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Journal  of  the 

Ropal  iKicroscoplcal  Socktp 

CONTAINING    ITS   TRANSACTIONS    AND    PROCEEDINGS 

AND 

A    SUMMARY    OF   CURRENT    RESEARCHES    RELATING    TO 

zooi-.o<3-""5r     .A-isriD     bot^^ist^ 

(principally   Invertebrata    and   Cryptogamia) 

3S/i:iG:ROsao:p"2',    <Ssc. 

EDITED   BY 
CHARLES    SINGER,  M.A.  M.D.  F.R.C.P. 

\VI  III    TME    ASSISTANCE   OF    THE    PUBLICATION    COMMITTEE    AND 

J.  ARTHUR  THOMSON,  M.A.  LL.D.  A.  N.   DISNEY,  M.A.  B.Sc 

Regius  Professor  of  Natural  History  in  the  F.IAN   G.RAWLINS 

University  of  Aberdeen 

FELLOWS    OF    THE    SOCIETY, 

A.  B.  RENDLE,  M.A.  D.Sc.  F.R.S.  F.L.S. 

Keeper,  Department  of  Bo  tatty,  British  Museum 

AND 

RALPH  ST.  JOHN  BROOKS, 
M.A.  M.D.  D.P.H.  D.T.M.  &  H.  (Camb.) 


Minimis  partibus,  per  totum  Naturae  campum,  certitude  omnis  innititur 
qiias  qui  fugit  pariter  Naturam  fugit.— Zm«^«j-. 


FOR      THE      YEAR 
1920 


TO  BE  OBTAINED  AT  THE  SOCIETY'S  ROOMS 

20    HANOVER    SQUARE,    LONDON,  W.i 
OF   Messrs.    WILLIAMS  &  NORGATE,   14    Henrietta    Street,    London,   W.C.2 
AND  of  Messrs.  DULAU  &  CO.,  Ltd.,  34  Margaret  Street,  London,  W.i 


^l-^< 


CONTENTS 


TRANSACTIONS  OF   THE  SOCIETY. 

PAGE 

I. — Studies  oj^  the  Binucleate  Phase  in  the  Plant-Cell. 
By  iVgnes  Arber,  D.Sc,  F.L.S.,  Fellow  of  Newnham 
College,  Cambridge.     (One  Plate  and  two  text-figs.)         .  .         1 

11. — On  Multinucleate  Cells  :  An  Historical  Study  (1H79- 

1919).     By  Pvudolf  Beer  and  Agnes  Arber         23 

III.— Ox  the  Relationship  between  the  Formation  of  Yolk 
AND  the  Mitochondria  and  Golgi  Apparatus  during 
OoCxENESiS.  By  J.  Bronte  Gatenby,  B.A.,  B.Sc,  D.Phil., 
Senior  Demy,  Magdalen  College,  Oxford,  Lecturer  in 
Cytology,  University  College,  Oxford,  London  ;  and  J.  H. 
Woodger,  B.Sc,  Assistant  in  Zoology  and  Comparative 
Anatomy,  University  College,  London.  (One  Plate  and 
fom-  text-figures) 129 

lY. — Method  for  the  Demonstration  of  the  Goloi  Appa- 
ratus IN  Nervous  and  other  Tissues.  By  C.  Da  Fano, 
M.D.,  I/.D.  on  Morbid  Anatomy,  University  of  Pavia 
(Italy),  F.Pt.M.S.,  Lecturer  on  Histology,  King's  College, 
University  of  London.     (One  Plate) 157 

Y.— On  Acari  from  the  Lungs  of  Macacus  rhesus.  By  F. 
Martin  Duncan,  F.R.M.S.,  F.R.P.S.,  F.Z.S.  (One  Plate 
and  two  text-figures) . .     163 

YL— The  Lycopodium  Method  of   Quantitative  Microscopy. 

By  T.  E.  Wallis,  B.Sc.  (Lond.),  F.I.C.     (One  text-figure)       169 

YII. — Notes  on  Fresh- water  Ciliate  Protozoa  of  India. 
By  B.  L.  Bhatia,  M.Sc,  F.Z.S.,  F.R.M.S.,  Assistant  Pro- 
fessor of  Zoology,  Government  College,  Lahore         . .      . .     257 


\  U(c45 


IV  CONTENTS. 


PAGE 


VIII. — The  Problem  of  Synapsis.  By  Lancelot  Hogben,  M.A., 
B.Sc,  Lecturer  in  Zoology,  Imperial  College  of  Science 
and  Technology 269 

IX. — Further  Notes  on  the  Oogenesis  and  Fertilization 
OF  Grantia  compressa.  By  J.  Bronte  Gatenby,  B.A., 
B.Sc,  D.Phil.  (Oxon.),  F.RJI.S.,  Lecturer  in  Cytology 
and  Senior  Assistant  in  Zoology,  University  College, 
London,  and  Senior  Demy,  Magdalen  College,  Oxford, 
(One  Plate) 277 

X.— A  Universal  Microtome.     By  Sir  Horace  Darwin,  F.R.S., 

and  W.  G.  Collins.     (Four  text-figures) 283 

XI. — Preliminary  Tests  on  the  Homologue  of  the  Golgi 
Apparatus  in  Plants.  By  A.  H.  Drew,  D.Sc,  F.R.M.S. 
(Four  text-figures)      295 


SUMMARY   OF  CURRENT  RESEARCHES  IN- 

BOTANY, 

MICROSCOPY,  AND 

INDUSTRIAL    PROCESSES. 


NOTICES    OF   NEW    BOOKS. 


PROCEEDINGS    OF  THE    SOCIETY. 


THE  REPORT  OF  THE  SYMPOSIUM 

Held  in  January,  1920, 

pp.  1-260,  at  the  end  of  the  volume. 


/ 


Any   Omissions    or    Errors    in   this    List   should    be   notified    to   the 

Secretary. 


LIST    OF    FELLOWS 

OF   THE 

Ropal  microscopical  Socictp 

{Corrected  to  September  SOfh,  1920.) 


ORDINARY    FELLOWS. 


*   Fellows  loho  have  compounded  for  their  Annual  Subscriptions. 

Elected. 

1892  Abraham,  Rev.  Nenclick. 

cjo  Miss  F.  Abraham,  Sherwood's  Buildings,  Maritzburg, 
Natal,  S.  Africa. 
1894     Abrams,  Albert,  M.D. 

2135.  Sacramento-street,  San  Francisco,  Gal.,  U.S.A. 

1919  Abusbady,  Ahmed  Zaby,  L.M.S.S.A. 

21,  Cairn-avenue,  Ealing,  W.6 

1893  Adair,  Thomas  Stewart,  M.D.,  CM.,  Edin. 

Storthes-Hall-asylum,  KirJcburton,  near  Huddersfield. 
1918     Adams,  Basil. 

Lynwood,  Cromwell-road,  Beckenham. 
1893     Adams,  Charles,  M.D. 

33,  Bellevue-place,  Chicago,  III.,  U.S.A. 

1920  Adams,  H.  V. 

1893     Adams,  James. 

Comely-park,  Dunfermline,  N.B. 
1918     Agate,  Charlton  S.,  B.Sc,  etc. 

Engineering  Staff,  Marconi  Works,  Chelmsford. 
1892     Aikin,  Charles  Edmund,  M.R.C.S.,  L.S.A. 

Pentre  Felin,  Llangollen,  Denbighshire,  North  Wales. 
1918     Ainslie,  Maurice  Anderson,  Instructor  Commander,  H.N. 

Boyal  Naval   College,  Greenwich,  S.E.IO,  and  8,  Wood- 
ville-road,  Blackheath,  S.E.S 
1906     Aitken,  Henry  James. 

Lauresdale,  Wellington-road,  Edgbaston,  Birmingham. 

[1] 


2  ROYAL   MICROSCOPICAL   SOCIETY. 

Elected. 

1914  Akehurst,  Sydney  Charles. 

60,  Bowes-road,  Palmers  Green,  N.IS 
1913     Allan,  Mark  J. 

"  Ludgersliall,''  Roslyn-street,  Middle  Brighton,  Victoria, 
Australia. 
1912     Allen,  George  Morris. 

"  Milhnrn,'"  Bury-street,  Euroa,  Victoria,  Australia. 

1905  *Allis,  Edward  Phelps^  Jan.,  C.E.,  LL.l).,  F.L.S.,  F.Z.S. 

Palais  Carnoles,  Menton,  Alpes  Maritimes,  France. 

1919  Alston,  Richard  A.,  A.M.C.T. 

4,  Golley -street,  Old  Trafford,  Manchester. 

1920  Altof,  Mrs.  Bertlia. 

95,  Castlewood-road,  Stamford-hill,  N. 
]  906     Andrews,  Cuthbert  Otto  Ralph. 

47,  Red  Lion-street,  Holhorn,  W.C.I 
1912     Angus,  Herbert  Francis. 

39,  Empress-avenue,  II ford,  Essex. 

1906  Antliony,    Charles,    F.R.S.E.,    M.Tnst.C.E.,    M.Am.Soc.C.E., 

F.R.A.S.,  F.R.Met.Soc.,  F.C.S. 

Casilla  de  Correo  149,  Bahia  Blanca,  Argentine  Bepuhlic, 
South  America. 

1911  Armstrong,  Frank. 

78,  Deansgate,  Manchester. 

1912  Ash,  Lieut.  Edward  C. 

Dallinqhoo  Hall,  Wickham  Market,  Suffolk. 
1909     Ashe,  Albert. 

55,  Warrior-square,  Southend-on-Sea. 

1916  Ashworth,  Fred,  F.R.Met.Soc,  M.S.C.I. 

15,  Woodlea,  Waterfoot,  near  Manchester. 

1917  Atkinson,  Ernest,  A.M.I.L.E.,  M.I.  (Sj  S.I. 

6,  Bank-road,  Workington. 

1915  Attridge,  Alfred  J, 

Ivydene,  Bhine-road,  Sea  Point,  Ga2)e  Town,  S.  Africa. 
19r>     Aubin,  Percy  Adrian. 

10,  Elizaheth-place,  St.  Helier,  Jersey. 
1912     Audas,  James  W.,  F.L.S. 

^^Engoivraj"  105,  Punt-road,  St.  Kilda,  Melbourne,  Victoria. 


1920     Baguall,  Richard  Siddoway,  F.R.S.E.,  F.L.S. 

Jiydal  Mount,  Blay don-on- Tyne. 
1909     Bagshaw,  V/ alter. 

17,  Hereford-road,  Harrogate. 
1894  *P>ailey,  Charles,  M.Sc.;  F.L.S. 

Sandhurst,  St.  Mary  Church,  Torquay. 
1908     Baird,  Tliomas  Stewart,  F.I.O.,  F.S.M.C,  D.B.O.A. 

54,  St.  Enoch-square,  and  34-36,  Queen-street,  (ilasgotv. 
1915     Baker,  Arthur. 

Baveniutrt  Lodge,  Pelham-road,  Gravesend,  Kent. 


ORDINARY    FELLOWS.  3 

Elected. 

1885      Baker,  Frederick  Henry,  F.L.S. 

167,  Hoddle-street,  Bichmond,  Victoria,  Australia. 

1894  Baker,  Frederick  William  Watson. 

313,  High  Holborn,  W.G.l 

1914  Baker,  Wilfred  E.  Watson. 

313,  High  Holborn,  W.Cl 
1882     Bale,  William  Mouutier. 

83,  Walpole  street,  Kew,  Victoria,  Anstralia. 

1895  Barnard,  Joseph  Edwin,  F.Inst.P. — Hon.  Secretary. 

Park  View,  Brondesbury-parh,  N.W ,  ami  Boyal  Societies 
Club,  St.  James  s-street,  S.  W.  1 
1913     Barratt,  Thomas  Franklin. 

Bellmoor,  Hampstead  Heath,  N.  W. 
1913     Barton,  Norman  V. 

10,  Exhibition-road,  S.  Kensington,  S.W.7 

1874     Bate,  George  Paddock,  M.D.,  F.R.C.S.E.,  M.R.C.S.,  Surgeon- 
Lieut. -Col.  Army  Medical  Beserve. 

2,  King  Edward-road,  Hackney,  E.9 
1920     Bates,  George  Frederick,  B.A.,  B.Sc. 

66,  Craigie-road,  Perth. 
1918     Baxter,  Charles,  C.E. 

Cleveland-house,  Bradford-road,  Shipley. 
1913     BayliPS,  Professor  William  Maddock,  D.Sc,"  F.R.S. 

St.  Cuthbert's,  West  Heath-road,  Hampstead,  N.  PP.3 
1899     Beale,  Peyton  Todd  Bowman,  F.li.C.S 

"  Oaklands,"  Hythe,  Southampton. 

1915  Beattie,  William. 

8,  Lower  Grosvenor-place,  S.W.I 
1885  *Beck,  Conrad,  C.B.E. 

68,  Cornhill,  E.C.S 
1899     Beck,  Horace  Courthope. 

Lister  Works.  Weedington-road,  Kentish  Town,  N.W.6 
1879  *Bell,   Francis   Jeffrey,    M.A.,   F.Z.S.    Emeritus   Professor  of 
Comparative  Anatomy  and  Zoology  in  Kings  College,  London, 
Corresponding  Member  Linnean  Society  of  New  South  Wales, 
Honorary  Member  Manchester  Microscopical  Society. 

11,  Aberdeen-chambers,  43,  Great-Marlborough-street,  W.\ 
1910     Berridge,  Miss  Emily  Mary,  D.Sc,  F.L.S.       . 

7,  The  Knoll,  Beckenham,  Kent. 

1918  Berry,  John  Leslie. 

151a,  New-street,  Burton-on-Trent. 
1913     Bestow,  Charles  Horton. 

Melford-house,  Upper  Clapton,  N.E. 

1919  Bhatia,  Bihari  Lai,  M.Sc,  F.Z.S.,  Professor  of  Zoology. 

Department  of  Zoology,  Government  College,  Lahore,  India. 
1912     Billinghurst,  Humphrey  Godwin. 

76,  Lebanon-gardens,  Wandsworth,  S.W.IS 
1918     Blackmore,  Herbert  George. 

23,  Gloucester-gardens,  W.2 

A  2 


4  ROYAL   MICROSCOPICAL    SOCIETY. 

Elected. 

1899     Bliss,  J. 

Boar  Bank  Hall,  Grange-over-Sanda,  Lancashire. 
1903  *Blootl,  Maurice,  M.A.,  F.C.S. 

51,  Winchester-avenue,  Kilhurn,  N.W.6 
1916     Bocock,  0.  Hanslope,  F.E.S. 

The  Elms,  Ashley,  Newmarket. 
1918     Bois,  Sir  Stauley. 

12,  Fenchurch-street,  E.G. 

1889  Booth,  Miss  Mary  Ann. 

60,  Dartmouth-street,  Springfield,  Mass.,  U.S.A. 
1862     Borradaile,  Charles. 

3,  Norfolk-terrace,  Brighton. 

1913  Boyce,  David  E. 

Greenwood-park,  Durban,  Natal,  South  Africa. 

1914  Boyer,  Charles  S.,  A.M. 

6140,  Goliimhia-avenue,  Philadelphia,  Pa.,  U.S.A. 

1910  Brace  well,  Geoffrey  Alfred. 

17,  Farcliffe-terrace,  Bradford,  Yorkshire. 

1918  *Bradshaw,  Thomas  Buller,  J.P. 

Millways,  Launceston,  Cornwall. 

1914  Brand,  Felix. 

37  d;  38,  Hatton-garden,  E.G.I 

1915  Brewster,  Frank. 

Criminal    Intelligence    Office-,    Simla,    India,    and    The 
"  Dingle,"  Simla. 

1890  Briant,  Lawrence,  F.C.S. ,  Mem.  Soc.  Public  Analysts. 

24,  Holborn-viaduct,  E.G.I 
1905     Bridge,  John  William. 

Brewer-street,  Maidstone. 
1908     Brooks,  Theodore,   15. A.  (Cantab.),  F.R.G.S.,  3Iember  of  the 
Academy  of  Natural  Sciences,  Philadelphia,  U.S.A.,  Member 
of  the  Entomological  Society  of  America. 

Central  Caracas,  Caracas  Sanha,  Clara  Province,  Cuba. 
1887     Browne,  Edward  Thomas,  F.Z.S. 

Anglefield,  Berkhampstead,  Herts. 

1911  Browning,  Sidney  Howard,  L.R.C.P.,  M.R.C.S. 

The  Station  Hospital,  Jubhulpore,  India. 
1920     Brumwell,  Harold. 

Bengal  Tanneries,  Ltd.,  Hide-road,  Dock  Junction  P.O., 
Calcutta,  India. 

1919  Brunelle,  Major  (ieorge  C,  Ph.C,  M.D. 

200,  Chester  Pike,  Glen  Olden,  Pa.,  U.S.A. 

1920  Bull,  Henry  H.  J. 

Albion-cottage,  Haddenham,  Bucks. 

1912  Bnllamore,  Geo.  W. 

Walden-cottage,  Albury,  Herts. 
1920     Bullock-Wchster,  Hoy.  Canon  (ieorgo  II. 

17,  Gordon-square,  W.G. 
1919      P.umsted,  William  Frederick. 

16,  Conway-avenue,  Toronto,  Canada. 


ORDINARY   FELLOWS.  5 

Kkcted. 

1920     Burgess,  Arthur  Savell,  M.A.,  M.B.,  B.Ch. 

ejo  Provincial  Medical  Officer,  Kumasi,  Gold  Coast,  West 
Africa. 
1918     Burke,  George  Edwin. 

Box  476,  Colorado  Sjjrings,  Colorado. 
1913     Burus,  Nesbitt,  B.A.,  M.B,  B.Ch. 

The  Lodge,  Highhridge^  Somerset. 


1910     Caird,  William  John. 

Schoolhouse,  SandJiaven,  Fraserburgh. 
1892     Cale,  (Jeorge  W.,    M.D.,   Chief  Surgeon,  St.  Louis  and   San 
Francisco  Railroad  Company. 

San  Francisco  Hosjntal,  4960,  Laclede-avenue,  St.  Louis, 
Mo.,  U.S.A. 
1920     Cannon,  Herbert  Graham,  B.A.,  F.Z.S. 

Zoology  Department,  Imperial    College   of  Science   and 
Technology,    and    62,   Stockwell-pjark-road,    Stochwell, 
S.W.9 
1913     Capell,  Bruce  J. 

10,  Castelnau,  Barnes,  S.W.IS 

1891  earlier,  Edraond    William    Wace,  M.D.,  B.Sc,  Professor  of 

Physiology,  Mason  University  College,  Birmingham. 

Morningside,  Granville-road,  Dorridge,  near  Birmingham. 
1880  *Carruthers,  William,  Ph.D.  F.E.S.,  F.L.S.,  F.G.S. 
44,  Central-hill,  Norwood,  S.E.ld 

1910  Carter,  John  Arthur,  Assoc.M.I.M.E. 

6,  Temple-road,  Stowmarket,  Suffolk. 
1861  *Cattley,  Edward  Abbs. 

Officer  Str'.  5,  lodg.  15,  St.  Petersburg,  Russia. 
1918     Cattley;  Major  Eobert,  M  B.,  CM.,  B.Sc.,  etc. 

43,  Main-avenue,  Heicorth,  York. 

1903  Chapman,  Alfred  Chasten,  F.R.S.,  F.I.C.,  F.C.S. 

8,  Duke-street,  Aldgate,  E.C.3 

1892  Chapman,  Frederick,  A.L.S.,  Palseontologist    to   the  National 

Museum,  Melbourne;  Hon.  Palaeontologist,  Geological 
Survey,  Victoria  ;  President.  Microscopical  Society,  Victoria; 
Lecturer  and  Demonstrator  in  Pal  deontology,  Melbourne 
University. 

'  Croham     Hurst,"     Threadneedle-street,    Balioyn,    near 
Melbourne,  Victoria,  Australia. 

1911  Cljatwin,  Charles  Panzetta. 

32,  Cassland-road,  Thornton-heath,  Surrey. 
1909     Cheaviu,  Captain  W.  H,  S.,  F.C.S.,  F.E.S. 

Middlesex  Medical  College,  Berners-street,  W.l 

1904  Cheshire,  Professor  Frederic  John,  C.B.E.,  F.Inst.P.,  Director 

of  Technical  Optics,  hnperial  College  of  Science  and  Tech- 
nology, South  Kensington,  S  W.l 

23,  Carson-road,  West  Dulwich,  S.E. 


b  ROYAL   MICROSCOPICAL   SOCIETY. 

Elected. 

1885     Clark,  Joseph. 

Hind  Hayes,  Street,  S.O.,  Somerset. 
1917     Clcmence,  Walter,  M.T.Mecli.E. 

1,  ParJc-ferrnce,  Nottingham. 
1914     Clibborn,  Lt.-Col.  JoLd,  C.I.E.,  B.A. 

87,  Victoria-street.  S.W.I 

1907  Clowes,  William  Afcliibald,  F.Z.S. 

Duke-street,  Stamford-street,  S.E.I 
1919     Coghill,  Douglas. 

The  Dominion  Lahoratory,  Sydney-street,  Wellington,  New 
Zealand. 
1905     Cole,  Thomas  Skelton. 

Westhury,  7,  Endcliffe-crescent,  Sheffield. 

1908  Connell.  John  Gibson. 

Biology  Department,  Glasgow  Provincial  Training  College^ 
Gowcaddens-street,  Glasgow,  and  22,  Bellwood-street, 
Glasgow. 

1919  Constantine,  Rev.  Allan  W.,  B.A. 

Grafton  Lodge,  Muizenhurg,  Gape  Peninsula^  South 
Africa. 

1920  Cooke,  William  Edmuucl,  M.D.,  F.R.C.P.,  D.P.H. 

Public  Health  Department,  Town  Hall,  Bermondsey,  S.E. 
1875     Cowau,  Thomas  William,  F.L.S.,  F.G.S. 

Sutherland-house,  Glevedon,  Somerset. 
1881     Creese,  Edward  James  Edgell,  F.Z.S. 

3,  Gos well-villas,  London-road,  Newbury,  Berks. 
1884  *Crisp,  Lady  Catherine. 

5,  Lansdowne-road,  Notting-hill,  W. 
1891     Crowther,  Henry. 

Curator,  The  Museum,  Leeds. 
1919     Curtios,  Charles  Lees. 

244,  High  Holborn,  W.G.I 
1913     Cuzner,  Edgar. 

36,  Trothy-road,  Bermondsey ,  S.E.I 


1920     Da  Fano,  Corrado,  M.I).,  L.D. 

King's  College,  Strand,  W.C"! 

1914  Daniels,  Major  William  Cooke. 
1916     Duvies,  Alfred  T. 

Avon-house,  Keynsham,  near  Bristol. 
1908     Davies,  Daniel. 

c/o  Messrs.  McGruer,  Davies  d  Co.,  Timarn,  New  Zealand. 

1915  Denne,  Mark  Thomas,  O.B.E. 

74,  Hornsey-lane,  Highgate,  A7.6 
1885     Do  Witt,  William  (i. 

88,  Nassau-street,  Neio  York,  U.S.A. 
1904     Dibdin,  William  Josej.li,  F.I.C.,  F.C.S. 

31,  IdmistoH-road,   West  Norwood,  S.E.27 


OHDINARY    FELLOWS.  7 

I<:iected. 

1918     Digby,  Miss  Lcttice. 

Kings  Ford,  Colchester. 
1913     Diusley,  Lieut.  Alfred,  ll.A.O.C. 

c/o  Sir  C.  B.  McGrigor,  Bart.,  d'  Co.,  29,  Panton-street, 
Haymarhet,  S.  W. 
1886     Disney,  Alfred  Normau,  M.A.,  B.Sc. 

14.  Wilton-crescent,  Wimhledon,  S.W.19 

1918  *  Dixon,  Miss  Annie. 

43,  Pine-road,  Didsbury,  Manchester. 
1896     Dixon,  Walter. 

38,  Bath-street,  Glasgow. 
1892     Dixon-Nuttall,  Frederick  Kichard. 

Ingleholme,  Eccleston-parh,  near  Prescot,  Lancashire. 

1919  Dovey,  Ernest  Roadley,  A.R.C.S. 

Government  Laboratory,  Hongkong,  China. 
1907     Dowdy,  Sidney  Ernest,  M.P.S. 

1,  Belton-villas,  Hill-road,  Dovercourt,  Essex. 

1918  Downes^  Harold,  M.B.,  CM.,  L.R.C.P.,  etc. 

Ditton  Lea,  Ilminster,  Somerset. 

1919  Drescber,  Theodore  Bauscli. 

149,  Westminster-road,  Bochester,  N.Y.,  U.S.A. 
1919     Drew,  Aubrey  H.,  D.Sc. 

Imperial    Cancer    Besearch    Fund,    8-11,    Qaeen-sqiiare, 
W.C.I 

1910  Duuiat,  Frank  Campbell. 

26,   Standard  BanJc-chamhers,  Johannesburg,   Transvaal, 
South  Africa. 
1894     DuDcan,  Cecil  Cooke,  F.I.C.,  F.C.S. 

The  County  Chemical  Laboratory,  Shire  Hall.   Worcester. 

1911  Duncan,  Francis  Martin,  K.ILP.S.,  F.Z.S. 

37a.  Belsize-square,  N.W.3 
1919  *Dunn,  Gano,  A.I.E.E. 

J.  G.  White  Engineering  Corporation,  43,  Exchange- place. 
New  York,  U.S.A.,  and  117,  West  5Sth  Street,  New  York. 

1919  Dimu,  Ke.Ljinald. 

90,  Lome-road,  Clarendon-yark,  Leicester. 

1920  Durand,  Alexandre. 

16,  Bue  Casimir  Delavigne,  Havre,  France. 


1910     Earland,  Arthur. 

Aviemore,  34,  Granville-road,  Watford,  Herts. 
1907     Eastbam,  John  VV.,  B.Sc.  (Edin.). 

Vernon  British  Columbia. 
1912     Edvvardes,  Seabury. 

Burma  Excise  Department,  Moulmein,  Lower  Burma. 
1899     Elliott,  Oliver  Thomas,  M.P.S.,  Pb.C. 

c/o  Messrs.  Philip  Harris  d  Co.,  Edmund-street,  Birming- 
ham, and  The  Bowans,  Lloyd's-street.  Small  Heath. 


8  ROYAL   MICROSCOPICAL    SOCIETY. 

Elected, 

1919     Elliott,  Thomas  Gifford,  F.I.C.,  F.C.S. 

Besearch  Laboratory,  Hecla  Works,  Sheffield,  and  Hillcots, 
Park  Edge,  Hathersage,  near  Sheffield. 
1907     Ewell,  Marshall  D.,  M.D. 

749,  Tate-aveime,  Memphis,  Tenn.,  U.S.A. 
1897     Eyre,  John  William  Henry,  M.D.,  M.S.Durh.,  D.P.H.,  F.ll.S.E. 
— President,    Professor    of    Bacteriology    in   the    London 
University. 
Bacteriological     Laboratories,     Guy's     Hospital,    S.E.I. 
62,  Wimpole-street,  W.l,  and  The   Warren,  Tulse-hill, 
S.W.2 


1883  *rawcett,  John  Edward. 

Heron-court,  Far7iham,  Knaresborough. 
1883     Fellows,  Charles  Sumner. 

107,    Chamber    of    Commerce    Minneapolis,    Minnesota, 
U.S.A. 
11)17     Fendick,  Ernest  A. 

Wicklewood,  22,  Finedon-road,  Wellingborough. 
190';'     Ferguson,  Arthur  Duncan. 

British  Guiana  Bank,  Gerrgetown,  Demerary.  British 
Guiana. 
1904  Fischer,  Charles  Edward  Max,  M.D.,  Associate  Professor  of 
Biology,  Histology,  and  Embryology,  College  of  Physicians 
and,  Surgeons  of  the  University  of  Illinois,  Memb.  Amer. 
Microscopical  Soc,  Memb.  of  the  Amer.  Assoc,  for  the 
Advancement  of  Science. 

Suite  1320-2,  25,  E.  Washington-street,  Chicago,  III,  U.S.A. 
1866  *Fitch,  Frederick  George. 

34,  Hamilton-terrace,  N.W.S 
1902     Flatters,  Abraham. 

Syddal-cotiage,  Bramhall,  Cheshire. 
1919     Fleurct,  John  B. 

47,  W(dsingh<i)u-road,  Hove. 
1917      Fotlieringham,  William,  J.P. 

Hillhead,  Lerwick,  Shetland. 
1915     Francis,  Miss  Lilian  Angela. 

9,  Henrietta-street,  Cavendish-square,  W.l 


1912     Gadd,  Arthur. 

115,  Atwood-road,  Didsbury,  near  Manchester 
1918     Garbutt,  Ernest  Chalders. 

York-hoiim,  St.  Ives,  Cornioall. 
1902     Gardner,  William. 

292,  Hollo loay-road,  NJ 


ORDINARY   FELLOWS.  9 

Elected. 

1911  Garforth,  Sir  William  Edward,  LL.D. 

Snydale  Hall,  Normanton. 

1919  Garnett,  John  Beubow. 

309,  Oxford-road,  Manchester.   . 

1920  Gatenby,  James   Broute,  B.A.,  B.Sc,  l).Pbil.(Oxorj),  Lecturer 

in  Cytology. 

University  College,  Gower  Street,  W.C.I 
1920     Gauntlett,  H.  Leon,  M.R.C.S.,  L.K.C.P. 

46,  Hotham-road,  Putney,  *S^.TF.15 
1905     Gettys,  Henry  B.,  M.D. 

3526,  Washington-avenue,  St.  Louis,  Mo.,  U.S.A. 
1910     Gibbs,Miss  Lilian  S.,  F.L.S. 

22,  South-street,  Thurloe-square,  S.  W. 
1902     Gibson,  Joseph. 

Elmfield,  Psalter-lane,  She^eld. 

1919  Gibson,  William  H.,  M.B.E.,  D.'Sc. 

YorJc'Street  Flax  Spinning  Co.,  Ltd.,  York-street,  Belfast. 
1892     Gifford,  James  William. 

Oaklands,  Chard,  Somerset. 
1899     Gleadovv,  Frank. 

Bakeham-house,  Englefield  Green,  Surrey. 

1912  Glover,  Samuel. 

Olive  Mount,  St.  Ann's,  St.  Helens,  Lancashire. 
1910     Gooding,  Henry  Cornish. 

Ipswich-street,  Stoiomarket,  Suffolk. 

1908  Gordon,  David. 

Care  of  D   &  W.  Murray,  Ltd..  Adelaide,  South  Australia. 

1909  Gordon,  Fred.  William. 

61,  Broadway,  New  York  City,  U.S.A. 
1885     Gordon,  Rev.  J.  M.,  M.A. 

7,  Moreton-gardens,  S.  W.b 

1920  Graham,  Joseph,' B.Sc. 

Glen  Hurst,  Corhridge-on-Tyne. 
1919     Grant,  Ernest  Henry. 

Britannia-villas,  Cheshim,  Bucks. 
1904     Griffiths,  Waldron. 

1,  Cecily-hill,  Cirencester. 

1910  Grundy,  Ja,ines. 

96,  Teignmouth-road,  Crickleivood,  N.  W.2 
1912     Gurrin,  Gerald  Francis. 

59,  Holhorn-viadiict,  E.C.I 
1902     Giissow,  Hans  Theodore. 

Chief,  Division  of  Botany,  Dominion  Experimental  Farm, 

Ottawa,   Canada,  and   43,  Fairmo ant-avenue,   Ottawa, 

Canada 

1910     Gwyune-Vaughan,    Dame    Helen    Charlotte    Isabella,    D.Sc, 

F.L.S. ,  Head  of  the  Department  of  Botany,  Birkbeck  College, 

E.C.4: 

93,  Bedford-court -mans  ions,  W.C.I 


10.  ROY Al /"microscopical   SOCIETY. 

Elected. 

1919  Hadlield,  Sir  Kobert  A.,^^Bart.,  D.Sc,  F.R.S.,  F.lnst.P. 

22,  Carlton -house-terrace,  S.W.I 
1893     HJigler,  Elmer  Ellsworth,  M.D. 

The  Edgier  Building,  401,  East  Gapitol-avcnue,  Spring- 
field, Illinois,  U.S.A. 
1914     Halford-Boberts,  Stanley. 

Edenholme,  East  Boldott,  near  Newcastle-on-Tyne^ 
1912     Hall,  Rev.  C.  A. 

"  Woodburnj"  Clynder,  Dumbartonshire. 

1920  Hall,  T.  D.  Tuton. 

Technical  School,  Bochdale. 
1885     Hallam,  Samuel  Eobinson,  L.S.A.(Loiid.),  L.M.S.S.A. 

586,  Old-Kent  road,  S.E.I 
1920     Hallowes,      Kennett      Knight,      M.A.,      F.G.S.,      A.R.S.M., 
A.Inst.M.M.,    Assistant    Superintendent,   H.M.    Geological 
Survey  of  India. 

27,  Chowringhill,  Calcutta,  India,  and  50,  Begenfs-park- 
road,N.W.- 
1919     Hampshire,  Percy. 

5,  Kensington-terrace,  Leeds. 
1882  *Hanaman,  Charles  Edward. 

103,  First-street,  Troy,  N.Y.,  U.S.A. 
1874  t Hanks,  Professor  Henry. 

1124,  Greenwich-street,  San  Francisco,  California,.  U.S.A. 

1914  Harding,  H.  Bertram,  F.L.S. 

77,  Hannah-street,  Forth,  Glam. 
1905     Hardy,  Alfred  Douglas,  F.L.S. 

State    Forests    Department,     Melbourne,     Yarra  -  langi, 
Studley-avenue,  Keiv,  Melbourne,  Victoria,  Australia. 
1905     Harris,  Charles  Poulett,  M.D.  (Lond.),  M.K.C.S.,  L.R.C.P. 

192,  Lower  Addiscombe-road,  Croydon,  S.E. 
1919     Hari)er,    Captain    Raymond     Sydney,    M.R.C.S.,     L.R.C.P., 
ILA.M.C. 

4,  Adelaide-crescent,  Hove. 
1912     Harrison,  James. 

1915  Hartland,  Albert  J. 

22,  Cambridge-road,  King  Williams  Town,  Cape  Province, 
S.A. 
18G7  *Hartreo,  William,  Associate  Inst.  C.E.,  F.Z.S. 

Havering,  Tunbridge  Wells. 
1911     llartridgc,  Hamilton,  M.A.,  M.D. 

King's  College,  Cambridge. 
1919     Harvey,  John  Henry,  F.C.S. 

Bavensworlh,  Llantarnam,  Newport,  Mon. 
1897     Hassall,  John,  M.D.,  M.R.C.S.,  iSic. 

Inglesidc,  Mouldsworth,  near  Chester. 
1910     Hatoly,  Jolm  Craig. 

70,  Board  of  Trade,  Chicago,   III.,  and  Galewood,  Lake 
Geneva,  Wiss.,  U.S.A. 

t  Correspondiug  Fellow. 


ORDINARY    FELLOWS.  11 

Elected. 

1919  Hawksley,  Cliarles  Worth  in  gton. 

83,  Wigmore-street,  W.l,  and  13  Alma-square,  St.  Johns- 
wood,  N.W.S 

1916  Hazeldinc,  Frederick  James. 

Barnfield,  South  Godstone,  Surrey. 
1909     Heath,  diaries  EmauueJ. 

178,  Loughhorough-road,  Brixton,  S.W.9 

1909  Heath,  Ernest. 

Clidga,  Sennen,  Cornwall. 
1899     Heaton,  John,  F.C.S. 

SouthcUffe,  Boher,  Sunderland. 

1917  Hensman,  Leonard  Newton,  Ph.C,  M.P.S. 

2,  Killarney-road,  Wandsworth,  S.W.IS 
1889     Hepworth-Collins,  Walter,  F.G.S.,  F.C.S. 

Junior  Constitutional  Club.  Piccadilly,  W. 
1891     Heron -Allen,     Edward,     F.E.S.,     F.L.S.,     F.G.S.,     F.Z.S., 
M.R.I.A.,  etc. 

33,  Hamilton-terrace,  N.  Pr.8,  and  "  Large  Acres"  Selscy- 
hill,  Sussex. 

1910  Hewlett,  Richard  Tanner,  M.D.,  F.R.O.P.,  D.P.H. 

Prdfessor   of  Bacteriology,    Bacteriological    Laboratory, 
King's-college,   Strand,    W.C,  and    12    Colinette-road . 
Putney,  S.W.15 
1904     Hill,  Cyril  Francis,  M.Inst.M.M. 

Druids-croft,  Kinnaird-avenue,  Bromley,  Kent. 
1881  *Hill,  Joseph  Alfred,  F.L.S. 

St.  Bees,  Nortliumberla.7id-road,  Leamington. 
1906     Hiscott,  Thomas  Henry. 

16,  Woodville-road,  Ealing,  W.6,  and  5,  Stone-huildings, 
Lincoln's  Inn,  W.C. 

1917  Hitchins,  Alfred  Bishop,  Ph.D.,  D.Sc,  A.M. 

c/o  AnsGo  Co..  Besearch  Laboratory,  Binghampton,  N.Y., 
U.S.A. 

1920  Hornyold,  Professor  Alfonso  G.,  D.Sc. 

Professor  Agregardo  of  the  Marine  Biological  Laboratory, 
Porto-Pi,  Palma  de  Mallorra,  Spain. 

1918  Hort,  Edward  C,  F.R.C.P. 

8,  Harley-street,  W.l 
1918     Hoseason,  William  Sandford. 

Dochmasters  Office,  Alexandra  Dock,  Bombay,  India. 
1891     Howard,  A.  Dashwood,  B.A.,  M.D.,  M.R.C.S.,  L.R.C.P. 

"  The  Corner,"  Hampton-hill,  Middlesex. 
1917     Howard,  Henry  J. 

94,  Bosary-road,  Thorpe,  Norwich. 
1894     Howard,  Capt.  Robert  Nesbit,  M.R.C.S.,  S.A.M.C. 

No.  2  General  Hospital,  Maitland,  near  Cape  Town,  S.A. 
1889     Huber,    Gotthelf    Carl.    M.D.,    Professor    of    Histology    and 
Embryology,  and   Director    of  the   Histological  Laboratory 
in  the  University  of  Michigan. 

1330,  Hill-street,  Ann  Arbor,  Mich.,  U.S.A. 


12  ROYAL    MICROSCOPICAL    SOCIETY. 

Elected. 

1918     Hughes,  Owen  Lloyd. 

Ael-y-Bryn,  Henllan,  Trefnaiit,  Denbighshire,  N.  Wales. 
1913     Hughes,  R.  H.  Pnllen. 

Alexander-house,  141,  Dvhe-street,  Southiiort. 
1911     Huish,  Charles  Henry. 

"  The  Limes,"  63,  London-road,  Bedhill,  Surrey. 
1913     Hurrell,  Harry  Edward. 

25,  Regent-street,  Great  Yarmouth. 


1867     Ingpen,  John  Edmund. 

21,  Wrotham-road,  Broadstairs. 
1920     Ireland,  William  Jabez. 

6,  Hurlingham-road,  Fulham,  S.W.iJ 
1903     Ives,  Frederic  Eugene,  F.R.P.S.,  Member  of  the  Franldin  Inst., 
N.Y.,    Camera    Club,    and   American    Microscopical    Soc, 
F.A.A.A.S. 

1327,  SjJruce-street,  Philadelphia,  Pa.,  U.S.A. 

1909  James,  Robert  Denley. 

1901     Johnson,  Charles  Harold,  M.D.,  CM.,  F.R.C.S.E. 

Weijanoke,  Kerang,  Victoria,  Australia. 
1912     Jolmston,  Thomas  Harvey,  M.A.,  D.Sc,  F.Z.S. 

Biology  Department,  The  University  of  Queensland,  Bris- 
bane, Australia. 
1918     Jonos,  Sir  Bertram  Hyde,  K.B.E. 

llgars,  Runwell,  Wichford,  Essex. 

1910  Jones,  William  Llewellyn. 


1885     Karop,  George  C,  M.R.C.S. 

Inniscorrig,  Belting e-road,  Heme  Bay. 
1910     Keeley,  Frank  J.,  B  S.,  E.M.,  Member  of  the  Council,  Academy 
of  Natural  Sciences,  Philadelphia;    Vice- Director,  Miner  (d- 
ogical  Section,  Academy  of  Natural  Sciences,  Philadelphia. 

Box  25,  Merion  Station,  Penna,  U.S.A. 
1919     Keen,  Percy  Frederick. 

64,  Fairholt-road,  Stamford-hill,  N.16 
1918     Kidd,  Robert  Hicks. 

Marlborough-house,  Neivbury,  Berks. 
1912     King,  Mrs.  Cecil. 

33,  Evelyn-gardens,  South  Kensington,  ^.1^.7 
1909     Kirby,  Edwin  Henry. 

The  Sungei  Bahru  Rubber  Estates,  Ltd.,  Home  Division, 
Alor  Gaja,  Malacca. 
1898     Kirknian,  Hon.  Thomas. 

Groftlands,  Esperanza,  Natal,  S.  Africa. 
1905     Kitchin,  Joseph. 

The  Mount,  53,  Parh-hill-road,  Croydon, 


ORDINARY  FELLOWS.  13 

Elected. 

1897     Klein,  Sydney  Turner,  F.L.S.,  F.K.A.S.,  F.E.S. 

Lancaster-lodge,  Kew-gardens,  Surrey. 
1913     Koch,  Victor  M.  E.* 

cjo  Messrs.  Martin  and  Tomkins,  61,  Margaret-street^  W.\ 


1920     Lamb,  Morris  Charles,  F.I.C. 

176,  Tower-Bridge-road,  S.E.I 
1915     Lambert,  Joseph. 

68,  Dartmouth-road,  Cricklewood,  N.W.2 

1918  Lancaster,  Henry  C. 

39,  Ladhroke-grove,  Holland-park,  W. 
1920     Lanc^eron,    Maurice    C.    P.,    Docteur    en    Medicine,    Chef  de 
Lnhoratoire  a  la  Faculie  de  Medicine  de  Paris. 
15,  Bue  de  VEcole  de  Medicine,  Paris,  France. 
1865     Lankester,  Sir  Edwin  Kay,  K.C.B.,  M.A.,  LL.D.,  F.R.S.,  F.L.S., 
F.Z.S.,  Bon.  Felloiv  of  Exeter  College,  Oxford. 
29,  Thurloe-place,  'S.W.7 
1887     Latham,  Miss  Vida  Annette,  M.D.,  D.D.S. 

1644,  Morse-avenue,  Bogers-park,  Chicaqo^  BL,  U.S.A. 

1919  Lauwers,  Walter  H.  M.,  F.P.S.L. 

77,  Bue  Lamoriniere,  Antwerp,  Belgium. 
1919     Lawrie,  Leslie  G. 

Stornoijcay,  Holden-road,  Kersal,  Manchester. 
1912     Lawson,  Peter. 

"  Jesmond,"  Nella-road,    Fulham-pal ace-road.   Hammer- 
smith, W.6 
1914     Leesou,  John  Rudd,  J.P.,  M.D.,  F.L.S.,  F.R.A.S. 

Clifden  House,  Twickenham. 
1919     Lissimoro,  Norman. 

Byde  Villa,  Dixon' s-green,  Dudley. 


1916     McEwen,  Alfred. 

Craig  Avel,  Tarrytown-cn-the- Hudson,  Neiv   York,  U.S.A. 
1894     Macintyre,  John,  M.B.,  CM.,  F.R.S.E. 

179,  Bath-street,  Glasgow. 
1919     Mackay,  Rev.  A.  F.  Gordon. 

Villamont,  Blue  Bidge  Springs,  Virginia,  U.S.A. 
1910     McKeever,  Frederick  Leonard 

P.O.  Box  210,  Penticton,  British  Columbia. 
1904     MacKenzie,  John  Ross,  F.C.S. 

Woodleiqh,  Sflhorne-road,  Barhourne,  Worcester. 
1884     McMurrich,  J.  Playfair,  M.A. 

Anatomical  Laboratory,    University  of  Toronto,   Toronto, 
Canada. 
1919     Macphenson,  Angus  Duncan,  M.B. 

18,  Cornwall-mansions,  Chelsea.  S.W.IO 


14  KOYAL   MICROSCOPICAL   SOCIETY. 

Elected. 

1884     Mainland,  George  Edward. 

14,  The  Norton,  Tenby,  South  Wales. 

1911  Mansfield-Aders,  Walter,  Ph.D. 

Zanzibar,  East  Africa. 
1909     Mapp,  Charles  Richard,  B.Sc. 

37,  Monfpellier-terrace,  Cheltenham. 
1920     Marchment,  Reginald  Henry. 

lu,  High-road,  Wood  Green,  N. 
189G     Marshall,  William  John. 

"  The  Nook,"  15,  Elms-road,  Dulwich  Village,  S.E. 

1904  Mason,  Francis  Archibald. 

29,  Franhland-terrace,  Leopold-street,  Leeds. 
1920     Maulik,  Professor  Samarendra,  M.A.,  F.Z.S. 

Zoological  Laboratorij,  The  University,  Calcutta,  Lidia. 
1892     Maw,  William  Henry,  C.E.,  F.R.G.S. 

18,  Addison-road,  Kensington,  W. 
1879  *Mercer,  A.  Clifford,  M.D. 

324,  Montgomery-street,  Syracuse,  NY.,  U.S.A. 
1899     Merlin,  Augustus  Alfred  Cornwallis  Eliot. 

31,  Cleveland-gardens,  West  Ealing,  Tr.l3 

1914  Merriman,  Captain  Arthur  D.,  M.A. 

27,  Ashmore-road,  King's  Norton,  Birmingham. 
1884     Mestayer,  Richard  Liron,  M.Inst.C.E. 

139,  Sydney-street,  West  Wellington,  N.Z. 
1901   *Methcny,  Samuel  Alexander  Sterrett,*B.A.,  M.D. 

617,  North  Forty-third-street,  Philadelphia,  Pa.,  U.S.A. 
1877     Michael,  Albert  Davidson.  F.L.S.,  F.Z.S.,  F.R.H.S. 

.     The  Warren,  Studland,  near  Swanage,  Dorsetshire.     [See 
Honorary  Fellows.^ 

1915  Milbank,  Sidney  Alexander,  M.B.A.A. 

14,  North-street,  Bishop  Stortford. 
1895     Millard,  Edgar  James,  F.C.S. 

35-42,  Charlotte-street,  E.C.2 
1891     Miller,  John  Albert,  M.Sc,  Ph.D.,  F.C.S.,  Chemist  to  the  State 
of  New  York. 

44  and  45,  Lewis  Block,  East  Sivan-street,  Buffalo,  N.Y., 
U.S.A. 
1920     Mills,  Albert  Edwarrl,  F.C.S.,  M.P.S. 
8,  George-street,  Bath. 

1912  Mills,  Frederick  William. 

Thornleigh,  Edgerton,  Huddersjield. 
1907      Minns,  John  Kdvvard,  M.S.C.I. 

H2,   North-street,    Taunton,   Somersetshire,   and    5,   North 
Town-terrace,  Taunton. 

1905  Moffat,  Kliezer. 

75,  High-street,  Chatham. 
1911     Mond,    Robert    Ludwig,    :\r.A.,    F.R.S.E.,    F.Tnst.P.,    F.CS., 
F.Ph.S.,  F.G.S.,  F.Z.S. 
Comhe  Bank,  Sevenoaks,  Kmt. 


OKDINARY   FELLOWS.  15 

Elected. 

1916     Moore,  Professor  Benjamin,  M.A.,  D.Sc,  F.R.S. 

8,  Pembroke-villas,  The  Green,  Richrnond. 
1897     Moore,  Harry,  Curator,  Public  Museum,  Ciifton-park,  liother- 
ham. 

12,  WJiisfon-grove,  Moorgate,  Rotherham. 
1851     Moruland,  liicliard,  M.Inst.C.E. 

4,  Highbury-quadranty  Highbury,  iV.5 
1896     Moretou-Parry,  Lewis. 

163,  Oahfield-road,  Everton,  Liverpool. 
1918     Morrisli,  William  J.,  M.D.,  etc. 

''Westleigh,"  Thrale-road,  Streatham-park,  S.W.lij 

1918  Mortimer,  Hugh  Hamilton. 

15,  Mulgrave-road,  Croydon. 
1913    -Mosey,  Hessay,  M.I.H. 

7,  Pond-street,  Hampstead,  N.W.S 
1915     Mosley,  Frederick  Ormrod.  - 

University   College,  Heading,  and  ^'Whernsidc,"  Basing- 
stoJce-road,  Beading. 
1911     Mumford,  Major  E.  Moore,  M.Sc 

75,  High-street,  Ghorlton-on-Medlock,  Manchester. 

1919  Murray,  James  Alexander,  M.D. 

Director,  Imperial  Cancer  Research  Fund. 

8,  Queen' S'Square,  W.C.I 
1900     Murphy,  Albert  John,  F.C.S. 

2,  Dorset-square,  N.  W.l 


1914  Nail,  Kev.  George  Herbert. 

18,  Deans-yard,  Westminster,  S.W.I 

1915  Naylor,  George,  F.B.O.A.,  F.I.O. 

52,  Cavendish-place,  Jesmond,  Newcastle-on-Tyne. 
1890  *Nelson,  Edward  Milles. 

Beckington,  near  Bath,  Somersetshire. 
1911     Noad,  Lewis. 

7,  King's  Bench-walk,  Temple,  E.C. 
1899      Norman,  Albert,  L.K.C.P.  and  L.R.r.S.  Edui. 

36,  Coleherne-road,  EarVs  Court,  S.W.ii) 


1920     Oakdcn,  Charles  H.,  F.R.P.S. 

Hamilton  House,  W.C. 
1887     Ochsner,  A.  J.,  Ph.D.,  M.D. 

2106,  Sedg wick-street,  Chicago,  HI.,  U.S.A. 
1883     Offord,  John  Milton. 

8,  Culmington-road,  West  Ealing,  W.IS 
1907     Ogilvy,  James  Wilson. 

18,  Bloomsbury-square,   W.C,  and  21,  Ravensdale-man- 
sions,  Crouch-end,  N. 


16  ROYAL  MICROSCOPICAL  SOCIETY. 

Klccted. 

1878  O'Hara,  Lieut.-Colonel  Eicbard. 

West  Lodge,  Galway. 
1919     Oppenlieimer,  Captain  Frank,  I. M.S.,  8.R.,  M.R.,  Ch.B. 

c/o  Messrs.  Grlndlay  cit  Co.,  Bombay,  India. 
1897     Oructa  y  Diiarte,  Domingo  de 

Lagasca  IIG,  Madrid,  Spain. 
1900     Oxbrow,  Alfred  William. 

7,  Old  Haymarket,  Norwich. 

1879  Oxley,  Frederick. 


1912     Palmer,  Henry,  J. P.,  F.R.G.S. 

"  Wall  Nooh''  Langley  Park,  Durham. 

1910  Palmer,    Thomas    Chalkley,    President   of    Delaware    Comity 

Natural  History  Society,  Vice-Director,  Biological  Section, 
Academy  of  Natural  Sciences  of  Philadelphia. 

Media,  Delaware  Co.,  Penn.,  U.S.A. 
1919     Parish,  Rev.  Herald. 

191,  Stamford-street,  Brooks's  Bar,  Manchester. 
1912     Parsons,  Frederick  A. 

15,  Oshorne-road,  Stroud-green,  N. 
1890  *Paterson,  Mrs.  Catherine  Childs. 

15,  Compayne-gardens,  N.W.Q 
1916     Patterson,  Capt.  William    R.,  F.R.A.S.,  F.R.G.8.,  F.R.A.I., 

F.R.C.I.,  M.R.A.S.,  F.R.Met.Soc,  M.O.P. 
1907     Paulson,  Robert,  F.L.S. 

Glenroy,  Cecil-park,  Pinner,  Middlesex. 
1898     Payne,  Arthur  E.  T. 

Physiological     Laboratory,      University     of     Melbourne, 
Victoria,  and  Scotshurn,   Toorak,  Melbourne,  Victoria. 
1884   *Peek,  The  Honourable  Lady. 

Widworthy  Court,  Honiton. 
1898     Pillischer,  Jacob. 

88,  New  Bond-street,  W.l 

1911  Piuchin,  Ernest  Alfred,  B.Sc.  (Lond.),  F.l.C. 

4,  Gleneldon-road,  Streatham,  S.W  IG 

1906  Plaskitt,  Frederick  James  Wade. 

15,  Uxhridge-road,  Eickmansworth,  Herts. 

1907  Pledge,  John  Harry. 

7'2,  Nibthwaite  Boad,  Harroio,  Middlesex. 
1919     Poignand,  Rev.  Cecil  W.,  M.A. 

c/o  The  Admiralty,  London,  S.  W. 
1897     Pollard,  Jonathan. 

10,  Porteus-road,  Paddington-green,  W.2 
1902     Poser,  Max. 

16,  Vick  Park  B.,  Rochester,  N.Y.,  U.S.A.,  and  c/o 
Bausch  d  Lomb,  St.  Paul-street,  Eochestcr,  N.Y., 
U.S.A. 

1867     Potter,  Georgcf. 

296,  Archway-road,  N.6 


ORDINARY    FELLOWS.  17 

Klccted. 

1919     Pougher,  Ernest  W.,  M.M.A.E. 

93,  Manchester-road,  Chorlton-cam- Hardy,  Manchester. 
1892     Pound,  Charles  Joseph. 

Director,  Stock  Experiment  Station,  Yeeromjpilly,  Queens- 
land, Australia. 
1880     Powell,  Thomas  Hugh. 

Emsdale,  Greenham-road,  Muswell-hill,  N. 


1898  Radley,  Percy  Edward, -F.Z.S. 

Nesta,  Broxbourne,  Herts,  and  The  Metric  Puhlishimj  Co., 
329,  High  Holhorn,  W.G.I 

1919  Ramana-Sastrin,  Vedaranyesvara  Vaidyanatha,  M.A.,  Ph.D., 

F.L.S.,  F.Z.S.,  F.R.H.S.,  F.R.A.S.,  F.U.Met.Soc,  F.P.S.L., 
Mem.  Brit.  Astron.  Ass.,  Mem.  Royal  Astron.  Soc.  of 
Canada,  Mem.  London  Math.  Soc,  M.R.A.S. 

Vedaraniam,    Tanjore,  Dt.,   South    India,    and  1,  Sami 
Pillai-street,  Ghoolai,  Madras,  JV.(7.,  South  India. 

1896  Ranken,  Charles,  F.C.S. 

11,  Stockton-road,  Sunderland. 

1920  Rau,  Venkata,  M.A. 

Department    of    Agriculture,     Bangalore,     India,     and 
c/o  Messrs.  Coutts  tit  Go.,  Bankers,  Stra^id,  W.G. 
1917     Rawlins,  Francis  Ian  Gregory. 

White  Waltham  Grove,  near  Maidenhead,  Berkshire. 
1912     Rees,  W.  Eric,  F.S.M  C. 

Glovelly,  Bedford-road,  Newport,  Mon. 
1910     Reid,   Alfred,   M.B.,  D.P.H.,  B.Hy.  Durh.,  M.R.C.S.   Eng., 
L.R.O.P.,  Government  Medical  Officer. 

Kuala  Lumpur,  Selangor.  Federated  Malay  States. 
1920     Reid,  Duncan  James,  M.B.,  CM. 

20,  Blakesley-avenne,  Ealing^  W.6 

1897  Remington,  John  Stewart,  M.R.A.C.',  F.C.S.,  I'.L.S. 

Aynsome-house,  Grange-over- Sands,  B.S.O.,  Lancashire 

1899  Rheiuberg,  Julius. 

23,  The  Avenue,  Brondeshury-park,  N.  W. 
1893     Richardson,  Frederic  William,  F.I.C.,  F.C.S.,  Gounty  Analyst, 
Bradford,  and  Oak  Lea,  Menston,  Yorkshire. 

1916  Richardson,  John. 
1908     Robertson,  James  A. 

Skerryvore,  llolmfield-acenue,  Gleveleys,  near  Blackpool. 

1910  *Robins,  Herbert  George,  F.R.G.S. 

Toms  Farms,  Wankie,  S.  Bhodesia,  South  Africa. 

1917  *  Robinson,  Miss  Nancy  M. 

Glassel  House,  Glassel,  Aberdeenshire. 
1899      Rogers,  George  Henry  James. 

2,  Bower-terrace,  Tonhridge-road,  Maidstone. 

1911  Ross,  John  Pilkethly,  M.P.S. 

Gare  of  Messrs.  Stella  and  Go.,  Esplanade-road,  Bombay, 
India. 


18  ROYAL   MICROSCOPICAL   SOCIETY. 

Elected. 

1918     Boss,  Sydney  W. 

Michelmersh,  Romsey,  Hants. 
1883  *Kosseter,  Thomas  B. 

6,  Salisbury -road  ^  St.  Stephen's,  Canterbury. 
1888     Rousselet,  Charles  Frederic. 

15,  Cloud esley -road,  St.  Leonards-on-Sea. 
1918     Rowley,  Frank,  M.I.M.M. 

21,  BucMand'Crescent,  Hampstead,  N.  W.d 
1897      Kowley,  Frederick  Richard,  Curator,  Boyal  Albert  Memorial 
Museum,  Exeter. 

8,  Pinhoe-road,  Heavitree,  Exeter. 
1917     Ryiand,  Lieut,-C()lonel  Alfred  W. 

Glen  Hurst,  WatUng-street-road,  Fulwood,  Preston. 


1919     St.  John- Ward,  Henry. 

Brebner  School.  Bloemfontein,  Orange  Free  State,  South 
Africa. 
1918     Salmon,  Walter 

17,  The  Grove,  Eccles,  Lanes. 
1892  ^Salomons,  Sir  David  Lionel,  Bart.,  J.P.,  M.A.,  D.L.,  F.K.G.S., 
F.G.S.,  F.Z.S. 

49,  Grosvenor-street,  W. ;  and  Broo)iihill,  Tiinbrid(je  Wells. 
1909     Saxton,  Thomas  R.,  Assoc.^I.Inst.C.E. 

48,  East  Bank,  Stamford-hill,  JV.16 
1898     Scales,  F.  Shillington,  M.A.,  M.I).,  B.C.  (Cantab.). 

Bedcourt,  Adams-road,  Cambridge. 
1880     Scott,  Dukinfield   Henry,  M.A.,  D.iSc.,  Ph.D.,  LL.D.,  F.R.S., 
F.L.S. 

East  OaMey-house,  Basingstoke,  Hants,  and  Atheneeum- 
club. 

1916  Scott,  Joseph  Henry. 

2,  Priory-gardens,  Weld-road,  Birhdale,  Southport. 
1909     Scott,  Walter. 

Nant-y-Coed,  Conway,  Carnarvonshire. 

1918  Scott,  Wm.,  F.R.C.V.S. 

Friarn  House,  Bridgioater. 
1900     Scourtield,  David  J.,  F.Z.S.,  Hon.  «eckktary. 

63,  Queen' 8-road,  Leytonstone,  E.ll 
1907     Scriven,  Charles  R. 

Kingscote,  Furze-hill,  Burgh-heath,  Surrey. 

1919  Seager,  John  H or s ford. 

1,  St.  Mary's-road,  Faversham,  Kent. 

1917  Sears,  R.  S.  W. 

1,  Lisson- grove,  Marylebone,  N.W.I 

1918  Seymour- J  ones,  Alfred. 

"  Pendoicer,"  Wrexham. 
1902     Sharpc,  Charles  James. 

130,  Fenchurch-street,  E.C.S 


ORDINARY   FELLOWS.  19 

Elected. 

1885  *Shelley,  Major  A.  D.  G.,  R.E.  (Retired). 

Bombay,  Baroda  and   Central  Indian  Railway    Board, 
1\,  Bishopsgate,  E  C.'2 
1910     Sheppard,  Alfred  William,  F.L.S. 

"  Boyal  Oak  "  Hotel,  Sevenoaks. 
190!)     Sheppard,  Edward  James. 

137,  Kennington-road,  Lambeth,  S.E.ll 
1920     de  Sibour,  Le  Vicorate,  F.Z.S. 

c/o  Messrs.  Morgan  Grenfell   <&^  Co.,   22,    Old   Broad- 
street,  E.G. 

1909  Sidwell,  Clarence  J.  H. 

46,  AsJibourne-grove,  East  Dulivich,  S.E. 
1912     Simpson,  Norman  DoiigLis,  B.A. 

Maesbury,  Cavendish-road,  Bournemouth. 

1916  Singer,  Charles,  M.A.,  M.D. 

Westbury  Lodge,  Norham-road,  Oxford. 

1910  Sinha,  J.  C,  J. P.,  Honorary  Presidency  Magistrate. 

cjo    Jones  &    Co.,   Solicitors,   6,    Old    Post   Office-street, 
Calcutta. 
1918     Skepper,  Harry  Godfrey. 

"  Lindum''  Brothertoft-road,  Boston,  Lines. 

1917  Smith,  Joseph,  F.S.A.A. 

28,  Altom-street,  BlacJcbiirn,  Lancashire. 

1908  Smith,  Theodore  White. 

Naperville,  Du  Page  County,  Illinois,  U.S.A. 
1906     Smitii,  Thomas  James. 

Braeside,  Bosioorth-road,  New  Burnet. 
1897     Soar,  Charles  David,  F.L.S. 

37,  Dryburgh-road,  Putney,  S.W.l^ 
1920     Sonutag,  Charles  F.,  M.D.,  Ch.B. 

80a,  Belsize-park-gardens,  N.W.'d 
1903     Spitta,  Edmund  Johnson,  L.R.C.P.  (Lond.),  M.R.C.S.,  (Eng.), 
F.R.A.S. 

41,  Ventnor-villas,  Hove,  Brighton. 

1918  Springall,  Hubert  F. 

The  Friars,  King's  Lynn. 
1903     Spry,  Robert,  Lieut.-Commaiider,  R.N. 

83,  Mount-Gold-road,  Plymouth. 
1882     Squance,  Major  Thomas  Coke,  M.D.,  M.S.,  F.R.S.E. 

The  Cottage,  Newbiggin,  Aysgarlh,  S.O.,  Yorks. 

1909  Stewart,  Thomas  S.,  M.  I ). 

1736,  Spruce-street,  Philadelphia,  Pa.,  U.S.A. 
1900     Stiles,  Matthew  Henry. 

10,  Avenue-road,  Doncaster. 
1867     Stoker,  George  Nay  lor. 

Fairfield,  Lessar-avenue,  Clapham-common,  S.W. 
1914     Strachan,  James. 

74,  Blenheim-'place,  Queen  s  Cross,  Aberdeen. 
1912  *Stringer,  Edward  Belcher, 

Eger ton-lodge,  Bromley,  Kent. 


20  KOYAL    MICROSCOPICAL    SOCIETY. 

KlecWd 

1871     Stuart,  Jolin. 

3,  North-side,  Clapham-common,  S.WA 

1918  Sutoliffe,  Herbert. 

The    Research    Laboratory,  Petaling,    Federated    Malay 
States. 
1920     Sutherland,  Donald,  M.A. 

"  Golden     Surst,"     20,     Carmunnock-road,      Cathcart, 
Glasgow. 

1919  Swainson-Hall,  li,  F.L.S. 

Foste  Restante,  Casa  de  Senor  Joao  Martins,  Cahinda, 
Fortuguese  Congo,  S.  W.  Africa. 
1906     Swift,  Mansell  James. 

81,  Tottenham-court-road,  W.l 
1889     Sykes,  Mark  Langdale. 

95,  Gardigan-roadf  Leeds. 
1911     Syner,  Harry. 


1911     Tabor,  Charles  James,  F.R.A.I. 

The  White  House,  Knott' s-green,  Leyton,  Essex. 
1891  *Talmage,    James    Edward,    D.Sc,    Ph.D.,    F.R.S.E.,    F.G.S., 
Frofessor  of  Geology,  University  of  Utah,  Salt  Lake  City, 
Utah,  U.S.A. 

The  Deseret  Museum,  Salt  Lake  City,  Utah. 

1900  Taveruer,  Henry. 

Wrekin  House,  319,  Seven- Sisters-road,  Finshury-ptirk,  N.4. 

1919  Taylor,  Albert. 

32,  William-street,  Ryecroft,  Ashton-uudey-Lyne. 
1916     Taylor,  Frederick  H. 

County  Bank,  Chorley,  Hants. 
1891     Terry,  Edwin,  F.C.S. 

Sunhuri/  House,  374,  Brixton-road,  S.W.9 
1916     Thirunal    Eaja,    Rohani,    M.R.A.S.C.,    M.S.S.A.,    M.A.S.P., 
etc.,  etc. 

Kizhakke    Kottaram    Falace,    Trivandrum,    Travancore, 
S.  India. 
1885   ^Thomson,  J.   Arthur,  M.A.,  LL.J).,  F.R.S.i:.,  ¥ .Z.^.,  Regius 
Frofessor  of  Natural  History  in  the  University  of  Aberdeen. 
Natural  History  Department,  Marischal  College,Univcrsity, 
Aberdeen,  and  Castleton  House,  Old  Aberdeen. 
1881     Thomson,  William. 

Royal  Institution  Laboratory,  79a,  Frincess-street,  Man- 
chester. 

1920  Tliorne,  Captain  Ralph  G.  A.,  \].A. 

82,  Ashley-gardens,  S.W.I 
1912     Tierney,  Clarence,  M.S.,  IJ.Sc. 

"  Netherton,"  CouUdon,  Surrey. 

1901  Tilling,  George. 

Grasmere,  Rydal-road,  Streatham,  S.W.16 


ORDINARY   FELLOWS.  21 

Elected. 

1919     Tomlinson,  Thomas  Willis  Brown. 
High-street,  Berkhamsted. 

1919  Topley,     William     Whiteman     Carlton,     M.D.,     F.R.C.P., 

M.E.C.S.,  etc. 

The   Institute   of    Pathology,    Charing    Cross    Hospital 
Medical  School,  Chandos-street,  W.G.2 

1918  Triggs,  Edward  E. 

c/o  Marconi  Co.,  Milburn  House,  Newcastle-on-Tyne. 

1920  Trinder,  George  A.  W.,  M.J.I. 

471,  Harrow-road,  TF.IO. 
1917     Tripp,  Charles  Llewellyn  H.,  M.R.C.S.,  L.R.C.P. 
The  Chestnuts,  Staplegrove,  Taunton. 

1919  Tucker,  Quincey  C,  M.B.,  Ph.G. 

U.S.  Naval  Hospital,  Fort  Lyon,  Colorado,  U.S.A. 

1920  Turner,  William. 

21,  Vera-road,  Fulham,  S.W. 
1915     Tutt,  Captain  John  Francis  Donald,  M.R.C.V.S.,  F.Z.S. 

1,  St.  Cross-road,  Winchester. 
1882     Tuttle,  Albert  Henry,  M.Sc. 

University  of  Virginia,  Charlottesville,  Va.,  U.S.A. 


1913     Verrall,  Frederick  H.,  B.A.,  LL.B. 
The  Hollies,  Worthing,  Sussex. 


1909     Walter,  Rev.  Frederick  William. 

The  Grange,  Worstead,  Norfolk. 
1%(S1  ^Walters,  James  Bfopkins,  M.R.C.S. 

15,  Friar-street,  Reading. 
1869     Ward,  Frederic  Henry,  M.R.C.S. 

52,  Lancaster-road,  West  Norwood,  S.E.27 
1885     Warner,  Edmond. 

Southend  House,  Eltham,  S.E. 

1911  Warrington,  Capt.  A.  F.  G.,  F.R.G.S. 

c/o    The  British  India  Marine  Service,    Club,  Norton  s- 
huildings,  Calcutta,  India. 
1883     Waters,  Arthur  William,  F.L.S.,  F.G.S. 

Alderley,  McKinley-road,  Bournemouth. 
1919     Watkinson,  Harry. 

848,  Hainton-avenue,  Grimsby. 

1919  Watts,  George  William,  L.D.S.Eng. 

103,  Haverstock-hill,  N.W.Z 

1912  Webb,  AVilfred  Mark,  F.L.S. 

The  Hermitage,  Hanicell,  W. 
1897     Webster,  William  Thomas. 

252,  Caledonian-road,  N.l 

1920  Welsford,  Miss  Evelyn  Janie,  M.B.E.,  F.L.S. 

Horticultural  College,  Swanley,  Surrey. 


22  ROYAL   MICROSCOPIOAL   SOCIETY.^ 

Elected. 

1885  *Western,  Edward  Young. 

27,  Pembridge-square,  Notting-Mll-gate,  W.S 
1919     Wliipp,  James  Euarr,  M.P.S. 

16,  St.  John-street,  Longsight,  Manchester. 
1895     White,  Charles  Powell,  M.D.,  F.R.C.S.,  L.R.C.P.,  Pathological 
Department,  Victoria  University,  3Ianchester. 

1,  Albemarle-road,  Withington,  Manchester. 
188G  *Whitehead,  Palph  Radcliffe. 

Woodstock,  Ulster  C,  N.Y.,  U.S.A. 
1898     Whittaker,  Oscar,  F.E.S. 

"  Ormidale,"  Ashlands,  Ashton-upon-Mersey,  Cheshire. 

1915  Whitteron,  Frederick. 

78,    Barkly -street,    St.    Kilda,    Melbourne,    Victoria, 
Australia. 
1913     Wigau,  BasilP.,F.C.S. 

Rhondda-valley  Breweries  Co.,  Treherbert,  S.  Wales. 

1910  Wilding,  Percy  P. 

Fern  Nook,  Penwortliam  Hill,  Preston,  Lanes. 

1916  Wilkin,  Lieutenant  Arthur  P.,  F.E.H.S.,  F.Z.S.,  F.K.B.S. 

cjo  Eastern  Telegraph  Co.,  Ltd.,  Bombay,  India. 

1908  Wilson,  Joseph. 

The  Hawthorns,  3,  West-park-road,  Kew-gardens,  S.W. 

1911  Wilton,  Edmund  Wade,  A.I.S.E.,  F.S.A. 

Planet  Works,  Bramley,  Leeds,  and  Cliff  View,  Pollard- 
lane,  Newlay,  near  Leeds. 

1909  Winton,  Francis  Langridge,  M.A. 

The  Brewery,  Chatteris,  Cambs.,  and  23,  Bateman-street, 
Cambridge. 
1911     Woodhead,    Sir    German    Sims,  K.B.E.,  M.A.,  M.D.,  LL.D., 
F.R.S.E.,  F.R.C.P.  (Ed.),   Professor  of  Pathology   in  the 
University  of  Cambridge. 

Dysart  House,  Luard-road,  Cambridge. 
1880  *Wo()dward,  Beiuara  B.,  F.L.S.,  F.G.S. 

4,  Longfield-road.  Ealing,  W.^ 
1880  *Woodward,  Henry,  LL.D.,  F.R.S.,  F.G.S.,  F.Z.S. 

Tudor  Cottage,  Clay  Hill,  Bushey,  Herts. 
1889     Wright,  Charles  Henry. 

10,  Clarence-road,  Kew. 
1882     Wright,  Prof.  R.  Ramsay,  M.A.,  B.Sc. 

Bed  Gables,  Headington-hill,  Oxford. 
1919     Wycherley,  Sydney  R. 

25,  Hollegrave-road,  Bronfley,  Kent. 


1918     Yennolofi;  Sir  N.,  K.C.B.,  K.C.V.O.,  F.L.S. 

3,  Whitehall-court,  S.W.I 
1890  *youdale,  William  Henry. 

21,  Belle  lale-sireet,  Workiiigton. 


Honorary  Fellows.  23 


Elected. 

1918     Young,  George  William. 

20,  Grange-road,  Barnes,  S.W. 


1904     Zimmerman,  Professor  Charles,  F.R.M.S. 

Sao  Carlos  de  Pinhal,  Rua  18  de  Maio,  60,  Estado  de 
S.  Paulo,  Brazil. 


HONORARY   FELLOWS. 

1879     Balbiani,  E.  G. 

Paris. 
1904     Bonnier,  G. 

Paris. 

1918  Bruce,  Lady  Mary  Elizabeth,  R.RC. 

London. 

1904  Delage,  Y. 

Paris. 
1895     Golgi,  C. 

Padua. 

1905  Jennings.  H.  S. 

Baltimore. 
1897     Lee,  A.  B. 

Gologny. 

1919  Michael,  Albert  Davidson,  F.L.S.,  F.Z.S.,  F.R.H.8. 

Studland. 
1912     Penard,  Eugene. 

Geneva. 
1904     Ramon  y  Cajal,  S. 

Madrid. 
1879     Ranvier,  L. 

Paris. 
1879     Sars,  G.  0. 

Ghristiania. 

1904  Teall,  J.  J.  H. 

London. 
1897     Toni,  G.  B.  de 

Modena. 
1879     Warming,  E. 

Copenhagen. 

1905  Wilson,  E.  B." 

New  York. 
1905     Wood,  R.  W. 

Baltimore. 


patron. 

HIS    MAJESTY    THE    KING 


ipast-presttients. 


Elected 


M.D.,  LL.D.,  F.R.S. 


*SiH  Richard  Owen,  K.C.B.,  D.C.L 

*J0HN    LiNDLEY,    Pll.D.,    F.R.S 

*Thoma8  Bell,  F.R.S 

*  James  Scott  Bowerbank,  LL.D.,  F.R.S. 
♦George  Busk,  F.R.S. 

*  Arthur  Farre,  M.D.,  F.R.S 

*George  Jackson,  M.R.C.S. 

*  William  Benjamin  Carpenter,  C.B.,  M.D.,  LL.D.,  F.R.S. 
*George  Shadbolt     .. 

*Edwin  Lankester,  M.D.,  LL.D.,  F.R.S 

*JoHN  Thomas  Quekett,   F.R.S. 
*Robert  James  Farrants,  F.R.C.S. 
*Charles  Brooke,  M.A.,  F.R.S. 

*  J  AMES  Glaisher,  F.R.S. 
*Rev.  Joseph  Bancroft  Reade,  M.A.,  F.R.S. 

*  William  Kitchen  Parker,  F.R.S. 
*Charle8  Brooke,  M.A.,  F.R.S. 
*Henry  Clifton  Sorby,  LL.D.,  F.R.S.      .. 

*  Henry  James  Slack,  F.G.S. 
♦Lionel  S.   Be  ale,  M.B.,  F.R.C.P.,  F.R.S. 

*  Peter  Martin  Duncan,  M.B.,  F.R.S. 
*Rev.  William   Henry  Dallinger,  M.A..  LL.D.,  F.R.S. 

1884 
♦Charles  Thomas  Hudson,  M.A.,  LL.D.  (Cantab.),  F.R.S. 

1888- 
♦Robert  Bbaithwaite,  M.D.,  M.R.C.S. 
Albert  D.  Michael.  F.L.S. 
Edward  Milleh  Nelson     ,. 
William  Carruthers,  F.R.S. ,  F.L.S.,  F.G.S.     .. 
Henry  Woodward,  LL.D.,  F.R.S.,  F.G.S.,  F.Z.S 


1840-1 

1842-3 

1844-5 

1846-7 

1848-'.) 

1850-1 

1852-3 

1854-5 

..      1856-7 

..      1858-9 

..      1860 

..      1861-2 

,      1863-4 

1865-6-7-8 

..    1869-70 

..      1871-2 

..      1873-4 

1875-6-7 

..      1878 

..    1879-80 

1881-2-3 

5^6-7 

9-90 

..      1891-2 

1893-4-5-6 

1897-8-9 

..      1900-1 

1902-3 


Dukinfield  Henry  Scott,  M.A.,  Ph.D.,  LL.D., F.R.S., F.L.S. 

1904-5-6 
^The   Right   Hon.  Lord  Avebury,  P.C,   D.C.L.,   LL.D., 

F.R.S.,  etc 1907-8 

Sir  Edwin  Ray  Lankester,  K.C.B.,  M.A.,  LL.D.,  F.R.S., 

F.L.S.,  F.Z.S ..  1909 

J.  Arthur  Thomson,  M.A.,  F.R.S.E.  ..  ..  1910-11 
»Henry  Geo.  Plim.mkk,  F.R.S.,  F.L.S..  F.Z.S.,  etc.  ..  1911-12 
G.  Sim  Woodhead,  M.A.,  M.I).,  LL.D.,  F.R.S.E.,  etc.  ..  1913-15 
Edward  Hkuon-Allkn,  F.li.S.,  F.L.S.,  F.G.S. ,  etc.  ..  1916-17 
Joseph  E.  IUunard,  K.Inst.P 1918-19 


Uec(«l8(;(l. 


JOUENAL 

OF   THE 

ROYAL   MICROSCOPICAL   SOCIETY. 

MARCH,  1920. 


TRANSACTIOXS   OF   THE   SOCIETY. 


I. — Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  * 

By  Agnes  Arber,  D.Sc,  F.L.S.,  Keddey  rietcher-Warr  Student 
of  the  University  of  London. 

(Bead  February  18,  1920.) 
One  Plate  and  Two  Text-figb. 

Introduction. 

In  a  recent  paper,  by  Mr.  Rudolf  Beer  and  the  present  writer,  in 
the  Proceedings  of  the  Royal  Society,t  attention  has  been  drawn 
to  the  occurrence  of  binucleate  or  multinucleate  cells  in  the  young 
vegetative  tissues  of  177  species,  representing  60  families,  and 
including  members  of  the  Pteridophytes,  Gymnosperms,  Dicotyle- 
dons and  Monocotyledons.  The  binucleate  condition,  which  in 
these  cases  occurred  as  a  normal  feature,  was  invariably  found  to 
arise  through  mitosis,  and  not  by  direct  division.  It  was  shown 
that,  though  the  cell-plate  makes  its  appearance  as  usual,  it  fails 
to  give  rise  to  any  cell-membrane,  while  the  whole  complex  of 
spindle  fibres  with  the  associated  cytoplasm  becomes  transformed 
into  a  hollow  sphere  which  encloses  the  daughter  nuclei.  For  this 
spherical  shell  we  have  suggested  the  term  "  phragmosphere." 
The  phragmosphere  is  seen  in  section  in  a  number  of  the  examples 
drawn  on  the  plate  accompanying  the  present  paper  (see,  for 
instance,  figs.  7,  26  and  39  A).     In  the  memoir  cited  we  enume- 

^  *  The  writer  desires  to  acknowledge  her  indebtedness  to  the  Senate  of  the 
University  of  London  for  a  grant  from  the  Dixon  Fund  towards  the  expenses  of 
tihs  and  other  researches. 

t  Beer,  R.  and  Arber,  A.  (1919)  and  (1916). 

B 


2  Transactions  of  the  Society. 

rated  many  case's  in  which  these  phenomena  had  been  observed, 
but  we  did  not  describe  them  individually.  In  the  present  instal- 
ment I  propose  to  deal  with  the  history  of  the  vegetative  nucleus, 
so  far  as  this  history  bears  upon  the  binucleate  phase,  in  the 
following  species,  each  of  which  has  been  chosen  as  presenting 
certain  features  of  interest : — 

1.  Eremurus  himalaicus  Baker  (PL  I,  figs.  1-11,  and  pp.  2-6). 

2.  Asparagus  officmalis  L.  (PI.  I,  figs.  13,  27,  28,  and  pp.  6-11). 

3.  Helianthus  Nuttallii  Torr.  et  Gray  (PL  I,  figs.  21-24,  and 
pp.  11-12). 

4.  Helianthus  tuber osus  L.  (pp.  12-13). 

5.  Syringa  vulgaris  L.  (p.  13). 

6.  Monstera  deliciosa  Liebm.  (PL  I,  figs,  39  A  and  B,  and  p.  14). 

7.  Hemerocallis  fulva  L.  (PL  I,  figs.  33-37,  and  pp.  14-15), 
Nothoscordum  fragrans  Kunth  (p.  15),  and  Alisma  Plantago  L. 
(PL  I,  fig.  38,  and  p.  15). 

8.  Polygonum  cuspidatum  Sieb,  et  Zucc.  (PL  I,  figs.  25  and  26, 
and  pp.  15-16). 

9.  Morus  nigra  L.  (PL  I,  figs.  12  A-C,  and  pp.  16-18). 

10.  Hippuris  vulgaris  L.  (PL  I,  figs.  17-20,  and  pp.  18-19), 
and  Modea  canadensis  Michx  (PL  I,  figs.  29-32,  and  p.  19). 

11.  Stratiotes  aloides  L.  (Text-figs.  1  and  2,  and  pp.  19-21). 


1.  Eremurus  himalaicus  Baker  (PL  1,  figs.  1-11). 

Eremurus  himalaicus  is  a  large  and  vigorous  member  of  the 
Liliace?e,  which  throws  up  in  the  spring  a  rapidly -growing  raceme 
of  numerous  flowers,  sometimes  attaining  the  height  of  6  feet  or 
more  by  the  middle  of  June.  The  developing  inflorescence  axis 
affords  very  favourable  material  for  the  study  of  the  binucleate 
phase.  A  transverse  section  of  the  axis  in  the  flowering  region 
reveals  a  broad  vascular  zone  enclosing  a  small  central  pith, 
the  whole  surrounded  by  a  narrow  parenchymatous  cortex.  Such 
a  section,  examined  while  the  inflorescence  is  quite  immature 
(e.g.  in  the  latter  part  of  April),  shows  that  the  great  majority  of 
the  cells  of  the  pith  and  the  ground  tissue  between  the  bundles 
contain  two  nuclei,  or  in  some  cases  as  many  as  three.  Binucleate 
cells  also  occur,  though  more  rarely,  in  the  cortex,  which  consists 
of  elements  of  smaller  diameter  than  tliose  of  the  pith  and  ground 
tissue.  The  epidermis  appears  to  be  entirely  uninucleate.  A 
study  of  the  origin  of  the  supernumerary  nuclei  shows  that  they 
invariably  arise  by  mitosis.  The  cells  contain  vacuolate  cyto- 
plasm. When  a  nucleus  is  about  to  divide  the  cytoplasm  appears 
to  be  attracted  towards  it,  and  it  becomes  suspended  from  the 
lining  layer  by  more  numerous,  conspicuous  and  well-defined 
bridles  than  in  the  case  of  those  nuclei  which  are  in  a  condition 


Sticdies  on  the  Binucleate  Phase  in  the  Plant-cell.  3 

of  complete  rest  (PI.  I,  fig.  1).  The  same  aggregation  of  cytoplasm 
has  been  noticed  in  the  case  of  Dipsacus  laciniatus.  In  some 
preparations  of  the  prothallus  of  Cephalotaxus  Fortunei,  at  the  stage 
when  the  cells  are  becoming  multinucleate,  which  Mr.  Boodle  has 
kindly  shown  to  me,  the  relation  of  the  cell  protoplasm  to  the 
dividing  nuclei  is  exactly  similar  to  that  just  described  for 
Eremurus,  the  cytoplasmic  bridles  being  particularly  well 
developed. 

The  formation  of  binucleate  cells  proceeds  exactly  on  the  lines 
described  in  general  terms  in  the  paper  already  cited.*  While  the 
daughter  nuclei  are  passing  into  rest,  the  chromosomes  go  through 
a  stage  in  which  they  each  show  a  large  vacuole  (PL  I,  figs.  8  and 
^).  That  such  paired  nuclei  retain  the  power  of  further  division 
is  shown  by  the  fact  that  a  phragmosphere,  with  its  two  included 
nuclei,  may  be  accompanied,  in  the  same  cell,  by  a  resting  nucleus 
(PI.  I,  fig.  7).  This  indicates  that  the  cell  previously  enclosed  a 
pair  of  nuclei,  one  of  which  has  divided  again,  while  the  other  has 
remained  in  the  resting  condition.  This  is  of  some  interest,  since 
it  means  that  two  sister  nuclei,  necessarily  of  identical  age  and 
living  apparently  under  identical  conditions  within-  a  single 
Tegetative  cell,  are  yet  capable  of  showing  marked  individuality  in 
their  behaviour. 

In  the  previous  generalized  account  of  the  development  of  the 
phragmosphere  (I.e.  p.  10),  it  is  stated  that  a  cell-plate  is  formed 
but  disappears  later.  It  may,  however,  be  objected  that  when  two 
daughter  nuclei  are  observed  with  a  cell  plate  between  them  (as  in 
PI.  I,  fig  4)  there  is  no  proof  that  the  development  of  a  phragmo- 
sphere will  follow,  since  the  appearance  in  question  might  equally 
well  be  interpreted  as  an  early  stage  in  actual  cell-wall  formation. 
The  conclusion  that  such  stages  are  both  hona  fide  members  of  the 
phragmosphere  series  is  based  on  the  fact  that  in  the  inflorescence 
described  there  is  no  evidenc3  of  any  recent  wall  formation  in 
planes  parallel  to  the  long  axis  of  the  organ  ;  a  cell  plate  such  as 
that  figured  could  form  a  wall  in  such  a  plane  only.  The  cells  both 
of  the  pith  and  of  the  ground  tissue  between  the  bundles  have 
a  rounded  outline,  as  seen  in  transverse  section,  and  intercellular 
spaces  occur  between  them.  This  is  true  of  all  the  inflorescences 
studied,  even  the  very  young  one  to  which  attention  will  be  called 
shortly.  The  only  exception  is  found  in  certain  small  cells  in  the 
pith  which  contain  raphides  and  mucilage,  and  which  divide  fairly 
frequently.  But  these  cells  are  quite  distinct  in  their  characters, 
and  the  occurrence  of  wall  formation  in  them  does  not  affect  our 
argument ;  our  figures  and  descriptions  refer  to  the  normal  pith  and 
ground  tissue,  and  not  to  these  specialized  cells.  In  order  to  test 
the  contention  that  the  increase  in  diameter  of  the  axis  depends 

»  Beer,  E.  and  Arber,  A.  (1919)  p.  10. 

B   2 


4  Transactions  of  the  Society. 

mainly,  if  not  entirely,  upon  increase  in  size  of  the  cells  without 
cell  division,  measurements  were  made  of  the  dimensions  in  trans- 
verse section  of  ten  pith  cells  taken  at  random  from  the  extreme 
bases  of  the  inflorescences  gathered  on  February  9  and  April  27 
respectively.  The  pith  cells  in  the  former  case  were  found  to- 
average  58  /a  and  in  the  latter  73  /a  in  diameter,  which  represents 
an  increase  of  26  p.c.  The  entire  axis  had  increased  in  the  same 
period  from  approximately  6  mm.  to  7*5  mm.  in  diameter,  repre- 
senting an  increase  of  25  p.c.  As  there  is  much  variation  in  size 
in  the  pith  cells,  no  great  reliance  can  be  placed  upon  the  exact 
figure  obtained  for  their  average  diameter,  and  the  extremely  close 
coincidence  of  these  percentages  is  probably  more  or  less  accidental  y. 
but  we  may  at  least  conclude  that  in  the  case  of  the  pith  the 
stretching  of  already  existing  cells  is  competent  to  account  for  the 
increase  of  diameter,  and  that  no  appreciable  amount  of  cell  mul- 
tiplication, with  formation  of  cell  walls  in  planes  parallel  to  the 
long  axis  of  the  organ,  need  be  postulated. 

In  describing  the  binucleate  phase  in  the  inflorescence  gathered 
on  April  27,  we  have  so  far  been  considering  only  the  main  part  of 
the  flowering  region.  Binucleate  cells  occur  near  the  apex,  but 
this  is  not  a  favourable  case  for  studying  the  exact  point  at  which 
this  condition  arises,  since  the  tip  becomes  hollow  and  dies  at 
a  relatively  early  period.  Passing  to  the  lower  sterile  region 
of  the  inflorescence  axis,  we  find  that  binucleate  cells  no  longer 
occur,  but  the  single  nuclei  are  bilobed  or  irregularly  lobed. 

For  comparison,  older  and  younger  inflorescences  were  studied, 
A  very  young  inflorescence  was  dissected  out  of  the  terminal  leaf- 
bud  early  in  February.  The  flowering  region  was  about  2  •  5  cm, 
long,  and  the  sterile  stalk  not  more  than  2  cm.  Binucleate  cells 
and  phragmospheres  occurred  in  the  fertile  region,  just  as  in  that 
gathered  at  the  end  of  April.  In  this  young  inflorescence,  how- 
ever, phragmospheres  were  not  confined  to  the  fertile  region,  but 
occurred,  in  addition,  in  the  sterile  stalk. 

Two  older  inflorescences,  gathered  on  May  7  and  May  28  re- 
spectively, were  also  studied.  On  examining  the  fertile  region  of 
the  inflorescence  fixed  on  May  7,  it  was  found  that,  though  many 
cells  of  the  pith  and  ground  tissue  were  binucleate,  as  in  the 
younger  axes,  nuclear  division  had  apparently  ceased  and  many  of 
the  cells  had  become  uninucleate.  The  nuclei  within  the  uni- 
nucleate cells  were  often  neatly  bilobed,  but  sometimes  lobed  o? 
fissured  in  an  irregular  fashion,  thus  recalling  the  condition  in  the 
sterile  lower  region  in  the  inflorescence  axis  fixed  ten  days  earlier 
(PI.  I,  fig.  10).  In  the  axis  gathered  on  May  28  uninucleate  cells 
liad  become  still  more  universal,  and  the  lobing  was  as  pronounced 
as  in  the  previous  case.  In  both  these  axes  the  nuclei  appeared 
somewhat  flattened  wlien  seen  in  profile.  The  bilobing  of  the 
nuclei  was  so  frequent  and  striking  that  its  occurrence  in  cella 


Studies  on  the  Bmudeate  Phase  in  the  Plant-ceVt,  5 

which  must  have  been  binucleate  at  an  earlier  stage  immediately 
suggested  that  it  was  an  indication  of  nuclear  fusion.  This  view  we 
were  at  first  inclined  to  accept,  but  further  work  has  led  to  the 
conclusion  that,  it  is  probably  untenable.  The  converse  view,  that 
theje  lobings  might  represent  early  stages  in  amitotic  division,  is 
at  once  put  out  of  court  by  the  fact  that  this  stage  follows  the  bi- 
nucleate stage  instead  of  preceding  it.  Light  is  thrown  upon  the 
subject  by  a  careful  examination  of  the  fertile  region  of  the  inflor- 
escence axis  gathered  on  April  27.  Here  we  find  a  number  of 
instances  in  which  one  nucleus  in  a  cell  looks  more  or  less  normal, 
while  the  other  stains  homogeneously  and  is  apparently  degene- 
rating (PI.  I,  fig.  11).  Such  evidence  has,  naturally,  to  be  used 
with  great  caution  to  avoid  confusing  the  results  of  poor  fixation 
with  actual  degeneration  stages,  especially  when  considering 
resting  nuclei,  wliich  are  often  less  well  preserved  than  those  in 
process  of  division.  It  seems  improbable,  however,  that  we  are 
dealing  with  an  artefact  in  the  present  case,  since  in  the  same 
section  phragmospheres  and  well-preserved  nuclei,  both  in  the 
inesting  stage  and  various  mitotic  phases,  may  be  observed.  One 
apparently  degenerating  nucleus  and  one  in  the  prophase  of 
division  have  been  noted  in  a  single  cell.  However,  though 
dividing  nuclei  in  all  stages  are  well  preserved  in  our  material  of 
■this  species,  the  preservation  of  the  resting  nuclei  is  throughout 
less  satisfactory,  and  the  possibility  must  be  recognized  that  our 
"  degenerations  "  are  artefact. 

That  one  of  two  sister  nuclei  of  identical  age  and  history  in  the 
same  cell  should  degenerate  while  the  other  remains  normal  is 
perhaps  a  somewhat  unexpected  result,  but,  as  we  have  already 
shown  (p.  3),  there  is  no  doubt  that,  at  earlier  stages,  such  pairs 
may  show  differential  behaviour,  one  entering  upon  a  second 
division,  while  the  other  remains  in  the  resting  stage.  We  are,  on 
the  whole,  inclined  to  think  that  the  ultimate  uninucleate  condition 
is  brought  about  by  the  degeneration  and  resorption  of  one  nucleus, 
while  the  later  lobing,  whether  regular  or  irregular,  is  merely  a 
symptom  of  age  and  perhaps  partial  degeneracy.  The  large-sized 
nuclei  of  the  Liliaceae  must  naturally  be  more  liable  to  collapse  and 
become  irregular  in  outline  than  smaller  and  more  compact  nuclei, 
such  as  are  generally  met  with  among  the  Dicotyledons.  We  do 
not,  however,  consider  that  the  possibility  of  an  occasional  fusion  is 
■excluded;  the  close  approximation  in  which  the  pairs  of  nuclei 
sometimes  lie  seems  favourable  to  such  an  event. 

In  order  to  find  out  whether  the  cytological  features  observed 
bore  any  relation  to  the  rates  of  elongation  of  the  different  regions, 
two  inflorescences  were  chosen  at  the  end  of  April  and  their  axes 
were  marked  off  with  Indian  ink  into  zones  1  cm.  in  length ;  the 
increase  in  length  of  these  zones  was  recorded  week  by  week  in  the 
period  before  fixation.     A  single  example  will  suffice  to  show  the 


6  Transactions  of  the  Society. 

result  of  the  examination  of  the  nuclei  in  these  zones,  whose 
growth-history  was  known.  Sections  were  cut  from  two  regions  of 
an  inflorescence  axis  gathered  on  May  28th,  one  of  which  had  not 
increased  in  length  at  all,  while  the  other  showed  the  greatest 
increase  observed  in  any  zone  in  this  particular  week — namely,  an 
elongation  of  from  2*8  to  5*5  cms.,  or  nearly  100  p.c*  It  was 
found  that  in  both  these  cases  the  nuclei  showed  the  same 
characteristics ;  most  of  the  cells  were  uninucleate  and  many  of 
the  nuclei  were  bilobed.  In  general,  the  conclusion  to  be  drawn 
from  the  different  inflorescences  which  came  under  observation 
seems  to  be  that  the  binucleate  stage  in  which  phragmospheres  are: 
abundant  is  characteristic  of  the  inflorescence  in  its  younger  state,, 
while  the  period  of  greatest  elongation,  which  occurs  subsequently^ 
is  marked  by  the  presence  of  single  nuclei,  Often  much  lobed  and 
flattened,  whose  appearance  suggests  senility.  These  nuclei  seem 
to  remain  in  much  the  same  condition  after  the  cessation  of 
growth. 

Besides  the  inflorescence  axes,  very  young  leaves  gathered  in 
February  were  examined.  They  showed  binucleate  cells  and 
phragmospheres  in  the  mesophyll  of  their  basal  centimetre,  while- 
near  the  apex  few  nuclei  were  visible  at  all,  and  binucleate  cell& 
were  apparently  absent.  The  results  obtained  from  the  leaf  thus 
harmonized  with  those  just  recorded  for  the  inflorescence,  bearing: 
in  mind. that  the  basal  region,  in  the  leaves  of  this  type  among  the 
Liliacese,  is  the  growing  zone. 


2.  Asparagus  officinalis  L.  (PI.  I,  figs.  13,  27,  28). 

The  young  shoots  of  Asparagus,  examined  in  the  early  part  of 
May,  at  the  stage  at  which  they  are  usually  cut  for  market,  show 
the  binucleate  phase  very  clearly.  Sections  across  the  "  head  " 
reveal  the -presence  of  binucleate  and  sometimes  trinucleate  or 
even  quadrinucleate  parenchyma  cells  in  the  pith,  in  the  ground 
tissue  between  the  scattered  bundles,  and  in  the  cortex.t  Binu- 
cleate cells  may  also  be  observed,  though  rarely,  in  the  xylem 
parenchyma  bordering  the  young  vessels,  and  in  the  epidermis.  The 
paired  nuclei  arise  by  karyokinesis,  the  process  of  division  and  the 
formation  of  phragmospheres  occurring  precisely  as  described  for 
the  case  of  Eremurns.  Asparagus  is  less  well  adapted  than  Eremurus 
for  the  study  of  the  various  stages  leading  up  to  phragmosphere 
formation,  because,  side  by  side  with  the  production  of  binucleate 
cells,  wall  formation  is  going  on  on  a  considerable  scale,  in  planes 
both  parallel  and  perpendicular  to  the  axis.     The  result  is  that  it 

♦  These  measurements  are  only  approximately  accurate,  since  the  growth  of 
the  axis  had  stretched  and  blurred  the  indian  ink  marks, 
t  Beer,  R.  and  Arber,  A.  (1919),  Text-figs.  1  and  2,  p.  9. 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  7 

is  impossible  to  say,  when  a  nucleus  is  observed  in  the  act  of 
division,  whether  it  will  ultimately  give  rise  to  paired  nuclei  in  a 
single  cell  or  to  the  solitary  nuclei  of  two  sister  cells.  It  is 
interesting  to  observe  that  the  nuclei  of  cells  which  are  adjacent, 
or  almost  adjacent,  may  divide  simultaneously,  one  giving  rise  to 
paired  nuclei  enclosed  in  a  phragmosphere,  while  the  other  produces 
two  nuclei  whose  phragmoplast  deposits  a  new  cell  wall  in  a 
perfectly  normal  fashion. 

The  parenchyma  cells  of  the  pith  and  ground  tissue  are  rela- 
tively large  and  vacuolate,  and,  as  usual  in  such  cases,  the  wall 
formation  occurs  by  the  "  progressive  "  method  first  described  by 
Treub* — the  two  nuclei  and  the  phragmoplast  travelling  across 
the  cell  in  order  to  carry  the  new  cell  wall  over  the  entire  area. 
The  cell  figured  on  PL  I,  fig.  27,  shows  this  point,  and  also  illus- 
trates the  fact  that  a  pair  of  free  nuclei  may  be  formed  within  a 
single  cell,  and  that  one  may  subsequently  divide  into  two  daughter 
nuclei  which  become  separated  by  a  cell  wall.  A  similar  occur- 
rence has  been  described  by  Nemec  f  in  the  case  of  the  multi- 
nucleate plerome  elements  of  Ricinus,  but  he  mentions  that  it  is 
extremely  rare.  This  wall  formation  between  the  daughters  of  a 
nucleus  which  was  itself  "  free  "  shows  that  the  appearance  of 
binucleate  cells  cannot  be  taken  to  indicate  that  the  power  of 
initiating  wall  formation  is  actually  lost ;  it  should  rather  be 
regarded  as  being  in  abeyance. 

The  fact  that  in  the  stem  of  Asparagus  wall  formation  is 
actively  continued  to  some  little  distance  below  the  apex  is 
perhaps  connected  with  the  existence  of  a  subsequent  period  of 
extremely  rapid  cell  stretching  and  elongation.  This  point  may 
be  illustrated  by  some  actual  measurements.  A  shoot  whose 
above-ground  portion  was  6 "3  cm.  long  on  May  12  increased  in 
a  week  to  18*3  cm.,  thus  almost  trebling  its  length,  but  remain- 
ing unbranched.  In  the  next  week  (May  19  to  26)  it  not  only 
increased  to  84  cm. — adding,  that  is  to  say,  05*7  cm.  to  its  stature 
— but  also  threw  out  branches  from  the  axils  of  all  the  upper 
leaves;  the  lowest  of  these  branches  was  18  cm.  long,  or  about  as 
tall  as  the  entire  main  axis  of  a  week  ago !  Such  rapid  growth 
must  be  very  largely  a  matter  of  the  elongation  of  already  existing 
cells,  so  it  is  not  sui-prising  that  the  Asparagus  shoot  prepares 
itself  by  a  good  deal  of  preliminary  wall  formation.  After  this 
great  growth  has  taken  place,  and  the  short,  thick  Asparagus  shoot 
has  become  slender  and  branched,  binucleate  cells  may  still  be 
observed  near  the  apex,  showing  that  this  character  is  not  confined 
to  the  very  young  stages. 

The  distance  from  the  apex  at  which  the  binucleate  phase 
begins  to  make  its  appearance  was  determined  by  means  of  serial 

IContd.  on  p.  10, 

♦  Treub,  M.  (1879).  t  N6mec,  B.  (1910). 


Transactions  of  the  Society. 


EXPLANATION  TO  THE   PLATE. 

All  figures,  unless  otherwise  stated,  drawn  with  the  camera  lucida  from 
transverse  hand  sections  of  the  organs  in  question.  Zeiss  2-mm.  oil-immersion 
lens  and  CO.  6  used  throughout.  Magnification  1070,  reduced  in  reproduction  to 
about  460. 

Figs.  1-11. — Eremurus  himalaicus  Baker. 

Figs.   1-9  illustrate  phragmosphere  formation  in  the  ground  tissue  cells  of    a 
young  inflorescence  axis  at  the  stage  reached  towards  the  end  of 
April  or  beginning  of  May. 
Fig.     1. — Binucleate  cell  in  which  one  nucleus  is  about  to  divide  again  (to 
economize  space  outline  of  cell  incompletely  shown). 
„        2. — Chromosomes  on  equatorial  plate. 
,,        3.—  Spindle  with  chromosomes  at  the  poles,  from  a  cell  which  also  contained 

a  resting  nucleus. 
„       4. — Initiation  of  cell  plate. 
Figs.  5,  6. — Early  stages  in  phragmosphere  formation. 

Fig.    7. — A  phragmosphere  with  paired  nuclei,  in  a  cell  also  containing  a'resting 
nucleus. 
„        8. — Phragmosphere  expanding  towards  the  wall  of  the  cell ;  chromosome 

of  daughter  nuclei  becoming  vacuolate. 
„        9. — Phragmosphere  coinciding  with  the  cytoplasm  lining  the  cell  wall. 
„      10. — Nuclei  from  uninucleate  cells  just  below  flowering  region  in  an  in- 
florescence somewhat   older   than  that  from  which  the  majority 
of  figs.  1-9  were  drawn  (gathered  May  7,  1915). 
11. — A  normal  nucleus  (n)  and  a  degenerating  nucleus  (d)  belonging  to  the 
same  cell  (April  27,  1915).     The  nuclei  were  not  in  contact,  but  lay 
in  difierent  focal  planes. 

Figa.  12  A-C.—Morus  nigra  L.     May  8,  1916. 

Fig.  12  A.— Spindle  in  the  corner  of  a  large  pith  cell.    (To  economize  space  the 
outline  of  the  cell  is  only  shown  in  part.) 
„      12  B. — Pith  cell,  with  a  phragmosphere  enclosing  two  daughter  nuclei. 
,,      12  C. — Phragmosphere  at  a  late  stage,  in  a  pith  cell. 

Fig.  13  (see  also  figs.  27,  28)— Asparagus  officinalis  L.    May  6,  1915. 

Lobed  nuclei,  from  five  uninucleate  cells  of  ground  tissue  between 
2-5  and  4-5  cm.  below  base  of  head. 

Figs.  14,  15. — Chrysanthemum  Parthenium  Bernh.    Pith  cells 
from  an  axis  gathered  June  12,  1915, 

Fig.  14. — Two  adjacent  cells,  one  containing  a  resting  nucleus  and  a  second 
nucleus  dividing  at  the  spindle  stage  (also  a  cluster  of  crystals). 
The  second  cell  contains  a  phragmosphere,  of  which  only  one  of 
the  two  nuclei  is  included  in  the  section. 
„  15. — Another  cell,  showing  a  phragmosphere  at  a  later  stage,  at  which  it 
almost  coincides  with  the  primordial  utricle. 

Fig.  16. — Selaginella  Wildenovii  Baker. 

Cell  of  cortex,  with  a  resting  nucleus  and  paired  nuclei  in  a  phrag- 
mosphere. 


JOURN.  R.  MICR.  SOC,  1920.     PI.   I 


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To  face  p.  8. 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  9 

Figs.  17-20. — Hippuris  vulgaris  L.     Axis  gathered  May  8,  1916. 

Fig.  17.— Cortical  cell,  with  nucleus  preparing  to  divide. 

,,  18. — Cortical  cell,  with  nuclear  spindle,  showing  chromosomes  at  the  poles. 

,,  19.— Cortical  cell,  with  phragmosphere  and  paired  nuclei. 

^,  20. — Endodermal  cell,  with  phragmosphere  and  paired  nuclei. 

Figs.  21-2i.—HeUa7ithus  Nuttallii  Torr.  and  Gray. 

Fig.   21.— One  pith  cell  with  two  nuclei,  one  of  which  is  degenerating,  at  3  cm. 

from  the  apex  of  a  shoot  gathered  June  9,  1915.     (To  economize 

space  the  outline  of  the  cell  is  not  completed.) 
^,      22. — The  nucleus  of  a  pith  cell  between  4  and  5  cm.  from  the  apex. 
„      23. — A  nucleus  of  a  pith  cell  1  cm,  from  the  apex. 
,,      24. — Two  nuclei  from  one  pith  cell  between  5  and  6  cm.  from  the  apex  of  a 

young  shoot  gathered  May  23,  1916. 

Figs.  25,  26. — Polygonum  cuspidatum  Sieb.  and  Zucc. 

Fig.   25. — Nucleus  of  a  stem  parenchyma  cell  preparing  to  divide. 
,,      26. — Phragmosphere  with  paired  nuclei  in  a  stem  parenchyma  cell. 

Figs.  27,  IQ'.^Asparagus  officinalis  L. 

Fig.   27. — Progressive  wall  formation  in  ground  tissue  cell. 
„      28. — Quadrinucleate  ground  tissue  cell. 

Figs.  29-S2.—Elodea  canadensis  Michx.     Gathered  June  2,  1916. 

Fig.   29.— Cortical  cell,  with  nucleus  in  process  of  division,  showing  chromo- 
somes. 
„      30. — Cortical  cell  of  stem,  with  phragmosphere. 
,,      31. — Epidermal  cell  of  stem,  with  phragmosphere. 
,,      32. — Lobed  nucleus  from  cortical  cell. 

Figs,  33-37. — Hemerocallis  fulva  L. 

Fig.  33. — Cell  of  ground  tissue,  with  one  normal  and  one  degenerating  nucleus, 

from  the  axis  just  below  a  young  inflorescence.     Gathered  May  24, 

1916. 
,,      34. — Cells  of  the   outer  epidermis   of   the   basal  part  of  a  leaf  gathered 

January  28,  1916 ;    seen  in  tangential  section,  showing  the  lobed 

nuclei. 
,,      35. — Other  lobed  nuclei,  from  the  same  epidermis  as  fig,  34. 
Figs.  36  A,  B.— Pairs  of  nuclei,  in  each  case  one  normal  and  one  degenerating, 

from  two  adjacent  ground  tissue  cells  of  the  axis  just  below  a  young 

inflorescence,  gathered  May  24,  1916. 
Fig.  37. — Pair  of  nuclei  from  one  ground  tissue  cell    of  the  axis  just^  below 

another  young  inflorescence,  gathered  May  21,  1916.     As  in  figs. 

36  A  and  B,  one  nucleus  is. normal  and  the  other  degenerating. 

Fig.  Z8.—Alisma  Plantago  L. 

Cell  from    the   lacunate  mesophyll  of    a    young    petiole,   gathered 
May  5,  1916,  showing  a  phragmosphere  with  paired  nuclei. 

Figs.  39  A,  B.—Monstera  deliciosa  Liebm. 

Fig.  39  A,— Cell  of  inner  cortex  of  aerial  root,  gathered  October  20, 1916,  showing 
phragmosphere  and  paired  nuclei. 
„     39  B.— Lobed  nuclei  from  conjunctive  tissue  of  stele  of  aerial  root,  gathered 
November  26,  1915  ;  4  to  5  mms.  from  root  apex. 


10  Transactions  of  the  Society. 

transverse  sections  through  the  apices  of  two  young  shoots.  In 
one  case  phragmospheres  and  paired  nuclei  were  first  seen  at  about 
0*20  mm.  from  the  apex.  At  this  level  the  section,  which  was 
irregular  in  outline  owing  to  the  leaf  rudiments,  was  only  0*22  to- 
0"26  mm.  in  diameter.  In  the  second  case  the  result  obtained 
was  of  a  similar  order,  a  phragmosphere  being  observed  in  the 
epidermis  at  0-24  mm.  from  the  apex. 

The  ground  tissue  of  the  "  head  "  is,  as  we  have  already  shown,, 
characteristically  binucleate,  but  further  down  the  axis  we  come 
to  a  region  in  which  most  of  the  cells  are  uninucleate.  The  transi- 
tion is  gradual  and  cannot  be  said  to  occur  at  any  fixed  level,  but^ 
in  a  shoot  gathered  early  in  May,  3  to  4  cm.  from  the  apex  is  a 
good  place  to  look  for  it.  Phragmospheres  have,  however,  been 
observed  at  nearly  6  cm.  from  the  apex,  and  the  binucleate 
character  is  very  persistent  in  the  case  of  individual  cells,  notably 
certain  small,  deeply  staining  elements  in  the  pith  which  probably 
contain  mucilage.  At  about  2*5  to  4*5  cm.  from  the  apex,  the 
nuclei,  which  are  mostly  single  in  the  cells,  begin  to  become  lobed 
and  irregular  in  outline  (PL  I,  fig.  13) ;  further  from  the  apex  the 
lobinsj  becomes  more  marked,  and  the  nuclei  become  flattened  and 
tend  to  lie  close  to  the  walls.  In  a  shoot  about  19  cm.  long  which 
was  examined,  single  nuclei,  more  or  less  irregular  in  outline,  were 
found  to  persist  to  the  base. 

The  question  of  how  the  transition  from  two  nuclei  to  one  takes 
place  is  extremely  difficult  to  answer.  As  in  the  case  of  Eremurus^ 
there  are  many  bilobed,  single  nuclei  to  be  found  whose  appear- 
ance at  first  glance  suggests  that  fusion  has  occurred,  and  sometimes 
two  nuclei  are  seen  lying  in  a  close  proximity  which  favours  this 
idea.  In  some  plants  the  number  of  nucleoli  might  be  a  guide  to 
whether  fusion  had  taken  place,  but  in  Asparagus  no  help  is  to  be 
looked  for  in  this  direction,  since  the  number  of  nucleoli  is  liable 
to  much  variation.  Por  instance,  in  the  same  section  four  cells 
were  observed,  each  with  a  pair  of  nuclei,  containing  nucleoli  in 
the  following  numbers  : — 1,  and  1 ;  2,  and  1 ;  2,  and  2  ;  3,  and  3. 
I  am  inclined  to  think  that  fusions,  if  they  ever  occur,  are  of 
entirely  subordinate  importance  in  reducing  the  number  of  nuclei, 
the  main  reason  for  this  opinion  being  that  the  bilobed  character^ 
which  is  so  conspicuous  a  feature  of  some  of  the  older  nuclei,  seems 
to  arise  gradually,  and  at  a  somewhat  later  stage  than  the  transi- 
tion from  two  nuclei  to  one.  The  importance  of  bilobing  is  also 
diminished  when  we  see  (as  in  PI.  I,  fig.  13)  tliat  it  is  not  universal, 
some  of  the  nuclei  being  lobed  quite  irregularly.  If  fusion  be 
excluded,  another  possibility  which  must  be  considered  is  the 
deferred  production  of  walls  between  the  paired  nuclei ;  but  of  this 
our  observations  have  furnished  no  evidence  whatever,  and  the 
probabilities  seem  to  be  altogether  against  such  an  occurrence. 
The  phragmoplast,  in  the  case  of  binucleate  cells,  was  converted 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  11 

into  a  phragmosphere  which  ultimately  became  merged  in  the 
general  cytoplasm,  so  it  is  difficult  to  see  what  apparatus  could  be 
brought  into  play  at  a  later  stage  to  produce  a  wall.  This  leaves 
us  with  a  third  alternative,  which  appears  to  have  most  in  its 
favour.  There  are  indications  that,  of  the  pair  of  nuclei  within  a 
single  cell,  one  is  apt  to  become  senile  more  rapidly  than  the  other^ 
and  we  sometimes  see  a  cell  containing  one  nucleus  in  fair  preser- 
vation, while  the  other  is  smaller,  somewhat  dense,  and  possibly  in 
process  of  disappearance.  But  we  have  been  imable,  in  spite  of 
repeated  attempts,  to  get  really  critical  evidence  on  this  point,  and,, 
though  the  degeneration  of  one  nucleus  seems  the  most  probable 
method  by  which  the  transition  from  two  nuclei  to  one  is  brought 
about,  we  cannot  regard  it  as  definitely  proved. 

Since  the  above  account  of  Asparagus  officinalis  was  written,  a 
recent  paper  by  Schiirhoff*  on  nuclear  fusions  in  the  shoot  apex  of  this 
plant  has  come  to  our  notice.  This  author  seems  to  have  overlooked 
the  multinucleate  condition  of  the  ground  tissue  in  general,  but  he 
describes  the  occurrence  of  "  nuclear  fusions  "  in  the  cells  at  the 
periphery  of  the  vascular  bundles,  after  these  have  become  bi- 
nucleate. He  states  that  he  has  not  determined  the  origin  of  the 
binucleate  condition  in  the  younger  stages,  but  that  in  older  stages 
it  occurs  through  the  breaking  down  of  the  partition  walls  between 
adjacent  cells.  I  have  examined  more  than  a  hundred  hand  and 
microtome  preparations,  stained  in  various  ways,  made  from  nine 
shoots  of  Asparagus,  mostly  of  the  age  of  those  used  by  Schiirhoff^ 
gathered  in  two  successive  years,  and  fixed  on  the  spot  with 
chrom-acetic  or  alcohol  acetic,  but  I  have  never  observed  any  in- 
dication of  the  breaking  down  of  walls  or  of  nuclear  migrations- 
such  as  he  describes.  On  the  contrary,  I  have  seen  paired  nuclei 
with  phragmospheres  in  the  ground-tissue  cells  at  the  periphery  of 
the  vascular  bundles,  which  are  apparently  the  elements  to  which 
he  refers ;  thus,  the  origin  of  the  binucleate  condition  is  precisely 
the  same  here  as  in  the  rest  of  the  ground  tissue.  The  "  fusions  '^ 
which  he  describes  are  no  doubt  the  lobed  nuclei  whose  significance 
we  have  already  fully  discussed. 

3.  Helianthus  Nuttallii  Torr.  et  Gray  (PL  I,  figs.  21-24). 

Young  axes  of  the  Perennial  Sunflower,  Helianthus  Nuttallii^ 
were  examined  at  stages  at  which  the  rudimentary  inflorescence- 
was  just  'becoming  differentiated  within  the  terminal  bud. 
Binucleate  cells  and  phragmospheres  were  found  to  make  their 
appearance  remarkably  near  the  tip  ;  in  the  case  of  one  axis^. 
which  was  cut  into  serial  sections,  the  first  phragmosphere  was 
seen  at  less  than  0  •  1  mm.  from  the  extreme  apex.     At  this  level 

*  Schiirhoff,  P.  N.  (1916). 


i2  Transactions  of  the  Society. 

there  was  no  sign  of  differentiation  of  vascular  tissue,  but  the 
phragmosphere  observed  occurred  in  the  central  region,  which  would 
subsequently  become  the  pith.  In  a  series  of  sections  through  a 
second  axis,  at  a  slightly  more  advanced  stage  than  the  first,  a 
typical  phragmosphere  with  its  paired  nuclei  was  seen  at  about  tlie 
same  distance  from  the  apex — in   this   case   slightly  more  than 

0  •  1  mm.  In  passing  down  the  axis  the  binucleate  cells  become 
rapidly  more  numerous.  In  an  axis  gathered  on  May  23  it  was 
"found  that,  at  1  cm.  from  the  apex,  binucleate  cells  were  extremely 
common  in  the  pith,  and  trinucleate  cells  also  occurred,  while 
occasional   binucleate   cells  were   seen  also   in  the  cortex.       At 

1  •  5  cm.  from  the  apex  a  large  proportion  of  the  pith  cells  had 
become  uninucleate.  Binucleate  cells,  however,  could  be  seen  as 
far  from  the  apex  as  the  ninth  centimetre,  but  they  steadily  became 
rarer,  and  in  the  tenth  centimetre  none  were  detected.  Variation 
in  the  length  of  the  binucleate  phase  occurs  in  different  shoots,  for 
in  another  axis  of  smaller  diameter  no  binucleate  cells  could 
be  found  even  in  the  sixth  centimetre. 

The  young  nuclei  of  Helianthiis  Nuttallii  are  rounded,  but  in 
the  region  in  which  the  transition  from  a  binucleate  to  a  uni- 
nucleate condition  takes  place  a  number  of  nuclei  can  be  seen 
whose  appearance  suggests  fusion  very  strongly  (PI.  I,  figs.  21  and 
22).  A  form  with  two  well-marked  pointed  lobes  is  decidedly 
characteristic.  Such  cases  as  that  drawn  in  PI.  I,  fig.  21,  appear 
however  to  invalidate  the  fusion  interpretation,  since  a  deeply 
bilobed  nucleus  may  sometimes  be  found  in  the  same  cell  as  a 
second  nucleus  which  is  either  normal  or  in  a  state  of  degeneration. 
It  is  conceivable,  though  unlikely,  that  such  a  case  might  represent 
the  subsequent  history  of  a  trinucleate  cell  in  which  two  nuclei 
•are  fusing  and  one  degenerating.  But  besides  symmetrically  bilobed 
nuclei,  we  also  find  examples  of  curiously  elongated  forms  (PI.  I, 
fig.  23),  and  of  lobing  into  two  highly  unequal  parts  (PI.  I,  fig.  24). 
Such  irregularity  detracts  very  much  from  the  probability  of  the 
fusion  hypothesis,  and,  as  in  the  other  cases  here  described,  it 
seems  that  the  transition  from  the  binucleate  to  the  uninucleate 
stage  comes  about  by  the  degeneration  of  one  nucleus  (PI.  I, 
fig.  21),  while  lobing  is  merely  a  characteristic  of  the  single  nuclei 
in  the  later  stages  of  their  career.  But  at  the  same  time  I  feel 
that  in  this  case  my  preparations  do  not  absolutely  dispose  of  the 
possibility  that  the  "  degenerating  "  nuclei  may  be  artefact. 

4.  Helianthus  tuherosus  L. 

Shoots  of  the  Jerusalem  Artichoke,  Helianthus  tuherosus  L., 
were  examined  for  comparison  with  H.  Nuttallii,  and  the  behaviour 
of  the  nuclei  was  found  to  be  closely  similar  in  the  two  cases. 
Binucleate  cells  begin  to  occur  very  near  the  apex  in  H.  tuherosus ; 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  IS 

the  first  phragmosphere  seen  in  serial  sections  through  an  apical 
bud  occurred  at  a  level  at  which  the  diameter  of  the  axis,  excluding 
the  leaf  bases,  was  less  than  0*5  mm.  This  phragmosphere 
occurred  in  the  rudimentary  vascular  zone,  which  was  just  becoming 
distinguishable  from  the  pith  by  the  form  of  the  cells  and  ther 
staining  power  of  the  nuclei  and  cytoplasm.  Binucleate  cells- 
rapidly  become  very  numerous,  and  at  1  cm.  from  the  apex  the- 
pith  contains  a  large  number  of  binucleate  and  some  trinucleate 
cells.  Binucleate  cells  occur  also,  though  less  frequently,  in  the 
cortex.  The  binucleate  phase  is  somewhat  protracted ;  phragmo- 
spheres  have  been  observed  at  19  cm.  from  the  apex  in  a  shoot 
gathered  on  June  5,  while  occasional  binucleate  cells  occurred  in 
the  outer  part  of  the  pith  at  80  cm.  from  the  apex  in  a  stem 
collected  on  June  20  in  a  previous  season.  The  change  from  the 
binucleate  to  the  uninucleate  condition  comes  about  through  the 
degeneration  of  one  nucleus.  Cells  showing  one  normal  nucleus, 
while  the  other  is  contracted  and  irregular  in  form  and  stains  deeply, 
have  been  observed  at  distances  of  1,  3,  and  5  cm.  from  the  apex. 
The  surviving  nuclei  are  often  bilobed,  the  lobes  being  sometimes 
acutely  pointed  as  in  H.  Nuttallii.  The  number  of  chromosomes 
is  large,  and  the  number  of  nucleoli  in  the  resting  nuclei  may  range 
from  1  to  8,  in  nuclei  observed  in  the  same  section. 


5.  Syringa  vulgaris  L. 

In  the  unbranched,  lateral  shoot  of  the  common  Lilac,  Syringa 
vulgaris*  the  binucleate  phase  is  well  represented.  Many  of  the 
pith  cells  are  bi-  or  even  tri-nucleate,  and  binucleate  cells  occur, 
though  less  freely,  in  the  smaller-celled  cortex.  These  lateral 
shoots  grow  to  a  considerable  length  in  a  single  season,  and  their 
interest,  from  our  point  of  view,  lies  in  the  fact  that  they  are 
characterized  by  binucleate  cells  throughout  a  remarkably  long 
region.  In  two  sets  of  serial  sections  through  different  apical  buds, 
the  first  phragmosphere  was  observed  in  each  case  at  about  0  •  1  mm. 
from  the  apex ;  while  in  a  shoot  gathered  on  June  19  binucleate 
cells  were  still  to  be  found  in  the  perimeduUary  zone  as  far  as  93  cm. 
from  the  apex.  The  binucleate  cells  still  persist  in  the  perimeduUary 
zone  after  the  inner  cells  of  the  pith  have  become  uninucleate  or  have 
lost  their  nuclei  altogether.  In  the  older  part  of  the  shoot,  the  pith 
nuclei  show  signs  of  decadence,  and  there  are  some  rather  obscure 
indications  that  in  the  case  of  cells  with  paired  nuclei  one  may 
degenerate  more  rapidly  than  the  other.  But  the  long  continuance 
of  the  binucleate  phase  makes  this  plant  an  unfavourable  subject 
for  following  out  the  fate  of  the  nuclei. 

*  Miss  Prankerd  (1916)  has  recorded  the  occurrence  of  binucleate  cells  in  the 
petiole  of  this  species. 


14  Transactions  of  the  Society. 

6.  Monstera  deliciosa  Liebm.  (PL  I,  figs.  39  A,  B). 

In  the  aerial  roots  of  Monstera  deliciosa  certain  cells  remain 
ibinucleate  for  a  very  long  time.  In  a  root  fixed  on  October  25, 
1915,  many  binucleate  cells  were  seen  in  the  inner  region  of  the 
<cortex  at  a  distance  of  1  to  2  mm.  from  the  apex.  At  a  little 
further  from  the  apex  occasional  cells  with  3,  or  even'4,  nuclei  were 
observed.  Phragmospheres  (PL  I,  fig.  39  A)  were  first  noticed  at 
about  4  mm.  from  the  apex.  In  order  to  see  how  far  back  the 
binucleate  cells  extended,  another  root  was  fixed  in  May  1916,  and 
it  was  found  in  this  case  that,  even  at  a  distance  of  38  cna.  from 
the  apex,  many  of  the  cells  of  the  inner  part  of  the  cortex  were 
binucleate.  Unfortunately  the  still  older  part  of  this  root  had  not 
heen  preserved.  Later  in  the  season  (in  August)  an  old  woody  root 
was  obtained ;  this  was  incomplete  at  the  apex,  but  the  part  that 
remained  was  58  cm.  long.  It  was  found  that  even  at  the  base  of 
this  root,  at  a  point  which  was  thus  probably  considerably  more 
than  58  cm.  from  the  apex,  occasional  binucleate  cells  still  occurred. 
At  this  stage  the  cortex  had  become  interspersed  with  thick- walled 
■fibres,  and  most  of  the  nuclei  had  disappeared.  The  nuclei  of  the 
surviving  binucleate  cells  had  become  angular  and  irregular  in 
form. 

In  the  conjunctive  tissue  of  the  young  stele  the  cells  are  uninu- 
cleate, but  the  nuclei  show  a  tendency  to  be  deeply  bilobed  (PL  I, 
fig.  39  B).  This  lobing  occurs  very  near  the  tip  of  the  root ;  it  has 
been  seen  at  a  distance  of  4  to  5  mm.  from  the  apex  in  an  apparently 
well-preserved  root,  and  we  do  not  think  it  can  be  dismissed  as  an 
indication  either  of  senility  or  of  imperfect  fixation.  It  closely 
recalls  the  lobing  of  the  nuclei  in  the  stelar  parenchyma  of  Stratiotes 
aloides*  roots  (see  pp.  19-21). 


7.  Hemerocallis  fidva,  L.  (PL  I,  figs.  33-37),  Nothoscordum 
fragrans  Kunth,  and  Alisma  Plantago  L.  (PL  I,  fig.  38). 

In  1880  Strasburgerf  stated  that  he  had  searched  unsuccessfully 
for  nuclear  "  Fragmentation  "  in  plants  belonging  to  seven  Mono- 
cotyledonous  genera  which  he  names.  He  enters  into  no  further 
details,  but  it  seems  probable  that  if  in  his  search  for  amitosis  he 
had  met  with  binucleate  cells,  he  would  have  mentioned  the  fact. 
It  was  therefore  decided  to  investigate  some  of  the  cases  to  which 
be  refers,  in  order  to  see  whether  they  were  really  exceptional  in 
this  respect.  Three  of  his  seven  cases  were  chosen  at  random, 
Hemerocallis  fxilva^  Nothoscordum  fragrans  and  Alisma  Plantago, 
and  it  was  found  that  all  three  showed  binucleate  cells  differing  in 

*  Arbor,  A.  (1914).  f  Strasburger,  E.  (1880). 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  15 

no  essential  respect  from  those  of  the  other  examples  described  in 
the  present  paper. 

|g  In  the  young  flowering  axis  oi  Hemerocallis  fidva  binucleate  and 
trinucleate  cells  are  common  in  the  ground  tissue,  and  I  have 
observed  prophase  and  spindle  stages  and  phragmospheres.  The 
chief  interest  of  this  plant  however  is  that  it  furnishes  particularly 
•definite  evidence  as  to  the  fate  of  the  nuclei ;  *  the  cells  apparently 
become  uninucleate  by  the  degradation  and  disappearance  of  one 
member  of  the  pair.  Pairs  of  nuclei  from  individual  cells,  one  of 
which  seems  to  be  degenerating  while  the  other  remains  more  or 
less  normal,  are  shown  in  PL  I,  figs.  33,  36,  and  37. 

I  have  also  examined  the  leaves  of  Hemerocallis  fulva,  and  have 
observed  binucleate  cells  and  phragmospheres  in  the  mesophyll  of 
the  basal  region  of  a  young  leaf.  This  is  the  growing  region,  as  I 
have  demonstrated  by  marking  off  the  leaf  with  Indian  ink  into 
zones  of  1  cm.  and  measuring  the  growth  of  the  zones.  The 
-epidermal  cells  show  a  peculiarity  which  may  be  mentioned  here. 
They  are  always,  so  far  as  I  have  been  able  to  observe,  uninucleate, 
and  in  the  younger  stages  the  nuclei  are  rounded,  but  later  on 
they  become  very  markedly  bilobed  (PL  I,  figs.  34  and  35).  This 
lobing  is  obviously  not  a  case  of  degeneration  or  senility,  as  it  occurs 
in  very  young  leaves  ;  I  have  found  it  for  instance  in  leaves  gathered 
on  January  28,  1916.  The  nuclei  are  sometimes  so  deeply  bilobed 
as  to  be  almost  bisected,  but  we  have  no  evidence  that  actual  division 
into  two  ever  takes  place.  The  lobing  is  probably  comparable 
with  that  observed  in  the  young  roots  of  Stratiotes.'\ 

Nothoscordum  fragrans  shows  very  numerous  binucleate  cells 
in  the  ground  tissue  of  the  young  inflorescence  axis.  One  or  two 
phragmospheres  with  paired  nuclei  wei:e  observed,  but  the  material, 
which  was  gathered  on  April  29,  was  probably  rather  too  old  to 
show  many  cells  in  process  of  becoming  binucleate.  The  resting 
nuclei  are  of  a  curious  irregular  form,  the  significance  of  which  I 
propose  to  consider  in  a  later  paper. 

I  have  examined  a  young  leaf  of  Alisma  Plantago  gathered 
on  May  5,  1916.  It  showed  some  typical  phragmospheres  with 
paired  nuclei  (PL  I,  fig.  38),  and  various  earlier  karyokinetic  stages. 
A  young  inflorescence  axis,  also,  was  collected  on  June  10.  Many 
cells  of  the  ground  tissue  were  binucleate,  but  the  material  was 
apparently  too  old  to  show  phragmospheres. 

8.  Polygonum  cusjpidatum  Sieb.  et  Zucc.  (PL  I,  figs.  25 
and  26). 

The  stem  of  Polygonum  cuspidatiim  Sieb.  et  Zucc.  was  ex- 
amined because  this  appears  to  be  the  plant  in  which,  under  the 

*  Beer,  R.  and  Arber,  A.  (1919),  p.  12.      f  Arber,  A.  (1914),  and  see  pp.  19-21. 


16  Transactions  of  the  Society. 

name  of  '*  Polygonum  Sieboldii,"  multinucleate  cells  were  described 
by  Grant.*  I  can  confirm  his  statement  that  the  ground  tissue  is 
multinucleate.  I  have  found  binucleate  cells  both  in  the  pith^ 
cortex  and  epidermis  of  the  relatively  young  internodes  ;  in  the 
pith  they  are  extremely  numerous.  But  my  observations  on  the 
origin  of  these  nuclei  fail  to  accord  with  those  of  this  author.  He 
writes,  "  In  this  plant  I  have  been  enabled  to  trace  the  formation 
of  the  multinucleate  condition  distinctly,  and  have  found  it  in  all 
cases  to  be  due  to  *  direct  division.'  "  I  have  observed  lobed  nuclei 
similar  to  those  figured  by  Grant,  especially  at  some  little  distance 
from  the  stem  apex,  but  I  regard  these  as  senile  phases,  or  possibly 
in  some  cases  the  results  of  poor  fixation,  rather  than  stages  of 
direct  nuclear  division.  In  both  pith,  cortex  and  epidermis, 
especially  in  the  younger  internodes,  the  formation  of  paired  nuclei 
with  associated  phragmospheres  (PL  I,  fig.  26)  has  been  observed. 
Various  karyokinetic  stages  showing  the  spindle  and  chromosomes 
have  also  been  noticed  (e.g.  the  prophase  seen  in  PI.  I,  fig.  25),  and 
there  thus  seems  no  reason  to  doubt  that  the  binucleate  condition 
originates,  as  in  the  other  cases  studied  by  Mr.  Beer  and  the 
present  writer,  by  karyokinesis  rather  than  by  the  amitosis 
described  by  Grant. 

I  can  confirm  Grant's  account  of  the  fusiform  and  sometimes 
extremely  elongated  nuclei  which  occur  in  the  elongated  vascular 
elements.  But  I  have  been  unable  to  detect  any  cases  of  the 
multinucleate  cells  described  by  this  author  as  occurring  in  tan- 
gential sections  of  the  vascular  bundles.  It  seems  possible  that 
Grant  mistook  the  nuclei  of  adjacent  elements,  of  very  narrow 
lumen,  for  nuclei  occurring  within  the  same  cell — a  mistake  which 
it  is  exceedingly  easy  to  make  in  the  case  of  these  longitudinal 
sections. 


Morus  nigra  L.  (PL  I,  figs.  12  A-C). 


Morus  nigra,  the  Mulberry,  is  one  of  the  species  in  which  Miss 
Prankerd  f  has  described  and  figured  the  occurrence  of  multinu- 
cleate cells  in  the  pith  and  cortex  of  the  axis.  She  considers 
it  probable  that  the  presence  of  more  than  one  nucleus  in  these 
cells  is  due  to  amitosis.  I  have  re-examined  this  plant,  and  am 
able  to  confirm  the  existence  of  multinucleate  cells  in  the  develop- 
ing axis.  I  have  found  definite  evidence,  however,  that  the 
increase  in  the  number  of  nuclei  comes  about,  as  in  other  cases 
described  in  the  present  paper,  by  karyokinesis.  Young  shoots  of 
Mulberry  were  fixed  on  May  8,  1916,  soon  after  the  buds  had 
expanded  ;  these  were  thus  probably  at  a  closely  similar  stage  to 
the  material  described  by  Miss  Prankerd,  which  was  gathered  on 
May  9,  1915.     In  both  pith  and  cortex  of  the  young  axis  spindle 

•  Grant,  A.  E.  (1886).  f  Prankerd,  T.  L.  (1916). 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell.  17 

stages  were  found  (PI.  I,  fig.  12  A),  and  also  paired  daughter  nuclei, 
in  telophase  and  in  resting  stages,  enclosed  in  phragmospheres 
(Plate  I,  figs.  12  B  and  12  C).  The  nuclei,  as  Miss  Prankerd  has 
already  recorded,  often  exceed  two  in  number  ;  I  have  seen  a  case 
of  a  nucleus  dividing  by  mitosis  in  a  cell  also  including  two  resting 
nuclei.  I  have  not  seen  in  my  preparations  any  group  or 
""  complex  "  of  nuclei  suggesting  an  origin  from  one  parent  nucleus 
by  direct  division,  such  as  that  figured  by  Miss  Prankerd  (I.e.  fig.  5), 
though  nuclei  were  often  seen  in  close  contact,  and  more  or  less 
overlapping  one  another.  It  is  possible  that  the  appearance  of  a 
'*  complex  "  may  be  brought  about  by  the  method  of  fixation  used. 
The  nuclei  of  Morus  have  one  or  more  nucleoli,  each  surrounded 
by  an  exceptionally  wide  clear  areola.  This  type  of  structure 
suggests  fragility,  and  these  nuclei  seem  in  practice  particularly 
sensitive  to  the  action  of  the  fixing'  agent.  I  have  found  that 
when  fixed  with  alcohol-acetic  the  nuclei  are  perfectly  distinct,  but 
chrom-acetic  acid,  which  evidently  does  not  suit  the  material,  gives 
curious  results ;  the  individuality  of  the  nuclei  in  a  cell  is  often 
obscured,  and  irregular  figures  are  obtained  which  might  easily  be 
mistaken  for  amitosis,  if  the  comparison  with  alcohol-acetic 
material  did  not  prove  them  to  be  artefact.  In  well-preserved 
material  I  have  often  seen  individual  nuclei  of  bilobed  form,  such 
as  those  figured  by  Miss  Prankerd  (I.e.  fig.  4  B),  but  I  have  found 
no  evidence  for  regarding  them  as  stages  in  direct  division.  A 
somewhat  similar  lobing  of  the  nuclei  observed  in  the  young  roots 
of  Stratiotes*  which  in  a  former  paper  I  described  as  an  indication 
of  amitosis,  I  now  interpret  differently  (see  pp.  19-21);  I  have  also 
observed  the  constant  occurrence  of  neatly  bilobed  nuclei  in  the 
young  epidermis  of  Hemerocallis  fulva,  but  here  again  the  lobing 
appears  to  have  no  connexion  with  direct  division  (see  p.  15). 

Miss  Prankerd  suggests  that  at  later  stages  the  transition  to 
a  uninucleate  condition  is  probably  brought  about  by  the  ultimate 
occurrence  of  deferred  wall  formation  between  the  nuclei  of  the 
binucleate  cells.  I  have  in  my  preparations  observed  nothing 
which  suggests  such  an  occurrence,  and  on  general  grounds  I  am 
inclined  to  regard  it  as  unlikely.!  On  comparing  the  basal  region 
of  an  opening  bud  gathered  on  May  8  with  that  of  a  long  shoot 
gathered  on  September  3,  it  was  found  that  the  total  diameter  had 
increased  by  80  p.c,  while  the  number  of  elements  on  the  greatest 
diameter  of  the  pith  had  increased  only  by  about  12  p.c.  This 
shows  that  the  increase  in  girth  during  the  season's  growth  is 
accompanied  by  relatively  little  cell  division.  I  have  further 
observed  that  the  mitosis  of  the  pith  nuclei  is  not  always  followed 

*  Arber,  A.  (1914). 

t  The  occurrence  of  wall  formation  after  amitosis  was  suggested  as  a  possi- 
bility in  my  former  paper  on  Stratiotes  (Arber,  A.  (1914)),  but  further  work  has 
convinced  me  that  this  idea  is  untenable. 

C 


18  Transactions  of  the  Society, 

by  the  formation  of  a  phragmosphere ;  cases  of  progressive  wall 
formation  have  also  been  noticed  sufficiently  frequently  to  account 
for  the  small  amount  of  cell  division  that  occurs  in  the  later  stages 
of  development  of  the  pith.  These  facts  taken  together  seem  to 
eliminate  the  possibility  of  subsequent  wall  formation  occurring: 
between  the  nuclei  of  binucleate  cells — unless  these  walls  are 
entirely  confined  to  horizontal  planes  and  are  thus  invisible  in 
transverse  sections. 

Morns  nigra  does  not  seem  to  be  a  particularly  favourable  plant 
for  studying  the  fate  of  the  nuclei.  My  observations  lead  me  to 
believe  that  in  many  cells  of  the  pith  the  binucleate  condition  i& 
very  persistent,  and  that  both  nuclei  perhaps  survive  in  some- 
of  the  cells,  as  long  as  these  elements  remain  nucleated  at  all.  In 
certain  cells,  on  the  other  hand,  I  have  observed,  in  September,, 
appearances  indicating  that  one  nucleus  becomes  moribund  while 
the  other  remains  normal.  I  am  thus  disposed  to  think  that  the 
transition  from  the  binucleate  to  the  uninucleate  condition  comes- 
about  in  the  same  way  as  in  the  other  plants  here  described,  but  I 
do  not  wish  to  lay  much  stress  upon  this  point,  as  my  results  in 
the  case  of  Morus  nigra,  if  taken  alone,  are  by  no  means  conclusive. 


10.  Eippuris  vulgaris  L.  (PL  I,  figs.  17-20),  and  Modea 
canadensis  Michx.  (PI.  I,  figs.  29-32). 

In  a  paper  published  in  1914  Dr.  McLean*  has  described 
amitosis  giving  rise  to  binucleate  cells  in  the  parenchyma  of  the 
young  stem  cortex  of  species  belonging  to  nine  different  genera 
of  flowering  plants  and  one  fern.  Since  the  observations  made  by 
Mr.  Beer  and  the  present  writer  on  a  number  of  other  genera  have^ 
as  we  have  already  shown,  indicated  that  the  general  origin  of  the 
binucleate  condition  is  through  karyokinesis,  I  have  re-examined 
two  of  Dr.  McLean's  cases.  As  Hippuris  vulgaris  is  the  species 
to  which  he  devotes  the  greatest  attention,  and  in  which  he  figures- 
the  binucleate  cells,  I  chose  this  plant  as  a  Dicotyledon,  and  Modea 
canadensis  as  a  Monocotyledon,  for  investigation. 

In  my  material  of  Jlipptcris  vulgaris  the  cortex  showed 
numerous  cases  of  paired  fusiform  nuclei  as  figured  by  Dr.  McLean. 
But  I  have  found  no  evidence  at  all  that  these  nuclei  arise  through 
direct  division,  and  I  have  seen  none  of  the  stages  of  "  longitudinal 
fission  "  which  he  describes.  But  on  the  other  hand  I  have  seen 
all  stages  of  karyokinesis  (e.g.  PL  I,  figs.  17  and  18),  and,  finally, 
pliragraospheres  with  the  paired  nuclei  at  rest  (PL  I,  figs.  19  and 
20).  The  nuclei  are  exceptionally  small,  as  will  be  recognized  on 
comparing  PL  I,  figs.  17-20,  which  represent  them,  with  those,  for 

♦  McLean,  R.  C.  (1914). 


Studies  on  the  Bi7iucleate  Phase  in  the  Plant-cell.  19 

instance,  of  Eremurus  himalaicus  (e.g.  PL  I,  fig.  1),  which  are 
magnified  to  the  same  degree.  This  fact,  and  a  certain  difficulty 
which  is  experienced  in  staining  the  nuclei  satisfactorily,  probably 
accounts  for  the  karyokinetic  stages  and  phragmospheres  having 
been  overlooked  by  Dr.  McLean,  who  says,  "  Amitosis  is  the  only 
form  of  nuclear  division  which  has  been  recognized  in  the  tissues 
investigated,  and  from  its  exceeding  frequency  in  the  constituent 
cells  it  may  be  inferred  that  it  is  the  only  form  occurring  there." 
In  all  Dr.  McLean's  figures  the  process  of  nuclear  division  is  already 
completed ;  the  fact  that  the  pairs  of  nuclei  lie  close  together  does 
not  supply,  as  far  as  my  experience  goes,  any  evidence  for  amitosis, 
since  I  have  often  observed  the  approximation  of  the  paired 
nuclei  in  cases  in  which  their  karyokinetic  origin  has  been  proved. 
Elodea  canadensis  presents  no  essential  differences  from 
Hippiiris  vulgaris.  In  the  region  towards  the  apex  of  an  axis 
fixed  on  June  2,  1916,  binucleate  cells  were  numerous,  especially 
just  above  the  nodes.  Many  nuclei  were  observed  in  mitosis 
(PI.  I,  fig.  29),  and  phragmospheres  occurred  both  in  the  cortex 
and  the  epidermis  (PL  I,  figs.  30  and  31).  There  appears  to  be  no 
evidence  of  amitosis,  but  I  have  seen  some  lobed  nuclei  (PL  I, 
fig.  32)  which  might  at  first  sight  suggest  that  direct  division 
was  in  progress.  However  from  analogy  with  Asparagus  and 
Eremurus,  in  which  I  have  been  able  to  follow  their  history  more 
closely,  I  think  that  these  lobed  nuclei  are  probably  merely  senile. 


11.  Stratiotes  aloides  L.  (Text-figs  1,  2). 

In  a  note  published  some  years  ago*  I  gave  an  account  of  certain 
cytological  peculiarities  observed  in  the  roots  of  Stratiotes  aloides, 
the  Water  Soldier.  Further  work  on  this  subject,  in  the  light  of 
the  results  obtained  in  other  connexions,  has  greatly  modified  the 
conclusions  there  expressed.  The  principal  feature  to  which  atten- 
tion was  drawn  was  the  constant  occurrence  of  bilobed  nuclei  in 
the  tissues  of  the  young  roots,  especially  in  the  vascular  cylinder. 
Examination  of  further  material  has  confirmed  the  view  that  this 
lobing  is  natural  and  not  artefact.  Examples  are  shown  in  text- 
figs.  1  and  2.  A  certain  number  of  binucleate  cells  were  also 
observed — chiefly  in  the  cortex — and  it  was  supposed  that  amitosis 
took  place  and  that  the  paired  nuclei  arose  through  the  bilobed 
nuclei  becoming  nipped  in  two.  But  a  further  search  through 
material  collected  in  two  later  seasons  has  shown  that  binucleate 
cells  arise  in  the  root  cortex  of  Stratiotes,  just  as  in  other  cases 
described  in  the  present  paper,  by  karyokinesis  associated  with  a 
phragmosphere.     Owing   to   the  small  size  of  the  cells  and  the 

*  Arber,  A.  (1914). 

C   2 


20 


Transactions  of  the  Society. 


relatively  large  size  of  the  nuclei,  these  phragmospheves  are 
somewhat  obscure,  but  at  the  same  time  their  identity  cannot  be 
questioned.* 

Paired  nuclei  and  phragmospheres  have  not  only  been  found 
near  the  apex  of  the  roots,  but  also  in  the  cortex  of  a  young  stolon 


Fig.  l.—Stratiotes  aloides  L.    Lobed  nuclei  from  parenchyma  cells 
of  stele  of  young  root,     x  535,  circa. 


Fig.  2. — Stratiotes  aloides  L.  Young  vessel  surrounded  by  parenchyma 
cells  with  lobed  nuclei  from  transverse  section  of  a  young  root. 
X  535,  circa. 

and  the  mesophyll  of  a  young  leaf.  Owing  to  the  larger  size  of 
the  cells,  the  phragmospheres  here  attain  to  a  more  typical  develop- 
ment than  in  the  case  of  the  roots. 

Further  work  has  shown  that  the  bilobing  of  the  root  nuclei  is 
more  widespread  than  was  believed  when  the  previous  paper  was 
written  ;  it  occurs  not  only  in  young  roots,  but  in  roots  of  all  ages, 
being  found,  for  instance,  from  base  to  apex  in  a  root  73  cm.  long, 

•  Beer,  R.  and  Arber,  A.  (1919),  PI.  I,  fig.  29. 


Studies  on  the  Binucleate  Phase  in  the  Plant-cell,  21 

in  which  it  occurred  in  the  stele — in  the  conjunctive  tissue,  xylem, 
parenchyma  and  companion  cells — and  also  in  the  cortex.  It 
now  seems  probable,  however,  that  the  bilobing  rarely,  if  ever, 
goes  so  far  as  to  give  rise  to  complete  division,  and  thus  the  roots 
of  Stratiotes  can  no  longer  be  claimed  as  furnishing  examples  of 
amitosis. 


List  of  Memoirs  Cited. 

Arber,  a.  (1914). — On  Root  Development  in  Stratiotes  aloides  L.      Proc, 

Camb.  Phil.  Soc,  xvii.  (1914)  pp.  369-79  (2  pis.). 
Beer,  R.  &  Arber,  A.  (1915). — On  the  Occurrence  of  Binucleate  and  Multi- 
nucleate Cells  in  Growing  Tissues.     Ann.  Bot.,  xxix.  (1915)  pp.  597-8. 
(1919). — On  the  Occurrence  of  Multinucleate  Cells  in  Vegetative 

Tissues.     Proc.  Roy.  Soc,  B,  xci.  (1919)  pp.  1-17  (1  pi.  2  text-figs.). 
Grant,  A.  E.  (1886).— The  Multinucleated  Condition  of  the  Vegetable  Cell, 

with  some  special  Researches  relating  to  Cell  Morphology.     Trans. 

Bot.  Soc.  Edinburgh,  xvi.  (1886,  read  June   1883)    pp.  38-52  (pis. 

vand  vi). 
McLean,  R.  C.  (1914). — Amitosis  in  the  Parenchyma  of  Water-plants.    Proc. 

Camb.  Phil.  Soc,  xvii.  (1914)  pp.  380-2  (1  text-fig.). 
Nemec,  B.  (1910). — Das  Problem  der  Befruchtungsvorgange.     Berlin  (1910) 

532  pp.  (119  text-figs,  5  pis.). 
Prankerd,  T.  L.  (1915).— Notes  on  the  Occurrence  of  Multinucleate  Cells. 

Ann.  Bot.,  xxix.  (1915)  pp.  599-604  (8  text-figs.). 
ScHiJRHOFF,  P.  N.  (1916). — Kernverschmelzungen  in  der  Sprossspitze  von 

Asparagus  officinalis.     Flora,  N.F.  Bd.  9,  G.R.  Bd.  109  (1916)  pp. 

55-60  (1  pi.). 
Strasburger,  E.  (1880). — Einige  Bemerkungen  liber  vielkernige  Zellen  und 

liber  die  Embryogenie  von  Lujpinus.     Bot.    Zeit.,  Jahrg.  38  (1880) 

pp.  845-54,  857-68  (1  pi.). 
Treub,  M.  (1879). — Quelques  recherches  sur  le  role  du  noyau  dans  la  division 

des  cellules  vegetales.     Verhandel.  d.k.  Akad.  van  Wetenschappen, 

xix.  (Amsterdam,  1879)  35  pp,  (4  pis.). 


23 


II. — On  Multimccleate  Cells  :  An  Historical  Study  {1879-1919), 
^j  Rudolf  Beer  and  Agnes  Arber. 

{Bead  February  18,  1920). 

"The  idea  of  the  cell,  as  the  fundamental  unit  in  the  bodies  of  all 
organized  beings,  has  now  become  so  deeply  ingrained  into  all  our 
biological  thought,  that  there  is  a  danger  of  our  treating  the  cell- 
theory  and  its  associated  corollaries  rather  as  rigid  axioms  than  as 
truths  which  are  still  in  process  of  disclosure.  It  is,  after  all,  only 
eighty  years  since  the  publication  of  Schwann's  epoch-making 
■*'  Microskopische  Untersuchungen,"  and  it  may  be  well  to  remind 
ourselves  from  time  to  time  that  the  history  of  the  cell-theory  has 
been  so  brief  that  our  general  notions  of  the  construction  of  the 
-cell  and  of  the  relation  of  its  parts  must,  for  many  years  to  come, 
be  open  to  criticism  and  revision. 

For  more  than  a  century  and  a-half  after  the  first  discovery  by 
Hobert  Hooke  of  the  cellular  structure  of  plants  the  attention  of 
microscopists  was  almost  exclusively  devoted  to  the  cell  membrane. 
It  was  not  until  1833  that  Robert  Brown  observed  a  nucleus  in 
the  cells  of  a  number  of  plant  tissues,  his  earliest  records  relating 
to  certain  orchids.  This  discovery  marks  the  first  step  towards  a 
proper  appreciation  of  the  protoplasmic  content  of  the  cell  as  its 
<essential  component.  The  conception  of  the  typical  cell  as  a  uni- 
nucleate structure  is  often  treated  at  the  present  day  as  if  it  were 
a  self-evident  proposition,  the  truth  of  which  could  be  established 
on  a  priori  grounds.  It  should  be  remembered,  however,  that  it  is 
really  an  idea  which  was  arrived  at  inductively  by  the  earlier 
cytologists,  and  which  rests  entirely  on  accumulated  observations. 
It  was  Nageli,  in  1844,  who  first  definitely  formulated  the  now 
familiar  view  as  to  the  uninucleate  character  of  the  vegetable  cell. 
He  concluded,  from  his  extensive  researches,  that,  with  the 
'exception  of  cells  in  the  act  of  division,  pollen  grains,  pollen  tubes 
and  embryo  sacs,  each  element  contains  only  a  single  nucleus. 
Further  research  has  modified  and  elaborated  the  list  of  organs  that 
oome  under  the  head  of  Nageli's  exceptions.  The  literature  of 
botany  for  the  three-quarters  of  a  century  which  has  passed  since 
his  work  was  published  includes  extensive  references  to  the 
appearance  of  the  multinucleate  character  in  the  structures  to 
which  he  refers,  and  also  in  the  pro-embryo  of  the  Gymnosperms, 
suspensor  cells,  tapetal  tissues,  etc.     But  his  central  conception  of 


24  Transactions  of  the  Society. 

the  uninucleate  nature  of  the  typical  vegetative  cell  has  remained 
one  of  the  most  firmly  established  of  botanical  beliefs.  From  time 
to  time  cases  have  been  brought  to  light  indicating  that  it  is  not  of 
universal  application,  but  such  cases  have  until  recently  been 
regarded,  even  by  the  observers  who  drew  attention  to  them,  as- 
mere  exceptions  proving  the  rule,  and  Nageli's  position  has  thus^ 
remained  almost  unchallenged.  But  when  we  discuss  modern 
developments  in  the  later  part  of  this  paper,  it  will  be  recognized 
that  in  young  tissues  the  occurrence  of  a  binucleate  or  multinu- 
cleate phase  is  too  common  to  be  dismissed  as  a  mere  exception,, 
but  must  be  treated  as  a  normal,  and  possibly  almost  universal, 
phase  in  the  life  of  the  plant. 

We  propose  here  to  give  a  brief  sketch  of  the  work  of  those- 
observers  who,  since  the  time  of  Nageli,  have  recorded  the  occur- 
rence of  more  than  one  nucleus  in  the  vegetative  cells  of  the. 
higher  plants.  We  shall  entirely  omit  from  this  survey,  the  litera- 
ture dealing  with  those  recognized  exceptions  to  the  uninucleate 
rule  to  which  Nageli  was  the  first  to  refer ;  these  exceptions  have 
chiefly  been  observed  in  connexion  with  reproductive  structure&> 
such  as  endosperms,  tapetal  cells,  etc.,  and  hence  have  no  direct 
bearing  on  our  notions  concerning  ordinary  vegetative  tissues.  We 
shall  also  omit  any  account  of  cases  among  the  Thallophyta,  and 
of  pathological  examples. 

Disregarding  certain  early  references  to  binucleate  cells,  which 
are  probably  mere  errors  due  to  indifferent  optical  appliances  and 
a  rather  vague  conception  of  the  nucleus,  we  find  that  the  earliest 
record  of  the  occurrence  of  more  than  one  nucleus  in  the  purely- 
vegetative  cells  of  a  Phanerogam  is  due  to  Schmitz  (1879),  who 
observed  this  phenomenon  in  the  older  parenchyma  cells  of  Glyceria 
aquatica,  Taraxacum  officinale,  etc.  He  had  examined  the  Algte 
widely  from  this  point  of  view,  and  his  notes  on  Angiosperms  were 
merely  a  side  issue,  but  he  prophesied  that  further  work  would 
reveal  the  presence  of  multinucleate  cells  in  a  larger  number  of 
the  higher  plants.  He  also  placed  on  record  the  observation  of 
another  worker  in  the  same  laboratory  (E.  Schmidt),  that  numerous 
nuclei  occurred  in  the  tubular  latex  cells  of  Euphorhia. 

The  next  year  Treub  (1880)  published  independent  observations 
on  the  same  subject.  He  states  that  the  large  cells  of  the  paren- 
chyma of  Cereus  rmtltiangularis  were  in  several  cases  seen  to 
contain  two  nuclei,  and  the  same  thing  was  noted  in  Tradescantict 
hypoplisea.  In  the  pith  of  Ochrosia  coccinea  long  cells  occur, 
the  walls  of  which  eventually  become  considerably  thickened.  In 
these  cells,  when  young,  Treub  found  constantly  as  many  as  five  to 
eight  nuclei ;  after  the  thickening  of  the  walls  was  completed  the 
nuclei  were  no  longer  distinct.*  A  comparable  multinucleate  stage 
was  described  many  years  later  in  the  case  of  the  woody  cells  of  the 

•  Pigott,  E.  M.  (1915). 


Multinucleate  Cells  :  An  Historical  Study  {1879-1919).     25 

ovary  wall  in  one  of  the  Araliaceae.  "  The  instances,"  Treub  writes, 
"  of  cells  with  two  or  more  nuclei ....  perhaps  deserve  some  interest 
as  exceptions  to  a  rule  hitherto  believed  general.  However,  they 
may  very  well  merely  be  more  or  less  frequent  abnormalities,  and 
hence  they  cannot  serve  as  the  basis  for  any  theoretical  deduction." 
Probably  Treub's  most  important  discovery  was  the  constant  occur- 
rence of  numerous  nuclei  in  the  bast  cells  and  laticiferous  tubes  of 
a  large  number  of  plants.  In  both  types  of  element  the  nuclei 
multiplied  by  mitotic  division.  He  states  that  there  is  a  tendency 
for  many,  if  not  all,  of  the  nuclei  of  one  cell  to  divide 
simultaneously. 

In  the  same  year  Johow  (1880)  described  multinucleate  cells 
in  the  older  tissues  of  several  Monocotyledons.  He  gave  most  of 
his  attention  to  the  internodal  parenchyma  cells  of  Tradescantia^ 
in  which  he  believed  that  the  plurality  of  nuclei  arose  through 
amitotic  division.  Strasburger  (1880)  confirmed  this  conclusion, 
and  Tradescantia  has  since  remained  one  of  the  classic  examples  of 
amitotic  division,  being  used  as  an  illustration  of  this  phenomenon 
in  every  botanical  laboratory.  But,  as  we  have  shown  in  a  recent 
paper,*  we  believe  that  many  (if  not  all)  of  the  cases  of  amitotic 
division  in  this  plant,  which  have  been  figured  and  described,  are 
merely  instances  of  changes  of  form  in  the  nuclei,  not  necessarily 
bearing  any  relation  either  to  division  or  fusion. 

In  several  other  Monocotyledons  Johow  obtained  similar 
results.  He  observed  lobed  nuclei,  which  he  interpreted  as  cases 
of  amitosis,  in  the  inner  tissues  of  the  leaf  of  Allium  cepa, 
constricted  nuclei  in  the  floral  axis  of  Orchis  raaculata,  fragmented 
(zergliederte)  nuclei  in  the  scape  of  Tulijoa  sylvestris,  and  nuclei 
in  the  petioles  of  Anthurium  sagittatum  which  were  traversed  by  a 
narrow  hyaline  strip  suggesting  direct  division.  All  these  cases 
we  now  regard,  however,  not  as  instances  of  amitosis,  but  as 
coming  under  the  same  interpretation  as  that  which  we  have 
indicated  for  Tradescantia. 

In  a  later  paper  (1881)  Johow  added  several  other  instances 
of  the  occurrence  of  multinucleate  cells  in  the  older  tissues  of 
Monocotyledons.  He  observed  such  cells  in  the  inflorescence  axis 
of  Hyadnthus  orientalis  and  in  the  older  leaves  of  Sempervivum 
Wulfeni. 

At  about  the  same  time  Strasburger  (1880)- also  contributed 
some  observations  upon  the  same  subject.  Like  Johow  he- 
considered  that  a  fragmentation  of  the  nuclei,  often  leading  to 
a  multinucleate  condition,  was  a  widespread  phenomenon  in  the 
older  cells  of  Monocotyledons.  In  the  tissues  of  Dicotyledons 
he  found  nuclear  fragmentation  to  be  much  rarer.  He  however 
figured  lobed  nuclei  in  the  very  old  pith  cells  of  Tropdeolummajus 
and  what  is  probably  a  pair  of  nuclei  lying  closely  approximated 

*  Beer,  R.  and  Arber,  A.  (1919). 


26  Transactions  of  the  Society. 

in  Nicotiana  Tahacum.  In  discussing  these  two  cases  of  lobed 
and  fragmented  nuclei,  he  expressly  remarks  that  they  only  occur 
*'  in  very  old  cells  shortly  before  the  total  disorganisation  of  the 
nuclei.  Cells  with  lobed  nuclei  are  therefore  distributed  between 
others  which  have  become  entirely  devoid  of  a  nucleus.  Only 
very  rarely  does  this  constriction  of  a  nucleus  lead  to  its  complete 
division.  Multinucleate  cells  are,  therefore,  only  met  with  very 
■occasionally."  Strasburger  also  observed  lobed  nuclei  in  the 
vessels  of  Bryonia  dioica  at  the  time  that  their  membranes  are 
becoming  thickened. 

In  1886  a  paper  by  A.  E.  Grant  appeared,  which  has  since 
been  almost  entirely  overlooked,*'  and  with  which  we  shall  therefore 
deal  at  greater  length  than  if  it  had  received  due  recognition.  In 
this  memoir,  which  is  entitled  "  The  Multinucleated  Condition  of 
the  Vegetable  Cell,"  the  author  records  the  occurrence  of  more 
than  one  nucleus  in  the  cells  of  the  following  species  : — Polygonuwy 
JSieboldii,  Acanthus  mollis,  Podophyllum  peltatum,  Eschscholtzia 
calif ornica,  Impatiens  noli-me-tangere,  Dictamnus  fraxinella,  Lilium 
pyrenaicumsiiidFolygonaJu7nmultiflorum.  He  found  the  plurality 
of  nuclei  in  the  bast  cells,  the  wood  cells  and  the  parenchymatous 
ground  tissue  of  the  stem,  and,  in  the  case  of  Acanthus  mollis,  in 
the  parenchyma  of  the  petiole.  Grant  was  unable  to  detect  any 
evidence  for  the  existence  of  mitosis,  and  he  concluded  that  in  all 
these  cases  the  multiplication  of  the  nuclei  takes  place  by  direct 
division ;  he  figures  and  describes  lobed  nuclei  in  support  of  this 
view.  He  took  a  remarkably  broad  view  of  his  results,  and  his 
paper,  which  was  written  thirty-six  years  ago  (having  been  read 
three  years  before  it  was  published),  does  not  deserve  the  oblivion 
into  which  it  has  fallen. 

Before  passing  on  to  the  more  recent  work  on  multinucleate 
parenchyma  cells,  we  may  deal  with  a  series  of  observations  on  a 
multinucleate  condition  observed  in  the  young  vessels  of  certain 
plants.  In  the  development  of  the  larger  pitted  vessels  of  the 
Dioscoreacese,  Pirotta  and  Buscalioni  (1898)  observed  a  multi- 
nucleate phase  in  the  vessel  initials.  The  'vessels  develop  from 
longitudinal  series  of  cells  which  are  at  first  isodiametric,  but 
-which  ultimately  become  elongated  by  marked  intercalary  growth. 
The  nuclei  of  these  elements  are  at  first  single,  but  they 
subsequently  divide  so  that  each  cell  may  finally  possess  more 
than  a  hundred  nuclei.f  The  primary  and  secondary  divisions 
are  all  mitotic,  but  afterwards  the  process  does  not  always  proceed 
normally.     Eventually   the  nuclei,  cytoplasm   and   parts   of  the 

*  We  were  unacquainted  with  this  paper  at  the  time  that  our  preliminary 
note  was  published,  Beer,  R.  and  Arber,  A.  (1915). 

t  Hill,  T.  G.  and  Freeman,  Mrs.  W.  G.  (1903),  give  an  account  of  the  origin  of 
plurality  of  nuclei  in  the  root  vessels  of  Dioscorea  prehensilis  which  conflicts  with 
that  of  Pirotta  and  Buscalioni,  but  the  Italian  observers'  work  is  much  more 
widely  based,  and  its  accuracy  may  probably  be  accepted. 


Multinucleate  Cells  :  An  Historical  Study  (1879-1919).      27 

transverse  walls  are   resorbed,  and  the  characteristic  sculpturing 
is  formed.    • 

In  several  species  of  Euphorhia  and  Bicinus,  the  young  plerome 
elements  of  the  root,  destined  to  form  the  segments  of  the  vessels, 
were  observed  by  Smolak'(1904)  to  be  quadrinucleate.  He  found 
that  the  plurality  of  nuclei  in  the  vessel  initials  arose  by  mitotic 
divisions  which  were  not  followed  by  cell  divisions  or  wall- 
formation.  The  four  nuclei  sometimes  fused  into  one  long  nucleus, 
e.g.  Euphorhia  Lathyris,  but  in  Bicinus  fusions  were  less  frequent. 

Nemec  (1910)  six  years  later  made  a  comprehensive  study  of 
the  multinucleate  vessel  rudiments  and  plerome  cells  of  Bicinus. 
He  likewise  found  that  the  nuclei  arose  by  karyokinesis.  A 
spindle  is  produced  between  the  nuclei  at  each  division,  but  this 
breaks  down  at  an  early  stage,  becomes  granular,  and  soon 
disappears  altogether.  From  two  to  sixteen  nuclei  may  be  found 
in  a  single  cell,  generally  arranged  in  a  longitudinal  row.  Nuclear 
fusions  may  occur,  but  Nemec  regards  them  as  rare. 

We  have  now  to  consider  that  group  of  papers  on  multinucleate 
parenchymatous  cells  which  includes  the  most  recent  work  on  the 
subject.  Twenty  years  ago,  one  of  us  (Beer,  K.,  1899)  recorded  the 
fact  that  multinucleate  cells  of  a  very  pronounced  character  occur 
in  the  stem  and  leaf-sheaths  of  a  number  of  Graminese.  He  found 
this  to  be  the  case  in  Zea  Mays  (stem,  leaf-sheath  and  root),  Secale 
cereale  (leaf- sheath),  Triticum  vulgare  (stem  and  leaf-sheath), 
Hordeuni  sativum  (leaf-sheath),  and  Dactylis  glomerata  (leaf-sheath). 
He  called  attention  to  the  fact  that  it  is  in  young,  still  active 
tissues  that  the  multinucleate  condition  is  most  marked. 

In  1914  Dr.  E.  C.  McLean  published  an  account  of  his 
observations  upon  amitosis  in  the  parenchyma  of  water  plants. 
He  found  that  nuclei  which  he  regarded  as  having  arisen  through 
direct  division  were  frequently  to  be  found  associated  in  pairs  in 
the  same  cell,  while,  moi-e  rarely,  three  nuclei  might  be  met  with 
in  one  cell.  Certain  stages,  which  the  author  regards  as  represent- 
ing the  actual  separation  of  the  two  daughter  nuclei,  were  observed. 
According  to  McLean's  description,  no  constriction  occurs,  but 
the  process  resembles  the  longitudinal  fission  of  the  Flagellata. 
His  observations  relate  to  eight  aquatic  species,  including  both 
Dicotyledons  and  Monocotyledons,  as  well  as  to  two  land  plants, 
Dionsea  muscipula  and  Polypodium  ireoides.  He  believes  that 
cell-division  may  follow  the  amitotic  division  of  the  nucleus,  but 
he  does  not  describe  this  in  any  particular  case.  We  chose  two  of 
McLean's  cases  for  re-examination  {Hippuris  and  Elodea),  and 
although  we  can  confirm  his  record  of  multinucleate  cells  in  both 
plants,  we  find  that  the  nuclei  in  question  invariably  arise  by 
mitosis  and  not  by  direct  division.* 

*  Arber,  A.  (1920). 


28  Transactions  of  the  Society. 

Simultaneously  with  McLean's  paper  one  of  us  (Arber,  A.,  1914} 
described  multinucleate  cells  and  lobed  nuclei  in  Stratiotes  aloides. 
The  root-cap  of  a  young  adventitious  root,  and  certain  cells  of  the 
stem  cortex  through  which  it  was  dissolving  its  way,  were  observed 
in  some  instances  to  be  highly  multinucleate,  as  many  as  twelve 
nuclei  being  observed  in  one  case  in  a  single  cell  of  the  root-cap, 
Lobed  nuclei  are  notably  frequent  in  the  conjunctive  tissue  of  the 
stele.  Further  work  on  Stratiotes  has  convinced  us  that  the 
conclusions  expressed  in  this  paper  as  to  the  part  played  by 
amitosis  require  revision ;  we  have  now  observed  the  origin  of  the 
binucleate  condition  through  karyokinesis,  and  we  regard  the 
lobing,  which  was  formerly  supposed  to  be  a  precursor  of  amitosis, 
as  having  no  connexion  with  any  division.* 

A  year  later  than  the  appearance  of  the  two  papers  which  we 
have  just  considered,  Miss  Prankerd  (1915)  published  an  account 
of  her  researches  on  multinucleate  cells.  She  recorded  the 
occurrence  of  elements  with  more  than  one  nucleus  in  thirty-six 
species  of  plants  "  widely  separated  in  habit,  habitat,  and  systematic 
position,"  including  both  Vascular  Cryptogams  and  Angiosperms. 
The  plurality  of  nuclei  was  observed  sometimes  in  the  pith, 
sometimes  in  the  cortex,  and  sometimes  in  both  tissues.  It  was 
also  found  in  the  mesophyll  of  some  plumular  leaves  (e.g.  Zizania 
aquatica)  and  in  the  ground  tissue  of  certain  Ferns  and 
Monocotyledons.  Binucleate  cells  were  usually  found,  but  in 
certain  cases  (e.g.  Armn  maculatifjii,  Limnanthcmuni  jpeltatiim, 
Zizania  aquatica  and  Morus  nigra)  three  or  even  more  nuclei 
could  be  observed  in  some  of  the  cells.  It  was  found  that  the 
multinucleate  elements  tend  to  occur  in  regions  of  activity 
(cotyledonary  nodes  of  seedlings)  and  of  rapid  elongation  (axes  of 
buds).  Miss  Prankerd  considers  that,  in  general,  the  plurality  of 
nuclei  arises  by  amitosis.  We  have  re-examined  certain  of  the 
species  with  which  Miss  Prankerd's  studies  were  concerned,  and 
again — as  in  the  case  of  Grant's  and  McLean's  work — we  find  that 
we  can  confirm  the  existence  of  the  multinucleate  phase,  but  that 
our  observations  point  entirely  to  mitosis,  and  not  direct  division, 
as  the  mode  of  origin  of  the  extra  nuclei. t 

In  the  same  issue  of  the  Annals  of  Botany  as  that  in  which 
Miss  Prankerd's  paper  appeared,  we  published  a  preliminary  note 
dealing  with  the  same  subject  (Beer,  R.  and  Arber,  A.,  1915).  We 
recorded  a  plurality  of  nuclei  in  the  young  parenchymatous  tissues 
of  seventy-six  species,  chiefly  Angiosperms,  but  including  also  a 
Gymuosperm  and  a  Vascular  Cryptogam.  This  phenomenon 
seemed  to  us  so  widespread  that  we  suggested  the  possibility  that 
a  binucleate  or  multinucleate  stage  might  often  intervene  as  a 
normal  phase  of  development  between  the  meristematic  and  adult 

*  Arler,  A.  (1920).  t  Ibid. 


Multinucleate  Cells :  An  Historical  Study  (1879-1919).       29 

conditions.  The  main  difference  between  our  results  and  those  of 
the  other  authors  quoted  is  tliat,  according  to  our  observations,  the 
plurality  of  nuclei  arises,  not  by  aniitosis,  but  by  a  process  of 
karyokinesis  with  which  certain  peculiar  features  are  associated. 
In  1919  we  published  a  fuller  paper  *  in  which  we  dealt  on  broad 
lines  with  the  occurrence  of  multinucleate  cells  in  vegetative 
tissues.  We  recorded  the  occurrence  of  more  than  one  nucleus — 
two  being  the  commonest  number — in  the  young  parenchymatous 
tissues  of  177  species  representing  60  families,  including  members 
of  the  Filicales,  Equisetales,  Lycopodiales,  Psilotales,  Isoetales, 
Gymnosperms,  Monocotyledons  and  Dicotyledons.  Our  observa- 
tions related  chiefly  to  stems,  but  w^e  also  found  a  binucleate  phase 
in  leaves  and  roots.  It  is  most  conspicuously  developed  in 
parenchymatous  tissues,  such  as  the  cortex  and  pith  of  the  axis, 
and  the  mesophyll  of  the  leaf,  but  we  have  also  seen  it  in  the 
central  cylinder.  The  "  heads  "  of  Asparagus,  at  the  stage  at  which 
it  is  usually  cut,  form  particularly  favourable  material  on  which  to 
demonstrate  the  binucleate  phase,  which  is  a  striking  feature  of  the 
ground-tissue  cells. 

As  we  have  already  meiitioned,  we  find  that  the  binucleate 
condition  is  invariably  brought  about  by  mitosis.  The  division 
occurs  normally  in  the  earlier  stages,  up  to  the  period  at  which 
the  two  daughter  nuclei  are  at  the  poles  of  the  spindle,  while  the 
cell-plate  is  just  being  initiated.  But  at  this  point  the  mechanism 
seems  to  break  down  and  the  cell-plate  is  resorbed,  while  the 
phragmoplast,t  with  its  associated  cytoplasm,  goes  through  a 
singular  metamorphosis.  It  becomes  vacuolate  in  the  centre  and 
develops  into  a  hollow  sphere  which  gradually  grows  until  it 
encloses  both  the  daughter  nuclei,  and  then,  by  its  further  extension, 
ultimately  merges  into  the  cytoplasm  lining  the  cell  wall.  For 
this  hollow  shell  we  have  proposed  the  term  "  phragmosphere." 
In  some  cases  it  is  exceedingly  well-defined  and  stains  deeply, 
giving  the  sections  in  which  it  occurs  a  curious  appearance  of 
exhibiting  cells  within  cells. 

The  binucleate  condition  of  parenchymatous  cells  persists  in 
some  cases  for  a  very  long  time — possibly  throughout  the  life  of  the 
-element — but  in  other  cases  the  cells  eventually  become  uninucleate. 
This  seems  to  be  brought  about  by  the  degradation  and  resorption 
of  one  nucleus  of  the  pair.  We  have  seen  no  evidence  of  any 
other  method  of  transition  from  the  binucleate  to  the  uninucleate 
state — such,  for  instance,  as  fusion  of  the  nuclei,  or  a  belated 
development  of  walls  between  them.  In  old  tissues,  lobed  nuclei 
are  frequently  seen  which  might  easily  be  taken  to  be  stages  either 

*  Beer,  R.  and  Arber,  A.  (1919) ;  see  also  Arber,  A.  (1920). 
t  This  convenient  term  wag  introduced  by  Errera,  L.  (1888),  to  denote  the  com- 
plex ofspindle  fibres  which  generally  assumes  the  form  of  a  **  Rotationsellipsoid." 


30  Transactions  of  the  Society. 

in  fusion  or  amitosis,  but  we  have  come  to  the  conclusion  that 
these  are  merely  degeneration  stages. 

We  must  not  here  enter  upon  the  far-reaching  question  of  the 
significance  of  the  binucleate  phase.  It  may  possibly  have  its 
value  in  increasing  the  area  of  nuclear  surface  in  contact  with  the 
cytoplasm ;  we  have  shown  elsewhere*  that  there  is  a  certain 
amount  of  evidence  in  favour  of  this  view.  But  on  the  other  hand 
the  binucleate  condition  may  merely  indicate  that  the  cytoplasm 
flags  in  its  capacity  for  active  division  before  the  nucleus  shows 
any  sign  of  having  passed  from  the  energy  of  youth  to  the  repose 
of  age. 

List  of  Memoirs  Cited. 

Arber,  a.  (1914). — On    Root    Development   in    Stratiotes   aloides.     Proc. 

Camb.  Phil.  Soc,  xvii.  (1914)  pp.  369-79  (2  pis.). 
(1920). — Studies  on  the  Binucleate  Phase  in  the  Plant  Cell.     Journ.. 

Roy.  Micr.  Soc,  1920,  pp.  1-21  (1  pi.,  2  text-figs.). 
Beer,  R.  (1899).— On  the   Multinuclear  Cells   of  some  Grasses.     Natural 

Science,  xv.  (1899)  pp.  434-9  (2  pis.). 
Beer,   R.   &   Arber,  A.  (1915).— On  the  Occurrence   of    Binucleate  and 

Multinucleate  Cells  in  Growing  Tissues.    Ann.  Bot.,  xxix.  (1915) 

pp.  597-8. 
(1919).— On  the  Occurrence  of  Multinucleate  Cells  in  Vegetative 

Tissues.     Proc.  Roy.  Soc,  B,  xci.  (1919)  pp.  1-17  (1  pi.,  2  text-figs.). 
Brown,  R.  (1833). — On  the  Organs  and  Mode  of  Fecundation  in  Orchidea& 

and  Asclepiadeae.     Trans.  Linn.  Soc,  xvi.  (1833)  pp.  685-745  (3  pis.). 
Errera,  L.  (1888). — Ueber   Zellformen  und  Seifenblasen.     (Versammlung 

Deutsche  Naturforscher  und  Aerzte  in  Wiesbaden.)     Bot.  Centralbl., 

Bd.  34  (1888)  pp.  395-8. 
Grant,  A.  E.  (1886.)— The  Multinucleated  Condition  of  the  Vegetable  Cell, 

with  some  special  Researches  relating  to  Cell  Morphology.     Trans. 

Bot.  Soc.  Edinburgh,  xvi.  (1886,  read  June  1883)  pp.  38-52  (2  pis.). 
Hill,   T.  G.,  &   Freeman,  Mrs.  W.   G.    (1903).— The    Root- Structure    of 

Dioscorea  prehensilis.    Ann.  Bot.,  xvii.  (1903)  pp.  413-24  (1  pi.  and 

text-figure). 
JoHOW,  F.  (1880). — Untersuchungen  iiber  die  Zellkerne  in  den  Secretbehah 

tern  und  Parenchymzellen  der  hoheren  Monocotylen.     Inaug.  Diss. 

Bonn,  1880,  47  pp. 
McLean,  R.  C.  (1914). — Amitosis  in  the  Parenchyma  of  Water-Plants.    Proc. 

Camb.  Phil.  Soc,  xvii.  (1914)  pp.  380-2  (1  text-fig,). 
Nagbli,  C.  (1844). — Zellenkerne,  Zellenbildung,  und  Zellenwachsthum  bei 

den  Pflanzen.     Zeitschr.  f.  Wiss.  Bot.,  von  M.  J.  Schleiden,  Bd.  1,. 

Heft  I.  (1844)  pp.  34-133  (2  pis.). 
Nemec,  B.  (1910). — Das  Problem  der  Befruchtungsvorgjinge.     Berlin  :  1910^ 

532  pp.,  119  text-figs.,  5  pis. 
PiGOTT,  E.  M.  (1915). — Notes  on  Nothopanax  arhorcu7)i,  with  some  Reference 

to  the  Development  of  the  Gametophyte.     Trans,  and  Proc.  New- 
Zealand  Institute,  xlvii.  (1915)  pp.  599-612  (23  text-figs.). 
PiROTTA,  R.,  &  BuscALioNi,  L.  (1898). — Sulla  presenza  di  element!  vascolari 

multinucleati  nelle  Dioscoreacee.    Annuario  del  R.  Istituto  Botanico 

di  Roma,  Anno  VII.  (1898)  pp.  237-54  (4  pis.). 

*  Beer,  R.  and  Arber,  A.  (1919), 


Multinucleate  Cells:  An  Historical  Study  {1879-1919).,     31 

Prankerd,  T.  L.  (1915). — Notes  on  the  Occurrence  of  Multinucleate  Cells* 
Ann.  Bot.,  xxix.  (1915)  pp.  599-604  (8  text-figs.). 

ScHMiTZ,  F.  (1878  and  1880). — Untersuchungen  liber  die  Zellkerne  der  Thallo- 
phyten.  Sitzungsber.  d.  Niederrheinisch.  Gesellsch.  in  Bonn.  (Natur- 
hist.  Verein  der  preuss.  Bheinlande  und  Westfalens.)  Jahrg.  S^ 
(Folge  iv.  Jahrg.  6)  1879,  pp.  345-76,  and  Jahrg.  37  (Folge  iv. 
Jahrg.  7)  1880,  pp.  122-32. 

Schwann,  T.  (1839). — Mikroskopische  Untersuchungen  iiber  die  Ueberein 
stimmung  in  der  Struktur  und  dem  Wachsthum  der  Thiere  xmd, 
Pflanzen.     Berlin  :  1839,  xviii  and  270  pp.  (4  pis.). 

Smolak,  J.  (1904). — Ueber  vielkernige  Zellen  bei  einigen  Euphorbiaceen, 
Bull.  Internat.  de  I'Acad.  des  Sci.  de  I'Empereur  Francois  Joseph  I, 
(Ceska  Akad.  Ci'sare  Frantiska  Josef  a  I.).  Prague  :  IX  Annee,  1904, 
ii.,  pp.  135-49  (36  text-figs.). 

Strasbukgbr,  E.  (1880). — Einige  Bemerkungen  iiber  vielkernige  Zellen  unc! 
iibcr  die  Embryogenie  von  Lupinus.  Bot.  Zeit.,  Jahrg.  38  (1880) 
pp.  845-54,  857-68  (1  pi.). 

Treub,  M.  (1879). — Quelques  recherches  sur  le  role  du  noyau  dans  la 
division  des  cellules  vegetales.  Verhandel.  d.k.  Akad.  van  Weten- 
schappen.     Amsterdam  :  1879,  xix.  35  pp.  (4  pis.). 

—  (1880). — Sur  les  cellules  vegetales  a  plusieurs  noyaux.  Arch.  Neer- 
landaises,  T.  xv.  (1880)  pp.  39-60  (3  pie.). 


33 

SUMMARY  OF  CURRENT  RESEARCHES 

RELATING   TO 

ZOOLOGY     AND      BOTANY 

(principally  invertebrata  and  cryptogamia), 

MICEOSCOPY,   Etc.* 


ZOOLOGY. 


VERTEBRATA. 


o.    Embryolog-y,  Evolution,  Heredity,  Beproduction, 
and  Allied  Subjects. 

Relation  of  Spermatozoa  to  Certain  Electrolytes. — J.  Gray 
i^Proc.  Roy.  Soc,  1920,  91,  147-57).  A  suspension  of  the  spermatozoa 
of  Echinus  miliaris  in  sea-water  behaves  towards  trivalent  positive  ions 
in  exactly  the  same  way  as  a  suspension  of  negatively  charged  particles 
of  such  colloids  as  albumen  or  globulin.  It  is  only  in  those  solutions 
which  are  capable  of  maintaining  the  normal  negative  charge  that  move- 
ment of  spermatozoa  can  take  place.  Trivalent  ions  flocculate  sperm 
suspensions  by  removing  the  negative  charge.  The  action  of  the 
hydrogen  ions  is  very  intense,  and  changes  the  surface  charge  from 
negative  to  positive  without  any  immediate  flocculation.  The  experi- 
mental evidence  goes  to  show  that  the  surface  charge  on  the  spermatozoa 
is  of  fundamental  importance  to  their  activity,  and  that  this  charge 
depends  upon  the  nature  of  the  solutions  with  which  the  spermatozoa 
are  in  contact.  Just  as  particles  of  different  colloids  (or  membranes  of 
different  composition)  possess  different  charges  when  in  contact  with 
the  same  solution,  so  the  eggs  and  spermatozoa  of  different  species  may 
have  different  surface  charges  when  in  sea- water  of  the  same  composi- 
tion. If,  therefore,  the  possibility  of  fertilization  of  the  Qg^  depends 
partly  on  the  mutual  relationship  between  the  surface  charge  of  the  ^gg 
and  that  of  the  spermatozoon,  it  is  possible  that  many  cases  of  artificial 
hybridization  may  find  a  simple  solution.  It  is  proposed  to  investigate 
the  surface  charges  of  the  spermatozoa  of  different  species,  with  a  view 
to  determining  whether  the  possession  of  a  critical  surface  charge  con- 
trols the  fertilizing  power  of  the  sperm  for  eggs  of  the  same  and  of 
different  species.  J.  A.  T. 

*  The  Society  does  not  hold  itself  responsible  for  the  views  of  the  authors 
of  the  papers  abstracted.  The  object  of  this  part  of  the  Journal  is  to  present 
a  summary  of  the  papers  as  actually  published,  and  to  describe  and  illustrate 
Instruments,  Apparatus,  etc.,  which  are  either  new  or  have  not  been  previously 
described  in  this  country. 

D 


34  SUMMARY   OF   CURRENT   RESEARCHES  RELATING  TO 

Testicular  Grafts.— Ed.  Retterer  {C.  R.  Soc.  Biol,  1919,  82^ 
1022-5).  Testicular  grafts  have  been  previously  made  in  amphibians 
and  birds,  and  it  has  been  noted  that  the  seminiferous  tubules  continue 
for  some  time  to  form  spermatozoa,  but  that  the  epithelium  gradually 
degenerates.  Mammalian  testes  transplanted  into  the  peritoneal  cavity 
or  underneath  the  skin  show  after  some  time  only  Sertoli's  cells,  which 
multiply  by  mitosis,  or  are  converted  into  giant-cells  or  indifferent 
epithelium.  Testes  of  rats  grafted  on  the  internal  surface  of  the 
abdominal  wall  showed  degeneration  of  seminal  cells  ;  the  seminiferous- 
tubules  became  covered  only  by  a  succulent  epithelium,  and  the  inter- 
stitial cells  increased  in  number.  Retterer  has  made  grafts  of  testes  or 
pieces  of  testes  in  the  goat.  Both  in  the  entire  testes  and  in  the  pieces 
the  only  parts  that  survived  were  the  superficial  portions  which  con- 
tinued to  receive  nutritive  plasma.  The  superficial  cells  that  survived 
changed  their  structure  and  mode  of  development.  A  few  continued  to* 
divide  to  form  small  nuclei  and  the  heads  of  spermatozoa.  The  great 
majority  were  transformed  into  a  mass  of  coalescent  cytoplasm  which 
ended  by  becoming  reticular  connective  tissue.  J.  A.  T. 

Experimental  Degeneration  of  Testis  in  Dog. — Albert  Kuntz 
{Anat.  Record,  1919,  17,  221-34,  4  figs.).  Elimination  of  the  sympa- 
thetic nerve  supply  to  the  testes  is  followed  by  degeneration  of  the 
seminal  epithelium  and  accompanying  hypertrophy  of  the  interstitial 
secretory  tissue.  The  same  degeneration  followed  in  both  testes  after 
ligature  and  resection  of  the  right  ductus  deferens.  The  degeneration 
was  similar  to  that  following  exposure  of  the  testis  to  X-rays,  or  follow- 
ing a  diet  deficient  in  the  water-soluble  vitamines.  J.  A.  T. 

Innervation  of  Gonads  in  Dog. — Albert  Kuntz  {Anat.  Record^ 
1919,  17,  203-19,  4  figs.).  The  sympathetic  nerves  to  ovaries  and 
testes  pass  distally  along  the  ovarian  and  spermatic  arteries  respectively^ 
and  enter  the  organs  in  more  or  less  intimate  association  with  the  blood- 
vessels or  the  efferent  ducts.  The  majority  of  these  fibres  are  derived 
directly  from  the  sympathetic  ramus  ascending  from  the  inferior  mesen- 
teric ganglia  to  the  renal  plexus.  The  blood-vessels  and  all  other 
structures  in  the  gonads  which  contain  smooth  muscle  receive  an 
abundant  sympathetic  nerve  supply.  The  evidence  available  does  not 
indicate  a  sympathetic  nerve  supply  either  to  the  ovarian  follicles  and 
the  interstitial  secretory  tissue  in  the  ovary,  or  to  the  seminal  epithelium 
and  the  interstitial  secretory  tissue  in  the  testis.  J.  A.  T. 

Sterility  of  Mules. — W.  M.  Goldsmith  {Amer.  Journ.  Veterinary 
Medicine,  1917,  June,  1-8,  19  figs.).  The  mule  possesses  the  necessary 
reproductive  organs  and  the  sex  impulse.  The  early  cells  of  the  testis 
show  normal  cells  with  fifty  ordinary  chromosomes  and  one  sex- 
determiner.  The  horse  has  only  thirty-six  plus  the  extra  chromosome. 
It  is  supposed  that  the  ass  has  about  sixty-five  chromosomes.  According 
to  Wodsedalek,  most  of  the  mule's  spermatocytes  disintegrate  during 
the  maturation  division,  perhaps  because  of  the  marked  difference  in 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  35 

the  numbers  of  the  chromosomes  in  the  two  parents.  Wodsedalek 
denies  that  fertility  ever  occurs  in  mules,  but  Goldsmith  cites  Lloyd- 
Jones  to  the  effect  that  female  mules  and  "  hinnies  "  may  be  the  mothers 
of  colts.  Goldsmith  has  been  "unable  to  find  any  record,  either 
authentic  or  otherwise,  of  a  reproducing  male  mule."  There  seems  to  be 
a  lack  of  facts  in  this  and  other  discussions  of  the  sterility  of  mules. 

J*  A.  J.. 

G-erm-plasm  of  Ostrich.— J.  E.  Dueeden  {American  Naturalist^ 
1919,  51,  312-37).  "Without  any  hesitancy  it  can  be  affirmed  that 
in  the  course  of  the  fifty  years  during  which  the  ostrich  has  been 
domesticated,  it  has  never  produced  a  feather  variation,  germinal  in  its 
origin,  such  as  could  be  regarded  as  of  the  nature  of  a  sport  or 
mutation."  The  germ-plasm  is  often  very  conservative.  "  The  greatest 
mixture  of  germ-plasm  is  going  on,  but  no  single  hereditary  factor  or 
determiner  is  altered  in  the  process,  and  has  not  altered  throughout  the 
history  of  ostrich  breeding  ;  only  new  combinations  are  formed  of  factors, 
already  available."  Crossing  does  not  originate  novelties.  Artificial 
selection  does  not  in  the  case  of  ostriches  do  more  than  sift  out  the 
possessors  of  certain  characters  and  bring  them  together  so  as  to  effect 
a  desired  combination  in  the  progeny.  The  germ-plasm  changes  as 
between  the  northern  and  the  southern  ostrich  have  resulted  entirely 
from  internal  physiological  causes.  In  many  respects  the  degeneration 
phenomena  in  the  ostrich  appear  to  be  best  understood  on  the  conception 
of  autonomous  changes  and  variations  in  potency  of  the  germ  factors. 
It  is  possible  that  by  inbreeding  an  inherent  tendency  towards  reduction 
(e.g.  towards  the  loss  of  toe-scales)  may  be  accentuated.  J.  A.  T. 

Asymmetrical  Duplicity  in  Chick. — Noel  Taylor  {Proc.  Zooh 
Soc,  1919,  83-109,  3  pis.,  2  figs.).  Description  of  a  blastoderm  showing 
asymmetrical  duplicity,  unique  in  the  respect  that  both  of  the  embryonal 
formations  exhibited  gross  structural  defects.  It  seems  explicable  only 
on  the  monozygotic  theory  of  origin,  i.e.  that  both  centres  originated 
through  some  kind  of  disturbance  from  a  single  and  possibly  normal 
germ.  The  primary  modification  induced  in  the  larger  embryonic 
formation  resulted  in  the  inhibition  of  the  normal  growth  of  the 
anterior  portion  of  the  nervous  system  and  of  the  formation  of  the  head- 
fold.  From  this  there  followed  various  secondary  modifications. 
Although  no  true  head-fold  could  have  been  present,  there  was  never- 
theless a  well-developed  fore-gut.  While  it  has  been  experimentally 
demonstrated  that  the  material  of  the  primitive  streak  does  not  enter 
into  the  formation  of  the  brain,  it  appears  from  the  case  in  question 
that  the  material  from  which  the  anterior  region  of  the  medullary  plate 
normally  arises  may  under  certain  circumstances  have  the  power  of 
*  giving  rise  to  a  primitive  streak-like  mass  of  tissue.  The  importance  of 
the  case  is  that  the  two  embryonal  formations  were  from  the  first  unlike^ 
the  asymmetry  being  intimately  bound  up  with  the  actual  origin  of 
the  two  centres  of  embryonal  formation  from  a  single  centre,  and  not 
resulting  from  secondary  modification  in  the  course  of  development. 

J.  A.  T. 

D  2 


36  SUMMARY   OF   CURRENT   RESEARCHES   RELATING  TO 

Duplicity  in  Chick  Embryos.  —  G.  W.  Tannreutheb  (Anat. 
Record,  1919,  16,  355-67,  6  figs.).  A  description  of  some  unusual 
forms  of  partial  and  complete  duplicity  in  chick  embryos,  where  the 
blastoderm  divides  into  several  equipotent  regions.  In  one  case  the 
blastoderm  showed  four  primitive  streaks ;  in  another  the  embryo 
anterior  to  the  primitive  streak  showed  an  almost  complete  duplication 
of  parts  ;  in  a  third  case  there  is  an  almost  complete  duplication  of 
structures  on  a  common  blastoderm  ;  in  another  there  seem  to  have 
been  two  independent  primitive  streaks  with  the  anterior  ends  of  the 
head  processes  continuous  or  in  immediate  contact.  J.  A.  T. 

Absence  of  Hind  Legs  below  Femur  in  a  Full-term  Pig. — 
M.  Carreon  {Philippine  Journ.  Sci.,  1919,  14,  201-5,  1  pi).  In  an 
otherwise  normal  litter  one  member  had  no  hind  limbs  below  the  femur, 
and  had  also  cleft  palate.  It  is  'reasonable  to  assume  that  the  two 
abnormal  conditions  had  the  same  underlying  cause.  Both  show  an 
interrupted  growth  very  early  in  the  development  of  the  pig.  Every- 
thing points  to  some  physico-chemical  interference  with  growth. 

J .  A.  X . 

Development  of  Membrane  Bone. — Ed.  Retterer  {C.  R.  Soc. 
Biol.,  1920,  83,  4-6).  The  development  of  the  first  bony  trabeculae  in 
a  connective  membrane  has  been  studied  in  the  case  of  the  human 
maxilla.  In  the  mesodermic  tissue  in  which  the  bone  develops  there 
are  cells  with  a  granular  and  reticular  framework  containing  only 
hyaloplasm.  This  becomes  dense  and  eosinophilous.  The  reticulate 
and  anastomosing  filaments  become  more  numerous.  Thus  arises  the 
first  intercellular  or  osseous  substance.  Between  it  and  the  nucleus  a 
.clear  cytoplasm  appears,  which  forms  the  cellular  body  of  the  bone-cells. 
These  are  separated  from  the  intercellular  substance  by  the  formation 
of  a  capsule.  The  inter-cellular  or  osseous  substance  increases  and 
differentiates  into  a  framework  and  an  amorphous  calcified  mass. 

J.  A.  T. 

Developing  Connective  Tissue. — Raphael  Isaacs  {Anat.  Record, 
1919,  17,  243-70,  6  figs.).  A  study  of  developing  connective  tissue  in 
embryos  of  chick,  pig,  and  man,  and  of  colloids  of  gelatin,  egg  albumin, 
and  fibrin  under  controlled  laboratory  conditions.  The  intercellular 
jelly  of  embryonic  and  adult  tissue  is  structurally  homogeneous  and 
contains  no  network  of  fibrils.  The  so-called  fibrils  of  connective  tissue 
and  neuroglia  are  fixation  artefacts.  The  fibres  of  adult  tissues  are 
formed  by  the  thickening  (concentration  increase)  of  the  colloid  lying 
between  the  fibroblasts.  The  polarization  of  the  cells,  their  movement, 
and  the  stress  exerted  on  the  growing  tissue,  all  serve  to  give  the  adult 
white  fibres  their  arrangement  as  strands  in  a  bundle.  J.  A.  T. 

Embryological  Studies  of  Indian  Fishes. — T.  Southwell  and 
B.  Prashad  {Record!^  Indian  Mmeum,  1919,  16,  215-40,  4  pis.).  1.  A 
description  is  given  of  two  Leptocephalids  from  the  brackish  waters  of 
the  Gangetic   Delta.     2.  An   account  is   given   of  the  life-history  of 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  37 

Notopterus  chitala,  a  teleost  of  the  Ganges.  The  glutinous  eggs  are 
usually  laid  on  solid  bodies,  such  as  stones ;  the  male  emits  milt  over 
them ;  they  are  jealously  guarded  ;  seven  stages  of  development  are 
described.  3.  The  egg-case  of  ChlloscylUum  griseum  is  described.  It 
has  attached  to  one  of  the  longer  sides  a  very  long  (134  mm.)  and 
thick  mooring  cord  of  a  silky  (?)  material,  which  would  be  useful  in 
anchoring  the  egg-case  to  any  object  on  the  floor  of  the  sea.  4.  Intra- 
uterine embryos  are  described  in  a  number  of  Indian  Elasmobranchs. 
In  the  earlier  embryonic  stages  of  the  placental  forms  there  is  no  placenta, 
but  the  yolk-sac  functions  as  such.  Later  on  a  placenta  develops  by  a 
modification  of  the  yolk-sac,  and  nourishment  is  obtained  directly  from 
the  blood  of  the  mother.  In  some  cases  additional  structures  or  appen- 
dicula  are  developed  on  the  placental  cord,  and  these  probably  absorb 
the  uterine  secretion  in  which  the  embryo  is  floating.  In  the  aplacental 
forms  the  yolk-sac  persists  as  such  through  the  greater  part  of  the 
embryonic  life,  and  the  yolk  is  directly  taken  into  the  gut  with  or 
without  the  intermediation  of  an  internal  yolk-sac.  Possibly  the 
branchial  filaments  help  in  absorption,  and  in  earlier  stages  they  absorb 
uterine  secretion.  The  blood-vessels  in  the  mesoblastic  portion  of  the 
yolk-sac  are  also  absorptive.  In  later  stages  special  processes  of  the 
maternal  uterine  wall  (trophonemata)  enter  the  embryonic  spiracles  and 
pour  in  secretion.  The  stomach  does  not  function  as  such  during  the 
embryonic  period,  but  is  a  mere  channel  to  the  absorptive  colon. 

J.  A.  T. 

Muscular  Metamerism. — Henri  V.  Vallois  {C.R.  Soc.  Biol.,  1920, 
83,  111-3).  In  most  fishes  and  Urodela  the  myosepta  which  persist 
in  the  adult  have  undergone  foldings  which  completely  modify  their 
insertion.  The  episomatic  portion  of  each  myotome  does  not  correspond 
to  one  intervertebral  space  as  in  the  embryo,  but  extends  over  adjacent 
spaces  in  front  and  behind.  It  is  not  accurate  to  say  that  the  primitive 
metameric  structure  persists  in  the  adult ;  the  muscular  metamerism 
does  not  correspond  with  the  skeletal  metamerism.  The  author  discusses 
the  state  of  affairs  in  higher  vertebrates  where  there  is  a  general 
disappearance  of  the  myosepta.  J,  A.  T. 

Neuromeres  and  Metameres. — H.  V.  Neal  {Journ.  Morphol.,  1919, 
31,  293-315,  ]7  figs.).  However  doubtful  the  interpretation  of  the 
so-called  neuromeres  of  vertebrate  embryos  in  other  regions  of  the  body, 
the  hind -brain  neuromeres  or  rhombomeres  can  be.  explained  neither  as 
primordia  of  adult  organs  nor  as  the  passive  results  of  mechanical 
pressure  produced  by  the  bending  of  the  neural  tube.  A  phylogenetic 
interpretation  of  them  therefore  appears  to  be  not  impossible.  Neuro- 
merism  is  not  seen  in  the  central  nervous  system  of  Amphioxus.  It  is 
more  conspicuous  in  the  embryos  of  higher  Chordates  than  in  those  of 
lower,  and  it  is  more  conspicuous  in  the  head  than  in  the  trunk. 
Analogous  evidence  led  to  the  abandonment  of  the  vertebral  theory  of 
the  skull.  The  author  suggests  that  the  rhombomeres  may  have  arisen 
in  adaptation  to  the  branchiomeric  segmentation  ;  their  neuromuscular 
relations  are  hard  to  reconcile  with  the  assumption  of  metameric  value. 


38  SUMMARY   OF   CURRENT   RESEARCHES   RELATING  TO 

The  mesodermic  somites  afford  reliable  criteria  of  the  primitive  meta- 
merism of  the  head,  but  the  same  cannot  be  said  of  the  rhombomeres. 
The  chief  evidence  of  the  metameric  value  of  neuromeres  consists  in 
their  numerical  correspondence  with  the  mesodermic  somites,  but  this 
correspondence  obtains  in  the  head  region  of  vertebrates  for  only  the 
primary  brain  vesicles  (Neal's  neuromeres  I-VII),  and  not  for  the 
secondary  subdivisions  of  these,  such  as  rhombomeres  1  and  2,  which 
result  from  the  secondary  subdivisions  of  neuromere  III.  Except  in  the 
case  of  neuromeres  II  and  III  (Neal),  the  motor  nerve  relations  of 
the  neuromeres  do  not  accord  with  the  supposition  that  they  are  meta- 
meric structures.  J.  A.  T. 


b.  Histology. 

Cytology. — L.  Doncaster  (An  Introduction  to  the  Study  of  Cytologij, 
Cambridge  Uiiiversity  Press,  1920,  xiv  +  280  pp,  24  pis.,  31  figs.).  An 
admirably  clear  and  scholarly  introduction  to  cytology  which  will  be 
widely  welcomed.  It  is  marked  by  careful  workmanship  and  sound 
judgment.  The  illustrations  are  admirable  and  abundant,  and  there  is 
a  representative  bibliography.  The  subjects  dealt  with  are  the  follow- 
ing :  The  cell  in  general  and  protoplasm,  the  cell-organs,  cell-division, 
the  centrosomes,  the  maturation  of  the  germ-cells,  fertilization,  seg- 
mentation, natural  and  artificial  parthenogenesis,  the  cytological  basis  of 
sex-determination,  germ-cell  determinants,  the  theory  of  the  individuality 
of  the  chromosomes,  the  mechanism  of  hereditary  transmission,  the  role 
of  the  cytoplasm  in  development  and  heredity.  As  was  to  be  expected 
from  the  author's  personal  investigations,  prominence  is  given  to  the 
cytological  basis  of  hereditary  transmission  and  of  sex-determination  ; 
but  to  these  questions  a  great  part  of  the  cytological  research  of  the 
past  fifteen  years  has  been  devoted,  and  a  judicial  up-to-date  exposition 
is  very  timely.  The  book  hardly  deals  with  the  physiological  and 
biochemical  sides  of  cytology,  and  we  venture  to  express  the  hope  that 
this  self-denying  ordinance  will  not  be  adhered  to  in  subsequent 
editions.  J.  A.  T. 

Chromosome  Dimensions. — C.  F.  U.  Meek  {Proc.  Roy.  Soc,  1920, 
91,  157-65,  2  pis.).  Measurements  of  a  large  number  of  chromosomes 
in  different  types  lead  to  the  following  conclusions : — The  degree  of 
somatic  complexity  of  an  animal  cannot  be  correlated  with  the  lengths 
of  the  chromosomes  composing  its  complex,  nor  with  the  diameters  of 
these,  nor  with  the  total  volume  of  these,  nor  with  their  number. 
There  are  many  different  chromosomes  in  different  types,  and  the 
chromosomes  composing  the  spermatogonial  complex  are  not  necessarily 
identical  in  diameter  with  those  composing  its  secondary  spermatocyte 
complex.  All  chromosomes  composing  an  individual  complex  are  not 
necessarily  of  the  same  diameter.  The  tendency  noted  in  a  previous 
communication  for  the  chromatin  volume  and  chromosome  diameter  to 
increase  from  simple  to  complex  animals  must  have  been  fortuitous. 

J.  A.  T. 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  39 

Specific  Substances  In  Leucocytes  of  Immunized  Animals. — 
Alois  Bachmann  {C.  E.  Soc.  Biol,  1919,  82,  1031-3).  A  study 
of  the  leucocytes  of  guinea-pigs  immunized  against  Eberth's  bacilli 
reveals  the  presence  of  specific  substances  which  can  be  isolated.  To 
these  substances  the  leucocytes  owe  their  specific  immunizing  power. 
The  substances  are  more  stable  products  than  the  endolysins.  Indeed, 
they  were  experimentally  isolated  by  the  destruction  of  the  endolysins  > 
a  method  which  left  the  specific  substances  intact.  J.  A.  T. 

"  Patty  Cells "  of  Pulmonary  Alveolus. — E.  Faur^-Fremiet 
{C.  R.  Soc.  Biol,  1920,  83,  11-13).  In  the  pulmonary  alveolus  of  ox, 
cat,  rat,  and  other  forms  "  fatty  cells  "  have  been  described.  The 
■delicate  conjunctive- vascular  support  of  the  wall  of  the  alveolus  is 
•covered  on  each  surface  with  an  epithelium  of  non-nucleated  flat  cells 
.and  of  nucleated  globular  cells.  The  nucleated  globular  cells  contain 
lipoid  globules,  which  appear  to  be  in  great  part  due  to  cholesterin.  As 
the  result  of  slight  irritation  these  elements  multiply  and  may  become 
mobile  phagocytes.     If  they  become  free  they  lose  the  lipoid  inclusions 

J.  A.  T. 

Blood  Corpuscles  of  Camelidse. — J.  Jolly  (C.  R.  Soc.  Biol,  1920, 
83,  125-7).  The  blood  of  a  Llama  showed  regularly  oval  red  blood 
■corpuscles,  8  /x,  by  4  /x,  without  trace  of  nucleus.  Seen  in  profile  they 
looked  Hke  spindles.  They  are  delicate  lamellae,  but  when  they  float 
they  show  a  marked  tendency  to  roll  themselves  up  on  their  longitu- 
dinal axis.  J.  A.  T. 

Haversian  Systems  in  Membrane  Bone. — Leslie  B.  Arey  {Anat. 
Record,  1919, 17,  59-61,  2  figs.).  Sections  from  bones  like  the  parietal 
and  temporal  controvert  current  statements  as  to  the  absence  of 
Haversian  systems  in  membrane  bone.  These  erroneous  statements 
have  helped  to  perpetuate  a  false  histological  distinction  between  bones 
primarily  of  intracartilaginous  and  bones  primarily  of  intramembranous 
origin.  The  fact  is  that  in  the  arrangement  of  bone  tissue  into 
periosteal.  Haversian,  and  interstitial  lamellag  there  is  essential  archi- 
tectural uniformity,  irrespective  of  the  mode  of  development. 

J.  A.  T. 

Minute  Structure  of  the  Brain. — Gr.  Fuse  {Arh.  Anat.  Inst.  K, 
Japan  Univ.  Sendai,  1919,  2,  1-384,  218  figs.).  A  series  of  researches 
on  the  minute  structure  of  various  parts  of  the  brain  in  man  and 
mammals.  They  deal,  for  instance,  with  the  medulla  oblongata,  the 
trigeminal  root,  the  corpus  trapezoides,  the  zona  quinto-olivaris  superior, 
and  the  auditory  tracts.  J.  A.  T. 

Lateral  Line  of  Polyodon  spathula. — Homer  B.  Latimer  {Trans. 
Amer.  Micr.  Soc,  1919,  38,  189-206,  2  pis.)-  As  the  lateral  canal 
passes  backwards  from  the  gill  region  its  diameter  gradually  becomes 


40  SUMMARY  OF  CURRENT  RESEARCHES  RELATING  TO 

smaller.  The  sensory  ridges  are  located  on  crests  or  portions  of  the 
canal  approaching  the  surface.  The  lumen  of  the  canal  here  is  always 
larger  than  just  anterior  or  posterior  to  the  ridge.  The  longest  ridges 
are  in  the  anterior  region.  There  is  a  gradual  diminution  in  length  in 
a  posterior  direction  until  just  before  the  tail  is  reached.  Upon  the 
tail  itself  a  slight  increase  in  length  occurs.  No  branchlet,  except 
on  the  caudal  fin,  where  there  seems  to  be  great  irregularity,  is  given 
off  without  a  sensory  ridge  at  its  posterior  end.  Ridges  may  or  may 
not  occur  between  the  branchlets.  Though  there  is  a  slight  grouping, 
branchlets  are  given  off  throughout  the  entire  length  of  the  lateral 
canal.  J.  A.  T. 

Investigations  on  the  Spiroptera  Cancer,  III.-VI. — Johannes 
FiBiGER  {Det.  Kgl.  Danshe  Videnskahernes  SelsJcab.  Biologiske  Meddelelser^ 
1918-19,  1,  9,  10,  11,  14).  Following  on  his  previous  observations  on 
the  development  of  carcinoma  in  12  black  and  white  laboratory  rats 
infected  with  a  round  worm,  Spiroptera  neoplastica,  Johannes  Fibiger 
records  further  similar  experiments  on  214  black  and  white  laboratory 
rats.  Of  these,  102  rats  survived  more  than  45  days,  of  whom  54 
(53  p.c.)  developed  carcinoma  of  the  fundus  of  the  stomach.  His  ability 
to  produce  carcinoma  at  will  is  a  big  step  forward  in  the  investigation 
of  the  origin  of  tumour  cells  from  normal  tissue,  as  transplantion  experi- 
ments only  permit  of  the  study  of  the  continued  propagation  of  fully- 
developed  spontaneous  tumours.  The  experiments  consisted  of  feeding 
the  animals  with  the  muscles  of  cockroaches  {Feriplaneta  americana  and 
P.  orientalis)  infected  with  the  larvae  of  Spiroptera  neoplastica.  The 
cockroaches  were  fed  on  the  excrement  of  rats  containing  the  eggs  of 
the  parasite.  The  nematode  lives  attached  to  the  pavement  epithelium 
of  the  mouth  and  fundus  of  the  stomach. 

Out  of  116  rats,  in  107  the  fundus  was  examined  in  serial  section. 
This  was  necessary  in  that  the  growth  may  be  too  slight  to  be  seen 
microscopically,  as  rats  surviving  IJ  to  3  months  after  infection  showed 
carcinomata  of  only  1  mm.  in  extent,  but  in  those  living  up  to  6  months 
the  growth  reached  2*5  to  5  mm.  The  earliest  development  of  carci- 
noma was  45  to  50  days  after  infection  with  the  larvag. 

Carcinoma  was  only  diagnosed  on : — 1.  The  heterotopical  down- 
growth  of  epithelial  cells  belonging  not  only  to  the  normal  type  of  the 
basal  epithelial  layers,  but  mixed  up  with  atypical  and  keratinized  cells 
partly  arranged  as  spherical  masses  and  horny  globes.  2.  Infiltration  of 
these  cells  into  the  deeper  layers  splitting  up  invasively  the  connective 
tissue  of  the  mucosa  and  muscle  cells  of  muscularis  mucosae,  forming 
islets  and  spurs  in  the  latter  or  penetrating  through  this  layer  into  the 
submucosa.  Metastases  occurred  in  8  cases,  and  contained  no  worms  or 
ova.  Also  carcinomatous  growth  continued  after  all  the  Spiroptera  had 
disappeared  from  the  stomach.  Whereas  previously,  as  he  points  out, 
there  have  been  only  10  (about)  recorded  cases  of  cancer  of  the  tongue 
in  domestic  animals  and  none  in  rats,  he  has  succeeded  in  the  production 
in  rats  of  6  cases,  5  by  Spiroptera  infection  and  1  by  feeding  with  oats. 
One  hundred  and  fifteen  tongues  were  examined  in  serial  section  (at 
10  /x  every  10th  to  6th  or  more  of  which  were  examined),  comprising 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC. 


41 


in  some  cases  the  tongue  in  toto.  The  growths  were  typical  of  cancer 
of  the  tongue,  showing  invasion  of  the  muscles.  No  metastases  were 
found. 

In  addition,  out  of  59  white  mice  which  survived  the  infection  for  45 


Fig.  1. — Sjnroptera  carcinoma  of  the  tongue  in  rats. 

days  or  more,  3  developed  carcinoma  of  the  fundus  of  the  stomach  ;  but 
whereas  in  the  rats  none  showed  invasion  of  the  muscularis  of  the 
stomach,  in  the  mice  2  showed  invasion  of  all  the  layers  of  the  stomach 
wall.    This  he  explains  as  being  due  to  the  early  death  of  the  rats 


Fig.  2.—Spiroptera  carcinoma  of  the  tongue  of  a  rat. 

(9  to  10  months  after  infection  in  longest-lived)  compared  with  the 
later  deaths  of  the  mice  (16  and  13  months  respectively).  In  one  case 
of  mouse  carcinoma  transplantation  of  the  tumour  was  successful  through 
4  generations,  with  28  successful  "  takes  "  in  55  inoculated  mice.    The 


42 


SUMMARY  OF   CURRENT   RESEARCHES   RELATING  TO 


transplanted  tumours  retained   their  histological  features  throughout, 
with  perhaps  slight  increase  in  the  degree  of  keratinization. 

He  suggests  that  his  findings  show  that  carcinoma  must  be  regarded 
as  a  specific  process  which,  under  certain  conditions,  accompanies  the 
hyperplastic  heterotopical  proliferation  of  the  epithelium,  and  is  not  the 
•culmination  of  this  proliferation.     Also  he  does  not  find  evidence  that 


Fig.  3. — Mouse  with  intraperitoneal  transplanted  Spiroptera  carcinoma 
107  days  after  transplantation  ;  fourth  generation. 

inflammatory  changes  are  necessarily  in  casual  relationship  to  carcinoma 
at  all,  for  in  the  mice  which  gave  a  very  low  percentage  of  carcinomatous 
development  the  hyperplasia  and  inflammatory  changes  were  as,  or  more, 
marked  than  in  the  rats. 

The   original  articles   are  extremely  interesting,   discussing  every 
question  which  the  experimental  results  bring  up.  R.  D.  P. 


c.  General. 

Theory  of  Vital  Phenomena. — Felix  Regnault  (C.  R.Soc.  Biol, 
1919,  82,  1280-2).  'The  organism  is  regarded  as  made  up  of  two 
substances,  the  living  substance  or  energid,  and  the  organic  products. 
The  two  together  form  the  tissues  and  are  present  in  variable  propor- 
tions. The  tissues  may  be  grouped  according  to  the  quantity  of  organic 
products  which  they  contain.  Certain  substances  regarded  as  living  are 
really  organic  products,  such  as  the  blood  corpuscles  and  the  sarcolemma 
of   muscles.      Protoplasm   itself   may   be   an   organic  product  of   the 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  43 

nucleus ;  in  any  case  it  has  an  incomplete  vital  energy  which  it  acquires 
from  the  nucleus.  The  organic  products  obey  physico-chemical  laws  ; 
the  energid  produces  an  energy  special  to  life.  J.  A.  T. 

Blood  as  Food.— Hassan  el  Diwany  {G.  R.  Soc.  Biol.,  1919,  82, 
1282-3).  A  study  of  the  digestive  tract  of  the  medicinal  leech  and 
Hemiclepsis  tesseUata,  and  also  of  a  tick  (Ixodes  ridiwms),  which  furnishes 
evidence  that  the  intestinal  cells  break  up  the  molecule  of  haemoglobin, 
giving  rise  not  only  to  biliary  pigments  which  are  eliminated,  but  also 
to  utiUzable  materials  which  are  absorbed.  The  latter  include  fat  and 
iron-compounds.  J.  A.  T. 

Reduction  of  Jugal  in  Mammals. — L.  T.  Hogben  (Proc.  Zool  Soc. 
London,  1919,  71-8).  An  account  is  given  of  the  state  of  the  jugal  in 
a  variety  of  mammalian  types.  "  Seeing  that  in  a  diversity  of  isolated 
genera  among  the  Placentals  exhibiting  every  possible  variety  of  diet 
and  habit,  and  also  in  some  of  the  less  specialized  representatives  of 
the  larger  groups  themselves,  the  jugal  displays  essentially  the  same 
relations  as  in  the  Metatheria — namely,  extending  postero-ventrally  from 
the  glenoid  to  the  lachrymal  antero-dorsally — it  is  hardly  possible  to 
agree  with  Weber  that  the  jugal  was  small  in  the  earliest  Mammalia,  as 
in  the  Insectivora  of  to-day  :  on  the  contrary,  there  can  be  little  doubt 
that  this  represents  the  ancestral  condition  retained  by  the  class  till  a 
date  later  than  that  at  which  the  modern  lines  of  mammalian  descent 
had  become  differentiated."  In  Monotremes,  though  the  arch  is  strong, 
the  jugal  is  vestigial  or  absent.  Reduction  is  common,  but  the  reason 
for  it  is  obscure.  J.  A.  T. 

New  Adaptive  Callosity  in  Ostrich. — J.  E.  Duerden  (Records  of 
Albany  Museum,  1919,  3,  189-95).  At  a  certain  stage  in  its  develop- 
ment, the  two-toed  Ostrich  {Struthio)  has  three  toes  and  hints  of  four 
and  five.  Two  or  three  toes  have  been  lost,  but  the  loss  is  not  quite 
complete.  When  crouching  the  ostrich  rests  on  the  tip  of  its  partly 
bent  toes  and  upon  the  ankle-end  of  the  tarso -metatarsus.  There  are 
callosities  on  the  toes  and  ankle,  and  these  occur  on  chicks  before 
hatching.  They  are  part  of  the  inheritance.  But  besides  the  median 
ankle  callosity  there  is  an  accessory  ankle  callosity,  which  begins  to  form  at 
an  early  chick  stage,  and  becomes  gradually  larger  and  coarser.  This 
accessory  pad  is  more  practically  useful  than  the  inborn  ankle  callosity. 
But  it  is  not  known  to  be  transmissible.  "  In  many  respects  the  ostrich 
appears  to  have  reached  senility,  and  it  may  be  that  structural  changes 
resulting  from  external  stimuli  are  now  more  likely  to  remain  transient, 
instead  of  becoming  impressed  permanently  upon  the  organism.  This 
may  assist  in  some  measure  in  understanding  why  the  later  accessory 
ankle  callosity  has  not  become  hereditary,  and  also  why  the  median 
callosity,  though  unused,  continues  to  appear  generation  after 
generation."  J.  A.  T. 

Action  of  Snake-poison  on  Blood. — B.  A.  Houssay  and  A. 
SoRDELLi  (C.  R.  Soc.  Biol.,  1919,  82,  1029-.31).  Twenty-one  different 
kinds  of  snake-poison  have  been  studied.  All  these  destroy  the 
cytozyme  (thrombokinase)  by  their  lipolytic  power.      This  soon  stops 


44  SUMMARY  OF  CURRENT  RESEARCHES  RELATING  TO 

coagulation,  and  no  blood- thrombin  is  formed.  Some  have  only  J  an 
anti-cytozyme  power  ;  others  have  besides  this  a  power  of  coagulating  the 
plasma  or  solutions  of  fibrinogen,  for  they  contain  specific  substances 
with  an  action  comparable  to  that  of  the  blood-thrombin.  This  is  only 
an  indication  of  the  results  of  prolonged  researches.  J.  A.  T. 

Morphology  of  So-called  Balancers  in  Amblystoma. — John  S. 
Latta  {Anat.  Record,  1919,  17,  63-71,  4  figs.).  The  larvae  of  some 
species  of  Amblystoma  and  a  few  other  salamanders  are,  at  an  early  stage 
of  their  development,  possessed  of  a  long  villiform  process  on  each  side 
of  the  head,  a  little  ventral  to  the  eye  and  equidistant  between  it  and  the 
base  of  the  external  gills.  They  are  very  rigid  and  resistant  for  struc- 
tures so  slender,  and  they  are  almost  immovable.  There  is  no  relation 
to  the  hyoid,  or  Meckel's  cartilage,  such  as  the  external  gills  have  to  the 
gill-arches.  A  dermal  bone  develops  in  connexion  with  each.  This  is 
formed  within  its  own  substance,  while  that  of  the  Cascilian  tentacle  is 
independently  formed  and  comes  secondarily  into  relation  with  it. 
Larvae  without  balancers  sink  into  the  mud  when  coming  to  rest.  The 
balancers  serve  as  props.  They  show  some  regenerative  capacity.  It 
seems  impossible  to  homologize  them  with  an  external  gill  or  with  a 
Caecilian  tentacle.  If  they  have  any  homologue  in  other  forms,  it  is 
most  likely  the  stalked  "  suctorial  discs  "  of  Triton  and  the  viscid  organs 
of  Anuran  larvae.  J.  A.  T. 

Lympathic  System  of  Anuran  Amphibia. — Otto  F.  Kampmeier 
{Anat.  Record,  1919, 16, 341-53).  A  summary  is  given  of  an  unpublished 
monograph  on  the  lymphatic  system  in  the  frog  and  toad,  with  especial 
reference  to  its  origin  and  development.  The  author  deals  with  the 
lymphatic  system  in  fully  formed  individuals,  the  modifications  of  the 
venous  system  during  development,  the  components  of  the  system  in 
young  tadpoles,  the  origin  and  development  of  the  primary  maxillary 
lymph  sinus,  the  origin  and  development  of  the  jugular  lymphatics,  the 
anterior  lymph  hearts,  the  lateral  lymphatics  of  the  trunk,  the  subver- 
tebral  lymphatics  (thoracic  ducts),  the  posterior  lymph  hearts  and  the 
lymphatics  of  the  tail,  the  formation  of  the  lymphatic  capillaries,  the 
transformation  of  the  lymphatic  vessels  of  the  tadpole  into  the  lymph 
sacs  and  sinuses  of  the  adult,  and  the  homology  of  the  chief  components 
of  the  lymphatic  ground-plan  in  the  different  groups  of  vertebrates. 

J.  A.  T. 

New  Blind  Fish  from  Texas. — Carl  H.  Eigenmann  {Proc.  Amer. 
Phil.  Soc,  1919,  58,  397-400,  2  figs.).  From  an  artesian  well  in  San 
Antonio,  Texas,  a  small  blind  catfish,  Trogloglanis  pattersoni  g.  etsp.  n., 
was  obtained.  Some  of  the  catfishes  are  nocturnal,  and  seek  their  food 
by  touch  and  taste  organs,  and  various  catfishes  have  become  blind  in 
different  parts  of  the  world.  This  new  one  is  probably  derived  from  a 
genus  like  Schilbeodes.  Just  as  the  eyes  of  the  Texan  blind  newt 
XTyphlomolge)  are  more  degenerate  than  those  of  the  salamanders  of 
Missouri,  so,  judging  from  external  appearancas,  the  eyes  of  Troyloglanis 
are  more  degenerate  than  those  of  any  of  the  blind  fishes  from  farther 
north.  J.  A.  T. 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,  ETC.  45 

Fauna  of  Water-pipes  and  Reservoirs. — R.  Kirkpatrick  (^The 
Biology  of  Water ic or ka,  British  Museum  (^Natural  History)^  1917, 
2nd.  ed.,  1-58,  18  figs.).  The  fauna  that  may  be  associated  with  a 
water-supply  includes  fixed  and  free-swimming  Protozoa,  the  two  com- 
mon fresh- water  sponges  {Spongilla  lacustris  and  Ephydatia  fluviatilis), 
species  of  Hydra,  many  kinds  of  worms,  numerous  Polyzoa,  about  a 
dozen  kinds  of  Molluscs,  a  few  crustaceans  and  insect  larvae,  young  eels 
jand  the  like.  In  reservoirs  there  are  sponges,  Polyzoa,  Entomostraca, 
larvae  of  Okiro?iomus,  and  so  on.  The  Algag  and  Bacteria  are  also  dealt 
with,  and  the  various  methods  of  securing  purity  in  the  water-supply. 
The  whole  study  is  very  interesting.  J.  A.  T. 

Tunicata. 

Bactericidal  Processes  in  Ascidia. — J.  Cantacuzene  (0.  R.  Soc. 
Biol.  Paris,  1919,  82,  1019-22).  Specimens  of  Ascidia  mentula  were 
inoculated  with  a  mobile  Bacterium  isolated  from  the  intestine  of 
Aplysia.  The  blood  of  the  Ascidian  is  strongly  acid,  is  very  rich  in 
oxydase,  and  contains  a  great  variety  of  amoebocytes.  To  begin  with, 
the  circulating  blood  shows  no  other  defence  but  intracellular  digestion, 
but  after  the  sixth  day  there  is  very  marked  agglutination  of  the 
Bacteria  in  direct  contact  with  the  amoebocytes.  Some  hyaline 
amoebocytes  give  rise  to  a  tenuous  glairy  substance  which  immobilizes 
Bacteria ;  others  containing  fatty  substances  arrest  the  Bacteria  that 
come  into  contact  with  them.  The  agglutination  increases  from  the 
sixth  to  the  tenth  day.  The  phagocytosis  also  continues  with  intensity  ; 
the  infection  is  usually  mastered.  The  acidity  and  oxidizing  capactiy 
of  the  blood  are  remarkably  diminished  soon  after  inoculation,  but 
re-appear  as  the  Ascidian  recovers.  J.  A.  T. 


INVERTEBRATA. 

Mollusca. 
a.  Cephalopoda. 

Orthogenetic  Development  of  Costsein  Perisphinctinae. — Marjorie 
O'CONNELL  (A7ner.  Journ.  Set.,  1919,  48,  450-60,  2  figs.).  Using  the 
term  orthogenesis  to  denote  the  fact  of  progressive  change  in  one 
direction  in  a  succession  of  ontogenetic  or  phylogenetic  stages,  and  not 
as  a  term  for  a  theoretical  interpretation  of  the  fact,  the  author 
illustrates  it  in  the  ontogeny  of  the  Jurassic  Ammonite,  Ferisphinctes 
cubanensis,  as  regards  the  development  of  the  cost*,  and  shows  that  the 
stages  in  the  single  individual  are  characteristic  of  the  adults  of  earlier 
geological  representatives  of  the  genus.  The  definite  direction  seen  in 
the  ontogeny  is  not  a  matter  of  individual  growth,  but  is  some  tendency 
inherent  in  the  organism  which  leads  to  the  same  type  of  development 
in  related  species  and  in  ancestors  and  descendants  throughout  Middle 
and  Upper  Jurassic  time.  J.  A.  T. 


46  SUMMARY   OF   CUKRENT  RESEARCHES   RELATING   TO 


7.  Gastropoda. 

Peculiar  Venezuelan  Land  Snail. — "Henry  A.  Pilsbry  {Proc. 
Acad.  Nat.  Sci.  Philadelphia,  1919,  71,  206,  1  fig.).  A  minute  discoidal 
shell,  concave  above  and  below,  whitish-transparent,  glossy,  with 
sculpturing  of  spaced  radial  grooves  after  the  first  half  whorl.  These 
grooves  become  closer  near  the  aperture,  and  in  the  largest  and  freshest 
specimens  they  are  occupied  there  by  projecting  riblets,  which  may  be 
partly  cuticular  and  deciduous.  The  specimens  were  0'55  mm.  high 
and  1*6  mm.  in  diameter,  and  were  obtained  by  sifting  leaf  debris. 
The  affinities  remain  uncertain,  as  it  is  very  unlike  any  described  form. 
It  doubtless  belongs  to  a  new  genus,  provisionally  placed  near  Proserpinida 


Three  views  of  Xenodiscula  venezuelensis,  and  the  aperture 
more  enlarged. 

or  Volvidens,  both  Antillean  genera.     The  name  proposed  is  Xe?iodiscida 
venezuelensis  g.  et  sp.  n.  J.  A.  T. 

Gastropods  of  Old  Lake-heds  in  Upper  Burma.  —  Nelson 
Annandale  {Records  Geol.  Survey  India,  1919,  50,  209-40,  3  pis.). 
Attention  is  called  to  parallel  evolution  or  convergence  on  a  large  scale 
in  the  shells  of  fresh-water  Gastropods  of  different  regions  and  epochs. 
The  evolution  of  the  genus  Taia,  a  peculiar  off-shoot  of  the  Yiviparidfe, 
with  peculiarly  ridged,  nodulose,  and  even  spiny  shells,  is  exactly  parallel 
i%  but  quite  independent  of,  that  which  produced  Margarya  in  the 
lakes  of  south-western  China,  and  also  that  which,  at  an  earlier  period 
and  in  a  distant  country,  resulted  in  a  large  series  of  species  of 
Vivipara  and  Tulotoma  with  a  similar  type  of  shell  in  the  Vienna  basin. 
But  Taia  is  proved  by  the  peculiar  structure  of  its  columellar  callus  to 
be  only  analogous,  not  homologous,  with  the  Austrian  and  Chinese 
forms.  The  genus  Vivipara  has,  in  fact,  again  and  again,  in  diverse 
countries  and  at  different  periods,  manifested,  when  left  undisturbed 
and  isolated  for  longer  periods,  a  tendency  to  produce  shells  ornamented 
with  smooth  spiral  ridges.  With  further  evolution  these  ridges  become 
at  first  undulated  on  the  surface,  then  granular  or  nodular,  and  finally 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  47 

in  a  few  instances  (e.g.  the  living  Taia  intha  and  some  forms  of 
Margarya  melanoides)  are  transformed  into  series  of  peculiar  squamous 
spines.  Moreover,  Vivipara  is  not  the  only  genus  in  which  this 
tendency  appears.  It  is  shown  to  some  extent  by  the  Neritidae  of 
Tertiary  beds  in  Cos,  and  in  a  more  striking  manner  by  the  Hydrobiidse 
or  Paludestrinidse  of  the  same  period  and  region,  and  by  those  still 
living  in  the  Yangtse  valley.     A  number  of  new  forms  are  described. 

J.  A.  T. 

Action  of  Veratrin  on  Snails  and  Slugs.— G.  Colosi  {Arch,  ZooL 
Exper.,  1919,  58,  Notes  et  Revue^  45-8,  2  tigs.).  If  a  specimen  of 
Helix  or  Limax  be  immersed  in  water  with  a  few  drops  of  weak  solution 
of  veratrin  there  is  protrusion  and  paralysis  of  tentacles,  buccal  mass 
and  penis,  while  the  rest  of  the  body  pulsates  violently  and  then 
becomes  rigid.  There  appears  to  be  a  great  increase  of  internal 
pressure  in  the  anterior  region  of  the  body.  The  protrusion  of  the 
penis  after  veratrin  treatment  showed  that  Limax  maximus  is  as  regards 
this  organ  very  different  from  L.  cinereo-niger.  J.  A.  T. 


Arthropoda. 
a.  Insecta. 

Blood-sucking  Insects  of  the  Philippines.— Charles  S.  Banks 
{Philippine  Journ.  Sci.,  1919,  14,  169-89).  A  useful  survey  of  the 
different  kinds  of  blood-sucking  insects  :  bed-bugs,  lice,  forest  flies 
(Hippoboscidse),  bat  flies,  mosquitoes,  horse  flies  (Tabanidae),  moth  flies 
(Psychodidse),  true  flies  (Muscidas),  buffalo  gnats  (Simuliidae),  midges 
(Chironomidae),  fleas,  water-bugs,  rubber  flies  (Mydaidse  and  Asilidse), 
which  capture  and  suck  other  insects,  and  the  small  fringe-winged 
Thrips.  Blood-sucking  mites  and  ticks  are  also  referred  to  for  the  sake 
of  completeness.  J.  A.  T. 

Trapping  of  Insects  by  an  Asclepiad. — H.  Ricome  {C.R.  Soc. 
Biol.,  1919,  82,  1045-7).  Many  insects,  such  as  hawk-moths  and  bees, 
are  trapped  by  an  Asclepiad  of  the  genus  Arauja,  which  is  cultivated  in 
gardens.  The  flower  is  adapted  to  pollination  by  insect  visitors,  and  all 
goes  well  if  the  insect  keeps  its  proboscis  between  the  stamens  and  the 
petals.  It  carries  away  the  poUinia  on  its  tarsal  joints.  But  if  the 
proboscis  is  inserted  between  one  of  the  retinacula  and  the  contiguous 
edges  of  two  adjacent  anthers  it  gets  caught  in  a  viscous  groove  of 
the  retinaculum.  There  is  no  reason  to  believe  that  this  means  more 
than  that  European  insects  are  not  adapted  to  an  exotic  flower.  Perhaps 
in  the  natural  conditions  the  trap  eliminates  unwelcome  visitors. 

J.A.T. 

.  Larva  of  Pontania  vesicator. — Rob.  Staeger  {Revue  Suisse  Zool, 
1919,  27,  333-46).  This  gall-wasp  larva  makes  bean-shaped  galls  on 
the  leaves  of  Salix  daphnoides.  The  presence  of  the  %gg  is  not  enough 
to  cause  the  irritation  ;  the  larva  is  necessary.  If  a  gall  be  cut  open, 
the    larva  will  seek  another  open  one  if  that  promises  food.      The 


48- 


SUMMARY   OF  CURRENT  RESEARCHES   RELATING  TO 


full-grown  larva  takes  to  sandy  and  powdery  soil,  and  makes  an  oval 
hollow.  It  spins  a  network  with  strong  compound  ribs  and  more  delicate 
tissue  between  these,  and  attaches  this  to  little  stones  in  the  hollow. 
Soil-particles  also  become  entangled  in  the  web.  As  the  result  of  often- 
repeated  somersaulting  movements  it  makes  an  oval  cocoon.  The  first 
pair  of  legs  helps  in  the  cocoon-forming.  Damaged  cocoons  are  repaired, 
but  not  if  the  damage  extends  to  half  of  the  cocoon.  An  excised  end 
€an  be  replaced  apart  from  the  substratum,  and  in  the  absence  of  sub- 
stratum-particles thick  strands  are  made  by  compounding  many  single 
threads.  The  plasticity  of  the  instinctive  behaviour  is  of  great  interest ; 
the  instinct  is  still  capable  of  development.  J.  A.  T. 

Poison  of  Predatory  Hymenoptera. — A.  Ch.  Hollande  (G.R.  Soc. 
Biol.,  1920,  83,  9-11).  Roubaud  has  maintained  that  the  poison  of 
predatory  Hymenoptera,  such  as  wasps,  has  a  twofold  effect,  producing 
paralysis  and  preventing  rapid  decomposition  after  death.  Hollande 
has  studied  twenty-three  paralyzed  Geometrid  caterpillars  taken  from 
the  nest  of  some  Eumenid  or  the  like.  They  were  in  perfect  preserva- 
tion, and  they  reacted  to  the  touch  of  a  needle  by  slight  movements 
of  the  end  of  the  abdomen.  Careful  examination  of  the  tissues  showed 
that  the  cells  were  quite  normal  in  their  staining  reactions.  But  this 
need  not  be  ascribed  to  any  preservative  effect  of  the  poison  ;  it  is 
simpler  to  suppose  that  while  the  poison  anaesthetizes  the  nerve-cells  the 
ordinary  cells  of  the  body  remain  aUve.  J.  A.  T. 

Australian  Honey-ants. — W.  M.  Wheeler  {Proc.  Amer.  Acad. 
Arts  and  Sciences,  1915,  51,  255-86,  12  figs.).     Observations  on  the 


Leptoniyrmex  varians  Emery  var.  ruficeps  Emery, 
o.  Replete  worker.     6.  Head  from  above. 


singular  ants  of  the  genus  Leptomyrmex.  The  worker  is  marked  by  the 
extraordinary  attenuation  and  elongation  of  all  parts  of  the  body 
except  the  abdomen.  There  is  a  very  high  development  of  the  pro- 
ventriculus,  which  functions  as  a  valve  between  the  ingluvies  or  crop 
and  the  ventriculus  or  true  stomach.     The  insects  have  the  habit  of 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  49 

storing  large  quantities  of  liquid  food  in  the  crop.  In  L.  unicolor, 
Trhich  has  not  this  habit,  the  proventriculus  is  much  smaller,  its  valves 
are  proportionally  shorter,  and  the  layer  of  musculature  is  much  thinner. 
The  venation  of  the  fore-wing  in  the  male  is  unlike  that  of  any  known 
ant.  Another  peculiarity  is  the  absence  of  a  queen  or  female  caste  in 
any  of  the  known  species.  The  nests  are  in  the  ground  or  in  great 
rotten  logs,  but  the  large  size  of  the  nests,  and  the  very  slender  and  frail 
stature  of  the  ants,  suggest  that  the  insects  take  possession  of  cavities 
made  and  abandoned  by  lizards  or  small  marsupials.  When  walking  or 
running  they  carry  the  gaster  bent  up  at  right  angles  to  the  long  thorax, 
hence  the  name  "  motor-car  ants."  They  forage  singly,  and  are  highly 
carnivorous,  sucking  the  juices  of  their  victims,  which  are  usually 
insects.  Except  in  L.  loiicolor,  all  colonies  showed  a  certain  percentage 
of  "  repletes  "  with  the  gaster  distended  with  fluid  ;  they  are  able  to  run 
about,  but  they  devote  themselves  very  sedulously  to  the  larvae  or  pupae. 
The  larvae  are  very  peculiar,  with  vestigial  mandibles  ;  they  imbibe  liquid 
food.  The  adults  have  a  rancid-butter  odour.  The  probability  is  that 
one  or  more  fertile  workers  in  each  nest  supply  the  eggs.        J.  A.  T. 

Myrmecophily  in  Uncaria. — E.  de  Wildeman  {C.  R.  Soc.  Biol. 
1919,  82,  1076-8).  In  a  species  of  this  Rubiaceous  genus  the  lower 
internodes  of  the  lateral  branches  show  a  hollow  swelling  tenanted  by 
ants.  The  cavity  is  continued  at  its  base  into  a  cavity  of  the  adjacent 
internode  of  the  main  stem.  There  are  numerous  regularly  arranged 
rounded  apertures  leading  into  the  myrmecodomatia.  It  is  suggested 
that  the  frequency  of  myrmecodomatia  in  plants  growing  in  marshy 
places  or  by  the  sides  of  rivers  has  to  do  with  the  unsuitability  of  the 
soil  for  underground  nests.  J.  A.  T. 

Immunity  of  Caterpillars  of  Galleria  melonella.— S.  Metal- 
NIKOFF  (C.  R.  Soc.  Biol,  1920,  83,  119-21).  These  beehive  cater- 
pillars were  injected  with  various  pathogenic  microbes  fatal  to  higher 
animals,  but  seemed  quite  refractory.  This  applies  to  microbes  like 
those  of  tetanus,  tubercle,  diphtheria,  plague,  and  yet  the  caterpillars  are 
very  susceptible  to  saprophytic  and  slightly  pathogenic  microbes. 

J.A.  T. 

Adjustments  of  Lymantria  dispar. — Arnold  Victet  {MT.Schiveiz. 
Entomol.  Ges.,  1919, 13, 20-54).  An  account  is  given  of  the  Hfe-history 
of  this  moth  and  of  its  adjustments  to  unusual  conditions.  For  three 
consecutive  generations  the  caterpillars  were  fed  on  leaves  of  Conifers. 
They  ate  the  leaves,  but  the  result  was  an  enfeebling  of  the  race,  as 
regards  growth,  reproductive  success,  and  resistance  to  disease.  In 
many  cases  reproduction  became  impossible.  The  low  temperature  of 
the  environment  is  partly  responsible,  but  the  diet  is  also  prejudicial. 
Lasting  adjustments  to  poplar,  horse-chestnut,  and  Mespilus  germanica, 
and  also  the  dandelion  and  Onohrycliis  saliva,  seem  to  be  quite  practic- 
able. J.  A.  T. 

Chromosomes  in  Tiger-beetles.  —  W.  M.  Goldsmith  {Journ. 
Morphol,  1919,  32, 437-87, 10  pis.).     The  early  spermatogonia  occur  in 

£ 


50  SUMMARY   OF  CURRENT   RESEARCHES   RELATING  TO 

groups  of  syncytia,  each  syncytium  behaving  like  a  unit  of  cellulai 
activity.  The  early  oogonia  have  very  definite  cell  walls.  The 
spermatogonial  number  of  chromosomes  for  five  species  of  Cicinchla  is 
twenty-two.  The  oogonial  and  female  somatic  number  is  twenty-four. 
Definite  pairs  of  chromosomes  are  readily  recognized  in  .every  clear 
spermatogonial,  oogonial,  and  somatic  metaphase  plate.  The  eleven 
chromosomes  of  the  first  spermatocyte  are  very  irregular  in  shape  and 
especially  difficult  to  figure.  Autosomes  in  the  form  of  complete  and 
incomplete  V's  of  various  sizes,  rings,  hooks,  and  rods  were  figured 
from  side  views  of  the  spindles.  The  secondary  spermatocyte  numbers 
of  chromosomes  are  ten  and  twelve,  much  more  uniform  than  those  of 
the  first  spermatocyte.  The  "sex- chromosome"  appears  on  the  first 
spermatocyte  spindle  as  a  double  body,  the  two  elements  (X,  x)  of  which 
are  very  unequal  in  size  and  loosely  united.  These  elements  neither 
divide  nor  separate  in  the  first  division,  but  pass  to  one  pole  in  advance 
of  the  autosomes,  giving  secondary  spermatocytes  with  ten  and  with 
twelve  (10  +  X  +  x)  chromosomes  respectively.  In  the  second  division 
the  components  of  the  bipartite  body  separate.  The  germ  cells  of  the 
female  seem  to  contain  approximately  twice  as  nuich  X  chromatin  as  is 
found  in  those  of  the  male.  J.  A.  T. 

Intestinal  Glands  in  Larval  Insects. — ^J.  Pantel  {La  Cellule, 
1914,  29,  393-429, 1  pi.,  2  figs.).  In  larvae  of  PtychopteridEe  there  are 
five  Malpighian  tubes,  two  directed  forwards  and  partially  transformed 
into  large  sacs  distended  with  granular  calcareous  concretions,  the  others 
directed  backwards.  The  minute  structure  of  the  tubes  is  described. 
The  tubes  are  bound  to  other  structures  by  muscular  fibres.  During 
the  pupation  the  posterior  tubes  pass  without  disintegration  into  the 
imaginal  structure  ;  the  sacciform  tubes  expel  their  contents  into  the 
intestine,  whence  it  is  got  rid  of,  and  pass  into  the  imaginal  structure  ; 
the  muscular  fibres  degenerate.  The  calcareous  granules  are  to  be 
regarded  simply  as  products  of  renal  excretion.  J.  A.  T. 

Dipterous  Parasite  of  Peaches. — J.  Legendre  (C.  R.  Soc.  Biol. 
1920,  83,  8-9).  Madagascar  peaches  are  much  spoiled  by  amber- 
coloured  maggots  of  Ceratitis  capitata,  often  called  the  "  orange  fly," 
which  is  well  known  in  the  Mediterranean  region,  in  Africa,  Mauritius 
and  Reunion.  '  J.  A.  T. 

Dorsal  Blood-vessel  in  Larval  Muscids. — J.  Pantel  {La  Cellule, 
1914,  29,  318,  3  figs.).  Description  of  the  minute  structure  of  the 
posterior  region  of  the  dorsal  blood-vessel  in  larva3  of  Thrixion, 
Comimlura  and  Ceromasia,  showing  differences  in  detail  in  these  types. 

J.  A.  T. 

Cyrtopogon  platycerus  Villeneuve. — J.  Escher-Kundiq  {MT. 
Schweiz.  Entomol.  Ge.^.^  1919,  13,  54-9,  3  pis.).  A  description  of  the 
hitherto  unknown  male  of  this  rare  predatory  fly,  which  the  author  found 
at  Novaggio,  in  the  Malcantone  Valley.  Its  sex  dimorphism  is  compared 
with  that  of  C.  longiharhus  Low.,  and  a  careful  description  is  given  of 
both  sexes.  J.  A.  T. 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  51 

Midge  Infesting  Potatoes. — Edith  M.  Patch  {Journ.  Econ.  Ento- 
molofjy,  1917,  10,  472-3,  1  pi ).  A  Chironomoid  larva,  probably  a 
species  of  Camptocladius,  was  found  as  a  miner  in  potatoes  in  Maine,  a 
very  unusual  habit  which  may  have  been  induced  by  some  peculiar  local 
condition.  J.  A.  T. 

Parasite  of  Blueberry  Maggot. — W.  C.  Woods  {Canadian  Ento- 
mologist^ 1915,  47,  293-5,  1  pi).  From  apple  maggots  or  "  railroad 
worms  "  {Rhagoletis  pomoneUa  Walsh),  infesting  the  fruits  of  the  blue- 
berry in  Maine,  there  emerged  specimens  of  a  Braconid  {Biosteres 
rhagoletis  sp.  n.)  which  are  described  by  E.  A.  Richmond  in  this  paper. 

J.  A.  T. 

Philippine  Species  of  Phlebotomus.— Charles  S.  Banks  {Philip- 
pine  Journ.  Science,  1919,  14,  163-7,  1  pi.).  A  description  of  Phle- 
botomus nicnic,  a  minute  moth-fly  (Psychodid),  about  2  mm.  in  length, 
which  gives  an  extremely  severe  bite,  more  painful  than  that  of  most 
mosquitoes.  Its  grey  shaggy  appearance  makes  it  difficult  to  be  seen 
against  the  skin.  The  genus  is  represented  in  India  and  Ceylon,  but  this  is 
the  first  Philippine  record.  It  is  believed  that  the  "  nicnic  "  breeds  in 
kitchen  drains.  The  tiny  fly  is  a  serious  factor  in  human  existence  in 
the  Philippines,  and  is  not  improbably  an  agent  in  disease  transmission. 

J.  A.  T. 

Psyllid  Gall  on  Juncus. — Edith  M.  Patch  {Psyche,  1916,  23, 
No.  1,  1  pL).  The  normal  compact  inflorescence  of  Juncus  is  some- 
times replaced  by  a  monstrous  tassel  of  the  nature  of  a  gall.  It  is 
shown  that  this  is  due  to  the  young  stages  of  a  beautiful  little  Psyllid, 
Livia  maculipennis,  which  Fitch  described  in  1857  as  frequenting 
-swampy  places.  J,  A,  T» 

Meadow  Plant-bug.— Herbert  Osborn  {Journ.  Agric.  Research, 
1918,  15,  175-200,  1  pi.).  An  account  of  3Iiris  dolahratus,  common  in 
timothy  meadows  in  the  eastern  United  States  during  the  past  forty 
years,  and  now  distributed  as  far  west  as  Illinios  and  as  far  south  as 
Kentucky.  It  is  believed  to  be  of  European  origin.  It  feeds  on 
cultivated  grasses.  There  are  dimorphic  females,  about  90  p.c.  short- 
winged,  and  the  rest  long-winged.  The  species  hibernates  in  the  egg- 
stage.  The  %gg  is  thrust  into  the  stem  of  grass  or  clover  and  remains 
protected  in  the  hollow  before  hatching.  Rotation  and  other  practical 
measures  are  suggested.  The  known  natural  enemies  are  spiders,  the 
predacious  damsel  bugs,  a  Tachnid  fly,  and  a  fungus.  J.  A.  T. 

Glyphotaelius  punctatolineatus.— F.  Ris  {MT.  Schweiz.  Entomol. 
Ges.,  1919,  13,  17-9).  This  is  one  of  the  most  notable  of  Pal^earctic 
Trichoptera,  remarkable  in  size  and  beauty.  The  author  reports  its 
occurrence  among  the  Bog-bean  {Menyanthes)  leaves  by  the  side  of  an 
Alpine  lake  (at  an  elevation  of  1302  metres)  in  Toggenburg.  The 
gelatinous  egg-masses  were  attached  in  thousands  to  the  leaves,  but  the 
It  is  probable  that  they  are  nocturnal  in  habit. 

J.  A.  T. 
E  2 


52 


SUMMARY   OF  CURRENT   RESEARCHES   RELATING   TO 


Ceriparous  Cells  in  Lecanium  persicae. — G.  Teodoro  {Bull:  Soc, 
Entomol.  Ital.,  1919,  50,  23-7).  There  are  free  ceriparous  cells  or 
cerodecytes  in  the  hsemolymph,  and  there  are  others  which  occur  in 
groups  contiguous  to  a  tracheal  trunk  (the  so-called  hypo-stigmatic 
glandular  cells).  The  two  sets  differ  not  only  in  localization  but  also  in 
their  minute  structural  details.  J.  A.  T. 

Coccidae  of  South-western  United  States.  —  Gordon  Floyd 
Ferris  {Leland  Stanford  Junior  University  Fuhlications,  1919,  1-68, 
38  figs.).  An  account  is  given  of  a  large  number  of  Coccidae  collected 
in  the  arid  regions  of  the  south-western  portion  of  the  United  States. 
Numerous  new  forms  are  recorded  and  defined,  and  numerous  previously 
named  forms  are  re-described.  J.  A.  T. 

Mealy  Bugs  of  California. — Gordon  Floyd  Ferris  (Leland 
Stanford  Junior  University'  Publications,  1918,  1-77,  3  pis.).  In 
addition  to  systematic  descriptions  there  is  a  discussion  of  the  taxonomic 


Section  through  a  wax-gland  of  Eriococcus  adenostomx  Ehrb. 


value  of  the  characters  of  the  antennae,  legs,  dorsal  ostioles  (from  which 
globules  of  secretion  exude),  cercarii  (marginal  groups  of  pores  and 
differentiated  spines  from  which  arise  the  characteristic  tassels  or 
filaments  of  wax),  the  pores  and  ducts  of  the  wax-secreting  glands,  and 
the  setae  of  the  body.  J.  A.  T. 

Mound-building  Termites  of  Philippines.  —  Leopoldo  B. 
UiOHANCO  {Philippine  Journ.  Sci.^  1919,  15,  59-65,  4  pis.).  The 
mounds  make  by  species  of  Termes  in  the  Philippines  rarely  exceed 
2  metres  in  height.  Beneath  the  thick  outer  crust  of  clay  there  are 
numerous  coral-like  "fungus  gai'dens"  of  woody  and  plaster-hke 
material.  The  "mushrooms"  may  crop  out  on  the  surface  and  are 
eaten  by  man.  Counts  of  swarms  gave  an  average  of  five  females  to  a 
hundred  males.  The  swarms  are  thinned  by  bats,  birds,  lizards  and 
other  enemies.  After  shedding  their  wings  the  couples  run  about,  and 
a  pair  seem  able  to  make  a  new  colony.     In  about  three  months  there 


ZOOLOGY  AND  BOTANY,  MICROSCOPY,  ETC.  53 

are  workers  enough  to  make  a  fungus  garden.  *'  The  queen's  life  has 
been  estimated  to  last  about  twenty  years."  The  male  is  short-lived. 
The  "  guests  "  of  the  termitary  are  largely  scavengers.  J.  A.  T. 

The  Genus  Krisna. — C.  F.  Baker  [Philippine  Joum.  Sci.,  1919, 
15,  209-20,  5  pis.).  A  common  evening  visitor  to  one's  table-lamp 
almost  anywhere  in  the  Malaisian  countries  is  a  vividly  virescent  leaf- 
hopper  of  the  genus  Krisna,  a  half  inch,  more  or  less,  in  length,  and 
with  the  transverse  fore  margin  of  the  vertex  black  or  a  bright  reddish 
colour.  This  is  likely  to  be  Krisna  strigicollis,  but  there  are  many 
other  species.  The  present  paper  deals  with  the  genus  Krisna  and  the 
allied  genus  Gessius,  both  members  of  the  tribe  Stegelytraria. 

J.  A.  T. 

Jumping  Plant-lice  of  the  Palaeotropics  and  the  South  Pacific 
Islands. — David  L.  Crawford  {Philippine  Joum.  Sci.,  1919,  15, 
139-207,  3  pis.,  3  figs.).  An  extension  of  our  knowledge  of  the  Psyllid 
or  Chermid  Homoptera  of  these  regions.  The  author  takes  a  taxo- 
nomic  survey  of  the  family  and  describes  numerous  new  species.  There 
<are  some  very  interesting  evolutionary  features  in  the  Psyllid  fauna  of 
oertain  island  groups.  Thus,  in  the  Hawaiian  Archipelago,  thirteen  of 
the  fifteen  known  species  are  apparently  derivatives  of  one  species  long 
ago  established  there.  Some  of  these  species  have  diverged  so  far  from 
the  ancestral  type,  a  Trioza,  that  two  other  generic  groups  embrace 
them.  In  the  Malay  Archipelago  the  genus  Megatrioza  is  abundantly 
represented,  but  extends  into  the  Philippines  and  south  into  Australia, 
and  one  species  has  found  its  way  as  far  south  as  the  Hawaiian  Islands. 
Several  other  genera  appear  to  have  sprung  from  this  one.  Economi- 
cally the  family  is  of  less  importance  than  the  Aphididae  and  much 
less  than  the  Coccidse.  Buckton's  Psylla  isitis  (probably  the  same  as 
Crawford's  Arytaina  jnmctipenfiis)  is  a  pest  on  indigo  ;  and  Euphalenis 
citri  on  citrus  trees.  J.  A.  T. 

Hermaphroditism  in  Lice. — D.  Keilin  and  Gr.  H.  F.  Nuttall 
{Parasitology,  1919,  11,  279-328,  6  pis.,  28  figs.).  No  fewer  than  155 
hermaphrodites  of  Pedicnlus  humanus  were  studied.  They  were  of 
various  degrees,  all  of  them  "  mixed  gynandromorphs,"  and  including 
representatives  of  Cockayne's  three  groups — genetic,  primary  somatic, 
and  secondary  somatic  hermaphrodites.  The  hermaphroditism-  is  often 
accompanied  by  secondary  malformations — viz.  fragmentation  of  the 
<iorsal  bands,  disoriented  proliferation  of  the  genitalia  of  one  sex,  and 
various  invaginations,  devaginations  and  prolapses  of  the  genitalia. 
These  prolapses,  in  the  male  organs,  are  due  to  atrophy  of  the  retractor 
muscles  and  basal  plate,  whilst  in  the  female  organs  the  prolapses  are 
-either  due  to  the  abnormal  development  or  to  coital  traumatism.  The 
•structure  of  the  hermaphrodites  indicates  that  they  may  be  either  sexu- 
ally non-functional  or  functional,  serving,  in  the  latter  case,  as  males  or 
as  females  in  respect  to  copulation.  In  "  wild  "lice  the  few  lots  which 
comprised  hermaphrodites  had  0  *  2  to  8  p.c.  of  them.  In  the  progeny  of 
•crosses  between  P.  capitis  and  P.  corporis,  some  families  gave  over  20  p.c. 
of  hermaphrodites  (always  associated  with  a  great  decrease  in  the  pro- 


54  SUMMARY   OF  CURRENT  RESEARCHES  RELATING  TO 

portion  of  females  to  males).  Other  abnormalities  not  connected  with 
hermaphroditism  are  discussed.  It  is  shown  that  the  P.  capitis  may 
acquire  all  the  characters  of  P.  corporis;  the  two  are  but  races  of 
P.  humanus.  J.  A.  T. 

Abor  Collembola. — G.  H.  Carpenter  {Records  Indian  Museumy 
1917,  8,  561-8,  3  pis.).  A  new  genus,  Cyp^hoder apsis,  is  established  for 
G.  keyyipi  sp.  n.,  a  blind,  pale,  scaled  spring- tail,  found  by  Stanley  W. 
Kemp  under  stones  at  Rotung,  North-East  Assam,  at  an  elevation  of 
1400  feet.  The  spring  has  a  rigid  tapering  dens,  with  a  double  row 
of  strong  spines  and  a  delicate  distal  scale-appendage.  The  mucro  is 
elongate  and  narrow,  with  terminal  and  dorsal  teeth.     This  remarkable 


Cyphoderojpsis  kempi  g.  et  sp.  n.    Lateral  view. 

genus  resembles  Cyphoderns  in  many  respects,  and  may  be  regarded  as 
a  connecting  link  between  typical  Cyphoderini  and  the  Paronellini.  Its 
features  are  so  striking  that  Carpenter  has  no  hesitation  in  establishing 
the  ne,v  genus  and  species  on  a  single  specimen.  New  species  of 
Protanura,  Lepidocyrtus^  and  Paronella  are  described.  J.  A.  T. 


y,  Myriopoda. 

Occurrence  of  Craterostigmus  tasmanianus  in  New  Zealand. — 
Gilbert  Archey  {Trans.  New  Zealand  Inst.,  1916, 49,  319-20).  This 
unique  genus  of  centipedes,  the  sole  representative  of  the  order  Cratero- 
stigmophora,  occupies  according  to  Pocock  an  intermediate  position 
between  Scolopendromorpha  and  Lithobiomorpha.  It  has  hitherto  been 
known  only  from  two  specimens  collected  on  the  summit  of  Mount 
Rumney,  Tasmania.  It  has  now  been  found  abundantly  within  a  certain 
range  in  New  Zealand.  "  The  occurrence  of  such  an  archaic  form  as 
Craterostiymus  in  both  New  Zealand  and  Tasmania  is  of  considerable 
interest,  for  it  may  be  regarded  as  having  some  significance  in  connexion 
with  the  question  of  a  former  land  connexion  between  these  two 
countries."  J.A.  T. 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  55 

Lithobiomorpha  of  New  Zealand. — Gilbert  Archey  [Trans.  New 
Zealand  Inst,  1916,  49,  303-18,  46  figs.).  Hitherto  only  six  species 
of  this  sub-order  of  centipedes  have  been  known  from  New  Zealand. 
The  author  adds  three  new  species  of  Lamyctes,  two  new  species  of  the 
genus  Paralamyctes  (hitherto  not  known  to  be  represented  in  New 
Zealand),  and  two  new  species  of  a  new  genus,  Wailamyctes.  A  key  to 
the  families  is  given.  J.  A.  T. 

Revision  of  SpirobolidsB. — J.  Carl  {Revue  Suisse  Zool.,  1919,  27, 
377-404,  42  figs.).  An  account  of  Rhinocricus,  Messicobolus,  Saussuro- 
lolus  g.  n.,  Xenoholus  g.  n.,  CheloyonoMus  g.  n.,  and  Spiroiolus,  with 
especial  reference  to  the  minute  structure  of  the  gonopods,  which  appear 
to  have  much  systematic  value.  J.  A.  T. 

Alpine  Leptoiulidae. — Walter  Bigler  (Revue  Suisse  Zool.,  1919, 
27,  283-333,  2  pis.,  7  figs.).  An  account  of  seven  Alpine  species,  four 
of  which  are  new.  The  specific  characters  are  crisply  defined,  but  the 
group  shows  a  very  distinct  unity  in  certain  structural  features,  notably 
as  regards  the  copulatory  apparatus.  The  evolutionary  interest  of  the 
unity  amid  diversity  is  discussed  in  detail.  J.  A.  T. 

Revision  of  Glomeridae.— F.  Silvestri  (Records  Indian  Museum, 
1917,  13,  103-51,  35  figs.).  A  systematic  report  on  Indian  Glomeridae, 
a  family  of  Oniscomorph  Diplopoda.  The  author  deals  with  four 
genera — Apiomeris,  Rhopalomeris,  Hyperglomeris  g.  n.,  and  Dinoglomeris 
g.  n. — and  26  species.  J.  A.  T. 

5.  Arachnida. 

The  Genus  Oxus— Charles  D.  Soar  {Journ.  QueTcett  Micr.  Clul), 
1919,  14,  1-6,  1  pL).  A  revision  of  this  genus  of  water-mites,  of  which 
there  are  three  British  representatives,  0.  plantar  is  Sig.  Thor.,  0.  ovalis 
(Miill.)  Koenike,  and  0.  strigatus  (Miill.)  Piersig.  J.  A.  T. 

New  Species  of  Arrhenurus. — Ruth  Marshall  (Trans.  Atner. 
Micr.  Soc,  1919,  38,  275-81,  3  pis.).  About  90  genera  of  Hydrachnidse 
are  now  recognized,  with  some  800  species.  About  one-fourth  of  these 
species  belong  to  the  genus  Arrhenurus.  Fifty-five  have  been  described 
for  North  America,  chiefly  from  the  Upper  Mississippi  Valley.  This 
paper  adds  one  new  species  from  Wisconsin,  six  from  South  America, 
and  two  from  China.  J.  A.  T. 


<•  Crustacea- 

Commensalism  in  Hermit-crabs.— R.  P.  Cowles  (Philippine  Journ. 
Sci.,  1919,  15,  81-9,  1  pL).  Observations  on  the  partnership  between 
hermit-crabs  and  sea-anemones.  The  careful  transfer  of  the  sea- 
anemones  from  the  old  shell  to  the  new  one  was  observed  in  two  species. 
Considerable  inaccuracy  in  the  attachment  was  sometimes  seen.  In 
some  cases  the  anemones  attach  themselves  as  larvae  to  the  mollusc  shell. 
The  behaviour  of  the  hermit-crabs  gives  evidence  of  some  inherited 
nervous  condition  which  directs  the  actions.     We  must  not  credit  the 


56  SUMMARY  OF  CURRENT  RESEARCHES   RELATING  TO 

hermit-crab  with  understanding  what  it  does,  "  yet,  assuming  that  the 
remarkable  behaviour  of  the  hermit  is  due  to  instinct — that  is,  to  an 
'inherited  combination  of  reflexes'  which  have  been  so  brought  to- 
gether by  the  nervous  system  that  the  behaviour  has  become  fixed  and 
adaptive  in  the  species — it  is  extremely  difficult  to  conceive  how  it  has 
acquired  these  habits."  J.  A.  T. 

Arctic  Decapods. — Arvid  R.  Molander  {Arkiv  f.  Zool,  1914,  9, 
1  pi.).  A  synopsis  is  given  of  the  species  of  &pirontocaris^  and  an 
account  of  ^S'.  recurvirostris  sp.  n.,  with  a  long  rostrum  sharply  bent,  with 
its  upper  edge  dentated,  aud  with  the  base  free  from  spines  over  the 
orbits.  A  hermit-crab,  Eupagurus  ])orceUanus  sp.  n.,  from  the  Behring 
Sea,  is  marked  by  the  completely  smooth  surface  of  the  carpopodite  and 
propodite  of  the  right  forceps.  Both  these  joints  are  strongly  developed, 
and  the  propodite  is  rectangular.  J.  A.  T. 

Variability  of  Potamon  edule. — A.  Matteotti  {Bull.  Soc.  Entomol. 
Ital.f  1919,  50,  12-17,  2  figs.).  A  study  of  the  variations  in  this 
Crustacean  as  regards  the  dimensions  and  shape  of  the  abdomen  and  the 
characters  of  the  third  pair  of  maxillipedes.  A  distinction  is  drawn 
between  those  connected  with  the  age  of  the  animal  and  those  which  are 
true  variations.  J.  A.  T. 

New  Species  of  Lernseopoda. — W.  H.  Leigh-Sharpe  {Parasitology, 
1919,  11,  256-66,  7  figs.).     A  description  of  L.  nmstelicola  sp.  n.,  from 
the  smooth  hound  {Mustehis  vulgaris).     Only  the  female  was  obtained 
Among  the  specific  characters  the  following  may  be  noted  :  cephalo 
thorax  pigmented  with  black  dots  ;   proximal  end  of  second  maxillee 
swollen;    ovisacs   short  (4  mm.,   about  two-thirds  length  of   trunk) 
abdominal  appendages  short  (1  mm.,  about  one-sixth  length  of  trunk)  ; 
the  base  of  the  mandible  bears  a  hooked  projection  on  its  inner  side 
The  new  species  is  compared  with  L.  scgllicola,  L.  galei,  and  L.  glohosa 
Strange  tumour-like  growths  from  the  cephalothorax*  of  L.  scyllicola  are 
described,  and  a  detailed  account  is  given  of  the  antennse  of  this  species, 
which  bear  what  may  be  photo-receptors.     These  also  occur  iu  L.  galei 
and  L.  mustelicola,  but  apparently  not  in  L.  globosa,  which  lives  in 
darkness.  J.  A.  T. 

Annulata. 

Stomodseum  of  Lumbricidae — J.  J.  Menzi  {Revue  Suisse  Zool., 
1919,  27,  405-76,  2  pi.,  13  figs'.).  The  stomodseum  begins  as  a  narrow 
blind  ectodermic  tubule,  with  which  the  endoderm  has  no  communication. 
It  grows  back  to  the  fourth  segment,  and  histolysis  occurs  at  the  junction 
of  ectoderm  and  endoderm.  A  muscular  cushion  appears  dorsal  to  the 
stomodaeum,  and  is  the  first  hint  of  the  future  pharynx,  which  is  almost 
certainly  ectodermic  in  origin.  The  stomodaeum  shows  at  first  a 
continuous  internal  ciliation,  but  this  embryonic  character  disappears 
and  the  cilia  are  replaced  by  a  cuticle.  The  pharynx  as  it  grows  extends 
as  far  as  the  sixth  segment.  There  is  general  agreement  that  an  ecto- 
dermic invagination  forms  the  mouth  cavity  in  the  regenerative  process  ; 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  57 

there  is  considerable  discrepancy  in  regard  to  the  pharynx.  The  author 
presents  an  interesting  summary  of  the  data  which  previous  observers 
have  furnished  in  regard  to  the  correspondence  or  lack  of  correspondence 
between  the  embryonic  and  the  regenerative  development  of  the  pharynx. 
He  is  not  inclined  to  draw  embryological  conclusions  from  regenerative 
processes.  J.  A.  T. 

North  American  Oligochaets. — Paul  S.  T\^elch  {Trans.  Amer. 
Microscop.  Soc,  1919,  38,  175-88,  1  pi.).  Continuing  his  studies  on 
Mesenchytrseids,  the  author  gives  an  account  of  Mesenchytrseus  hydrins 
sp.  n.,  from  an  altitude  of  3,400  feet  on  Mount  Rainier.  The  specimens 
crawled  about  in  sand  in  slowly  moving  water,  in  close  proximity  to 
melting  snow.  The  colour  is  light  yellow ;  pigmentation  is  entirely 
absent.  A  description  of  the  reproductive  system  is  given.  A  curious 
feature  is  the  crossing  of  the  elongated  spermothecae.  They  extend 
from  segment  10  forwards,  and  at  the  posterior  end  of  segment  5  or  the 
anterior  part  of  6,  the  right  organ  crosses  to  the  left  side  of  the  body 
and  the  left  organ  to  the  right  side.  A  key  is  given  to  the  species  of 
Mesenchytrseus  known  to  occur  in  North  America.  J.  A.  T. 

New  Echiuroid  Genus  from  Great  Barrier  Reef.— T.  Harvey 
Johnston  and  0.  W.  Tiegs  {Proc.  Limi.  Soc.  N.S.W,,  1919,  44, 
213-30,  3  pis.).  A  description  of  Fseudobonellia  Unterina  g.  etsp.  n., 
an  interesting  relative  of  Bonellia,  but  very  distinct.  The  female  shows 
a  Bo7ieUia-\ike  form,  two  to  four  setaB,  two  well-developed  and  func- 
tional uteri,  simple  anal  glands  opening  directly  into  the  rectum,  an 
ovary  in  a  posterior  transverse  position,  and  a  siphon  associated  with  the 
intestine.  There  is  an  invagination  or  male  tube  within  which  a  single 
male  is  lodged.  The  male  is  extremely  degenerate  and  apparently 
partly  fused  to  the  female.  It  shows  two  functional  vesiculae  seminales  ; 
there  are  no  hooks.  J.  A.  T. 

Nematohelminthes. 

Anomaly  in  Ovary  of  Ascaris  megalocephala. — J.  Dragoiu  and 
E.  Faure-Fremiet  {C.R.  Soc.  Biol.,  1920,  83,  123-5).  An  adult 
female,  about  20  cm.  in  length,  showed  in  the  ovary  no  trace  of  germ- 
cells.  The  lumen  contained  only  mucus.  It  is  probable  that  there  had 
been  in  the  course  of  development  a  suppression  of  the  initial  cell  which 
gives  rise  to  the  germinative  line,  as  contrasted  with  the  somatic  lines  of 
the  ovarian  wall.  J.  A.  T. 

Life-history  of  Ascaris  suilla  —  F.  H.  Stewart  {Parasitology, 
1919,  11,  385-7,  1  pi.).  Continuing  previous  investigations,  the 
author  reports  that  after  giving  about  22,000  ripe  eggs  of  A.  suilla 
to  each  of  two  sucking-pigs  numerous  larvse  were  found  in  the  small 
intestine  of  one  (fourteen  days  after  infection),  but  none  in  the  other 
(nineteen  days  after  infection).  In  another  case  about  50,000  ripe  eggs 
were  given,  and  thirty-one  days  after  no  worms  were  found  in  the 
intestine.  An  account  is  given  of  the  structure  of  a  larva  of  A.  suilla 
taken  from  the  intestine  of  a  pig  fourteen  days  after  infection.    J.  A.  T. 


58  SUMMARY  OF  CURRENT  RESEARCHES  RELATING  TO 

Refractive  Body  of  Spermatozoon  in  Ascaris  canis. — A.  C.  Walton 
(Proc,  Amer.  Acad.  Arts  and  Sci.,  1916,  52,  255-66,  2  pis.).  The 
"  refractive  body  "  of  the  spermatozoon  is  formed  in  the  vas  deferens 
by  a  fusion  of  the  "  refringent  vesicles  "  of  the  spermatocytic  stages. 
These  "refringent  vesicles"  are  formed  from  the  cytoplasm  of  the 
spermatocytes  through  the  action  of  small  extruded  granules  of  karyo- 
chromatin,  the  "  karychondria  "  of  Wildman.  The  "  refractive  body  '* 
in  Ascaris  canis  takes  no  part  in  the  fertilization  of  the  egg  other  than 
as  a  source  of  food  supply  to  the  spermatozoon  between  the  time  of 
copulation  and  the  time  of  "  insemination  "  (surely  an  incorrect  use  of 
the  word,  instead  of  fertilization).  Plastochondria,  the  so-called  mito- 
chondria, which  cluster  round  the  nucleus  of  the  spermatozoon,  are  not 
plasma-bearers  of  hereditary  factors.  They  are  partly  of  plastosomal 
and  partly  of  karyochondrial  origin,  being  formed  in  the  "  refringent 
granules."  J.  A.  T. 

Hew  Nematode  from  a  Baboon. — C.  H.  TuEADaoLD  {Parasitologijy 
1920,  12,  113-34,  2  pis.).  A  description  of  Loapapionis  sp.  n.,  occur- 
ring in  larval  and  adult  conditions  in  subcutaneous  tissues  and  some 
other  regions  of  Fapio  cynocephalus  from  French  Guinea.  The  inter- 
mediate host  is  unknown.  The  larvae,  unlike  those  of  the  human 
parasite  Loa  loa,  show  no  diurnal  periodicity.  Some  adults  show 
bacterial  disease.  There  is  evidence  of  both  traumatic  and  toxic  action 
on  baboons.  The  ova  and  larvae  are  described,  and  a  number  of  struc- 
tural features  are  elucidated.  The  so-called  excretory  and  genital  cells 
of  the  larvae,  as  described  by  Rodenwalt,  are  frequently  not  individualized 
at  all  ;  their  outline,  when  present,  may  be  double  or  incomplete  ;  no 
chromatin  or  nucleus  could  be  seen.  Hanson's  *'  buccal  apparatus  ** 
would  seem  to  be  nothing  more  than  an  optical  illusion.  J.  A.  T. 

Flatyhelminthes. 

Swiss  Helminths.— 0.  Fuhrmann  (Revue  Suisse  Zoologie,  1919, 
27,  353-76,  1  pi.,  11  figs.).  An  account  of  Notocotylus  seineti^^.n., 
an  interesting  form  from  the  caeca  of  Querquednla  querquedida  ;  Davainea 
urogalli  (Modeer)  ;  D.  tdraonensis  sp.  n.  from  Tetrao  urogalli ;  and 
D.progloitina  Dav.,  which  is  probably  the  same  as  B,  varians.     J.  A.  T.- 

Pigmentation  of  a  Polyclad.— W.  J.  Crozier  {Proc.  Amer.  Acad. 
Arts  and  Sci.,  1917,  52,  725-9,  1  pi.).  In  a  Polyclad  Turbellarian 
belonging  to  the  genus  Pseudoceros,  found  in  association  with  various 
Tunicates,  e.g.  Ectinascidia,  there  is  a  parallel  between  the  coloration  of 
the  Turbellarian  and  that  of  the  Tunicate.  At  least  a  good  fraction  of 
the  colour  is  due  directly  to  the  food  in  the  alimentary  canal ;  and  it 
seems  practically  certain  that  the  three  colour  varieties  studied  are 
"  physiological  varieties  "  (or  modificational  forms)  of  one  species,  feed- 
ing on  different  hosts.  The  readiness  with  which  these  Polyclads  return 
to  their  own  particular  kind  of  Tunicate  is  interesting.  J.  A.  T. 

New  Trematode  from  Little  Brown  Bat.  —  Ernest  Carroll 
Faust  {Trans.  Amer.  Microc.  Soc,  1919,  38,  209, 1  pi.,  1  fig.).     A  new 


ZOOLOGY  AND  BOTANY,  MICROSCOPY,  ETC. 


59 


genus,  Acanthatrium^  is  established  for  Lecithodendrkcm  sphserula  Looss, 
and  for  a  new  form  {A.  nijcteridis)  found  in  the  intestine  of  a  bat 
{Nycteris  Urealis)  in  Illinois.  The  genus  includes  small-sized  Brachy- 
coeUinae,  spherical  to  pyrif  orm,  with  a  genital  atrium  lined  with  numerous 
integumentary  spines  ;  prostate  glands  numerous  ;  testes  pre-acetabular^ 
in  a  plane  with  the  genital  pore  ;  vitellaria  anterior  to  the  digestive 
caeca ;  excretory  system  with  four  groups  of  flame -cells  of  three  each  for 
each  half  of  the  body.     The  fourfold  grouping  may  be  a  common 


The  excretory  system  of  Acanthatrium  nycteridis  g.  et]sp.  n. 

The  natural  size  of  the  fluke  is  0-185-2  mm.  in  length  by  0- 15-0- 16  mm, 

in  breadth. 

denominator  of  the  several  sub-families  of  the  Brachycceliid^e.  From 
the  genus  Lecithodendrium  it  is  necessary  to  separate  off  another  new 
genus,  Mesodendrium,  for  L.  granulosum,  L.  hirsiitum  and  X.  imia. 

J.  A.  T. 


Coelentera. 

Development  of  Sea-anemones. — James  F.  Gemmill  {Phil.  Trans.,. 
1920,  209,  Series  B.,  351-75,  3  pis.).  A  study  of  3Ietridium  dianthus 
and  Adamsia  palliata.  Segmentation  is  equal  or  subequal,  from  the  first 
in  J/.,  beginning  with  the  4-celled  stage  in  A.  There  is  a  bilaminar,. 
greatly  folded,  and  subsequently  often  saucer-shaped  pre-blastula  stage 
in  A.  The  blastulge  are  spherical  hollow  in  J/.,  filled  in  A.,  with  a 
central  non-nucleated  or  sparsely  nucleated  trophic  mass,  produced  by 
constriction  of  the  inner  yolky  ends  of  the  cells  of  the  blastula  wall.  In 
both  M.  and  A.  embolic  gastrulation  occurs,  sometimes  assisted  by  uni- 
polar cell  proliferation,  and  in  A,  the  central  trophic  material  gradually 


60  SUMMARY  OF  CURRENT  RESEARCHES  RELATING  TO 

passes  through  the  in-pushing  endoderm  into  the  cavity  of  the  archen- 
teron.  In  M.  a  small  amount  of  "mesoderm"  is  formed  from  the 
developing  endoderm  cells.  The  blastopore  becomes  the  mouth,  and  in 
early  stages  is  oval  or  slit-like  and  slightly  to  one  side.  The  larva  of  M. 
has  an  aboral  tuft  of  long  cilia  and  an  aboral  sense-organ.  The  stomo- 
dseum  forms  by  in-folding  of  epiblast  at  the  blastopore,  with  subsequent 
elongation  by  interstitial  growth.  There  is  a  definite  8-mesentery 
stage ;  the  sulco-lateral  mesenteries  are  the  first  to  appear ;  the  mesenteric 
filaments  contain  downgrowths  of  stomodaeal  epiblast.  The  planula  is 
provided  with  stinging  cells.  The  young  if.,  prior  to  aboral  fixation  and 
tentacle  formation,  creeps  about,  mouth  downwards,  with  the  stomodseum 
more  or  less  everted.  It  is  probable  that  feeding  takes  place  at  this 
time,  as  in  the  immediately  preceding  late  planula  stage.  It  is  suggested 
that  the  Anthozoa  acquired  an  ectodermic  stomodaBum  and  the  rudi- 
ments of  bilateral  symmetry  during  a  creeping  ancestral  stage,  from 
which  the  Turbellaria  and  the  higher  Metazoa  may  have  been  derived. 

J.A.T. 

Northern  and  Arctic  Alcyonaceae. — Arvid  R.  Molander  (A". 
SvensTca  VetensTcapsakad.  Handlingar.^  1915,  51,  1-93,  3  pis.,  14  figs.). 
Part  of  a  systematic  survey,  with  special  attention  to  localities  and 
depths.  As  regards  structure,  emphasis  is  laid  on  the  details  of  the 
canal-system,  on  the  formation  of  the  calyx,  aud  on  the  spicules. 
Descriptions  are  given  of  Anthelia  borealis  (Dan.),  A.  fallax  Broch., 
Clavularia  arctica  (Sars.),  C.  stormi  Dan.,  Xenia  ivandelii  Jungersen, 
Anthomastus  j^urpureus  (Kor.  &  Dan.),  A.  agaricus  Studer,  Alcyonium 
digitatum  and  two  varieties,  Sympodium  catenatum  (Forbes),  five  species 
of  Gersemia  and  varieties,  six  species  of  Eunephthya^  including  E. 
groenlandka  sp.  n.  J.  A.  T. 

Spitzbergen  Alcyonacea. — A.  R.  Molander  {Zool.  Ergehnisse 
Schived.    Exp.    Spitzbergen,    in   K.   Svenska    Vetenskapsakad,    Handl.^ 

1918,  54,  No.  9,  1-19,  1  fig.).  An  account  is  given  of  Gersemia  rubi- 
formis  (Ehrenberg),  G.  uvaeformis  (May),  G.  clavata  (Dan.),  G.  clavata 

var.  crassa  (Dan.),  G.  fruticosa  (M.  Sars.),  G.  fruticosa  var.  rigida 
Molander,  G.  mirabilis  (Dan.),  and  Eunephthya  glomerata  Yerrill.  The 
species  of  Gersemia  are  difficult  to  deal  with,  and  this  further  study  is 
very  welcome.  Special  attention  is  given  to  the  distribution  of  the 
species.  J.  A.  T. 

New  Genus  of  Tetracoralla. — G.  M.  Ehlers  {Amer.  Jonrn.  ScL, 

1919,  48, 461-7,  3  figs.).  A  new  genus  and  species,  Heterolasma  fctrsteij 
from  the  Niagaran  of  Michigan,  seems  to  represent  an  aberrant  depar- 
ture from  Zaphrentis,  differing  (like  Amplexus)  in  not  having  the  septa 
reach  the  centre  of  the  corallum.  The  genus  is  also  characterized  by 
its  wide  tabulae,  its  shape  (a  short  cone  with  more  or  less  horizontally 
extended  margins),  and  the  diversity  in  the  form  of  the  septa.    J.  A.  T. 

Development  of  Colonies  of  Aglaophenia. — Maurice  Bedot  {C.R. 
Soc.  Phys.  His.  Nat.  Geneve,  1919,  36,  50-7,  4  figs.).     The  author 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,  ETC. 


61 


distinguishes  a  primitive  stem  (A),  without  hydrocladia,  with  a  naked 
basal  region  and  a  region  with  cauline  hydrothecae.  When  the 
hydrocladia  begin  to  be  formed,  the  colony  has,  for  a  time,  a  transitory 
stem  (B)  in  which  may  be  distinguished  a  basal  region  (Rb),  a 
hydrocladial  region  (Rh),  and  an  intermediate  region  (Ri),  the  cauline 
joints  of  which  bear  hydrothecae.  The  definitive  stem  (C)  is  characterized 
by  the  disappearance  of  cauUne  hydrothecae.     The  joints  of  its  inter- 


A  B  C 

Diagram  of  three  stages  in  the  development  of  the  stem  of  Aglaophenia. 

mediate  region  bear  nematothecas  only.  The  figure  shows  the  typical 
architectonic  scheme  for  a  colony  arising  from  a  larva  and  not  arising 
by  budding  from  a  hydrorhizal  stolon.  Modifications  of  the  scheme 
may  arise  in  various  ways.  J.  A.  T. 

Variations  of  Aglaophenia  pluma. — M.  Bedot  {Revue  Suisse 
Zool,  1919,  27,  243-82,  27  figs.)-  An  interesting  study  of  this 
Plumularid,  showing  the  variations  (or  observed  differences)  in  facies, 
size,  hydrorhiza,  stem,  nematothecae,  hydrocladia,  hydrothecae,  gonosomes, 
and  so  on.  The  species  is  re-defined  on  a  broad  basis  of  investigated 
form,  three  varieties  are  established,  and  the  relation  of  A.  pluma  to 
related  species  is  discussed.  J.  A.  T. 

Pcrifera. 

Remarkable  Phenomenon  in  Gemmule  Cells  of  Fresh-water 
Sponge.— H.  van  Trigt  (Arch.  Neerland.  Physiol.,  1918,  2,  594-603, 
3  figs.).     The  turgescent  cells  of  the  gemmule  of  Spongilla  are  seen 


62  SUMMARY   OF  CURRE.^T  RESEARCHES   RELATING   TO 

I)efore  germination  to  expel  drops  of  vitelline  material.  This  prevents 
over-svvelling  of  the  cells,  and  it  may  also  lead  to  cell-division  by  re- 
ducing the  vitelline  maws,  for  cell-division  is  slowed  by  the  presence 
of  much  vitelline  substance.  J.  A.  T. 

Protozoa. 

Heredity  and  Variation  in  Arcella  dentata.  —  R.  W.  Hegner 
{^Genetics,  1919,  4,  95-150,  26  figs.).  The  main  problem  attacked  is, 
Can  heritably  diverse  lines  be  recognized  among  the  descendants  of  a 
single  specimen  of  Arcella  dentata  multiplying  vegetatively  ?  It  was 
found  that  a  large  family 'so  derived  consists  of  a  number  of  branches 
that  are  hereditarily  diverse  with  respect  to  diameter  and  number  of 
spines.  These  diverse  branches  resemble  the  hereditarily  diverse  families 
that  were  obtained  by  vegetative  reproduction  from  different  "  wild  " 
specimens.  The  formation  of  such  hereditarily  diverse  branches  appears 
to  be  a  true  case  of  evolution  that  has  been  observed  in  the  laboratory, 
and  that  occurs  in  a  similar  way  in  nature.  J.  A.  T. 

Culture  of  Amoebae. — Monica  Taylor  {Proc.  R.  Physical  Soc. 
EcUnhurgh,  1919,  20,  179-82).  Amoebae  were  found  flourishing  in  the 
more  or  less  undisturbed  mud  with  abundant  organic  debris  in  flowing 
water  which  secures  good  aeration.  By  adding  wheat  grains  to  the 
mud  and  by  having  sufficient  water-weed  to  secure  aeration,  successful 
cultures  were  kept  up  in  the  laboratory  throughout  the  winter.  Plentiful 
food  and  good  oxygenation  seem  to  be  the  most  important  conditions. 

J .  A.  J.. 

Malarial  Parasite  in  Blood  of  Buffalo. — A.  L.  Shearer  (Bull. 
Agric.  Research  hist.  Pusa,  1919,  90,  1-5,  2  pis.).  The  blood  of  an 
Indian  buffalo  showed  small  and  large  ani  dividing  forms  of  what  is 
probably  a  new  species  of  Plasmodium,  for  which  the  name  hulalis  is 
proposed.  J.  A.  T. 

Toxicity  of  Acids  to  Ciliate  Infusorians. — M.  E.  Collett  {Journ. 
Exper.  ZooL,  1919,  29,  443-72,  6  graphs).  The  order  of  toxicity  of  a 
series  of  acids  varies  with  the  concentration,  the  temperature,  and  the 
species.  The  action  is  therefore  not  simple.  The  H-ion  is  an  im- 
portant factor,  but  not  the  only  one.  The  anions  of  formic,  acetic, 
propionic,  butyric,  valeric,  citric,  benzoic,  phthalic,  and  salicylic  acids  are 
toxic  to  both  Paramecium  and  Euplotes.  The  anions  of  oxalic,  tartaric, 
lactic,  and  malonic  acids  are  toxic  to  Paramecium,  but  not  to  Euplotes. 
The  temperature  co-efficients  indicate  that  both  chemical  and  physical 
reactions  are  probably  concerned  in  the  toxic  effect  of  acids.  A  most 
marked  irregularity  is  shown  by  acetic  and  butyric  acids,  in  that  their 
toxicity  to  Euplotes  (though  not  to  Paramecium)  is  greatly  increased  by 
temperatures  below  as  well  as  above  20°  C.  J.  A.  T. 

Ciliata  of  Lahore.— B.  L.  Bhatia  {Records  Indian  Musewn,  191 G, 
12,  177-83,  3  figs.).     Notes  on  Paramecium  caudat^im,  with  three  con- 


ZOOLOGY  AND   BOTANY,   MICKOSCOPY,   ETC. 


63 


tractile  vacuoles,  as  Biitschli  observed  in  P.  putrinum  ;  on  Holophrya 
indica  sp.  n.,  which  has  a  main  posterior  contractile  vacuole,  and  a 
variable  number  (up  to  seven)  of  subsidiary  vacuoles  feeding  it ;  on 
Lacrymaria  vermicularis  (Ehrbg.),  with  a  single  circlet  of  reflexed  cilia 
anteriorly,  a  single  oval  macronucleus,  and  a  single  contractile  vacuole  ; 


N 


<x^. 


5?7--c.v 


Lachrymaria  vermicularis  (Ehrbg.). 

2,  fully  extended ;    2a,  moderately  extended  ;    26,  fully  contracted. 
Full  length  104  /x.     N,  macronucleus  ;  c.v.,  contractile  vacuole. 

on  a  new  subspecies  of  Loxophyllum  fasciola^  with  contractile  vacuole 
in  two  longitudinal  rows  ;  and  on  other  forms.  J.  A.  T. 


Ingestion  of  Erythrocytes  by  a  Monad  associated  with  Dysentery. 
— F.  G.  Haughwout  and  W.  De  Leon  {Philippine  Journ.  Sci.,  1919, 
14,  207-19,  1  pi).  The  Trichomonads  found  in  the  intestines  of  a 
man  include  members  of  three  genera — Trichomonas,  Tetratrichomonas, 
and  Petitatrichomonas,  with  three,  four,  and  five  anterior  flagella  re- 
spectively. All  are  equiped  with  an  axostyle  and  an  undulating 
membrane  bearing  a  marginal  flagellum,  which  is  continued  beyond 
the  posterior  end  of  the  body  as  a  free  lash.  On  the  basis  of  present 
knowledge,  the  species  of  the  first  two  genera  seem  to  be  lumen-dwelling 
forms  subsisting  solely  on  bacteria.  But  the  authors  have  shown  that 
Pentatrichomonas  is  adapted  to  the  rather  specialized  diet  of  erythro- 
cytes, and  gives  no  evidence  of  being  a  bacteria  eater.  The  actual 
process  of  the  ingestion  of  an  erythrocyte  was  observed;  many  in- 
dividuals contained  an  erythrocyte  ;  in  no  case  was  expulsion  seen.  The 
inclusion  of  a  red  blood  corpuscle  in  a  Pentatrichomonas  was  reported  by 
Chatterjee  in  1915.  J.  A.  T. 

Fission  in  Trichomonads.  —  Charles  A.  Kofoid  and  Olive 
SwEZY  {Proc.  Amer.  Acad.  Arts  and  Sciences,  1915,  61, 289-364,  8  pis., 
7  figs.).  Mitosis  and  multiple  fission  occur  during  periods  of  great 
amoeboid  activity  of  the  Trichomonads  in  the  mucus  of  the  intestinal 
epithelium.     Mitosis  is  premitotic  with  the  nuclear  membrane  intact 


64  SUMMARY   OF  CURRENT   RESEARCHES  RELATING   TO 

throughout  the  period  of  division,  with  nuclear  separation  by  constric- 
tion, which  simulates  amitosis.  It  is,  however,  essentially  mitotic,  with 
extranuclear  division  centres,  intranuclear  spindle  fibres,  and  chromosome 
organization  out  of  a  chromatin  network  and  skein.  The  chromo- 
somes are  four  in  Tetratrichomonas  proivazehi,  five  in  Trichomonas  augusta, 
T.  muris,  and  Eutrichomastix  serpentis.  There  is  one  small  one  and 
some  fairly  constant-size  differences  among  the  larger  ones.  They 
appear  to  be  split  longitudinally  prior  to  their  arrangement  in  the  equa- 


chr.  b<u.  r- 


mar.  fU.  -J 


post.  ax.  gr ..,..: 
post  fL 


t  Diagram  of  Trichomonas  augusta. 

Ant.fl.,  anterior  flagella;  ax.,  axostyle  ;  ax.chr.,  axostylar  chromidia; 
bl.y  blepharoplast ;  chr.  bas.  r.,  chromatic  basal  rod  or  parabasal  body ; 
cyt.,  cytostome ;  cyt.  chr.,  cytoplasmic  chromidia  ;  mar.  fit,  marginal 
fQament;  w.,  nucleus ;  post.ax.gr.,  posterior  axostylar  granules; 
post.fi.,  posterior  flagellum  ;  rh.,  rhizoplast  connecting  blepharoplast 
and  nucleus ;  und.  m.,  undulating  membrane  ;  vac,  food  vacuole. 

torial  plate,  and  seem  to  slip  into  an  end-to-end  position  in  this  plate,  or 
to  be  parted  by  a  transverse  constriction. 

The  extranuclear  organellas  all  share  in  the  mitosis.  The  blepharo- 
plast— from  which  flagella,  rhizoplast,  chromatic  margin  and  basal  rod, 
and  axostyle,  all  take  their  origin — contains  the  division  centre.  It 
parts  into  two  bodies  which  go  to  the  two  poles  of  the  fusiform 
mitotic  nucleus,  spinning  out  the  deeply  staining,  always  extranuclear, 
paradesmose  between  them.  The  daughter  blepharoplasts  may  each 
divide  in  the  polar  position  into  an  axial  centrosome  and  an  adjacent 
basal  granule  to  which  flagella,  paradesmose,  and  parabasal  are  attached. 


ZOOLOGY  AND   BOTANY,  MICROSCOPY,   ETC.  65 

These  two  granules  subsequently  unite.  In  its  divisions  the  blepharo- 
plast  shows  no  independent  mitotic  phenomena.  It  is  not  a  "  kineto- 
nucleus,"  and  its  behaviour  does  not  support  the  binuclearity  hypothesis. 

The  anterior  flagella  are  shared,  two  and  one  respectively,  by  the 
daughter  blepharoplasts,  and  new  outgrowths  complete  the  complement 
of  each  daughter  organism.  The  chromatic  margin  of  the  undulating 
membrane  represents  an  intra-cytoplasmic  posteriorly-directed  flagellum. 
It  splits  longitudinally  to  the  tip  of  its  projecting  end.  The  undulating 
membrane  below  it  also  splits.  The  chromatic  basal  rod  is  the  homo- 
iogue  of  the  parabasal  body  of  Janicki  in  Parajmiia  and  the  Tricho- 
oymphidae.  His  so-called  parabasal  in  Trichomonas  is  in  reality  only 
the  early  stage  of  a  new  parabasal  or  chromatic  basal  rod  at  mitosis, 
hence  its  rarity  and  transitory  nature.  At  mitosis  a  new  parabasal  or 
chromatic  basal  rod  grows  out  in  the  base  of  one  new  undulating  mem- 
brane, while  the  old  parabasal  lies  in  the  other  membrane. 

The  new  axostyles  of  the  daughter  organisms  are  formed  by  the 
jongitudinal  splitting  of  the  old.  The  axostyle  is  not  for  support  or 
fixation  ;  it  is  a  locomotor  organ  used  vigorously  in  the  amoeboid  phases. 
During  mitosis  the  organellge  are  shifted  about  a  good  deal.  Plas- 
motomy  is  long  delayed  after  nuclear  mitosis.  The  plane  of  division  is 
longitudinal.  Multiple  fission  occurs  as  a  normal  phase  of  the  life-cycle, 
and  results  in  an  eight-nucleate  plasmodium  or  somatella.  This  dis- 
integrates into  its  component  members  by  the  successive  detachment  of 
single  merozoites.  This  multinueleate  plasmodium  may  point  on  to 
Metazoa.  J.  A.  T. 

Chromosome  Cycle  in  Gregarines. — A.  Pringle  Jameson  (Quart. 
Journ.  Micr.  Sci.,  1920,  64,  207-66,  4  pis.).  An  account  of  the  life- 
-cycle  of  Diplocystis  scJmeideri,  a  parasite  of  the  cockroach,  with  special 
reference  to  the  behaviour  of  the  nuclei  and  chromosomes.  The  author 
deals  with  the  life-history  as  a  whole,  the  spore  and  the  sporozoites,  the 
penetration  of  the  gut-wall  and  the  growth  of  the  parasite  therein,  the 
growth  in  the  cavity  of  the  body,  the  first  nuclear  division  of  the  adult 
parasite  (gamont),  the  later  nuclear  divisions,  the  peripheral  divisions 
preceding  gamete  formation,  the  formation  of  the  gametes,  the  union 
of  the  gametes,  the  first  division  (reduction  division)  of  the  sporoblast 
nucleus,  the  later  divisions  within  the  spore.  A  comparison  is  made 
between  the  nuclear  phenomena  in  Diplocystis  and  those  in  other 
'Gregarines.  Special  emphasis  is  laid  on  three  points.  1.  In  Diplocystis 
-schneideri  a  "  micronucleus  "  makes  its  way  inside  a  nucleolus,  giving  rise 
to  a  "  karyosome  "  composed  of  two  clearly  differentiated  portions.  A 
similar  construction  of  the  karyosome  occurs  in  many  other  Gregarines, 
and  this  raises  the  question  how  the  entire  Gregarine  "  nucleus  "  is  to 
be  compared  with  the  nucleus  of  a  Metazoan  cell.  It  is  probably  a 
much  more  complex  organ,  comparable  to  a  nucleus  within  a  nucleus. 
2.  Hitherto,  reduction  in  Gregarines  has  been  sought  for  in  the  two 
nuclear  divisions  immediately  preceding  gamete  formation.  But  in  none 
of  the  so-called  "  reduction  divisions  "  which  have  been  described  has 
a  true  reduction  been  demonstrated.  In  Diplocystis  schneideri  the 
reduction   division   has   been  found   to   be   the   first   division  in  tne 


66  SUMMARY   OP  CURRENT  RESEARCHES  RELATING  TO 

sporoblast,  and  this  is  probably  the  stage  at  which  it  occurs  in  other 
forms.  This  mode  of  reduction  offers  a  simple  explanation  of  the  odd 
chromosome  number  which  is  so  common  in  Gregarines  ;  it  is  the 
haploid  number  which  is  present  in  every  nucleus  in  the  whole  life-cycle 
except  the  zygote  nucleus.  3.  As  Dobell  has  shown,  it  is  futile  to  try 
to  interpret  the  Protozoa  in  terms  of  the  Metazoan  cell.  *'  Clarity  of 
thinking  will  not  come  in  Protozoology  until  the  Protozoa  are  fully 
recognized  as  non-cellular  organisms,  comparable  with  whole  Metazoan 
individuals  rather  than  with  their  single  component  cells."     J.  A.  T. 

New  Gregarines. — D.  Kbilin  {Parasitology,  1920, 12,  154-8, 1  pi.,. 
2  figs.).  Descriptions  of  Allantocystis  dasyhelei  g.  et  sp.  n.,  from  the 
midgut  of  the  larva  of  a  Ceratopogonid  {Dasyhelea  obscura),  and  of 
Dendrorhynchus  systeni  g.  et  sp.  n.,  from  the  midgut  of  the  larva  of  a 
Dolichopodid  fly,  a  species  of  Systenus.  In  the  first  the  two  sporont& 
associated  for  reproduction  do  not  change  their  form,  but  secrete  a  very 
long  sausage-like  cyst.  The  only  other  Gregarine  where  the  sporonts  do 
not  contract  before  sporulation  is  Ceraiospora  from  a  Polychast.  In  the 
second  genus  the  epimerite  has  the  form  of  a  disc  surrounded  by 
numerous  more  or  less  ramified  papillae,  which  are  fixed  in  an  epithehal 
cell  of  the  host's  midgut.  At  various  stages  the  cephalont,  shedding  off 
the  epimerite,  can  separate  itself  from  the  host's  epithelial  cell  and 
become  a  free  moving  sporont.  Under  the  longitudinal  striated  epicyte 
there  is  a  network  of  very  well-defined  circular  fibrils  with  oblique 
anastomoses  which  surround  the  whole  Gregarine.  They  correspond  to- 
myocyte  fibrils.  J.  A.  T. 

New  Coccidian. — Paul  Debaisieux  {La  Cellule,  1914,  29,  433-49, 
1  pi.).  A  description"  of  Eimeria  cystis-fellese  sp.  n.  from  the  gall-bladder 
of  the  Grass  Snake  {Tropidonotus  natrix).  The  formation  of  micro- 
gametes  and  of  macrogametes,  the  schizogony  and  the  sporogony  are 
described.  The  life-history  conforms  to  that  already  established  for  the 
genus.  A  comparison  is  made  with  the  species  Coccidium  agamse  from 
an  Agama  and  C.  cerastis  from  a  Horned  Asp.  The  new  species  ha& 
cysts  with  perfectly  hyaline  membrane,  and  the  spores  are  spherical  or 
sub-spherical,  both  distinctive  features.  J.  A.  T. 

Life-history  of  Ceratomyxa  acadiensis  sp.  n. — James  W.  Mavor 
{Proc.  Amer.  Acad.  Arts  and  Science,  1916,  51,  551-74,  3  pis.,  3  figs.). 
A  new  species  of  Ceratomyxa  from  the  gall-bladder  of  Urophycis  chuss^ 
Zoarces  angularis  and  Pseudopleuronectes  americanus.  The  earliest  stage 
contains  a  single  nucleus.  By  a  heteropolar  division  this  single  nucleus 
gives  rise  to  a  trophic  and  a  propagative  nucleus.  The  stage  of  the 
myxosporidium  with  four  nuclei  probably  arises  by  the  division  of  the 
trophic  nucleus  to  form  two  tropho-nuclei,  and  the  division  of  the 
propagative  nucleus  to  form  two  propagative  nuclei.  The  origin  of  the 
sporoblasts  by  the  coming  together  of  cells  originally  separate,  as  de- 
scribed by  Awerinzewifor  C.  drepanopsettse,  is  confirmed  for  C.  acadiensis. 
The  presence  of  valve-cells  and  capsulogenous  cells  is  noted.  The  two 
germ-nuclei  can  be  distinguished  in  the  early  stages  of  spore-formation 
and  until  the  spore  is  completely  formed.  J.  A.  T. 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  67 

Parasitic  Spiral  Organism  in  Stomach  of  Cat. — R.  K.  S.  Lm 
{Parasitology,  1920,  12,  108-12,  1  pi.).  Description  of  an  extremely 
active  organism,  averaging  4  to  8  /a  in  length,  with  regular  closely  set 
spirals  about  0*75  /x  broad,  found  in  the  stomachs  of  eight  cats,  none  of 
which  showed  any  obvious  signs  of  gastric  disturbance.  The  organism 
occurred  in  the  lumina  of  ducts  and  glands  throughout  the  stomach,  and 
also  within  the  oxyntic  cells.  They  were  not  seen  elsewhere  except  at 
the  very  beginning  of  the  duodenum.  The  organisms  are  new  species 
of  Spirochfetoidese.  J.  A.  T. 

Capillitia  of  Mycetozoa. — A.  E.  Hilton  {Journ.  Quekett  Micr.  Club, 
1919,  14,  1-8).  There  is  great  diversity  in  the  nature  of  the  capillitial 
threads  associated  with  the  masses  of  spores  within  the  sporangia  of 
Mycetozoa.  The  threads  may  be  rigid  or  flexible,  free  or  attached,  solid 
or  tubular,  simple  or  branched,  sparingly  forked  or  forming  a  network, 
and  so  on.  They  have  their  origin  in  the  processes,  structural  and 
metabolic,  by  which  the  plasm  of  an  amoeboid  plasmodium  is  converted 
into  the  plasm  of  innumerable  spores.  The  mode  of  development  is 
described.  "From  first  to  last,  the  capillitial  threads,  notwithstand- 
ing their  variety  and  often  elaborate  details,  are  sterile  things,  of  only 
secondary  importance,  and  of  little  biological  significance."     J.  A.  T. 


'    F  2 


68 


SUMMARY   OF  CURRENT   RESEARCHES   RELATING  TO 


BOTANY. 

GENERAL, 

Including  the  Anatomy  and  Physiology  of  Seed  Plants. 

Structure   and  Development. 
Vegetative. 

Embryo  and  Seedling  of  Dioon  spinulosum. — H.  A.  Dorety  {Bot. 
Gaz.,  1919,  67,  251-6,  2  pis.).  The  material  for  this  study  was  grown 
from  ovules  brought  by  Dr.  Chamberlain  from  Mexico,  where  the  plant 
forms  a  magnificent  ornamental  tree  30  to  40  feet  high.  The  study  of 
the  vascular  anatomy  of  embryo  and  seedling  emphasizes  the  general 
harmony  which  prevails  among  the  Cycads  in  this  respect.  The  coty- 
ledons vary  in  number  from  two  to  four,  and  are  often  lobed  or  divided  ; 


Diagram  illustrating  girdling  of  leaf-traces  in  stem. 


in  rare  cases  the  cotyledonary  sheath  is  undivided  except  near  the  tip. 
They  are  mnltifascicular,  resembling  those  of  Ceratozamia  and  Micro- 
ci/cas,  rather  than  those  of  Zamia  and  Cycas,  which  have  but  few  strands. 
The  arrangement  and  orientation  of  the  vascular  strands  of  cotyledons, 
hypocotyl,  stem,  leaves  and  root,  do  not  differ  in  any  marked  degree 
from  the  general  Cycad  arrangement.  The  stem  is  large  enough  to 
demonstrate  the  cause  of  the  girdling  habit  ;  each  node  of  the  stem  is, 
like  the  nodes  on  a  first-year  stem  of  foxglove,  telescoped  within  the 
older  one  instead  of  growing  above  it.  The  internodes  are  not  elon- 
gated because  the  primary  meristcm  of  the  stem- tip  is  held  in  check  by 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  69 

the  more  rapidly  growing  secondary  meristem  for  each  developing  leaf. 
Since  each  leaf  is  supplied  with  strands  from  cauline  bundles  in  different 
parts  of  the  stem,  those  strands  which  come  to  it  from  the  opposite  side 
of  the  stem  describe  almost  a  semicircle  to  reach  the  leaf  ;  those  which 
arise  on  the  same  side  of  the  leaf  pass  directly  into  it,  and  small  arcs  are 
described  by  strands  which  arise  in  intermediate  positions.  There  is  no 
extrafascicular  cambium  or  any  other  vestige  of  polystely.       A.  B.  R. 

Polyxylic  Stem  of  Cycas.— W.  L.  Miller  {Bot.  Gaz.,  1919,  68, 
208-21,  11  figs.).  The  author  has  studied  the  cambium  of  the  stem  of 
Cycas  media  in  order  to  discover  the  origin  and  subsequent  development, 
and  to  form  some  definite  conclusions  concerning  the  unusual  method 
of  secondary  growth  of  the  vascular  elements.  He  has  examined  the 
xylem  and  phloem  of  the  normal  and  first  cortical  cylinders  of  the 
full-grown  stem,  and  finds  that  the  vascular  cylinders  are  of  unequal 
length.  The  normal  cylinder  begins  to  differentiate  at  the  meristem, 
while  the  others  begin  at  successively  lower  joints ;  thus  the  normal 
cylinder  is  the  only  one  which  has  its  origin  in  the  procambium,  and 
which  forms  protoxylem  and  protoplasm.  The  protoxylem  is  usually 
scalariform,  but  elementary  spiral  tracheids  are  not  infrequent.  The 
primary  xylem  is  also  scalariform,  while  the  secondary  xylem  is  pitted. 
In  the  first  cortical  cylinder  there  is  neither  protoxylem  nor  protophloem  ; 
the  xylem  cells  are  mostly  pitted,  but  a  few  scalariform  tracheids  are 
present.  In  the  secondary  phloem  of  both  cylinders  suberised  bast- 
fibres  are  relatively  numerous  in  comparison  with  the  sieve-tubes.  The 
origin  and  development  are  similar  in  all  cortical  cylinders,  and  their 
appearance  is  probably  connected  with  the  plant's  periods  of  activity  and 
rest.  No  material  was  available  for  studying  the  differentiation  of 
cortical  cambium.  S.  G. 

Companion-Cells  in  Bast  of  Gnetum  and  Angiosperms. — W.  P. 
Thompson  {Bot.  Gaz.,  1919,  68,  451-9).  In  previous  papers 
the  author  has  indicated  the  existence  in  Gnetum  of  elements  in  the 
bast  resembling  the  companion-cells  of  the  angiosperms.  The  present 
is  a  comparative  study  of  their  structure  and  development.  Companion- 
cells  resembling  those  of  angiosperms  in  size,  in  their  association  with 
sieve-tubes,  in  their  usual  location  in  the  angles  of  the  sieve-tubes,  and 
in  their  vertical  elongation,  are  present  in  the  bast  of  some  species  of 
Gnetum.  The  development  of  these  companion-cells,  however,  is  quite 
different  from  that  found  in  angiosperms.  Whereas,  in  the  latter,  each 
sieve-tube  and  its  companion-cell  are  derived  from  two  successive  cells 
in  a  single  row  of  cambial  products,  in  Gtietum  sieve-tubes  and  companion- 
cells  are  produced  from  different  rows  of  cambial  cells.  Thus  although 
the  completed  forms  of  companion-cell  in  the  two  groups  are  similar, 
they  have  probably  been  independently  evolved.  Primitive  conditions 
in  which  companion-cells  are  lacking,  or  in  which  continuous  rows  of 
companion-cells  are  present,  are  found  in  certain  regions  of  some  species. 
Thus  they  are  absent  in  the  young  stem  of  G.  moluccense,  also  in  seed- 
lings of  several  species  and  in  reproductive  axes.  The  parenchyma  of 
the  wood  is  formed  by  those  cambial  cells  which  form  companion-cells  ; 


70 


SUMMARY  OF  CURRENT   RESEARCHES   RELATING  TO 


the  distribution  of  the  wood  parenchyma  is  consequently  in  radial  bands, 
which  frequently  become  interrupted  by  the  expansion  of  vessels  and 
fibres.  The  author  has  previously  shown  {Bot.  Gaz.,  1918,  65,  83-90), 
that  in  regard  to  the  similarity  of  the  wood-vessels  with  those  of  angio- 
sperms,  we  are  dealing  with  a  case  of  parallel  evolution  and  not  of 
genetic  relationship.      If  two  such  striking  points  of  resemblance  as 


Wood,  cambium  and  young  bast  of  Gnetum  latifolium^  showing  sieve- 
tubes  and  companion-cells  formed  from  different  rows  of  cambium 
cells ;  also  wood-parenchyma  formed  inwardly  from  those  cambial 
cells  which  form  companion-cells. 

vessels  in  the  wood  and  companion-cells  in  the  bast  are  the  result  of  in- 
dependent evolution  in  Gnetum  and  angiosperms,  the  inference  is  natural 
that  other  resemblances  may  be  in  the  same  category.  x\.  B.  R. 

Hybrid  Sarracenias  and  their  Parents. — A.  M.  Russell  {Univ. 
Pennsy I.  Philadelphia :  Thesis^  1919,  1-41,  5  pis.).  The  author  has 
studied  several  species  of  Sarracenia  in  order  to  compare  their  macro- 
scopic structures  with  those  of  their  parents.  The  hybrid  forms  are 
intermediate  in  nearly  every  detail.  Thus,  the  size  of  the  hybrid  is 
intermediate,  although  there  is  frequently  increased  vigour,  a  feature 
especially  noted  in  hybrids  of  S.  Moorei  and  S.  areolata.  The  inter- 
mediate shape  is  best  seen  in  S.  Catesbsei,  while  other  hybrids  exhibit  a 
distinct  blending  of  botli  parents,  especially  in  smaller  details,  such  as 
the  character  of  the  lid.  In  colour  intermediate  blending  is  well 
shown,  but  with  half  the  intensity  of  the  colour  of  the  parents.  The 
flowers  resemble  those  of  both  parents,  but  tend  to  be  larger  and  more 
showy.  All  the  above  characters  are  readily  visible  to  the  naked  eye, 
but  the  same  intermediate  features  extend  to  the  microscopic  structures. 
The  epidermal  cells  of  the  pitcher  and  the  lid  resemble  those  of  both 
arents,  and  the  number  of  stomata  is  an  exact  arithmetic  mean  of  the 


ZOOLOGY   AND    BOTANY,    MICROSCOPY.    ETC.  71 

numbers  found  in  the  parents.  The  hairs  found  on  both  the  pitcher 
and  the  rim  likewise  show  a  blending  of  the  parental  characters. 
Sections  of  the  pitcher,  the  rim  and  the  lid  show  that  the  cell-structure 
is  intermediate  in  every  respect.  In  all  cases  where  there  are  apparent 
variations  from  exact  blending,  they  are  probably  due  to  the  higher 
state  of  evolution  of  one  of  the  parents.  The  writer  concludes  that 
such  overwhelming  evidence  of  the  blending  of  parental  characters 
■"  points  to  some  exact  relation  in  molecular  structure  of  the  hybrid 
plant,  extending  even  to  the  amount  of  thickening  laid  down  in  a  cell- 
wall,  the  size  of  the  starch-grains,  or  the  size  of  a  chloroplast."    S.  G. 

Ray-tracheid  Structure  in  Second  Growth  in  Sequoia  Washing- 
tonia  (S.  gigantea).— H.  C.  Belyea  {Bot.  Gaz.,  1919,  68,  467-73, 
5. figs.).     Ray-tracheid  structure  is  an  essential  feature  of  the  Coniferales, 


Radial  section  of  second-growth  wood,  showing  wood-tracheid  bent 
and  prolonged  along  the  ray  to  act  as  ray-tracheid. 

but  is  only  constantly  and  normally  present  in  the  older  genera.  In 
the  younger  genera  this  structure  may  or  may  not  be  present,  but  is 
invariably  recalled  under  traumatic  stimulus.  The  author  describes  a 
peculiar  adaptation  in  ray-tracheid  structure  in  the  second-growth  wood 
tissue  of  Sequoia  gigantea.  Ray-tracheid  structures  have  already  been 
found  to  occur  normally  in  both  species  of  the  genus,  S,  gigantea  and 
S.  virens.  In  the  mature  wood  of  the  former  two  kinds  are  to  be 
found — namely,  single  isolated  detached  radially  elongated  elements  on 
the  upper  and  lower  margins  of  the  primary  rays  ;  and,  secondly,  inter- 
spersed ray  tracheids  occurring  in  the  radial  prolongation  of  rays  one 
cell  high.  In  the  present  instance  sections  were  taken  from  the  main 
trunk  of  a  tree  which  showed  a  phenomenally  rapid  growth.  In  this 
specimen  true  ray-tracheids  do  not  occur,  but  the  marginal  structures 
■on  the  rays  of  the  wood  of  second  growth  show  great  variation.  The 
vertical  wood-tracheids  terminate   directly  at  the  ray,  and  there  are 


72  SUMMARY   or   CURRENT  RESEARCHES  RELATING   TO 

communicating  pits  in  the  contiguous  walls  of  the  tracheids  and  tbe- 
parenchyma-cells  of  the  ray.  There  is  also  a  radial  elongation  and 
projection  of  the  ends  of  the  vertical  tracheary  elements  in  a  direction 
parallel  to  and  in  contact  with  the  parenchymatous  cells  of  the  ray,, 
with  communicating  pits  in  the  intervening  walls.  As  true  ray-tracheids^ 
do  not  occur,  it  is  believed  that  these  structures  are  acting  as  such,  and 
possess  all  the  functions  attributed  to  and  carried  on  by  ray- tracheids.. 
In  many  cases  the  course  of  the  bent  and  prolonged  tracheid  is  imitated 
by  those  immediately  contiguous  with  greater  or  less  development. 
These  structures  are  similar  to  those  described  by  Thompson  in  the 
cone-axis  of  Finns  Sirobus,  and  by  Jones  in  the  mature  wood  of 
Sequoia  semperviretis,  A.  B.  R. 

Reproductive. 

Staminate  Strobilus  of  Taxus  canadensis. — A.  W.  Dupler  {Bo(^ 
Gaz.,  1919,  68,  345-66,  3  pis.,  22  figs.).  In  a  previous  paper  {Bot. 
Qaz.^  1917,  64)  the  author  has  described  the  gametophytes  of  this 
species.  The  development  and  vascular  anatomy  of  the  staminate 
structures  are  here  treated. 

The  staminate  strobili  occur  in  the  axils  of  the  leaves.  The  buds 
may  first  be  distinguished  from  other  types  of  buds  by  the  broad  apex. 
The  sporophyll  primordia  first  appear  as  slightly  rounded  lobes  above 
the  general  surface,  and  may  arise  in  acropetal  succession.  The  arche- 
sporial  initials  are  hypodermal  cells  and  develop  according  to  the 
eusporangiate  method.  There  are  4-8  of  them,  distributed  around  the 
margin  of  the  primordium.  The  sporogenous  tissue  reaches  the  mother- 
cell  stage  about  October  1,  and  forms  microspores  about  two  weeks  later. 
There  is  no  abortion  of  sporangia  such  as  occurs  in  Torreya,  the 
sporangia  occurring  in  a  circle  around  the  stalk  of  the  sporophyll.  The 
sporangium-wall  is  usually  two-layered.  The  tapetum  arises  from  the 
peripheral  layer  of  the  sporogenous  tissue  and  persists  until  after 
megaspore-formation.  The  epidermis  of  the  sporangium  remains  alive 
and  thin-walled  at  the  base,  dehiscence  being  accomplished  by  the 
rupture  of  these  cells  at  maturity,  by  the  elongation  of  the  stalk  of  the 
sporophyll.  Owing  to  the  disintegration  of  the  sporangium-wall,, 
the  epidermis  is  the  functional  wall  in  the  later  stages.  The  strobilus. 
matures  in  the  latter  part  of  April.  Just  before  maturity  there  is  an 
enlargement  and  elongation  of  the  axis,  pushing  the  sporophylls  beyond 
the  scales.  The  strobili  of  Taxus  canadensis  are  somewhat  smaller  than 
those  of  T.  baccata.  The  strobilus-bundles  are  collateral  endarch,. 
excepting  in  the  terminal  portions  of  the  scale-bundles  and  the  sporo- 
phyll-bundles,  where  they  may  be  mesarch,  and  in  the  latter  show 
indications  of  occasional  exarch  structure,  the  terminal  portion  of  these 
bundlcK  also  being  concentric.  A.  B.  R. 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  73 

CRYPTOGAMS. 

Pteridopliyta. 

Leaf-architecture  as  Illuminated  by  a  Study  of  Pteridophyta. — 
F.  0.  Bower  (Tratis.  Roij.  Soc.  Edinb.,  1916,  51,  657-708,  1  pi. 
and  figs.).  There  are  three  chief  avenues  which  may  lead  up  to  a 
scientific  knowledge  of  leaf -architecture.  1.  A  comparative  study  of 
adult  leaves  (mature  or  while   developing)   of   many  different  types, 

2.  A  study  of  the  juvenile  leaves  of  an  individual,  tracing  the  gradual 
stages  up  to  the  adult  form  ;  the  results  in  various  forms,  related  or 
otherwise,  may  then  be  made,  especially  those  of  more  primitive  types, 

3.  The  results  of  such  studies  may  be  compared  with  the  fossil  record, 
and  conclusions  obtained  as  to  phyletic  progression.  The  second  avenue 
has  been  somewhat  neglected,  especially  in  the  Pteridophyta.  In  the 
present  paper  the  juvenile  leaves  of  this  group  are  studied  and  compared 
with  results  obtained  from  other  sources.  A  long  summary  of  compara- 
tive conclusions  is  given,  and  a  postscript  on  theories  of  the  ultimate 
origin  of  the  leaf.  A.  Gepp. 

Maceration  of  Carboniferous  Plant-remains.— K.  Nagel  {Natiiriu. 
Wochenschr.,  1917,  15,  569-71,  figs.l;  see  also  Bot.  Centralbl,  1917, 
135,  359).  A  popular  account  of  the  very  important  results  of  the 
recent  experiments  in  macerating  carboniferous  impressions,  in  order  to 
render  possible  a  microscopical  examination  of  the  epidermis  of  pre- 
historic plants.  By  treatment  with  KCIO3  +  HNO3  (Schulze's  macera- 
tion-mixture) the  carboniferous  plant-remains  are  reduced  to  a  soft 
peaty  condition,  which,  after  treatment  with  ammonia  (whereby  the 
insoluble  humus-acid  produced  during  the  oxidation  is  eliminated), 
allows  the  epidermis  to  be  detached  from  the  subjacent  layers  and  to  be 
studied  in  glycerin  under  the  microscope.  Some  preparations  of 
Neuropteris  ovata  Hoffm.,  Anomozamites  gracilis  Nath.,  and  Ctenoptens 
Wolfiana  Goth,  are  described.  The  method  has  been  worked  out 
recently  by  Zeiller  and  others,  and  has  systematically  yielded  great 
results.  A.  G. 

Old  Red  Sandstone  Plants  showing  Structure,  from  the  Rhynie 
Chert  Bed,  Aberdeenshire.  Part  I.  Rhynia  Gwynne-Vaughani 
Kidston  and  Lang.— Pt.  Kidston  and  W.  H.  Lang  (Trans.:Roy.  Soc. 
Edinb.,  51,  1917,  761-84,  10  pis.  and  figs.).  An  account  of  a  new 
genus  of  fossil  plants  summarized  as  follows  :— Rhynia  Gwynne-Vaughani 
grew  in  gregarious  fashion  in  a  peaty  soil  practically  composed  of  the 
decaying  remains  of  the  same  species.  The  land  surface  was  probably 
in  the  neighbourhood  of  water,  and  liable  to  periodic  inundations.  The 
plant  had  no  roots  and  no  leaves.  It  was  entirely  composed  of  branched 
cylindrical  stems.  The  branched  underground  rhizomes  were  attached 
to  the  peat  by  numerous  rhizoids,  most  abundant  on  large,  downwardly 
directed  bulges  of  the  outer  cortex.  Some  of  the  branches  grew  upwards 
as  tapering  aerial  stems.  The  aerial  stems  bore  small  lateral  projections 
irregularly  scattered  over  the  surface.     Some  of  the  projections^  possibly 


74  SUMMARY  OF  CURRENT  RESEARCHES   RELATING  TO 

in  the  lower  regions,  developed  rhizoids.  Some  of  the  projections  at 
various  levels  on  the  stem  gave  rise  to  adventitious  lateral  branches. 
-Some  of  the  lateral  branches,  attached  by  a  narrow  base,  were  readily 
detachable  and  probably  served  for  vegetative  propagation.  Dichoto- 
mous  branching  of  the  stem  occurred  sparingly.  In  the  rhizomes  and 
stems,  epidermis,  outer  cortex,  inner  cortex,  and  stele  can  be  distin- 
guished. The  epidermis  in  the  aerial  stems  had  a  thick  outer  wall, 
and  stomata  were  sparingly  present.  The  cortex  consisted  of  a  narrow 
outer  zone,  which  in  the  aerial  stems  had  the  character  of  a  hypoderma, 
and  a  broader  inner  cortex.  The  more  delicate  tissue  of  the  inner 
•cortex  had  intercellular  spaces  and  was  in  relation  with  the  stomata. 
It  possibly  represented  the  assimilating  tissue.  The  vascular  system 
consisted  throughout  of  a  simple  cylindrical  stele  composed  of  a  slender 
solid  strand  of  tracheids  with  broad  annular  thickenings  and  no 
distinction  of  protoxylem  and  metaxylem.  Surrounding  the  xylem  was 
a  zone  of  phloem  consisting  of  elongated  thin-walled  elements.  No 
vascular  strands  were  given  off  to  the  small  projections  on  the  stem. 
No  vascular  connexion  existed  between  the  stele  of  a  lateral  branch  and 
the  stele  of  the  parent  axis.  In  the  dichotomous  branching  of  the  stem 
the  stele  divided  to  supply  the  two  branches.  The  branch  bore  large 
cylindrical  sporangia.  The  sporangium  had  a  thick  wall,  and  terminated 
a  stout  stalk  which  corresponded  to  a  small  stem.  The  sporangium 
•contained  numerous  spores  which  were  all  of  one  kind.  The  authors 
find  the  plant  to  be  allied  to  Fsilophyton  princeps  Dawson,  and  place 
them  in  a  new  class,  Psilophytales.  A.  G. 

Contributions  to  our  Knowledge  of  British  Palaeozoic  Plants. 
Part  L,  Fossil  Plants  from  the  Scottish  Coal  Measures. — R.  Kij)ston 
{Trans.  Roy.  Soc.  Edinb.,  1916,  51,  709-20,  3  pis.  and  figs.).  Descrip- 
tions and  figures  of  the  fossil  species — Sphenopteris  incurva  (new), 
Sphenophyllum  cuneifolimn,  Sigillaria  elegans,  S.  incerta  (new),  S.  Stri- 
mlensis  (new),  Stigmaria  minuta,  Lagenospermum  parvulum  (new). 

A.  G. 

Anatomy  and  Affinity  of  Platyzoma  microphyllum  R.  Br. — John 
McLean  Thompson  {Trans.  Roy.  Soc.  Edinh.,  1916,  51,  631-56,4  pis. 
and  figs.).  An  account  of  the  structure  of  this  tropical  Australian  fern, 
which  is  notable  for  the  heterophyllous  character  of  its  xerophytic 
foliage.  On  the  horizontal  rhizome,  zones  of  reduced  leaves  usually 
devoid  of  pinnai  alternate  with  zones  of  larger  pinnate  fertile  leaves. 
Bifurcate  leaves  sometimes  occur.  Platyzoma  has  always  been  placed 
in  the  Gleicheniacese,  but  differs  markedly  in  the  crowding  of  its  leaves, 
as  well  as  in  the  remarkable  characters  of  its  stele,  leaf-trace  and 
sporangia.  The  stele  is  protostelic,  a  continuous  ring  without  leaf -gaps  ; 
the  xylem  is  in  two  zones,  the  inner  a  storage  zone  ;  the  bulky  pith  is 
sclerotic  and  mucilaginous,  and  is  surrounded  by  a  continuous  inner, 
distinct  from  the  outer,  endodermis  ;  outside  the  xylem  is  a  narrow  zone 
of  phloem,  a  pericycle,  and  external  endodermis.  The  leaf-traces  issue 
(without  leaf -gap)  from  the  outer  xylem  as  a  crescentic  mass  of  tracheids 
with  an  outer  arc  of  phloem  ;  the  further  development  of  the  leaf -trace 
and  the  behaviour  of  the  endodermis  are  described.     The  sporangia  do 


ZOOLOGY   AND    BOTANY,   MICROSCOPY,   ETC.  75 

nob  constitute  definite  sori,  but  are  distributed  solitarily,  terminally  on 
the  veins  ;  there  is  no  indusium,  but  hairs  occur  along  the  veins  and 
revolute  margins  of  the  pinnae.  The  sporangium  is  short-stalked, 
globular,  with  oblique  irregular  annulus,  interrupted  at  the  stalk ;  the 
stomium  is  variable.  The  larger  sporangia  contain  12-16  large  spores  ; 
the  smaller,  26-32  small  spores.  Flaiyzoma  has  no  close  affinity  with 
Gleicheniaceae,  though  probably  of  common  origin.  A.  G. 

Anatomy  and  Affinity  of  Deparia  Moorei  Hook.— John  McLean 
Thompson  {Trans.  Hoy.  Soc.  Edinh.,  1915,  50,  837-56,  3  pis.  and  figs.). 
An  account  of  the  structure  of  the  sporophyte  of  this  fern,  and  a  dis- 
cussion of  the  significance  of  the  anatomy  of  its  members.  The  phyletic 
and  systematic  position  are  debated  at  some  length,  and  the  conclusion 
is  reached  that  the  morphological  characters  described  in  the  paper  show 
Deparia  Moorei  to  stand  high  in  the  scale  of  ferns,  and  indicate  for  it  a 
Davallioid  affinity.  A.  G. 

Anatomy  and  Affinity  of  certain  Rare  and  Primitive  Ferns.— 
John  McLean  Thompson  {Trans.  Roy.  Soc.  Edinh.,  1918,  52, 363-97, 
7  pis.  and  figs.).  An  account  of  Jamesonia,  Uavea  and  Trismeria, 
Their  structure  is  described  ;  and  they  are  compared  with  Gymnogramme, 
Cryptogramme^  Cheilanthes,  Nothochlaena,  Pellaea,  Ceratopteris  and 
Plagiogyria.  The  anatomical  and  sporangial  characters  are  held  to 
indicate  for  Jamesonia  an  ultimate  origin  from  some  Schizseaceous 
source  ;  the  same  applies  to  Llavea,  which  is  more  advanced  than 
Jamesonia  ;  and  as  to  Trismeria^  the  conclusion  is  that  it  is  not  a  distinct 
genus,  but  an  "  Acrostichoid  "  Gymnogramme.  A.  G. 

Some  Notes  on  Neurosoria  pteroides  (R.  Br.)  Mett.— W.  Walter 
Watts  {Journ.  Froc.  Roy.  Soc.  N.  S.  Wales,  1919,  53,  49-57, 
2  pis.).  This  fern,  originally  named  Acrostichum  pteroides  by  Robert 
Brown,  was  assigned  to  Fhorolobus  by  Desvaux,  by  Mettenius  to 
Neurosoria  n.  g.,  by  Moore  to  Gymnopteris  or  to  Ch^lanthus,  by  Kuhn 
first  to  Allosorus  and  later  to  Neurosoria,  which  genus  Kuhn  described 
at  some  length  in  1869.  Watts  now  criticises  Kuhn's  description  and 
conclusions,  and  decides  that  Neurosoria  should  be  placed  in  the 
Oheilanthinae,  falling  into  the  group  with  thickened  nerve-ends,  but 
with  the  sori  occupying  the  whole  of  the  upper  nerve-branches,  while  in 
Gheilanthes  and  Hypolepis  the  sori  are  confined  to  the  nerve-ends,  being 
more  or  less  confluent  in  Gheilanthes,  and  solitary  at  the  base  of  a  leaf- 
sinus  in  Hypolepis.  A.  G. 

Prothallus  of  Tmesipteris  tannensis. — A.  Anstruther  Lawson 
{Trans.  Roy.  Soc.  Edinb.,  1917,  51,  785-94,  3  pis.).  An  account  of 
the  discovery  of  the  prothallus  of  Tmesipteris  in  Xew  South  Wales,  and 
of  its  structure.  It  is  small,  subterranean,  saprophytic,  characterized  by 
numerous  long  rhizoids,  is  light  brown  in  colour  (hence  inconspicuous 
in  its  habitat),  without  chlorophyll,  associated  symbiotically  with  a 
mycorrhizal  fungus.  The  antheridia  are  large  and  scattered,  the  arche- 
gonia  quite  small  and  numerous ;  and  these  organs,  do  not  much 
resemble  those  of  Eqtiisetwn  or  Lycopodium.     The  description  of  the 


76  SUMMARY  OF  CURRENT  RESEARCHES  RELATING   TO 

embryo  is  postponed  until  better  material  is  available.  The  suggestion 
of  both  Bower  and  Scott  that  Fsilotum  and  Tmesipteris  find  their 
affinity  among  the  ancient  Sphenophyllales  is  strengthened  by  the  facts 
in  the  present  paper.  A.  G. 

Pteridophyta  of  Indo-China. — Prince  N.  Bonaparte  {Notes  Pteri- 
dologiqueSj  Paris,  1919,  Fasc.  8, 197  pp.).  The  present  fascicle  contains 
the  first  part  of  a  monograph  of  the  ferns  of  Indo-China,  i.e.  Siam, 
Lagos,  Tonkin,  Cambodia,  Annam  and  Cochin-China,  and  comprises  the 
first  four  families  —  Hyraenophyllaceae,  Gleicheniacese,  Schizaeaceae, 
Cyatheaceai.  Descriptions,  sometimes  original,  are  given  for  each 
family,  genus  and  species  ;  and  keys  are  provided.  The  synonyms  and 
illustrations  of  the  species  are  given,  and  their  geographical  distribution, 
and  critical  remarks  where  necessary.  A.  G. 


Bryophyta. 

Ramification  of  Mosses  :  A  Morphological  Study. — K.  Kavina 
(Hedwigia,  1915,  56,  308-32  ;  see  also  Bot.  Centralbl.,  1918,  137, 
75-6).  The  mode  of  branching  in  mosses  is  monopodial,  in  Sphagna 
dichotomous,  and  in  liverworts  more  often  dichotomous  than  monopodiaL 
These  three  groups  form  three  independent  parallel  types,  which  probably 
have  nothing  but  their  origin  in  common.  The  following  details  are  of 
special  interest : — A  pushing  up  of  the  subtending  leaf  on  to  the 
daughter-axis  in  Calliergon  cuspidatimi  and  Antitrichia  curtipendnla. 
Regular  axillary  branching  is  the  most  usual,  in  which  the  branch  stands 
exactly  in  the  median  line  of  the  leaf-axil  (e.g.  Eurhymhium  muraUy 
species  of  Fhilonoiis,  Hylocomium  loreum).  In  Mnium  no  sort  of 
branch  sheath  is  present.  It  is  represented  only  by  the  knob-like 
swelling  of  the  basal  part  of  the  axillary  branch.  Sometimes  it  is  found 
that  the  lateral  shoot  does  not  appear  to  be  so  exactly  lateral  as  it  should 
be,  but  stands  high  above  the  axis  of  the  subtending  leaf,  either  pre- 
cisely in  the  median  line  or  to  the  right  or  left  of  it  ;  in  both  cases 
apparently  breaking  the  general  rule  of  monopodial  branching.  The 
explanation  is  that  in  the  first  case  the  lateral  shoot  grows  together  with 
the  main  axis  for  a  certain  distance,  or  there  occurs  a  displacement  of 
the  lateral  shoot  high  above  the  leaf-axil  {Rhytidiadelphus  triguetrus^ 
Callisryon  stramineum  ;  in  the  second  case  a  torsion  of  the  main  stem 
takes  place  {Hedivigia,  Climaciiim),  or  plagiotropism  has  been  the  influ- 
ence {Eurhynchium  sp.  LesJcea  sp.  Neckera  sp.)  Adventive  shoots  have 
no  orientation  to  the  leaves.  The  subject  of  orientation  is  discussed  : 
dorsiventral,  opposite,  and  transverse.  But  it  is  so  variable  that  it  is 
impossible  to  set  up  any  types.  The  "  first  leaves  "  are,  according  to 
the  author,  of  a  trichome-like  nature  ;  only  in  Mnium  divided  normal 
leaves  occur  in  the  form  of  bristles.  The  small  scale-like  or  bristle - 
like  leaves  occurring  between  the  normal  leaves  in  the  middle  of  the 
lateral  shoots  or  on  the  adjacent  stems  in  Mnium,  Hypnum,  Climacium, 
Scleropodium,  etc.,  are  trichomes,  and  only  requisite  for  their  biological 
function — namely,  the  enveloping  of  the  young  vegetative  growing  point. 

E.  S.  Gepp. 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  77 

Studies  on  the  Biology  and  Geography  of  Mosses.  I.  Biology 
and  Ecology  of  Mosses. — C.  Grebe  {Hedwigia,  1917,  59,  1-205  ;  see 
also  Bot.  Oentralbl,  1918,  137,  87).  This  may  be  called  a  band- 
book  of  practical  biology  and  ecology  of  mosses,  and  is  the  result  of 
very  numerous  observations  made  by  the  author  during  long  decades. 
He  has  studied  the  mosses  of  all  the  mountainous  districts  of  Central 
Germany  ifi  situ,  as  has  never  been  done  previously  ;  and  while  he  con- 
tents himself  principally  with  recording  his  actual  observations,  he 
follows  the  teleological  methods  of  thought  when  he  seeks  to  explain 
them.  The  work  contains  the  following  sections  : — (1)  Humicolous, 
Humus-fed,  and  Saprophyte.  (2)  The  biology  of  water-  and  swamp- 
mosses.  (3)  The  xerophytic  structure  of  the  xerophilous  mosses.  (4)  Be- 
haviour of  mosses  towards  light  and  shade.  (5)  Moss  vegetation  of 
woodland  formations.  (6)  Calcicolous  mosses  and  their  behaviour  to  the 
substratum.  (7)  Fresh  mineral  soil  and  its  influences.  (8)  Biology  of 
the  inflorescence.  (9)  The  peristome  of  mosses  and  its  functions. 
(10)  Appropriateness  in  organic  structure  in  mosses.  Each  section  is 
further  sub-divided,  and  the  subjects  discussed  from  all  sides.     E.  S.  Q. 

Bryological  Novelties. — C.  Warnstorf  {Bryol.  Zeitschr.,  1916,  1, 
33  ;  see  also  Bot.  Oentralbl,  1918,  137,  108).  The  result  of  a 
series  of  small  investigations  of  the  structure  and  systematic  position  of 
certain  Bryophytes.  Fhuroclada  albescens  is  compared  with  P.  islandica, 
and  the  latter  is  proved  to  be  merely  a  delicate  habitat-form,  having 
small,  widely  separated  leaves.  In  Mnium  affine  an  abnormal  leaf  for- 
mation, with  very  strong,  forked  midrib,  is  described.  Vegetative 
propagation  has  been  observed  in  Sphagnum  molluscum  ;  a  lateral  shoot 
having  stem  characters  with  leafy  branchlets  was  found  in  the  place  of 
the  usual  branch  tuft ;  and  on  normal  stems  there  occur  single  long 
subcomal  shoots ;  also  there  occurred,  on  an  otherwise  normal  stem  of 
^S'.  amblyphyllum,  a  stem-like  lateral  shoot  arising  from  the  base  of 
a  branch-tuft,  and  bearing  a  small  terminal  head  and  slightly  developed 
leaves.  Fontinalis  antipyretica  var.  mollissima  is  described,  and  support 
is  given  to  the  view  that  F.  arvernica  is  a  variety  of  F.  antipyretica ;  as 
also  F.  fasciculata  Lindb.  var.  danubica  Cardot,  from  the  bank  of  the 
Danube  at  Neustadt,  and  F.  Lachenaudi  Cardot.  On  the  other  hand, 
var.  laxa  of  F.  antipyretica  is  regarded  as  worthy  of  specific  rank.  A 
hermaphrodite  flower  is  recorded  for  Pohlia  nutans,  hitherto  known  as 
protogynous.  Finally,  nematode  colonies  are  described  in  Grimmia 
montana.  E.  S.  G. 

Scapania  paludicola  Loeske  at  C.  Mull. :  Contributions  to  the 
Question  of  Parallel  Forms  in  Mosses. — L.  Loeske  {Ungar.  bot. 
Blatter,  1915,  298-302  ;  see  also  Bot.  Centralbl,  1918,  137, 
135,  136).  A  detailed  discussion  of  the  two  species  of  Scapania, 
which  are  united  under  S,  paludosa  C.  Mull. — namely,  S.  imdulata- 
paludosa  and  S.  irrigua-paludosa.  Both  are  alike  in  inhabiting  swamps 
at  high  altitude,  in  their  lax  growth,  their  pale  green  colour,  and  in 
having  a  short,  remarkable  arcuately  curved  commissure.  The  different 
species   are   distinguished   without   difficulty  by  their  areolation.     In 


78  SUMMARY  OF   CURRENT  RESEARCHES  RELATIKG  TO 

S.  undidata,  the  leaf-cells  are  either  thin-walled  or  of  even  thickness 
throughout ;  in  S.  irrigua  the  cells  have  triangular  thickenings.  These 
differences  in  areolation  are  hereditary  (phjletic).  S.  paludosa  C.  M.  is 
here  regarded  as  an  extreme  and  striking  swamp- form  of  the  very 
variable  S.  undulata,  forming  perhaps  the  opposite  pole  in  S.  dentata, 
which  is  the  other  extreme  of  S.  undulata^  S.  dentata  occurring  in  the 
Upper  Harz  mountains,  and  being  regarded  as  a  xeromorphosis  of 
S.  undulata.  In  herbaria  the  two  species  distinguished  above  lie  side 
by  side  under  S.  paludosa.  Since  the  name  was  created  for  the  former 
of  the  two,  the  name  of  S.  paludicola  Loeske  et  C.  Miill.  is  created  for 
the  latter.  A  considerable  portion  of  the  northern  Martinellia  paludosa 
belongs  to  S.  paludicola.  Two  conditions  help  to  bring  about  such 
parallels  :  the  respective  original  species  must  be  closely  allied  (as  is 
the  case  here),  and  demand  similar  conditions.  But  they  must  be  also 
very  variable  and  extremely  open  to  influence  by  the  action  of  water. 
In  the  case  of  Fhilonotis  the  action  of  water  brings  about  variation 
along  similar  lines  to  so  great  an  extent  that  it  is  sometimes  only 
possible  to  guess  the  species,  not  to  determine  it  with  certainty. 

E.  S.  G. 

Organic  Balancing  between  the  Pedicel  of  the  Female  Recep- 
tacle and  that  of  the  Sporogonium  in  Lunularia  vulgaris. — 
P.  Lesage  {Gomptes  Rendus  Acad.  Sci.  Paris,  160,  1915,  679- 
881).  The  author  obstructed  the  upward  growth  of  the  pedicels  of  the 
female  receptacles  in  the  species  by  covering  them  down  with  bricks ; 
and  found  the  pedicels  of  the  sporogonia  to  become  longer  than  normal. 
He  concludes  that  in  this  a  compensation  may  be  discerned.       A.  G. 

Liverworts  of  Germany,  Austria  and  Switzerland,  with  Con- 
sideration of  the  other  European  Countries. — K.  Mjjller  (Raben- 
horsCs  Kryptog amen- flora,  Leipzig  :  E.  Kummer,  1916,  6,  Lief.  28, 
849-947).  The  final  part  of  this  monograph.  A  chapter  is  devoted 
to  Vertical  Distribution  of  the  Liverworts,  and  another  to  their  Ecology. 
The  dependence  of  Liverworts  on  climatic  factors  (warmth,  light, 
moisture)  and  on  biotic  and  edaphic  factors  is  discussed.  A  complete 
index  of  families,  genera,  species,  varieties  and  forms,  with  all  synonyms, 
completes  this  work,  the  preparation  for  which  has  taken  eleven  years. 

E.  S.  G. 

Thallophyta. 

AlgSB. 

Thalassiophyta  and  the  Subaerial  Transmigration. — A.  H.  Church 
(Botanical  Memoirs,  Xo.  3,  Oxford  University  Press,  1919,  95  pp.)  An 
essay  on  the  origin  of  the  Land  Flora.  The  author  shows  that  the 
latter  must  Lave  ))een  derived  from  the  marine  alg^e,  and  indeed  from 
green  algie  of  the  highest  type  of  development.  Life  originated  in  the 
sea  from  the  ionized  sea-water,  yielding  unicellular  plankton  organisms, 
autotrophic  chiefly,  but  associated  with  their  animal  derivatives.  To 
this  plankton  phase  was  added  after  vast  ages  a  benthic  phase,  when 
the  sea-bottom,  slowly  elevated  to  within  100  fathoms  from  the  surface, 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  .        79 

afforded  a  safe  anchorage  to  algae  (and  animals),  which  then  began  to 
develop  a  multicellular  structure  and  to  elaborate  modes  of  reproduction 
and  of  spore-dispersal  necessitated  by  their  sedentary  existence.  After 
further  ages  the  sea-bottom  gradually  came  right  to  the  surface,  and 
the  exposed  algas  and  animals  had  to  adapt  themselves  to  aerial  condi- 
tions or  to  perish.  Several  of  the  best  fitted  successfully  passed  through 
the  ordeal,  but  in  the  struggle  became  so  drastically  altered,  in  shape, 
structure,  physiology  and  modes  of  reproduction  that  the  ancestry  of 
the  distinct  phyla  of  the  Bryophyta,  Lycopods,  Equisetaceae,  Ferns, 
Gymnosperms,  x\ngiosperms,  etc.,  is  now  untraceable,  though  in  several 
of  them  an  ancient  and  primitive  character  survives  in  the  structure  of 
the  respective  antherozoids,  and  affords  powerful  evidence  as  to  ancestral 
affinities.  Another  interesting  group  are  the  Fungi.  These  date  from 
the  same  period  of  land-emergence,  and  had  a  markedly  polyphyletic 
origin  (e.g.  Phycomycetes,  Ascomycetes,  Basidiomycetes,  Uredineae)  ; 
they  too  came  through  great  tribulation  in  adapting  themselves  to  a 
saprophytic  or  parasitic  life  and  in  elaborating  resting-spores,  air-borne 
spores,  etc.,  which  enabled  them  to  withstand  drought  and  secure  a 
wide  dispersal.  No  trace  of  the  highly  organized  green  algae  of  the 
transmigration  is  to  be  found  in  geological  strata.  They  became  land- 
plants,  or  they  perished.  But  the  brown  and  the  red  algae  were  not 
fitted  for  the  transmigration,  being  inadequately  developed  in  reproduc- 
tive mechanism  (brown  algae)  or  in  vegetative  structure  (red  algae). 

The  memoir  is  of  the  highest  importance  in  connexion  with  the 
study  of  the  fundamental  facts  of  botany,  and  is  replete  with  details, 
deductions  and  arguments  which  can  only  be  studied  with  advantage  in 
the  original  text.  A.  G. 

Terminology  of  Alternation  of  Generations  in  Plants. — D.  Renxer 
{Biol.  CentralU.,  1916,  36,  337-74  ;  see  also^o^.  Centralhl,  1918,  137, 
97-8).  An  attempt  to  bring  uniformity  into  the  terminology  of  alter- 
nation of  generations.  The  author  disapproves  of  the  term  in  the 
Hofmeister  sense,  and  seeks  to  prove  among  the  most  varied  famihes  of 
the  plant  world  that  where  alternation  of  phases  is  present,  alternation 
of  generations  does  not  necessarily  exist  also.  "  Alternation  of  genera- 
tions" he  acknowledges  exclusively  in  tliose  cases  "where,  over  and 
above  the  zygote,  at  least  a  second  obligate  germ-cell,  a  true  spore,  is 
present,  which  does  not  originate  directly  at  the  germination  of  the 
zygote."  Under  "  generation "  he  understands  a  portion  of  the 
development  which  is  intercalated  between  two  different  obhgate  germ- 
cells,  and  to  a  certain  extent  exhibits  vegetative  growth.  Alternation 
of  phases  would  then  be  an  alternation  of  stages  having  haploid  and 
diploid  nuclei  and  need  not  necessarily  coincide  with  alternation  of 
generations.  Thus  Spirogyra,  which  completes  its  reduction-division  on 
the  germination  of  the  zygote,  lacks,  according  to  the  author,  an  alter- 
nation of  generations.  The  author's  view  is  that  the  gametophyte 
begins  with  the  gonospore,  or  in  some  cases  with  the  gonotokont  and 
ends  with  the  gametes,  while  the  sporophyte  represents  a  generation 
which  produces  spores.  The  gametophyte  is  always  haploid,  while  the 
newly  defined  sporophyte  is  as  a  rule  diploid  ;  but  in  those  cases  where 


80  SUMMARY  OF   CURRENT   RESEARCHES   RELATING  TO 

it  arises  from  a  zyc^ote  which  may  also  be  haploid  (e.g.  Scinaia,  in 
which  reduction-division  is  completed  directly  on  germination)  the 
gonimoblast  is  haploid.  Different  cases  are  to  be  distinguished  according 
to  whether  the  diploid  sporophyte  produces  gonospores  (mostly  similar 
to  tetraspores)  or  tokospores  (a  new  and  degenerate  expression  coined 
by  the  author  for  gonotokont-spores),  or  diplospores.  These  views  are 
also  applied  to  the  various  families  of  plants.  E.  S.  Gepp. 

Periodicity  and  Geographical  Distribution  of  the  Algae  of  Baden. 

A.  Rabanus  (Ber.  Naturforsch.  Freiburg  i.  Br.,  1915,  21,  1-158  ; 

see  also  Bot  Centralbl.,  1917,  135,  389-91).  The  work  has  a 
double  aim  :  to  give  an  insight  into  the  periodicity  of  the  algae  during 
the  course  of  a  year  in  various  localities,  and  to  give  a  geographical 
account  of  the  alg»  of  Baden.  A  resume  of  previous  work  on  the 
subject  is  followed  by  an  account  of  the  algal  vegetation  of  the  Black 
Forest,  the  plain  of  the  Rhine  and  the  Kaiserstuhl.  The  difference  in 
the  flora  of  the  three  regions  arises  from  the  differences  of  temperature 
and  the  varying  water-level.  After  describing  the  annual  cycle  of 
algee  in  the  various  habitats,  the  author  discusses  their  periodicity  in 
different  localities— the  ditches  by  the  roadside  in  the  plains,  the 
mountainous  districts,  rivers,  ponds,  marshes,  etc.  Most  of  the  species 
are  too  much  (Ulothrix)  or  too  little  {Cylindrocystis)  dependent  on 
outside  factors  to  allow  of  an  inherited  periodicity  in  their  life-cycle. 
Only  Spirogyra  flourishes  from  autumn  to  spring,  or  only  in  the  spring, 
and  mostly  in  puddles  and  ditches  which  are  filled  with  water  only  in 
the  rainy  season.  The  explanation  of  "  water  bloom "  is  still  far  to 
seek.  Certain  algae  retained  life  through  a  prolonged  period  of  freezing, 
and  this  is  dependent  not  only  on  the  degree  of  the  frost,  but  on  the 
^'  mood  "  of  the  algal  cell.  The  resistance  to  heat  varied  greatly,  the 
most  sensitive  being  Ulothrix,  in  lesser  degree  Stigeoclonium  and 
Conferva  ;  Vaucheria  can  bear  fairly  high  temperatures.  Many  other 
interesting  peculiarities  are  noted  for  various  species.  The  geographical 
distribution  is  fully  treated.  A  list  of  species  recorded  for  Baden  is 
given,  and  certain  aberrant  forms  of  Desmidiaceae  are  described,  but  not 
named.     Various  results  are  shown  in  tabular  form.  E.  S.  G. 

Notes  on  Some  Intermediate  Forms  of  the  Genera  Navicula 
and  Cymhella. — Sir  Nicholas  Yermoloff  {Journ.  Quekett  Microsc. 
Club,  191H,  13,  18  pp.,  3  pis.).  The  author  shows  by  a  process  of 
*'  synthetic  integration  "  that  the  fossil  diatom  Navicula  mo}wiouthiana 
may  be  considered  as  an  ancestral  form  of  a  whole  series  of  species  of 
VymbeUa,  which  he  describes.  The  series  ends  in  the  very  small  C. 
microcephala,  the  intermediate  forms  passing  almost  imperceptibly  from 
one  to  the  other  along  the  ladder.  It  is  presumed  that  the  parental 
fossil  form  N.  monmouthiana  appeared  about  the  end  of  the  Pliocene 
period  in  the  State  of  Maine,  and  the  descendant  species  have  been 
evolved  during  the  sul)sequent  Quaternary  period  up  to  the  present 
day.  As  regards  the  term  "species,"  the  author  gives  a  definition 
which  was  advocated  in  Russian  scientific  circles  before  the  war  :  "  A 
.species  in  Nature  corresponds  to  what  in  the  Differential  Calculus  is 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  81 

meant  bj  a  derived  function  ;  it  is  a  certain  type-limit,  to  which' tend, 
without  even  sometimes  quite  identically  attaining  it,  certain  varying 
intermediate  forms."  He  enumerates  seven  ^distinguishing  features  in 
the  systematic  classification  of  diatoms,  and  advocates  a  close  comparison 
of  fossil  »and  living  forms  for  determining  the  lines  of  genealogical 
descent.  Certain  observations  are  made  on  the  structure  of  the  genus 
Cymlella^  and  of  the  various  intermediate  forms  lying  between  N. 
momnouthiana  and  C.  microcephala.  The  tendency  in  some  of  the 
intermediate  forms  to  triundulate  margins  may  perhaps  be  regarded  as 
a  transitional  rather  than  as  a  specific  character.  Descriptions  of  the 
various  recognized  species  are  given,  and  the  various  changes  along  the 
road  of  transition  are  pointed  out.  E.  S.  G. 

* 
Amphora  inflexa,  a  Rare  British  Diatom. — G.  West  {Journ. 
Quek.  Micr.  Club,  1919,  14,  6  pp.  1  pi.).  An  authoritative  reply  to  the 
various  doubts  and  queries  concerning  the  identity  of  a  species  of  diatom 
collected  by  Capt.  D.  Griffiths  in  Carmarthen  Bay  in  1915.  Amphora 
inflexa  has  been  published  under  various  synonyms.  It  has  been 
recorded  from  Calvados  and  Biarritz  in  France,  and  from  the  Adriatic ; 
in  England  from  Ilfracombe  and  the  Tay,  previous  to  Capt.  Griffiths' 
find  in  Wales.  In  the  present  paper  the  differences  between  this  species 
and  the  various  genera  in  which  it  has  been  placed  are  pointed  out,  and 
the  species  itself  is  for  the  first  time  adequately  described  and  figured. 
It  is  a  free  marine  diatom,  living  amongst  the  muddy  sediment  in  rock 
pools  within  tidal  influence.  Navicula  scopulorum  Breb.,  N.  {Schizo- 
nema)  ramosissima  Ag.  and  Toxonidia  insignis  Donk.  were  found  in  the 
same  gathering  as  Amphora  inflexa  (Breb.)  H.  L.  Smith.         E.  S.  G. 

Action  of  Sulphate  of  Copper  on  Plankton. — A.  Betant  (C.  R. 
Soc.  Phys.  d'Hist  Nat.  Geneve,  1918,  35,  86-91).  A  successful 
attempt  to  eliminiate  plankton  from  the  drinking  water  taken  from  the 
Lake  of  Geneva  by  the  action  of  sulphate  of  copper.  The  annual 
report  of  the  Water  Board  shows  a  fairly  even  quantitative  distribution 
throughout  the  years,  with  the  exception  of  May  to  July,  when  a  very 
variable  increase  may  take  place.  In  1914  and  1917  it  did  not  exceed 
380  and  500  mm.^  per  100  litres  of  water,  while  in  1915  it  reached 
5273  mm.3,  and  in  1918,  3100  mm.^  per  100  litres.  During  the  rest 
of  the  year  the  proportion  is  fairly  constant  at  100  mm.^.  Among  the 
diatoms  the  characteristic  species  are  :  Fragilaria  crotonensis,  Cyclotella, 
Synedra,  and  others  less  frequently;  among  green  algae,  Spirogyra, 
Sphaerocystis,  etc.  The  method  of  killing  the  organisms  with  sulphate 
of  copper  and  letting  them  sink  down  and  form  a  sediment  is  fully 
described,  and  was  attended  with  perfect  success.  While  the  natural 
water  before  treatment  contained  150  mm.^  of  plankton,  it  showed  only 
7  mm.^  per  100  litres  afterwards.  E.  S.  G. 

Synopsis  of  the  Biological  Examination  of  Water. — J.  Wilhelmi 
(Siizungsber.  Ges.  naturf.  Freunde  Berlin,  1916,  9,  297-306  ;  see  also 
Bot.  Centralbl.,  1917,  135,  191-92.)  A  criticism  of  the  Kolkwitz- 
Marsson  scheme  for  the  grouping  of  the  biological  contents  of  water, 

G 


82  SUMMARY  OF  CUERENT   RESEARCHES   RELATING  TO 

and  the  presentation  of  a  new  scheme.  The  author  regards  as  neces- 
sary the  determination,  quantitatively  and  qualitatively,  of  the  organic 
and  inorganic  floating  matter,  Plankton  and  Tripton.  He  dis- 
tinguishes three  groups  :  I.  Euplankton  (Kolkwitz)  and  Eutripton. 
In  size  the  two  are  analogous.  Both  are  found  in  the  clearest  water  as 
Nannoplankton  and  Nannotripton.  II.  Pseudoplankton  and  Pseudo- 
tripton.  Under  the  former  he  understands  all  organisms  which  may 
live  in  water  but  do  not  actually  find  therein  the  true  conditions  essen- 
tial to  life  ;  such  as  organisms  torn  from  the  bank  or  the  bottom  and 
able  to  exist  for  a  certain  time,  or  those  attached  to  Euplankton 
individuals,  or  those  dependent  on  sewage  (Saproplankton).  III.  Hemi- 
plankton  and  Periplankton.  All  organisms  which  pass  a  certain  stage 
of  their  development  as  a  plankton  unit.  The  auto-purification  of 
sewage  is  more  difficult  to  bring  about  in  the  sea  than  in  fresh-water. 
Impurities  of  harbours  and  of  bays  in  tideless  seas  cause  an  enormous 
development  of  Ulva  Lactuca  through  a  rich  supply  of  nitrogen,  and  it 
fouls  the  water  and  spreads  disease.  E.  S.  G. 

Fresh-water  Biological  Institute  at  Aneboda,  and  the  Scientific 
Investigations  carried  out  there. — E.  Naumann  {Skrift.  Sodra  Sver. 
Fisherifor.  Lund,  1916,  No.  13,  17  pp. ;  see  also  Bot.  Centralbl.,  1918, 
137,  134-5).  In  connexion  with  the  Swedish  Fishery  Association  a 
laboratory  was  opened  at  Aneboda  in  1907,  for  the  investigation  of 
problems  of  fresh-water  biology  and  fishery.  The  influence  of  the  food 
supply  on  planktological  conditions  of  the  water  was  examined.  It  was 
shown  to  produce  a  more  or  less  marked  change  of  the  chemical  medium, 
and  in  a  mildly  saprobihzing  direction,  which  caused  an  increase  in 
certain  plankton  forms,  often  in  extreme  degree.  These  culture  for- 
mations have  a  two-fold  importance.  They  bring  about  a  normal 
biochemical  automatic  regulation  of  the  water — a  sort  of  automatic 
protection  against  otherwise  harmful  remains  of  nutrition ;  and  the  in- 
creased production  of  phyto-plankton  provides  a  larger  supply  of  food 
for  the  pelagic  and  benthic  fauna.  E.  S.  G. 

Simple  arrangement  for  obtaining  Biological  Samples  of  Water 
from  the  deeper  Water  Strata. — E.  Naumann  {Skrift.  Sodra  Sver. 
Fiskerifor.  Lund,  1916,  No.  13,  8  pp. ;  see  also  Bot.  Centralbl.,  1918, 
137,  135).  A  description  of  a  new  type  of  dipping-bottle  used  by 
the  author  for  some  years  for  biological  purposes.  The  appearance  of 
the  apparatus  is  described  and  figured.  It  is  specially  adapted  for  the 
•collection  of  quantitative  samples  of  water  from  various  depths. 

E.  S.  G. 

Lietzensee,  near  Berlin  :  An  example  of  Applied  Hydrobiology. — 
E.  Naumann  {Skrift.  Sodra  Sver.  Fiskerifor.  Lund,  1916,  No.  13, 
34  pp.  ;  see  also  Bot.  Centralbl.,  1918,  137,  135).  An  exhaustive 
report  on  the  investigations  of  R.  Kolkwitz  on  the  plankton  production 
of  the  Lietzensee,  together  with  a  discussion  of  the  measures  undertaken 
by  him  for  the  reduction  of  the  surplus  production.  An  original 
drawing  is  given  of  Oscillatoria  Agardhii  Gom.  E.  S.  G. 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  83 

Marine  Algse  of  the  Pacific  Coast  of  North  America.  Part  I. : 
Myxophyceae. — W.  A.  Setchell  and  N.  L.  Gardner  {University  of 
California  Fuhlications  :  Botany,  1919,  8,  1-138,  8  pL).  Thia  is  the 
first  part  of  a  complete  account  of  the  seaweeds  of  the  Pacific  Coast ; 
and  the  three  remaining  parts  are  stated  to  be  in  advanced  preparation. 
The  present  one  contains  thirty  genera  of  Blue-green  Algse,  under 
which  are  placed  ninety-sii  species  and  some  varieties  and  forms. 
Descriptions  of  the  orders,  families,  genera  and  species  are  given,  and 
are  amplified  with  critical  notes.  The  addition  of  keys  facilitates  the 
naming  of  specimens.  A  marine  flora  of  this  region  has  long  been 
needed.  A.  G-. 

Preliminary  Catalogue  of  the  Pelagic  Flora  of  the  Bay  of 
Quarto  dei  Mille,  near  Genoa. — A.  Forti  {Nuova  Notarisia,  1920,  31, 
65-72).  Merely  a  preliminary  list  of  235  species  collected  in  the  Bay 
-during  the  whole  year  of  1915  by  Eaffuele  Issel,  to  be  followed  by  full 
details  and  descriptions  later ;  a  study  carried  out  at  the  Marine 
Laboratory  of  Quarto  dei  Mille.  The  recorded  species  include  1  Cysto- 
flagellate  {Noctiluca  miliaris  Sur.),  123  Peridiniales,  101  Bacillariales, 
•3  Silicoflagellata,  GoccoUthophora  leptopora  Lehm.,  and  6  Chlorophyceae. 

E.  S.  G. 

Parasitic  Floridae :  I. — W.  A.  Setchell  {Univ.  California  PuU. 
Bot,  1914,  6,  1-34,  6  pis.).  A  monograph  of  the  genus  Janczewskia. 
After  a  short  introduction  the  author  gives  a  history  of  the  genus, 
followed  by  a  short  account  of  his  materials  and  the  host  plants.  The 
morphology  of  J.  verrucdeformis  and  /.  tasmanica  is  then  discussed  as 
representing  the  extremes  of  structure  thus  far  discovered  in  the  genus. 
All  three  sorts  of  reproductive  bodies  usually  found  among  Floridege 
are  known  in  this  genus.  Under  taxonomy  a  critical  description  is 
given  of  each  of  the  six  species,  of  which  four  are  new.  The  host- 
plant  of  one  of  them,  J.  Solmsii^  is  the  species  commonly  known  as 
Laurencia  virgata,  but  has  proved  to  be  (either  wholly  or  in  part) 
Ohondriopsis  subopposita  J.  Ag.,  a  true  species  of  Laurencia.  Janczewskia 
is  divided  into  two  groups  which  differ  in  certain  morphological  details. 
The  genus  is  widely  distributed  in  temperate  seas  from  the  Mediterranean 
to  the  Cape  of  Good  Hope.  Since  their  hosts,  Laurenciese  and 
Ghondrieae  are  also  abundant  in  the  warmer  temperate  and  tropical 
waters,  the  parasite  may  reasonably  be  supposed  to  have  a  wider  distri- 
bution than  is  at  present  known,  since  they  both  belong  to  the  same 
family.     The  paper  is  well  illustrated.  E.  S.  G. 

Marine  Algae  of  the  Danish  West  Indies. — F.  Borgesen  {Dansk 
Bot.  Arkiv.,  1919,  3,  305-68).  A  further  continuation  of  this  work. 
The  present  part  completes  Rhodomeleae,  including  Delesseriaceae  and 
Bonnemaisoniaceae,  and  begins  the  treatment  of  Gigartinales,  family 
Gigartinaceae.  Each  species  is  fully  discussed  and  nearly  all  are  figured 
in  habit  and  structure,  as  in  previous  parts  of  the  work.  The  novelties 
described  are  Cottoniella  arcuata  g.  et  sp.  n.,  Dasya  caraibica,  and  a  var. 
laxa  for  Heterosiphonia  Wurdemanni  Falkenb.  E.  S.  G. 

G  2 


84  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 

Additions  to  "  Oceanic  Algology." — A.  Mazza  {Nuova  Notarisia^ 
1920,  31,  1-64).  Additional  species  of  genera  and  further  notes  on 
species  already  treated  in  the  main  body  of  this  work.  In  the  present 
contribution  the  note  on  Porphyroglossum  Zollingeri  Kiitz.  is  completed^ 
and  is  followed  by  a  discussion  of  Acanthopeltis  japoiiica  Okam.,  Hennedya 
crispa  Harv.,  Iridaea,  Besa  papiUseformis  Setchell,  and  a  number  of 
species  and  forms  of  Gigartina.  The  notes  on  structure,  nomenclature,, 
etc.,  are  full  of  detail.  E.  S.  G. 

Tertiary  Calcareous  Algae  from  the  Islands  of  St.  Bartholomew^ 
Antigua  and  Anguilla. — M.  A.  Howe  {Carnegie  Inst.  Washington^ 
Publ.  291,  1919,  9-19).  Descriptions  and  illustrations  of  the  fossil 
calcareous  algge  collected  in  February  and  March  1914  by  Dr.  T.  AV. 
Yaughan,  in  the  Eocene  limestone  of  St.  Bartholomew,  the  middle 
Oligocene  formation  of  Antigua,  and  the  upper  Oligocene  of  Anguilla. 
The  new  species  are  described  in  detail  and  compared  with  already 
known  species.  They  belong  to  the  genera  Archseolithothamiiiwn^ 
Lithothamniiim,  Lithophyllum,  and  Lithoporella.  E.  S.  G. 

Melobesieae  of  the  Danish  Antilles  Collected  by  Dr.  F.  Boergesen. 
— ^Madame  Paul  Lemoine  {Bidl.  Mus.  d'Hist.  Nat.,  1917,  133-6). 
Notes  on  the  geographical  distribution  of  the  Melobesieae  founded  on 
collections  made  by  Dr.  Boergesen  and  those  in  the  Museum  of  Natural 
History  in  Paris.  The  calcareous  algag  of  the  Danish  Antilles  is  limited 
to  four  genera,  Liihothamnium  (4  sp.),  Lithophyllum  (9  sp.),  PoroUthon 
(3  sp.),  and  31elobesia  (4  sp.),  and  nearly  all  are  crustaceous  forms. 
Conditions  are  apparently  unfavourable  for  branched  forms.  The  dis- 
tribution throughout  the  Antilles  is  fairly  uniform,  and  a  certain 
number  of  species^ occur  also  in  Florida,  the  Bahamas  and  Bermuda. 
There  appears  to  be  no  analogy  between  the  species  north  and  south  of 
the  equator,  two  or  three  only  being  common  to  the  Antilles  and 
Brazil.  Except  the  ubiquitous  Melobesia  farinosa  there  is  no  species  in 
common  between  the  Antilles  and  the  Atlantic  Coasts  of  Europe,  though 
two  of  the  former  have  been  recorded  from  Cape  de  Verde  and  in  the 
Gulf  of  Guinea.  Certain  Antilles  species  show  close  affinity  with  certain 
tropical  Pacific  species  from  Borneo,  Sumatra,  Caroline  Islands,  Samoa, 
Funafuti,  etc.  Also  some  Antilles  species  show  remarkable  analogy 
with  Mediterranean  and  E.  Atlantic  species,  both  in  external  characters 
and  in  the  reproductive  organs  ;  yet  in  anatomical  structure  they  prove 
to  be  far  asunder.  Similar  zoological  analogies  exist,  and  have  given 
rise  to  the  hypothetical  continent  of  Atlantis.  E.  S.  G. 

Corallinaceae  found  in  a  Limestone  in  course  of  Formation  in  the 
Indian  Ocean.— Madame  Paul  Lemoine  {Bidl.  Mus.  d'Hist.  Nat.^ 
1917,  No.  2,  130-2).  The  calcareous  algae  in  question  were  found  in 
a  specimen  in  a  miueralogical  collection  from  the  island  of  Mayotte  in 
the  Comoro  Archipelago.  A  deposit  of  limestone  is  in  actual  course  of 
formation  at  the  northern  end  of  the  islet  Pamanzi,  by  the  accumulation 
of  debris,  particularly  shells,  united  in  a  cement  of  volcanic  debris  and 
small  fragments  of  calcareous   algae.      Among  these   the   author  has 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,  ETC.  85 

recognized  five  different  species,  one  Lithothamnium,  three  Lithophyllum 
and  one  Amphiroa.  Three  of  these  were  determined  specifically,  and 
the  remaining  two  are  probably  new,  but  too  fragmentary  to  allow  of 
sufficient  description  to  establish  new  species.  Notes  are  given  on  each 
of  the  five  species,  with  such  distinguishing  characters  as  can  be 
discerned.  This  investigation  proves  that  calcareous  algge  continue  to 
this  day,  in  the  constitution  of  marine  deposits,  the  more  or  less 
preponderant  role  that  they  have  played  in  all  geological  epochs  since 
Silurian  times.  This  is  the  first  record  of  calcareous  algee  from  the 
Comoro  Archipelago,  though  the  neighbouring  regions,  Seychelles, 
Amirante,  Saya  de  Malha  and  Mauritius,  are  comparatively  well  known 
Irom  that  point  of  view.  E.  S.  G. 

Note  on  an  Algal  Limestone  from  Angola.— Mrs.  M.  F.  Romanes 

'{Trans.  Roy.  Soc.  Edinb.,  1916,  51,  581-4,  1  pi.).  A  description  of 
Tock-specimens  from  the  Albian  beds  near  Lobito  Bay  in  the  province 
of  Benguella,  Angola,  collected  by  J.  W.  Gregory.  Two  new  calcareous 
algse  are  figured — Girvanella  minima  and  Lithothamnion  angolense. 

A.  G. 

New  Species  of  Fucus,  F.  dichotomus  Sauv. — C.  Sauvageau 
iC.  R.  Acad.  Sci.  Paris,  1915,  160,  557-9).  A  description  of  this^ 
new  species  of  Fucus,  which  has  been  found  on  the  "  brandes  "  border- 
ing certain  oyster  beds,  now  covered  with  sand  and  abandoned,  in  the 
harbour  of  Arcachon.  F.  dichotomus  grows  only  for  a  few  months,  and 
is  distinguished  from  F.  platycarpus  by  its  flabellate  ramification  in- 
volving the  simultaneity  and  abundance  of  the  receptacles,  and  by  the 
cylindrical  form  of  the  receptacles.  The  plant  being  fixed,  the  adven- 
titious shoots  do  not  propagate  the  species,  but  preserve  it ;  and  to 
them  is  due  the  extension  of  life  in  certain  individuals  to  one  or  even 
perhaps  two  years.  E.  S.  G. 

Availability  of  the   Nitrogen    in   Pacific   Coast   Kelps. — G.  R. 

■Stewart  {Journ.  Agric.  Research,  Washington,  4,  1915,  21-38). 
The  value  of  dried  and  ground  kelp  as  a  fertilizer  varies  with  the 
species.  The  nitrogen  of  Kereocystis  Luetkeana  is  relatively  very 
available,  while  that  of  Pelagophycus  porra  is  not.  That  of  Macrocystis 
pyrifera  is  slowly  yielded  in  the  soil,  and  more  quickly  when  the  kelp  is 
fresh  or  only  partially  dried.  Removal  of  the  salts  from  the  alga  does 
not  hasten  its  decomposition.  For  easy  grinding  the  Macrocystis  must 
be  dried  crisp,  but  should  not  be  scorched.  The  presence  of  kelp  ia 
unlikely  to  interfere  with  the  ammonification  or  nitrification  going  on 
in  the  soil.  A.  G. 


Fungi. 

Repeated  Zoospore  Emergence  in  Dictyuchus. — William  H. 
Weston  {Bot  Gaz.,  1919,  68,  287-96,  1  pL,  1  fig.).  The  fungus 
described  appeared  in  a  culture  of  moist  sand,  leaves  and  other  debris 
iaken  from  a  shaded  brook  near  Great  Bacrington,  Massachusetts.     It 


86  SUMMARY   OF   CURRENT   RESEARCHES   RELATING  TO 

was  determined  as  Dictyuchus  from  the  retention  of  spores  in  the 
sporangium  while  they  germinated,  with  the  liberation  of  zoospores- 
These  zoospores  were  observed  to  come  to  rest  and  encyst.  After  a 
time  some  of  these  encysted  spores  germinate  by  hyphse.  Many  of 
them,  however,  emit  zoospores  which  are  biciliate,  and  thus  exactly 
similar  to  those  formed  in  the  sporangium.  The  writer  is  of  opinion 
that  this  secondary  zoospore  formation  will  be  found  general  in  Dicty- 
uchus. No  sexual  organs  were  formed,  and  it  was  thus  found  impossible 
to  determine  the  species.  A.  Lorrain  Smith. 

Study  of  Synchytrium.— W.  Rytz  {Beih.  Bot.  Oentralbl,  1917,  34,. 
343-72,  3  pis.  ;  see  also  Ann.  Mycol..,  1917,  15,  289).  Synchytrium 
Taraxaci  is  parasitic  in  the  epidermis  of  Taraxacum  officinale.  The- 
zoospores  penetrate  directly  from  the  outside  into  the  host-cell,  the 
latter  enlarges,  and  in  due  time  division  of  the  parasitic  nuclei  begins 
up  to  a  large  number.     Division  is  always  mitotic.  A.  L.  S. 

Specialization  of  Peronospora  on  some  Scrophulariacege. — Ernst 
Gaumann  {Ann.  Mycol,  1918, 16, 189-99, 4  figs,  and  diagrams).  There 
is  considerable  biological  specialization  among  Peronosporese,  and  there- 
is  also  considerable  difference  in  spore  sizes.  Gaumann  has  taken  up 
the  question  with  regard  to  a  limited  number  of  what  he  terms  collective 
species.     He  describes  seven  new  species.      .  A.  L.  S. 

Study  of  Plasmopara. — Alfred  Wartenweiler  {Ann.  Mycol.^ 
1917,  15,  495-7;  1918,  16,  269-99,  3  pis.,  12  figs.).  The  author 
finds  that  when  a  species  of  Plasmopara  grows  on  different  hosts,, 
there  is  considerable  variation  in  conidia  and  conidiophores.  Thus  for 
Plasmopara  nivea  he  tested  sizes  from  twenty  different  hosts.  He  gives- 
the  number  of  measurements  and  the  average  size  of  spores  on  each ; 
they  vary  from  16  "99  ft  x  16*21 /u.  in  the  first  host  in  even  higher 
measure  to  28 /x  x  21'48/t  on  the  last.  He  made  similar  tests  for 
P.  pygmaea  and  P.  densa,  which  showed  somewhat  equal  variations. 
The  conidiophores  were  also  examined  and  found  to  vary  according  to- 
the  host. 

In  the  second  paper  he  continues  the  study  of  conidia  and  conidio- 
phores. He  also  gives  the  results  of  a  research  on  the  wintering  of 
Plasmopara  nivea.  He  claims  to  have  proved  that  the  mycelium  passes 
the  winter  in  Laserpitium  latifoUum.  He  has  established  this  |in  plants- 
from  many  districts,  but  cannot  say  if  it  is  of  universal  occurrence.  He- 
gives  in  a  summary  at  the  end  a  comparative  account  of  the  various- 
species  examined.  A.  L.  S. 

Classification  of  the  Phacidiales.  —  Fr.  von  Hohnel  {Ber, 
Deutsch.  Bot.  Gesell,  1917,  35,  416-22).  The  Phacidiales  comprise 
discomycetes  without  or  with  a  stroma  and  with  a  carbonaceous  ascoma 
which  opens  in  lobes.  Van  Hohnel  divides  the  order  into  six  families. 
Diagnoses  of  these  and  of  the  genera  are  given.  A.  L.  S. 

Study  of  Hypocreacese. — I.  Weese  {Siiz.-Ber.  Akad.  Wiss.  Wien 
Math.  Nat.  Kl.  Abhl,  1916,  125,  467-575,  3  pis.  15  figs.).     A  critical 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  87 

study  of  various  genera  of  this  family.  The  author  traces  affinity  be- 
tween the  genera  in  the  form  of  the  perithecium  and  only  secondarily 
in  the  septation  of  the  spores.  Illustrations  are  given  of  twenty-two 
species.  A.  L.  S. 

Mycological  Contributions. — T.  Theiszen  (Ami.  Mycol,  1918,  16, 
175-88,  4  figs.).  Notes  are  given  on  genera  of  Pyrenomycetes  such 
as  Lasiohotrys  and  Vestergrenia.  The  author  has  also  examined  material 
from  S.  America  and  from  Asia,  and  pubhshes  a  number  of  new  species, 
with  extended  descriptive  accounts  of  some  that  are  not  new.  A.  L.  S. 

Laboulbeniales. — Roland  Thaxter  (Proc.  Amer.  Acad.  Arts  mid 
Sci.,  1915,  51,  1-51  ;  1915,  52,  1-54  and  649-721  ;  1918,  53,  697, 
749;  1918,  54,  207-32).  In  this  series  of  papers  Thaxter  describes 
many  new  species  from  widely  separated  localities  situated  in  or  near 
the  tropics.  In  the  first  list,  comprising  Indo-Malayan  species,  one_  of 
the  gatherings  provided  evidence  that  the  genus  Ceraiomyces  should" be 
merged  in  Lahoidhenia.  Java  and  Ceylon  furnished  most  of  the 
material.  In  the  second  paper  species  of  Chitonomyces  and  RicTcia  are 
described.  They  were  collected  in  the  Cameroons,  Philippines,  W.  Indies 
and  Central  America.  A  paper  is  devoted  to  American  species — not 
the  United  States — and  includes  as  new  genera  Nycteromyces  and 
Ilytheomyces.  A  record  of  extra-American  species  includes  mostly 
African  or  Malayan  species,  while  the  final  paper  takes  account  only  of 
species  from  Chili  and  New  Zealand.  The  two  countries  are  associated 
because  the  flora  of  Southern  Chili  and  New  Zealand  are  similar  in 
many  respects.  A.  L.  S. 

Synoptic  Tables.— F.  Theiszen  and  H.  Sydow  [Ann.  BIijcol.,  1917, 
15,  389-491,  38  figs.).  The  authors  point  out  that  in  the  twenty 
years  since  the  publication  of  the  "Natur.  Pflanzenfamilien "  there 
have  been  many  changes  in  the  systematic  arrangement  of  various 
groups  of  fungi.  They  deal  here  with  Pyrenomycetes,  and  have  given 
synoptic  tables  of  the  orders  Hemisphaeriales,  Myriangiales  and  Peri- 
sporiales.  Tables  are  given  of  the  families  into  which  these  are  divided, 
then  the  genera  of  each  family  and  a  diagnosis  of  each  genus  with  the 
type  species  and  synonymy.  A  number  of  new  genera  have  been  formed 
or  new  names  substituted  in  the  course  of  the  work.  An  index  of  the 
genera  is  given.  A.  L.  S. 

Sketch  of  Pseudosphseriales.— F.  Theiszen  and  H.  Sydow  {Ann. 
Mycol.,  1918,  16,  1-34,5  figs.).  In  the  Pseudosphaeriace^  the  locuK 
of  a  stroma  enclose  only  one  ascus.  There  are  several  genera  in  the 
family.  A  full  account  is  given  by  the  authors  of  this  and  other 
families.  They  also  give  a  special  synoptic  list  of  Pyrenomycetes 
parasitic  on  the  lichen  thallus.  A.  L.  S. 

Dothideales :  a  Critical  Systematic  Original  Research.— F.  Theiszen 
and  H.  Sydow  {Ann.  Mycol,  1915,  13,  149-746,  6  pis.).  The  authors 
give  an  historical  sketch  of  the  treatment  of  this  group  of  Pyrenornycetes. 
Von  Hohnel  had  published  an  account  of  these  fungi,  but  his  work 


88  SUMMARY   OF  CURRENT   RESEARCHES   RELATING  TO 

remains  unfinished.  Theiszen  and  Sjdow  here  give  special  attention 
to  the  stroma  in  their  research,  and  the  arrangement  chosen  follows  on 
the  lines  of  its  growth  and  mature  form.  They  divide  the  Dothideales 
into  four  famiUes :  (1)  Polystomellace^,  with  three  sub-families — Parmu- 
lineae,  Poljstomelleae  and  Munkielleae ;  (2)  Dothideaceae,  also  with  three 
sub-families  —  Coccoideae,  Leveillelleae  and  Dothidese  ;  (3)  Phylla- 
choraceae,  divided  into  Trabutinese,  Scirrhineae  and  Phyllachorineae  ; 
(4)  Montagnellacea?,  with  two  sub-families — Eu-Montagnelle^e  and 
Eosenscheldieae.  The  last  family  has  a  very  reduced  vegetative  stroma, 
or  a  basal  stroma  only,  or  none.  In  these  famihes  they  recognize  140 
genera  set  out  in  a  systematic  key.  Of  these  some  64  are  new  names.  A 
number  of  well-known  genera  have  been  included  in  others,  as,  for 
instance,  Ploivrightia,  which  gives  way  to  a  previous  name,  Dothidella. 
Each  species  is  fully  described,  and  there  is  a  complete  index.     A.  L.  S. 

Occurrence  of  Bulgaria  platydiscus  in  Canada. — A.  W.  McCallum 
(Mycologia,  1919,  11,  293-5,  1  pL).  This  fungus,  originally  described 
from  Konigsberg  in  Germany,  has  recently  been  found  in  the  valley  of 
the  Lievre  River.  The  plant  was  allowed  to  mature,  and  drawings 
were  made  of  the  peculiar  spiral  form  of  the  exterior  hyphae.  A  full 
description  is  given.  A.  L.  S. 

Contributions  to  the  Systematy  of  the  Ascomycetes. — F.  Theiszen 
{A7in.  MijcoL,  19?6,  14,  401-39,  1  pL).  Theiszen  divides  the 
present  "  contribution "  into  three  divisions.  The  first  deals  with 
Perisporiaceae,  and  notes  are  given  on  a  number  of  genera.  Two  new 
genera  are  added  to  the  family — Stomatogene,  on  which  the  perithecia 
grow  superficially  on  a  brown  felted  mycelium,  but  penetrate  the  leaf 
through  the  stomata  by  a  central  "foot,"  is  founded  on  Asterina  Agaves 
E.  &  E.  Another  genus,  Piline^  is  substituted  for  Asterina  splendens. 
The  second  division  discusses  various  species  of  Physalospora^  a  number 
of  which  are  removed  to  other  genera.  Pledosphaera  g.  n.  replaces 
Physalospora  Bersamae  Syd.  Several  other  species  are  included  in  the 
new  genus.  Physalospora  rosicola  becomes  the  type  of  Schizostege  g.  n., 
and  Physalospora  boreal  is  the  type  of  Heter  opera  g.  n.  Under 
Stigmataceae  (the  third  division)  he  gives  notes  on  the  genera  Stigmatea, 
Ooleroa  and  Vigella.  Finally,  he  discusses  various  fungi,  establishing  as 
new  genera  Halbaniella  (Microthyriace^e)  and  Plactogene  (Sphaeriaceae). 
Theiszen  has  in  this  paper  established  seven  new  genera.  The  plants 
dealt  with  are  herbarium  specimens.  A.  L.  S. 

^Study  of  Botryosphseria.— F.  Theiszen  {Ann.  Mycol.,  1916,  14, 
297-340,  1  fig.).  Theiszen  gives  an  historical  account  of  this  genus, 
and  then  describes  its  characteristics  and  affinities.  In  most  of  the 
species  the  perithecia  are  embedded  in  a  stroma ;  only  rarely  are  they 
isolated.  The  inner  structure  of  the  stroma  is  not  distinctive,  and 
spores  are  frequently  undeveloped  in  herbarium  material.  It  is  neces- 
sary, therefore,  in  distinguishing  species  to  rely  more  or  less  on  the 
outward  appearance  of  the  fungus.  He  divides  the  genus  into 
(1)  Sderopleoidea,  in  which  the  perithecia  occur  singly,  and  Botryosa, 
where  they  are  united  in  a  stroma.     The  Botryosa  species  are  further 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  89 

divided  up  according  to  the  form  of  the.  stroma — round,  ellipsoid, 
elongate,  etc.  The  species  described  (66)  are  from  herbaria,  and  thus 
thej  have  been  collected  in  many  parts  of  the  world,  though  most  of 
them  are  from  America.  A.  L.  S. 

Additional  Notes  on  Dothideae  and  other  Microfungi.  —  F. 
Theiszen  and  H.  Sydow  {Ami.  Glycol,  191G,  14,  444-53).  These 
notes  are  on  fungi  from  widely  different  localities,  most  of  them  already 
described  ;  some  are  now  transferred  to  other  genera.  Descriptions  and 
synonymy  are  given.  Two  new  genera  are  published — Fhragmosperma, 
based  on  Micropeltis  Ilarattiae  P.  Henn.  ;  and  Periaster^  based  on 
Erikssonia  spathoIoM  Syd.  Periaster  differs  from  Erikssonia  in  the 
septate  spores.  A.  L.  S. 

Mycological  Memoirs. — F.  Theiszen  {Verk.  Zool.  Bot.  Ges.  Wien, 
1915,  66,  296-400,  1  pi.,  14  figs. ;  see  also  Ann.  Mycol,  1916,  14, 
469-70).  The  phylogeny  of  the  Pseudosphaariaceffi  receives  special 
attention.  According  to  the  author  the  family  is  closely  associated 
with  Myriangiaceffi  ;  the  two  differ  in  the  more  or  less  complete  separa- 
tion of  loculi  in  the  fruiting  body.  Englerulaceae  are  fully  described, 
and  as  new  genera  are  added  Euthnjpton,  Thrauste.  Syntexis  and  Ophio- 
texis.  The  genus  Physalospora  is  fully  described,  and  to  it  are  added 
as  new  genera  PyrenieUa,  Eypostegium.,  Disperma  and  Amerostegi,  the 
latter  placed  under  Clypeosph^riaceag.  A.  L.  S. 

New  Ascomycetes. — H.  Rehm  (Ati7i.  Mycol.,  1915,  13,  1-6).  The 
fungi  described  are  from  Europe  and  North  xlmerica.  A  few  have  been 
previously  described.  Diagnoses  and  notes  are  given  along  with  locality 
and  collector.  A.  L.  S. 

Some  New  Fungi.— Fe.  Bubak  and  H.  Sydow  [Ann.  Mycol.,  1915, 
13,  7-12,  2  figs.).  The  species  described  are  microfungi  belonging  to 
the  Ascomycetes  or  to  the  Deuteromycetes,  and  were  collected  in  various 
districts  of  Germany.  A  new  Hyphomycete  is  described,  Pachylasi- 
diella  polyspora  g.  et  sp.  n.  It  is  distinguished  by  the  very  broad  blunt 
conidiophores,  which  bear  four  to  eight  conidia  at  the  apex.    A.  L.  S. 

New  Fungi  from  Bohemia. — Fr.  Bubak  {Ann.  Mycol.,  1915,  13, 
26-34).  A  considerable  number  of  new  species  belonging  to  the 
Sphaeropsideae  are  described,  and  others  are  critically  considered.  They 
are  all  parasitic  on  the  higher  plants  ;  some  of  them  cause  serious 
disease.  A.  L.  S. 

Various  Contributions.— T.  Theiszen  {Ann.  Jlycol,  1916,  14, 
263-73,  6  figs.).  Under  this  heading  the  author  publishes  notes 
on  fungi  along  with  descriptions  of  new  forms.  He  has  passed  in 
review  a  number  of  species  of  Rhytisma  from  the  Kew  Herbarium,  now 
unrecognizable  ;  others  are  from  American  collections.  A  new  genus, 
Haplophyse  (Hypodermatacege),  from  Hawaii  has  been  diagnosed.  It 
grew  on  leaves  of  Coprosma.     Other  genera  and  species  are  dealt  with. 

A.  L.  S. 


90  SUMMARY   OF  CURRENT   RESEARCHES   RELATING  TO 

Genus  Parodiella. — F.  Theiszen  and  H.  Sydow  {A7iti.  MycoL,  1917, 
15,  125-142).  The  genus  Parodiella  was  based  by  Spegazzini  on 
Doihidea  perisporiordes.  He  described  it  as  a  Perisporieae.  The  above 
writers  have  amended  it  and  have  added  many  new  species.  Among 
the  forms  examined  they  have  detached  a  number  that  are  not 
Farodiellse,  and  among  these  they  find  new  genera :  Bypoplegma^ 
Fseudoparodiay  Chrysomyces  and  Rhizotexis.  A.  L.  S. 

Origin  and  Development  of  the  Pycnidium. — F.  E.  Kempton 
[Bot.  Gaz.,  1919,  68,  233-61,  6  pis.).  The  author  takes  up  De  Bary's 
view  of  a  twofold  origin  of  these  structures  :  "  symphogenous  "  when 
the  pycnidial  primordium  arises  from  an  interwoven  network  of  hyphae  ; 
"  meristogenous  "  when  the  primordium  arises  from  a  hyphal  cell  or  a 
group  of  adjacent  cells  of  a  single  hypha  by  continued  cross  and 
longitudinal  division.  Species  belonging  to  a  number  of  genera  were 
studied  chiefly  by  cultures  from  spores  or  hyphag.  The  meristogenous 
method  was  found  to  be  the  most  frequent,  and  in  it  there  are  two 
modes  of  development :  "  simple  "  when  the  pycnidium  arises  from  a 
single  cell  or  a  few  adjacent  cells  of  a  single  hypha  ;  and  "  compound  '* 
when  the  cells  of  adjacent  hyphae  take  part  in  the  primordium. 

Acervuli  arise,  as  do  pycnidia.  The  pseudo-acervulus  of  Pestalozzia 
develops  first  as  a  pycnidium,  then  breaks  open  and  appears  like  an 
acervulus.     The  different  stages  of  growth  are  well  illustrated. 

A.  L.  S. 

Development  and  Biology  of  Pycnidia. — H.  Schnegg  {CentraJU, 
BakL  Abt.  2,  1915,  43,  326-64,  25  figs.  ;  see  also  Ann.  Mycol,  1916, 
14,  294-5).  A  widely  spread  fungus  in  breweries  was  placed  in  culture, 
and  its  development  as  a  Phoma  was  watched.  The  pycnidia  arose,  in  all 
cases,  from  the  conidia  in  the  culture-media.  One  ostiole  was  usually 
formed,  but  several  might  arise.  In  thirty  to  thirty-two  hours  after  sow- 
ing, the  conidial  development  would  be  complete.  Wort  was  found  to 
be  the  most  favourable  medium  ;  in  other  media  the  fungus  gradually 
degenerated.  In  the  older  cultures  resting  spores  of  various  kinds  were 
formed.     The  fungus  was  named  Phoma  conidiogena.  A.  L.  S. 

Lists  of  Fusaria. — H.  W.  Wollenweber  {Ann.  Mycol.,  1917,  15, 
1-56).  The  lists  compiled  by  the  author  are  mainly  based  on  his  own 
collections  and  cultures.  He  gives  first  an  account  of  his  herbarium, 
and  then  a  note  on  the  results  arrived  at.  Of  the  442  so-called  Fusaria 
180  are  true  fungus  species,  but  69  of  these  belong  to  other  genera, 
mostly  Hyphomycetes.  A  number  also  are  conidial  forms  of  Ascomy- 
cetes,  such  as  Gibberella,  Calonectria,  Bypomyces  and  Nectria.  The 
relationship  between  the  forms  has  been  established  by  cultures.  A 
tabulated  list  is  given  of  all  these  fungi  now  determined  ;  a  list  of  the 
Fusaria  to  be  conserved  and  of  those  to  be  excluded  ;  a  list  of  host 
plants  with  their  parasites  ;  and,  finally,  diagnoses  of  a  new  genus, 
Neonectria,  and  several  new  species  of  Fusarium.  A.  L.  S. 

Position  of  the  Sorus  in  Uredineae  and  its  Value  as  a  Syste- 
matic Character.— F.  Grebelsky  {Gentralhl.  BakL,  1915,  AM.  2,  43, 
645-62,  12  figs.;    see  b\^o  Ann.  Mycol.,  1916,  14,  130).     The  author 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  91 

finds  that  the  position  of  the  uredospores  depends  on  the  stomata,  and 
they  are  mostly  to  be  found  only  on  the  side  of  the  leaf  where  they  are- 
formed.  In  certain  cases,  however,  where  stomata  occur  on  both 
surfaces,  the  uredospores  are  confined  to  one.  Teleutospores  appear 
very  often  on  the  side  of  the  leaf  free  from  stomata.  A.  L.  S. 

Some  New  Roumanian  Uredinese. — J.  C.  Constantineanu  {Ann^ 
Mycol.,  1916,  14,  268-536,  6  figs.).  The  author  here  describes  five 
new  species  belonging  to  JJromyces  and  Puccinia.  Very  full  descrip- 
tions are  given,  with  figures  of  the  various  spores.  Comparisons  are 
made  between  the  species  described  and  allied  forms.  A.  L.  S. 

Grass  Rusts  of  Unusual  Structure. — J.  C.  Arthur  and  E.  B. 
Mains  {Bull  Torrey  Bot.  Club,  1919,  46,  411-5,  2  figs.).  The 
authors  remark  on  the  close  resemblance  of  the  leaves  of  Olyra 
(PaniceaB)  with  those  of  various  bamboos.  This  has  led  to  some  confusion 
in  determining  the  hosts  of  their  respective  rusts,  but  also  there  is  a 
curious  resemblance  between  these  rusts.  Comparisons  are  drawn 
between  three  of  them  : — Puccinia  pallescens  on  Tripsacum,  P.  phaJcsop- 
soroides  sp.  n.  on  Olyra,  and  Uredo  ignava  on  the  genus  Bambusa. 
Tropical  rusts  frequently  produce  thin-walled,  pale  or  colourless  spores^ 
with  a  fringe  of  incurved  hyphoid  paraphyses.  The  authors  find  these 
characters  present  in  the  species  examined.  A.  L.  S. 

Systematic  Position  of  Uredo  alpestris  Schrot. — P.  Dietel  {A7in, 
Mycol.,  1916,  14,  98-9).  This  Uredo  on  Viola  Uflora  is  frequently 
found  in  the  Alps.  There  occur  in  the  sori  spores  of  two  kinds  :  broadly 
fusiform  with  a  projection  at  the  apex,  or  ellipsoid  and  without  any 
projection.  Dietel  holds  that  such  uredospores  are  only  known  in  the 
genus  Uredinopsis.  In  other  respects  also  the  Uredo  is  similar  to  that^ 
of  the  above  genus.  A.  L.  S. 

Research  on  the  Behaviour  of  the  Nuclei  in  the  Reproduction, 
of  Smut  Fungi. — Eugen  Paravicini  {Ann.  Mycol.,  1917,  15,  57-96,, 
6  pis.,  5  figs.).  The  author  gives  an  historical  account  of  work  done  on 
the  reproductive  nuclei  of  fungi.  He  then  sets  out  the  problems  still 
awaiting  solution  in  the  Ustilagineae,  and  describes  the  methods  he 
employed  in  his  research.  He  wished  to  verify  the  nuclear  fusions 
already  described  in  Ustilagineae  and  Tilletiae ;  to  examine  further  species- 
as  to  whether  in  the  copulation  of  conidia  and  promycelia  there  was  a 
passing  over  of  protoplasm  along  with  the  nuclei,  etc.  The  solution  of 
these  and  other  problems  was  sought  in  the  germination  of  spores  in 
artificial  cultures  of  many  species.  He  confirmed  the  presence  of  one 
nucleus  in  the  spore,  which  divides  or  germinates,  one  of  the  daughter- 
nuclei  passing  to  the  promycelium.  The  conidia  formed  on  the  promy- 
celium  are  also  uninucleate.  When  two  conidia  copulate  the  nucleus 
and  protoplasm  of  one  cell  pass  to  the  other.  Mycelial  cells  copulate 
similarly.  A  binucleate  coujugate  condition  thus  arises  and  is  to  be 
found  in  the  mycelium  of  infected  host  plants.  Fusion  between  the 
conjugate  nuclei  takes  place  on  spore-formation,  and  this  the  author 
regards  as  a  sexual  act.  A.  L.  S. 


92  SUMxMARY   OF   CURRENT   RESEARCHES   RELATING  TO 

Researches  on  the  Infection  of  Cereal  Rusts.— G.  Gassner 
{Ce?itralbl  Bakt.,  Idlb,  AM.  2,  44,  512-617;  see  also  ^nw.  3Iycol, 
1916,  14,  285-6).  The  author  has  worked  for  several  years  in  Uruguay 
on  rust  infection,  and  he  finds  that  it  is  in  certain  cases  influenced  by 
the  stage  of  development  reached  by  the  host.  This  is  especially  the 
case  in  Puccinia  graminis  ;  young  host  plants  can  resist  infection  during 
the  greater  part  of  the  year,  while,  at  a  later  stage  of  growth,  the  plants 
are  more  easily  infected  and  the  young  leaves  of  these  older  plants  also 
suffer.  Other  results  were  obtained  with  P.  triticina  and  P.  coronifera. 
They  could  infect  cereals  at  any  stage  up  to  the  time  of  teleutospore 
development.  The  time  of  maximum  infection  was  found  to  differ  for 
the  various  rusts.  A  warm  temperature  was  favourable  to  rusts ;  the 
physical  condition  of  the  soil  had  no  effect,  except  through  greater  or 
less  moisture.  A  high  content  of  nitrogen  in  the  soil  was  not  found  to 
be  particularly  favourable  to  infection.  Phosphorous  manure  had  no 
effect  except  in  the  case  of  P.  graminis,  when  the  host  plant  may 
have  matured  earlier  and  so  reached  the  infection  stage  more  quickly. 

A.  L.  S. 

Sexuality  in  the  Basidiomycetes. — Mathilde  Bensaude  {Memoirs^ 
1918,  1-150,  13  pis.,  30  figs.  ;  see  also  Mycologia,  1919,  11,  280-3). 
This  is  a  careful  and  long  study  of  nuclear  phenomena  in  the  mycelia 
of  Basidiomycetes.  The  writer  argues  for  the  sexual  significance  of 
the  familiar  typhal  anastomoses  in  these  fungi.  Cultured  studies  were 
made  from  spores  and  from  mycelia  gathered  in  the  field.  In  a  culture 
from  spores  of  Coprinus  fimetarius  she  found  that  mycelium  from  a 
single  spore  grew  vegetatively  for  eight  months  ;  there  was  no  carpo- 
phore development.  With  a  mixed  culture,  fruit  bodies  w^ere  formed. 
She  concludes  that  binucleated  cells  are  formed,  following  plasmogamy 
between  cells  coming  from  two  different  thalli,  though  she  also  considers 
that  some  Basidiomycetes  are  homothallic,  while  others  are  hetero- 
thallic,  as  in  the  Mucorini.  Clamp  formations  and  their  importance 
are  fully  described  and  discussed.  A.  L.  S. 

Gasteromycetae  ZeylanicaB. — T.  Fetch  {Ann.  Roy.  Bot.  Gard., 
Peradeniga,  1919,  7,  57-78).  Gasteromycetes  are  very  frequent  in  the 
tropics  and  occur  under  strange  forms.  T.  Fetch  has  published  a  list  of 
all  those  collected  in  Ceylon  by  himself  or  others.  He  gives  an  account 
of  the  collections  and  of  the  various  determinations  of  the  fungi.  A 
number  of  new  species  are  included,  and  a  new  genus,  Pharus,  is  based 
on  Lysurus  Gardneri  Berk.  A.  L.  S. 

Revisions  of  Ceylon  Fungi.— T.  Fetch  {Ann.  Roy.  Bot.  Gard., 
Peradeniya,  1919,  7,  1-44).  This  is  part  vi.  of  Fetch's  examination 
of  doubtful  species  ;  the  numbers  treated  are  218-72,  and  comprise 
some  of  the  larger  fungi,  though  mainly  microfungi.  There  is  one  new 
genus,  Phseopeltis,  based  on  Micropeltis  gomphispora  B.  &  Br.  The 
notes,  historical  and  descriptive,  are  very  full.  A.  L.  S. 

Mycological  Contributions.— H.  and  F.  Sydow  {Ann.  Mycol,  1918, 
16,  240-8).     The  paper  deals  chiefly  with  a  critical   examination  of 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  93 

kuown  species.  Of  most  importance  are  the  species  of  Uredineae,  of 
which  several  new  genera  are  established  :  Desmella,  in  which  the 
teleutospores  are  borne  on  hjphae  that  emerge  in  fascicles  through  the 
stomata  ;  Calidion^  of  which  the  uredospores  only  are  known — in  the 
sorus  there  are  many  curved  paraphyses  ;  and  Crossopsora,  in  which 
the  uredosori  are  surrounded  by  curved  paraphyses. 

In  a  further  paper  {Ann.  Mycol.,  1919,  17,  33-47,  figs.)  the  same 
authors  deal  with  microf ungi  from  many  localities.  They  establish  as 
new  genera  StarbaecMeUa  and  Microscypha  (Pyrenomycetes)  with 
Xenopeltis  (Sphseropsidese),  the  pycnidia  of  which  grow  on  the  fructifi- 
cations of  grasses.  There  is  a  lengthy  discussion  on  the  nomenclature 
of  MycosphsereUa.  A.  L.  S. 

Fungoid  Infection  of  Eggs. — A.  Brtnik  (Centralbl  BaJct.,  19 1^, 
Ait.  2,  46,  427-44  ;  see  also  Ann.  Mycol,  1916,  14,  474).  It  was 
proved  that  eggs  from  absolutely  clean  localities  and  with  good  handling 
in  transport  were  extremely  resistant  to  the  entrance  of  fungi  up  to» 
three  months'  duration  or  more.  The  fungi  dealt  with  were  Mucor 
mucedo,  31.  stolonifer,  Aspergillus  niger,  A.glaucus,  Penicillium  glaucum^ 
and  P.  irevicaule.  A.  L.  S. 

Growth  of  Fungi  in  Hens'  Eggs. — A.  Postolka  {Centralb.  Bakt.y 
AM.  2,  1916,  46,  320-80  ;  see  also  Ann.  Mycol,  1916,  16,  476).  A 
number  of  spoilt  eggs  were  examined,  the  fungus  being  due  to  fungus 
penetration.  The  effect  produced  on  the  ^^g  varied  exceedingly, 
Postolka  found  that  Penicillium  glaucum  and  Cladosporium  herbarum 
were  the  chief  agents  of  fungoid  infection,  but  other  fungi  might  also 
penetrate  and  spoil  the  eggs.  A.  L.  S. 

Field  Meeting  of  Pathologists. — William  A.  Murrill  {Myco- 
logia,  1919,  11,  308-12,  1  pi.).  Murrill  gives  here  an  account  of  the 
discussions  and  excursions  at  the  meeting  of  plant  pathologists  at  New 
Haven,  Storrs  and  elsewhere  in  August.  Spraying  problems  received 
special  attention.  Tobacco  fields  were  visited  and  several  diseases 
affecting  the  plants  were  noted.  A.  L.  S. 

Synonyms  and  Mycological  Notes.— J.  Bresadola  {Ann.  Mycol.^ 
1916,  14,  221-42).  During  some  years  the  author  has  dealt  with 
fungi  from  distant  lands,  and  has  had  occasion  to  examine  many 
herbarium  plants.  He  has  detected  a  great  many  errors  in  determina- 
tion, and  he  now  publishes  a  list  of  synonyms  that  he  has  come  across. 
They  refer,  almost  without  exception,  to  Hymenomycetes  from  other 
than  European  countries.  In  addition  to  the  bare  lists  he  has  added 
notes  and  short  descriptions  to  a  large  number.  A.  L.  S. 

Mycotheca  germanica,  Fasc.  xxvii-viii.  Nos.  1301-1400. — Sydow 
{Ann.  Mycol.,  1916,  14,  243-7).  Sydow  gives  a  list  of  the  century  of 
fungi  and  adds  full  diagnoses  of  his  new  species  in  the  fascicles.  They 
are  all  microfungi  from  dead  or  living  leaves  or  branches  of  plants. 

A.  L.  S. 


94  SUMMARY   OF   CURRENT  RESEARCHES  RELATING  TO 

Fungi  amazonici  of  E.  Ule.— H.  and  P.  Sydow  {Ann.Mycol,  1916, 
14,  65-97).  A  record  of  the  fungi  collected  by  the  late  E.  Ule  on  his 
last  journey,  mostly  from  Brazil ;  a  few  are  recorded  from  Peru.  There 
are  many  new  species  of  Uredinese  and  Ustilagineae.  In  the  various 
families  of  Ascomycetes  the  species  are  nearly  all  new  to  science.  As 
new  genera  '.—Cleistosphaera  (Perisporeacese)  ;  Haplostrona,  on  leaves 
of  Miconia,  with  perithecia  immersed  in  stromata,  of  doubtful  affinity  ; 
Stegastroma  (Clypeosphagriacese),  with  brown  1-septate  spores ;  Leptocrea 
(Hypocreace£e),'in  stromata,  with  oblong  simple  spores  ;  Gaudella  (Micro- 
thyriace^e),  of  which  the  1-septate  spores  have  a  long  slender  process  at 
the  lower  end.  The  Fungi  Imperfecti  are  less  numerous,  but  they  in- 
clude four  new  genera  : — Pyremchsetina^  near  ito  Fyrenochseta,  but  the 
pycnidia  without  pores  ;  Botryella,  with  minute  pycnidia  in  botryose 
stromata,  on  leaves  ;  Hemidothis,  with  Dothidea-like  stromata  and  filiform 
spores,  on  leaves  of  31iconia;  and  Marcosia  (Tuberculariaceae),  the 
conidia  of  which  formed  on  sporodochia  become  3-septate,  on  leaves  of 
Cynometra,  A.  L.  S. 

Contribution  to  the  Study  of  Northern  Fungi.— J.  Lind  (Ann. 
Mycol.,  1915,  13,  18-25,  4  figs.).  This  includes  a  critical  study  of  a 
number  of  species.  Fuccinia  porri  is  shown  to  be  the  same  plant  as 
Uromyces  mnbiguus,  but  of  different  form.  The  differences  are  fully  set 
forth.  The  author  made  culture  experiments  with  Fhorna  Rostrupii,  a 
fungus  which  causes  great  damage  to  Daiicus  Carota  ;  finally,  he  was  able 
to  connect  it  up  with  Lepfosphaeria  Rostrupii  sp.  n.  A  special  note  is 
written  on  Botrytis  cinerea.  Lind  repeats  his  former  statement  that 
Botnjtis  is  wholly  unconnected  with  Scleroti7iia.  Two  other  fungi  he 
describes  as  synonymous — Fusarium  avenaceum  and  Fionnotes  Biasolet- 
tiana.  The  Fusarium  is  a  wound  parasite  ;  its  mycelium  spreads  out 
and  forms  a  Stereum-like  fruit  body— the  Fionnotes  stage.  Three 
Ascomycetes  from  Finland  are  also  described,  two  of  which  are  new.  A 
copious  bibliography  is  appended.  A.  L.  S. 

Illustrations  of  Fungi.  XXXI.— William  A.  Murrill  {Mtjcologia, 
1919,  11,  289-92,  1  col.  pL).  The  fungi  dealt  with  are  edible.  Of  the 
three  depicted  and  described,  one — Fholiota  squarrosoides — is  American. 
The  author  gives  the  points  in  which  it  differs  from  the  European 
F.  squarrosa.  A.  L.  S. 

Mycological  Notes. — P.  A.  Saccardo  [Ann.  Mycol.,  1915,  13, 
115-38).  Saccardo  gives  an  account  of  eight  sets  of  Fungi  from  diffe- 
rent countries: — I.  Fungi  Noveboracensis  (States  of  New  York  and  Mass.), 
collected  by  H.  t).  House,  number  53  species  of  microfungi  belonging  to 
various  families  and  genera,  several  of  them  new  species.  II.  Fungi 
FJakotenses,  collected  by  J.  F.  Brenckle,  19  species.  III.  Fungi 
Canadenses,  17  species,  collected  by  J.  Dearness.  IV.  Fungi  Fhilippi- 
7ienses,  sent  to  Hariot  by  Baker  and  others,  8  species,  nearly  all  new. 

V.  Fungi  Uruguayenses,  19  species,  transmitted  by  0.  Matterolo,  and 
comprising  a  number  of  the  larger  fungi,  Agaricaceje  and  Polyporaceae. 

VI.  Fungi  Moravici  et  Bohemici,  22  species,  sent  by  Petrak.     VII.  Fungi 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  95 

Gallici,  Hispanici  et  Italici,  40  species,  sent  from  these  different  countries  ; 
one  new  genus,  Heteroceras  (Melanconiaceag),  and  a  number  of  new 
species  are  described.  VIII.  Fungi  Aiistralienses,  2  species  of  micro- 
fungi,  one  of  them  new.  A.  L.  S. 

Fungi  in  "  Scientific  Results  of  the  Expedition  to  Mesopotamia." 
— Fe.  Bubak  (1914,  28,  189-218,  2  pis. ;  see  also  A7i?i.  Mycol,  1915, 
13,  57-8).  Many  new  species  are  included  in  this  account ;  they  are 
all  of  them  minute  and  mostly  parasitic  species.  There  are  several  new 
genera — Sderosphaeropsis,  similar  to  a  sclerotial  Sphseropsis  ;  Basiascella 
(Leptostromacea^),  with  one-celled  brown  spores ;  Ramulariospora 
(Excipulacese),  with  spores  in  chains.  A.  L.  S. 

New  Fungi  from  Saxony. — G.  Bresadola  {Ann.  Mycol.^  1915, 13, 
194-6).  The  list  is  accompanied  by  a  note  from  Krieger,  explaining 
that  these  are  fungi  sent  by  him  to  Bresadola.  They  are  all  microf ungi, 
most  of  them  parasites  on  branches,  leaves,  etc.  A.  L.  S. 

Seventh  Contribution  to  the  Fungus  Flora  of  the  Tyrol. — Fr. 
Bubak  and  J.  E.  Kabat  {Ann.  Mijcol,  1915,  13,  107-14).  The 
authors  list  80  different  species,  most  of  them  already  determined ;  a 
small  proportion  are  new  to  science.  They  are  microfungi,  and  most  of 
them  parasites  on  living  plants.  A.  L.  S. 

Contributions  to  the  Knowledge  of  the  Fungi  of  Dalmatia. — 
Otto  Jaap  {Ann.  Mycol.,  1916,  14,  1-44).  A  very  large  number  of 
fungi  (510)  are  here  listed  by  the  author.  They  belong  to  all  the  diffe- 
rent groups.  First  on  the  list  are  nine  species  of  Myxomycetes  and  two 
species  of  Schizomycetes,  bacilli  which  gave  rise  to  disease  of  olive  trees. 
Habitat  and  locality  are  given  in  each  case.  Fifty  new  species  of 
microf  ungi  have  been  discovered  and  described  by  the  author.     A.  L.  S. 

Fungus  Flora  of  the  Tyrol. — Fr.  Bubak  {Ann.  Mycol.,  1916, 14, 
145-58,  figs.).  This  contribution — the  eighth  for  the  Tyrol — comprises 
seventy  different  species,  all  of  them  microfungi  and  many  of  them 
parasites.  A  large  number  of  new  species  are  described,  and  the  following 
new  genera : — Cytostaganospora^  in  which  the  pycnidia  are  covered  by  a 
clypeus;  Biplodothiorella,  which  differs  from  Dothiorella  in  the  two- 
celled  spores.  Bubak  also  slightly  emends  the  genus  Fedilospora  von 
Hohn.,  and  adds  a  second  species  to  it.  A.  L.  S. 

Diagnoses  of  New  Philippine  Fungi. — H.  and  P.  Sydow  {Ann, 
Ifycol.,  1916,  14,  353-75,  1  fig.).  The  fungi  determined  were  sent  by 
C.  E.  Baker  in  1915.  Sydow  diagnoses  a  new  genus  of  Puccineaceae, 
Aiithomycetella,  in  which  the  teleutospores  are  in  two  series  :  the  upper 
series  of  one  cell,  the  lower  of  six  to  eight  cells,  much  narrower  than  the 
upper.  Setella,  a  new  genus  of  Periosporiaceae,  is  distinguished  by  the 
apical  setulae  of  the  perithecium  and  the  septate  spores  ;  Rhahdostroma^ 
near  to  Scirrhiella,  with  subepidermal  stromata  and  colourless  spores, 
one  septate  near  the  base  ;  Stegasph-eeria^  the  representative  of  a  new 


96  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 

family,  Stegasphaeriacese,  very  near  to  Clypeosph^riaceffi ;  and  in  tli& 
same  family,  Stegaphora  ulmea,  formerly  Gnomonia  sp.  Other  new 
genera  of  Ascomycetes  are—Fi/cnopeUis  (Trichopeltacearum)  ;  Stegano- 
pijcnis  (Sphserioide^)  ;  Discothecium  (Leptostromatge)  ;  and  a  new- 
genus  of  Hyphomycetes,  Xiphomyces  (Tuberculariaceae),  with  very  large 
continuous  acrogenous  yellow-brown  conidia.  A.  L.  S. 

Fungi  Papuani. — H.and  P.  Sydow  {Engler's  lot  Jahrl.,  1916,  54^ 
246-61,  3  figs. ;  see  also  Ann.  Mycol,  1916, 14,  468-9).  These  include 
Basidiomycetes,  Ascomycetes  and  Fungi  Imperfecta  A  number  of  new 
species  are  described  in  each  group,  and  as  new  genera  Scrosperma 
(Sphseropsidese),  and  Sarophonm  (Hyphomycetes).  A.  L.  S. 

Contributions  to  Mycology.  IX. — Fr.  von  Hohnel  {Zeitschr.  f, 
Gdhrimgsphysiologie,  1915,  5,  191-215  ;  see  also  Ann.  J7^co/.,  1916,14, 
122-3).  Yon  Hohnel  publishes  an  account  of  llyxosporium,  a  genus 
of  Melanconiea3,  the  species  of  which  grow  on  branches  of  trees.  He 
has  subdivided  it  into  fourteen  new  genera,  and  finds  Myxosporium  as 
understood  by  Link  and  others  does  not  exist.        .  A.  L.  S. 

Fungi  from  Various  Localities. — Fr.  Bubak  (Ann.  My  col.,  191(>, 
14,  341-52,  2  figs.).  The  author  deals  mostly  with  new  species — one 
Entomophthora,  the  others  belonging  to  Sphseropsidese  or  Hyphomycetes,, 
and  mostly  collected  in  Bohemia.  A  new  genus,  Titseospora  (Mucedinege)^ 
is  described,  with  peculiar  curved  septate  spores.  It  has  been  found  in 
Europe  and  America.  Another,  Colnmnophora  (Demetieae),  has  been 
fipjured  and  described  :  it  grows  on  the  stroma  of  Rhytisma  Salicis. 

A.  L.  S. 

Mycological  Notes. — R.  G.  Fragoso  [Mem.  Real.  Soc.  Esp.  Hist. 
Nat.,  1919,  11,  77-123, 1  fig.).  A  large  number  of  microfungi  belong- 
ing to  many  different  families  and  genera  are  listed.  Several  are  new  to 
science.  Many  of  them,  such  as  species  of  Phyllachora  and  Erisyphey 
are  parasitic  on  living  plants.     A  full  index  is  provided.  A.  L.  S. 

Contribution  to  the  Knowledge  of  the  Fungus-Flora  of  the 
Philippine  Islands.— H.  and  P.  Sydow  {Ann.  Mycoh,  1917,  15,  165- 
268,  3  figs.).  This  list  includes  representatives  of  many  different 
groups.  Most  abundant  of  all  are  the  Pyrenomycetes,  and  many  of  the 
species  recorded  are  new.  The  authors  have  also  described  new  genera  ; 
these  are  : — Ceratochaete,  Teratone^na,  Irene,  Melanomyces,  Linotexis,. 
Bolosplisera,  Dimerinopsis,  Baker omyces,  Prostigme,  Linoholus,  Lino- 
carpon,  Hyalocrea,  Epinectria,  Stereocrea,  Lasiostemma,  Chsetaspis,  Pleio- 
stomella,  iSynpeUis,  Metanoplaca,  Chaetoplaca,  Eremothecella,  Yatesula,  and 
Peltella.  Among  Discomycetes  they  have  also  estabhshed  new  genera  : — 
Benguetia,  with  a  spreading  disc  and  a  dense  black  hypothecium  ; 
Calloriopsis,  as  the  name  implies,  near  to  Calloria  ;  and  Ramosiella,  near 
to  JEgyron.  In  Sphnpropsidea?  they  have  placed  as  new — Stenocarpella, 
Botryogene,  Discotheciella,  and  Peltaster.  Leucodochium  is  a  new  genus 
of  Tuberculariaceae ;  the  conidia  are  green  coloured.  FuUgo  septica  is 
the  only  Myxomycete  recorded.  A.  L.  S. 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  97 

New  Species  of  Fungi.    XIII. — H.  and  P.  Sydow  (An7i.  3fycol., 

1915,  13,  34-43,  2  figs.).  The  fungi  described  came  from  many  parts, 
mostly  from  Asia  and  Africa.  They  comprise  species  of  Uredinese  and 
Ustilagineae,  Ascomycetes  and  Denteromycetes.  Of  special  interest  are 
a  new  species  of  Eurytheca  from  Trinidad,  and  a  new  genus  of  Dema- 
teaceae,  Gheirojjodium.  There  are  no  specialized  conidiophores  in  the 
latter  ;  the  conidia  rise  directly  from  the  creeping  mycelium,  which  also 
bears  hair-like  tufts.  G.  flagellatwn  grew  on  living  leaves  of  Carex  in 
Japan.  A.  L.  S. 

Contributions  to  the  Fungus-Flora  of  Moravia  and  Austrian 
Silesia.— F.  Petrak  {Ann.  Mycol,  1915,  13,  44-51).  The  author 
gives  a  short  list  of  known  fungi,  and  then  describes  at  length  a  con- 
siderable number  of  new  species  of  minute  Ascomycetes,  with  copious 
biological  notes. 

In  a  subsequent  contribution  (Atm.  MycoL,  1916,  14,  159-76) 
Bubak  continues  his  account  of  these  minute  fungi  belonging  to  the 
Pyrenomycetes  and  also  to  Fungi  Imperfecta  He  again  diagnoses  many 
new  species.  He  discusses  various  specific  points,  such  as  the  occurrence 
of  the  black  stroma  line  in  Phomopsis,  a  feature  by  no  means  constant. 

In  a  further  paper  (A7in.  My  col.,  1916,  14,  440-3)  Petrak  records 
a  new  genus,  CucurUtariella,  with  congregate  perithecia  and  brown 
simple  spores.  G.  moravica  sp.  n.  grew  on  branches  of  Primus  spinosa  ; 
four  new  species  of  Phomopsis  are  also  added  to  science  and  to  the 
fungus-flora  of  Moravia.  A.  L.  S. 

Further  Contributions  to  the  Fungus-Flora  of  Switzerland. — 
Otto  Jaap  {Ann.  Mycol,  1917,  15,  97-124).  This  is  a  second  list  of 
Swiss  fungi  by  the  author.  The  species  were  collected  by  him  in  a 
journey  through  Switzerland  in  the  summer  of  1910,  and  at  Lugano  in 
1913.  He  gives  a  short  list  of  Myxomycetes.  The  fungi  are  all  micro- 
fungi,  belonging  to  many  different  groups.  A  number  of  species  are 
new  to  science.  A.  L.  S. 

Fungi  Indias  Orientalis.  Part  V.— H.  and  P.  Sydow  and  E.  J. 
Butler  {Ann.  MycoL,  1916,  14,  177-220).  The  present  contribution 
deals  with  Sphseropsidese  and  a  few  Melanconieae.  H.  Diedecke  helped 
in  the  determination  of  the  new  fungi.  Many  of  the  new  species  are 
parasites  on  Indian  plants,  and  were  collected  in  various  parts  of  India.. 
The  new  genera  are  :  Phyllostictina  Syd.,  which  differs  from  Phyllosticta. 
in  that  the  spores  are  involved  in  mucus;  Pleosphaeropsis,  in  which 
the  spores  become  brown;  Gystophsera  Died.,  nearly  akin  to  the 
preceding,  but  differing  in  the  absence  of  mucus  ;  Plenozythia  Syd. 
(Nectrioidese),  with  simple  spores  ;  and  Diplozythiella  Died.,  with  two- 
celled  spores.  There  is  also  a  new  genus  in  Leptostromataceae,  Siro- 
thyrium  Syd.,  in  which  the  membranaceous  stroma  is  not  stellate  as  in 
Sirothyriella.  A.  L.  S. 

Novae  Fungorum  Species.    XIV. — H.  and  P.  Sydow  {Ann.  Mycol. y 

1916,  14,  256-62,  1  fig.).     Sydow  gives  diagnoses  of  fungi  mostly  from 

H 


98  SUMMARY    OF    CURRENT    RESEARCHES    RELATING   TO 

tropical  lands,  from  India,  Philippines,  etc.  A  number  of  them  are 
Uredineaj.  There  is  one  new  genus,  Stilbodendron  camerunense 
(Stilbace^e),  from  the  Cameroons.  The  fruiting  bodies  are  erect  and 
rather  long  and  brightly  yellow,  and  covered  the  whole  length  with  fertile 
hypha^  that  bear  chains  of  conidia.  A.  L.  S. 


Lichens. 

New  or  Better-known  Lichens. — A.  Hue  {Ann.  Mycol.,  1915,  13, 
73-103).  Abbe  Hue  describes  a  considerable  number  of  new  species, 
many  of  them  from  China  and  Japan.  Most  of  them  belong  to  the 
genus  Lecanora,  as  understood  by  him.  Very  lengthy  and  detailed 
descriptions  are  given  of  each  species,  but  chemical  reactions  are  mostly 
ignored.  Several  species  described  formerly  by  himself  and  others  are 
emended.  A.  Lorrain  Smith. 

New  Lichens.  VIII. — A.  Zahlbruckner  {A7in.  My  col.,  1916,  14, 
45-61).  The  present  contribution  includes  twenty-five  lichens  from 
Japan,  most  of  them  new  to  science.  They  are  very  fully  described,  and 
their  affinities  with  other  species  are  indicated.  In  footnotes  the  author 
has  given  keys  to  Japanese  species  of  Pyrenula  and  Hdematomma. 

A.  L.  S. 

German  and  Austrian  Lichens  as  Food  and  Fodder.— C.  Jacobi 
{TilUngen,  3Iohr,  1915,  8vo.,  16  pp. ;  see  also  Ann.  Mycol,  1916, 14, 142). 
Owing  to  war  conditions  the  economic  value  of  lichens  had  to  be  tested. 
The  author  found  that  Iceland  moss  {Getraria  islandica)  was  rich  in 
starch-content  and  valuable  as  food,  if  the  bitter  principle  were  removed. 
Instructions  are  given  how  to  deal  with  the  plant.  He  proved  also  that 
Gladonia  rangiferina.,  the  reindeer  moss,  was  a  valuable  fodder  for  pigs. 

A.  L.  S. 

Lichenes  in  A  Ginzherger  :  Contributions  to  the  Natural  History 
of  Scoglien  and  the  Smaller  Islands  of  South  Dalmatia. — A.  Zahl- 
bruckner {Denkschr.  K.  Akad.  Wiss.  Wien  Math.-Naturw.  Kh,  1915, 
92,  301-22;  see  also  Ann.  Mycol,  1916,  14,  142-3).  The  lichens 
enumerated  (126  species)  belong  to  the  "  Adriatic  Lichen-region,"  and 
they  are  similar  to  those  already  collected  on  the  larger  islands.  Additions 
have  been  made  of  lichens  on  primitive  rocks.  Very  characteristic 
species  from  North  Africa  were  found.  As  a  whole  these  Adriatic  lichens 
resembled  East  rather  than  West  Mediterranean  forms.  A.  L.  S. 

Morphological  and  Biological  Observations.— K.  Goebel  {Flora, 
1915, 108,  311-5).  In  the  mountains  of  Brazil  a  species  of  Ephebaceae 
was  frequently  found  on  stones  in  waterfalls.  The  specimens  were  all 
sterile,  and  could  not  be  determined  ;  the  algal  cells  belonged  to  Stigo- 
nema.  The  noteworthy  fact  is  the  unusual  formation  of  haustoria  in 
the  hyphae,  and  their  penetration  into  the  algal  cells,  which  were 
ultimately  killed.     The  fungus  in  this  instance  was  a  true  parasite. 

A.  L.  S. 


ZOOLOGY    AND    BOTANY,    xMICROSCOPY,    ETC.  99 

Characteristic  Constituents  of  Lichens. — 0.  Hesse  (Joum.  Prakt. 
Chemie,  1915,  93,  254-70  ;  see  also  Ann.  Mycol,  1916,  14,  480).  In 
this  contribution  Hesse  deals  mainly  with  the  starch-content  of  certain 
lichens.  As  compared  with  the  potato,  the  starch  of  Getraria  islandica 
is  1  :  2  •  35,  in  reindeer  moss  1  :  2  *  5.  These  two  lichens  are  therefore 
valuable  as  human  food  or  as  fodder  for  cattle.  In  the  former  case  the 
bitter  principle  contained  in  the  plant  must  be  eliminated.     A.  L.  S. 

Lichenographical  Notes. — D.  Steiner  (Oesterr.  Bot.  Zeitschr.,  1915, 
65,  278-92  ;  see  also  Ann.  Mycol.,  1916, 14,  397-8).  In  the  first  three 
chapters  of  this  work  Steiner  deals  with  the  section  Aspicilia  of  the 
genus  Lecanora ;  certain  species  have  been  critically  studied  and  de- 
scribed. He  has  shown  also  that  the  genera  Placolecania  and  Soleno- 
spora  are  synonymous,  and  that  the  latter  has  priority.  The  genus 
Acaraspora  has  also  been  examined  with  reference  to  the  compound 
apothecia  characteristic  of  some  species ;  some  of  these  associated 
hymenia  have  a  common  exciple,  others  retain  separate  margins,  and 
are  known  as  "  Apothecia  composita."  He  contrasts  the  formation  of 
pycnidia,  which  may  be  associated  and  show  chambered  interiors. 

A.  L.  S. 

The  Lichen-Flora  of  Hertfordshire.— Robert  Paulson  {Trans. 
Hertf.  Nat  Hist.  Soc,  1919,  17,  83-96,  1  pi.).  Two  previous  lists  of 
lichens  had  been  made  for  Hertfordshire,  the  second  of  the  two,  in 
1902,  numbered  sixty-seven  species.  Paulson  now  records  143  species, 
varieties,  or  forms.  Attention  is  directed  to  the  habitat  of  the  lichens 
with  reference  to  light  intensity  and  to  the  soil,  which  even  affects 
the  number  of  tree-lichens.  The  number  of  saxicolous  lichens  recorded 
has  been  greatly  increased.  The  author  has  himself  verified  the  lichens 
recorded  with  the  exception  of  nine  species.  A.  L.  S. 

Lichen-Flora  of  Kazan.  —  Const.  Mereschkovsky  {Hedivigia, 
1919,  61,  183-241,  1  pi.).  The  author  describes  the  country  round 
Kazan — flat  and  without  any  rocky  formations.  The  flora  is  therefore 
soil  or  forest,  and  the  absence  of  rocks  is  reflected  in  the  prevailing 
type  of  lichen  vegetation.  There  is  also  a  complete  absence  in  his 
list,  as  he  himself  notes,  of  Stereocaidon,  Nephroma,  Opegrapha,  and 
Collemaceas.  There  is,  further,  an  almost  complete  lack  of  Ramalina, 
which  he  explains  (?)  by  the  distance  from  the  sea.  A  predominant 
genus  is  Physcia.  In  certain  forests  the  trees  are  covered  with  grey 
or  white  spots,  the  thallus  of  various  Physcise.  Mereschkovsky  has 
described  many  new  varieties  and  forms  of  well-known  and  variable 
lichens.  A.  L.  S. 

Discussion  of  Parmelia  camtschadalis. — Const.  Mereschkovsky 
{Hedivigia^  1919,  61,  303-7).  Certain  authors  having  affirmed  the 
absence  of  this  lichen  in  Kamschatka,  Mereschkovsky  brings  forward  facts 
to  prove  that  the  lichen  in  question  is  found  there,  that  is  has  been  found 
at  Geneva,  and  that  it  is  autonomous,  and  not  identical  with  Evernia 
furfur acea.  A.  L. 

H  2 


100  SUMMAP-Y   OF   CURRENT   KESEARCHES. 

Relation  of  Silicicolous  Lichens  to  the  Substratum.— E.  Bachmann 
[Ber.  Deutsch.  Bot.  Ges.,  1917,  35,  467-76,  8  figs.).  The  author  found 
that  the  hyph^  of  Lecidea  crustidata  left  no  trace  on  quartz  crystals. 
He  noted  that  the  rhizoids  of  ParrneUa  siihaurifera  swelled  at  the  base 
into  a  somewhat  stellate  "  foot-plate,"  which  consisted  of  mucilage  cells. 
A  hollow  space  between  the  foot-plate  and  the  lower  surface  of  the 
thallus  served  as  a  "  damp  chamber,"  and  therefore  the  rhizoids  of  this 
species  serve  as  water  conductors  and  water  storers.  A.  L.  S. 

Relation  between  Algae  and  Hyphse  in  the  Lichen-thallus. — 
W.  NiENBURG  (Zeitschr.  Bot,  1917,  9,  529-43,  1  pi.,  6  figs.).  The 
author,  while  criticizing  recent  work  by  Elfving,  records  the  results  of 
his  own  researches  :  that  algfe  are  transported  within  the  thallus  by 
"  push-hyphae  "  from  the  gonidial  zone  to  positions  in  the  cortex  ;  and 
also  that  cases  of  parasitism  occur  in  Evernia  furfuracea.  On  this 
account  he  regards  the  relationship  between  the  components  of  the 
thallus  as  helotism.  A.  L.  S. 

Botanical  Results  of  the  Swedish  Expedition  to  Patagonia  and 
Terra  del  Fuego,  1907-9.  VI.  Lichens. — A.  Zahlbruckner  {Kgl. 
Sv.  Vet.-Akad.  Hcmdl,  1917,  15,  No.  6,  1-62).  The  author  indicates 
the  sources  from  which  he  received  the  material  examined — a  few  saxi- 
colous  specimens  from  the  Swedish  Expedition,'  1901-3 ;  P.  Dusen'e 
collection  under  Nordenskjold  ;  also  those  collected  by  Skottsberg  in 
the  1907-9  Expedition.  He  describes  a  large  number  of  species,  new 
and  old ;  and  he  gives  a  tabulated  list  of  all  the  lichens  from  the  Falk- 
land Islands.  A.  L.  S. 

Lichens  from  the  Neighbourhood  of  Hamburg. — J.  Erichsen 
{Verk.  Naturw.  Ver.  Hamburg,  1917,  24,  65-100  ;  see  also  Ann.  My  col., 
1917,  15,  509).  A  description  of  the  more  unusual  lichens.  A  large 
number  are  new  to  the  district.  The  author  has  given  a  full  account 
of  the  species,  with  full  biological  details.  A.  L.  S. 

Lichens  of  Dune  Rubble  at  Pelzerhaken.— J.  Erichsen  {Allgem. 
Bot.  Zeitschr.,  1916,  21,  79-85  and  138-16  ;  see  also  Ann.  Mijcol,  1917, 
15,  508-9).  The  dunes  examined  are  in  Holstein.  Most  of  the  lichens 
collected  were  dark-coloured  forms,  and  were  characterized  by  minute 
apothecia  and  spores.     Degenerate  thalli  were  fairly  frequent.    A.  L.  S. 

Research  on  Lichens  in  Polarized  Light.  —  L.  Santha  {Bot. 
Kozlem&nyek,  1916,  15,  99-101  and  31-2  ;  see  also  Ann,  Mycol.,  1917, 
15,  510-11).  The  author  has  examined  sections  of  the  thallus  of 
various  Physciae  under  polarized  light.  He  finds  curious  differences 
in  the  amount  of  light  transmitted.  Mostly  the  upper  cortex  is  clear ; 
the  other  layers  are  clear  or  dark  according  to  the  group.  He  distin- 
guishes five  types,  of  which  the  last,  the  Obscnra  group,  remains  wholly 
dark.  A.  L.  S. 


101 


PROCEEDINGS    OF    THE    SOCIETY 


AN   ORDINARY  MEETINa 

OF  THE  Society  was  held  at  the  Northampton  Polytechnic 
Institute,  E.G.,  on  Wednesday,  December  17th,  1919,  Mr. 
R.  Paulson,  Vice-President,  in  the  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirmed,  and 
signed  by  the  Chairman. 


The  nomination  papers  were  read  of  five  Candidates  for  Fellowship. 


New  Fellows. — The  following  were  elected  Ordinary  Fellows  of  the 

Society  : — 

Mr.  Bihari  Lai  Bhatia,  M.Sc,  F.Z.S. 

Mr.  Ernest  Roadley  Dovey,  A.R.C.S.,  A.I.C. 

Mr.  Gano  Dunn,  A.I.E.E. 

Mr.  John  Beach  Fleuret. 

Mr.  Norman  Lissimore. 

Mr.  Cecil  Willoughby  Poignand,  M.A.,  R.N. 

Mr.  Ernest  Willie  Rougher,  M.M.A.E. 

Mr.  V.  y.  Ramanan,  M.A.,  Ph.D.,  F.R.A.S.,  F.Z.S.,  etc. 

Mr.  Harry  Watkinson. 

Mr.  James  Ewart  Whipp,  M.P.S. 

Honorary  Fellow.— Mr.  Albert  D.  Michael  (President  of  the  Society 
1893-96)  was  elected  an  Honorary  Fellow. 

Donations  were  reported  from  : — 

Messrs.  H.  F.  Angus  and  Co. — 

Spencer  Lens  Vertical  Illuminator. 
Messrs.  Chapman  and  Hall,  Ltd. — 

"  Bacteriology  and  Mycology  of  Foods  "  (F.  W.  Tanner). 

On  the  motion  of   the   Chairman,   hearty  votes  of   thanks   were 
accorded  to  the  donors. 


Auditors. — Mr.  Hiscott  and  Mr.  Mortimer  were  elected  Auditors  for 
the  ensuing  year. 

It  was  announced  that  the  next  Meeting  of  the  Biological  Section 
would  be  held  on  January  7th,  when  Dr.  J.  A.  Murray  would  read  a 
communication  on  "  The  Manipulation  of  Frozen  Sections  of  Animal 
Tissues." 


102  PROCEEDINGS    OF   THE   SOCIETY. 

The  Meeting  was  held  during  the  Society's 

CONVERSAZIONE 

at  the  Northampton  Polytechnic  Institute,  St.  John  Street,  E.C.I 
(by  kind  permission  of  the  Governing  Body), 

A  Reception  was  held  by  the  President,  Mr.  J.  E.  Barnard,  at 
7.0  p.m. 

General  Exhibits  were  given  by  : — 

M.  A.  Ainslie,  R.N.,  F.R.M.S. — Diatom  structure  under  high- 
power  objective. 

H.  F.  Angus  &  Co. 

Charles  Baker. 

J.  E.  Barnard,  P.R.M.S. — Coloured  Drawings  of  various  micro- 
scopical objects. 

R.  &  J.  Beck,  Ltd. 

M.  Blood,  M.A.,  F.R.M.S. — Brittle  Starfish  illuminated  by  means 
of  a  Lieberkuhn  ;  also  Opal  in  matrix. 

Cambridge  &  Paul  Scientific  Instrument  Co.,  Ltd. — Cambridge 
Reading  Microscope  and  Dissecting  Lens  Stand. 

Prof.  F.  J.  Cheshire,  C.B.E.,  F.R.M.S. 

Prof.  J.  W.  H.  Eyre,  M.D.,  F.R.M.S.— Preparations  of  the 
Influenza  Germ. 

G.  H.  Gabb — An  Instrument  made  about  1760  to  demonstrate 
the  curious  effect  of  bending  the  rays  of  light  by  means  of  a 
prismatic  lens. 

Prof.  R.  T.  Hewlett,  M.D.,  F.R.M.S 

Miss  A.  Hibbert-Ware,  F.L.S. — Braconidse  and  Chalcididae  taken 
from  Aphides  which  they  destroy. 

C.  F.  Hill,  F.R.M.S. — Specimens  of  Iron  and  Steel  prepared  for 
microscopical  examination. 

Miss  G.  Lister,  F.L.S. — Sections  of  leaves  of  grasses. 

Miss  L.  Lyle,  F.L.S. — A  new  species  of  Chantransia. 

J.  Rheinberg,  F.R.M.S. 

E.  J.  Sheppard,  F.R.M.S. — Longitudinal  transverse  section 
through  head  (eye-region)  of  the  Rat  Flea. 

C.  Singer,  M.A.,  M.D.,  F.R.M.S.— Exhibition  of  Pictures  from 

Ancient  Herbals  from  the  11th  to  15th  Centuries. 
T.  J.  Smith,  F.R.M.S.— Shell  of  PUtnorbis  nitidus  (polarized). 
R.  B.  Turner  &  Co. — Stains  and  Microscopical  Re-agents. 
T.  E.  Wallis — Preparations  of  various  objects  (spiders,  insects, 

liverworts)  mounted  in  Amyl-Sandarac. 
W.  Watson  &  Sons,  Ltd. 

F.  Welch — Staining  Bacteria  (demonstration). 

S.  Wycherley,  F.R.M.S.— Monocotyledonous  stem  (Rattan  cane). 

By  the  kindness  of  Dr.  R.  Mullineux  Walmsley,  Principal  of  the 
Northampton  Polytechnic  Institute,  a  Practical  Exhibition  of  Lens 
Grinding  and  Polishing  was  given  by  Students  of  the  Institute. 


PROCEEDINGS    OF   THE    SOCIETY. 


103 


Pond  Life  Exhibits  were  given  by  the  following  Fellows  of  the 
Society  and  Members  of  the  Quekett  Microscopical  Club  : — 


S.  C.  Akehurst.  F.R.M.S. 

E.  R.  Martin. 

W.  H.  L.  Baddeley. 

H.  H.  Mortimer,  F.R.M.S. 

C.  H.  Bestow,  F.R.M.S. 

J.  C.  Myles. 

A.  J.  Bowtell. 

E.  R.  Newmarch. 

N.  E.  Brown. 

J.  M.  Oflford,  F.R.M.S. 

J.  Burton. 

R.  Paulson,  F.R.M.S. 

W.  R.  Chappell. 

E.  A.  Pinchin,  F.R.M.S. 

F.  W.  Chipps. 

F.  J.  W.  Plaskitt,  F.R.M.S 

T.  N.  Cox. 

J.  L.  Ribbons. 

E,  Cuzner,  F.R.M.S. 

J.  Richardson,  F.R.M.S. 

D.  Davies,  F.R.M.S. 

W.  Russell. 

H.  Goullee. 

D.  J.  Scouriield,  F.R.M.S. 

H.  F.  Green. 

R.  S.  W.  Sears,  F.R.M.S. 

J.  Grundy,  F.R.M.S. 

C.  D.  Soar,  F.R.M.S. 

A.  Hardcastle. 

B.  J.  Thomas. 

C.  E.  Heath,  F.R.M.S. 

R.  H.  Thomas. 

T.  H.  Hiscott,  F.R.M.S. 

C.  Tierney,  D.Sc,  F.R.M.S 

J.  T.  Holder. 

C.  Todd. 

C.  H.  Huish,  F.R.M.S. 

W.  R.  Traviss. 

H.  E.  Hurrell,  F.R.M.S. 

C.  Turner. 

J.  J.  Jackson. 

G.  Watts,  L.D.S.,  F.R.M.S. 

H.  H.  Jewell. 

J.  Wilson,  F.R.M.S. 

A.  Morley  Jones. 

C.  L.  Withycombe. 

H.  J.  Lawrence. 

G.  W.  Young,  F.R.M.S. 

J.  Rudd  Leeson,  F.R.^iLS. 

Photomicrographic  Exhibits  were  given  by  the  following  Members 
of  the  Photomicrographic  Society  : — 
'     A.  W.  Aldis — Photomicrographs. 

W.  H.  Baddeley — Microscope  and  objects  (chiefly  diatoms)  and 

accompanying  photomicrographic  prints. 
J.    G.   Bradbury — Microscope   and   objects   and    accompanying 
phctomicrographs  in  colour  and  monochrome  ;  also  a  frame 
of  photomicrographic  transparencies. 
C.  A.  Bunnin — Microscope  and  objects  and  photomicrographs. 

E.  Cuzner^  F.R.M.S. — Photomicrographs  in  colour  and  mono- 
chrome in  a  viewing  frame,  and  stereoscopic  photomicro- 
graphs. 

F.  Martin  Duncan,  F.R.M.S. — Photomicrographic  prints. 

E.  A.  Pinchin,  F.R.M.S. — Photomicrographic  prints  of  diatoms. 

J.  H.  Pledge,  F.R.M.S. — Photomicrographs  and  light  filters,  etc. 

A.  E.  Smith — Microscopes  and  objects,  and  accompanying  photo- 
micrographs ;  also  stereoscopic  photomicrographs. 

H.  C.  Whitfield  and  W.  R.  Biss — Photomicrogra'^hic  apparatus, 
with  microscopic  objects  projected  in  a  photomicrographic 
camera. 

During   the  evening  Selections  on   the  Organ  were  given  by  Mr. 
Seymour  Dicker. 


104  PROCEEDINGS    OF    THE    SOCIETY. 


THE    SYMPOSIUM. 

The  JloYAL  Microscopical  Society,  the  Faraday  Society,  the 
Optical  Society,  aud  the  Photomicrocraphic  Society  in  co-opera- 
tion with  the  Technical  Optics  Committee  of  the  British  Science 
Guild,  meeting  in  joint  session,  held  a  Symposium  and  G-eneral 
Discussion  on 

*'THE   MICROSCOPE:    ITS    DESIGN,    CONSTRUCTION 
AND    APPLICATIONS," 

on  Wednesday,  January  14th,  1920,  by  kind  permission  of  the  Royal 
Society  in  its  Rooms  at  Burlington  House,  W.l. 

The  meeting  extended  over  two  sessions  :  from  4.15  to  6.30,  and 
from  8.15  to  10.30  p.m.  During  the  afternoon  preceding  the  meeting 
an  Exhibition  was  held  illustrating  recent  developments  in  the  Science 
of  Microscopy  and  the  latest  applications  of  the  Microscope  in  various 
branches  of  industry.  There  was  an  attendance  of  not  far  short  of  one 
thousand.  The  proceedings  were  of  an  enthusiastic  nature,  and  the 
Exhibition  was  probably  the  most  important  ever  held  on  this  subject. 

'  Sir  Robert  Hadfield,  Bart.,  D.Sc,  D.Met.,  F.R.S.,  President  of 
the  Faraday  Society,  presided  over  the  Discussion,  and  delivered  an 
Introductory  Address. 

The  Chairman  opened  with  a  brief  history  of  the  Societies  taking 
part  in  the  Symposium,  and  explained  how  the  question  of  such  a 
Symposium  first  arose.  He  pointed  out  the  unenviable  position  of  the 
British  Optical  Industry  at  the  outbreak  of  war  and  the  necessity  of 
ensuring  that  such  a  condition  of  affairs  should  never  recur.  He  then 
gave  a  short  history  of  the  microscope  from  ancient  times  up  to  the 
present  day,  touching  on  the  work  of  those  who  have  contributed  to 
the  development  of  tliis  powerful  instrument  of  research.  Subsequently 
he  dealt  with  the  application  of  the  microscope  to  modern  metallurgy, 
emphasizing  some  of  the  subsidiary  points  which  must  be  attended  to 
for  complete  success.  In  addition,  he  dealt  with  certain  aspects  of 
crystallography,  and  with  the  ultra-microscope,  two  subjects  which  are 
intimately  related  to  the  work  of  the  modern  microscopist.  An  adden- 
dum to  his  Address  consists  of  a  short  Bibliography  of  some  of  the 
most  important  work  relating  to  microscopy  and  metallography.  The 
printed  Address  is  accompanied  by  many  plates  and  figures,  including 
portraits  of  Sor])y  and  Dallinger. 

Mr.  J.  E.  Barnard,  President  of  the  Royal  Microscopical  Society, 
delivered  an  address  in  which  he  indicated  future  lines  of  development 
in  microscope  design  and  in  microscopy. 

The  address  considered  the  microscope  chiefly  as  used  in  biological 
research.     The  modern  microscope  ^as  mechanically  far  more  unstable 


PROCEEDINGS    OF    TUE    SOCIETY.  105 

than  it  was  fifty  years  ago,  and  they  must  aim  at  producing  a  stable 
optical  bar  with  all  parts  adjustable  and  removable. 

The  question  of  resolving  power  was  considered,  and  its  relation  to 
the  wave-length  of  the  light.  Limits  of  visibility  were  much  extended 
with  a  bright  object  against  a  darker  ground,  and  the  use  of  invisible 
radiation  of  small  wave-length,  perhaps  even  soft  X-rays,  would  extend 
the  limits  of  resolution. 

Mr.  F.  Martin  Duncan,  F.R.M.S.,  F.R.P.S.,  F.Z.S.,  President  of 
the  Photomicrographic  Society,  gave  a  resume  of  his  paper,  "Some 
Notes  on  the  History  and  Design  of  Photomicrographic  Apparatus," 
drawing  special  attention  to  the  following  points  : — 

The  discovery  of  photography  was  due  to  British  and  French 
scientists,  and  the  first  to  apply  successfully  photography  to  the  record- 
ing of  microscopic  objects  were  Fox-Talbotin  England  (1835),  Daguerre 
in  France,  and  Draper  in  America.  Since  that  date  all  the  important 
advances  and  discoveries  in  photography  had  been  made  by  scientific 
workers  in  those  three  countries.  He  drew  particular  attention  to  the 
admirable  design  of  photomicrographic  apparatus  by  British  manufac- 
turers in  pre-war  days,  and  to  the  superiority  of  the  best  British  micro- 
scope stand  for  accurate  research  work  and  photomicrography. 

Sir  Herbert  Jackson,  K.B.E.,  F.R.S.,  emphasized  the  objects  of 
the  Symposium,  which  were  to  consider  methods  of  promoting  the 
science  of  microscopy,  developing  and  improving  the  instruments,  and 
extending  their  use  in  science,  industry  and  education. 

Beginning  with  the  subject  of  glass,  he  said  that  while  our  makers 
could  equal  the  best  obtained  from  abroad,  new  glasses  were  needed 
with  optical  constants  different  from  those  at  present  known  if  new 
and  improved  optical  combinations  were  to  be  achieved. 

Mathematical  investigations  in  the  design  of  lenses  and  optical 
systems  were  in  progress,  and  they  foreshadowed  important  develop- 
ments, but  much  experimental  work  would  be  necessary. 

The  growing  use  of  the  microscope  in  industry  called  for  systematic 
education  in  theory  and  practice.  He  drew  attention  to  the  new  School 
of  Technical  Optics  at  South  Kensington,  and  pleaded  for  support  and 
encouragement.  Lack  of  knowledge  often  led  to  wrong  interpretation  of 
results  and  to  the  consequent  neglect  of  the  instrument.  Training,  such 
as  was  given  in  spectroscopy,  was  essential,  and  he  outlined  the  kind  of 
course  he  had  in  mind,  an  important  feature  of  which  was  the  study 
of  the  use  of  the  microscope  under  all  conditions  of  illumination  and 
powers. 

Professor  F.  J.  Cheshire,  C.B.E.,  President  of  the  Optical  Society, 
followed  with  a  paper  on  "The  Mechanical  Design  of  Microscopes." 

He  showed  how  the  microscope  was  the  keystone  of  the  arch  of  a 
key  industry,  and  therefore  its  manufacture  must  be  in  a  healthy  and 
thriving  condition.  To  efiFect  this  "  mass  production  "  must  follow  the 
stage  of  "  artistic  production,"  depending  on  extraordinary  personal 
skill.  It  must  meet  the  demands  of  the  manufacturer  as  well  as  of  the 
user,  and  therefore  be  made  cheaply  as  well  as  accurately.     This  called 


106  PROCEEDINGS    OF   THE    SOCIETY. 

for  specialisation,  standardisation  and  repetition  production,  but  design 
came  first.  A  thorough  overhaul  of  design  without  reference  to  tradi- 
tional designs  must  lead  to  startling  results. 

Dr.  Charles  Singer,  F.R.M.S.,  contributed  a  paper  in  which  he 
outlined  "  The  Earliest  Steps  in  the  Invention  of  the  Microscope." 

The  author  dwelt  not  on  the  well-known  work  of  the  classical 
observers  Leeuwenhoek  and  his  successors,  but  he  reverted  to  the 
earliest  stages  in  the  discovery  of  the  microscope,  beginning  with  the 
work  of  Euclid,  and  passing  through  that  of  Ptolemy  and  Alhazen  to 
Roger  Bacon,  who  was  truly  the  father  of  microscopy.  Jansen  of 
Middle  burg  is  usually  regarded  as  the  first  to  construct  an  actual  micro- 
scope, with  Lippershey  of  Wesel  as  a  rival,  but  Galileo  was  the  first 
effective  discoverer  of  the  microscope  as  of  the  telescope. 

Professor  Alfred  W.  Porter,  D.Sc,  F.R.S.,  spoke  on  "  The 
Resolving  Power  of  the  Microscope." 

The  paper  consists  in  part  of  a  brief  historical  summary.  Emphasis 
is  laid  on  the  entrance  of  the  human  element  into  the  question  of 
resolving  power.  It  is  the  "  thing  seen  "  with  what  we  have  to  do  ; 
and  no  two  people  can  see  precisely  alike.  Nor  can  any  unique  limit  be 
fixed  applying  indifferently  to  various  shapes  of  object  and  various 
modes  of  illumination.  Under  best  conditions  two  lines  will  not  be 
resolved  by  a  dry  objective  unless  they  are  more  than  half  of  a  wave- 
length apart.  Even  then  they  will  not  be  seen  as  separate  unless  the 
magnification  reaches  such  a  value  that  the  ultimate  image  subtends  at 
the  eye  an  angle  greater  than  two  minutes'  of  arc  ;  and  if  it  is  desired 
to  detect  their  separation  with  ease,  an  angle  considerably  greater  than 
this  is  desirable. 

More  attention  should  be  paid  to  the  size  of  the  Ramsden  circle  (the 
bright  spot),  which  is  small  in  most  microscopic  cases.  The  image 
probably  begins  to  deteriorate  in  quality,  owing  to  the  reduction  in  the 
beam  entering  the  eye,  when  the  total  magnification  with  a  one- twelfth 
is  about  300.  The  eye,  however,  is  a  fairly  long-suffering  organ.  In 
the  paper  it  is  throughout  assumed  that  the  optical  system  is  perfect 
from  the  point  of  view  of  geometrical  optics.  This  is  never  the  case  ; 
and  improvements  in  this  respect  must  be  made  pari  passu  with  increase 
in  numerical  aperture. 

Professor  A.  E.  Conrady  contributed  some  "  Notes  on  Microscopical 
Optics,"  which  were  communicated  by  Professor  A.  W.  Porter.     - 

The  paper  deals  vj'idi  the  points  in  which  the  actual  construction  of 
a  lens  may  be  improved.  The-defects  considered  are  spherical  and 
chromatic  aberration,  the  secondary  spectrum  (which  requires  fluorite 
glasses  for  its  correction),  and  curvature  of  the  field.  It  is  indicated 
how  it  may  be  possible  to  combine  moderate  curvature  of  field  with 
apochromatic  perfection  and  thus  remove  the  outstanding  defect  of  the 
best  objectives.  Defects  in  condensers  are  also  discussed  and  remedies 
suggested. 


PKOCEEDINGS   OF   THE    SOCIETY.  107 

The  author  is  of  opinion  that  advances  in  numerical  aperture  offer 
little  attraction.  Abbe  carried  the  N. A.  too  far,  and  no  notable  discovery 
had  been  achieved  with  his  monobromide-immersion  objectives  of  N.A. 
1*60.  The  rise  in  ultra-violet  light  was  more  promising,  but  the 
technical  difficulties  and  limitations  were  great. 

Dr.  R.  MuLLiNEUX  Walmsley,  Chairman  of  the  Technical  Optics 
Committee  of  the  British  Science  Guild,  outlined  the  work  of  that 
Committee. 

The  first  step  taken  was  the  Conference  held  in  1915,  as  a  result 
of  which  three  specifications  were  drawn  up,  one  for  a  pathological 
microscope,  another  for  a  student's,  and  a  third  for  a  metallurgical 
microscope.  These  specifications  were  published  in  1916,  and  amended 
specifications  are  now  about  to  be  issued. 

Mr.  Conrad  Beck,  C.B.E.,  F.R.M.S.,  read  a  paper  describing  "A 
Standard  Microscope,"  which  his  firm  was  making,  to  fulfil  the  require- 
ments of  the  British  Science  Guild  Specification. 

The  form  and  dimensions  of  the  microscope  are  described  in  detail 
in  the  paper.  The  novel  features  include  the  fine  adjustment,  a  new 
object  glass  changer  possessing  many  advantages  over  a  revolving  nose- 
piece,  and  a  new  micrometer  eyepiece  and  system  of  measurement. 

A  supplementary  paper  emphasized  the  necessity  for  research  on 
the  use  of  the  microscope.  The  search  for  an  illuminator  by  which 
much  larger  angles  could  be  used  in  the  object  glass,  and  a  method  of 
illumination  which  would  modify  the  diffraction-images,  seen  for 
example  when  micro-organisms  were  examined  by  dark-ground  illumina- 
tion, were  cited  as  instances  of  such  researches.  Other  examples  were 
the  relation  between  resolution  and  the  increase  of  brilliancy  induced 
by  wide  apertures  in  the  condenser,  and  in  metallurgical  work  a  means 
of  illumination  to  eliminate  flaw  and  ghost  images. 

Mr.  F.  Watson  Baker,  F.R.M.S.,  spoke  on  "  Progress  in  Micro- 
scopy from  a  Manufacturer's  Point  of  View." 

So  long  as  thirty- eight  years  ago  microscopes  were  made  in  this 
country  which  anticipated  the  requirements  of  to-day,  and  when  apochro- 
matic  objectives  were  first  introduced  the  only  microscope  which  allowed 
of  the  full  advantage  being  taken  of  the  optical  qualities  was  the  British 
instrument.  British  makers  had  always  excelled  in  the  making  of 
microscopes  of  high  class,  involving  skilled  hand  work. 

The  hand-workers  of  the  past  had,  however,  become  reduced  by 
dispersion  and  death,  and  partly  on  this  account,  and  in  order  to  reduce 
the  present  heavy  costs,  steps  had  been  taken  to  produce  microscopes 
by  means  of  machine  tools,  and  such  instruments  would  be  available 
in  the  near  future. 

Mr.  Powell  Swift  read  a  paper  on  "A  New  Research  Microscope," 
which  described  a  model  shown  embodying  the  results  of  consultations 
held  between  makers  and  users. 


108  PROCEEDINGS   OF   THE    SOCIETY. 

The  special  points  considered  are  rigidity  ;  diameter  of  body,  which 
is  2  inches,  enabling  a  photographic  lens  placed  in  its  interior  to  cover 
a  large  field  ;  and  the  novel  construction  of  the  substage,  which  is  of 
great  advantage  for  physical  research,  as  it  enables  special  apparatus 
to  be  introduced  and  produce,  as  occasion  may  require,  a  most  perfect 
optical  bench  for  general  experimental  work.  There  is  a  considerable 
class  of  delicate  optical  research  which  calls  for  an  optical  bench  possess- 
ing the  perfect  adjustments  of  a  microscope,  and  hitherto  this  require- 
ment has  not  been  met.  Almost  any  class  of  apparatus  could  be  applied 
to  the  stand  for  making  small  and  accurate  measurements  in  physics, 
and  although  the  chief  object  of  this  instrument  is  to  provide  the  most 
perfect  microscope  that  can  be  required,  the  other  function  for  such  an 
instrument  has  been  borne  in  mind. 

The  Chairman  having  invited  discussion  on  the  three  papers  first 
presented  : — 

Mr.  J.  E.  Barnard  announced  that  at  the  suggestion  of  some  of 
the  makers  a  small  standing  committee  would  be  appointed,  consisting 
of  the  Presidents  of  the  Societies  meeting  that  evening  and  one  or  two 
others,  to  test  the  apochromatic  objectives  now  being  manufactured  by 
English  firms. 

Dr.  R.  MuLLiNEUX  Walmsley  said  that  to  enable  microscopes  to 
be  successfully  produced  in  large  quantities  called  for  thoroughly  trained 
men  in  the  inspection  room  of  the  factory.  The  educational  aspect  was 
therefore  all-important. 

Lieut.-Col.  GiFFORD  criticised  existing  apochromatic  objectives  on 
the  ground  that  they  were  mostly  not  truly  apochromatic. 

Instructor-Commander  Ainslie  spoke  on  apochromatic  objectives 
from  the  point  of  view  of  resolution.  While  the  best  English  lenses  he 
had  used  were  of  superlative  excellence,  he  urged  the  necessity  for  a  far 
higher  average  of  excellence  than  was  the  case  at  present. 

Dr.  E.  C.  BousFiELD  also  spoke  on  apochromatic  lenses  and  the 
conditions  required  for  making  them  perfect  and  lasting.  A  fault 
difficult  to  obviate  was  roundness  of  field.  He  described  a  better 
distance  focusing  arrangement  for  photomicrograph ic  work  than  that 
usually  employed. 

Dr.  W.  RosENHALN,  F.R.S.,  pointed  out  that  it  was  important  to 
distinguish  between  mass  production  of  a  standard  microscope  and  the 
progress  of  the  microscope  as  an  instrument  of  research  and  precision. 

Mr.  Arthur  Banfield,  in  a  written  communication,  suggested 
possible  improvements  in  the  microscope  as  a  result  of  his  experience. 

The  following  papers  were  presented  and  taken  as  read  : — 

"  Notes  on  the  Future  of  the  Microscope,"  by  M.  Eugene  Schneider. 

{a)  Mechanical  Improvements. — A  universal  screw  is  suggested  for 
the  tubes  in  which  eyepieces  and  condensers  slide. 

{h)  Optical  Improvements. — We  are  restricted,  at  least  in  usual 
practice,  by  the  impossibility  of  going  beyond  the  numerical  aperture 
of  1-40.     Better  correction  of  the  aberrations  and  especially  of  the  field 


PROCEEDINGS    OF   THE    SOCIETY.  109 

curvature  seem  only  to  be  possible  by  the  creation  of  new  optical  materials. 
The  use  of  nltra-violet  rays  admits  of  increasing  the  definition  to  a 
considerable  degree  ;  but  the  insufficient  transparency  of  media  fre- 
quently imposes  a  limit. 

"  A  New  Microscope  Illuminator,"  by  Mr.  Alexander  Silverman. 

The  illuminator  described  is  largely  used  in  America.  It  is  claimed 
to  show  greater  detail  than  older  forms  when  examining  opaque  objects, 
sucJi  as  metals,  and  it  is  of  special  value  for  papers,  textiles,  etc.,  which 
are  invisible  under  vertical  light. 

"  Some  Problems  in  High  Power  Photomicrography,"  by  Dr.  R.  E. 
Slade,  F.I.C,  and  Mr.  G.  I.  Higson,  M.Sc. 

The  paper  describes  devices  to  ensure  the  greatest  possible  resolving 
power  in  examining  photographic  emulsions.  The  source  of  light  is  a 
"  Pointolite  "  lamp.  No  optical  system — merely  a  colour  screen  for 
reasons  explained — is  interposed  between  the  lamp  and  the  condenser. 
A  vibrationless  shutter  operates  in  front  of  the  eyepiece  of  the  micro- 
scope ;  no  camera  is  employed. 

Mr.  R.  J.  E.  Hanson,  F.R.C.S.,  contributed  a  paper  on  "  Fatigue 
Factors  Incidental  in  the  Use  of  Certain  Optical  Instruments,"  which 
was  taken  as  read. 

Defects  in  or  moisture  of  the  muscular  mechanism  of  eye-movement 
are  considered,  as  they  concern  the  microscopic  observer.  A  head-piece 
is  described  which  obviates  fatigue,  which  can  be  attached  to  any  standard 
microscope. 

A  group  of  papers  dealt  with  the  subject  of  "  Glass  for  Optical 
Purposes." 

Dr.  Morris  W.  Travers,  F.R.S.,  referred  to  the  work  done  in 
America  in  1917,  when  a  sudden  demand  arose  for  an  enormous  supply 
of  optical  glass.  No  information  existing  in  this  country  was  obtainable 
on  that  occasion,  but  by  June  1918  a  group  of  twenty  scientific  men 
'  from  the  Geophysical  Laboratory  and  the  Bureau  of  Standards  co- 
operating with  the  industry  succeeded,  after  two  months'  concentrated 
effort,  in  producing  the  quantities  required  and  in  qualities  that  seldom 
called  for  rejections.  He  deprecated  the  Government  policy  in  this 
country  of  attempting  to  monopolise  science. 

Dr.  W.  E.  S.  Turner  dwelt  on  the  difficulties  involved  in  making 
optical  glass,  the  demand  for  which  was  so  small,  and  he  suggested 
remedies  for  meeting  them.  He  considered  England  could  supply  all 
her  own  needs,  and  he  thought  America  behind  this  country  in  output 
and  variety  ;  indeed,  there  was  a  market  for  glass  made  here. 

He  forwarded  to  the  meeting  a  beautiful  specimen  of  a  crystal  of 
calcium  fluoride  from  Johannesburg. 

Mr.  Robert  Mond  read  a  note  relating  to  the  occurrence  of  fluorite 
in  Canada,  and  he  submitted  a  specimen  from  the  one  deposit  that 
showed  any  promise.  A  lens  would  be  cut  from  it  to  test  its  optical 
properties. 


110  PROCEEDINGS    OF    THE    SOCIETY. 

Mr.  F.  TwYMAN  read  a  paper  on  "  The  Annealing  of  Glass." 
Badly  annealed  glass  meant  the  presence  of   internal  stress.     The 
annealing  range  of  temperature  is  the  limited  intermediate  one  during 
which  stresses  take  some  little  time  to  die  out,  and  an  accurate  know- 
ledge of  the  mechanical  properties  of  glass  in  this  region  is  necessary. 

The  remaining  papers  and  communications  dealt  with  various  appli- 
cations of  the  microscope. 

Dr.  J.  W.  Evans,  F.R.S.,  spoke  on  "  The  Requirements  of  the  Petro- 
logical  Microscope." 

Besides  having  the  functions  of  an  ordinary  microscope,  the  petro- 
logical  microscope  had  to  identify  crystals  by  the  action  of  light  upon 
them.    The  provisions  specially  designed  for  this  purpose  were  described. 

Mr.  A.  Chaston  Chapman,  F.I.C,  spoke  on  "The  Application  of 
the  Microscope  to  the  Selection  and  Control  of  Yeast  employed  for 
Brewing  Purposes." 

It  is  possible  to  detect  the  contamination  of  the  pitching  yeast  of 
the  brewery  with  bacteria  and  undesirable  yeast  species  and  to  take  the 
necessary  steps  to  purify  it. 

Lantern  slides  were  shown  illustrating  this  fact. 

Dr.  R.  S.  Willows,  M.A.,  presented  a  paper  describing  "The 
Microscopic  Outfit  of  a  Textile  Research  Laboratory." 

It  is  pointed  out  that  the  design  of  a  microscopic  outfit  for  research 
on  textiles  has  not  yet  received  due  attention.  Attention  is  particularly 
directed  to  the  importance  of  considering  more  fully  the  mechanical  design 
of  the  photographic  apparatus,  so  as  to  lessen  the  effects  of  vibration  ; 
the  provision  of  a  simple  method  of  changing  from  transmitted  to 
vertical  illumination  and  of  a  reflecting  device  to  enable  a  vertical 
microscope  to  be  used  with  a  horizontal  camera,  in  cases  where  the 
effect  of  solutions  is  being  followed. 

The  next  group  of  papers  dealt  with  the  use  of  the  microscope  in 
metallography. 

A  paper  by  Sir  Robert  Hadfield,  Bart.,  on  "  The  Great  Work  of 
Sorby  of  Sheffield,"  introduced  the  subject. 

The  late  Dr.  Sorby,  the  founder  of  the  science  of  metallography, 
first  worked  as  a  geologist  on  transparent  rock  sections,  but  he  sub- 
sequently realized  the  immense  advantage  of  the  application  of  the 
microscope  to  the  structure  of  metals,  his  first  paper  on  this  subject 
being  read  in  1864.  His  earlier  work  was  for  some  years  neglected, 
but  in  view  of  the  immense  strides  which  were  subsequently  made  in 
the  science  of  metallurgy,  the  microscope,  in  the  hands  of  such  men  as 
Martens,  Osmond  and  le  Chatelier,  became  one  of  the  most  powerful 
instruments  of  research.  To  Sorby,  however,  belongs  the  credit  of 
having  first  evolved  the  microscope  method  ;  it  was  his  discovery  of 
the  means  whereby  the  structure  of  a  metal  can  be  laid  bare  that  gives 
him  the  ri<{ht  to  this  title. 

Dr.  W.  Rosenhain,  F.R.S.,  read  a  paper  on  "The  Metallurgical 
Microscope." 

The  principal  requirements  of  the  metallurgical  microscope  are  sum- 


PROCEEDINGS  OF   THE   SOCIETY.  Ill 

marized.  Rigidity  is  essential.  It  is  shown  how  the  instrument  can 
be  designed  on  the  basis  of  a  machine  tool,  Large  working  distance 
between  stage  and  objectives  and  freedom  of  movement  for  the  specimen 
are  important. 

The  optical  requirements  are  those  common  to  all  the  most  exacting 
microscopic  work,  but  ever-increasing  demands  are  being  made  on 
resolving  power,  since  metallurgical  progress  tends  to  the  production 
of  material  of  extremely  minute  niicrostructure. 

The  accessories  are  of  some  importance,  particularly  the  illuminator. 
For  visual  purposes  a  source  of  light  behind  ground  glass  or  opal  is 
recommended,  no  lenses  or  condensers  being  necessary.  A  suitable 
arrangement  is  described. 

The  author  finally  describes  his  optical  levelling  apppliance  for 
mounting  specimens  with  their  surfaces  at  right  angles  to  the  optic  axis. 

Dr.  Rosenhain,  in  the  course  of  the  discussion,  pointed  out  that 
one  method  of  getting  higher  resolving  power  was  to  use  a  front  glass 
of  higher  refractive  index  than  was  at  present  obtainable.  It  was 
doubtful  whether  a  satisfactory  and  lasting  glass  could  be  found,  but 
he  thought  the  solution  lay  in  finding  or  perhaps  growing  artificially  a 
crystalline  substance. 

Professor  Cecil  H.  Desch,  D.Sc,  contributed  some  "Notes  on 
the  Construction  and  Design  of  Metallurgical  Microscopes." 

The  author  begins  with  some  criticistns  of  the  existing  types  of 
instrument,  which,  while  well  designed  mechanically,  do  not  wear  satis- 
factorily. He  proceeds  to  discuss  in  some  detail  the  principal  parts  of 
the  instrument. 

The  Stand. — A  heavy  horseshoe  foot  is  recommended  on  the  whole ; 
other  forms  are  useful  for  special  purposes.  The  Le  Chatelier  inverted 
stand  is  pronounced  flimsy  and  needing  better  design,  because  specimens 
are  quickly  examined  in  it. 

For  larger  instruments  used  for  photography  the  ordinary  design 
might  be  completely  departed  from  and  a  type  of  optical  bench  devised. 

Adjustments. — All  racks  and  screws  should  be  cut  in  hard,  incor- 
rodible metals  or  alloys,  adopting  engineering  methods. 

The  Body  Tiihe  should  be  short  and  of  wide  diameter. 

The  Stage. — A  rack-work  focusing  movement  should  be  provided. 
Levelling  stages  are  a  nuisance  ;  specimens  should  be  levelled  in  other 
ways.     Mechanical  movement  is  essential  and  rotation  desirable. 

The  Vertical  Illuminator. — The  Beck  or  transparent  illuminator  is 
the  only  suitable  form  for  high  powers. 

The  Objectives. — Apochromatics  are  deficient  in  flatness  of  field,  and 
the  author  questions  whether  good  achromats  are  not  to  be  preferred 
for  photographic  purposes,  especially  with  the  almost  monochromatic 
colour  screens  now  in  use. 

Mr.  J.  H.  G.  MoNYPENNY  contributed  "  Some  Notes  on  the  Metal- 
lurgical Photomicroscope." 

The  first  part  of  the  paper  emphasizes  the  importance  of  the  illumi- 
nation in  the  production  of  a  photomicrograph,  outlines  the  conditions 
necessary  for  obtaining  good  illumination,  and  gives   descriptions  of 


112  PROCEEDINGS   OF   THE   SOCIETY. 

arrangements  of  condensers  which  fulfil  these  conditions.  In  connexion 
with  the  vertical  illuminator,  while  the  disc  pattern  is  held  to  be 
superior  to  the  prism,  the  faults  of  individual  discs  (owing  to  the  un- 
suitable nature  of  the  reflector)  are  pointed  out.  The  influence  of  the 
curvature  of  the  back  combination  of  the  objective  on  the  production  of 
flare  is  dealt  with,  and  the  differences  found  in  achromats  and  apo- 
chromats  mentioned.  After  a  general  discussion  on  the  use  of  colour 
screens,  the  relationship  of  aperture  and  magnification  and  possible 
future  developments  in  objectives  for  metallurgical  work,  the  paper 
gives  a  description  of  apparatus  specially  designed  for  obtaining  low- 
power  photomicrographs  embracing  a  large  field  of  view.  Some  typical 
results  obtained  are  included. 

Mr.  Leslie  Aitchison,  D.Met.,  B.Sc,  A.I.C.,  and  Mr.  F. 
Atkinson  read  a  paper  on  "  Metallurgical  Microscopes  and  their 
Development." 

This  paper  is  written  from  the  point  of  view  of  the  working  metal- 
lurgist to  whom  the  microscope  is  of  constant  value  and  usefulness  ;  no 
attempt  is  made  to  discuss  the  subject  from  the  optician's  point  of  view. 

Sir  Egbert  Hadfield,  Bart.,  D.Sc,  D.Met.,  F.R.S.,  and  Mr. 
T.  G.  Elliott,  F.I.C,  F.R.M.S.,  presented  a  paper  entitled  "  Photo- 
micrographs of  Steel  and  Iron  Sections  at  High  Magnifications." 

Further  progress  in  metallography  depends  essentially  on  the  use  of 
more  powerful  microscopes  giving  higher  magnifications  allied  with 
increased  resolving  power.  To  this  end  the  authors  have  carried  out  an 
extensive  research  on  steel  and  iron  sections  up  to  a  magnification  of 
8,000  diameters.  The  paper  is  accompanied  by  eight  plates  containing 
twenty-six  photomicrographs,  the  first  two  being  selected  from  one  of 
Sorby's  earlier  papers  at  nine  magnifications,  the  remainder  being 
obtained  by  the  authors  under  various  conditions  at  magnifications  from 
100  to  8,000.  The  type  of  apparatus  required  is  dealt  with  and  also 
the  precautions  necessary  for  exacting  work  of  this  nature,  and  it  is 
shown  in  what  directions  further  progress  is  to  be  anticipated. 

Mr.  F.  C.  Thompson,  D.Met.,  B.Sc,  contributed  a  paper  on  "  The 
High-Power  Photomicrography  of  Metals." 

The  paper  aims  chiefly  at  emphasizing  the  predominating  importance 
of  adequate  resolving  power  for  high  magnifications.  Starting  with  the 
fact  that  it  is  impossible  to  produce  a  microscopical  rendering  of  a  point 

other  than  as  a  disc,  the  diameter  of  which  =  ,  where  7n  is  the 

magnification,  A.  the  -^ave-length  of  light  used,  and  N.A.  the  numerical 
aperture  of  the  objective,  it  is  shown  how  sorbite  may  become  apparently 
laminated  and  how  pearlite  or  sorbite  may  lose  their  structure,  becoming 
apparently  troostitic.  The  probable  value  of  the  use  of  ultra-violet 
"  light "  and  silica  lenses  is  pointed  out.  The  "  Davon  "  super-micro- 
scope is  considered  at  some  length,  the  conclusion  arrived  at  being  that 
whatever  may  be  its  merits  in  other  directions  it  possesses  little  or  no 
value  for  high-power  photo-micrography  as  a  result  of  the  altogether 
inadequate  resolving  power. 


PKOCEEDINGS    OF    THE    SOCIETY.  113 

Mr.  Henry  M.  Sayers  spoke  on  "  lilumination  in  Micro-Metal- 
lography." 

A  full  discussion  of  the  subject  of  illumination  is  entered  into.  The 
author  concludes  that  improvement  is  desirable  in  the  following  items  : — 

1.  A  transparent  vertical  illuminator  reflector  which  shall  get  nearer 
the  theoretical  perfection  of  reflecting  50  p.c.  and  transmitting  50  p.c 
of  the  light  incident  on  it  at  45°  without  much  coloration  of  the 
transmitted  light.  An  optically  worked  glass  lightly  platinised  seems 
the  most  promising. 

2.  A  source  of  light  of  uniform  and  steady  high  brilliancy  presenting 
an  area  of  about  half  an  inch  square,  to  which  a  condenser  of  2  in. 
working  distance  can  be  focused  without  damage  from  radiant  heat. 
Either  the  "  Pointolite  "  or  the  "  half -watt "  metal  filament  lamp  may 
be  able  to  meet  this.     The  limitation  of  bulb  size  is  important. 

3.  Oil  immersion  objectives  intermediate  in  focal  length  and  aperture 
between  the  f  in.  and  the  jV  in.,  well-corrected  for  colour.  If  any- 
thing can  be  done  by  computation  to  reduce  glare  by  reflection  from  the 
lens  surface  in  objectives  designed  for  metallography  it  will  be  an 
advantage. 

4.  An  auxiliary  condenser  combination  with  a  long  working  distance 
compared  with  its  focal  length,  to  be  used  to  present  a  magnified  virtual 
image  of  the  radiant  to  the  objective. 

5.  A  simple,  firm  optical  bench  or  geometric  slide  arrangement 
with  carriers  for  lamp  and  condenser  at  heights  corresponding  to  those 
of  usual  microscopic  axes  when  horizontal  or  vertical,  to  suit  both 
positions. 

Mr.  Samuel  Whyte,  B.Sc,  read  a  paper  on  "The  Use  of  the 
Microscope  in  Engineering  Works." 

The  microscope  is  of  great  practical  use  in  controlling  steel  supplies 
and  their  heat-treatment.     Its  uses  are  briefly  that  of  : — 

1.  Examination  of  raw  materials,  such  as  bars  and  especially  small 

stampings  for  segregations  and  "  laps  "  of  oxide. 

2.  An  aid  to  arriving  at  the  best  heat-treatment,  especially  for  high- 

speed steels. 

3.  A  means  of  detecting  causes  of  failures,  helping  to  work  out  the 

processes  by  which  failures  occur. 

Professor  H.  Le  Chatelier,  in  a  communication,  suggested  some 
"  Improvements  in  Metallurgical  Microscopes." 

It  would  be  an  advantage  to  tvj  and  obtain  good  photomicrographs 
with  objectives  corrected  only  for  a  single  wave-length,  say  the  highly 
actinic  blue  line  of  the  mercury  vapour  lamp,  instead  of  using  costly 
apochromatics. 

Great  errors  frequently  arise  from  the  ignorance  of  observers.  Thus 
it  is  forgotten  that  every  objective  is  intended  to  give  an  image  at  a 
fixed  point.  Another  mistaken  procedure  is  to  reflect  the  luminous 
pencil  by  a  total  reflection  prism,  instead  of  by  a  mirror,  forgetting  that 
the  objective  is  calculated  for  working  in  air,  not  glass. 

I 


114  PROCEEDINGS    OF   THE    SOCIETY. 

Professor  Cael  Benedicks  and  Mr.  Erik  Walldow  sent  in  a 
paper  entitled,  "  Some  Points  Concerning  Sharpness  in  High  Magnifica- 
tion Micrographs." 

The  investigations  were  started  as  a  detailed  and  critical  examination 
of  the  new  Reichert  microscope,  which  is  of  the  Le  Chatelier  type.  It 
was  found  to  produce  excellent  results  at  the  very  highest  magnifications. 

A  note  received  from  Professor  F.  Giolitti  (Turin)  suggested  some 
*'  Alterations  in  the  Design  of  the  Le  Chatelier  Metallurgical  Micro- 
scope." 

The  author  considers  this  instrument  preferable  to  other  similar  types 
on  the  market,  but  two  disadvantages  should  be  removed  ;  one  is  the 
sagging  of  the  rack  due  to  the  weight  of  the  stage,  and  the  second 
is  the  absence  of  an  apparatus  for  easily  and  rapidly  changing  the 
objective.  An  instrument  is  described  which,  while  preserving  the 
principle  of  vertical  observation,  embodies  these  improvements.  The 
instrument  can  support  on  the  stage  several  kilogrammes  without  causing 
distortion.  The  fine  focusing  is  effected  by  manipulating  not  the  stage, 
but  the  eyepiece  tubes. 

Mr.  Albert  Sauveur  (Harvard  University)  also  sent  in  a  note 
suggesting  "  Improvements  in  Metallurgical  Microscopes." 

The  two  types  of  microscopes  used  in  the  United  States  are  described. 
One  of  these  is  the  horizontal-vertical  type  in  which  a  vertical  micro- 
scope is  used  for  visual  and  a  connected  horizontal  camera  for  photo- 
graphic work.  The  author's  magnetic  holder  for  iron  and  steel  is  largely 
employed. 

Mr.  Sauveur  does  not  expect  much  from  greatly  increased  magnifi- 
t^ations  of  iron  and  steel.  What  is  needed  at  the  moment  are  better 
methods  for  identifying  constituents  and  impurities,  and  he  briefly 
indicates  the  gaps  in  our  present  knowledge. 

Mr.  F,  Ian  C  Rawlins,  F.R.M.S.,  described  how  an  Ordinary 
Microscope  can  easily  be  Adapted  for  Metallographical  Work. 

The  adaptions  suggested  are  a  focusing  substage  fitting,  a  simple 
'Carrier  in  which  to  mount  the  objective  close  to  the  reflector  of  the  vertical 
illuminator,  and  for  illumination  a  type  of  half-watt  lamp  made  in 
Holland  (used  with  a  condenser  of  small  aperture),  in  which  the  ring- 
filament  gives  a  very  solid  and  concentrated  source  of  light. 

Dr.  W.  H.  Hatfield,  in  the  course  of  the  discussion,  spoke  of  the 
value  of  high-magnification  photographs  of  iron  and  steel,  but  he 
reminded  the  meeting  that  1,000  diameters  represented  the  limit  of 
adequate  resolution — more  than  that  only  enlarged  the  picture.  If 
that  resolution  could  be  exceeded,  he  anticipated  a  considerable  advance 
in  knowledge.  Such  problems  as  the  cause  of  the  influence  of  cold 
work  on  metals  still  awaited  solution. 

Professor  H.  M.  Howe,  in  a  communication  to  the  meeting,  also 
indicated  the  value  of  aiming  at  higher  magnifications. 

Mr.  E.  F.  Law  similarly  alluded  to  the  fine  structure  of  modern 
alloys,  which  could  not  be  resolved  with  existing  instruments.     Similar 


I 


PROCEEDINGS   OF   THE    SOCIETY.  115 

problems  were  to  be  found  in  the  intercrjstalline  weakness  of  metal  and 
the  so-called  amorphous  phase. 

A  group  of  papers  dealt  with  "  Microscope  Micrometry." 

Mr.  Zay  Jeffries  (Cleveland,  U.S.A.)  communicated  a  paper  on  the 
application  of  the  microscope  to  the  determination  of  grain  size  in 
tungsten. 

Professor  W.  M.  Thornton  described  a  method  of  calibrating  the 
eyepiece  micrometer  of  a  microscope  used  for  measuring  small  objects, 
using  a  loose  scale  in  the  eyepiece  in  conjunction  with  a  graduated  slide 
for  calibration. 

Dr.  A.  E.  H.  TuTTON,  F.R.S.,  contributed  a  paper  on  "  The 
Grayson  Rulings." 

These  wonderful  rulings  begin  where  others  leave  off,  and  they  have 
reached  an  extreme  value  of  120,000  to  the  inch,  representing  the 
highest  resolving  power  of  the  microscope.  They  are  thus  of  great 
value  in  studying  resolution,  while  the  rulings  of  40,000  to  the  inch 
(about  the  wave-length  of  red  light)  are  capable  of  becoming  of  great 
importance  in  metrology  and  as  fiducial  marks  in  connection  with 
interferometric  fine-measurement  in  general. 

The  recent  death  of  Professor  Grayson  in  Melbourne  was  a  great 
loss,  and  he  hoped  the  meeting  would  help  to  ensure  that  his  ruling 
machine  should  be  available  for  the  continued  production  of  rulings. 

A  note  by  Professor  H.  Le  Chatelier  described  and  illustrated 
"  A  Microscope  used  for  Measuring  Brinell  Depressions." 

Dr.  H.  Hartridge,  F.R.M.S.,  contributed  a  preliminary  description 
of  "An  Accurate  Method  of  Objective-testing,"  and  Mr.  F.  Twyman  a 
note  on  "  The  Testing  of  Objectives  by  Interferometry." 

Mr.  Hartridge's  method  aims  at  being  less  dependent  on  the  skill 
of  the  observer  than  present  methods.  It  consists  in  measuring  with 
a  micrometer  the  position  of  the  image  pattern  when  different  parts  of 
the  objective  aperture  are  used.  If  there  is  movement  of  the  image 
pattern  the  micrometer  reading  is  plotted  against  the  N.A.  of  the  aper- 
ture in  use,  and  the  resulting  curve  shows  the  aberrations  present. 
Examples  of  typical  curves  obtained  are  discussed. 

Mr.  Twyman's  method  has  not  yet  been  much  used,  but  actual  tests 
made  show  on  an  interference  "contour  map"  aberrations  of  wave 
surface  not  exceeding  one  wave  length  for  monochromatic  light.  The 
interferometer  employed  is  briefly  described. 

Lt.-Col.  J.  W.  GiFFORD  described  how  to  make  up  simple  "  Light 
Filters  for  the  Microscope  and  Photomicrography." 

A  solution  of  malachite  green  in  glycerine  is  used  which  transmits 
only  a  broad  band  in  the  region  of  the  F  line  and  a  narrow  red  band, 
and  the  latter  is  eliminated  by  the  peacock-green  glass  used  for  making 
the  cells  for  holding  the  solution.  For  photomicrography  a  solution  of 
methyl  violet  is  similarly  used.  The  author's  present  method  of  making 
the  cells  is  described. 

I  2 


116  PROCEEDINGS    OF   THE    SOCIETY. 


AN   ORDINARY  MEETING 


OF  THE  Society  was  Held  at  20  Hanover  Square,  W.,  on 
Wednesday,  January  21st,  1920,  Mr.  J.  E.  Barnard,  Presi- 
dent, IN  THE  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirmed,  and 
signed  by  the  President. 


The  nomination  papers  were  read  of  eight  candidates  for  Fellowship. 


New  Fellows.— The  following  were  elected  Ordinary  Fellows  of 
the  Society  : — 

Mr.  Arthur  S.  Burgess,  M.A.,  M.B.,  B.Ch. 
Mr.  Henry  Herbert  James  Bull. 
Mr.  Harry  Leon  Gauntlett,  M.R.C.S.,  L.R.C.P. 
Mr.  Albert  Edward  Mills,  F.C.S.,  M.P.S.,  F.Z.S. 
Mr.  Venkata  Rau,  M.A.,  F.L.S. 


A  Donation  was  reported  from  : — 

Major  T.  C.  Squance,  consisting  of — 

1.  A  Cuff  Microscope. 

2.  A  Culpepper  and  Scarlett  Microscope. 

3.  Raspail's  Modification  of  Cuff's  Microscope. 

On  the  motion  of  the  President,  a  very  hearty  vote  of  thanks  was 
accorded  to  Major  Squance  for  his  valuable  gift  to  the  Society. 


The  Annual  Report  of  the  Council  for  1919  was  read  as  follows  : — 

fellows. 

During  the  year  46  Ordinary  Fellows  have  been  elected,  and  1  re- 
instated. Seven  have  died  and  7  have  resigned.  One  Honorary  Fellow 
has  been  elected. 

The  number  of  Fellows  on  the  Roll  at  the  end  of  the  year  1919  was 
as  follows  : —  I 

Ordinary        ....     420 
Honorary       .  .  .  .17 

Ex-officio       ....       69 
Corresponding        ...         1 

507 


PROCEEDINGS   OF   THE   SOCIETY.  117 

Of  the  Ordinary  Follows — 

g  334  have  paid  the  annual  subscription. 
37  have  compounded. 
10  have  had  subscriptions  remitted. 

''  The  deaths  referred  to  above  included  that  of  Sir  Frank  Crisp,  Bart., 
who  for  many  years  took  a  very  active  and  important  part  in  the  work 
of  the  Society,  and  although  he  had  not  attended  the  Society's  Meetings 
during  recent  years  his  interest  in  its  welfare  remained  unabated. 

Deceased  Fellows : — 

Sir  Frank  Crisp,  Bart.     Elected  1870. 

Mr.  John  W.  Dunkerley.     Elected  1883. 

Dr.  George  E.  Fell.     Elected  1882. 

Sir  Frederick  Du  Cane  Godman.     Elected  1877. 

Mr.  John  Hopkinson.     Elected  1867. 

Mr.  William  Hudson.     Elected  1864. 

Mr.  James  A.  Robertson.     Elected  1908. 


FINANCE. 

The  Council  regrets  that  on  account  of  the  delay  in  issuing  Part  4 
of  the  Journal,  it  has  again  not  been  possible  to  get  out  the  accounts  in 
time  for  the  General  Meeting,  therefore  they  will,  together  with  the 
Treasurer's  Financial  Report,  be  presented  later. 


Journal. 

The  Journal  of  the  Society  has  been  produced  during  the  past  year 
under  somewhat  difficult  conditions,  but  it  is  hoped  that  as  these  adverse 
circumstances  are  gradually  removed  it  will  be  possible  to  develop  its 
scope  and  usefulness  in  many  hitherto  unexploited  directions. 

The  Council  wishes  to  thank  most  cordially  the  Editors,  Abstractors, 
and  Contributors  for  their  valuable  and  much  appreciated  work  during 
the  past  year. 

LIBRARY. 

During  the  year  95  volumes  have  been  borrowed  from  the  Library 
by  Fellows  of  the  Society,  in  addition  to  21  volumes  that  have  been 
obtained  from  Lewis's  Lil3rary  for  their  use. 

Donations  to  the  Library  have  been  received  from — The  Macmillan 
Company,  University  of  Chicago  Press,  Chapman  and  Hall,  Limited, 
Dr.  H.  Woodward,  British  Museum,  Lieut.-Col.  F.  K.  McClean,  and 
Mr.  W.  Carruthers. 

INSTRUMENTS   AND   APPARATUS. 

The  Instruments  and  Apparatus  belonging  to  the  Society  are  in 
excellent  condition. 


118  PROCEEDINGS   OF   THE   SOCIETY. 

During  the  year  the  Society  has  received  the  following  donations  : — 

Mr.  T.  B.  Rosseter  : — Two  Microscopes,  Slide  Cabinets,  Slides,  etc. 
Sir  David  L.  Salomons,  Bart.  : — A  solid  Silver  Microscope,  by  Fran$oi8 

Watkins  (1754). 
Mr.  Frank  Rowley  ; — Case  of  Ivory  Mounts. 

Although  no  progress  has  been  made  with  the  Instrument  Catalogue 
during  the  past  year,  the  Council  regards  this  as  an  important  work 
which  must  now  be  vigorously  prosecuted. 

CABINET. 

During  the  year  further  work  has  been  done  in  connexion  with  the 
preparation  of  a  card-index  to  the  Slides  belonging  to  the  Society,  and 
valuable  additions  to  the  Cabinet  have  been  received  from — Mr.  G.  H. 
Wailes,  F.L.S.,  Mr.  E.  J.  Sheppard,  Mr.  T.  B.  Rosseter,  and  Professor 
G.  F.  Bryan,  D.Sc,  F.R.S. 

MEETINGS. 

The  Meetings  of  the  Society  have  been  well  attended. 

The  papers  have  been  of  a  varied  and  interesting  character,  and 
have  been  followed  by  useful  discussion. 

The  Biological  Section,  which  meets  on  the  first  Wednesday  of  each 
month,  is  most  active  and  energetic,  and  its  meetings  are  so  well 
attended  that  the  accommodation  in  the  Library  is  barely  sufficient  for 
the  purpose.  During  the  session  a  visit  was  paid  to  the  Laboratories  of 
King's  College,  on  the  invitation  of  Mr.  Barnard. 

The  thanks  of  the  Society  are  due  to  Mr.  J.  Wilson  for  his  continued 
energy  and  activity  as  Honorary  Secretary  of  the  Section. 

METALLURGICAL   SPECIMENS. 

A  collection  of  metallurgical  specimens  for  microscopical  study  has 
been  presented  to  the  Society  by  Sir  Robert  Hadfield  ;  and  these 
specimens  were  prepared  and  polished  at  the  Royal  School  of  Mines 
through  the  kindness  of  Professor  H.  C.  H.  Carpenter. 

A  detailed  report  on  the  individual  items  included  in  this  collection 
was  read  at  an  Ordinary  Meeting  by  Mr.  F.  I.  G.  Rawlins,  who  has  now 
been  nominated  by  the  Council  for  election  as  Curator  of  such  specimens. 

THE   CONVERSAZIONE. 

By  the  kindness  of  Dr.  Walmsley,  the  Principal,  and  the  Governing 
Body  of  the  Northampton  Polytechnic  Institute,  it  was  found  possible 
to  hold  a  Conversazione  at  that  Institute  in  December  last.  This,  the 
first  since  1013,  was  highly  successful.  The  exhibits  were  of  a  most 
interesting  character,  and  particular  mention  must  be  made  of  the 
working  exhibit,  dealing  with  glass-grinding  from  beginning  to  end,  by 


PROCEEDINGS    OF   THE    SOCIETY.  119 

students  of  the  Institute,  arranged  by  Mr.  Redding.  The  good  atten- 
dance of  Fellows  and  their  friends  clearly  indicates  the  great  advantage 
that  will  be  derived  from  the  resumption  of  one  of  the  principal  annual 
fixtures  of  the  Society. 

The  Council  has  tendered  its  best  thanks  to  the  Governing  Body 
for  placing  the  Institute  at  its  disposal,  and  to  the  various  gentlemen 
who  contributed  to  the  success  of  the  gathering. 


THE   SYMPOSIUM. 

The  Report  of  your  Council  would  not  be  complete  without  some 
reference  to  the  Symposium  which  was  held  at  the  Rooms  of  the  Royal 
Society  on  Wednesday  last,  January  14,  for  although  the  Symposium 
was  not  held  until  after  the  termination  of  the  year  to  which  this  report 
relates,  all  the  spade-work  in  connexion  with  it  was  carried  out  during 
the  year  under  review,  and  some  notice  of  the  Symposium  itself  there- 
fore fittingly  finds  place  in  this  report. 

In  conjunction  with  the  Faraday  Society,  the  Optical  Society,  the 
Photomicrographic  Society,  and  in  co-operation  with  the  Optical 
Committee  of  the  British  Science  Guild,  a  Symposium  and  Discussion 
on  "  The  Microscope  :  its  Design,  Construction  and  Applications,"  was 
arranged.  It  wns  probably  one  of  the  most  important  events  that  has 
occurred  in  the  history  of  the  Society,  and  the  ultimate  results  cannot 
fail  to  develop  and  extend  the  influence  of  the  Society  in  many  directions. 
The  bulk  of  the  work  of  organization  was  undertaken  by  Sir  Robert 
Hadfield  and  the  President  of  this  Society,  Mr.  J.  E.  Barnard,  and  our 
heartiest  thanks  are  due  to  those  gentlemen  for  their  generous  exertions 
which  ensured  the  striking  success  of  a  unique  function. 

The  best  thanks  of  the  Society  are  also  due  to  the  Council  of  the 
Royal  Society  for  granting  the  use  of  the  Rooms  at  Burlington  House 
for  the  holding  of  the  Symposium  and  the  accompanying  Exhibition. 

Arrangements  are  being  made  for  the  publication  of  the  papers  read 
at  the  Symposium  and  a  record  of  the  proceedings. 

Mr.  Clemence  moved,  and  Mr.  Heath  seconded,  that  the  Annual 
Report  be  received  and  adopted.     Carried. 

Mr.  Young  moved,  and  Mr.  Marshall  seconded,  that  a  very  heartf 
vote  of  thanks  be  tendered  to  the  Honorary  Officers  and  Members  of  the 
Council  for  their  services  to  the  Society  during  the  past  year.     Carried. 


The  President  appointed  Mr.  Pledge  and  Mr.  Taverner  to  act  as 
Scrutineers,  and  afterwards  announced  the  result  of  the  ballot  for  the 
election  of  Officers  and  Council  for  the  ensuing  year  as  follows  : — 

President.— J.  W.  H.  Eyre,  M.D.,  M.S.,  F.R.S.Edin. 

Vice- Presidents. —Sir  George  Sims  Woodhead,  K.B.E.,  M.A.,  M.D., 
LL.D.,  etc.  ;  Frederic  J.  Cheshire,  C.B.E. ;  Percy  E.  Radley  ;  Alfred  N, 
Disney,  M.A.,  B.Sc. 

Treasurer. — Cyril  F.  Hill. 

Secretaries. — Joseph  E.  Barnard  ;  David  J.  Scourfield,  F.Z.S. 


120  PROCEEDINGS    OF   THE    SOCIETY. 

Council. — Maurice  A.  Ainslie,  R.N.  ;  Herbert  F.  Angus  ;  Maurice 
Blood,  M.A.,  F.C.S.  ;  F.  Martin  Duncan,  F.R.P.S.  ;  Arthur  Earland  ; 
Sir  Robert  Hadfield,  Bart.,  D.Sc,  F.R.S.  ;  T.  H.  Hiscott  ;  James  A. 
Murray,  M.D.  ;  Julius  Rheinberg  ;  E.  J.  Sheppard  ;  Charles  Singer, 
M.A.,  M.D.  ;  Joseph  Wilson. 

Librarian. — F.  Martin  Duncan,  F.R.P.S. 

Curators. — F.  Ian  (t.  Rawlins  ;  E.  J.  Sheppard  ;  Charles  Singer, 
M.A.,  M.D. 

A  vote  of  thanks  to  the  Scrutineers  was  moved  from  the  Chair  and 
carried. 


The  President  then  delivered  his  Presidential  Addres?,  entitled 
"  The  Present  Status  of  Microscopy." 

Commander  Ainslie  moved :  "  That  the  best  thanks  of  this  meeting 
be  accorded  to  Mr.  Barnard  for  his  Presidential  Address,  and  that  he 
be  asked  to  allow  it  to  be  printed  in  the  Journal  of  the  Society." 

Mr.  W.  E.  Watson  Baker  seconded  the  proposal,  which  was  carried 
by  acclamation. 


Mr.  E.  J.  Sheppard  exhibited  a  slide  showing  mitosis  in  the  root 
tips  of  Fritillaria  Imperialis.     The  specimen  was  stained  with  safranin. 

Mr.  Scourfield  exhibited  living  specimens  of  Hydrodictyon  (Water 
Net).  He  mentioned  that  the  specimens  had  been  brought  from  the 
Caucasus,  but  it  was  also  a  British  alga,  although  not  very  common. 

The  thanks  of  the  meeting-  were  accorded  to  Mr.  Sheppard  and 
Mr.  Scourfield  for  their  exhibits. 


The  President  announced  that  the  next  meeting  of  the  Society 
would  be  held  on  February  18,  and  of  the  Biological  Section  on 
February  4,  when  Sir  Nicholas  Yermoloff,  K.C.B.,  K.C.V.O.,  would 
make  a  communication,  "Notes  on  Beggiatoa  and  some  Allied  Forms." 


PROCEEDINGS   OF   THE    SOCIETY.  121 


AN   ORDINARY  MEETING 

OF  THE  Society  was  held  at  No.  20  Hanover  Square,  W.,  on 
Wednesday,  February  18th,  1920,  Professor  John  Eyre, 
President,  in  the  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirmed,  and 
signed  by  the  President. 


The  nomination  papers  were  read  of  six  Candidates  for  Fellowship. 


New  Fellows. — The  following  were  elected  Ordinary  Fellows  of  the 

Society : — 

Mr.  H.  y.  Adams. 

Mr.  Alexandre  Durand. 

Prof.  Alfonso  Gandolfi  Hornyold,  D.Sc. 

Dr.  Maurice  C.  P.  Langeron. 

Prof.  Samarendra  Maulik,  M.A.,  F.Z.S.,  F.E.S. 

Mr.  Charles  Henry  Oakden,  F.R.P.S. 

Mr.  George  Albert  William  Trinder,  M.J.I. 

The  Rev.  Canon  G.  R.  Bullock-Webster. 


Donations  were  reported  from  : — 

The  Cambridge  University  Press — 

"  An  Introduction  to  the  Study  of  Cytology." 

Mr.  E.  Heron-Allen — 

"  Foraminifera   of  the   Cote    des   Basques,"   and   another 
volume. 

On  the   motion    of   the   President,   hearty  votes   of   thanks  were 
accorded  to  the  donors. 


The  Financial  Statement  for  the  year  1919,  which  should  have  been 
included  in  the  Annual  Report  of  the  Council,  was  presented  and  read 
by  the  Treasurer,  as  here  inserted  (see  pages  122-3). 


finance. 


The  Revenue  Account  shows  excess  of  Income  over  Expenditure  of 
£2  16s.  Id. 

Part  4  of  the  Journal  has  not  yet  been  issued,  and  the  Council  have 
therefore  placed  to  reserve  an  amount  of  £150  to  cover  the  cost  of 
publishing  this  Number  of  the  Journal. 


INCOME  AND   EXPENDITURE  ACCOUNT 


Dec.  31,  1918. 

£     s.  d. 
161  17     9 
235  18  10 

20    5     3 
86  10  11 
31     4     2 

To  Rent  and  Insurance 
,,  Salaries  and  Reporting     . 
,,  Sundry  Expenses — 

Library,  Books  and  Binding 
Stationery,  Printing,  etc.     , 
Petty  Expenses  and  Postages 

„  Journal  (Parts  1,  2,  3)— 
Expenditure- 
Printing 

Editing  and  Abstracting  . 
Illustrating 
Postages,  etc.  . 

Less  Receipts — 

Sales       .... 
Advertisements 

Reserve  for  Part  4 
,,  Conversazione 
,,  Donation  to  Board  of  Scientific 

Societies     .... 
„  Balance,  being  excess  of  Income 

over  Expenditure 

£     s. 

477     4 
60     1 
32  10 
23  12 

d. 

3 
6 
1 
0 

£     s. 

29    0 
85  19 
32    2 

d.        £      s.   d. 
155     5     0 
254     7     6 

2 
7 
0 

593     7 
432  15 

10 

2 

160  IQ     ft 

343  19 

88  15 

7 
7 

163  14     4 

• 

150    0    0 

150     0     0 
35     6    9 

10  10    0 

2  16    7 

849  11     3 

£916    0    3 

IBr. 

BALANCE 

Dec.  31,  1918. 
£     5.   d.  Liabilities.  &     s.  d.        £    s.    d.         £  s.   d. 


328    4     8 
150    0    0 


Liabilities. 
To  Sundry  Creditors- 
Subscriptions  paid  in  Advance 
On  A/c  Journal  Printing,  etc. 

„       Sundries,  Printing,  etc. 
Reserve  for  Part  4  of  Journal 

£     s. 

2140  13 
48     6 

2  16 

d. 

1 
7 

7 

£    s. 

15  15 
160  19 

37     8 
160.   0 

d. 

0 
3 

4 
0 

„  Life  Membership  (1917  A/c)   . 
Add  Life  Membership  Fees 
received  in  1919 

63     0 
55     2 

0 
6 

„  Capital  Funds  A/c— 

Balance  as  per  last  A/c 
Reserve  A/c 
Excess  of  Income  over  Ex- 
penditure for  year    . 

2191  16 
168  14 

3 
0 

Less  Depreciation  of  Society's 
Investments    . 

364     2     7 


63    0    0  L-       118     2     6 

2140  13     1 

48    6    7 


2023     2     3 


2730    4    4  £2505     7     4 


(Signed)    C.  F.  Hill,  Eon.  Treasurer. 
February  7,  1920. 


FOR   YEAR   ENDING   31st  DECEMBER,  1919.  Cr. 

Dec.  31,  1918. 
£      s.    d. 

By  Subscriptions  (excluding  Life  Members'  Fees) 
,,  for  year  1919,  unpaid 

634     1     1 
67     4     0  ,,  Admission  Fees  ...... 

18  12     6  ,,  Sundry  Sales  and  Receipts  .... 

106     17  „  Interest  on  Investments  and  Deposit  A/c     . 


23  12    1 


2730    4    4 


£  s.  d. 

£  s. 

d. 

636  0  11 

46  14  6 

682  15 

5 

77  14 

0 

35  15 

8 

119  15 

2 

849  11     3  £916    0    3 


SHEET.  Cr. 


Dec.  31,  1918. 

£  s.  d. 

Assets. 

By  Cash- 

300  0  0 

On  Deposit  A/c 

53  14  4 

On  Current  A/c 

1  16  4 

On  Petty  Cash  A/c 

£      s.    d.       £    s.    d. 


239     5     4 


150  0 

86  2 
3  2 

0 

11 
5 

46  14 

183  7 

29  14 

6 
6 
6 

,,  Sundry  Debtors — 

Subscriptions  unpaid 
On  A/c  Journal  Sales 

,,  ,,        Advertisements 

210     2     2  259  16     6 

,,  Investments  at  Valuation,  Dec.  31,  1916 — 
£400  North  British  Railway  3  %  Deb. 
£500  Nottingham  Corporation  3  %  Deb. 
£915  India  3  %  Deb. 
£150  Metropolitan  Water  Board  3  %     . 
£421  War  Loan  5  % 
£612  Caledonian  Railway  No.  1  Pref. 
Less  Depreciation        .... 
1981  14    0 

18  16     0  „  Stock  of  Screw  Guages,  Valued  at 

,,   Property  Account,  as  per  last  Balance  Sheet 
Add  Purchased  during  year 
164     1     6 


1981  14 
168  14 

0 
0 

0 
0 

6 

164  1 

10  8 

18  16 
6 
0 

174.  Q 

£2505  7 

4 

We  have  examined  the  accounts  as  above  set  forth,  and  have  verified  the  same  with  the 
books,  vouchers  and  securities  belonging  to  the  Society,  and,  in  our  opinion,  the 
Balance  Sheet  is  properly  drawn  up  so  as  to  exhibit  a  true  and  correct  view  of  the 
state  of  the  Society's  affairs,  but  no  account  has  been  taken  of  the  value  of  the  Society's 
Library,  Ingtruments  and  Stocks  of  Journals  (valued  for  Insurance  at  £3000). 

(Signed)    T.  H.  Hiscott,       |  ^       Auditcyrs. 

.  H.    H.    MOETIMBE, 


124  PROCEEDINGS    OF   THE    SOCIETY. 

Since  the  last  valuation  of  the  Society's  Securities,  these  have 
depreciated  by  £168  14s.,  and  this  amount  has  been  written  ofif  the 
Investment  and  Capital  Account. 

The  Investment  Account  therefore  now  stands  at  £1813. 

The  Auditors  draw  attention  to  the  fact  that  the  Property  Account 
stands  at  the  nominal  amount  of  £174,  and  does  not  include  any 
account  of  the  instruments  and  books,  which  are  insured  for  a  sum 
of  £3000. 

During  the  year  two  Life  Composition  Fees  have  been  received,  and 
these  have  been  placed  to  the  credit  of  the  Life  Membership  Account, 
making  that  Account  £118  2s.  6^. 

Compared  with  last  year,  the  Income  of  the  Society  shows  a  steady 
increase,  and  the  amount  received  from  Subscriptions  and  Admission 
Fees  is  practically  the  same  as  received  in  1913 — the  last  pre-war  year. 

Unfortunately,  the  cost  of  publishing  the  Journal  again  shows  an 
increase,  and  it  will  not  be  possible  to  revert  to  a  bi-monthly  issue 
unless  the  income  of  the  Society  is  considerably  increased. 

Mr.  Hill  moved  and  Mr.  Wilson  seconded  : — '*  That  the  Financial 
Statement  be  received  and  adopted."     Carried. 

Mr.  Blood  moved  and  Mr.  E.  J.  Sheppard  seconded — "  That  the 
best  thanks  of  this  Meeting  be  accorded  to  the  Auditors,  Mr.  Hiscott 
and  Mr.  Mortimer."     Carried. 


The  following  papers  were  read  by  Mrs.  Arber,  D.Sc,  F.L.S.  : — 
"  Studies  on  the  Binucleate  Phase  in  the  Plant-Cell,"  by  Agnes  Arber  ; 
"  On  Multinucleate  Cells  :  An  Historical  Study  (1879-1919),"  by  Rudolf 
Beer  and  Agnes  Arber. 

These  papers  appear  on  pages  1-31. 

The  President  said  that  the  Society  was  greatly  indebted  to  Mrs. 
Arber  for  her  papers.  As  he  was  not  a  botanist  he  did  not  feel  com- 
petent to  deal  with  or  criticize  the  papers,  but  he  could  appreciate  the 
work,  and  realize  the  amount  of  tedious  toil  that  had  been  necessary  in 
their  preparation. 

Mr.  E.  J.  Sheppard  said  that  several  facts  had  come  under  his 
notice.  In  rapidly  growing  tissues  it  was  quite  a  common  feature  to 
see  nuclei  with  very  long  pseudopodia.  Sometimes  they  were  extensively 
lobed,  and  the  ends  extremely  truncated  or  lobed.  It  had  often 
occurred  to  him  that  these  large  pieces  might  be  separated  off.  He  had 
seen  in  these  extended  portions  a  nucleolus,  and,  as  growth  proceeded,  it 
was  quite  possible  they  might  form  other  nuclei.  In  cases  like  these  he 
was  inclined  to  suggest  that  it  was  amitotic  division  rather  than  mitosis. 

Mr.  Paulson  pointed  out  that  in  the  course  of  her  remarks  Mrs. 
Arber  had  supported  very  strongly  the  view  that  the  irregular  nucleus 
was  a  nucleus  that  was  passing  away,  but  admitted  that  there  was  a 
possibility  that  two  nuclei  might  fuse  within  the  cell.  Mrs.  Arber's  view 
that  ,the  irregular  nucleus  was  a  nucleus  in  a  state  of  old  age,  and  Dr. 
G.  R.  McLean's  that  the  bi-lobed  nucleus  was  the  result  of  the  fusion 
of  two  nuclei,  led  to  opposite  conclusions.  In  the  first  case  they 
had  old  age  ;  in  the  second  a  form  of  rejuvenescence. 


PROCEEDINGS   OF   THE    SOCIETY.  125 

Miss  Pankerd,  Dr.  Ruggles  Gates  and  Mr.  Beer  also  spoke. 

Mrs.  Arber,  in  reply,  said  there  was  a  nuclear  lobing  that  occurred 
in  young  cells,  and,  in  addition,  she  had  unfortunately  used  the  word 
"  lobing  "  for  the  irregular  forms  developed  by  very  old  nuclei.  This 
perhaps  accounted  for  the  disagreement  pointed  out  by  Mr.  Paulson. 
With  reference  to  the  nuclear  pseudopodia  breaking  olf,  she  would  like 
to  know  whether  Mr.  Sheppard  had  evidence  of  their  actual  detach- 
ment. She  had  always  found  that  they  were  joined  by  a  little  bridge. 
That  was  what  had  puzzled  them.  At  the  present  time  there  appeared 
to  be  some  doubt  about  most  of  the  botanical  cases  described  under  the 
name  "  amitosis." 

The  President  proposed  a  very  hearty  vote  of  thanks  to  Mrs  Arber, 
and  it  was  carried  by  acclamation. 


Mr.  Akehurst  gave  an  exhibition  of  Professor  Silverman's  Illuminator 
for  Opaque  Objects. 

Mr.  E.  J.  Sheppard  exhibited  a  slide  showing  Mitosis  in  Hyacinth 
root-tips,  with  marked  differentiation  in  the  staining  of  the  chromosomes. 

Mr.  F.  Martin  Duncan  exhibited  a  slide  of  Cladonoma  radiatuniy 
a  Medusa  narcotized  by  the  Menthol  Crystal  method. 

Mr.  Wilson  exhibited  specimens  of  Floscularia  ornata. 

Mr.  Scourfield  exhibited  a  specimen  of  Diaptomus  Castor. 

Votes  of  thanks  were  accorded  to  the  above  for  their  exhibits. 


The  President  announced  that  the  next  Meeting  would  be  held  on 
March  17,  and  the  next  Meeting  of  the  Biological  Section  on  March  3, 
when  Dr.  Tierney  would  read  a  communication  on  "The  Bacterial 
Flora  of  Water." 


The  business  proceedings  then  terminated. 


126  PROCEEDINGS    OF   THE    SOCIETY. 


EEPORT  ON  THE  WORK  OF  THE  BIOLOGICAL  SECTION 
OF  THE  ROYAL  MICROSCOPICAL  SOCIETY  DURING 
1918-19. 

{Read  at  the   First  3Ieeting  of  the  Twelfth  Session 
of  the  Section.) 

It  is  my  pleasing  duty  at  this  Meeting  to  submit  the  Eleventh  Annual 
Report  on  the  Biological  Section,  which  will  show  that  the  Section  has 
not  only  survived  the  turbulent  times  through  which  we  have  passed 
during  the  last  five  years,  but  that  it  has  steadily  increased  in  member- 
ship and  maintained  the  interest  of  its  Meetings.  The  usual  Meetings 
were  held  on  the  first  Wednesdays  of  the  months  November  to  June, 
at  which  the  average  attendance  was  25*6,  as  against  the  previous  record 
of  22*4  for  the  Session  1916-17.  At  the  February  Meeting  only  nine 
Members  were  present,  but  these  enthusiasts  braved  the  snowstorm  then 
raging,  and  the  risk  of  having  to  walk  to  their  homes  owing  to  the  strike 
of  the  railway  employees  then  in  progress. 

The  November  Meeting  was  held  at  the  King's  College  Laboratory, 
Chandos  Street,  on  the  invitation  of  our  President,  Mr.  J.  E.  Barnard, 
who  exhibited  and  described  the  various  microscopical  and  optical  appa- 
ratus used  in  his  important  researches  on  ultra-violet  light,  etc.,  and  his 
assistant,  Mr.  Welch,  gave  a  demonstration  in  staining  bacteria. 

At  the  Meeting  on  December  4,  1918,  Mr.  C.  D.  Soar  gave  a  short 
description  of  "  A  Species  of  Uropoda'"' 

The  Meeting  on  January  8,  1919,  was  occupied  by  Mr.  D.  J. 
Scourfield,  who  described  the   "  Sense-organs  of  Daphnia  and  its  Allies." 

Mr.  A.  W.  Shepherd,  on  February  5,  described  the  "  Pollen-chamber 
of  Cycads  and  its  Function,"  and  on  March  5  Mr.  F.  Martin  Duncan 
exhibited  and  described  some  interesting  Marine  Crustacea.  The  Meet- 
ing on  April  2  was  occupied  by  Sir  Nicholas  Yermoloff,  K.C.B.,  who 
gave  some  "Notes  on  Flagellates,"  and  by  Mr.  H.  Taverner,  who 
described  "  Colour-Photography  as  applied  to  Photomicrography."  At 
the  Meeting  held  on  May  7  Mr.  F.  A.  Parsons  read  some  notes  on  a 
"  Pycnogon,"  and  Mr.  N.  E.  Brown,  A.L.S.,  made  a  communication  on 
"  Starch  and  its  Formation."  At  the  last  Meeting,  on  June  4,  Mr.  E.  J. 
Sheppard  gave  some  notes  on  "  Original  Work  on  the  Rat-Flea." 

In  addition  to  these  more  formal  communications,  many  interesting 
specimens  were  shown  under  microscopes  by  the  Fellows  and  described 
by  them,  and  these  formed  very  valuable  topics  for  discussion  which 
added  greatly  to  the  interest  of  the  Meetings.  J.  Wilson. 


ROYAL   MICROSCOPICAL   SOCIETY   STANDARDS 
FOR   EYE-PIECES. 

During  the  year  1915  the  Council  of  the  Society  deposited  with  the 
Director  of  the  National  Physical  Laboratory  their  Standard  Eye-pieces 
and  Sub-stage  Gauges.*  These  gauges  were  made  for  the  Society  in  1900, 
and  were  good  examples  of  the  Plug  and  Ring  gauges  of  that  date.f  They 
have  recently  been  carefully  checked  at  the  Natural  Physical  Laboratory, 
and  are  found  to  be  not  sufficiently  accurate  for  use  as  standards.  Further- 
more, the  Committee  on  Standardization  of  the  Elements  of  Optical 
Instruments  of  the  Department  of  Scientific  and  Industrial  Research 
recommend  that  as  the  standards  were  for  the  eye-piece  tube  only,  and 
the  fit  of  the  eye-piece  was  left  to  the  maker's  own  judgment,  it  would 
be  in  accordance  with  advanced  practice  if  suitable  tolerances  were 
defined  and  approved  by  the  Society.  This  has  accordingly  been  done, 
and  the  dimensions  are  shown  in  the  followins:  table  : — 


Eye-Piece  Fittings— 

-Diameters  in  Inches. 

Internal  Diameter  of                    External  Dianaeter  of 
Draw  Tube.                                     Eye-piece. 

SmaU  .... 
Large  .... 
Extra  large  . 

Not  under 
0-917 
1-270 
1-410 

Not  over 
0-918 
1-271 
1-411 

1  Not  under 
0-915 
1-268 
1-408 

Not  over 
0-916 
1-269 
1-409 

The  obsolete  gauges  have  been  returned  from  the  National  Physical 
Laboratory,  and  are  now  deposited  in  the  Society's  collection  of  instru- 
ments. It  is  worth  while,  however,  recording  the  variation  from  the 
true  nominal  diameters  of  these  old  gauges.  The  N.P.L.'s  report  on 
them  is  follows  : — 

"  The  gauges  have  been  measured  at  the  Laboratory  at  62°  F.,  and 
the  following  table  gives  the  dimensions  : — 


Diameter  of  Hing  Gauges. 

Nominal 

Mean  of 
Plug  Gauge. 

Fit  of  the  Plug  in  the 

Diameter. 

Smallest 

Value  towards 

Ring. 

value. 

the  faces. 

inches 

inches 

inches 

inches 

0-9178 

0-9167 

0-91615 

0-9166 

Plug  only  enters  a  short 
distance  at  each  face. 

1-04 

1-0393 

to 
1-03945 

1-0393 

1-0396 

The  plug  can  be  forced 
through  the  ring  with 
lubrication,  but  seizes  at 
the  centre  of  ring  when 
dry. 

As  above. 

1-27 

1-2698 

to 
1-2700 

1-26965 

1-26975 

1-41 

1-40975 

1-41005 

1-41005 

The  plug  is  a  nice  fit  in  the 
ring. 

1-527 

1-52685 

to 
1-5270 

1-52615 

1-5265 

The  plug  will  not  enter  the 
ring. 

*  Trans,  of  the  Royal  Microscopical  Society,  1915,  p.  558. 
t  Ibid.,  1900,  pp.  141,  147. 


128  PROCEEDINGS   OF   THE    SOCIETY. 

"  Four  of  the  ring  gauges  are  slightly  bell-mouthed,  and  measurements 
have  been  made  of  the  smallest  diameter,  which  occurs  towards  the 
centre  of  the  gauge,  and  also  of  the  diameters  towards  the  faces  of  the 
gauge.  The  latter  measurements  were  made  at  about  |-  inch  from  the 
faces,  and,  therefore,  owing  to  the  taper,  the  diameters  at  the  faces  will 
be  slightly  larger  than  the  values  given.  This  is  also  evident  from  the 
tit  of  the  plugs  in  the  rings.  In  several  cases  the  plug  is  found  to  enter 
a  short  distance  at  each  face  and  then  pull  up  well  before  the  end  of  the 
plug  has  passed  half-way  through  the  ring." 

The  Council  of  the  Society  does  not  propose  to  have  new  standard 
reference  gauges  constructed  for  eye-pieces,  as  any  maker  can  have,  if 
he  requires  it,  his  own  limit  gauges  checked  at  the  National  Physical 
Laboratory. 


Attention  is  drawn  to  the  fact  that  the  Eoyal  Microscopical  Society's 
Standard  Object  Glass  Screw  Thread  Gauges  are  still  deposited  with  the 
National  Physical  Laboratory,  and  the  Society  has  on  sale  special 
verified  taps  and  dies  for  sizing  the  objectives  and  nose-pieces  of 
microscopes. 


JOURNAL 

OF    THE 

KOYAL    MICROSCOPICAL   SOCIETY, 

JUNE,  1920. 


TEANSACTIONS   OF  THE  SOCIETY. 


III. — On  the  Belationship  between  the  Formation  of  Yolk  and  the 
Mitochondria  and  Golgi  Apparatus  ditring  Oogenesis* 

By  J.  Beo^e  Gatenby,  B.A.,  B.Sc,  D.Phil.,  Senior  Demy, 
Magdalen  College,  Oxford,  Lecturer  in  Cytology,  University 
College,  London ;  and  J.  H.  Woodgek,  B.Sc,  Assistant  in 
Zoology  and  Comparative  Anatomy,  University  College, 
London. 

{Bead  April  21,  1920.) 

One  Plate  and  Four  Text-Figures. 

In  this  paper  we  have  endeavoured  to  present  some  of  the  new 
aspects  of  the  various  questions  surrounding  the  origin  and  forma- 
tion of  those  elements  or  bodies  which  together  form  what  is  known 
as  the  "  yolk  "  of  the  animal  egg.  So  far  as  possible  we  have  con- 
fined ourselves  to  the  Vertebrata,  but,  as  much  of  the  newer  work 
has  been  carried  out  on  the  oogenesis  of  the  various  Invertebrata, 
we  have  been  obliged  to  refer  to  them  rather  often. 

We  have  to  discharge  the  pleasant  duty  of  thanking  Professor  ^ 
J.  P.  Hill,  r.Pt.S.,  for  reading  over  this  paper  and  advising  us,  i 
though  he  is  not  in  any  way  responsible  for  any  of  the  views  we3 
have  expressed. 

Cell  Elements  known  to  occur  in  Somatic 
AND  Germ  Cells. 

In  all  animal  cells  thoroughly  studied  by  the  modern  technical 
methods,  there  occur  two  definite  categories  of  protoplasmic  inclu- 
sions— the  mitochondria  and  the  Golgi  apparatus.     In  a  previous 

*;;;Part  of  the  material  used  in  this  research  was  supplied  by  a  Government 
grant  of  the  Royal  Society,  for  which  I  express  my  thanks.     (J.  B.  G.) 

K 


130  Transactions  of  the  Society. 

paper  (ii)*  by  one  of  us  a  special  text-figure  has  been  given,  and 
the  reader  is  referred  to  this.f  On  Plate  II  are  figures  of  nerve, 
sperm,  egg,  liver  and  gut  cells,  to  illustrate  our  views.  Each  cell 
■when  suitably  prepared  by  either  a  Formalin-silver  nitrate  method, 
or  an  Osmic  acid  technique,  shows  a  Golgi  apparatus  in  an  excentric 
juxta-nuclear  position  (PI.  II,  figs,  lb,  2,  3,  4  and  9),  or  in  a 
partly  diffuse  (PI.  II,  fig.  Ic),  or  a  completely  diffuse  condition 
(PI.  II,  figs,  la  and  5).  Mitochondria  are  always  found  after 
the  application  of  certain  well-known  techniques,  and  are  shown 
in  PI.  II,  figs.  2,  3,  8  and  9  at  M. 

In  growing  QggB,  or  oocytes  of  animals,  one  finds  not  only 
mitochondria  and  Golgi  apparatus  elements,  but  also  various  sorts 
of  deutoplasmic  materials — yolk,  fat  and  glycogen. 

Apart  from  the  new  structures  which  have  been  described 
within  the  cell  cytoplasm,  the  modern  technique  has  revealed  at 
least  one  kind  of  granule  or  rod  unknown  hitherto  within  the 
nucleus  {36).  This  new  intra-nuclear  body  has  been  called  a 
nucleolinus,  and  the  recent  observations  of  Carleton  {S)  have 
revealed  the  fact  that  the  nucleolinus  stains  differently  from  the 
chromosomes,  and  is  capable  of  independent  binary  fission.     (See 

*  The  italic  figures  within  brackets  refer  to  the  Bibliography  at  end  of  the 
paper.  t  Journ.  R.  Micr.  Soc,  1919,  p.  96. 


EXPLANATION   OF  PLATE   II. 

Lettering.— Gk  =  Golgi  apparatus  ;  A  =  acrosome ;  M  =  mitochondria  ;  N  = 
nucleus  ;  NO  =  nucleolus  ;  NL  =  nucleolinus  ;  V  =  vacuole  (glycogen)  ;  Y  = 
yolk. 

Scale  of  figures  on  right  bottom  corner  of  Plate. 

Fig.  1. — Dorsal  root  ganglion  cells  of  cat,  to  show  at  a,  b,  and  c  passage  of 
Golgi  apparatus  from  an  excentric  juxta-nuclear  position  (b)  to  a  difiuse  stage  (a). 
Drawn  from  a  Cajal  preparation  made  by  Dr.  Penfield,  Histology  Laboratory^ 
Oxford. 

Fig.  2. — Spermatocyte  of  the  cavy  showing-  Golgi  apparatus  (compare  with 
fig.  16)  and  mitochondria.     (Cajal  followed  by  acid  fuchsin.) 

Fig.  3.— Spermatid  of  cavy  showing  Golgi  apparatus,  mitochondria,  and 
acrosome.     (Mann-Kopsch-Altmann  method.) 

Fig.  4. — Spermatocyte  of  Limnxa  showing  Golgi  apparatus.  (Kopsch's  un- 
modified method.) 

Fig.  5. — Oocyte  oiLimnxa  showing  Golgi  apparatus  i  diffuse  (compare  with 
fig.  la)  and  yolk  bodies.     (Same  method.) 

Fig.  6. — Metamorphosis  of  Golgi  element  to  form  a  yolk  body,  as  seen  in 
Kopsch's  methods  (OsO.,).     Not  to  scale. 

Fig.  7. — Metamorphosis  of  mitochondrium  into  a  yolk  body,  as  seen  in 
Altmann's  method  (acid  fuchsin).     Not  to  scale. 

Fig.  8. — Binucleate  liver  cell  of  rabbit  showing  glycogen  vacuoles  and  mito- 
chondria (M).     (Formalin  andiron  hsematoxylin.) 

Fig.  9. — Cell  of  mucous  membrane  of  cat's  duodenum  showing  Golgi  apparatus 
(GA),  mitochondria  (M),  nucleolus  (NL),  and  nucleolinus  (NO)  stained  black. 
From  a  preparation  by  Cajal's  method,  with  safranin,  made  by  Mr.  H.  M.  Carleton. 
Histology  Laboratory,  Oxford. 

Fig.  10.— Oocyte  of  Linmsea  by  Altmann's  method  ;  mitochondria  red,  yolk 
brownish. 


Mitochondria,  Golgi  Apparatus,  and   Yolk 


131 


PL  II,  fig.  9,  XO.)  Thus  the  cell,  as  the  modern  cytologist  knows 
it,  is  a  truly  complicated  structure,  and  the  revelation  of  so  many 
new  bodies  within  it  may  necessitate  the  reconsideration  of  many 
biological  conceptions. 

Among  certain  writers,  of  whom  Faure-Fremiet  {lO)  may  be 
taken  as  an  example,  it  is  considered  that  the  structure  which 
others  consider  to  be  a  Golgi  apparatus  is  produced  at  one  period 
of  the  life  of  the  cell  by  a  metamorphosis  from  part  of  the  mito- 
chondrial constituents  of  the  cytoplasm.  Faure-Fremiet  states 
that  the  "  Nebenkern  "  rodlets  or  dictyosomes  of  the  snail  sperma- 
tocyte are  produced  by  a  transformation  of  mitochondria.  The 
dictyosomes  of  the  snail  spermatocyte  are  the  representatives  in 
that  cell  of  the  Golgi  apparatus,  and  we  cannot  therefore  regard 
them  as  having  anything  to  do  with  the  mitochondria.  Hirschler 
{22)  and  one  of  us  {16)  have  shown  that  the  dictyosomes  or  Golgi 
rodlets  can  be  traced  through  development.  Faure-Fremiet's  work 
was  repeated  by  one  of  us  {16),  and  it  was  shown  that  by  tlie 
Kopsch  or  Cajal  methods  the  dictyosomes  are  found  to  be  present 
in  the  youngest  germ  cells  and  are  not  directly  related  to  the 
mitochondria.  Following  his  previous  views  on  the  '-'Xebenkern," 
Faure-Fremiet  in  his  work  on  Ascaris  seems  to  misinterpret  the 
Golgi  apparatus  of  this  form. 

The  following  table  shows  the  elements  which  have  been 
hitherto  mentioned : — 


Nucleus; 


Oocyte: 


^Cytoplasm:;: 


Chromosomes. 

Nucleoli. 

Nucleolini. 

Mitochondria. 

Golgi  elements. 

Yolk  granules. 

Fat  or  lipoid  vacuoles. 

Glycogen. 

Chromatin  granules. 


Explanatory  Eemarks  ox  Methods. 


Elsewhere  {11)  one  of  us  has  noted  some  staining  reactions  of 
yolk,  fat,  mitochondria  and  Golgi  apparatus.'  In  order  to  make 
this  paper  clear  it  is  proposed  to  describe  shortly  the  methods  used, 
and  some  of  the  staining  and  fixing  reactions  of  the  various  cyto- 
plasmic inclusions. 

Nearly  every  fixing  mixture  contains  either  alcohol  or  acetic 
acid,  but  the  last  few  years  of  cytological  research  have  shown  that 
the  picture  given  by  a  fixing  mixture  containing  "them  is  incorrect 
and  inadequate,  and  one  cannot  fail  to  be  surprised  at  the  im- 
provement produced  when  these  reagents  are  omitted.  Xearly  all 
the  modern  research  on  the  cytoplasm  has  to  be  carried  out  by 

K  2 


132  Transactions  of  the  Society. 

observers  using  chrome-  or  platinum-osmium  fixatives,  followed 
by  iron-alum  haematoxylin,  Benda's  crystal  violet,  or  Altmann's 
acid  fuchsin ;  or  by  tlie  useful  methods  of  Cajal  or  Golgi,  which 
consist  of  silver-nitrate  impregnation  following  formalin  fixation. 
Intra  vitam  methods,  such  as  Janus  green,  neutral  red,  or  Dahlia- 
violet  are  also  used  extensively.  The  mitochondria  are  extremely 
fuchsinophile,  and  after  chrome-osmium  fixation  stain  in  an  intense 
manner  in  iron-alum  haematoxylin.  The  Golgi  apparatus  of 
somatic  cells  and  of  ovarian  cells  rarely  stains  by  these  methods 
(Altmann  or  Haidenhain),  although  the  Golgi  apparatus  of  the 
male  germ  cells  nearly  always  stains  in  fuchsin  or  hematoxylin 
after  chrome-osmium  fixation. 

To  demonstrate  the  Golgi  apparatus  of  somatic  cells,  or  of 
oogonia  or  oocytes,  there  are  several  methods  ;  the  silver-impregna- 
tion methods  of  Cajal  or  Golgi  are  useful,  especially  the  former, 
and  in  the  hands  of  an  experienced  technician  are  fairly  reliable ; 
then  there  are  the  methods  of  Kopsch  and  Sjovall,  which  have  as 
their  basis  osmium  tetroxide.  Modern  improvements  on  the 
Kopsch  method  are  those  of  Mann-Kopsch  {IS),  and  Mann-Kopsch- 
Altmann  {11). 

On  PI.  II  we  endeavour  to  give  true  pictures  of  the  ap- 
pearance of  various  cells,  after  treatment  of  a  tissue  or  organ,  by 
means  of  one  of  the  above-mentioned  special  methods.  In  figs.  1, 
2,  and  9  we  have  cells  impregnated  by  a  formol-silver  method ;  in 
figs.  4  and  5  the  material  has  been  stained  byKopsch's  method, 
and  in  figs.  8  and  10  by  iron-haematoxylin  and  acid  fuchsin  respec- 
tively. 

To  a  greater  or  less  extent  most  of  these  modern  methods  can 
be  controlled  in  such  a  way  as  to  stain  any  given  category  of  cell 
body  in  a  perfectly  specific  manner,  though,  as  will  presently  be 
noted,  puzzling  exceptions  may  be  met  with.  It  can  be  said,  how- 
ever, that  a  cytologist  can  generally  distinguish  between  or  stain 
specifically — yolk,  fat,  glycogen,  chromatin,  mitochondria,  and 
Golgi  apparatus. 

The  problem,  nevertheless,  becomes  very  complicated  when  it 
is  found  that  one  sort  of  cell  granule  or  element  may  metamorphose 
into,  and  become  chemically  altered  to  resemble  another. 

Nomenclature  and  Definitions. 

!"?  Archoplasm,  Archoplasmic  Splicrf. — A  concentrated  region  of  the 
cell  cytoplasm  generally  associated  with  the  centrosome,  and  at 
certain  stages  w^th  the  Golgi  apparatus  elements.  The  archoplasm 
seems  to  have  some  relation  to  the  amphiaster,  but  this  has  not 
been  conclusively  established.  The  sphere  or  archoplasm  is  also 
known  as  the  idiozome  (IMeves)  {-^9),  or,  as  it  is  sometimes  wrongly 
spelt,  "idiosome.", 


Mitochondria,  Golgi  Ajyparahcs,  and   Yolk.  133 

Chondriome  means  the  entire  mitochondrial  content  of  the 
cytoplasm,  or  the  mitochondrial  apparatus  or  complex  looked  upon 
as  a  whole.     This  does  not  include  the  Golgi  apparatus. 

Chromidiuin. — A  granule  or  structure  formed  of  substance 
resembling  the  chromatin  of  the  nucleus  in  its  microchemical 
reactions.  It  is  well  preserved  in  alcohol-acetic  fixation,  and 
stains  in  basic  dyes  like  methyl  green  and  safranin  ;  it  will  not 
impregnate  in  Cajal  or  Kopsch  techniques  {11),  and  goes  blue 
or  green  in  Champy-Kull's  method  {18),  or  green  in  Bensley 
Cowdry  {18). 

Chromatic. — Used  to  describe  any  granule  or  structure  which 
stains  heavily  in  any  dye  (also  chromophile). 

Ghroniatinic. — Used  to  describe  any  granule  or  structure  whose 
microchemical  characteristics  are  so  similar  to  those  of  the  chro- 
matin of  the  normal  nucleus  as  to  lead  to  the  belief  that  it  is 
formed  of  chromatin . 

Chromophobe. — Used  to  describe  any  structure  which  does  not 
stain  by  the  usual  methods. 

Cytoplasmic  Inclusions  refers  to  any  granules  or  rods  included 
within  the  cell  cytoplasm ;  these  may  be  classified  under  two  sub- 
heads as  follows : — 

{a)  Protoplasmic  Inclusions  refers  to  granules  belonging 
to  either  mitochondria  or  Golgi  apparatus,  or  to  isolated 
granules  known  to  be  formed  of  protoplasm  (e.g.  chromatoid 
body  of  cavy  spermatids). 

(h)  Deutoplasmic   Inclusions   refers   to    inert   non-living 
granules,  such  as  fat,  glycogen,  or  yolk,  which  are  incapable 
of  binary  or  multiple  fission,  and  which  are  not  centres  of 
cytoplasmic  activity  in  the  same  way  as  the  protoplasmic 
inclusions. 
Deutoplasmagenesis  is  the  process  of  formation  of  yolk  spheres 
or  discs,  fat,  and  glycogen  within  the  egg  during  oogenesis.     It 
only  includes  the  evolution  of  the  mitochondria  and  Golgi  appa- 
ratus so  far  as  they  are  directly  concerned  with  the  formation  of 
either  yolk,  fat  or  glycogen.     (Also  Vitellogenesis.) 

Golgi  App)aratus. — This  phrase  was  originally  used  for  the 
internal  reticulate  apparatus  in  the  cells  of  nerve  tissue  prepared 
by  a  formalin-silver  nitrate  technique.  It  is  found,  however,^  that 
other  somatic  cells  of  all  kinds,  as  well  as  germ  cells,  contain  an 
apparatus  which  exhibits  the  same  microchemical  reactions  and 
morphological  arrangement  as  the  Golgi  apparatus  in  the  nerve 
ganglion  cells.     The  Golgi  apparatus  has  the  following  reactions  : 

1.  Black  in  Cajal's,  Da  Fano's,  or  Golgi' s  special  formalin 
(uranium  and  cobalt  nitrate,  or  arsenious  acid)  silver  nitrate 
impregnation  methods  {11). 

2.  Black  in  Kopsch's  or  Mann-Kopsch's  osmium  tetroxide 
methods  {18). 


134:  Transactions  of  the  Societij. 

AVitli  regard  to  the  use  of  the  word  Golgi  apparatus,  it  is  neces- 
sary to  point  out  that  in  young  germ  cells  and  in  all  embryonic 
cells  the  apparatus  occupies  a  position  surrounding  the  archoplasm 
and  centrosome,  from  which  the  elements  of  the  apparatus  are 
rarely  separated.  The  word  Golgi  apparatus  we  take  to  mean  all 
the  Golgi  elements  or  dictyosomes  (Perrincito,  So)  en  bloc ;  the 
words  Golgi  element  or  dictyosome  refers  to  a  part  of  the  apparatus 
lying  discrete. 

For  a  much  fuller  treatment  of  the  subject,  see  the  following 
papers  {11-20,  21-2 J^  and  32)  in  the  bibliography ;  also  note  the 
inicrochemical  reactions  explained  on  pages  129  and  135  of  the 
p^'esent  paper. 

IJitocJionchio. — Numerous  grains  or  filaments  scattered  in  the 
cytoplasm,  which  act  as  follows  : — 

.  1.  Eedden   in    acid   fuchsin   after  bichromate  of  potash  and 
osmic  fixation  (11). 

2.  Stain  violet  by  Benda's  method,  red  by  Champy-Kull,  and 
black  in  iron-ha-matoxylin  after  neutral  formalin  or  clu'ome- 
osmium  fixation. 

3.  Do  not  go  Idack  but  red  after  Mann-Kopsch-Altmann,  or 
Kopsch-Altmann ;  do  not  stain  after  Bouin  or  corrosive  acetic,  or 
Petrunkewitsch  or  Carnoy  fixation,  followed  by  Ehrlich's  haema- 
toxylin  or  methyl-blue  eosin  (etc.). 

4.  Stain  intra  vitam  in  Janus  green  and  neutral  red  (IS), 

5.  Either  do  not  stain,  or  are  only  golden  brown  or  greyish, 
after  Cajal's  silver-nitrate  method.  (For  further  details  see 
4,  9-24,  ol,  35,  and  ^2) 

Yolk. — The  woid  has  been  applied  to  any  granular  formations 
of  the  cytoplasm  of  the  egg.  This  usage  must  be  abandoned,  for 
recent  researches  show  that  certain  granules  hitherto  called  yolk 
are  really  true  mitochondria,  similar  to  those  of  ordinary  somatic 
cells.  The  g^^^^  contains  yolk  and  mitochondria  and  Golgi  apparatus, 
the  yolk  being  something  different  from  the  two  latter  protoplasmic 
inclusions.  It  seems  certain  that  part  of  both  mitochondria  and 
Golgi  elements  can  change  into  yolk ;  this  makes  it  difficult  to 
give  a  simple  definition  of  the  word.  In  any  given  species  one 
could  easily  draw  up  a  table  distinctly  showing  the  difterences 
lietween  yolk  and  protoplasmic  inclusions  such  as  the  mitochondria ; 
but  such  a  table  would  not  apply  to  every  other  species,  because 
the  yolk  in  eggs  of  different  species,  even  in  closely  allied  forms, 
may  vary  greatly  in  its  chemical  constitution  and  origin. 

The  main  constituents  of  the  yolk  of  the  hen's  Q^g,  which  has 
been  carefully  examined,  are  protein,  fat  and  lipin,  and  there  is 
little  d<.)ubt  that  tlie  true  yolk  of  invertebrate  eggs  also  consists  of 
protein,  fats,  and  ]i]»ins,  though  not  necessarily  in  the  same  per- 
ci^^ntage. 

While  typical  yolk  spheres  will  be  found  to  consist  of  these 


Mitoclwndria,  Golgi  Apparatiis,  and   Yolk. 


135 


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three  categories  of  substances,  it  is  possible  that  any  one  of  the 
categories  may  be  either  absent  or  reduced  to  a  very  small  quantity. 
Thus  the  yolk  of  the  sponge  Qgg  seems  to  contain  a  very  slight 
amount  of  protein,  as  is  indicated  by  fixing  and  staining  tests.  As 
has  already  been  mentioned,  the  percentage  and  kind  of  fat  may 
vary  also,  even  among  closely  allied  forms.  Many  workers  now 
consider  that  the  mitochondria  are  formed  of  a  protein  substance 
associated  with  a  lipin,  and  microchemical  tests  appear  to  bear  out 
this  assumption.  The  constitution  of  the  Golgi  apparatus  is  pro- 
bably much  like  that  of  the  mitochondria — i.e.  proteid  in  some  way 
linked  with  lipin  materials. 

Any  collection  of  granules  or  discs  within  the  Qgg  cytoplasm 
which  behaves  according  to  a  majority  of  these  tests  may  be  called 
"yolk":— 

1.  Granules  which  do  not  go  red  in  Altmann,  Champy-Kull  or 
Bensley-Cowdry  (i.e.  granules  which  are  not  fuchsinophile).  In 
the  case  of  Champy-Kull,  grains  which  go  blue,  or  in  the  case  of 
Bensley-Cowdry  grains  which  go  green,  are  likely  to  be  chromatin. 
(Insect  yolk,  however,  may  be  fuchsinophile.) 

2.  Granules  which  are  yellowish,  brown  or  black  in  Champy- 
Kull,  Benda,  or  chrome- osmium  fixation,  i.e.  Flemming  or  Her- 
mann's fluids. 

3.  Granules  which  do  not  go  black  after  staining  in  iron- 
haematoxylin,  following  two  days'  fixation  in  neutral  (5  p.c.  to 
20  p.c)  formalin.  (There  are  notable  exceptions  to  this,  e.g.  the 
yolk  of  Amphibia,  which  stains  intensely  in  iron-hsematoxylin.) 

4.  Granules  which  do  not  disappear  after  fixation  in  corrosive 
acetic  acid,  Bouin,  Carnoy  or  Petrunkewitsch.  (These  are  many' 
exceptions  to  this,  e.g.  the  delicate  yolk  of  sponge,  and  some 
mollusc  eggs.) 

5.  Granules,  which  rarely  go  black  in  Mann-Kopsch  or  Kopsch 
(but  which,  if  they  do  go  black,  are  easily  decolorized  by  a  short 
immersion  in  turpentine,  and  are  then  left  as  yellowish  spheres, 
and  not  as  vacuoles)  ;  granules  which  will  not  stain  red  after  such 
extraction  of  their  colour  in  turpentine. 

6.  Granules  which  are  greyish  or  yellowish  intra  vitam  (in 
some  cases,  however,  the  mitochondria  may  be  loaded  with  a 
yellow  pigment). 

7.  Granules  which  do  not  go  black  in  Cajal's  silver  impregna- 
tion method. 

8.  Granules  which  exceed  2//,  in  diameter. 


Yolk-Formation  in  the  Sponge  Grantia. 

Eecently  the  oogenesis  of  Grantia  comprcssa  was  studied  by 
one  of  us  (19),    At  no  period  of  oogenesis  will  the  usual  techniques, 


JOURN.   R.   MICR.  SOC,   1920.    PI.  II, 


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Mitocho7idria,  Golgi  Apparatus,  and  Yolk.  137 

which  demonstrate  the  mitochondria  of  the  sponge  Q^g,  bring  into 
(so  called  chromidia)  evidence  the  yolk  spheres.  In  no  form  could 
one  feel  more  certain  that  the  yolk  spheres  are  not  metamorphosed 
mitochondria.  The  yolk  granules  of  Grantia  are  formed  in  and 
by  the  ground  cytoplasm,  aud  are  of  a  much  more  delicate  nature 
than  the  true  mitochondria.  The  latter,  in  sponge  eggs,  are  so 
large  and  so  few,  that  there  can  be  no  question  of  confusion  of 
yolk  spheres  and  mitochondrial  spheres  at  any  stage  of  oogenesis. 

So  far  as  could  be  ascertained  the  yolk  spheres  of  the  Grantia 
egg  are  of  a  semi-fluid  consistency,  and  possibly  contain  a  small 
amount  of  protein,  but  a  large  bulk  of  lipin.  The  spheres  are 
believed  to  arise  as  small  vacuoles  in  the  ground  cytoplasm  of  the 
endoplasm  of  the  egg.  Techniques  which  depend  for  their  efficiency 
on  the  coagulation  of  protein  are  quite  inadequate  for  the  preserva- 
tion of  the  sponge  yolk,  while  methods  known  to  fix  fat  or  lipins 
are  the  only  ones  suitable  for  the  yolk  of  the  Gra7itia  oocyte.  The 
spheres  in  the  Grantia  oocyte  do  not  go  black  in  osmic  acid,  even 
after  prolonged  immersion  in  strong  solutions. 


Oogenesis  of  Mollusca  (Helix  and  Llmn^ea). 

As  a  simple  type  the  oogenesis  of  a  mollusc  {Limnsea)  may  be 
taken.  Lately  it  has  been  shown  {16)  that  the  ripe  egg  contains 
three  categories  of  granular  or  formed  structures,  viz.  mitochondria,. 
Golgi  elements  and  yolk  spherules.  The  mitochondria  and  Golgi 
elements  appear  to  be  present  in  the  germinal  epithelial  cells, 
though  it  has  been  difficult  to  make  certain  with  regard  to  the 
mitochondria ;  it  is  however  a  fact  that  in  Amphibia  {Bano,  BufOy 
Molge),  Birds  (Gallus),  Mammals  (Mus,  Lepus),  in  other  Mollusca 
{Helix,  Arion),  in  Insecta  {Apanteles,  Sphinx),  the  primitive 
germinal  cells  contain  mitochondria  and  Golgi  apparatus. 

It  has  been  shown  that  in  such  a  mollusc  as  Helix  or  Limnsea 
the  mitochondria  and  Golgi  elements  gradually  spread  out  through- 
out the  oocyte,  and  the  grains  forming  these  systems  increase  in 
number.  It  seems  quite  probable  that  the  diffuse  Golgi  elements 
actively  take  part  in  the  formation  of  yolk  bodies,  as  indicated 
in  PL  II,  fig.  5  ;  we  cannot  say  so  much  in  the  case  of  the  mito- 
chondria. From  a  study  of  a  number  of  Pulmonate  Mollusca  we 
have  concluded  that  much  of  the  evidence  in  these  forms  is  against 
the  view  that  part  of  the  mitochondrial  constituents  of  the  cyto- 
plasm metamorphose  into  yolk.  The  latter  seems  to  form  either 
from  Golgi  elements,  or  per  se  in  the  ground  cytoplasm.  Since  we 
cannot  yet  give  a  definite  opinion  on  this  point,  we  have  taken 
care  to  leave  the  matter  open  in  our  schemes  of  oogenesis  given  on 
page  148  of  this  paper. 


138  Transactions  of  the  Society. 


Oogenesis  of  the  Mollusc  Patella. 

Patella  is  the  common  sea-limpet ;  a  study  of  the  oogenesis  of 
this  mollusc  shows  that  the  formation  of  the  yolk  is  a  more  com- 
plicated process  than  is  the  case  with  another  mollusc  such  as 
Helix  (the  snail)  or  Limna^a.  Just  as  in  Helix  the  youngest 
oocytes  contain  a  typical  Golgi  apparatus  formed  of  discrete  rods 
(dictyosomes)  and  a  group  of  mitochondria.  While  in  Helix  the 
Golgi  apparatus  spreads  out  through  the  egg  cytoplasm,  and 
becomes  an  important  contributor  to  the  number  of  formed  bodies 
of  the  Qgg,  the  Golgi  apparatus  in  Patella  is  from  the  first  begin- 
ning of  deutoplasmagenesis  a  much  more  important  part  of  the 
two  protoplasmic  inclusions  (mitochondria  and  Golgi  apparatus)". 
Kot  only  do  the  Golgi  elements  surpass  tlie  mitochondria  in  their 
growth  activities,  but  many  of  them  become  associated  in  some 
way  with  the  yolk  spheres.  This  is  to  say,  that  however  the  yolk 
spheres  may  be  formed,  be  it  from  the  mitochondria,  archoplasm, 
or  simply  in  the  ground  cytoplasm,  the  Golgi  elements  later  become 
stuck  upon  the  surface  of  many,  if  not  all,  of  the  yolk  spheres,  and 
form  a  most  important  part  of  the  yolk  substance. 

The  important  point  to  note  is  that  in  two  molluscs.  Helix  and 
Patella,  the  Golgi  apparatus  in  each  case  differ  a  good  deal  in  the 
extent  in  which  they  take  direct  part  in  the  formation  of  true  yolk 
bodies.  We  believe  that  in  the  case  of  Patella  the  Golgi  apparatus 
provides  most  of  the  yolk  spheres  of  the  full-grown  egg,  but  in 
Limmea  either  the  mitochondria  (or  the  ground  cytoplasm)  are 
most  active  in  this  respect. 

In  PI.  II,  figs.  6  and  7,  we  have  given  figures  representing  the 
staining  changes  which  come  over  the  Golgi  element  (stained  with 
OSO4)  or  the  mitochondrium  (stained  in  acid  fuchsin  after  chrome- 
osmium  fixation)  during  their  metamorphosis  into  yolk  bodies. 

Oogenesis  in  Amphibia  and  Insecta. 

In  some  ways  the  oogenesis  of  Amphibia  typified  by  Rana  or 
Triton  (Molge),  and  of  Insecta  by  Apanteles  and  Dytiscns,  presents 
the  same  general  features.  The  mitochondria  increase  in  number 
and  tend  to  form  a  filamentous  mass  on  the  peripheral  part  of  the 
growing  oocyte.  When  deutoplasmagenesis  begins  the  yolk  discs 
appear  at  the  periphery  of  the  egg,  in  the  mitochondria,  but  though 
the  mitochondria  may  lie  towards  the  centre  of  the  oocyte,  or 
entirely  spread  throughout  the  oocyte,  the  yolk  discs  appear  at  the 
periphery.  We  have  observed  this  also  in  the  oocyte  of  the 
sparrow  {Passer  domesticus). 

Note. — (1)  The  yolk  discs  of  insects  and  amphibians  appear  at 
the  periphery  of  the  Qgg  where  mitochondria  happen  to  lie ;  and 


Mitochondria,  Golgi  Apimratus,  and   Yolk.  139 

(2)  yolk  discs  do  not  appear  in  the  inner  regions  of  the  egg  till 
later,  even  though  these  regions  may  contain  abundant  mito- 
chondria. 

It  seems  natural  to  conclude  that  the  yolk  grains  of  the  egg 
are  formed  from  metamorphosed  mitochondria,  as  is  believed  to 
occur  in  other  animals.  It  should  be  mentioned  that  in  both 
insects  and  amphibians  the  mitochondrial  elements  become  so  fine 
that  it  is  difficult  to  tell  whether  the  yolk  is  being  formed  from 
them  or  not. 

In  preparations  of  frog  ovary  by  the  Mann-Kopsch  method  {18) 
the  mitochondria  of  the  oocyte  impregnate  in  a  different  manner 
from  the  yolk, 'and  no  certain  transitional  forms  between  the 
mitochondria  and  the  yolk  can  be  noted.  We  consider  that  the 
matter  is  not  settled. 

By  the  Mann-Kopsch  method  the  full-grown  frog  oocyte  cyto- 
plasm is  found  to  contain  enormous  numbers  of  granules  which 
fall  into  three  categories,  according  to  the  manner  in  which  they 
act  in  the  osmium  tetroxide.  There  are,  firstly,  fine  evenly  sized 
grains  which  go  brownish  to  black ;  these  have  been  identified  as 
the  mitochondria.  There  are,  secondly,  the  very  large  yolk  bodies, 
which  go  yellowish ;  then  one  finds  intermediate  forms  which  go 
black  in  the  osmium  solution.  These  granules  intermediate  in 
size  may  be  derived  from,  and  represent,  the  Golgi  apparatus  of 
the  frog  oocyte.  Sufficient  work  on  this  problem  has  not  been 
carried  out  to  enable  us  to  make  quite  certain  as  to  the  identity 
and  origin  of  the  intermediate  or  black  granules,  and  as  to  whether 
the  large  yolk  granules  and  the  smaller  mitochondria  are  in  any 
way  related  to  the  black  granules. 

The  granules,  hitherto  called  *'  yolk,"  are  in  the  case  of  the 
frog  oocyte  of  at  least  three  different  kinds,  whose  histo-chemical 
reactions  are  different  in  each  case. 

About  twelve  years  ago  Lams  (27)  carried  out  some  w^ork  on 
the  formation  of  the  "  vitellus  "  of  the  amphibian  egg.  Lams 
used  no  Golgi  apparatus  method,  and  he  did  not  go  very  deeply 
into  the  question  as  to  whether  the  mitochondria  metamorphose 
into  yolk.  In  the  oogonium  Lams  finds  an  archoplasm  contain- 
ing a  centrosome  and  surrounded  by  a  halo  of  mitochondrial 
substance.  During  growth  the  mitochondria  multiply  with  the 
archoplasm  as  their  centre,  so  that  the  former  become  surrounded 
by  a  thick  mass  of  mitochondria.  The  archoplasm  Lams  calls  the 
yolk  body  (corps  vitellin),  and  the  mitochondrial  cloud  he  calls 
the  yolk-forming  mass  (masse  vitellogene),  believing  that  the  mito- 
chondria of  the  frog  are  in  some  way  connected  with  the  formation 
of  the  yolk. 

We  have  gone  into  the  subject  of  the  behaviour  of  the 
mitochondria  in  the  oogenesis  of  the  Amphibia.  What  Lains 
describes  with  regard  to  the  evolution  of  the  mitochondria  is  in 


140  Transactions  of  the  Society. 

accordance  with  our  own  observations  ;  but  we  differ  as  to  inter- 
pretations. The  archoplasm  has  no  direct  connexion  with  the 
formation  of  the  yolk,  though  we  recognize  that  it  is  in  the  region 
of  the  archoplasm  that  the  mitochondria  are  found  and  grow  most 
rapidly ;  this  however  does  not  allow  us  to  conclude  that  the 
archoplasm  may  be  called  a  vitelline  body,  or  that  it  grows  or 
behaves  in  a  way  which  resembles  the  true  yolk  nucleus  of  an 
Ascidian.  While  we  acknowledge  that  the  mitochondria  form  an 
elongate  matted  body  in  the  region  of  the  archoplasm,  during  one 
period  of  the  oogenesis,  it  is  extremely  doubtful  whether  this  body 
should  be  homologized  with  the  Ascidian  yolk  nucleus.  We  con- 
clude that  there  is  not  satisfactory  evidence  that  a  true  "  yolk 
body  "  or  "  nucleus  "  exists  in  Amphibia. 

This  temporary  conclusion  is  in  agreement  with  the  view 
expressed  by  Dubuisson  (7),  with  whose  work  Lams  disagrees. 

In  insects  such  as  Steiiohothrus,  the  Golgi  elements  appear  to 
be  separate  from  the  yolk.  In  Dtjtiscus,  ISTusbaum-Hilarowitz  (31) 
has  shown  that  the  Golgi  apparatus  and  the  formation  of  yolk 
spheres  are  unconnected  with  each  other.  In  Dytiscus  with 
Champy-Kull's  method  the  yolk  spheres  are  fuchsinophile  (see 
page  136).  We  have  lately  seen  some  of  Mr.  L.  Hogben's  prepara- 
tions of  Periplaneta  ovaries,  from  which  it  seems  clear  that  some, 
at  least,  of  the  yolk  sj^heres  of  the  cockroach  ^gg  are  formed  within 
the  nucleus,  possibly  from  the  nucleoli,  and  finally  shot  out  into 
the  egg  cytoplasm. 

Formation  of  Yolk  in  Ascidian  Oogenesis. 

According  to  Hirschler  (£?)  yolk  granules  of  Ascidian  ova  are 
formed  by  two  processes  : — 

(1)  A  simple  metamorphosis,  and  enlargement  of  the  mito- 
chondrium  to  form  a  new  body,  and  (2)  a  secondary  fusion  of 
many  of  the  Golgi  elements  with  these  swollen  mitochondria,  to 
form  a  compound  structure,  and  a  swelling  up  of  the  Golgi  elements 
themselves. 

He  tells  us  ''  that  the  yolk  spherules*  which  represent  the 
reserve  material  of  the  developing  embryo  consist  of  mitochondrial 
and  Golgi  apparatus  substance.  During  embryonic  development 
a  more  vigorous  growth  and  regeneration  of  the  apparatus,  and 
perhaps  of  the  mitochondrial  substance,  also  very  probably  takes 
place,  as  the  investigations  of  Van  der  Stricht  on  Noctula  would 
suggest.  This  regeneration  would,  as  we  suppose,  come  about  in 
the  following  manner: — The  yolk  gives  off  the  apparatus  and 
mitochondrial  structures  present  in  small  quantity  in  the  dividing 
Qgg  cell,  so  that  the  dissolution  and  using  up  of  the  yolk  during 
embryonic  development  would  thus  in  great  part  be  attributed  to 
the  giving  off  of  these  substances." 


Mitochondria 


Mitochondria,  Golgi  Api^aratus,  and   Yolk.  141 

Thus  Hirschler  thinks  that  the  swollen  mitochondria  (i.e.  yolk) 
may  shrink  to  their  original  size  during  the  development  of  the 
egg,  and  so  again  come  under  the  category  of  mitochondrial  sub- 
stance. 

Oogenesis  of  Ascaris. 

Hirschler  {^1)  finds  a  Golgi  apparatus  and  mitochondria  in  the 
young  oocytes  of  Ascaris,  The  mitochondria  occasionally  swell  up 
to  form  the  large  yolk  granules  of  the  older  eggs.  The  Golgi 
apparatus  segments  may  lie  close  to  the  yolk  spheres,  but  do  not 
generally  become  intimately  associated  with  them.  The  mito- 
chondria and  Golgi  elements  are  throughout  separate  entities. 
Hirschler  also  describes  true  fat  granules  in  the  ground  cytoplasm. 
His  interpretations  may  be  graphically  shown  thus  : — 

ASCARIS. 
Oogonium.  Full-grown  Oocyte. 

-^  Definitive  mitochondria. 

-^  Yolk  spheres. 

Golgi  apparatus ^  Golgi  apparatus. 

Ground  cytoplasm >-Fat  vacuoles. 

Subsequently  to  Hirschler's  observations,  Faure-Fremiet  carried 
out  an  exhaustive  research  on  AscmHs  {10).  Faure-Fremiet  did 
not  seem  to  have  known  of  Hirschler's  work,  and  the  interpreta- 
tions of  the  former  author  cannot  be  accepted  completely  by  us. 
Faure-Fremiet  describes  the  young  oocytes  as  containing  mito- 
chondria (chondriokontes),  vacuoles  of  phosphate  substance,  and 
fat-globules.  He  recognizes  no  Golgi  apparatus.  He  says  :  "  As 
have  been  explained  above,  a  part  of  the  chondriome  (mitochondrial 
constituents  of  the  cytoplasm)  of  the  oocytes  of  Ascaris  become 
transformed  into  special  elements  comparable  to  certain  '  Neben- 
kerne.'  "  Faure-Fremiet  here  means  the  "  nebenkern  "  of  the  snail 
spermatocyte,  which  we  know  now  to  be  a  true  Golgi  apparatus — 
see  Perrincito  {33)  and  {16-20,  20-4,  and  42).  Hirschler  (21) 
previously  showed  that  the  Golgi  apparatus  (or  "  nebenkern  ")  of 
Ascaris  is  not  related  to  the  mitochondria.  Faure-Fremiet  is 
wrong  in  his  interpretation  of  these  elements  in  the  Ascaris  egg, 
and  we  prefer  Hirschler's  interpretation. 

The  Golgi  Apparatus  of  the  Mammalian 
Ovary  and  Testis. 

The  cells  of  the  mammalian  ovary,  like  those  of  invertebrate 
ovaries,  contain  a  typical  Golgi  apparatus,  demonstrable  either  by 


142 


Transactions  of  the  Society. 


Cajal's  method,  or  by  the  Mann-Kopsch  method.  (Text-fig.  1, 
Del  Kio  Hortega  {36),  which  shows  the  apparatus  in  the  o5cytes, 
follicle  cells,  and  germinal  epithelium  of  the  rabbit  and  cavy 
(fig.  2).) 


--■-^A£ 


^     Ap 


Text-Figures  1,  2,  3,  4. 

Pij^  1.— Part  of  the  ovary  of  the  rabbit  prepared  by  Cajal's  Golgi  apparatus 
raethod,  showing  the  apparatus  in  the  germinal  epithelium  (GAE),  and  in  oocytes 
at  different  stages  :  0,  GAO,  GAO.  At  0  is  a  very  young  oocyte  showing  the 
Golgi  apparatus  in  its  excentric  position  ;  in  the  oocyte  at  ON  the  follicle  (FN)  is 
well  formed,  and  each  nucleu=;  has  a  Golgi  apparatus  outside  it ;  the  oocyte  is 
surrounded  by  a  zona  pellucida,  and  the  apparatus  consists  of  branched  threads 
lying  through  the  cytoplasm  (GAO).     After  llio  Hortega  (36). 

Pig^  2. Young  oocytes  of  the  guinea-pig,  drawn  at  a  higher  magnification  to 

show   the  Golgi  apparatus  at  GAO,  and  the  nucleolinus  (?)  at  NI.      After  Rio 

Hortega.  ^  .     .-i 

j^-'ig,  3.— Oocyte  of  Canis,  showing  inside  the  nucleus  the   "  filament  spiroide 

intranucleaire,"  which   may  be  another  form  of  the  nucleolinus  (page  130,  and 

Compare  PI.  II,  fig.  9,  NO);  FN  =  follicle.     After  Kio  Hortoga. 

jj^ig,  4.— Young  oocyte  of  man,  showing  the  mitochondria  (M),  the  archoplasm 

at  AR,  vacuoles  at  V,  and  the  enigmatic  rod-like  body  at  AB.    FN  =  follicle.    After 

Marie  Loyez  (2S). 


Mitochondria,  Golgi  Apparatus,  and   Yolk.  143 

lo  the  oocyte  tlie  apparatus  is  at  first  juxta-nuclear  and 
eccentric,  but  later  spreads  out  throughout  the  egg  cytoplasm. 
The  elements  of  the  Golgi  apparatus  are  somewhat  filamentary 
and  branched,  and  possibly  take  no  direct  part  in  the  formation  of 
fat  or  yolk.  From  our  preparations  of  guinea-pig  testis,  both 
by  Cajal  and  the  Mann-Kopsch  methods,  we  believe  that  the 
mammalian  Golgi  apparatus,  like  that  of  certain  invertebrates, 
consists  of  numerous  semi-lunar  plates  or  rods  and  not  of  branched 
straight  bodies  as  drawn  by  Hortega.  The  appearance  shown  in 
Text-figs.  1  and  2  of  such  branched  rods  is  possibly  due  to  the 
distortion  caused  by  the  formalin  fixation.  In  all  probability 
further  v/ork  will  show  that  the  Golgi  apparatus  in  mammalian 
oocytes  is  formed  of  small  curved  plates  and  rods  which  may 
occasionally  join  together  in  chains  to  produce  a  reticular  or 
branched  appearance.  In  PL  II,  figs.  2  and  3,  are  a  sperma- 
tocyte and  a  spermatid  showing  the  Golgi  apparatus  (GA). 


On  the  Supposed  Metamorphosis  of  Mitochondria 
INTO  Fat  Vacuoles. 

Dubreuil  {8)  and  Murray  {30)  showed  that  mitochondria  could 
metamorphose  into  bodies  possessing  the  histo-chemical  reactions 
of  fat.  The  elongate  mitochondrium  in  this  case  becomes  swollen 
parts  of  its  length,  and  finally  forms  one  or  more  separate  fat 
spheres.  It  may  be  remembered  that  in  degeneration  of  medul- 
lated  nerve,  the  lipin  substances  in  the  sheath  become  changed 
into  fat.  The  fat  globules  which  appear  in  mammalian  and  other 
oocytes  during  oogenesis  may  be  formed  partly  by  a  metamorphosis 
of  the  lipin  substance  in  the  mitochondria,  but  it  would  be  a 
mistake  to  consider  that  the  fat  of  cells  is  exclusively  produced  by 
changes  in  mitochondria. 

In  the  case  of  digestion  there  seems  little  doubt  that  the 
mitochondria  take  no  direct  part  in  the  production  in  the  cells  of 
fat.  Food  matter  containing  the  latter  is  acted  upon  by  a  lipase 
which  breaks  up  the  fat  into  glycerol  and  fatty  acid,  in  which  form 
it  passes  through  the  membrane  of  the  intestines,  in  whose  cells  it 
is  reconverted  into  fat.  Such  fat  ultimately  becomes  distributed 
by  the  blood,  and  is  taken  up  into  connective  tissue  and  other 
storage  cells.  There  seems  no  reason  for  disbelieving  that  oocytes 
could  take  up  fat  in  a  similar  manner,  and  independently  of  the 
mitochondria. 

With  reference  to  the  formation  of  fat  in  cells,  we  may  give 
some  account  of  Schreiner's  work  on  the  subcutaneous  cells  of 
Myxine  (39).  He  describes  a  most  complicated  process  in  these 
cells ;  their  nuclei  contain  a  nucleolus  or  several  nucleoli,  which 
bud  off  smaller  bodies,   and  these   become  separate  as   "  neben- 


144  Transactions  of  the  Society. 

nucleolen."  These  secondary  nucleoli  pass  through  the  nuclear 
membrane  into  the  cell  cytoplasm,  and  ultimately  give  rise  to 
chondriokontes  or  plasma  rodlets.  The  latter  appear  to  be  true 
mitochondria,  and  soon  segment  to  form  "secondary  granules," 
which  swell  up  to  form  fat  globules.  The  latter  part  of  this 
account  agrees  fully  with  the  work  of  Murray  and  Dubreuil,  but 
the  former  part — i.e.  that  referring  to  the  formation  of  the  secondary 
nucleoli  and  their  passage  into  the  cell  cytoplasm — has  not  yet  been 
confirmed  by  other  observers.  We  should  like  to  know  whether 
the  subcutaneous  cells  before  their  metamorphosis  into  fat  cells 
do  not  already  contain  mitochondria. 

It  should  be  noted  that  Schreiner  has  used  the  latest  cytological 
methods,  and  for  this  reason  alone  his  views  demand  attention. 
(See  p.  154.) 

The  Archoplasm  and  the  Formation  of  Yolk 
FROM  GoLGi  Elements. 

In  the  undifferentiated  cell,  such  as  a  spermatogonium  or  an 
oogonium,  the  Golgi  apparatus  consists  of  a  number  of  rods  stuck 
upon  the  surface  of  the  archoplasm  or  condensed  protoplasmic 
substance  surrounding  the  centrosome. 

In  Limn^a  or  Helix  (16)  the  Golgi  apparatus,  during  oogenesis, 
spreads  out  through  the  cytoplasm,  its  individual  units  increasing 
greatly  in  number  (PL  II,  fig.  5).  During  this  process'  it  seems 
probalDle  that  the  original  archoplasm  becomes  divided  out  among 
the  various  Golgi  elements  or  dictyosomes,  so  that  finally  each 
little  group  of  two  to  four  or  five  Golgi  rodlets  reposes  on  a  part 
of  the  much-divided  archoplasm.  In  Limnma  this  archoplasmic 
substance  can  be  traced  back  to  the  original  archoplasm  of  the 
oogonium.  In  the  subsequent  cleavage  of  the  Qgg  there  comes  a 
time  when  the  Golgi  elements,  hitherto  scattered  haphazardly  in 
the  cytoplasm  of  the  blastomeres,  finally  take  up  their  position 
near  the  nucleus,  and  in  an  excentric  position.  The  archoplasm 
of  each  daughter  blastomere  is  therefore  regenerated  from  a  part 
of  the  original  archoplasm  of  the  oogonium  which  gave  rise  to  the 

egg  {10)- 

But  now  when  we  turn  to  the  oogenesis  of  Patella  or  an 
ascidian  we  discover  a  further  complication.  In  Patella  and  the 
ascidians  the  Golgi  apparatus  is  undoubtedly  associated  more  or 
less  directly  with  deutoplasmagenesis.  From  the  observations 
we  have  made  on  the  oogenesis  of  Patella  it  seems  certain  that 
the  Golgi  elements  are  directly  stuck  upon  the  surface  of  spheres 
whose  chemical  reactions  are  those  of  true  yolk. 

We  then  enquire  as  to  the  fate  of  the  archoplasm  in  these 
cases.  Do  the  yolk  spheres  represent  the  archoplasm  loaded  with 
food  substances,  or  has  the  original  archoplasm  degenerated  or 


Mitoclwndria,  Golgi  Aijparatus,  and   Yolk.  145 

parted  company  with  the  Golgi  rodlets  or  dictyosomes  ?  We  are 
inclined  to  believe  that  the  original  archoplasm  may  have  become 
loaded  with  lipins  and  fats  and  thus  metamorphose  into  yolk 
elements. 


Basophility  and  Oxyphility  of  the  Ground  Cytoplasm 
DURING  Oogenesis. 

Pari  passu  with  the  evolution  of  the  mitochondria  and  Golgi 
apparatus  of  the  growing  oocyte,  there  may  occur  changes  in  the 
chromophility  of  the  egg  cytoplasm ;  probably  there  is  some 
definite  relationship  between  the  ground  cytoplasm  and  of  the 
degree  of  spreading  out  and  development  of  the  protoplasmic 
inclusions.  More  possibly,  however,  the  relation  is  between  the 
nucleus  itself  and  the  surrounding  cytoplasm.  Hirschler  has 
noted  important  changes  in  the  chromophility  of  the  egg  cytoplasm 
during  the  growth  of  the  ascidian  oocyte.  In  different  growth 
stages  the  ground  plasma  shows  a  very  variable  staining,  from 
which  it  may  be  concluded  that  during  growth  of  the  ovum  it 
undergoes  far-reaching  metabolic  changes. 

Hirschler  distinguishes  three  chief  conditions  of  staining: — 
<1)  primary  oxyphilia,  (2)  basophilia,  and  (3)  secondary  oxyphilia. 
He  believes  that  the  Golgi  apparatus  may  in  some  way  be  con- 
cerned with  the  passage  of  the  chromophility  of  the  cytoplasm 
from  oxyphile  to  basophile,  and  considers  that  the  nucleus  is  not 
directly  concerned  with  the  process. 

The  exact  significance  of  changes  in  chromophility  of  the  Qgg 
cytoplasm  are  unknown  to  us,  but  may  indicate  something  of  the 
growth  metabolism  of  proteid  substances. 


Yolk  Nuclei. 

Wilson  {JfJf)  says,  "  During  the  growth  period  (of  an  egg)  a 
peculiar  body  known  as  the  yolk  nucleus  appears  in  the  cytoplasm 
of  many  ova,  and  this  is  probably  concerned  in  some  manner  with 
the  growth  of  the  cytoplasm  and  the  formation  of  the  yolk.  Both 
its  origin  and  its  physiological  role  are,  however,  still  involved  in 
doubt." 

Many  authors  have  loosely  used  the  word  ''  yolk  nucleus  "  to 
mean  any  largish  granule  which  they  have  noticed  in  the  egg 
cytoplasm.  The  archoplasm  and  mitochondria  have  both  been 
erroneously  identified  as  "  yolk  nuclei."  That  there  may  be  such 
a  body  as  a  true  yolk  nucleus,  distinct  from  any  other  known 
cytoplasmic  inclusion,  cannot  be  doubted. 

Hirschler  (^^)  finds  a  true  yolk  nucleus  which  stains  like  the 
mitochondria  during  the  early  stages  of  its  development.     In  the 

l 


146  Transactions  of  the  Society, 

youngest  ascidian  oocytes  Hirschler  describes  the  presence  of  two 
granular  bodies  —one  fuchsinophile,  which  is  the  chondriome  (i.e. 
the  representative  of  the  mitochondria  of  the  cell) ;  the  other  stained 
black  by  osmium  tetroxide,  and  forming  the  primordium  of  the 
Golgi  apparatus  of  the  egg.  From  the  former,  which  Hirschler 
calls  the  chondriome,  develop  both  yolk  nucleus  and  definitive 
mitochondria.  AVith  regard  to  Hirschler's  use  of  the  term  "  chon- 
driome," the  word  here  means  the  entire  content  of  mitochondrial 
substance  in  the  cell,  whether  a  single  grain,  or  many  grains 
collectively,  and  this  meaning  is  the  one  in  which  most  French 
observers  have  used  the  word. 

Hirschler  says,  "  One  can  suppose  that  the  small  red  (fuchsino- 
phile) yolk  nuclei  of  the  young  oocytes,  even  alone  on  account  of 
their  specific  staining  affinities,  represent  the  chondriome  of  these 
cells,  and  that  during  the  cell  growth,  out  of  this  chondriome, 
which  consists  of  small  mitochondrial  bodies,  are  produced  on  the 
one  hand  small  granular  mitochondria,  and  on  the  other  hand  the 
peculiar  substance  of  the  yolk  nucleus.  In  this  view,  the  yolk 
nuclei  would  be  regarded  as  derivatives  of  the  chondriome,  and 
such  an  interpretation  would  then  harmonize  with  the  accounts 
given  in  the  literature.  But  by  simply  looking  at  the  facts  alone, 
it  seems  that  the  mitochondria  and  the  yolk  nuclei  have  a  common 
origin,  and  develop  out  of  fuchsinophile  spherical  bodies,  which 
represent  at  the  same  time  mitochondria  and  the  youngest  stages 
of  the  yolk  nuclei." 

Following  out  the  history  of  the  yolk  nucleus  of  ascidian  eggs, 
Hirschler  remarks,  "  As  long  as  the  yolk  nuclei  exhibit  a  red  or 
reddish  staining  (fuchsin)  they  appear  for  the  most  part  as  com- 
pact spherules  which  are  directly  applied  to  the  nuclear  membrane. 
Later,  however,  the  mitochondrial  substance  is  given  off  from 
them,  and  they  change  their  form  and  structure  quite  considerably 
in  older  oocytes." 

A  kind  of  capsule  becomes  formed  around  the  periphery  of  the 
growing  yolk  nucleus,  while  the  interior  of  the  latter  gradually 
comes  to  stain  in  the  same  way  as  the  ground  cytoplasm.  Hirschler 
continues,  '*  But  before  the  yolk  nuclei  have  received  their  capsular 
form,  quite  peculiar  stalks  develop  out  of  their  substance,  by  which 
they  are  attached  to  the  nuclear  membrane.  Usually  a  yolk 
nucleus  possesses  only  one  stalk,  but  some  have  two  or  even 
three."  These  stalks  are  intimately  related  to  the  nuclear  mem- 
brane and  thence  to  the  chromatinic  reticulum.  Hirschler  says 
with  reference  to  the  latter  fact,  "  One  could  suppose  that  through 
these  stalks  certain  nuclear  substances  are  led  in  a  fluid  state 
through  the  nuclear  membrane  into  the  yolk  nucleus  and  promote 
the  growth  of  the  latter."  In  support  of  this  view  Hirschler  states 
that  he  finds  granules,  possibly  chromatin,  lying  in  the  substance 
of  the  yolk  nucleus. 


Mitocliondria,  Golgi  Apparatus,  and   Yolk.  147 

Later  tlie  yolk  nucleus  (or  nuclei)  disappear  without  leaving  a 
trace.     (See  also  page  139.) 

Sufficient  work  has  not  been  carried  out  in  the  light  of  the 
newer  interpretations  of  the  inclusions  of  the  cytoplasm  to  enable 
us  to  take  a  satisfactory  survey  of  the  conditions  leading  to  the 
formation  of  the  "  yolk  nuclei "  in  forms  such  as  the  arthropod  or 
the  vertebrate.  In  mammals  the  archoplasm  has  long  been  known 
as  the  "  yolk  body  of  Balbiani,"  but  probably  in  no  mammal  does 
the  archoplasm  form  true  yolk.  The  "  yolk  nucleus  "  of  the  spider 
egg  or  the  ascidian  appears  to  be  different  from  the  archoplasm. 


Graphic  Eepresentation  of  the  Formation  of  the 
"Yolk"  in  Various  Forms. 

In  the  following  section  we  have  attempted  to  represent 
graphically  the  manner  of  formation  of  the  yolk  and  associated 
bodies  in  several  forms.  We  recognize  several  grades  of  progres- 
sive complexity.  At  one  end  we  find  such  a  case  as  Grantia,  where 
the  yolk  is  formed  as  vacuoles  in  the  ground  cytoplasm,  and  where 
neither  mitochondria  nor  Golgi  apparatus  take  direct  part  in  the 
production  of  yolk ;  at  the  other  end  we  find  such  an  example  as 
the  ascidian,  where  the  formation  of  the  ''  yolk  "  is  extraordinarily 
complex.  Intermediate  forms  are  found  in  Patella,  and  possibly 
Bana.  Such  a  mammal  as  Lepus  is  specialized  and  simplified  : 
the  mitochondria  may  contribute  to  the  formation  of  fat,  while 
the  Golgi  apparatus  does  not  appear  to  be  altered. 

These  grap)]iic  representations  are  based  on  observations  which 
in  some  cases  are  at  'present  difficult  to  prove  or  disprove,  and  to 
lohich  future  work  may  lend  a  different  interpretation.  In  each 
case  we  begin  in  the  oogonium  with  Golgi  elements  and  mito- 
chondria, and  by  the  time  the  oocyte  has  become  full  grown  the 
latter  bodies  may  metamorphose  in  a  most  complicated  manner,  or 
they  may  simply  have  grown  in  bulk  or  in  the  number  of  their 
individual  parts,  without  having  become  loaded  with  food  sub- 
stances which  would  cause  them  to  be  classified  as  "  yolk." 

PORIFERA. 

Grantia  compressa. 
Oogonium.  Full-grown  Oocyte. 

Mitochondria — — ^  Mitochondria. 

(Ground  cytoplasm) >- Yolk  spheres. 

Golgi  apparatus — -->  Golgi  apparatus. 

L    2 


148 


Transactions  of  the  Society. 


Oogonium. 
Mitochondria- 


MOLLUSCA. 
Helix,  Limnxa,  etc. 


Oolgi  apparatus- 
Mitochondria — 


Full-grown  Oocyte. 
>  Mitochondria. 


Yolk  spheres. 


>-  Golgi  apparatus. 


Patella  vulgaris. 


■>  Mitochondria. 


Yolk  spheres  associated  with 
Golgi  elements. 


Golgi  elements  and  archoplasm 


■^ 


-^  Definitive  Golgi  apparatus  with 
unchanged  archoplasm. 


ASCIDIA. 


Mitochondrium  (chondriome) 


Definitive  mitochondria. 


Yolk  spheres. 


Yolk  nucleus  7( 

(soon  disappears) 


Golgi  apparatus- 


■>  Definitive  Golgi  apparatus. 


Golgi  apparatus  associated 
with  yolk  spheres. 

MAMMALIA  (like  Leyus). 

^  Definitive  mitochondria. 


Mitochondria" 


->Fat. 


Golgi  apparatus- 


Ground  cytoplasm  (?] 


Mitochondria: 


Golgi  apparatus- 


->■  Definitive  Golgi  apparatus. 
.->-    Scanty  yolk. 
>     Fat 

INSECTA  (Apanteles). 

^  Definitive  mitochondria. 

'  >  Yolk. 


■>  Golgi  apparatus 


Nucleus  (nucleolus) 


->■  Secondary  nuclei. 


Mitocliondria,  Golgi  Apimratm,  and   Yolk.  149 

Then  possibly  the  nucleoli  may  produce  "  yolk  "  (Periplaneta ; 
page  140)  in  certain  insects. 

AMPHIBIA  (Raoia). 
Oogonium.  Full-grown  Oocyte. 


Mitochondria: 


._^  Definitive  mitochondria. 
-->  Yolk  bodies. 


Golgi  apparatus >  Golgi  apparatus  yolk 

(i.e.  apparatus  elements 
slightly  enlarged). 

On  the  Fate  of  the  Mitochondrial  and  the  Golgi 
Apparatus  Yolk  Body  during  Embryogeny. 

The  mitochondria  can  metamorphose  into  fat  spheres  or  yolk 
bodies  during  oogenesis.  This  probably  means  that  the  proto- 
plasmic substratum  which  forms  the  basis  of  the  mitochondrium^ 
or  which  in  the  case  of  the  Golgi  apparatus  is  possibly  the  archo- 
plasm,  becomes  loaded  with  fatty  substance,  phosphorized  or 
otherwise.  This  metamorphosis  leads  to  the  granules  in  question 
becoming  inert,  and  chromophobe  with  most  dyes. 

Now,  during  organogeny  the  yolk  bodies  are  drawn  upon  to 
provide  the  energy  for  development,  and  they  become  smaller  and 
smaller.  A  question  is  whether  the  yolk  granule  formed  from  the 
mitochondrium,  or  from  a  part  of  the  Golgi  element,  changes  back 
to  its  former  state,  or  again  metamorphoses  into  a  protoplasmic 
granule  ?  This  is  a  point  to  the  elucidation  of  which  future  work 
on  the  minute  cytology  of  the  embryonic  tissues  alone  can  give  an 
answer.  „ 

Chromidia  in  Metazoan  Oogenesis. 

The  word  "  chromidium  "  is  used  by  protozoologists  to  mean  a 
small,  generally  "solid"  body,  composed  of  true  chromatin  and 
lying  in  the  cytoplasm  of  the  cell.  In  Arcella,  for  instance,  the 
presence  of  true  chromatinic  chromidia  at  certain  stages  in  the  life 
cycle  of  this  protist  cannot  be  doubted.  As  Dobell  has  noted  in 
his  paper  (6),  workers  on  metazoan  cytology,  of  whom  Popoff  is  an 
example,  have  erroneously  identified  various  structures  as  true 
chromidia ;  Popoff  identifies  what  we  now  know  to  be  the  Golgi 
apparatus  of  the  Mollusc  spermatocyte  as  the  chromidia  (34)' 

Many  workers  on  oogenesis  have  wrongly  identified  the  egg 
mitochondria  as  chromidia  :  *  this  misinterpretation  has  been  due 

*  Can  chromidia  metamorphose  into  mitochondria  ?  Does  the  plasmosome 
of  the  nucleus  arise  from  chromatin,  and  can  nucleolar  substance  give  rise  to 
mitochondria  ?  These  questions  are  all  more  or  less  intimately  related,  and  still 
unanswered. 


150  Transactions  of  the  Society. 

to  the  fact  that  few  cytologists  take  the  trouble  to  examine  care- 
fully the  fixing  and  staining  properties  of  those  bodies  which  they 
call  "  chromidia."  Jorgensen  (^26),  in  a  paper  on  the  oogenesis  of 
Grantia  comj^ressa,  calls  the  mitochondria  "  chromidia."  Dendy  (o) 
has  followed  Jorgensen,  and  by  both  authors  the  sperm  middle 
piece  is  called  a  "  chromidium,"  though  it  should  be  noted  that 
these  observers  were  not  aware  that  the  body  they  described  was 
the  spermatozoon  (see  paper  (19) ). 

Nearly  all  cytologists  use  some  form  of  iron  alum  hsematoxylin 
for  staining^.  While  we  disas^ree  with  the  statement  that  such 
h?ematoxylin  stains  cannot  be  relied  upon,  it  is  true  that  these 
methods  tinge  a  black  or  grey-blue  colour  many  different  cell 
bodies.  To  fix  a  tissue  in  ordinary  Flemming  and  to  stain  in  iron 
liaematoxylin,  and  then  to  describe  in  such  preparations  any  blackly 
stained  granule  as  chromatin  or  a  "  chromidium,"  is  unjustifiable  ; 
to  describe  any  cell  substances  which  stain  basiphil  in  the  so-called 
chromatin  or  nuclear  dyes  as  chromatin  is  equally  unjustifiable, 
yet  perusal  of  cytological  work  carried  out  by  many  zoologists  will 
show  that  it  is  customary  to  regard  basophil  materials  as  chromatin. 
One  example  which  reminds  us  of  the  care  which  must  be  taken  in 
the  interpretation  of  cytological  staining  methods  will  suffice  : 
methyl  green,  a  dye  which  is  extremely  useful  for  staining  chro- 
matin, will  also  stain  mucin  of  goblet  cells,  and  the  matrix  of 
cartilage  ;  it  is  sometimes  found  that  after  chrome-osmium  fixation 
pyroniu  and  methyl  green  may  stain  oxyphil  materials  green,  and 
.basophil  ones  red. 

It  should  be  noted  here  that  we  have  no  certain  methods  for 
differentiating  cell  chromatin,  but  there  are  numbers  of  ways  which 
enable  us  to  detect  and  separate  out  substances  which  are  not 
chromatin. 

Let  us  take  the  case  of  the  so-called  sponge-egg  "  chromidia." 
After  chrome  fixation  and  iron  hematoxylin  or  ironbrazilin  stain- 
ing, these  bodies  stain  black  or  brownish  respectively ;  Jorgensen 
therefore  calls  them  "  chromidia."  Going  somewhat  further  into 
the  matter,  we  find  that  by  fixing  in  chrome  osmium  and  staining 
in  Ehrlich's  htematoxylin,  the  nuclear  chromatin  goes  blue,  while 
the  so-called  "chromidia"  either  do  not  show,  or  are  faintly 
brownish  and  not  stained;  fixing  the  sponge  in  Carney's  fluid  and 
staining  by  any  other  methods  fails  to  reveal  the  "  chromidia  "  ; 
fixing  and  staining  by  Champy-Kull  (JS),  the  "  chromidia  ''  go  red 
(fuchsin)  and  the  chromatin  of  the  nucleus  blue  (toluidin  blue), 
while  the  nucleolus  (plasmosome)  goes  red.  Therefore  we  can 
pronounce  the  "chromidia"  not  to  be  chromatin,  because  they  are 
dissolved  away  by  Carnoy,  because  they  fail  to  stain  like  chromatin 
in  Ehrlich's  ha3matoxylin  or  by  Champy-Kull's  method,  and 
because  their  histo-chemical  reactions  are  those  of  mitochondria 
which  have  no  direct  relation  to  chromatin. 


Mitochondria,  Golgi  Apparatus,  and   Yolk.  151 

In  the  animal  egg,  besides  the  mitochondria  which  have  thus 
been  mistaken  for  chromidia,  we  have  the  Golgi  apparatus.  Since 
the  latter  is  never  demonstrated  in  eggs,  by  the  usual  methods,  we 
do  not  believe  that  Golgi  grains  liave  so  far  been  misinterpreted 
as  "chromidia."  The  case  of  the  male  cells  has  already  been 
mentioned. 

It  may  be  noted  here  that  trus  chromidia,  by  which  we  simply 
mean  granules  of  chromatinic  nature  distinct  from  the  nucleus, 
but  traceable  to  nuclear  activity,  do  occasionally  occur  in  metazoan 
oogenesis.  The  cases  of  insect  oogenesis  are  well  known  (.?,  17) ; 
in  Hymenopterous  insects  especially  are  often  found  granular 
chromatinic  structures  free  in  the  cytoplasm,  and  quite  distinct 
from  either  mitochondria  or  Golgi  apparatus.  Such  cases  have 
been  noticed,  but  less  well  studied  in  other  Invertebrata.  It  can 
be  stated  that  true  chromidia  (chromatinic)  are  not  characteristic 
of  metazoan  cells.  Nearly  every  so-called  case  of  the  occurrence 
of  chromidia  in  Metazoa  is  really  a  misinterpretation  of  the 
mitochondria. 

On  page  153  we  have  given  a  scheme  showing  the  fixing  and 
staining  reactions  of  chromatinic  structures,  plasmosome,  and  of 
the  cytoplasmic  inclusions  such  as  the  mitochondria.  It  will  be 
noted  that  it  is  possible  to  stain  both  mitochondria  and  true  chro- 
matinic structures  in  different  colours  in  the  same  preparation. 
For  the  modus  operandi  of  these  methods,  see  {11)  and  {18). 


The  so-called  Chromatin  Emission  during 
Oogenesis. 

There  still  appears  to  be  a  rooted  belief  that  the  nucleus  is  able 
to,  and  constantly  does,  pass  out  granular  emissions  of  true  chromatin 
into  the  Qgg  cytoplasm  ;  it  is  also  believed,  but  with  more  justifica- 
tion, that  the  nucleolus  or  plasmosome  may  pass  out  and  break  up 
into  granules  which  are  in  some  way  concerned  with  yolk  forma- 
tion. Working  with  inappropriate  methods,  and  in  ignorance  of 
recent  researches  on  the  cytoplasm,  some  observers  are  wont  to 
describe  any  basophil  or  even  chromophil  cytoplasmic  granules 
as  chromidia,  and  to  trace  the  origin  of  such  granules  to  the 
nucleus. 

Among  more  modern  workers,  Schaxel  {37^  38)  has  written  a 
great  deal  on  these  questions  ;  in  the  polychaete  worm,  Aricia 
fcetida  (Claparede),  for  instance,  he  describes  how,  during  oogenesis, 
the  nuclear  matter  increases  in  bulk,  and  then,  "  When  the  chro- 
matin increase  has  reached  a  certain  stage,  there  appears,  with 
simultaneous  cell  growth,  a  dense  mass  of  numberless  chromatin 


152  Transactions  of  the  Society. 

particles  on  the  whole  outside  of  the  nuclear  membrane,  soon 
becoming  heaped  at  many  places  into  larger  clusters,  so  that  they 
form  striking,  scaly  masses  in  the  immediate  neighbourliood  of  the 
nucleus.  This  emission  process  persists  for  a  fairly  long  time. 
Nucleus  and  cell  body  increase  simultaneously  in  volume." 

These  quotations  from  Schaxel's  work  may  be  taken  as  typical. 
Two  obvious  objections  may  be  raised  against  his  interpretation  : 
(1)  Schaxel  produces  not  one  jot  or  tittle  of  evidence  that  the 
granular  particles  are  chromatin  ;  and  (2)  he  has  not  shown  satis- 
factorily that  the  granules  come  from  the  nucleus  at  all. 

Now  with  regard  to  the  first  objection  it  will  at  first  seem 
natural  enough,  from  the  point  of  view  of  the  older  technique,  to 
regard  such  an  extranuclear  basophil  mass  as  emitted  chromatin, 
but  modern  work  on  the  mitochondria  of  the  female  germ  cell 
allows  us  to  look  at  the  facts  from  quite  another  point  of  view,  for 
just  such  appearances  as  Schaxel  figures  are  produced  by  the 
mitochondria  at  certain  sta^^^es  of  oo2;enesis. 

We  further  believe  that  certain  at  least  of  the  appearances 
figured  by  Schaxel  as  chromophil  granules  flattened  upon  and 
adhering  to  the  nuclear  membrane,  are  artifacts  produced  by  the 
inferior  fixation  methods  employed.  Even  with  non-acetic  chrome 
osmium  fixation  bad  preparations  are  occasionally  produced  in 
which  a  granular  appearance  of  the  nuclear  membrane  is  to  be 
seen.  The  mitochondria  during  their  dispersal  through  the  egg 
cytoplasm  become  very  fine,  and  we  have  little  doubt  that  fixatives 
of  unsuitable  osmotic  pressure  would  cause  those  grains  near  the 
nuclear  membrane  to  be  driven  into  or  upon  the  latter  so  as  to 
produce  the  appearance  found  by  Schaxel. 

Schaxel,  moreover,  has  not  used  the  methods  which  best  dis- 
criminate between  chromatinic  and  non-chromatinic  matter.  He 
falls  into  the  error  of  relying  far  too  much  on  the  original  Flemming 
acetic  mixture  and  iron  alum  h^ematoxylin  method.  Schaxel  is 
not  the  possessor  of  a  unique  technique  unknown  and  unattainable 
by  other  w^orkers ;  he  simply  uses  methods  which  are  now  known 
to  be  inadequate  to  reveal  many  important  cytoplasmic  constituents, 
and  which  can  be  employed  by  any  zoologist. 

Eecent  w^orkers  such  as  Hirschler,  Weigl,  Nussbaum-Hilarowitz 
and  ourselves  do  not  find  true  chromatin  behaving  in  the  manner 
Schaxel  describes.  It  is  true  tliat  in  rare  cases,  such  as  in  insect 
and  some  other  eggs  (;?,  17),  a  definite  formation  of  presumably 
true  cliromatin  particles  is  found  in  the  egg  cytoplasm,  and  several 
observers  trace  these  granules  as  originating  from  the  nucleus 
(nucleolus),  but  similar  cases  are  rare.  These  definite  cytoplasmic 
chromatin  granules  are  to  be  distinguished  from  such  "  emitted  " 
granules  (mitochondria)  as  have  erroneously  been  described  as 
chromatin  by  Schaxel. 


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154  Transactions  of  the  Society, 

Under  this  section  we  are  obliged  to  conclude  that  the  so-called 
chromatiD  emission  of  Schaxel  is  very  probably  a  misinterpreted 
stage  in  the  evolution  of  the  mitochondria,  described  from  prepara- 
tions made  by  methods  which  do  not  produce  the  best  results. 

Such  definite  cases  of  extrusion  of  chromatin ic  granules  as  are 
known  {17)  do  not  resemble  anything  described  by  Schaxel. 

The  Nucleolus  and  the  Formation  of  Yolk. 

The  nucleolus  (plasmosome)  of  the  germinal  vesicle  of  young 
o5cytes  may  also  give  rise  to  bodies  which  are  themselves  to  be 
considered  yolk  granules,  or  which  metamorphose  into  yolk. 
Hempelmann  {20)  and  Buchner  {2a),  for  instance,  in  the  archian- 
nelid  Saccocirrus,  describe  the  partial  fragmentation  of  the  young 
oocyte  nucleolus,  the  migration  of  these  fragments  through  the 
nuclear  membrane,  and  the  subsequent  formation  of  yolk  from 
them. 

The  secondary  nuclei  of  insect  eggs,  which  may  originate  from 
the  nucleolus  do  not  seem  to  have  any  connexion  with  such  bodies 
described  in  Saccocirrus. 

jSTote  also  Schreiner's  work  mentioned  on  page  143,  and  Dendy's 
observations  on  Grantia  (5).  Schaxel's  descriptions  and  figures  do 
not  coincide  with  Hempelmann's  {:20)  observations  for  Saccocirrus, 
and  the  two  processes  are  unalike. 


The  Mitochondria  and  Golgi  Apparatus  in  Human 
Post-mortem  Material. 

The  cells  of  the  human  body,  like  those  of  other  animals,  are 
known  to  contain  the  above-mentioned  mitochondria  and  Golgi 
apparatus. 

It  has  been  found  by  experiment  that  very  soon  after  death 
the  protoplasmic  inclusions  partially  or  wholly  disintegrate,  under- 
going a  sort  of  plasmc^lysis ;  consequently  post-mortem  material, 
unless  procured  almost  immediately  after  death,  will  not  be  suitable 
for  a  study  of  any  of  the  cytoplasmic  inclusions. 

It  should  also  be  pointed  out  that  the  ether  or  chloroform  used 
to  produce  anaesthesia  may  occasionally  have  an  effect  on  the  cell 
inclusions  and  so  introduce  artifacts,  especially  in  small  animals. 

Mr.  Carleton,  of  the  Physiological  Department  of  Oxford, 
informs  us  that  he  has  been  unable  to  note  any  changes  in  the 
Golgi  apparatus  of  the  gut  cells  of  decerebrate  cats,  or  in  cats  which 
have  been  continuously  under  an  anesthetic  for  an  hour.  It  is 
nevertheless  necessary  to  avoid  tissues  which  have  been  exposed 
in  any  way  to  injurious  agents. 


Mitochondria,  Golgi  Apimratus,  and   Yolk.  155 


Bibliography. 

1.  Beckwith,  C.  J. — The  Genesis  of   Plasma  Structures  in  the   Egg  of 

Hydractinia.     Journ.  Morph.,  xxv.  (1914). 

2.  BucHNER,    Paul. — Die    akzessorischen    Kerne  des  Hymenoptereneies. 

Arch.  f.  Mikr.  Anat.,  Bd.  xci.  (1918). 
2a.  Saccocirrus.     Arch.  f.  Zellf.  (1914). 

3.  Carleton,  H.  M. — On  a  New  Intra-nucleolar  Body.    Quart.  Journ.  Micr. 

Science,  Ixii.  (1920). 

4.  CowDRY,  E.  V. — The   Mitochondrial   Constituents   of  the  Protoplasm. 

Contributions  to  Embryology,  viii.  Nos.  24-6. 

5.  Dendy,  A. — The  Gametogenesis  of  Grantia  compressa.     Quart.  Journ. 

Micr.  Science,  Ix.  (1914-15). 

6.  DoBELL,  C. — Chromidia  and  the  Binuclearity  Hypothesis.    Quart.  Journ. 

Micr.  Science,  liii. 

7.  DuBUissoN — Contribution    a   I'etude    du  vitellus.     These  de  Paris,  No. 

1249  (Nov.  1906),  as  quoted  by  Lams  (;?7). 

8.  DuBREuiL,  G. — Transformation  directe  des  mitochondries  et  des  chon- 

driocontes  en  graisse  dans  cellules  adipeuses.     C.R.  Soc.  Biol.,  Ixx. 

9.  Faure-Fremiet. — Etude  sur  les  mitochondries  des  Protozoaires,  et  des 

cellules  sexuelles.  .  Arch.  d'Anat.  Micr.,  xi. 

10.  Le  cycle  germinatif  chez  VAscaris.     Arch.  d'Anat.  Micr.,  xv. 

11.  Gatenby,  J.  Bronte — The  Identification  of    Intracellular   Elements. 

Journ.  E.  Micr.  Soc.  (1919). 

12.  The   Cytoplasmic   Inclusions  of  the  Germ-Cells.     Part    I.   Lepi- 

doptera.     Quart.  Journ.  Micr.  Science,  Ixii. 

Part       II.    Helix  aspersa.     Ibid.,  Ixii. 
,,      III.    Other  Pulmonates.     Ibid.,  Ixiii. 

Paludina  and  Testacclla.     Ibid.,  Ixiii. 
Limnxa.     Ibid.,  Ixiv. 
Apanteles.     Ibid.,  Ixiv. 

Modern  Cytological  Technique.     Ibid.,  Ixiv. 
Grantia  compressa.     Journ.  Linnean  Soc.  (1920). 
— Die  Geschlechtsorgane  und-  Zellen  von  Saccocirrus. 
Zoologica,  Heft  67. 

21.  Hirschler,  J. — Ueber  die  Plasmastrukturen  in  den  Geschlechtszellen 

der  Ascariden.     Arch.  f.  Zellf,,  Bd.  9  (1913). 

22.  Ueber  ein  Verfahren  zur  gleichzeitigen  Darstellung  des  Golgischen 

Apparates  und  der  Mitochondrien  des  Zellenplasmas  in  differenten 
Farben.     Zeit.  f.  Wiss.  Mikr.  u.  Tech.,  xxxii.  (1915). 

23.  Ueber   den   Golgischen   Apparat   embryonalen    Zellen.      Arch.   f. 

Mikr.  Anat.,  Bd.  xci.  (1918). 

24.  Ueber  die  Plasmakomponenten  der  weiblichen  Geschlechtszellen. 

Arch.  f.  Mikr.  Anat.,  Bd.  Ixxxix.  (1919). 

25.  Jexkinson,  J.  W. — Vertebrate* Embryology.     Oxford. 

26.  Jorgensen,  M. — Beitriige  zur  Kenntnis  der  Eibildung  Reifung,  Befruch- 

tung  u.  Furchung  bei  Schwammen.     Arch.  f.  Zellf.,  Bd.  iv.  (1910). 

27.  Lams,  M.  H. — Contribution  a  I'etude  de  la  genese  du  vitellus  dans  I'ovule 

des  Amphibiens.     Arch.  d'Anat.  Micr.,  ix.  (1907). 

28.  LoYEz,  Marie— Sur  la  Structure  de  I'Oocyte  de  la  Femme  a  la  Periode 

d'Accroissement.     C.E.  Soc.  Anat.  (1911). 

29.  Meves,  Fr. — Zelltheilung.     Merk.  u.  Bonnet,  Erg.  vi. 

30.  Murray,  J.  A. — On    a    Transplantable    Sarcoma   of  the   Guinea- Pig. 

Cancer  Research  Reports,  1919. 

31.  NusBAUM-HiLAROWicz. — Ueber  das  Verhalten  des  Chondrioms  wahrend 

der  Eibildung  bei  Dytiscus.     Zeit.  f.  wiss.  Zool.  (1917). 


156  Transactions  of  the  Society. 

32.  Pappenheimbr,  A. — The  Golgi  Apparatus.     Anat.  Eecord,  xi.  (1916). 

33.  Perrinoito,  A. — Contribution  a  I'etude  de  la  biologie  cellulaire,  etc. 

Arch.  Ital.  de  Biol.,  liv.  (1910). 

34.  PopoFF,  M. — Eibildung  von   Paludina    vivipara  und   Chromidien   bei 

Faludina  und  Helix.     Arch.f.  Mikr  Anat.,  Bd.  Ixx. 

35.  Regaud,  Cl. — Etudes  sur  la  structure  des  tubes  seminiferes  et  sur  la 

spermatogenese  chez  mammiferes.     Arch  d'Anat.  Micr.,  xi. 

36.  Rio  Hortega,  P. — Details  nouveaux  sur  la  structure  de  I'ovaire.     Trab. 

Lab.  Invest.  Biolog.,  xi.  (1913). 

37.  Schaxel,  J. — Plasmastrukturen,  Chondriosomen  u.  Chromidien.     Anat. 

Anzeig.,  Bd.  39  (1911). 

38.  Die  Geschlechlszellenbildung  und  die  normale  Entwicklung  von 

Aricia  fixtidia.     Zool.  Jahrb.,  Bd.  34  (1912). 

39.  ScHREiNER — Kern.  u.  Plasmaveranderungen  in  Fettzellen  wahrend  de& 

Fettansatzes.     Anat.  Anzeig.  (1915). 

40.  Stockard  &  Papanicolaou — The  .Development  of  the  Idiosome  in  the 

Germ-Cells  of  the  Male  Guinea-Pig.     Amer.  Journ.  Anat.,  ccxli. 
(1918). 

41.  Van   der    Stricht — Vitellogenese   dans  I'ovule    de  Chatte.     Arch,  de 

Biol.,  xxvi. 

42.  Weigl,  R. — Vergleichend-zytologische  Untersuchungen  liber  den  Golgi- 

Kopschen  Apparat,  etc.     Bull,  de  I'Acad.  Sclent.  Cracovie  (1912). 

43.  Whitman,  C.  O. — The  Inadequacy  of  the  Cell  Theory  of  Development. 

Biol.  Lect.  Woods  Hole  (1893). 

44.  Wilson,  E.  B.— The  Cell.     N.Y.  (1900). 


157 


IV. — Method  for  the  Demonstration  of  the  Golgi  Apparatus 
ill  Nervous  and  other  Tissues. 

By  C.  Da  Fano,  M.D.,  L.D.  on  Morbid  Anatomy,  University  of 
Pavia  (Italy),  F.E.M.S.,  Lecturer  on  Histology,  King's  College, 
University  of  London. 

(Bead  March  17,  1920.) 

One  Plate. 

The  preparations  I  have  the  honour  of  showing  to  this  Society 
have  all  been  obtained  by  the  following  method : — 

1.  Fixation. 
Small  pieces  of  quite  fresh  tissues  are  fixed  in — 

Cobalt  nitrate     ......     1  grm. 

Distilled  water 100  c.c. 

Formalin   .......     15  c.c. 

The  solution  can  be  prepared  beforehand  and  keeps  unaltered 
for  months.  Formalin  need  not  be  neutralized  unless  strongly 
acid  or  containing  free  sulphuric  acid,  in  which  case  it  is  neces- 
sary to  neutralize  it  by  one  of  the  usual  i methods,  such  as  shaking 
with  calcium  carbonate  and  filtering  before  using.  For  the  fixation 
of  embryonic  organs,  and  in  all  cases  in  which  a  shrinkage  of 
delicate  tissues  is  to  be  feared,  the  quantity  of  the  formalin  may 
be  reduced  to  10,  8,  6  c.c.  for  every  100  c.c.  of  distilled  water. 
The  pieces,  about  3  mm.  thick,  are  generally  left  six  to  eight  hours 
in  the  fixing  solution  at  room  temperature.  This  time  should 
be  shortened  to  3-4  hours,  or  even  less  in  the  case  of  certain 
tissues,  such  as  cartilage,  or  of  very  small  pieces,  such  as  spinal 
ganglia  of  mice  and  rats,  adrenals  of  mice,  the  pituitary  body  of 
the  same  animals,  etc.  Hollow  organs,  such  as  the  stomach  and 
intestine,  are  better  fixed  if  partially  filled  with  the  fixing  fluid 
and  kept  in  it  in  toto  for  about  one  hour,  after  which  time  they 
are  reduced  to  due  proportions  and  treated  according  to  their 
thickness.  Pieces  of  spinal  cord,  cerebrum,  cerebellum  of  adult 
animals  give  better  results  if  fixed  for  about  eight  to  ten  hours.  The 
fixation  may  be  prolonged  in  special  cases  to  12-20  hours,  but 
should  not  exceed  twenty-four  hours.  For  the  difficult  fixation  of 
the  testis  of  mammalia  it  is  advisable  to  inject  the  fluid  through 
the  abdominal  aorta  and  afterwards  to  plunge  the  entire  organ  in ' 
the  fluid  for  some  time  before  proceeding  to  cut  off  the  necessary 
pieces.     Small  animals  can  be  injected  in  toto   from  the  heart, 


158  Transactions  of  the  Society. 

allowing  the  blood  to  flow  out  from  the  wound  made  to  expose  it. 
If  the  injection  is  successful,  organs  and  tissues  becomie  very 
quickly  ready  for  the  second  stage  of  the  method,  and  one  must 
rapidly  proceed  to  their  extraction  and  reduction  into  small  pieces, 
which  are  left  in  the  fixing  fluid  for  a  short  period,  corresponding 
to  about  one-third  or  one-half  of  the  time  needed  for  the  fixation 
of  non-injected  material.  Should  it  be  particularly  interesting  to 
have  the  outermost  layers  of  certain  organs  well  stained,  these 
must  be  fixed  with  some  of  the  surrounding  tissue,  such  as  fatty 
or  connective  tissue,  the  pia  mater  in  the  caseof  the  central  nervous 
system,  etc.  I  have  at  present  little  experience  of  the  fixation  of 
material  from  low  vertebrates  and  invertebrates.  In  general  I 
should  advise  proceeding  by  tentative  experiments,  which  are  also 
necessary  for  the  systematic  study  of  the  internal  apparatus  in 
some  determined  tissues,  as  the  moment  in  which  they  become 
ready  for  the  subsequent  treatment  appears  to  vary  a  little  in 
almost  every  one  of  them.  The  fixation  at  a  temperature  vary- 
ing between  25  and  37°  C.  has  been  attempted  with  some  success, 
particularly  in  the  case  of  cortex  cerebelli  of  mammalia.  It 
leads,  however,  to  some  special  results  which  M'ill  be  dealt  with 
afterwards. 

2.  Impregnation. 

The  pieces  are  quickly  washed  twice  in  distilled  w^ater,  their 
surfaces  made  smooth  if  necessary,  and  then  placed  in  a  1*5  p.c. 
solution  of  AgNOs.  For  very  small  fragments  and  structures 
which  are  easily  impregnated,  as  the  Fallopian  tube  of  small 
mammals,  1  p.c.  AgNOg  can  be  used.  For  pieces  of  spinal  cord 
of  adult  animals  and  organs  containing  much  fat,  the  strength  of 
the  AgN0:5  solution  may  be  raised  to  2  p.c.  The  quantity  of 
AgNO.}  solution  changes  according  •  to  the  number  of  pieces ; 
generally,  no  more  than  five  or  six  are  put  in  a  specimen  bottle 
of  an  approximate  capacity  of  30  c.c.  They  are  left  in  the  silver 
bath  from  twenty-four  to  forty-eight  hours,  according  to  their  size. 
A  longer  stay,  though  often  without  danger,  should  be  avoided  as 
precipitates  may  form.  As  a  rule  the  pieces,  once  in  the  AgNOj 
solution,  are  kept  away  from  the  light  and  at  room  temperature. 
In  winter  and  if  the  temperature  of  the  laboratory  fails  very 
much  during  the  night,  one  may  have  recourse  to  an  incubator  at 
25-28°  C.  The  use  of  an  incubator  at  36-37°  C.  may  be  attempted 
with  success  for  the  spinal  cord  of  adult  mammals,  and  for  pieces 
which  are  difficult  to  impregnate.  This  practice  may  be  attended 
by  good  as  well  as  by  negative  residts,  and  ought  to  be  arrived  at 
by  tentative  experiments,  in  order  to  establish  the  most  suitable 
length  of  time  during  which  the  pieces  may  be  safely  left  in  the 
"incubator  at  certain  temperatures. 


Method  for  Demonstration  cf  the  Golgi  Apparattis.       159 


3.  Reduction. 

The  pieces  are  quickly  washed  twice  in  distilled  water,  and 
further  recut  so  that  their  thickness  does  not  exceed  2  mm.  They 
are  then  transferred  into  Cajal's  reducing  fluid  to  be  freshly 
prepared  every  time  : — 

Hydroquinone     ......  l"5--2  grms. 

Anhydrous  sodium  sulphite  .         .         .  0' 15-0 -25  grms. 

Distilled  water  ......  100  c.c. 

Formalin  .......  6  c.c. 

First  dissolve  the  hydroquinone  in  water  and  then  the  sodium 
sulphite  before  adding  the  formalin,  to  be  neutralized  only  if 
strongly  acid,  as  pointed  out  before.  Instead  of  hydroquinone, 
pyrogallic  acid  may  be  used,  though  it  appears  to  have  a  lesser 
power  of  penetration,  and  the  pieces  must  consequently  be  smaller. 
Its  use  may  be  of  some  advantage  if  only  a  dark  brown  colour  of 
the  apparatus  is  desirable.  Pieces  are  generally  left  in  the  reduc- 
ing fluid  from  one  day  to  the  next.  A  longer  stay,  though  harmless, 
is  without  purpose,  as  after  about  twelve  hours  the  A  glSTOg  appears 
to  be  completely  reduced.  Weaker  solutions  of  hydroquinone  are 
to  be  used  only  in  special  cases.  Various  attempts  have  been 
made  to  leave  the  pieces  in  the  reducing  fluid  a  few  hours  only, 
but  either  no  special  results  have  been  obtained,  or,  in  contradic- 
tion to  Caiieton's  statement,  the  staining  of  the  apparatus  was 
insufficient  in  consequence  of  a  probably  incomplete  reduction  of 
the  silver. 

4.  Embedding,  Toning  and  Counterstaining. 

The  reduction  having  taken,  place,  the  method  is  ended,  and 
the  pieces  may  be  washed  in  distilled  water  for  a  little  while  to 
extract  the  formalin,  and  cut  by  means  of  a  freezing  microtome. 
It  is,  however,  preferable  to  pass  them  rapidly  through  alcohols  of 
increasing  strength,  clear  them  by  means  of  fluid  cedar-wood  oil, 
and  embed  them  in  paraffin  melting  at  48°  C.  They  may  also  be 
embedded  in  celloidin,  but  rapidly,  because  absolute  alcohol  and 
ether  have  a  tendency  to  dissolve  the  unstable  reduced  silver. 
Moreover,  celloidin  blocks  must  be  cut  as  soon  as  possible,  while 
paraffin  blocks  keep  indefinitely,  and  may  be  cut,  eventually  in 
series,  when  most  convenient.  The  sections,  however  obtained, 
free  or  stuck  to  slides,  are  mounted  in  Canada  balsam  or  xylol- 
colophonium  in  the  usual  way.  They  show  the  apparatus  stained 
black  or  dark  brown  on  a  more  or  less  intense  yellow  or  buff 
background.  These  preparations  do  not  generally  keep  well, 
because  the  xylol  of  the  balsam  very  often  dissolves  the  reduced 
silver.    Further,  in  most  cases  a  counterstaining  is  desirable.    For 


160  Transactions  of  the  Society. 

these  reasons  it  is  preferable  to  transfer  the  sections,  either  single 
or  stuck  to  slides  by  the  albumin  method,  through  xylol  and 
alcohols  of  decreasing  strength  into  distilled  water,  and  tone  them 
by  means  of  a  0*1-0 -2  p.c.  acid  solution  of  gold  chloride,  as 
suggested  in  my  communication  to  the  January  Meeting  of  the 
Physiological  Society,  at  which  a  preliminary  note  on  the  above 
described  method  was  also  communicated.  The  unstable  reduced 
silver  may  be  fixed  by  other  methods,  e.g.  by  the  toning  and 
bleaching  process  of  Veratti,  as  published  by  Golgi,  which  has  the 
advantage  of  imparting  to  the  finished  preparations  a  white,  almost 
colourless  background,  though  I  find  it  rather  more  difficult  of 
execution,  and  more  expensive  on  account  of  the  greater  quantity 
of  gold  chloride  solution  required.  The  toned  preparations  can  be 
either  dehydrated  and  mounted  or  counterstained,  as  one  may  think 
desirable,  the  consecutive  treatment  being  according  to  the  stain 
chosen.  For  routine  work  I  prefer  alum-carmine,  because  it  allows 
the  handling  of  many  sections  or  slides  at  the  same  time,  does  not 
usually  require  a  successive  differentiation,  and  imparts  to  both 
nuclei  and  cytoplasm  a  deep  pink  staining  contrasting  well  with 
the  black  or  dark  grey  colour  of  the  apparatus.  For  the  dehydra- 
tion of  sections  stained  with  alum-carmine  no  absolute  alcohol  is 
required,  as  after  the  95  p.c.  alcohol  clearing  in  carbol-xylol  and 
mounting  in  balsam  may  follow. 


5.  General  Considerations. 

The  present  method  is  only  a  modification  of  the  uranium 
nitrate  method  proposed  by  Cajal,  who  had  already  suggested  the 
use  of  other  nitrates,  such  as  those  of  manganese  and  of  lead. 
Various  attempts  were  made  by  me  with  copper  nitrate,  but 
unsuccessfully.  The  same  can  be  said  of  cobalt  sulphate.  Cobalt 
acetate  I  am  still  investigating,  as  it  appears  to  be  particularly 
suitable  for  the  study  of  the  internal  apparatus  in  generative 
organs,  and  enables  one  to  recognize  in  the  middle  piece  of 
spermatozoa  a  very  small  structure,  similar  to  a  minute  apparatus, 
to  which  I  paid  special  attention  after  having  seen  some  preparations 
of  Dr.  J.  Bronte-Gatenby. 

Cobalt  nitrate,  like  uranium  nitrate  and  arsenious  acid,  does 
not  alter  the  Nissl's  substance,  as  can  be  shown  by  counter-staining 
toned  sections  of  spinal  ganglia  or  spinal  cord  with  neutral  red, 
toluidin  blue,  crystal  violet,  etc.  Much  the  same  might  be  said  of 
neurofibrils,  on  which  subject,  however,  I  propose  to  give  a  special 
demonstration  in  due  course. 

As  pointed  out  in  my  preliminary  communication,  my  method 
stains  in  certain  conditions  not  only  the  internal  apparatus,  but 
also  intracellular  formations,  which,  according  to  their  morphology 


JOURN.  R.  MICR.  SOC,  1920.  PI.   Ill, 


,iC^ 


^  .^\j 


Fig.  1,— Golgi  apparatus  in  spinal  ganalion-cells  of  a  young  rabbit. 
For  comparison  witli  fig.  2. 


*         > 


-|,        *€J  * 


Method  for  Demonstration  of  the  Golgi  Apparatus.       161 

and  arrangement,  are  to  be  considered  as  mitochondria.  This  was, 
in  a  way,  to  be  expected,  as  in  uranium  nitrate  preparations  there 
also  appear  sometimes  well-stained  mitochondria ;  and  Perroncito 
has  shown  that  similar  results  can  be  obtained  by  Golgi' sarsenious 
acid  method,  if  the  fixing  solution  is  made  to  act  for  some  hours 
at  45-50°  C.  The  same  happens  almost  constantly  in  the  case 
of  my  cobalt  nitrate  modification  if  the  fixation  is  prolonged 
to  18-24  hours  at  room  temperature,  or  takes  place  with  fluid 
previously  warmed  and  kept  at  36-37°  C.  for  a  few  hours  as 
explained  above.  An  almost  constant  staining  of  both  mitochondria 
and  internal  apparatus  in  the  same  preparations  has  been  observed 
by  me  in  transplantable  sarcomata  of  rats  and  mice,  and  in  the 
uterus  glands  and  epithelium  of  some  mammalia  by  the  unmodified 
method  described  above,  as  can  be  seen  in  two  of  the  preparations 
I  am  showing. 

These  various  results,  together  with  the  extraordinary  variations 
in  the  morphological  aspect  of  Golgi' s  internal  apparatus,  strengthen 
the  belief  that  we  are  not  faced  here  by  mere  capricious  precipitations 
of  silver  or  by  some  artefact  due  to  the  methods  of  fixing  and 
staining.  In  this  respect  it  seems  to  me  that  my  preparations 
from  human  Gasserian  ganglion  obtained  five  hours  after  death  are 
particularly  interesting  (fig.  2).  The  apparatus,  fixed  when  under- 
going an  evident  process  of  autolysis,  has  lost  much  of  its  peculiar 
aspect  and  appears  broken  into  irregularly  shaped  pieces,  lumps  and 
granules,  which  also  occur,  for  instance,  in  parts  of  transplantable 
tumours  undergoing  a  process  of  necrosis  or  in  other  degenerating 
tissues,  but  not  in  normal  freshly  fixed  organs. 


KeT'ERENCES. 

Golgi,    C. — Une   methode    pour  la  prompte    et   facile   demonstration   de 

I'appareil  reticulaire  interne  des  cellules  nerveuses.     Arch.  Ital.  Biol., 

xlix.  (1908)  p.  269. 
Perroncito,  A. — Contributo  alio  studio  della  biologia  cellulare.    Mitocondri, 

cromidii  ed  apparato  reticolare  interno  nelle  cellule  spermatiche.    Mem. 

E.  Ace.  Lincei,  Roma,  viii.  (1910)  p.  6. 
Cajal,  R.  S. — Formula  de  fijacion  para  le  demonstracion  facil  del  apparato 

reticular  de  Golgi,  etc.     Trab.  Lab.  Invest.  Biol.,  x.  (1912)  p.  209. 

Alcunas  variaciones  fisiologicas  y  patologicas  del  apparato  reticular  de 

Golgi.     Trab.  Lab.  Invest.  Biol.,  xii.  (1914)  p.  127. 

Carleton,  H.  M. — Note  on  Cajal's  Formalin-silver  Nitrate  Impregnation 
Method  for  the  Golgi  Apparatus.     Journ.  R.  Micr.  Soc,  1919,  p.  321. 

Da  Fano,  C. — On  the  so-called  toning  of  sections  stained  by  my  modifica- 
tions of  the  Bielschowsky  Method  and  by  other  Reduced  Silver  Methods. 
Phys.  Proc.  Journ.  Physiol.,  liv.  (1920). 

Method  for  the  Demonstration  of  Golgi's  Internal  Apparatus.     Phys. 

Proc.  Journ.  Physiol.,  liv.  (1920). 


M 


163 


V. — On  Acari  from  the  Lungs  of  Macacus  rhesus. 
By  F.  Martin  Duncan,  F.E.M.S.,  F.R.P.S.,  F.Z.S. 

{Read  June  18,  1919.) 

One  Plate  and  Two  Text-Figures. 

The  first  case  of  Acariasis  in  the  lungs  of  the  Common  Ehesus 
Monkey  (Macacus  rhesus)  to  come  under  my  observation  was 
during  September  1918,  when  I  was  assisting  Dr.  J.  A.  Arkwright 
in  Trench  Fever  investigation  at  the  Lister  Institute  of  Preventive 
Medicine.  Since  then  I  have  been  able  to  investigate  a  number 
of  cases  from  various  other  sources,  and  from  these  cases  the 
material  shown  under  the  microscopes  this  evening,  and  the 
photographs,  have  been  obtained. 

The  presence  of  these  Acari  is  generally  revealed  by  small, 
pale,  whitish-yellow  vesicles  dotted  about  on  the  surface  of  the 
lung,  and  varying  in  size  from  ^th  to  ^th  of  an  inch  in  diameter. 
On  dissection  these  vesicles  are  found  to  communicate  with  small 
bronchi,  and  to  have  thin  fibrous  walls,  which  are  generally  lined 
internally  with  a  layer  of  soft  white  or  greyish-white  debris,  in  the 
midst  of  which  the  mites  rest.  Although  these  cavities  are 
commonly  situated  just  beneath  the  pleura,  they  are  also  occasion- 
ally found  in  the  depth  of  the  lung.  The  Acari  are  always  most 
numerous  in  the  cavities  just  beneath  the  pleura,  and  from  the^^e 
"nurseries"  they  appear  to  wander  into  the  small  bronchi  that 
open  into  the  cavity,  and  thence  make  their  way  deep  into  the 
tissues  of  the  lung,  their  presence  in  this  situation  having  been 
demonstrated  in  several  batches  of  serial  sections  of  lungs. 

On  opening  a  vesicle  the  mites  will  generally  be  seen  resting 
with  their  legs  apparently  more  or  less  embedded  in  the  debris 
lining  the  cavity.  They  begin  to  move  about,  however,  very  soon 
after  the  vesicle  has  been  cut  open,  and  if  left  alone  may  be  seen 
to  crawl  about  and  enter  the  bronchi  opening  into  the  vesicle,  and 
to  disappear  from  view.  The  debris  within  the  vesicle  seems  to 
consist  chiefly  of  desquamated  epithelial  cells  and  leucocytes,  with 
minute  crystals,  possibly  of  haemoglobin.  A  few  bacteria  have 
also  been  detected  in  smears. 

It  is  interesting  to  note  that  in  all  the  cases  so  far  examined 
the  presence  of  these  Acari  in  the  lung  does  not  appear  to  have 
caused  serious  illness  or  death — death  in  each  case  being  due  to 
some  other  clearly  defined  cause.     At  the  same  time  the  presence 

u  2 


164  Transactions  of  the  Society. 

of  these  Acari  in  large  numbers  must  set  up  a  certain  amount  of 
irritation  likely  to  predispose  to  pulmonary  disease,  and  may  be 
a  factor,  if  not  the  actual  reason,  for  the  marked  susceptibility  of 
Macacus  Monkeys  to  such  diseases.  Infestation  probably  takes 
place  early  in  life,  as  many  of  the  monkeys  examined  were  young 
individuals,  perhaps  half  grown.  How  the  Acari  find  entrance  to 
the  lung  in  the  first  instance  has  yet  to  be  established,  but 
probably  infestation  takes  place  via  the  nasal  passages  or  mouth. 
Once  established  in  the  lung,  however,  breeding  takes  place,  and 
apparently  the  whole  life -cycle  can  be  passed  through  in  this 
environment,  as  I  have  found  young  and  advanced  larv?e,  nymphs, 
and  adults  present  in  the  lung.  The  number  of  Acari  present  in 
the  vesicles  varies,  ranging  from  a  single  individual  to  twelve  or 
fourteen.  Males  appear  to  be  few  in  number  as  compared  with 
females. 

The  Acari  in  the  larval,  nymph,  and  adult  stages  of  their 
existence  are  semi-opaque,  ashy-white  in  colour,  the  mid-intestine 
and  diverticulpe  showing  through  the  semi-transparent  surface  of 
the  dorsal  skin  in  pale  opaque,  cream-coloured  lines.  The 
epidermis  is  soft  and  easily  ruptured,  therefore  considerable  care 
is  necessary  in  handling  and  mounting  these  Acarids  for  micro- 
scopic examination. 

The  larva  is  six-legged,  short  and  oval  in  shape,  averaging  ^^Q-th 
of  an  inch  in  length  of  body,  yJo^^^  ^^  ^^^  ^^^^^  across  the  thorax, 
and  g^th  of  an  inch  across  the  greatest  width  of  abdomen.  The 
first  pair  of  legs  average  y^gth  of  an  inch  in  length,  and  the 
second  ^jfi^  and  third  pair  j^th  of  an  inch.  The  legs  have  a  few 
stout  hairs,  and  are  cylindrical  and  tapering  to  the  slender  foot. 
The  tarsus  is  very  slender,  with  equal  curved  claws,  and  well- 
developed  pulvillus,  which  extends  between  and  beyond  the  claws. 
The  palps  are  tapering,  and  appear  more  prominent  and,  in 
comparison,  slightly  longer  than  in  the  adult,  each  palp  bearing  a 
long  stout  terminal  hair.  The  mandibles  are  pointed,  and  straight- 
edged  on  their  inner  surface,  like  the  blade  of  a  knife. 

The  nymph  and  adult  closely  resemble  each  other  in  size  and 
shape,  the  most  distinctive  feature  in  the  nymph  being  the  absence 
of  the  external  genital  pore.  The  palpi  are  short,  composed  of 
three  segments,  and  crowned  with  a  minute  apical  hair.  The 
body  is  oblong,  broader  at  the  abdominal  extremity,  narrower 
towards  the  thorax.  Average  length  of  body  of  adult  female,  ^^th 
of  an  inch ;  average  width  across  thorax,  -^\h  of  an  inch ;  average 
across  greatest  width  of  abdomen,  ^W\  of  an  inch.  The  genital 
pore  is  situated  centrally  on  the  anterior  part  of  the  ventral  surface 
of  the  abdomen,  as  a  transverse  oblong  slit  with  a  slightly 
thickened  rim.  The  mandibles  in  the  adult  are  chelate,  have 
slender  curved  points,  and  rest  witliin  a  transparent  sheath.  The 
legs  are  cylindrical  and  tapering,  each  segment  bearing  a  few  hairs. 


JOURN.  R.  MICR.  SOC,  1920.     PL.  IV. 


Larva  x  60. 


Adult  9  X  60. 


Adult  cJ  X  60. 


'■•^     .    .     ^      V,  -   ,                >,    ,                       -K      ,.          . 

UgM:^^^.y^\:':'. 

'♦ 

<^'^"  --^    lr'^^,..■r-^^  ^•;"-^      -^    '     ".  ', 

'o'-'  ■•'   .'     .. 

•.' ::'.'••;•■,?.-•:■.•. "v%- .    ^•' '' i    >:- 

■\^:-  ^"^ 

.y--'-  '*'  ' 

071  Acari  from  the  Lyings  of  Macacus  rhesus. 


166 


The  claws  of  the  tarsus  are  well  developed  and  strongly  curved, 
and  the  pulvillus  extends  between  and  considerably  beyond  them. 
Average  length  of  first  pair  of  legs,  xoo^^^  ^^  ^^  ^^^^^  j  ^^  ^'^^ 
second  pair,  j^o^h  of  an  inch ;  of  the  third  pair,  y^^^^  ^^  ^^  ^^^^ ' 
of  the  fourth  pair,  jJo^^^  ^^  ^^  ^^^^^-  ^^^^  stigmata  are  oval  and 
open  on  the  ventral  surface  of  the  thomx  between  the  third  and 
fourth  legs. 

A  dorsal  shield  or  scutum  is  present,  but  is  somewhat  difficult 
to  detect  in  whole-mounted  specimens. 

From  the  material  I  have  so  far  been  able  to  examine  I  have 


Tarsus  of  second  leg  of  larva,     x  500. 


obtained  only  two  specimens  that  are  probably  males.  I  have 
judged  these  to  be  males  from  their  slightly  smaller  and  more 
slender  build,  plus  the  absence  of  the  vulvar  orifice  and  the 
presence  of  a  special  anterior  ventral  orifice ;  also  the  small  anai 
projection  is  within  the  margin  and  not,  as  in  the  nymph  and 
female,  upon  it.  What  is  probably  the  male  genital  orifice  can  be 
made  out  as  a  small  circular  aperture  close  behind  the  hypostome ; 
and  from  it  a  tube  can  be  traced,  with  some  difficulty,  leading 
posteriorily  for  a  certain  distance  beneath  the  ventral  cuticle.  This 
tube  is  not  easy  to  see  in  my  specimens,  and  might  from  a  casual 
examination  be  mistaken  for  a  longitudinal  furrow.  The  average 
length  of  body  is    4\jth  of  an  inch ;   the  width  across  middle  of 


16 '3  Transactioiis  of  the  Sodety. 

tliorax,  yJo^^^  ^^  ^^^  ^^^^^^  5  across  greatest  width  of  abdomen,  ^(jth. 
Length  of  first  pair  of  legs,  y-Jo^h  of  an  inch ;  second  pair,  j^o^h ; 
third,  yj(jth,  and  the  fourth  pair,  y^oth  of  an  inch.  All  the  legs  are 
cylindrical,  tapering  to  the  well-developed  strongly  curved  claws, 
with  the  extending  pulvillus,  and  are  sparsely  clothed  with  stout 
hairs.  The  palpi .  are  short,  three- jointed,  and  the  mandibles 
chelate. 

So  far  no  eggs  have  been  detected  either  in  the  vesicles  or  in 
bronchi  containing  the  Mites.  It  is  possible  that  these  Acarids 
are  larviparous,  for  Weidman  (^)*  mentions  finding  a  young  larva 
in  the  vicinty  of  a  ruptured  female.  Professor  Allman  (7), 
describing  a  new  genus  and  species  of  Tracheary  Arachnidians, 
states  that  on  rupturing  the  walls  of  the  abdomen  of  female 
specimens,  he  frequently  obtained  young  larvae  "formed  as  yet 
with  only  six  legs,  and  the  abdomen  scarcely  visible."     Allman 


Tarsus  of  third  leg.    Adult,      x  500. 

states  that  these  small  six-legged  larv?e  were  also  found  in 
numbers  along  with  tlie  adults.  These  Mites  were  discovered  by 
Allman  in  the  posterior  nares  of  a  Seal  {Halicluerus  gryphus),  and 
named  by  him  Halarachne  Halichceri.  His  drawing  of  the  larva 
bears  a  striking  resemblance  to  the  larva  found  in  the  lungs  of 
Macacus  rhesiis. 

Acari  from  the  lungs  of  different  species  of  JNIonkeys  (including 
Macacus  rhesus)  have  been  described  by  Newstead  and  Todd  {S), 
by  Newstead  (4),  Landois  and  Hoepke  (5),  but  the  descriptions  of 
these  authors  do  not  coincide  with  all  the  morpholoiiical  details 
of  the  Mites  I  have  had  under  examination.  Weidman  (6^), 
however,  has  given  a  full  and  well-illustrated  account  of  some 
IMites  that  he  had  ol)tained  from  the  lungs  of  a  single  Rhesus 
IMonkey,  and  his  description  coincides  in  all  particulars  with  the 
specimens  that  I  have  obtained  from  all  the  lungs  that  have  so  far 

^-  The  italic  figures  within  brackets  refer  to  the  Bibliography  at  end  of  the 
paper. 


On  Acari  from,  the  Lungs  of  Macacus  rhesus.  167 

passed  through  my  hands.  For  this  Mite  he  proposes  to  establish, 
the  name  Pneumonyssus  foxi.^  Of  the  specimens  described  by  the 
previously  cited  authors,  the  Pneumonyssios  griffithi  of  Newstead 
most  closely  resembles  the  species  under  consideration ;  but  it  does 
not  coincide  in  all  details,  nor  do  the  rather  sketchy  outline 
drawings  illustrating  his  paper. 

Mites  belonging  to  the  Gytoditinse  are,  according  to  Neumann 
(7),  found  in  the  subcutaneous  or  inter-muscular  connective  tissue 
surrounding  the  respiratory  organs,  or  in  the  air-sacs  of  birds.  The 
Oytodites  inhabit  the  air-sacs  of  the  Gallinacea,  especially  Fowls 
and  Pheasants.  They  enter  the  bronchi,  and  even  reach  the  air- 
canal  in  the  bones.  They  often  exist  in  large  numbers  in  the 
air-sacs  without  betraying  their  presence  during  the  life  of  their 
host,  and  apparently  causing  no  serious  inconvenience  or  ill-health, 
though  occasionally  they  have  been  known  to  be  so  numerous  as 
to  crowd  the  bi-onchi,  and  cause  by  their  irritation  of  the  mucous 
membrane  fits  of  coughing.  The  evidence,  however,  appears  to  be 
quite  inadequate  to  permit  acceptance  of  the  statements  of  various 
German  authors  that  these  Mites  are  the  frequent  cause  of  enteritis, 
peritonitis,  etc.,  in  Fowls.  Symjplectoptes  cysticola  belonging  to  the 
second  genus  of  Sarcoptid  Cysticoles  is  also  peculiar  to  the 
Gallinacea  living  in  the  connective  tissue,  but  does  not  appear  to 
affect  the  health  of  the  birds.  The  cysts  containing  these  Mites 
are  yellow  oval  bodies  about  1  mm.  long,  sometimes  very 
numerous,  and  their  contents  are  soft,  granular,  and  adipose  or 
calcareous — much  like  those  of  tubercle ;  and  are  to  be  found  on 
the  abdominal  viscera,  in  the  peritoneum,  in  the  muscles,  and 
beneath  the  skin.  Biologically  and  pathologically,  the  account 
given  by  Neumann  of  these  Acarids  peculiar  to  the  Gallinacea  is 
of  great  interest  as  showing  their  relatively  similar  results  in  the 
host  to  those  of  the  Acari  infecting  the  lungs  of  Mammals. 

I  would  express  my  thanks  to  Mr.  Chas.  D.  Soar  for  looking 
over  my  notes  and  specimens. 


Bibliography. 

1.  Allman. — Description   of  a   New  Genus  and   Species   of    Tracheary 

Arachnidans.     Ann.  &  Mag.  Nat.  Hist.,  xx.  47  (1847). 

2.  Banks,  N.— A  Treatise  on  the  Acarina  or  Mites.     Proc.  U.S.  Nat.  Mus., 

xxviii.  1-114  (1904). 

3.  Newstead,  K.,  &  Todd,  J.  I. — On  a  New  Dermanyssid  Acarid,  Pneu- 

monyssus  duttoni  sp.  n.     Liverpool  School  Trop.  Med.  Mem.,  xviii. 
41. 

*  After  Dr.  Herbert  Fox,  who  Weidman  states  performed  the  autopsy  on  the 
Monkey,  recognized  the  parasitic  nature  of  the  lesions  and  submitted  all  the 
material  to  him. 


168  Transactions  of  the  Society . 

4.  Newstead,   R. — Another   New    Dermanyssicl   Acarid,   Pneiimonyssus 

gri-ffithi  sp.  n.     Liverpool  School  Trop.  Med.  Mem.,  xviii.  47. 

5.  Landois,  F.,  &  HoEPKE,  H.     Eine  endoparasitare  Milbe  in  du  lunge 

von   Macacus   rhesus.     Centralb.   f.    Bakteriol.,    Abt.    i.,  Orig.|  73, 
384-91  (1914). 

6.  Weidman,    Fred.   D.  —  Pneumonyssus   foxi    sp.  n. :    An'  Arachnoid 

Parasitic  in  the  Lung  of  a  Monkey  {Macacus  rhesus).     Jour.  Para- 
sitology, ii.  37. 

7.  Neumann,  L.  G. — Treatise  on  the  Parasites  and  Parasitic  Diseases  of 

Domesticated  Animals.     Translated  and  edited  by  Geo.  Flemming> 
C.B.,  LL.D.  (1892). 


169 


VI. — The  Lyco^odium  Method  of  Quantitative  Microscopy, 
By  T.  E.  Wallis,  B.Sc.  (Lond.),  FJ.C. 

{Read  March  17,  1920). 
One  Text-Figure. 

The  use  of  the  microscope  for  quantitative  measurements  is 
attended  by  many  difficulties.  Such  determinations  are,  however, 
of  great  importance,  since  they  offer^the  only  available  method  of 
solving  certain  analytical  problems.  For  example,  the  proportion 
of  maize  starch  added  to  the  ordinary  wheat  flour  cannot  be  deter- 
mined by  chemical  methods,  which  will  give  accurately  the  total 
starch  present,  but  fail  to  differentiate  between  different  starches. 
Similarly  one  can  determine  chemically  the  total  woody  structures 
(crude  fibre)  in  a  powder-like  pepper  or  gentian  root,  but  cannot 
tell  what  proportion  consists  of  foreign  stone  cells,  if  such  are 
present.  Both  these  problems  can  be  satisfactorily  solved  by 
microscopical  methods. 

In  carrying  out  work  of  this  kind  attention  must  be  given  to 
such  thorough  mixing  of  the  materials  as  will  assure  efficient 
sampling.  The  necessity  for  care  in  this  particular  is  evident 
from  the  fact  that  the  result  is  based  upon  observations  made  of 
the  composition  of  a  very  minute  quantity  of  powder — namely, 
that  which  occupies  about  twenty  fields  of  view.  Assuming  that 
there  is  about  0*2  grm.  of  substance  in  10  to  20  c.c.  of  the 
fluid  used  as  a  suspending  agent,  and  that  one  is  working  with  a 
one-sixth  inch  objective,  then  under  ordinary  circumstances  twenty 
fields  will  represent  from  one-250th  to  one-lOOth  part  of  a  milli- 
gramme of  powder.  The  mixing  then  must  be  so  thorough  that 
every  200th  part  or  thereabouts  of  a  milligramme  of  the  mixture 
shall  have  a  composition  similar  to  that  of  the  whole  sample. 

The  suspending  agent,  too,  must  be  of  a  suitable  character.  It 
should  not  bring  about  a  separation  of  the  constituents,  and  should 
not  allow  the  suspended  material  either  to  sink  or  to  rise  too 
rapidly.  It  should  also  contain  no  structures  that  could  be  mis- 
taken for  any  that  are  present  in  the  powder  under  investigation. 

Further,  the  materials  for  the  determination  of  which  quanti- 
tative methods  are  needed  are  of  very  varied  types,  ranging  from 
substances  like  starches,  whose  structure  is  quite  simple,  to  powders 
of  increasing  complexity,  such  as  olive  stones,  mixed  flours,  pepper, 
insect  flowers,  etc. 


170  Transactions  of  the  Society. 

Perhaps  the  greatest  difficulty  with  which  one  is  faced  is  to 
devise  a  simple  means  of  ascertaining  the  quantity  of  material  in 
which  certain  specified  particles  have  been  counted  by  the  micro- 
scope. 

Some  of  the  earlier  methods  proposed  and  used  {1  to  5*)  give 
only  approximate  results,  with  an  uncertain  range  of  error,  and 
may  lead  to  erroneous  conclusions.  Other  more  reliable  methods 
require  either  a  specially  constructed  mechanical  stage  {6  and  7), 
or  a  specially  made  glass  slide  with  squares  of  a  known  size  ruled 
over  a  limited  area  equal  to  that  of  the  cover-glass  used  {8),  or  a 
glass  slide  with  a  well  of  a  particular  depth  and  squares  engraved 
upon  the  enclosed  area  {9).  All  these  methods  are  of  limited 
application,  and  are  tedious  to  carry  out. 

To  bring  quantitative  measurements  within  the  sphere  of 
regular  microscopical  practice,  one  needs  a  general  method  applic- 
able with  slight  modifications  to  a  wide  range  of  substances,  and 
requiring  no  specially  constructed  apparatus.  The  method  should 
be  simple  in  principle,  and  reliable  within  comparatively  narrow 
limits  for  all  percentages  of  admixture.  The  use  of  lycopodium  as 
suggested  by  the  author  {12)  provides  such  a  generally  applicable 
process  which  gives  results  rarely  showing  an  error  greater  than 
10  p.c.  of  the  amount  to  be  determined.  It  is  therefore  possible, 
for  example,  in  dealing  with  an  admixture  present  to  the  extent  of 
20  p.c.  to  obtain  a  result  that  will  lie  between  18  and  22  p.c. 
Kesults  showing  this  order  of  accuracy  are  quite  equal  to  many  of 
those  obtained  by  chemical  operations,  and  the  careful  use  of  this 
lycopodium  method  entitles  microscopical  quantitative  determina- 
tions of  suitable  materials  to  rank  on  an  equality  with  those  made 
by  the  use  of  many  well-tried  chemical  processes. 

Outline  of  the  Method. 

In  general  outline  the  method  of  procedure  is  as  follows  : — 
The  nature  of  the  admixture  is  first  ascertained,  and  a  powder  con- 
taining this  ingredient  and  the  pure  substance  in  equal  proportions 
is  prepared.  Of  this  50  p.c.  mixture  a  convenient  weighed  amount 
(about  0*2  grm.  in  most  cases)  is  mixed  with  a  weighed  quan- 
tity (about  0  •  1  grm.)  of  lycopodium  spores,  and  with  a  suitable 
volume  (about  20  c.c.)  of  a  suspending  agent  such  as  mucilage  of 
tragacanth,  olive  oil  or  castor  oil. 

A  drop  of  the  suspension  is  mounted  for  microscopical  examina- 
tion and  the  number  of  lycopodium  spores  ajid  of  characteristic 
elements  of  the  powder  are  counted  in  ten  fields  selected  according 
to  the  scheme  described  below.  A  second  drop  of  the  suspension 
is  mounted  and  ten  fields  counted  as   for  the  first  slide,  and  the 

*  The  italic  figures  in  brackets  refer  to  the  Bibliography  at  the  end  of  the 
paper. 


The  Lycojpodium  Method  of  Quantitative  Microscopy.       171 

result  should  agree  closely  with  that  previously  obtained.  In  case 
of  a  disagreement  greater  than  10  p.c,  which  will  rarely  occur  in 
practice,  fresh  counts  must  be  made. 

One  next  prepares  a  suspension  of  a  similar  weighed  quantity 
of  the  article  to  be  examined,  mixed  with  an  amount  of  lycopodium 
spores  equal  to  tlie  weight  of  spores  used  in  the  first  part  of  the 
experiment.  Drops  of  this  suspension  are  mounted,  and  counts  of 
twenty  fields  are  made  as  in  the  former  case. 

For  both  suspensions  the  number  of  characteristic  particles 
counted  for  100  lycopodium  spores  is  calculated.  These  two 
numbers  represent  the  quantities  by  weight  of  one  ingredient  present 
in  equal  weights  of  the  two  mixtures,  and  since  one  percentage  is 
known,  the  other  is  immediately  obtained  by  simple  proportion. 


Example. 

An  example  will  simplify  the  explanation.  It  was  desired  to 
find  the  proportion  of  maize  starch  that  had  been  added  to  some 
ordinary  wheat  flour.  A  mixture  of  wheat  flour  and  maize  starch 
in  equal  proportions  was  prepared,  and  0  *  2  grm.  of  this  mixture 
was  carefully  mixed  with  0*1  grm.  of  lycopodium  spores,  and 
about  20  c.c.  of  mucilage  of  tragacanth.  A  drop  of  the  suspension 
was  mounted,  and  the  following  counts  obtained  in  ten  selected 
fields : — 

Lycopodium  spores   .         .     14,  15,  7,  11,  11,  5,  4,  13,  12,  10  =  102 

Maize  starch  grains    .  .     43,  74,  53,  33,  61,  39,  25,  38,  57,  59      =  482 

Giving  473  maize  starch  grains  for  100  lycopodium  spores. 

A  second  slide  was  prepared  by  mounting  another  drop  of  the 
same  suspension,  and  the  counts  obtained  were  as  follows : — 

Lycopodium  spores    .  .     11,  11,  11,  7,  12,  7,  4,  9,  9,  12  =     92 

Maize  starch  grains   .  .     61,  45,  57,  52,  63,  28,  23,  37,  47,  86      =  439 

Giving  477  maize  starch  grains  for  100  lycopodium  spores. 

It  will  be  seen  that  the  two  sets  of  counts  give  closely  similar 
results,  and  the  average  for  the  50  p.c.  mixture  is  475  maize  starch 
grains  for  100  lycopodium  spores. 

The  adulterated  wheat  flour  was  next  similarly  examined  by 
mixing  0  •  2  grm.  of  the  flour  with  0  •  1  grm.  of  lycopodium  spores, 
and  about  20  c.c.  of  mucilaoje  of  traG^acanth. 

Ten  fields  from  the  first  slide  gave  the  following  counts : — 

Lycopodium  spores    .  .     13,  10,  14,  20,  21,  11,  4,  14,  16,  12        =   135 

Maize  starch  grains  .  .     48,  88,  42,  87,  64,  25,  24,  43,  77,  49      =  497 

Giving  368  maize  starch  grains  for  100  lycopodium  spores. 


172  Transactions  of  the  Society. 

Ten  fields  from  the  second  slide  gave  counts  as  follows : — 

Lycopodium  spores    .         .     11,  6,  5,  8,  12,  5,  8,  8,  14,  6  =83 

Maize  starch  grains  .         .     30,  28,  34,  46,  26,  17,  18,  11,  44,  40      =  294 

Giving  354  maize  starch  grains  for  100  lycopodium  spores. 

The  average  for  the  twenty  fields  is  361   maize  starch  grains  for 
100  lycopodium  spores. 

Hence  a  certain  weight  of  the  50  p.c.  mixture  contains  475 
maize  starch  grains,  and  an  equal  weight  of  the  adulterated  flour 
contains  361  maize  starch  grains.  Therefore  the  amount  of  maize 
starch  in  the  flour  is  50  X  361-4-  475  =  38  p.c.  The  actual 
amount  of  maize  starch  present  in  the  flour  was  37  *  8  p.c. 


Eemarks. 

The  flour  and  lycopodium  are  mixed  by  rubbing  them  together 
by  means  of  a  flexible  steel  spatula  upon  a  glass  plate  or  porcelain 
slab.  The  mucilage  of  tragacanth,  which  is  prepared  by  mixing 
1  •  25  grm.  of  powdered  gum  tragacanth  with  2  •  5  c.c.  of  alcohol 
(90  p.c),  and  adding  100  c.c.  of  distilled  water  as  rapidly  as 
possible  and  shaking  vigorously,  should  be  made  some  hours 
before  it  is  needed  for  use  so  that  the  gum  may  be  fully  swollen. 
This  suspending  agent  is  best  added  a  little  at  a  time  and 
thoroughly  incorporated  with  the  powder  on  the  glass  plate  by 
trituration  with  the  spatula.  The  mixture  is  transferred  to  a 
corked  or  stoppered  tube,  and  the  plate  is  cleaned  by  adding  more 
mucilage  in  small  quantities  at  a  time,  mixing  it  with  any  residue 
and  transferring  the  successive  quantities  to  the  tube  until  none 
of  the  powder  remains  on  the  plate.  The  contents  of  the  tube  are 
thoroughly  shaken  up  and  a  drop  is  quickly  removed  with  a  glass 
rod  and  mounted  for  examination. 

The  fields  in  which  the  counts  are  made  are  selected  so  as  to 
include  some  from  all  parts  of  the  preparation.  This  is  necessary 
because  the  mount  may  be  thinner  on  one  side  than  on  another, 
thus  resulting  in  a  slight  unevenness  of  distribution.  It  is  also 
necessary  to  avoid  counting  the  same  field  twice,  hence  the  positions 
of  the  fields  are  fixed  beforehand  by  choosing  such  as  are  at  certain 
measured  distances  from  the  centre  of  the  cover-glass.  The  slide 
is  placed  on  the  stage  of  the  microscope  so  that  the  centre  of  the 
cover-glass  is  immediately  beneath  the  front  lens  of  the  objective, 
and  the  position  of  tlie  right-hand  near  corner  is  read  off  on  the 
two  graduated  scales  of  the  mechanical  stage.  The  slide  is  then 
moved  by  means  of  the  milled  heads  which  actuate  the  mechanical 
stage  until  each  specified  field  is  brought  in  succession  under  the 
microscope  objective.     The  positions  suggested  for  the  fields  are 


The  Lycopodium  Method  of  Quantitative  Microscopy.      173 

those  shown  in  the  diagram,  where  the  numbers  indicate  distances  in 
millimetres  from  the  centre  of  the  cover-glass,  while  the  +  and  — 
signs  denote  directions  right  and  left  or  above  and  below  the  two 
diameters  which  are  parallel  to  the  directions  of  movement  of  the 
stage.  To  facilitate  the  actual  counting,  a  disc  of  glass  ruled  in 
millimetre  squares  is  dropped  on  to  the  diaphragm  of  the  eye-piece 
and  particles  are  counted  successively  along  each  line  of  squares 
until  the  whole  field  has  been  covered. 

Mucilage  of  tragacanth  and  olive  oil  are  the  most  generally 


Note, — The  figures  in  this  diagram  not  preceded  by  a  sign  are  to  be 
read  as  having  a  +  sign  prefixed  to  them. 

useful  suspending  agents.  When  the  mucilage  is  used  for  oily 
powders,  the  oil  or  fat  must  be  removed  by  a  preliminary  extraction 
with  a  suitable  solvent.  Olive  oil  may  be  used  for  the  suspension 
of  almost  any  material  that  is  in  an  ordinary  air-dry  condition ;  it 
is  particularly  suitable  for  oily  substances  and  in  cases  where  it  is 
necessary  to  use  the  polariscope,  as  for  the  analysis  of  a  mixture  of 
wheat  and  potato  starches. 


MEA.SUREMENTS   OF   WEIGHT. 


The  use  of  lycopodium  in  the  manner  suggested  gives  one  a 
measure  of  the  relative  proportions  of  the  quantities  of  material 


174  Transactions  of  the  Society. 

present  in  various  preparations,  so  that  when  one  is  known  the 
other  can  be  calculated.  It  does  not,  however,  enable  one  to 
determine  the  actual  weights  of  the  material  in  which  the  counts 
have  been  made.  One  can  immediately  ascertain  the  weight  of 
any  counted  number  of  lycopodium  spores  if  one  knows  the 
average  weight  of  one  spore,  or,  as  it  is  more  conveniently  expressed,, 
the  number  of  spores  per  milligramme  of  lycopodium.  Then,  since 
the  lycopodium  and  other  material  have  been  mixed  in  known 
proportions  by  weight,  the  corresponding  weight  of  the  other 
substance  can  be  found  by  a  simple  calculation.  This  weight  of 
material  contains  the  counted  number  of  characteristic  particles, 
and  from  this  can  be  calculated  the  number  of  such  particles  per 
milligramme.  Hence  for  each  substance  there  is  a  definite  number 
representing  the  countable  particles  per  milligramme,  and  these 
figures  can  be  used  as  a  means  of  characterizing  or  of  standardizing 
the  material.  Such  figures  are  not  always  suitable  for  calculating 
the  amount  of  the  substance  present  in  mixtures,  for  which  purpose 
it  is  better  to  obtain  a  special  number  by  counting  a  mixture  of 
known  composition  containing  the  same  ingredients,  but  not 
necessarily  in  the  same  proportions  as  the  material  to  be  examined. 
The  figures  representing  pure  substances  form  a  useful  check  upon 
those  obtained  by  counting  standard  mixtures,  but  cannot  safely  be 
used  in  their  place. 


Determination  of  the  Number  of  Spores  per 
Milligramme  of  Lycopodium. 

The  number  of  spores  per  milligramme  of  lycopodium  has  been 
shown  to  average  94,000,  a  figure  which  was  obtained  by  weighing 
accurately  about  0*1  grm.  of  lycopodium  and  mixing  it  with  a 
definite  weight,  about  10  to  12  grm.,  of  olive  oil  or  mucilage 
of  tragacanth.  A  clean  microscopic  slide  and  cover-glass  were 
then  weighed,  and  a  drop  of  the  suspension  was  mounted  on  the 
slide,  which  was  again  weighed,  thus  giving  the  weight  of  the 
suspension  on  the  slide.  Twenty  fields  were  then  counted  accord- 
ing to  a  pre-arranged  plan  similar  to  that  advocated  for  quantitative 
microscopy  in  general.  The  total  counted  number  of  spores- 
multiplied  by  the  area  of  the  cover-glass  and  divided  by  the  area 
of  twenty  fields  gives  the  number  of  spores  under  the  cover-glass. 
From  this  number,  the  total  weight  of  suspension  and  the  weight 
of  suspension  mounted  on  the  slide,  one  obtains  the  number  of 
spores  per  milligramme. 

The  following  example  will  show  how  the  result  is  obtained : — 

Weight  of  lycopodium     .....=  0*1102  grm, 
Weight  of  suspension  (oil  and  lycopodium)       .      =   9*8560   ,, 
Weight  of  suspension  on  the  slide    .  .         .      =  0*0276   „ 


The  Lycopodium  Method  of  Qioantitative  Microscopy.      175 

The  counts  of  spores  in  twenty  fields  were,  22,  25,  19,  18,  32^ 
4,  13,  10,  20,  25,  24,  26,  9,  18,  7,  10,  10,  22,  29,  30,  giving  a  total 
of  373  spores. 

Area  of  20  fields  .         .         .         .      =  20  x  0*2003  sq.  mm. 

=  4 '006  sq.  mm. 
Area  of  the  cover-glass  .  .  .      =  322  sq.  mm. 


Nmnber  of  spores  under  the  cover-glass 


373  X  322 

4-006 
29,983 


Nmnber  of  spores  per  milligramme       .     =  ^9, 983  x  9-856 
^  0-0276  X  110-2 

=  97,170 

The  mean  of  twenty-six  determinations  was  93,000.  This 
figure  was  confirmed  by  calculation  from  the  linear  dimensions  and 
the  specific  gravity  of  lycopodium  spores,  which  gave  the  number 
95,000.     The  mean  of  the  results  is  therefore  94,000  (IS). 


Determination  of  the  Number  of  Starch  Grains 
PER  Milligramme  of  Maize  Starch. 

The  number  of  starch  grains  per  milligramme  of  starch  dry  at 
100°  C.  can  be  used  to  characterize  a  starch.  The  figure  was  found 
by  the  following  method  in  the  case  of  a  sample  of  commercial 
maize  starch: — 0*2  grm.  of  lycopodium  was  mixed  with  0*1  grm. 
of  maize  starch  and  about  20  c.c.  of  olive  oil.  Four  slides  were 
prepared  by  mounting  drops  of  the  suspension,  and  the  counts 
obtained  gave  480,  477,  436,  and  410  starch  grains  respectively,  or 
on  an  average  450  grains  for  every  100  lycopodium  spores.  Hence 
there  are  450  X  94,000  -^  100  starch  grains  for  every  milligramme 
of  lycopodium,  and  since  this  weight  of  lycopodium  was  mixed 
with  0-5  milligramme  of  starch  there  are  2  x  450  X  94,000  -r-  100 
=  846,000  starch  grains  per  milligramme  of  air-dry  starch.  Allow- 
ing for  13*4  p.c.  of  moisture,  there  are  846,000  x  100 -^  86  "6 
=  977,000  grains  per  milligramme  of  maize  starch  dry  at  100°  C. 
This  number  represents  the  sample  of  maize  starch  examined,  but 
further  research  is  needed  before  one  can  regard  it  as  characteristic 
of  maize  starch  in  general. 


Other  Practical  Applications. 

Examples  of  the  use  of  these  figures  as  a  means  of  standardiza- 
tion are  to  be  found  in  the  determination  of  the  number  of  pollen 
grains  present  in  such  powders  as  Kousso  and  Insect  Flowers. 
Kousso  is  a  well-known  anthelmintic,  and  consists  of  the  dried 


176  Transactions  of  the  Society. 

panicles  of  pistillate  flowers  of  Brayera  antlulmintica  Kunth 
(N.O.  Eosacese).  This  drug  is  frequently  adulterated  by  the 
admixture  of  staminate  flowers.  The  pistillate  flowers  always 
yield  a  few  pollen  grains  which  have  lodged  among  the  floral  whorls 
or  are  adherent  to  the  stigmas,  but  beyond  this  very  small  number 
pollen  grains  should  be  absent.  It  has  been  shown  by  Arthur 
Meyer  (7)  that  this  number  should  not  exceed  200  per  milligramme, 
^nd  if  more  than  this  number  are  found  the  presence  of  staminate 
flowers  in  excessive  amount  is  definitely  established. 

In  the  case  of  Insect  Flowers,  one  desires  to  find  a  powder 
having  as  high  a  number  as  possible  of  the  characteristic  pollen 
grains.  Insect  powder  consists  of  the  powdered  unexpanded 
flower-heads  of  Chrysanthenunn  cincraricefoliuni  Vis  (N.O.  Com- 
positae),  and  if  admixed  with  fully  expanded  flower-heads  an 
inferior  article  results.  The  more  fully  expanded  heads  contain 
less  pollen  grains,  and,  if  present  in  the  powder,  considerably  lower 
the  number  of  pollen  grains  per  milligramme.  Lehmann  and 
Trottner  {IJ/)  have  show^n  that  a  powder  made  from  the  buds  of 
Dalmatian  Insect  Flowers  contains  about  2000  pollen  grains  per 
milligramme,  while  partly  expanded  flowers  yield  1000  to  2000 
pollen  grains  per  milligramme,  and  they  suggest  that  any  powder 
containing  less  than  500  per  milligramme  should  be  rejected  as  of 
inferior  quality.  The  followiDg  example  shows  how  this  number 
■was  determined  in  the  case  of  a  sample  of  insect  powder  recently 
submitted  to  the  author  for  examination  as  to  its  quality : — 


Number  of  Pollen  Grains  per  Milligramme 
OF  Insect  Pow^der. 

One  grm.  of  the  insect  powder  was  carefully  mixed  with 
€'05  grm.  of  lycopodium,  and  from  the  mixture  a  crude  fibre  was 
prepared  by  boiling  it  in  a  porcelain  disli  for  thirty  seconds  with 
50  c.c.  of  10  p.c.  nitric  acid,  and  filtering  under  reduced  pressure 
through  a  piece  of  moistened  Horrockses'  longcloth  M.  2,  stretched 
over  a  Buchner  funnel  supported  in  a  filtering  flask.  The  residue 
on  the  cloth  was  washed  with  about  100  c.c.  of  boiling  water, 
returned  to  the  dish  and  boiled  for  thirty  seconds  with  50  c.c.  of 
2 '5  p.c.  aqueous  caustic  soda,  filtered  through  the  cloth  at  the 
pump  and  washed  with  boiling  water.  The  crude  fibre  containing 
the  lycopodium  was  removed  from  the  strainer  and  carefully  mixed 
with  mucilage  of  tragacanth  until  the  volume  "was  about  20  c.c. ; 
the  whole  was  Avell  shaken  in  a  stoppered  tube  and  a  drop  was 
mounted  for  microscopical  examination.  The  number  of  pollen 
grains  was  counted  in  a  strip  across  a  diameter  of  the  cover-glass 
having  a  width  equal  to  the  diameter  of  the  field  of  view"  in  the 
microscope.     This  number  was  found  to  be  71.     The  number  of 


The  Lycopodium  Method  of  Quantitative  Microscopij.      177 

lycopodium  spores  present  in  20  fields  evenly  distributed  along 
the  same  diameter  was  100,  giving  an  average  of  5  spores  per  field 
of  view;  hence  in  the  whole  diameter  (equal  to  45*8  fields 
of  view)  there  were  5  x  45*8  =  229  spores.  There  were  there- 
fore 71  pollen  grains  for  every  229  lycopodium  spores,  and  hence 
71  X  94,000  -4-  229  =  29,100  pollen  grains  for  every  milligramme 
of  lycopodium  (  =  94,000  spores).  Hence  for  0  *  05  milligramme  of 
lycopodium  there  were  29,100  -4-  20  =  1450  pollen  grains,  and 
since  0*05  milligramme  of  lycopodium  was  mixed  with  every 
milligramme  of  insect  flowers  there  were  1450  pollen  grains  per 
milligramme  of  insect  powder,  which  was  therefore  a  perfectly 
satisfactory  example  from  this  point  of  view. 


Conclusion. 

Other  more  difficult  problems  upon  which  a  certain  amount  of 
preliminary  research  has  already  been  done  are  such  as  the  deter- 
mination of  the  percentage  of  wheat  flour  in  mixtures  of  wheat 
and  barley,  and  of  the  percentage  of  foreign  stone  cells  in  powders 
like  pepper  and  gentian.  Almost  every  problem  presents  its  own 
special  difficulties  which  may  involve  an  inquiry  into  the  range  of 
variation  found  in  different  varieties  of  the  same  material,  and  a 
much  more  close  scrutiny  of  details  than  has  been  necessary  where 
only  qualitative  results  were  desired.  For  this  reason  progress 
must  be  slow,  but  the  fundamental  principle  of  the  lycopodium 
method  is  applicable  in  all  cases,  and  an  ultimate  solution  of  the 
difficulties  is  brought  within  the  reach  of  microscopists. 


Eeferences. 

1.  Cleaver,  E.  L. — Admixture   of  Oatmeal   with   Barley-Meal.     Analyst 

(1877)  1,  p.  189. 

2.  Bell,  James — The  Analysis   and  Adulteration  of  Foods  (1883)  pt.  2, 

p.  151. 

3.  Allen,  A.  H. — Commercial  Organic  Analysis,  4th  edit.  i.  (1909)  p.  417. 

4.  Clark,  Frederick  C. — The  Microscopical  Examination,  Physical  Test- 

ing, and  Chemical  Analysis  of  Paper  (New  York,  1917). 

5.  SiNDALL,  E.  W.— Paper  Technology  (1906)  p.  149. 

6.  Meyer,  Arthur — Grundlagen  und   Methoden  fur   die  mikroskopische 

Untersuchung  von  Pflanzenpulvern  (1901)  pp.  125-37. 

7.  Der    Artikel    "  Flores  Koso "    des    Arzneibuches  und    eine   neue 

Methode  der  quantitativen  mikroskopischen  Analyse.  Archiv  der 
Pharmazie  (1908)  246,  pp.  523-40. 

8.  Linde,   0.  —  Zur  Untersuchung   des   Kosobliitenpulvers.      Apotheker- 

Zeitung  (1911)  26,  p.  136. 

9.  Hartwich,   C,  &  WicHMANN,   A. — Einige  Beobachtungen  an    Starke- 

kornen  und  iiber  die  Zahlkammer,  ein  Hilfsmittel  zur  quantitativen 
Ermittelung  von  Verfiilschungen  vegetabilischer  P'jlver.  Archiv  der 
Pharmazie  (1912)  250,  p.  452. 

N 


178  Transactions  of  the  Society. 

10.  Bruijning,  F.  F. — De  ontwikkeling  der  techniek  van  het  microscopisch 

onderzoek  der  veevoederstofifen  aan  de  Eijkslandbouwproefstations, 
gedurende  de  laatste  25  jaren,  in  het  bijzonder  met  betrekking  tot 
lijnkoek.     Pharmaceutiscb  Weekblad  (1915)  Nos.  9-10. 

11.  Chamot,  E.  M. — Elementary  Chemical  Microscopy  (1916)  pp.  205-19. 

12.  Wallis,  T.  E.— Quantitative  Microscopy.   Analyst  (1916)  41,  pp.  357-74. 

13.  The   Use   of  Lycopodium  in  Quantitative  Microscopy.     Pharm. 

Journ.  iv.  (1919)  49,  p.  75. 

14.  Lehmann  &  Trottner — Eevist.  farm,  through  Kepertoire  Pharm.  (1917) 

28,  49. 


179 


SUMMARY  Of  CUERENT  RESEARCHES 

RELATING   TO 

ZOOLOGY      AND      BOTANY 

(principally  invertebrata  and  cryptogamia), 

•    MICROSCOPY,    Etc.* 


ZOOLOGY. 
VERTEBRATA. 


a.  Embryolog-y,  Evolution,  Heredity,  Reproduction, 
and  Allied  Subjects. 

Individuality  of  Germ-nuclei  in  Cleavage  Stages  of  Crypto- 
branchus  allegheniensis. — Bertra:^i  G.  Smith  {Froc.  Amer.  Soc. 
Zool.  in  Anat.  Record,  1920,  17,  323).  The  germ-nuclei  do  not  fuse  in 
fertilization.  In  the  first  cleavage  mitosis  each  gives  rise  to  a  separate 
group  of  chromosomes  whose  descendants  pass  separately  to  the  daughter- 
nuclei.  During  the  ensuing  resting  stage  each  germ-nucleus  is  repre- 
sented by  a  structurally  distinct  vesicle.  Throughout  early  cleavage 
the  nuclear  divisions  are  duplex,  and  the  resting  nuclei  distinctly  double. 
The  genetic  continuity  of  each  half  of  the  double  nucleus  has  been 
clearly  traced  to  an  advanced  cleavage  stage,  and  even  in  the  early 
gastrula.     But  the  double  structure  becomes  increasingly  disguised. 

J.  A.  T. 

Causal  Factor  in  Hatching  of  Chick. — A.  Gr.  Pohlman  {Aiiat. 
Recorcl,^  1919,  17,  89-104,  2  charts).  Doubt  is  cast  on  Keibel's  account 
of  the  importance  of  the  musculus  complexus  in  causing  the  bill  and  egg- 
tooth  to  strike  forcibly  against  the  shell.  The  musculus  complexus  does 
attain  a  maximum  development  before  and  at  the  stage  of  hatching,  and 
shows  a  progressive  atrophy  after  the  chick  is  hatched,  to  the  eighth 
clay  at  least.  But  before  the  time  of  hatching  the  muscle  is  infiltrated 
with  lymph,  which  attains  its  maximum  with  the  complete  injection  of 
the  yolk  and  the  discharge  of  the  allantoidal  blood  into  the  systemic 
vessels.  The  infiltrated  muscle  is  physiologically  incapacitated  from 
pronounced  muscular  contraction,  and  one  reason  for  the  marked  infil- 
tration is  undoubtedly  its  relaxed  condition.  The  active  muscular  agent 
in  breaking  the  shell  comes  about  through  a  change  in  the  position  of 

*  The  Society  does  not  hold  itself  responsible  for  the  views  of  the  authors 
of  the  papers  abstracted.  The  object  of  this  part  of  the  Journal  is  to  present 
a  summary  of  the  papers  as  actually  xmhlished,  and  to  describe  and  illustrate 
Instruments,  Apparatus,  etc.,  which  are  either  new  or  have  not  been  previously 
described  in  this  country. 

N  2 


180  SUMMARY   OF   CURRENT  RESEARCHES   RELATING  TO 

the  head  and  upper  cervical  vertebrae  chiefly  dependent  on  muscuhis 
biventer  and  muscuhis  spinahs.  The  head  shifts  from  the  normal  egg 
position  of  flexed  lateral  rotation  to  one  of  extension  more  nearly  on 
the  vertebral  axis.  The  reflex  mechanism  which  touches  off  the  muscles 
referred  to  is  probably  a  respiratory  reflex  (drinking-choking  reflex), 
not  dependent  on  demand  for  oxygen,  but  dependent  on  distention  of 
the  abdomen,  particularly  the  muscuhis  levator  ani,  brought  about 
through  injection  of  the  yolk-sac.  The  enormous  lymph  infiltration  is 
a  result  of  rapid  absorption,  partly  due  to  pressure  and  partly  due  to- 
awakened  glandular  activity,  as  positive  factors,  and  to  th^  failure  of 
the  kidneys  to  deal  with  the  excess  of  water,  as  a  negative  factor.. 
Not  until  respiration  sets  in  does  the  general  oedema  disappear,  which 
implies  that  most  of  the  water  in  birds  is  excreted  by  the  lungs,  and 
also  accounts  for  the  ability  of  the  newly-hatched  chick  to  go  at  least 
three  days  (perhaps  four  or  five)  without  water.  J.  A.  T. 

Hypertrophy  of  Suprarenal  Capsules  in  Pregnant  Rabbit. — 
J.  Watrin  (g.  E.  Soc.  Biol,  1919,  82,  14-.05-7).  The  hypertrophy 
and  increased  functioning  of  the  suprarenal  capsule  during  pregnancy 
has  been  referred  by  some  to  the  influence  of  the  foetus,  whose  waste - 
products  require  additional  anti-toxins  to  counteract  them.  But  the 
hypertrophy  is  seen  also  in  the  thyroid  and  in  the  hypophysis,  which, 
the  author  says,  are  not  known  to  have  an  anti-toxic  function.  On  his 
view  the  hypertrophy  of  the  suprarenal  capsules  is  a  reaction  to  specific 
substances  secreted  by  the  ovum  before  its  fixation  and  by  elements  in 
the  foetal  part  of  the  placenta.  Moreover,  this  reaction  does  not  come 
about  unless  the  suprarenal  capsules  have  been  "  sensibilised  "  by  the 
internal  secretion  of  the  corpus  luteum.  J.  A.  T. 

Nutrition  of  Mammalian  Foetus  from  Maternal  Blood. — Hassan 
EL  Diw^ANY  {G.  R.  Soc.  Biol.,  1919,  82, 1235-7).  Maternal  haemorrhage 
in  the  placenta  at  a  definite  time  during  the  gestation  has  been  studied 
in  sheep,  ferret,  dog,  cat,  and  white  mouse.  In  the  first  four  numerous 
chorionic  villosities  enter  the  hagmorrhagic  mass  and  numerous  maternal 
blood-corpuscles  are  captured  by  phagocytosis.  Free  maternal  haemo- 
globin is  also  observed.  The  chorion  cells  show  biliary  pigments  in 
their  supra-nuclear  portion  and  fatty  droplets  towards  the  base.  In  the 
white  mouse,  cells  of  the  trophoblast  degenerate  in  the  midst  of  the 
extravasated  red  blood-corpuscles,  and  giant  decidual  cells  act  as  the 
phagocytes.  These  giant  cells  degenerate  in  turn  and  their  debris  is 
absorbed  by  the  high  cylindrical  cells  Avhich  form  the  visceral  wall  of 
the  l)lastodermic  vesicle.  The  "  hivmatic  cmbryotrophy,"  the  nutrition 
from  maternal  blood,  gives  the  foetus  an  abundant  supply  of  iron. 

J.  A.  T. 

Testicular  Epithelium.— Ed.  Retterer  {G.  JR.  Soc.  Biol.,  1919, 
82,  lir);]-G).  In  the  human  embryo  and  in  the  child  the  epithelium 
of  the  testis  is  in  cords,  in  the  centre  of  which  lacunas  gradually  appear, 
making  a  tubule.  In  the  middle  of  a  syncytium  of  granular  cells  large 
spermatocytes  appear  with   clear   perinuclear   cytoplasm.     Each   gives 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  181 

rise  to  four  spermatids.  The  mitoses  in  the  proliferation  of  the  testicular 
epithehum  are  associated  with  the  elaboration  of  abundant  protoplasm. 
With  increase  of  as^e  the  divisions  of  the  seminal  epithelium  become 
fewer.  The  seminiferous  tubule  becomes  a  solid  band  or  cord.  The 
intermediate  connective  tissue  increases.  The  testis  is  modified  in 
part  into  islands  of  fibrous  tissue  containing  cells  with  clear  perinuclear 
cytoplasm.  J.  A.  T. 

Aggregation  of  Spermatozoa  of  Sea-urchin  in  Water  in  which  the 
Ova  have  been  Macerated. — J.  Cotte  (C.  R.  Soc.  Biol.,  1919,  82, 
1419-21).  The  spermatozoa  converge  in  groups,  as  if  towards  invisible 
ends.  It  seems  that  the  "  chorion  "  of  the  ova  becomes  dissociated  into 
particles,  and  it  is  likely  that  the  spermatozoa  hurry  towards  these  as  if 
to  ova.  J.  A.  T. 

Secretion  of  Epididymis  in  Hibernating  Bat. — M.  R.  Couerier 
{G.  R.  Soc.  Biol,  1920,  83,  67-9).  During  the  hibernation  there  is  an 
intense  secretion  of  the  epididymis  which  probably  serves  for  the 
nutrition  of  the  spermatozoa,  large  numbers  of  which  are  found  in  the 
canal  of  the  epididymis.  The  spermatozoa  arrange  themselves  radially 
around  the  large  secretory  granules.  In  the  testis  there  is  an  arrest  of 
spermatogenesis  ;  the  seminiferous  tubules  contain  only  spermatogonia 
and  Sertoli's  nuclei  with  hardly  visible  protoplasm.  But  the  interstitial 
tissue  is  much  developed  and  in  full  secretory  activity.  Probably  this 
endocrine  gland  conditions  the  activity  of  the  epididymis.       J.  A.  T. 

Spermatogenesis  in  Anolis  carolinensis. — T.  S.  Painter  {Proc. 
Amer.  Soc.  Zool.  in  Anat.  Record,  1920,  17,  328).  In  this  lizard,  "  the 
American  cham^eleon,"  what  appears  to  be  a  typical  "accessory"  or 
sex-chromosome  is  found  in  the  first  maturation  division  ;  it  is  bipartite 
in  character  and  goes  undivided  to  one  pole  of  the  spindle.  In  the 
second  maturation  division,  the  sex-chromosome,  when  present,  divides. 
The  spermatozoa  are  dimorphic  as  regards  the  sex-chromosome  ;  half 
have  it,  half  are  without  it.  The  autosome  complex  consists  of  ten 
large  chromosomes  and  twenty- two  smaller  bodies.  In  the  first  and 
second  spermatocyte  divisions  five  large  and  eleven  small  chromosomes 
are  seen  (in  addition  to  the  sex-chromosome),  and  these  divide  in  the 
usual  way.  There  is  no  "  double  reduction."  There  is  essential  agree- 
ment as  regards  the  chromosomes  with  what  occurs  in  insects  and  other 
Invertebrates.  J.  A.  T. 

Monsters  Produced  by  X-rays. — W.  M.  Baldwin  {Anat.  Record, 
1919,  17,  135-63,  2  pis.).  Experiments  on  developing  frogs'  eggs 
show  that  the  mitotic  routine  may  be  altered,  that  the  cytoplasm  is 
affected  as  well  as  the  chromatin,  that  growth  and  differentiation  are 
affected,  that  the  action  of  the  rays  is  selective,  and  that  definite  changes 
of  a  chemical  nature  in  the  protoplasmic  content  of  the  cells  and  in 
their  enzymes  may  be  produced  by  X-ray  energy.  Experimental 
evidence  at  present  points  to  a  definite  chemical  intracellular  chemical 
reaction  which  may  lead  to  structural  abnormalities.  J.  A.  T. 


182  SUMMARY   OF   CUEEENT   EESEAECHES   EELATING   TO 

Early  Development  of  Peripheral  Nerves  in  Vertebrate  Embryo. 
— H.  H.  Lane  {Proc.  Amer.  Soc.  Zool  iu  Anat.  Record,  1920, 17,324). 
The  chief  nerve  trunks  are  laid  down  before  distinctly  nervous  functions 
can  be  present.  In  the  rat  embryo  of  23  mm.  in  length  the  vestibular 
and  cochlear  nerves  are  well  developed,  though  there  is  no  hearing  until 
about  the  twelfth  day  after  birth  ;  in  the  16  mm.  embryo  the  vibrissa 
have  not  emerged,  yet  the  maxillaris  and  mandibularis  branches  of  the 
trigeminus  are  well  formed.  According  to  Harrison's  experiments  on 
the  cultivation  of  tissues  in  vitro,  each  neurone  sends  out  its  axone  in  a 
predetermined  manner  and  direction  to  a  distance  of  a  millimetre  or  so, 
enough  to  reach  at  an  early  stage,  but  only  at  an  early  stage,  to  the 
part  it  is  destined  to  innervate.  J.  A.  T. 

Branchial  Segmentation  of  Cranial  Nerves. — K  Betchov  {Revue 
Suisse  Zool.,  1918,  26,  233-44,  2  figs.).  It  is  a  common  usage  to 
refer  the  trigeminal  to  the  first  branchial  arch,  the  facial  to  the  second, 
the  glosso-pharyngeal  to  the  third,  and  the  vago-spinal  to  the  remainder. 
The  author  indicates  some  of  the  difficulties  in  this  interpretation  and 
proposes  another.  The  trigeminal  is  the  nerve  of  the  buccal  cleft. 
The  acustico-facial  is  associated  with  the  first  branchial  cleft,  the  glosso- 
pharyngeal with  the  second,  the  superior  laryngeal  with  the  third,  the 
recurrent  spinal  with  the  sixth.  The  fourth  and  fifth  clefts  no  longer 
possess  special  innervation.  Hia  interpretation  appHes  directly  to 
mammals.  J.  A.  T. 

Development  of  Pancreas. — Aeox  (C  R.  Soc.  Biol.,  1919,  82, 
1428-30).  A  study  of  the  pancreas  in  embryos  of  the  pig  goes  to  show 
that  the  endocrinal  gland  appears  somewhat  late  in  the  course  of 
development,  and  suggests  that  the  embryonic  pancreas  may  have  an 
erythropoietic  function,  like  the  embryonic  liver,  but  more  restricted 
and  more  accessory.  J.  A.  T. 

Development  of  Thymus,  Parathyroid  and  Ultimo-branchial  Bodies 
in  Turtles. — C.  E.  Johnson  {Proc.  Amer.  Soc.  Zool.  in  Anat.  Record, 
1920,  17,  325-6).  In  embryos  of  Ghelydra,  Ghrysemis,  Triomjx  the 
thymus  arises  from  the  third  and  fifth  visceral  pouches.  The  third 
also  gives  rise  to  a  parathyroid  body  ;  this  is  not  the  case,  at  least  as 
a  rule,  with  the  fifth.  The  ultimo-branchial  body  arises  as  a  secondary 
diverticulum  from  an  evagination  from  the  pharynx,  which  also  gives 
origin  to  the  fourth  and  lifth  visceral  pouches.  The  ultimo-branchial 
body  is  relatively  very  large,  especially  in  Ghelydra  ;  it  is  at  first  nearly 
equal  on  the  two  sides,  but  that  on  the  right  soon  lags,  and,  as  a  rule, 
attains  only  relatively  small  size.  J.  A.  T. 

Influence  on  Frog's  Inter-renal  Tissue  of  Extirpation  of  the 
Thyroid  and  Pituitary  Primordia. — Alice  L.  Brown  {Proc.  Amer. 
Soc.  Zool.  in  Anat.  Record,  1920,  17,  326).  In  larvje  of  Rana  pipiens 
twenty-seven  months  old,  from  which  the  thyroid  primordia  had  been 
removed,  the  inter-renal  tissue  remained  as  irregular,  but  definite  tissue 
masses  about  the  renal  vein.  In  larvae,  from  which  the  pituitary  pri- 
mordium  had  been  removed,  the  inter-renal  tissue  was  smaller  and  less 


ZOOLOGY  AND   BOTANY,    MICROSCOPY,   ETC.  183 

definite.  In  all  these  cases  the  inter-renal  tissue  remains  in  its  larval 
position  in  relation  to  the  mesonephros — namely,  in  the  form  of  irregular 
masses  about  the  renal  blood-vessel.  J.  A.  T. 

Thyroid  and  Parathyroid  in  Toad  Tadpoles  deprived  of  Pituitary 
Body. — Bennet  M.  Allen  {Proc.  Ayner.  Soc.  Zool.  in  Anat.  Record, 
1920,  17,  324-5).  Tadpoles  without  pituitary  body,  killed  six  months 
after  the  operation,  more  than  four  months  after  the  metamorphosis 
of  the  controls,  showed  thyroid  one-third  of  the  actual  size  of  normal 
tadpoles  of  Bufo  at  metamorphosis,  but  they  showed  the  normal  propor- 
tion to  the  size  of  the  body.  The  parathyroid  glands,  on  the  other 
hand,  showed  unusual  size,  both  relatively  and  absolutely.       J.  A.  T. 

Influence  of  Thyroid  Extirpation  on  Toad  Larvae. — Bennet  M. 
Allen  {Proc.  Amer.  Soc.  Zool.  in  Anat.  Record,  1920,  17,  325).  The 
removal  of  the  thyroid  tends  generally  to  check  the  differentiation  of 
somatic  structures,  such  as  stomach,  kidney  and  bladder.  But  the 
gonads  are  larger  and  farther  advanced  in  the  giant  thyroidless  tad- 
poles than  in  the  much  younger  metamorphosed  controls.        J.  A.  T. 

Development  of  Columella  auris  in  Reptiles. — Edward  L.  Rice 
[Proc.  Amer.  Soc.  Zool.  in  Anat.  Record,  1920,  17,  352-3).  The 
reptilian  columella  auris  has  been  regarded  {a)  as  of  otic  origin,  (Jb) 
as  of  hyoid  origin,  and  (c)  as  derived  from  both.  In  embryos  of 
Eumeces  there  is  evidence  of  a  genetic  relation  of  the  proximal  portion 
of  the  columella  to  the  otic  capsule  and  of  the  distal  portion  to  the 
hyoid  arch.  Yet  it  seems  as  if  the  entire  columella  was  a  unit  structure. 
The  seeming  contradiction  may  be  explained  on  the  assumption  that 
columella,  otic  capsule,  and  hyoid  arch  are  all  three  developed  from  a 
continuous  embryonic  stroma  and  later  differentiated  into  separate 
skeletal  elements.  J.  A.  T. 

Development  of  Denticles  in  Sword-fish. — J.  Thornton  Carter 
{Proc.  Zool.  Soc,  1919,  321-6,  3  pis.).  The  developing  denticles  in  a 
young  Xiphias  gladius  consist  of  a  cap  of  dentine  and  a  pediment,  con- 
nected by  a  transparent  area.  Later  on  there  is  a  formation  of  trabeculae 
joining  adjacent  pediments.  The  pediments  are  seen  to  stand  up  above 
the  level  of  the  surrounding  bone,  but  this  bone  continues  to  thicken 
and  grow  until  its  surface  lies  almost  at  the  level  of  the  transparent  area. 
The  same  is  true  in  Blenny,  Bream  and  Histiophorus.  Tooth  or 
denticle,  pediment,  and  connecting  area  are  formed  in  all  cases  on  the 
surface  of  the  same  papilla.  The  bone  to  which  the  teeth  or  denticles 
are  attached  is  not  independently  developed,  but  is  "  an  extension  of  the 
denticle  cone,"  so  that  the  sharp  line  of  demarcation  drawn  by  Goodrich 
between  the  tooth-bearing  bones  in  Teleostei  and  the  bases  of  placoid 
scales  does  not  exist.  J.  A.  T. 

Hermaphrodite  Green  Lizard. — Noel  Taylor  {Proc.  Zool.  Soc, 
1918,  223-30,  3  figs.).  A  specimen  of  Lacerta  viridis  showed  testes 
normal  in  shape  and  structure,  but  bearing  stalked  outgrowths  contain- 


184     SUMMA.RY  OF  CURRENT  RESEARCHES  RELATING  TO 

ing  ova.  Besides  epididjmes  and  vasa  deferentia  there  were  typical 
oviducts  developed  for  about  a  third  of  their  lengths.  Xo  vasa  efferentia 
were  to  be  seen  passing  from  testes  to  epididymis.  There  was  on  the 
dorsal  portion  of  one  of  the  kidneys  an  embedded  mass  of  almost 
fully  grown  ova  surrounded  by  folUcular  cells.  The  animal  must  have 
been  physiologically  sterile.  J.  A  .T. 

Sex  Determination  in  Mammals.— S.  Monckton  Copeman  {Proc. 
Zool.  Soc,  1919,  433-5).  Rabbits  and  some  other  mammals  (pigs,  cats, 
guinea-pigs,  mice)  were  used  for  experimentation.  Semi-castration  or 
semi-spaying  (affecting  the  gonads  of  one  side)  and  ligature  of  vas 
deferens  or  uterine  cornu  (on  one  side)  was  effected  ;  but  there  was  no 
demonstrable  effect  on  the  sex  of  the  offspring.  The  number  of 
experiments  made  is  not  noted,  but  it  is  stated  that  the  few  cases  (four) 
of  unisexual  families  (i.e.  all  male  or  all  female)  which  were  obtained 
were  shown  by  further  experiment  to  be  fortuitous.  J.  A.  T. 


6.  Histology. 

Changes  in  Nucleolar  Substance  during  Mitosis. — J.  Benoit  (C. 
R.  Soc.  Biol.,  1919,  82,  1431-3).  A  study  of  spermatocytic  mitoses  in 
mice.  After  the  prophase  the  nucleoli  seem  to  give  rise  to  nucleoluli, 
which  spread  themselves  in  the  nuclear  area.  These  nucleoluli  condense 
and  apply  themselves  to  the  spireme  thread.  Each  doubles  into  two 
daughter-granules,  which  dispose  themselves  at  the  ends  of  the  chromo- 
somes when  these  are  constituted,  and  migrate  with  them  to  the 
daughter-nuclei.  There  they  form  by  coalescence  a  daughter-nucleolus, 
whose  substance  is  directly  due  to  the  parent-nucleolus.  There  is  a 
nucleolar  division  as  meticulous  as  the  division  of  the  chromatin. 

J.  A.  T. 

Varieties  of  Cartilage. — Ed.  Retterer  (C.  R.  Soc.  Biol.,  1920,  83, 
21-4).  Hyaline  cartilage  is  preceded  by  a  stage  in  which  the  clear 
cells  are  not  separated  by  any  matrix.  This  epithelioid  cartilage  passes 
into  hyaline  cartilage  by  a  thickening  of  the  partitions  betAveen  the 
cells.  This  may  pass  into  bone.  The  sub-cuboid  nodule  of  the  tendon 
of  the  long  lateral  peroneal  muscle  is  connective  or  fibrous  in  children 
and  sedentary  people  ;  it  is  vesiculo-fibrous  in  most  adults ;  it  is  trans- 
formed into  a  cartilaginous  or  bony  sesamoid  in  those  who  perform 
repeated  energetic  movements  with  their  legs.  In  arboreal  monkeys  this 
sesamoid  passes  through  a  stage  of  hyaline  cartilage  and  ends  as  bone. 
Hereditary  predispositions  count  for  something,  but  the  stage  which  the 
supporting  tissue  reaches  is  in  direct  relation  to  the  frequency  or  the  in- 
tensity of  mechanical  excitations.  J.  A.  T. 

Development  of  Mastocytes  in  White  Rat. — E.  Laguesse  {C.  R. 
Soc.  Biol.,  1919,  82,  1415-7).  Mastocytes  (Mastzellen)  are  very  abun- 
dant in  the  newly-born  rat,  and  it  seems  clear  that  this  crop  is  due  to 
the  transformation  of  fixed  connective  tissue  cells.  They  may  arise 
from  any  mesenchymatous  cell.      In   certain   tissues  which  retain   in 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,  ETC.  185 

part  the  properties  of  the  primitive  mesenchyme  (osseous  medulla) 
there  arises  a  specially  mobile  variety,  the  myelocyte,  and  afterwards 
the  basophilous  leucocyte.  The  latter,  after  diapedesis,  may  become  a 
fixed  basophilous  cell,  probably  a  clasmatocyte.  J.  A.  T. 

Structure  of  the  Duodenum  in  Mammals. — F.  Yillemin  {G.  R. 
6'oc.  Biol,  1919,  82,  1426-8).  The  duodenum  in  man  and  in  those 
mammals  with  the  openings  of  the  bile  duct  and  pancreatic  duct  at  the 
same  level  (monkey,  some  rodents,  carnivores,  some  herbivores)  may  be 
divided  into  two  portions,  an  upper,  down  to  the  apertures,  and  a 
lower,  beyond  the  apertures.  The  upper  portion  is  dilated,  with  a 
thick  wall,  with  arteries  from  the  hepatic  only,  and  with  Brunner's 
glands.  The  lower  portion  is  like  a  jejunal  loop  ;  it  receives  branches 
from  the  superior  mesenteric  ;  it  has  no  Brunner's  glands.  In  the 
mammals  mentioned  above  Brunner's  glands  are  of  the  mucous  type. 

J.  A.  T. 

Types  of  Duodenum  in  Mammals. — F.  Yillemix  (6'.  R.  Soc.  Biol., 
1920,  83,  65-7).  In  the  ox  the  bile  duct  opens  far  from  the  pylorus  ; 
the  pancreatic  duct  below  the  bile  duct  at  a  relatively  short  distance 
from  it.  In  the  pig  the  bile  duct  opens  near  the  pylorus  ;  the  pan- 
creatic duct  as  before.  In  the  rabbit  the  bile  duct  opens  very  near  the 
pylorus,  and  the  pancreatic  duct  far  from  the  pylorus  at  the  end  of  the 
duodenum.  There  are  these  three  types.  Brunner's  glands,  whether 
mucous  or  mixed,  extend  to  the  opening  of  the  pancreatic  duct,  but 
never  further,  whatever  be  the  distance  of  the  aperture  from  the  pylorus. 

J.  A.  T. 

Structure  of  Sphincter  Muscles  in  Man. — A.  Lacoste  (C.  R.  Soc, 
Biol.,  1920,  83,  41-8).  In  sphincters  with  striped  muscle-fibres,  such 
as  those  in  the  ureter  and  around  the  anus,  each  fibre  has  a  thick 
connective  sheath,  formed  of  connective  and  elastic  fibres.  The  muscle- 
fibres  are  surrounded  by  a  plexus  of  elastic  fibres,  mostly  perpendicular 
to,  or  obliquely  disposed  to,  the  lie  of  the  muscle-fibres.  It  is  probable 
that  the  intervention  of  the  connective  tissue  between  the  fibres  gives 
the  latter  a  "  point  d'appui "  in  the  absence  of  fixed  bony  points. 

J.  A.  T. 

Plexiform  Sphincters  of  Smooth  Muscle  in  Alveolar  Canals  and 
Pulmonary  Acini  of  Mammals.— Gr.  Dubreuil  and  P.  LA]iiARQUE  {C. 
R.  Soc.  Biol.,  1919,  82,  1375-7).  The  muscles  of  the  terminal 
bronchioles  are  continued  on  the  alveolar  canals  by  smooth  muscle-fibres 
which  form  a  plexus.  This  plexus  surrounds  by  its  meshes  the  lumen 
of  the  alveolar  canals,  forming  a  sphincter  for  each.  J.  A.  T. 

Regenerative  Growth  of  Striped  Muscle-fibres  after  Traumatic 
Lesion.— J.  Nageotte  and  L.  Guyon  {C.  R.  Soc.  Biol,  1919,  82, 
1364-7).  It  was  observed  that  a  piece  of  glycerinated  nerve  introduced 
between  the  two  ends  of  a  cut  muscle  was  invaded  by  newly  formed 
striped  muscle-fibres.  J.  A.  T. 


186  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 

Endocrine  Gland  in  Uterus  of  Pregnant  Rat —  P.  Weill  {C.  R. 
Soc.  Biol,  1919,  82,  1433-5).  A  description  of  large  glandular  cells 
clustered  round  the  capillaries  of  the  uterine  myometrium.  Cytologically 
they  seem  referable  to  the  connective-tissue  type  of  cell,  but  they  are 
distinctly  secretory,  elaborating  eosinophilous  granulations.  They  form 
a  perivascular  endocrine  gland.  J.  A.  T. 

Cortical  Layer  of  Simple  Teeth.— Ed.  PtETTERER  ((7.  R.  Soc.  Biol, 

1919,  32, 1222-5).  The  cortical  layer  or  cement  is  ossified  in  the  same 
way  as  the  periosteum  or  tendons.  Connective-tissue  cells  become  first 
vesicular  and  then  bony  ;  they  are  transformed  into  cementoblasts  or 
corticoblasts.  This  transformation  takes  place  under  conditions  of 
pressure.  The  corticoblasts  are  oval  or  rounded  cells,  with  clear 
cytoplasm ;  they  are  encapsuled,  and  the  capsule  is  surrounded  by 
granular  non-calcified  cytoplasm.  J.  A.  T. 

Dust  Cells  in  Pulmonary  Alveoli. — A.  Guieysse-Pellisier  (C.  R. 
Soc.  Biol,  1919,  82,  1215-7).  A  study  of  stages  of  transformation 
convinces  the  author  that  the  dust  cells  found  free  in  the  pulmonary 
alveoH  are  greatly  modified  epithelial  cells,  adapted  to  a  phagocytic 
function.  J.  A.  T. 

Fat  in  Pulmonary  Epithelium.— F.  Granel  (G.  R.  Soc.  Biol,  1919, 
82,  1367-9).  A  study  of  the  epithelium  of  the  alveoli  and  of  the 
terminal  bronchial  ramifications.  There  is  in  the  small  nucleated  cells 
a  transformation  of  mitochondrial  granules  into  fat.  In  fact  these  cells 
may  be  fairly  called  glandular,  producing  granules  of  a  fatty  nature 
which  may  possibly  play  a  part  in  fixing  certain  substances.  This  may 
be  of  interest  in  connection  with  Bohr's  theory  that  the  gaseous 
exchanges  in  the  lung  are  more  aUied  to  secretory  activity  than  to 
osmotic  diffusion.  J.  A.  T. 

Supporting  Tissue  of  Human  Liver.— Pt.  Collin  {C.  R.  Soc.  Biol, 

1920,  83,  78-80).  The  supporting  tissue  of  the  liver  is  much  reduced 
in  man  ;  it  consists  essentially  of  the  interlobular  connective  tissue,  of 
the  adventitia  which  surrounds  the  central  vein  of  the  lobules,  and  of  the 
trellised  fibres  forming  an  intralobular  system,  connecting  the  interlobular 
connective  tissue  and  the  adventitia.  It  seems  subordinated  to  the  dis- 
position of  the  blood-vessels.  J.  A.  T. 

c.  General. 

Cross  Immunization.— li.  Camus  and  E.  Gley  (0.  R.  Soc.  Biol, 
1919,  82,  1240-1).  Rabbits  immunized  against  the  serum  of  Muraena 
resisted  that  of  AnguiUa,  and  vice  versa,  there  being  reciprocal  innnuniza- 
tion.  The  authors  have  already  shown  that  rabbits  immunized  against 
the  serum  of  AnguiUa  are  also  immune  to  that  of  the  conger-eel.  But 
rabbits  immunized  against  eel  serum  are  not  immune  to  that  of  the 
Torpedo,  nor  vice  versa.  J.  A.  T. 

Physiological  Inertia  and  Physiological  Momentum. — D.  Eraser 
Harris  {Scientific  MonthJij,  1919,  539—49).     Functional  or  physiological 


ZOOLOGY    AND    BOTANY,    MICROSCOPY^    ETC.  187 

inertia  is  that  property  of  living  matter  in  virtue  of  which,  having 
received  a  stimuhis,  it  continues  to  maintain  the  functional  status  quo  an/e, 
whether  that  was  activity  or  inactivity  ;  and  functional  momentum  is 
that  property  of  bioplasm  in  virtue  of  which  the  living  matter,  having 
responded  to  a  stimulus,  continues  to  exhibit  its  activity  or  inactivity 
after  the  stimulus  has  ceased  to  exist.  Functional  or  physiological 
inertia  is  that  property  of  living  matter  which  maintains  the  status  quo 
ante,  namely,  non-response  to  a  stimulus  tending  to  arouse  a  response 
(functional  inertia  of  rest),  or  response  after  the  stimulus  has  ceased 
(functional  momentum).  Affectabihty  is  that  property  of  living  matter 
in  virtue  of  which  it  responds  to  a  stimulus  either  by  activity  or  by  the 
quelling  of  activity  (inhibition).  Protoplasmic  inertia  is  the  physiological 
counterpart  of  affectability.  J.  A.  T. 

Immunity  and  Anaphylaxis. — Maurice  Arthus  ((7.  R.  Soc.  Biol., 
1919,  82,  1230-2).  Xolf  has  suggested,  on  the  ground  of  some 
interesting  experiments,  that  immunity  and  anaphylaxis  are  two  mani- 
festations of  the  same  organic  state.  Arthus  reports  other  experiments, 
chiefly  with  rabbits  in  relation  to  snake-poison,  which  go  to  show  that 
the  two  states  are  quite  distinct  and  may  exist  simultaneously  in  the 
same  animal.  J.  A.  T. 

Hereditary  Brachyphalangy. — Otto  L.  Mohe  and  Chr.  Wriedt 
{Puhlic.  Carnegie  Inst.  Washington,  1919,  295,  1-64,  7  pis.).  A  sym- 
metrical shortening  of  the  second  phalanx  of  the  second  fingers  and 
toes  inherited  within  a  Norwegian  family,  some  members  of  which 
emigrated  to  North  America.  The  peculiarity  is  restricted  to  one 
phalanx  ;  the  other  parts  are  normal ;  the  individuals  show  no  shortness 
of  stature.  The  anomaly  manifests  itself  as  "  slightly  "  shortened  and 
as  "  much  "  shortened,  but  there  is  no  intermediate  condition.  There 
is  no  premature  ossification  of  the  epiphysial  cartilage.  The  inheritance 
is  followed  without  any  break  through  six  generations,  including  and 
descended  from  an  individual  born  in  1764.  The  brachyphalangy  is 
inherited  as  a  dominant,  not  sex-linked  character.  All  the  brachy- 
phalangous  individuals  are  heterozygous  for  the  gene  in  question,  with 
one  possible  exception.  The  material  included  a  case  of  identical  twins, 
both  brachyphalangous  of  an  identical  type.  The  two  types,  "  slightly  " 
and  "  much  "  shortened,  are  explained  through  the  presence  in  some  of 
the  normal  individuals,  married  into  the  family,  of  a  dominant  specific 
modifying  gene  which  enhances  the  effect  of  the  principal  gene  for 
brachyphalangy,  and  changes  the  "  slightly  "  into  the  "  much  "  shortened 
type.  J.  A.  T. 

Homologies  of  Squamosal  of  Fishes. — Edward  Phelps  Allis,  Jr. 
{Anat  Record,  1919,  17,  73-87).  The  squamosal  of  fishes,  frequently 
called  the  pterotic,  is  primarily  a  dermal  bone  which  develops  along  the 
dorsal  surface  of  the  ridge  of  the  lateral  semicircular  canal.  Anteriorly 
it  articulates  with  frontal  or  parietal  or  both.  The  summit  of  the  post- 
orbital  process  ossifies  as  the  sphenotic  or  dermosphenotic.  Both  acquire 
primary  relations  with  the  chondrocranium,  and  may  be  composed  of 


188  SUMMARY   OF  CURRENT   RESEARCHES   RELATING  TO 

external  and  internal  plates  enclosing  the  fish's  temporal  fossa,  corre- 
sponding to  part  of  the  temporal  fossa  in  mammals.  The  cerebral  portion 
of  the  squamosal  in  man  and  the  zygomatic  process  are  derived  from  the 
sphenotic  of  fishes  or  that  bone  fused  to  the  pterotic.  The  auricular 
portion  of  the  squamosal  corresponds  to  the  cheek-plate  of  fishes.  The 
tympanic  of  mammals  and  the  quadrato-jugal  of  amphibians  and  reptiles 
correspond  to  the  pre-operculum  of  fishes.  The  jugal  corresponds  to  a 
fusion  of  some  sub-orbital  bones  in  fishes,  and  the  post-orbitals  of  fishes 
fuse  with  the  maxilla  to  form  the  maxilla  of  mammals.  There  are 
apparently  four  distinctly  different  temporal  arches  in  Vertebrates  :  one 
formed  by  the  dermosphenotic  and  post-orbital  (man,  npper  arch  in 
Hatteria  and  Crocodile) ;  one  formed  by  the  cheek-plate  of  fishes  and 
the  post-orbital  or  jugal  (Lacerta,  Scleroporus,  part  of  lower  arch  of 
Hatteria) ;  one  formed  by  the  quadrato-jugal  and  jugal  (lower  arch  of 
Crocodile,  part  of  lower  arch  of  Hatteria);  and  one  formed  by  the 
quadrato-jugal  and  maxilla  (Amphibians).  J.  A.  T. 

Reputed  Endocrine  Function  of  Thymus  Gland.— Matsuziro 
Takenouchi  {Journ.  Exper.  Zool,  1919,  29,  311-42,  2  charts).  Experi- 
ments with  thymus  substance  of  the  albino  rat,  mainly  by  means  of  serum 
obtained  from  rabbits  immunized  with  the  thymus  substance,  yield  very 
negative  results.  "  So  long  as  we  are  unable  to  maintain  a  more  solid 
foundation,  we  cannot  accept  the  specific  action  of  the  antithymus  serum, 
nor,  furthermore,  can  we  believe  [in]  any  endocrine  function  whatever 
of  the  thymus  gland,  no  matter  whether  the  cortical  or  medullary  portion 
play  the  principal  role  in  the  physiological  function  of  this  gland." 

J.  A.  T. 

Locomotion  in  a  Spiral. — A.  A.  Schaeffer  {Proc.  Amer.  Soc.  Zooh 
in  Anat.  Record,  1920,  17,  342).  So  far  as  the  author's  observation 
goes,  all  motile  plants  and  animals,  when  not  guided  by  orienting  senses, 
are  influenced,  when  freely  moving,  by  some  agency  so  that  the  resulting 
path  resembles  some  form  of  spiral.  The  great  diversity  of  form 
exhibited  by  organisms  that  move  in  spiral  paths  indicates  that  the 
automatic  mechanism  regulating  the  direction  of  the  path  is  not  depen- 
dent upon  or  connected  with  structure,  but  is  much  more  fundamental 
in  its  nature,  affecting  the  protoplasm  directly.  J.  A.  T. 

Cerebral  Function  in  Learning. — K.  S.  Lashley  {PsychohioJogy, 
1920,  2,  55-128,  4  pis.).  There  is  complete  vicarious  functioning  of  all 
parts  of  the  rat's  cerebrum  in  learning.  This  seems  to  hold  true  both 
for  the  cortex  and  for  the  underlying  structures  making  up  the  archi- 
pallium.  Learning  may  go  on  with  equal  speed  in  the  presence  or 
absence  of  particular  specialized  areas.  There  is  strong  evidence  against 
there  being  special  cerebral  areas  that  have  a  directive  influence  over 
learning,  whether  it  be  by  "  attention,"  mediated  through  the  frontal 
lobes,  or  by  the  "conscious  action  "  of  the  brain  as  a  whole.  On  the 
contrary,  Lashley's  results  suggest  that  the  only  essential  condition  for 
learning  is  the  simultaneous  activity  of  two  reaction  systems  which  are 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  189 

in  anatomical  connexion  by  association  fibres.  Within  certain  limits 
there  is  no  relation  between  the  amount  of  cerebral  material  functioning 
and  the  rate  of  formation  of  complex  habits.  In  normal  rats  the  habit 
of  brightness  discrimination  is  mediated  by  the  occipital  pole  of  the 
cerebrum  (area  striata),  and  by  no  other  part  of  the  cerebral  cortex. 

J.  A.  T. 

Ear  of  Guinea-pig.— Geoeges  Poetmanx  (G.  R.  Soc.  Biol.,  1919, 
82,  1384-6,  1  fig.).  This  differs  from  the  ordinary  mammalian  type. 
There  is  a  median  dumb-bell-shaped  portion  with  a  very  narrow  connect- 
ing tube  (the  endolymphatic  canal),  two  gradually  expanding  ends,  one 
of  them  intracranial  (the  endolymphatic  sac,  in  close  relations  with  the 
lateral  sinus),  the  other  vestibular  (the  sacculus).  From  the  sacculus  a 
very  straight  and  short  canalicule  establishes  communication  with  the 
utriculus,  and  a  larger  one  leads  to  the  cochlear  canal.  In  passing  from 
the  sac  to  the  saccule  there  is  a  gradual  flattening  of  the  epithelium 
and  a  progressive  development  of  perilymphatic  spaces.  The  endo- 
lymphatic sac  is  in  intimate  relations  with  the  intracranial  venous 
system.  J.  A.  T. 

Endolymphatic  Sac  and  Duct  in  Do^. — Geoeges  Poet^iann  (C.  R. 
Soc.  Biol,  1920,  83,  45-8,  1  fig.).  The  author's  description  of  the 
inner  ear  of  the  dog  does  not  agree  with  what  is  believed  to  be  usual  in 
mammals.  The  membranous  internal  ear  shows  a  median  dumb-bell-like 
portion,  with  unequal  expansions.  The  narrow  median  isthmus  is  the 
endolymphatic  canal.  One  gradually  expanded  end,  the  larger  one,  lies 
intracranially,  the  endolymphatic  sac,  which  is  in  intimate  relations  with 
the  lateral  sinus.  The  other  end,  the  smaller,  is  vestibular,  and  is  the 
sacculus.  From  the  sacculus,  and  from  about  the  same  level,  two 
canaliculi  arise,  the  upper  one  communicating  with  the  utriculus,  the 
lower  one  with  the  cochlear  canal.  Emphasis  is  laid  on  the  following 
facts  : — The  endolymphatic  sac  is  relatively  very  large  ;  its  connexion 
with  the  lateral  sinus  is  intimate  and  extensive  ;  the  epithelium  is  gradu- 
ally flattened,  and  the  perilymphatic  spaces  are  increasingly  developed  in 
passing  from  the  sac  towards  the  sacculus.  J.  A.  T. 

Distribution  of  Parasitized  Fish. — H.  Chas.  Willia^ison  {Ann. 
Applied  Biol.,  1919,  6,  48-52).  What  are  called  "spotted  haddocks" 
show  in  the  muscles  numerous  cysts  of  a  Protozoon  parasite,  Dokus  cuius. 
They  have  an  unpleasant  smell  (suggestive  of  creosote),  and  are  said  to 
have  a  sour  taste.  They  seem  to  have  a  restricted  geographical  distri- 
bution, about  Shetland  and  west  of  Orkney,  but  the  evidence  is  not  very 
convincing ;  they  are  absent  from  Faroe.  vSimilarly,  "  worm-infested 
codlings,"  with  numerous  very-resistant  Nematodes  (like  young  stages  of 
Ascaris  decipiens),  coiled  up  in  the  muscles  (able  to  survive  brine-pickle 
for  half-an-hour  and  smoking  for  three-quarters  of  an  hour  or  more), 
do  not  occur  at  Shetland  but  at  Faroe.  It  may  be  that  local  environ- 
mental factors  account  for  the  diverse  distribution  of  certain  kinds  of 
parasitized  fish.  J.  A.  T. 


190  SUMMARY   OF   CURREI^T   RESEARCHES   RELATING  TO 

INVERTEBRATA. 

MoUusca. 

7.  Gastropoda. 

Radula  of  Mitridse.— A.  H.  Cooke  {Proc.  Zool  Soc,  1919,  405-22, 
18  figs.).  The  rbachidian  tooth  exhibits  wide  differences  in  structure, 
ranging  from  the  lozenge-shaped  8-  to  9-cusped  form  in  3Iitra  to 
the  unicuspid  triangular  form  of  the  variegata  group.  These  divergences 
in  the  structure  of  the  rhachidian  are  accompanied  bj  a  general  similarity 
of  plan  in  the  laterals,  subject  however  to  a  progressive  modification  in 
their  form.  The  laterals,  in  fact,  exhibit  every  symptom  of  regress 
towards  a  gradual  degradation.  Perhaps  there  is  a  chie  here  to  the 
genesis  of  the  familiar  bicuspid  or  unicuspid  lateral  of  many  of  the 
Rhachiglossa.  It  seems  within  the  bounds  of  possibility  that  the  coales- 
cing, or  gradual  disappearance,  of  the  cusps,  in  a  multicuspid  lateral, 
produced  in  more  cases  than  that  of  the  Mitridge  a  lateral  with  one  or 
two  large  cusps  instead  of  many  small  ones.  J.  A.  T. 

Sensory  Reactions  of  Chromodoris  zebra. — W.  J.  Crozier  and 
Leslie  B.  Arey  {Journ.  Exper.  Zool.,  1919,  29,  261-310, 8  figs.).  Ex- 
periments on  mechanical,  photic,  thermal  and  chemical  excitation  of  this 
Nudibranch.  There  are  differentiated  receptors  mediating  reactions  to 
tactile,  chemical  and  shading  stimulation,  to  the  constant  intensity  of 
light,  and  perhaps  to  heat.  Locally,  the  responses  of  the  general  integu- 
ment and  all  the  outgrowths  depend  upon  locally  contained,  peripheral, 
non-synaptic  networks,  which  are  polarized  in  the  gill-plumes  and 
probably  in  other  projecting  parts.  Reactions  involving  parts  distant 
from  the  site  of  activation  depend  upon  central,  ganglionic  transmission. 
The  central  nervous  system  is  essentially  synaptic.  The  Nudibranch  is 
positively  phototropic,  the  chief  receptive  organs  probably  being  the 
eyes,  but  the  gill-plumes  are  also  sensitive,  expanding  in  light,  retracting 
when  shaded.  When  sexually  mature,  the  animal  is  negatively  geotropic. 
It  is  negatively  rheotropic  to  strong  Avater  currents,  the  directive  organs 
being  the  "  rhinophores."  Chemotropic  reactions  to  body  secretions  of 
other  individuals  lead  to  conjugation,  "olfactory"  and  "gustatory" 
stimulation  being  concerned.  The  locomotion  is  primarily  muscuhir,  not 
ciliary.  The  outer  lateral  margins  of  the  foot  are  active.  The  foot  is 
positively  stereotropic,  and  when  removed  from  a  surface  folds  together 
laterally.  This  suits  creeping  on  narrow  blades  of  eel-grass.  The  stereo- 
tropism  of  the  anterior  end  of  the  foot  is  responsible  for  righting 
behaviour.  There  is  no  apparent  statolithic  control  for  dorso- ventral 
body  orientation.  J.  A.  T. 

Sensory  Responses  of  Chiton.— Leslie  B.  Arey  and  W.  J. 
Crozier  {Journ.  Exper.  Zool.,  1919,  29, 157-260, 14  figs.).  An  account 
of  the  general  natural  history  of  Chiton  inhere nlatus,  its  movements  and 
reactions,  and  its  responses  to  mechanical,  thermal,  photic,  and  chemical 
excitation.     The   sensory   conditions  are   unexpectedly   complex ;    the 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  191 

major  pathways  of  nervous  transmission  are,  by  contrast,  unusually 
clear  and  well  defined,  {a)  Tactile  receptors  are  absent  from  the  shell 
surfaces.  The  "  scales  "  and  "  hairs "  upon  the  girdle  are  important 
tactile  organs.  The  ctenidia  are  also  sensitive  to  touch,  as  are  the 
proboscis,  the  foot,  and  the  ventral  surface  of  the  girdle.  The  foot  is 
positively  thigmotactic  to  large  surfaces,  but  retracts  locally  when 
stimulated  by  a  small  surface.  The  tegmental  aesthetes  are  photo- 
sensitive ;  they  are  activated  by  light  of  constant  intensity  and  by 
sudden  decrease  in  light  intensity,  not  by  increase.  The  dorsal  surface 
of  the  girdle,  the  soft  ventral  surfaces  and  the  periphery  of  the  girdle 
are  sensitive  to  light.  The  superficial  soft  tissues  are  open  to 
chemical  activation,  to  stimulation  by  abnormal  osmotic  pressures,  and 
by  "  irritants."  Tactile,  photic,  and  chemo-receptors  are  physiologically 
distinct.  There  is  no  clear  evidence  of  sensitivity  to  heat ;  that  to  cold 
is  less  doubtful.  There  is  a  pronounced  tendency  for  the  animal  to 
come  to  rest  in  positions  avoiding  uneven  tensions  in  the  musculature. 
This  is  responsible  for  the  precise  negative  geotropism  exhibited  by  Chiton. 
It  is  not  sensitive  to  vibratory  mechanical  disturbances,  (b)  The 
problem  of  differential  irritability  is  difficult.  One  factor  is  anatomical 
isolation  of  particular  receptors  (e.g.  removal  from  the  external  surface). 
Another  is  the  structure  of  the  receptor.  An  additional  factor  is 
probably  found  in  the  possession  by  certain  receptor  cells  of  special 
substances  which  enter  into  excitation  reactions.  On  the  sole  of  the 
foot  of  Chiton  there  is  evidence  of  separate  photo-,  tacto-,  and  chemo- 
reception.  Even  if  the  epithelial  cells  of  an  animal  were  open  to  sensory 
activation  by  a  variety  of  stimuli,  it  would  not  be  legitimate  to  argue  to 
a  primitive  "  universal "  kind  of  receptor,  (c)  The  reactions  of  Chiton 
to  local  stimulation  are  of  a  character  consistent  with  the  known 
distribution  of  the  central  nervous  system.  The  responses  of  isolated 
portions  of  an  animal  cut  transversely  are  such  as  to  show  the  absence 
of  any  strong  centralization.  This  is  in  agreement  with  the  known 
occurrence  of  ganglion  cells  throughout  the  whole  length  of  the  nerve 
strands,  (d)  The  young  Chiton  is  photo-negative,  the  old  Chiton 
photo-positive,  to  sunlight.  There  is  a  progressive  age  change,  which  is 
connected  with  the  erosive  destruction  of  the  photo-sensitive  aesthetes. 
The  erosion  of  the  shell  is  due  to  growth  effects  and  to  organisms 
settling  down  on  it.  (e)  The  homochromic  coloration  of  Chiton  is 
determined  by  the  algal  food  and  by  organisms  on  the  shell.  A  homo- 
chromically  coloured  Isopod  is  a  characteristic  companion.  Various 
harmonious  correlations  follow  automatically  in  the  wake  of  the  changing 
phototropism  of  Chiton.  The  animal's  habits  determine  the  environment 
in  which  it  lives.  J.  A.  T. 

Homing  of  Limpet. — Henri  Pieron  {C.  R.  Soc.  Biol,  1919,  82, 
1227-30).  The  limpet  shows  a  topographical  memory  for  its  site.  It 
feels  the  surface  of  the  rock  with  its  cephalic  tentacles,  and  to  some 
extent  by  its  pallial  tentacles.  But  there  is  also  a  kingesthetic  memory. 
There  are  two  other  factors  which  operate  in  the  homing — namely, 
gravity  and  illumination— but  these  are  secondary  compared  with  the 
topographical  data  afforded  by  touch  on  rough  surfaces.  J.  A.  T. 


192  SUMMARY   OF   CURRENT   RESEARCHES  RELATING  TO 

Arthropoda. 
a.  Insecta. 

Study  of  Ammophila  heydeni. — E.  Rabaud  {Bidl.  Soc.  Zooh 
France,  19]  9, 44,  52-63).  Description  of  the  behaviour  of  this  digger- 
wasp.  In  beginning  to  burrow  the  insect  holds  firmly  with  the  second 
and  third  pairs  of  legs,  uses  her  head  and  fore-legs,  and  vibrates  her 
wings  rapidly.  The  earth  is  carried  out  in  the  mandibles,  sometimes  by 
flight,  sometimes  afoot.  There  is  considerable  elasticity.  After  deposit- 
ins:  a  paralysed  caterpillar,  the  wasp  lays  an  Qgg  on  the  side  of  the  victim  ; 
and  then  another  caterpillar  may  be  brought  in  and  no  o^gg  laid. 
Sometimes  five  or  six  caterpillars  were  collected.  There  is  more 
plasticity  than  some  observers  have  admitted.  The  position  of  the 
burrow  is  found  after  a  flight  by  motor-memory  ;  but  when  the  mouth 
of  the  furrow  was  concealed  the  wasp  w^as  sometimes  baffled.  Though 
she  returned  to  the  situation  (by  motor-memory),  she  could  not  always 
find  the  disguised  doorway.  This  points  to  a  sensory  memory.  With 
few  exceptions  the  wasp  kept  to  the  same  species  of  caterpillar.  This 
involved  extra  hunting,  and  its  utility  is  not  obvious,  for  Fabre  showed 
that  the  wasp-grubs  can  thrive  on  various  sorts  of  food.  The  use  of 
the  paralysing  is  not  very  clear,  for  the  wasp-gmbs  can  thrive  on  dead 
caterpillars,  and  they  do  often  die.  The  results  of  putrefaction  seem  to 
be  trivial.  J.  A.  T. 

Reactions  of  Bees  to  Light. — Dwight  E.  Minnich  (Journ.  Exper. 
Zool,  1919,  29,  313-425,  17  figs.).  Light  exerts  a  kinetic  influence  in 
honey-bees  ;  it  tends  to  induce  activity.  In  its  absence  activity  is 
greatly  reduced  or  is  entirely  lacking.  Isolated  worker-bees,  in  an 
active  condition,  exhibit  strong  positive  phototropism  when  flying  or 
creeping.  Temporary  suppressions  of  this  response  may  occur,  however. 
Normal  bees  creeping  in  non-directive  light  often  move  asymmetrically, 
probably  for  internal  reasons,  for  the  same  occurs  in  darkness.  Bees 
with  one  eye  blackened  usually  loop  towards  the  functional  eye  as  they 
creep  toward  a  source  of  light.  In  non-directive  light  they  generally 
circle  toward  the  functional  eye ;  this  is  more  marked  in  more  intense 
illumination.  The  cause  is  the  continuous  unilateral  stimulation. 
Variability  of  response  may  be  accounted  for  in  many  Avays.  Photic 
orientation  in  the  normal  honey-bee  is  eff^ected  through  the  continuous 
action  of  light  on  both  photo-receptors.  Orientation  to  light  in 
Arthropods  generally  is  effected  through  the  continuous  action  of  the 
stimulus  rather  than  through  intermittent  changes  of  its  intensity. 

J.  A.  T. 

American  Insect  Galls. — E.  P.  Felt  (Bull  N.  Y.  State  Museum, 
191S,  200,  l-olO,  IG  pis.,  250  figs.).  A  very  useful  finely  illustrated 
key  to  American  Insect  Galls  and  Mite  Galls,  arranged  under  the  plants 
on  which  they  occur.  No  fewer  than  1,441  insects  are  included,  682 
being  gall  midges  and  445  gall  wasps.  Besides  these  there  are  other 
Diptera  and  Hymenoptera,  besides  various  Coleoptera  and  Hemiptera. 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  193 

There  are  161  species  of  mites  (Eriophyidas)  on  the  list.  The  irritant 
causes  recognized  are  fluids  in  the  egg  or  injected  with  it,  secretion  from 
the  larva,  mechanical  stimulation  by  the  gall-maker  itself.       J.  A.  T. 

Plant  Galls  of  Philippines. — Leopoldo  B.  Uichanco  {Philippine 
Joiirn.  Sci.,  1910,  14,  527-5-4,  15  pis.).  An  account  of  57  zoocecidia 
due  to  Rhynchota  (Psyllidae,  Aphididae  and  Coccidas),  Diptera 
(Itonididae  or  Cecidomyidfe  and  Trypetid^),  Hymenoptera  (Cynipidae 
and  Tenthredinid^),  Lepidoptera  (Gelechidaa),  Coleoptera  (Buprestidie),. 
Thysanoptera,  and  Eriophyid  mites.  It  is  noted  that  the  gall  of  animal 
origin  may  be  occasionally  a  response  to  severe  mechanical  injury  or  to 
continuous  mechanical  irritation,  but  is  mainly  due  to  a  secretion  either 
at  the  time  of  oviposition  or  during  the  development  of  the  insect. 
Moliard  (1917)  removed  some  of  the  secretion  of  the  larva  of  Aulax 
papaveris,  a  Cynipid  gall-maker  on  the  pistil  of  Papaver  rlmas,  and 
injected  it  into  the  growing  pistil  of  the  poppy,  where  galls  were  evoked 
like  those  produced  by  the  larva  itself.  Euphorbiaceae  and  Moracea& 
seem  to  furnish  in  the  Philippines  more  galls  than  any  other  orders  do. 
Galls  can  be  produced  only  when  the  tissue  of  the  plant  is  still  developing. 
After  the  plant  tissue  has  been  fully  matured  no  amount  of  stimulus  will 
evoke  a  gall.  J.  A.  T. 

Emergence  of  Larvae  of  Apanteles  glomeratus  from  Caterpillars 
of  Pieris  brassicaB.— Cl.  Gautier  {G.  R.  Soc.  Biol,  1919,  82, 1369-71). 
The  parasitized  caterpillars  never  attach  themselves  as  the  normal  ones 
do  when  they  pass  into  the  chrysalid  stage.  The  larvae  bore  out  almost 
simultaneously,  emerging  mostly  on  the  sides  above  the  pro-legs.  But 
a  few  may  come  out  on  the  back,  and  very  rarely  on  the  ventral  surface. 
They  form  cocoons  in  one  mass  below  the  caterpillar,  or  in  two  groups. 
These  are  in  part  attached  to  the  caterpillar's  chrysalid  threads.  The 
caterpillar  may  be  found  dead  above  or  among  the  cocoons,  or  it  may 
actually  move  with  its  burden  to  some  distance,  where  it  dies.  Before 
it  dies,  however,  it  makes  a  new  and  thick  feltwork  of  filaments  around 
the  cocoons  of  the  parasites.  Caterpillars  from  which  the  larvse  have 
emerged  never  eat  and  never  form  an  actual  chrysalis.  Fabre  described 
the  issue  of  the  parasites  by  a  single  aperture,  but  Gautier  and  others 
describe  each  parasite  emerging  by  its  own  aperture.  J.  A.  T. 

Food  of  Caterpillars  of  Pieris  and  Euchlde. — Cl.  Gautier  and 
Ph.  Kiel  {C.  R.  Soc.  Biol,  1919,  82,  1371-4).  Fabre  laid  emphasis  on 
the  fact  that  the  caterpillars  of  Pieris  brassicse  require  Cruciferous  plants, 
but  as  a  matter  of  fact  they  may  also  eat  Tropaeolum.  Their  relatives 
may  likewise  feed  on  members  of  the  families  Trop^olacese,  Resedace^e, 
Myrtacea),  Araceae,  Papilionaceas,  Crassulaceae,  and  Capparidacete.  In 
short,  the  caterpillars  are  more  "  polyphagous  "  than  has  been  supposed. 
Guignard  has  shown  a  chemical  affinity  between  Cruciferag,  Tropseolace^e, 
Capparidaceae,  and  Resedace^,  for  most  of  them  show  the  presence 
of  myrosin  and  sulphurous  glucosides.  The  butterflies  are  probably 
directed  mainly  by  the  odour  to  plants  suitable  for  the  nutrition  of  the 
caterpillars.  J.  A.  T. 


194      SUxMMARY  OF  CURRENT  RESEARCHES  RELATING  TO 

Notes  on  Common  Flies.— G.  S.  Graha^i-Smith  {Parasitologij, 
1919,  11,  347-84,  2  pis.,  23  figs.,  2  charts).  The  curve  indicatmg  the 
number  of  flies  caught  in  a  trap  baited  with  excrement  corresponds  with 
the  curve  for  maximum  temperature  recorded  bj  a  thermometer  exposed 
in  the  sun.  Flies  spend  a  very  large  proportion  of  their  time  in  cleaning 
themselves  and  usually  follow  a  definite  routine.  Empusa  disease  occurs 
in  a  good  many  species.  Certain  Gamasid  mites  destroy  both  fly  eggs 
and  young  larvae.  Certain  species  of  beetles  destroy  large  numbers  of 
fly  puparia.  Numerous  parasites  were  obtained  from  naturally  infected 
fly  puparia,  especially  species  of  Chalcidida^  and  Braconid^.  The 
Chalcid  Melittohia  acasta  frequently  parasitizes  puparia  already  infected 
with  the  Braconid  Alysia  manducator.  The  males,  which  are  blind, 
unable  to  fly  and  relatively  few  in  number,  reach  maturity  before  the 
females  in  the  same  puparia,  and  the  stronger  specimens  destroy  the 
weaker.  The  males  never  leave  the  puparia  in  which  they  hatch,  but 
mate  with  the  females  before  the  latter  escape  from  the  puparia. 
Fertilized  females  lay  large  numbers  of  eggs  from  which  a  few  males 
and  numerous  females  develop.  Virgin  females  only  lay  a  few  eggs, 
from  which  males  develop.  If  fertilized  subsequently,  numerous  eggs 
are  deposited  which  develop  into  both  males  and  females.  These 
parasites  oviposit  in  puparia,  not  in  larvae.  The  Brachonid  Alysia 
manducator  attacks  large  larvae  ;  some  of  the  imagines  emerge  in  spring 
and  others  in  autumn,  one  from  each  puparium.  Virgin  females  lay 
numerous  eggs  which  develop  into  males.  J.  A.  T. 

Mosquitoes.—  F.  W.  Edwards  {Puhlications  British  Museum,  Kat. 
Hist.,  1916,  Economic  Series,  4,  1-19,  6  figs.).  An  admirably  clear  and 
terse  account  of  the  general  characters  and  life-history  of  mosquitoes, 
which  are  grouped  for  practical  purposes  as  domestic,  stream  and  pool, 
sylvan,  and  swamp  mosquitoes.  The  distinctive  features  of  the  Anopheles 
mosquitoes  are  discussed,  and  the  relations  of  mosquitoes  to  malaria, 
yellow  fever  and  elephantiasis  are  briefly  dealt  with.  Practical  measures 
are  also  discussed.  J.  A.  T. 

Anopheles  crucians. — C.  W.  Metz  (Beports  U.S.  Public  Health 
Service,  1918,  495,  215G-69).  This  species  occurs  along  with  A. 
punctipennis  and  A.  quadrimacidatus  in  the  gulf  coast  region  of  the 
United  States.  It  is  a  swamp  mosquito  ;  it  seemed  to  live  on  non- 
living vegetable  debris  ;  it  was  breeding  prolifically  at  the  beginning  of 
April  and  continued  breeding  until  late  summer  at  least ;  it  will  become 
distributed  over  an  area  within  approximately  7,000  feet  of  the  source. 

J.  A.  T. 

Sense-Organs  in  Antennae  and  Palps  of  Diptera.— K.  M.  Smith 
{Proc.  Zool.  Soc,  1919,  31-G9,  4  ])ls.,  43  figs.).  An  interesting  compara- 
tive study,  very  abundantly  and  clearly  illustrated,  of  "  sense-pits  "  and 
similar  structures.  Each  component  element  consists  of  a  large,  modified, 
hypodermal  cell,  above  which  is  a  very  thin-walled  chitinous  process, 
rising  from  the  thicker  chitin  of  the  general  surface,  and  of  a  nerve- 
iibre   which  runs   close  up   to   the  base   of,   if  not  actually  into,  the 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  195 

chitinous  process.  A  typical  sense-pit  shows  an  opening  in  the  chitin 
leading  down  into  the  pit  itself,  frequently  a  channel  with  spiral  folds  or 
various  ridges,  and  a  floor  produced  into  the  sensory  processes  which  rise 
like  the  fingers  from  a  glove.  Below  the  floor  is  a  rounded  mass  of 
large  radiating  cells,  each  shell  separating  from  its  fellow  as  it  approaches 
the  base  of  the  pit  and  running  to  its  corresponding  sensory  process. 
The  whole  mass  of  cells  is  embraced  by  a  branch  of  the  large  antennary 
nerve.  In  an  appendix  Prof.  H.  M.  Lefroy  suggests  that  the  function 
of  the  structures  is  purely  olfactory,  that  the  general  surface  of  the 
antennae  acts  for  delicate  perceptions,  that  the  pits  come  into  play  when 
the  concentration  of  the  absorbed  liquid  has  dulled  the  simple  organs  on 
the  outer  surface,  and  that  the  final  location  of  the  source  of  scent  is 
due  to  the  protected  pits.  Further,  it  is  suggested  that  the  presence  of 
two  kinds  of  pits  in  some  species  is  correlated  with  the  dual  perception 
in  the  female  of  food  and  of  breeding-place  ;  in  the  male,  of  food  and  of 
the  female.  J.  A.  T. 

Horned  Littoral  Fly.— L.  Mercieu  {G.  R.  Soc.  Biol,  1919,  82, 
1217-18).  A  specimen  of  FucelUa  ?naritima  Hal.  showed  a  minute 
horn  between  the  eyes,  and  Yilleneuve  suggested  that  this  was  due  to  a 
hardening  and  persistence  of  the  frontal  vesicle,  which  is  protrusible  and 
contractile  on  the  head  of  the  young  flies  ;  experiments  corroborate  this. 
The  larvae  pupate  in  the  sand  under  clumps  of  seaAveed,  and  some  which 
may  find  it  difficult  to  get  free  may 'show  a  horn.  J.  A.  T. 

Flies  in  Snails.— D.  Keilin  {Parasitologij,  1919, 11,430-55,4  pis., 
6  figs.).  The  fly  Melinda  cognata  Meigen  has  its  young  stages  in  the 
small  snail  Helicella  virgata.  The  oviposition  was  not  observed.  The 
larva  occurs  first  in  the  kidney,  which  it  destroys,  and  then  in  the  mantle 
cavity.  It  kills  the  snail  and  pupates  in  the  earth.  There  are  several 
hyperparasites  of  M.  cognata,  notably  two  Ichneumonids  {Atractodes  exilis 
and  Exolgtus  petiolarius)  which  oviposit  in  Melinda  larvae  while  still  in 
the  snail.  The  early  stages  of  Melinda  are  described.  Three  other  flies 
were  found  in  Helicella — viz.  (1)  another  species  of  Melinda,  probably 
M.  geniilis  ;  (2)  Sarcophaga  nigriventris  ;  and  (3)  another  species  of 
SarcoiJhaga,  probably  >S'.  crassimargo.  Finally,  the  author  sums  up  what 
is  known  as  to  parasitic,  carnivorous,  epizoic,  and  saprophagous  Diptera 
occurring  on  living  and  dead  molluscs.  J.  A.  T. 

Photic  Orientation  in  Drone-Fly. — S.  0.  Mast  {Proc.  Amer.  Soc. 
Zool.  in  A7iat.  Record,  1920,  17,  314).  It  has  been  maintained  that 
photic  orientation  depends  on  the  fact  that  unequal  illumination  of 
the  two  eyes  means  a  difference  in  the  tonus  of  the  muscles  of  the  legs 
on  the  two  sides  of  the  body.  The  body,  in  response  to  the  unequal 
tonus,  is  turned  until  the  two  eyes  are  equally  illumined.  But  if  the 
two  front  legs  on  one  side  are  removed,  orientation  is  nearly  as  precise 
as  it  is  in  normal  specimens,  showing  that  orientation  is  not  necessarily 
dependent  upon  the  relation  in  tonus  in  the  muscles  of  the  legs  on 
opposite  sides.  If  one  eye  is  covered,  orientation  may  still  occur.  If 
the  two  front  legs  on  one  side  are  removed  and  either  eye  is  covered, 

0  2 


196  SUMMARY   OF   CURRENT   RESEARCHES   RELATING    TO 

proper  unilateral  illumination  may  still  induce  turning  either  to  the 
right  or  the  left,  showing  that  the  movements  of  the  legs  may  be  con- 
trolled by  impulses  received  from  either  eye.  Moreover,  the  response 
depends  in  part  upon  the  location  of  the  stimulus  on  the  eye,  and  not 
solely  upon  the  magnitude  of  the  stimulus.  In  short,  the  process  of 
orientation  may  be  more  complicated  than  is  implied  in  the  theory  of 
unequal  illumination  and  resulting  difference  of  tonus.  J.  A.  T. 

Oviposition  of  Gastrophilus  nasalis. — A.  E.  Cameron  {Science, 
1919,  49,  2G).  It  is  denied  that  this  bot-fly  darts  at  a  horse's  lips  and 
leaves  eggs  there,  as  C.  H.  Townsend  stated.  The  eggs  of  G.  nnsalis 
are  deposited  on  hairs  of  the  throat.  The  adult  fly  strikes  at  the  hairs 
of  the  skin  between  the  mandibles,  and  sometimes  on  the  hairs  of  the 
cheek.  The  clasping  stalk  of  the  ^gg  of  G.  hsemorrhoidcdis,  which  is 
invariably  found  attached  to  the  short  hairs  of  the  lips,  often  appears  to 
penetrate  the  skin.  This  is  not  really  the  case,  but  the  clasping  stalk 
may  sometimes  enter  the  hair  follicle.  J.  A.  T. 

Behaviour  of  Larvae  of  Corethra  punctipennis. — Chancey  Juday 
(Froc.  Amer.  Soc.  Zool.  in  Anat.  Record,  1920,  17,  340).  In  the  deeper 
portions  of  Lake  Mendota  these  larvge  are  very  abundant ;  more  than 
30,000  per  square  metre  have  been  noted.  The  larger  larva3  burrow 
during  the  day  in  the  mud  (in  anaerobic  conditions  for  two  months  in 
summer)  ;  at  night  they  occupy  the  water,  and  may  ascend  to  the  surface 
— a  vertical  migration  of  25  metres.  The  pupge  do  the  same.  The 
small  larvse  occupy  the  lower  water  in  the  daytime  for  a  week  or  two, 
migrating  upwards  at  night.  J.  A.  T. 

Olfactory  Sense  in  Orthoptera. — N.  E.  McIndoo  {Proc.  Amer.  Soc, 
Zool.  in  Anat.  Record,  1920,  17,  3-41-2).  In  grasshoppers  and  crickets 
there  are  olfactory  pores  on  the  first  and  second  segments  of  the  antennae. 
When  the  antennae  are  cut  off  through  the  third  segment  the  reaction 
time  to  odours  is  increased.  The  average  reaction  time  of  the  intact 
grasshoppers  is  8  •  4  seconds,  after  mutilation  9  seconds.  The  average 
reaction  time  of  the  intact  crickets  is  8*8  seconds,  and  after  mutilation 
10-2  seconds.  J.  A.  T. 

Variation  in  Venation  of  Panorpa  communis. — L.  Mercier  {G.R. 
Soc.  Biol,  1919,  82,  1168-70).  The  radial  nervure  in  the  genus 
Panorpa  has  a  single  sector,  which  often  gives  off  four  branches,  and  often 
three  in  P.  communis.  The  character  may  be  regarded  as  at  present 
quite  unfixed.  J.  A.  T. 

Bed-bug. — Bruce  F.  Cummings  (Pnhlications  British  Museum,  Nat. 
Hist.,  Economic  Series,  1918,  No.  5,  1-20,  7  figs.).  A  very  clear  account 
of  the  external  structure  and  the  habits  of  Cimex  Jectularius,  with 
particular  reference  to  its  mode  of  sucking  blood.  The  life-history  is 
sketched,  and  the  possibility  tliat  it  spreads  disease-germs  is  discussed. 
The  blockage  of  the  gut  with  bacteria  that  occurs  in  the  rat-flea  is  not 
likely  to  occur  in  the  bed-bug  ;  so  it  is  not  very  probable  that  the  trans- 
mission of  diseases  by  bed-bugs  is  of  general  occurrence.  Remedies  are 
duly  dealt  with.  J.  A.  T. 


ZOOLOGY   AND    BOTANY,   MICROSCOPY,    ETC.  197 

Incubation  of  E^gs  of  Horse-lice. — A.  Bacot  and  L.  Lixzell 
{Parasitology,  11)19,  11,  388-92).  Three  kinds  of  lice  are  found  on 
iorses — Trickodectes  equi  ^nii  T.p'dosus  (Mallopliaga),  and  Bsematojmius 
asini  (one  of  the  Siphunculata).  The  eggs  of  the  last-named  species 
may  take  a  month  or  more  to  hatch,  therefore  the  last  dressing  should 
be  given  not  less  than  thirty-four  days  after  the  time  the  treatment 
started.  The  minimum  time  for  development  from  hatching  to  the 
fertile  female  is  probably  about  a  fortnight.  If  the  dressing  is  repeated 
at  ten-day  intervals  there  should  be  at  least  four  dressings.  The  normal 
incubation  period  would  appear  to  be  sixteen  to  twenty  days  ;  the 
minimum  in  natural  conditions  about  fifteen  to  sixteen  days.  A  very 
small  amount  of  dry  heat  is  fatal  to  the  eggs.  Moist  cold  also  kills,  but 
dry  cold  lengthens  out  the  incubation  period.  J.  A.  T. 

Systematic  Questions  concerning  Lice. — George  H.  F.  Nuttall 
{Parasitology,  1919,  11,  329-16).  The  name  Anoplura  Leach  (1817) 
was  originally  applied  to  both  Siphunculata  and  Mallophaga,  and  it 
should  be  still  used  in  that  sense.  Diagnoses  are  given  of  the  order 
Anoplura,  the  sub-orders  Mallophaga  and  Siphunculata,  the  four  families 
of  Siphunculata  (Pediculidae,  H^matopinidEe,  Echinophthiriidfe,  and 
H£ematomyzida3),  and  the  genera  Pedicidus  and  Phtkirus.  Morpho- 
logical and  biological  evidence  is  submitted  showing  that  Pedicidus 
w pit  is  and  P,  corporis  merely  represent  two  unstable  races  of  one  species, 
P.  humanus  Linnaeus.  J.  A.  T. 

Mallophaga  from  Formosan  Birds. — Seinosuke  Uchida  (Annot. 
Zool.  Japon.,  1920,  9,  635-52,  3  figs.).  Twenty-six  species  are  de- 
scribed, three  new,  including  Coinatomenopon  elongatwn  g.  et  sp.  n. 
from  a  tern.     It  is  an  elongate  translucent  form,  showing  in  both  sexes 


Gastric  teeth  of  Comatomenopon  elongatum  g.  et  sp.  n.     x  230. 

a  dense  row  of  dark-coloured  teeth  at  the  distal  end  of  the  crop.  This 
is  the  second  case  known  of  the  presence  of  gastric  teeth  in  the  Mallo- 
phaga, the  first  case  having  been  reported  by  B.  F.  Cummings  in 
Trimenopon  echinodermata  from  Cavia  aperea.  J.  A.  T. 

New  Mallophaga  from  South  African  Birds.— Gr.  A.  H.  Bedford 
{Parasitology,  1920, 12, 167-72,  2  pis.).  A  description  of  Machwrileemus 
2)locei  sp.  n.  from  a  waxbill,  and  Neomenopon  pteroclurus  g.  et  sp.  n.  from  a 
sand-grouse.     The  head  of  the  new  genus  has  distinct  and  fairly  deep 


198  SUMMARY   OF   CURRENT   RESEARCHES    RELATING   TO 

ocular  emarginations  ;  it  is  very  broad,  more  than  twice  as  wide  as  long  ; 
the  temples  are  large.  There  is  no  chitinous  plate  on  the  throat,  but 
there  is  a  chitinous  framework  for  the  support  of  the  mandibles.  The 
prothorax  has  its  lateral  margins  rounded.  The  mesothorax  is  fused  to 
the  metathorax.     The  pleurites  are  well-developed.  J.  A.  T. 

Head  and  Mouth-parts  of  the  Apple-sucker. — A.  J.  Grove  {Para- 
sitologij,  1919,  11,  456-88,  3  pis.,  1  fig.).  Description. of  Ps?/Z/«  ?naU  as, 
regards  the  exoskeleton  of  the  head  (the  head-capsule,  the  buccal  region 
and  labium,  the  setse,  and  the  hypopharynx),  the  endoskeleton  of  the 
head  (the  tentorium,  the  salivary  pump,  and  the  pharynx),  and  the 
complex  musculature  concerned.  In  regard  to  the  mechanism  of  pierc- 
ing, it  is  shown  that  this  cannot  be  due  to  the  ac'-ion  of  the  protractor 
muscles,  and  it  is  suggested  that  the  setse  are  forced  into  the  host 
through  the  agency  of  the  labium,  actuated  by  variations  in  the  internal 
pressure  of  the  body-fluid  contained  within  it.  A  raising  of  the  thorax 
w^hen  the  labium  is  in  a  state  of  turgescence,  and  consequently  has  a 
firm  grip  of  the  setae,  will  withdraw  the  setse  from  the  v^ound.  As 
regards  the  mechanism  of  sucking,  it  is  suggested  that  the  sap  rises  in 
the  suction-canal  by  means  of  capillarity.  The  injection  of  the  salivary 
secretion  into  the  host  by  the  propulsive  force  exerted  by  the  salivary 
pump  is  also  discussed.  J.  A.  T. 

Food-canal  of  Cicada. — 0.  W.  Hargitt  and  L.  M.  Hickernell 
{Froc.  Amer.  Soc.  Zooh  in  Ayiat  Record,  1920,  17,  351-2).  There  is  a 
well- differentiated  and  continuous  digestive  tube  in  the  adults  of  both 
sexes.  The  alleged  discontinuity  is  not  confirmed,  but  there  is  a 
thinning  of  the  digestive  epithelium  as  adult  life  proceeds.  At  the 
posterior  end  of  the  relatively  short  and  narrow  oesophagus  there  is  a 
valve  which  marks  the  beginning  of  the  crop.  Following  the  crop 
proper  there  is  an  anteriorly  directed  coil  of  intestine  with  Malpighian 
tubules.  The  coil  lies  just  dorsal  to  the  crop.  Thereafter  the  intestine 
run^  dorsally  to  the  seventh  abdominal  segment  where  it  opens  into  the 
rectum.  J.  A.  T. 

Vision  in  Cicada  septendecim.— S.  0.  Mast  {Froc.  Amer.  Soc. 
Zool.  in  Anat  Record,  1920,  17,  345).  When  the  "pupie"  emerge 
from  their  long  sojourn  (seventeen  years  or  so)  in  the  ground  they 
make  for  a  tree  or  the  like,  which  they  ascend.  If  it  is  dark  or  if  their 
eyes  are  covered  they  no  longer  go  toward  the  trees.  While  the  trunks 
of  most  trees  are  considerably  darker  than  the  rest  of  the  background, 
those  of  some  trees  (e.g.  the  sycamore)  are  lighter.  But  the  Cicadas 
(which  appear  to  be  called  "  locusts  ")  go  toward  the  latter  as  well  as 
toward  the  former.  Hence  their  positive  reaction  to  trees  is  largely 
independent  of  the  intensity  of  the  reflected  light.  They  probably 
perceive  the  configuration  or  outline.  They  almost  never  climb  up  on 
bare  buildings.  "  How  the  eyes  and  vision  originated  in  these  animals 
in  which  they  are  functional  only  a  few  weeks  during  the  seventeen 
years  of  their  life  is  an  interesting  problem."  (The  origin  is  surely  to 
be  looked  for  in  ancestral  forms  of  different  habits.)  J.  A.  T. 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,   ETC.  199 


5.  Aracbnida. 

Palpar  Organ  of  Male  Spiders. — W.  M.  Barrows  {Proc.  Amer. 
Soc.  Zool.  in  Anat.  Record,  1020,  17,  351).  The  palpar  organ  is  a 
hjpertropbied  terminal  claw  or  dactylus.  Before  the  last  moult  of  the 
male  spider,  the  gland  which  secretes  the  claw  is  pulled  back  toward 
the  centre  of  the  tarsus  by  the  attached  muscles,  which  then  degeneratCo. 
The  mass  of  gland  cells  which  now  forms  the  foundation  of  the  palpar 
organ  develops  an  inner  tube  by  tlie  invagination  of  cells  from  the  tip. 
In  its  cramped  position  the  claw  twists  on  itself,  developing  variously 
shaped  teeth  which  usually  correspond  with  unmodified  teeth  on  the 
female  claw.  The  muscles  working  the  claw  or  palpar  organ  appear  to 
degenerate  and  to  be  replaced  by  a  new  set  after  each  moult. 

J.  A.  T. 

Injurious  Arachnids  and  Myriopods. — Stanley  Hirst  {Species  of 
Arachnida  and  Myriopoda  Injurious  to  Man,  British  Museum  {Natural 
History)  Fublicafions,  1917,  Economic  Series,  No.  6,  1-60,  2G  figs.). 
An  excellent  account  of  spiders,  scorpions,  ticks,  and  mites  which  are 
directly  or  indirectly  injurious  to  man.  AVe  may  note  Holothyrus 
coccinella,  a  mite  which  secretes  an  irritant  poisonous  fluid  ;  Oytoleichus 
hominis,  an  acarid  found  by  Castellani  in  the  body  of  a  negro  in  Uganda ; 
Rhizoglyphus  parasiticus,  causing  *'  water  itch  "  on  the  feet  of  coolies 
employed  in  tea-gardens  in  Assam ;  the  carnivorous  mite  Fedicidoides 
ventricosus,  causing  "  grain  itch  "  on  men  handling  cotton-seed  ;  Nephro- 
phagus  sanyuinarius,  a  mite  found  dead  day  after  day  for  a  week  or 
more  in  the  urine  of  a  Japanese.  There  are  some  other  very  interesting 
forms  dealt  with  which  are  not  very  generally  known.  J.  A.  T, 

Behaviour  of  Sexes  in  Ixodidse.— George  H.  F.  Nuttall 
{Parasitology,  1919, 11,  394-404).  The  males  of  Amblyomma  helrseum 
anchor  immediately  when  placed  in  a  hungry  state  upon  the  host 
(scrotum  of  a  ram),  but  females  will  not  do  so  in  the  absence  of 
previously  anchored  males.  After  the  males  are  fed  for  some  days  they 
show  sexual  excitement ;  without  releasing  their  mouth-parts  they  seize 
females  that  chance  to  come  near.  To  copulate  they  must  release  their 
mouth-parts.  After  feeding  for  two  to  eight  days  the  females  wander 
and  are  seized  by  males.  The  ventral  surfaces  are  apposed,  and  the 
female  proceeds  to  feed,  puncturing  the  skin  of  the  host  with  her 
mouth-parts,  in  close  proximity  to  those  of  the  male.  Copulation  takes 
place  in  due  course,  the  male  temporarily  removing  his  mouth-parts 
from  the  host  for  the  purpose.  A  male  may  copulate  with  several 
females.  A  female  may  seek  two  males  in  succession.  Females  feed 
very  slowly  in  the  absence  of  males.  They  gorge  rapidly  when  fertilized, 
and,  when  fully  gorged,  usually  abandon  the  host  without  delay. 

The  males  of  Hyalomma  segyptium  anchor  immediately  when  placed 
on  the  same  host.  In  the  absence  of  females  they  remain  fixed  or 
change  very  slightly.  They  are  excited  by  the  close  proximity  of 
females.  The  females  do  not  as  a  rule  change  their  anchorage 
from  start  to  finish  ;  the  males  seek  them  out.     The  sexes  of  Rhipi^ 


200  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 

tepJialns  bursa,  when  hungry,  fix  at  once  on  the  host.  After  three  to 
five  days  the  males  seek  anchored  females,  a  number  in  succession.  As 
in  other  species  the  males  remain  upon  the  host  after  the  females  drop 
off,  which  accounts  for  the  predominance  of  male  ticks  on  a  host. 

J.  A.  T. 

Spermatogenesis  in  Ixodes  ricinus. — Erik  Nordenskiold  {Para- 
sitology, 1920,  12,  159-66,  1  pL).  The  spermatogonium  has  twenty- 
eight  chromosomes  at  mitosis ;  the  centrosome  appears  then  as  a  very 
conspicuous  triangular  corpuscle.  The  spermatocytes  of  the  first  and 
second  order  are  described.  The  spermatid  undergoes  intricate  meta- 
morphosis, affecting  nucleus,  cytoplasm,  centrosome  and  mitochondria. 
'The  outcome  of  the  changes  which  the  author  describes,  not  very 
readily  summarized,  is  the  formation  of  an  atypical  spermatozoon,  not 
easily  comparable  with  the  common  spermatozoon  type.  It  shows  a  rod- 
like, laterally  placed  nucleus,  a  conical  centrosomal  corpuscle  united  with 
the  nucleus,  and  a  plasma  rod  with  a  stainable  core.  J.  A.  T. 

Patal  Occurrence  of  a  Pentastomid  in  Man. — Monziols, 
CoLLiGNON,  and  Jean  Roy  {G.  R.  Soc.  Biol.,  1920,  83,  28-9).  A 
Senegalese  tirailleur  died  in  hospital  at  Constantinople  of  severe  icteritis, 
accompanied  by  cerebral  excitement.  His  liver,  of  small  size,  showed  in 
the  biliary  canaliculi  an  enormous  number  of  specimens  of  Poro- 
cephaliis  armillattis,  marked  by  four  simple  hooks  and  twenty  to  twenty- 
two  rings.  The  adult  is  found  in  the  trachea  of  large  snakes  ;  the  larva 
occurs  in  monkeys  and  in  man  in  the  deeply  situated  organs.  The 
epidermis  of  the  specimens  is  chitinogenous  ;  connective  tissue  occupies 
the  place  of  the  dermis  and  the  interstices  ;  the  walls  of  the  intestine 
show  deep  folds  ;  there  was  no  trace  of  reproductive,  respiratory,  nervous, 
or  sensory  systems  ;  there  is  a  strongly  developed  muscular  system  of 
peripheral  fibres  (longitudinal  and  annular)  and  of  deep  fibres  around 
the  intestine.  This  is  the  second  instance  of  this  parasite  in  a  Sene- 
galese. J.  A.  T. 

e.  Crustacea. 

Fresh-water  Harpacticids  from  Peru. — Tir.  Delachaux  (Revue 
iSuisse  Zool.,  1918,  26,  117-27,  1  pi.).  Nine  species  of  Ganlhocamptus, 
including  three  new  ones.  The  occurrence  of  Mar  sen  oh  lotus  natico- 
chensis  is  interesting  as  regards  geographical  distribution.  Attention  is 
directed  to  a  representative  of  the  genus  Godetella,  whicli  is  allied  to  the 
European  WoJterstorffia  and  to  the  Asiatic  Marshia,  the  three  genera 
being  primitive  types  wliich  have  undergone  a  parallel  evolution  on  three 
continents.  The  Harpacticids  do  not  live  among  the  plankton  of  the 
open  water  of  the  lake,  but  in  shallow  water  among  aquatic  plants  and 
on  stones.  J.  A.  T. 

Annulata. 

Structure  of  Sabellids  and  Serpulids. — W.  C.  ^PIntosh  {Ann. 
3Ia(/.  Nat.  Hist.,  1918,  2,  1-59,  6  pis.).  Sabellid  structure  is  illustrated 
mainly  in  reference  to  Bispira  voluiacornis,  attention  l)eing  directed  to 


ZOOLOGY    AND    BOTANY.   MICROSCOPY.    ETC.  201 

the  body-wall,  the  branchial  apparatus  (with  its  chordoid  skeleton),  the 
nervous  system,  the  bristles,  the  blood-vessels,  and  the  thoracic  glands 
or  anterior  nephridia.  Serpulid  structure  is  illustrated  mainly  in  re- 
ference to  Pomatoceros  triqueter^  with  special  attention  to  the  body- wall, 
the  peri-intestinal  sinus,  the  thoracic  glands,  the  branchial  filaments,  the 
operculum  and  its  development,  and  the  nervous  system.  The  paper  is 
rich  in  interesting  observations  ;  we  cannot  do  more  than  indicate  its 
general  scope.  J.  A.  T. 

Interesting  Abnormality  in  a  Serpulid. — Enrique  Rioja  {Boll. 
Soc.  Espan.  Hist.  Nat.,  1*)19,  19,  445-9,  2  figs.).  Description  of  a 
specimen  of  Hydroldes  norvegica  Gunn.  which  showed  two  opercula.  The 
operculum  is  the  result  of  a  transformation  of  a  branchial  plume,  and 
the  author  maintains  that  the  primitive  Serpulids  had  a  double  operculum. 
The  present  day  forms  show  a  suppression  of  one  operculum  or  of  both 
of  them,  a  suppression  of  the  branchlets  on  the  stalk,  a  diminution  of 
the  number  of  thoracic  segments,  and  an  asymmetry  associated  with 
spiral  coiling.  J.  A.  T. 

Nematohelminthes . 

Nematode  Parasites  of  Zebra. — Charles  L.  Boulenger  {Para- 
sitology, 1920,  12,  98-107,  7  figs.).  Seven  species  are  dealt  with — 
Strongijliis  vulgaris,  Gylindropharynx  Irevicauda,  C.  longicauda,  Gylico- 
stomum  minutum,  C.  zelrae  sp.  n.,  C.  montgomeryi  sp.  n.,  Triodontophorus 
serratus,  and  Craterostomum  tenuicauda  g.  et  sp.  n.  The  first,  fourth 
and  seventh  are  also  parasites  of  domestic  equines.  The  new  genus  is 
closely  allied  to  Triodontophorus  Looss,  but  differs  in  the  absence  of 
teeth  projecting  into  the  mouth-capsule.  The  mouth  is  also  relatively 
smaller  and  the  number  of  elements  of  the  leaf-crowns  considerably  less 
than  in  any  known  species  of  Triodontophorus.  J.  A.  T. 

Trichocephalus  in  Liver  of  Rat. — L.  Muratet  {C.  R.  Soc.  Biol., 
1919,  82,  1383-4).  Lesions  on  the  liver  of  Mus  demmanus  were  found 
to  be  due  to  adult  specimens  of  Trichocephalus,  which  occur  coiled  up  in 
the  liver.  There  were  also  very  abundant  ova.  Some  adult  specimens 
of  Trichocephalus  were  also  found  in  the  intestine.  J.  A.  T. 

Platyhelminthes. 

New  Species  of  Oochoristica  from  Lizards. — H.  A.  Baylis 
{Parasitology,  1919, 11,  405-14,  1  pi.).  Descriptions  of  O.zoniiri?>^.  n., 
from  Zonurus  tropidosternum,  in  Portuguese  East  Africa,  and  0.  agamse 
sp.  n.  in  Agama.  These  new  forms  are  contrasted  with  0.  truncata  from 
Agama,  and  the  genus  Oochoristica  with  the  genus  Linstoivia.  Both 
genera  seem  to  belong  rather  to  the  Dilepinidag  than  to  the  Anoplo- 
cephalidae.  J.  A.  T. 

New  Species  of  Anchitrema. — L.  Gedoelst  {G.R.  Soc.  Biol,  Idld, 
82,  1250-2).  Description  of  A.  latum  sp.  n.,  from  the  posterior  intes- 
tine of  Chamseleon  dilepis,  differing  from  the  other  species  of  the  genus 
{A.  sanguineum)  mainly  in  the  proportions  of  the  body.  J.  A.  T. 


« 


202  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 

Turbellarians  of  Mississippi  Basin. — Ruth  Higley  {Illinois  BioL 
Monographs,  1918,  4,  1-94,  8  pis.).  In  swiftly  flowino^  streams  where 
a  rocky  bed  furnishes  a  sheltered  place  of  attachment,  Planarians  and  a 
few  creeping  Rhabdocoels  find  a  suitable  habitat.  For  most  of  the  free- 
swimming  species,  ponds  and  temporary  puddles  are  best.  They  afford 
a  protected  retreat  and  also  a  feeding-ground  in  the  masses  of  filamentous 
algis,  and  a  source  of  food  in  the  associated  animal  comumnities.  The 
response  to  the  presence  or  absence  of  oxygen  and  carbon  dioxide  is 
more  precise  than  that  evoked  by  any  other  stimulus.  The  reaction 
to  light  varies  in  different  species  ;  in  most  instances  it  is  negative, 
though  not  definitely  so.  Response  to  temperature  is  general  or  diffuse, 
rather  than  to  a  localized  stimulus,  such  as  the  seasonal  change  in  the 
condition  of  the  water.  Since  nourishment  is  obtained  mostly  from  dis- 
integrating protoplasm,  the  food  relationships  are  very  simple,  and 
although  nearly  defenceless  the  Turbellarians  appear  to  have  few 
enemies.  New  species  of  Stenostoma,  Macrostoma,  Dalyellia,  Strongylo- 
stoma  and  Merostoma  are  described,  and  the  precise  conditions  under 
which  they  live  are  noted.  J.  A.  T. 

Intestinal  Helminths  in  Indians  in  Mesopotamia— C.  L.  Boulexger 
{Parasitologij,  1920,  12,  95-7).  Out  of  1,180  individuals  examined 
1  • :}  p.c.  had  Teenia  saginata  ;  2  p.c.  Hymenolepis  nana  ;  5 '  2  p.c.  Ascaris 
lumhricoides  \  0*08  p.c.  Oxyuris  vermicuJaris  \  18*5  i^.c.  Anchylostoma 
(or  Ancylostoma)  dnodenah  and  Necator  americanus ;  1  •  2  p.c.  Tricho- 
strongylus  sp.  ;  0 '  5  p.c.  Strongyloides  stercoralis  ;  and  5  p.c.  Trichuris 
trichiurus.  Attention  is  drawn  to  the  fact  that  Hymenolepis  nana 
seems  to  be  the  commonest  tapeworm  met  with  among  Indians. 

J.A.  T. 


Nemertea. 

Sex  Dimorphism  in  Nemerteans. — W.  R.  Coe  {Proc.  Amer.  Soc 
Zool.  in  Anat.  Record,  1920,  17,  852).  Several  secies  of  Necione- 
mertes  show  in  the  mature  males  a  pair  of  lateral  muscular  tentacle-like 
appendages  immediately  behind  the  head.  The  testes,  which  are  limited 
to  the  head  region,  have  a  powerful  musculature  for  the  forcible  ejacula- 
tion of  the  sperms.  The  females  are  so  different  that  they  have  been 
referred  to  a  separate  genus.  It  is  probable  that  the  "  tentacles  "  are 
both  tactile  and  prehensile.  They  may  serve  to  hold  the  females  during 
insemination.  J.  A.  T. 


Coelentera. 

Mesenteries  in  Urticina  crassicornis. — James  F.  Cemmill  {Proc. 
Zool.  Soc,  1919,  45;)-7).  The  adult  Urticina  is  remarkable  as  having 
its  mesenteries  and  tentacles  apparently  arranged  in  ten-cycled  symmetry, 
and  on  that  account  has  been  placed  by  various  authors  among  the 
Paractinea3.  It  is,  however,  a  Ilexactinian,  with  the  arrangement  of  the 
mesenteries  modified  during  early  growth.  The  author  explains  how 
this  comes  about.  "  J.  A.  T. 


ZOOLOGY   AND    BOTANY,   MICROSCOPY,   ETC.  203 

Evolution  in  Sea-pens. — Sydney  J.  Hickson  {Proc.  Roy.  Soc, 
1918,  90,  108-35).  1.  liadially  symmetrical  animals,  sedentary  or 
drifting  in  habit,  are  far  more  variable  in  external  form  and  in  the 
number  and  arrangement  of  their  organs  than  are  bilaterally  sym- 
metrical ani]na]s,  free  and  active  in  their  movements.  2.  The 
radially  symmetrical  Pennatulids  are  more  variable  than  the  bilaterally 
symmetrical  Pennatulids  in  almost  all  the  important  characters  upon 
which  the  classification  is  based. I  This  is  substantiated  in  detail. 
3.  Particularly  in  the  sedentary  animals  do  we  find  illustrations  of 
plasticity  in  specific  characters.  4.  The  more  primitive  Pennatulids 
are  the  radially  symmetrical  forms,  and  it  is  probable  that  between 
sedentary  Alcyonarian  ancestors  aud  the  Pennatulids  we  know  there 
intervened  an  intermediate  stage  with  some  powers  of  muscular  move- 
ment, such  as  a  floating  or  drifting  colony.  J.  A.  T. 

Development  of  Agaricia  fragilis.— J.  W.  Mayor  (Froc.  Amer. 
Acad  Arts  Sci.,  1915,  51,  485-511,  6  pis.).  An  account  of  the  early 
stages  of  this  coral  common  on  the  shore  at  Bermuda.  A  pear-shaped 
planula  fixes  itself  and  becomes  flattened.  The  development  of  the 
mesenteries,  the  mesenterial  filaments,  and  the  gastro-vascular  cavities 
is  described.  The  gastro-vascular  cavity  seems  to  be  formed  by  a 
breaking  down  and  splitting  of  the  endoderm.  The  mesenteries,  muscle 
cells  and  the  cells  which  will  form  or  have  formed  the  mesenterial 
filaments  are  the  agents  which  determine  its  form.  An  account  is  also 
given  of  the  post-larval  development,  including  the  earliest  stages  of 
the  skeleton.  The  basal  plate  and  the  six  primary  entosepta  are  the 
first  structures  to  be  developed.  The  primary  exosepta  do  not  arise 
simultaneously.  Bilateral  symmetry  is  frequently  shown  in  the  arrange- 
ment of  the  primary  entosepta.  There  is  considerable  varialjility  in 
the  development  of  the  septa.  J.  A.  T. 

Ciliation  of  a  Leptomedusan. — James  F.  Gemmill  (Proc.  Zool. 
Soc,  1919,  459-61,  1  fig.).  In  the  gonophore  of  Melicertidiiim  octoco- 
staturn  (Sars)  the  radial  and  ring  canals  are  wide  enough  to  allow  the 
action  of  the  ciliated  lining  to  be  studied.  The  ciliary  currents  are 
described  in  the  stomach,  the  manubrial  canal,  the  radial  canal,  and 
the  ring  canal.  There  is  no  ciliation  on  the  exi.mbrellar  surface, 
but  there  is  much  on  the  sub-umbrellar  surface,  and  the  currents  are 
regular,  gathering  food-particles  to  the  mouth.  The  tentacles  show^ 
weak  ciliation  except  on  their  inner  sides  near  their  bases,  where  they 
are  ciliated  more  strongly.  Their  ends  are  sometimes  turned  into  the 
mouth.  The  ciliation  of  the  gastrovascular  lining  subserves  in  the  first 
place  the  mixing  and  transport  of  the  food,  and  is  also  capable  of  aiding 
the  ingestion  of  small  food  particles  and  the  evacuation  of  the  sex-cells 
through  the  mouth.  J.  A.  T. 

Somatic  and  Germ-cells  in  CoBlentera. — George  T.  Hargitt 
(Proc.  Amer.  Soc.  Zool.  in  Anat.  Record,  1920,  17,  327).  All  cells  of 
the  Hydrozoan  body,  except  perhaps  the  stinging-cells  and  the  nerve- 
cells,  are  capable  of  further  differentiation  in  various  directions.  This 
includes  the  power  of  de- differentiation  and  of  specialization  in  a  new 


204 


SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 


direction.  Therefore,  the  author  says,  there  cannot  be  any  real  distinction 
between  body-cells  and  germ-cells.  (There  remains,  however,  this 
•distinction,  that  a  fertilized  ovum  can  develop  into  an  offspring,  which 
no  de -differentiated  somatic  cell  or  pair  of  cells  can  do.)  Specialized 
cells  even  in  Vertebrates  show  in  varying  degrees  the  power  of  de- 
differentiation  and  new  specialization.  But  there  is  a  time  in  ontogeny 
when  further  specialization  of  cells  involves  the  loss  of  capacity  of  any 
new  differentiation  ;  this  is  the  period  at  which  germ-cells  are  usually 
segregated  into  a  distinct  tissue.  In  the  higher  organisms  this  may  occur 
early  in  development ;  in  Hydrozoa  it  never  occurs.  J.  A.  T. 

Coeloplana. — Taku  Komai  {Annot.  Zool.  Japon.,  1920,  9,  575-84, 
5  figs.).  Description  of  a  Ccdoplcma  bocJci  sp.  n.,  found  abundantly  as  a 
commensal  of  a  littoral  species  of  Dendronephthya,  common  near  Misaki. 
It  differs  from   C  tvilleyi  and  C.  mitsuTcuri  from  the  same  locality  in 


Larva  of  Coeloplana  bocki,  adhering  to  the  substratum  by  the  thin " 
expanded  sole.  The  main  body  is  laid  back  and  seen  on  the 
transverse  plane,      x  170. 

ph.\  inner  part  of  pharynx  ;  pg.,  pigment  spots  ;  ce.,  oesophagus  ; 
t.,  tentacle;  t.sh.,  tentacle  sheath;  s.,  aboral  sense-organ; 
pp.,  polar  plates  ;  ph.f.,  pharyngeal  folds 


being  much  smaller,  in  peculiarities  of  coloration,  and  in  having  two  to 
five  lobe-like  processes  around  the  periphery  of  the  polar  plates.  It  is 
hermaphrodite,  and  some  specimens  overlay  clusters  of  developing  eggs 
in  direct  contact  with  the  ventral  surface.  The  segmentation  and  gas- 
trulation  are  as  in  other  Otenophores,  and  there  is  a  Cydippid  larva. 
There  can  be  no  doubt  that  the  genus  is  derived  from  a  Cydippid  stock 


ZOOLOGY   AND   BOTANY,    MICROSCOPY,   ETC.  205 

by  a  loss  of  certain  characters  and  a  concomitant  acquisition  of  new 
features  adapted  to  the  change  from  free-swimming;  to  creeping  life. 
There  is  evidence  that  the  entire  creeping  surface  of  Cceloplcma  is  derived 
from  a  turning  out  of  a  large  part  of  the  inner  pharyngeal  surface  of 
ordinary  Cydippids.  It  seems  that  the  flatness  of  the  body  in  this 
aberrant  form  is  largely  due  to  this,  and  not  merely  to  a  reduction  of  the 
vertical  axis  of  the  body.  J.  K.  T. 

Ciliary  Action  in  Pleurobrachia  pileus. — James  F.  Gemmill 
{Proc.  Zool.  Soc,  1918,  263-5,  2  figs.).  In  the  internal  cavities  of  this 
Ctenophore  there  is  very  orderly  "circulation"  maintained  by  ciliary 
action,  and  detected  by  the  motion  of  particles  suspended  in  the  contained 
fluid — e.g.  small  oil  globules,  alimentary  particles  and  debris.  There  are 
aboralward  and  oralward  currents  in  the  stomodteum,  and  there  is  a 
more  complex  circulation  in  the  canal  system.  J.  A.  T. 

Gastrodes  parasiticum  Korotneff. — Taku  Komai  {Annot.  ZooL 
Japon.^  1920,  9,  585-90).  An  account  of  this  imperfectly  l^nown  and 
remarkable  parasitic  Coelenterate,  found  embedded  in  the  test  of  Salpa. 
Korotneff,  the    discoverer   of   the   animal,  referred  it  at  first  to   the 


^.e 


Dorsal  view  of  an  early  stage  of  Gastrodes  parasiticum  Korotneff.     x  90> 
ce.,  oesophagus;  w.c,  meridional  canal ;  t.h.,  tentacle  basis. 

XarcomedusEe  and  afterwards  to  the  Actiniae.  Heider  regarded  it  as  a 
degenerate  Ctenophore,  and  Ctenophore  it  is.  The  colourless  disc-like 
body  is  more  or  less  convex  on  the  dorsal  side,  and  measures  0  •  5-3  mm. 
in  diameter.  The  gastrovascular  system  is  represented  by  a  connected 
pair  of  cavities,  each  laterally  divided  into  four  peripheral  pouches  ;  the 
oesophagus  is  not  laterally  compressed  ;  the  tentacle  apparatus  is  indi- 
cated by  mere  thickenings  of  the  epidermis,  and  the  aboral  sense-orgau 
by  a  shallow  depression  containing  as  yet  no  otolithic  mass.  From 
such  simple  stages  there  is  a  gradation  to  forms  with  eight  rows  of  comb- 
plates,  an  aboral  sense-organ,  and  a  tentacle  apparatus.     It  is  likely  that. 


206 


SUMMARY    OF   CURRENT    RESEARCHES   RELATING   TO 


the  auimal  becomes  free.  It  is  probably  referable  to  the  Platjctenea. 
This  is  indicated  by  the  covering  of  the  ventral  surface  with  ciliated 
epithelium  and  the  profuse  foldings  in  the  central  region  of  that  surface. 
The  ventral  surface  may  have  arisen,  as  in  Cmloplana,  by  a  turning  out 


Advanced  stage  of  Gastrodes  parasiticmn  Korotneff,  which  has  changed 
from  a  more  flattened  to  a  hemispherical  shape  on  liberation  from 
the  host.      X  50. 

c,   comb-plates;    s.,  aboral   sense-organ;    t.b.,   tentacle   basis;    w.c, 
meridional  canal ;  ph.c,  pharyngeal  canal ;  t.,  tentacle, 

of  the  pharynx.  Moreover  the  oesophagus  is  well  differentiated,  the 
meridional  canal  exhibits  signs — though  slight — of  branching,  and  the 
infundibular  canal  is  obliterated.  J.  A.  T. 


Protozoa. 

Influence  of  Environment  on  Arcella. — Robert  W.  Hegner 
{Journ.  Ejyer.  Zooh,  11)11),  29,  427-41,  7  figs.).  AVhen  specimens  of 
Arcella  dentata  are  underfed,  the  interval  between  successive  divisions 
increases  from  an  average  of  2  •  5  days  to  about  4  ;  the  shell  decreases 
in  diameter  on  the  average  2 '08  units  of  4*;^ /a  each  ;  the  spine  number 
slightly  decreases.  The  offspring  are  normal  when  given  abundant 
food.  In  a  medium  containing  1  drop  of  sodium  silicate  to  100  cc.  of 
water  A.  dentata  grows  and  reproduces ;  the  fission  rate  decreases 
as  above  ;  the  size  of  the  progeny  produced  in  the  solution  is  reduced  ; 
the  spines  disap])ear;  the  colour,  which  becomes  brown  in  a  normal 
medium,  remains  a  pale  greenish  yellow.      Specimens  reared  in  this 


ZOOLOGY    AND    BOTANY,    MICllOSCOPY,    ETC.  207 

:solutioii  and  then  returned  to  a  normal  medium  regain  the  fission  rate, 
size,  spine  length,  and  colour  characteristic  of  the  race.  Specimens 
grow  and  reproduce  in  a  medium  with  0*25  to  1  p.c.  of  alcohol,  but  the 
alcohol  is  injurious,  as  indicated  bj  the  retarded  fission  rate  and  irregu- 
larities in  the  shells  of  the  off'spring.  Lowering  the  temperature  seems 
to  lead  to  reduction  of  the  length  of  the  spines.  Wild  specimens  of 
A.  polypora  with  a  bent  oval  shell  with  an  oval  mouth  gave  rise  in 
laboratory  conditions  to  offspring  with  a  flat  circular  shell  and  a  circular 
mouth  opening.  It  appears,  then,  that  modifications  induced  by  environ- 
mental peculiarities  persist  only  so  long  as  the  modifying  factors  are 
operative.  Xo  heritable  diversities  were  observed  that  were  due  to  the 
changed  conditions.  J.  A.  T. 

Intestinal  Protozoa  in  Members  of  Egyptian  Expeditionary  Force. 
— F.  ^\.  OX'ONNOR  {Parasitology,  11)19,  11,  239-55,  1  pL,  3  figs.). 
Report  dealing  Avith  Entammha  histolytica,  E.  coU,  Trichomonas  hominis, 
LamUia  intestinalis,  ^'  Entamoeba  ^^  nana,  Tricercomonas  and  Isospora 
hominis.  J.  A.  T. 


Race  of  Oxytricha  without  a  Micronucleus.  —  J.  A.  Dawson 
{Journ.  Exper.  ZooL,  1919,  29,  473-513,  2  pis.).  A  pedigreed  culture 
of  Oxytricha  hymenostoma  was  kept  up  for  289  generations  (from 
July  10,  1917,  to  April  30,  1918),  and  no  micronucleus  was  seen.  Nor 
was  there  any  true  conjugation  or  syngamy.  Individuals  fused  in  pairs 
in  a  manner  similar  to  that  of  conjugating  individuals,  and  remained 
fused  till  death  occurred,  or  else  separated  and  went  on  multiplying. 
Catmibalism  was  frequent  and  digestion  rapid.  Cannibalism  has  the 
effect  of  raising  the  division  rate  somewhat  for  a  short  time.  The 
amicronucleate  condition  seems  to  preclude  the  occurrence  of  conjuga- 
tion, autogamy,  and  endomixis  ;  yet  without  these  the  race  flourishes  in 
favourable  environmental  conditions.  J.  A.  T. 


Structure  of  Noctiluca. — Charles  A.  Kofoid  (JJniv.  California 
PuUications,  Zoology,  1920,  19,  317-34,  1  pi.,  2  figs.).  A  new  inter- 
pretation is  offered,  that  Noctiluca  is  a  dinoflagellate  highly  modified 
through  distention  by  hydrostatic  vacuoles.  It  retains  the  dinoflagellate 
sulcus,  modified  anteriorly  into  the  apical  trough  and  the  recessed  oral 
pouch  and  cytostome.  Of  the  girdle  only  the  proximal  part  persists  ;  it 
has  been  hitherto  overlooked.  It  is  a  shallow  trough  at  the  left  of  the 
sulcus  and  at  right  angles  to  it.  It  is  best  seen  in  small  individuals. 
With  the  degeneration  of  the  girdle  has  gone  the  reduction  of  the  trans- 
verse flagellum  to  the  prehensile  tooth  which  lies  at  the  proximal  end  of 
the  girdle  at  the  left  of  the  base  of  the  longitudinal  flagellum.  This 
organ  exhibits  structural  undulations  and  spasmodic  and  rhythmical 
contractions.  The  longitudinal  flagellum  is  reduced  and  lies  within  the 
oral  pouch.  It  is  the  distention  with  hydrostatic  vacuoles,  with  flotation 
replacing  active  locomotion,  which  has  led  to  the  degeneration  of  the 
flagella  and  their  reduction  in  size,  and  to  the  almost  complete  disappear- 
ance of  the  girdle.     The  posterior  tentacle  is  the  homologue  of  the 


208 


SUMMARY  OF  CURRENT  RESEARCHES  RELATING  TO 


tentacle  of  Pavillardia  and  Enjihroims^  and  is  not  a  modified  flagellum. 
The  order  Cystoflagellata  is  not  required  for  Noctiluca  ;  it  may  remain 
in  the  meantime  for  Leptodiscus  and  Oraspedotella.     The  structure  of 


*'"- — -  postp. 


long,  fl 


A  typical  dinoflagellate,  Gyrodinium  corallinum  g.  et  sp.  n. 
(Kofoid  and  Swezy  MSS.).     x  600. 

■Ant.p,^  anterior  pore;  epi.,  epicone ;  qir.,  girdle;  hyp.,  hypocone ; 
interc.a.,  inter-cingular  area ;  long.fl.,  longitudinal  liagellum ;  n.., 
nucleus  ;  pig.,  pigment ;  post. p.,  posterior  pore  ;  pus.,  pustule  ;  sulc, 
sulcus  ;    tr.fi.,  transverse  flagellum. 

Noctiluca  should  be  compared  with  that  of  a  typical  dinoflagellate  (see 
figure),  with  sulcus,  girdle,  and  flagella,  but  it  has  no  theca  or  cuirass. 

J.  A.  T. 

Renewal  of  Vitality  through  Conjugation. — Gary  N.  Calkins 
{Joum.  Exper.  Zool.,  1919,  29,  191-56,  1  chart,  1  fig.).  In  the  hypo- 
trichous  ciliate  UrolejHus  mobiUs  the  processes  of  metabolism  are  not 
capable  of  unlimited  activity.  The  limits  vary  from  'iiJS  to  349  genera- 
tions after  conjugation  or  encystment.  There  is  an  optimum  during 
the  first  tliree  montlis  after  conjugation,  and  then  a  progressive  and 
cumulative  weakening  of  metabolic  vigour,  leading  to  death.  Conjuga- 
tion, however,  changes  the  protoplasm  from  metabolic  weakness  to 
optimum  vigour.  There  is  a  limit  to  tlie  extent  to  wliich  the  pro- 
toplasm can  be  rejuvenated.  It  seems  as  if  the  protoplasm  could  hold 
only  a  certain  charge,  so  to  speak,  or  potential  of  metabolic  vigour,  as  a 


ZOOLOGY   AND    BOTANY,  MICROSCOPY,   ETC.  209 

result  of  conjugation.  This  optimum  is  subject  to  change  by  environ- 
mental conditions,  being  increased,  for  example,  by  heat.  It  also 
appears  that  rejuvenescence  may  follow  encystment  and  parthenogenesis 
when  no  nuclear  interchange  has  occurred.  In  some  cases  the  re- 
juvenating effect  of  parthenogenesis  was  even  greater  than  that  of 
conjugation.  Parthenogenesis  through  encystment  seems  to  be  am 
attribute  of  high  vitality,  and  the  ability  to  encyst  is  apparently  lost 
at  an  early  date.  The  condition  of  physiological  depression  is  ac- 
companied by  structural  changes,  which  are  described  in  detail.  In 
conjugation  the  most  significant  phenomenon  is  the  granular  disin- 
tegration of  the  old  macronuclei  and  the  absorption  of  relatively  large 
quantities  of  nuclear  substance  in  the  cytoplasm.  The  same  is  true  of 
encystment  and  in  division — there  is  re-organization  of  the  cytoplasm. 

J.  A.  T. 

Periodicity  in  Photic  Responses  of  a  Euglenoid. — S.  0.  Mast 
{^Proc.  Amer.  Soc.  Zool.  in  Anat.  Record,  1920,  17,  345).  In  some 
organisms — eg.  Convohita — changes  of  movement  continue  for  some 
time  in  the  absen(;e  of  the  environmental  conditions  to  which  they  were 
formerly  related  (the  tides  in  the  case  mentioned).  Like  many  of  the 
Euglenoids,  Septocinclis  texta  responds  very  definitely  to  light.  If  kept 
in  total  darkness  and  tested  from  time  to  time  in  an  illumination  of 
proper  intensity,  it  is  positive  from  early  morning  to  about  1  p.m.  It 
then  becomes  negative,  and  remains  so  till  8  or  9  p.m.,  when  it  becomes 
positive  again  until  the  following  afternoon.  Thus  in  the  absence  of 
light,  for  at  least  three  days,  there  appears  to  be  in  its  physiological 
processes  a  periodicity  w^hich  is  normally  associated  with  alternation 
between  day  and  night,  and  determines  whether  its  orientation  to  light 
is  positive  or  negative.  J.  A.  T. 

Adaptation  to  Light  in  Euglena  variabilis. — S.  0.  Mast  {Proc. 
Amer.  Soc.  Zool.  in  Anat.  Record^  1920,  17,  346).  Euglena  becomes 
rapidly  adapted  to  any  given  illumination,  and  if  adapted  to  low  illumi- 
nation or  darkness  it  tends  to  be  negative  in  strong  and  positive  in 
weak  light,  and  to  aggregate  in  moderate  illumination.  If  adapted  to 
high  illumination,  it  tends  to  be  positive  in  strong  and  negative  in  weak 
light,  and  to  aggregate  in  very  high  and  very  low  illumination.    J.  A.  T. 

Trichomonas  of  Guinea-Pig. — Edouaed  Chatton  {C.  R.  Soc.  Biol., 
1920,  83,  69-72).  An  account  of  attempts  to  secure  a  pure  culture  of 
a  species  of  Trichomonas  which  is  often  very  abundant  in  the  caecum  of 
the  guinea-pig.  It  lives  well  in  ordinary  bouillon  to  which  blood  is 
added,  but  it  was  not  found  practicable  to  get  rid  of  four  kinds  of 
associated  bacteria.  The  flagella  are  markedly  alkalinophilous.  In  the 
culture  the  recurrent  flagellum  of  Trichomonas  separates  from  the  body, 
suppressing  the  undulating  membrane.  When  inoculated  into  the  peri- 
toneum of  the  guinea-pig  there  is  a  reappearance  of  the  undulating 
membrane.  In  different  media  there  are  different  surface-tension 
conditions  which  may  influence  the  structure  ;  there  may  also  be  an 
influence  from  specific  substances.  The  transformation  shows  how  close 
the  relationship  is  between  Trichomonas  and  Trichomastix.       J.  A.  T. 

P 


210  SUMMARY    OF  CURRENT    RESEARCHES    RELATING   TO 

Parasites  in  Chiton  and  Patella. — Paul  Debaisieux  {C.  R.  Soc. 
Biol,  1919,  82,  1400-2).  In  Chitons  there  are  at  least  three  distinct 
parasitic  Protozoa.  In  Acanthochites  fascicularis  the  liver  and  the 
epithelium  of  its  ducts  contain  large  numbers  of  FseudoJdossia  chitonis 
sp.  n.,  while  the  salivary  glands  abound  in  stages  of  one  of  the  Eimeridea. 
In  many  organs  of  CraspidocMlus  cinereus  there  is  Haplospoiidium 
chitonis  (=  Minchinia  chitonis).  In  Patella  vulgaris  there  is  a  new  form, 
FseudoJdossia  patella  sp.  n.  J.  A.  T. 

New  Species  of  Haplosporidium. — Paul  Debaisieux  (C.  R.  Soc. 
.Biol,  1919,  82,  1399-1400).  In  specimens  of  the  long  Nemertean 
Lineus  marimis  there  were  very  numerous  spores  of  a  new  species  of 
Haplosporidium  (H.  nemertis).  They  occurred  especially  in  the  connec- 
tive tissue  between  the  gut  and  the  longitudinal  muscles,  forming  an 
almost  continuous  layer.  The  youngest  stages  are  subspherical  and 
binucleate  masses — small  plasmodia.  These  grow  and  show  a  multipli- 
cation of  nuclei,  three  to  five  divisions  being  observed.  The  nuclei 
increase  in  size  and  undergo  two  more  successive  divisions  ;  the  multi- 
nucleate Plasmodium  resolves  itself  into  uninucleate  sporoblasts,  which 
are  transformed  into  spores.  Some  large  plasmodia  resolve  themselves 
into  the  binucleate  forms  mentioned  above,  which  spread  the  infection  in 
the  host.  J.  A.  T. 

Nutrition  of  the  Protozoa.  The  Growth  of  Paramoecia  in  Sterile 
Culture  Medium.— R.  A.  Peters  {Proc.  Phijs.  Soc,  1920,  53,  108-9). 
As  a  preliminary  step  to  the  study  of  the  metabolism  and  reactions  of 
Paramoecia  in  solutions  of  known  chemical  composition,  pure  cultures 
free  from  bacteria  are  needed.  Cultures  of  a  race  of  Paramoecia  about 
50  ft  in  length,  isolated  from  a  single  individual,  have  been  obtained  in 
the  following  medium  : — 

Per  cent. 

Sodium  chloride  .         ,         .         .         .  0*06 

Potassium  chloride     .....  0"0014 

Calcium  chloride 0'0012 

Basic  sodium  phosphate  (NaHPO)       .         .  0-0001 

Acid  potassium  phosphate  (KHPO)      .  .  O'OOOl 

Magnesium  sulphate.  ....  0*001 

Sodium  bicarbonate 0-002 

Phenol  red Trace 

Glucose      .         .         .         .  .         ,         .0*03 

Histidine O-Ql 

Arginine 0"01 

Leucine     .  .  .  .         .         .         .  0  01 

Ammonium  lactate     .....  0*003 

Ferric  chloride   ......  Trace 

Potassium  iodide        .....  Trace 

Manganous  chloride  .....  Trace 

The  above  substances  are  made  up  with  glass-distilled  water.  The 
constituents  are  autocluved  separately.  The  final  mixture  is  sterilized 
by  heating  to  80°C.  on  three  successive  days.  The  reaction  is  adjusted 
to  PH  =  7*4  with  NaOH  N/100.  The  organisms  were  cultivated  in 
sterile  media  in  depression  shdes,  experiment  showing  the  most  suitable 
concentration  for  division.     After  a  number  of  individuals  had  been 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,   ETC.  211 

obtained,  sub-cultures  in  test-tubes  were  made  with  all  sterile  pre- 
cautions, and  when  a  good  tube-culture  bad  been  obtained  it  was  used 
for  culture  purposes  as  required.     (Temperature,  15-20°  0.) 

No  bacterial  or  other  adventitious  growth  was  obtained  by  sowing 
from  these  successful  cultures  into  (1)  nutrient  broth,  (2)  nutrient  agar, 
(3)  glucose  agar,  and  (4)  litmus  milk,  at  room  temperature  or  at  36°C.  ; 
nor  on  the  special  medium  itself  stiffened  with  agar  ;  although  pecuUar 
rod-shaped  bodies  (10  /x  long  by  2  /x  broad)  were  detected  in  growing 
cultures  with  a  y^^th-in.  oil-immersion  lens.  Experiments  with  the 
special  medium  showed  that  when  eingle  amino  acids  were  supplied, 
histidine,  arginine,  and  leucine  gave  more  rapid,  growth  than  trypto- 
phane ;  also  that  galactose  and  fructose,  but  not  maltose,  could  be  sub- 
stituted for  glucose.  J.  E. 


p  2 


212  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 


BOTANY. 

GENERAL, 
Including-  the  Anatomy  and  Physiolog-y  of  Seed  Plants. 

Cytology, 
Including-  Cell-Contents. 

Mitochondrial  Origin  of  the  Plastids. — A.  Guilliermoxd  (Ann. 
Sci.  Nat.  (Bot.),  1919,  ser.  x.,  1,  225-47,  5  pis.,  10  figs.).  A  paper 
dealing  with  Mottier's  recent  work  in  connexion  with  the  origin  of  the 
mitochondrias  (Ann.  of  Bot,  1918,  32).  The  latter  writer  claims  to 
have  proved  that  plastids  and  mitochondrias  are  two  different  and 
distinct  constitutional  elements  of  plant-cells.  The  present  work  is 
intended  to  show  that  plastids  are  specialized  forms  of  mitochondrias. 
It  is  pointed  out  that  in  animal  cells  the  mitochondrias  have  been 
proved  to  perform  the  same  functions  as  the  plastids  of  plant-cells — 
i.e.  they  elaborate  different  nutritive  products  and  pigments.  The  writer 
also  claims  to  have  proved  conclusively  that  the  yellow  pigment  of  the 
tulip  is  formed  by  the  chondriocontes  ;  also,  that  the  epidermal  cells  of 
the  leaf  of  Iris  germanica  contain  amyloplasts  which  are  identical  in 
every  respect  with  the  chondriocontes.  It  is  admitted  that  mito- 
chondrias and  plastids  may  be  formations  of  the  same  nature  and 
significance,  but  evolving  separately  and  having  distinct  elaborative 
functions — i.e.  there  are  varieties  of  mitochondrias  each  specializied  for 
its  own  particular  function.  It  appears  preferable  to  regard  both  mito- 
chondrias and  plastids  as  different  forms  evolved  from  a  common  origin, 
and  the  writer  claims  that  investigations  made  by  himself  and  other 
botanists  fully  confirm  the  work  done  by  animal  cytologists,  and  show 
that  while  some  of  the  mitochondrias  retain  their  primitive  form,  others 
develop  into  chondrioplasts  in  the  animal  cell  and  plastids  in  the  plant 
cell.  S.  Cr. 

Structure   and   Development. 

Vegretative. 

Exudation  of  Water  by  Colocasia.— M.  G.  Flood  (Sci.  Proc.  Eotj. 
Soc.  DiiMin,  1919,  15,  505-12,  2  pis.,  1  fig.).  The  writer  has  studied 
the  leaves  of  Colocasia  antiqiwrum  in  order  to  locate  the  gland  or  tissue 
responsible  for  effecting  the  exudation  or  the  filtration  of  the  water. 
.Rapid  transfer  of  water  through  the  petiole  and  blade  is  indicated  by  the 
lacunae  in  the  petiole,  canals  in  the  leaf,  and  spaces  and  perforations  in 
the  mesophyll.  These  features,  however,  do  "not  support  the  hypo- 
thesis that  the  water  is  secreted  by  cells  in  the  tissues  of  the  apex,  or  is 
even  filtered  there."  It  was  not  possible  to  demonstrate  by  histological 
methods  the  presence  of  continuous  membranes  under  the  pores  in  the 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  213 

depressions  of  the  leaves,  but  physical  methods  were  devised  which 
showed  that  the  exuded  water  was  not  a  secretion  from  a  gland  in  the 
leaf -tip.  All  the  experiments  prove  that  there  is  no  special  tissue 
which  can  be  regarded  as  a  gland  ;  neither  is  there  any  membrane 
between  the  water-channels  and  the  depressions  for  filtering  water.  All 
the  structures  indicate  that  "  cells  lower  down  in  the  plant  are  re- 
sponsible for  the  secretion  or  filtration  of  water,  and  there  seems  no 
evidence  for  the  existence  of  special  cells  for  this  function  outside  the 
root."  S.  G. 

Reproductive. 

Reproductive  Organs  and  Phylogeny  of  the  Amentales. — P. 
VuiLLEMiN  {Ann.  Sci.  ISfat.  {Bot),  1919,  ser.  x.,  1,  139-200,  3  figs.). 
An  account  of  the  reproductive  organs  of  the  Amentales,  with  special 
reference  to  their  bearing  upon  the  phylogeny  of  this  group.  In 
describing  these  organs  the  author  employs  the  term  "  amphigonelle," 
and  points  out  that  while  a  true  inflorescence  has  numerous  mono- 
centric  axes,  the  amphigonelle  has  a  single  polycentric  axis.  Like 
the  pedicel,  the  polycentric  axis  arises  in  the  axil  of  a  leaf,  which  may  be 
unmodified,  or  bract-like,  or  elongated  into  a  leafy  stem ;  in  the  first 
case  the  axillary  shoot  is  entirely  reproductive,  and  in  the  other  cases  it 
is  partly  vegetative  and  partly  reproductive.  The  amphigonelle 
may  resemble  a  capitulum,  a  spike,  or  a  glomerulus.  In  the  Cupuliferse 
the  axis  is  oligocentric,  being  sometimes  a  true  stem  with  typical  vegeta- 
tive leaves,  as  in  Quercus  and  Fagus,  in  other  cases  functioning  as  a 
peduncle  ;  while  the  reproductive  organs  resemble  an  inflorescence  in 
which  a  vegetative  shoot  is  subordinated  to  the  reproductive  shoots. 
The  amphigonelles  enclose  sexual  organs — unisexual  in  the  lower 
Amentales,  bisexual  in  the  higher  types.  The  primitive  male  organ  is 
dichotomous,  with  two  filaments  and  two  unilocular  anthers,  but  the 
dichotomy  is  gradually  suppressed  from  below  upwards,  until  finally 
there  is  a  single  filament  bearing  a  bilocular  anther.  The  female  organs 
are  represented  by  the  nucellus,  placentas,  and  stigmas.  No  true  carpels 
have  been  found  in  the  Amentales  ;  the  ovary  is  of  the  nature  of  a  leafy 
emergence  surrounding  the  female  organs,  tbe  partitions  corresponding 
to  the  outgrowths  of  the  leaf  (e.g.  the  Juglandace^e)  or  to  prolongations 
of  the  placenta  (e.g.  the  Casuarinese  and  Betulaceae). 

The  appendages  of  the  amphigonelle  are  sepals  and  bracteoles. 
In  the  lower  groups  the  sepals  are  often  attached  to  the  stamens  or 
stigmas,  while  in  the  higher  groups  these  appendages  come  into  close 
union  with  the  organs,  and  become  the  ovary  composed  of  carpels.  In 
certain  female  amphigonelles  some  or  all  of  the  bracteoles  form  a  primi- 
tive cupule  ;  the  latter  is  well  differentiated  in  the  Cupulif er^,  but  in  the 
lower  families  of  the  Myricacese  and  Juglandaceag  it  is  very  rudimentary. 
In  tracing  the  phylogeny  of  the  Amentales  it  has  not  been  possible  to 
fix  any  direct  line  of  descent,  but  taking  into  account  numerous  indica- 
tions of  affinity,  we  have  a  system  of  short  branches  arising  one  from 
another  at  different  angles  of  divergence.  Through  the  Casuarinese  the 
Amentales  are  derived  directly  from  the  Protosperms,  the  common 
source  of  the  Gymnosperms  and  Angiosperms,  themselves  derived  from 


214  SUMMARY   OF   CURRENT  RESEARCHES  RELATING   TO 

the  Mesophytes,  which  also  give  rise  to  the  Muscineas.  The  Amentales 
show  traces  of  their  relationship  to  the  Musciuese,  and  in  some 
respects  resemble  the  Gjmnosperms,  more  especially  the  Gnetaceae. 
The  Cupuliferfe,  although  higher  than  the  Casaarinea^,  have  diverged  less 
from  the  direct  line  than  the  Myricineae  ;  the  other  families — Salicineee, 
Piperineas,  Chloranthinese,  and  Juglandaceag — start  at  different  levels 
from  the  branch  which  terminates  in  the  Myricaceae.  S.  G. 


CRYPTOGAMS. 

Pteridopliyta. 

Contribution  to  our  Knowledge  of  the  Vascular  System  of  the 
Genus  Equisetum. — Kate  Barratt  (Ann.  of  Bot.,  1920,  34,  201-35, 
2  pis.  and  figs.).  An  investigation  of  the  anatomy  of  the  sporeling 
and  the  development  of  the  vascular  system.  1.  The  sporeling  of 
E.  arvense  is  protostelic  at  its  base,  siphonostelic  where  the  vascular 
supply  of  the  secondary  axis  is  attached,  and  protostelic  again  for  a  short 
distance  below  where  the  first  whorl  of  leaves  is  attached.  2.  The  basal 
regions  of  the  succeeding  axes  of  the  young  plant  possess  a  compact 
closed  siphonostele  composed  of  short  reticulate  tracheids.  There  is 
thus  formed  a  sympodial  vascular  tube  in  which  five  or  more  axes  may 
be  concerned.  3.  The  secondary  axis  arises  endogenously  from  the 
primary  axis  below  the  level  of  the  first  leaf -whorl.  4.  The  vascular 
structure  of  an  anomalous  tuber  is  described,  in  which  carinal  canals  are 
formed  in  connexion  with  the  protoxylem,  and  these  in  the  middle 
region  of  the  tuber  are  enveloped  by  separate  endodermis.  5.  A  young 
sporeling  of  E.  limosum  is  described  showing  a  forked  primary  axis. 
The  arrangement  of  the  vascular  system  indicates  that  it  has  almost 
certainly  arisen  by  a  dichotomy.  6.  Secondary  thickening  of  the  nodes 
of  B.  arvense  and  E.  maximum  was  studied  in  the  light  of  the  develop- 
ment of  the  nodal  tracheids  ;  and  the  conclusion  was  arrived  at  that 
the  apparent  increase  in  elements,  which  has  been  attributed  to  secondary 
thickening,  is  due  to  the  enlargement  and  displacement  of  developing 
tracheids.  7.  The  vascular  structure  of  the  cones  of  E.  arvense,  E. 
maximum,  E.  paliistre,  E.  limosum,  and  E.  sylvaticum  is  described. 
The  endogenous  protoxylem  strands  are  shown  to  form  complete  and 
continuous  systems,  uninterrupted  by  nodal  tracheids,  as  is  invariably 
the  case  in  vegetative  shoots.  The  metaxylem  develops  later,  and  varies 
in  amount  and  distribution  in  the  different  species.  E.  arvense  shows 
the  greatest  amount,  and  E.  limosum  and  E.  sylvaticum  the  least.  It  is 
concluded  that  the  gaps  in  the  metaxylem  siphonostele  cannot  be 
described  as  leaf-gaps,  bearing  no  relation  to  the  sporangiophore  traces, 
but  may  be  related  to  the  mechanical  efficiency  of  the  cone.  It  is  also 
concluded  that  the  vascular  structure  of  the  cone  indicates  that  the 
sporangiophores  are  not  the  morphological  equivalent  of  leaves,  but  are 
organs  sui  generis,  and  the  axis  of  the  cone  is  undifferentiated  into  node 
and  internodes.  8.  The  general  vascular  system  of  the  plant  is  dis- 
cussed, and  it  is  concluded  that  the  general  plan  of  development  proceeds 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  215 

from  a  simple  protostele  which  opens  out  into  a  siphonoslele.  This 
shows  a  considerable  reduction  in  the  cone  by  the  development  of  large 
parenchymatous  meshes  or  longitudinal  tracks,  and  still  further  reduction 
in  the  internodes  of  vegetative  shoots.  A.  Gepp. 

Third  Contribution  to  our  Knowledge  of  the  Anatomy  of  the 
Cone  and  Fertile  Stem  of  Equisetum. — Isabel  M.  P.  Bro^vne  {Ann. 
o/Bot,  1920,  34,  237-63,  2  pis.  and  figs.).  An  account  of  the  fertile 
region  in  E.  hyemale  and  E.  giganteum.  1.  The  following  series  shows 
the  species  arranged  according  to  the  gradual  reduction  of  the  vascular 
system  in  the  cone  :  {a)  E.  arvense,  (b)  E.  hyemale,  (c)  E.  pahistre, 
(d)  E.  giganteum,  (e)  E.  maximum,  (/)  E.  Umosum.  In  («),  relatively  to 
its  size,  the  vascular  system  is  by  far  the  best  developed,  and  in  (e)  and 
(/)  by  far  the  most  reduced  ;  in  (b)  (c)  [d)  the  reduction  of  xylem  has 
proceeded  in  somewhat  different  ways,  but  on  the  whole  to  much  the 
same  degree.  2.  The  reduction  of  the  xylem  of  the  cone  is  manifested 
in  E.  hyemale  and  E.  giganteum,  as  in  the  other  species  studied,  by  the 
persistence  of  parenchymatous  meshes,  arising  vertically  above  traces 
that  have  departed,  upwards  into  more  than  one  internode,  and  by  their 
extension  laterally  above  traces  given  off  from  at  or  near  the  edge  of 
a  strand.  Both  phenomena  may  be  considered  to  be  due  to  poor 
development  of  axial  xylem  at  the  nodes  of  the  cone.  3.  Specially 
characteristic  of  E.  hyemale,  and  showing  relatively  good  development 
of  the  vascular  system,  are  the  following  points  :  \a)  the  closure  of 
parenchymatous  meshes  by  the  formation  of  additional  tracheids  at 
the  node  rather  than  by  the  oblique  course  of  the  tracheids  of  the 
branches  of  a  strand  above  the  departure  of  a  trace  ;  {]))  the  relatively 
large  number  of  parenchymatous  meshes  and  the  high  proportion 
among  these  of  meshes  of  the  first  and  second  orders.  4.  In  E.  gigan- 
teum a  relatively  high  development  of  the  xylem  of  the  cone  is  shown  : 
(a)  by  the  slightly  greater  radial  extent  of  the  xylem  in  this  species  ; 
lb)  by  the  not  infrequent  development  of  wide  internodal  tracts  of 
xylem,  involving  the  absence  of  parenchymatous  meshes  over  median 
traces  ;  (c)  by  the  fact  that  closure  of  parenchymatous  meshes  more 
often  involves  the  formation  of  additional  tracheids  than  the  oblique 
course,  and  ultimate  fusion  of  groups  of  tracheids  lying  on  either  side 
of  the  mesh  ;  and  {d)  by  the  fact  that  this  fusion  of  strands,  owing  to 
the  formation  of  additional  tracheids,  not  infrequently  occurs  con- 
siderably below  the  node.  5.  Both  in  E.  hyemale  and  E.  giganteum 
the  sporangiophores  of  successive  whorls  alternate  with  considerable 
regularity.  But  the  traces  at  their  insertion  on  the  axial  stele  do  not 
alternate  regularly  with  those  of  the  whorls  above  and  below.  In  both 
species  regular  superposition  occurs  when  parenchymatous  meshes  persist 
unnarrowed  on  either  side  of  a  trace-bearing  strand  through  two  or 
more  nodes.  This  superposition,  being  due  to  poor  development  of 
axial  xylem  at  the  nodes,  is  less  common  than  in  E.  maximum  or  in 
E.  Umosum.  Within  tiie  species  the  specimens  with  less  well-developed 
xylem  show  more  numerous  examples  of  superposition  of  traces.  6. 
The  traces  of  the  sporangiophores  of  E.  giganteum  are  the  most  massive 
yet  described  for  the  genus.     7.  The  traces  of  the  lowest  whorls  of  the 


216  SUMxMARY   OF   CURRENT   RESEARCHES   RELATING  TO 

cone  of  E.  hyemale  tend,  even  when  young,  to  be  deflected  slightly 
downwards  while  passing  outwards  through  the  cortex.  8.  In  E. 
hyemale  the  axis  is  narrower  at  the  base  than  in  the  middle  or  slightly 
above  the  middle  of  the  cone  ;  but  the  internodal  axial  strands  and 
members  in  a  whorl  are  markedly  more  numerous  at  the  base  of  the  cone. 
Consequently  the  vascular  bundles  are  much  closer  to  one  another  in  the 
annular  region  than  in  the  wider  parts  of  the  axis  of  the  cone.  This 
probably  partly  accounts  for  the  relatively  high  number  of  meshes 
closed  at  or  near  the  level  of  insertion  of  the  annulus.  Above  the  latter 
numerous  fresh  meshes  arise.  9.  In  E.  giganteum  the  annulus  is 
normally  sporangiferous,  the  sporangia  being  attached  by  their  upper 
ends  to  the  free  incurved  edge  of  the  annulus.  A  vascular  strand  runs 
to  the  point  of  insertion  of  each  sporangium.  The  number  of  the  latter 
bears  no  constant  relation  to  that  of  the  strands  in  the  axis  or  the  lobes 
of  the  annulus.  The  annular  bundles  may  remain  free  from  or  be 
connected  with  the  axial  stele  ;  they  may  branch  or  remain  unbranched. 
10.  E.  giganteum  differs  from  the  other  species  studied  in  that  no  fresh 
parenchymatous  meshes  arise  above  the  annulus.  The  nodal  nature  of 
the  axis  at  the  level  of  the  insertion  of  the  latter  is,  however,  supported 
by  the  analogy  with  other  species,  and  by  the  closure  of  some  parenchy- 
matous meshes  in  this  region.  11.  The  sporangiferous  annulus  is 
regarded  as  derivative  in  the  genus  Equisetum,  and  the  reasons  for  this 
view  are  briefly  examined.  12.  In  E.  giganteum  the  uppermost  vegeta- 
tive node  of  the  fertile  branch  shows  no  persistent  diaphragm.    A.  G. 

Phylogenetic  Considerations  on  the  Internodal  Vascular  Strands 
of  Equisetum.— Isabel  M.  P.  Browne  {New  Phytologist,  1920,  19, 
11-25,  7  figs.).  A  discussion  of  the  structure  and  nature  of  these 
strands,  the  treatment  of  which  is  somewhat  meagre  in  the  text-books. 
The  question  of  which  is  the  most  primitive  type  of  internodal  bundle 
in  Equisetiim  is  considered,  as  also  the  direction  of  lignification  of  the 
lateral  groups  of  metaxylem.  '  A.  G. 

Studies  in  the  New  Zealand  Species  of  the  Genus  Lycopodium : 
Part  I. — J.  E.  HOLLOWAY  {Trans.  Proc.  New  Zealand  Inst.,  1916, 
48,  253-303,  2  pis.  and  figs.).  A  detailed  account  of  the  New  Zealand 
species,  including  the  occurrence  and  habit  of  the  mature  plant,  the 
occurrence  and  structure  of  the  prothallus,  the  nature  of  the  dependence 
of  the  young  plant  upon  the  prothallus,  and  the  vascular  anatomy  of 
both  the  "seedling"  and  the  full-grown  plant.  The  results  are  as 
follows  : — Prothalliof  seven  species  are  described  and  are  grouped  under 
four  types  :  (1)  Phlegmaria  (L.  Billardieri)  ;  (2)  Cermia  (L.  lateraJe, 
L.  ramulosum) ;  (3)  Clavata  {L.  voluhile,  L.fastigiatiim)  ;  (4)  Complanata 
(L.  scariosum)  \  and  it  is  presumed  that  L.  densum  will  be  added  to 
one  or  other  of  the  latter  two  types.  A  large  foot  is  characteristic  of 
the  embryo  in  L.  voluldle,  L.  densum^  L.  fastigiatnm,  L.  scariosum, 
while  in  case  of  L.  latcrale  and  L.  ramidosnm  there  is  an  exceptionally 
large  and  long-lived  protocorm.  This  latter  is  presumed  to  be  merely  a 
physiological  adaptation.  As  to  the  vascular  cylinder  a  stellate  or  radial 
configuration  is  characteristic  in  L.  Selago,  L.  BiUardieri^  and  L.  varium  ; 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,   ETC.  217 

a  mixed  type  in  L.  cernuuni,  L.  laterale,  and  L.-  Drummondii  ;  and  a 
parallel  type  in  L.  volubile,  Z.densum,  L.  fastir/iatum,  and  L.  scariosum. 
The  radial  or  stellate  type  is  regarded  as  being  the  more  primitive. 

The  author  discusses  the  taxonomic  sections  of  Lycoioodium  adopted 
by  Pritzel  and  finds  them  to  agree,  in  the  main,  with  the  chief  char- 
acters of  both  the  sexual  and  the  asexual  generations  of  the  various 
species.  He  also  summarizes  the  views  of  writers  as  to  whether  these 
main  sections  are  more  or  less  nearly  inter-related  or  are  widely  separated, 
and  finds  that  the  inter-relationship  view  is  more  w^idely  held  than  is 
the  other.  And  from  his  own  studies  he  believes  that  the  Selago  section 
contains  the  most  primitive  members  of  the  genus,  and  that  from  it 
have  been  derived  the  Phlegmaria  and  Glavata  sections,  but  that  the 
exact  relation  of  the  Cernua  and  Inundata  sections  is  difficult  to  gauge. 
The  type  of  prothallus  in  L.  cernuum  is  commonly  regarded  as  primitive 
for  the  genus  ;  but  other  characters  of  the  species  seem  to  be  highly 
specialized.  Hence  Cernua  and  Inundata  are  best  regarded  as  groups 
parallel  with  Selago.  A.  G. 

Studies  in  the  New  Zealand  Species  of  the  Genus  Lycopodium  : 
Part  11.  Methods  of  Vegetative  Reproduction. — J.  E.  Holloway 
{Trans.  Proc.  New  Zealand  Inst.,  1917,  49,  80-93,  2  pis.  and  figs.).  A 
description  of  the  methods  of  vegetative  propagation  observed  in  New 
Zealand  species.  These  are — (1)  Vegetative  propagation  of  the  pro- 
thallus ;  (2)  isolation  of  portions  of  lateral  branches  .or  of  the  main 
axes  of  the  plagiotropic  species ;  (3)  bulbils  on  adult  plants  ;  (4)  root- 
tubercles  ;  (5)  gemmae  produced  from  cortical  cells  of  old  roots  ; 
(6)  bulbils  on  detached  leaves ;  (7)  vegetative  reproduction  of  the  pro- 
tocormous  rhizome.  In  no  case  in  L.  cernuum,  L.  laterale  and  L. 
ramulosuni  has  the  author  ever  noticed  fungal  hyph^  in  the  cells  of  the 
protocorm.  A  store-tuber  comparable  to  the  protocorm  is  sometimes 
found  on  detached  leaves  of  L.  ramulosum  in  relation  to  an  adventitious 
bud  ;  also  the  adventitious  plantlets  derived  from  cortical  cells  of  roots 
begin  as  tubers,  as  also  do  those  budded  off  from  the  protocormous 
rhizome  of  L.  ramulosum  ;  and  these  cases  are  comparable  with  the 
annually  produced  tuber  in  Phylloglossum,  which  initiates  a  new  plant. 

A.  a. 

studies  in  the  New  Zealand  Species  of  the  Genus  Lycopodium  : 
Part  III.  The  Plasticity  of  the  Species. — J.  E.  Holloway  {Trans. 
Proc.  New  Zealand  Inst.,  1919,  51,  161-216,  6  pis.  and  figs.).  An 
account  of  the  variations  observed  by  the  author  in  the  main  characters 
of  the  Xew  Zealand  species  of  Lycopodium.  The  five  main  characters 
studied  are — (1)  Habit  of  growth  and  external  form  ;  (2)  stem-anatomy  ; 
(3)  nature  of  fertile  region  ;  (4)  form  and  structure  of  prothallus ; 
(5)  form  of  young  plantlet.  From  these  five  points  of  view  the  vari- 
ations of  the  eleven  known  species  are  investigated  in  detail  at  some 
length  under  their  sectional  headings — (1)  Selago  and  Phlegmaria  ; 
(2)  Inundata  and  Cernua ;  (3)  Clavata ;  and  it  is  shown  that  the  species 
are  in  a  condition  of  considerable  plasticity.  The  evidence  obtained  is 
further  digested  in  a  lengthy  summary.  A.  G-. 


218  SUMMARY   OF   CURKENT   RESEAP.CHES   RELATING  TO 

Prothallus  and  Young  Plant  of  Tmesipteris.— J.  E.  Holloway 
{Trans.  Proc.  New  Zealand  Inst.,  1918,  50,  1-44,  3  pis.  and  figs.).  The 
subject  is  treated  in  chapters,  as  follows  : — Occurrence  and  habit ; 
general  form  and  structure  of  the  prothallus ;  the  distribution  of  the 
sexual  organs ;  development  of  the  sexual  organs ;  the  development  of 
the  embryo ;  development  of  the  young  plant ;  development  of  the 
vascular  anatomy  ;  comparative  remarks.  The  author  compares  his 
results  with  those  of  A.  A.  Lawson,  and  finds  himself  in  agreement  in 
many  particulars — as  to  the  subterranean  saprophytic  prothallus,  its 
brown  colour  and  covering  of  i-hizoids  ;  its  cylindric  form,  and  its 
branching ;  its  endophytic  fungus ;  the  distribution  of  the  antheridia 
and  archegonia  scattered  all  over  the  surface;  the  structure  of  the 
mature  sexual  organs ;  the  embryo  borne  on  a  prothallial  protuberance  ; 
the  peculiar  lobular  development  of  the  epibasal  portion  of  the  embryo. 
But  he  finds  Lawson's  prothalli  to  be  much  smaller  and  tender,  with 
twisted  rhizoids,  with  a  different  distribution  of  the  endophytic  fungus, 
and  with  the  prothallium  lobes  pointed.  The  explanation  may  be  that 
under  T.  tannensis  two  species  are  included,  Holloway's  material  being 
of  the  form  known  as  T.  lanceolata,  which  differs  from  this  type  in  both 
habit  and  histological  details.  The  author  points  out  how^  the  prothallus 
of  Tmesipteris  differs  from  those  of  Ophioglossace^e  and  Lycopodiacese ; 
and  cites  the  evidence  for  the  near  affinity  of  Tmesipteris  and  Psilotum., 
and  for  the  connexion  of  these  Psilotace^e  with  certain  of  the  fossil 
Sphenophyllales.  He  discusses  the  question  as  to  whether  the  Psilotacese 
are  to  be  regarded  as  primitive,  or  as  the  result  of  reduction,  or  as  being 
recent  adaptations ;  he  draws  an  analogy  from  the  Equisetace^e  and  the 
Lycopodiaceai,  and  gives  a  resume  of  what  is  known  of  Rhijnia  Gwynne- 
Vaughani,  referred  by  Kidston  and  Lang. to  a  new  class,  Psilophy tales  ; 
and  he  concludes  that  the  Psilotace^e  are  to  be  regarded  as  of  a  primi- 
tive character.  In  a  postscript  he  points  out  how^  his  researches  correspond 
more  closely  with  Lawson's  second  account  of  Tmesipteris  than  with  the 
first.  A.  G. 

Cantheliophorus,  Bassler  :  New  Records  of  Sigillariostrobus 
(Mazocarpon).— M.  Benson  {Ann.  of  JBot.,  1920,  34,  135-7).  Some 
criticisms  of  Bassler's  recent  paper  on  a  Sporangiophoric  Lepidophyte 
from  the  Carboniferous — namely,  Cantheliophorus.  The  view  is  put 
forward  that  the  material  may  be  referred  to  Sigillariostrolus  on  the 
ground  of — (1)  The  general  occurrence  free  from  the  axis  of  tlie  cone; 
(2)  the  form  of  the  sporange  and  the  bract ;  (3)  the  occurrence  of  lateral 
lines,  some  of  which  suggest  the  vascular  pedicel  and  some  the  "  lateral 
lamella  "  of  Mazocarpon  ;  (-l)  the  indication  of  a  bulky  sporange  wall  and 
the  relatively  small  spore-bearing  region.  Most  of  Bassler's  specimens 
are  to  be  welcomed  as  further  examples  of  Sigillarian  microsporophylls, 
of  which  previously  only  one  incrustation  record  was  known.      A.  G. 

Pit-closing  Membrane  in  Ophioglossaceae. — Gertrude  Wright 
{Bot.  Gaz.,  1920,  69,  237-17,  2  pis.  and  figs.).  An  account  of  some 
investigations  of  Helminthostachys  zeylanica,  Ophioglossum  vulgatum  and 
Botrychium  obliquwn,  with  a  view  to  determining  the  presence  or  absence 


ZOOLOGY   AND    BOTANY,   MICKOSCOPY,    ETC.  219 

of  a  pit-closing  membrane — a  matter  of  dispute  in  all  vascular  Cryptogams. 
Halft  and  Bancroft  have  proved  the  presence  of  the  membrane,  but  did 
not  study  the  Ophioglossacea?.  This  omission  the  present  author  makes 
good  by  figures  and  description.  Only  with  the  greatest  difficulty  could 
the  membrane  be  demonstrated  clearly  in  Helminthostachys,  but  more 
easily  in  Ophioglossum  and  Botrychium.  The  methods  of  staining  are 
explained ;  and  the  torus  or  thickening  of  the  membrane  is  discussed. 

A.  G. 

Some  Impressions  of  Pteris  aquilina  L.  in  the  Tufa  of  the  Villa 
Torlonia  at  Frascati. — R.  Meli  {Atti  Pontif,  Accad,  Romana  del 
Nuovi  LinceL,  1919,  71,  49-64).  A  resume  of  papers  previously  pub- 
lished upon  this  subject,  with  criticisms  and  additional  information .  The 
living  ferns  were  buried  in  position  by  a  fall  of  volcanic  dust  and  cinders, 
thus  diifering  from  other  instances,  as  from  the  Valley  of  the  Tiber  and 
of  the  Sacco,  and  from  Onano  in  the  Vulsini,  where  the  impressions, 
mingled  with  those  of  other  plants,  are  mostly  disposed  horizontally  in 
the  tufa.  A.  G. 

Norfolk  Island  Species  of  Pteris.— R.  M.  Laing  {Trans.  Proc.  New 
Zealand  List.,  191G,  48,  229-37,  figs.).  A  revision  based  on  good  and 
abundant  material,  and  an  attempt  to  identify  with  certainty  Endlicher's 
species,  described  in  1833.  The  results  are  as  follows  : — A.  Veins 
forked — (1)  Pteridium  esmdentum  Cockayne  {Pteris  escidenta  Forst.  f.) ; 
(2)  Pteris  tremida  R.  Br.,  P.  Baueriana  Dies.) ;  (3)  P.  Kingiana  Endl. ; 
(4)  P.  biaurifa  L.  var.  quadriaurita  Retz.  (?  P.  TrattinicJciana  Endl). 
B.  Veins  anastomosing— (5)  P.  comans  Forst.  f.  (?  P .  ZaMhruckneriana 
Endl);  (6)  P.  Brunoniana  Endl.;  (7)  Histiopteris  {Pteris)  incisa 
(Thunb.)  J.  Sm.  The  author  contends  that  P.  Brunoniana  is  a  good 
species.     The  text-figures  are  clear  and  accurate.  A.  G. 


Bryophyta. 

Spermatogenesis  in  Blasia. — Lester  W.  Sharp  {Bot.  Gaz.,  1920, 
69,  258-68,  1  pL).  An  account  of  spermatogenesis  observed  in  Blasia 
pusilla  collected  near  Chicago.  1.  Centrosomes  are  present  at  ail  stages 
of  the  mitosis  which  differentiates  the  androcytes,  and  in  the  androcytes 
they  persist  and  function  as  the  blepharoplasts.  2.  In  the  transforma- 
tion of  the  androcyte  into  the  spermatozoid,  the  blepharoplast  divides 
repeatedly  by  simple  fission,  forming  a  number  of  distinct  granules 
which  coalesce  to  form  a  short  lumpy  rod.  This  rod  elongates  and 
becomes  a  more  uniform  thread  bearing  two  cilia,  while  the  nucleus  also 
elongates  in  intimate  union  with  it  to  form  the  body  of  the  spermatozoid. 
The  present  instance  is  the  first  in  which  blepharoplast  fragmentation 
has  been  reported  in  a  Bryophyte.  3.  It  is  possible  that  the  fission  of 
the  Blasia  blepharoplast,  and  therefore  the  more  complex  fragmentation 
of  the  blepharoplasts  of  Eqtnseium,  Marsdia,  and  the  Cycads,  may  be 
homologized  with  the  normal  division  exhibited  by  ordinary  centro- 
somes. A.  G. 


220  SUMMARY    OF   CQKRENT    RESEARCHES    RELATING   TO 

Life-history  of  Fossombronia  cristula.— Arthur  W.  Haupt  {Bot. 
Gaz.,  1920,  69,  318-31,  6  pis.  and  fig.)-  This  paper  is  summarized  as 
follows : — 1.  The  vegetative  bodv  of  F.  cristula  consists  of  a  minute, 
creeping,  rather  profusely  branched  thallus  which  bears  genuine  leaves 
in  two  dorsal  rows.  2.  The  apical  cell  is  dolabrate.  Branching  is 
strictly  apical.  3.  The  plants  are  monoecious,  the  sex  organs  occurring 
in  the  axes  of  the  leaves,  xintheridia  and  archegonia  may  occur  in  the 
same  leaf  axis,  and  there  is  no  time  relation  in  the  order  of  their  appear- 
ance. They  originate  from  the  immediate  segments  of  the  apical  cell, 
and  their  development  is  strictly  acropetal.  4.  The  antheridia  develop 
according  to  the  usual  method  found  among  the  anacrogynous  Junger- 
manniales.  Variations  occur  in  the  order  of  appearance  of  the  walls  in 
the  primary  stalk  cell.  5.  Until  the  appearance  of  the  first  vertical 
wall  young  archegonia  cannot  be  distinguished  from  young  antheridia. 
The  first  transverse  division  in  the  archegonium  initial  separates  tho 
stalk  cell  from  the  archegonium  proper,  and  subsequent  development 
follows  the  usual  Jungermanniales  type.  The  cover  cell  is  inactive, 
six  to  eight  neck  canal  cells  are  formed,  and  the  venter  is  two  cells  thick 
before  fertilization.  The  archegonium  is  of  an  advanced  type.  6.  The 
early  divisions  of  the  embryo  are  transverse,  both  halves  of  the  fertilized 
Qgg  contributing  to  the  development  of  the  foot,  seta  and  capsule.  A 
calyptra,  three  to  four  cells  in  thickness,  is  formed.  7.  The  sporogenous 
tissue  is  differentiated  rather  early  in  the  history  of  the  sporophyte. 
The  elaters  are  rudimentary,  and  each  is  homologous  with  a  single  spore 
mother-cell,  not  with  a  row  of  them.     8.  The  sporophyte  is  primitive. 

A.  G. 

Studies  in  some  East  Indian  Hepaticae :  Calohryum  Blumei 
N.  ab  E.— D.  H.  Campbell  {Ann.  of  Bot.,  1920,  34,  1-12,  1  pi.  and 
figs.).  An  account  of  the  morphology  and  reproduction  of  Oalohnjian. 
The  conclusion  is  reached  that  Calobryum  and  Haplomitrium,  although 
differing  in  certain  particulars  (e.g.  the  position  of  the  archegonia),  are 
closely  related  and  constitute  a  special  family,  Calobryaceae  ;  but  their 
relationships  with  the  other  Hepaticae  are  very  obscure.  Goebel  ranges 
them  in  a  series  independent  of  the  other  foliose  Hepaticae.  The 
development  of  leaves  has  evidently  occurred  in  several  quite  independent 
series  among  the  Liverworts  ;  and  the  Calobryacese  probably  represent 
the  end  of  such  a  series,  and  are  not  closely  related  to  the  foliose  Junger- 
manniales. Whether  they  are  most  nearly  related  to  the  anacrogynous 
Jungermanniales,  or  have  been  derived  from  forms  more  like  the 
Sphasrocarpales,  is  a  question.  The  character  of  the  sporophyte,  with 
its  single  layer  of  wall-cells,  would  suggest  the  latter  hypothesis.  The 
author  suggests  the  establishment  of  a  special  order,  Calobryales, 
co-ordinate  with  the  SphiL^ocarpales,  Marchantiales  and  Jungermanniales. 
The  present  distribution  of  Calobryum  suggests  that  the  genus  was 
formerly  more  generally  distributed.  A.  G. 

Gemmse  of  Tortula  mutica  Lindb. — B.  Muriel  Bristol  {Ann.  of 
Bot.,  1920,  34,  137-9,  figs.).  Gemma}  have  been  recorded  for  only  17 
out  of  the  620  odd  species  recorded  in  Braithwaite's   "  British  Moss 


ZOOLOGY    AND   BOTANY.   MICROSCOPY,    ETC.  221 

Flora."  The  gemmae  of  a  specimen  of  Tortula  mutica  from  North  Wales 
are  now  described.  They  were  found  scattered  over  the  upper  surface  of 
the  leaves,  and  also  rarely  on  the  protonema.  They  consist  usually  of 
two  or  four  cells,  bounded  by  thick,  reddish-brown  walls  ;  they  are  easily 
detached  and  are  capable  of  resting  ungerminated.  In  an  allied  specie?, 
T.  impillosa,  gernm^  occur  only  on  the  upper  part  of  the  thickened  leaf- 
costa.  A.  G. 

Rhaphidostegium  coespitosum  (Sw.)  and  its  Affinities.— H.  N. 
Dixon  {Joum.  of  Bot.,  1020,  58,  81-9).  An  account  of  the  investi- 
gation of  numerous  original  specimens  collected  in  various  countries,  and 
described  as  species  by  a  large  number  of  authors.  It  is  found  to  be 
quite  impossible  to  maintain  them  as  distinct  species ;  they  show  them- 
selves inevitably  to  be  but  forms  of  one  species  widely  spread  throughout 
the  tropical  and  subtropical  regions  of  the  southern  hemisphere,  and 
extending  also  into  the  temperate  zone.  The  oldest  type  is  Hypnum 
coespitosum  Swartz  (Prodomus,  p.  142  [1788]),  placed  in /?^«/;M^os^e^mm 
by  Jaeger,  and  now  furnished  with  a  synonymy  running  to  nearly  three 
score  names.  This  is  one  of  the  most  extensive  and  satisfactory  reduc- 
tions of  unnecessary  and  redundant  species  that  has  yet  been  achieved 
in  bryology.  A.  G. 

Thallophyta. 

Algae. 

Attempt  to  explain  the  Colourless  Series  of  Flagellates. — A. 
Pascher  {Ber,  Deutsch.  Bot.  GeselL,  1916,  34,  410-7  ;  see  also  Bot 
Centralbl,  1918,  137,  20-22).  A  synopsis  of  the  lines  followed  by 
the  author  in  his  treatment  of  the  fresh-water  flagellates  in  Rabenhorst's 
"  Kryptogamen  Flora."  He  considers  that  the  colourless  forms  which 
occur  in  every  series  of  coloured  flagellates  are  a  secondary  development 
of  the  coloured  forms.  In  every  colourless  series  there  are  genera  and 
species  which  stand  in  the  closest  relation  to  the  coloured  ones,  but  with 
a  reduced  chromatophore  apparatus,  and  having  a  saprophytic,  parasitic, 
and  animal  existence,  thereby  declaring  their  derived  character.  Inter- 
mediate stages  are  found  ;  and  it  is  possible  artificially  to  produce 
colourless  from  coloured  forms.  In  all  the  coloured  series  animal 
nutrition  occurs  secondarily,  and  leads  direct  in  certain  forms  to  a  per- 
manent rhizopodial  organization.  As  opposed  to  the  coloured  series  of 
flagellates,  there  are  three  series  of 'colourless  forms,  with  characters 
which,  among  coloured  flagellates,  are  only  found  in  derived  forms.  The 
author  considers  Protomastiginse  and  Pantostomatin^  to  be  series  of 
flagellates  which  have  been  classed  together  on  quite  secondary  charac- 
ters, and  therefore  represent  wholly  artificial,  heterogeneous,  polyphyletic 
groups.  The  component  species  are  apochromatic  and  apoplastid  forms 
of  the  most  diverse  coloured  species,  and  in  some  cases  are  so  obviously 
related  that  the  coloured  and  colourless  should  not  be  separated.  The 
author  only  continues  the  present  artificial  classification  for  the  sake  of 
convenience.  He  gives  an  enumeration  of  the  coloured  and  colourless 
series.  E.  S.  Gepp. 


222      SUJMMAKY  OF  CURRENT  RESEARCHES  RELATING  TO 

Peridinese  of  New  South  Wales.— G^.  I.  Playfair  (Proc.  Linnean 
Soc.  New  South  Wales,  1920,  44,  793-818,  3  plates  and  figs.).  An 
account  of  such  Peridineae  as  have  been  found  in  gatherings  of  fresh- 
water algte  from  Sydney  and  Lismore,  involving  a  revision  of  the 
plankton  of  the  Sidney  Water  Supply.  Sixteen  species  (two  are  new) 
and  twenty-three  varieties  (many  are  new)  are  recorded  ;  most  of  them 
are  figured  and  described.  Some  introductory  remarks  on  grouping  of 
forms,  polymorphism  and  structure  are  provided.  A.  Gepp. 

Some  Species  of  Fresh-water  Plankton  from  Gandia  (Valencia). 
— Luis  Pardo  {Boletin  R.  Soc.  Espanola  Hist.  Nat.  Madrid,  1920,  20, 
125-9).  An  account  of  some  algae  collected  at  Gandia  in  November, 
including  an  Oscillator ia,  three  Conjugatas,  a  desmid,  twelve  diatoms,  and 
a  flagellate,  with  remarks  on  their  periodicity  and  requirements.  A.  G. 

Lake  of  Segrino. — E.  Corti  (Nuova  Notarisia,  1920,  31,  161-6). 
This  note  on  lacustrine  biology  contains  a  list  of  phytoplankton  collected 
during  spring  and  summer  months  in  fine  weather  from  Lake  Segrino, 
at  the  mouth  of  the  Assina  Valley,  in  Upper  Brianza,  south  of  Lake 
Como.  The  lake  has  no  affluent  streams,  and  is  fed  by  springs,  only  one 
of  which  is  visible  from  the  bank.  The  phytoplankton  consists  of 
eight  Schizophyceai,  three  Dinoflagellat^,  five  Chlorophycese,  seven 
Desmidie^e,  and  six  Diatomese.  Quantitatively  it  is  much  less  than  the 
zooplankton,  qualitatively  the  contrary  is  the  case.  In  the  neighbour- 
ing lakes  of  Pusiano  and  Alserio  the  animal  surpasses  the  vegetable 
plankton  ;  in  take  Como  the  phytoplankton  is  quantitatively  superior. 

E.  s.  a, 

Campbellosphaera,  a  New  Genus  of  the  Volvocaceae. — Walter 
R.  Shaw  {Philippine  Journ.  Sci.,  1919,  15,  493-520,  3  pis.  and  fig.). 
An  account  of  a  new  genus  of  Volvocese,  Camphellosphsera  {C.  ohversa), 
■collected  near  Manila.  It  is  described  in  detail  and  figured  by  photo- 
micrographs. The  most  peculiar  character  of  the  genus  is  the  migration 
of  gonidia,  formed  early  in  the  development  of  the  embryo,  from  the 
outside  to  the  inside  of  the  embryo  through  the  phialopore.  The 
gonidia  become  very  large  before  dividing.  The  somatic  protoplasts 
lack  protoplasmic  connecting  fibres.  The  life-history  is  described  from 
a  series  of  specimens,  showing  the  salient  features  of  asexual  and  sexual 
reproduction.  The  sexual  coenobia  are  monoecious.  Comparison  is 
made  with  Volvox  and  closely  allied  genera,  involving  some  revision  of 
synonymy.  V.  aureus  Ehrenb.  (1838)  is  reported  to  have  been  collected 
in  California  in  1896,  and  to  agree  with  Klein's  ample  descriptions 
(1889-90).  The  relationships  of  the  Volvoceae  are  displayed  in  a 
diagram.  A.  G. 

Botrydium  granulatum. — C.  Janet  {Surle  Botrydium  granulatum. 
Limoges  :  Libraire  Ducourtieux  et  Gout,  1918,  6  pp.,  1  pi.).  An  account 
of  the  life-history  of  this  alga.  B.  (franidatum  generally  occurs  in  the 
form  of  vesicles,  either  much  elongated  or  pyriform,  arising  from  the 
development  of  a  protoplastid  which  maybe  either  : — 1.  A  purely  vege- 
tative  cell,   developed   precociously  on  the   individual   from  which  it 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  223 

springs  ;  after  the  collapse  of  the  parent  this  cell  is  cast  off  like  a 
propagule.  2.  An  asexual  planospore  which  comes  to  rest,  develops  a 
membrane,  and  undergoes  a  certain  period  of  rest.  3.  A  zygote,  as  yet 
unobserved  by  the  author,  but  of  undoubted  existence.  Each  of  these 
three  varieties  of  cell  develops. first  into  a  small  vesicle  here  described  in 
detail,  a  syncytial  blastea  formed  of  juxtaposed  plastids,  and  clothed 
with  a  general  cuticle.  This  blastea  is  the  faithful  representation  of  an 
ancestral  primitive  stage.  It  throws  out,  above,  a  tube  rich  in  deeply- 
coloured  chromatophores  ;  and,  below,  a  rhizoid  containing  nuclei  and 
chromatophores,  which  at  once  lose  their  colour.  The  aerial  tube  forms 
a  vesicle,  of  which  the  author  defines  three  kinds,  according  to  the 
nature  of  the  cells  which  they  produce.  The  development  of  each  is 
described  in  detail.  The  essential  productiou  of  the  first  kind  is  a 
number  of  small  cells  surrounded  with  a  cellulose  cuticle,  which  after  the 
bursting  of  the  mother-cell  are  disseminated  by  rain  and  germinate.  In 
the  second  kind  asexual  planospores  are  produced  which,  after  escaping 
from  the  burst  mother-cell,  have  a  short  period  of  activity,  and  then 
settle  down  and  germinate  in  the  same  way  as  the  cells  of  the  first  kind. 
The  third  kind  of  vesicle  produces  a  "  gametangium,"  homologous  with 
the  oogonium  and  spermogonium  of  Fums.  The  author  has  observed 
all  the  stages  of  development  except  the  emission  of  the  flagella  of  the 
gametai,  and  their  subsequent  movement  and  coalescence.  In  a  diagram 
are  sketched  out  the  various  aspects  of  the  ontogenesis  of  the  plant. 

E.  S.  G. 

Algological  Notes.  XXV.-XXIX.— N.  Wille  {Nyt  Mag.  Natur- 
videnskah.  Christiania,  1918,  56,  61,  2  pis.).  The  first  of  these  notes, 
No.  XX Y.  of  the  series,  deals  with  variability  in  the  genus  Scenedesmus 
Meyen.  The  author  discusses  critically  the  work  of  former  authors, 
and  emphasizes  the  importance  of  wide  views  in  regard  to  the  occur- 
rence of  variation.  He  describes  the  germination  of  aplanospores  in 
S.  hijugatus  Klitz.,  the  stages  of  which  vary  greatly  from  the  normal 
form.  These  stages  must  not,  however,  be  regarded  as  constituting 
polymorphism;  nor  may  also  the  aberrant  forms  produced  under  adverse 
conditions.  The  vegetative  forms  of  S.  obliquus  Klitz.  and  S.  hijugatus 
respectively  are  described.  The  former  was  found  varying  in  the 
number  of  its  component  cells  from  one  to  eight,  four  and  eight  being 
the  most  common.  In  S.  hijugatus  the  same  variation  occurred,  but 
the  numbers  other  than  four  and  eight  were  much  more  rarely  found. 
In  Note  XX YI.  the  germination  of  the  aplanospores  in  the  genus 
Ccelastrum  Nag.  is  described.  No.  XXYII.  gives  a  list  of  the  fresh- 
water alg^e  of  Beeren  Island,  containing  fifty-five  species  and  varieties 
of  Chlorophycese  and  Myxophyceee,  sixteen  of  which  are  not  yet  recorded 
from  Spitzbergen.  No.  XXYIII. :  The  name  of  Lynghya  ejyiphytica 
Wille,  a  marine  species,  is  changed  to  L.  Willei  Setchell  &  Gardner, 
the  former  specific  name  having  been  previously  used  in  the  genus  for 
a  fresh-water  species.  In  Note  XXIX.  the  author  continues  his  studies 
in  Agardh's  "  Herbarium,"  interrupted  since  1913.  Haematococcus  san- 
guineus proves  to  be  Gloeoca'psa  sanguinea  Kiitz.  Meneghini's  specimens 
of   Microcystis   bullosa   (Kiitz.)  Menegh.   and   M.  gelatinosa  jVIenegh. 


224  SUMMARY   OF   CUERENT   RESEARCHES   RELATING   TO 

were  studied,  with  the  result  that  both  of  them,  together  with  PalmeUa 
bullosa  Kiitz.,  Olcecapsa  gelatinosa  Kiitz.,  Aphanothece  bullosa  Rabh., 
and  Glaucocystis  Nostochinearum  Itzigs.  var.  minor  Hansg.,  were  found 
to  be  synonyms  of  Glaucocystis  hullosa  (Kiitz.)  Wille.  Aphanocapsa 
muscicola  (Menegh.)  Wille  was  found  to  include  as  synonyms  :  Cocco- 
chloris  muscicola  Menegh.,  G.  parietina  Menegh.,  PalmeUa  muscicola 
Kiitz.,  P. parietina  Nag.,  Aphanocapsa  parietina  Niig.  &  Thuret  in  Wittr.  & 
Xordst.  alg.  exs.  Xo.  1547,  A.  virescens  Rabh.  &  A.  Forti.  A  study  of 
original  material  of  PalmeUa  alpicola  Lyngb.  shows  that  it  is  Gkeocapsa 
magma  Kiitz.,  and  both  equal  G.  montana  Wille.  Chroococcus  paUidus 
Nag.  is  C.  aurantius  Wille.  PalmeUa  hyalina  is  Tetraspora  bullosa 
Kiitz.  PalmeUa  minuta  Ag.,  with  five  other  species,  is  Tetraspora 
explanata  Ag.  Proiococcus  natans  Ag.  proves  to  be  the  germinating 
zoospores  of  a  filamentous  alga,  probably  Stigeoclonium  tenue  (Ag.) 
Rabh.  var.  uniformis  (Ag.)  Kiitz.  ^  E.  S.  O. 

New  Species  of  Uronema  from  India. — ^.ItMno^^  {Ann.of  Bot., 
1920,  34,  95-8,  figs.).  Description  of  Uronema  indicum,  found  in  a 
dirty  drain  at  Lahore,  India.  It  differs  from  U.  elongatum  in  being 
larger,  in  the  chloroplast  running  the  whole  length  of  the  cell,  and  in 
the  cells  being  usually  broader  than  long.  A.  Gr. 

Alga-Flora  of  some  Desiccated  English  Soils :  an  Important 
Factor  in  Soil  Biology. — B.  Muriel  Bristol  {Ann.  of  Bot.,  1920, 
34,  :>5-80,  1  pi.  and  figs.).  The  results  of  the  investigation  of  forty- 
four  samples  of  soil  from  widely  separated  localities.  The  material  was 
studied  by  means  of  water-cultures ;  and  it  was  found  that  there  is  a 
widely  distributed  ecological  plant-formation  in  cultivated  soils  consist- 
ing of  moss-protonema  and  alga3.  The  most  important  alg^  in  this 
formation  are  :  Hantzschia  amphioxys  (Ehr.)  Grun.,  Trochiscia  aspera 
(Reinsch)  Hansg.,  CIdorococcum  humicola  (Naeg.)  Rabenh.,  Bumilleria 
exilis  Klebs,  and  to  a  less  degree  Ulothrix  subtilis  Kiitz.  var.  variabilis 
(Kiitz.)  Kirchn.  Other  species  of  typical  soil-algte  occurring  somewhat 
less  frequently  give  rise  to  smaller  plant-associations  within  this  formation. 
In  all,  G4  species  and  varieties  were  found — 20  Bacillariet\3,  24  Myxo- 
phyceaj,  and  20  Chlorophyceas.  The  soil-samples  had  all  been  subjected 
to  complete  desiccation  for  4  to  2G  weeks  before  being  placed  in  the 
cultures ;  hence  those  species  could  be  expected  to  withstand  any  period 
of  drought  that  might  occur  naturally.  It  seems  likely  that  this  ex- 
tensive algal  formation  must  be  of  considerable  economic  importance  in 
the  biology  of  the  soil.  Six  new  species  or  varieties  are  described,  16 
species  already  known  are  newly  recorded  for  the  British  Islands,  and  a 
number  of  new  or  interesting  stages  are  depicted  in  the  life-histories  of 
certain  species  already  known,  especially  in  connexion  with  the  germina- 
tion of  the  spores  of  some  blue-green  alg;i3.  The  final  section  of  the  paper 
contains  a  short  account  of  each  of  the  species  found  in  the  cultures. 
Further,  in  three  tables  are  displayed  the  botanical  analyses  of  the  various 
samples  of  soil.  A.  G. 

Roya  anglica  G.  S.  West,  a  new  Desmid  ;  with  an  Emended 
Description  of  the  Genus  Roya. — AVilliam  J.  Hodgetts  {Jo urn.  of 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  225 

Bot.,  1920,  58,  G5-9).  A  discussion  of  the  distinguishing  characters 
of  the  genus  Roija  by  which  it  can  he  separated  from  Glosterlum.  These 
are  mainly  two  : — (1)  The  simple  structureless  nature  of  the  cell- wall  ; 
and  (2)  the  fact  that  division  of  the  chloroplast  into  halves  is  delayed 
until  the  cell  has  reached  mature  age,  or  even  until  it  is  about  to  divide. 
A  modified  Latin  description  of  Roya  is  given,  and  the  new  species 
R.  anglica  is  described.  The  latter  was  gathered  near  Birmingham  in 
the  spring  of  1916  in  very  shallow  water,  and  has  never  been  found  in 
such  abundance  again.  It  was  almost  a  pure  growth,  affording  numerous 
cases  of  conjugation  and  thousands  of  zygospores.  A.  G. 


Studies  on  the  Chloroplasts  of  Desmids.  III. — X.  The  Chloro- 
plasts  of  Cosmarium.— Xellie  Carter  {Ann.  of  Bot.,  1920,  84, 
265-85,  4  pis.  and  figs.).  An  illustrated  account  of  the  chloroplasts 
found  in  Cosmarium.  In  most  species  these  are  axile,  in  a  few  they  are 
parietal.  In  the  former  either  one  or  two  chloroplasts  occur  in  each 
semi-cell,  and  very  often  in  the  axis  of  each  chloroplast  there  is  typically 
one  pyrenoid  ;  the  actual  number  of  pyrenoids  depends  on  the  individual. 
Many  of  the  smaller  species  have  a  single  chloroplast  in  each  semi-cell 
consisting  of  a  central  axis,  containing  typically  one  pjrrenoid  from  which 
radiate  either  four  more  or  less  forked  plates  or  a  number  of  simple 
ridges  or  string-like  outgrowths.  In  C.  dijolosporum  there  is  a  rough 
kind  of  parietal  network  arising  from  the  lateral  expansion  of  the  ends 
of  the  chloroplast  rays  extending  from  the  central  axis,  [n  C.  pseudo- 
pyramidatiun  the  plates  arising  from  the  central  axis  containing  the 
central  pyrenoid  or  group  of  pyrenoids  are  very  complicated  in  form 
and  irregular  in  arrangement.  C.  pyramidatum  differs  from  the  previous 
species  in  having  a  more  delicate  axis  in  the  arrangement  of  its  pyrenoids, 
which  rarely  occupy  the  centre  of  the  chloroplast.  G.  achondroides 
differs  from  G.  dlplosporum  in  having  pyrenoids  in  the  lateral  lobes  of 
its  chloroplast  as  well  as  in  its  central  axis.  In  G.  pseudoconnatwn  the 
chloroplast  is  axile  with  four  wedge-shaped  masses  radiating  towards  the 
periphery,  each  mass  possessing  typically  one  pyrenoid.  G.  ornatiim 
and  G.  Ralfsii  differ  from  all  the  other  species  examined  in  having 
scattered  pyrenoids,  rarely  more  than  three  in  G.  ornatumy  but  more 
numerous  in  the  larger  G.  Ralfsii ;  and  the  chloroplast  of  the  latter 
resembles  those  of  certain  thick-celled  species  of  Micrasterias.  Many 
species  of  Gosmarium  have  two  axile  chloroplasts  in  each  semi-cell,  there 
being  one  point  of  pyrenoid  formation  in  each  chloroplast.  The  axis 
which  contains  the  pyrenoid  or  group  of  pyrenoids  is  surrounded  by  a 
number  of  radiating  plates  or  more  numerous  string-like  projections, 
whose  peripheral  edges  in  many  cases  spread  out  over  the  internal 
surface  of  the  cell-wall,  either  in  irregular  parietal  masses  or  as  a  more 
or  less  continuous  reticulated  film.  Two  forms  of  G.  prsemorsum  were 
examined,  containing  one  and  two  chloroplasts  in  a  semi-cell  respectively. 
G.  BreMssonii  has  most  peculiar  and  variable  chloroplasts,  sometimes 
parietal,  sometimes  distributed  throughout  the  cell.  A  few  species 
have  chloroplasts  entirely  parietal,  with  scattered  pyrenoids,  the  number 
of  both  beino^  variable.  A.  G. 


226  SUMMAIIY    OF   CURRENT   RESEARCHES   RELATING  TO 

Catalogue  of  the  Collections  of  Diatoms  and  Fungi  in  the 
Pontifical  Academy  in  Rome.— G.  Antonelli  (Rome  :  1918, 171  pp.). 
A  catalogue  of  the  diatoms  of  Count  Francesco  Castracane  and  of 
Br.  M.  Lanzi  preserved  in  the  Accademia  Pontificia  Romana  dei  Nuovi 
Lincei.  It  includes  the  entire  collection  of  Castracane;  and  a  large 
part  of  Lanzi's  collection  of  diatoms,  together  with  all  his  microscopical 
preparations  of  fungi.  The  arrangement  of  the  slides  and  material  into 
groups  was  carried  out  by  Cav.  F.  Gatti.  The  Castracane  collection 
contains  4682  preparations,  each  of  which  is  here  recorded,  with  the 
name  of  the  species,  locality,  and  preparer.  Preparations  other  than 
•diatoms  bring  the  Castracane  total  to  4738  slides.  There  is  a  catalogue 
of  557  samples  of  diatomaceous  earth,  with  localities,  and  a  further  list 
of  recent  material,  bringing  the  number  of  samples  to  1191.  Then 
follow  indices  to  the  genera  and  species,  to  the  geographical  distribu- 
tion, to  the  expeditions  and  cruises  represented,  etc.  The  Lanzi 
collection,  which  is  catalogued  in  the  same  way,  contains  633  prepara- 
tions of  diatoms.  E.  S.  G. 

Campylonema  lahorense,  a  new  Member  of  Scytonemacese. — 
S.  L.  Ghose  {New  Phytologist,  1920,  19,  35-9,  figs.).  A  description  of 
a  blue-green  alga  which  appears  during  the  August  rains  at  Lahore,  and 
forms  vast  strata  on  damp  lawns,  etc.  The  sheath  of  the  filaments 
embedded  in  the  mud  is  inconspicuous,  but  is  strongly  developed  on  the 
upward  curved  aerial  filaments.  Though  previously  referred  to  Tohj- 
pothrix,  the  plant  shows  itself  to  be  quite  distinct  from  that  genus  by  its 
frequent  intercalated  heterocysts,  its  lack  of  pseudobranches,  and  the 
curvature  of  its  filaments.  It  falls  more  suitably  into  Campylonema,  but 
is  quite  distinct  from  the  Bombay  species,  G.  indicum,  which  is  epiphytic 
on  hepatics.  A.  G. 

Some  Tuscan  Myxophycese. — A.  Forti  and  M.  Savelli  {Bull. 
Soc.  Bot.  Itah,  1917,  6  pp.).  A  list,  with  localities,  of  forty-seven 
species  of  Tuscan  Myxophycese,  almost  all  collected  from  the  environs  of 
Pisa,  and  forming  a  preliminary  publication  to  a  work  on  the  fresh- 
water algae  of  the  district  of  Pisa.  E.  S.  G. 

Myxophycese  from  Italian  Somaliland. — A.  Forti  {R.  1st.  Studl 
Sup.  Fireiize,  1916,  p.  188).  A  few  remarks  extracted  from  the  Report 
by  E.  Chiovenda  on  the  Botanical  Collections  of  the  Stefanini-Paoli 
Mission.  The  author  records  Nostoc  commune  Yawch.  Yur.flar/eUiforme 
B.  et  F.,  of  which  he  gives  a  certain  amount  of  synonomy,  from  Salagle, 
in  Jubaland.  A  previous  record  is  Smithfield,  in  the  Orange  River 
Colony,  and  the  distance  between  the  two  stations  leads  to  tlic  inference 
that  the  variety  is  probably  diffused  throughout  the  continent.  It  does 
not  correspond  with  the  more  capilliform  varieties  of  typical  Nema- 
tonostoc  rhizomorphoides,  but  recalls  well  the  clathrate  thalli  distributed 
by  Collins  as  No.  1901  of  his  "  Phycotheca  Boreali- Americana,"  which 
demonstrate  the  slight  systematic  value  of  this  distinction.  This  variety 
is  eaten  in  China  under  the  name  of  Fahtsai.  The  distribution  includes 
the  Pyrenees,  Bohemia,  Texas,  Montana,  Mexico,  and  China.     E.  S.  G. 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,   ETC.  227 

Observations  on  Monosporangial  Discs  in  the  Genus  Liagora. — 
M.  A.  Howe  [Bull.  Torreij  Bot.  Club,  1920,  47, 1-8,  1  pL,  figs,  in  text). 
An  explanation  of  the  structures  briefly  described  and  figured  by  Kiitzing 
in  1858  (Tab.  Phjc.  YIIL,  pi.  90).  The  structures  in  question  are 
small  flat  orbicular  discs  lying  on  the  general  surface  of  the  plant  or 
somewhat  immersed  among  the  assimilatory  filaments.  They  are  of  a 
deeper  red  colour  than  the  main  Liagora  plant ;  they  send  down  few 
or  numerous  root-hairs  from  their  ventral  (proximal)  surface  in  among 
the  assimilatory  filaments  ;  and  they  bear  on  their  dorsal  (distal)  surface 
a  few  sporangia,  the  contents  of  which  remain  undivided,  so  that  they 
may  be  referred  to  as  monosporangia.  Long,  colourless,  gelatinizing 
hairs  may  usually  be  seen  arising  from  this  outer  or  dorsal  surface.  It 
might  be  supposed  that  they  are  either  independent  organisms  or 
perhaps  obligate  epiphytes  of  various  species  of  Liagora  ;  or  that  they 
result  from  the  germination  of  carpospores  and  represent  a  non-sexual 
alternating  phase  in  the  life-history  of  the  genus.  But  the  truth  seems 
to  be  that  these  discs  arise  from  gonidia,  gemmae,  or  aplanospores  derived 
from  the  terminal  or  subterminal  cells  of  the  assimilatory  filaments  of 
the  Liagora  ;  and  more  often  on  male  than  on  female  plants.  The 
development  of  the  discs  varies  in  certain  details  according  to  the 
species  they  represent.  The  author  has  made  a  prolonged  and  careful 
study  of  these  discs  on  four  of  the  West  Indian  species,  L.  ceratioides, 
L.  valida,  L.farinosa  and  L.  pinnata,  and  describes  the  variations  in 
the  development  of  each.  The  mature  discs  are  suborbicular  and  are 
more  or  less  similar  in  these  four  species.  Fertile  discs  are  mostly 
90-230  /x  broad  (not  including  the  mucous  envelope),  though  in 
L.  farinosa,  the  largest  species  of  the  four  named,  they  may  reach  a 
diameter  of  nearly  400  fx.  The  monosporangia  are  ellipsoid,  ovoid  and 
obovoid.  To  what  these  give  rise  on  germination  has  not  been  deter- 
mined, but  there  seems  to  be  some  ground  for  believing  that  they 
produce  monosporangial  discs  like  those  from  which  they  sprang.  In- 
ferences that  young  sporelings  associated  with  a  Liagora  represent  stages 
in  development  of  the  Liagora  itself  demand  vigorous  confirmation  ;  but 
the  almost  constant  association  of  Acrochsetium-like  forms  with  various 
species  of  Liagora  is  a  suspicious  circumstance  that  deserves  investigation. 
Finally,  he  points  out  criticisms  that  may  be  raised  on  his  conclusions, 
since,  as  he  frankly  acknowledges,  he  knows  of  no  analogy  among  other 
Rhodophycese  for  the  state  of  things  here  described.  He  suggests  that 
a  study  of  living  material,  cultural  experiments  and  cytological  investi- 
gation would  settle  the  question,  although  he  believes  his  explanation  to 
be  correct.  E.  S.  G-. 


Appendix  to  "  Oceanic  Algology." — A.  Mazza  {Nuova  Notarisia, 
1920,  31,  93-160).  Further  additional  notes  on  species  belonging  to 
sub-families  Mychode^e  and  Callymenie^e,  and  to  the  family  Rhodo- 
phyllidaceag.  The  author  devotes  considerable  attention  to  Calhjmenia 
crihrosa  Harv.,  describing  its  structure  and  perforations,  and  comparing 
it  with  perforated  species  of  Ph^eophyceae,  Hydroclathrus,  Agarum  and 
Thalassiophylliim,  as  well  as  with  other  Floridese.  The  two  doubtful 
species  of  Jleristotheca — 31.  Diichassaingii  J.  Ag.  and  M.  Fergussonii  Grun. 

Q  2 


228  SUMMARY    OF    CURRENT    RKSKARCIIES    RELA.TING    TO 

— are  considered,  but  though  the  author  suggests  other  affinities  for 
them,  he  does  not  consider  himself  justified  in  placing  them  in  any 
definite  genus,  until  the  limitations  of  the  genera  Meristotheca,  Garpo- 
cocciis  and  Euryomma  have  been  more  accurately  determined.  E.  S.  Gr. 

Geographical  Distribution  of  the  Marine  Algae. — W.  A.  Setchell 
{Science,  N.S.,  1917, 45, 197-204).  An  address  to  the  Botanical  Section 
of  the  American  Association  for  the  Advancement  of  Science.  The 
author  has  made  a  survey  of  the  entire  literature  of  the  marine  alg^, 
and  noted  the  influence  of  various  writers  in  developing  the  different 
lines  of  geographical  study.  He  considers  that  the  work  done  on  the 
following  five  lines  bears  most  directly  on  geographical  distribution,  viz. 
taxonomy,  morphology  and  development,  floristics,  physiology,  and  geo- 
graphical distribution.  The  work  of  various  authors  is  briefly  discussed. 
As  a  summing  up  of  the  general  results  and  an  attempt  to  determine  the 
general  subdivisions  of  the  coast-lines  to  satisfy  all  requirements  of 
geographical  distribution,  the  following  divisions  are  suggested  : — 
A.  Climatic. — I.  Zones,  regulated  by  temperature  of  the  warmer  months, 
especially  to  be  determined  by  the  mean  summer  temperatures  or  in 
practice  by  the  isotheral  lines  at  intervals  of  5°  C.  11.  Regions,  purely 
geographic  segregations  under  zones.  III.  Provinces,  subdivisions  of 
regions  according  to  mean  winter  temperatures,  in  practice  by  isocrymes, 
5°  apart  or  less.  lY.  Districts,  subdivisions  under  provinces  according 
to  geographical  remoteness  and  varying  physical  conditions  of  a  general 
nature.  B.  Topographiccd. — Y.  i^(9rmr^^/o?is,  aggregations  of  alg^eof  same 
general  form,  depending  particularly  upon  substratum.  YI.  Associations, 
aggregations  depending  for  general  likeness  of  form,  etc.,  upon  depth 
(belts),  salinity,  light,  aeration,  etc.,  generally  characterized  by  the 
predominance  of  a  single,  or,  at  most,  of  a  few  species.  E.  S.  G. 

Marine  Flora  of  the  Pacific  Coast. — W.  A.  Setchell  {Nature 
and  Science  on  the  Pacific  Coast.  San  Francisco  :  P.  Elder  and  Co., 
1915,  177-84).  A  more  or  less  popular  and  condensed  consideration  of 
a  large  subject,  touching  only  on  salient  features  and  giving  general 
directions  for  further  study.  The  area  is  divided  into  zones  which  are 
geographically  defined  :  Upper  Boreal,  Lower  Boreal,  N.  Temperate, 
N.  Subtropical,  Tropical.  Each  zone  has  a  flora,  the  general  aspect  or 
facies  of  which  is  distinct  and  characteristic.  All  the  main  groups  of 
algae  are  well  represented,  but  the  most  conspicuous  and  famous  are  the 
]iaminariacea3  of  which  the  author  gives  details  of  interest.  Marine 
phanerogams,  lichens  and  fungi  are  also  recorded.  A  short  list  of 
bibliography  is  appended.  E.  S.  G. 

Utilization  of  Marine  Algae.— C.  Sauvageau  {Encijclopedie  Scien- 
tifique.  Paris:  0.  Doin,  1020,  vi  and  394  pp.,  ^1^  figs,  in  text).  A 
description  of  the  uses  which  may  be  made  of  marine  algoe.  In  the 
introduction  the  author  refers  to  the  mode  of  life  of  the  seaAveeds,  their 
scientific  importance,  their  chemical  analysis,  and  the  biological  causes 
of  errors  made  by  analysts.  The  first  chapter  is  devoted  to  a  discussion 
of  the  weed  (wrack)  and  the  manner  of  collecting  it.  Three  sorts  are 
officially  recognized,  and  have  been  legislated  for  in  France  since  1681  i 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  229 

weeds  thrown  up  on  the  shore,  those  which  can  be  cut  in  situ  at  low 
water,  and  those  collected  from  a  boat  in  deeper  water.  The  rights  of 
the  French  people  along  the  shore,  who  use  the  wrack  for  agricultural 
purposes  and  for  fuel,  are  carefully  defined.  Also  an  account  is  given 
of  the  progress  of  the  industry  in  the  United  States.  In  the  second 
chapter  the  author  discusses  in  detail  the  application  of  wrack  to  agri- 
cultural purposes  in  various  countries.  It  promotes  the  growth  of 
excellent  potatoes  and  barley,  and  has  been  of  great  use  in  checking  the 
ravages  of  Phylloxera  in  vineyards.  Among  its  advantages  is  its  freedom 
from  noxious  insects,  seeds,  etc.,  which  are  common  in  ordinary  farm- 
yard manure.  He  discusses  the  chemical  value  of  the  giant  Laminari^e 
harvested  in  the  Pacific,  quoting  various  analyses,  and  refers  to  the 
methods  of  drying,  etc.,  which  is  .carried  out  on  a  large  scale  and  with 
great  success.  The  third  chapter  deals  with  the  industrial  utilization 
of  the  Brown  alg^e,  and  describes  the  commercial  uses  to  which  they 
have  been  put  to  in  old  days  ;  the  processes  of  calcination  and  lixivia- 
tibn  ;  the  extraction  of  soda,  potash,  iodine  ;  algin  and  its  properties  ; 
algulose  and  alga^-paper  ;  norgine  ;  process  of  fermentation  ;  sugars  ; 
pectic  compounds  (algin,  fucin,  fucoidin)  ;  intracellular  substances 
(mannite,  fucosan,  laminarin)  ;  and,  finally,  the  use  of  Zostera  and 
Posidonia  in  the  making  of  paper.  In  the  fourth  chapter  the  author 
discusses  the  industrial-utilization  of  the  Red  algye  under  the  headings  : 
iodine  ;  mucilaginous  and  gelatinizing  properties  ;  fabrication  of  funori 
and  kanten  in  Japan  ;  carra'gheen,  its  collection,  properties  and  uses  ; 
chemical  nature  of  the  mucilages.  Chapter  Y.  contains  an  account  of 
the  utilization  of  marine  algte  for  food  of  man  and  of  animals  (experi- 
ments in  feeding  French  horses  during  the  AVar),  with  an  interesting 
account  of  marine  herbivores,  the  blue  diatom  and  the  green  coloration 
of  oysters.  The  sixth  and  final  chapter  describes  various  uses  of  marine 
alg£e  and  their  culture  ;  the  use  of  dried  stipes  of  Laminari^e  ;  of  algse 
for  fishing  line,  and  as  bait  for  certain  fishes  ;  red  alga3  and  Tyrean 
purple  ;  medical  use  of  certain  alg^  ;  preparation  of  algfe  for  herbaria, 
etc.  ;  and  culture  of  marine  alges  in  Great  Britain  and  Japan.  The 
work  of  Lefranc  is  cited  as  showing  that  Tyrean  purple  is  the  product 
of  two  gastropods  and  not  of  algae.  A  bibliography,  a  table  of  authors' 
names,  an  index,  and  a  synopsis  complete  this  interesting  work. 

E.  S.  G. 

Feeding  of  Horses  with  Marine  Algse.— C.  Sauvageau  and  L. 
MoREAU  {C.R,  Acad.  Sci.  Paris,  1919,  168,  1257-61).  Describes  the 
experiments  made  in  1918  in  France  to  make  good  the  scarcity  qf 
forage,  especially  oats,  for  horses  by  feeding  them  on  marine  alga}. 
Horses  which  had  been  placed  on  the  sick  list  were  first  treated,  their 
oats  ration  being  replaced  by  alg».  They  recovered.  Healthy  horses 
were  then  gradually  trained  to  accept  the  new  food,  both  chemically 
prepared  and  in  a  natural  state.  The  algte  employed  were  Fiicus 
serratus  and  Laminaria  flexicaulis.  The  results  were  excellent,  and  the 
horses  under  observation  were  able  to  do  full  work  without  any  ration  of 
oats.  L.  saccharina,  however,  was  obstinately  refused.  This  fact  had  been 
noted  by  former  observers,  who  had  recorded  the  feeding  of  Norwegian 


230     SUMiMAHY  OF  CUEEEXT  EESEARCHES  RELATING  TO 

and  Lapp  beasts  on  marine  algse.  The  conclusion  is  therefore  that 
L.flexicaiilis  and  Fucus  serratus  constitute  an  excellent  food,  the  only 
drawback  being  that  it  is  as  a  rule  at  first  difficult  to  digest.  But  in  the 
course  of  a  week  or  two  digestion  becomes  more  and  more  complete,  till 
at  last  the  food  not  only  supports  life,  but  gives  strength  for  work,  and 
even  appears  to  aid  the  assimilation  of  the  ordinary  food.        E.  S.  G. 

British  Charophyta.  Vol.  I.  Nitellae. — J.  Groves  and  G.  R. 
Bullock-Webster  (London  :  Bay  Society,  1920,  xiv  and  141  pp., 
20  pis.,  figs,  in  text).  The  first  volume  of  a  monograph  of  the  British 
Charophyta,  which  will  be  completed  in  two  volumes.  The  first 
embraces  Nitellse  {NiteUa  and  TohjpeUa),  the  second  will  include  Chara; 
(Nitellojms,  Lamprothcminkun^  and  Chara).  In  an  introduction  the 
authors  discuss  the  rank  and  position  of  the  group,  its  antiquity,  geo- 
graphical distribution,  conditions  of  growth,  economic  uses,  etc.  Then 
follo»vs  a  detailed  and  illustrated  account  of  the  structure  and  develop- 
ment of  the  Charophyta  ;  a  conspectus  of  the  distinctive  characteristics 
of  the  oospores  and  membranes  of  the  British  Charophyta  ;  a  glossary  ; 
and  a  table  of  Latin  adjectival  names.  The  rest  of  the  book  is  devoted 
to  the  systematic  treatment,  which  opens  with  a  history  of  the  identifica- 
tion of  Charophyta  in  this  country,  reprinted  from  the  Joiirn.  of  Bot., 
1880.  Keys  to  the  five  genera  and  thirty-two  species  are  followed  by  a 
detailed  systematic  account  of  the  genera,  NiteUa  and  Tohjpella.  A 
full  list  of  synonymy,  diagnosis,  distribution,  and  critical  remarks  are 
supplied  under  each  species.  The  twenty  plates  exhibit  germination, 
stages  of  growth,  decoration  of  membranes,  and  the  habit  and  structure 
of  each  species  described  in  this  volume.  E.  S.  G. 

Preliminary  Note  on  a  Differential  Staining  of  the  Cytoplasm 
of  Characese.— R.  Hitchcock  {BuU.  Torrey  Bot.  Club,  1919,  46, 
375-9).  Describes  the  result  of  staining  the  cells  of  two  species  of 
NiteUa  with  a  dilute  solution  of  neutral  red.  The  central  cylinder 
is  seen  to  become  a  pronounced  cardinal  red  or  wine  colour,  bordered 
on  either  side  by  a  narrow  line  of  green.  Within  the  coloured  cylinder, 
or  vacuole,  are  numerous  suspended  granules,  etc.,  of  undetermined 
nature,  which  quickly  take  the  stain.  In  the  green  border  the  chloro- 
plasts  may  be  seen  regularly  arranged  along  the  cellulose  wall,  and 
next  to  that  layer  is,  all  coloured,  one  of  denser  cytoplasm,  carrying 
small,  nncoloured  granules  and  some  spherical  plasmic  bodies  in  suspen- 
sion, in  active  cyclosis,  closely  following  the  cell-wall.  Further  details 
of  the  cell-structure  are  discussed,  and  the  manner  in  wliich  the  colour- 
ing matter  makes  its  way  into  the  vacuole  of  the  NiteUa  cell.  A 
peculiar  plasmic  stmcture  in  the  NiteUa  cell  is  then  described,  consisting 
of  curious  spherical  masses  of  granular  matter,  of  extreme  plasticity, 
greatly  varying  in  size  up  to  0-1  mm.  diam.  The  granules  are  in  a 
state  of  constant  agitation,  as  though  the  mass  were  seething  with  life. 
The  author  describes  them  in  detail,  and  suggests  they  may  be  con- 
nected with  the  development  of  chloroplasts.  These  were  observed  in 
two  species  of  NiteUa  and  one  of  ( 'hara.  The  author  suggests  these 
structures  may  be  the  same  as  those  imperfectly  described  by  Goeppert 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  231 

and  Cohn  (Bot.  Zeit.,  184:9),  and  by  them  associated  with  the  formation 
of  starch.  In  a  supplementary  note  the  author  states  that  the  long 
hyaline  rhizoids  of  Nitella  afford  a  more  favourable  means  of  demon- 
strating the  selective  colouring,  the  vacuole  becoming  deeply  coloured, 
while  the  thin  uncoloured  outer  stream  is  in  active  rotation.  The 
vacuole-contents  may  be  strongly  coloured  by  reason  of  an  acid  reaction. 
Ordinary  vrater,  or  distilled  water,  is  usually  slightly  alkaline,  slowly 
changing  neutral  red  to  yellow  or  orange.  When  Nitella  is  grown  in 
water  slightly  acidified  with  acetic  acid  the  vacuole  becomes  much  more 
deeply  coloured  than  the  culture  solution.  E.  S.  G. 


Fungi. 

New  Peronospora  for  Italy  (Peronospora  Radii  De  Bary)  and  its 
Floral  Deformations  on  Matricaria  Chamomilla. — Nicola  Bblosersky 
{Atti  Accad.  Sci.  Venet. -Trent. -Istr.,  191'J,  10,  111-G).  The  author 
sums  up  the  deformations  caused  by  the  fungus  as  reported  by  Molliard 
— the  mechanical  action  exercised  by  the  mycelium  on  dividing  cells ; 
torsion  of  the  floral  peduncle  owing  to  the  formation  of  secondary  tissue ; 
modifications  due  to  alterations  in  nourishment,  such  as  the  atrophy  of 
the  sexual  organs  and  transformation  of  the  floral  ligules  into  floral  tubes, 
etc.  The  latter  deformations  more  especially  were  confirmed  by  the 
author,  and  are  described  in  detail.  A.  Lorrain  Smith. 

Infection  Experiments  on  Tomatoes  with  Phytophthora  terrestria, 
etc. — J.  RosENBAmi  {Phytopathology,  1920,  10,  101-5).  The  fungus 
causes  a  rot  of  the  fruits,  these  being  attacked  where  they  touch  the 
ground.  If  the  fruit  is  only  slightly  damaged,  the  fungus  can  be  killed 
by  immersion  of  the  tomatoes  in  60°  C.  water  for  one  and  a  half  minutes. 
The  addition  of  1-5000  copper  sulphate  to  infected  soil  will  prevent 
infection  from  the  soil  to  the  tomatoes.  A.  L.  S. 

Zoophagus  insidans. — Robert  Mirande  {Bull.  Soc.  MycoL  Fr., 
1920,  36,  47-53,  2  figs.).  This  fungus,  a  parasite  on  rotifers  and 
other  animalculse,  was  discovered  in  Austria  in  1911.  Mirande  has 
recently  found  it  in  an  aquarium  in  which  aquatic  mosses  were  cultivated. 
The  fungus  has  a  long  non-septate  wide  filament  similar  to  that  of  a 
Saprolegnia.  At  varying  intervals  there  are  narrow  branchlets  or 
projections  at  right  angles  to  the  main  filament.  It  is  by  means  of 
these  branchlets  that  the  fungus  captures  the  animalcules  and  retains 
them  until  their  contents  are  exhausted.  The  author  seems  to  agree 
with  the  suggestion  that  the  fungus  is  allied  to  Saprolegnia,  He 
compares  it  with  Arthroboirys  oh'yospora,  which  captures  Nematodes. 

A.  L.S. 

Chytridine  Parasite  of  Lucerne. — Fron  and  Laonier  {Bull.  Soc. 
Mycol.  Ft.,  1920,  36,  53-61,  1  pi.,  1  fig.).  The  fungus  Urophlyctis 
Alfalfas  causes  deformation  of  the  host  plant.  It  invades  the  cells, 
causing  them  to  enlarge  ;  the  cellular  membrane  is  thickened,  and  the 


232  SUMMARY   OF   CURRENT   RESEARCHES    RELATING   TO 

final  destruction  of  these  cells  gives  rise  to  cavities  in  which  are  formed 
resting-bodies,  termed  "  chronisporocjstes."  No  sexual  process  was 
observed.  A.  L.  S. 

Development  of  the  Spinach  Mildew  (Peronospora  Spinaciae). — 
Jakob  Eriksson  (ArJciv.  Bot.,  1919,  15,  Xo.  15,  1-25,  3  figs.,  4  pis.). 
An  account  of  the  geographical  distribution  of  the  fungus  is  given.  It 
was  described  first  in  England  as  Botrytis  effusa  and  confused  with 
Peronospora  effusa.  It  has  been  recorded  in  most  European  countries 
and  America.  Eriksson  discusses  and  condemns  the  theories  held  l:)y 
various  workers  as  to  the  over-wintering  of  the  fungus.  He  then 
proceeds  to  give  the  results  of  his  own  cytological  researches  on  the 
spinach  plant.  He  traces  the  beginning  of  the  fungus  to  a  mycoplasm 
in  the  cell  of  the  host.  The  history  of  development  is  followed  through 
the  escape  of  the  mycoplasm  from  the  cell,  the  formation  of  hyphffi  and 
sexual  organs,  and  the  production  of  conidiophores  and  conidia,  which  in 
turn  initiate  new  infections.  A.  L.  S. 

Studies  in  Discomycetes.  IL— Jessie  S.  Bayliss  Elliott  {Trans. 
Brit.  Mycol.  Soc,  1920,  6,  263-8,  30  figs.).  The  writer  publishes 
critical  notes  on  a  number  of  rare  species  ;  she  gives  a  new  and  revised 
description  of  Dasyscypha  conformis,  and  she  judges  that  Orhih'a 
coccinella  does  not  differ  from  0.  Uucostigma  var.  Xant  ho  stigma.  Asso- 
ciated constantly  with  Pyrenopeziza  pUcata  is  to  be  found  Phoma  conicoJa 
sp.  n.     Mollisia  Populi  sp.  n.  was  found  at  Tanworth-in-Arden. 

A.  L.  S. 

Formation  of  Conidia  and  the  Growth  of  the  Stroma  of  Daldinia 
concentrica. — Jessie  S.  Bayliss  Elliott  {Trans.  Brit.  Mycol.  i^oc, 
1920,  6,  2G9-73,  9  figs.).  The  author  watched  the  development  of  the 
conidia  both  in  nature  and  in  artificial  cultures.  Observations  are 
recorded  on  the  development  of  the  stroma,  the  formation  of 
perithecia,  and  the  discharge  of  the  ascospores.  The  fibrous  nature  of 
the  stroma  is  due  to  tlie  arrested  growth  of  perithecia.  Any  increase 
in  humidity  brings  about  active  growth  which  leads  to  the  formation  of 
a  new  perithecial  layer  and  atrophy  of  the  preceding  zone.       A.  L.  S. 

Aspergillus  fumigatus,  A.  nidulans,  A.  terreus  sp.  n.,  and  their 
Allies. — Charles  Thom  and  Margaret  B.  Church  {Ainer.  Joum. 
Bot.,  1918,  5,  84-101,  3  figs.).  The  authors  give  an  account  of  their 
cultural  researches  on  these  three  related  Aspergilli.  They  fall  into  two 
divisions  : — A.  fumiyatus  with  simple  sterigmata,  and  the  others  with 
compound  sterigmata.  Each  Aspergillus  also  represents  a  group.  The 
authors  give  descriptions  of  tbem  all,  a  key  to  the  species,  and  a  descrip- 
tive list  of  published  species  belonging  to  this  well-marked  series. 

A.  L.  S. 

Spore  Formation  in  Philocopra  coeruleotecta  Rehm  sp.  n. — Hallv 
Jolivette  8ax  {Amer.  Joum.  Bot.,  19 IS,  5,  G1-7S,  ;5  pis.).  The 
fungus  has  a  minute  perithecium  and  polyspored  asci.  The  research  was 
undertaken  to  determine  the  manner  of  spore  formation  in  such  an  ascus. 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,   ETC.  233 

in  order  to  see  if  the  development  had  any  affinity  with  spore  formation 
in  a  sporangium.  The  author  describes  his  methods  and  cultures,  and 
finally  gives  a  summary  of  the  points  determined  : — Spore  formation 
proceeds  as  in  the  eight-spored  ascus  ;  there  is  successive  nuclear  division 
until  the  final  number  is  reached,  then  the  spore  is  delimited,  as  in  other 
species,  by  the  astral  hairs  which  bend  back  and  fuse  to  form  the  spore 
membrane.  There  is  therefore  no  indication  of  any  phylogenetic  rela- 
tionship between  the  ascus  and  the  sporangium  of  the  Phycomycetes. 

A.  L.  S. 

Audibility    of    Spore   Discharge   in   Helvella    elastica. — R.    E. 

Stone  {Trans.  Brit.  MycoL  Soc,  1920,  6,  294).  The  writer  brought  to 
his  laboratory  a  basket  full  of  these  fungi,  and  the  following  day  he 
detected  a  hissing  sound  at  a  distance  of  five  to  six  feet.  On  lifting 
the  cover  of  the  basket  he  noted  a  spore-puff  with  a  distinct  hiss.  The 
puffs  occurred  at  intervals  and  always  accompanied  by  a  hissing  sound. 

A.  L.  S. 

Diplocystis  and  Broomeia. — I.  B.  Pole  Evans  and  Averil  M. 
BoTTOMLEY  {Trans.  Roy.  Soc.  S.  Africa,  1919,  7,  189-92,  5  pis.).  The 
authors  describe  a  new  species,  Diplocystis  Junoclii,  sent  from  Portuguese 
E.  Africa,  and  called  by  the  natives  "  Fole  da  mangapfi,"  viz.  the 
tobacco  of  the  hawk.  The  authors  compare  Diplocystis  with  Broomeia  ; 
the  two  genera  are  nearly  related,  but  differ  in  the  form  of  the  stroma, 
which,  in  the  latter,  is  thick  and  somewhat  columnar,  while  in  Diplocystis 
it  is  saucer-hke.  It  has  been  stated  that  Broomeia  congreyata  grows  on 
rotten  wood,  but  the  authors  find  it  on  living  trees  of  Acacia  karoo,  and 
the  trees  thus  associated  were  gumming  freely  from  the  main  stem. 

A.  L.  S. 

Furrows  and  Germinating  Pores.— J.-E.  Chenantais  {Bull.  Soc. 
3Iycol.  France,  1920,  36,  29-33,  figs.).  The  writer  criticizes  as  a 
character  of  taxonomic  importance  the  presence  of  a  pore  or  furrow  in 
spores  of  Xylariaceai.  Yincens  had  published  a  paper  which  insisted  on 
the  importance  of  the  furrow  as  indicating  relationship.  Chenantais 
considers  that  the  furrow  is  simply  a  mode  of  dehiscence  in  brown  thick- 
walled  spores,  and  may  occur  in  unrelated  genera.  A.  L.  S. 

Development  of  the  Geoglossacess. — G.  H.  Duff  (Bot.  Gaz.,  1920, 
69,  341-6.)  The  writer  traces  the  growth  of  Gudonia  lutea  and 
Spathularia  velutipes  from  the  earliest  stages.  He  finds  at  the  centre  of 
a  minute  cushion  of  hyphse  certain  filaments  conspicuous  by  their  size 
and  staining  qualities ;  they  are  the  precursors  of  coiling  procarps 
which  arise  from  them  at  a  later  stage.  In  Spatliuluria  generative 
hypha^  appear  much  later,  as  do  the  procarps.  In  Gudonia  the  procarp 
produces  "  typical  multiseptate  trichogynes  which  penetrate  the  envelope, 
projecting  into  the  air  for  a  short  distance.  Spermogonia  and  spermatia 
are  entirely  lacking,  and  it  is  not  thought  that  the  trichogynes  are 
functional  organs."  The  writer  contrasts  this  development  with  that  of 
the  Gladonise  among  lichens  as  described  by  Nienburg.  A.  L.  S. 


2 Si  SUADIAUY    OF   CURRENT   RESEARCHES   RELATING   TO 

List  of  the  Discomycetes  of  Perthshire. — James  Menzies  {Trans. 
Perthshire  Soc.  Nat.  ScL,  1919,  72-7).  The  author  has  brought  together 
all  the  Discomycetes  that  have  been  recorded  in  that  county  ;  those  from 
the  Perth  district  were  found  by  himself.  The  list  is  long  and  represen- 
tative of  British  species.  With  the  list  is  associated  the  description  of  a 
rare  Myxomycete,  LindhJadia  effiisa.  It  grew  on  sawdust,  and  when  in 
full  vigour  looked  like  a  great  splash  of  tar.  A.  L.  S. 

South  African  Perisporiaceae.  11. — Ethel  M.  Doidge  (Trans. 
Roij.  Soc.  S.  Africa,  1919,  7,  193-7,  ?>  figs.)  reviews  and  corrects  the 
description  of  Meliola  torta  Doidge.  She  finds  on  the  same  host  a  second 
species,  M.  scabra  and  Asterina  sp.,  also  another  fungus,  Perisporina 
meUoliicola  sp.  n.,  parasitic  on  the  mycelium  of  Meliolse.  A.  L.  S. 

South  African  Perisporiaceae.  III. — Ethel  M.  Doidge  {Trans, 
Roy.  Soc.  S.  Africa,  1919,  8,  107-10,  1  pi.)  describes  four  species  of 
Meliola  from  Natal  and  the  eastern  part  of  the  Cape  Province,  hitherta 
unrecorded  from  South  Africa.  Full  descriptions  and  figures  of  these 
species  are  given.  A.  L.  S. 

South  African  Perisporiaceae.  IV.— Ethel  M.  Doidge  {Trans.  Rotj, 
Soc.  S.  Africa,  1919,  8,  111-5,  2  pis.)  in  this  contribution  gives  diagnoses 
of  six  new  species  of  Meliola,  two  species  of  Zukalia,  and  PhseodimerieUa 
asterinicola  sp.  n.,  the  latter  parasitic  on  the  mycelium  of  Asterina.  All 
of  them  grew  on  leaves  from  various  regions  of  South  Africa,  but  mostly 
from  Natal.  A.  L.  S. 

South  African  Perisporiaceae.  V. — Ethel  M.  Doidge  {Trans.  Roy. 
Soc.  S.  Africa,  1919,  8, 137— 43, 2  pis.)  describes  a  number  of  new  species 
of  Meliola  from  Natal,  and  lists  a  number  of  species  already  recorded 
from  South  Africa  or  elsewhere  on  the  same  or  on  different  hosts. 

A.  L.  S. 

Mycological  Notes.— Ethel  M.  Doidge  {Trans.  Roy.  Soc.  S.  Africa, 
1920,  8,  117-9).  The  paper  contains  notes  on  Asterodothis  Solaris 
(K.  and  Cke.)  Th.,  a  frequent  parasite  on  leaves  of  Olea  verrucosa  in 
South  Africa.  The  author  gives  several  new  records  for  other  leaf -fungi, 
and  describes  two  new  species.  A.  L.  S. 

Meliolaster,  a  New  Genus  of  the  Microthyriaceae. — Ethel  M. 
Doidge  {Trans.  Roy.  Soc.  S.  Africa,  1920,  8,  121-3)  places  the  new 
genus  in  the  group  of  Hemisphaeriales,  as  it  bears  a  perithecium  or 
"  thyriothecium  "  of  hemispherical  form.  Meliolaster  combines  characters 
of  Meliola  and  Asterina ;  it  grows  on  leaves  of  Pijieris  capensis  in  Natal. 

A.  L.  S. 

Descriptions  of  New  Fungi  Imperfecti  from  the  Philippines. — 
H.  DiEDECKE  [Ann.  Mycol.,  191G,  14,  02-4).  There  are  eight  new 
species  in  the  list  and  two  new  genera,  Bakcroplioma  and  Macropliomella, 
both  related  to  Phoma,  but  the  pycnidia  seated  on  a  subiculum,  or 
furnished  with  setae  at  the  apices.  A.  L.  S. 


ZOOLOGY   AND    BOTANY,   MICROSCOPY,    ETC.  'loD 

Contribution  to  the  Study  of  the  Brazilian  Mycological  Flora. — 
A.  Maublaxc  {Bull.  Soc.  Glycol.  France,  1920,  36,  :)3-43,  3  pis.)  made 
a  large  collection  of  fungi,  more  particularly  of  plant  parasites,  during 
a  two  years'  residence  in  Brazil.  His  intention  is  to  publish  a  com- 
plete list  of  his  plants,  but  meanwhile  he  is  issuing  descriptions  of 
new  fungi.  These  include  Pyrenomycetes  and  Sph^ropsideae,  with  one 
new  genus,  Uroiwly stigma  (Nectriace^e).  A.  L.  S. 

Phomopsisjuniperovora,  a  New  Species  causing  Blight  of  Nursery 
Cedars. — Glexn  Gardner  Hahn  {Phytopatholoyij,  1920,  10,  249-53, 
1  fig.).  The  fungus  occurs  on  the  needles  and  stems  of  Junipenis 
virginiana.  The  author  noted  two  types  of  spores,  the  usual  oblong  or 
ellipsoid  spores,  and  long  narrow  curved  spores,  which  he  terms  scoleco- 
spores.  A.  L.  S. 

Study  of  Fusarium. — Z.  Paravicini  {Ann.  Mycol,  1918,  16, 
300-19,  1  pi.).  The  author  set  out  to  examine  the  Fiisaria  that  cause 
rottenness  of  fruits,  and  to  observe  the  occurrence  of  anastomosis  and  its 
significance.  The  principal  agent  in  causing  the  rot  is  Fusarium 
putrefaciens.  Paravicini  by  his  cultures  obtained  growths  of  two  new 
species,  F.  hitewn  and  F.  rtibrum  ;  full  particulars  of  these  are  given. 
He  observed  anastomosis  in  the  mycelium  and  between  spores.  There 
was  no  evidence  of  any  sexual  act.  Anastomosis  took  place  unfailingly  in 
the  hanging-drop  cultures,  but  still  more  surely  if  the  drop  became 
concentrated  by  evaporation.  A.  L.  S. 

New  Genus  of  Hyphomycetes. — Komualdo  G.  Fragoso  (Bol  Real 
Soc.  Esp.  Hist.  Nat.,  1920,  20,  112-4,  3  figs.).  The  new  genus 
belongs  to  the  Dematiese,  and  is  characterized  by  large  septate  spores 
curved  at  the  ends.  It  grows  on  Sphagnum  squarrosum,  and  has  been 
named  Oasaresia  sphagnorum.  A.  L.  S. 

Puccinia  obscura  and  Related  Pucciniae  on  Luzula. — P.  Dietel 
{Ann.  Mgcol,  1919,  17,  48-58).  Puccinia  olscura  is  distinguished 
from  other  forms  on  Luzula  by  the  large  uredospores.  Dietel  has  tested 
the  size  of  these  spores  by  many  measurements,  comparing  those  from 
different  Luzulse.  He  made  the  same  measurements  and  comparisons 
with  the  teleutospores,  noting  in  both  series  of  experiments  the  colour 
as  well  as  the  size.  A.  L.  S. 

Structure  of  the  Uredinium  in  Pucciniastrum  Agrimoniae. — 0.  A. 
LuDWiG  and  C.  C.  Rees  (Amer.  Journ.  Bot.,  1918,  5,  5.5-6(i,  1  pi.). 
In  this  species  the  uredinium  begins  as  a  small  aggregation  of  hypha3 
under  the  epidermis,  which  is  finally  burst.  The  mesophyll  tissues  of 
the  host  are  scarcely  affected.  At  maturity  the  sorus  is  bounded  above 
and  at  the  sides  by  a  peridium  of  somewhat  overlapping,  thin-walled 
cells,  but  of  considerable  tensile  strength,  as  the  sorus  maintains  its 
shape  and  the  only  escape  for  the  spores  is  by  a  central  ostiole.  When 
this  stage  is  reached  the  peridium  begins  to  disintegrate.  The  mature 
spores  are  catenulate  and  echinulate.  The  authors  suggest  new  methods 
of  arrangements  in  the  Fucciniastratse  to  which  this  rust  belongs. 

A.  L.  S. 


236  SUMMARY    OF    CUllRENT    UESl!:ARCnES    KELATING    TO 

Short  Cycle  Uromyces  of  North  America. — G.  R.  Bisby  {Bot.  Gaz., 
1920,  69,  193-217, 1  pi.)-  The  writer  gives  an  account  of  the  genus,  and 
of  work— cytological  and  other—  done  on  the  genus.  There  are  eleven 
species  of  short-cycle  Uromyces  in  X.  America,  and  he  gives  a  detailed 
description  of  each  species.  They  occur  in  the  higher  and  warmer 
portions  of  the  Continent  and  upon  seven  widely  separated  host  families, 
iilorphological  evidence  shows  they  are  not  inter-related,  but  are  rather 
associated  with  other  rusts  upon  the  same  or  related  hosts.      A.  L.  S. 

Two  Russian  Gymnosporangiese. — Jakob  Eriksson  (ArMv.  Bot., 
1919,  15,  Xo.  20,  1-23,  2  pis.,  1  col).  One  of  these  rusts  *has  been 
determined  by  Eriksson  as  Gymnosporangium  Oxycedri  Bres.  He  was 
able  to  produce  the  secidium  stage  on  Crataegus  monogyna,  C.  nigra  and 
Mespilus  germanica.  Other  Fomacex — Sorbiis,  Fyrtis,  etc. — remained 
immune.  Another,  Gymnosporangium  tauricum  sp.  n.,  formed  teleuto- 
spores  on  Juniperus  excelsa.  It  formed  fecidia  on  Crataegus  monogyna 
and  spermogonia  on  Cydonia  vidgaris.  Other  Pomaceee — Fyrus, 
Mespilus,  Sorbus,  etc. — were  immune  to  infection.  A.  L.  S. 

Uredinales  of  Guatemala  based  on  Collections  by  E.  W.  D. 
Holway.— J.  C.  Arthur  {Amer.  Journ.  Bot.,  1918,  5,  325-36,  420-40, 
402-89).  Arthur  has  pubhshed  his  results  in  three  different  papers. 
A  total  of  600  rust  specimens  was  collected  by  Holway  during  three 
successive  visits.  In  the  first  paper  an  account  is  given  of  the  different 
expeditions,  and  the  Coleosporacese  and  Melampsorace^e  are  described 
(twenty-two  species),  several  of  them  new  to  science.  The  second  paper 
deals  with  ^Ecidiaceae,  exclusive  of  Fuccinia,  bringing  the  total  up  to 
101  species  ;  the  third  paper  takes  up  Fuccinia  exclusive  of  species  on 
CarduaceaB.  He  finds  that  in  the  last  group  the  most  interesting  are 
the  species  on  grasses  ;  such  rusts  are  less  common  in  the  tropics. 
Holway  secured  fifteen  species,  three  of  them  undescribed.  Holway 
was  also  able  to  connect  up  an  jEcial  form  on  Eupatorium  with  a  grass 
rust  on  jFjgopogon,  A.  L.  S. 

Selected  Cycles  in  Gymnoconia  Peckiana. — Gr.  F.  Atkinson 
{^Amer.  Journ.  Bot.,  1918,  5,  71>-83).  This  rust  was  considered  to  be 
a  short-cycle  species  with  two  generations.  It  is  associated  with  Cseoma 
nitens,  a  rust  of  raspberry  plants.  It  has  also  been  demonstrated  that 
the  cycle  may  be  further  shortened  by  the  lecidiospores  germinating 
in  the  manner  normal  for  teleutospores,  i.e.  by  the  production  of 
promycelia  and  sporidia.  The  author  confirmed  this  finding  and 
discusses  the  importance  and  the  position  in  classification  of  Gymnoconiar 
Ferlciana.  A.  L.  S. 

Dothideaceous  and  other  Porto  Rican  Fungi. — F.  L.  Stevens 
{Bot.  Gaz.,  1920,  69,  24S-r)7,  3  figs,  and  2  pis.).  Stevens  collected  the 
fungi  described  in  Porto  Rico  ;  they  are  all  plant  fungi  occurring  on 
leaves  or  stems  of  various  trees.  There  are  a  number  of  new  species 
and  one  new  genus  Hahtedia,  the  asci  of  which  are  borne  in  a  locule  in 
a  superficial  stroma.  A.  L.  S. 


ZOOLOGY   AND   BOTANY,    MICROSCOPY,    ETC.  237 

Genus  Clavariopsis  Holt. — X.  Patouillard  {Bull.  Soc.  Mijcol. 
France,  1920,  36,  61-3,  2  figs.).  The  genus  was  established  by  Holter- 
mann  to  induclc  species  of  Tremella  with  a  Clavaria  form  of  growth. 
Three  species  from  tropical  countries  have  been  determined  as  belonging 
to  the  genus.  Patouillard  now  describes  a  fourth  from  the  Philippines 
collected  by  Professor  Otto  Reinking.  This  species  is  distinguished  by 
the  formation  of  new  basidia  arising  from  a  continuation  of  the  fertile 
filament  from  the  base  of  that  previously  formed.  A  section  shows  a 
whole  series  of  these  basidia  in  tiers  up  to  the  exterior  of  the  plant. 
The  fungus  grows  in  groups  of  upright  simple  or  branched  stalks  up  to 
2  cm.  high.  A.  L.  S. 

Higher  Basidiomycetes  from  the  Philippines  and  their  Hosts. 
I.— 0.  A.  PtEiXKiXG  {Pliilippine  Joum.  Sci.,  1919,  15,  479-90).  The 
list  includes  the  larger  fungi  that  grow  on  living  or  dead  trees.  The 
former  being  parasitic  are  more  restricted  in  their  hosts.  Schizophyllum 
commune,  a  saprophyte,  is  recorded  on  fifteen  different  woods.  The 
fungi  were  identified  by  X.  Patouillard.  A  list  of  hosts  is  also  given 
with  their  parasites.  A.  L.  S. 

Cytology  of  Eocronartium  muscicola. — Harry  M.  Fitzpatrick 
{Amer.  Joum.  But,  1918,  5,  397-419,  3  pis.).  A  detailed  study  of  the 
cytology  of  the  fungus  in  all  its  stages.  All  the  hyphse  seem  to  have 
binucleate  cells.  The  nuclei  fuse  in  the  young  basidia.  The  various 
phases  of  nuclear  division  are  described.  Nothing  is  known  of  the 
nuclear  history  which  follows  spore  germination  and  precedes  the 
appearance  of  the  binucleated  series  of  cells  in  the  hyphse.  The  fungus 
is  closely  related  to  the  Uredinales,  and  there  may  be  a  cell  fusion  at 
one  stage  which  would  provide  the  two  nuclei.  A.  L.  S. 

Hymenomycetes  of  France. — H.  Bourdot  and  A.  Galzix  {Bull. 
Soc.  Mycol.  France,  1920,  36,  43-7).  An  account  of  species  of 
Asterostroma  and  Asterodon.  The  Asterostromea^  form  a  small  group 
characterized  by  the  stellate  cystidia  analogous  with  the  cystidia  of 
Hymenochsete,  etc.  Three  species  of  Asterostroma  are  recorded  for 
France,  and  one  of  Asterodon.  They  are  all  more  or  less  brightly 
yellow  in  colour.  A.  L.  S. 

Polyporacese  of  Bengal.  III. — S.  R.  Bose  {Bull.  Med.  Coll.  Belgachia, 
1920,  1-8,  6  pis.).  The  writer  gives  good  popular  descriptions  of 
twelve  species  of  more  or  less  common  occurrence.  The  paper  forms 
part  of  a  series  by  the  same  author.  A.  L.  S. 

Development  of  some  Exogenous  Species  of  Agarics. — Gertrude 
E.  Douglas  {Amer.  Joum.  Bot.,  1918,  5,  36-54,  7  pis.).  A  study  of 
development  in  Mycena  suhalccdina,  Hygrophorus  sp.,  and  Entoloma  sp. 
In  these  Agarics  the  fruit-body  is  at  first  a  button  of  interwoven 
hyphae.  Differentiation  arises  by  apical  growth,  and  the  hymenophore 
originates  in  the  annular  furrow  which  is  at  the  junction  of  stem  and 
pileus.  Gills  develop  as  in  endogenous  forms,  except  that  they  are 
exposed  from  the  beginning.  A.  L.  S. 


238  SUMMARY   OF    CURRENT   RESEARCHES   RELATING   TO 

Some  New  Species  of  Inocybe.— Geo.  F.  Atkinson  (A^ner.  Journ. 
Bot,  1918,  5,  210-8).  The  author  gives  diagnoses  of  twenty-five 
species  of  Inocijle  new  to  science.  They  were  all  collected  at  various 
dates  during  the  last  twenty  years  or  so  in  Xew  York  State,  mostly 
at  Ithaca  or  in  the  grounds  of  Cornell  University.  Atkinson  pays 
special  attention  to  the  cystidia  as  diagnostic  characters.         A.  L.  S. 

Novae  Fungorum  Species.  XV.— H.  and  P.  Sydow  {Ann.  Mijcoh, 
1917,  15,  143-8).  The  fungi  described  in  this  contribution  were  sent 
from  many  different  regions,  Japan,  South  Africa,  etc.  One  new  genus 
is  recorded,  Actinomyxa  ;  the  species  A.  australienses  (Microthyriaceag) 
was  sent  from  Mr.  Wilson  in  Australia,  and  grew  on  leaves  of  Lasio' 
petahis.  A.  L.  S. 

Notae  Mycologicse.  Series  XXIII. — P.  A.  Saccardo  (Atii  Accad. 
8ci.  Venet.-Trent.-Istr.,  1919,  10,  57-94).  These  notes  deal  with 
Philippine  fungi  collected  by  C.  F.  Baker.  The  list  comprises  149  fungi, 
109  of  which  are  new  to  science,  the  new  species  belonging  largely 
to  Fungi  Imperfecti.  There  are  also  four  new  genera  :  Reyesiella 
(Uredine^),  near  to  Ravenelia,  but  differing  in  the  absence  of  sterile 
cells,  etc. ;  Ferrarisia  (Perisporiace^e)  ;  Tr otter ia  (Sphserioideas)  ;  and 
Syorostachys  (Hyphomycetes).  The  species  all  come  under  the  micro- 
fungi  group.  A.  L.  S. 

Tympanopsis  and  some  other  Genera. — F.  Theiszen  {Ann.  MycoL, 
1917, 15,  269-77, 1  fig.).  Under  this  title  Theiszen  gives  the  result  of  his 
examination  of  a  number  of  doubtfully  placed  species.  He  classifies 
Tympanopsis  among  Coronophorese,  a  group  very  near  Sorclarieee,  and 
adds  a  new  genus,  Euacanthe,  with  a  setose  perithecium,  to  the  group. 
Detailed  descriptions  of  other  genera  and  species  are  also  given. 

A.  L.  S. 

Mycological  Contributions. — Fr.  von  Hohnel  {Ber.  Deutsch.  Bot. 
Ges.,  1917,  35,  246-56)  passes  in  review  a  considerable  number  of  the 
smaller  fungi,  indicating  mistakes  that  have  been  made  generally  of 
species  placed  in  the  wrong  genera.  He  has  established  as  new  genera  : 
Discosphserhia,  Apioportlie,  Fezizellaster,  Lacknastcr,  Stereolachnea^  the 
last  three  on  account  of  hair  formation  on  margin  or  disc.  Also 
CaJothyrieJla  and  HapJotheciella,  the  latter  based  on  Dothedea  Prostii. 
Among  Sph^ropsidese  he  descril)es  Septochroa  g.n.  and  Fhseophomopsis, 
the  latter  based  on  FJioma  Hederee. 

In  a  furtlier  paper  {Ann.  MycoJ.,  1917,  15,  293-;>03)  von  Hohnel 
criticizes  a  great  many  genera  and  species.  He  himself  adds  as  new 
genera :  Hypodermellina,  with  the  associated  RhahdostromeUina,  Eiipro- 
polella,  Bifusella,  and  Eosphseria.  A.  L.  S. 

Study  of  Fumagines.— F.  W.  Neger  {Flora,  1917,  X.F.,  10, 
67-lo9,  31  figs.).  The  term  "fumagine"  is  given  to  those  fungi  that 
live  on  the  honey-dew  of  leaves.  Such  fungi  are  provided  with  a 
mucilaginous  mycelium  to  protect  them  against  drought.  Artificial 
cultures  were  made  of  the  fungi  which  are  described.     Numerous  other 


ZOOLOGY    AND    BOTANV,    MICROSCOPY,    ETC.  239 

fungi  are  associated  with  them  and  appeared  in  the  cultures.  Neger 
enumerates  as  fumagines  :  Dematium  puUidaris,  Gladosporium  her- 
barum,  Hormisciwti  pmophilum,  with  species  of  Triposporium,  Gyroceras, 
Torula,  Helminthospormm,  Sarcinomyces  and  Atichia.  A.  L.  S. 

Mycological  Fragments. — Fr.  von  Hohnel  {Ann.  Mycol.,  1918, 
16,  35-174.).  The  author  continues  his  criticism  of  work  done  on 
Pyrenomycetes,  with  very  full  descriptive  and  explanatory  notes.  He 
makes  a  number  of  new  species  and  of  new  genera :  Phyllocrea 
(Hysteriacege),  Kriegerella  (Microthyriacese),  DidymelUna  (near  to 
Didymella)^  etc.  Synoptic  keys  of  the  genera  in  several  families  are 
given.  A.  L.  S. 

Mycological  Notes. — C.  G.  Lloyd  {Mycol.  Notes,  Cincinnati,  Ohio, 
1919,  877-903,  figs.  1497-1596).  Lloyd  gives  descriptions  and  notes 
on  a  large  series  of  fungi  mostly  from  tropical  or  sub-tropical  countries. 
He  makes  a  new  genus  and  species,  Bovistoides  simplex,  collected  by  Miss 
Duthie,  South  Africa,  distinguished  by  the  capillitium,  which  consists 
of  simple  short  wavy  coloured  threads  with  acute  ends.  Another  fungus, 
which  he  describes  as  Thelep)liora  gelatinoidea  sp.  n.,  may  be,  he  thinks, 
a  new  genus,  and  suggests  Pseudothelepliora  as  a  generic  name.  It  has 
a  gelatinous  consistency,  but  the  spores  resemble  those  of  Thelephora.  A 
number  of  Xylarise  come  under  review.  A.  L.  S. 

Pimina  parasitica,  Grove.— A.  Lorrain  Smith  {Trans.  Brit.  Mycol. 
Soc,  1920,  6,  295-6).  The  writer  points  out  the  close  resemblance  of 
Urophiala  mycophiala  described  by  Yuillemin  to  the  above  fungus. 
Vuillemin,  on  being  consulted,  agreed,  but  held  that  it  belonged  to  a 
different  species,  and  he  also  claimed  that  Urophiala  should  be  the 
name  of  the  genus,  as  Pimina  was  imperfectly  described.        A.  L.  S. 

Preservation  of  Artificial  Cultures  of  Moulds.— Harry  F.  Tagg 
{Trans,  and  Proc.  Bot.  Soc.  Edinl).,  1918-19,  27,  335-7).  The  author 
describes  various  practical  methods  of  preserving  cultures  on  agar  or 
gelatine  either  as  herbarium  material  or  as  exhibition  specimens.  If  the 
medium  is  not  liquefied  formalin  may  be  used  to  kill  and  steriHze 
the  preparation  ;  if  liquefaction  has  begun  the  process  may  be  hastened 
by  allowing  hot  water  to  enter  below  the  medium  and  gradually  to 
dissolve  the  gelatine.  Further  information  is  given  as  to  mounting, 
etc.  A.  L.  S.  ° 

Fungi  of  the  Baslow  Foray.— E.  Wakefield  {Trans.  Brit.  Mycol. 
Soc,  1920,  6,  239-47).  The  itinerary  for  the  several  excursions  from 
Baslow  as  a  centre  is  given,  with  the  special  finds  for  the  different 
localities,  and  finally  a  complete  list  of  fungi  collected  during  the 
autumn  foray.  Two  species  new  to  Britain,  Mycena  cUlatata  Fr.  and 
Botryotrichum  piluliferum  Sacc.  &  March.,  were  found  along  with  other 
specimens.  *  A.  L.  S. 

Bacteria  and  Perithecial  Development. — A.  Sartory  {C.R.  Acad. 
Sci.,  1918,  167,  302-5),     Sartory  had  already  found  that  a- bacterium 


240  SUMMARY    OF    CURRENT   RESEARCHES    RELATING   TO 

was  necessary  in  the  cultures  to  induce  the  sporalation  of  a  yeast  and 
the  formation  of  perithecia  in  Aspergillus.  He  has  repeated  his  experi- 
ments. He  grew  the  Aspergillus  on  culture  media  with  and  w^ithout  the 
addition  of  bacteria.  When  these  were  absent  conidiophores  and  conidia 
were  formed  ;  perithecia  very  slowly  and  very  rarely.  With  the  bacteria 
present  there  was  a  ready  and  abundant  formation  of  perithecia. 

A.  L.  S. 

Drain-blocking  Fungus. — A.  Lorraix  Smith  {Trans.  Brit.  31ycol. 
Soc.^  1920,  6,  262-3).  The  writer  describes  the  circumstances  in  which 
the  fungus  Fomes  ulmarius  was  found  blocking  a  sewer  30  ft.  below 
ground  in  the  City  of  London.  There  was  no  elm-tree  in  the  vicinity, 
nor  any  evident  nutriment  for  the  fungus,  but  the  gap  in  the  pipes  by 
which  it  had  penetrated  was  evident.  A.  L.  S. 

Elementary  Notes  on  the  Morphology  of  Fungi.— A.  H.  Church 

{Bot.  Memoirs,  Oxford,  No.  7,  1920,  1-29).  Church  states  his  aim  in 
the  opening  sentence  : — "  Systematy  includes  the  consideration  of  the 
Progression  of  Plant  Life  from  first  '  origins '  to  the  condition  of 
present  vegetation,"  etc.  He  thus  traces  the  origin  and  development 
of  fungi  from  their  algal  ancestry  in  the  sea,  and,  as  polyphyletic,  from 
a  wide  range  of  transmigrant  alga3.  All  the  groups  from  bacteria 
onwards  are  discussed.  He  closes  with  a  consideration  of  the  various 
types  of  symbiosis  between  fungi  and  other  plants.  A.  L.  S. 

Notes   and   Additions   to   the    Fungus    Flora    of   Tasmania. — 

L.  RoDAVAY  {Papers  and  Proc.  Roy.  Soc.  Tasmania,  1920  (1919),  110-6). 
The  author  gives  a  series  of  notes  on  well-known  fungi  and  diagnoses 
of  several  new  species.  We  read  that  Collyhia  lutyracea  is  common, 
chiefly  amongst  wattle-trees,  that  Boletus  badius  only  appears  under 
introduced  pine-trees,  etc.  There  is  a  new  species  of  Spragueola,  only 
one  other  species  from  America  being  known  ;  also  two  new  subterranean 
fungi,,  Paurocotylis  niveus  and  Sphserosoma  tasmanica.  A.  L.  S. 

Influence  of  Illuminating  Gas  on  Bacteria  and  Fungi. — C.  A. 
LuDWiG  {Amer.  Journ.  Bof.,  1918,  5,  1-31).  The  paper  deals  with 
the  toxicity  of  coal  gas.  In  high  concentration  all  bacterial  oi 
fungoid  growth  is  checked  or  wholly  stopped.  Although  different 
species  are  differently  affected,  on  the  whole  the  vigour  of  any  strain 
is  reduced  by  prolonged  cultivation  under  the  influence  of  the  gas. 
The  effect  is  not  due  to  any  one  of  the  constituents,  but  is  probably 
caused  by  the  sum  of  the  small  effects  of  each  plus  the  deficient 
oxygen  content.  The  results,  however,  indicate  that  the  gas  incident- 
ally present  in  any  laboratory  is  quite  harmless.  A.  L.  S. 

Upon  the  Visibility  of  Spore  Dissemination  in  Fomes  pinicola. — 
R.  E.  Stone  {Trans.  Brit.  Mycol.  Soc,  1920,  6,  29;5)-  The  writer 
cites  the  experience  of  A.  H.  BuUer,  who  had  recorded  seeing  the 
discharge  of  spores  from  Polyporus  squamosus^,  he  saw  the  same  kind 
of  discharge  from  the  under  side  of  the  fruit-body  of  Fo?nes  pinicola ; 
the  spores  streamed  out  and  drifted  away  in  the  slight  air  currents. 

A.  L.  S. 


ZOOLOGY  AND   BOTANY,   MICROSCOPY,   ETC.  241 

Higher  Fungi  in  Relation  to  Human  Pathology. — Aldo  Castel- 
LANi  {Journ.  Troj).  Med.  and  Hyg.,  1920,  23,  101-10  ;  117-25,  figs.). 
Castellani  has  chosen  tliis  as  the  subject  of  the  Milroy  Lectures.  He 
sketches  the  history  of  our  knowledge  of  the  "  higher  fungi "  as 
contrasted  with  bacteria,  describes  the  fungi  likely  to  be  pathogenic, 
and  gives  an  account  of  their  chemical  powers  and  the  use  that  has  been 
made  of  them  to  determine  the  presence  of  various  substances  in  a 
solution.  In  the  second  lecture  he  describes  cases  of  mycosis  in  (1) 
thrush,  (2)  broncho-mycoses,  (3)  tonsillo-mycoses,  (4)  certain  mycoses 
of  the  nervous-system  and  organs  of  special  sense,  (5)  certain  mycoses 
of  the  uro-genital  system.  Thrush  he  finds  to  be  caused  by  a  fungus 
with  a  stout  mycelium  often  showing  arthrospores  and  numerous  free 
oval  or  roundish  budding  yeast-like  forms.  He  has  isolated  a  great 
many  different  species  and  placed  them  in  the  genus  Monilia.  They 
vary  chiefly  in  the  effect  ou  sugars.  Bronchial  affections  are  caused  by 
several  different  fungi : — Nocardicin  Monilia,  Oidiiim,  Hemispora,  Asper- 
gillus, Fenicillium,  Mucor  and  Sporotrichium,  The  causative  agents  in 
other  diseases  are  also  given  and  the  effects  produced.  The  lectures 
are  well  illustrated.  A.  L.  S. 

Some  Observations  on  Erysiphe  Polygoni.— G.  D.  Searle  {Trans. 
Brit.  Mgcol.  Soc,  1920,  6,  275-9).  Ergsiphe  Fohjgotii cames  the  swede 
mildew ;  this  and  various  problems  were  attacked  in  the  investigation. 
In  field  trials  no  kind  of  swede,  turnip  or  rape  out  of  seventy-seven 
tested  was  found  to  be  immune  to  the  disease.  Biologic  forms  were 
proved  to  exist.  As  to  overwintering  it  is  suggested  that  the  "  most 
probable  method  of  overwintering  of  the  '  biologic  form '  of  Ergsiphe 
Folggoni  on  the  cultivated  Brassicse  is  by  means  of  subinfections  on 
varieties  of  B.  oleracea  aided  by  persistent  mycelium  on  varieties  of 
B.  campestris.'''  The  experiments  are  described  in  detail  and  the  results 
set  forth  in  six  tables.     A  bibliography  of  the  subject  is  appended. 

A.  L.  S. 

Iris  Leaf-spot  caused  by  Didymellina  Iridis. — W.  B.  Tisdale 
(Phgtojmthologg,  1920,  10,  148-63,  6  figs.).  The  fungus  is  a  severe 
disease  of  the  broad-leaved  Iris  in  Wisconsin  and  wherever  the  species 
is  grown  ;  other  species  are  immune.  The  conidial  stage  is  known  as 
Heierosporiiim  gracile  ;  an  abundant  crop  of  conidia  appear  in  spring 
and  spread  infection,  penetrating  the  leaves  by  the  stomata.  Perithecia 
also  develop  in  spring,  but  do  not  always  produce  asci.  The  fungus 
overwinters  in  the  dead  leaves.  A.  L.  S. 

Phyllosticta  Blight  of  Snapdragon.— Edwina  M.  Smiley  {Phyto- 
pathologg,  1920,  10,  232-48,  8  figs.).  The  disease  gives  an  unsightly 
appearance  to  the  host  plants.  On  the  leaves  there  appear  brownish 
purple  or  dull  brown  spots  usually  near  the  top  of  the  leaves.  When 
the  centre  of  the  spot  falls  away  a  shot-hole  effect  is  produced.  Large 
brown  spots  are  also  formed  on  the  stems.  Pycnidia  appear  on  the  spots 
in  more  or  less  abundance,  and  may  carry  the  plant  over  the  winter 
season.  The  pathological  effect  of  the  disease  on  the  tissues  of  the 
plant  is  described.  Pure  cultures  were  also  made  and  the  relations  to 
different  media  studied.  A.  L.  S. 

R 


242  SUMMARY   OF   CURRENT   RESEARCHES   RELATING   TO 

*'  Brown  Rot "  Diseases  of  Fruit-trees,  with  special  Reference  to 
two  Biologic  Forms  of  Monilia  cinerea.  II. — H.  Wormald  {Ann.  Bot., 
1920,  34,  143-71,  2  pis.).  The  author  has  established  the  existence  in 
Britain  of  two  species  of  Monilia,  viz.  31.  fructigena,  the  conidial  stage  of 
Sclerotinia  fructigena,  and  M,  cinerea.  The  former  causes  a  fruit  rot 
of  apples,  plums  and  cherries,  and  on  apple-trees  produces  cankers  by 
invading  the  branch  through  the  fruit.  M.  cinerea  causes  "  blossom 
wilt"  and  "canker  disease  "  on  apples;  the  same  on  plums,  with,  in 
addition,  a  "  wither  tip  "  of  young  shoots  ;  while  on  cherry-trees  it  gives 
rise  to  "  fruit  rot,"  "  blossom  wilt "  and  "  twig  disease."  31.  cinerea 
produces  conidia  from  December  onwards  which  are  smaller  than  the 
summer  forms.  31.  fructigena  forms  no  conidia  in  winter.  Various 
biological  peculiarities  are  also  described.  A  complete  bibliography  is 
appended.  A.  L.  S. 

Physiological  Study  of  the  Parasitism  of  Pythium  debaryanum 
on  the  Potato  Tuber. — L.  A.  Hawkins  and  R.  B.  Harvey  {Journ. 
Agric.  Res.,  1919,  18,  275-97,  2  figs.).  The  authors  experimented  with 
a  number  of  potatoes ;  they  found  that  while  some  were  very  susceptible, 
others,  such  as  the  White  McCormick,  were  resistant  to  the  disease. 
They  think  it  probable  that  the  fungus  penetrates  the  epidermis  of  the 
potato  by  puncture  rather  than  by  enzymes,  and  they  explain  the 
immunity  of  the  McCormick  tubers  by  the  condition  of  its  cell  walls. 
The  rate  of  growth  of  the  fungus  in  the  McCormick  is  also  much 
slower.  A.  L.  S. 

Biology  of  Fomes  applanatus. — J.  H.  White  {Trans.  Rog.  Can. 
Inst.  Toronto,  1919,  133-74,  6  pis.).  The  fungus  attacks  practically  all 
deciduous  trees  and  several  conifers,  causing  great  damage  to  timber. 
The  author  describes  the  basidiospores  as :  "  Yellow  papillate  thick-walled 
chlamydospores  within  a  thin  hyaline  wall."  A.  L.  S. 

Plant  Sanitation  in  Fruit  Plantations. — F.  T.  Brooks  {Trans. 
Brit.  3Iycol.  Sec,  1920,  6,  253-62).  The  author  lays  down  certain 
principles  that  should  be  attended  to  if  disease  is  to  be  eradicated  from 
orchard,  garden,  field  or  forest.  It  is  most  important  that  no  harbourage 
for  the  disease  should  be  left.  Discarded  and  dead  branches  should  be 
removed  ;  dead  or  mummified  fruits  should  be  destroyed  ;  in  the  case  of 
rusts  the  alternative  hosts  should  be  eliminated.  Sanitation  measures 
such  as  spraying,  cultivation  of  the  soil,  etc.,  should  be  directed  by 
experts  with  knowledge  of  the  diseases  and  of  the  local  conditions.  The 
author  is  convinced  that  by  careful  control  measures  such  baffling 
diseases  as  silver-leaf  can  be  overcome ;  its  presence  is  often  clue  to  great 
neglect.  A.  L.  S. 

Notes  on  some  Diseases  of  Aspen.— Carl  Hartley  and  Glen  G. 
Hahn  {Phytopatkologg,  1920,  10,  141-7,  3  figs.).  PopuJus  trenmloidesl 
a  widely  distributed  American  forest  tree,  is  unusually  subject  to  disease. 
The  authors  have  investigated  there  and  report  : — Leaves  are  killed  by 
Sclerotium  bifrons,  and  rusted  by  3IeIa7npsora  alberlensis ;  Fomes 
igniarius  causes  premature  death  in  the  stems,  while  other  minute  fungi 
attack  injured  portions.  A.  L.  S. 


ZOOLOGY   AXD    BOTANY,    MICROSCOPY,    ETC.  243 

Pink  Disease  of  Citrus. — H.  Athertox  Lee  and  Harry  S.  Yates' 
{PhUippine  Journ.  Sci.,  1919,  14,  657-73,  7  pis.,  2  figs.).  This  disease 
is  caused  by  the  fungus,  Corticium  salmonicolor  Berk.,  which  attacks  the 
stem  and  branches  of  citrus  trees.  It  has  been  well  known  as  a  disease 
of  Hevea,  and  has  been  reported  on  Citrus^  but  not  hitherto  considered  as 
a  cause  of  serious  trouble.  The  writers  describe  its  appearance  on  the 
trees  and  their  methods  of  treating  it ;  they  also  give  recommendations 
for  the  prevention  of  further  spread.  A.  L.  S. 

Disease  of  Tomato  and  other  Plants  caused  by  a  New  Species  of 
Phytophthora. — G.  H.  Pethybridge  and  H.  A.  Lafferty  {ScL  Proc. 
Roy.  DuWn  Soc,  1919,  15,  487-505,  3  pis.).  The  root  systems  and 
lower  portion  of  the  stems  are  attacked  by  the  fungus.  It  was  success- 
fully isolated  and  grown  in  artificial  cultures  in  which  the  development 
of  sexual  organs  took  place.  These  conformed  to  the  type  of  Phytophthora 
infestans,  and  the  species  has  been  named  P.  cryptoyea.  The  fungus 
was  also  found  causing  a  similar  disease  in  Petunia,  and  may  probably 
be  the  cause  of  disease  in  Aster  and  Cheiranthus.  It  was  found  by 
inoculation  experiments  to  be  pathogenic  to  potato  and  other  plants. 
It  is  probable  that  the  oospores  of  the  fungus  hibernate  in  the  soil. 
Methods  of  control  are  outlined.  A.  L.  S. 

Botrytis  Disease  of  Galanthus. — K.  von  Keissler  {Zeitschr. 
Giirimysphys,  1917,  6,  18-27,  2  figs. ;  see  also  Ann.  3Iycol.,  1917, 15, 
160).  Botrytis  yalanthina  has  caused  considerable  damage  to  cultivated 
plants  of  Galanthus.  Lately  the  fungus  has  been  found  on  wild  plants  ; 
both  the  Botrytis  stage  and  the  sclerotium  were  found.  A.  L.  S. 

Leaf-disease  of  Tobacco  in  Roumania. — K.  Preissecker  (Fachliche 
Mitteil.  Oesterr.  Talahr.  Wien,  1916,  Heft  1-15,  4  pis.  ;  see  also  Ann. 
MycoL,  1917,  15,  161).  Whitish  or  brownish  spots  on  tobacco  leaves 
were  found  to  be  caused  by  Alternaria  Brassicee  var  tabaci.     A.  L.  S. 

Studies  with  Macrosporium  from  Tomatoes. — J.  Rosenbaum 
(Phytopathology,  1920,  10,  9-21,  2  pis.,  1  fig.).  From  observation  in 
the  field,  and  from  laboratory  cultures  the  author  distinguishes  two 
diseases  due  to  Macrosiwrium.  "Nail-head"  spots  on  fruit  stem  and 
leaves  are  caused  by  Macrosporium  Tomato  Cooke.  Immature  fruits  are 
attacked  in  transit ;  fully  ripe  fruits  seem  to  be  immune.  Another 
disease  of  stems  and  fruit  is  due  to  M.  Solani  E.  and  M.,  which  grows 
chiefiy  on  potato  tubers.  A.  L.  S. 

Market  Pathology  of  Vegetables. — K.  K.  Link  and  Max  W. 
Gardner  [Phytopathology,  1919,  9,  497-520).  The  rots  dealt  with  in 
various  vegetables  and  fruits  are  :  (1)  Slimy  soft  rot ;  all  the  bacterial 
soft  rots  attack  cabbages,  etc.  (2)  Watery  soft  rot,  due  to  Sderotinia 
Jibertiana ;  it  is  a  prevalent  vegetable  rot.  (3)  Rhizopus  rot ;  especially 
virulent  on  sweet  potatoes.  (4)  Grey  mould  rot ;  includes  rots  due  to 
Botrytis.  An  enumeration  of  different  market  produce  is  made  with 
the  rots  to  which  they  are  subject.  Other  rots  due  to  different  fungi 
are  also  touched  on.  A.  L.  S. 

R   2 


244  SUMMARY   OF   CURRENT   RESEARCHES   RELATING  TO 

Moulding  of  Snow-smothered  Nursery  Stock. — Carl  Hartley, 
Roy  G.  Pierce  and  Glenn  G.  Hahn  {Phytopathology,  1919,  9, 
521-31).  The  authors  state  that  evergreens  smothered  by  tight  pack- 
ing or  by  snow  covering  are  liable  to  injury  from  parasitic  fungi  attacking 
the  leaves.  Botrytis  cinerea  and  a  dark  sterile  mould  unidentified  are 
the  most  prevalent  causes  of  trouble.  The  best  way  found  to  treat  the 
disease  is  to  sprinkle  black  soil  on  the  snow  early  in  spring  to  hasten  the 
melting.  Nurseries  for  raising  Douglas  fir  should  not  be  established 
where  there  are  prolonged  winter  conditions.  A.  L.  S. 

Fungal  Diseases  of  the  Common  Larch. — W.  E.  Hiley  {Oxford, 

1919,  204  pp.,  73  figs.).  The  fungi  dealt  with  in  the  book  are  in  the 
following  order,  which  is  also  the  order  of  importance  : — Canker  due  to 
Dasyscypha  calycina  ;  heart-rot  caused  by  Fomes  annosiis  ;  heart-rot 
less  frequently  caused  by  Polyporus  Schiveinitzii,  Porta  vaporaria, 
Polyporus  sulphiirens  and  Torametes  Pini ;  disease  due  to  Armillan'a 
mellea  ;  and  finally  leaf  and  seedling  diseases,  the  former  being  attacked 
by  Sjjhderella  laricma,  Meria  laricis,  Hypodermella  laricis,  Melampsoridium 
betulmum,  Melampsora  tremidse,  and  the  latter  liable  to  suffer  from 
damping  off  due  to  Phytophthora  omnivora  and  Fusoma  parasiticum. 
The  list  of  diseases  is,  as  observed  by  the  author,  rather  depressing 
reading,  but  the  fungi  are  not  all  equally  virulent  or  equally  common. 
Full  descriptions  are  given  of  them  all  and  of  damage  that  results  to  the 
tissues  from  their  presence.  In  a  general  summary  at  the  end  there  is 
advice  given  as  to  the  selection  of  soil  for  larch  planting,  so  that  the 
roots  of  the  trees  may  be  well  aerated.  The  canker  of  the  larch  is 
possibly  the  most  to  be  feared,  as  the  fungus  causing  it  is  very  wide 
spread  ;  but  Ar miliar ia  mellea  does  also  much  harm  and  is  equally 
abundant,  and  is  not  confined  to  larch.  There  is  a  good  bibliography 
and  a  full  index.  A.  L.  S. 

White  Rot  Disease  of  Onion  Bulbs. — A.  D.  Cotton  {Journ.  Agric, 

1920,  26,  1093-9,  3  figs.).  The  fungus  causing  the  disease  appears  as 
a  fine  fluffy  mycehum  on  the  onions,  which  became  attacked  in  the  soil 
at  the  end  of  May  or  early  in  June,  the  visible  symptoms  of  the  disease 
being  the  wilting  and  yellowing  of  the  foliage.  At  a  further  stage 
minute  black  sclerotia  about  the  size  of  a  poppy  seed  are  formed  in  great 
numbers,  and  by  August  the  plants  are  mostly  killed.  The  sclerotia 
drop  back  into  the  soil  where  they  pass  the  winter.  In  spring  the 
sclerotium  germinates  directly,  forming  hyph^  which  infect  new  onion 
plants.  The  name  Sclerotium  cepivorum  was  given  by  Berkley  to  the 
fungus  in  1841,  and  has  been  retained  as  it  never  shows  any  Sclerotinia 
stage.  No  success  has  followed  the  use  of  soil  fungicides,  and  the  best 
way  of  combating  the  disease  is  to  starve  out  the  fungus  by  changing  the 
crop  for  a  number  of  years — eiglit  or  ten  may  not  be  too  long.     A.  L.  S. 

Leaflets  on  Plant  Diseases. — Ministry  of  Agriculture  and 
Fisheries  (Publications  Branch,  3  St.  James's  Square,  London,  S.AV.l). 
A  series  of  these  leaflets  have  recently  been  revised  and  re-written, 
and  may  be  had  free  of  charge  from  the  Publications  Branch.     They 


ZOOLOGY  AND   BOTANY,   MICKOSOOPY,   ETC.  245 

include  No.  87,  "  The  Die-back  (Cytospora)  Disease  of  Fruit-trees," 
that  attacks  the  branches;  No.  120,  "Peach  Leaf -curl"  {Exoascus 
deformans)  ;  No.  133,  "  Powdery  Mildew  of  the  Yine"  {Uncinula  necator), 
a 'leaf  disease;  No.  164,  "Potato  Leaf -curl,"  the  origin  of  which  is 
obscure  ;  No.  195,  "  American  Gooseberry  Mildew  "  {Sphserotheca  Mors- 
iwse),  a  ruildew  which  attacks  leaves  and  branches ;  No.  242,  "  Stripe 
Disease  of  Tomatoes,"  due  to  a  bacillus ;  No.  271,  "  Clover  Stem- 
rot  "  (Sderotmia  trifoUorum)  ;  No.  302,  "  Silver  Leaf  in  Fruit-trees," 
generally  caused  by  Stereum  purpureum  ;  and  No.  345,  "  The  White-rot 
Disease  of  Onion  Bulbs,"  distinguished  by  the  white  mycelium  on  the 
bulbs.  The  last-mentioned  is  a  new  publication.  All  of  the  leaflets 
are  illustrated,  and  with  the  description  of  the  disease  certain  instruc- 
tions are  sfiven  how  best  to  combat  it.  A.  L.  S, 


Lichens. 

Short  History  of  Lichenology.— Charles  C.  Plitt  (Bryologlst, 
1919,  22, 77-85).  An  account  is  given  of  lichens  in  botanical  literature 
from  the  earliest  references  onwards.  The  advance  of  knowledge  con- 
cerning these  plants  is  also  outlined  with  reference  to  their  structure  and 
to  the  development  of  the  fructifications.  The  author  gives  quotations 
from  various  lichenologists  who  have  held  strong  views  on  the  nature 
and  autonomy  of  lichens.  A.  Lorrain  Smith. 

Schedulae  of  Lichenes  Ticinenses  Exsic— Const.  Mereschkovsky 
(Ann.  Conserv.  Jard.  Bot.  Geneve,  1919,  21,  145-216).  The  author 
publishes  here  descriptions  and  notes  on  some  120  species.  They  have 
been  collected  and  issued  to  complete  another  collection  which  he  had 
undertaken,  but  of  which  much  of  the  material  had  to  be  abandoned  in 
Kazan.  A.  L.  S. 

Lichens  from  Transcaucasia. — J.  Steiner  {Ann.  Mycol.,  1919, 17, 
1-32).  A  large  series  of  lichens  sent  by  Woronoff  to  Steiner  have  been 
determined.  There  are  a  number  of  new  species.  The  greater  number 
are  common  European  species.  Steiner  remarks  on  the  number  of 
Central  European  forms,  and  also  notes  the  abundance  of  Lecanorse 
rather  than  Lecidese,  with  the  great  lack  of  Verrucarise.  He  considers 
that  certain  lichens  may  be  found  in  a  narrow  belt  all  round  the  world. 

A.  L.  S. 

Supplemental  Report  on  the  Lichens  of  Epping  Forest.— R. 
Paulson  and  Percy  G.  Thompson  {Essex  Naturalist,  1919, 19,  27-30). 
The  authors  have  added  about  twenty  species,  varieties  or  forms  to  the 
lists  of  present-day  Hchens  in  Epping  Forest  published  by  them  in  1911 
and  1913.    The  total  record  of  lichens  from  the  locality  is  now  127. 

A.  L.  S. 

Lichens  of  the  Baslow  Foray.— A.  Lorrain  Smith  {Trans.  Brit. 
Mycol.  Soc,  1920,  6,  252).  A  short  account  of  lichens  found  at  or  near 
Baslow.  The  district  is  affected  by  the  smoke  of  Sheffield,  and  the 
lichen  vegetation  is  not  abundant.  A.  L.  S. 


246  SUMMARY   OF   CURRENT    RESEARCHES    RELATING   TO 

Additions  to  Lichen  Distribution  in  North  America. — Bruce 
Fink  {Mtjcologia,  1919,  11,  296-307).  The  lichens  enumerated  were 
mostly  collected  in  Western  America  bv  the  writer  in  such  widely- 
separated  regions  as  the  islands  of  Puget  Sound,  British  Columbia,  and 
Laggan,  Alberta.  Other  collectors  sent  contributions  from  various 
western  areas.     A  bare  list  with  locality  and  habitat  appended. 

A.  L.  S. 

Contribution  to  the  Lichenographia  of  Thuringen. — Gr.  Lettau 
{Hedivigia,  1919,  61,  97-175).  Lists  of  lichens  from  Thiiringia,  the  total 
lichen  flora  for  the  region  numbering,  according  to  the  author,  about 
594.  Many  descriptive  and  biological  notes  are  added.  In  an  appendix 
there  is  a  list  of  fungi  parasitic  on  lichens.  A.  L.  S. 


Mycetozoa. 

Mycetozoa  from  Cornwall.— G.  Lister  {Journ.  Bot,  1920,  58, 
127-30).  The  account  of  Cornwall  Mycetozoa  was  partly  prepared 
by  Dr.  A.  Adams,  who  died  last  autumn.  He  was  a  keen  student  of  the 
group,  and  experimented  with  living  specimens.  Several  of  the  species 
recorded  are  new  to  England.  Other  collectors  who  contributed  notes 
are  Gr.  H.  Fox  and  J.  M.  Coon.  Eighty-two  species  and  four  varieties 
are  included,  with  locaUties  of  the  rarer  forms.     A.  Lorrain  Smith. 


Mycetozoa  found  during  the  Baslow  Foray. — G.  Lister  {Trans. 
Brit.  3Iycol,  Soc,  1920,  6,  248-52).  During  two  previous  forays  at 
Baslow  forty-four  species  of  Mycetozoa  were  found  ;  the  number  on  the 
last  occasion  was  forty-five,  and  fifteen  of  these  are  new  to  Derbyshire. 

A.  L.  S. 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  247 


MICROSCOPY. 

B.    Technique. 

Cellular  Changes  in  Cartilage  Grafts. — J.  A.  Murray  {Sci.  Rep. 
Imp.  Cancer  Remi.rch  Fund.,  1910,  6,  71).  Slow  degenerative  changes 
take  place  in  the  cells  of  cartilage  grafts.  Accompanying  the  de- 
position of  fat-globules,  which  is  probably  only  an  exaggeration  of  what 
occurs  in  undisturbed  cartilage,  there  are  nuclear  changes  regarded 
by  Murray  as  amitotic.  In  a  human  autologous  graft  irregular  achro- 
matic spindles  and  attraction  spheres  were  found  and  figured.  The 
paper  describes  the  methods  found  useful  by  the  author  for  the  study 
of  cartilage  grafts.  As  they  are  of  more  general  application  they  are 
given  here  in  greater  detail : — 

Gelatin  Slides  for  Frozen  or  Gum  Sections. — Clean  slides  are  coated 
with  a  film  of  1  p.c.  gelatin  in  distilled  water.  The  film  must  be  as 
thin  as  is  compatible  with  the  formation  of  a  continuous  layer,  spread 
with  a  glass  rod  or  slide  (like  a  blood  film).  The  slides  are  put  aside 
to  dry  and  kept  till  required.  To  fix  sections  on  slides,  immerse  the 
slide  in  water  containing  the  sections  in  a  flat  dish.  Arrange  in 
position  with  a  glass  rod,  withdraw  the  slide  with  the  sections  on  it, 
and  drain  off  the  superfluous  water.  Lower  a  wet  cigarette-paper  over 
the  sections,  and  dry  by  pressing  on  firmly  a  thick  layer  of  absorbent 
paper  (blotting  or  filter).  Strip  off  the  cigarette-paper  and  place  the 
slide  in  a  tube,  with  a  wad  of  cotton  soaked  in  commercial  formalin  at 
the  bottom.  In  two  to  four  minutes  the  gelatin  film  will  be  sufficiently 
hardened  to  keep  the  sections  in  position.  Complete  the  fixation  by 
immersing  the  slide  in  a  bottle  of  10  p.c.  formol  in  0*8  p.c.  salt  solution. 
Staining  can  now  be  carried  out  without  fear  of  the  sections  coming 
adrift,  unless  hot  mineral  acid  solutions  are  used  for  more  than  ten 
minutes. 

SalkincVs  Lead-gum  Imbeddinfj  Method  {G.R.  Soc.  Biol,  1916,  79, 
811). — An  aqueous  solution  of  gum  arable,  treated  with  lead  acetate,  is 
transformed  into  a  gel  on  exposure  to  vapour  of  ammonia.  On  addition 
of  acetic  acid  it  returns  to  the  sol  condition.  This  is  the  basis  of  the 
imbedding  method,  which  is  as  follows : — 1.  Dissolve  cherry-gum 
(white),  1  part  (by  wt.),  in  aq.  dest.,  2  parts  (by  wt.).  2.  Filter  (this 
is  usually  very  slow,  and  I  usually  use  more  water.  The  yellow  and 
brown  samples  of  gum  practically  will  not  filter).  3.  Add  to  the 
clear  solution  one-third  of  its  volume  of  liq.  plumbi  subacetatis  fort., 
containing  5  p.c.  acetic  acid.  4.  The  tissues*  to  be  cut  are  soaked  in  the 
clear  solution  so  prepared,  usually  12  hours  for  each  millimetre  in 
thickness.  They  may  be  kept  in  it  indefinitely.  5.  To  prepare  for 
cutting,  allow  the  water  to  evaporate  at  room  temperature  till  the  liquid 
is  of  the  consistency  of  thick  collodion  solution.  6.  Arrange  the  piece 
in  a  drop  of  thickened  gum  on  a  wooden  block  and  expose  to  ammonia 


248  SUMMARY   OF   C.URRENT   RESEARCHES   RELATING   TO 

vapour.  The  mass  solidifies  at  once,  and  is  ready  to  cut  in  J  to  J  hour. 
After  10  hours  the  mass  becomes  brittle  and  cuts  badly.  7.  Cut  on  the 
sliding  microtome  with  an  oblique  knife  wetted  with  1  p.c.  salt  solution 
in  distilled  water.  Transfer  the  sections  to  a  dish  of  this  salt  solution, 
i  n  which  they  spread  out.  After  an  hour  they  become  opaque  white 
and  crumble,  therefore  fix  on  the  slide  by  the  method  described  above 
before  this  happens.  8.  Remove  the  lead-gum  by  soaking  the  slides, 
with  sections  attached,  in  5  p.c.  acetic  acid  for  5-15  minutes  and  wash- 
ing in  running  water.     Stain  and  mount  as  desired. 

Hollande's  CMorocarmiii  Stain mg  Method.  —  Place  5  c.cm.  pure 
hydrochloric  acid  in  a  porcelain  dish.  Add  little  by  little  14  grm. 
powdered  carmin,  stirring  constantly  to  make  a  homogeneous  doughy 
mass.  Allow  to  digest  for  24  hours.  Add  250  c.cm.  distilled  water,, 
bring  to  the  boil,  and  keep  boiling  for  J  hour.  Filter ;  make  up  to 
180  c.cm.  with  distilled  water,  and  then  add  enough  75  p.c.  alcohol  to 
make  a  total  volume  of  200  c.cm.  Stain  sections  or  pieces  in  this  solu- 
tion for  2-24  hours.  Rinse  in  distilled  water  or  30  p.c.  alcohol. 
Immerse  in  3  p.c.  iron-alum  solution,  in  which  the  sections  become 
black  and  are  then  slowly  decolorized.  When  differentiation  is  com- 
plete, rinse  in  1  p.c.  pyridin  and  wash  under  the  tap  for  10-15  minutes. 
Counterstain  and  mount  as  desired. 


METALLOGRAPHY,  Etc. 

Differential  Crystallization  in  a  Cast  Steel  Runner. — F.  B.  Foley 
{Tlte  Iron  Age,  Dec.  18,  1919).  The  author  discusses  a  remarkable 
specimen  (some  2  in.  in  diameter)  in  which  the  microstructure  varies 
from  normal  "  ingot  "  structure,  through  "  Widmannstiittian  "  and  back 
to  "  ingot "  again.  Photomicrographs  taken  from  the  outside  towards 
the  centre  of  the  runner  are  appended. 

The  Effect  of  Initial  Temperature  upon  the  Physical  Properties 
of  Steel. — J.  H.  Andrew,  J.  E.  Rippon,  C.  P.  Milijer  and  A.  Wragg 
(Iron  and  Steel  Institute  Meeting,  May,  1920).  In  this  research  the 
effect  of  variation  in  initial  temperature  upon  the  position  of  the  resulting 
transformation  points  in  certain  Ni,  Cr  and  Ni-Cr  steels  has  been  deter- 
mined. 

The  Structure  of  some  Chromium  Steels. — J.  II.  G.  Moxypexny 
(Iron  and  Steel  Institute  Meeting,  May,  1920).  It  appears  that  the 
properties  of  austenitic  chromium  steels  are  of  great  theoretical  interest, 
since  they  show  that  martensite  is  the  first  stage  in  the  decomposition 
of  austenite. 

Note  on  the  Structural  Constitution,  Hardening  and  Tempering 
of  High-Speed  Steel  containing  Chromium  and  Tungsten. — K.  Honda 
and  T.  Murakami  (Iron  and  Steel  Institute  Meeting,  May,  1920).  The 
tempering  of  high-speed  steel  takes  place  in  two  steps,  at  approximately 
400"  0.  and  above  700°  C. 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,   ETC.  249' 

The  Distribution  of  Phosphorus  in  Steel  between  the  Points 
Acl  and  Ac3.— J.  H.  Whiteley  (Iron  and  Steel  Institute  Meeting, 
May,  1920).  Details  are  given  of  methods  for  etching  phosphoretic 
steels  for  microscopical  analysis,  and  further  work  has  been  undertaken 
on  the  subject  of  "  ghost-lines." 

Some  Defects  in  Electro-deposited  Iron. — W.  E.  Hughes  (Iron 
and  Steel  Institute  Meeting,  May,  1920).  The  author  concludes  that 
electrolytic  iron  is  prone  to  a  number  of  defects  that  make  it  unsuitable 
for  engineering  purposes.  The  view  that  its  hardness  is  due  to  the 
presence  of  hydrogen  is  called  in  question. 

Silica  Brick  from  the  Roof  of  an  Open-hearth  Furnace.— J.  E. 
Stead  {Trans.  Ceramic  Soc,  1918-19,  18,  389-98).  A  silica  brick 
from  a  Middlesbrough  furnace  had  been  reduced  in  size  from 
12  in.  X  6  in.  X  3  in.  to  12  in.  x  2|  in.  x  2|  in.  The  results  of  micro- 
scopical examination  of  this  brick  are  given. 

The  Microstructure  of  Zinc  Retorts. — A.  Scott  {Trans.  Ceramic 
Soc,  1918-19,  18,  512-15).  Two  types  of  zinc  silicate  are  present. 
The  spinel  crystals  forming  one  of  the  chief  constituents  of  used  zinc 
retorts  are  identical  with  gahnite,  ZnAloO^. 

Effect  of  Nitrogen  on  Steel.— Geoege  F.  Comstock  and  W.  E. 
Ruder  {Chemical  and  3Ietallurgical  Engineering,  March  3,  1920,  22, 
No.  9).  A  resume  of  the  important  literature  on  amount  of  nitrogen  in 
various  classes  of  steels,  its  method  of  occurrence  and  effect  on  physical 
properties,  together  with  some  recent  experiments  on  its  action  during 
heat  treatment. 

Nature  of  the  Defects  revealed  by  the  Deep  Etching  of  Trans- 
versely-fissured Rails. — Henry  S.  Rawdon  {Chemical  and  Metal- 
lurgical Engineering,  March  17, 1920,  22,  No.  11).  Microscopic  studies 
which  show  that  "gashes"  developed  by  deep  etching  of  polished 
surfaces  correspond  to  tightly  closed  intracrystalline  cracks  ;  they  may 
be  discovered  by  dipping  a  magnetized  specimen  into  a  suspension  of  fine 
iron  dust. 

Genesis  of  Ferrite. — Federico  Giolitto  {Chemical  and  Metal- 
lurgical Engineering,  April  21,  1920,  22,  No.  16).  Contrary  to 
commonly  accepted  ideas,  the  ferrite  in  hypo-eutectoid  steels  is  not 
extruded  as  a  shell  to  the  outside  of  austentic  kernels,  but  exists  as  an 
aggregation  of  crystals  essentially  discontinuous  at  the  low-carbon  nuclei 
of  solid  solution  grains. 

Copper  and  Magnetite  in  Copper  Smelter  Slags. — Charles  G. 
Maier  and  G.  D.  Yan  Arsdale  {Chemical  and  Metallurgical  Engineer- 
ing, June  16,  1920,  22,  Nos.  24-5).  Chemical  and  microscopic 
examination  of  a  series  of  representative  slags,  showing  how  copper 
losses  occur,  the  relation  of  magnetite  to  copper  loss,  the  behaviour  of 
converter  slags  in  reverberatory  furnaces,  and  suggestions  for  reducing 
copper  slag  losses. 


250 


PEOCEEDINGS    OF    THE    SOCIETY. 


AN   ORDINARY  MEETING 

OF  THE  Society  was  held  at  No.  20  Hanover  Square,  \Y.,  on 
Wednesday,  March  17th,  1920,  Professor  John  Eyre, 
President,  in  the  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirmed,  and 
signed  by  the  President. 


The  nomination  papers  were  read  of  four  Candidates  for  Fellowship. 


New  Fellows.— The  following  were  elected  Ordinary  Fellows  of  the 
Society : — 

Mr.  George  Frederick  Bates,  B.A.,  B.Sc. 

Mr.  Joseph  Graham,  B.Sc. 

Mr.  Kennett  Knight  Hallowes,  M.A.,  F.G.S.,  A.R.S.M., 

A.Inst.M.M. 
Mr.  William  Jabez  Ireland, 
Captain  Ralph  G.  A.  Thorne.  B.A. 
Miss  Evelyn  J.  Welsford,  M.B.E.,  F.L.S. 


Donations  were  reported  from  : — 
Mr.  P.  E.  Radley,  F.Z.S.— 

"  Catoptricae   et    Dioptricae   Sphaericae  Elementa "  (Davide 

Gregorio,  1G95). 
"  Dioptrische  Untersuchungen  "  (C.  F.  Gauss,  1841). 
Messrs.  Methuen  &  Co.,  Ltd. — 
"  Iron  Bacteria  "  (Dr.  Ellis). 

On   the   motion   of   the  President,  hearty  votes  of  thanks  were 
accorded  to  the  donors. 


Mr.  E.  J.  Sheppard  exhibited  a  slide — mitosis  in  hyacinth  root-tips 
^showing  marked  differentiation  in  the  staining  of  the  chromosomes. 

Dr.  Drew  exhibited  slides  showing  the  Golgi  apparatus  in  the  cells 
of  the  onion  root  and  in  the  epididymus  of  the  rat. 

On  the  motion  of  the  President,  hearty  votes  of  thanks  were  accorded 
to  Mr.  Sheppard  and  Dr.  Drew. 


PEOCEEDINGS   OF   THE   SOCIETY.  251 

Dr.  C.  Da  Fano  gave  a  demonstration  of  the  Gol^i  Internal  Appa- 
ratus in  Nervous  and  other  Tissues.  (Details  of  this  demonstration  will 
be  found  on  pages  157-61  of  the  present  issue  of  the  Journal.) 

Dr.  Murray  congratulated  Dr.  Da  Fano.  For  himself  the  particular 
interest  was  that  although  they  all  had  a  prejudice  against  metallic 
impregnation  methods,  they  must  recognize  that,  by  the  application 
of  the  new  methods,  the  Golgi  apparatus  presented  a  characteristic 
appearance  in  each  of  the  tissues.  Although  the  appearances  differed 
according  to  the  staining  method,  it  was  very  suggestive  that  they  had 
there  a  real  constituent  of  the  cell.  "What  its  function  was  or  what  it 
was  for  it  was  difficult  to  determine. 

Mr.  E.  J.  Sheppard  said  that  in  Professor  Schaefer's  "  Essentials  of 
Histology  "  was  shown  an  enlarged  figure  of  an  animal  cell  in  which 
were  seen  the  radiating  structures,  and  these  were  described  as  tropho- 
plasm  or  canula  which  might  be  demonstrated  or  not  according  to  the 
method  of  fixation.  The  canula  could  not  be  seen  unless  the  prepara- 
tion was  suitably  fixed.  He  had  many  times  seen  the  canula  in  various 
structures  in  the  unfixed  and  the  lightly-fixed  preparations,  and  he  was 
not  sure  that  he  had  not  also  seen  them  by  the  aid  of  dark-ground 
illumination.  He  was  not  an  upholder  of  the  precipitate  method  as 
applied  to  silver  impregnations.  If  the  canals  did  exist  it  was  easy  to 
precipitate  upon  them  and  show  the  structure.  If  they  existed  there 
was  a  very  wonderful  field  for  research.  At  present  he  looked  upon 
them  with  some  scepticism.  He  warmly  congratulated  Dr.  Da  Fano 
upon  his  beautiful  exhibits. 

Dr.  Gatenby  thanked  the  Society  for  the  interest  it  had  shown  in 
the  discussions  on  the  Golgi  apparatus  and  mitosis.  He  had  attended  a 
good  many  meetings,  and  had  met  with  a  deal  of  scepticism.  He  was 
glad  to  hear  Mr.  Sheppard  now  admit  that  there  might  be  such  a  thing 
as  the  Golgi  apparatus.  It  had  been  seen  intra  vitam  in  tissue  cultures 
and  in  the  ovotestis  and  ganglion  cells  of  the  snail.  He  had  lately  been 
using  Dr.  Da  Fano's  method,  and  some  of  his  best  results  had  been 
obtained  with  this  cobalt  nitrate  method. 

Dr.  Drew  drew  attention  to  two  exhibits  that  were,  being  shown. 
They  were  from  an  onion  and  a  rat.  The  chief  interest  lay  in  the  fact 
that  the  specimens  had  been  fixed  by  Dr.  Da  Fano's  method,  cut  with  a 
freezing  microtome,  and  stained  with  iron-hasmatoxylin. 

The  President  said  that  the  Society  was  much  indebted  to  Dr. 
Da  Fano  and  to  the  other  observers  who  had  taken  part  in  the  discussion, 
which  had  brought  out  many  important  points.  He  moved  from  the 
Chair  that  the  best  thanks  of  the  Meeting  be  accorded  to  Dr.  Da  Fano. 

This  was  carried  by  acclamation. 


Mr.  T.  E.  Wallis  read  a  paper  on  "  The  Lycopodium  Method  of 
Quantitative  Microscopy,"  which  was  illustrated  by  lantern  slides  and 
exhibits.  The  paper  is  printed  in  the  present  issue  of  the  Journal  (see 
pages  169-78). 

A  discussion  followed,  in  which  Mr.  Barnard,  Mr.  Sheppard,  and 


252  PKOCEEDINGS   OF  THE   SOCIETY. 

Mr.  Blood  took  part,  after  which  a  hearty  vote  of  thanks  was  accorded 
to  Mr.  Wallis  for  his  paper. 

A  vote  of  thanks  was  accorded  to  Messrs.  Hawksley  and  Sons  for  the 
loan  of  fifteen  microscopes. 


The  President  announced  that  the  next  Meeting  of  the  Biological 
Section  would  be  held  on  April  7,  when  there  would  be  a  further  dis- 
cussion on  Dr.  Tierney's  communication,  "The  Bacterial  Flora  of 
Water." 

The  business  proceedings  then  terminated. 


AN  ORDINARY  MEETING 


OF  THE  Society  was  held  at  No.  20  Hanover  Square,  W.,  on 
Wednesday,  April  21st,  1920,  Mr.  A.  N.  Disney,  Vice- 
President,  IN  THE  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirmed,  and 
signed  by  the  Chairman. 


The  Nomination  Papers  were  read  of  six  Candidates  for  Fellowship. 


New  Fellows.— The  following  were  elected  Ordinary  Fellows  of  the 
Society : — 

Mr.  Corrado  Da  Fano,  M.D.,  L.D. 
Mr.  T.  D.  Tuton  Hall. 
Mr.  Morris  Charles  Lamb,  F.I.C. 
Mr.  Duncan  James  Reid,  M.B.,  CM. 


The  following  papers  were  read  in  title,  and  it  was  announced  that 
they  would  be  published  in  the  Journal ; — 

Mr.  B.  L.  Bhatia,  M.Sc,  F.Z.S.— 

"  Notes  on  Fresh- water  Ciliate  Protozoa  of  India." 

Mr.  Aubrey  H.  Drew,  D.Sc. — 

"  A  Preliminary  Note  on  the  Golgi  Apparatus  in  Plants." 

Mr.  J.  Bronte  Gatenby,  B.A.,  B.Sc,  D.  Phil.,  and  Mr.  J.  H.  Woodger, 
B.Sc— 

"  On  the  Relationship  between  the  Formation  of  Yolk  and  the 
Mitochondria  and  the  Golgi  Apparatus  during  Oogenesis." 


The  business  proceedings  then  terminated. 


PROCEEDINGS   OF   THE   SOCIETY.  253 

On  the  same  evening  in  the  Lecture  Hall  was  held  a  General 
Discussion  on 

The  Mechanical  Design  and  Optics  of  the  Microscope. 

Professor  John  Eyre,  M.D.,  M.S.,  etc.,  President  of  the  Royal 
Microscopical  Society,  opened  the  proceedings  with  a  short  Address. 

Mr.  J.  E.  Barnard  gave  a  "  General  Survey,"  which  was  followed  by 
■abstracts  of  the  following  papers  on  Ihe 

Mechanical  Design  of  the  Microscope. 

(a)  General. 

Professor  F.  J.  Cheshire,  C.B.E.,  "  The  Mechanical  Design  of 
Microscopes." 

Mr.  Conrad  Beck,  C.B.E.,  "The  Standard  Microscope." 

Mr.  F.  W.  Watson  Baker,  "  Progress  in  Microscopy  from  a  Manu- 
facturer's Point  of  View." 

Mr.  Powell  Swift,  "  A  New  Microscope." 

Sir  Robert  Hadfield,  Bart.,  D.Sc,  F.R.S.,  President  of  the  Faraday 
Society,  then  took  the  Chair  during  the  reading  of  the  abstracts  of  the 
following  papers  : — 

(b)  Metallurgical. 

Dr.  W.  Rosenhain,  F.R.S.,  "The  Metallurgical  Microscope." 
Professor  Cecil  H.  Desch,  D.Sc,  "  The  Construction  and  Design 

of  Metallurgical  Microscopes." 
Mr.  E.  F.  Law,  "  The  Microscope  in  Metallurgical  Research." 
Mr.  H.  M.  Sayers,  "  Illumination  in  Micro-metallography." 

(c)  Petrological. 

Dr.  J.  W.  Evans,  F.R.S.,  "  The  Requirements  of  a  Petrological 
Microscope." 

A  discussion  followed  on  the  foregoing  papers. 

Mr.  Robert  S.  Whipple,  President  of  the  Optical  Society,  then  took 
the  Chair  during  the  reading  of  abstracts  of  the  following  papers  on  the 

Optics  of  the  Microscope. 

Professor  A.  E.  Conrady,  "  Microscopical  Optics." 

Dr.  H.  Hartridge,  M.A.,    "An  Accurate  Method  of  Objective 

Testing." 
Mr.  H.  S.  Ryland,  "  The  Manufacture  and  Testing  of  Microscope 

Objectives." 
Mr.  F.  Twyman,  "  Interferometric  Methods." 

A  discussion  followed  on  the  foregoing  papers. 


A  full  report  of  the  proceedings  will  be  published  in  connexion  with 
the  report  of  the  Symposium  held  on  January  14,  1920. 


254  PROCEEDINGS  OF   THE   SOCIETY. 


AN   ORDINARY  MEETING 

OF  THE  Society  was  Held  at  20  Hanover  Square,  W.,  on 
Wednesday,  May  19th,  1920,' Professor  John  Eyre,  Presi- 
dent, IN  the  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirraed,  and 

signed  hj  the  President. 


The  nomination  papers  were  read  of  three  candidates  for  Fellowship. 


New   Fellows.— The  following  were  elected  Ordinary  Fellows  of 
the  Society  : — 

Mr.  Harold  Brum  well. 

Mr.  Reginald  Henry  Marchment. 

Le  Yicomte  de  Sibour,  F.Z.S. 

Mr.  Charles  F.  Sonntag,  M.D.,  Ch.B. 

Mr.  Donald  Sutherland,  M.A. 

Mr.  William  Turner. 


Donations  were  reported  from  : — 

Mr.  G.  T.  Harris— 

A  Collection  of  Slides  of  Bryophyta. 
Dr.  E.  J.  Spitta— 

'•  Microscopy  "  (New  Edition). 
Messrs.  W.  Wesley  and  Son — 

"  Common  Diatoms  "  (T.  K.  Mellor). 

On  the  motion   of  the   President,  hearty  votes  of   thanks  were 
accorded  to  the  donors. 


Pond-Life  Exhibition. — The  President  then  called  upon  ]\Ir. 
Scourfield  to  make  some  observations  on  the  Annual  Exhibition  of 
Microscopic  Pond-Life  which  had  been  arranged  by  Fellows  of  the 
Society  and  Members  of  the  Quekett  ^licroscopical  Club. 

Mr.  Scourfield  said  that  it  bad  been  his  privilege,  in  connexion  with 
several  previous  Pond-Life  exhibitions,  to  call  attention  to  some  of  the 
special  problems  which  could  be  studied  only  by  observation  of  the 
living  organisms,  such  problems,  for  instance,  as  the  movements  of  pond- 
life  organisms  and  the  correlation  of  their  structure  to  particular  modes 
of  life.  He  proposed  that  evening  to  refer  briefly  to  yet  another  matter 
which  could  only  be  satisfactorily  approached  in  the  same  way,  namely, 
the  colour  of  microscopic  aquatic  organisms.  Mr.  Scourfield  then 
alluded  to  some  of  the  commoner  colours  presented  by  such  organisms. 


PKOCEEDINGS    OF   THE    SOCIETY.  '255 

directing  special  attention  to  the  animal  types  of  a  green  colour.  In 
most  cases  these  green  animals  were  found  to  owe  their  characteristic 
colour  to  the  presence,  just  under  the  ectosarc  or  ectoderm,  of  symbiotic 
algte  usually  known  as  zoochlorell^.  Such  cases  occurred  among  the 
Rhizopoda  in  some  species  of  Dlfflugia,  etc.  ;  among  the  Heliozoa  in  one 
species  of  Raphidiophrys  ;  among  the  Ciliata  in  species  of  Stentort  Para- 
?nsecium,  Vorticella^  Ophrydium,  etc. ;  among  the  Hydrozoa  in  Hydra 
viridis,  H.  igneus,  etc. ;  and  among  the  Turbellaria  in  DalyelJia  viridis, 
etc.  It  was  evident  that  a  number  of  interesting  questions  arose  out  of 
this  peculiar  association  of  animals  and  plants,  the  solution  of  which 
would  almost  certainly  yield  results  of  fundamental  biological  import- 
ance. 

Closely  connected  with  the  colour  of  organisms  was  the  mode  of  its 
distribution  over  the  surface  of  the  body.  When  this  was  not  uniform 
it  usually  gave  rise  to  some  kind  of  pattern,  and  this  was  an  important 
but  very  obscure  subject  upon  which  a  good  deal  of  light  could 
undoubtedly  be  thrown  by  a  study  of  small  aquatic  creatures  in  which 
colour  patterns  occurred  in  their  simplest  forms. 

Proceeding  to  refer  in  detail  to  the  actual  exhibits,  Mr.  Scourfield 
made  special  mention  of  the  abnormal  specimens  of  Simocephalus  vetidus, 
shown  by  Mr.  Cannon,  which  had  been  produced  by  feeding  upon  a 
species  of  Chlamydomonas .  These  were  similar  to  those  described  by 
Prof.  Agar  in  an  important  paper  in  the  Transactions  of  the  Royal 
Society  on  the  inheritance  of  acquired  characters  in  certain  species 
of  Entomostraca,  etc. 

On  the  motion  of  the  President,  a  hearty  vote  of  thanks  was 
accorded  to  the  Members  of  the  Quekett  Microscopical  Club,  and  to  the 
Fellows  of  the  Royal  Microscopical  Society  who  had  kindly  exhibited 
specimens,  and  to  Mr.  Scourfield  for  his  remarks. 


The  President  announced  that  the  next  Meeting  of  the  Biological 
Section  would  be  held  on  June  2,  when  Mr.  Scourfield  would  read  a 
communication  on  "  Zoochlorellae." 


The  business  proceedings  then  terminated. 


List  of  Pond-Life  exhibits — 

Mr.  A.  J.  Bowtell   .  .      Vorticella  sp. 

^Ir.  H.  G-.  Cannon  .     Simocephalus  vetuhis,  showing  abnormality, 

similar  to  that  described  by  Prof.  Agar 
in  Trans.  Roy.  Soc,  produced  by  feeding 
on  a  species  of  Chlamydomonas. 

Mr.  F.  W.  Chipps  .  .    LojJhopiis  cry  stall  i/ms^ahoBatrachosjwrmiim. 

Mr.  H.  GouUee       .  .     Larvae    of    Tamjpus    just    emerging,  also 

young  newt. 

Mr.  C.  E.  Heath     .         .     Lophopus  crystalUnus. 


256 


PROCEEDINGS   OF   THE   SOCIETY. 


Mr.  T.  H.  Hiscott  . 
Mr.  J.  T.  Holder    . 

Mr.  H.  E.  Hurrell  . 
Mr.  J.  J.  Jackson   . 
Mr.  H.  J.  Lawrence 
'Dr.  J.  Rudd  Leeson 
Mr.  W.  J.  Magenis. 
Mr.  E.  R.  Martin    . 
Mr.  E.  K.  Maxwell . 
Mr.  J.  C.  Mjles       . 
Mr.  E.  R.  Newmarch 
Mr.  R.  Paulson 
Mr.  F.  J.  W.  Plaskitt 
Mr.  J.  Richardson  . 
Mr.  W.  Russell 
Mr.  D.  J.  Scourfield 

Mr.  R.  S.  W.  Sears. 

Mr.  C.  J.  H.  Sidwell 


Mr.  A.  E.  Smith  . 
Mr.  B.  J.  Thomas  . 
Mr.  W.  R.  Traviss  . 
Mr.  a.  AV.  Watts  . 
Mr.  H.  C.  Whitfield 
Mr.  S.  R.  Wycherley 


Acanthocystis  turfacea. 

Closterium     sp.,    showing     movement     of 

granules  in  terminal  vesicles. 
Lophopus  crystaUinus. 
Euglena  sp.,  Chlamydomas  sp.,  etc. 
31  icr aster ias  trimcata. 
Spirillum,  Euglena,  etc. 
Bacillus  coli,  etc. 
Hydra  fusca. 
CEcistes  stygis. 
Stephanoceros  eichhornii. 
Plumatella  rqmu  and  Melicerta  ringens. 
Spiroggra  longata  and  Ulothrix  variabilis. 
Euglena  spirogyra. 
Cothurnia  imberbis. 
Melicerta  ringens. 
Hydra  fusca,  showing  brown  bodies  which 

give  the  colour  to  the  animal. 
Amoeba  ^woteus,   also    Hydra   viridis  and 

Volvox  globator. 
Hydra  viridis,  showing  nematocysts  and  the 

symbiotic    algal   cells,   which   give   the 

green  colour  to  the  animal. 
Larva  of  beetle  Acilius  sulcatus. 
Stephanoceros  eichlwrnii. 
Anacharis,  showing  circulation. 
Closteriwn  sp. 
Closterium  sp. 
Floscularia    campanulata    and     Philodina 

aculeata. 


JOURNAL 

OF    THE 

ROYAL    MICROSCOPIC  iL    SOCIETY 

SEPTEMBER,  1920. 


TKANSACTIONS   OF   THE   SOCIETY. 


VII. — Notes  on  Fresh-water  Ciliate  Protozoa  of  India. 

By  B.  L.  Bhatia,  M.Sc,  F.Z.S.,  F.K.M.S.,  Assistant  Professor  of 
Zoology,  Government  College,  Lahore. 

{Read  April  21,  1920.) 

Very  little  work  has  been  done  so  far  on  the  fresh-water  Protozoan 
fauna  of  India.  Up  to  1889,  the  year  of  publication  of  Biitschli's 
work  on  Protozoa  {6)*  practically  the  only  record  of  fresh- water 
forms  was  based  on  the  work  of  H.  J.  Carter,  who  studied  these 
forms  in  Bombay  towards  the  middle  of  the  last  century,  and 
published  a  number  of  papers  (7,  8,  9,  10).  In  1862  J.  Mitchell 
contributed  a  short  note  from  Madras  (17).  From  1869  to  this 
date  nobody  appears  to  have  seriously  taken  up  the  study  of 
fresh-water  Ciliates  in  India,  and  I  am  unable  to  find  any  record 
of  these  interesting  organisms  from  India,  except  for  a  paper  by 
Annandale  (4)  and  another  by  Ghose  (13). 

In  a  previous  paper  (S)  the  writer  recorded  a  number  of  species 
of  Ciliates  occurring  in  fresh  water  collected  from  ditches,  ponds, 
etc.,  in  and  about  Lahore,  which  are  enumerated  below  for  ready 
reference : — 

Holophyra  mdica  Bhatia.  Loxophi/lhcm   fasciola    (Ehrbg.) 
Urotricha    globosa    Schewia-  CI.  &  L.,   subsp.  punjabensis 

kofif.  Bhatia. 

Enchelys  arcuata  Clap.  &  L.  Nassula  stromphii  Ehrbg. 

LaG7'ymaria    vermicularis  Triclioda  pura  Ehrbg. 

Elirbg.  Colpoda  cucullus  Ehrbg. 

Goleps  hirtus  0.  F.  Miill.  Paramecium  caudatum  Ehrbg. 

Didinium  nasutum  Stein.  Spirostomum  ambiguum  Ehrbg. 

*  The  italic  figures  within  brackets  refer  to  the  Bibliography  at  end  of  the 
paper. 

S 


258       *  Transactions  of  the  Society. 

The  study  of  the  fresh- water  Ciliates  of  this  locality  has  been 
continued,  and  the  forms  met  with  are  recorded.  Very  little  work 
having  been  previously  done  on  the  fresh- water  Protozoan  fauna  of 
India,  most  of  the  forms  encountered  are  being  recorded  for  the 
first  time  from  any  part  of  India.  The  best  thanks  of  the  writer 
are  due  to  Lieut.-Colonel  J.  Stephenson,  D.Sc,  I.M.S.,  Principal 
and  Professor  of  Zoology,  Government  College,  Lahore,  for  the 
guidance  and  encouragement  he  lias  always  received,  and  for 
great  assistance  in  obtaining  a  number  of  books  and  periodicals 
dealing  with  Protozoa,  but  for  which  the  work  could  not  have 
been  undertaken. 

Lahore  is  situated  in  the  plains  of  the  Punjab  (India,  latitude 
31°  34'  K,  longitude  74°  21'  E.,  height  above  sea-level  706  feet), 
and  experiences  extremes  of  temperature  conditions  in  its  hot  and 
cold  seasons.  The  principal  rainfall  of  the  year  takes  place  in  the 
months  of  July  and  August,  and  this  is  followed  by  a  period  of 
drought,  in  which  most  temporary  collections  of  water  dry  up. 
The  majority  of  the  pools  examined  were  only  temporary  collec- 
tions of  water  after  rains,  some  being  only  a  few  centimetres  deep. 
Samples  of  water  from  some  of  the  artificial  ponds,  such  as  the 
tanks  in  the  Shalamar  Gardens  and  the  duck-ponds  in  the  Zoo,  have 
also  been  examined.  Protozoan  life  seems  most  abundant  at  Lahore 
in  the  summer  season,  i.e.  from  May  to  September.  The  specimens 
obtained  were  mostly  studied  in  the  living  condition  either  under 
a  small  cover  glass  or  as  hanging-drop  preparations,  aud  as  a  rule 
a  preliminary  examination  of  a  sample  of  water  was  made,  with 
the  aid  of  a  centrifuge,  on  the  same  day  that  the  water  was 
collected.  For  slowing  the  movements  of  rapidly  moving  forms, 
the  mucilage  obtained  by  soaking  Ispaglvul  seeds  (seeds  of  Flantago 
ovata)  was  found  to  give  very  satisfactory  results.  This  mucilage 
can  be  readily  obtained  in  varying  degrees  of  consistency,  and  has 
the  further  advantage  of  being  perfectly  transparent.  It  can  be 
added  directly  on  the  slide  to  tlie  drop  of  water  containing  the 
Ciliates,  or  the  seeds  are  spread  at  the  bottom  of  the  tube  in  a  layer 
about  1-2  cm.  high,  and  the  culture  containing  the  Ciliates  poured 
on  to  them  to  the  height  of  8-10  cm.,  when  in  a  day  or  two  by 
the  diffusion  of  the  mucilage  into  the  culture  a  proper  consistency 
is  obtained. 

Of  the  reagents  commonly  used,  I  have  employed :  (1)  for 
fixing,  concentrated  solution  of  corrosive  sublimate,  liot  or  cold ; 
sublimate  alcohol  (concentrated  watery  solution  of  corrosive,  2  parts, 
90  p.c.  alcohol,  1  part) ;  or  vapour  of  4  p.c.  osmic  acid  solution — 
all  of  which  gave  good  results ;  (2)  for  rendering  cilia  distinct,  a 
1  p.c.  solution  of  alum ;  and  (3)  for  staining,  ])rincipally  acetic- 
methyl  green,  washing  it  out  with  water  to  which  a  few  drops  of 
liquor  ammonia?  have  been  added. 

The  forms  met  with  are  recorded  below,  with  brief  notes  on 


Notes  on  Fresh-iuater  Ciliate  Protozoa  of  India.  259 

them.  Eegarding  measurements  of  size,  the  terms  very  small, 
small,  of  medium  size,  large,  and  very  large  are  used  for  dimen- 
sions as  defined  by  Schewiakoff.  The  writer  has  recorded  his  own 
measurements  only  where  they  differ  markedly  from  those  usually 
iriven. 


HOLOTRICHA. 

Family  Holopheyina  Perty. 
Genus  Spathidium  Dujard. 
Spathidium  spathula  0.  F.  Miill,  var.  moniliforme  var.  nov. 

Found  in  large  numbers  in  stagnant  water  from  a  drain  (Septem- 
ber). The  animals  may  be  referred  to  Spathidium  s'pathula 
0.  F.  Mull.,  inasmuch  as  the  body  is  flask-shaped,  flexible,  though 
not  very  contractile,  the  anterior  end  narrower  than  the  middle  of 
the  body,  obliquely  truncate,  and  occupied  almost  completely  by 
the  narrow  and  elongated  slit-like  mouth.  The  margins  of  the 
oral  portion  are  padded.  The  general  surface  of  the  body  appears 
to  be  striate.  The  cytoplasm  is  granular,  the  anterior  portion  of 
the  body  being  somewhat  clearer.  The  contractile  vacuole  is  single 
and  situated  near  the  posterior  end.  The  ciliation  is  uniform, 
except  that  the  cilia  rouod  the  anterior  end  are  slightly  longer. 
The  movements  of  the  animal  are  slow,  the  anterior  part  of  the 
body  occasionally  bending  slightly. 

The  form  met  with  however  differed  from  the  type  in  its  very 
much  smaller  size  and  the  character  of  the  nucleus.  The  animals 
measured  lOS/x  by  20yLt,  instead  of  the  usual  size,  which  is  men- 
tioned as  180-240  yLt.  The  macronucleus  consists  of  a  long  chain  of 
small  beads,  and  is  bent  upon  itself.  In  the  generic  characters 
given  in  Biitschli  {6)  the  nucleus  is  said  to  be  round  to  elongated 
and  rosary- shaped,  but  in  the  figure  of  S.  spathula  is  shown  as 
consisting  of  three  large  beads  only.  E.  Andre  {3)  has  described 
under  the  name  of  >S'.  spathula  var.  plurinudeata  a  form  contain- 
ing a  large  number  of  separate  rounded  nuclei.  The  present  form 
differs  from  the  latter  in  that  these  small  nuclei  are  not  regularly 
scattered  but  are  parts  of  an  elongated  rosary,  which  is  bent  upon 
itself.  Hence  the  form  may  be  said  to  belong  to  a  new  variety, 
for  which  the  name  var.  moniliforme  is  proposed. 

Genus  Prorodon  Ehrbg. 
Prorodon  teres  Ehrbg. 

Specimens  of  this  form  were  found  in  great  abundance  in  a 
collection  ot   rain-water  which  had  been  standing  for  less  than  a 

s  2 


260  Transactions  of  the  Society. 

week  on  the  roadside  near  the  Chaiiburji  grounds  in  August. 
Every  drop  contained  several  specimens.  The  animals  were 
63-84  yLt  by  45  yLt  in  size,  and  contained  yellow  or  brown  alga?. 
The  form  however  differed  from  the  one  figured  in  Lang  {15)  in 
certain  important  respects.  The  macronucleus,  which  is  large  and 
sphaeroidal,  is  situated  in  the  anterior  half  of  the  body,  and  is  carried 
about  in  the  granular  endoplasm.  When  stained  with  acetic  methyl 
green  it  is  found  to  be  of  the  granular  type,  and  a  small  rounded 
micronucleus  is  placed  on  its  surface.  The  mouth  is  anterior  and 
terminal,  but  the  pharynx  does  not  extend  as  far  back  as  there 
figured.  The  animals  were  examined  after  slowing  their  move- 
ments by  the  mucilage  obtained  from  Ispaghul  seeds  (seeds  of 
Planiago  ovaia),  and  the  pharynx  studied  in  a  dilated  condition. 
It  was  found  to  be  12  /-t  in  length,  and  measured  9  /z  across  at  its 
anterior  end,  becoming  somewhat  narrower  posteriorly.  The  fascicle 
of  rods  in  the  pharynx  was  distinct,  and  eight  rods  could  be  counted 
in  the  surface  presented  to  view.  The  cilia  on  either  side  of  the 
mouth  were  slightly  longer  than  over  the  rest  of  the  body.  The 
contractile  vacuole  is  single  and  situated  near  the  posterior  end  of 
the  body,  though  in  one  specimen,  which  was  about  to  disintegrate^ 
two  subsidiary  ones  were  also  seen  situated  on  one  side  of  it. 

Family  Amphileptina  Biitschli. 

Genus  Loxophyllum  Duj. 

Loxophyll'iim  fasciola  Ch  &  Lachm. 

Specimens  belonging  to  this  typical  form  were  found  in  large 
numbers  in  September  in  water  from  a  draiu.  Body  small,  63  //. 
in  length,  greatest  width  31  yu,. 

Genus  Loxodes  (Ehrbg.)  01.  &  Lachm. 

Loxodes  rostrum  (O.F.M.)  Eln-bg.  (—  Pelicida  rostrum  Duj.). 

Specimens  referable  to  this  species  were  found  in  water  from  a 
pond  in  the  Lawrence  Gardens  (August).  The  usual  size  recorded 
for  the  species  by  Eyferth  (/,?)  is  450-580 /x,  but  the  specimen& 
found  in  Lahore  were  very  much  smaller.  One  specimen  measured 
126/1,  by  44 /i,  another  150//,  by  63//,.  This  agrees  fairly  closely 
with  the  minimum  size  as  recorded  in  Kent  {14)  (yJ^,  in.),  or 
Pritchard  {17)  {^\^  in.).  Ciliation  uniform,  marginal  cilia  sliort, 
fine,  and  close  set,  the  cilia  bordering  the  adoral  groove  being 
somewhat  larger.  The  mouth  is  situated  in  the  concave  border  of 
the  proboscis,  which  measured  32  ^  in  one  specimen  and  42  fi  in 
the  other.  Body  flexil)le,  but  persistent  in  form,  with  the  anterior 
extremity  curved  slightly  to  the  left;  posterior  end  bluntly  pointed 


Notes  on  Fresh-water  Ciliate  Protozoa  of  India.  261 

and  also  curving  slightly  inwards  in  the  same  direction.  The 
endoplasm  is  granular  and  vacuolated,  and  numerous  chloroplasis 
are  scattered  in  it,  the  colour  of  the  part  of  the  body  free  from 
them  being  greyish.  Macronuclei  are  numerous,  spherical,  of  the 
vesicular  type,  and  irregularly  distributed  in  the  posterior  three- 
fourths  of  the  body,  but  the  connecting  cord-like  filament  or 
funiculus  could  not  be  observed.  The  micronuclei  also  were  not 
made  out. 

There  was  a  single  contractile  vacuole  situated  about  the  middle 
of  the  body,  and  a  row  of  numerous  very  much  smaller  vesiculffi 
arranged  alonj:j  the  left  border  which  were  non-contractile. 


Family  Chilifera  Biitschli. 

Genus  Glaucoma  Ehrbg. 

Glaucoma  lyijriformis  Stein.  (?) 

The  animals,  which  I  have  referred  witli  some  hesitation  to  this 
species,  were  found  in  August  in  water  from  a  pond  in  Lawrence 
Gardens,  and  measured  60  yit  by  30  \x.  The  form  of  the  body  is 
somewhat  pyriform,  ciliation  is  uniform  though  very  fine  ;  cilia  over 
the  general  surface  w^ere  distinctly  visible  with  ^^  in.  oil  immer- 
sion and  No.  6  compensating  ocular,  those  along  the  margin  being 
equally  fine  and  situated  rather  apart  from  one  another.  The 
mouth  is  situated  about  9  /x  from  the  anterior  end,  and  the  oral 
fossa  is  provided  with  an  undulating  membrane  arising  from  both 
margins,  with  a  finger-shaped  projection  protruding  from  the  middle. 
The  macronucleus,  which  is  of  the  granular  type,  is  ovoidal  and 
situated  about  the  middle,  the  small  micronucleus  lying  close  to  its 
posterior  edge.     Tlie  contractile  vacuole  is  near  the  middle. 

Genus  Colindiuni  Stein. 
Goljpidium  colpoda  Stein. 
In  infusions  of  dry  leaves. 

Family  Paka^mecina  Duj. 

Genus  Paramecium  O.F.M. 

Paramecium  hursaria  Ehrbg. 

In  pond  water.  Size  84 /a  by  40 /^  to  95 /x  by  42  jx.  Anterior 
end  obliquely  truncate  ;  contractile  vacuoles  two,  spherical  in  some 
specimens  and  stellate  in  others.  Macronucleus  kidney-shaped. 
Mostly  with  Zoochlorellte. 


262  Transactions  of  the  Societij. 

HETEEOTRICHA. 

Family  Stentoeina  Stein. 

Genus  Stentor  Oken. 

Stentor  sp. 

Specimens  belonging  to  Stentor  sp.  were  once  found  in  a  pond 
near  Chhota  Ravi  river,  but  the  specimens  were  not  identified. 

Family  Halterina  C].  &  Laclim. 

Genus  Halteria.  Duj. 

Halteria  grandinella  0.  F.  Miill. 

Found  in  water  in  a  pond  in  Lawrence  Gardens  in  the  month 
of  August.  The  specimens  exhibited  the  usual  movements  so 
characteristic  of  the  species,  Form  somewhat  spherical,  with  a 
small  triangular  depression  at  the  anterior  end,  with  a  small 
number  (six  or  seven)  of  stiff  cilia  at  the  anterior  end,  and  a  few 
slender  bristles  from  the  central  region  of  the  body.  Macronucleus 
kidney-shaped.  Contractile  vacuole  in  the  anterior  half  of  the 
body.     Size  about  25  yit. 

HYPOTRICHA. 

Family  Pleurotkichina  Biitschli. 
Genus  Plenrotriclia  Stein. 
Pleurotricha  graMciis  Stein. 
In  infusion  of  dry  leaves.     Size  84  yu,  by  42  fi. 

Family  Aspidiscina  Ehrbg. 

Genus  Aspidisca  Ehrbg. 

Aspidisca  costata  Duj. 

In  large  numbers  in  water  from  drain  near  a  water-tap  in  the 
laboratory  compound.  Body  very  small,  possessing  six  deep  canals 
on  the  dorsal  surface. 


Notes  on  Fresh-water  Ciliate  Protozoa  of  India.  263 


Aspidisca  lynceus  Elirbg. 

Body  very  small,  length  about  2-4//,.  In  pond  water  from 
Shalamar  Gardens,  among  Sjnrogijra  filaments,  in  August.  Form 
oval,  posterior  part  broader,  posterior  end  truncated,  anterior  end 
pointed,  with  the  peristomial  cleft  under  its  overlap.  Five  posterior 
styles  ;  frontal  styles  distributed  partly  over  the  ventral  surface  of 
the  body,  four  on  the  central  portion  of  the  ventral  surface,  and 
three  near  the  anterior  end. 

Dorsal  surface  smooth  and  not  furrowed.  Contractile  vacuole 
near  the  posterior  end.  Xucleus  horse -shoe  shaped.  Locomotion 
characteristic,  swimming  round  and  round,  now  from  left  to  rights 
now  from  right  to  left,  sometimes  stopping,  and  jumping  or  creep- 
ins  forward. 


PERITPJCHA. 

Family  Yoeticellina  Biitschli. 

Genus  Scyphiclia  Duj. 

Scyjphidia  fromentelii  S.K.  (?). 

The  specimens,  which  I  have  referred  to  this  species  with  some 
hesitation,  were  found  in  August  attached  to  the  carapace  of 
Daplmia,  in  pond  Avater  from  Shalamar  Gardens.  Body  small,  52  jjl 
by  25yLt,  form  elongated,  posterior  end  thinner  and  provided  with  a 
rounded  sucking  cup.  In  a  specimen  detached  from  the  host, 
this  posterior  end  was  seen  to  contract  independently  as  in  sucking. 
Body  transversely  wrinkled.  Peristomial  margin  thickened  and 
reversible.  Contractile  vacuole  anterior,  near  the  middle  of  the 
body.  The  form  differed  however  from  the  description  of  the 
type  as  recorded  in  Kent  (IJf)  in  that  the  body  was  transversely 
wrinkled,  and  the  posterior  extremity  was  not  seen  to  be  longi- 
tudinally plicate. 

Genus  Vorticella  EhrbR. 


Vorticelkt  campanula  Ehrbg. 

In  water  from  a  pond  in  the  Lawrence  Gardens.  On  leaves  of 
Lemna,  mostly  on  leaves  which  are  dried  up  and  brownish.  October. 
Social.     Size  63  /t  to  73  yu,  being  common. 

With  characters  of  the  type. 


264:  Transactions  of  the  Society. 

Vorticella  citrina  Ehrbg. 

Very  abundant  in  an  infusion  of  dry  leaves  (August).  Body 
broadly  campanulate,  not  narrowed  behind  the  anterior  '  end. 
Length  of  the  body,  including  the  basal  cone-like  projection,  26  /a 
in  one  specimen  (somewhat  contracted),  and  50  fi  in  another 
specimen.  Length  of  the  stalk  about  three  to  five  times  the 
lengtli  of  the  body. 

Genus  Cccrchesium  Ehrbg. 
Garchesium  epistylidis  CI.  &  Lachm. 

iSTumerous  colonies  on  the  gills,  legs  and  tail  bristles  of 
Ephemerid  larvae  in  pond  water  Irom  Shalamar  Gardens  (August), 
each  colony  consisting  of  a  few  (two  to  four)  individuals  only. 
Individual  zooids  separately  contractile,  the  thread  in  the  stalk 
being  interrupted  at  each  bifurcation.  Stalk  four  to  five  times  the 
length  of  the  body,  smooth,  and  in  contracting  the  portion  of  the 
stalk  near  the  animal  thrown  into  a  spiral.  Some  stalks  end  in 
two  zooids,  the  stalk  just  bifurcating  near  the  tip,  one  portion  con- 
taining the  thread  and  the  other  not.  Individual  zooids  about  o2  fju 
in  length ;  anterior  end  slightly  less  wide  than  the  middle  of  the 
body  ;  peristomial  margin  thickened,  slightly  reversible.  Contractile 
vacuole  situated  about  the  middle  of  the  body.  Nucleus  slightly 
curved,  somewhat  kidney-shaped.  Contracted  zooid  pyriform  in 
shape,  cuticle  smooth. 

The  form  encountered  differed  however  from  the  type  in  lacking 
the  articulate  character  of  the  stalk. 


Genus  Epistylis  Ehrbg. 

Epistylis  plicatilis  Ehrbg. 

Forming  a  whitish  tuft  on  shells  of  snail  (probably  Limnimts) 
in  pond  water  in  Shalamar  Gardens  (August).  Long  dichotomously 
branching  colonies ;  individuals  independently  contractile,  with  no 
thread  running  in  the  stalk.  The  secondary  branches  of  the  stalk 
showed  longitudinal  striations  at  the  attachment  of  the  zooid,  but 
are  otherwise  granular  and  somewhat  feathery  in  appearance. 
Length  of  the  expanded  zooids  is  <S4//,  to  126 /x.  Peristomial 
margin  dilatable  ;  ciliary  disc  capable  of  considerable  projection 
when  the  animal  is  in  a  fully  expanded  condition.  Wlien  con- 
tracted there  is  an  anterior  projection,  and  the  posterior  half  of  the 
body  shows  distinct  transverse  pleating,  wliich  is  characteristic  of 
the  species. 


Notes  on  Fresh-water  Oiliate  Protozoa  of  India.         265 

Epistylis  articnlata  From. 

Growing  abundantly  on  all  sides  on  a  small  spirally  coiled 
Gastropod  shell  (probably  PlanorUs),  on  which  it  forms  a  white 
fluffy  mass ;  found  in  pond  water  in  Shalamar  Gardens.  Colonies 
erect,  height  of  colony  about  0*6  mm.  Pedicle  dichotomous, 
sparingly  branched,  striate  longitudinally,  articulate  at  one  or  two 
intervals  between  each  bifurcation,  in  which  respect  it  differs  from 
E.  plicatilis.  Body  form  as  in  that  species,  but  two  zooids  at 
termination  of  each  terminal  stalk. 

Kent  (14),  in  a  note  to  the  description  of  this  species,  observes 
as  follows  : — "  In  shape  the  animalcules  of  this  species  appear  to 
closely  resemble  those  of  E.  plicatilis,  and  it  is  a  question  whether 
the  chief  point  of  difference  cited  by  de  Fromentel,  that  of  the 
articulation  at  distant  intervals  of  the  pedicle,  is  sufficient  to 
distinguish  them,  more  especially  as,  in  the  last-named  form.  Stein 
has  remarked  that  old  specimens  are  similarly  jointed.  No  mention 
is  made  as  to  the  form  assumed  by  the  zooids  when  in  a  state  of 
contraction,  which  would  have  been.useful  in  the  settlement  of  this 
supposed  identity,  nor  as  to  whether  the  species  forms  large  or 
small  colonies." 

I  am  able  to  throw  some  light  on  this  disputed  point,  having 
observed  the  zooids  in  the  contracted  condition.  The  form  assumed 
by  the  contracted  zooids  is  globular,  the  posterior  part  showing 
transverse  furrows  as  in  E.  plicatilis.  The  size  of  the  colony,  which 
is  considerably  smaller  than  that  of  E.  plicatilis,  and  the  fact  that 
two  zooids  are  perched  at  the  termination  of  each  stalk,  along  with 
articulate  character  of  tlie  stalk,  which  is  constant  in  one  and  a 
rare  feature  in  the  other,  will  serve  to  distinguish  between  the  two 
species. 


SUCTOPJA. 

Family  Podophryid.e  Biitschli. 
Genus  S2:)hserophrya  CI.  &  Lachm. 
Sphxrophrija  p)usilla  CI.  &  Lachm. 

Body  very  small,  found  parasitic  in  Paramecium  caudatum 
A  specimen  containing  four  young  individuals  was  encountered  in 
October.  Two  individuals,  provided  with  knobbed  tentacles  all 
Tound,  escaped  under  observation  and  began  to  swim  freely. 


26(3  Transactions  of  the  Society. 

TABLE  OF  INDIAN  SPECIES  OF  CILIATA. 

Species 


Holophrya  lateralis  S.K.     . 
„  indica  Bhatia    , 

,,  bcngalcnsis  Ghosh. 

,,  annandalei  Ghosh.     . 

TJrotricha  glohosa  Schew.    . 
Enchelys  arcuata  01.  &  Lachm. 
SpatJiidium  spathula  var.  monilifonne  var 
Prorodon  teres  Ehrbg. 
Lacrymaria  vermicularis  Ehrbg.  sp 
Coleps  hirtus  O.  F.  Miill.    . 
Didinium  nasutiim  Stein.  - 
Mesodinium  pulex  01.  &  Lachm. 
Loxophyllum  fasciola  Ehrbg.  sp. 

>>  ,,        suh.s-g.punjabensis'Bha.tisL 

Loxodes  rostrum  Ehrbg. 
Nassula  sp.        .  .         .  . 

,,        stromphii  Ehrbg.  sp. 
Chilodon  cucullulus  0.  F.  MiiU.  sp 
Glaucoma  pyriformis  Stein.  (?) 
Ti-ichoda  pura  Ehrbg. 
Frontonia  leucas  Ehrbg.     . 
Ophryoglena  sp.  (=  OtostoiJia  carteri  S.K. 
Colpidium  colpoda  Stein.    . 
Paramecium  aurelia  0.  F.  Miill. 
„  caudatum  Ehrbg.  . 

„  bursaria  Ehrbg.     . 

Plagioyyla  (?)  carteri  S.K. 
Spirostomum  ambiguum  Ehrbg.  var. 
Climacostomum  virens  Ehrbg.     . 
Stentor  sp.         .  .  ,  . 

Folliculina  ampulla  0.  F.  Miill. 
Halteria  grandinella  0.  F.  Miill. 
Pleurotricha  grandis  Stein. 
Oxytricha  sp.     . 
Euplotes  charon  0.  F.  Miill. 
Aspidisca  costata  Duj. 

„         lynceus  Ehrbg.    . 
Scyphidiafromentelii  S.K.  (?)     . 
Voi'ticella  microstow,a  Ehrbg. 

„         patellina  0.  F.  Miill.  . 

,,         convallaria  L.     . 

,,         campanula  Ehrbg. 

,,          citrina  Ehrbg.    . 
Carchesium  epistylidis  01.  &  Lachm. 

„  polyjmnim  Ehrbg.    . 

Epistylis  galea  Ehrbg. 

„        lilicaiilis  Ehrbg. . 

„         articulata  From. 
Cothurnia  sp.  {=  Pyxicola  carteri  S.K.) 
Vaginicola  sp.  . 
Syhxrophrya  sp.         .  .  . 

,,  imsilla  01.  &  Lachm.     ....  _ 

Podophrya  fixa  Ehrbg.        ....]!  4- 

Tokophrya  quadripartita  01.  &  Lachm.        .  !  + 

Acineta  tuberosa  Ehrbg.     .....    j  -i. 


Recorded  from 

Fomid  and 

India  by 

recorded  by 

other  writers 

the  Author 

+ 

— 

+ 

4- 

+ 

_ 

— 

+ 

— 

+ 

— 

+ 

— 

+ 

— 

+ 

+ 

+ 

— 

+ 

+ 

- 

+ 

'             + 

— 

+ 

— 

+ 

+ 

_ 

— 

+ 

+ 

— 

— 

+ 

— 

+ 

+ 

— 

+ 

— 

— 

+ 

+ 

— 

— 

+ 

— 

+ 

+ 

— 

— 

4- 

+ 

— 

+ 

+ 

+ 

— 

— 

+ 

— 

4- 

+ 

— 

+ 

— 

- 

4- 

— 

4- 

— 

4-. 

+ 

— 

+ 

— 

+ 

— 

— 

4- 

—            i 

4- 

— 

4- 

4- 

— 

+ 

— 

— 

+ 

- 

4- 

Xotes  on  Fresh-ivater  Ciliaie  Protozoa  of  India.  2(37 


Keferences  to  Literatuke. 

1.  Andre,  E. — Kecherches  sur  la  faune  pelagique  duLeman  et  Description 

cle  nouveaux  genres  d'Infusoires.     Rev.  Suisse  de  Zoologie,  xxii.  No.  7 
(1914). 

2.  Contribution  a  1' Etude  de  la  faune  infusorienne  du  lac  Majeur. 

Ibid.,  xxiii.  No.  4  (1915). 

3.  Contribution  a  I'Etude  de  la  faune  infusorienne  du  Leman.     Ibid., 

xxiv.  No.  10  (1916). 

4.  AxNANDALE,  N. — The  Fauna  of  Brackish  Ponds  at  Port  Canning,  Lower 

Bengal.     Rec.  Ind.  Mus.,  i.  pt.  1  (1907). 

5.  Bhatia,  B.  L. — Notes  on  the  Ciliate  Protozoa  of  Lahore.      Rec.  Ind. 

Mus.,  xii.  pt.  5,  No.  15  (1916). 

6.  BCtschli,  O. — Protozoa.       In    Bronn's    Klassen    und   Ordnungen   des 

Thierreichs.,  Bd.  I,  Dritte  Abtheilung.    (Leipzig  u.  Heidelberg,  1889.) 

7.  Carter,  H.  J. — Further  Observations  on  the  Development  of  Gonidia, 

etc.     Ann.  Mag.  Nat.  Hist.,  xvi.  (2)  (1856). 

8.  Notes   on   the  Fresh-water  Infusoria  of  the  Island  of  Bombay. 

Ibid.,  xviii.  (2),  Nos.  104,  105  (1856). 

9.  Notes  and  Corrections  on  the  Organisation  of  Infusoria,  etc.    Ibid., 

viii.  (3),  No.  46  (1861). 

10.  Notes  on  the  Filigerous  Green  Infusoria  of  the  Island  of  Bombay. 

Ibid.,  iii.  (4),  No.  16  (1869). 

11.  DoFLEiN,  F. — Lehrbuch  der  Protozoenkunde.     (Jena,  1909.) 

12.  Eyferth,  B. — Einfachste  Lebensformen  des  Tier-  und  Ptlanzenreiches. 

Vierte  Auflage,  von  W.  Schoenichen  (Braunschweig),  (1909). 

13.  Ghosh,  E. — Studies  on  Infusoria,  II.     Rec.  Ind.  Mus.,  xvi.  pt.  1  (1919). 

14.  Kent,  S. — A  Manual  of  the  Infusoria.     (London,  1880-2  ) 

15.  Lang,  A. — Lehrbuch    der   Vergleichenden   Anatomic    der   Wirbellosen 

Thiere.     (Jena,  1901.) 

16.  MiNCHiN,    E.    A.— An    Introduction   to   the    Study    of    the    Protozoa. 

(London,  1912.) 

17.  Mitchell,  J.— Notes  from  Madras.      Quart.   Journ.   Micr.  Sci.,  n.s.  ii. 

(1862.) 

18.  Pritchard,  a. — A  History  of  Infusoria.     (London,  1861.) 

19.  Prowazek,  S. — Taschenbuch  der  mikroskopischen  Technik  der  Protist- 

enuntersuchung.     (Leipzig,  1907.) 

20.  ScHEWiAKOFF,    W.  — Beitriige   zur    Kenntnis    der  holotrichen  Ciliaten. 

Bibliotheca  zoologica,  i.  Heft.  5  (1889). 

21.  tjber  die  geographische  Verbreitung   der    Siisswasser-Protozoen. 

Mem.  de  I'Academie  Imp.  des  Sciences  de  St.  Petersbourg,  Serie  VII. 
xli.  No.  8  (1893). 

22.  Infusoria  Aspirotricha.    Ibid.,  Serie  VIII.  iv.  No.  1  (1896). 

23.  Statkewitsch,  P. — Zur    Methodik    der  biologischen   Untersuchungen 

liber  die  Protisten.     Arch.  f.  Protistenkunde,  Band  5  (1905). 


269 


VIII. —  Tlie  Frohleiii  of  Sijnapsis. 

By  Lancelot  Hogben,  M.A.,  B.Sc,  Lecturer  in  Zoology, 
Imperial  College  of  Science  and  Technology. 

{Read  June  16,  1920.) 

The  attention  which  has  been  directed  of  late  years  by  Duesberg^ 
Cajal,  Weigl,  Guillermond,  Gatenby  and  others  upon  the  behaviour 
of  the  intracellular  inclusions  in  the  germ  cycle  of  animals  and 
plants  has  again  called  in  question  the  Weismannian  doctrine 
relating  to  the  genetic  significance  of  the  nucleus.  In  attempting 
to  correlate  the  phenomena  of  cell  anatomy  with  our  knowledge  of 
the  hereditary  mechanism  there  are  two  propositions  which  may  be 
stated  at  the  outset  as  a  basis  of  agreement.  First,  that  in  all 
cases  of  biparental  reproduction  of  which  we  have  any  knowledge 
both  parents  contribute  equally  to  the  constitution  of  the  zygote ; 
secondly,  that  the  only  data  in  genetics  which  permit  any  legiti- 
mate inference  as  to  the  behaviour  of  the  substantial  basis  of 
inherited  characters  during  the  germ  cycle  are  those  derived  from 
the  pursuit  of  Mendelian  experiment.  The  first  must  be  borne  in 
mind  in  approaching  any  theories  which  attempt  to  distinguish 
between  "specific"  and  "generic"  characters  in  the  process  of 
hereditary  transmission.  The  demonstration  of  paternal  characters 
in  Echinoid  generic  hybrids  by  MacBride  and  Debaisieux,  as  also 
the  observations  of  Baltzer,  Doncaster  and  others  on  chromosome 
elimination,  leave  no  justification  for  assuming  that  there  is  any 
difference  between  the  paternal  and  maternal  moieties  contributed 
to  the  zygote,  or,  as  Jenkinson  believed,  between  the  role  of  cyto- 
plasm and  nucleus  respectively,  in  relation  to  the  specific  and 
generic  characteristics  of  the  organism.  At  the  same  time  we  must 
dismiss  every  sort  of  speculation  upon  heredity  based  on  a  consider- 
ation of  cell  structure  unsupported  by  experimental  fact.  When, 
therefore,  authors  like  Mot-tier  declare  that  they  only  claim  the 
transmission  of  non-Mendeliancliaractersby  the  chondriosomes,  etc., 
it  is  hardly  possible  to  treat  sucli  hypotheses  with  serious  consider- 
ation. There  may  be  a  mode  of  inheritance  which  on  analysis 
yields  no  evidence  of  segregation  or  factorial  integrity ;  but 
whether  there  is  or  not,  at  present  nothing  is  known  of  such  a 
mechanism  as  could  provide  a  foundation  for  correlating  the 
behaviour  of  the  cell  elements  with  it.  It  must  therefore  be  con- 
ceded that  at  present  genetic  cytology  has  to  build  upon  the  data 
of  Mendelism  ;  and  it  may  be  safely  said  that  such  considerations 


270  Transactions  of  the  Society. 

exclude  both  mitochondria  and  chondrioplasts  (Grolgi  rods)  from  the 
exercise  of  a  direct  part  in  hereditary  transmission.  The  unequal 
distribution  of  these  elements  during  cytokinesis  and  their  incon- 
stant numerical  relations  (cf.  Wilson  on  Opistkacanthv.s) -,  their 
elimination  either  wholly  or  partly  from  the  male  gamete  either 
during  spermateleosis  (Oatenby  and  Montgomery),  or  before 
fertilization  (Lillie; ;  and  finally,  their  failure  to  provide  any 
evidence  of  segregation  in  gametogenesis  (cf.  especially  Gatenby  on 
Limax),  demonstrate  (1)  that  the  complex  of  one-cell  generation  is 
not  integrated  in  such  a  way  as  to  be  individually  representative  of 
that  of  another;  (2)  that  in  many  cases  at  least  the  mitochondrial 
or  chondrioplast  organization  of  the  zygote  has  no  continuity  with 
that  of  the  male  parent.  The  relation  of  the  maternal  and  paternal 
cytoplasmic  inclusions  provides  no  means  of  effecting  alternating 
inheritance. 

Thus  to-day  the  importance  of  the  nucleus  in  inheritance  has 
been  emphasized  rather  than  diminished  by  the  attention  which 
improved  technique  has  directed  to  other  parts  of  the  cell.  The 
immediate  problem  of  genetic  cytology  therefore  concerns  the 
manner  in  which  the  nucleus  itself  functions  in  the  process ;  and 
naturally,  the  theory  of  synapsis,  or  the  conjugation  of  chromo- 
somes derived  from  alternate  parents  preparatory  to  this  segrega- 
tion in  the  maturation  divisions,  occupies  a  position  of  central 
importance  in  the  discussion.  Considerations  in  favour  of  the 
recognition  of  chromosomes  as  units  in  the  hereditary  process  have 
been  drawn  from  cytological  studies  in  relation  to  sex  determina- 
tion, mutation,  and  generic  hybridization ;  and  since  these  have 
been  admirably  epitomized  by  Gates  and  Doncaster  (Q.J. M.S., 
1914),  they  do  not  call  for  comment  in  this  place.  The  most 
fruitful  basis  however  for  a  discussion  of  the  chromosome  hypothesis 
concerns,  whether,  in  the  behaviour  of  the  chromosomes  in  the 
germ  cycle,  we  are  actually  witnessing  the  mechanism  of  alternat- 
ing heredity  in  operation.  This  problem  has  become  an  increasingly 
technical  one,  the  issues  of  which  have  not  been  sufficiently 
criticized. 

In  treating  of  the  growth  of  the  modern  doctrine  of  Synapsis,  it 
is  convenient  to  accept  as  a  starting  point  Sutton's  observations 
(1902)  on  the  chromosome  groups  of  Brachystola,  published  shortly 
after  the  rediscovery  of  Mendel's  laws  by  Correns,  Tschermak  and 
De  Vries ;  for  it  cannot  be  too  insistently  stated  that  the  whole 
theory  rests  primarily  upon  the  fact  of  chromosomal  heteromorphism 
rather  than  the  behaviour  of  the  nucleus  in  the  meiotic  phase. 
To  illustrate  the  bearing  of  heteromorphism  among  chromosomes 
on  the  theory  of  gametic  segregation  a  more  convenient  example 
than  Brachystola  itself  is  furnislied  by  Nakahara's  recent  work  on 
the  Stonefly,  Perla  (1919).  The  spermatogonia!  complex  liere 
consists  of  ten  chromosomes,  which  may  be  arranged  according  to 


The  Problem  of  Synapsis.  271 

size  and  shape  as  follows :  a  and  a  are  rod-like  and  equal ;  two 
pairs,  yS  and  ^',  7  and  7,  are  Y-shaped  and  equal ;  one  pair,  S  and  h', 
are  minute  and  spherical ;  while  the  fifth  pair  is  unequal,  ajand  y. 
Reduction  takes  place  in  the  formation  of  the  sperms,  and  the 
second  spermatocyte  has  the  constitution  a  or  a'  -f  ,  y8  or  yS'  -f  , 
7  or  7'  +  ,  S  or  h'  ■\',  X  or  y.  Assuming  that,  as  in  all  the  closely 
allied  insects,  x  is  equally  paired  in  the  female,  it  follows  that  the 
gamete  has  one  representative  of  each  pair  of  chromosomes  in  the 
gametogonial  cells  ;  and  if  it  is  legitimate  to  assume  that  the 
chromosomes  of  the  latter  correspond  individually  to  those  of  the 
zygote,  it  is  clear,  since  the  zygote  is  the  product  of  the  union  of 
two  gametes,  that  the  process  of  "  reduction  "  involves  the  resolu- 
tion of  chromosome  pairs  into  their  maternal  and  paternal  com- 
ponents. The  debatable  implication  of  this  argument  is  the 
assumption  that  the  chromosomes  of  one  cell  generation  individu- 
ally correspond  to  those  of  another.  As  is  well  known,  the 
chromatin  organization  of  an  ordinary  resting  nucleus  exists  in  a 
reticulate  condition,  so  that  it  is  not  possible  to  settle  by  imme- 
diate inspection  whether  the  chromosomes  are  temporary  and  in- 
constant aggregates  of  chromatin  particles,  or  whether  on  the  other 
hand  to  decide  in  favour  of  a  definite  structural  continuity  of  the 
former  as  opposed  to  an  interpretation  of  a  more  remote  character. 
Upon  this  decision  the  elaborate  body  of  doctrine  embodied  in 
*'  the  chromosome  hypothesis  "  logically  rests. 

The  considerations  in  favour  of  the  view  that  each  chromosome 
of  the  prophase  corresponds  structurally  to  a  similarly  constituted 
chromosome  in  the  preceding  telophase  may  be  summarized  as 
follows: — {!)  Actual  continuity  occurs  in  certain  plants;  ''pro- 
chromosomes "  were  first  observed  by  Schwarz  (1892)  and  Zacharias 
(1895)  ;  they  have  been  recently  studied  by  Overton,  Eosenberg  and 
Stout  (1913).  (2)  The  transition  of  the  chromosomes  of  the  telo- 
phase into  the  reticulate  condition,  and  the  emergence  of  the 
prophase  from  this  state  studied  by  Overton  in  Podophyllum, 
Digby  (1919)  in  Osmunda;  also  Boveri's  work  on  the  relation  of  the 
chromosomes  to  the  orientation  of  the  reticulum  in  the  curiously 
lobed  nuclei  of  Ascaris,  seem  to  indicate  clearly  that  the  reticulum 
is  itself  a  complex  of  "unit  reticula,"  corresponding  to  the  chromo- 
somes themselves.  (3)  The  numerical  relations  exhibited  in  the 
behaviour  of  the  chromosomes  in  mitosis  always  fulfil  the  expecta- 
tions that  would  be  anticipated  on  the  assumption  of  persistent 
individuality  not  only  in  normal  reproduction  but  also  in  cases  of 
polyspermy  (Boveri),  and  of  hybrids  from  parents  with  complexes 
that  are  numerically  unlike  (Federley).  (4)  The  character  of  the 
complex  when  it  exhibits  heteromorphism  is  only  such  as  could  be 
expected  if  the  chromosomes  maintained  their  individuality  intact 
from  one  generation  to  another.  This  is  very  arresting  in  the  case 
of  hybrids  (Federley,  Baltzer)  of  parents  whose  chromosomes  are 


272  Transactions  of  the  Society. 

distinguishable  in  size  and  shape,  but  the  most  important  data 
are  derived  by  the  study  of  multiple  chromosmes  in  the 
Orthoptera.  Eeferring  to  the  existence  of  a  "hexad"  in  the 
maturation  division  of  a  species  with  the  accessory  united 
to  an  ordinary  chromosome  in  the  piemeiotic  mitosis,  McClung 
comments  thus :  "  One  of  the  elements  possesses  a  distinctive 
character  not  shared  by  the  others — it  has  an  individual  and 
more  or  less  independent  movement  which  takes  place  at  only 
one  time  in  all  the  history  of  the  organism.  Up  to  this  one  point 
it  is  distributed  in  mitosis  like  the  other  chromosomes  ;  ...  so  much 
of  the  chromatin  substance  possesses  distinctive  characters.  Are 
these  the  consequence  of  separate  unity,  or  is  there  some  specific 
nature  of  the  material  ?  The  history  of  the  hexad  multiple  answers 
this  question,  for  although  joined  to  another  element  the  same 
characteristic  behaviour  occurs."  Summing  up  the  evidence,  it 
may  be  said  that  in  certain  cases  persistent  individuality  is  demon- 
strable directly  ;  in  other  cases  the  reticulum  appears  to  be  defin- 
itely organized  with  respect  to  the  mitotic  complex ;  while  in 
mitosis  generally  the  facts  in  all  cases  coincide  with  those  which 
would  be  anticipated  from  the  assumption  that  the  loss  of  chromo- 
somal individuality  during  interkinesis  is  only  apparent.  Further- 
more, the  persistent  individuality  of  chromosomes  is  a  sound 
working  hypothesis  ;  it  permits  of  verifiable  predictions  which  could 
not  be  legitimately  inferred  without  its  aid — as,  for  instance,  the 
existence  of  octads  and  hexads  in  the  heterotype  complex  of  forms 
with  multiple  chromosomes  (see  McClung,  op.  cit).  To  accept  it  as 
such  does  not  imply  a  denial  of  the  possibility  that  some  mechan- 
ism may  be  discovered  which  could  manoeuvre  the  chromatin 
granules  so  as  to  produce  the  effects  observed  without  preserving 
this  continuity  and  integrity  of  structure.  Since,  however,  Tick, 
Delia  Valle,  Meves,  Granata,  and  its  critics  generally  have  failed 
to  reveal  such  a  mechanism,  the  theory  of  persistent  individuality 
affords  at  present  the  most  satisfactory  interpretation  of  the  nucleus. 
The  earlier  exponents  of  the  doctrine  under  consideration  were 
content  to  gather  evidence  in  favour  of  the  reality  of  synapsis, 
relegating  the  means  by  which  the  conjugation  of  homologous 
chromosomes  is  effected  to  a  position  of  secondary  importance. 
The  study  of  partial  linkages  compels  enquiry  into  the  latter 
])roblem  increasingly  to-day.  It  is  not  enough  to  interpret  the 
phenomena  of  independent  segregation  and  coupling  of  different 
pairs  in  terms  of  localization  in  identical  or  tiistinct  bivalents ; 
some  mechanism  must  be  found  to  account  for  "  crossing  over  "  if 
tlie  cliromosome  liypothesis  is  to  develop  further,  and  such  a 
mechanism  Prof.  Morgan's  scliool  claims  to  hnd  in  the  twisting  of 
V)ivalent  tlireads.  It  is  not  possible  to  criticize  here  the  issues 
generally  raised  by  the  "  chiasmotype  "  theory ;  it  is  sufficient  to 
say  tliat  such  an  attempt  to  provide  an  interpretation  of  partial 


The  Problem  of  Synapsis.  273 

linkage  in  Mendelian  inheritance  is  exceedingly  ambitious  in  view 
of  the  widespread  disagreement  concerning  the  genesis  of  the 
lieterotype  chromosomes.  And  it  is  a  surprising  fact  that  many 
chromosome  workers  appear  still  to  treat  the  mode  of  synapsis  as 
a  matter  of  little  concern.  McClung  declines  to  offer  any  view  as 
to  the  genesis  of  the  bivalents  in  the  Orthoptera  from  their  com- 
ponent halves  ;  yet  it  is  evident  that  the  whole  theory  of  synapsis 
stands  or  falls  with  its  consistency  with  the  events  of  the  matura- 
tion prophases. 

As  rei>ards  the  events  which  occur  in  animals  two  views  are 
commonly  maintained  to-day.  Janssens,  the  Schreiners,  Von 
Winiwarter,  Agar,  Wenrich,  Wilson  find  in  general  that  the  initial 
event  is  the  parallel  conjugation  in  pairs  of  chromatin  ("  leptotene") 
filaments  equivalent  in  number  to  the  chromosomes  of  the  pre- 
ceding telophase ;  this  is  followed  by  the  longitudinal  splitting  of 
the  reduced  "  pachytene  "  threads.  The  heterotype  chromosomes 
("  tetrads  ")  are  formed  by  the  drawing  out  of  the  double  threads 
of  the  previous  stage  ("  diplotene  ")  along  the  line  of  cleavage  so 
that  the  transverse  constriction  of  the  tetrad  corresponds  to  the 
longitudinal  split  in  the  diplotene  filament.  Assuming  that  this 
cleavage  separates  the  original  conjugants,  the  heterotype  mitosis 
is  reductional,  the  homotype  equational  (for  the  autosomes).  Un- 
fortunately, to  be  certain  that  actual  segregation  of  the  bivalent 
C(jmponents  occurs,  it  is  necessary  to  be  able  to  trace  the  double 
character  of  the  bivalent  at  every  stage  of  the  process. 

The  view  stated  above  has  been  criticized  by  Goldschmidt  and 
his  pupils,  Arnold  and  certain  earlier  workers  on  the  Orthoptera 
(Sutton,  Davis).  According  to  tliese  workers  the  heterotype  chro- 
mosome is  found  to  be  developed  by  the  union  of  the  looped 
diplotene  thread  by  its  free  ends  so  that  the  heterotype  division 
constricts  the  diplotene  thread  transversely,  while  the  longitudinal 
cleavage  is  interpreted  as  a  precocious  preparation  for  the  homotype 
mitosis.  According  to  the  exponents  of  this  hypothesis  synapsis, 
if  it  occurs,  must  involve  the  end  to  end  union  (telosynapsis  or 
metasyndesis)  of  the  conjugants  rather  than  the  parallel  conjuga- 
tion (parasynapsis)  described  by  the  American  school.  In  accord- 
ance with  this  view  they  are  unable  to  find  any  stage  at  which  the 
full  diploid  number  of  elements  is  present  in  the  meiotic  stage — 
from  the  first  the  chromatin  is  present  as  the  reduced  number  of 
longitudinally  split  loops  or  threads.  They  employ  the  old  concep- 
tion of  the  "  continuous  spireme  "  to  explain  how  the  adherence  of 
chromosomes  in  pairs  end  to  end  may  have  come  about ;  but  no 
cytologist  claims  to  have  actually  witnessed  a  telosynaptic  union 
in  animals.  Eecently  Nakahara  (1919)  has  provided  striking 
evidence  for  this  view  in  the  case  of  the  Perlidse ;  but  the  great 
difficulty  raised  is  the  similarity  of  the  diplotene  stage  in  both 
telosynaptic   and   parasynaptic    accounts   of  the   meiotic    phase. 


274  Transactions  of  the  Society, 

Since  the  two  views  are  mutually  exclusive,  and  since  the 
phenomena  are  in  many  points  essentially  similar  in  all  cases,  it 
is  difficult  to  accept  as  a  compromise  the  existence  of  both  modes 
of  union.  In  attempting  an  evaluation  of  both  sides  of  the  contro- 
versy it  must  be  remembered  that  the  diplotene  threads  often  pass 
through  a  complicated  series  of  changes  in  the  process  of  tranform- 
ing  into  the  heterotype  chromosomes,  so  that  satisfactory  evidence 
of  the  relation  of  the  transverse  cleavage  of  the  latter  to  the 
longitudinal  split  in  the  former  can  only  be  obtained  if  the  history 
of  individual  chromosomes  is  studied  as  Wenrich  (1917)  has  done. 
Secondly,  it  must  be  conceded  that  the  parasynaptic  accounts  have 
been  based  on  some  of  the  most  favourable  material  for  study 
(Batrachoseps  and  Lepidosiren).  Finally,  in  a  large  number  of 
cases  where  early  investigators  described  a  telosynaptic  transforma- 
tion of  the  lieterotype  chromosome,  and  denied  the  existence  of  a 
diploid  leptotene  stage,  subsequent  workers  have  disagreed  with 
their  conclusions.  This  applies  not  only  to  the  work  of  Gold- 
schmidt,  Arnold  and  others  on  Flatworms,  which  has  been  denied 
by  Gelei  and  later  workers,  but  to  all  the  earlier  work  on  the 
Orthoptera.  In  regard  to  the  latter  it  is  only  necessary  to  mention 
the  namay  of  Morse,  Mohr,  Steevens,  Vejdovsky,  Gerard,  Eobertson, 
Wenrich,  Otte,  all  of  whom  have  adopted  the  theory  of  parallel 
conjugation  ;  and  the  work  of  Metz  and  others  showing  the  lateral 
association  in  pairs  of  the  chromosomes  in  the  somatic  complex  of 
Diptera  has  increasingly  influenced  cytologists  in  favour  of  para- 
synapsis. 

In  opposition  to  both  schools  Duesberg  has  attacked  the  whole 
theory  of  synapsis  from  a  study  of  the  meiotic  phase  itself. 
Duesberg's  own  work  on  the  spermatogenesis  of  the  Eat  has  been 
very  destructively  criticized  by  Allen  ;  but  as  his  general  thesis  has 
certain  points  in  common  with  views  held  by  botanical  cytologists 
it  merits  (brief)  comment.  Briefly,  he  holds  that  the  events  of  the 
meiotic  phase  are  not  essentially  different  from  those  of  a  normal 
prophase.  Now  a  comparison  with  a  normal  prophase  must  be 
based  upon  similarity  in  number,  size  and  shape  or  disposition  of 
the  chromatin  elements.  As  regards  number  Duesberg  is  content 
to  neglect  the  witness  of  reliable  workers  who  claim  that  the  full 
diploid  number  of  leptotene  threads  is  present  at  the  inception  of 
the  meiotic  pliase.  With  respect  to  the  form  of  the  chromatic 
elements  there  is  obviously  no  basis  of  similarity  between  the 
leptotene  threads  and  the  tlocculent  prochromosome  of  a  normal 
prophase ;  while  the  polar  orientation  of  the  meiotic  nucleus  is  a 
phenomenon  which  Duesberg  is  content  to  dismiss  from  serious 
consideration  on  tlie  basis  of  his  own  incomplete  observations  on  the 
rat.  It  is  true  to  say  that  the  majority  of  competent  cytologists 
are  com[)elled  to  recognize  in  oi)position  to  this  view  that  the 
meiotic  phase  in  the  nucleus  is  an  event  sui  generis. 


The  FroUem  of  t^yna]_)sis.  275 

Some  cytologists  have  attempted  to  draw  a  too  detailed  com- 
parison between  the  phenomena  of  the  meiotic  phase  in  animals 
and  plants,  consequently  the  issue  has  been  very  much  complicated, 
for  reasons  that  will  appear.  As  early  as  1905  Farmer  and  Moore 
formulated  a  theory  of  meiotic  phase  in  plants  and  animals  based 
upon  a  comparison  of  a  series  of  types  (Osmunda,  Feriplaneta, 
Lilium)  and  advocating  a  telosynaptic  interpretation .  The  principal 
animal  type,  Penplaneta,  was  selected,  unfortunately,  owing  to  the 
peculiar  difficulties  of  Orthopteran  spermatogenesis;  and  subsequent 
work  has  made  it  clear  that  the  Blattids  in  reality  conform  to  the 
theory  of  parallel  conjugation.  Since  then  the  terms  "  telo- 
synapsis "  and  *'  parasynapsis "  have  come  into  use  in  botanical 
cytology  in  a  sense  altogether  different  from  that  in  which  they 
are  employed  in  zoology.  Of  the  two  contractions  of  the  chromatin 
threadwork  in  the  preineiotic  phase  of  plants  the  telosynaptic  theory 
identifies  the  second,  the  parasynaptic  theory  the  first,  as  the  point 
at  which  synapsis  of  homologous  chromosomes  is  effected.  Gregoire 
has  compared  the  first  contraction  stage  of  plants  to  the  bouquet 
stage  in  animals  (1906-11),  thus  aggravating  the  confusion  in  existing 
terminology.  Now,  Miss  Digby  (1919)  has  shown  recently  that 
in  Osmunda  the  archesporial  chromosomes  undergo  cleavage  in  the 
telophase,  and  that  the  fusion  witnessed  in  the  first  contraction 
stage  of  the  meiotic  nucleus  is  in  reality  the  reassociation  of  lialf- 
chromosomes  split  in  anticipation  of  a  division  which  is  arrested. 
In  view  of  the  fact  that  wherever  the  leptotene  threads  in  animals 
can  be  definitely  counted  their  number  corresponds  to  the  telophasic 
chromosomes,  and  also  the  possibility  of  tracing  them  back  to  the 
latter  in  a  number  of  cases  (e.g.  "Wilson  in  Hemiptera),  it  may  be 
stated  without  hesitancy  that  the  data  embodied  in  the  interpreta- 
tion of  the  first  contraction  phase  of  plants  by  Farmer,  Digby,  Gates 
and  others  have  no  bearing  on  any  stage  which  occurs  normally  in 
animals. 

Turning  now  to  the  bearing  of  the  study  of  the  meiotic  phase 
on  the  general  theory  of  synapsis  derived  from  a  consideration  of 
the  heteromorphism  of  chromosome  complexes,  the  principal 
questions  that  arise  are,  first,  whether  there  is  actual  evidence  that 
chromatin  elements  conjugate ;  second,  whether  such  elements  are 
chromosomes  sensu  stricto ;  lastly,  whether  the  conjugating  elements 
are  subsequently  disjoined  by  a  reduction- division.  As  regards 
the  first,  all  those  who  advocate  parasynapsis  in  animals  are  agreed  ; 
concerning  the  second,  a  few  authors  (e.g.  Wilson)  claim  to  have 
established  continuity  between  the  telephase  chromosomes  and  the 
conjugating  filaments ;  while  with  respect  to  the  last,  the  fusion  of 
the  conjugating  elements  in  parasynapsis  is  usually  so  complete 
that  it  is  almost  impossible  to  be  certain  that  they  do  not  lose 
their  individuality,  as  believed  by  Vejdovsky  and  Bonnevie.  It 
will  thus   be  seen    that  w^hile    the '  chromosome    hypothesis  has 

T  2 


276  2\ansactions  of  the  Society. 

proved  a  great  incentive  to  research — particularly  in  the  problem 
of  sex — its  major  premise,  the  reality  of  synapsis,  is  in  no  way 
firmly  established  ;  further  knov^ledge  of  the  relation  of  chromo- 
somes to  the  organization  of  the  resting-nuclei  and  a  specialized 
study  of  individual  heterotype  chromosomes  constitute,  therefore, 
two  of  the  most  imperative  needs  of  cytological  theory  to-day. 


Bibliography  of  more  Important  Papers  containing  a 
General  Discussion  of  the  Problem  of  Synapsis. 

1.  Agar  (1912). — The  Spermatogenesis  of  Lej)idosiren ])aradoxa.    Q.J.M.S.^ 

voL  57.    Transverse   Segmentation  and  Internal   Differentiation  of 
Chromosomes.     Q.J.M.S.,  voL  58. 

2.  Arnold  (1909). — The   Prophase   in  the  Ovogenesis,  etc.,  of  Planaria. 

ArchZellf.,3. 

3.  BucHNER  (1909). — Das  Accessoriche   Chromosom  im   Spermatogenese 

und  Ovogenese  der  Orthoptera.     Arch.  Zellf.  3. 

4.  DiGBY    (1919). — The   Archesporial  and   Meiotic  Mitoses  of    Osmunda, 

Ann.  Bot.,  No.  130. 

5.  DuESBERG  (1909). — Note  complementaire  sur  la  spermatogenese  du  rat. 

Arch.  Zellf.,  3. 

6.  Farmer  (1912). — Telosynapsis  and  Parasynapsis.     Ann.  of  Bot.,  vol.  26. 
and  Moore  (1905). — The  Meiotic  Phase  in  Animals  and  Plants. 

Q.J.M.S.,  vol.  48. 

7.  Gates  (1911). — The  Mode  of  Chromosome  Pteduction.     Bot.  Gaz.,  51. 

8.  Gelci   (1913). — Tiber  die  Ovogenese  von  Dendrocoelium.     Arch.   Zell- 

porsch.,  Bd,  11. 

9.  Gregoire  (1910). — Les    cineses  de   maturation   dans  les  deux  regnes. 

La  Cellule,  26. 

10.  Hogben  (1920). — Studies  on  Synapsis.    I-II.     Proc.  Roy.  Soc,  vol.  91. 

11.  Janssens  (1905). — Evolution    des    Auxocytes   males  du  Batsachosaps. 

La  Cellule,  22. 

12.  McClung    (1914). — A    Comparative    Study   of    the   Chromosomes  in 

Orthopteran  Spermatogenesis.     Journ.  Morph.,  25. 

13.  Meves    (1908). — Die     Spermatocytenterlungen     bei    des     Honigbeine. 

Arch.  Mikr.  Anat.,  70. 

14.  Morse    (1909).— The   Nuclear  Components   of  the  Sex  Cells  in  Four 

Species  of  Cockroaches.     Arch.  Zellf.  3. 

15.  Nakahara  (1919). — Spermatogenesis  of  Perfa,  etc.     Journ.  Morph.,  33. 

16.  Payne  (1914). — Chromosomal    Variation,   etc.,    in   Forficula,     Journ. 

Morph.,  25. 

17.  Schreiner,  a.  &  K.  E.  (1906). — Neue  Studien  iiber  die  Chromatin  des 

Geschlechtzellan.     Arch,  de  Biol.,  22. 

18.  "Wenrich  (1917). — Synapsis  and  Chromosome  Organization  in  Steno^ 

bothrus  and  Inmerotropis.     Journ.  Morph.,  29. 

19.  Wilson    (1919).— Studies   in    Chromosomes.    VIII.        Journ.    Exper. 

Zool.,  13. 

20.  Winiwarter  &  Sainmont  (1909). — Nouvelles  recherches  sur  I'ovogenese 

et  Torganogenese  des  mammiferes.     Arch,  de  Biol.,  24. 


277 


IX. — Further  Notes  on  the  Oogenesis  and  Fertilization  of 
Grantia  compressa* 

By  J.  Beonte  Gatenby,  B.A.,  B.Sc,  D.Phil.  (Oxon.),  F.R.M.S., 
Lecturer  in  Cytology  and  Senior  Assistant  in  Zoology, 
University  College,  London,  and  Senior  Demy,  Magdalen 
College,  Oxford. 

One  Plate. 

Inteoductiox. 

So  far  as  at  present  known  the  sponr^e  is  the  only  animal  in  which 
the  male  element  does  not  itself  penetrate  the  egg  directly,  but 
first  enters  another  cell  which  is  thereby  induced  to  carry  the 
sperm  to  the  expectant  ripe  oocyte. 

Precocious  fertilization,  such  as  occurs  in  Saccocirrus  or  Otome- 
sostoma  (->),t  is  a  very  peculiar  process,  but  no  carrier  cell  intervenes 
between  oogonium  and  spermatozoon,  and  so  the  process  does  not 
introduce  a  third  cell  as  in  the  sponge. 

In  this  paper  I  have  described  a  stage  hitherto  missing  from 
my  previous  description  {3),  and  I  have  taken  the  opportunity  to 
examine  further  the  "  chromidia  "  formation  found  by  Jorgensen  (7) 
and  Dendy  {2). 

The  First  Stages  of  Fertilization  in  Grantia 

.  compressa. 

In  a  previous  paper  I  have  described  the  peculiar  fertilization 
in  a  sponge,  in  which  the  spermatozoon  enters  a  collar  cell  and  is 
thereby  carried  to  the  ripe  oocyte.  All  the  spermatozoa  found  in 
collar  cells  were  oval  structures  containing  a  bun-shaped  reticu- 
late nucleus  and  a  similarly  shaped  mitochondrial  middle-piece. 
From  some  stages  of  spermatogenesis  found  by  me  in  Grantia  it 
was  known  that  the  spermatozoon  (spermatid)  was  provided  with 
a  flagellum.  It  was  concluded  that  the  ovoid  spermatozoa  found 
in  the  collar  cells  were  somewhat  changed  in  shape,  a  result  due 
to  their   presence   in  another  cell,   and   that  very  probably   the 

*  The  materials  used  in  this  research  were  purchased  by  a  Government  Grant 
of  the  Royal  Society. 

t  The  italic  figures  within  brackets  refer  to  the  Bibliography  at  the  end  of 
the  paper. 


278  Transaclions  of  the  Socictij. 

spermatozoon  of  Grantia  was  tilifomn  and  flagellate  like  the 
majority  of  metazoon  sperms. 

Tills  year  more  material  was  sent  from  Plymouth  by  Dr.  Allen, 
and  one  missing  stage  was  found ;  this  stage  nearly  completes  the 
story  of  the  fertilization  of  Grantia  compressa,  and  confirms  tlie 
views  expressed  in  tiie  previous  paper  [S). 

In  PI.  V,  fig.  2,  is  drawn  a  part  of  an  oocyte  of  Gfantia, 
and  on  the  left  a  row  of  choanocytes  lining  the  iiagellated  cavity. 
At  NNS  is  the  sperm-carrying  collar  cell  whose  nucleus  has 
become  altered  under  the  influence  of  the  sperm  at  MP  ;  the 
spermatozoon  is  ovoid  in  sliape,  and  at  this  period  still  lies  within 
the  cytoplasm  of  the  collar  cell. 

Earlier  stages  than  this  were  not  found  in  the  material  prepared 
last  year,  but  in  fig.  1  is  a  much  earlier  stage.  The  coarsely  dotted 
area  above  represents  the  ectoplasm  of  the  Grantia  oocyte  (E  in 
PL  V,  fig.  2),  and  three  collar  cells  are  represented ;  the  middle 
one  contains  at  X,  MP  the  head  of  middle-piece  of  a  spermatozoon. 
The  latter  is  still  elongated,  and  it  seems  sufficiently  clear  that  the 
sperm  here  beginning  to  alter  in  shape  was  filiform.  Such  a  stage 
closely  resembles  what  one  finds  in  a  typical  metazoon  fertilization 
just  after  the  filiform  sperm  has  entered  the  Qgg. 


EXPLANATION   OF   PLATE  V. 

Lettering. — BM.,  basal  merabrane  ;  CN.,  collar  cell  (choanocyte)  nucleus; 
E.,  ectoplasm  ;  EM.,  egg  membrane  ;  EN.,  endoplasm  ;  FL.,  flagellum  ;  G.,  mito- 
chondrial (in  some  cases  yolk)  granule  ;  H.,  halo  of  dense  cytoplasm  around 
nucleus  ;  MP.,  sperm  nucleus  ;  N.,  nucleolus  ;  NU.,  nucleus  ;  NNS.,  nucleus  of 
the  sperm-carrying  collar  cell ;  X.,  extruded  nucleolar  material  still  lightly  staining. 

All  figures  on  Plate  V,  excepting  1  and  2,  drawn  from  Champy-Kull  material 
stained  after  sectioning  by  Benda's  alizarin  and  crystal  violet  method.  Figs. 
1  and  2  are  drawn  from  ordinary  Champy-Kull  material. 

The  scale  of  figures  is  near  fig.  10. 

All  Grantia  covipressa. 

Fig.  1. — Three  collar  cells,  showing  the  spermatozoon  embedded  in  one;  the 
head  of  the  sperm  is  at  N,  the  middle-piece  at  IMP.  The  dotted  area  on  the  right 
is  the  ectoplasm  of  the  oocyte.  The  relationship  of  these  parts  can  be  seen  by 
examining  fig.  2,  where  E  is  the  ectoplasm. 

Fig.  2. — Later  stage,  showing  at  NNS  the  changed  nucleus  (NNS)  of  the  collar 
cell  which  contains  the  spermatozoon  (MP).  This  changed  collar  cell  has  sunk 
below  its  fellows  in  the  germinal  epithelium  ;  on  the  right  is  a  part  of  a  ripe 
oocyte,  at  E  and  EN  are  the  ectoplasm  and  endoplasm  respectively  of  the  oocyte,  ■ 
and  at  NU  a  part  of  its  nucleus. 

Fig.  3. — Collar  cell.     Arrow  points  to  inhalent  chamber. 

Fig.  4. — Progerminative  collar  cell,  about  to  become  an  oogonium. 

Fig.  5. — Later  stage  of  above,  sliowing  enlargement  of  nucleolus. 

Fig.  6. — Oogonium  at  the  stage  of  extrusion  of  nucleolar  fragments  (N).  A 
halo  of  thickened  cytoplasm  indicates  perinuclear  activity  (H). 

Figs.  7,  8. — Stages  in  extrusion  of  nucleolar  (plastin)  fragments. 

Fig.  9. — Nucleuw  reformed  after  its  collapse  (e.g.  in  fig.  8). 

Fig.  10. — Another  form  of  extrusion  of  nucleolar  fragments. 


JOURN.   R.  MICR.  SOC.  1920.     PL  V. 


To  face  p.  278 


Oogenesis  and  Fertilization  of  (rrantia  comjyressa.        'A79 

New  Interpretations  of  the  Nucleolar  Extrusion  in  the 
Oogenesis  of  Grantia  cOxMPRessa. 

Dend}'  (?)  has  described  a  peculiar  process  in  the  oogenesis  of 
Grantia,  whereby  pieces  of  the  nucleolus  are  squeezed  out  into  tlie 
cytoplasm.  In  his  figures  40—1:4  of  Plate  XXV  Dendy  has  given 
figures  illustrating  the  process. 

I  believe  that  such  a  peculiar  occurrence  is  rare  in  the  oogenesis 
of  animals,  and  for  a  time  I  had  some  doubt  as  to  the  correctness- 
of  the  description  previously  given  (J^). 

Further  material  has  been  collected  and  prepared  by  the  best 
new  methods  ;  it  is  possible  to  confirm  Dendy's  previous  description, 
and  to  add  new  facts.  The  figures  3-10  of  PI.  V  of  this  paper  are 
drawn  from  sponges  fixed  by  Champy-KuU's  method,  and  then 
stained  in  Benda's  alizarin  and  crystal  violet. 

In  PL  V,  fig.  o,  is  drawn  a  choanocyte ;  its  nucleus  stained 
reddish  brown,  the  nucleolus  was  violet,  and  the  granules  (G)  in 
the  cytoplasm  also  stained  a  deep  violet.  I  believe  that  some  of 
these  granules,  if  not  all,  are  to"  be  regarded  as  the  mitochondria 
of  the  cell.  In  certain  cases  the  very  large  granules  stained  less 
densely  than  the  smaller  ones,  and  these  may  be  yolk  (with  dense 
proteid  content)  or  mitochondrial  granules  partly  changed. 

In  PI.  V,  fig.  4,  is  a  collar  cell  just  after  it  has  begun  to 
metamorphose  into  an  oogonium.  This  cell  lay  in  the  collar 
epithelium,  just  beneath  two  normal  choanocytes.  The  nucleolus 
(plasmosome)  has  enlarged,  and  the  nuclear  network  stained  less 
densely  than  that  of  most  of  the  unchanged  collar  cells.  Such 
cells  as  the  one  drawn  in  PI.  V,  fig.  4,  migrate  from  the  flagellated 
cavity  into  the  mesoglea,  where  they  undergo  further  remarkable 
changes 

Figs.  5-10  are  drawn  from  mesogleal  oogonia;  in  fig.  5  the 
nucleolus  has  increased  enormously  in  size,  while  the  cytoplasmic 
granules  derived  directly  from  those  already  existing  when  the  cell 
was  still  a  choanocyte  are  still  evident,  but  often  shrunken  in  size. 
In  subsequent  stages  the  large  plasmosome  elongates  and  divides 
by  transverse  fission,  a  large  piece  being  shot  out  into  the  cyto- 
plasm, as  in  PI.  V,  fig.  6,  at  N.  In  other  cases  large  numbers  of 
plasm osomes  collect  inside  the  oogonial  nucleus  ;  the  latter  seems 
to  collapse  bodily  and  the  contained  granules  pass  into  the 
cytoplasm,  as  in  PI.  V,  figs.  7  and  8. 

In  a  number  of  cases  large  pieces  of  the  plasmosome  are 
separated  from  the  central  nucleolus,  and  pass  to  the  nuclear 
membrane;  this  becomes  broken  down,  and  the  granules  pass 
through,  as  shown  in  PI.  Y,  fig.  10. 

In  such  stages  a  really  extraordinary  change  comes  over  the 
hitherto  spherical  nucleus.  PI.  V,  fig.  8,  shows  an  appearance 
which  is  quite  usual :  here  the  nucleus  has  more  or  less  become 


.280  Transactions  of  ths  Society. 

l3roken  up,  and  in  such  cases  it  is  difficult  to  identify  the  remains 
■as  being  a  nucleus.  From  a  study  of  a  number  of  oogonia  at  this 
stage  it  seems  as  if  the  nucleus  becomes  blown  up  with  its  con- 
tained nucleoli,  suddenly  bursts,  and  shoots  its  granular  contents 
into  the  surrounding  cytoplasm.  One  is  impressed  at  all  events 
by  the  collapsed  and  changed  condition  of  the  nucleus  after  it  has 
parted  with  most  of  its  plasmosome  material. 

In  many  cases  it  becomes  possible  to  identify  a  thick  halo 
of  differentiated  cytoplasm  surrounding  the  nucleus,  as  shown 
in  PL  V,  figs.  6  and  10,  at  H.  One  is  irresistibly  induced  to 
believe  that  this  halo  is  formed  by  materials  squeezed,  or  at  all 
events  passively  passing,  out  of  the  nucleus.  In  certain  examples, 
as  in  PI.  Y,  fig.  6,  the  peri-nuclear  halo  contains  vacuoles  and 
granules,  and  is  arranged  in  a  radiating  manner  from  the  nuclear 
membrane. 

Using  Benda's  alizarin  and  crystal  violet  stain,  or  even  acid 
fuchsin  and  toluidin  blue,  it  has  been  possible  to  sliow  that  the 
nucleolar  or  plastin  material  undergoes  a  change  when  extruded 
into  the  cytoplasm,  or  when  it  comes  into  contact  with  the  cyto- 
plasm. This  is  shown  by  such  stages  as  in  PL  V,  figs.  9  and  10; 
in  each  case  the  granules  (G  or  N)  after  passing  into  the  cytoplasm 
stain  more  densely  in  crystal  violet  than  before.  In  fig.  10  the  two 
plastin  bodies  at?  X  stain  more  heavily  than  their  parent  body  in 
the  centre. 

After  the  extrusion  of  the  plastin  materials  the  nucleus  reforms 
as  in  PL  V,  fig.  9.  Occasionally  some  of  the  extruded  plasmo- 
somes  stain  less  heavily  than  tlieir  fellows,  as  at  X.  The  nature 
of  this  peculiarity  is  not  known. 

That  the  extruded  plasmosomes  form  the  mitochondria  of  the 
ripe  egg  seems  to  me  to  be  an  attractive  view.  A  number  of 
authors  (^,  7)  have  identified  these  cytoplasmic  granules  as  chro- 
midia  and  have  traced  their  origin  to  the  nucleus.  Subsequently 
the  extruded  plasmosomes  break  up  (divide  ?)  into  smaller  pieces, 
and  appear  to  grow  and  continue  active  within  the  cytoplasm. 

Quite  lately  I  have  found  that  in  the  oogenesis  of  Saccocirrns 
the  extrusion  of  nucleolar  materials  and  the  formation  and  presence 
of  mitochondria  in  the  cell  are  not  related.  As  is  well  known, 
Hempelman  and  Buchner  both  describe  in  Saccocirrus  the  extru- 
sion of  nucleolar  (plasmosome)  fragments  which  later  form  "  yolk." 
Now  these  nucleolar  fragments  in  Saceocirnis  simulate  the  staining, 
if  not  the  fixing  reactions  of  the  mitochondria,  and  for  a  time  I 
thought  that  the  cases  of  the  sponge  and  of  this  nrchiannelid  might 
be  similar.  This  seems  to  be  far  from  being  true ;  in  Saccocirrus 
true  mitocliondria  exist  in  the  (ig^  before  the  extrusion  of  the 
nucleolar  fragments.  In  my  last  paper  on  sponge  embryology  {3) 
I  came  to  tke  conclusion  that  true  mitochondria  did  exist  in  Grantia 
collar  cells,  and  that  the  so-called  "chromidia"  in  the  egg  cytoplasm 


Oogenesis  and  Fertilization  of  Grantia  cornjjressa,        281 

described  by  Jorgensen  and  Dendy  were  mitochondria.  In  my 
previous  work  on  the  oogenesis  of  Grantia  I  found  what  I  con- 
sidered to  be  true  yolk,  and  confirmed  tlie  previous  descriptions  by 
Jorgensen  and  Dendy  of  the  presence  of  the  "  chromidia."  I  have 
pointed  out  that  these  bodies  should  not  be  called  "  chromidia,"  for 
they  are  not  related  to  true  chromatin.  I  still  have  doubts  as  to 
whether  the  yolk  granules,  the  "  chromidia,"  and  the  Golgi  bodies 
are  the  only  formed  structures  to  be  found  in  the  sponge  egg ;  and 
had  it  been  possible  I  should  have  )  iked  to  have  made  many  further 
trials  with  modified  mitochondrial  methods  to  try  to  detect  a  finer 
granulation  which  might  be  something  apart  from  Jorgensen's 
"  chromidia,"  which  at  present  I  believe  to  be  the  mitochondria. 
The  only  points  which  make  me  doubt  an  interpretation  of  these 
^'  chromidia  "  as  mitochondria  are  : — 

(a)  Nucleolar  "  chromidia  "  (so-called)  and  true  mitochondria 

both  exist  in  Saccocirrus. 

(b)  The  fixing  reactions  of  the  sponge  "  chromidia  "  are  not 

exactly  similar  to  those  of  most  metazoon  mitochondria. 

Of  course,  neither  of  these  points  may  signify,  but  I  have  tliought 
it  necessary  to  bring  them  forward.  It  should  be  remarked  that 
the  archiannelid  oogenesis  is  probably  unique  in  the  animal 
kingdom,  and  the  "  chromidia  "  of  the  sponge  in  later  stages  of 
oogenesis  approximate  closely  to  the  fixing  reactions  of  the  mito- 
chondria of  other  animals. 

Addendum  I. 

Dr.  Bidder,  of  Cambridge,  showed  me  recently  a  preparation  of 
Sycon  to  illustrate  what  he  calls  "  dolly  "  cells.  One  slide  impressed 
me  very  much  because  it  showed  two  large  cells  partly  protruding 
from  a  "  cloaca,"  and  to  each  of  these  cells  was  attached  a  much 
smaller  cell  the  expected  size  of,  flagellate,  and  closely  resembling 
a  sponge  spermatid.  I  consider  that  these  cells  found  by  Dr.  Bidder 
might  be  changing  spermatozoa  which  have  become  attached  to 
the  large  cells,  though  it  would  not  be  possible  to  give  an  opinion 
of  value  until  one  had  personally  studied  the  material. 

Addendum  II. 

A  few  months  ago  Mr.  Julian  Huxley  showed  me  some  of  his 
slides  illustrating  his  work  on  sponges  (6).  As  is  well  known 
H.  V.  Wilson  found  that  sponges  could  be  strained  through  fine 
gauze  so  as  to  separate  their  individual  elements,  and  many  of  the 
latter  could  come  together  again  and  regenerate  to  form  a  new 
sponge  (8).  Mr.  Huxley  repeated  Wilson's  work,  and  among  the 
new  sponges   or  regenerates  procured   by  this  method  he  found 


282  Transactions  of  the  Societti. 

some  which  seemed  to  be  surrounded  by  bodies  resembling  sperma- 
tozoa ;  he  kindly  drew  my  attention  to  these  examples,  and  allowed 
me  to  restain  certain  of  his  Sycon  slides,  from  which  I  was  able  to 
come  to  a  definite  opinion  that  these  bodies  in  question  resembled 
the  ordinary  metazoon  sperm  in  detail,  and  had  a  tail  sheath 
staining  in  crystal  violet.  While  it  is  possible  to  identify  these  as 
spermatozoa,  the  evidence  that  they  are  sponge  sperms  is  much 
less  complete ;  but  two  facts  must  be  borne  in  mind :  the  sperm 
in  Siyongilla,  according  to  Gorich,  is  filiform  and  flagellate  ;  the 
sperms  in  Mr.  Huxley's  slides  were  definitely  attracted  by  the 
collar  cell  regenerate  masses,  and  in  some  cases  seem  to  have 
penetrated  into  individual  collar  cells.  The  main  bulk  of  evidence 
is  therefore  that  in  the  Syconidse  the  sperm  is  flagellate  and  filiform, 
and  this  opinion  is  further  supported  by  the  figure  1  of  PL  Y.  in 
the  present  paper. 

Bibliography. 

1.  BucHNER,  p. — Oogenese  bei  Saccocirrus.     Arch.  Zellf.  (1914). 

2.  Bendy,  A. — Gametogenesis  of   Grantia  compressa.     Quart.  Journ.  Micr. 

Sci.  (1914). 

3.  Gatenby,  J.  Bronte. — The  Cytoplasmic  Inclusions  of  the  Germ  Cells. 

Part  VIIL,  Grantia  compressa.     Journ.  Linn.  Soc.  (1920). 

4.  Gorich,  W.—  Zur  Kenntnis  der  Spermatogenese  bei  den  Poriferen  und 

Coelenteraten.     Zeit.  wiss.  Zool.,  Bd.  26  (1903). 

5.  Hempelmann,  F.— Die    Geschlechtsorgane   und-Zehen  von  Saccocirrus. 

"  Zoologica,"  Heft  67  (1912). 

6.  Huxley,  Julian. — Some  Phenomena  of  Eegeneration  in  Sycon.     Phil. 

Trans.,  ccii.  (1911). 

7.  JorCtENSen,  M. — Beitrage  zur  Kenntnis  de  Eibildung,  Reifung,  Befruch- 

tung  und  Furchung  bei  Schwammen.     Arch.  Zellf.,  Bd.  4  (1910). 

8.  Wilson,  H.  V. — Coalescence  and  Rejuvenation  in  Sponges.     Jouru.  Exp. 

Zool.,  V.  (1907). 


283 


X. — A    Universal  Microtome. 
By  SiK  Horace  Darwin,  F.E.S.,  and  Mr.  W.  G.  Collins. 

[Bead  June  16,  1920.) 
Four  Text-figures. 

The  Cambridge  Rocking  Microtome  was  designed  and  first  made 
in  1885 ;  it  has  been  much  used  and  undoubtedly  is  a  successful 
instrument.  The  Universal  Microtome  has,  we  believe,  all  the 
good  features  of  the  Eocking  Microtome,  and  at  the  same  time  lias 


Fig.  1. 


the  additional  advantage  that  flat  sections  are  cut.  The  instru- 
ment is  well  adapted  for  cutting  objects  embedded  in  paraffin  or 
celloidin,  or  frozen  preparations  ;  it  is  also  convenient  for  the 
ribbon  or  serial  method  in  paraffin,  and  for  Apathy's  "  series  on 
the   knife"  method   in  celloidin.     This  microtome  differs  in  its 


284  Transactions  of  the  Society. 

action  and  appearance  from  most  other  microtomes,  and  we  will 
first  give  a  short  description  of  it,  and  then  the  reasons  wliy  we 
consider  the  special  construction  is  advantageous,  and  further 
details  of  some  of  its  parts. 


Brief  Description. 

The  microtome  (see  fig.  1),  which  is  made  almost  wholly  of  cast 
iron,  has  a  circular  base  250  mm.  in  diameter,  with  three  cork  feet 
which  rest  on  the  table.  The  object  moves  and  the  knife  is  fixed. 
The  knife  is  machine  ground  and  is  clamped  at  botli  ends  to  the 
knife-holder,  but  can  be  slid  longitudinally  in  the  holder  to  bring 
a  different  part  of  its  edge  into  action,  it'  one  part  is  blunted.  Its 
cutting  edge  is  horizontal,  and  can  be  adjusted  to  give  the  best 
angle  of  cut.  The  knife-holder  can  be  moved  laterally  and  clamped 
to  the  base  at  any  convenient  position.  It  can  be  also  rotated 
about  a  vertical  axis  so  as  to  give  a  slicing  cut — that  is,  the  direc- 
tion of  the  cutting  edge  of  the  knife  can  be  placed  at  an  acute 
angle  to  the  direction  of  the  movement  of  the  object.  The  object 
is  fixed  in  an  orientating  object-holder,  very  rigid  in  construction 
and  carried  at  the  outer  end  of  a  iiorizoiital  swinging  arm.  This 
swinging  arm  can  rotate  at  its  inner  end  about  a  vertical  axis. 
Thus  the  object  moves  in  a  horizontal  plane  along  the  arc  of  a 
circle  and  not  in  a  straight  line.  The  action  is  like  the  swinging 
of  a  gate  with  the  object  carried  at  a  point  near  the  latch.  In  the 
microtome  the  hinges  are  constructed  so  as  to  allow  both  rotation 
and  movement  along  the  vertical  axis  of  rotation  of  the  hinges. 
It  is  by  means  of  this  vertical  sliding  movement  that  the  object  is 
raised  between  successive  s^tions.  The  micrometer  screw  and  nut 
for  giving  this  vertical  movement  to  the  object  are  similar  to  that 
used  in  the  Eocking  Microtome.  The  method  of  feeding  the  screw 
forward  and  the  handle  for  moving  ihe  object  past  the  knife  are 
also  similar.  In  the  new  microtome  the  feed  screw  A  (see  fig.  2) 
is  ap})roximately  vertical  and  is  given  a  small  rotary  motion  at  the 
end  of  each  stroke  from  a  pawl  B,  orried  on  the  oscillating  handle 
C,  which  pawl  engages  with  a  large  steel  ratchet  wheel  D  at  the 
lower  end  of  the  screw.  This  partial  rotation  elevates  the  feed  nut 
E  on  which  is  carried  the  outer  end  of  the  feed  lever  F.  The 
design  is  such  that  this  nut  cannot  rotale  about  the  feed  screw,  but 
is  free  to  rock  with  respect  to  the  feed  lever  as  it  rises.  Tlie  feed 
screw  is  supported  in  a  conical  seating  at  its  lower  end  so  that  the 
nut  and  screw  can  adapt  themselves  to  tlie  movements  of  the  feed 
lever.  Tlie  large  end  of  this  lever  which  extends  across  the  micro- 
tome is  supported  on  horizontal  knife  edges,  working  on  planes  of 
the  same  design  as  the  vertical  knife  edges  and  planes  of  the 
swinmn<4  arm.     The  axes   of  these  two   sets   of  knife  edc^es   are 


A    Universal  Microtome, 


285 


therefore  at  right  angles  to  each  other,  but  do  not  intersect.  At  a 
point  which  we  will  call  tlie  "  feed  point "  a  projection  on  the  feed 
lever  intersects  the  vertical  axis  of  the  knife  edges  of  the  swinging 
arm  and  engages  with  this  arm  through  a  special  connecting  pin 


Fig.  2. 


described  below.  It  will  be  clear  that  if  this  feed  point  be  between 
the  feed  nut  and  the  fulcrum  of  the  feed  lever  it  will  rise  as  the 
feed  nut  rises  and  carry  the  swinging  arm  with  it.  In  this  micro- 
tome the  feed  point  is  considerably  nearer  to  this  fulcrum  than  to 
the  feed  nut,  and  consequently  the  swinging  arm  has  less  vertical 


286  Transactions  of  the  Society. 

motion  than  has  the  feed  nut.  At  its  lower  end  tlie  connecting 
pin  seats  into  a  conical  hole  in  the  feed  lever  and  at  its 
upper  end  into  a  conical  hole  in  the  swinging  arm.  This  pin  is 
kept  in  compression  and  in  geometric  contact  with  both  the  feed 
lever  and  the  swinging  arm  by  means  of  a  spring.  It  will  be 
seen  that  this  pin  remains  approximately  vertical  throughout  the 
motion,  and  that  che  swinging  arm  is  kept  at  a  constant  height 
during  the  cutting  stroke,  owing  to  its  point  of  contact  with  the 
feed  pin  being  on  its  axis. 

Flat  Sections. 

In  the  Eocking  Microtome  the  sections  are  cut  from  a  cylin- 
drical surface  of  90  mm.  radius.  If  the  section  is  5  mm.  in 
diameter  the  maximum  deviation  of  the  surface  of  the  cylinder 
from  a  plane  is  0 '  035  mm.  This  is  a  small  amount,  and  probably 
with  soft  tissues  the  deformation  of  the  parts  from  the  normal 
position  caused  by  embedding  or  freezing  is  far  greater  than  this. 
The  advantage  gained  by  cutting  flat  sections  is  sometimes  more 
imaginary  than  real,  but  it  is  not  infrequently  some  advantage, 
and  with  large  sections  it  is  well  worth  havincr. 


Horizontal  Sections. 

The  plane  of  the  sections  is  horizontal ;  this  is  advantageous 
for  paraffin  embedded  sections  as  the  correct  orientation  of  the 
object  is  far  easier,  and  this  position  is  essential  for  celloidin 
embedded  sections  as  the  lubricating  liquid  remains  on  the  knife, 
and  it  is  possible  to  float  off  the  sections,  which  is  not  the  case 
where  the  side  of  the  knife  is  in  a  vertical  plane.  For  frozen 
sections  a  horizontal  position  is  essential.  A  dissecting  lens  and 
stand  can  be  conveniently  used  during  the  precise  orientation  of 
the  object.  Eibbons  of  paraffin  embedded  sections  can  be  made 
witli  ease  by  this  microtome,  although  perhaps  their  manipulation 
requires  slightly  more  care  than  with  the  Eocking  Microtome. 
The  clamps  for  the  knife  have  been  designed  to  project  only  a 
little  above  the  knife  itself,  and  so  do  not  interfere  with  the  con- 
venient use  of  tlie  section  lifter ;  thus  delicate  handling  of  the 
sections  is  simpler,  and  the  danger  of  damaging  them  is  lessened. 


Uniform  Sections. 

In  all  cases  successive  sections  should  be  as  nearly  as  possible 
of  equal  thickness,  and  each  section  should  be  of  the  same  thick- 
ness throughout.  With  a  good  well-sharpened  knife  a  section  in 
paraffin  can  be  cut  as  thin  as  1  micron.     If  the  sections  with  a 


A    Universal  Microtome,  287 

thickness  of  2  microns  vary  by  not  more  than  +10  per  cent,  of 
their  thickness,  the  relative  displacement  of  the  knife  and  object 
from  any  cause  must  be  less  than  i  micron  (0-0002  mm.).  This 
is  a  very  small  amount,  and  it  is  clear  that  the  instrument  must  ]je 
rigid,  and  that  there  must  be  no  shake  in  any  of  the  parts.  Each 
nioving  part  must  in  fact  move  with  great  precision  along  its 
correct  path.  The  sections  are  cut  by  moving  some  part  of  the 
instrument  by  hand,  and  even  with  the  most  careful  use  there  is 
some  uncertain  pressure  of  the  hand  at  right  angles  to  the  direction 
of  the  movement  of  the  handle,  and  there  must  be  some  bending 
of  tlie  frame.  The  frame  should  therefore  be  rigid.  But  it  is  more 
important  still  to  design  the  instrument  so  that  this  uncertain 
force  has  little  or  no  effect  in  bending  those  parts  which  will  alter 
the  thickness  of  the  sections.  There  is  also  a  component  of  the 
cutting  force  at  right  angles  to  the  plane  of  the  section  acting 
between  the  cutting  edge  of  the  knife  and  the  object.  This  force 
is  not  constant,  especially  with  hard  sections.  These  considera- 
tions show  the  importance  of  rigidity  in  the  knife,  the  object 
holder,  the  moving  parts,  and  the  frame.  All  these  parts  bend 
when  force  is  applied  to  them,  and  it  is  of  comparatively  little  use 
to  make  the  frame  stiff  if  the  knife  or  the  object  holder  is  capable 
of  springing  under  the  forces  acting  on  them. 

In  some  sliding  microtomes  the  knife  is  clamped  at  one  end 
only ;  this  is  particularly  objectionable  when  cutting  objects 
emlDedded  in  celloidin  with  nearly  the  full  length  of  the  knife  in 
use,  as  the  sections  are  cut  by  a  part  of  the  knife  at  a  considerable 
distance  from  the  clamped  end,  and  the  knife  bends  more  easily. 
Clamping  the  knife  at  both  ends  very  greatly  increases  its  stiffness. 
In  the  new  microtome  the  knife  is  clamped  rigidly  at  both  ends  in 
the  adjustable  knife  holder,  which  can  be  firmly  clamped  to  the 
base  of  the  instrument. 

Orientating  object  holders  are  often  not  sufficiently  rigid,  and 
have  a  large  number  of  joints  with  possibility  of  slackness,  and 
when  provided  with  means  for  tightening  such  joints  have  the 
disadvantage  that  they  must  be  loosened  and  tightened  after  each 
adjustment.  The  orientating  object  holder  we  have  designed  for 
this  microtome  is  new  and  is  very  rigid. 

There  are  other  causes  of  want  of  uniformity  in  the  sections. 
In  microtomes  with  large  sliding  surfaces  the  irregular  distribution 
and  the  varying  thickness  of  the  film  of  oil  between  the  surfaces 
may  influence  the  thickness  of  the  sections.  The  collection  of 
dust  on  the  oiled  surfaces  wil]  have  the  same  effect.  The  oxidation 
of  the  oil  will  also  cause  trouble. 

In  the  new  instrument  no  oil  is  essential  on  any  surface  con- 
cerned with  the  precise  guiding  of  the  object,  although  it  is 
desirable  with  the  view  of  preventing  rust  that  such  surfaces  be 
oiled  or  greased.     The  moving  surfaces  in  contact  are  of  small  area 


288  Transactions  of  the  Society. 

and  the  pressure  between  them  is  large  ;  this  prevents  dust  from 
getting  in  and  ensures  an  extremely  thin  film  of  oil,  which  will 
not  vary  in  thickness  by  an  appreciable  amount.  These  bearings 
are  a  slightly  modified  form  of  the  knife  edge  and  plane  used  with 
such  success  in  the  Eocking  Microtome. 

Another  cause  of  irregularity  in  the  thickness  of  the  sections 
is  the  looseness  produced  by  the  wear  of  the  various  slides. 
Usually  the  slides  require  the  attention  of  a  skilled  mechanic  for 
their  proper  adjustment.  In  some  instruments  the  object  is  carried 
on  a  reciprocating  slide  with  a  comparatively  long  travel ;  this 
slide  will  wear,  and  then  precise  cutting  becomes  impossible  until 
skilled  attention  has  been  given  to  the  instrument. 

In  the  new  microtome  the  geometric  principle  is  adopted  in 
the  chief  moving  parts,  ensuring  accurate  working  without  shake, 
even  after  much  wear  of  the  rubbing  surfaces.  The  wear  at  these 
surfaces  is,  however,  small,  but  even  if  it  were  large  it  would  be 
all  taken  up  automatically  by  springs,  and  thus  no  shake  is  possible. 
Skilled  attention  is  not  required  to  keep  the  microtome  in  good 
order. 

Manipulation. 

In  cutting  sections  with  a  microtome  it  is  advantageous  that 
the  force  acting  on  the  object  during  cutting  should  be  transmitted 
accurately  to  the  hand.  This  is  markedly  the  case  in  this  micro- 
tome. The  connexion  between  the  hand  and  the  object  is  rigid, 
whereas  in  the  Eocking  Microtome  the  cutting  force  is  due  to  a 
spring.  But  what  is  more  important,  the  friction  and  inertia  of 
the  moving  parts  is  small.  In  the  majority  of  sliding  microtomes 
the  friction  is  considerable,  and  in  microtomes  of  the  Minot  pattern 
there  is  a  considerable  amount  of  inertia  of  the  moving  parts,  and 
the  friction  is  not  small  and  is  somewhat  uncertain  in  amount. 
The  connexion  between  the  hand  and  the  object  is  by  means  of  a 
crank  and  connecting  rod,  and  thus  the  ratio  of  the  force  on  the 
hand  to  the  force  on  the  object  varies  greatly  during  the  rotation 
of  the  handle.  The  ratio  of  the  velocity  of  the  hand  to  the  velocity 
of  the  object  also  varies  during  the  rotation  of  the  handle.  A 
variation  of  tlie  ratios  of  the  forces  and  velocities  takes  place  in 
the  Universal  Microtome,  but  the  variation  is  much  less.  A  fly- 
wheel of  considerable  weight  is  usually  fixed  to  the  crank  axle  in 
the  Minot  type  of  microtome.  This  increases  the  inertia  of  the 
moving  parts  and  ensures  more  uniform  velocity  of  the  hand  and 
less  uniform  velocity  of  the  object  relatively  to  the  knife.  We 
find  that  if  the  cutting  speed  is  too  high,  the  edge  of  a  hollow 
ground  knife  vibrates  and  irregular  work  may  be  produced.  If 
the  cutting  speed  is  uniform  throughout  the  stroke  it  is  easier 
to  prevent  it  ever  becoming  too  great,  and  if  the  inertia  of  the 


■     A    Universal  Microtome.  289 

moving  parts  is  small  the  speed  of  cutting  can  be  regulated 
instantly,  or  the  object  can  be  stopped  even  while  a  section  is 
being  cut. 

These  considerations  lead  us  to  think  that  a  continuous  rotation 
of  a  handle  is  not  the  best  method  of  giving  the  reciprocating 
movement  of  the  object  in  a  microtome,  and  we  have  adopted  a 
similar  design  to  that  used  in  the  Eocking  Microtome.  Many 
years'  experience  have  shown  that  this  movement  of  the  hand  is 
convenient  and  the  mechanism  is  simple  and  efficient.  A  radial 
bar  which  can  turn  about  a  vertical  axis  at  one  end  is  made  to 
oscillate  backwards  and  forwards  through  a  large  angle  by  means 
of  a  handle  fixed  at  its  other  end.  This  oscillation  moves  the 
object  past  the  knife  and  feeds  it  upward  at  the  end  of  the  return 
stroke,  the  feed  occurring  after  the  object  has  completed  its 
travel. 

The  foregoing  considerations  would  lead  one  to  expect  that 
with  very  little  skill  good  sections  can  be  cut  with  this  microtome, 
and  we  find  that  this  is  the  case.  We  also  believe  that  with  objects 
which  are  difficult  to  cut,  the  fact  that  the  force  exerted  by  the 
knife  on  the  object  is  directly  transmitted  to  the  hand  will  enable 
an  operator  to  make  the  best  use  of  his  skill,  and  may  there- 
fore enable  him  to  get  better  results  than  would  otherwise  be 
possible. 

The  amount  of  feed  for  giving  any  required  thickness  of  section 
is  set  instantly  and  requires  no  clamping.  Each  division  on  the 
scale  corresponds  to  1  micron  in  thickness,  and  sections  as  thick 
as  35  microns  can  be  cut. 

The  feed  or  micrometer  screw  is  fitted  with  a  milled  head 
which  permits  of  very  ready  fine  adjustment  of  the  object  to  the 
knife.  The  manipulation  of  the  orientating  object  holder  is  simple. 
The  object  (see  fig.  3)  is  clamped  in  a  vice  B,  which  has  a  cylin- 
drical stem  C  sliding  in  a  cylindrical  hole  in  the  sphere  D.  The 
sphere  is  cut  almost  completely  through  along  the  axis  of  the  hole, 
and  the  screw  E  which  clamps  it  also  serves  to  clamp  the  stem  of 
the  object  holder,  owing  to  the  geometrical  mounting,  at  whatever 
angle  the  sphere  may  be  in  its  seating.  To  orientate  the  object 
the  clamping  screw  is  slackened,  and  the  object  can  then  be 
rotated  in  any  direction  through  an  angle  of  16°  from  the  vertical, 
owing  to  the  movement  permitted  to  the  sphere.  It  can  also  be 
rotated  through  any  angle  about  a  vertical  axis,  and  can  be  raised 
or  lowered  owing  to  the  movement  of  the  stem  in  the  sphere,  and 
then  rigidly  clamped  by  the  single  screw. 

The  knife  holder  is  easily  adjusted  to  give  a  slicing  cut ;  it  can 
also  be  moved  so  that  sections  can  be  cut  with  new  parts  of  the 
knife  as  it  becomes  blunt  or  damaged.  The  knife  thus  requires 
less  frequent  sharpening,  much  time  is  saved,  and  good  work  can 

u 


290 


Transactions  of  the  Society. 


be  done  afc  once  after  the  knife  has  been  shifted.  The  knife  F 
(fig.  3)  itself  is  longer  than  the  distance  between  the  two  clamps 
H,  Hi,  and  can  be  shifted  lengthwise  in  the  clamps,  again  increas- 
ing the  proportion  of  the  cutting  edge  of  the  knife  that  can  be 
used.  The  knife  holder  can  be  moved  so  as  to  place  the  object  as 
near  the  knife  as  desired  before  the  cutting  begins.  The  knife  can 
also  be  adjusted  in  the  knife  holder.     To  do   this  the  knife  is 


Fig.  3. 


rotated  about  a  line  parallel  to  tlie  cutting  edge  and  then  clamped 
in  that  position.  The  movement  is  given  by  a  double  wedge 
(fig.  4),  which  lifts  the  back  of  the  blade  at  the  two  places  where 
it  is  clamped.  The  wedge  is  moved  by  a  screw  with  a  divided 
head  F,  indicating  the  amount  of  the  angular  movement.  The 
best  clearance  angle  for  cutting  depends  on  the  material  to  be  cut 
and  on  the  form  of  the  cutting  edge  of  the  knife ;  when  this  angle 


A    Universal  Microtome. 


291. 


Fig.  4. 


is  found  by  trial  the  knife  can  be  re-set  at  the  same 
graduations  on  the  divided  head  have  been  noted. 


angle 


if  the 


Other  Details  of  the  Desigx. 

A  well-designed  instrument  should  work  well  when  worn  or 
damaged,  and  it  should  be  robust  and  have  few  or  no  delicate 
parts  requiring  careful  handling.  We  believe  that  the  new  instru- 
ment fulfils  these  conditions.  It  is  as  robust  as  the  Kocking 
Microtome,  and  will  stand  rough  treatment  equally  well ;  it  will 
cut  good  sections  after  long  use,  or  even  when  slightly  damaged. 
The  principle  of  geometrical  design  has  been  largely  used  in  the 
moving  parts,  so  that  no  unnecessary  constraint  is  given  to  them 
and  shake  is  automatically  eliminated.  The  nut  on  the  micrometer 
screw  is  an  exception ;  it  is  always  pressed  in  one  direction  and 
there  can  be  no  shake.  The  clamping  devices  for  the  knife  holder 
and  the  knife  itself  are  not  geometric,  but  there  is  no  movement 
when  these  parts  are  clamped,  and  we  believe  that  it  is  best  not  to 
make  them  geometric. 

The  other  places  where  movement  takes  place  and  where  the 

u  2 


292  Transactions  of  the  Society. 

fit  is  geometric  are  : — The  bottom  bearing  of  the  micrometer  screw  ; 
the  connexion  of  the  micrometer  screw  nut  to  the  end  of  the  feed 
lever ;  the  fulcrum  of  this  lever ;  the  fulcrum  of  the  swinging 
arm;  the  connexion  between  this  lever  and  the  swinging  arm 
carrying  the  object;  and  the  clamp  for  the  sphere  carrying  the 
object  holder. 

Vertical  Movement  of  the  Object. 

As  previously  mentioned  a  difference  of  10  per  cent,  in  the  thick- 
ness of  two  successive  sections  amounts  to  0  *  0002  mm.  with  sec- 
tions 0  •  002  mm.  thick.  It  is  clear  that  the  nut  on  the  micrometer 
screw  must  transmit  its  movement  to  the  object  with  great 
accuracy.  Now  there  must  be  friction  in  the  vertical  movement 
of  the  swinging  arm  on  its  knife  edges.  The  first  very  small 
movement  of  the  micrometer  screw  will  move  the  nui  a  very  small 
amount ;  the  first  effect  will  be  to  bend  the  lever  connecting  the 
nut  to  the  sliding  part,  and  this  bending  will  go  on  till  there  is 
sufficient  force  to  overcome  the  friction  of  the  slide.  It  would 
seem  that  the  relation  between  the  movement  of  the  object  and 
the  micrometer  screw  might  not  be  perfect.  The  danger  of  this 
error  is  increased  because  the  nut  is  connected  to  the  slide  by  a 
lever,  and  this  must  have  more  spring  in  it  than  when  the  con- 
nexion is  more  direct.  We  considered  this  point  and  came  to  the 
conclusion  that  it  would  not  cause  an  appreciable  error  for  the 
following  reason,  and  experiments  proved  we  were  right : — 

The  vertical  sliding  part  is  also  the  axis  of  rotation  of  the 
swinging  arm.  Now  it  is  well  known  that  a  rotating  shaft  even 
when  carrying  a  heavy  wheel  can  be  moved  endways  by  the 
slightest  force  ;  although  when  it  is  at  rest  the  force  ret|uired  to 
move  it  is  great.  We  all  know  that  less  force  is  required  to  pull 
a  cork  out  of  a  bottle  if  the  cork  is  rotated  at  the  same  time,  and 
most  of  us  have  done  this  without  realizing  the  reason.  The  same 
thing  happens  in  the  vertical  axis  of  the  microtome ;  the  micro- 
meter screw  is  turned  and  the  swinging  arm  rotates  ;  this  causes  a 
slight  movement  of  the  rubbing  surfaces  in  the  vertical  slide  in  a 
direction  at  right  angles  to  the  direction  in  which  the  sliding  parts 
should  move.  This  eliminates  the  effect  of  friction  so  far  as  it 
acts  in  the  vertical  direction  in  which  the  sliding  motion  takes 
place,  and  the  ratio  of  the  movement  of  the  micrometer  screw  to 
the  vertical  movement  of  the  object  is  constant. 

A  defect  in  many  microtomes  is  that  either  the  diameter  of 
the  micrometer  feed  screw  is  too  small  or  that  the  pitch  is  very 
fine,  and  not  infrequently  both  of  these  defects  are  present  in  the 
same  instrument.  In  the  first  case  the  screw  is  readily  bent,  and 
in  the  second  case  the  amount  of  wearing  surface  between  the  nut 
and  the  screw  on  which  it  works  is   small,  and  the  wear  soon 


A    Universal  Microtome.  293 

becomes  serious.  In  this  microtome  the  screw  is  robust  and  of 
large  diameter,  and  the  pitch  i<5  1  mm.,  which  is  not  too  fine. 

The  knives  are  ground  in  a  macliine  which  gives  a  true 
rectilinear  movement  to  the  grinding  wheel,  thus  ensuring  a 
straight  cutting  edge.  This  is  especially  important  when  a  slicing 
cut  is  used  for  cutting  sections.  The  back  of  the  knife  is  also 
straight  and  parallel  to  the  cutting  edge.  The  knife  is  in  fact  a 
true  prism.  When  this  condition  is  fulfilled  the  cutting  edge 
remains  straight  when  the  knife  is  sharpened  on  the  hone,  and  it 
is  far  easier  to  produce  a  thoroughly  satisfactory  cutting  edge.  By 
the  special  process  of  grinding  adopted  it  is  easy  to  make  the 
knives  more  or  less  hollow  ground  to  suit  different  conditions. 

The  microtome  was  designed  and  made  by  the  Cambridge  and 
Paul  Instrument  Company.*  In  the  design  of  the  mechanism  it 
resembles  the  Eocking  Microtome,  which  was  designed  and  made 
in  the  Cambridge  Works.  Many  of  the  good  features  in  this 
instrument  are  due  to  the  care  and  thought  given  to  them  by 
members  of  the  staff  of  the  company.  Tlie  method  of  adjusting 
the  cutting  angle  of  the  knife  is  the  design  of  Mr.  C.  C.  Mason, 
and  the  orientating  object  holder  is  due  to  Mr.  J.  L.  Orchard. 

Summary. 

We  believe  that  the  advantages  of  this  microtome  may  be 
briefly  summarized  as  follows  : — 

1.  The  sections  are  fiat  and  are  cut  in  a  horizontal  plane. 

2.  Sections  of  any  thickness  in  steps  of  1  micron  may  be  cut 
between  2  and  35  microns. 

3.  Owing  to  the  rigid  and  geometric  design  of  the  instrument, 
each  section  is  of  uniform  thickness,  and  successive  sections  are  of 
equal  thickness. 

4.  Most  of  tlie  cutting  edge  of  the  knife  can  be  used  so  that 
the  knife  requires  the  minimum  amount  of  sharpening. 

5.  The  object  holder  can  be  readily  adjusted  in  every  direction. 

6.  The  instrument  is  robust. 

7.  As  there  is  little  friction  and  the  moving  parts  of  the 
instrument  are  light,  it  is  possible  to  "follow  through"  with  one's, 
hand  whilst  the  sections  are  being  cut. 

*  Patents  have  been  applied  for  on  this  instrument. 


295 


XI. — Preliminary  Tests  on  the  Homologue  of  the  Golgi 
Apparatus  in  Plants. 

By  A.  H.  Drew,  D.Sc,  RE.M.S. 

{Bead  April  21,  1920.) 
Four  Text-figures. 

At  the  March  Meeting  of  the  Eoyal  Microscopical  Society  I 
demonstrated  certain  cytoplasmic  inclusions  in  the  cells  from  the 
root-tip  of  the  onion  closely  resembling  or  identical  with  the 
Golgi  apparatus  of  animal  cells.  Guilliermond  {!)*  has  recently 
described  similar  appearances  in  the  roots  of  the  pea  and  barley  as 
filamentous  mitochondria,  and  noted  their  resemblance  to  the 
Golgi  apparatus.  The  present  note  puts  on  record  the  appearances 
seen  in  the  onion  and  the  method  used. 

Growing  root-tips  are  fixed  for  twenty-four  hours  in  formol, 
20  com.  ;  cobalt  nitrate,  2  grm. ;  sodium  chloride,  0  8  grm. ;  water 
to  100  c.cm.  (preferably  at  37°  C.).  Frozen  sections  are  cut  after 
soaking  in  gum-syrup  for  at  least  an  hour.  The  sections,  after 
washing  in  water,  are  fixed  on  gelatin-coated  slides  with  formalin, 
rinsed  in  water  to  remove  excess  of  formalin  and  mordanted  at 
50°-55°  C.  in  chromic  acid,  4  p.c,  osmic  acid,  2  p.c,  equal  parts, 
on  the  slide  for  varying  periods — fifteen  minutes  to  one  hour  or 
longer.     The  staining  is  tlien  carried  out  as  follows  : — 

Einse  in  water  and  stain  with  iron-alum,  3  p.c,  fifteen  minutes, 
followed  by  J  p.c.  hematoxylin  fifteen  minutes  at  50°  C.  Differen- 
tiate in  3  p.c.  iron-alum,  cold,  till  the  nuclei  are  pale  brown,  transfer 
to  2  p.c.  pyridin  two  minutes,  wash  in  running  water  two  to  five 
minutes  and  mount  in  xylol-balsam. 

In  specimens  chromated  for  the  shorter  periods,  the  mitochon- 
dria only  are  visible  in  addition  to  the  nuclei.  These  are  usually 
of  the  granular  variety,  but  also  occur  as  very  fine  short  rods 
staining  very  black  with  heematoxylin.  They  are  extremely 
numerous  and  are  scattered  over  the  whole  of  the  cytoplasm  (see 
fig.  1).  The  mitochondria  may  also  be  well  seen  when  stained  by 
Hollande's  chloro-carmine  {2),  but  the  Golgi  apparatus  is  not 
stained  by  this  method.  In  sections  mordanted  with  the  chrom- 
osmic  solution  for  longer  periods,  it  is  found  that  the  mitochondria 
stain  very  much  more  faintly,  and  new  structures  begin  to  make 

*  The  italic  figures  within  brackets  refer  to  the  Bibliography  at  end  of  the 
paper. 


296 


Transactions  of  the  Sonet//. 


Fig.  1 — Central  cell  of  onion  root. 
Mitochondria  only  stained,  no  Golgi 
apparatus.  Short  mordanting  with 
chrom-osmic  mixture  on  slide. 
Iron-alum  hsematoxylin.    x  1300/1, 


Fig.  3. — Cell  midway  between  centre 
and  surface  of  onion  root.  Long 
mordanting  with  chrom-osmic  mix- 
ture. A  few  mitochondria  and 
delicate  and  coarse  Golgi  elements. 
X  1800/1. 


Fig.  2. — Central  cell  of  onion  root» 
Long  mordanting  with  chrom-osmic 
mixture.  No  mitochondria  :  Golgi 
apparatus  long  and  short  filaments 
forming  a  dense  network  around 
nucleus  and  scattered  filaments 
throughout  cytoplasm,      x  1800/1. 


Fig.  4. — Surface  cell  of  onion  root. 
Long  mordanting  with  chrom-osmio 
mixture.  Granular  mitochondria 
and  oval  lenticular  Golgi  elements. 
X  1300/1. 


Homolofiue  of  tlie  Golrji  Ajjpa-ratus  in  Plccnts.  297 

their  appearance.  These  consist  of  darkly  staining  oval  and  elon- 
gated bodies,  many  clustered  around  the  nuclei.  They  are  most 
easily  demonstrated  in  the  superficial  cells  (see  figs.  3  and  4),  and 
in  them  they  are  almost  entirely  short,  oval,  flattened  elements. 
If  the  mordanting  be  pushed  still  further,  the  mitochondrial  elements 
no  longer  stain,  whilst  the  Grolgi  apparatus  stains  more  intensely 
and  becomes  evident  in  the  great  majority  of  the  cells.  In  the 
central  cells,  especially,  it  occurs  as  coarse  and  irregular  filaments 
and  rods,  many  closely  adherent  to  the  nuclei  (see  fig.  2).  (The 
same  effect  of  prolonged  mordanting  has  been  demonstrated  in 
animal  cells,  where  again  it  is  found  that  the  shorter  chromating 
only  brings  out  the  mitochondria,  whilst  these  stain  more  faintly 
after  longer  mordanting  and  the  GolgL  apparatus  appears).*  From 
their  general  appearance,  their  relation  to  the  nucleus,  and  their 
behaviour  with  chroni-osmic  a(ud  it  is  reasonable  to  class  these 
structures  in  plants  with  the  Golgi  apparatus  of  animal  cells.  This 
is  also  suggested  by  their  sensitiveness  to  external  conditions,  as 
well  as  to  the  histological  differentiation  of  the  cells  at  the  time  of 
fixation.  During  mitosis  the  Golgi  apparatus  is  distributed  l^etween 
the  two  daughter-cells,  but  I  have  not  been  able  to  ascertain  with 
what  degree  of  accuracy  it  is  divided  between  the  two. 

Eeferences. 

1.  A.  GuiLLiERMOND — C.  E.  Soc.  Blol.,  Ixxxlli.  (1920)  pp.  408  and  411. 

2.  A.-Ch.  Hollande— C.  R.  Soc.  Biol.,  Ixxix.  (1920)  p.  662. 

*  The  Cajal  silver  method  is  not  successful  with  plant  tissues,  but  sections 
stained  in  this  manner  showed  that  the  elongated  bodies  stained  with  the  silver, 
which  is  additional  evidence  as  to  their  identity  with  the  Golgi  apparatus. 


299 


SUMMARY  OF  CURRENT  RESEARCHES 

RELATING   TO 

ZOOLOGY     AND      BOTANY 

(principally  invertebrata  and  cryptogamia), 

MICEOSCOPY,  Etc.* 


ZOOLOGY. 

VERTEBRATA. 

'J't    Embryolog-y,  Evolution,  Heredity,  Reproduction, 
and  Allied  Subjects. 

Interstitial  Cells  in  Ovary  of  Bats. — M.  Athias  {Arch.  Biol.,  1919, 
30,  89-212,  1  pi.).  Interstitial  glandular  tissue  was  found  in  all  the 
bats  studied  ;  in  Vespertilionid^  it  forms  the  greater  part  of  the  ovarian 
stroma  ;  in  Rhinolophidae  it  is  much  less  developed  ;  it  occurs  in  the 
ovaries  of  the  foetus  and  the  young  animal,  as  well  as  in  adults.  During 
pregnancy  and  lactation  the  interstitial  tissue  is  at  its  maximum  ;  in 
autumn  it  suffers  considerable  reduction  ;  towards  the  middle  of  winter 
it  begins  to  increase  again.  The  tissue  consists  of  masses  of  cells 
separated  by  a  connective  reticulum,  rich  in  blood  vessels.  In  this 
respect  the  architecture  is  like  that  of  an  endocrine  gland.  In 
Yespertilionid^  the  interstitial  cells  occupy  the  whole  extent  of  the 
cortical  or  parenchymatous  zone  of  the  ovary,  but  always  leave  a  clear 
band  at  the  periphery  below  the  germinative  epitheliam.  This  more 
or  less  narrow  band  includes  the  young  oocytes  and  the  primordial 
follicles.  The  medullary  zone,  the  importance  of  which  varies  a  good 
deal  in  different  species,  contains  the  same  elements,  isolated  or  in  small 
groups.  In  the  Rhinolophidas  the  interstitial  elements  are  situated 
round  about  the  atresic  follicles,  and  there  are  also  sometimes  masses  in 
the  inter-follicular  spaces  and  in  the  vascular  zone  of  the  ovary. 
The  interstitial  cells  have  glandular  characters — abundant  chondriome, 
enclosures  of  lipoid  substance,  siderophilous  protoplasm,  and  nuclei 
marked  by  very  distinct  polychromaticity.  The  chondriome  consists 
of  chondrioconts  and  mitochondria.  The  lipoid  enclosures  are  certainly 
the  results  of  secretory  processes.     In  young   females  the  interstitial 

*  The  Society  does  not  hold  itself  responsible  for  the  views  of  the  authors 
of  the  papers  abstracted.  The  object  of  this  part  of  the  Journal  is  to  present 
a  summary  of  the  papers  as  actually  published,  and  to  describe  and  illustrate 
Instruments,  Apparatus,  etc.,  which  are  either  new  or  have  not  been  previously 
described  in  this  country. 


300      SUMMARY  OF  CURRENT  RESEARCflES  RELATING  TO 

cells  arise  from  all  the  connective  elements  of  the  stroma  of  the  ovary. 
Later  on  they  arise  chiefly  from  the  cells  of  the  internal  theca  of  the 
atrcsic  follicles.  They  form  first  the  false  corpora  lutea  as  a  transition 
stage.     In  the  adult  there  is  also  a  transformation  of  cells  of  the  inter- 


vv;^.- 


A  group  of  interstitial  cells  in  the  ovary  of  an  adult  Serotinus,  showing 
alveolar  cytoplasm  and  numerous  mitochondria. 

follicnlar  stroma  into  interstitial  cells.  The  interstitial  cells  in  the  bat 
do  not  seem  to  have  to  do  with  rut  and  ovulation,  but  probably  with 
the  nutrition  of  the  genital  system  and  with  the  determination  of  the 
secondary  sex  characters.  J.  A.  T. 

Parthenogenetic  Development  and  what  it  Suggests. — M.  Her- 
LANT  (Arch.  ZooL  Exper.,  191:),  58,  291-:-514).  (1)  The  simple  activa- 
tion of  the  ovum  of  Faracentrotus  lividns  by  means  of  butyric  acid 
is  characterized  by  the  formation  of  a  monaster  which  repeats  itself 
rhythmically  without  ever  provoking  segmentation.  Only  after  numerous 
attempts  at  division  does  the  ovum  begin  to  suffer  self-destruction  by 
cytolysis.  But  this  is  merely  tlie  final  result  of  cytological  conditions 
incompatible  with  life  ;  it  is  not  their  cause.  (2)  Following  Loeb's 
method,  Herlant  subjected  the  ova,  activated  by  butyric  acid,  tO' 
hypertonic  solution.  A  new  reaction  is  artificially  induced  which  gives 
the  monaster  the  bipolarity  which  it  lacks.  This  makes  segmentation 
and  development  possible.  (3)  No  structure  in  the  cell  is  indispensable 
to  division  of  the  cell  as  a  whole  or  of  parts  of  the  cell.  The  division 
of  the  cell  is  the  sum  of  a  series  of  particulate  and  independent  divisions. 
Thus  the  division  of  the  chromosomes  is  not  the  consequence  of  the 
division  of  the  centrosome.  There  is  a  general  physico-chemical  change 
in  the  economy  of  the  cell.  J.  A.  T. 

Spermatogenesis  of  Horse.— K.  Masui  (Jouni.  CoU.  Agric.  Imp. 
Univ.  Tokyo,  191!),  3,  ;}.")7-76,  3  pis.).  The  resting  nucleus  of  the 
spermatogonium  contains  a  large  nucleolus  and  several  small  chromatin 
masses.  In  the  metaphase  of ^the  spormatogouia  the  numerous  chromo- 
somes  are   divided   at   the  same  time.     Many  symmetrical  pairs  were- 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    KTC.  301 

distinguishable,  but  a  count  was  not  possible.  The  resting  nucleus  of 
the  primary  spermatocyte  contains  a  large  chromatin  nucleolus.  The 
conjugation  of  the  chromatin  threads  takes  place  by  parasynapsis. 
The  chromosome  nucleohis  presents  itself  throughout  the  synapsis  and  the 
growth  stages.  In  the  primary  spermatocyte  the  idiozome  is  conspicu- 
ously present.  The  number  of  chromosomes  in  the  first  division  is  nine- 
teen— namely,  eighteen  bivalent  and  one  accessory.  The  first  division 
is  reducing  and  heterotypic.  The  accessory  chromosome  now  passes 
undivided  to  one  pole,  thus  producing  two  groups  of  spermatocytes,  one 
with  and  the  other  without  the  accessory  chromosome.  The  resting 
stage  of  the  secondary  spermatocytes  seems  to  be  very  short.  The 
second  pairing  of  the  chromosomes  in  the  second  division  was  not 
observed.  The  second  division  is  equal  and  homotypic.  The  accessory 
chromosome  divides  like  the  ordinary  ones.  The  behaviour  of  the 
centrosome  in  the  development  of  the  spermatozoa  is  almost  the  same 
as  that  described  by  Meves  for  man.  The  chromatoid  corpuscle, 
appearing  in  the  growth  stage,  seems  to  be  cast  out  finally.  The 
mitochondria  appear  during  the  postsynaptic  stage.  In  the  spermatids 
most  of  them  give  rise  to  a  mass  similar  to  the  "  Nebenkern "  of 
insects  ;  the  main  portion  finally  comes  to  occupy  the  middle  part  of 
the  spermatozoon.  J.  A.  T. 

Spermatogenesis  in  Ox. — K.  Masui  {Journ.  Coll.  Agric.  Imp.  Univ. 
Tokyo,  1919,  3,  377-403,  3  pis.,  1  fig.).  In  embryos  and  quite  young 
animals  the  spermatogonia  divide  by  amitosis.  The  cells  seem  to  be 
degenerating,  being  used  as  nutritive  materials  by  others.  The  resting 
nuclei  in  both  the  last  and  the  penultimate  spermatogonial  generations 
usually  contain  a  large  nucleolus  and  a  small  chromatin  mass.  The 
number  of  chromosomes  in  the  spermatogonia  is  thirty-three  ;  they 
vary  considerably  in  size  and  form,  but  occur  in  pairs.  Each  splits 
longitudinally  along  the  cleft  which  appeared  in  the  spireme  stage.  No 
special  chromosome  with  different  behaviour  was  to  be  seen.  In  the 
telophase  of  the  last  spermatogonia  the  chromosomes  are  not  fused. 
They  become  lengthened  into  leptotene  threads.  Conjugation  of 
chromosomes  probably  takes  place  by  telosynapsis  during  the  synaptene 
stage.  In  this  stage  the  leptotene  threads  converge  towards  one  side  of 
the  nucleus,  leaving  a  clear  space  on  the  other  side.  During  the  final 
prophase  the  longitudinal  splitting  and  transverse  constriction  of  the 
chromosomes  are  to  be  seen.  The  chromosomes  are  divided  along  the 
constriction  in  the  first  reducing  division.  In  the  second  reducing 
division  all  the  chromosomes  become  so  placed  that  the  line  of  the 
longitudinal  split  coincides  with  the  equatorial  plane,  and  along  this 
line  all  the  chromosomes  (the  accessory  ones  included)  are  divided  at  the 
same  time.  Thus  it  is  simply  an  equation  division.  In  the  sperma- 
togonia and  the  spermatocytes  the  centrosome  is  so  minute  that  it 
cannot  be  distinguished  from  the  other  granules.  Its  changes  during 
the  formation  of  spermatozoon  can  be  followed  and  are  seen  to  differ 
considerably  from  those  in  the  horse.  The  chromosome  nucleolus  or 
the  accessory  chromosome  can  be  traced  throughout  the  growth  stage 
and  the  reduction  division.     The  idiosome   appears   as   a   cytoplasmic 


302 


SUMMARY    OF   CURRENT   RESEARCHES   RELATING   TO 


body  in  the  growth  stage,  and  during  the  formation  of  the  spermatozoon 
it  becomes  more  and  more  conspicuous,  till  it  assumes  the  appearance  of 
a  small  spherical  body  and  comes  to  be  situated  in  a  depression  at  the 
anterior  part  of  the  nucleus.  It  seems  to  have  no  connexion  with  the 
centrosome.  Mitochondrial  granules  are  abundant  during  the  growth 
stage.  Second  pairing  of  chromosomes  is  not  found,  but  as  in  the  case 
of  the  horse  incomplete  fusion  of  the  chromosomes  is  seen  to  occur.  In 
such  a  case  nine  or  ten  chromosomes  are  occasionally  to  be  counted. 
The  chromatoid  corpuscle  cannot  be  found,  but  during  the  reduction 
division  a  small  spherical  body,  staining  faintly  with  iron-ha3matoxylin, 
appears  in  rare  cases  in  the  cytoplasm.  J.  A.  T. 

Development  of  Gobies.— C.  G.  Joh.  Petersen  {Report  Danish 
Biol.  Stat,  1920,  26,  45-66,  3  pis.).  Notes  on  the  young  stages  of 
five  species  of  Golius  and  of  Lebetus,  Crystallorjolius^  and  Aiihya,  with 
particular  attention  to  the  pigmentation  at  various  stages.  The  eggs  of 
gobies  are  found  in  enormous  numbers  in  Danish  fjords  ;  the  develop- 
ment as  a  rule  takes  place  in  less  than  a  year  ;  there  is  considerable 
migration  of  the  adults  of  several  species.  The  chief  aim  of  the  paper 
is  to  facilitate  the  identification  of  the  young  stages  of  different  species 
of  Gobiid^.  J.  A.  T. 

Development  of  Vascular  System  in  Embryo  Stickleback. — R. 
Anthony  lArch.  Zool.  Exper.,  1918,  57,  1-45, 1  pi.,  31  figs.).   A  study  of 


Larva  of  Stickleback  {Gasterosteus  ^^/^mi^^r-ws),  thirty-eight  hours 
after  hatching. 

0.,  eye;  C,  heart;  V.a.,  auditory  vesicle;  R.b.,  branchial  rays; 
G.h.,  oil  globule;  "r.i;.?^.,  median  vitelline  vein;  B.v.,  vitelline 
plexus;  iS^.;?.,  pectoral  fin;  V.s.i.,  sub-intestinal  vein ;  I.p.,  pos- 
terior intestine  ;  V.ii.,  urinary  bladder  ;  V.c,  caudal  vein  ;  A.,  aorta  ; 
Ch.,  notochord.  The  arrows  indicate  the  direction  of  the  blood- 
current.     The  pigmentation  is  not  indicated. 


the  beginnings  of  tiie  circulation  and  of  the  vitelline  circulation  in  par- 
ticular in  Gasterosifi2is  f/i/mnur us,  vf'ith  comparison  with  other  Teleosteans. 
The  primitive  pathway  of  the  blood  returning  to  the  heart  from  the 
aorta  is  a  simple  large  venous  vessel,  fed  by  caudal,  anal,  and  sub-intes- 
tinal veins,  which  runs  to  the  left  on  the  vitellus.  There  is  a  complete 
circuit  before  there  is  a  vascular  vitelline  network.  The  first  vitelline 
circulation  in  the  stickleback  is  entirely  venous.     But  when  the  vitelline 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  303 

network  is  established,  the  vitelline  circulation  becomes  partially  arterial, 
in  virtue  of  the  development  of  the  mesenteric  artery  and  its  vitelline 
branches.  There  is  a  marked  asymmetry  in  the  vitelline  circulation  ; 
bilateral  symmetry  is  not  established  until  the  absorption  of  the  yolk  is 
completed.  The  primary  circulation  in  the  stickleback  is  very  like  the 
primitive  circulation  of  Amphioxus,  though  the  stickleback  is  far  from 
being  archaic.  J.  A.  T. 

Development  of  Shoulder-Girdle  of  Pig. — F.  B.  Hanson  {Anat. 
Record,  1920,  18,  1-21,  28  figs.).  There  is  a  permanent  supra-scapula, 
in  which  no  centres  of  ossification  appear.  In  the  entire  shoulder- 
girdle  there  are  only  two  ossific  centres  :  one  for  the  scapular  l^lade  and 
one  for  the  subcoracoid.  Coracoid  process,  acromion,  and  clavicle  are 
aborted.     The  pig's  scapula  is  at  once  primitive  and  degenerate. 

J.  A.  T. 

Eye-colour  in  Birds.— C.  J.  Bond  {Journ.  Genetics,  1919,  9, 
69-81).  An  analysis  of  certain  factors  concerned  in  the  production  of 
eye-colour  in  birds.  The  "  bull  "  eye  owes  its  black  or  dark  colour  to 
the  absence  of  pigment  on  the  anterior  surface  of  the  iris.  The  delicacy 
and  translucency  of  the  iris  tissues  allow  the  posterior  uveal  pigment  to 
shine  through,  and  this  gives  an  appearance  of  blackness.  Another  type 
is  the  "  pearl "  eye,  where  anterior  iris  pigment  is  absent,  but  the  iris 
tissues  are  not  translucent  as  in  the  "bull"  eye.  They  are  crowded 
with  granules  which  are  themselves  colourless,  but  prevent  the  passage 
of  transmitted  light,  and  when  seen  by  reflected  light  give  a  grey-white 
appearance  to  the  surface  of  the  iris.  Another  type  is  the  "  yellow  "  or 
"  gravel "  eye,  due  in  the  pigeon  to  a  network  of  branching  cells 
crowded  with  small  spherical  yellow  granules.  These  cells  lie  on  the 
anterior  surface  of  the  iris  ;  tiiey  cover  the  capillary  Ijlood  vessels  and 
surround  the  striated  muscle  fibres  of  the  iris,  which  in  the  pigeon  are 
themselves  free  from  pigment.  Amongst  birds,  as  amongst  mammals, 
quite  a  large  number  of  species  possess  anterior  iris  pigment  which 
passes  through  all  grades  of  brown  up  to  black.  AYith  some  exceptions, 
notably  the  Silky  Fowl,  the  black  iris  is  associated  with  black  feather 
colour,  and  in  its  deeper  grades  with  black-leg  colour.  Histologically 
the  brown  (in  the  darker  shades)  and  the  black  iris  are  produced  by  a 
•well-defined  layer  of  characteristic  branching  cells,  which  contain  dark 
brown  or  black  pigment,  on  the  anterior  surface  of  the  iris.  These  cells 
intercommunicate  by  their  l)ranches  and  form  a  plexus  of  pigmented 
cells  thickest  over  the  capillaries  in  the  peripheral  or  middle  zones  of 
the  iris.  The  author  deals  also  with  the  "  black  "  eye  in  fowls,  with 
the  "triplex"  eye,  containing  two  kinds  of  anterior  iris  pigment,  the 
"  ruby  "  eye  (due  to  a  surface  layer  of  branching  cells  with  yellow  pig- 
ment, which  surround  the  capillaries  on  the  anterior  surface  of  the  iris), 
and  the  "parti-  or  zone-"  coloured  iris.  He  contributes  notes  on  the 
genetics  of  the  various  factors.  Some  special  cases  of  coloration  are 
analyzed.  Thus  in  Lawes'  Bird  of  Paradise  a  brilliant  colour  effect  is 
produced  by  the  combination  of  three  factors  :  (1)  thinness  and  trans- 
lucency of  the  iris  tissue,  allowing  the  uveal  pigment  to  shine  through  ; 


304  SUMMARY    OF    CUKRENT    RESEARCHES    RELATING    TO 

(2)  the  absence  of  anterior  yellow  pigment  cells  in  the  inner  zone  ;.  and 

(3)  a  peculiar  physical  conformation  of  the  connective  tissue  cells  in  this 
area.  A  parallel  fibrillation  of  cells  acts  as  a  diffusion  grating  and 
causes  light  to  be  reflected  from  the  anterior  surface  of  the  iris  at  a 
certain  ansrle  as  blue  in  colour.  J.  A.  T. 


Transplanting  Cerebral  Hemispheres  of  Amblystoma  Larvse. — 
H.  Saxton  Burr  {Jouni.  Exper.  Zool,  1920,  30,  159-69,  9  figs.).  The 
cerebral  hemisphere  and  nasal  placode  were  transplanted  to  other  places, 
especially  the  region  just  posterior  to  the  right  limb.  In  every  case  the 
transplants  showed  a  healthy  development.  The  successful  results  of 
the  transplantation  of  the  cerebral  hemispheres  show  that  the  factor 
which  stimulates  the  growth  phase  of  nervous  development  is  not  the 
functional  activity  of  the  end  organ,  but  the  ingrowth  of  peripheral 
neurones.  In  the  transplanted  hemisphere,  the  central  grey  matter  is 
restricted,  particularly  in  the  regions  of  the  nucleus  medianus  septi  and 
in  the  primordium  hippocampi.  The  absence  of  ascending  fibres 
reduces  the  size  of  the  lateral  forebrain  tract  and  practically  prevents  the 
formation  of  the  columna  f ornicis  and  the  fimbria  complex.  A  vascular 
pia  mater  is  formed  about  the  transplanted  hemisphere,  and  a  choroid 
plexus  may  be  formed  from  properly  placed  blood  vessels.  J.  A.  T. 

Regulation  in  Anuran  Embryos  with  Spina  Bifida  Defect. — 
H.  V.  Wilson  and  Blackwell  Markham  {Journ.  Exper.  Zoo!.,  192o, 
30,  171-88,  5  figs.).  In  fishes  and  amphibians  it  frecpiently  happens 
that  something  interferes  with  the  normal  movement  of  the  blastopore 
lip  over  the  yolk.  In  these  cases  the  anterior  end  of  the  axial  body 
develops  in  front  of  the  blastopore  lip  and  is  continuous  behind  with 
the  two  halves  of  the  latter.  The  authors  studied  embryos  of  Bufo 
and  Chorophilus  in  which  blastopore  closure  was  inhibited,  and  they 
observed  an  interesting  regulatory  process.  Instead  of  the  two  lateral 
blastopore  lips  fusing  in  the  midline,  the  blastopore  is  shifted  over 
toward  one  side,  and  from  a  single  lip  a  backward  extension  of  the 
axial  organs  is  produced.  Such  a  tadpole  was  reared  to  a  stage  in  which 
external  gills  had  been  absorbed,  and  internal  gills  and  opercular  cavity 
formed.  J.  A.  T. 

Effect  of  Starving  Young  Rats.— C.  ]\I.  Jackson  and  V.  A. 
Stewart  {Journ.  Exper.  Zool,  1920,  30,  97-127,  5  charts).  Albino 
rats  fully  re-fed  after  underfeeding  from  birth  to  three,  six  or  ten 
weeks,  or  from  three  weeks  to  nearly  a  year  of  age,  grow  variably,  but 
usually  fail  to  reach  the  normal  adult  size.  The  ultimate  effect  varies 
according  to  the  length  of  the  underfeeding  period,  the  age  at  which 
inanition  occurred,  the  sex  (body  weight  more  affected  in  males),  the 
severity  and  th(;  cliaracter  of  the  inanition.  The  effects  on  particular 
systems  and  individual  organs  are  noted.  Thus  the  ovaries  are  markedly 
under  weight,  which  probably  accounts  for  the  reduction  of  reproduc- 
tive capacity  marked  after  long  underfeeding.  But  the  abnormalities  of 
weight  are  usually  slight,  and  in  general  it  may  be  said  that  the  organs 


ZOOLOGY    AND   BOTANY,    MICROSCOPY,    ETC.  305 

and  parts  are  almost  normally  proportioned  in  the  permanently  stunted 
rats.  Thus  the  early  starvation  apparently  retards  or  inhibits  the  later 
growth  process  of  the  body  as  a  whole,  with  a  few  exceptions.      J.  A.  T. 

Results  of  Early  Removal  of  Thymus  Glands  in  Tadpoles. — 
Bennet  M.  Allen  {Jonrn.  Exper.  ZooL,  1920,  30,  189-200,  1  fig.). 
Experiments  with  Ranapipiens  show^ed  that  the  thymus  glands  from  their 
very  inception  exert  no  influence  upon  growth  or  upon  the  progress 
of  metamorphosis.  They  are  not  at  any  stage  indispensable  to  life, 
nor  does  their  removal  cause  any  marked  deficiency  in  the  general 
metabolism  of  the  body.  Their  extirpation  does  not  affect  the  gonads, 
nor  the  thyroid  glands,  nor  any  internal  feature.  J.  A.  T. 

Parathyroid  Glands  of  Thyroidless  Toad  Larvae. — Bennet 
Allen  {Journ.  Exper.  ZooL,  1920,  30,  201-10).  Removal  of  the 
thyroid  glands  of  Bi/fo  causes  a  very  marked  hypertrophy  of  the  para- 
thyroid glands,  so  that  they  grow  to  many  times  the  normal  volume. 
There  is  not  in  these  parathyroids  any  deposition  of  colloid  or  evidence 
of  the  assumption  of  a  vicarious  relationship.  There  are  no  noticeable 
histological  peculiarities  in  these  hypertrophied  parathyroids.     J.  A.  T. 

Breeding  of  Dog-Perch. — Jacob  PtEiGHARD  (Report  Michigan  Acad. 
Sci.,  1913,  15,  10-1-5).  In  this  fish  the  female  is  pursued  by  several 
males,  and  after  a  tortuous  course  settles  to  the  bottom.  A  male  takes 
position  over  her  with  his  pelvic  fins  clasping  her  head  and  his  tail  at 
the  side  of  hers.  Rapid  vibration  of  the  tail  and  fins  (pectoral  and 
pelvic)  of  both  sexes  excavates  a  little  pit  in  the  sand.  The  eggs  are 
emitted,  fertilized  and  buried.  Each  egg  is  weighted  by  a  coating  of 
adhering  sand-grains.  Supernumerary  males  crowding  round  attempt  to 
supplant  the  pairing  male.  After  spawning  is  finished  at  a  pit  the 
female  at  least  leaves  the  eggs.  She  repeats  the  process  at  many  pits.* 
The  supernumerary  males  (and  perhaps  the  pairing  male)  devour  such 
eggs  as  they  can  get.  There  is  no  parental  care.  There  is  colour 
dimorphism  between  the  sexes,  but  this  is  not  the  basis  of  discrimination. 
If  a  male,  substituted  experimentally  for  a  female,  moves  rapidly  and 
then  stops  on  the  bottom,  it  is  treated  by  other  males  as  a  female. 

J.  A.  T. 

Factors  in  Variation. — Heber  A.  Longman  (Proc.  R.  Soc. 
Queensland,  1920,  32,  1-18).  Against  the  view  that  evolution  is  an 
unpacking  of  an  original  complex  the  author  emphasizes  the  real 
newness  of  the  pouch  of  marsupials,  the  patagium  of  parachuting 
mammals,  the  venom  fangs  of  snakes,  the  pharyngeal  teeth  of  fishes, 
and  the  copulatory  apparatus  of  the  male  dragon-fly.  He  suggests  that 
the  evolution  of  environments  w^ould  provide  stimuli  which  might  have 
cumulative  effects  in  many  generations.  He  lays  emphasis  on  the 
importance  of  environmental  change  in  inducing  mutations.  The 
general  aim  of  the  paper  is  to  suggest  a  reconsideration  of  Lamarckism. 

J.  A.  T. 

The  Method  of  Evolution.— E.  W.  MacBride  (Scientia,  1920,  14, 
23-33.)     By  the  "  force  of  heredity  "  is  meant  the  tendency  of  the 

X 


306  SUMMARY    OF   CUERENT    RESEARCHES    RELATING   TO 

offspring  to  resemble  the  parent.  It  is  obvious  that  in  some  wav  this 
force  must  be  modified  as  time  progresses,  otherwise  evolution  could  not 
take  place,  and  the  manner  and  means  of  this  modification  is  just  what 
we  mean  by  the  phrase  "method  of  evolution."  Darwin  and  Wallace 
assumed  that  small  variations  are  heritable,  and  farther  that  the  force 
which  produced  a  deviation  of  heredity  would  continue  to  act  in  the 
same  direction  in  succeeding  generations.  "  Pure  line  "  investigations 
are  against  the  theory  that  progressive  results  can  l)e  attained  by  selec- 
tion of  these  small  quantitative  variations.  Thus  emphasis  has  been 
laid  on  the  importance  of  sports  or  mutants.  But  mutations  tend  to  be 
of  the  nature  of  "  cripples  " — deviations  from  the  normal  which  are 
notoriously  unlike  the  differentiating  characters  which  distinguish  allied 
species  from  one  another.  If  we  have  to  reject  small  individual  differ- 
ences and  larger  occasional  mutations  as  the  raw  material  of  evolution, 
there  remains  only  a  third  alternative— that  evolutionary  change  is  due 
to  the  inheritance  of  the  effects  of  use  and  disuse.  If  it  be  said  that 
the  experimental  evidence  is  against  this  alternative,  there  is  the  work 
of  Kammerer,  which  MacBride  finds  convincing,  and  there  is  transmission 
of  acquired  characters  in  bacteria  (where,  however,  there  is  no  "  body  " 
in  the  strict  sense).  But  according  to  MacBride  tbe  distinction  between 
somatoplasm  and  germ-plasm  is  a  "Weismaunian  nightmare."  The 
inheritance  of  the  effects  of  use  and  disuse  is  the  method  of  evolution, 
"the  dominating  influence  which  has  moulded  the  animal  world  from 
simple  beginnings  into  the  great  fabric  of  varied  life  which  we  see 
around  us."  J.  A.  T. 

Mutational  and  "  Recapitulatory "  Characters.  —  R.  Ruggles 
Gates  {Rep.  Brit.  Assoc,  1919,  87,  H40).  A  mutation  is  due  to  a 
chemical  or  ^)hysical  change  in  a  chromosome  of  a  germ-cell,  and  is 
continued  through  the  ontogeny  by  the  equal  splitting  of  the  chromo- 
somes in  mitosis.  A^'hat  are  called,  not  very  happily,  "  recapitulatory  " 
characters  "  ari^e  througli  the  impress  of  the  environment,  usually  involve 
adaptation  to  new  conditions,  are  gradually  developed,  and  in  becoming 
permanent  involve  the  principal  of  inheritance  of  acquired  characters. 
In  the  lengthening  out  of  a  life-cycle  by  the  addition  of  adaptive  lai-val 
stages  there  are  good  instances  of  recapitulatory  characters.  Such 
characters  could  not  have  arisen  through  a  mutation,  for  that  would 
modify  every  stage  instead  of  adding  certain  stages  as  it  does.  Thus 
both  mutational  and  recapitulatory  characters  are  necessary  for  the 
phenomena  of  evolution.  The  one  is  nuclear  in  origin  and  centrifugal 
in  effect  ;  the  other  extrinsic  in  origin  and  ultimately  centripetal  in  its 
effect  in  the  organism."  (But  the  transmission  of  an  exogenous  somatic 
modification  as  such  or  in  any  representative  degree  has  not  vet  been 
proved.)  J.  A.  T. 

h.  Histologry. 

Blood  Platelets  in  Mammals. — A.  Cesahis-Demel  {Atii.  Soc. 
Toscaiia  Sci.  N((t.,  1915,  30,  lUO-lU,  2  pis.).  Blood  platelets  are  due 
to  megakaryocytes  in  the  s})leen  which  peiutrate  into  the  veins.  They 
may  also  arise  from  megakaryocytes  in  the  marrow.     The  megakaryocytes 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  307 

seen  in  pulmonary  embolism  are  also  in  the  main  of  splenic  origin,  but 
may  also  come  from  the  marrow.  Besides  free  platelets  and  aggregated 
platelets  there  are  other  elements  in  the  spleen,  approaching  the  platelet 
type,  and  from  these  platelets  may  perhaps  arise  as  well  as  from  the 
megakaryocytes.  J.  A.  T. 

Eosinophilic  Leucocytes  in  Thymus  of  Postnatal  Pigs. — J.  A. 
Badertscher  (Anaf.  Record,  1920,  18,  23-34).  Granular  eosinophilic 
leucocytes  are  formed  in  the  thymus  of  the  postnatal  pig.  It  follows 
that  the  bone-marrow  is  not  the  only  source  of  the  granular  leucocytes 
found  in  the  blood.  The  fact  bespeaks  for  the  thymus  a  function  with 
which  it  has  not  been  generally  credited.  It  is  indicated  that  the 
lymphocytes  (especially  the  large  lympliocytes)  in  the  thymus  have,  to 
a  limited  extent  at  least,  the  potentiality  of  the  premyelocytes 
(myeloblast,  h?emoblast,  primitive  blood-cell,  "  lymphocyte ")  in  the 
bone-marrow  in  so  far  that  they  are  capable  of  developing  into  some  or 
all  (perhaps  variable  in  different  mammalian  species)  of  the  types  of  the 
granular  leucocytes  found  in  the  blood.  J.  A.  T. 

Theory  of  Symbions  in  all  Cells. — Auguste  Lumiere  (Le  Mythe 
des  SymMotes,  1919,  Paris,  xi  +  209,  50  figs.).  Criticism  of  Portier's 
heresy  that  all  the  elements  of  Protozoa  and  Metazoa,  and  indeed 
practically  all  organisms  except  bacteria,  contain  symbiotic  microbes  by 
aid  of  which  synthetic  metabolic  process  is  made  possible.  It  is 
admitted  that  the  normal  tissues  of  vertebrates  often  contain  quiescent 
saprophytic  micro-organisms,  and  these  have  supplied  in  part  a  basis 
for  Portier's  extraordinary  theory  of  symbions  ;  but  the  microbes  in 
question  have  not  the  qualities  of  Portier's  "  symbiotes."  Mitochondria 
have  also  been  mistaken  for  microbes,  while  they  are  only  formed 
colloid  aggregates  in  the  cytoplasm.  To  suppose  that  vitamines  are 
carried  by  special  symbions  is  quite  gratuitous.  J.  A.  T. 

Blood-coloured  Muscle  in  Fish.— IVzuRU  Okuda  (Journ.  Colleye 
of  Agric.  Imp.  Univ.  Tokyo,  1919,  7,  1-28,  1  fig.).  In  Katsuuwnus 
pekmiis  and  Auxis  tapeinosoma  the  blood-coloured  flesh  in  the  lateral 
muscle  (common  to  many  fishes)  contains  more  ether  extract  and  less 
carbohydrates,  soluble  matter,  creatine  and  nitrogenous  matters.  It  is 
superior  to  the  ordinary  flesh  in  respect  of  its  contents  of  phosphorus  in 
lipoid  form,  but  inferior  in  its  content  of  phosphorus  in  inosinic  acid 
form.  Each  kind  has  about  the  same  quantity  of  protein-sulphur  and 
volatile  sulphur,  but  the  red  flesh  has  more  taurine.  It  also  has  more 
lecithin,  haemoglobin,  and  hypoxanthin.     Other  differences  are  noted. 

J.  A.  T. 

Cells  of  Tadpole's  Tail.— W.  J.  Schmidt  (Zool.  Anzeiger,  1920,  51, 
49-63,  7  figs.).  A  description  of  (1)  the  ordinary  pigmented  epidermic 
cells  in  the  outer  epithelial  layer,  (2)  the  bi-nucleate  strongly  pigmented 
giant  cells  of  the  same  layer,  (3)  the  occasional  ciliated  cells,  (4)  the 
pigmented  wandering  cells  which  are  usually  found  in  the  epithelium 
but  sometimes  in  the  cutis,  and  (5)  the  stellate  melanophores^of   the 

X  2 


308  SUMMARY    OF   CURRENT   RESEARCHES    RELATING   TO 

cutis.  Four  kinds  of  movement  may  be  distinguished  in  these  cells  : — 
Ciliary  movement,  the  amoeboid  movement  of  wandering  cells,  the 
irregular  and  regular|i,streaming  of  granules — the  former  in  the  outer 
layer  of  epithelium  and  the  latter  in  the  melanospores  of  the  cutis.  The 
author  poiuts  out  that  the  tadpole's  tail  is  admirably  suited  for 
demonstration  purposes.  J.  A.  T. 

c.  General. 

Variation  in  Deer-mice. — F.  B.  Sumner  (Amer.  Naturalist,  1918, 
177-208,  290-301,  439-54,  13  figs.).  A  study  of  the  structural  and 
pigmentary  differences  distinguishing  four  geographical  races  of  Fero- 
myscus  manicidatus.  The  pigmentary  differences,  show  a  general 
correlation  with  enviromental  features  ;  the  structural  differences  do 
not.  All  the  differences  are  differences  of  degree,  revealed  through  a 
comparison  of  mean  or  modal  conditions  rather  than  of  individuals. 
These  subspecific  differences  are  hereditary.  They  persist  when 
environmental  conditions  are  interchanged.  Hybrids  between  even  the 
most  divergent  of  the  four  races  are  predominantly  intermediate  in 
character,  both  in  the  F^^  and  the  Fg  generations.  In  contrast  to  the 
sensibly  continuous  variation  and  sensibly  blended  inheritance  shown  in 
respect  to  these  subspecific  characters  is  the  behaviour  of  certain 
"mutations."  Here  are  seen  typical  illustrations  of  discontinuous 
variation  and  inheritance  of  the  strictly  alternative  or  Mendelian  type. 
There  are  two  types  of  variation  and  inheritance.  J.  A.  T. 

Androgenic  Origin  of  Horns  and  Antlers.— J.  F.  van  Bemmelen 
{Proc.  K.  Akad.  Wiss.  Amsterdam,  1918,  21,  570-5).  According  to 
Weber  and  others,  horns  and  antlers  were  originally  common  to  both 
sexes  and  were  defensive  weapons  against  enemies.  Later  on  they 
came  to  be  used  more  and  more  in  the  contests  of  rival  males,  and  have 
become  exclusively  masculine  features,  or  at  least  more  strongly  developed 
in  the  males.  This  is  in  agreement  with  the  view  of  Tandler  and  Gross 
that  all  secondary  sex  features  were  originally  specific  characters.  To 
van  Bemmelen  the  opposite  view  seems  more  justifiable  that  the  head 
armature  arose  in  males  as  a  means  of  attack  in  their  duels  for  the 
females,  and  afterwards  passed  to  the  females.  Among  his  arguments 
are  the  following  : — In  deer  the  antlers  are  absent  in  all  females  except 
the  reindeer,  where  there  may  be  a  non-sexual  function ;  in  those  antelopes 
that  have  horns  in  the  female  sex  as  well  as  in  the  male,  the  horns  of 
the  females  are  usually  smaller,  and  those  of  the  males  show  a  tendency 
to  hypertrophic  and  exaggerated  growth  not  consistent  with  the  require- 
ments of  practical  use ;  similar  exaggerations,  e.g.  the  four-horned 
goat,  are  known  in  cattle,  sheep  and  goats;  in  giraffes  with  small 
pedicle  and  small  os  cornu,  the  males  have  higher  and  stronger  horn- 
stumps  than  the  females,  and  they  have  the  unpaired  nasal  knob  ; 
in  the  Okapi  the  horns  are  primarily  absent  in  the  female  ;  the  annual 
shedding  of  the  antlers  and  their  regrowth  in  Cervini\3  are  apparently 
connected  with  rut ;  the  same  appears  to  be  the  case  in  Antilocapra ;  the 
bony  processes  on  the  head  of  giraffes,  Suidas,  and  extinct  forms  cannot 
reasonably  be  regarded  as  practical  weapons,  they  are  far  too  cumbrous 


ZOOLOGY    AND   BOTANY,    MICROSCOPY,   ETC.  309 

and  hypertrophic  for  that;  neither  can  this  be  the  case  with  the 
antlers  of  most  deer  or  the  horns  of  numerous  antelopes,  cattle,  sheep, 
and  goats ;  on  the  other  hand  the  structures  in  question  wear  to  a  very 
high  degree  the  character  of  sex-features,  "in  their  exuberance^ 
unpractical  build,  curious  complication,  obviousness  and  variability." 
But  the  author  cannot  agree  with  Bolsche  that  the  growths  on  the  roof 
of  the  skull  are  purely  ornamental  exuberances  of  growth,  and  connected 
with  a  regression  of  the  ensiform  tusks  of  the  male.  J.  A.  T. 

Mandible  of  Birds. — N.  G.  Lebedinsky  (Revue  Suisse  Zool,  1918, 
26,  129-46,  6  tigs,).  A  discussion  of  a  number  of  points — the  paired 
primordia  of  the  dentary  in  nine  orders  (as  in  other  vertebrates),  the 
proportions  of  the  various  regions  in  the  lower  jaw,  the  reduction  of 
the  pars  anterior  in  parrots  and  some  other  types,  and  the  relation  of 
particular  features  to  the  conditions  of  life.  J.  A.  T. 

Increasing  Number  of  Ostrich  Plumes. — J.  E.  Duerden  {Bull. 
Defpt.  Agric.  Pretoria,  1918,  No.  7,  1-39,  12  figs.).  The  first-row 
feathers  on  each  wing  vary  from  33  to  39,  the  mean  being  36*54.  The 
ostriches  of  the  whole  of  Africa  seem  to  produce  the  same  average 
number  of  plumes.  During  fifty  years  of  ostrich  farming  no  advance 
in  the  number  has  been  made.  The  breeding  has  been  for  quality,  not 
"quantity.  Of  late  two  42-plumed  birds  have  occurred.  One  of  these 
survived  and  bred  true.  On  the  whole  the  wings  of  the  ostrich  have 
undergone  degeneration  as  regards  number  of  feathers.  The  third 
finger  (which  has  no  claw  as  is  sometimes  alleged)  is  almost  buried  in 
the  flesh.  The  42-plumed  wing  is  regarded  as  a  survivor  of  an  ancestral 
condition.  It  appears  that  the  factors  for  quantity  do  not  interfere 
with  those  for  quality.  From  the  42-plumed  strain  it  may  be  possible 
to  raise  a  stock  giving  the  same  quantity  of  feathers  from  three-quarters 
of  the  number.  J.  A.  T. 

Phylogeny  of  Jaw  Muscles  in  Vertebrata. — L.  A.  Adams  {Ann. 
New  York  Acad.  Sci,,  1919,  28,  51-166,  13  pis.).  The  two  chief 
muscle  masses  of  the  jaw — {a)  the  adductor  mass  innervated  by  the  ramus 
mandibularis  of  the  fifth  nerve,  and  {h)  the  depressor  or  digastric  mass 
innervated  by  the  facial — are  homologous  throughout  the  Vertebrata. 
The  adductor  of  the  fish  type  is  the  mother  mass  from  which  the  muscles 
of  mastication  are  derived  throughout  the  vertebrates,  by  the  separation 
of  slips  of  this  muscle  and  by  their  gradual  complete  separation  in  nerve 
supply  through  the  growth  of  the  originally  small  twigs  into  separate 
nerve  branches.  In  a  very  interesting  way  the  author  traces  the  evolu- 
tion of  new  slips,  such  as  the  so-called  pterygoid  muscles,  and  brings 
them  into  correlation  with  the  changes  in  the  skull,  e.g.  in  the  temporal 
fenestra  and  the  quadrate.  J.  A.  T. 

Comparative  Study  of  Pelvic  Muscles. — S.  Nishi  {Arbeit.  Anat.  Inst. 
Japan,  Univ.  Sendai,  1919,  3,  1-72,  21  figs.).  A  study  of  the  differen- 
tiation of  muscles  in  the  region  of  the  exitus  pelvis.  Beginning  with 
the  early  differentiation  in  the  pelvic  region  of  fishes,  the  author  traces 
the  differentiation  of  M.  subvertebralis  pelvus,  M.  obliquus  pelvis,  M. 


310  SUMMAEY    OF    CURRENT   RESEARCHES   RELATING   TO 

rectus  pelvis,  which  are  all  represented  in  Selachians,  and  those  muscles 
of  the  exitus  which  owe  their  origin  to  the  musculature  of  the  hind 
limbs.     The  smooth  musculature  is  also  dealt  with.  J.  A.  T. 

Mating  in  Frog-s.— Harold  CmnimQ^  {Joiini.  Exper.  ZooL,  1920, 
30,  825-43).  Migration  of  frogs  (of  four  species)  into  a  pond  at  the 
breeding  time  occurs  in  waves,  during  periods  of  high  relative  humidity 
coincident  with  temperature  ranging  between  about  41°  and  52''  Fahr. 
Voice  does  not  direct  the  movements  of  frogs  into  the  pond  ;  sight  is 
not  essential  for  correct  coupling  and  seems  unimportant  in  sex  recog- 
nition. Sex  "recognition"  in  clasping  results  from  the  differential 
behaviour  of  the  two  sexes  when  clasped,  and  depends  on  the  reaction  of 
the  clasping  male  to  this  differential  behaviour.  Clasped  normal  males 
struggle,  inflate  the  vocal  sacs  and  croak,  and  are  always  released. 

J.  A.  T. 

Diemyctylus  viridescens  with  Bifurcated  Tail.— Bertram:  G. 
Smith  (Report  Michigan  Acad.  Sci.,  1918,  15,  105,  1  fig.).  A  specimen 
with  the  tail  forked  in  a  vertical  plane,  each  ramus  of  the  forked  portion 
having  a  distinct  vertebral  column  and  spinal  cord.  In  the  ventral 
ramus  the  spinal  cord  is  not  continuous  with  that  of  the  dorsal  ramus, 
but  is  perhaps  connected  with  it  by  nerve  fibres.  In  ordinary  spina 
bifida  the  tail  is  divided  in  a  horizontal  plane.  The  condition  of  the- 
specimen  is  probably  due  to  an  injurv,  followed  by  regeneration. 

J.  A.  T. 

Toxicity  of  Extract  of  Eel.— G.  Buglia  {Atti  Soc.  Tosccma  Sci. 
Nat.,  1919,  32, 165-98,  2  pis.).  Aqueous  extract  of  the  cutis  of  young 
stages  of  Anguilla  has  a  toxic  influence  like  that  of  the  blood  serum. 
The  same  is  true  of  the  fluid  secretion  of  the  skin  in  the  same  juvenile 
stages,  while  the  larva  is  still  transparent.  J.  A.  T. 

Spiracular  Sense-Organ  in  Fishes.— H.  W.  Norris  and  Sally  P. 
Hughes  (Anat.  Record,  1920,  18,  205-9,  1  fig.).  Various  investigators 
have  called  attention  to  a  sense-organ  in  the  spiracular  cleft  of  Elasmo- 
brancbs  and  Ganoids,  which  is  probably  homologous  with  Pinkus'  organ 
in  Dipnoi.  The  structures  are  derivatives  of  the  lateral  line  system 
of  sense-organs.  The  writers  find  on  the  anterior  mesial  wall  of  the 
spiracular  cleft  of  Squalm  acanthias,  both  embryo  and  adult,  a  tubular 
organ  Avhich  bears  one  or  more  sense-organs.  It  is  very  variable  in 
form  and  structure.  In  the  most  differentiated  condition  a  small  pore 
in  the  spiracular  wall  leads  into  a  sac-like  expansion  with  which  are  con- 
nected three  diverticula,  two  short  and  cup-like  and  the  third  much 
elongate.  The  entire  organ  with  its  three  diverticula  evidently  re}>resents 
a  much  modified  ampulla  of  Lorenzini.  Its  occurrence  in  Mustelus  is 
noted.  In  Raia  radiata  a  diverticular  sense-organ  opens  not  into  the 
spiracle,  but  on  the  roof  of  the  pharynx  at  the  anterior  border  of  the 
inner  pharyngeal  opening  of  tlie  hyomandil)nlar  cleft.  J.  A.  T. 

Fish  Food  in  the  Limfjord.— P.  Boyhen  Jensen  {Rep.  Danish 
Biol  Station,  1920,  26,  1-44,  4  charts).     The  stock  of  bottom  animals, 


ZOOLOGY    AND    BOTANY,    MICKOSCOl^Y,    ETC.  811 

serving  as  food  for  plaice  and  eels,  varies  greatly  from  year  to  year,  both 
qnantitatively  and  qualitatively.  The  bottom  animals  are  often  eaten 
up  within  the  year  ;  the  brood  is  in  many  cases  far  from  ready  to  replace 
what  is  devoured;  diiferent  species  breed  in  different  years.  In  Ahra 
the  breeding  is  about  every  second  year,  in  Solen  less  frequently,  in 
My  a  triincata  only  at  intervals  of  many  years.  The  magnitude  of 
annual  consumption  in  Thisted  Bredning  has  varied  between  ,31 '8  and 
84 '8  gr.  gross  vreight  per  square  metre.  The  magnitude  of  the  annual 
production  varied  (1910-1915)  between  42-1  and  77*1  gr.  gross  weight 
per  square  metre.  In  Corhala,  Mya  trmuata^  and  other  bottom  forms 
it  looks  as  if  the  growth  continued  throughout  life.  The  general  result 
of  the  valuation  studies  is  to  show  that  an  unlimited  supply  of  fish  food 
is  not  available,  and  that  transplantation  of  fry  is  profitable  only 
between  certain  limits,  which  in  some  cases  have  been  alreadv  surpassed. 

"  J.  A.  T. 

Quantitative  Estimate  of  Littoral  Animals. — AV.  A.  Herdman 
[Jouni.  Liiiii.  Sac.  ZooJ.,  1920,  34,  247-59,  8  figs.).  The  gregarious 
Polych^et  Sahellaria  alveolata  may  show  65  to  75  tubes  on  a  surface  of 
about  3  square  inches.  Taking  05,  a  square  foot  would  have  3,120,  a 
square  yard  some  28,080.  In  many  localities  there  are  very  many  square 
yards  of  SaheUaria,  therefore  many  millions  ;  and  these  Polych^ets  form 
a  favourite  food  of  fishes  like  plaice  and  sole.  A  quarter  of  an  inch 
square  is  an  average  size  for  an  adult  of  Balanus  halanoides,  and  on  one 
square  foot  of  rock  near  Port  Erin  2,940  l^arnacles  were  counted.  These 
rock-barnacles  are  eaten  by  various  animals,  and  their  larvae  form  in 
March  and  April  an  important  part  of  the  plankton.  From  80  to  100 
young  mussels  may  be  counted  on  a  square  inch,  which  means  about 
129,600  on  a  square  yard,  and  there  are  very  many  such  square  yards 
around  our  coast.  "  Xo  doubt  the  majority  of  these  young  mussels 
never  grow  to  maturity.  They  are  killed  by  storms,  smothered  by  their 
neighbours,  or  eaten  by  starfishes  or  by  plaice  and  other  fishes.  In  the 
latter  case  they  are  not  lost  as  a  food  matter,  and  even  in  the  former 
their  remains  will  be  eaten  by  something  which  will  indirectly  feed  man. 
Nothing  is  lost  in  the  sea,  and  everything  ultimately  in  the  metabolic 
cycle  contributes  to  man's  harvest."  Of  the  small  red  Ascidian  StyeJopsis 
grossiUaria  there  may  be  10  to  30  to  the  square  inch,  over  50,000  to 
the  square  yard.     Many  other  interesting  records  are  given.     J.  A.  T. 

Fauna  of  a  Moor.—  Adolf  H^eberli  {Rev.  Suisse  Zool.,  1918,  26, 
147-231,  18  figs.).  An  interesting  account  of  the  fauna  of  a  moor  near 
Bern.  The  list  shows  8  Flagellates  (the  commonest  being  Fhacus 
longkaudatus  and  Peridinium  tabidatum),  4  species  of  Ammba  and 
Pelomyxa  linudeata,  30  Testacea,  5  Heliozoa,  28  CiUata,  Hydra  viri- 
dissima,  6  Turbellarians,  3  Nematodes,  5  Oligocb^ets,  42  Rotifers, 
6  Gastrotricha,  the  leech  Helohdella  staynalis,  2  Ostracods,  15  Copepods, 
11  Cladocera,  the  Tardigrade  Macrohiotus  macronyx,  9  Hydracarina,  the 
bivalve  Fisidium  fossarium,  the  Gastropods  Lymnsea  peregra  and 
PlcmorUs  nitidus,  and  various  insect  larvae  such  as  Coretha  'plumicornis. 
On  many  of  the  components  of  this  characteristic  fauna  the  author  has 
interesting;  notes  to  make.  'I.  A.  T. 


312  SUMMAKY    OF    CURRENT    RESEARCHES    RELATING   TO 

Tunicata. 

'Tadpole  Larva  of  Amaroucium. — Caswell  Grave  {Journ.  Exper, 
ZooL,  11)20,  30,  239-57,  4  figs.).  A  study  of  the  activities  and 
reactions  of  the  larva  of  A.  2)ellucidutn  (Leidj)  form  constellat if m  Verrill. 
The  body  is  in  constant  clockwise  rotation  on  its  long  axis  as  it  is 
propelled  through  the  water  by  the  tail.  The  rotation  is  due  either  to 
the  asymmetrical  form  of  the  body,  or  to  a  torsion  of  the  tail  during  its 
strokes,  or  to  both.  Immediately  after  liberation  they  react  positively 
t>o  light ;  during  the  later  and  greater  part  of  their  free-swimming  life 
they  react  negatively.  At  first  they  remain  at  or  near  the  surface  ;  later 
at  or  near  the  bottom.  There  may  be  a  changing  response  to  gravity  ; 
but  the  response  to  gravity  is  aided  by  the  presence  of  directive  rays  of 
Ught.  The  viscid  contents  of  the  glandular  ends  of  the  adhesive 
papillae  are  extruded  on  the  outer  surface  of  the  tunic  toward  the  close 
of  the  free-swimming  period,  and  the  initial  attachment  of  the  tadpole 
is  due  to  one  of  these  droplets  coming  accidentally  into  contact  with  the 
surface  of  a  foreign  body.  The  free-swimming  period  lasts  from  ten 
minutes  to  two  hours.  J.  A.  T. 

INVERTEBRATA. 

MoUusca. 
a.   Cephalopoda. 

Histolog'y  of  "  Branchial  Hearts "  of  Sepia.  —  E.  Fernandez 
Galiano  (Boll.  Soc.  Espan.  Hist.  Nat.,  1919,  19,  853-Sl,  1  pi.,  10  figs.). 
These  enigmatical  organs,  situated  at  the  base  of  the  gills,  are  very 
vascular  and  likewise  glandular.  An  account  is  given  of  their  external 
epithelium  (showing  many  intercellular  bridges),  their  muscle  fibres,  and 
connective  tissue  network.  The  appendix  to  the  so-called  "  l)ranchial 
heart"  is  also  described.  The  cortical  part  comprises  an  epithelium, 
a  connective  stroma,  blood  vessels,  muscle-fibres  and  free  cells.  The 
author  inclines  to  regard  the  branchial  hearts  and  their  appendices  as  in 
part  pulsatile,  but  mainly  excretory.  J.  A.  T. 

Ammonite  Siphuncle.— A.  E.  Trueman  {Geol.  ALag.,  1920,  57, 
26-32,  2  figs.).  The  siphuncular  tube  or  envelope  (around  the 
membranous  siphuncle  jjroper)  is  not  continuous  in  Anmionites  through 
all  the  chambers  to  the  body  chamber.  In  some  cases  the  envelope  did 
not  extend  through  the  ten  chambers  preceding  the  living  chamber. 
This  is  seen  in  young  as  well  as  in  old  specimens,  though  the  number 
of  chambers  in  wliicli  there  is  no  envelope  apparently  increases  with  the 
age  of  the  individual.  Tlie  autlior  inclines  to  accept  the  suggestion 
of  Foord  and  Woodward  that  the  siphuncle  was  of  more  importance 
in  the  young  animal,  perhaps  then  serving  for  aitachment,  but  that  later 
on  this  function  was  performed  V)y  the  shell  muscles.  It  is  not  unlikely 
also  that  the  siphuncle  was  of  much  greater  importance  in  the  early 
stages  of  Cephalopod  evolution  than  it  is  in  Mesozoic  and  recent  forms. 
The  tendency  for  the  secretion  of  the  sipliuncular  envelope  in  Ammonites 
to  lag  behind  shell-growth  suggests  that  the  vahie  of  the  siphuncle  may 
at  least  have  been  declining:.  J.  A.  T. 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  313 

7.  Gasti'opoda. 

Relationships  of  the  Gastropods. — Louis  Boutan  {Actes  Soc.  Linn. 
Bordeaux,  1911),  71,  1-116,  25  figs.).  There  is  ventral  flexure  in 
Cephalopods  and  Scaphopods,  and  dorsal  flexure  in  Pelecypods,  but 
nothing-  comparable  to  these  in  Gastropods,  where  there  is  a  rotation  of 
the  anal  region  and  of  the  top  of  the  larval  shell.  Gastropods  seem  to 
have  a  monophyletic  origin.  Prosobranchs  and  Opisthobranchs  show  a 
close  j)aralielism  in  their  early  stages  and  larvae.  No  Gastropod  is  twisted 
on  the  longitudinal  axis  of  the  embryo  in  the  cerebro-pedal  region  ;  all 
except  the  Amphineura  are  twisted  on  the  longitudinal  axis  of  the 
embryo  in  the  abdominal  region.  Only  some  are  twisted  on  the  longi- 
tudinal axis  of  the  embryo  both  in  the  abdominal  region  and  in  tlie 
median  region  of  the  body.  Those  Opisthobranchs  which  have  only  a 
feebly  developed  larval  shell  and  have  in  the  adult  state  a  notseum  do 
not  exhibit  the  torsion  strictly  so-called  of  the  Prosobranchs.  Those 
Opisthobranchs  which  have  a  shell  developed  like  that  of  Prosobranchs 
and  a  cephalic  disc  slightly  developed  undergo  true  torsion,  incompletely 
at  first  and  afterwards  completely.  They  may  then  have  an  oesophagus 
twisted  upon  itself  and  a  Streptoneural  nervous  system  as  in  Proso- 
branchs. The  archaic  forms  of  Opisthobranchs  should  be  looked  for 
among  the  Nudibranchs,  some  types  of  which  show  resemblances  with 
Amphineura.  The  resemblances  which  Opisthobranchs  with  a  well- 
developed  adult  shell  present  to  Prosobranchs  seem  to  be  due  to  con- 
vergence, probably  due  to  the  progressive  disappearance  of  the  not^um, 
the  progressive  atrophy  of  the  cephalic  disc,  and  the  formation  of  a  more 
encumbering  shell.  There  is  no  detorsion  in  any  Prosobranch  or 
Opisthobranch.  Those,  like  the  Nudibranchs,  which  are  never  twisted 
in  the  larval  stage  in  the  median  (oesophageal)  region  of  the  body 
undergo  no  detorsion  on  becoming  adults.  Those,  like  some  Tecti- 
branchs,  which  are  sUghtly  twisted  in  the  larval  stage  in  the  median 
region  of  the  body  show  a  slight  torsion  in  the  adult  state.  Those,  like 
Actseon,  which  show  complete  torsion  (torsion  properly  so-called)  in  the 
median  region  of  the  body,  and  become  Streptoneural  in  the  larval  state, 
remain  Streptoneural  in  the  adult  state.  Finally,  the  Prosobranchs, 
which  all  show  torsion  in  the  strict  sense,  retain  this  in  adult  life  in  spite 
of  all  subsequent  regularization  of  the  body.  The  theory  of  detorsion 
has  rested  on  a  confusion  between  strict  torsion  and  the  general  rotation 
of  the  anal  region  and  the  top  of  the  larval  shell.  J.  A.  T. 

Breeding"  and  Habits  of  Periwinkle. — W.  M.  Tattersall  {Sci. 
Investigations  Fisheries,  Ireland,  1920,  1,  1-11,  1  pi).  The  supposed 
eggs  of  Littorina  littorea  figured  in  Bronn's  Tierreich,  and  often  copied, 
are  those  of  L.  ohtusata.  The  eggs  of  L.  littorea,  observed  in  an 
aquarium,  are  pink,  enclosed  in  transparent  capsules  like  a  soldier's  tin 
hat.  The  first  ones  usually  contain  a  single  ^gg,  the  later  ones  two  or 
more.  There  is  no  aggregation  of  capsules.  The  eggs  are  laid  freely 
on  the  shore  and  are  in  part  borne  about  by  the  water.  The  same 
female  may  go  on  depositing  eggs  intermittently  for  a  month  or  more 
(20th  March  to  24th  April),  the  original  act  of  copulation  sufficing  for 
the   whole,   which  is  roughly   estimated   at   5,000.     vSegmentation   is 


314  SUMMARY    OF   CURRENT   RESEARCHES    RELATING    TO 

completed  in  the  first  day,  and  seems  to  be  holoblastic.  Tlie  egg 
hatches  as  an  early  Yeliger  larva,  which  has  a  prolonged  free-swimming 
life,  passing  through  a  late  Veliger  stage  before  the  adult  form  is 
reached.  In  L.  obtusata  the  capsules  are  aggregated  in  masses,  and 
attached  to  weeds ;  the  egg  hatches  as  a  fully-formed  Veliger,  and  the 
free-swimming  period  is  thus  much  abbreviated.  The  chief  food  of 
L.  littorea  appears  to  be  the  hairs  of  Fiirvs  and  allied  seaweeds  ;  Blegvad 
says  it  eats  also  animal  detritus.  The  characteristic  climbing  habit  has 
not  to  do  with  nutrition  ;  it  is  dependent  on  the  calmness  of  the  sea. 

J.  A.  T. 

Breeding  of  Cerions.— Paul  Bartsch  {Dept.  Mar.  Biol.  Carnegie 
Inst.  Washington,  1920, 14,  1-55,  59  pis.).  Numerous  colonies  of  these 
land-snails,  each  with  an  individuality  of  features,  occur  on  the  Bahamas. 
They  are  nocturnal  in  habit,  feeding  on  fungi,  and  though  hermaphrodite 
do  not  reciprocally  fertilize  one  another.  A  number  of  forms  were 
transported  to  the  Florida  Keys,  where  there  is  a  considerable  variety  of 
climate  and  vegetation.  There  is  a  native  species,  Cerion  incanum 
(Binney),  but  it  is  very  remote  from  any  of  the  forms  introduced.  One 
of  the  interesting  results  obtained  was  crossing  between  G.  incanym  and 
the  very  different  C.  viaregia.  There  resulted  a  complex  of  forms  in  a 
state  of  flux.  Had  this  been  described  by  a  naturalist  not  aware  of  the 
history  it  would  have  been  described  as  an  instance  of  a  very  variable 
species.  But  its  heterogeneity  was  tlie  result  of  the  outbreeding.  The 
inference  is  that  similar  heterogeneous  colonies  may  be  the  result  of 
outbreeding.  The  crossing  is  spoken  of  as  having  an  energizing  effect 
on  the  new  product,  but  this  may  be  the  result,  one  would  think,  of  the 
pooling  of  corroborative  hereditary  characters  rather  than  of  a  physio- 
logical stimulus  in  the  hybrid  offspring.  Many  of  the  Bahama  colonies 
illustrate  the  homogeneity  which  follows  the  inbreeding  consequent  on 
isolation  or  insolation.  J.  x\.  T. 

S,  Lamellibrancliiata. 

Crystalline  Style  in  Mya  arenaria.—  Charles  Howard  Edmoxdson 
{Journ.  Exper.  ZooL,  1920,  30,  259-91,  30  figs.).  About  50  p.c.  of 
individuals  survive  the  extraction  of  the  crystalline  style  by  a  severance 
of  the  style  sac.  A  new  style  is  formed  in  the  proximal  portion  of  the 
style  sac  in  about  74  days  when  the  conditions  are  most  favourable.  It 
is  seen  beginning  at  the  end  of  the  fourth  day  as  a  dehcate  sheath 
of  mucus  enclosing  a  core  of  food  material,  and  lies  on  one  of  tne 
typhlosoles,  usually  the  right.  It  grows  more  rapidly  in  sununer  than 
in  winter.  Under  favourable  conditions  a  crystalline  style  is  reformed 
in  the  short  distal  portion  of  the  style  sac,  whicii  is  entirely  separated 
from  the  proximal  division  by  the  operation.  This  proves  that  the 
epithelium  of  the  style  sac  is  the  source  of  the  crystalline  style.  The 
axillary  food  core  disappears  as  the  style  becomes  fully  formed.  The 
ingestion  and  digestion  of  food  is  apparently  dependent  upon  the  degree 
of  develoinnent  of  the  crystalline  style,  since  not  until  the  organ  reaches 
a  state  of  sufficient  maturity  to  be  projected  into  the  stomach  does  the 
ingestion  of  food  occur.     The  animal  may  be  kept  alive  out  of  water 


ZOOLOGY    AND    BOTANY,    MICKOSCOPY,    ETC.  315 

and  without  food  for  fourteen  days  after  the  extraction  of  the  style.  A 
new  style  begins  to  be  formed,  but  it  does  not  develop  far.  The 
typhlosoles  supply  the  material  for  the  substance  of  the  crystalline  style, 
and  the  shorter  cells  with  strong  ciha  assist  in  moulding  it  into 
cylindrical  form  and  at  the  same  time  rotate  it  and  push  it  into  the 
stomach.  J.  A.  T. 

Muscles  of  Bivalves.— R.  Anthony  {Arch.  Zool.  Exper.,  1919,  58, 
Notes  et  Revue,  1,  1-10,  o  figs.).  In  the  adductor  muscles  of  Lamelli- 
branchs  there  are  two  kinds  of  fibres — {(t)  smooth  fibres  with  a  high 
coefficient  of  shortening,  used  in  slow  sustained  movements  (the  nacreous 
portion)  ;  and  {h)  fibres  with  a  co-efficient  of  shortening  not  so  high, 
associated  with  rapid  and  less  sustained  movements— which  sometimes 
show  distinct  striations  and  sometimes  an  apparently  quite  different 
lozenge-shaped  structure,  occurring  in  many  Invertebrates.  According 
to  Anthony,  the  fibres  with  the  lozenge  structure  are  fixed  stages  of  the 
transition  between  smooth  and  striped  muscle,  and  are  associated  with 
increasing  rapidity  of  movement.  This  is  opposed  to  Marceau's  view, 
which  interprets  the  lozenge-like  pattern  as  due  to  the  intercrossing  of 
two  layers  of  spiral  fibrils.  Anthony  points  out  that  the  transition  may 
be  seen  in  one  fibre,  and  maintains  that  the  theory  of  helicoidal  fibrils 
does  not  work.  J.  A.  T. 

Shell  of  Cockle.— C.  L.  Walton  {Report  Lancashire  Sea-Fisheries 
Laboratory,  1911),  28, 17-50).  Concentric  grooves  denote  periods  during 
which  growth  has  ceased,  notably  winter,  and  their  number  increases  in  a 
regular  manner  along  with  the  increase  in  the  size  of  the  shell.  Variations 
in  food  supply  and  other  environmental  conditions  also  affect  the  shell. 
Large  forms  showed  seven  to  ten  grooves.  Tliere  is  no  correlation 
between  the  number  of  ribs  (twenty  to  twenty-seven)  and  the  age  and 
size  of  the  shell.  In  the  smallest  specimens  examined  (0*98-1  "50  cm. 
in  dorso-ventral  diameter)  the  number  of  ribs  varied  in  exactly  the  same 
•degree  as  the  largest  (;^>  •  50-1  -11  cm.).  J.  A.  T. 

Arthropoda. 
a.   Insecta. 

Isle  of  Wight  Disease  in  Hive  Bees.— John  Rennie  and  Elsie 
J..  Harvey  {Scottish  Joiirn.  Ar/ric,  1919,  2,  1-13).  The  presence  of 
this  disease  in  a  stock  is  manifested  by  the  inability  of  the  worker  bee  to 
fly.  They  loiter  on  the  ahghting  board,  on  the  ground,  on  grass.  They 
gather  in  clusters  and  lie  almost  motionless.  Individual  bees,  once  stricken 
with  the  disease,  do  not  recover,  but  a  remnant  of  a  badly  affected  stock 
was  kept  alive  for  two  months  in  the  autumn.  Within  the  hive  the 
smitten  bees  do  little  work,  feed  little,  show  lack  of  co-ordination  of 
fore-  and  hind-wing,  and  often  fall  from  the  frames.  Very  generally  the 
hind-gut  becomes  dilated  with  undischarged  faeces,  which  is  largely  due 
to  the  incapacity  of  the  bee  for  flight,  defecation  normally  occurring 
when  on  the  wing.  It  is  suggested  that  infection  takes  place  most 
readily  through  contact  with  sick  bees,  in  the  early  adult  phase  before 


316  SUMMARY    OF    CURRENT    RESEARCHES    RELATING   TO 

foraging.  It  is  not  certain  that  drones  take  it.  The  continual  produc- 
tion of  new  bees  may  enable  a  stock  to  make  s^ood  its  losses  from  disease^ 
but  there  is  no  recovery  of  sick  bees  nor  any  ultimate  survival  of  a  badly 
infected  stock.  Some  other  diseases  may  be  mistaken  for  Isle  of  Wight 
disease.  It  is  an  infectious  disease,  but  not  causally  connected  with 
Nosema  apis.  J.  A.  T. 

Mountain  Ants  of  Western  North  America.— W.  M.  Wheeler 
{Proc.  Amer.  Acad.  Arts  Sci.,  1917,  52,  457-569).  Ants  are  specially 
fitted  for  the  mapping  out  of  geographical  regions,  for  they  are  not 
dependent  on  specific  food- plants  ;  their  colonies  are  stable  and  stationary 
entities  ;  they  are  very  sensitive  to  climatic  and  otiier  environmental 
influences.  They  may  ascend  to  a  great  height  in  their  nuptial  flights, 
but  no  colonies  are  established  at  high  altitudes,  and  the  wing-muscles 
are  not  capable  of  being  used  for  more  than  a  few  hours  after  fertiliza- 
tion. The  author  has  made  a  study  of  the  conditions  of  humidity 
(warmth,  slope  exposure,  steepness,  and  so  on)  that  determine  the  distri- 
bution of  mountain  ants,  and  has  analysed  the  characteristics  of  various 
ant  faunas  in  North  America.  J.  A.  T. 

The  Argentine  Ant  in  Madeira.— M.  C.  Grabham  {Rep.  British 
Assoc,  1919,  87,  209).  Insidiously  introduced  into  Madeira,  Iridcmyr- 
7nex  humilis  has  suppressed  competing  species,  has  established  destructive 
colonies  up  to  2,500  ft.  above  sea  level,  has  ruined  coffee  cultivation,  many 
fruit  trees  {Citrus  especially),  and  crops  of  sweet  potatoes  {Batatus),  and 
has  invaded  every  house.  There  is  no  winter  weather  to  check  the 
increase.  Poultry,  young  birds,  and  bees  are  defenceless.  The  ants  are 
ingenious  and  persistent  in  food-searching.  They  transplant  the  pupjB 
to  favourable  conditions.  They  make  bridges  to  reach  flies  caught  on 
sticky  fly-paper.  The  females  are  mostly  impregnated  within  the 
formicary  and  immediately  afterwards  shed  their  wings.  There  is  great 
harmony  in  working,  and  there  is  a  singular  absence  of  fighting  when 
separate  communities  meet.  The  ant's  enemies  are  few.  Spiders  devour 
them  ;  and  one  spider  in  particular,  Pholcus  phalangioides,  is  very 
formidable.  Chalk  powder  is  a  useful  counteractive,  and  banding  witla 
rags  soaked  in  corrosive  sublimate.  A  circle  of  powdered  potassium 
cyanide  round  one  lemon  tree  killed  all  the  comers  and  goers,  and 
showed  that  40,500  ants  had  been  tending  the  scale-insects  on  this  one 
tree.  The  ant  appears  to  be  as  serious  a  pest  as  Colorado  beetle  or 
cotton-boll  weevil.  One  hope  is  in  eventual  exhaustion  and  decreased 
fertility.  J.  A.  T. 

Australian  Cerapachyini. — W.  M.  AVhekler  {Proc.  Amer.  Acad. 
Arts  Sci.,  1918,  53,  215-G5, 17  figs.).  The  Cerapachyini  are  of  unusual 
interest  to  the  myrmecologist,  because  they  represent  one  of  the  most 
primitive  sections  of  the  most  primitive  sub-family  of  ants,  the  Ponerinje, 
and  because  they  are  so  closely  related  to  the  sub-family  Dorylimi)  as  to 
suggest  that  the  latter  must  have  arisen  from  Cerapachyine  ancestors. 
They  form  small  colonies,  like  most  Ponerina^.  The  species  of 
Eusphinctus  (with  the  i)robal)le  exception  of  E.  turneri)  are  hypogasic 
in  habits,  a  peculiarity  also  indicated  by  the  absence  of  eyes  in  the 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  317 

workers  of  nearly  all  the  species  and  the  small  eyes  of  the  females.  The 
large-eyed  members  of  the  genus  Phyracaces  forage  in  troops  (or  in  whole 
colonies  ?)  on  the  surface  of  the  ground,  their  prey  consisting  of  the 
brood  of  other  ants.  The  workers  of  the  Cerapachyini  are  easily  recog- 
nized by  their  long,  slender,  jointed  bodies  ;  the  petiole  and  post-petiole 
of  the  abdomen  are  distinct ;  and  in  Eusphinctus  even  the  gastric 
segments  are  marked  off  from  one  another  by  pronounced  constrictions. 

J.  A.  T. 

Ants  of  Borneo. — W.  M.  Wheeler  {Bull.  Mus.  Gomp.  Zooh 
Harvard,  1919,  63,  43-147).  A  list  of  256  Bornean  species  is  given, 
adding  58  to  the  known  fauna,  and  23  new  to  science.  On  the  whole, 
the  fauna  has  many  forms  in  common  with  Sumatra,  Java,  and  the  Malay 
Peninsula,  but  many  seem  to  be  peculiarly  Bornean.  "  Of  course, 
Borneo  has  been  invaded  by  the  usual  tropicopolitan  tramp  species." 
But  the  most  interesting  fact  is  that  the  series  of  Bornean  genera  com- 
prises, especially  in  the  mountains,  several  of  ancient  aspect,  like 
Cerapachys,  Phyracaces,  Metapojie,  Dimorphomyrmex,  Gesomyrmex, 
Echinopla.  Several,  like  Gesomyrmex  chaperi,  are  probably  relicts  of  the 
once  very  widely  distributed  Eocene  ant  fauna.  J.  A.  T. 

Frit-Fly  on  Oats. — T.  H.  Taylor  {Pamphlets  Agric.  Dept.  Univ. 
Leeds,  1918,  108,  1-12,  12  figs.).  A  finely  illustrated  account  of  this 
serious  pest.  Shining  black  flies,  less  than  ^th  of  an  inch,  appear  in  May 
and  June.  After  mating,  the  females  lay  their  eggs  upon  the  young 
corn  between  the  lowermost  sheaths.  The  white  Qg^  is  a  mere  speck  to 
the  naked  eye.  The  female  has  a  retractile  egg-laying  tube.  The 
hatched  larv^  cut  a  short  spiral  track  through  the  intervening  leaves, 
attack  the  growing  point,  and  pupate  in  the  recesses  of  the  plant.  The 
flies  of  the  summer  brood  emerge  in  July  or  the  beginning  of  August, 
and  lay  eggs  upon  belated  tillers,  or  more  especially  on  young  ears,  the 
eggs  being  usually  placed  on  the  inner  surface  of  the  chaff.  The  larvae 
pupate  in  the  grain,  and  a  third  brood  emerges  during  August  and  Sep- 
tember. These  lay  in  a  winter  cereal  or  on  a  grass.  The  larvae,  feeding 
through  the  winter  on  the  grass  shoots,  pupate  in  April  or  May,  and  give 
rise  to  the  first  brood  of  flies  of  the  new  season.  The  larvas  only  live 
through  the  winter.  In  spring  and  summer  the  life-history  takes  about 
thirty-five  days.  Death  occurs  after  egg-laying.  Frit-flies  are  con- 
spicuous chiefly  on  sunny  days,  when  they  seek  the  tops  of  plants.  They 
move  in  a  leisurely  way,  occasionally  taking  short  flights  from  one  leaf 
to  another.  It  is  probable  that  frit-flies,  like  many  other  insects  which 
lay  their  eggs  separately,  spend  a  considerable  time  over  the  process  and 
require  to  feed.  They  are  unusually  wary  and  shy  when  laying  their 
eggs.  J.  A.  T. 

Urticating  Hairs  of  Parasa  lepida. — P.  E.  Keuchenius  {Tijdschr. 
Nederland.  Dierk.  Ver.,  1916,  15,  94-109,  1  pi.,  1  fig.).  It  is  well 
known  that  the  setee  of  some  caterpillars,  like  Thaumatopma,  the 
Procession  Caterpillar,  produce  great  skin  irritation.  The  author  has 
studied  the  urticating  setae  of  a  Javanese  caterpillar,  Parasa  lepida. 
There  is  considerable  variety,  and  a  description  is  given  of  :  {a)  delicate 


318  SUMMARY    OF   CURRENT    RESEARCHES    RELATING   TO 

pointed  setie,  each  containing,  enclosed  in  a  fold  of  epithelium,  a  single 
glandular  cell  with  a  large  branched  nucleus  ;  {b)  flagelliform  seta?  ; 
(c)  flask-shaped  and  conical  setae  ;  and  (d)  branched  setfe,  in  which  the 
glandular  cell  is  at  its  simplest.  It  is  probable  enough  that  the  glandular 
cell  which  fills  most  of  the  epithelium-lined  cavity  of  the  urticating  seta 
is  of  epidermic  origin,  like  the  epithelium  itself.  In  its  young  stage  the 
glandular  cell  is  in  communication  with  the  epithelium  and  the  epidermis 
by  means  of  protoplasmic  threads.  The  author  notes  that  we  are  not 
yet  quite  certain  whether  the  hairs  of  the  Procession  Caterpillar  are 
glandular  or  not.  J.  A.  T. 

Vitality  and  Longevity  of  Silkworm  Moths  during^  Cold  and 
Rainy  Season.— Maude  L.  Cleghorn  [Joimi.  and  Froc.  Asiatic  Soc. 
Bengal,  1919,  15,  101-5,  ?.  plates  of  tables).  On  the  whole  the  moths 
live  very  long  during  the  cold  seasons,  fairly  long  in  the  hot  weather, 
but  only  a  few  days  in  the  rainy  season.  There  is  always  a  pronounced 
rise  in  the  vitality  of  the  moths  in  the  cold  season,  and  a  fairly  sudden 
drop  in  the  rainy  season.  J.  A.  T. 

Metamorphosis  of  Lepidoptera. — Edna  Mosher  {Ball.  Illinois 
State  Lab.  Nat  Hist.,  11)16,  12,  17-159,  9  pis.).  Including  a  good 
account  of  the  changes  preceding  pupation.  The  first  striking  difference 
between  larva  and  pupa  is  the  diminution  of  size  in  the  latter,  winch  is 
especially  associated  with  the  reduction  of  the  alimentary  canal.  The 
absence  of  legs  is  only  apparent  ;  the  scars  of  the  pro-legs  remain  ;  so 
do  indications  of  the  larval  seta?.  The  full-grown  larva  usually  hastens 
to  pupate.  The  larval  cuticle  becouies  wrinkled  ;  the  moulting 
glands  pour  their  secretions  between  the  outer  and  inner  layers  of  the 
cuticle.  The  old  cuticle  is  loosened  off  and  splits  along  the  middle  line 
of  the  thorax,  and  is  worked  towards  the  tail-end.  The  liberated  piipa 
is  covered  with  a  very  thin  cuticle.  In  the  genus  jlIicropter?jx  the 
appendages  of  the  pupa  are  all  movable,  and  so  are  all  but  the  posterior 
segments  of  the  abdomen.  In  ordinary  cases  the  appendages  are 
soldered  to  each  other,  and  in  the  more  specialized  forms  to  the  body 
surface  as  Avell.  The  mobihty  of  the  abdominal  segments  is  reduced  to 
nil.  Before  the  emergence  of  the  imago  the  individual  appendages 
usually  get  free.  In  more  specialized  forms  the  hard  pupal  cuticle 
remains  in  one  piece,  except  for  the  slit  through  which  the  imago 
emerges.  In  the  highly-specialized  Lepidoptera  the  appendages  are  not 
fully  formed  when  pupation  takes  place,  but  consists  of  the  transparent 
cuticular  coverings  through  which  one  or  more  slender  trachea)  may  be 
seen.  J>efore  the  pupa  covering  is  cast  the  cuticular  parts  of  the  adult 
are  fully  formed  in  wliat  is  sometimes  called  the  pre-imago  stage. 

J.  A.  T. 

Classification  of  Lepidoptera  based  on  Pupal  Characters.— Edna 
Mosher  {Ball.  Illinois  State  Lab.  Nat.  Hist.,  11)1(5,  12,  17-150,  1)  pis.). 
It  is  shown  that  the  following  pupal  characters  may  be  used  to  good 
effect  in  the  determining  ])liylogeny  : — The  number  of  movable  segments, 
the  freedom  of  the  api)endages,  the  number  of  sutures  present  in  the 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  319 

head,  the  relative  length  of  the  body  segments,  the  presence  or  absence 
of  visible  labial  palps  and  maxillary  palps,  the  presence  of  exposed 
portions  of  the  prothoracic  femora  in  specialized  pupae,  and  the  method 
of  dehiscence.  J.  A.  T. 

Markings  of  Lepidopterous  Pupge. — J.  F.  yan  Bemmelen  {Proc. 
K.  Akad.  Wetensch.  Amsterdam,  191H,  21,  1-10).  According  to  the 
author  the  colour-markings  of  ])utterflj  pup^e — those  on  the  body  as 
well  as  those  on  the  wing-sheaths — are  to  be  regarded  as  an  original 
pattern,  the  uniform  colour  of  the  white,  yellow,  brown  or  black  pupa3  of 
most  moths  resulting  from  the  loss  of  the  primitive  design.  Theories 
of  sympathetic  coloration  and  influence  of  surroundings  are  not  necessary 
to  explain  the  manifestation  of  the  pattern.  It  is  not  denied,  however, 
that  modifications  of  the  pattern  may  secondarily  come  to  have  some 
protective  value.  J.  A.  T. 

Structure  and  Habits  of  Cryphalus  abietis. — Walter  Ritchie 
{Ann.  Applied  BioL,  11)19,  5,  171-99,  15  figs.).  A  description  of  this 
wood-boring  Scolytid  beetle,  and  a  contrast  between  it  and  C.  picea3  ;  an 


Mi*MMMi**MM<M<MUWM 


First  maxillae  and  labium  of  larva  of  Ghryphalus  abietis. 
Greatly  magnified. 

c,  eardo  ;    s.,  stipes;    mx.p.,  maxillary  palp;    la.,  lacinial  lobe;    1.,  ligulae  ;    ] 
Z.^:*.,  labial  palp  ;  m.,  mentum;  s.m.,  sub-mentum  ;  s. a.,  sub-mental  area. 

account  also  of  the  larva  and  pupa,  of  the  brood-galleries,  and  of  the 
internal  reproductive  organs.  There  are  excellent  figures.  The  larvse 
are  destroyed  in  numbers  by  a  Chalcid  parasite.  The  parent  beetle 
makes  a  circular  burrow  round  the  base  of  a  branch,  and  the  larval 
galleries  radiate  out  on  all  sides  almost  at  right  angles.  The  parent 
beetles  do  not  all  die  after  egg-laying,  but  in  many  cases  feed  anew  prior 
to  a  possible  second  egg-laying.  ^  J.  A.  T. 


320  SUMMARY    OF   CURRENT   RESEARCHES   RELATING   TO 

'  Study  of  Setal  Pattern  of  Caterpillars  and  Pupae. — A.  Schierbeek 
{Tijdsckr.  Nederlancl  Dierk.  Ver.,  1917,  15,  261-418,  5  pis.).  A  wide 
study  of  caterpillars  and  pup^  has  led  the  author  to  the  following  con- 
clusions : — The  modern  architecture  of  the  insect's  thorax  is  quite 
secondary.  The  anal  segments  vary  considerably  in  number  in  different 
species.  To  begin  with  all  the  abdominal  segments  bore  a  pair  of  legs. 
The  various  types  of  setal  arrangement,  for  which  a  new  nomenclature 
is  proposed,  can  be  derived  from  each  other.  A  metamerically  repeated 
pattern  of  pigment  spots  is  more  primitive  than  a  pattern  of  stripes.  The 
change  of  setae  into  verrucsB  is  a  reversible  process.  The  pupa  and  the 
first  caterpillar  instar  are  both  primitive,  while  the  other  larval  instars 
are  to  be  considered  as  secondary  adaptations.  The  pupa  is  to  be  regarded 
as  a  sub-imaginal  stage  which  has  become  secondarily  stationary.  The 
various  types  of  caterpillars  have  for  the  most  part  evolved  independently 
of  or  parallel  to  one  another.  A  general  larval  pattern  for  the  Holome- 
tabola  is  still  uncertain.  J.  A.  T. 

Bacterial  Disease  of  Larvae  of  June  Beetle.— Z.  Xorthrup  {Rep. 
Michigan  Acad.  Sci.,  191  o,  15,  G-l).  The  grubs  of  the  June  beetle 
{Lachnosterna  sp.),  which  do  serious  damage  to  crops,  were  found 
infected  by  a  Micrococcus  which  blackened  the  tissues.  Healthy  larvae 
placed  in  inoculated  soil  were  quickly  infected,  especially  if  a  cut  was 
made  in  the  integument.  The  disease  was  transmitted  to  Allorhina 
nitida,  another  June  beetle,  and  to  the  cockroach.  It  may  turn  out  to  be 
useful  as  a  remedial  measure.     Rabbits  and  guinea-pigs  are  immune. 

J.  A.  T. 

Muscid  Larva  sucking  Blood  of  Nestlings. — 0.  E.  Plath  {Publi- 
cations Univ.  California,  Zoology,  1919,  19,  191-200).  Evidence  of 
nestling  birds  {Astragalinus,  Zonotrichia,  etc.)  being  sucked  and  weakened 
or  killed  by  larvse  of  Frotoccdliphora  azurea  (Fallen).  The  larva3  were 
gorged  with  blood,  which  is  stored  in  a  diverticulum  of  the  oesophagus 
just  behind  the  pharynx.  Pupation  occurs  in  the  faeces  at  the  bottom 
of  the  nest.  Some  blood  seems  to  be  necessary  if  the  larvae  are  to  reach 
maturity.  Forty-four  nests  infested  with  larvae  of  P.  azurea  (and 
P.  chrysorrho^a)  have  been  recorded.  J.  A.  T. 

Chromosomes  in  Larva  of  Corethra  plumicornis.  —  Armand 
Dehorne  {Arch.  Zool.  Exper.,  1919,  58,  Notes  et  Revue,  pp.  25-30, 
10  figs.).  The  somatic  cells  show  three  chromosomes,  which  seems  to  be 
the  diploid  number.  The  smallness  of  the  number  is  remarkable,  and 
the  fact  that  it  is  an  odd  number.  How  the  meiotic  division  is  accom- 
plished lias  not  been  observed  as  yet.  The  material  is  well  suited  for 
the  study  of  mitosis.  J.  A.  T. 

Larva  of  Micrometrus  lineatus. — F.  C.  Eraser  {Records  Indian 
Museum,  1919,  16,  197-S,  1  pi.).  This  dragon-fly  larva  from  Poona 
lives  in  quickly  running  water,  holding  on  tightly  to  roots,  submerged 
twigs  and  the  like.      They  are  difficult  to  collect  because  they  grip 


ZOOLOGY    AND    BOTANY,  MICROSCOPY,    ETC. 


321 


firmly  and  because  they  accumulate  dehris  on  the  short  hairs  which  cover 
the  abdomen  and  caudal  appendages.  They  are  rectal  breathers.  No 
true  or  functional  caudal  gills  are  present,  these  being  replaced  by  two 


Larva  of  Micrometrus  Uneatus,  with  the  mask  shown  on  the  right. 

caudal  appendages  which  seem  only  to  serve  for  defence.  These  parts 
are  readily  surrendered  by  autotomy,  as  is  probably  the  case  in  the 
related  Rhinocvphine  larva.     The  "  mask  "  is  long  and  narrow. 

J.  A.  T. 

British  Orthoptera.  — W.  J.  Lucas  {A  Mo7iograph  of  the  British 
Orthojjtera,  Ray  Society,  1920,  1-261,  25  pis.,  25  figs.).  The  author  is 
to  be  congratulated  on  the  completion  of  this  very  welcome  monograph, 
which  deals  with  thirty-one  indigenous  species  and  eight  naturalized 
aliens.  The  sub-orders  include  the  earwigs,  the  cockroaches,  the 
crickets,  the  long-horned  grasshoppers  and  the  short-horned  grass- 
hoppers. The  workmanship  of  the  monograph  is  at  a  high  level,  and 
there  is  a  generous  supply  of  illustrations.  J.  A.  T. 

5.  Arachnida. 

Sarcoptid  Mite  in  a  Cat. — Harold  Cummings  {Report  Michigan 
Acad.  Sci.,  1913,  15,  106).  Note  of  occurrence  of  Notoedres  cati 
Hering,  heavily  infesting  a  cat  at  Ann  Arbor,  and  causing  loss  of  hair 
over  a  large  surface.  The  genus  includes  Sarcoptid  mites  infecting 
cats  and  rabbits,  but  there  seem  to  be  few  records  of  their  distribution. 

J.A.T. 


Pygidium  of  Trilobites.— P.  E.  Raymond  {Geol.  Mag.,  1920,  57, 
22-5).  The  large  pygidium  is  primitive  and  the  small  one  is  specialized. 
The  thorax  grows  through  the  degeneration  of  the  pygidium,  new 
segments  being  pushed  forward  through  the  pygidium  by  those  which 
are  added  in  the  growing  area  immediately  in  front  of  the  anal  segment. 
The  free  segments  of  the  thorax  become  such  by  the  breaking  down  of 
a  large  pygidium,  and  a  small  pygidium  is  the  result  of  the  degeneration 

Y 


322  SUMMARY    OF   CURRENT   RESEARCHES   RELATING   TO 

of  a  large  one.  The  large  primary  pygidium  was  probably,  as  Spencer 
suggested,  of  use  as  a  caudal  fin  in  swimming.  Perhaps  the  group  had 
a  pelagic  rather  than  a  benthonic  origin.  J.  A.  T. 


e.  Crustacea. 

Life-history  of  Cape  Crawfish. — J.  D.  F.  Gilchrist  {Joum. 
Linn.  Soc.  ZooL,  1920,  34,  180-201,  2  pis.,  13  figs.).  The  embryonic 
development  of  Jasus  lalandu  remains  unknown,  but  the  naupliosoma 
stage  and  the  phyllosoma  have  been  observed.  The  transition  from 
the  phyllosoma  to  the  puerulus  is  not  known,  but  the  pueruli  have 
been  followed  to  the  post-puerular  stage.  The  red  spots  on  the 
underside  of  the  puerulus  disappear  and  all  the  upper  parts  become 
coloured  ;  the  spines  of  the  carapace,  definite  in  number  in  the 
puerulus,  become  much  more  numerous  ;  there  are  changes  in  anten- 
nules,  mandibles  and  some  other  appendages  ;  the  exopodites  of  the 
pereiopods  disappear ;  the  cervical  groove  is  well  marked ;  the  telson 
has  additional  spines  ;  and  so  on.  The  post-puerulus  differs  from 
succeeding  stages  in  having  the  cuticle  uncalcified,  in  having  the 
incisor  part  of  the  mandible  provided  with  denticles  on  the  margin  of 
its  thick  cuticle,  in  showing  no  sex  differentiation  in  the  pleopods, 
and  in  the  third  maxillipedes  being  separate  at  their  bases.       J.  A.  T. 

Species  of  Asellus. — E.  G.  Racovitza  {Arch.  Zool.  Exper.^  1919, 
58,  Notes  et  Revue,  31-43,  12  figs.).  It  appears  that  Asellus  aqKcitkus 
auct.  is  a  taxonomic  error  which  has  lasted  for  nearly  two  centuries. 
Under  this  name  there  are  ranked  a  medley  of  different  forms,  of 
diverse  origin  and  taxonomic  value,  but  not  forming  one  species. 
The  author  differentiates  a  northern  species  Asellus  aquaticus  Linne  and 
an  older  species  A.  meridianus  of  more  southern  distribution.    J.  A.  T. 

Study  of  Asellus. — E.  G.  Racovitza  {Arch.  Zool.  Exper.,  1919, 
58,  Notes  et  Revue,  49-77,  38  figs.).  A  minute  discussion  of  Asellus 
coxalis  sp.  n.  (Syrian),  A.  coxalis  peyerimhoffi  subsp.  n.  (Algerian),  and 
A.  ianyidensis  (France),  which  in  respect  to  several  important  structures 
form  a  very  definite  orthogenetic  series.  The  origin  of  the  stock  may 
be  looked  for  in  Asia  Minor,  whence  it  has  spread  along  the  southern 
shores  of  the  Mediterranean.  Attention  is  also  directed  to  the  sex 
dimorphism  and  to  the  abundance  of  a  large  commensal  protozoon, 
Stylocometes  cUgitatus  CI.  and  L.,  on  the  endopodites  of  the  pleopods. 

J.  A.  T. 

Studies  on  Asellidae. — E.  G.  Racovitza  (Arch.  Zool.  Exper.,  1920, 
58,  Notes  et  Revue,  79-115,  33  figs.).  A  detailed  discussion  of  the 
first  and  second  pleopods  in  Asellidie,  which  have  come  to  be  associated 
with  reproduction  and  have  undergone  reductions  and  transformations. 
In  the  male  the  first  pleopod  is  reduced  to  two  undivided  joints,  a 
sympodite  and  an  exopodite  ;  it  is  absent  in  the  female.  In  the  male 
the  second  pleopod  shows  an  undivided  sympodite,  a  slightly  modified 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  323 

two-jointed  exopodite,  and  an  endopodite,  biarticulate  or  undivided, 
transformed  into  a  copulatory  organ.  It  is  reduced  to  one  piece  (fused 
sjmpodite  and  exopodite)  in  the  female.  There  is  also  a  discussion  of 
Asellus  communis.  J.  A.  T. 

Sex-intergrade  Strain  of  Cladocera. — Arthur  M.  Banta  {Proc. 
Soc.  Exjjer.  Biol.  Medicine,  1916,  14,  3-4).  After  130  parthenogenetic 
generations  of  Simocephalus  vetulus,  in  the  course  of  which  only  females 
occurred,  there  being  no  males  nor  sexual  eggs,  the  131st  generation 
showed,  in  addition  to  normal  females,  both  males  and  many  sorts  of 
sex  intergrades.  "  There  occurs  practically  every  gradation  from  the 
entirely  normal  female  with  a  full  complement  of  female  secondary 
sex  characters  ;  thi-ough  female  intergrades  of  all  sorts  ;  hermaphrodites, 
with  various  combinations  of  secondary  sex  characters ;  and  male 
intergrades  of  various  rank  ;  to  normal  males  with  all  the  primary  and 
secondary  sex  characters  distinctly  and  strongly  male."  J.  A.  T. 

Sex  Intergrades  in  Cladocera. — Arthur  M.  Banta  {Proc.  Nat. 
Acad.  Sci.,  1918,  373-9).  Unmistakable  intermediate  sex  forms  are 
known  in  Riddle's  hybrid  pigeons,  Goldschmidt's  hybrid  gipsy  moths, 
and  Banta's  Cladocei-a.  They  are  not  sex  mosaics  but  sex  intergrades. 
In  Simoceijlialus  vetuJus  the  occurrence  of  clearly  marked  sex  intergrades 
is  rare  ;  it  is  not  so  unusual  in  Daj^hnia  longispina,  where  several  strains 
have  been  studied.  In  these,  however,  male  sex  intergrades  (i.e.  inter- 
grades with  testes)  are  almost  or  quite  lacking,  and  males  are  rare, 
whereas  in  the  Simocephalus  vetulus  sex  intergrade  stock  normal  males 
are  abundant  and  male  intergrades  are  common.  Sex  intergrade  pro- 
duction would  seem  to  be  the  result  of  a  disturbed  balance,  a  condition 
which  is  a  struggle  of  two  nearly  equal  factors  or  sets  of  factors,  the  one 
making  for  maleness,  the  other  for  femaleness.  The  resnlt  of  this 
struggle  of  factors  is  the  development  of  individuals  ostensibly  male  in 
part  and  female  in  part,  and  obviously  intermediate  in  part — but  as  a 
whole  distinctly  intermediate  in  sex  characters.  The  facts  suggest  that 
maleness  and  femaleness  are  not  complete  and  mutually  exclusive  states, 
but  that  sex  is  relative.  J.  X.  T. 

Selection  with  a  Pure  Line  of  Cladocera. — Arthur  M.  Banta 
{Proc.  Soc.  Exper.  Biol.  Medicine^  1919,  16,  123-4).  A  study  of  long- 
continued  selection  upon  several  parthenogenetic  pure  lines  (clones)  of 
three  species  of  Cladocera,  using  their  reactiveness  to  light  as  a  basis  for 
selection.  In  most  of  the  lines  the  results,  though  suggestive,  are 
inconclusive;  or  there  is  clearly  no  effect  of  selection  ;  or  (in  two  lines) 
the  results  even  suggest  slight  differences  in  the  reverse  of  an  effect  of 
selection.  But  with  one  line  of  Simocephalus  vetulus  the  result  of 
selection  was  pronounced  and  convincing.  This  line  was  subjected  to 
selection  for  a  period  of  54  months,  covering  181  generations  of  descent. 
In  the  final  ten  generations  the  strain  selected  for  greater  reactiveness 
to  light  had  a  reaction  time  less  than  one-third  as  large  as  that  for  the 
strain  of  the  same  line  selected  for  reduced  reactiveness  to  light. 

J.A.T. 
Y  2 


324      SU.MMAKY  OF  CUKKENT  RESEARCHES  RELATING  TO 

Cave  Ostracods. — Paul  Paris  {Arch,  Zool.  Exi^r.^  1920,  58, 
475-87,  4  pis.)-"  Not  maDy  Ostracods  are  known  from  caves,  but  that 
is  in  part  because  it  is  difficult  to  capture  these  minute  animals.  A 
description  is  given  of  Candona  breuili  sp.  n.  and  Sphseromicola  topsenti 
Paris.  The  latter  lives  in  commensalism  with  a  cave  Isopod,  Cseco- 
sphaeroina  hurgundum  (and  probably  on  G.  virei),  sheltering'  on  the  ventral 
surface  near  the  head,  and  hanging  on  veiy  firmly.  It  seems  to  repro- 
duce all  the  year  round.  It  cannot  live  aw^ay  from  the  Isopod,  but  it  is 
no  parasite.  A  detailed  account  is  given  of  the  appendages  of  both 
species.  J.  A.  T. 

Annulata. 

Madagascar  Polychsets.— P.  Fauvel  (Arch.  ZoolFqmr.,  191'.),  58, 
315-473,  3  pis.).  An  account  of  a  large  collection,  representative  of 
twenty-three  families,  and  including  nine  new  species.  In  Lumhriconereis 
papilHfera  sp.  n.  there  are  large  elongated  vesicles,  below  and  behind  the 
parapodia,  W'hich  represent  long  nephridial  ampullee.  In  Gravierella 
midtimi7itdatct  g.ets^f.n.  there  is  a  very  remarkable  intercalary  growth 
with  unique  peculiarities.  The  anal  cone  is  at  the  base  of  a  dilated 
funnel.  J.  A.  T. 

Vitelline  Membrane  of  Serpulids.^ — A.  Hovlier  {Arch.  Zool.  Ex2)er., 
1916,  56,  Notes  et  Revue,  16-20).  The  vitelline  membrane  disappears 
in  the  course  of  development.  In  Serpida  crater  it  disappears  from  off 
the  trochophore  cells  which  it  protects,  but  it  disappears  quite  gradually, 
beginning  at  the  posterior  end,  where  the  larva  grows  in  length.  It  is 
much  the  same  in  Hydroides  pectinata  and  Frotula  meilhaci,  where  the 
disappearance  is  again  posterior.  The  cuticle  is  an  epidermic  formation, 
and  the  idea  that  the  vitelline  membrane  is  transformed  into  the  cuticle 
is  not  to  be  entertained.  J.  A.  T. 

Australian  Exogonese.— W.  A.  Haswell  {Journ.  Linn.  Soc.  Zool., 
1920,  34,  217-45,  2  pis.,  2  figs.).  Descriptions  of  Australian  represen- 
tatives of  this  Polychagt  family,  including  Exogone  fustifera  sp.  n., 
Gruhea  pmsilloides  sp.  n.  It  is  demonstrated  that  the  pedal  glands 
produce  the  secretion  by  means  of  which  the  ova  are  attached  after 
extrusion.  A  description  is  given  of  the  proventriculus  with  its  non- 
striated  muscle-columns,  and  of  the  hitherto  undescribed  glands,  the 
ducts  of  which  open  into  it.  An  account  is  given  of  the  changes  under- 
gone by  the  nephridia  of  both  sexes  of  Exogone  in  association  with  the 
development  of  the  sex-cells.  In  Gruhea  pusilloides  there  is  distinct 
hermaphroditism.  The  author  also  describes  some  stages  in  the 
development  not  previously  investigated.  J.  A.  T. 


Nematohelminthes. 

Syngamus  laryngeus  in  Indian  Cattle. — A.  L.  Sheather  and 
A.  AV.  Shilston  {Bull.  Agric.  Research  Pusa,  1920,  No.  92,  1-8, 
28  figs.).  This  parasite  was  found  in  about  13  p.c.  of  700  buffaloes 
and  hill  bulls  and  in  about   15  p.c.  of  100  plains  cattle.     With  few 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  325 

excepfcious  they  occurred  in  the  larynx.  In  no  case  were  the  males  and 
females  found  apart.  An  account  is  given  of  the  general  structure  of 
both  sexes.  Except  in  one  special  case  no  pathogenic  effects  could 
be  traced  to  the  parasite.  It  seems  that  the  eggs  are  passed  out  under 
the  posterior  flap  of  the  saddle-shaped  pouch  of  the  male  embracing  the 
flattened  boss  on  the  body  of  the  female  on  which  the  vulva  opens.  For 
it  appears  very  wasteful  that  the  eggs  should  only  escape,  as  is  usually 
supposed  to  be  the  case  in  S.  trachealis,  by  the  bursting  of  the  female 
worm.  J.  A.  T. 

Platyhelmintlies. 

Head-g-eneration  in  Planarians. — C  M.  Child  {Journ.  Exper. 
ZooL,  1020,  30,  408-18,  8  figs.).  Isolated  pieces  of  Planaria  cloroto- 
cepliala  do  not  always  show  uniform  reconstitution  or  regeneration.  The 
structures  produced  at  the  anterior  ends  of  pieces  show  a  graded  series 
from  normal  heads  to  headless  healing  of  the  wound.  Five  types  have 
been  distinguished — normal,  normal  but  teratophtbalmic,  teratomor- 
phic  with  more  marked  inhibition  of  the  median  region,  anophthalmic 
without  eye-spots,  and  acephalic  with  a  mere  healing  of  the  wound  and 
no  outgrowth.  The  term  "  head-frequency "  is  used  to  indicate  the 
frequency  with  which  these  different  types  of  anterior  end  occur  in  a 
given  set  of  pieces.  Head-frequency  in  the  regeneration  of  pieces  is 
lower  in  physiologically  younger  (smaller)  than  in  physiologically  older 
(larger)  animals.  Head-frequency  is  lower  in  pieces  from  starved  than 
in  pieces  from  well-fed  animals,  even  when  the  two  are  of  the  same  size. 
Head-frequency  is  higher  in  pieces  which  are  frequently  stimulated  to 
motor  activity  during  at  least  several  hours  after  section  than  in  pieces 
remaining  undisturbed.  The  range  of  head  forms  is  the  same  in  relation 
both  to  physiological  conditions  and  to  external  chemical  and  physical 
agents,  and  the  changes  produced  are  changes  in  the  frequency  of  the 
different  forms.  This  non-spacific  effect  of  both  physiological  and 
external  factors  indicate  that  the  action  of  these  factors  is  essentially 
quantitative.  J.  A.  T. 

New  Japanese  Polyclads.— Megu^ii  Yeri  and  Tokio  Kaburaki 
{Aniiot.  Zool.  Japoii ,  1920,  9,  .591-8,  5  figs.).  A  description  of  Neo- 
stijloclms  fulvopunctatus  g.  et  sp.  n.,  near  Stylochus,  with  oval  body,  no 
tentacles,  marginal  eyes  confined  to  the  frontal  margin,  true  seminal 
vesicles,  prostate  dorsal  to  seminal  vesicle,  slender  tubular  penis,  and 
large  single  accessory  vesicle  to  the  vagina.  There  is  also  an  account  of 
Prosthiostomum  trilineatmn  sp.  n.,  differing  widely  from  other  species  in 
its  coloration.  J.  A.  T. 

New  Distome  fromRana  aurora. — W.  W.  Cort  {Publications  Unio. 
California,  Zoology,  1919,  19,  283-98,  5  figs.).  In  the  intestine  of  the 
red-legged  frog,  in  fourteen  cases  out  of  thirty,  anew  Distome  was  found, 
Marqeaaa  calif  or  niensis  g.  et  sp.  n.,  2*4-5  mm.  in  length.  It  shows 
the  characters  of  the  sub-family  Brachycoeliinae  ;  digestive  system  with 
prepharynx,  short  oesophagus,  and  intestinal  caeca  extending  into  the 
posterior  fifth  of  the  body,  but  not  reaching  the  posterior  end  ;  excretory 
system   of  the  "  2-6-3  "   type,  with  a  club-shaped  bladder ;  vitellaria 


326  SUMMARY    OF    CUKKENT    KESEAKCHES    RELATING   TO 


o.s, 


oes. 


Dorsal  view  of  Margeana  calif orniensis,  slightly  compressed, 
cir.,  cirrus  sac  ;    a-s.,  oesophagus  ;    i.,  intestinal  c»cum ;  w.,  mouth  ;  os. 
oral  sucker;    ov.,  ovary;   ph.,  lA^d^vynx;    .p^j/i.,  prcpharyux  ;    ^,  testis 
-26.,  uterus;  rif.,  vitellaria  ;  i;.s.,  ventral  sucker 


ZOOLOr;Y  AND  BOTANY,  MICROSCOPY,  ETC. 


327 


extendino-  from  in  front  of  the  pharynx  to  the  posterior  Hmits  of  the 
testes ;  cirrus  sac  large  ;  testes  large,  fillino-  most  of  the  width  of  the 
body.     Affinities  are  with  the  genus  Braelujccelium.  J.  A.  T. 

New  Cercaria  from  North   America.— AV.  AY.  Cort  {Jovrn.  Para- 
sitology,  I'Jls,   5,   .S6-91,   1    pL,   1  fig.).     In  Planorhis   compamdatus 


Cercarixum  mutahile.     Scale  equals  0-1  mm. 

A,  side  view  ;  B,  ventral  view  ;  o.s.,  oral  sucker  ;  ph.,  pharynx ;  ac,  aceta- 
bulum; ov.,  ovary  ;  ^.,  testes  ;  6.,  excretory  bladder  ;  a?s.,  oesophagus; 
exp.,  excretory  pore. 

smithii  Baker,  from  Douglas  Lake,  Michigan,  there  was  found  a  new 
Cercaria,  provisionally  named  Cenarisewn  mutahile.  The  redise  filled 
the  liver  of  the  snail. '  The  adult  is  not  known,  but  the  structure  of  the 
Cercaria  suggests  the    sub-family   AUocreadiinae.       The  Cercaria   has 


328  SUMMARY    OF   CURRENT    RESEARCHES    RELATING    TO 

practically  no  adaptive  larval  characters,  and  a  considerable  development 
of  adult  characters.  This  is  evidently  correlated  with  the  omission  of 
the  free-swimming  stage  of  the  life-history.  The  excretory  system 
consists  of  a  simple  club-shaped  bladder,  a  series  of  collecting  tubes,  and 
«ixty-four  flame  cells,  with  their  capillaries  arranged  in  eight  groups  of 
four  on  each  side.  J.  A.  T. 

Adaptability  of  Schistosome  Larvae  to  New  Hosts. — W.  W.  Cort 
{Journ.  Parasitology^  1918,  4,  171-;^).  In  many  cases,  e.g.  Fasciola 
hepatica,  the  larvae  of  Trematodes  can  flourish  in  species  which  are  not 
their  normal  specific  hosts.  The  larvae  of  Schistosoma  hsematobium  are 
known  from  BulUnus  contortus,  B.  di/botvski,  Physopsis  africana  ;  the 
larvae  of  Schistosoma  mansoni  is  known  from  Planorhis  boissyi  and 
P.  guadelupensis.  Other  examples  are  given  of  lack  of  specificity  in 
the  choice  of  intermediate  host.  Thus  among  fork-tailed  Cercarige 
Cercaria  douthitti  Cort  from  Lymneea  reflexa  has  been  found  in  L. 
stagnalis  oppressa,  L.  stagnalis  perampla,  and  Physa  ancillaria  parkeri ; 
and  an  undescribed  species  from  Douglas  Lake  was  found  in  three 
genera — Planorlis  trivolvis^  Lymnsea  exilis,  and  Physa  ancillaria.  The 
question  of  the  adaptability  of  the  schistosomes  to  new  interniediate 
hosts  becomes  a  problem  of  great  significance  in  relation  to  the  spread 
of  schistosomiasis.  J.  A.  T. 

Bryozoa. 

New  Japanese  Polyzoa. — Yaichiro  Okada  {Annot.  Zool.  Japon., 
1920,  9,  618-34,  1  pi.,  7  figs.).  A  report  on  thirteen  (five  new)  species 
of  Retepora  (including  Reteporellci)  and  two  species  of  Adeonella,  with 
figures  of  the  minute  structure  of  zocecia,  operculum,  and  the 
^'  mandibles  "  of  the  avicularia.  J.  A.  T. 

Echinoderma. 

Double  Hydrocoele  in  Sea-urchin  Larvae. — E.  W.  MacBride  (Rep. 
British  Assoc,  1919,  87,  207-<s).  When  plutei  of  Echinus  miliaris  are 
transferred  at  an  age  of  three  days  to  sea- water,  the  salinity  of  which 
has  been  increased  by  adding  2  grm.  of  NaCl  per  litre,  left  there  for  a 
week,  and  then  re-transferred  to  ordinary  sea-water,  they  show  at  the 
age  of  about  twenty-one  days  in  a  certain  percentage  of  cases  (not  more 
than  5  p.c.)  two  hydrocoeles.  It  is  suggested  that  the  exposure  to 
hypertonic  water  acts  on  a  hidden  rudiment  in  the  larva  and  starts  tlie 
right  hydrocoele  developing.  It  has  been  previously  shown  by  the 
author  that  the  organs  developing  on  one  side  of  the  larva  tend  to 
inhibit  the  development  of  similar  organs  on  the  other  side.  So,  when 
the  proper  hydrocoele  on  the  left  side  begins  developing  and  gets  a 
long  start  over  its  right  antimere,  it  may  check  and  eventually  entirely 
suppress  the  development  of  this.  The  re-transference  to  normal  sea- 
water  may  possibly  hold  up  temporarily  the  exuberance  of  development 
of  the  left  side  and  allow  the  right  side -to  hold  its  own.  "If  this 
supposition  be  'well  founded,  echinoderm  development  would  afford  a 
striking  instance  of  that  '  struggle  between  the  parts '  on  which  Roux 
has  always  insisted  as  an  important  feature  in  development."     J.  A.  T. 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,   ETC.  329 

Appearance  of  Division  Spindle  in  Sea-urchin  Ova.  — ;L.  V. 
Heilbrunn  (Journ.  Exper.  Zool,  1920,  30,  211-37).  During  the 
period  between  fertilization  and  the  first  cleavage  of  the  sea-urchin  egg 
the  viscosity  of  the  cytoplasm  rises  until  it  reaches  a  maximum,  then  it 
decreases  again.  Similar  changes  occur  in  relation  to  the  second  cleavage. 
The  changes  in  viscosity  are  very  marked. and  indicate  the  occurrence  of 
a  gelation  in  the  cytoplasm.  This  reaches  its  height  just  before  the 
spindle  appears  ;  later  on  the  cytoplasm  becomes  more  fluid  again.  The 
gelation  is  a  predetermining  factor  in  spindle  or  aster  formation  :  if 
it  is  suppressed  the  mitotic  figure  does  not  form.  Such  suppression  can 
be  produced  by  fourteen  different  substances,  all  lipoid  solvents  ;  it  can 
also  be  produced  by  cold.  Although  effecting  the  same  result,  the 
actions  of  cold  and  of  lipoid  solvents  are  mutually  antagonistic.  The 
effect  of  hypertonic  solutions  on  dividing  eggs  may  be  interpreted  as 
due  to  an  increase  of  the  cytoplasmic  viscosity.  Potassium  cyanide  and 
chloretone  also  act  in  this  way.  The  cytoplasmic  gelation  which  occurs 
in  relation  to  mitosis  is  apparently  due  to  an  abstraction  of  water,  for  it 
■can  be  most  closely  imitated  by  an  abstraction  of  water,  and  entrance  of 
water  into  the  fertilized  esfg  reverses  the  normal  cytoplasmic  gelation. 

J.  A.  T. 

Complete  and  Functional  Hermaphroditism  in  a  Sea  Urchin. — 
Maurice  Herlant  (Arch.  Zool.  Exper.,  1918,  57,  Notes  et  Revue, 
28-31,  1  fig.).     In  Paracentrotus  lividus  hermaphroditism  was  observed, 


■"■■ ^'K  ■■..WigM 


m 


Section  of  hermaphrodite  gonad  showing  large  oogonia 
and  numerous  minute  sperm-cells. 

a  very  rare  occurrence.  It  has  been  noted  by  Yiguier  in  Sphser echinus 
granular  is.  The  specimen  showed  three  normal  testes,  an  atrophied 
testis,  and  a  mixed  gonad  with  both  ova  and  spermatozoa.  Autogamy 
was  effected  artificially,  and  could  no  doubt  occur  in  nature.  Accidental 
hermaphroditism  has  been  recorded  in  Asterias  glacialis.  In  Asterina 
gihbosa  it  is  known  that  the  young  individuals  are  males  and  become 
female.  Giard  has  described  a  similar  condition  in  Echinocardium 
■cordatum.  J.  A.  T. 


330  SUMMARY  OF  ci;kk?:nt  researches  relating  to 


Ccelentera. 

Structure  of  Favia.— George  Matthai  {Brit.  Antarctic  ^' Terra 
Nova  "  Exped.,  Zoolof/i/,  1919,  5,  69-9(1,  4  pis.,  2  figs.).  In  Astr^id^e 
the  formation  of  colonies  takes  place  by  extra-tentacular  and  intra- 
tentacular  liuddintj— i.e.by  the  formation  of  ne\Ystomod8ea,  hence  of  buds, 
outside  or  inside  the  tentacular  rings  of  older  polyps.  In  both  cases  new 
stomodiea  arise  afresh  in  diverticula  by  invagination  of  the  oral  disc  or 
bj  union  of  the  margins  of  the  brv;ader  mesenteries,  without  involving 
the  longitudinal  fission  of  existing  stomodaea.  In  Favia  colony-formation 
is  mainly  by  intra-tentacular  budding,  but  extra-tentacular  budding 
unaccompanied  by  bilateral  and  hexameral  symmetry  occurs  at  the 
growing  edges  of  colonies.  A  description  is  given  of  the  corallum  and 
polyps  of  Favia  conferta,  which  is  compared  in  detail  with  F.  frag  urn.  A 
survey  is  taken  of  the  Atlantic  species.  J.  A.  T. 

West  African  Antipatharians. — H.jalmar  Broch  (Antipatharia, 
1920,  18-22,  2  figs.).  Little  is  known  of  Antipatharians  from  West 
African  waters.  A  description  is  given  of  Antipathes  (?)  spinescens 
Gray  and  Sticfiopathes  (?)  occidentalis  (Gray)  Brook.  The  dubiety 
refers  to  the  absence  of  polyps.  Attention  is  directed  to  fragments  of 
a  very  large  form  with  a  sinuous  main  axis  {Ih  cm.  in  diameter),  few 
lateral  branches,  and  almost  vestigial  spines.  The  form  suggests  Eoule's 
Antipathes  grimaldii.  J.  A.  T. 

Leptogorg-ia  irramosa  (Grieg). — Arvid  R.  Molander  {Arlciv  f. 
ZooL,  1919,  12,  No.  5,  1-7,  2  figs.).  A  revision  of  this  species 
(  =  Gorgonia  pinnata).  The  main  stem  is  not  prominent ;  the  branch- 
ing is  irregular  ;  the  polyps  are  about  2  mm.  long,  and  irregularly  or 
alternatively  disposed  on  the  stem  and  branches ;  the  calyx  is  usually 
distinct  and  about  1  mm.  high  ;  the  coenenchyma  includes  spindles  and 
double  stars;  the  polyps  show  spindles  which  form  eight  longitudinal 
douljle  rows  near  the  base  of  the  tentacles.  The  description  and 
photograph  given  do  not  convince  the  recorder  that  L.  irramosa  is  a 
Leptogorgia  at  all,  for  members  of  this  genus  are  marked  by  minute 
double  spindles  and  the  verruca;  are  typically  low  and  inconspicuous. 
The  suggestion  that  Stenogorgia  and  Call iateph anus  may  be  included  in 
tlie  Liciius  Leptogorgia  does  not  seem  to  the  recorder  to  be  warranted. 

J.  A.  T. 

Hydroids  of  Ingolf  Expedition.— Hjal^iar  Brock  (Danish  Ingolf 
Expedition,  1918,  5,  l-2<ir),  1  pi.,  1  chart,  95  figs.).  The  thecaphore 
hydroids  fall  into  four  main  groups  or  series  of  families,  the  most 
primitive  being  the  Hebellina  with  conical  proboscis  and  homogeneous 
gastral  endodertn.  From  this  are  derived  the  Haleciinaand  Sertulariina, 
with  the  .gastral  endoderm  not  homogeneous.  An  exceptional  position 
is  that  of  the  Proboscoida  with  clul)-shaped  proboscis.  The  author 
gives  an  account  of  a  large  collection  including  two  new  genera, 
Nemertesia  and  Nematocarpus,  and  some  new  species.  To  the  athecate 
forms  previously  dealt  with  is  added  Branchiocerianthus  reniformis  sp.  n. 
A  zoogeographical  survey  is  taken  of  the  Hydroid  Fauna  of  the  North 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  331 

Atlantic.  The  interest  of  the  laro-e  memoir  is  mainly  systematic,  hut 
the  introductory  chapter  proposing  a  classification  hased  on  the  characters 
of  the  nutritive  polyps  is  of  wider  interest.  J.  A.  T. 

Asexual  Multiplication  of  Microhydra  ryderi. — A.  Goette  {ZooL 
Anzelfjer,  I'.C^u,  51,  71-7,  8  figs.).  The  frustules  of  this  polyp  are  true 
buds,  which  are  separated  off  from  the  mother-animal  by  a  process  of 
division.  The  longitudinal  division  which  separates  off  a  frustule- 
primordium,  and  the  transverse  division  by  which  the  two  halves  of  the 
laterally  fixed  frustule  are  separated  from  one  another,  are  conditioned  by 
a  divergent  growth-movement  and  a  divergent  correlation.       J.  A.  T. 

Protozoa. 

Crystalloids  of  Entamoeba  histolytica. — Akmaxd  Dehorne  {Arch. 
ZooL  Exper.,  1910,  58,  Notes  et  Revue,  11-8,  4  figs.).  In  this  Amoeba, 
associated  with  abscesses  of  the  liver,  there  are  abundant  spindle-shaped 
crystalloids  which  appear  in  vacuoles  in  the  endoplasm.  They  corre- 
spond to  chromidia.  The  crystalloids  are  ephemeral ;  they  disappear  or 
are  much  reduced  when  the  cyst-envelope  is  formed.  Protozoa  with 
shells  or  capable  of  forming  cysts  have  an  important  chromidial  apparatus, 
and  this  is  causally  related  to  forming  the  shell  or  cyst.  The  crystalloids 
represent  a  stage  in  the  metabolism  that  leads  to  shell-making.  Perhaps 
trichocysts  are  similarly  related  to  memljrane-making.  Perhaps  every 
chromidial  apparatus  has  this  significance.  J.  A.  T. 

Nucleoplasmic  Relations  in  Arcella. — R.  AY.  Hegner  {Jouni. 
Exper.  ZooL,  1020,  30, 1-96,  47  figs.).  The  data  gathered  from  a  study 
of  four  species  favour  the  hypothesis  that  there  is  normally  a  definite 
quantitative  relation  between  nucleus  and  cytoplasm.  In  both  binucleate 
and  multinucleate  specimens  the  nuclei,  although  free  to  move  about  in 
the  cytoplasmic  mass,  become  arranged  in  such  a  manner  that  they  are 
equidistant  from  one  another,  and  hence  Lave  each  an  equal  amount  of 
cytoplasm  with  which  to  interact.  Many  micro-vivisection  experiments 
bear  out  the  idea  of  a  constant  mass  relation  between  cytoplasm  and 
nucleus.  An  excess  in  the  amount  of  cytoplasm  in  proportion  to  nucleo- 
plasm appears  to  be  dangerous.  The  final  conclusion  of  an  important 
investigation  is  that  the  size  of  the  organism  and  the  characteristics 
correlated  with  size  are  dependent  upon  the  chromatin  mass ;  that  changes 
in  these  characters  are  not  due  to  cytoplasmic  nor  chromidial  influence, 
but  to  qualitatively  unequal  nuclear  divisions,  resulting  in  two  types  of 
daughter  nuclei  differing  in  the  determiners  that  control  the  growth  of 
the  chromatin  ;  and  that  other  characters  that  vary  independently  must 
be  controlled  by  other  determiners  within  the  nuclei.  J.  A.  T. 

Chilomastix  mesnili  of  Man.— Charles  A.  Kofoid  and  Olive 
SwEZY  {Univ.  CaUfornia  Puhlications,  Zoology,  1920,  117-44,  3  pis., 
2  figs.).  In  the  human  intestine  this  is  a  common  and  widely  distributed 
parasite  often  mixed  up  with  Trichomonas  and  other  forms.  It  has  a 
deep  spiral  groove  running  posteriorly  from  right  over  to  left  as  a 
permanent  cell-organ  distinct  from  but  adjacent  to  the  cytostome.     It 


332  SUMMARY   OF   CURRENT   RESEARCHES    RELATING   TO 

persists  in  the  cyst  stage  as  a  meridional  structure.     The  neuromotor^ 
apparatus  consists  of  centresome,  nuclear  rhizoplast,  three  blepharoplast^ 


^ig^  A.—Chilo7nastix  mesnili  (Wenyon).  Normal  llagellate  viewed 
from  the  ventral  or  oral  side  and  showing  all  the  structures  of  the  body. 
X  6370. 

Fig^  B.— The  cyst  viewed  from  the  ventral  or  oral  side.     X  6370. 

cent.,  centrosome;  cent.k.,  central  karyosome  :  cyst.,  cyst  wall;  cyt., 
cytostome;  cyt.fl.,  cytostomal  fiagellum  or  undulating  membrane; 
iwf.rM^.,  intranuclear  rhizoplast ;  l.a.fl.,  left  anterior  liagella;  nuc., 
nucleus;  nuc.rhiz.,  nuclear  rhizoplast;  _2Jar.6.,  parabasal  body; 
parast,  parastyle ;  perist.f.,  peristomal  fibre;  prim.hleph.,  primary 
blepharoplast ;  r.a.fl.,  right  anterior  fiagellum  ;  S('c.6/ep/i.,  secondary 
blepharoplast ;  spir.gr.,  spiral  groove;  tert.bleph.,  tertiary  blepharo- 
plast ;  tr.rhiz.,  transverse  rhizoplast. 


ZOOLOGY    AND    BOTANY,    .MlCliOSCOPY,    ETC.  333 

and  connecting  rhizoplasts,  the  primary  giving  rise  to  two  fiagella,  the 
secondary  to  one  and  to  the  parastyle,  the  tertiary  to  the  parabasal,  the 
peristomal  fibril,  and  the  cytostomal  flagellnm  or  undulating  membrane. 
The  centroblepharoplast  complex  is  thus  subdivided  into  four  granules, 
the  centrosome  and  three  blepharoplasts  having  continuous  i-hizoplast 
connexions  with  the  central  karyosome  of  the  nucleus.  The  nucleus  is 
polarized  with  the  centrosome  anterior  and  the  spireme  forms  in  its 
longitudinal  axis.  Binary  fission  in  the  cyst  is  morphologically  longi- 
tudinal. The  blepharoplast-rhizoplast  chain  splits  lengthwise  at  mitosis, 
and  the  remainder  of  the  neuromotor  complex  appears  to  be  produced 
de  novo  by  outgrowths  from  the  blepharoplasts  prior  to  the  spireme 
stage.  The  .daughter  centrosomes  are  connected  by  a  paradesmose.  In 
mitosis  the  nuclear  membrane  remains  intact  and  its  constriction  is 
spatially  transverse.  The  daughter  nuclei  are  for  a  time  connected  by 
the  paradesmose,  but  lie  at  opposite  poles  of  the  cyst,  but  may  later 
change  their  position.  The  neuromotor  system  of  CMlomastix  is 
strikingly  similar  to  that  of  the  right  half  of  Giardia  in  symmetry  and 
in  its  constituent  elements.  The  two  daughter  individuals  are  each 
equivalent  to  the  right  half  of  Giardia.  The  bilateral  symmetry  of  the 
two-celled  Giardia  could  arise  only  by  a  complete  morphological  reversal 
from  the  sinistral  to  the  dextral  type  of  one  of  the  two  daughter 
schizonts  at  mitosis.  The  genus  Chilomastix  is  closely  related  in  the 
structure  to  the  bilateral  binucleate  Hexamitid^  and  may  be  their 
source.  J.  A.  T. 

Sensibility  of  Volvox  to  Light. — Henry  Laueens  and  Henry  D. 
Hooker,  Jun.  {Jouni.  Exper.  Zool.,  1920,  30,  345-68,  2  figs.).  A 
determination  of  the  relative  stimulating  effect  of  radiation  in  different 
parts  of  the  spectrum.  The  sensibility  of  Yolvox  to  radiation  of 
different  wave-lengths  but  of  equal  energy  (sensibility  to  radiation  at 
equal  energy)  was  investigated  by  two  methods :  (a)  the  relative 
duration  of  the  presentation  time,  and  {b)  the  relative  rate  of  locomotion 
and  precision  of  orientation.  Both  methods  showed  that  a  particular 
wave-length  has  the  highest  stimulating  value.  The  necessity  of  using 
an  equal-energy  spectrum  for  such  work  is  emphasized.  J.  A.  T. 

Double  Forms  of  an  Amicronucleate  Oxytricha. — J.  A.  Daw^son 
{Joiirn.  Exper.  Zool,  1920,  30,  129-57,  22  figs.).  In  cultures  of  an 
amicronucleate  race  of  Oxytricha  liymenostoma,  under  conditions  similar 
to  those  in  which  syngamy  usually  takes  place  in  hypotrichous  forms, 
there  is  a  strong  tendency  for  the  formation  of  double  animals,  or 
"twins,"  by  plastogamic  dorsal  fusion.  Twins  have  all  the  structures 
possessed  by  two  single  animals.  They  reproduce,  giving  {a)  two  pairs 
of  twins  exactly  similar  to  the  parent ;  {h)  from  the  anterior  portion,  a 
twin  which  pulls  apart  to  form  two  single  animals,  and  from  the  posterior 
portion,  a  typical  twin  ;  (c)  from  the  anterior  portion,  two  typical  single 
animals,  and  from  the  posterior  portion,  a  typical  twin.  Twins  may 
form  from  normal  strains,  from  descendants  of  single  animals  arising 
from  twins,  and  from  the  progeny  of  cannibal  animals.  In  stock  and 
mass  cultures  they  do  not  survive  in  competition  with  single  individuals  ;. 


334  SUMMARY    OF    CURRENT    RKSEARCHES    RELATING   TO 

they  require  favourable  environment.  A  pedigreed  strain  has  been  bred 
for  102  generations.  By  selection  a  striking  increase  in  the  percentage 
of  twins  may  be  produced.  The  division  rate  is  similar  to  that  of  normal 
single  animals.  As  pairing,  cannibalism,  and  twin-formation  occur 
among  animals  in  a  similar  physiological  condition,  it  is  believed  that  the 
three  phenomena  are  but  expressions  of  an  abortive  attempt  to  undergo 
syngamy,  abortive  probably  because  of  the  absence  of  idiochromatin 
morphologically  segregated  as  nuclei.  J.  A.  T- 

Life-History  of  Myxidium  gadi. — Jivoin  Georgevitch  {Arch. 
Zool.  Exper.,  1919,  58,  251-89,  3  pis.,  3  figs.).  Monosporic,  disporic,  and 
polysporic  forms  occur.  In  all  cases,  however,  the  scheme  of  the  life- 
history  is  the  same.  At  the  end  of  sporulation  a  syncarion  is  formed, 
and  this  unicellular  stage  (zygote  or  pansporoblast  resulting  from  the 
total  union  of  two  isogametes)  is  at  the  start  of  each  new  developmental 
cycle.  This  zygote  does  not  immediately  enter  upon  sporulation  :  it 
passes  through  several  generations  of  similar  schizonts  before  becoming 
sporont.  There  is  always  alternation  of  generations  between  schizogonic 
forms  and  sexual  sporogony.  Schizogony  is  marked  by  equal  cell- 
divisions  ;  in  sporogony  there  are  two  unequal  divisions  of  the  nucleus 
alongside  of  equal  divisions.  After  several  generations  of  schizogony,  the 
details  of  which  are  described,  the  schizonts  enter  into  sporogony.  If 
the  schizont  is  monosporic  or  disporic,  the  first  division  of  its  nucleus  is 
unequal,  unlike  the  subsequent  divisions.  If  it  is  polysporic  all  the 
divisions  are  equal.  The  diverse  phases  of  the  monosporic,  disporic, 
and  polysporic  operations  are  dealt  with,  all  of  them  leading  eventually 
to  a  zygote.     At  no  stage  are  these  parasites  intracellular.       J.  A.  T. 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  335 


BOTANY. 

GENERAL, 

Including"  the  Anatomy  and  Physiology  of  Seed  Plants. 

Cytology, 
Including"    Cell-Contents. 

Chromosomes  in  Zea  Mais — Y.  Kuwada  {Journ,  Coll.  Scl.  ToUo, 
1919,  39,  Art  10,  1-148,  2  pis.).  A  papei\dealiDg  with  the  number  and 
individuahty  of  the  chromosomes  in  Zea  Mais,  and  with  the  origin  of 
this  species.  The  author  finds  that  the  number  varies  from  ten  to 
twenty  ;  plants  which  may  be  regarded  as  the  ancestors  of  this  species, 
and  those  which  are  nearly  related,  also  usually  have  twenty  chromosomes 
in  the  cells  of  the  root-tips.  In  a  few  species  of  sugar-maize  the  number 
of  chromosomes  varies  with  the  different  species  ;  in  the  root-tips  ex- 
amined they  varied  between  twenty  and  twenty-four.  There  appears  to 
be  no  relation  between  the  number  of  chromosomes  and  the  chemical 
constitution  of  the  endosperm.  Comparative  examination  of  the  number, 
size  and  length  of  the  chromosomes  in  the  root-tip  proves  that  increase 
in  the  number  is  the  result  of  transverse  division  of  the  chromosomes. 
The  dissimilarity  in  these  respects  in  the  component  chromosomes  seems 
to  confirm  Collins's  opinion  that  Z.  Mais  is  a  hybrid  between  Euchlwna 
and  an  unknown  plant  belonging  to  the  Andropogoneas.  Three  kinds 
of  chromosomes  are  characteristic  of  the  species  :  — (1)  Long,  with  a 
tendency  to  divide  transversely,  derived  from  the  EiichJsena  ancestor  ; 
(2)  shorter,  with  no  such  tendency,  derived  from  the  Andropogon 
ancestor ;  (3)  chromosomes  found  in  certain  species  in  which  the 
transverse  division  has  become  a  fixed  hereditary  character.  The  chro- 
mosomes which  split  or  tend  to  spHt  are  dominant  to  those  which  do  not 
split,  but  the  dominance  is  an  unstable  factor.  The  different  combina- 
tions of  these  three  kinds  of  chromosomes  cause  a  variation  of  the 
number  within  certain  limits,  and  result  in  two  kinds  of  gametes,  one 
of  which  is  characterized  by  a  constant  number  of  chromosomes,  and 
another  in  which  the  number  is  variable.  The  size  of  the  nucleus 
and  of  the  cell  are  dependent  upon  the  size  of  the  chromosomes,  and 
conversely  the  chromosomes  themselves  vary  with  the  size  of  the  cell. 

S.G. 

Crystals  in  Australian  Timbers.— E.  T.  Baker  {Journ.  Proc. 
Roy.  Soc.  JV.S.  Wales,  1918,  51,  435-44,  9  pis.).  The  writer  has 
examined  specimens  of  timber  belonging  to  twenty-two  families,  and 
finds  that  fifteen  of  them  contained  crystals  in  the  secondary  wood. 
The  crystals  were  so  numerous  and  well-defined  that  it  was  possible  to 
determine  their  crystalline  system  without  any  special  preparation  or 
breaking  down  of  the  wood.  They  were  usually  contained  "  in  a  special- 
ized form  of  chambered  wood-parenchyma,  with  partitions  dividing  it 


330  SUMMARY    OF   CURRENT   RESEARCHES    RELATING   TO 

into  cells  of  about  equal  size  containing  as  a  rule  an  individual  crystal." 
In  one  specimen,  Mallotus  p/iiUppinensis,  the  raj-parenchyina  contained 
as  many  as  four  crystals  in  one  cell.  The  micro-sections  were  immersed 
in  strong  hydrofluoric  acid  without  any  effect  upon  the  crystals,  except 
in  the  case  of  Strychnos  arlorea,  where  they  occur  in  great  numbers  in 
special  long  pockets ;  in  this  case  the  greater  part  of  the  crystals  dis- 
appeared. In  Eucalyptus  pilularis  and  Tristania  conferta  the  "  grit " 
proved  to  be  silica.  The  author  finds  no  support  for  the  theory  that 
crystals  are  characteristic  of  certain  families  or  genera,  since  there  is 
great  uniformity  in  those  found  in  all  Australian  timbers,  the  only 
variation  being:  in  size  and  number.  S.  G. 


Structure    and   Development. 
Vegetative. 

Fibro-vascular  Formations  in  Monocotyledons. — A.  Dauphine 
{Ann.  Sci.  Natur.  Paris,  1917,  20,  309-14,  1  pL).  A  study  of  the 
development  of  the  "  supplementary "  fibro-vascular  'formations  in 
Draaena  indivisa  and  in  D.  Draco,  in  order  to  discover  their  relation- 
ship to  the  secondary  tissues  of  Dicotyledons.  The  author  refers  to  the 
marked  similarity  between  the  mode  of  secondary  thickening  in  the 
Chenopodiaceffi,  and  in  such  Monocotyledons  as  Dracdena.  He  compares 
with  the  latter  the  formation  of  successive  new  generative  layers  in  the 
beet,  showing  that  in  this  case  the  only  real  difference  is  that  in  Dracsena 
the  generative  layer  does  not  pass  between  the  bundles.  He  also  shows 
that  the  greater  part  of  the  elements  regarded  as  primary  in  Dicotyledons 
really  arise  from  secondary  tissues.  On  the  other  hand,  the  alternate 
primitive  phase  is  found  to  be  suppressed  in  Monocotyledons  owing  to 
acceleration  of  development ;  the  normal  generative  layer  has  such  a 
brief  duration  of  function  that  the  elements  beyond  the  primary  bundles 
are  forced  to  assume  the  functions  of  the  generative  layer.  Finally,  he 
finds  a  general  unity  of  plan  in  the  evolution  of  the  conducting  apparatus 
of  both  Monocotyledons  and  Dicotyledons,  which  bridges  over  the 
division  formerly  placed  between  the  two  groups.  S.  G. 

Growth  of  Trees.— A.  Mallock  {Froc.  Roy.  Soc,  Ser.  B.,  1919,  90, 
186-9!),  6  figs.,  4  diagrams)  has  adapted  the  method  employed  for 
observing  the  extension  of  cracks  in  buildings  to  finding  the  rate  of 
growth  of  timber-trees.  This  method  depends  upon  the  production  of 
bands  of  light,  as  a  consequence  of  the  illumination  of  sheets  or  prisms 
of  glass  meeting  at  definite  angles.  By  suitable  means  the  shifting 
of  ^th  of  a  band  can  be  noted,  and  this  corresponds  to  the  extension 
of  iiyT) 0 oiTofc^  of  an  inch  of  growth.  The  writer  made  observations  day 
and  night  on  four  trees  between  June  21  and  the  end  of  July,  and  found 
that  increase  of  girth  was  closely  related  to  temperature  ;  growth  was 
most  rapid  when  the  temperature  was  at  its  lowest.  Rain  produces 
great  effect,  even  a  shower  resulting  in  an  increase  of  girth.  The  eff'ect 
of  rain  may  be  partly  mechanical,  being  the  result  of  the  swelling  of 
the  bark,  but  the  checking  of  evaporation  from  the  leaves  appears  to  be 
an  important  factor.      In   these   experiments  there  was  no   means  of 


ZOOLOGY    AND    r>OTANY,    MICKOSCOPY,    E'lT.  337 

measuring  the  humidity  of  the  air,  \Yhich  would  seem  to  be  of  cousiderable 
importance  in  causing  increase  of  growth.  The  method  of  measurement 
appears  to  be  simple  and  satisfactory,  and  therefore  suitable  to  further 
observations  along  the  same  lines.  S.  G. 

CRYPTOGAMS. 

Pteridophyta. 

External  Morpholog'y  of  the  Stems  of  Calamites,  with  a  Revision 
of  the  British  Species  of  Calamophloios  and  Dictyocalamites  of  Upper 
Carboniferous  Ag^e. — ^E.  A.  Newell  Arber  and  F.  AV.  Lawfield 
{Journ.  Liiiii.  Soc,  1920,  44,  507-30,  3  pis.).  An  account  of  the 
external  features  of  Calamites  stems.  As  compared  with  fossilized  pith 
casts,  the  external  casts  or  impressions  are  rare  and  have  often  been 
confused  with  pith  casts.  Tiie  features  of  pith  casts  are  their  nodes  and 
their  ridged  and  grooved  internodes  ;  and  there  may  be  infranodal  canals 
and  branch  scars.  Submedullarv  casts  are  frequent,  representing  a 
region  within  the  secondary  wood  ;  they  are  characterized  by  very  broad 
ribs  (medullary  rays)  and  the  absence  of  infranodal  scars.  External 
casts  show  the  following  characters  :  nodes,  internodes  (smooth,  striated, 
etc.),  leaf  scars,  branch  scars,  root  scars,  which  are  discussed  in  detail. 
'An  attempt  is  made  to  correlate  the  specimens  of  British  Calamites  which. 
show  external  surfaces  with  their  corresponding  pith  casts.  And  this  is 
followed  by  a  systematic  revision  of  the  British  species  of  Calamophloios 
and  Didyocalamites.  A.  Gepp. 

Physiological  Anatomy  of  Xerophytic  Selaginellas.— J.  C.  Th. 
Uphof  {New  Phijtologisf,  1920,  19,  101-31,  12  figs.).  Six  p.c.  of  the 
species  of  Selaginella  are  xerophytic.  In  the  xerophytic  species  the 
dorsal  and  ventral  leaves  are  closely  approximated,  and  exhibit  a  striking 
similarity  of  size— a  matter  of  much  importance,  since  the  ventral  leaves 
contain  but  few  chloroplasts,  the  work  of  photosynthesis  devolving  upon 
the  comparatively  large  dorsal  leaves.  The  hygrophytic  species  on  the 
other  hand  have  their  leaves  spaced  out,  and  show  a  marked  difference 
in  size  between  the  dorsal  and  ventral  leaves.  There  are  three  groups 
of  xerophytic  Selaginellas  : — 1.  Plants  vdth  vertical  leaves  of  the  same 
shape  and  size  ;  the  apex  of  each  leaf  ends  in  a  long  awn  containing  no 
chloroplasts ;  the  anatomical  construction  is  sclerotic.  2.  Plants  with 
slender,  wiry,  trailing  stems,  spreading  over  the  ground  or  hanging  from 
rocks  and  sometimes  trees.  3.  Plants  with  a  spreading  habit,  often 
forming  a  flat,  dense  and  close  rosette,  rolling  into  a  cluster-ball  during 
drought.  In  the  first  group  the  erect  leaves  form  a  protection  against 
intense  insolation.  The  growing  points  of  the  stem  receive  the  sun's  rays 
directly,  but  the  apical  bundle  of  awns  reflects  the  light  entirely.  The 
epidermis,  hypodermis  and  outer  cortex  are  thick-walled  and  heavily 
impregnated  with  suberin.  The  elements  of  the  protoxylem  and 
metaxylem  are  much  narrower  than  in  hygrophytic  species.  Some 
species  are  petrophilous,  some  are  psammophilous.  The  second  group 
comprises  straggling  plants,  less  sclerotic  than  the  previous  group,  but 
very  thick-walled.     Some  have  a  red  pigment  in  very  exposed  stems  ; 

z 


338  SUMMARY    OF   CURRENT   RESEARCHES   RELATING   TO 

and  some  have  very  narrow  xylem  vessels,  the  water-supply  being  slight 
and  the  leaves  very  small.  The  mesophyll  is  well  developed  and  possesses 
large  air-spaces.  The  plants  of  the  third  group  are  very  well  fitted  for  a 
semi-arid  environment,  being  densely  ramified  and  curling  up  into  a 
close  cluster  ;  the  leaves  are  placed  horizontally  on  both  sides  of  the 
stem.  The  anatomical  construction  of  all  species  shows  a  rather  thin- 
walled  hypodermis  and  cortex  on  the  upper  (inner)  surface  of  the  stem, 
and  thick-walled  on  the  lower  (outer)  surface.  During  drought  the  thin- 
walled  tissue  loses  water  more  quickly  than  the  thick-walled  ;  hence  the 
plant  curls  inward.  Eeopening  is  due  to  quicker  absorption  of  water  by 
the  thin- walled  tissues  ;  and  the  plants  may  increase  in  weight  by 
42-54  p.c.  A  considerable  amount  of  oil  is  found  in  the  cells,  in  the 
form  of  small  drops  in  the  protoplasm  ;  these  oil-drops  unite  and  grow 
larger  during  desiccation,  and  possibly  form  a  protecting  film  around  the 
protoplasm.  Hygrophytic  species  produce  no  oil,  but  starch  :  and  it 
may  be  that  the  oil  is  a  reserve  food  in  the  xerophytic  species,  which 
produce  less  starch.  '  A.  G. 

Bulbils  of  Lycopodium  lucidulum. — R.  Wilson  Smith  {Bot. 
Gazette,  1920,  69,  426-37,  figs.).  A  description  of  the  bulbils  found 
on  certain  non-strobiliferous  species  of  Lycopodium.  The  author  con- 
cludes that  (1)  the  bulbil  is  not  the  homologue  of  a  branch,  since  it 
has  only  a  simple  vascular  strand  and  not  a  complex  exarch  radial 
system  :  nor  is  it  a  reduced  dichotomy,  nor  equivalent  to  the  bulblets 
of  Lilium  or  Allium.  (2)  It  is  not  the  homologue  of  a  sporangium, 
because  inter  alia  it  differs  in  receiving  a  prominent  vascular  strand. 
(8)  It  is  a  transformed  leaf,  retaining  the  position,  dorsiventrality,  and 
in  a  great  measure  the  vascular  strand  of  a  leaf  ;  it  may  perliaps  be 
homologized  with  an  early  undeveloped  bulblet  of  a  fern.  Further,  the 
author  describes  the  origin  and  vascular  bundles  of  the  branches,  leaves 
and  bulbils.  He  ascribes  the  accumulation  of  starch  in  the  bulbil  proper 
to  the  absence  of  phloem  in  the  narrow  neck  joining  it  to  the  base,  and  the 
detachment  of  the  ripe  bulbil  to  the  disorganization  of  the  xylem  walls 
in  this  region.  The  rate  of  growth  he  estimated  from  the  persistent 
bases  of  the  bulbils  ;  and  he  gives  some  observations  on  the  habits  of 
the  plant.  A.  G. 

Bryophyta. 

Cytology  of  Bryophyta.  I.  Spore-formation  in  Chiloscyphus  poly- 
anthus.— Rudolf  Florin  {Arkiv  for  Botanik,  1919,  15,  No.  16, 
1  pL).  An  account  of  spore-formation  in  Chiloscyphus  polya?ithus, 
describing  and  figuring  the  presynaptic  stage,  the  strepsinema,  diakinesis, 
metaphase,  anaphase,  etc.  A.  G. 

North  American  Species  of  Asterella. — Alexander  AY.  Evans 
(Contrib.  U.S.  Nat.  Herb.  Washington,  1920,  20,  247-812).  A 
monograph  of  the  North  American  members  of  this  difficult  genus,  the 
name  of  which  has  been  involved  in  much  change  and  confusion, 
Asterella  Pal.  de  Beauv.  was  created  in  1805-6  for  two  of  Linn^eus's 
species,  Marchantia  tenella  and  M.  hemisphserica.     These  have  long  been 


ZOOLOGY   AND    BOTANY,    MICKOSCOPY,    ETC.  339 

separated  under  t\YO  different  genera — as  Rehoulia  (originally  Rehouillia) 
hemisphaerica  Raddi  (1818),  and  i^/m&n«m  (originally  spelled ^//w&r^/'^V*) 
teneUa  Nees  (1820).  The  name  Asterella  tenella  should  be  restored  ; 
but  strangely  enough  S.  0.  Lindberg  (1868)  revived  Asterella  for 
A.  hemisphaenca,  while  Trevisan  (1874),  in  ignorance  of  this,  revived 
Asterella  for  A.  tenella  with  five  other  species,  but  soon  afterwards 
(1877)  adopted  Lindberg's  definition  of  Asterella  and  revived  Corda's 
Hypenantron  for  A.  tenella  and  its  alHes.  Lindberg  at  the  same  time 
also  changed  and  accepted  Trevisan's  definition  of  Asterella  for  A.  tenella 
and  its  allies.  Le  Jolis  (1895)  ridiculed  this  confusion  and  advocated 
the  suppression  of  Asterella.  But,  by  the  rules,  Asterella  must  stand, 
though  most  authors  have  preferred  to  use  Fimhriaria.  The  number  of 
species  in  the  genus  is  now  about  ninety-seven.  A  chapter  is  devoted 
to  the  morphological  features  of  the  plant.  Detailed  descriptions 
of  the  fifteen  Xorth  American  species  (three  are  new  to  science)  are  given, 
with  synonymy,  distribution,  and  critical  notes.  And  a  most  helpful  key 
to  the  species  is  provided.  A.  G. 

Three  South  American  Species  of  Asterella. — Alexander  W. 
Evans  {Bidl.  Torrey  Bot.  Cluh  1920,  46,  469-80).  Detailed  descrip- 
tions of  three  species  of  Asterella^  which  are  restricted  to  Chili,  Ecuador 
and  Bolivia  respectively  ;  six  other  species  have  been  recorded  for  the 
continent,  two  of  which  are  extensions  from  North  America.        A.  G-. 

Notes  on  North  American  HepaticsB.  VIII. — Alexander  W. 
Evans  {Bryologist,  1919,  22,  54-73,  1  pi.  and  figs.)-  Critical  notices  of 
ten  species  of  Hepaticae,  especially  Corsinia  coriandrlna  (Spreng.)  Lindb., 
Petalophyllum  Ralfsii  (Wils.)  Nees  &  Gottsche,  Nardia  fossomlronioides 
(Aust.)  Lind.,  A",  rubra  (Gottsche)  Evans,  N.  suMlifptica  Lindb.,  some 
of  which  are  discussed  at  considerable  length  and  figured.  A.  G. 

Notes  on  New  England  Hepaticse.  XV. — Alexander  W.  Evans 
{PJiodora,  1919,  21,  149-69,  1  pi.  and  figs.).  Nardia  hyalina  (Lyell) 
Carringt.,  N.  olscura  (a  new  species)  and  N.  olovata  (Nees)  Lindb.  are 
described  and  discussed  in  detail.  A.  G. 

New  Riccia  from  Peru. — Alexander  W.  Evans  {Torrey a,  1919, 
19,  85-8,  1  fig.).  Riccia  histriata,  a  new  species  collected  at  Santa  Ana, 
in  Peru,  by  0.  F.  Cook  and  G.  B.  Gilbert  in  1915,  is  characterized  by 
a  feature  not  known  elsewhere  in  Marchantiales — namely,  parallel  pairs 
of  thickening-bands  running  vertically  down  the  sides  of  the  columns  of 
cells  which  form  the  green  assimilative  tissue  of  the  thallus.         A.  G. 

Notes  on  North  American  Sphagnum.  VIII.— A.  LEPtOY 
Andrews  {Bryologist,  1919,  22,  45-9).  A  continuation  of  the  mono- 
graph of  the  section  Cuspidata,  containing  critical  notes  on  Sphagnum 
tenellum,  S.  cuspidatum  and  its  var.  Torreyi^  and  incidentally  on  some 
allied  species.  A.  G. 

Ecological  Succession  of  Mosses. — Aravilla  M.  Taylor  {Bot 
Gaz.,  1920,  69,  449-91,  2  figs.).     A  discussion  of  the  moss  ecology  of 

z  2 


340  SUMMAKV    OF    CUEKENT    RESEARCHES    RKLATING    TO 

the  Chicago  region,  under  two  headings — xerarch  and  hydrarch  succes- 
sions. In  Table  I.  is  shown  the  succession  of  the  fifteen  principal 
mosses  present  in  the  xerarch  series  of  the  sand  dunes,  through  the 
five  stages— cotton-wood,  pine,  transition  pine-oak,  oak,  beech-maple. 
Table  II.  represents  the  hvdrarch  succession  from  open  water  of  lagoons 
and  ponds,  through  the  stages — sedge  mat,  tamaracks,  swamp  forest,  to 
the  beech-maple  forest ;  and  here  twenty  mosses  are  concerned.  In  the 
successions  on  sand,  mosses  are  most  abundant  in  number  and  quantity 
in  the  pine  stage  and  decrease  in  and  after  the  oak  stage.  In  the 
hydrarch  successions  the  greatest  dominance  of  mosses  is  usually  in  the 
swamp  or  bog  forest  (tamaracks).  Mosses  are  important  pioneers  on 
bare  rock  surfaces,  and  continue  abundant  far  into  the  forest  association. 
They  are  of  the  greatest  value  from  an  economic  standpoint.  They  are 
soil-formers  and  provide  favourable  habitats  for  germination  of  higher 
plants.  They  assist  largely  in  forming  the  surface  mat  over  deep  lakes 
and  in  filling  up  shallow  waters.  They  may  help  to  build  up  tufa,  and 
to  make  floating  islands.  They  conserve  moisture  and  give  it  out 
slowly,  thus  checking  the  formation  of  disastrous  floods.  They  prevent 
erosion  of  clay  or  sand  surfaces.  A.  G. 

Hymen ostomum  in  North  America.  —  A.  LeRoy  x\xdrews 
{Bryologist,  1020,  23,  28-31).  A  discussion  of  the  delimitation  of  the 
genus.  There  is  a  perplexing  group  of  closely  related  species  which 
have  been  divided  among  the  genera  Astomum,  Hymenosiomum  and 
Weisia.  Alike  in  their  garaetophy tes  and  with  sporophy tes  representing 
a  very  close  gradation  of  forms,  these  plants  make  the  limitation  of 
species  and  genera  a  matter  of  debate.  Hymenostomum  rostellatwu  is 
as  good  an  Astomum  as  a  Hymenostomum.  After  citing  instances  of 
confusion,  natural  affinities,  attempted  revisions  of  genera,  he  proposes 
to  retain  the  name  Hympiiostomum  for  tbe  group,  the  type  being 
H.  microstomum  (Hedw.)  11.  Br.,  and  to  employ  three  sub-genera — 
Astomum^  Elihymenostomum,  Weisia,  which  normally  are  respectively 
cleistocarpous,  hymenostomous  and  peristomate.  A.  G. 

New  and  Interesting'  South  African  Mosses. — H.  X.  Dixon 
{Trans.  Roy.  Soc.  South  Africa,  1920,  8,  170-224,  2  pis.).  An  account 
of  a  large  number  of  mosses  from  South  Africa  collected  mainly  by 
H.  A.  Wager,  T.  K.  Sim,  J.  Henderson,  including  about  two  dozen 
species  new  to  science,  and  valuable  critical  notes  on  many  species  which 
required  illumination — e.g.  C'aj/ipijlojnis  inchangae,  the  specific  name  of 
which  has  l)een  rendered  by  various  authors  as  Inczangae,  Incrangae, 
Incrangse,  Imerangse.  It  is  shown  that  the  water  moss  Fissidens 
julianus  is  a  widely  distributed  species,  and  that  F.  Berterii,  F.  DiUenii 
(both  from  temperate  South  America),  /'.  capensis  and  F.  3IueJleri 
(Australia)  cannot  be  separated  from  it.  In  half  a  dozen  other  cases 
the  identity  of  Cape  species  with  previously  described  European  species 
is  demonstrated.  A.  G. 

Mosses  of  Madeira.— A  Luisier  {Broteria,  1010,  17,  28-6G,  1  pL). 
Continuation  of  an  historical  and  systematic  account  of  the  moss-flora  of 
Madeira,  with  some  critical  notes,  descriptions  and  a  few  figures.     A.  G. 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  o41 

Moss  Exchange  Club. —  Tirenty-fifth  Annual  Report.  (York  : 
Coultas  and  A'olaiis,  192(i,  255-66.)  A  list  of  the  British  and  foreign 
mosses  and  hepatics  collected  and  distributed  by  the  members  of  the 
club,  with  critical  notes  on  the  more  interesting  specimens.         A.  (t. 

Thallophyta. 
Algae. 

Auxospore-formation  of  Chsetoceros  debile  Cleve. — K.  Yexdo  and 
J.  Ikari  {Bot.  Mag.  Tokyo,  l'.)18,  32,  145-9, 1  pL).  Auxospore-forma- 
tion has  been  observed  in  about  20  out  of  the  160  genera  of  diatoms. 
It  has  been  previously  described  in  Chsetoceras  by  Schiitt  and  others, 
and  the  present  authors  give  a  detailed  account  of  the  process  in 
C.  (Mile,  which  they  had  the  chance  of  observing  on  a  free  scale  near 
Oshoro.  A.  Ct. 

Diatomaceous  Earth  of  Lompoc,  Santa  Barbara  Co.,  California. — 
X.  Yermoloff  {Geoloji.  Mag.,  1020,  57,271-7).  The  siliceous  remains 
in  the  fossil  deposit  of  Lompoc  belong  to  two  main  and  dominating 
groups  of  organisms,  Dictyochidie  and  Diatomaceae.  The  diatoms  are 
all  pelagic  and  nearly  all  discoid,  with  only  a  very  few  gonoid  forms. 
They  are  all  undoubtedly  northern  forms  ;  indeed,  very  similar  to  those 
usually  common  in  European  seas.  The  author  discusses  the  composition 
of  the  deposit  in  detail,  noting  the  presence  or  absence  of  certain  genera 
and  species.  The  predominating  genera  are  Euodia,  Coscinodiscus  and 
Thdlassionema,  together  with  the  silico-flagellate  Dictyocha,  and  these 
give  to  the  deposit  its  characteristic  facies.  Of  the  nine  groups  of 
Coscinodiscus  only  five  are  represented  in  Lompoc ;  the  constituent 
species  of  these  groups  are  analysed  and  discussed.  Finally,  an  enumera- 
tion is  given  of  all  the  species  recorded.  E.  S.  Gepp. 

Rare  Species  of  North  American  Diatomaceae. — C.  S.  Boyer  {Bull. 
Turr.  Bot.  Club,  1920,  47,  67-72,  1  pi.).  Descriptions  of  eleven  new 
species,  and  of  Xavicula  Attwoodii  Perag.,  which  is  here  figured  for  the 
first  time.  Abnormal  forms  of  Aulacodiscus  oregonus  are  discussed  and 
compared,  and  it  is  suggested  that  these  specimens  may  be  evidences  of 
the  formation  of  gonidia.  Numerous  valves  occur  in  rich  gatherings 
much  smaller  than  the  normal  valve  and  of  uniform  size,  equal  to  that 
of  the  partially  formed  valves  in  the  specimen  figured.  In  each  of  the 
specimens  examined  the  internal  finely  granular  plate  is  distinctly 
shown,  but  its  function  in  the  formation  of  new  valves  is  problematical. 

E.  S.  G. 

Fresh-water  Diatoms  from  Iceland.— Ernst  0strup  {The  Botany  of 
Iceland :  Copenhagen,  J.  Frimodt :  London  :  J.  Wheldon,  1920,  2,  Part  I., 
1-98,  5  pis.).  A  posthumous  paper  based  upon  572  samples  of  diatom 
material  collected  by  various  hands  in  several  parts  of  Iceland.  The 
work  is  divided  into  two  parts  : — 1.  A.  systematic  list  containing  refer- 
ences to  literature  and  descriptions  of  57  new  species  and  13  varieties, 
which  are  all  figured  in  the  plates.     2.  An  alphabetical  list  of  the  468 


342  SUMMARY    OF  CUKRENT    RE.SEARUHP:8    RELATING   TO 

forms,  with  tables  showiiif^  their  distribution  in  Iceland  itself  and  their 
wider  distribution  in  the  Arctic  region  and  in  the  five  continents  of  the 
world.  As  the  number  of  forms  previously  recorded  for  the  island  was 
131,  the  result  of  the  author's  work  is  to  make  the  total  about  3|  times 
as  large,  xlppended  is  a  list  of  the  forms  found  in  hot  springs,  and 
mostly  in  the  living  state;  these  represent  178  species  and  varieties,  and 
31  genera.  A.  G. 

Photosynthesis  in  Fresh-water  Algae. — B.  Mooee  and  T.  A. 
Webstee  {Proc.  Roy.  Soc,  Ser.  B.,  1920,  91,  201-15).  A  discussion 
of  the  fixation  of  both  carbon  and  nitrogen  from  the  atmosphere  by 
green  plant  cells,  to  form  organic  tissue.  Experiments  show  that  in  the 
absence  of  all  sources  of  nitrogen,  save  the  atmosphere,  unicellular  algse 
can,  in  presence  of  abundant  COg,  fix  N",  grow  and  form  proteins  ;  but 
the  rate  of  fixation  and  growth  is  much  accelerated  if  nitrites  or  oxides 
of  nitrogen  are  available.  Such  oxides  of  nitrogen  occur  normally  in 
pure  country  air,  especially  in  spring  and  summer.  Formaldehyde  and 
methylic  alcohol — products  of  photosynthesis — are  very  poisonous  to 
the  green  cell  ;  but  when  extremely  diluted  they  are  found,  in  the 
absence  of  COg,  to  be  nutritious  to  the  cell.  A.  G. 

Review  of  the  Genus  Chlorochytrium. — B.  M.  Bristol  {Joiirn. 
Linn.  Soc,  1020, 45, 1-28,  3  pis.,  1  hg.  in  text).  In  an  historical  intro- 
duction the  author  recalls  the  work  of  Prof.  G.  S.  West  in  submerging 
six  other  genera  into  Chlorochytrium,  and  his  suggestion  that  similar 
drastic  revision  was  needed  for  the  species  of  the  genus.  She  shows  that 
certain  characters  used  for  the  limitation  of  the  species  are  too  variable 
to  have  specific  value.  These  are  the  shapes  of  the  cells,  the  nature  and 
extent  of  the  thickenings  of  the  cell-walls,  the  form  and  size  of  the 
chromatophore,  and  the  fusion  or  asexual  development  of  the  zoogonidia. 
Thus  she  has  been  able  to  reduce  the  number  of  species  to  ten,  and  of 
each  of  these  she  gives  a  full  and  critical  account,  with  varieties.  This 
is  followed  by  a  summary  of  the  species  wdth  synonyms,  references  to 
literature,  diagnosis  and  habitat.  Three  doubtful  species  are  shortly 
described,  w'hich  in  the  absence  of  authentic  material  are  impossible  to 
identify.  Finally,  a  note  is  added  on  C.  glwophilum  Bohlin,  which  is 
probably  only  a  form  of  G.  Facclolase  Bristol.  The  plates  represent 
preparations  of  C.  Lemnse  and  C\  paradoxum.  E.  S.  G. 

Studies  on  the  Chloroplasts  of  Desmids.  IV.— Nellie  Carter 
{Annah  of  Botany,  1920,  34,  303-20,  3  pis.).  The  first  part  treats  of 
the  chloroplasts  of  Staurastrum.  Mostly  these  are  axile  ;  only  in 
S.  tumidum  were  they  found  to  be  parietal.  ]\Iany  of  the  smaller 
species  have  a  simple  axile  chloroplast  consisting  of  a  central  axis  which 
contains  a  single  pyrenoid  and  a  ])ilol)ed  mass  projecting  into  each  angle 
of  the  semi-cell.  Amongst  the  larger  species  the  general  form  of  the 
chromatophoi-e  is  often  quite  similar  to  that  of  the  smaller  ones,  but 
there  are  variations  in  the  number  of  plates  in  each  angle  and  also  in 
the  number  and  arrangement  of  the  pyrenoids.  Most  of  the  species 
examined  had  one  point  of  pyrenoid  formation  in  the  centre  of  the 


ZOOLOGY   AND    BOTANY,    MICROSCOPY,    ETC.  343 

semi-cell,  but  in  a  few  species  the  pyrenoids  occur  either  in  the  angles 
only  or  else  in  addition  to  those  in  the  centre.  S.  brasiliense  and 
S.  graude  differ  from  most  of  the  other  species  examined  in  their  very 
numerous  pyrenoids.  In  S.  grcmde  also  some  individuals  show  a 
tendency  to  the  parietal  disposition  of  the  chloroplast  by  the  total 
disappearance  of  the  axis  in  the  centre  of  the  semi-cell,  leaving  the 
peripheral  lobes  of  the  chloroplast  isolated. 

The  second  part  of  the  paper  discusses  the  behaviour  of  the  chloro- 
plasts  durin.o-  cell-division.  Those  of  Xetrium  and  Cylindrocystis 
probably  behave  much  as  do  those  of  Closterium,  as  described  by 
Lutman.  In  all  the  Placoderm  Desmids  examined  the  process  of  cell- 
division  is  rather  different  from  that  of  the  Saccodermae.  The  nucleus 
of  the  cell  completes  its  division,  and  the  two  new  colourless  semi-cells 
can  readily  be  distinguished  before  there  are  any  visible  changes  in 
the  chromatophores.  Tiie  latter  then  ra23idly  stream  through  the 
isthmus  from  the  old  semi-cell  into  the  new  one,  so  that  by  the  time  it 
is  fully  formed  it  is  usually  uniformly  green.  The  process  is  completed 
by  the  division  of  the  chloroplasts  at  the  isthmus  of  each  individual. 
In  those  species  in  which  the  points  at  which  pyrenoids  may  occur  are 
fixed  the  young  semi-cell  is  provided  with  a  corresponding  number  of 
pyrenoids  by  the  budding  of  those  already  existing  in  the  old  semi-cell. 
Where  the  pyrenoids  are  indefinite  in  number  and  scattered,  a  number 
of  these  enter  new  semi-cells  together  with  the  budding  chromatophore. 
A  striking  feature  of  the  ingrowth  of  the  chloroplast  in  many  species  is 
the  rapidity  with  which  the  cell-wall  of  the  young  semi-cell  is  completely 
mantled  by  the  chloroplast,  often  at  the  expense  of  the  more  central 
parts  of  the  semi-cell.  This  phenomenon  is  responsible  for  the  forma- 
tion of  parietal  chloroplasts  in  isolated  specimens  of  species  which 
normally  possess  axile  ones,  and  probably  also  for  their  original  produc- 
tion in  species  in  which  they  have  been  permanently  acquired.    A.  G. 

Fresh-water  Algae  from  Santo  Paulo. — 0.  Borge  {Ark.  Botanilc, 
1919,  15,  Xo.  13,  1-108,  8  pis.).  The  algse  here  recorded  were 
collected  by  Dr.  Lof gren  and  sent  to  Prof.  Nordstedt,  who  has  published 
a  certain  number  of  them  in  Wittrock  and  Nordstedt's  "  Exsiccatse." 
Most  of  the  Oedogoniacese  have  been  published  in  Hirn's  monograph. 
The  collection  was  afterwards  handed  over  to  the  author  for  further 
investigation,  and  the  publication  of  figures.  Nearly  400  species  and 
numerous  varieties  are  enumerated  ;  and  27  new  species  and  several 
varieties  are  described  in  the  present  paper.  E.  S.  G. 


Sub- Antarctic  and  Antarctic  Marine  Algse.  III.  Chlorophyceae. — 
D.  E.  Hylmo  (Wisseiisch.  Ergebn.  Sckicedisck.  Sildpolarexped.,  1901-3, 
Band  IV,  hef.  16,  Stockholm.  1919,  20  pp.,  36  figs.).  A  report  of  the 
marine  Chlorophycese  collected  by  Dr.  Skottsberg  on  the  coasts  of 
Tierra  del  Fuego,  Graham's  Land,  S.  Georgia,  and  the  Falklands.  To 
each  species  is  appended  a  list  of  synonymy  and  bibliography, 
geographical  distribution,  and  critical  observations.  Nineteen  species  are 
included,  one,  Bryopsis  magellanica,  being  new.  E.  S.  G. 


344  SUMMARY    OF    CUKKENT    1IESKAKCHE8    EELATI^'G    TO 

Contribution  to  the  Study  of  the  Verticillate  Siphonese  of  the 
Limestone  of  Villanova-Mondovi.— A3lu.ia  Baretti  (Att.  Soc.  Ital. 
Sci.  Sat.  e  Mus.  Civ.  St.  Xai.  Milam,  1919,  58,  216-3G,  figs,  in  text-). 
A  determiiiatioii  of  the  verticillate  Siphonea^  from  the  triassic  limestone 
of  Yillanova  according  to  Pia's  classification.  Ten  species  are  recorded, 
representing  three  genera — Diplopora.,  Kantia,  Teutloporella.  Kantia 
monreyaJense  and  K.  Brunoi  are  described  as  new  species.        E.  8.  C4. 

Researches  on  the  Laminarias  of  the  French  Coasts.— C.  SauvaCxEau 
{Mem.  Acad.  Sci.  Paris,  191.S,  56,  240,  85  ligs.  in  text).  An 
exhaustive  account,  with  illustrations,  of  all  the  work  on  the  subject 
carried  out  by  the  author.  In  an  introduction,  after  a  short  summary 
of  the  work  of  other  authors  and  their  conclusions,  the  results  hitherto 
unpublished  of  the  author's  cultures  of  Chorda  Fihim  are  briefly  described. 
The  embryospore  germinates,  and  the  resultino-  plantlet  is  entirely 
comparable  Avith  that  described  for  Laminaria,  the  swollen  distal  cells 
representing  a  prothallus.  After  fifteen  days  two  or  three  cells  were 
observed,  which,  not  being  of  uniform  size,  were  presumably  male  and 
female.  Then  growth  slackened  off,  the  prothalli  developed  septa  and 
branched,  producing  short  filaments  of  torulose  or  irregular  gloljular 
cells.  Neither  plantlets  (with  one  exception)  nor  sexual  organs  were 
obtained.  The  author  suggests  that  the  prothallia  of  C.  FUinn  at 
Eoscoff,  at  least  under  certain  conditions,  may  be  apogamous,  and  that 
the  plantlets  arise  direct  at  the  expense  of  a  cell  of  the  prothallus.  An 
examination  of  Dictyosiplion  fmnicidaceus  produced  more  complete 
results.  Alternation  of  generations  takes  place,  but  of  a  quite  different 
character  from  that  of  Laminaria.  The  zoospores  produce  a  prothallus 
bearing  plurilocular  organs,  the  motile  elements  of  Avhich  are  isogamous 
gametes  ;  the  zygotes,  or  the  parthenogenetic  gametes,  give  rise  to  a 
protonema  on  which  appear  the  plantlets  of  Uictf/osiphou.  The  alga 
known  under  this  name  is  merely  the  sporophyte  of  the  entire  individual. 
The  two  types  respectively  of  Laminaria  and  Diciijosiphon  re}»resent 
doubtless  the  mode  of  reproduction  followed  by  a  number  of  other 
Pha3ophycea3  ;  but  a  difficulty  still  remains  in  explaining  the  seasonal 
existence  of  certain  epiphytes  which  ai)pear  suddenly  and  abundantly, 
grow  rapidly,  and  disappear  after  fructification.  The  reproductive 
elements  which  they  disseminate  cannot  be  those  wliich  germinate  the 
following  season,  especially  when  the  host  plant  itself  is  ephemeral.  An 
instance  of  this  is  Litosiphon  pusiUus  on  Chorda  Filum.  AVhat  is  the 
intermediate  stage  of  this  and  many  similar  species  ?  Other  points  of 
interest  in  the  introduction  must  be  studied  in  the  original  work.  The 
first  part  of  the  memoir  is  devoted  to  Saccorhiza  bulboaa  : — 1.  Geogra- 
phical distribution.  2.  Biology  {S.  bidbosa  is  an  annual),  o.  Develop- 
ment :  sporangia  and  zoosjiores,  male  and  female  prothallia,  etc. 
4.  Nature  and  origin  of  the  tissues  of  the  young  plant.  The  remaining 
parts  treat  respectively  of  Laminaria  Hexic.aulis,  1j.  IjejoUsii,  L.  Cloustanii, 
L.  saccharina,  and  Alaria  escu.lenta  ;  two  chapters,  biology  and  develop- 
ment, Ijeing  devoted  to  each.  A  bil)liograp]iy  and  synopsis  of  contents 
complete  this  important  memoir.  E.  S.  (1. 


ZOULUGY    AND    BOTANY,    MICKOSCUPY,    Ki  C.  345 

Dissemination  and  Naturalization  of  Certain  Marine  Algae. — 
C.  Sauvageau  {Bull.  Inst.  Oceanoijr.  Fomln.  Prince  de  Monaco,  1918, 
No.  34-2,  '2d)  pp.).  A  discussion  of  the  gradually  enlarged  distribution  of 
certain  well-known  species,  their  means  of  transport,  and  the  difficulties 
thej  encounter.  The  species  discussed  are  Gijstoselra  (jranulata,  Alarkt 
esculenta,  which  are  probably  drift-weed,  and  Golpomenia  siniwsa, 
Lammaria  Lejolisii  and  Bonnemaisonia  hamifera,  which  are  chance 
emiorants  and  probably  transported  by  some  ship.  The  invasion  of 
Golpomenia  sinuom  is  likened  to  that  of  Elodea  canadensis  in  the 
mischief  they  both  cause.  Certain  forms,  Himanthalia  lorea^  Gystoseira 
concatenata  and  Sarqassum  vidgare  appear  unable  to  acclimatize  them- 
selves to  the  conditions  in  the  Gulf  of  (lascony,  though  frequently 
brought  there.  E.  S.  (x. 

Notes  on  Algae  New  to  Japan.— Kichisaburo  Yendo  {Bot.  Mag. 
Tokyo,  IDls,  32,  65-<sl,  175-87).  Concluding  chapters.  The  number  of 
alg^  treated  in  this  series  of  papers  amounts  to  178  species,  varieties  and 
forms  ;  and  the  author  suspects  that  several  more  epiphytic  and  parasitic 
species  have  yet  to  be  added  to  the  list.  In  the  final  chapter  he 
discusses  questions  of  synonymy  and  distribution.  It  is  interesting  to 
find  that  'dH  marine  alg^  are  common  to  Japan  and  Europe  ;  also  that, 
by  careful  study  of  the  living  plants,  39  species  of  Sargassum  have  been 
reduced  to  19.  An  index  to  the  genera  and  species  wiiich  are  discussed 
in  the  scattered  series  of  papers  is  provided.  A.  0-. 


Fungi. 

Blepharospora  terrestris  (Sherb.)  Peyr.  —  B.  Peyronel  {Atti 
Real.  Accad.  dei  Lincei,  1920,  ser.  5,  29,  194-7).  The  fungus  here 
described  was  found  to  be  causing  serious  damage  to  plants  of  Lrqnnus 
alb  us.  The  author  found  that  the  roots  of  the  plants  were  specially 
affected,  and  in  the  cells  he  found  the  characteristic  phycomycetous 
hypbffi  and  a  few  oospores.  He  was  also  able  to  observe  the  formation 
of  zoospores  and  later  their  germination.  The  fungus  was  placed  in 
Phytophthora  by  Sherbakoff,  but,  according  to  Peyronel,  its  place  is  in 
the  above  genus.  A.  Lorrain  Smith. 

Large  Pyrenomycetes.  II. — C.  G.  Lloyd  {Gincinnati,  Oltio,  1919, 
17-32,  23  figs.).  Lloyd  gives  a  synoptic  key  to  seventeen  genera  of 
this  group.  He  selects  a  few  of  these  for  special  note  :  Kretzschmaria^ 
a  tropical  genus,  with  stems  bearing  heads  that  become  confluent  ; 
Daldinia,  of  which  only  one  species,  D.  concentrica,  is  common.  A  new 
genus,  Garnostroma,  has  been  established  by  Lloyd  ;  the  species  G.  thyrsus 
has  a  stem  6-8  in.  long  with  a  conical  fleshy  stroma  at  the  apex  ; 
Penzigia,  Sarcoxylon  and  Olaziella,  all  rare  genera,  are  figured  and 
discussed.  A.  L.  S. 

Life-History  of  Ascobolus  magnificus. — B.  0.  Dodge  {Mycologia, 
1920,  12,  115-34,  2  pis.,  28  figs.).  This  fungus,  originally  from  Porto 
Rico,  has  been  kept  in  culture  by  the  author  for  several  years.     He 


346  SUMMARY    OF    CURRKNT    RESEARCHES    RELATING   TO 

discusses  (1)  the  development  of  the  primordia — ascogonia  and  antheridia, 
(2)  the  asexual  or  Papulospora  stage,  (3)  intrahyphal  mycelium,  and 
(4)  the  necessity  of  two  strains  in  sexual  reproduction.  He  finds  that 
both  ascogonia  and  antheridia  are  erect  structures  (air  being  evidently 
necessary  at  the  origin  of  the  ascocarps),  and  that  the  ends  of  the  two 
bodies  fuse.  The  ascogenous  cell  then  begins  to  enlarge  and  to  produce 
ascogenous  hypha3.  A  description  of  the  l)ulbils  or  Papalosjwra  stage 
follows,  and  the  appearance  of  hypha3  within  older  hyphas  of  the  same 
species.  In  spore  cultures  of  one  strain  there  is  no  fertilization,  only 
ascog(;nia  or  antheridia  arise  ;  but  sexual  reproduction  occurs  in  cultures 
containing  two  strains  properly  chosen.  Difficulty  was  experienced  in 
obtaining  the  germination  of  any  of  the  spores.  A.  L.  S. 

Another  New  Truffle.— W.  A.  Murrill  {Mycologia,  1920,  12, 
157-8,  1  fig.).  The  new  species,  Tuher  Shearii  Hark.,  was  collected  and 
described  by  Harkness  before  his  death  in  1899.  It  differs  from  allied 
species  in  the  markings  on  the  large  spores.  A.  L.  S. 

Mycotorula  turbidans  Will.— H.  Will  and  F.  0.  Landtblom 
{Zeitschr.  Oes.  Bramv.,  1919,  42,  367-70;  see  also  Journ.  Inst.  Breiv.^ 
1920,  26,  261-2).  The  new  Torula  produces  turbidity  in  beer.  Such 
Toriilse  were  rare  before  the  war,  but  the  writers  suggest  that  the  wort 
being  weak  allows  the  development  of  alien  organisms.  The  one 
described  appears  to  thrive  well  in  competition  with  the  normal  beer 
yeast.  As  the  beer  matures  the  cloudiness  disappears,  as  the  flocks,  at  a 
certain  stage  of  development,  fall  to  the  bottom  of  the  storage  vessel. 
Mycotorula  is  described,  and  the  results  obtained  in  cultures,  etc.,  are 
given.  A.  L.  S. 

Gloeosporium  Tremulse  and  Gloeosporium  Populi-albae. — A.  van 
LuYK  {Ann,  Myrol.,  1919,  17,  110-3,  1  fig.).  The  author  considers 
that  the  two  species  are  identical.  He  finds  a  curious  attachment  between 
the  spores  whereby  chains  are  formed  by  lateral  bridges.  Similar 
bridging  connexions  are  the  characteristic  feature  of  Titseospora  Bubak, 
but  as  the  spores  in  the  above  plants  are  simple  a  new  genus  is  formed, 
Tiiseosporina.  A.  L.  S. 

Uredinea;  with  Swelling  Spore-membranes.— H.  and  P.  Sydow 
{Ann.  MycoL,  1919;  17,  101-7).  The  authors  have  discussed  some 
unusual  forms.  Two  species  from  Paraguay  and  from  Ceylon  classified 
as  Uredo  forms  have  now  been  determined  as  teleutospore  stages.  They 
are  distinguished  by  the  swollen  walls  of  the  spores  covered  with  pro- 
jections ;  the  spores  are  one-celled  and  of  rather  large  size.  The 
authors  place  them  in  a  new  genus,  Gtenodernia.  A  discussion  follows 
on  the  method  of  distinguishing  Uromyces  and  Fuccinia.  In  both  these 
genera  are  found  forms  with  swollen  walls  and  with  a  large  number  of 
germinating  pores.  Sydow  proposes  two  genera  to  include  these — 
Diclilamys  for  those  belonging  to  Pmcinia,  and  Haplopyxis  for  the 
Uromyces  forms.  Still  another  genus  is  established,  Trochodium,  in 
which  the  teleutospores  are  one-celled,  with  swollen  furrowed  walls  and 
with  one  germ  pore.  A.  L.  S. 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  347 

Puccinia  Malvaceariim  and  the  Mycoplasm  Theory. — M.A.Bailey 

{Ann.  Jjot.,  1020,  34,  173-200).  The  ^Yriter^s  aim  was  to  test  Eriksson's 
repeated  statement  that  rust  persisted  in  plants  as  a  mycoplasm  in  the 
seed.  He  grew  different  series  of  hollyhocks  from  seed — a  certain  number 
of  plants  in  the  open,  others  in  enclosed  globes  protected  from  infection. 
All  the  plants  in  the  open  became  infested  with  hollyhock  rust ;  those 
in  the  globes  were  free  from  disease  until  finally  they  were  sprayed  with 
rust  spores.  An  account  of  these  experiments  is  given  and  the  results 
tabulated  as  regards  the  various  plants.  All  disease  was  proved  to  arise 
from  external  infection  and  in  no  case  to  come  spontaneously  from  a 
mycoplasm  in  the  cells.  A.  L.  S. 

Heteroccism  and  Specialization  in  Puccinia  Caricis. — Jakob 
Eriksson  (Eev.  Gen.  Bot.,  1920,  32,  15-8).  By  a  series  of  inoculation 
experiments  Eriksson  has  proved  that  Puccinia  Caricis  is  a  collective 
species  and  includes  a  number  of  biologic  forms,  and  several  different 
forms  may  be  found  on  the  same  species  of  Car  ex  and  the  same  species 
of  Bibes,  the  alternate  host.  A.  L.  S. 

Facultative  Heteroccism  in  Peridermium  cerebrum  and  Peri- 
dermium  Harknessii.— E.  P.  Meinecke  {Phytopathology,  1920,  10, 
279-97).  Meinecke  distinguishes  sharply  between  the  two  Peridermiiun 
species.  The  last-mentioned  is  now  confined  to  the  gall  forms  on 
mountain  pines,  and  produces  uredinia  and  teleutospores  on  Scrophu- 
lariacea?.  Peridermivm  cerebrum  forms  galls  on  pines  of  the  Pacific 
coast ;  the  alternate  hosts  are  Quercus  spp.  A.  L.  S. 

Puccinia  graminis  on  Berberis  canadensis. — E.  C.  Stakman  and 
L.  J.  Krakova  {Phytopatholoyy,  1920,  10,  305-6).  A  research  was 
undertaken  to  determine  if  Berberis  canadensis  would  prove  to  be  an 
alternate  ho&t  to  Puccinia  graminis.  The  workers  found  that  the  Berberis 
in  question  was  badly  rusted  and  that  the  rust  spread  to  wheat.  They 
recommend  the  eradication  of  the  bushes  which  are  especially  abundant 
on  limestone  formations.  A.  L.  S. 

^cidial  Form  of  Uromyces  Genistse-tinctoriae. — P.  Dietel  {Ann. 
Mycoh,  1919,  17,  108-9).  The  a^cidial  form  of  this  rust  develops 
on  Euphorbise.  The  author  proved  this  by  inoculation  experiments  ; 
he  describes  the  type  of  deformation  on  the  Euphorbia  plants  caused 
by  the  fungus.  A.  L.  S. 

New  or  Noteworthy  North  American  Ustilag-inales.  — ■  H.  S. 
Jackson  {Jlycoloyia,  1920,  12,  149-56).  The  writer  reports  for  the 
first  time  in  North  America  the  bunt  of  rye,  TiUetia  Secalis  ;  it  had  been 
collected  in  1892  by  L.  M.  Underwood  at  Syracuse,  New  York.  A  new 
species,  Crocystis  Trillii,  on  Trillium  chloropetalum  forms  conspicuous 
sori  on  the  leaves.  Another  new  to  America  is  Sorosporium  Junci,  two 
collections  of  which  were  made  on  Juncus  bufonius  in  Oregon. 

A.  L.  S. 

Biology  of  Fomes  applanatus. — J.  H.  White  {Trans.  Roy.  Canad. 
Inst.,  1920,  12,  133-74,  2  figs.,  6  pis.).     Fomes  applanatus  has  been 


o48  SU.MMAliY    OF    Cli'KRKNT    KKSIOAKCH  KS    KELATINU    TO 

proved  to  be  a  wound  parasite  :  it  is  very  common  and  very  destructive  ; 
it  attacks  practically  all  deciduous  trees  as  well  as  conifers,  both  livintr 
and  dead.  From  the  mature  fungus  there  is  an  enormous  spore 
discharge,  but  the  spc»res  do  not  retain  viability  for  more  than  six  and  a 
half  months.  Cultures  were  made  on  wood,  and  the  effect  produced  by 
the  growth  of  the  fungus  was  carefully  noted.  Wood  I'otted  by  this 
Forms  shows  a  mottled  appearance  ;  this  is  due  to  the  destruction  of 
the  tissues  at  certain  points  and  the  formation  of  pockets  filled  with 
mycelium.  In  the  later  stages  of  decay  the  fungus  was  accompanied  by 
bacteria  and  other  fungi.  On  living  trees  the  fungus  was  observed  to 
have  travelled  upward  in  the  heurt  wood  and  outward  through  the 
sapwood.     It  is  often  quickly  destrtictive.  A.  L.  S. 

Polyporaceae  of  Bengal.  Part  III.— S.  R.  Bose  {1M\.  Garni.  Med. 
Coll.  Belf/achia,  1920,  1,  1-5,  7  pis.).  The  author  records  twelve 
different  species  of  Poria,  Tramdes,  Fomes^  etc.  He  gives  full  descrip- 
tions, habitat,  etc.     K\\  of  those  listed  grew  on  dead  wood.     A.  L.  8. 

Mycological  Notes  for  1919. — L.  0.  Overholts  {Mycoloi/ia,  1020, 
12,  1:35-42,  2  pis.).  Tlie  author  comments  on  the  abundant  growth 
of  fungi  in  central  Pennsylvania  during  1919.  Many  species  have  been 
added  to  recorded  lists,  some  of  them  of  rare  occurrence.  It  is  on 
some  of  these  that  the  notes  aje  based  : — Clavaria  ornatipes,  with  brown 
hairs  on  the  stem  ;  Merulius  aureus^  a  rare  species  on  pine  ;  MucroneUa 
Ulmi^  a  rare  species  of  a  rare  genus  with  short  awl-shaped  teeth  ; 
Treniellodon  ueJaUnosuni  and  others.  A.  L.  S. 

Mycological  Notes.  I.— F.  Petrak  {Ann.  MycoL,  1919, 17, 59-100). 
The  author  discusses  a  number  of  fungi  (^microscopic)  already  known, 
both  of  Fungi  Imperfecti  and  of  Pyrenomycetes.  He  has  also  established 
for  both  grotips  several  new  genera  : — KeissUriana  (near  to  Dotltiora)^ 
Cutoplacoxphseria^  Psevdopleospora^  Xeolceisslen'a,  Ghaetoct/tostronia,  BJenn- 
oriopsis,  Macnidiaportlie^  and  PJiseodiaporthe.  Most  of  the  genera  are 
Pyrenomycetes.  Ghsetocytostroma  and  BJennoriopsis  belong  to  Fungi 
Impurfecti.  A.  L.  S. 

Mycological  Notes. — C.  G.  Lloyd  (Gincinmdi,  Ohio,  1919,  2s.  60, 
S(i2-7(i,  :)4  figs.).  The  present  notes  are  mainly  concerned  with  the 
genus  Fterida,  rare  in  this  country  and  in  North  America,  but  more 
common  in  the  tropics.  Lloyd  figures  and  describes  all  the  known 
species.  He  then  discusses  a  numbei*  of  tremellaceous  plants,  TremeUa, 
AurmdcD'ia,  Exldia^  etc.  A.  Ij.  S. 

Index  of  the  Mycological  Writings  of  C.  G.  Lloyd.—  Ginn'nnati^ 
Ohio,  1910-9,  5,  1-24,  1  pi.).  A  subject  index  of  the  papers  contributed 
by  Lloyd  to  mycological  literature.  A  portrait  of  the  author  is  pub- 
lished. A.  L.  S. 

Mycological  Fragments. — Franz  v.  Hohnel  {Ann.  Myrol.,  1919, 
17,  114-38).  The  author  publishes  criticisms  on  a  number  of  estal)lished 
species.  He  records  the  finding  of  Tricholoma  tenuiceps  Cke.  &  Mass. 
in  Vienna  woods,  the  first  time  it  has  been  found  out  of  England  so  far 


ZOOLOGY    AND    BOTANY,    MICROSCOPY,    ETC.  3^1:9 

as  known.  MeJanopsameUa,  a  now  genus  of  Melanommeae,  is  founded 
on  EriospJideria  insequaJis  Grove  ;  the  conidialforni  is  Gonytrichum.  He 
finds  that  the  genus  Fchnsias  is  synonymous  with  Fracchisea.  Several 
new  species  are  described.  A.  L.  S. 

Amount  of  Copper  required  for  the  Control  of  Phytophthora 
infestans.— 0.  Butler  {riiytopathology,  1020,  16,  298-804).  The 
author  records  results  arrived  at  from  spraying  experiments  carried  out 
in  1911>,  a  season  very  favourable  to  the  spread  of  the  disease.  The 
amount  of  copper  necessary  per  acre  per  annum  Kes  between  twenty-four 
and  twenty-six  pounds.  A.  L.  S. 

The  Skin  Spot  Disease  of  Potato  Tubers.— (t/ow/v?.  A(jric.,  11)20, 
26,  1245-50,  1  pi.).  The  paper  is  an  abridged  and  modified  version  of 
a  report  of  work  done  by  Miss  M.  N.  Owen  on  the  disease,  and  published 
in  the  Kew  Bull.,  X.  8,  1919.  It  is  a  disease  that  develops  in  storage, 
but  it  is  not  yet  known  whether  infection  takes  place  in  the  soil  or 
during  storage.  The  fungus,  at  first  considered  to  be  Spkaria  Solani, 
has  now  been  referred  to  Oospora  pustulans  sp.  n.  ;  it  is  confined  to  the 
surface  layers  of  the  potato,  but  may  be  so  disfiguring  that  the  commer- 
cial value  of  the  tubers  is  very  much  lowered,  and  "  eyes "  may  be 
pre\'ented  from  forming.  The  writer  advises  the  avoidance  of  spotted 
potatoes  for  planting.  A.  L.^S. 

Clover  Stem-rot.— A.  D.  Cotton  {Journ.  Agric,  1920,  26,  1241-4, 
1  pi.).  This  disease  is  due  to  Sderoiinia  trifoUorum.  It  usually  makes 
its  appearance  in  November,  and  spreads  as  a  sparse  white  mould  over 
the  foliage.  In  bad  cases  the  fungus  invades  the  roots  and  kills  the 
plants  outright.  The  sclerotia  in  the  soil  may  retain  their  vitality  for 
years.  An  interval  of  eight  or  twelve  years  should  be  allowed  before 
re-sowing  with  clover.  A.  L.  S. 

Diseases  of  the  Rhododendron. — Henry  Schmitz  {Pliytopatholoijy , 
1920,  10,  278-8,  1  pi.).  Descriptions  of  some  of  the  more  important 
diseases  of  rhododendron,  both  wild  and  cultivated,  on  the  Pacific  coast. 
The  writer  made  cultures  and  inoculations  of  various  parasites  :  Sporo- 
cyle  Azalese,  a  bud  rot  ;  Melamp^oropsis  piperiana,  a  rust  on  a  native 
rhododendron  ;  and  various  other  leaf  parasites.  He  investigated  also 
the  vsitches-brooms  of  the  native  plant,  bat  could  not  determine  the 
causal  agent.  A.  L.  S. 

Rot  of  Date  Fruit.— J.  G.  Broavn  {Bot.  Gaz.,  1920,  69,  521-9, 
5  figs.).  This  disease  was  worked  out  by  the  author  in  Arizona  Dates 
had  been  brought  to  him  very  badly  aft'ected.  On  examining  the  trees 
many  dates  were  found  to  be  rotted,  others  were  dry  and  mummified. 
Careful  cultures  showed  that  the  fruit  was  first  attacked  by  Alteniariciy 
which  induced  mummification,  but  if  the  first  attack  were  followed  by 
AsperyiUus  and  PeniciUium  on  the  diseased  areas,  the  date_s  were  quickly 
destroyed.  A.  L.  8. 

Entyioma  Ranunculi  injurious  to  Helleborus  niger. — C  Arnaud 
{Bull.  Soc.  Path.  vey.  Frame,  1919,  6,  10-12  ;  see  also  Bull.  Ayric. 
Intell.    PL   Pis.   Rome,  1919,    10,   747-8).      The  fungus  attacks  the 


350  SUMMARY    OF   CURRENT    RESEARCHES   RELATING   TO 

petioles  near  the  base,  and  the  leaf  dies  off.  On  the  diseased  petioles 
there  develops  also  Coniothyrium  Hellehori,  followed  by  other  fungi  and 
bacteria  which  complete  the  work  of  destruction.  A.  L.  S. 

liicliens. 

Lichen  Flora  and  Lichen  Vegetation  of  Iceland.— Olaf  Gall0e 
{The  Botany  of  Iceland,  1919-20,  2,  1,  1-248).  In  the  introduction  the 
author  gives  an  account  of  work  done  by  previous  collectors.  This  is 
followed  by  a  critical  examination  of  tlie  methods  of  classification  and 
by  the  lists  of  lichens,  most  of  them  seen  and  collected  by  himself.  In 
these  lists  he  notifies  the  occurrence  of  the  lichens  in  (xreenland  and 
in  Great  Britain.  Gall0e  discusses  the  means  of  dispersal  and  distri- 
bution, with  special  reference  to  the  conditions  that  prevail  in  Iceland  ; 
he  concludes  that  wind  is  there  the  chief  agent  in  scattering  spores  or 
portions  of  the  lichen  thallus.  Tlie  special  ecology  of  Iceland  lichens 
occupies  a  good  deal  of  his  paper.  There  are  few  trees,  and  the  bark 
lichens  are  "mainly  those  growing  on  old  birch  trunks.  Rock  and  soil 
lichens  are  numerous,  but  CTa]l0e  decides  that  abundant  growth  is 
inhibited  by  the  extreme  cold  of  such  a  northern  region. 

A.  LoRRAix  Smith. 

Hints  for  Lichen  Studies. — Albert  C.  Herre  {Bryoloyist,  1920, 
23,  26-7).  Herre  deplores  the  small  number  of  people  that  interest 
themselves  in  the  study  of  lichens,  seeing  the  plants  are  more  or  less 
abundant  everywhere.  He  concludes  that  it  is  the  lack  of  manuals  that 
has  hindered  students.  He  suggests  as  an  interesting  field  of  study  tlie 
observation  of  yearly  growth  in  definite  species  and  individuals.  He 
also  adds  observations  on  the  meaning  of  the  lichen  plant,  which  is 
largely  a  physiological  species,  but  shows  constant  heredity.     A.  L.  S. 

Mycetozoa. 

Critical  Study  of  the  Slime-Moulds  of  Ontario.— Mary  E.  Currie 
{Trans.  Roy.  Ganad.  Inst,  1920, 12,  247-^08,  ?>  pis.).  The  majority  of 
the  mycetozoa  recorded  in  this  paper  were  collected  in  the  Lake  Ontario 
region  ;  a  few  were  from  other  parts  of  Ontario.  The  writer  enumerates 
29  genera  and  117  species  and  varieties.  Of  these  :i  species  and 
2  varieties  are  new  to  North  America.  Interesting  biological  and  de- 
scriptive notes  are  given,  along  with  the  exact  localities  and  substrata. 

A.  LoRRAiN  Smith. 

Mycetozoa  and  Disease. — J.  Jackson  Clarke  {Protozoa  and 
Disease,  1920,  5,  1-133,  1  pL,  46  figs  ;  London  :  Balliere,  Tindall  and 
Gox).  The  author  claims  to  have  proved  the  occurrence  of  mycetozoa 
in  cancer.  He  gives  a  history  of  mycetozoa,  more  especially  of  their 
development  as  observed  in  cultures,  and  adds  his  own  observations, 
which  are  mainly  concerned  with  the  culture  of  Didymiwn  difforme.  He 
then  describes  cultures  of  very  similar  organisms  that  developed  from 
cancer.  Careful  figures  of  the  organisms  in  both  cases  are  placed  side 
by  side.  He  gives  arguments  and  reasons  in  support  of  his  facts.  He 
contrasts,  for  instance,  in  a  striking  figure  the  formation  of  capillitiuni 
fibres  in  tubers  and  those  in  a  mycetozoon  {Comatricha  nigra),  both 
examples  taken  from  his  own  cultures.  A.  L.  S. 


ZOOLOGY    AND   BOTANY,    MICROSCOPY,   ETC.  351 


METALLOGRAPHY. 

Some  Theoretical  Principles  of  Alloying. — Robert  J.  Anderson 
{Chemical  and  Metallurgical  Engineering,  August  25,  1920,  23,  Xo.  8). 
A  discussion  of  possible  applications  of  such  general  concepts  as  may  be 
drawn  from  the  equilibrium  diagram,  heat  of  alloy  formation,  thermit 
reaction,  diffusion  and  solution  to  problems  connected  with  the  produc- 
tion of  aluminium-copper  alloys  in  the  foundry. 

Studies  of  the  Macrostructure  of  Cast  Steel. — Fred.  G.  Allison 
and  Martin  M.  Rock  {Chemical  and  Metallurgiccd  Engineering,  Sept.  1, 
1920,  23,  No.  9).  Simple  and  reliable  procedure  is  outlined  for  the 
development  and  record  of  macrostructure.  A  peculiar  banded  structure 
is  described.  Symmetrical  arrangement  of  dendrites  is  necessary  for 
consistent  physical  tests.     Pouring  cold  metal  suppresses  dendrites. 

Some  Commercial  Heat-treatments  for  Alloy  Steels  for  Structural 
Purposes. — A..  H.  Miller  {Chemical  and  Metallurgical  Eagineermg, 
July  21,  1920,  23,  No.  ;->).  A  general  discussion  of  principles  of  heat- 
treatment,  having  especial  reference  to  a  nickel-chromium  steel,  the  effect 
of  time  in  complex  heat- treatments,  and  the  development  of  simple  heat- 
treatments  from  the  complex. 

The  Crystalline  Structure  of  Antimony. — R.  AY.  James  and  N. 
TuNSTALL  iyPhd.  Mag.,  August,  1920).  This  research  follows  the  lines 
laid  down  by  Professors  W.  H.  and  W.  L.  Bragg.  It  is  remarkably 
interesting  in  view  of  the  structure  of  antimony  and  its  alloys  as  usually 
seen  microscopically.  F.  I.  G.  R. 

On  the  Electrical  Conductivity  of  Copper  Fused  with  Mica. — 
A.  L.  Williams  and  Others  {Phil.  Mag.,  Sept.,  1920).  It  is  found 
that  samples  of  copper  fused  with  mica  exhibit  a  very  large  fall  in 
resistance  when  gradually  subjected  to  rising  temperatures.  Photomicro- 
graphs of  specimens  at  different  magnifications  are  given.  The  illumi- 
nation in  some  cases  was  oblique,  in  others  direct.  Ammonia  was 
employed  as  the  etching  re-agent.  F.  I.  G.  R. 

The  Economic  Selection  of  Coal. — A.  L.  Booth  (Iron  and  Steel 
Institute  Meeting,  Sept.,  1920).  Although  dealing  chiefly  with  coal 
from  the  industrial  standpoint,  the  author  gives  much  information  of 
interest  to  microscopists,  including  a  number  of  coloured  plates  prepared 
from  photomicrographs.  F.  I.  G.  R. 

Temper -brittleness  of  Nickel-Chromium  Steels. — R.  H.  Greaves 
and  J.  J.  A.  Jones  (Ironand  Steel  Institute  Meeting,  Sept.,  1920).  The 
paper  deals  with  (1)  the  range  in  which  temper-brittleness  is  produced  ; 
(2)  the  rate  at  which  temper-brittleness  is  produced  ;  (3)  the  suscepti- 
bility of  certain  steels  to  develop  temper-brittleness  ;  (4)  the  effect  of 
the  change  from  the  brittle  to  the  tough  condition  on  a  few  of  the 
physical  properties  of  the  steel.  F.  I.  G.  R. 


352  SUMMAKY    OF    CURRENT    RESEARCHES    RELATIXG    TO 

The  Constitution  of  the  Nickel-Iron  Alloys. — D.  Hanson  and 
H.  E.  Hanson  (Iron  and  Steel  Institute  Meeting,  Sept.,  1920).  The 
purpose  of  the  investigation  is  :  (1)  the  determination  of  the  effect  of 
small  quantities  of  nickel  on  the  critical  points  of  pure  iron  ;  (2)  an 
examination  of  Osmond's  theory  of  the  nickel-iron  alloys,  and  the  deter- 
mination, if  possible,  of  the  "  stable  "  diagram  of  the  nickel-iron  allovs. 

F.  I.  G.  r; 

On  Graphitization  of  Iron-Carbon  Alloys. — K.  Honda  and 
T.  Murakami  (Iron  and  ^teel  Institute  Meeting,  Sept.,  1020).  The 
authors  determine  the  period  of  graphite  formation  in  iron-carbon  alloys 
during  cooling,  and  the  condition  of  its  occurrence.  F.  I.  G.  R. 

On  the  Formation  of  Spheroidal  Cementite. — K.  Honda  and  S. 
Sait6  (Iron  and  Steel  Institute  Meeting,  Sept.,  11)20.)  The  conclusions 
reached  are  :—  1.  If  a  quenched  specimen  be  heated  to  below  Acl, 
sorbitic  cementite  spheroidizes.  2.  If  a  hyper-eutectoid  steel  be  heated 
above  Acl,  but  below  the  solubility  line,  and  quenched,  the  spheroidiz- 
ation  of  the  super-eutectoid  takes  place.  3.  If  a  lamellar  pearlitic  steel 
be  heated  to  just  Acl,  or  a  little  above,  for  a  certain  interval  of  time, 
spheroidization  takes  place.  4.  Granular  pearlite  spheroidizes  by  being 
heated  below  Acl  for  a  sufficiently  long  time.  5.  If  Acl  be  not  reached, 
the  spheroidization  of  lamellar  cementite  can  never  proceed.  If  the 
maximum  temperature  exceed  a  certain  limit  above  Acl  and  the  steel  be 
then  cooled,  cementite  appears  as  a  lamellar  pearlite.  6.  The  tempera- 
ture interval  of  spheroidization  in  low-carbon  steels  is  very  small, 
extending  to  only  about  20'  C  ;  it  increases  rapidly  with  the  content  of 
carbon.  In  verv  hiuh  carbon  steels  the  interval  amounts  to  about 
100  C.  '       ^  F.  I.  G.  R. 

Indian  Iron  Making"  at  Mirjati  Chota,  Nagpur. — A.  McWilliam 
(Iron  and  Steel  Institute  Meeting,  Sept.,  11)20).  Under  the  microscope, 
sections  of  the  iron  showed  mainly  normal  wrought-iron  structure, 
but  with  bands  of  varying  and  much  higher  carbon  content.  Several 
sections  were  examined  microscopically,  and  the  carbon  content  was  seen 
to  vary  from  nearly  nil  to  the  eutectoid  point.  F.  I.  G.  R. 

Intercrystalline  Fracture  in  Mild  Steel. — AV.  Rosenhain  and 
I).  Hanson  (Iron  and  Steel  Institute  Meeting,  Sept.,  1920). 

Experiments  on   the  De-oxidization  of  Steel  with  Hydrogen. — 

J.  II.  Whiteley  (Iron  and  Steel  Institute  Meeting,  Sept.,  11)20). 

On  Spherical  Shell  Crystals  in  Alloys. — J.  E.  Stead  (Institute 
of  Metals,  Autumn  Meeting,  Sheffield,  11)19).  This  is  the  first  instalment 
of  the  author's  work  on  this  subject.  Some  truly  beautiful  photographs 
of  structures  in  the  allovs  of  tin,  antimonv,  and  arsenic  are  given. 

F^.  I.  G.  R. 

Distinguishing  Lead  in  Brass  and  Bronze.— F.  P.  Galligan  and 
J.  J.  OuJiRAN  {Metal  InduMry,  June  25, 1920, 16,  No.  26).  A  criticism 
on  the  method  of  distinguishing  lead  in  brass  and  bronze  by  the  apphca- 
tion  of  sulphide  etching,  pointing  out  that  as  a  means  of  detection  it 
has  no  advantages,  that  lead  is  best  detected  in  a  polished  and  unetched 
specimen. 


ZOOLOGY   AND   BOTANY,   MICROSCOPY,    ETC.  353 


GEOLOGY. 

On  the  Quartzite  Pebbles  of  the  Oldhaven  (Blackheath)  Beds 
of  the  Southern  Part  of  the  London  Basin. — H.  A.  Baker  {Geological 
Mag.,  Feb.  1920). — 1.  The  sarseu  stones  and  pudding  stones  cousirlered 
are  cemented  portions  of  sandy  and  pebblj  lower  Eocene  strata.  2.  The 
TToolwich  and  Reading  Ijeds  have  afforded  one  source  of  supply  of  these 
stones.  3.  The  pebbles  of  quartzite  and  siliceous  flint  cong-lomerate 
occurring  in  the  Oldhaven  (Blackheath)  beds  are  rolled  fragments  of 
sarsen  and  pudding  stone  deiived  from  the  Woolwich  and  Reading 
beds.     Photo micrographic  illustrations  are  included  in  the  memoir. 

F.  I.  G.  R. 

On  the  Petrography  of  the  Millstone  Grit  Series  of  Yorkshire. — 
A.  GiLLiGAN  (Geological  Society,  May  21,  1919).  Since  Sorby's  work 
on  this  subject,  published  in  1859,  little  has  been  done.  The  present 
author  has  undertaken  much  microscopical  work  on  the  Millstone  Grit, 
and  brings  forward  theories  of  great  interest.  F.  I.  G.  R. 

Notes  on  the  Extraneous  Minerals  in  the  Coral  Limestones  of 
Barbados. — J.  B.  Harrison  and  0.  B.  W.  Anderson  (Geological 
Society,  June  4,  1919).  Characteristic  representative  specimens  of  the 
fossil-reef  corals,  etc.,  were  examined  microscopically.  A  note  on  the 
proportions  of  titanium  oxide  in  the  Barbados  Oceanic  Clays  and  in 
some  of  the  "  Challenger "  and  "  Buccaneer "  deep-sea  dredgings  is 
appended.  F.  I.  G.  R. 

On  the  Silurian  Rocks  of  May  Hill. — C.  L  Gardiner  (Geological 
Society,  May  21,  1919).  In  the  same  paper,  Dr.  F.  R.  C.  Reed  de- 
scribes a  new  species  of  Lichas  from  the  Wenlock  Limestone,  and  a  new 
variety  of  Calymene  pajnilata.  F.  I.  G.  R. 

On  the  Dentition  of  the  Pelalcdont  Shark  "  Climaxodus." — 
A.  Smith  WoODAVARD  (Geological  Society,  June  4,  1919). 

On  Syniogothyris  Winchell,  and  Certain  Carboniferous  Brachio- 
poda  referred  to  Spiriferina  d'Orhigny. —  F.  J.  North  (Geological 
Society,  Jan.  7,  1920). 

Some  Microchemical  Methods. — A.  Brammall  (Geological  Mag., 
March,  1920).  The  tests  afforded  by  ferricyanide,  ferrocyanide,  and 
thiocyanate  solutions  may  be  adapted  to  the  microchemical  investigation 
of  certain  rocks  in  thin  section.  F.  I.  G.  R. 


2  a 


354 


NOTICES    OF    NEW   BOOKS. 

Modern  Study  of  Heredity.   ByT.  H.  Morgan.    {The  Phijsical  Basis  of 
Heredity,  Philadelphia  and  London,  1919,  1-305,  117  figs.) 

The  two  fundamental  principles  of  heredity  discovered  by  Mendel 
were  the  law  of  segregation  and  the  law  of  independent  assortment  of 
the  genes.  Sutton,  in  1902,  was  the  first  to  point  out  clearly  how  the 
chromosomal  mechanism,  then  known,  supplied  the  necessary  mechanism 
to  account  for  Mendel's  two  laws.  The  acceptance  of  this  mechanism  at 
once  leads  to  the  logical  conclusion  that  Mendel's  discovery  of  segrega- 
tion applies  not  only  to  hybrids,  but  also  to  normal  processes  that  are 
taking  place  at  all  times  in  all  animals  and  plants,  whether  hybrids  or 
not.  Since  1900  four  other  principles  have  been  added.  These  are 
known  as  linkage,  the  linear  order  of  the  genes,  interference,  and  the 
limitation  of  the  linkage  groups. 

Mendelism  rests  on  the  theory  of  a  clean  separation  of  the  members 
of  each  pair  of  factors  (genes).  In  every  heterozygote  the  factor  for 
the  dominant  and  that  for  the  recessive  are  supposed  to  come  into 
relation  to  each  other  and  then  to  separate  at  the  ripening  of  the  germ- 
cells.  The  point  is  the  clean  separation  of  the  genes  without  contamina- 
tion (unless  as  an  exceptional  phenomenon).  Mendelian  characters  are 
not  confined  to  the  surface.  A  common  class  of  characters  showing 
perfect  Mendelian  behaviour  are  so-called  lethals  that  destroy  the 
individual  when  in  homozygous  condition.  In  recent  years  an  entirely 
unexpected  and  important  discovery  in  regard  to  segregating  pairs  of 
genes  (allelomorphs)  has  been  made.  In  an  ever-increasing  number  of 
cases  it  has  been  found  that  there  may  be  more  than  two  distinct 
characters  that  act  as  allelomorphs  to  each  other.  For  example,  in  mice, 
yellow,  sable,  black,  white-bellied  grey,  and  grey-bellied  grey  (wild  type) 
are  allelomorphs — i.e.  any  two  may  be  present  (as  a  pair)  in  an  indi- 
vidual, but  never  more  than  two.  In  all  probability,  apart  from  liybrids 
altogether,  the  germ-plasm  is  at  first  made  up  of  pairs  of  elements,  but 
at  the  ripening  of  the  germ-cells  these  elements  (genes)  separate,  one 
member  of  each  pair  going  to  one  daughter-cell,  the  other  member  to 
the  other  cell. 

The  sperm  and  the  (igg  pass  through  essentially  the  same  stages 
during  maturation,  the  essential  feature  of  which  is  the  conjugation  of 
homologous  (paternal  and  maternal)  chromosomes  followed  by  their 
subsequent  segregation.  Each  egg  and  each  sperm  is  left  with  half  the 
original  nnmber  of  chromosonies — one  of  each  kind,  i.e.  only  a  paternal 
or  a  maternal  member  of  each  chromosome  pair.  It  is  obvious  that  if 
one  member  of  any  pair  contains  material  that  produces  an  effect  on 
some  character  as  one  of  the  end  results  of  its  activity,  and  the  other 
member  of  the  pair  contains  a  different  material,  the  behaviour  of  the 


NOTICES    OF   NEW    BOOKS.  355 

chromosomes  at  the  time  of  maturation  supplies  exactly  the  mechanism 
that  Mendel's  law  of  segregation  calls  for. 

Mendel's  second  law  is  the  independent  assortment  of  the  genes. 
If  at  the  maturation  (whether  of  egg  or  sperm)  the  genes  "tall"  and 
"  colour  "  go  to  one  cell,  then  the  genes  "  short "  and  "  white  "  go  to  the 
other,  or  "short"  and  "colour"  go  to  one  cell,  "tall"  and  "white"  to 
the  other.  Four  classes  of  germ-cells  will  be  expected  in  the  F^  genera- 
tion— viz.  tall  colour,  tall  white,  short  colour,  and  short  white.  Each 
pair  of  chromosomes,  just  before  the  reduction  division,  consists  of  a 
maternal  and  a  paternal  member  ;  the  evidence  points  to  random  or 
free  assortment  of  some  maternal  chromosomes  to  one  pole  and  some  to 
the  other,  and  similarly  for  the  paternal  chromosomes.  This  will 
account  for  the  independent  assortment  of  genes  which  Mendel's  second 
law  postulates. 

But  further  investigation  is  disclosing  an  increasing  number  of  cases 
in  which  free  assortment  does  not  occur.  Many  characters  have  been 
found  to  keep  together  in  successive  generations  instead  of  assorting 
freely.  This  is  called  linkage,  and  it  may  be  complete  or  occasional. 
The  correlative  aspect  of  linkage  is  crossing  over,  and  inasmuch  as  it 
involves  a  change  in  the  mechanism  that  gives  linkage,  it  is  entitled  to 
rank  as  one  of  the  fundamental  principles  of  heredity.  It  means  that 
there  is  an  interchange  of  blocks  of  genes  between  homologous  pairs  of 
chromosomes.  Pairs  of  characters  may  be  spoken  of  as  loosely  linked, 
meaning  that  crossing  over  of  genes  frequently  takes  place,  or  as  strongly 
linked,  meaning  that  crossing  over  is  very  infrequent.  It  is  probable 
that  there  is  a  limiting  value  for  crossing  over,  and  if  this  can  be 
established  it  may  lead  to  the  discovery  of  the  lower  limit  of  size  of  the 
gene  (in  terms  of  chromosome  length).  The  crossing  over,  which  may 
occur  in  germ-cells  of  the  male  and  not  in  those  of  the  female,  is  not 
effected  earlier  than  the  time  of  the  conjugation  of  chromosomes,  but  it 
can  be  effected  at  the  time  when  the  conjugation  is  known  to  occur. 
In  regard  to  all  this,  however,  there  is  still  considerable  uncertainty. 

The  data  in  regard  to  the  Hnkage  of  characters  and  the  correlative 
phenomenon  of  crossing  over  lead  to  the  conclusion  that  the  genes  are 
arranged  in  linear  order,  standing  at  definite  levels  in  the  chromosomes 
and  definitely  spaced.  Ingenious  arguments  lead  to  the  conclusion  that 
the  size  of  the  blocks  that  interchange  in  a  crossing  over  depends  on  the 
location  of  the  breaking  point,  and  that  a  break  in  one  region  interferes 
with  a  break  in  another  region.  A  correspondence  between  the  number 
of  linkage  groups  and  the  number  of  chromosome  pairs  has  been  proved 
in  Drosophila  melanoijaster,  and  no  case  is  known  where  the  number  of 
linkage  groups  exceeds  the  number  of  chromosome  pairs.  It  may  be 
that  a  limitation  of  the  linkage  groups  to  the  number  of  chromosomes 
pairs  is  a  fundamental  principle  of  heredity.  An  interesting  fact  is  the 
variability  of  the  amount  of  crossing  over  in  certain  cases  ;  the  amount 
differs  at  different  temperatures  in  Drosophila,  and  it  has  also  been 
shown  that  there  are  genes  carried  by  the  chromosomes  themselves  that 
affect  the  amount  of  crossing  over. 

One  species  may  have  twice  as  many  chromosomes  as  a  closely 
related  one.     So  frequent  is  this  that  it  can  hardly  be  due  to  chance. 

2  A  '> 


356  NOTICES  or  new  books. 

The  implication  is  that  the  number  of  tlie  original  chromosomes  has 
either  become  doubled  or  halved.  If  the  number  is  simply  doubled, 
there  would  be  at  first  four  of  each  kind  of  chromosome  from  the  point 
of  view  of  genetic  contents.  There  is  some  direct  evidence  that  this 
tetraploidy  may  occur.  There  may  be  also  doubling  in  one  pair  of 
chromosomes,  and  there  are  other  modes  of  variation  in  the  number  of 
chromosomes. 

The  discovery  that  the  female  in  certain  species  has  two  X-chromo- 
somes,  and  the  male  only  one  X-chromosome,  either  with  a  Y-chromosomo 
in  addition  (Stevens)  or  without  the  Y  (Wilson),  established  a  view  first 
suo-o-ested  by  McClung  that  the  difference  between  the  sexes  is  connected 


'OO 


with  the  distribution  of  particular  chromosomes.  It  may  be  that  the 
presence  of  two  chromosomes  (XX),  in  connection  with  the  rest  of  the 
cell  complex,  causes  a  female  to  develop ;  while  only  one  sex  chromosome 
(X),  in  connection  Avith  the  rest  of  the  cell,  causes  a  male  to  develop. 
Or  it  may  be  that  XX  and  X  are  merely  indices  of  sex — i.e.  that  the  sex- 
chromosomes  follow  sex  and  do  not  determine  sex.  According  to 
Morgan,  the  evidence  is  now  conclusive  that  sex  follows  the  chromosomes. 
He  also  shows  how  the  chromosome  theory  of  sex  may  apply  to 
"  intersexes,"  gynandromorphs,  and  allied  phenomena. 

In  so  far  as  parthenogenetic  reproduction  takes  place  without 
redaction  in  the  number  of  the  chromosomes,  the  expectation  of  any 
character  is  that  it  will  have  the  same  frequency  distribution  in 
successive  generations,  because  the  chromosome  group  is  identical  in 
eacli  generation.  The  same  will  apply  to  a  species  propagating 
vegetatively,  or  to  cases  of  sexual  reproduction  in  a  homozygous  group 
of  individuals  (as  in  Johanusen's  pure  lines). 

Almost  the  whole  interpretation  outlined  above  rests  on  the  postulate 
that  the  chromosomes  are  the  bearers  of  the  hereditary  factors  or  genes. 
There  is  cytological  and  eml)ryological  evidence  supporting  this  view, 
but  it  is  the  genetic  evidence  that  is  convincing.  That  there  may  be 
substances  in  the  cytoplasm  that  propagate  themselves  there  and  that 
are  outside  the  influence  of  the  nucleus  must  be  conceded  as  possible  ; 
but,  aside  from  certain  plastids,  all  the  Mendelian  evidence  fails  to  show 
that  there  are  such  characters.  It  is  difficult  to  determine  whether  a 
peculiarity  of  the  ovum-cytoplasm,  such  as  colour,  is  due  to  inherited 
plastids  or  to  the  influence  of  the  ovum-nucleus  before  fertihzation. 

A  gene  is  to  be  tliought  of  as  a  certain  amount  of  material  in  the 
cln'omosome  that  may  separate  from  the  chromosome  in  wliicli  it  lies, 
and  be  replaced  by  a  corresponding  part  (and  none  other)  of  the 
homologous  chromosome.  It  is  of  fundtimental  significance  in  this 
connexion  to  recognize  that  the  genes  of  tlie  pair  do  not  jump  out  of 
one  chromosome  into  the  other,  so  to  speak,  but  are  changed  l)y  the 
thread  breaking  as  a  piece  in  front  of  or  else  behind  them,  but  not  in 
both  places  at  once,  as  would  be  the  case  if  only  a  single  pair  of 
allelomorphs  were  involved  each  time. 

A  number  of  general  propositions  may  be  stated  : — 1.  A  gene  is 
associated  with  manifold  effects.  AVhatever  it  is  in  the  germ-plasm 
that  produces  white  eyes  produces  other  peculiarities  as  well.  2.  The 
variability  of  ;i  character  is  not  necessarily  due  to  variability  in  the  gene  ;. 


NOTICES   OF   NEW    BOOKS.  357 

much  is  due  to  variability  in  the  environmental  conditions  of  development. 
3.  Characters  that  are  indistinguishable— e.g.  whiteness  in  poultry  may 
be  produced  Ijy  different  genes.  4.  Each  character  is  the  product  of 
many  genes,  but  each  of  these  may  change  witliout  the  others  changing. 
Both  in  segregation  and  in  crossing  over  each  pair  is  inseparable  from 
the  others. 

Of  mutations  it  may  be  said  that  they  appear  infrequently,  that  the 
change  is  definite  from  the  beginning,  that  some  at  least  are  recurrent, 
and  that  the  difference  between  the  old  character  and  the  new  one  is 
small  in  some  cases  and  greater  in  others.  Their  origin  remains  obscure. 
As  to  their  supposed  "  chance "  character,  it  is  pointed  out  that  the 
degree  of  development  of  any  character  increases  the  probability  of 
further  stages  in  the  same  direction.  Species  are  to  be  thought  of  as 
groups  of  genes,  and  related  species  have  a  good  many  genes  in  common. 
Thus  similar  mutations  are  likely  to  occur  in  different  species,  and  there 
is  experimental  evidence  of  this  in  Drosophila.  J.  A.  T. 

Traite  de  la  Lumike.  Par  Christian  Huyghens.  1920.  155  x  x  pp. 
Price  3  fr.  GO.     Published  by  Gauthier-Villars  et  Cie.,  Paris. 

Microscopical  Preparations.  Catalogue  of  Zoological  and  Botanical 
Mateiial,  Fresh  and  Preserved.  1920.  Flatters  and  Garnett,  Ltd., 
309  Oxford  Road,  Manchester. 

Report  of  the  Enquiry  Committee  on  the  Standardization  of  the 
Elements  of  Optical  Instruments.  39  pp.  Price  Is.  net.  Pub- 
lished for  the  Department  of  Scientific  and  Industrial  Research  by 
His  Majesty's  Stationery  Office. 

National  Physical  Laboratory  Report    for  the  Year  1919.     152  pp. 

Price  5s.  net.     Published  by  His  Majesty's  Stationery  Office. 

Common  Diatoms.  P>y  Thomas  K.  Mellor,  F.R.A.S.  1920.  16  pp., 
7  pis.  Price  Qs.  net.  Published  by  William  Wesley  and  Son, 
28  Essex  Street,  Strand,  W.C. 

Studies  on  Acari.  No.  1.  The  Genus  Demodex  Owen.  By  Stanley 
Hirst.  1919.  44  pp.,  13  pis.  Price  lOs.  Published  by  the  British 
Museum  (Xatural  History),  Cromwell  Road,  S.W.7 

Marine  Boring  Animals.  By  W.  T.  Caiman,  D.Sc.  1919.  36  pp. 
Price  Is.  Published  by  the  British  Museum  (Natural  History), 
Cromwell  Road,  S.W.7 

The  British  Charophyta.  By  .James  Groves,  F.L.S.,  and  George 
Russell  Bullock-Webster,  M.A.,  F.D.S.  1920.  142  pp.,  20  pis. 
Published  by  the  Ray  Society. 

A  Monograph  of  the  British  Orthoptera.  By  William  John  Lucas,  B.A. 
1920.     264  pp.,  25  pis.     Published  by  the  Ray  Society. 


358 


PEOCEEDINGS    OF    THE    SOCIETY 


AN   ORDINARY  MEETING 

OF  THE  Society  was  held  at  No.  20  Hanover  Square,  AV.,  ox 
Wednesday,  June  16th,  1920,  Professor  John  Eyre, 
President,  in  the  Chair. 

The  Minutes  of  the  preceding  Meeting  were  read,  confirmed,  and 
signed  by  the  President. 

The  nomination  papers  were  read  of  two  Candidates  for  Fellowship. 


New  Fellows.^The  following  were  elected  Ordinary  Fellows  of  the 
Society  : — 

Mrs.  Bertha  Altof . 

Mr.  Herbert  Graham  Cannon,  B.A.,  F.Z.S. 

Mr.  William  Edmund  Cooke,  M.D.,  F.R.C.P.,  D.Ph. 


A  Donation  was  reported  from  Dr.  E.  Penard,  of  Geneva,  an 
Honorary  Fellow  of  the  Society,  consisting  of  100  slides  covering  nearly 
all  the  genera  of  Fresh-water  Rhizopoda  and  a  few  Ciliata. 

Mr.  Scourfield  exhibited  a  number  of  Dr.  Penard's  preparations, 
including  the  following  -.^Difflugia  /lydrostatica^iihovfing  test  formed  of 
frustules  of  the  plankton  Diatom  CydoteUa  ;  GiicurUtalla  mespili- 
formis,  with  symbiotic  zoochlorella3 ;  tSpirochona  gemmipara,  and  Arcella 
dentata. 

A  hearty  vote  of  thanks  was  accorded  to  Dr.  Penard. 


Mr.  W.  G.  Collins  read  a  paper  on  "A  Universal  Microtome," 
written  by  Sir  Horace  Darwin,  F.R.S.,  and  himself.  The  paper  was 
illustrated  by  lantern  slides  and  exhibits,  and  is  printed  in  this  issue  of 
the  Journal  (see  page  288).  Asked  as  to  what  would  be  the  probable 
price  of  the  instrument,  Mr.  Collins  said  that  they  hoped  it  would  not 
exceed  £20. 

The  President  proposed  a  very  heurty  vote  of  thanks  to  the  authors 
of  the  paper,  and  this  was  carried  l)y  acclamation. 

Mr.  Lancelot  Hogben,  M.A.,  B.Sc,  read  a  paper  on  "  The  Problem 
of  Synapsis."  This  paper  is  printed  in  this  issue  of  the  Journal  (see 
page  26!)). 


PROCEEDINGS    OF   THE    SOCIETY.  359" 

Dr.  Gatenby  thought  that  the  problem  of  heredity  was  to  be  attacked 
from  the  nucleus.  It  was  probably  true  that  in  specialized  forms  there 
might  be  a  partial  handing  on  of  the  hereditary  functions  of  the  nucleus 
to  certain  inclusions  of  the  cytoplasm,  but  he  thought  in  the  long  run  it 
could  be  shown  that  the  functions  had  been  handed  on  by  the  nucleus 
which  was  at  the  bottom  of  everything. 

The  President  proposed  a  very  hearty  vote  of  thanks  to  Mr.  Hogben^ 
which  was  carried  by  acclamation. 

A  vote  of  thanks  was  accorded  to  Messrs.  Hawksley  and  Sons  for  the 
loan  of  microscopes. 

The  business  proceedings  then  terminated. 


REPORT  OX  THE  COLLECTION  OF  METALLURGICAL 
SPECIMENS  RECENTLY  PRESENTED  TO  THE 
SOCIETY  BY  SIR  ROBERT  HADFIELD,  Bart.,  F.R.S. 

By  F.  Iax  G.  Rawlixs. 

{Read  November  19,  1919.) 

The  primary  purpose  of  this  communication  is  to  bi'ing  to  the  notice  of 
Fellows  a  collection  of  Metallurgical  Micro-specimens  which  Sir  Robert 
Hadfield  has  been  good  enough  to  give  to  the  Society.  The  report  will 
deal  with  the  matter  in  the  following  order  :— 1.  Early  Suggestions. 
2.  The  Collection  Itself.  3.  Description  of  the  more  important  Micro- 
Structures.     4.  Preservation  and  Future  Arrangements. 

When  these  have  been  explained  and  discussed  Fellows  will  be  in  a 
position  to  examine  for  themselves  the  selection  of  specimens  from  the 
collection  which  is  on  view  this  evening. 

Before  proceeding  further  I  ought  perhaps  to  mention  that  in  June 
last  the  Council  honoured  me  by  asking  that  I  would  undertake  the 
duty  of  curator  of  this  collection.  I  assented  with  pleasure,  so  far 
as  the  pressure  of  other  work  permitted,  and  this,  I  trust,  explains  my 
presence  here  in  this  capacity  to-night. 

1.  Early  Sugf/estions. — In  the  Autumn  of  last  year,  about  the 
beginning  of  the  Session,  a  suggestion  was  made  that  this  Society 
might  become  a  means  of  furthering  interest,  and  perhaps  research,  in 
metallography  (i.e.  the  examination  of  prepared  metal  surfaces  micro- 
scopically) if  some  specimens  could  be  obtained  to  act  as  a  nucleus  of  a 
collection  which  would  be  at  the  service  of  Fellows,  in  much  the  same 
way  as  the  Society's  general  collection  of  slides.  It  is  hardly  necessary 
to  point  out  that  metal  specimens  cannot  be  purchased  commercially, 
as  is  the  case  with  some  other  kinds  of  objects,  nor  can  they  be 
prepared  except  by  those  who  have  the  necessary  appliances  ;  and  the 
number  of  persons  so  equipped  is  small.  Taking  account  of  these 
considerations,  in  December  1918  a  letter  was  sent  to  Sir  Robert 
Hadfield,  pointing  out  our  views  upon  the  matter,  and  asking  for  his 


360  PROCEEDINGS   OF   THE   SOCIETY. 

•assistance  towards  the  much-needed  collection  of  specimens.  A  reply 
was  received  from  Sir  Robert  in  which  he  generously  promised  to  give 
a  number  of  specimens  from  his  Research  Laboratory,  adding  at  the 
same  time  an  expression  of  his  whole-hearted  support  of  the  scheme. 

2.  The  GollexUoii  Itself. — After  a  short  interval  the  gift  of  slides 
€ame  to  hand.  It  consisted  of  twenty  specimens,  including  particularly 
interesting  alloy  steels,  together  with  cast  irons,  and  samples  of  varying 
carbon  content  after  having  received  different  thermal  treatment, 
the  whole  thoroughly  representative  of  modern  metallurgical  practice, 
and  affording  a  wide  range  of  interesting  micro-structures.  The 
specimens  w^ere  ground  down  to  level  surfaces,  but  naturally  the  polish- 
ing and  etching  process  had  yet  to  be  done.  I  may  add  that  I  was 
away  at  a  considerable  distance  during  this  period,  and  consequently 
some  delay  was  unavoidable  before  I  was  able  to  see  the  specimens  and 
consider  plans  for  their  final  treatment.  After  I  had  examined  the 
specimens  I  approached  Prof.  H.  C.  H.  Carpenter,  Ph.D.,  F.R.S.,  asking 
whether  he  would  be  so  kind  as  to  allow  tlie  finishing  process  to  proceed 
at  the  Royal  School  of  Mines.  To  this  he  generously  agreed,  and  to 
him  we  are  indebted  for  his  timely  assistance  and  interest  in  the 
scheme.  The  sections  were  received  back  complete  last  July,  since 
when  they  have  been  at  the  Society's  Rooms. 

3.  Description  of  the  more  important  Micro- Structures.'" — Sir  Robert 
Hadfield  enclosed  a  detailed  list,  giving  the  chemical  composition  and 
thermal  treatment  of  each  specimen,  and  in  the  light  of  this  information 
it  may  be  well  for  me  briefly  to  review  the  most  interesting  points  of 
the  structures  as  seen  under  the  microscope. 

The  "Armco"  iron  (2148)  is  a  beautiful  specimen.  It  consists, 
one  might  say  wholly,  of  allotriomorphic  crystals  of  "  ferrite  "  (pure 
alpha  iron).  The  outlines  of  the  grains  are  developed  on  etching, 
due  to  minute  differences  of  potential  at  their  junctions.  Neigh- 
bouring grains  are  coloured  differently  owing  to  variations  in  orienta- 
tion. The  "B.B."  wrought  iron  (2112)  shows  the  slag-inclusions 
very  characteristic  of  such  material.  Comparison  with  a  sample 
of  mild  steel  (say  1350)  shows  the  essential  difference  between  these 
products.  Wrought  iron  consists  of  a  number  of  layers  from  between 
which  the  whole  of  the  slag  has  not  been  squeezed  out.  The 
cast  irons  (912,  918)  bring  out  the  complexity  of  the  constituents  present, 
the  white  metal  being  especially  interesting.  The  low,  medium,  saturated, 
and  supersaturated  car])on  steels  show  the  transition  from  a  few  isolated 
islets  of  "  pearlite  "  (low  carbon  steel)  through  "saturated,"  where  the 
whole  structure  is  pearlitic,  to  "  supersaturated,"  where  areas  of  "cemen- 
tite  "  (FcaC)  make  their  appearance  surrounding  the  "  pearlite."  The 
*'  special  "  steels  "  Era  "  and  "  Cr-Ni  "  are  interesting,  the  former  because 
they  alloAV  of  the  retention  of  "  Austenite  "  (solid  solution  of  carbon  or 
FcgC  in  gamma  iron),  a  constituent  usually  only  stable  at  high  tempe- 
rature.    The  "  Cr-Ni  "  specimens  are  pearlitic,  as  is  generally  the  case. 

4.  Preservation  and  Future  Arrant/ements. — It  remains  now  to  deal 
with  this  important  matter.     After  careful  consideration  it  was  decided 

*  See  also  annotated  list  appended  to  this  paper. 


PROCEEDINGS    OF    THE    SOCIpyrY.  361' 

to  purchase  a  desiccator  in  which  the  specimens  may  be  kept  free  from 
rust  and  tarnish.  The  application  of  varnish  to  the  faces  is  not  to 
be  recommended  as  a  preservative.  Either  it  must  be  dissolved  off 
each  time  the  sample  is  examined,  or  else  applied  as  I  described  in  a 
communication  some  time  ago,  which  process  is  risky  and  not  very 
satisfactory.  I  have  had  these  sections  under  observation  for  some 
time,  and  I  am  hopeful  that  the  method  adopted  will  prove  efficacious. 
Owing  to  the  great  delicacy  of  the  surfaces,  it  will  be  understood 
that  the  greatest  care  is  necessary  in  handling,  as  the  infliction  of  a 
scratch  means  repolishing  and  etching. 

With  a  view  to  making  the  collection  generally  useful,  a  vertical 
illuminator  has  been  acquired  for  the  Society.  This,  of  course,  is  quite 
essential. 

In  the  near  future  the  question  of  a  suitable  light-source  will 
need  consideration.  Personally  I  have  obtained  excellent  results  with  a 
200  c.p.  J -watt  lamp.  These  lamps  are  very  moderate  in  cost,  and 
highly  convenient.  It  is  possible  to  use  our  existing  lamps,  though 
this  is  not  easy.  The  vertical  illuminator  fixes  successfully  to  one  of 
the  Society's  stands,  and  it  is  nat  essential  to  use  specially  mounted 
ol:>jectives. 

All  things  considered  the  Society  may  be  congratulated  upon  its  new 
possession.  If  it  is  appreciated,  il  will  not  be  difficult,  I  expect,  to 
obtain  additions  from  time  to  time. 


ANNOTATED  LIST   OF   METALLURGICAL   SPECIMENS    PRESENTED 

TO   THE   ROYAL   MICROSCOPICAL  SOCIETY   BY 

SIR   ROBERT   HADFIELD. 

1.  "AR:>rco"     Irox.  —  i?.  iVr?.-'-  :  2148.       Analysis-,   c.c.f  0.03  p.c, 

Mn  0-015  p.c.     Treafmmt  :  As  forged.     Mag.X  :  x  100. 

Polyhedral  grains  of  "  ferrite  "  (pure  alpha  iron).  The  individual 
grains  are  unequally  coloured  owing  to  difference  of  orientation  of  the 
crystalline  elements  composing  them.  The  boundaries  of  the  grains  are 
developed  on  etching  owing  to  minute  differences  of  potential. 

Eef.^  :  "  Metallography  and  Heat  Treatment  of  Iron  and  Steel " 
(Sauveur)  [hereinafter  called  "  Metallographv  "  (Sauveur)], 
p.  101,  fig.  116  ;  '^Metallography  "  (Desch),  p.  860,  pi.  xiii.A. 

2.  "B.B."  Wrought  Iron. — R.JS^o.  :  2112.     Analysis:  cc.  0*06  p.c, 

Mn  0  •  05  p.c.     Treatment :  As  forged.     May.  :  x  70. 
Very   typical   structure   of   wrought   iron.     This  is  a  longitudinal 
section  consisting  of  "  ferrite  "  and  layers  of  slag,  which  latter  are  the 

*  B.  No.  =  Reference  Number. 

+  cc.  =  combined  carbon. 

X  Mag.  =  Suitable  magnification. 

§  Bef.  =  References  to  well-known  treatises  where  descriptions  of  the  structure 
(together  with  further  details  than  here  given)  may  be  found.  Where  references 
to  figures  are  given,  these  illustrate  appropriately  the  particular  structure  in 
question. 


362  PROCEEDINGS   OF   THE    SOCIETY. 

cause  of  the  so-called  fibrous  appearance  of  wrought  iron.  The  ferrite 
is  not  really  pure  "  ferrite,"  but  a  solid  solution  containing  small  per- 
centages of  silicon  and  other  impurities. 

Ref.  :  "  Metallography  "  (Sauveur),  chap.  vi.  with  figs.  ;  "  Value  of 
Science  in  the  Smithy  and  Forge  "  (Cathcart),  pp.  48,  49  and 
figs. 

3.  Geey  Pio  Iron. — R.No.  :  912.     Analysis  :  c.c.  0*52  p.c,  graphite 

3  •  5  p.c.     Treatment :  As  cast.     3fa(/.  :   x   100. 

Matrix  (white)  of  ferrite — darker  parts  pearlite — long  black  inclusions 
graphite.  (The  graphite  has  probably  been  removed  in  polishing.  Only 
the  cavities  originally  containing  it  remain.) 

Ref.:  "Metallography"  (Sauveur),  chap.  xxii.  ;  "Microscopical 
Analysis  of  Metals"  (Stead)  [hereinafter  called  "Micro- 
Analysis"  (Stead)],  figs.  119  and  120. 

4.  White  Pio  Irois". — R.  No,  :  913.    Analysis  :  c.c. '^  ^.c.    Treatment', 

As  cast.     Mag.  :  x   150. 

Light  background  cementite  FegC.  Finely  divided  structure, 
pearlite.     Laminated  dark  areas,  sorbite. 

Ref.  :  "Metallography"  (Desch),  p.  376,  pi.  xiv.  A  and  b. 

5.  Low  Carbon  Steel. — R.  No.:  1350.     Analysis:    c.c.   0"17  p.c, 

Mn  0*4  p.c.     Treatment:  Annealed.     May.:  x   100. 

Polyhedral  grains  of  ferrite  ;  at  the  boundaries  may  be  seen  small 
areas  of  pearlite  which  under  higher  magnification  show  the  typical 
laminated  structure.  Throughout  the  range  of  carbon  steels  np  to 
0  •  9  p.c.  carbon,  a  gradual  increase  in  the  amount  of  pearlite  present 
will  be  noticed. 

Ref.  :  "  Metallography  "  (Sauveur),  chap,  xv.,  fig.  234. 

6.  Low    Carbon    Steel. — R.No.:  428.     Analysis:   c.c.  0*17  p.c, 
Mn  0-4  p.c     Treatment :  Quenched  900°  0.  water.     Mag.  :    x   100. 

The  effect  of  heat  treatment  is  here  seen  to  consist  in  the  breaking 
up  of  large  areas  of  pearlite,  and  a  close-grained  homogeneous  structure 
is  obtained. 

Ref.  :  "  Metallography  "  (Sauveur),  chap,  xv.,  fig.  229. 

7.  Low   Carbon   Steel.— i?.  No.:   429.      Analysis:  c.c.  0*17  }).c, 

Mn  0-4  p.c      Treatment:  Quenched  900"  C.  water,  400°  C.  air. 

Mag.  :  X  100. 
This  is  a  tempered  specimen  in  which  the  treatment  has  been  less 
drastic  ;    consequently  tlie  structure  is  inteimediate  between  Nos;  428 
and  1350. 

Ref.  :  '•  Metallography  "  (Sauveur),  chap.  xv.  p.  239  et  seq. 


PROCEEDINGS   OF    THE    SOCIETY.  363 

8.  Medium  Carbon  Steel. — R.  No.  :  970.     Analysis  :  c.c.  0  •  53  p.c, 

Mn  0-89  p.c.     Treatment:  Annealed.     Mag.:    x   100. 

Deeply- etched  specimen.  The  background  is  pearlite  not  well 
resolved.     Surrounding  it  are  membranes  of  ferrite. 

Eef. :  "  Metallography"  (Sauveur),  p.  124,  fig.  140. 

9.  Medium  Carbon  Steel. — R.No.:  977.     Analysis:  c.c.  0*53  p.c, 

Mn  0  •  89  p.c.    Treatment  :  Quenched  820°  C.  and  reheated  to  600°  C. 
Mag.  :    x   100. 

This  is  a  quenched  and  tempered  specimen  in  which  the  structure, 
though  resembling  the  foregoing,  is  more  compact.  This  has  been 
tempered  at  a  higher  temperature  than  usual,  with  the  result  that  the 
effects  of  hardening  have  been  greatly  modified. 

Ref,  :  "Metallography"  (Sauveur),  p.  239  et  seq. 

10.  Saturated  Carbon  Steel. — R.  No. :  2198.  Analysis :  c.c.  0  •  96  p.c, 

Mn.  0*36  p.c.     Treatment:  Annealed.     Mag.  :    x  100. 

This  is  practically  entirely  pearlite.  Small  indications  of  free 
cementite  can  be  found  here  and  there.  At  this  carbon  content 
(0*89  p.c.  accurately)  is  the  boundary  between  hypo-eutectoid  steel 
(less  than  0*89  p.c.  C.)  and  hyper-eutectoid  (more  than  0*89  p.c.  C). 

Ref.  :  "Metallography"  (Sauveur),  p.  127,  fig.  146. 

11.  Saturated  Carbon  Steel.— i?.  No. :  2199.  Analysis :  c.c.  0  •  96  p.c, 

Mn  0-36  p.c.     Treatment :  Quenched  800'  C.     Mag.  :    x  ,100. 

The  treatment  has  resulted  in  the  formation  of  martensite.  A 
general  idea  of  the  structure  can  be  obtained  at  this  temperature,  but 
higher  magnification  (some  300  diameters)  is  needed  to  resolve  the 
martensite. 

Ref.  :  "  Metallography  "  (Desch),  pp.  47  and  225. 

12.  Saturated  Carbon  Steel.— i^.  No. :  2200.  Analysis :  cc  0  96  p.c, 

Mn  0-36  p.c      Treatment :  Quenched  <soo°  C,  tempered  400°  C. 
Mag.  :    x  100. 

The  tempering  treatment  has  relaxed  the  strain  present  in  the 
quenched  specimen.  The  theory  of  tempering  is  beyond  the  present 
purpose.  A  treatise  on  the  subject  will  give  imformation  as  to  the 
tempering  of  steels  of  varying  carbon  content. 

Ref  :  "  Metallography  "  (Sauveur),  p.  242. 

13.  Supersaturated  Carbon  Seeel. — R. No. : 2195.  Analysis: c.c.  1-41 

p.c,  Mn  0*38  p.c.      Treatment:  Annealed.      Mag.:    x  100. 

Small  membranes  of  cementite  surround  the  pearlitic  areas.  The 
above  magnification  gives  a  good  idea  of  the  general  structure.  Higher 
magnification  will  resolve  the  aggregate,  though  the  structure  is  fine- 
grained. 

Ref.  :  "  Value  of  Science  in  the  Smithy  and  Forge  "  (Cathcart), 
p.  83,  fig.  37. 


364  PROCEEDINGS   OF    THE    SOCIETY. 

14:.    Supersaturated    Carbon   Steel. — R.   No.  :    2196.     Analysis : 
c.c.    1-41  p.c,  Mn  0*38  p.c.     Treatment  :   Quenched  800°  C. 
Mag.  :    x  100. 
Structure — very  fine  martensite,  which,  however,  is  just  resolved  at 

this  magnification. 

Ref. :  "  Metallography  "  (Sauveur),  p.  245  et  seq. 

15.  Supersaturated    Carbon   Steel. — R.  No.  :    2197.     Analysis  : 

c.c.   1-41    p.c,   Mn  0-38  p.c.     Treatmetit :  Quenched  800°  C, 
tempered  400°  C.     Mag.  :    x  100. 

Membranes  of  cementite.     The  dark  background  is  pearlite. 

Ref.  :  As  No.  2196. 

16.  Hadfield's     "Era"    Manoanese     Steel.  —  R.  No.-.     2035. 

Analysis:  c.c.  1-2  p.c,  Mn   11*98    p.c.     Treatment:  As  cast. 
Mag.  :    X  150. 

Structure  of  austenite  here  preserved  at  normal  temperature  by  the 
presence  of  much  manganese. 

Ref.:  "Metallography"  (Sauveur),  p.  343,  figs.  320-325. 
"  Micro-Analysis  "  (Stead),  p.  290. 

17.  Hadfield's    "  Era  "    Manganese     Steel.  —  R.    No. :     2030. 

Analysis:  c.c.  1*2  p.c,  Mn  11*98  p.c.      Treatment:  Quenched 
1000°  C.  water.     Mag. :    x  150. 

Polyhedral  grains  characteristic  of  "  gamma  iron."  Samples  possess, 
in  general,  low  elastic  limit,  great  hardness,  wearing  power  and  ductility. 

Ref.  :  As  No.  2035. 

18.  Chromium  Nickel  Steel. — R,  No. :  852.    Analysis  :  c.c.  0  *  70  p.c, 
Cr  2*5  p.c,  Ni  3  p.c.     Treatmetit:  Annealed.     3Iag. :    x  600. 

As  usual  with  quaternary  steels,  the  pearlite  is  very  minute  ;  in  this 
particular,  specimen  is  very  characteristic 

Ref:  "Metallography"  (Sauveur),  p.  353. 
"Metallography"  (Desch),  p.  66. 

19  and  20.  Chromium  Nickel  Steel. — R.  Nos. :  855  and  857. 
Analysis:  c.c  0*70  p.c,  Cr  2*5  p.c,  Ni  3  p.c  Treatment: 
(No.  855)  Quenched  800°  C.  oil ;  (No.  857)  Quenched  800°  C.  oil, 
650°  C.  air.     Mag.  :    x  600. 

A  minute  structure,  somewhat  martensitic  in  855  and  sorbitic  in 
857.  In  industrial  practice  only  steels  low  in  carbon,  nickel,  and 
chromium  are  used.  They  combine  the  good  points  in  nickel  steels 
together  with  those  of  chrome  steels  ;  high  elastic  limit,  ductility,  and 
resilience. 

Ref:  As  No.  852. 


•iCy, 


INDEX 


Adams,  L.  A.,  Phylogeny  of  Jaw  Muscles 

in  Vertebrata,  309 
Agaricia  fragilis,  203 
Agarics,  Exogenous  Species  of,  237 
Aglaophenia,  (JO 

—  pluma,  61 

Aicyonacea,  Spitz bergen,  60 
Alcyonacese,  Northern  and  Arctic,  60 
Alga-Flora  of  Desiccated  English  Soils,  224 
Algae,  Fresh-water,  Photosynthesis  in,  342 

—  Marine,  228,  345 

of  the  Danish  West  Indies,  83 

of  the  Pacific  Coast  of  North  America, 

82 
Sub-Antarctic  and  Antarctic,  343 

—  of  Budeii,  80 

—  of  Japan,  345 

—  of  Santo  Paulo   343 

—  Tertiary  Calcareovis,  84 
Algal  Limestoue  from  Angola,  85 
*'  Algology,  Oceanic,"  84 

Allen,  Bennet  M.,  Thyroid  and  Parathy- 
roid in  Toad  Tadpoles  deprived  of 
Pituitary  Body,  183 

—  Influence  of    Tiiyroid   Extirpation   on 

Toad  Larvse,  183 

—  Results  of  Early  Removal  of  Thymus 

Glands  in  Tadpoles,  305 

—  Parathyroid     Glands     of    Thyroidless 

Toad  Larvse,  305 
Allis,  Edward  Phelps,  Jr.,  Homologies  of 

Squamosal  of  Fishes,  187 
Allison,  Fred.  G.,  Macrostructure  of  Cast 

Steel,  351 
Alloying,  Principles  of,  351 
Alloys,  Spherical  Shell  Crystals  in,  352 
Alveoli,  Pulmonarv,  Dust  Cells  in,  186 

"  Fatty  Cells  "  of,  39       ■ 

Amaroueium,  Tadpole  Larva  of,  312 
Amblystoma,  So-called  Balancers  in,  44 

—  Larvai,  Transplanting  Cerebral  Hemi- 

spheres of,  304 
Amen  tales.     Reproductive     Organs     and 

Phylogeny  of,  213 
Amicronucleate  Oxytricha,  333 
Ammonite  Siphuncle,  312 
Ammophila  heydeni,  192 


Amoebae,  Culture  of,  6^ 

Amphora  inflexa,  81 

Anaphylaxis,  187 

Anchitrema,  201 

Anderson,  Robert  J.,  Principles  of  Alloy- 
ing, 351 

Andrew,  J.  H.,  and  others.  The  Effect  of 
Initial  Temperature  upon  Physical 
Properties  of  Steel,  248 

Andrews,  A.  LeRoy,  North  American 
Sphagnum,  339 

—  Hymenostomum    in     North    America, 

340 
Aneboda,  Fresh- water  Biological  Institute 

at,  82 
Annaudale,   Nelson,    Gastropods    of    Old 

Lake-beds  in  Upper  Burma,  46 
Anolis    carolinensis,   Spermatogenesis    in, 

181 
Anopheles  crucians,  194 
Anthony,   R.,   Development   of   Vascular 

System  in  Embryo  Stickleback,  302 

—  Muscles  of  Bivalves,  315 
Antimony,  Crystalline  Structure  of,  351 
Antipatharians,  West  African,  330 
Antonelli,  G.,  Diatoms  and  Fungi  in  the 

Pontifical  Academy  in  Rome.  226 
Ants,  Argentine,  in  Madeira,  316- 

—  of  Borneo,  317 

—  of  Western  North  America,  316 
Anuran  Amphibia,  Lymphatic  System  of, 

44 

—  Embryos,  301 
Apanteles  glo^neratus,  193 
Apple-sucker.  Head  and  Mouth-parts  of, 

198 
Arachnids  and  Myriopods,  199 
Arber,  Agnes,  Studies  on  tha  Binucleate 

Phase  in  the  Plant-Cell,  1,  23,  124 
Arber,  E.  A.  Newell,  and  F.  W.  Lawfield, 

External    Morphology    of    Stems   of 

Calamites,  337 
Arbor  CoUemhola,  54 
Arcella  dentdia,  62 

—  Influence  ot  Environment  on,  206 

—  Nucleoplasmic  Relations  in,  331 
Archey,    Gilbert,    Craterostigmus    tasma- 

nianus  in  Nev  Zealand,  54 

—  Lithobiomorpha  of  New  Zealand,  55 

2   B 


366 


INDEX. 


Arey,    Leslie   B..   Haversian    Systems   in 

Membrane  Bone.  39 
ArnaiKl,  G.,  Kntyloma  Bavunculi  injurious 

to  Hellehoriis  iihjer,  349 
Aron,  Development  of  Pancreas.  182 
Arrhenunis,  55 
Arthur,  J.  C.  Uredinales  of   Guatemala 

based  on  Oolleclions    by   E.   W.   D. 

Hoi  way,  236 

—  and^  E.  B.  Mains.  Grass  Rusts  of  Un- 

usual Structure,  91 

Arthus,  Maurice.  Immunity  and  Anaphy- 
laxis, 187 

Ascarls  cants,  Refractive  Body  of  Sperma- 
tozoon in,  58 

—  me(ialocep]iaIa,  57 

—  suilla.  57 

Ascidia,  Bactericidal  Processes  m,  45 
Asclepiad,  Trapping  of  Insects  by,  47 
Ascohulus  magnificu^,  345 
Ascoraycetes,  New.  89 

—  Systematy  of  tlie,  88 
Aspen,  Diseases  of,  242 

Aspeniillus   fumig((tm,    A.    nidulans,    A. 

terreuii  sp.  n.,  and  Allies.  232 
Asellidaj,  322 
Asellus,  322 
Asterella,  North  American,  338 

—  South  American,  339 

Athias,  M.,  Interstitial  Cells  in  Ovarv  of 

Bats.  299 
Atkinson,  G.  F..  Selected  Cycles  in  Gym- 

noconia  PecMana,  236 

—  New  Species  of  Inocybe,  238 


B 


Bachniann,  Alois,  Specific  Substances  in 
Leucocytes  of  Immunized  Animals, 
39 

Baclimann,  E.,  Silicicolons  Lich(  ns,  100 

Bacot,  A.,  and  L.  Liuzell,  Incubation  of 
Eggs  of  Horse-lice,  197 

Bncteriii  and  Fungi,  Influence  of  Illumin- 
ating Giis  on,  240 

—  and  Peritheciid  Development,  239 

Budertscher,  J.  A.,  Eosinopbilic  Leuco- 
cvtes  in  Thymus  of  Postnatal  Pigs, 
307 

Bailey,  M.  A.,  Purc'niia  Malvncearum  and 
the  Mycoplasm  Theory,  347 

Baker,  C.  F.,  The  Genus  Krisna,  53 

Baker,  H.  A.,  Quart.zitc  Pebbles  of  Old- 
haven  (Blackheath)  Bals,  353 

Baker.  R.  T..  (.'rystais  in  Australian 
Timbers,  335 

Bidanci;  Sheet,  122 

Baldwin,  AV.  M,,  Monsters  Produced  bv 
X-rays,  181 

Banks,  Charles  S.,  Blood-sucking  Insects 
of  the  Philippines,  47 


Banks,  Charles  S.,  Philippine  Species  of 

Phlebotomus.  51 
Banta,  Arthur  M..  Sex-intergrade  Strain 

of  Cladocera.  323 

—  Sex  Intergrades  in  Cladocera,  323 

—  Selection  with  a  Pure  Line  of  Cladocera,. 

328 

Baretti.  Amalia,  Verticillate  Siphoneae  of 
the  Limestone  of  Yillanova-Mondovi, 
344 

Barratt,  Kate.  Vascular  System  of  Genus 
Equisetum,  214 

Barrows.  W.  M.,  Palpar  Organ  of  Male 
Spiders,  199 

Bartscli,  Paul,  Breeding  of  Cerions,  314 

Basidiomycetes,  Higher,  from  the  Philip- 
pines, 237 

—  Sexuality  in  the,  92 

Bat,  Hibernating,  Secretion  of  Epididymis 

in,  181 
Baylis,  H.  A.,  New  Species  of  Oochoristica 

from  Lizards,  201 
Bed-bug,  196 
Bedford,  G.  A.  H.,  New  ]Mallophaga  from^ 

South  Africnn  Birds,  197 
Bedot,  Maurice,  Development  of  Colonies 

of  A«rlaoplieuia,  60 

—  Variations  of  Aglaoijhenia  phima,  61 
Beer.  Rudolf,  and  Agnes  Arber.  on  Multi- 
nucleate Cells;  An  Historical  Study 
(1879-1919),  23 

Bees,  Hive.  Isle  of  Wight  Disease  in.  315 
— >  Reactions  to  Light  of.  192 
Beloskersky,  Mcola,  New  Peionospoia  for 

Italy  (Feronaxpora  Jiadii  De  Bary)  : 

its  Floral  Deformations  on  Matricaria 

Chaiiiomilla,  231 
Belyea,    H.    C.     Sequoia     Wa>'hiu(jio)iia 

{S.  (j/gaidea),  71 
Bemraelen,  J.  F.  van.  Androgenic  Origin 

of  Horns  and  Antlers.  308 

—  Markings  of  Lepidopterous  Pupae,  319 
Benoit,   J.,  Changes   in    Nucleolar   Sub- 

siance  during  Mitesis,  184 
Bensa ude,    Matliilde,    Sexuality    in    the 

Basidiomycetes.  92 
lienson,    M.,     Cantheliophorus     P>assler: 

New     Records     of     Sigillariostrobus 

(Mazocarpon).  218 
Be'tant.  A,.  Action  of  Sulj^hate  of  Coi)pt-r 

on  I'lankton,  81 
Betchov,    N..  Branchi:*!  Segmentation    of 

Cranial  Nerves.  182 
Bhatia.  B.  Ij.,  Fresh-water  Ciliate  Protozoa 

of  India,  257 

—  Ciliate  of  Lahore,  62 

Bigler.  Walter.  Alpine  l.optoniulida),  55 
Binucleate  Phase  in  the  Plant-Cell,  I 
Biological  Section.  Rej)ort  of  the,  126    • 
Birds.  Mandible  of.  3i)9 
Bi^by.  ii.   K.,  Shoit   Cycle   Urcmyces  of 

North  America,  236 
Bivalves,  Muscles  of,  315 


INDEX. 


367 


Blepharo^pora  te,rediis(iih.ci'h  )  Peyr.,  315 
Blood,  Action  of  Snnke- poison  on.  4/5 

—  as  Food,  43 

—  Pliitelets  in  ^Mammals.  3()(; 
Blood-sucking  Insects  of  the  Philippines, 

47 

Blueberry  Maggot,  Parasite  of,  51 

Bimaparte.  Prince  N.,  Pteridophyta  of 
Indo-China,  76 

Bond,  C.  J.,  Eye- Colour  in  Birds,  303 

Booth,  A.  L.,  Economic  Selection  of  Coal, 
351 

I  Jorge.  O.,  Fresh-water  Algae  from  Santo 
>aulo.  343 

Borgesen,  F.,  Marine  Algge  of  the  Danish 
West  Indies,  83 

Bose,  S.  R.j  Polyporacese  of  Bengal,  237, 
348 

Botrijdiuni  granukitum,  222 

Botryosphseria,  88 

Botrytis  Disease  of  Galanthus,  243 

Boulenger,  Charles  L.,  Nematode  Para- 
sites of  Zebra,  201 

—  Intestinal    Helminths    in    Indians    in 

Mesopotamia.  202 
Bonrdot,  H.,  and  A.  Galzin,  Hymenomy- 

cetes  of  France,  237 
Boutan,  Louis.  Relations  of  the   Gastro- 
pods, 313 
Bower,  F.  O..  Pteridophyta,  73 
Boyer,    C.    S.,   Rare    Species    of    North 

American  Diatomact^ge,  341 
Bracliyphalangy.  Hereditary,  187 
Brain,  Minute  Structure  of  the,  '.Id 
Brammall,  A.,  Microchemical  Methods,  353 
Bresadola,  G. ,  Fungi  from  Saxony,  95 
Bresadola,  J.,  Synonyms  and  Mycological 

Notes,  93 
Bristol,    B.    Muriel.   Gemmae   of    Tortula 
mutica  Lindb.,  220 

—  Alga-Flora  of  Desiccated  English  Soils, 

224 

—  Chlorochytrium,  342 

Broch,     Hjalmar,    West     African     Anti- 

patharians.  330 
Brooks.  F.  T.,  Plant  Sanitation  in  Fruit 

Plantations,  242 
Brown,    Alice    L.,    Influence    on    Frog's 

Inter-renal  Tissue   of   Extirpation  of 

the  Thyroid  and  Pituitary  Primordia, 

182 
Brown,  J.  G..  Rot  of  Date  Fruit,  349 
Browne,   Isabel    M.  P.,  Anatomy   of  the 

Cone  and  Fertile  Stem  of  Equisetum, 

215 

—  Vascular  Strands  of  Equisetum.  216 
Brtnik,  A.,  Fungoid  Infection  of  Eggs,  93 
Bryological  Novelties,  77 

Bubak,  Fr.,  Fungi  in  "Scientific  Results 
of  the  Expedition  to  Mesopotamia," 
95 

—  Fungus  Flora^of  the  Tyrol,  95 

—  Fungi  from  Various  Localities,  96 


Bubak,    Fr..   and  J.    E.    Kabat,    Fungus 

Flora  of  tlui  U\vrol,  95 
—  and  H.  Sydow,  New  Fungi,  89 

from  IJohemia,  89 

Buffalo,  Malarial  Parasite  in  Blood  of.  62 
Buglia,  G.,  Toxicity  of  Extract  of  Eel,  3[0 
Bulgaria  ylatydiscus  in  Canada,  88 
Burr,  H.  Saxton,  Trans])lanting  Cerebral 

Hemispheres  of  Amblystoma  Larva), 

304 
Butler,  O.,  Amount   of  Copper   required 

for  the  Control   of   Phytophthora   in- 

festam,  349 


Calamites,  External  Morphology  of  Stems 
of,  337 

Calkins,  Gary  N..  Renewal  of  Vitality 
through  Conjugation,  208 

Caiman,  W.  T.,  Marine  Boring  Animals, 
357 

Calobryum  Blnmei  N.  ab  E.,  220 

Cameron,  A.  E.,  Oviposition  of  Gastro- 
pMlus  nasalis,  196 

Campbell,  I).  H.,  East  Indian  Hepaticae : 
Calobryum  Blnmei  N.  ab  E.,  220 

Campbellosphsera,  New  Genus  of  Volvo- 
cacese,  222 

CamelidiB,  Blood  Corpuscles  of,  39 

Campylonema  (aJiorense,  a  new  Member  of 
Scytonemacese,  226 

Camus.  L.,  and  E.  Gley,  Cross  Immuniza- 
tion, 186 

Cantacuze'ue,  J.,  Bactericidal  Processes  in 
Ascidia,  45 

Carboniferous  Plant-remains,  73 

Carl,  J.,  Spirobolidse,  55 

Carpenter,  G.  H.,  Arbor  Collembola,  54 

Carreon,  M.,  Ab.-^ence  of  Hind  Legs  in  a 
Pig,  36 

Carter,  J.  Thornton,  Denticles  in  Sword- 
fish,  183 

Carter,  Nellie,  Chloroplasts  of  Desmids  : 
Chloroplasts  of  Cosmarium,  225 

342 

Cartilage  Grafts,  Cellular  Changes  in,  247 

—  Varieties  of, 

Castellani,  Aldo,  Higher  Fungi  in  Rela- 
tion to  Human  Pathology,  241 

Cat,  Parasitic  Spinal  Organism  in  Stomach 
of,  67 

—  Sarcoptid  Mite  in,  321 
Caterpillars   and    Pupse,    Study   of  Setal 

Pattern  of,  320 
Cells,  Symbions  in,  307 
Cementite,  Spheroidal,  Formation  of,  352 
Cerapachyini,  Australian,  316 
Ceratomyxa  acadiensi'<  sp.  n.,  66 
Cerebral  Function  in  Learning,  188 
Cercaria  from  North  America,  327 

2  B  2 


368 


INDEX. 


Cerions,  Brcedinsr  of,  ill 4 

Cesaris-Deniel,  A..  Blood  J'latelets  in 
Mammals,  306 

Chxtoceros  dehile  Cleve,  Auxospore-forma- 
tion  of,  341 

Characese,  Cytoplasm  of,  230 

Charopliyta,  British,  230,  357 

Chatton,  Edouaid,  Trichomonas  of  Guinea- 
pig,  200 

Clienantais,  J.  E.,  Furrows  and  Germin- 
ating Pores,  233 

Chick,  Asymmetrical  Duplicity  in.  35 

—  Casual  Factor  in  Hatching  of,  179 

—  Embryos,  Duplicity  in,  36 

Child.  C.  M.,  Head-generation  in  Plana- 

riaus,  325 
Chilomastix  mesvili  of  Man,  331 
Chiloacyphiis  polyanthus,  338 
Chiton,  Sensory  Responses  of,  190 

—  and  Patella,  Parasites  in,  210 
Ghlorochytrium,  342 

Chromodoris  zebra.  Sensory  Reactions  of, 

190 
Chromosome  Dimensions,  38 
Church,  A.  H.,  Thalassiophyta,  78 

—  Morphology  of  Fungi.  240 
Chytridine  parasite  of  Lucerne,  231 
Cicada,  Food -canal  of,  198 

—  septendecim.  Vision  in,  198 

Ciliate  Infusurians,  Toxicity  of  Acids  to, 
62 

—  of  Lahore,  62 

Citrns,  Pink  Disease  of,  243 
Oadocera,  323 

—  Sex  Intergrades  in,  323 

Clarke,  J.  Jackson,  Mycetozoaand  Disease, 

350 
Clavariopsis  Holt,  237 
Cleghoin,   Alaude    L.,  Vitality  and  Long- 
evity of  Silkworm  Moths  during  Cold 

and  Rainy  St-ason,  318 
"  Climiixodus,"  Dentition  of.  353 
Clover  Stem-rot,  349 
Coal,  Economic  Selection  of,  351 
Coccidse  of  South-western  United  States, 

52 
Coccidian,  New,  i5C> 
Cockle,  Shell  of,  315 
Coe,  W.  R.,  Sex  Dimorphism  in  Nemer- 

tcans,  202 
Coelentera,  Somatic  and  Germ-cells  in,  203 
Coel  plana,  204 
Collett,  M.  E.,  Toxicity  of  Acids  to  Ciliate 

Infusorians,  62 
Collin,  R.,  Supporting  Tissue  of  Human 

Liver,  186 
Collins.  W.  G.,  3:)8 
Colocasia,  212 
Colosi,  G.,  Action  of  Veratrin   on   Snails 

and  Slugs,  47 
Columella  auris  in  Reptiles,  183 
Comstock,  George  F.,  and  \V.  E.  Ruder, 

Eflfect  of  Nitrogen  on  Steel,  249 


Connective  Tissue,  36 

Constantineanu,  J.  C,  New  Roumanian 
IJredineae,  91 

Conversazione,  102 

Cooke,  A.  H.,  Radula  of  Mitridse,  190 

Copeman.  C.  Monckton,  Sex  Determina- 
tion in  Mammals,  184 

Copper  and  Magnetite  in  Copper  Smelter 
Slags,  249 

Coretlira  plumicoinis.  Chromosomes  in 
Larva  of,  320 

Coral  Limestones  of  Barbados,  Extraneous 
Minerals  in,  353 

Coral  linacese,  84 

Coretlira  punctipennis.  Larvae  of.  196 

Cort,  W,  W..  New  Distome  from  Rana 
aurora,  325 

—  New  Cercaria  from  North  America,  327 

—  Adaptability  of  Schistosome  Larvae  to 

New  Hosts.  328 
Corti,  E.,  Lake  of  Segrino,  222 
Cotte,  J.,  Aggregation  of  Spermatozoa  of 

Sea-urchin,  181 
Cotton,  A.  D.  White  Rot  Disease  of  Onion 

Bulbs,  244 

—  Clover  Stem-rot,  349 

Courrier,  M.  R.,  Secretion  of  Epididymis 
in  Hibernating  Bat,  181 

Cowles,  R  P.,  Commensalism  in  Hermit- 
crabs,  55 

Craterostigmus  tasmanianus  in  New  Zea- 
land, 54 

Crawfifch,  Cape,  322 

Crawford,  David  L.,  Jumping  Plant-lice 
of  the  Pala?tropics  and  the  South 
Pacific  Islands,  53 

Crozier,  W.  J.,  Pigmentation  of  a  Polyclad, 
58 

—  and  Leslie  B.  Arey,  Sensory  Reactions 

of  Chromod'.ris  zebra,  190 

Sensory  Responses  of  Chiton,  190 

Cn/phalus  abietis.  Structure  and  Habits  of, 

319 
Cumin ings,  Bruce  F.,  Bed-bug.  196 
Cummiugs,  Harold,  Elating  in  Frogs,  309 

—  Sareoptid  Mite  in  a  Cai,  321 

Currie.  Marv  E.,  Slime-Moulds  of  Ontario, 

350 
Cyeas,  69 

Cyrtopogon  platycerua  Villcneuve,  50 
Cytology,  38 


D 


Da  Fano,  C.  Method  foi-  the  Demonstra- 
tion of  the  Golgi  Ajtparatus  in 
Nervous  and  otlier  Tissues,  157,  251 

Daldinia  concent rica,  Conidia  and  Stroma 
of,  232 

Darwin,  Sir  Horace,  and  W.  G.  Collins, 
A  IJniversal  Microtome,  283 


INDEX. 


369 


Date  Fruit.  Eot  of,  349 

Dau])hine,  A.,  Fibro-vascular  Formations 

in  Monocotyledons,  o36 
Dawson.  J.  A..  Rare  of  Oxvtricha  without 

a  Micron ucleus,  207 

—  Double    Forms  of   an    AmicronucJeote 

Oxiitnrhn,  333 
Debaisieux,  Pai/d,  New  Coccidiau,  C6 

—  New  Species  of  Haplosporidium,  210 

—  Parasites  in  Chiton  and  Patella,  21(t 
Decapods,  Arctic,  56 

Deer-mice,  Variation  in,  308 
Dehorne,  Armand,  (Jhromnsomes  in  Larva 
of  Corethra  jdumicornis.  320 

—  Crystalloids  of    Entamceba  hhtolylica, 

331 
Delachaux.  Th..  Fresh -water  Harpacticids 

from  Peril.  200 
Demodex  Owen,  357 
Denticles  in  Sword-fisli,  183 
Deparia  Moorei  Hook,  75 
Desmids.  Chloroplasts  of,  225,  342 
Diatomacese,  North  American,  341   ' 
Diatomaceous   Earth    of    l.ompoc,    Santa 

Barbara  Co.,  California,  341 
Diatoms,  357 

—  and  Fungi  in  the  Pontifical  Academy 

in  Rome,  226 

—  from  Iceland,  341 

Dictyuchns,  Zoospore  Emergence  in,  85 

DidymeUtna  Iridis,  241 

Diedecke,  H..  New  Fungi  Imperfect!  from 

the  Philippines,  234 
Diemyctylus  viride>'cens,  310 
Dietel.  P..  Pucnnia  obscura  and  Related 

Puccinise  oh  Lazula,  235 

—  Uredo  alpedris  Schriit,  91 

—  ^Ecidial    Form   of    Uromyres    Genistx- 

tinctorlx,  347 
Dionn  spinulosum.  68 
Diplocystis  and  Broomeia,  233 
Diptera,   Sense-oryaus    in    Antennae    and 

Palps  of.  194 
Discomycetes.  232 

—  of  Pertiishire,  234 

Diwany,  Hassan  el,  Blood  as  Food,  43 

—  Nutrition    of   Mammalian  Foetus  from 

Maternal  Blood,  180 
Dixon,  H.  N.,  lihaphidostefiium  coespitosum 
(Sw.)  and  its  Affinities.  221 

—  New  South  African  IM esses,  340 
Dodge.  B.  O.,  Ascobolus  mngnificus,  345 
Dog.  Experimental  Degeneration  of  Testis 

in,  34 

—  Innervation  of  Gonads  in,  34 
DoiT-Perch,  Breeding  of,  305 

Doidge.  Ethel   M.,  South   African    Peri- 
sporiacese.  234 

—  iNIycologicai  Notes,  234 

—  Meliolast^r,    New    Genus     of    Micro- 

thyriaceae,  234 
Domcaster,  L..  Cytology,  38 
Dorety,  H.  A.,  Dioon  fpinulosum.  68 


Dothideae  and  other  Micro  fungi,  89 

Dothideales,  87 

Douglas.  Gertrude  E.,  Exogenous  Species 

of  Agarics,  237 
Dragoiii,      J.,     and      E.    Faure-Fremiet, 

Anomaly  in  0\ary  of  Axcaris  megcdo- 

cephala,  57 
Drew.   A.   H..  Preliminary  Tests  on  the 

Homologue  of  the  Golgi  Apparatus 

in  Plant.-',  295 
Drone-Fly,  Photic  Orientation  in.  195 
Dubreuil,  G.,  and  P.  Lamarque,  Plexiform 

Sphincters    of    Smooth     Muscle     in 

Alveolar  Canals  and  Pulmonary  Acini 

of  ^lamnials.  185 
Duerden.  J.  p]..  Germ-plasm  of  Ostrich,  35 

—  New  Adaptive  Callositv  in  Ostrich,  43 

—  Increasing  Number  of  Ostrich  Plumes, 

309 
Duff,  G.  H.,  Geoglossacese.  233 
Duncan,   F.   Martin,  On   Acari    from  the 

Lungs  of  Macdcus  rhesn>'.  163 
Duodenum,  Structure  of,  in  ^Mammals,  185 
Dupler.    A.    W..   Stamiuate   Strobilus    of 

Taxus  canadensu,  72 


E 


Echiuroid,  New  Genus  from  Great  Barrier 

Reef,  57 
Edmondson,  Charles  Howard,  Crystalline 

Style  in  My  a  arenaria,  314 
Edwards,  P.  W.,  Mosquitoes.  194 
Eel,  Toxicity  of  Extract  of.  310 
Eggs,  Fungoid  Infection  of,  93 
Ehlers,  G.  M.,  New  Genus  of  Tetracoralla, 

60 
Eigenmann,   Carl    H.,    New   Blind    Fish 

from  Texas,  44 
Elliott.  Jessie  S.  Ba\  liss,  Discomycetes,  232 
— -  Formation  of  Conidia  and  the  Growth 

of  the  Stroma  of  DaJdinia  concentrira. 

232 
Endocrine  Gland  in  Uterus  of  Pregnant 

Rat,  186 
Endolymphatic  Sac  and  Duct  in  Dog,  189 
Entamoeba  histohjtica.  Cryst  Jloids  of,  331 
Entijloma   BanunruH   injurious   to   HeVe- 

borus  niger,  349 
Eocronartiuin  musdcola.  237 
Eosinophilic    Leucocytes  in    Thymus   of 

Postnatal  Pigs.  307 
Epithelium,  Fat  in  Pulmonary,  186 

—  Testicular,  180 

Equisetum,  Anatomy  of  Cone  and  Fertile 
Stem  of,  215 

—  Vascular  Strands  of,  216 
System  of,  214 

Erichsen,  J.,  Lichens  from  the  Neighbour- 
hood of  Hamburg,  100 
of  Dune  Rubble  at  Pelzerhaken,  100 


370 


INDEX. 


Eriksson,  Jakob,  Spinacli  Mildew  (Perono- 
spora  Spinaclx),  232 

—  T\v(.  Eussian  Gymnosporangiese,  236 

—  Heteroccisra     and     Specialization     in 

Puccinia  Caricis,  347 
Erysiphe  Polyijoni,  24 1 
Erythrocytes,  68 
Eseher-Kiindig,  J.,  ( 'yrtopoqan  platyceius 

Vilieneuve,  50 
Etching,    Deep,   of    Transversely- fissured 

Rails,  24!) 
Evglena  variahilis,  209 
Kuglenoid,  Photic  Responses  of,  209 
Evans,    Alexander     W.,    New     England 

Hepalicai,  339 
Riccia  from  Peru,  339 

—  North  American  Hepaticse,  339 
.Species  of  Asterella,  338 

—  South  American  Species   of  Asterella, 

339 
Evans,  I.  B.  Pole,  and  Averil  M.  T»ottom- 

ley,  Diplocystis  and  Broumeia,  233 
Exogenese,  Australian,  324 
Eye-Colour  in  Birds,  303 
Eye-piece  Standards,  127 


Faure-Fremiet,  E.,  -  Fatty  Cells "  of 
Pulmonary  Alveolus,  39 

Faust,  Ernest  Carroll,  New  Trematode 
from  Little  Brown  Bat,  58 

Fauvel,  P.,  Madagascar  Polvchsets,  324 

Favia,  330 

Kelt,  E.  P.,  American  Insect  Grails,  192 

Ferris,  Gordon  Floyd.  (JocciJse  of  South- 
western United  States,  52 

—  Mealy  iiugs  of  ( 'alifornia,  52 
Ferrite,  Genesis  of,  249 

Fibiger,  Johannes,  the  Spiroptera  Cancer, 

40 
Fink,  Bruce,  Lichen  Distribution  in  North 

America,  246 
Fish  Food  in  the  Limfjord,  310 

—  New  Blind,  from  Texas,  44 
Fislits,  Indian,  36 

—  Spiracular  Sense-Organ  in,  310 
Fitzpatrick,  Harry  M.,  Cytology  of  F.ocro- 

ndrtium  muxicola,  237 
Flagellates,  Colourless  Series  of,  221 
Flatters  and  Gurnett,  Ltd.,  IMicroscopical 

Preparatio  s,  357 
Flies,  ComtMon,  194 
Flood,  M.    G.,    Exudation   of   Water   by 

Colocasia.  212 
Floridje,  Piirasitic,  S3 
Florin,  Rudolf,  Si)ore-formation   iu  Chilo- 

scyphux  jio/yanthns,  338 
Fly,  Littoral,  Horned,  195 
Foley,  F.  B.,  Differential  Crystallization 

in  a  Cast  Steel  Runner,  248 


Fomes  ((/ipJiuiatus,  242,  347 

—  pinicola.  Spore  Dissemination  on,  240 
Forti,  A..  Pelagic  Flora   of  the  Bay  of 

Quarto  dei  Mille,  83 

—  Mvxophycese  from  Italian  Somaliland, 

226 

—  and  M.  Savelli.  Tuscan  Myxoidivcere. 

226 
Fossil    Plants    from    the    Scottish    Coal 

Meiisures,  74 
FonsDinbronin  cristula,  220 
FrHgoso,  R.  G..  Mycological  Notes.  96 

—  New  Genus  of  Hyjihomyeetes,  235 
Eraser, F.  C,  l^&.x\&.oi Micrometrus  lineatus, 

320 
F; it-Fly  on  Oats,  317' 
Fron  and  Laonier,  Chytridine  parasite  of 

Lucerne,  231 
Fruit   Plantations.  Plant    Sanitation    in, 

242 
Fucus,  E.  dichoiomus  Saur.,  85 
Fuhrmann,  O.,  Swiss  Helminths,  58 
Fumngines,  238 
Fungi  amazonicl  of  E.  Ule,  94 

—  Dothideaceous  and  other  Porto  Rican, 

236 

—  Higher,  in  Relation   to  Human  Path- 

ology, 241 

—  Imperfecti  from  the  Philippines,  234 

—  Indise  Oiientcdis,  97 

—  in  Hens'  Eggs,  93 

—  Morphology  of,  240 

—  New,  89 

—  Northern,  94 

—  of  Bohemia,  89 

Ceylon.  92 

Dalmatia,  95 

Mesopotamia,  95 

Saxony,  95 

the  Baslo^v  Foray,  239 

—  Philippine,  95 
Fungus,  Drain-])locking.  240 

—  Papuani,  96 

Funjius-Flora   of    ^Moravia   anil   Austrian 

Silesia,  97 

Switzerland,  97 

Tasmania,  240 

the  Philippine  Ishtnds,  96  * 

the  Tyrol,  95 

FuL-arium,  235 

Fuse,  G.,  Minute  Structure  of  the  Brain. 

39 


G 


Galiano,  E.  Fernandez,  Histology  of 
'*  Branchial  H<arts  "  of  Sepia,  312 

(ialleria  mdoneUa,  lumiunitv  of  Cater- 
pillais  of,  49        ♦ 

Galls,  Insect,  American,  192 

—  Plant,  of  Philippines.  193 


INDEX. 


371 


•Galligan,  F.  1'.,  and  J.  J.  Curran,  Distin- 

guishiug  Lead  in  Brass  and  Bronze, 

352 

Galloe,  Olaf,  Lichen  Flora  of  Iceland,  o50 

Gardiner,  C  I.,  Silurian    Rocks  of  May 

Hill,  :{o:{ 
GiiiHsner,  G.,  Infection  of  Cereal  Rusts,  92 
G aster omyeetes  Zei/lanicas,  92 
duArode^  parasitirum  Korotueff,  205 
Gastrophihis  ncn^alis,  Oviposition  of,  196 
Gastropods,  HIH 

—  of  Upper  Burma,  4(; 

Gatonby,  J.  Bronte.  The  Relationship 
between  tlie  Formation  of  Yolk  and 
the  ^litoehondria  and  Golgi  Appa- 
ratus during  Oogenesis,  129 

—  Further  Notes   on   the  Oogenesis  and 

Fertilization   cf    Grantia    compressa, 

'111 
•Gauges,  127 

Giiuiiann,  Ernst,  I'eronospora,  86 
Gautier,    01.,    Emergence    of    liarvse    of 

ApcDiteles  glomemtus  from  Caterpillars 

of  Pier  is  hrassicx.  193 

—  and  Ph.  Riel,  Food  of  Caterpillars  of 

rieri?  and  P^uchloe,  193 
Gednelst,  L.,  New  Species  of  Anchitrema, 

201 
•Gemmil,  James  F.,  Sea-anemones,  59 

—  Mesenteries  in  Urticina  crasHicornis,  202 

—  Ciliation  of  a  Leptomedusan,  203 

T—  Ciliary  Action  in  Fleurobracliia  piJeus, 

205 
•  Geoglossaceas,  233 

Georgevitch,  Jivoin,  Mijxidium  gadl,  334 
Germ-nuclei  in  Cleavage  Stages  of  Crypto- 

branchus  aUegheniensis,  179 
Gilchrist,  J.  D.  F.,  Life-history  of  Cape 

Crawfish,  322 
Gilligan,    A.,   Petrography   of    Millstone 

Grit,  353 
Giolitto,  Frederico,  Genesis  of  Ferrite,  249 
■Gliose,  S.  L.,  New   Species  of  Uronema 

from  India,  224 

—  -  Campylonema  lahorense,  a  new  ^lember 

of  Scytonemacese,  226 
Glceosporium    Tremnlx    and    Glceosporium 

Fopuli-cdbse,  346 
•Glomeridse,  55 

GlyphotxHus  punctatoUneatus,  51 
Gnetuui  and  Angiosperms,  69 
Gobies,  301 
Goebel,  K.,  Morphological  and  Biological 

Observations,  98 
Goette,  Asexual   Multiplication  of  Micro- 

hi/dra  ryderi,  331 
Goldsmitli,  W.  M.,  Sterility  of  Mules,  34 
Ciiromosomes  in  Tiger-beetles,  49 


Golgi    Apparatus   in 
Tissues,  157 

in  Plants,  295 

Grabliam,     M.    C. 
Madeira,  316 


Nervous  and  other 


Argentine     Ant    in 


Graham-Smith.  G.  S.,  Common  Flies.  194 
Grand,  F.,  Fat  in  Pulmonary  Epithelium, 

186 
Grantia  compressn.  Oogenesis  and  Fertili- 
zation of,  277 
Grave, Caswell,  Tadpole  Larva  of  Amarou- 

cium,  312 
Gray,    J.,    Relation    of    Spermatozoa    to 

Certain  Electrolytes,  33 
Greaves,    R.    H.,    Temper-britileness    of 

Nic-kel-CluOMiiuni  St(  els,  351 
Grebe.  C,  Biology  and  Ecology  of  Mosses, 

77 
Grebelsky,  F.,  Position   of  the  Sorus  in 

Urerliuea3,  90 
Gregarines,  Chromosome  Cycle  in,  65 

—  New,  66 

Grove,  A.  J..  Head  and  Mouth-parts  of 

Apple-sucker,  198 
Groves,  James,  British  Charophyta.  357 

—  and   G.    R.    Bui  lock- Webster.    British 

Charophyta,  230 

Guieysse-Pellisier,  A.,  Dust  Cells  in  Pul- 
monary Alveoli,  186 

Guilliermond,  A.,  Mitochondrial  Origin 
of  Plastids,  212 

Guinea-pig,  Ear  of,  189 

Gymnoconia  Peckiana,  Selected  Cvcles  in, 
236 

Gymnosporangieae,  Two  Russian,  236 


H 


Hseberli,  Adolf,  Fauna  of  a  Moor,  311 

Hahn,  Glenn  Gardner,  Phomopsis  juni- 
perovora,  235 

Hanson,  D.,  and  H.  E.  Hanson,  Nickel - 
Iron  Alloys,  352 

Hanson,  F.  B.,  Development  of  Shoulder- 
Girdle  of  Pig,  303 

Haplosporidiiun,  21u 

Hargitt,  C.  W.,  and  L.  :\L  Hickernell, 
Food-canal  of  Cicada,  198 

Hargitt,  George  T.,  Somatic  and  Germ- 
cells  in  Coelentera,  2U3 

Harpacticids.  Fresh-water,  from  Peru, 
20U 

Harris,  D.  Eraser,  Physiological  Inertia 
and  Physiological  Momentum.  186 

Harrison,  J.  B.,  and  C.  B.  AV,  Anderson, 
Extraneous  Minerals  in  Coial  Lime- 
stones of  Barbados,  853 

Hartley,  Carl,  and  Glen  G.  Hahn.  Diseases 
of  Aspen,  242 

—  and  others,  MouMing  of  Snow- 
smothered  Nursery  Stock,  244 

Haswell.  W.  A.,  Australian  Exogeneae, 
324 

Haughwout.  F.  G.,  and  W.  do  Leon, 
Ingestion  of  Erythrocytes  bj  a  ^Monad 
associated  with  Dysentery,  63 


372 


INDEX. 


Hanpt,  Arthur  W.,  Fossomhronia  cristula, 

220 
Haversian    Systems  in   Membrane   Bone, 

39 
Hawkins.  L.  A.,  and  E;  B.  Harvey,  I'ara- 

sitism    of   Pi/thium    deharyanuvi    on 

I'otato  Tuber,  242 
Hefner.  Robert  AV.,  Arcella  dentata,  62 

—  Influence  of  Environment  on  Arcella, 

206 

—  Nucleoplasmic    Relations    in    Arcella, 

331 
Heilbruun,  Ij.  V.,  Division  Spindle  in  Sea 

Urchin  Ova.  329 
Helmint lis.  Intestinal,  in  Indians  in  Aleso- 

potamia.  202 

—  Swiss,  58 

Hclvdla  elastica,  Spore  Discharge  in,  233 
Herdman,  W.  A.,  Quantitative    Estimate 

of  Littoral  Animals,  311 
Heredity,  354 
Hepaticfe,  New  England,  339 

—  North  American,  339 

Herlant,    M.,    Parthenogenetic    Develop- 
ment and  what  it  Suggests,  306 

—  Hermaphroditism    in    a    Sea    Urchin, 

329 
Hermaphroditism  in  Sea  Urchin,  329 
Hermit-crabs,  55 
Herre,  Albert  C,  Hints  for  Lichen  Studies,  j 

350  : 

Hesse.  O..  Constituents  of  Lichens,  99  I 

Hickson,  Sydney  J..  Sea-pens.  203 
Hiuley,  Ruth,  Turbellarians  of  ^Mississippi 

liasin,  202  1 

Hiley,  W.  E.,  Fungal  Diseases  of  Common   | 

Larch,  244  .  ' 

Hilton,   A.    E.,    Capillitia  of    ^lycetozoa,  j 

67 
Hirst.    Stanley,  Injurious  Arachnids  and 

Alyriopods.  199 

—  Demodex  Owen,  357 

Hitchcock,    R.,    DiflFerential    Staining    of 

Cytoplasm  of  Charnceae,  2:!0 
Hodgetts.  William  J.,  Roya  anfjlica  G.  S. 

West,  a  nev,'  Desniid,  224 
Hogben,     L.   T.,  Reduction    of   Jugal  in 

Mammals,  43 

—  The  Problem  of  Synapsis,  269,  358  | 
Hobnel.    Fr.    von,    Cla:>sification    of    the   , 

rhacidiates,  86 

—  ]Mycolr)gy.  96 

—  ]Mycological  Contributions,  238 
Fragments,  238,  348 

Hollande,    A.    Cli.,    I'oison    of    Predatory 

Hymenoptera,  48 
Holloway,  J.  E.,  New  Zealand  Species  of 

the  Cenus  Lycojjodium,  216,  217 

—  rrothallus  and  Young  IMant  of  Tmesip- 

teris,  218 
Hoi  way,  E.  W.  D.,  236 
Honda,   K.,  and  S.   Saito,   Formation    of 

Spheroidal  Comentite,  352 


Honda,  K..  and  T.  Murakami,  Strnctural 
,  Constitution,  Hardening  and  Tem- 
pering of  High-S]ieed  Steel  contain- 
ing Chromium  and  Tungsten,  248 

Graphitization        of      Iron-Carbon 

Alloys,  352 

Honey-ants,  Australian,  48 

Horns  and  Antlers,  Androgenic  Origin  of, 
308 

Horse-lice.  P^ggs  of,  197 

Houssay,  B.  A.,  and  A.  Sordelli,  Action  of 
Snake-poison  on  Blood,  43 

Howe,  31.  A.,  Tertiary  Calcareous  Algae, 
84 

—  Monosporangial  Discs  in  Genus 
Liagora,  227 

Hue,  A.,  New  Lichens,  98 

Hughes,  W.  E..  Some  Defects  in  Electro- 
deposited  Iron,  249 

Huyghens,  Christian,  Traite  de  la  Lumiere, 
357 

Hydroids  of  Ingolf  Expedition,  330 

Hylmo,  D.  E..  Sub-Antarctic  and  Antarc- 
tic Marine  Algje  (Chlorophycese),  343 

Hymenomycetes  of  France,  237 

Hymenoptera,  Poison  of  Predatory,  481 

Hymenostomiun  in  North  America,  340 

Hyphomycetea,  235 

Hypocreaceae,  86 


Immunization,  Cross,  186 
Inocybe,  2:58 

Interstitial  Cells  in  Ovary  of  Bats,  299 
Intestinal  Glands  in  Larval  Insects,  50 
Iron,   Electro-deposited,  some  Defects  in, 
249 

—  Indian,  352 

—  Carbon  Alloys,  Graphitization  of,  352 
Isaacs.  Raphael.    l)eveloi>ing    Connectivt^ 

Tissue,  36 
Ixodes  ncinns.  Spermatogenesis  in,  200 
Ixodidse,  Sexes  in,  199 


J 


Jaa}\  Otto,  Fujigi  of  Dalmatia.  95 
—  Fungus-Flora  of  Switzerland,  97 
Jackson,  C.  M.,  and  C  A.  Stewart,  Effect 

of  Starving  Young  Rats,  304 
Jackson.  H.  S.,  North   American   Ustlla- 

ginales,  347 
Jacobi,  C.,  German  and  Austrian  Lichens 

as  Food  and  Fodder,  '98 
James,  1{.  W..  and  N.  Tnnstall,  Crystalline 

Structure  of  Antimony,  351 
Jaraesoii.  A.  Pringle,   Chromosome   Cycle 

in  Gregarines,  65 


INDEX. 


373 


Janet,  C,  Botrydium  qramdatum,  222 

Jaw  Muscles  in  Vertebrat;i,  Pliylogeny  of,    \ 

3(»:>  ! 

Jensen,   P.    Bovseu,    Fisli     Food    in    the    I 

Liinfjord,  310  | 

Johnson,  C.  E.,  Development  of  Thymus,    I 

Paiathyroiil     and     Ultimo-branchial 

Bodies  in  Turtles,  182  i 

.lohiistou,   T.    Harvey,  and  O.  W.  Tiegs,    I 

New    Eehiuroid   Genus    from    Great    | 

Barrier  Keef.  57 
Jolly.  J.. Blood  Corpuscles  of  Camelidfe.  39 
Juday,Chancey,  Larvae  of  ('oiethra  puncti- 

'penniSj  196 
June   Heetle,  Bacterial  Disease  of  Larvae 

of,  320 

K 

Kamj^nieier,  Otto  F.,  Lymphatic  System 

of  Anuran  Amphibia,  44 
Kavina;  K.,  Ramification  of  Mosses,  7<I 
Koilin,  ]>..  Ne.v  Gregarines,  CS 

—  Flies  in  Snails.  19o     - 

—  andG.  H.  F.  Nuttall,  Hermaphroditism 

in  Lice.  53 
Keissler,    K.    von,    Botrytis    Disease    of    i 

Galanthus,  243 
Kelps.  Nitrogen  in.  85  i 

Kempton,  F.  E.,  Origin  and  Development    ! 

of  the  Pycnidium,  9(»  j 

Keuchenius,  P.   E,,    Urticati ng   Hairs   of    1 

Pa  rasa  lepida,  317 
Kidston,    R ,    Fossil     Plants     from     the 

Scottish  ( "oal  Pleasures.  74 

—  and    W.    H.    Lang,    L'hynia    Gioynne- 

Vaughani  Ki<lston  and  Lang,  73 
Kii'kpatrick,    R.,"  Fauna    of    Water-pipes 

and  Keservoirs,  45 
Kofoid,  Charles  A.,  Noctiluca,  207 

—  and    Olive  Swezy^  Fission    in  Tricho- 

monads,  63 

Chiloiiiastix  mesnili  of  ^Nlan,  331 

Komai.  Taku,  Ccjcloplana,  204 

—  Gastrndex  paia><iticuni  Korotncff,  205 
Krisna,  53 

Knntz,  Albert,  Degeneration  of  Testis  in 
Dog,  34 

—  Innervation  of  Gonads  in  Dog,  34 
Kuwada,  Y.,  Chromo-omes  in  Zea  Mais, 

335 

L 

Laboulbeniales,  87 

Lacoste.  A.,  Sphincter  ^Muscles  in  ^lan, 
185 

Laguesse,  E.,  ^Mastocvtes  in  White  Rat, 
184 

Lai  ng,  R.  ]M.,  Norfolk  Island  S]jecie8  of 
Pteris,  219 

Laminarias  of  tlie  Frencli  Coasts.  344 

Lane,  H.  H.,  Early  Development  of  Peri- 
pheral Nerves  in  Vertebrate  Embryo, 
182 


Larcli,  Common,  Fungal  Diseases  of.  244 
Lashlcy,    K.    S.,    Cerebral    Function    in 

Learning,  188 
Latimer.    Homer    B.,    Lateral     Line     of 

Pohjodnn  >(pathuh(.  39 
Latta,  John  8..  ^Morphology  of  So-called 

Balancers  in  Amblystoma,  44 
Laurens,   Henry,  and  Henry   D.   Hooker, 

Jun.,  Sensibility  of  Volvox  to  Light, 

334  '  • 

Lawson,    A.     Anstruther,    Prothallus    of 

Tmesipteris  tannensis,  75 
Lead  in  Brass  and  Bronze,  352 
Lebedinsky.   N.    G.,  ^Mandible   of  Birds, 

309 
Lecaninm  persiae,  Ceriparous  Cells  in,  52 
Lee,  H.   Atherton,  and  Harry    S.  Yates, 

Pink  Disease  of  Citrus,  243 
Legendre,     J.,     Dipterous      Parasite     of 

Peaches,  50 
Leigh-Sharpe,  W.     H.,    New    Species   of 

Lernseopoda.  56 
Lemoine,  .Madame  I*aul,Melobesie8e  of  the 

Danish  Antilles.  84    . 

—  Corallinaceee,  84 

Lepidoptera,  Classification  based  on  Pupal 
Characters.  318 

—  ^Metamorphosis  of,  318 
Lepidopterous  Pupae.  319 
Leptogorgia  irramosa  (Greig),  330 
Leptomedusan,  Ciliation  of,  203 
Leptoniulidae.  Alpine,  55 
Lornaeoporla,  New  Species  of,  56 
Lesage,  P.,  Lunularia  vulgaris,  78 
Lettau,  G.,  Lichenographia  of  Thiiriugen, 

246 
Leucocytes  of  Immunized  Animals,  39 
Lice,  197 

—  Hermaphrorlitism  in.  53 

Lichen  Distribution  in  North  America,  246 

—  Studies,  Hints  for,  350 
Licheiies  Tifinenser.  Exsic.  245 
Lichen-Flora  of  Hertfordshire,  99 
of  Iceland,  350 

of  Kazan.  99 

Ivichenographia  of  Thiiringen,  246 
Lichenology.  Sliort  History  of,  245 
Lichens,  Constituents  of,  99 

—  (xerman  anl  Austrian,  98 

—  in  A.  Giiizherger,  98 

—  in  Polarized  Light.  100 

—  of  the  Basl  .w  Foray,  245 

—  or  Epping  Forest,  245 

—  irom  Hamburg,  100 

—  of  Patagonia  and  Terra  del  Fuego,  100 

—  of  Pelzerhaken,  100 

—  of  Transcaucasia,  245 

—  Silicicolnus,  100 

Lichen-tiiallus.  Algae  and  Hyphae  in  the, 

100 
Lietzensee,  near  Berlin,  82 
Lim,  R.  K.  S.,  Parasitic  Spinal  Organism 

in  Stomacii  of  Cat,  67 


374 


INDEX. 


Limpet,  Homing  of,  191 

Liud,  J.,  Northern  Fungi,  94 

Link.    K.    K.,    and    3Iax    W.    Gardner, 

Market  Pathology  of  Vegetables,  243 
Lister,  (t.,  Mycetozoa  from  Cornwall,  246 

found  during  the  Baslow  Foray,  246 

Lithobiuraorpha  of  Xew  Zealand,  55 
Littoral  Animals.   Quantitative   Estimate 

of,  •'.  1 1 
Liver,  Human,  Supporting  Tissue  of,  186 
Liverworts  of  Germany,  etc.,  78 
Lizard,  Green,  Hermaphrodite,  18H 
Lloyd,  C.  G.,  Myeological  Notes,  239,  348 

—  Large  Pyreuomycetes,  345 

Loeske,  L.,  Scapania  paludiroJa  Loeske  et 
C.  Mull.  77 

Longman.  Heber  A.,  Factors  in  Variation, 
305 

Luoas,  W.  J.,  British  Orthoptera,  321,  357 

Ludwig,  0.  A.,  Influence  of  Illuminating- 
Gas  on  Bacteria  and  Fungi,  240 

—  and  C.  C.  Rees,  Uredinium  in  Fuccinia- 

strum  Agrimonice,  235 
Luisier,  A..  Mosses  of  Madeira,  340 
Lumbricidse,  Stomodseum  of,  56 
Lumiere,  Auguste.  Theory  of  .Symbions  in 

all  Cells,^  307  ' 
Lumiere.  'J'raite'  de  la,  357 
Lunularia  vulgarh,  78 
Luyk,  A.  van,  Gloeospoiium  Tremulse  and 

Gloeosporium  FopuU-albfc,  34t> 
Lycopodium  lucirhduiii.  Bulbils  of,  338 

—  3Iethodof  Quantitative  Microscopy,  169 

—  New  Zealand.  217 
Lynvintria  clispar,  49 


M 


Marxicus  rhesus,  Acari  from  the  Lungs  of. 

163 
]MacBride,   K.  W.,   Double  Hydrocoele  in 

Sea  Urchin  Larvae,  328 

—  The  :Method  of  Evolution,  305 
^McC'ullum.   A.  W.,  Bulgaria  platydiscus 

in  (^'anada,  88 

Mclndoo,  N.  E.,  Olfactory  Sense  in  Orthop- 
tera, 196 

^r-Intosh,  W.  (\,  Sabellids  and  Serpulids, 
200 

Macrosporium  from  Tomatoes,  243 

^IcVVilliam,  A.,  Indian  Iron  ^Making  at 
Mirjati  Chota,  Nagpur,  352 

3Iaier.  Charles  G.,  and  G.  G.  Van  Arsdale, 
Copper  and  Magnetite  in  Copper 
Smelter  Slags,  249 

.Mallock.  A..  Growth  of  Trees.  336 

Mallojdiaga  (rom  Formosan  Birds,  197 

—  New.  from  South  African  Birds,  197 
Man)malian  Foetus,  Xutrition  of,  ISO 
Mammals,  Reduction  of  .lugal  in,  43 
Marine  Boring  Animals,  357 

—  Flora*  of  Pacific  Coast,  228 


Marshall,  Ruth,  New  Species  of  Arrhen- 
urus,  55 

Mast,  S.  O.,  Photic  Orientation  in  Drone- 
Fly,  195 

—  Vision  in  Cicadd  sejjtendecini,  198 

—  Photic  Rpspouses  of  a  Euglenoid.  209 

—  EngJena  variahilis.  209 
Mastocytes  in  White  Rat,  184 

Masui.  K.,  Spermatogenesis  (jf  Horse,  300 

in  Ox,  300 

INIattcotti,  A.,  Potamon  edule,  56 
Matthai,  George,  Structure  of  Favia,  330 
Maublanc,  A., Brazilian  M\cological  Floia, 

235 
Mayor,  James  \V..  ('eratomyxa  acadiensis 

sp.  u..  66 

—  Agaric ia  Jraijilis,  203 

Mazza.  A.,  Oceanic  Algology.  84,  227 

Mealy  Bugs  of  California^  52 

Meek,  C,  F.  U..  Chromosome  Dimensions, 

38 
Meinecke,  E.  P.,  Facultative  Heteroccism 

in  Feridermium  cerehrum   and  Peri- 

dermium  Harlcnessii,  347 
Meli,  R..  PterU  aquilina  L.  in  the  Tufa  of 

the  Villa  Torlonia  at  Frascati,  219 
Meliolaster,  New  Genus  of  ^licrothyriaceae, 

234 
Mellor,    Thomas    K.,  Common   Diatoms, 

357 
Melobesiere  of  the  Danish  Antilles.  84 
Membrane  Bone,  Development  of.  36 
3Ienzi,  J.  J.,  Stomodjeum  of  Lumbricidse, 

5«> 
Menzies.  James.  Discomycetes  of  Perth- 
shire, 234 
Mercier,  L.,  Horned  Littoral  Fly.  IV'S 

—  Venation  of  Panorpa  communis.  196 
Mereschkovsky,    Const..    Lichen-Flora  of 

Kazan,  99 

—  Parmelia  cdmtschddalis,  99 

—  Lichenet  Tirinenses  Exsic.  245 
Metallurgical  Specimens,  359 
Metalnikoff.  S.,  Immunity  of  Caterpillars 

of  (i  idler  ia  melonella.  49 
Metamerism,  Muscular,  37 
Metz,  C.  W.,  Anopheles  crucians,  194 
Mica,  Electrical  Conductivity  of  Copper, 

fused  with.  351 
iMieroclien\ical  ^lethods.  353 
Microhydra  ryderi,  Asexual  3lultiplication 

of,  331 
Micro  til  etrw  lineatua.  Larva  of,  32(' 
-Microtome,  A  Universal,  283 
JMillei-,  A.  \l..  Chemical  Heat-tieatments 

for  Alloy  Steels,  351 
INIiller,  W.  L..  Polyxlic  Stem  of  C  yeas.  69 
jNIillstone  (irit.  Petrography  of,  353 
Minnich.  Dwiuht  E.,  Reactions  of  Bees  to 

Light,  P.>2 
Mirande,  Robert.  Zoophigus  iiisiaamt.  231 
3Iitosis.  Chanses  in  Nucleolar  Substance 

during.  184 


INDEX. 


375 


Mitridso,  Tviidula  of,  190 
^lohr,  Otto  L.,  and  Cbr.  Wriedt,  Heredi- 
tary Brachyplmlangy,  187 
]Molander,  Arvid  R.,  Arctic  Decapods,  56 

—  Northern  and  Arctic  Alcyonaceae,  60 

—  Spitzbergen  Alcyonacea.  60 

—  Leptogorgia  irramosa  (Grieg),  380 
MnidJia  cinerea.  Biologic  Forms  of,  21:2 
Monocotyledons,    Fibro- vascular    Forma- 
tions in,  336 

Monosporangial  Discs  in  Genus  Liagora, 

"I'll 
Monsters  Produced  by  X-rays,  181 
^loi'ypenny,  J.  H.  G.,  Structure  of  Cbro- 

mium  tSteels,  248 
31onziols  and  Others,  Pentastomid  iu  Man, 

200 
^loore,   P).,   and    T.    A.   Webster.   I'hoto- 

synthesis  in  Fresb-water  Algfe,  342 
^lorgan,  T.  H..  Heredity,  304 
^losher.  Edna,  Classification  of  Lepidop- 

tera  based  on  I'upal  Characters,  318 

—  Metamorphosis  of  Lepidoptera,  318 
3Iosquitoes,  194 

Moss  Exchange  Club,  341 
3Iosses,  Biology  and  Ecology  of,  77 

—  Ecological  Succession  of,  339 

—  of  Madeira,  340 

—  liamifieation  of,  16 

—  South  African,  340 

^Moulding  of  Snow-stnothered  Nursery 
Stock,  244 

Moulds,  Preservation  of  Artificial  Cultures 
of,  239 

Mules.  Sterility  of,  34 

Miiller,  K.,  Liverworts  of  Germany,  etc., 
78 

:\Iultiniicleate  Cells,  23 

3Iuratet.  L.,  Trichocepiialus  in  Fiver  of 
Bat,  201 

^luiray,  J.  A.,  Cellular  Changes  in  Carti- 
lage Grafts,  247 

IMurrill,  William  A.,  Another  New  Truffle, 
346 

—  Field  Meeting  of  Pathologists,  93 

—  Fungi,  94 

^Muscid  Larva  Sucking  Blood  of  Nestlings, 

320 
IMuscids,  Larval,  Dorsal  Blood-vessel  in,  50 
3Iusele,  Blood-coloured,  in  Fish,  307 

—  Smooth,  Plexiform  Sphincters  of,  185 

—  Fibres.  Striped,  185 

Muscles,  Pelvic,  Comparative  Study  of,  309 
Mutational  and  "  Recapitulatory  "  Cliarac- 

ters,  306 
Mya  arenaria.  Crystalline  Style  in,  314 
^Nlycetozoa,  246 

—  and  Disease,  350 

—  Capillitia  of,  67 

—  from  Cornwall,  246 
Mycological  Flora,  Brazilian,  235 
Mycotheca  germanica,  93 
Mycotorula  turhidans  Will.  346 


Myxidiiim  ga'li,  334 

Myxophycese.  226 

—  from  Italian  Somali  land,  226 


N 


Nagel,  K..  Carboniferous  Plant-remains,  73 
Xageotte,  J.,  and  L.  Guyon,  Regenerative 

Growth  of  Striped  Muscle-filn-es  after 

Traumatic  Lesion,  185 
National  Physical  Laboratory  Report  for, 

1919,  357 
Naumann,  E.,  Biological  Sanii^les  of  Water 

from  the  deeper  Water  Strata,  82 

—  Fresh-water    Biological     Institute    at 

Aneboda,  82 

—  Lietzensee  near  Berlin,  82 
Navicula  and  Cyinbella,  80 

Neal,  H.  V.,  Neuromeres  and  Metameres, 

37 
Neger,  F.  W.,  Fumagines.  238 
Nematode,  New,  from  a  Baboon,  58 

—  Parasites  of  Zebra,  201 
Nemerteans.  Sex  Dimorphism  in.  202 
Nerves,  Cranial,  Branchial  Segmentation 

of,  182 

—  Peripheral,  Pearly  Development  of.  in 

Vertebrate  Embryo,  182 
Xeuromeres  and  ^Metameres,  37 
Neurosoria  pteroides  (R.  Bi.)  Mett..  75 
Nickel-Iron  Alloys,  352 
NienburiT,  W.,  Algse  and  Hyphse  iu  the 

Lichen-thallus,  100 
Nishi,    S.,  Comparative    Study  of  I'elvic 

^luscles.  309 
Noctiiuca,  207 
Nor((enski('31d,    Erik,   Spermatogenesis  iu 

Ixodes  ricinas,  200 
Norris,    H.    W.,    and    Sally    1\    Hughes, 

Spiracular    Sense-Organ    in    Fishes, 

310 
North,  F.  J.,  On  Syniogothrysis  Winehell, 

and    Certain   Carboniferous    Brachio- 

poda referred  to  Spiriferinad'Orbignv. 

353 
Xorthrup,  Zae,  Bacterial  Disease  of  Larv* 

of  June  Beetle,  320 
Nuttall,  George  H.  F.,  Lice,  197 

—  Sexes  in  Ixodidse,  199 


O 


O'Conuell,  ]Marjoi-ie,  Orthogenetic  De- 
velopment of  Costae  in  I'erisphinctinae, 
45 

O'Connor,  F.  W.,  Intestinal  Protozoa,  207 

Okada,  Yaichiro,  New  Japanese  Polyzna. 
328 

Okuda,  Yuzuru,  Blood-coloured  Muscle  in 
Fish,  307 

Oligochaets,  North  American,  57 


376 


IXDEX. 


Onion  Bulbs,  White  Rot  Disease  of,  244 
Oochoristica  from  Lizards,  201 
Oogenesis,  Kelationship  between  the  For- 

raation  of  Yolk  and  the  ^litochondria 

and  Golgi  Apparatus  during,  129 
Ophio;i;loss;tCe8e,  IMt-clo.sing  ^lembrune  in, 

218 
Optical    Instruments,    Standardization    of 

the  Elements  of,  357 
Orthoptera,  British,  321,  357 

—  Olfactory  Sense  in.  196 

Osborn,  Herbert,  3l(  ado-.v  I'lant-bng,  51 
Ostracods,  Cave,  324 
Ostrich,  Germ-plasm  of.  35 

—  Xew  Adaptive  Callosity  in,  43 

—  I'lumet-,  Increasing  Number  of,  309 
0strup,  Ernst.  Fresh- water  Diatonis  from 

Iceland,  341 
Overholts,    L.   O.,   INIvcological    Notc^s  for 

1919,  348 
Owen,  M.  N.,  Skin  Spot  Disease  of  Potato 

Tubers,  349 
Oxus,  5o 
Oxytricha  without  a  Micronucleus.  207 


Painter,  T.  S.,  Spermatog(uesis  in  Anolis 

caroH^ensis,  181 
Pancreas,  Development  of,  182 
Fanorpa  comnamis.  Venation  of,  196 
Pantel,  J,.  Dorsal  Bloo  1 -vessel  in  Larval 

Muscids,  50 

—  Intestinal  Glands  in  Larval  Insects,  50 
Paramoecia  in  Sterile  Culture  Medium,  210 
Parasa  lejiida,  Urtieating  Hairs  of,  317 
Parasitism    of    Pytlouiu    dthariianum    on 

Potato  Tuber,  242 

Parasitized  Fish,  189 

Paravicini,  Eugen,  Behaviour  of  the 
Nuclei  in  Reproduction  of  Smut 
Fungi.  91 

Paravicini,  Z.,  Fusaiiinn,  235 

Pardo,  Luis,  Fresh- water  Plankton  from 
Gandia  (Valencia),  222 

Paris,  Paul,  Cave  Ostracods,  .■>24 

I'armelin  cdmlsrhadalis,  99 

Parodiella,  (♦() 

Partheuogenetic  Development,  30(1 

Paseher,  A.,  Colourle.-^.s  Series  of  P^'lagel- 
lates,  221  • 

Patch,  p]dith  M.,-]Midge  Infesting  Pota- 
toes, 51 

—  I'syllid  Gall  on  Juncus,  51 
I'atouillard.  N.,  Clfivariop-is  Holt,  237 
Paulson,  Robert,  I, ichen-Flora  of  Hertford- 
shire, 99 

—  and   Percy   (i.    Th()nip.,on.   Lielieus  of 

Eppintr  Forest.  245 
Peaclies,  Dipterous  Parasite  of,  50 
Pelagic  Flora  of  the    Hav  of  Quarto  dei 

Mille,  83 


Pentastomid  in  Man,  200 

Peridermiuru  cerebrum  and  Peridermium 

Harknesaii,  Facultative    Heteroccism 

in,  347 
I'eridinese  of  New  South  Wales,  222 
Perisphinctiuse.  Cost£e  in,  45 
l*erisi)oriace8e.  South  African,  234 
Periwinkle,  Breeding  and  Habits  of,  313 
Peronospora,  86 

—  New,  for  Italy  (Peronospora  Radii  De 

Bary),  231 

Peters.  R.  A.,  Nutrition  of  Protozoa : 
Growth  of  Paranlcecia  in  Sterile  Cul- 
ture Medium,  210 

Petersen.  C.  G.  Joh.,  Development  of 
Gobies,  301 

Petch,  T.,  Ceylon  Fungi.  92 

—  Gasttroiiiycetes  ZeyUnticx,  92 
I'ethybridge,  G.   H.,  and  H.  A.  Lafferty, 

Disease  of  Tomato  and  other  l*lants 
caused    by    New  Species    of    Phyto- 
phthora,  243 
Petraek,    F.,    Fungus-Flora   of   jMoravia 
and  Austrian  Silesia,  97 

—  Myctdogical  Notes,  348 

Peyronel,     B.,     Blepharo^pora     terrestris 

(Sherb.)  Peyr.,  345 
Phacidiales,  86 

Philocopra  eoeruleotecta  Rehm  sp.  n.,  232 
Phlebotomus,  Pliilii)pine  Species  of,  51 
Phomopsis  jiiniperorora,  235 
Phyllosticta  Blight  of  Snapdragon,  241 
Physiological  Inertia  and  Momentum.  186 
Phytophthora     Disease    of    Tomato    and 

other  Plants,  243 

—  i)ifestans.  Amount  of  Copper  required 

for  the  Control  of,  349 
I'ictet,  Arnold,  Lymantria  dispar.  49 
I'icris  and  Euchloe.  Caterpillars  of.  193 
Pieron,  Henri,  Homing  of  Limpet,  191 
Pig,  Absence  of  Hind  Legs  in,  36 

—  Development    of    Shoulder-Girdle   of, 

303 
Pilsbry,  Henry   A..   Peculiar  Venezuelan 

Land  Snail,  46 
Pinrhat  paralitica  Grove,  239 
Plana rians.  Head-generation  in,  325 
Plankton,  Acticm  of  Sulphate  of  Copper 

on,  81 

—  Fresh-wator,  from    Gandia  (Valencia), 

222 
Plant  Diseases,  244 
IMant-bug,  51 

lice,  .Iumi)ir.g,  53 

Plants,  Alternation  of  Generations  iu.  79 
Plasmopara,  S6 

IMastids,  Mitochondrial  Origin  of,  212 
Plath.  O.  E.,Muscid  [>arva  Sucking  Blood 

of  Nestlings.  320 
Phttyzorna  mirrophi/Umn  R.Br.,  74 
Plavfair.   G.  L,  IVridineaj  of  New  South 

*  Wales,  222 
Pleahocitrrhia  pileus,  205 


INDEX. 


37 


Plitt,  Charlt^s  C.  Short  History  of  I.ichen- 
ology,  245 

Pohlman.  A.  G..  Causal  Factor  in  Hatch- 
ing of  Chick,  179 

Polyclia3ts,  Madagascar,  324 

Polvclad,  Pigmentation  of,  58 

I'olyelads,  New  Japanese,  325 

Polyodou  spathida,  39 

I'olyporacese  of  Bengal,  237,  348 

Polyzoa,  New  Japanese,  328 

Pond-Life  Exhibition,  254 

Pontania  vesicatnr,  Larva  of,  48 

Pores,  Germinating.  Furrows  and,  233 

Portmann,  Georges,  Ear  of  Guinea-pig,  189 

—  Endolymphatic  Sac  and  Duct  in  Dog. 

18'-t 
Postolka,  A.,  Growth  of  Fungi  in   Hens' 

Eggs,  93 
Potamon  edule,  5(J 

Potato  Tubers,  Skin  Spot  Disease  of,  349 
I'otatoes,  3Iidge  Infesting,  51 
Preissecker,  K.,   Leaf-disease  of  Tobacco 

in  Koumania,  243 
Protozoa,  Fresh-water  Ciliate.  of  India,  257 

—  Intestinal.  2i)7 
Pseudosphrerialcs,  87 
Psyllid  Gall  on  Juncus,  51 
Pteridophyta,  73 

—  of  Indo-China,  76 

Pteris  aqmlina  L.  in  the  Tufa  of  the 
Villa  Torlonia  at  Frascati,  219 

—  Norfolk  Island  Species  of.  219 
Puccinia       Caricis,      Heteroccism       and 

Specialization  in,  347 

—  graminis  on  Berberis  canailensis,  347 

—  Mah-acearum     and     the     Mycoplasm 

Theory,  347 

—  obscura     and     Related    Puccinise    on 

Lazula,  235 
I'ycnidia,  90 
I'ycnitlium,  Oiigin    and   Development  of 

the,  90 
I'yrenomycetes,  Large,  345 


Q 


Quartzite  Pebbles  of  the  Oldhaven  (Black- 
heath)  Beds,  353 


Rabanus,  A.,  Algae  of  Baden,  80 

Rabaud,  E.,  Ammophila  heydeui^  192 

Rabbit,  Pregnant.  Hypertrophy  of  Supra- 
renal Capsules  in.  180 

Rana  aurora.  New  Distome  from,  325 

Rats,  Starving,  304 

Rawdim,  Henry  S.,  Defects  revealed  by 
the  Deep  Etching  of  Transversely- 
fissured  Rails,  249 

Raymond,  P.  E.,  Pygidium  of  Trilobites, 
321 


Regnault,  Felix,  Theory  of  Vital  Pheno- 
mena, 42 

Rehm,  H..  New  Ascomycetes,  89 

Reighard,  Jacob,  Breeding  of  Dog-Perch, 
305 

Reinking.  0.  A.,  Higher  Basidiomyeetes 
from  tl,e  Pliilippines,  237 

Renner,  D..  Alternation  of  Generations  in 
I'lants.  79 

Rennie,  John,  and  Elsie  J.  Harvey,  Isle  of 
AVight  Disease  in  Hive  Bees,  315 

Report,  Annual,  116 

Reservoirs,  Fauna  of,  45 

Retterer,  Ed..  Testicular  Grafts,  34 

—  Development  of  Membrane  Bone,  36 

—  Testicular  Epithelium,  180 

—  Varieties  of  Cartilage,  184 

—  Coi  tical  Layer  of  Simple  Teeth,  186 
BhapMdo><tegium  coespitosum  (Sw.)  and  its 

Affinities,  221 
Rhododendron,  Diseases  of.  349 
lihynia    Gwynne-Vaughani    Kidston    and 

Lang,  73 
Riccia  from  Peru,  339 
Rice.    Edward    L.,    Columella    auris    in 

Reptiles,  183 
Ricome.  H.,   Trapping   of  Insects   by  an 

Asclepiad,  47 
Rioja.  Enrique,  Abnormality  in  Serpulid. 

201 
Ris,  F..  Gli/pliotselius  punctatolineaius.  51 
Ritchie.  Walter,  Cryphalus  abietis,  319 
Rocavitza,  E.  G.,  Species  of  Asellus.  322 

—  Study  of  Asellus,  322 

—  Studies  on  Asellidse,  322 

Rodwav,  L.,  Fungus  Flora  of  Tasmania. 

240 
Romanes,  Mrs.   M.   F.,  Algal   Limestone 

from  Angola,  85 
Rosenbaum.  J.,  Infection  Experiments  on 

Tomatoes  with  Phytophthora  terrestria, 

231 

—  Macrosporium  from  Tomatoes,  243 
Rosenhain,    W.,   and   D.   Hanson,    Inter- 
crystalline'  Fracture  in    Mild   Steel, 
352 

Itoya  anglica  G.  S.  "West,  a  new  Desmid, 
224 

Ruggles,  R.,  Mutational  and*' Recapitu- 
latory "  Characters,  306 

Russell,  A.  M.,  Hybrid  Sarracenias  and 
their  Parents.  70 

Rusts,  Cereal,  92 

—  Grass,  91         # 

Rytz,  VV.,  Synchytrium,  86 


S 


Sabellids  aud  Serpulids,  201 

Saccardo,  P.'A.,  Mycological  Notes,  94,  238 

Santha,  L.,  Lichens  in   Polarized  Light, 

100 
Sarracenias,  Hybrid,  70 


378 


INDEX. 


Sartory,  A.,  Bacteria  and  I'erithecial  De- 

velopmeut,  239 
Sauvageau,   C,   Xew    Species   of  Fucus, 

E.  dicliotomu^  8auv.,  85 

—  Laminaiias  of  the  French  Coasts,  344 

—  Olariiie  Algse,  229,  345 

—  and  L.  Moreau,  Feeding  ot  Horses  with 

Marine  Algse,  229 
Sax,  Hally  Jolivette,  PhiJocopm  ccendeo- 

tecfa  Kehm  sp.  n.,  232 
l^capania  paludicola  Loeske  et  C.  Miill,  77 
Sciiaeflfer,  A.  A.,  Locomotion  in  a  Spiral, 

188 
Schierbeek,   A.,   Setal  I'atteru  of  Cater- 
pillars and  Pupae,  320 
Schistosome  Larvae,  Adaptability  of,  328 
Schmidt,  W.  J..   Cells  of  Tadpole's  Tail, 

307 
Schmitz,Henry,Diseases of  Rhododendron, 

349 
Schnegg,  H.,  Development  and  Biology 

of  Pycnidia,  90 
Scott,  A.,  Microstructure  of  Zinc  Retorts, 

249 
Sea-anemones,  59 
Sea-pens,  203 

Searle,  G.  D.,  Erysiphe  Polygoni,  241 
Sea-urchin,  Aggregation  of  Spermatozoa 

of,  181 

—  —  T.arvae,  Double  Hydrocoele  in,  328 
Ova,  Appearance  of  Division  Spindle 

in,  329 

Segrino,  Lake  of,  222 

Seichell,  W.   A.,   Geographical  Distribu- 
tion of  IMariiie  Algse,  228 

—  Marine  Flora  of  Pacific  Coast,  228 
Sepia,  ••  Branchial  Hearts"  of,  312 
Sequoia  Washimjtonia  {S.  gigantea),  71 
Scrpulids,  324 

Setchell,  W.  A.,  Parasitic  Florid se,  83 

—  and  N.  L.    Gardner,  INIarine   Algae  of 

tlie  Pacific  Coast  of  North  America. 

Part  I. :  Myxophyceae,  b2 
Sex  Determination  in  ^Mammals,  184 
Sharp,    Lester    W.,    Spermatogenesis    in 

Blasia,  219 
Shaw,  Walter  R.,  Canjpbellosphaera,  Xew 

Genus  of  Yolvocaceie,  222 
Siiearer,  A.  !>.,  Malarial  I'arasite  in  Blood 

of  Buflalo,  02 
Sheather,  A.   L.,   and  W.  Shilstou,   Syn- 

gamus  laryngeus  in  Indian  Cattle,  324 
SigHlurioxtroljus  (M((z<)i-ui'pon),  218 
Silica  .Jirick   from    Roo4   jf   Open-hearth 

Furnace,  249 
Silkwoiia  Moths,  318 
Silurian  Rucks  of  May  Hill,  353 
Silvestri,  I-'.,  licvision  of  Glomeridae,  55 
Slimo-Monlds  of  Ontario,  :;51) 
Smiley,  FdwinaM.,  I'hyllosticta  P.light  of 

Snapdragon,  241 
Smith,    A.     Lorrain,    I'hnina    parasitica 

Cirove,  232 


Smith,  A.,  Drain-blocking  Fungus,  240 

—  Lichens  of  the  Baslow  Foray,  245 
Smith,  Bertram  G.,  Individuality  of  Germ- 
nuclei  in  Cleavage  Stages  of  Crypto- 
hrancliufi  allegheniensis,  179 

—  Diemyctylus    viridescens    icith    Bifur- 

cated Tail,  310 
Smith,  K.   M.,  Sense-organs  in  Antennas 

and  Palps  of  Diptera,  194 
Smith,  R.  AVilson,  Bulbils  of  Lycopodium 

lucididunt,  338 
Smut  Fungi,  91 
Snail,  Venezuelan,  40 
Snails  and  Slugs,  Action  of  Veratrin  un. 

47 

—  Flies  in.  195 

Soar,  Charles  D.,  The  Genus  Oxus,  55 

Soulier,  A.,  Vitelline  Membrane  of  Ser- 
pulids,  324 

Southwell,  T.,  and  B.  Prashad,  Embryo- 
logical  Studies  of  Indian  Fishes,  36 

Spermatogenesis  of  Blasia,  219 
-of  Horse,  300 

—  in  Ox,  300 

—  Relation  of,  to  Certain  Electrolytes,  33 
Sphagnum,  North  American,  339 
Sphincter  Muscles  in  Man,  185 
Spiders,  Male,  Palpar  Organ  of,  199 
Spinach  ^lildew  (^Peronospora  Spinacix), 

232 

Spiral,  Locomotion  in  a,  188 

Spirobolidae,  55 

Spiroptera  Cancer,  40 

Sponge,  Fresh-water,  (iemmule  Cells  of. 
61 

Squamosal  of  Fishes,  Homologies  of,  187 

Staeger.  Rob,  Larva  of  Pontania  x-exicator, 
48 

Stakman,  E.  C,  and  L.  J.  Krakova, 
Puccinia  graminis  on  Beihtris  cana- 
densis, 347 

Stead,  J.  E.,  Silica  lirick  from  Roof  of 
Open-hearth  Furnace,  249 

—  Spherical  Shell  Crystals  in  Alloys,  352 
Steel,  Cast,  Macrostructure  of,  351 

—  De-oxidization  of,  with  Hydrogen.  352 

—  Eflfect   of    Initial    Temperature    upon 

Physical  Properties  of,  248 
Steel,  Effect  of  Nitrogen  on,  249 

—  High-Speed,  Structural    Constitution, 

Hardening  and  Tem|)ering  of,  248 

—  Mild,  Intercrystaliine   Fracture  in,  352 

—  Runner,  Cast,  Crystallization  in,  248 

!    Steels,  Allov,  Chemical    Hrat-treatnients 
for,  35  f 

—  Chromium,  Structure  of,  2 IS 

—  Nickel-Chromium,  ;jr»l 

Steincr,  1).,  Lichenographical  Notes,  99 
Steiner,  .!.,  Lichens  from  Transcaucasia, 

245 
Stevens,  F.  L.,  Dolhideaceous  and  otliei- 

Porto  Rican  Fungi,  236 
Stt'ssart,  F.  H..  Ascaris  sniUa,  57 


INDEX. 


379^ 


Stewart,  G.  E.,  Xitrogen  in  Pacific  Coast 
Kelprf,  85 

Stickleback,  Development  of  Vascular 
System  in  Embryo,  302 

Stone.  R.  E.,  Spore  Discharge  in  HelveUa 
elastica,  233 

—  A'isibility  of  Spore  Dissemination  on 
Fomes  'pimcoln,  240 

Sumner.  F.  B.,  Variation  in  Deer-mice, 
308 

Sytlow,  Mycoiheca  gerutanica,  93 

Sydow.  H.  and  P.,  Mycological  Contribu- 
tions, 92 

Fungi  amazonlci  of  E.  Ule,  94 

Fiuigus  Fapuani,  96 

New  Fungi.  97,  238 

New  Philippine  Fungi,  95,  96 

UredinefB  with  Swelling  Spore- 
membranes,  346 

and    E.    J.    Butler,   Fungi    Indix 

Orientalis,  97 

Symposium,  104,  252,  and  pp.  1-260 
at  end  of  volume 

Synapsis,  Problem  of,  269 

Syncliytrium,  86 

Sijngamus  laryngeus  in  Indian  Cattle,  324 

Si/nioijotlirysis  WincheU,  353 


Tadpole's  Tail,  307 

Tadpoles,  Removal  of  Thvmus  Glands  in, 

305 
Tagg,  Harry  V..  Preservation  of  Artificial 

Cultures  of  Moulds,  239 
Takenouclii,   Matsuziro,  Endocrine  Func- 
tion of  Thymus  Gland,  18S 
Tannreutlier,  G.  W.,  Duplicity  in  Chick 

Embrvos,  36 
Tattersall,'  W.   M.,  Breeding  and  Habits 

of  Periwinkle,  313 
Taxus  canadensis,  Staminate  Strobilus  of, 

72 
Taylor,  Ara villa  M.,  Ecological  Succession 

of  Mosses,  339 
Taylor,  jNEonica,  Culture  of  Amoebfe,  62 
Tavlor,  Noel,  Asymmetrical  Duplicity  in 
'  Chick,  35 

—  Hermaphrodite  Green  Lizard,  183 
Taylor,  T.  H.,  Frit-Kly  on  Oats,  317 
Teeth,  Simple,  Cortical  Layer  of,  186 
Teodoru,G.,  Ceriparous  Cells  in  Lecanium 

jierm-se,  52 
Termites,  ^Mound-building,  of  Philippines. 

52 
Testicular  Grafts,  34 
Tetracoralla,  60 
Thalassiopliyta,  78 
Thaxter,  Koland,  Laboulbeniales,  87 
Theiszen,  F.,  Systematy  of  the  Ascomy- 

cetes,  88 

—  Botryosphseria,  88 


j   Theiszen,  F.,  Mycological  Memoirs,  89 

—  Tympanopsis  and  other  Genera,  238 

—  and  H.  Sydow,  Dothideales,  87 

Pseudospboeriales.  87 

Synoptic  Tables,  87 

Dothideffi  and  other  ^Nlicrofungi,  89 

Genus  Parodiella,  90 

Theiszen.  T..  Mvcologieal  Contributions, 
87,  89 

Thom,  Charles,  and  Murgaret  B.  Church, 
Aspergillus  fiimigatus,  A.  nidulans, 
A.  terreuif  sp.  n.,'  and  Allies,  232 

Thompson,  John  McLean,  Deparia  Moorei 
I  Hook,  75 

I    —  Platyzoma  microphyllum  R.  Br.,  74 

—  Rare  and  Primitive  Ferns,  75 
Thompson,    "W.    P.,   Companion-Cells    in 

Bast  of  Gnetum  and  Angiosperms,  69 
Thymus   Gland,  Endocrine  Function  of, 

188 
j    Thyroid   and   I'arathyroid  in  Toad  Tad- 
j  poles  deprived  of  Pituitary  Body,  183 

I    —  and  Pituitary  Primordia,  Inflnence  on 
I  Frog's  Inter-renal    Tissue   of   Extir- 

I  patiou  of  the,  182 

;    Tiger-beetles,  Chromosomes  in,  49 
Timbers,  Australian,  Crystals  in,  335 
Tisdale.  W.  B..  Iris  Leaf-spot  caused  by 

Didymellina  Iridis,  241 
Tmesipteris,  Prothallus  of,  75,  218 
Toad  Larvee,  Influence  of  Thyroid  Extir- 
pation on,  183 
Parathyroid  Glands  of  Thyroidless, 

305 
Tobacco  in  Eoumania,  Leaf- disease  of,  243 
Tomatoes     Infected    with      Fhytophthora 

terrestria,  231 
Tortula  mutica  Lindb..  Gemmae  of,  220 
Treadgold,  C  H.,  New  Nematode  from  a 

Baboon.  58 
Trees,  Growth  of,  336 
Trematode,  New,  from  Little  Brown  Bat, 

58 
Tricliocephalus  in  Liver  of  Bat,  201 
Trichomonads,  Fission  in,  63 
Trichomonas  of  Guinea-pig,  209 
Trigt.  H.  van,  Plieuomtiuon  in  Gemmule 

Cells  of  Fresh -water  Sponge,  61 
Trilobites,  Pygidium  of,  321 
Trueman,  A.  E.,  Ammonite  Siphuncle,  312 
Truffle,  New,  346 

Turbellarians  of  Mississippi  Basin,  202 
Turtles.  Development  of   Thymus,  Para- 

thvroid  and  Ultimo-branchial  Bodies 

in,'  182 
Tympanopsis  and  other  Genera,  238 


U 


Uchida,      Seinosuke,     ^Fallophaga     from 
Formosan  Birds,  197  ^'si 

.    Uichanco,   Leopoldo  B.,   Mound-building 
i  Termites  of  Philippines,  52 


380 


INDEX. 


Ui<-hanco,  Leopoldo  B.,  Plant    Galls    of 

Philippines,  193 
Uncaria,  ]Nryrmeuophily  in,  49 
Upliof,  J.  C.  Til..  Xerophytic  Selagiuellae, 

337 
Uredinales  of  Guatemala,  236 
Uredineae,  Eoumanian,  91 

—  the  Some  in,  90 

—  with  Swelling  Spore-membranes,  346 
Urediniiim   in   Pucciniastrum  Aqrimonix, 

235 
TJredo  aJpestris  Schrot,  91 
Uromyces  Genistx-tinctorise,  uEcidial  Forln 

of,  347 

—  of  North  America,  236 
Uronema  from  India,  224 

Urticina  crassicornis,  jMesenteries  in,  202 
Ustilaginales,  North  American,  347 


Vallois,  Henri  V.,  Muscular  Metamerism, 

37 
Variation,  305 

Vegetables,  Market  Pathology  of,  243 
Verticillate  Siphonese  of  the  Limestone  of 

Villanova-Mondovi,  344 
Villemin,  F.,  Structure  of  Duodenum  in 

Mammals,  185 
—  Types  of  Duodenum  in  Mammals,  185 
Vitality,   Renewal   of,  through   Conjuga- 
tion, 208 
Volvox,  Sensibility  to  Light,  334 
Vuillemin,  V.,  Reproductive  Organs  und 
Phylogeny  of  Amiutales,  213 


W 


Wakefield,  E.,  Fnngi  of  the  Paslow  Foray, 

239 
Wallis,  T.  Fi.,  The  Lycojjodium  Method 

of  Quantitative  Microscopy,  l(i9,  251 
Walton,  A.  C,  Refractive  Body  of  Sper- 
matozoon in  Ascarii<  cauls,  58 
Walton,  C.  L.,  Shell  of  Cockle,  315 
Wurnstorff,  C,  Bryological  Novelties,  77 
Wartcnweiier,  Alfred,  Plasniopara,  86 
Water,  Biological  Kxamination  of,  81 
—  from  the  d(  eper  Water  Strata,  82 
Watrin.   J.,   llvfiertropiiy   of    Suprarenal 

Capsules  in  Pregnant  Kabliit,  180 
Watts,    W.   Walter.    JSieurosi'Ha  pteroides 

(H.Br.)  Mett.,  75 
Weesc,  I.,  llypocrcacea^,  86 
Weill,  P.,  Kndocrine  Gland  in  Uterus  of 

I'ngnant  Rat.  I8t) 
Welch,   I'aul  S.,  North  American  Oligo- 

clisBts,  57 
AV^est,  («.,  Anipltoni  hijlexa,  81 
West'ii.   William    II.,   lleiict.  d  Zoospore 

Kmcrgonc^e  in  Dictyuchus,  85 
Wheeler,  W.  M.,  Australian  Uoney-ants,  48 


Wheeler,    W.     M.,     Mountain     Ants     of 
Western  North  America,  316 

—  Australian  Cerapachyini,  316 

—  Ants  of  Borneo,  317 

White,  J.  H.,  Fomes  applanatus,  242,  347 
Whiteley,    J.    H.,    The    Distribution    of 

Phosphorus    in     Steel    between    the 

Points  Acl  and  Ac3.  249 

—  De-oxidization  of  Steel  with  Hydrogen, 

352 
Wildeman,      E.     de,     Myrmecophily      in 

Uncaria,  49 
Wilhelmi,  J,,  Biological  Examination  of 

Water,  81 
Will,  H.,  and  F.  O.   Landtblom,  2Ljcoto- 

rula  turhidcuis  Will,  346 
Wille,  N.,  Algological  Notes,  223 
AVilliams.  A.   L.,    and   otiiers,  Electrical 

Conductivity   of  Copper   fused   with 

Mica,  351 
Williamson,  H.  Chas.,  Parasitized  Fish, 

189 
Wilson,  H.  v.,  and  Blackvrell  Markhara, 

Regulation  'u  Anuran  Embryos  with 

Spina  Bifida  Defect,  304 
Wollenweber,  H.  W.,  Fusaria,  90 
Woods,    W.    C,    Parasite    of    Blueberry 

Maggot,  51 
AVoodvvard,  A.  Smith,  Dentition  of  Pela- 

lodont  Shark  "  Climaxodus,"  353 
Wormald.  H.,  "Brown  Rot"   Diseases  of 

Fruit-trees,  242 
Wright.  Gertrude,  Pit-closing  Membrane 

in  Opliioglossaceae,  218 


Xerophytic  Selaginellas,  337 


Yendo,  Ivichisaburo,  AlgsQ  New  to  Japan, 
345 

—  and  J.   Ikari,  Auxospore-formation  of 

Chxtoceros  debile  Cleve,  341 
Y«ri,  Megumi,  and  1  okio  Kaburaki,  New 

Japanese  Polycla  is,  325 
Yermolott',  N.,  Navicula  and  Cymbella,  80 

—  Diatomaceous  Earth  of  Eompoc,  Santa 

Barbara  Co.,  California,  341 


Zahlbruckner,   A.,    Licliens   in  A.  Ginz- 

berger,  98 
--  New  Lichens,  98 
—  Exi)editi(»n  to  Patagonia  and  Terra  del 

Furgo,  100 
Zea  i^lais,  Chroniosomrs  in,  335 
Zinc  Retorts,  Microstiucture  of.  249 
Zoopliaijua  inxidtiiiit,  231 


LONDON  :   PRINTED   BY    WILLIAM  OLOWBS  AND  SONS,   LIMITED,  GKKAT  WINDMILL  STREET,  W.l 


THE     MICROSCOPE 

Its    Design,  Construction  and  Applications 


A 

SYMPOSIUM   AND    GENERAL    DISCUSSION 

HELD    1!Y 

THE    FARADAY    SOCIETY 
THE  ROYAL  MICROSCOPICAL  SOCIETY 

THE   OPTICAL   SOCIETY 
THE    PHOTOMICROGRAPHIC    SOCIETY 

In     co-operation     with 

THE     TECHNICAL     OPTICS     COMMITTEE     OE 

THE   BRITISH    SCIENCE    GUILD 

WEDNESDAY,    JANUARY     14th,     1<)20. 


In  the  Rooms  of   the  Royal    Society,   London. 

[By   kind   permission   of    the    President  and  CounciLj 


Including  Reports  of  adjourned  Discussions  held  in  Sheffield, 
February     24th,     and     in     London,     April    21st,     1920, 


Edited    by    F.    S.    SPIERS,    B  Sc,    F.Inst. P.. 

Secretary    and    Editor    to   the    Faraday    Society. 


CXZ.-^^^^^^  r/u^<^i'^>^^^^  /^  ■ 


.^^^^5^^^ 


'I'his  llluslralion  is  lakim  from  the  IJook  bv  (iCorRC  Atlains 
'•' KSSAYS    ON    Tin-:    MKROSCOPK." 
Printed  in  the  year   i7(j8. 


JOURNAL  OF  THE   ROYAL  MICROSCOPICAL  SOCIETY 

DECEMBER.     1920. 


A 

SYMPOSIUM    AND    GENERAL    DISCUSSION 

ON 

THE     MICROSCOPE: 

Its    Design,    Construction,    and 
Applications. 


The  Faraday  Society,  the  Eoyal  Microscopical 
Society,  the  Optical  Society,  and  the  Photomicro- 
GRAPHIC  Society  in  co-operation  with  the  Technical  Optics^ 
Committee  of  the  British  Science  Guild,  meeting  in 
joint  session,  held  a  Symposium  and  General  Discussion 
on  "  The  Microscope  :  Its  Design,  Construction  and 
Applications,"  on  Wednesday,  January  14th,  1920,  in  the 
Eooms  of  the  Royal  Society  at  Burlington  House» 
Piccadilly,  London,  by  kind  permission  of  the  President 
and  Council. 


The  purpose  of  the  Symposium  and  Discussion,  which  was 
organised  by  a  Joint  Committee  of  the  Co-operating  Societies,  at  the 
initiative  of  Sir  Robert  Hadfield,  Bart.,  was:  — 

(1)  To  stimulate  the  study  of  and  research  in  microscopical  sci- 
ence in  the  United  Kingdom  by  indicating  lines  of  progress 
in  the  mechanical  and  optical  design  of  the  instrument^ 
showing   by  means  of   exhibits  recent  improvements  in   the 


2  THE    MICROSCOPE:    ITS  DESIGN 

microscope  and  its  technique  and  the  varied  uses  to  which 
the  microscope  can  be  applied  as  an  instrument  of  research 
in  the  sciences,  arts  and  industries. 

(2)  To  encourage  the  manufacture  in  this  country  of  the  highest 
class  of  instrument  and  of  the  optical  glass  required  for  that 
purpose. 

The  meeting  extended  over  two  sessions:  from  4.15  to  6.30  and 
from  8.15  to  10.30  p.m.  The  exhibition,  which  was  probably  the 
most  important  of  its  kind  ever  held  in  this  country,  took  place 
during  the  afternoon  preceding  the  meeting,  in  the  Library  of  the 
Koyal  Society,  The  list  of  exhibits  is  printed  as  an  Appendix  to  this 
Eeport. 

The  total  attendance  at  the  exhibition  and  meeting  was  not  far 
short  of  one  thousand,  and  the  proceedings  throughout  were  of  an 
enthusiastic  nature. 

The  meeting  was  presided  over  by  Sir  Robert  Hadfield,  Bart., 
D.Sc,  D.Met.,  F.R.S.,  President  of  The  Faraday  Society,  supported 
by  Mr.  J.  E.  Barnard,  President  of  the  Royal  Mici'oscopical  Society, 
Professor  F.  J.  Cheshire,  C.B.E.,  President  of  the  Optical 
Society,  Mr.  F.  Martin  Duncan,  President  of  the  Photomicrographic 
Society,  and  Dr.  R.  Mullineux  Waimsley,  Chairman  of  the  Tech- 
nical Optics  Committee  of  the  British  Science  Guild. 

The  Chairman,  Sir  Robert  Hadfield,  opened  the  proceedings  with 
the  following  remarks:  — 

Whilst  we  must  not  congratulate  ourselves  too  soon,  we  can  at 
any  rate  say,  by  the  large  numbers  present,  by  the  extraordinary 
variety  and  number  of  valuable  papers  submitted,  by  the  exhibits, 
both  historical  and  modern,  also  by  the  interest  shown  generally,  that 
this  Symposium  is  going  to  aid  in  throwing  more  light  on  the  impor- 
tant subjects  with  which  it  is  attempting  to  deal. 

I  earnestly  hope,  as  I  am  sure  we  all  do,  that  as  a  result  of  our 
proceedings,  not  only  will  our  knowledge — and  knowledge  is  power — 
be  increased,  but  that  this  country  will  be  rendered  independent  of 
foreign  supplies  in  products  which  it  is  so  vital  should  be  made  at 
bome.  In  this  respect  I  should  like  to  read  a  valuable  letter  I  have 
received  from  that  public-spirited  and  broad-minded  citizen  Lord 
Burnham,  who  is  taking  great  interest  in  our  deliberations  and 
who  had  hoped  to  be  present.  In  his  letter  he  is  kind  enough  to 
say :  — 

*'  It  is,  as  you  say,  of  vast  importance  to  our  future  that  we  should  do 
all  we  can  to  assist  the  British  optical  industry  to  meet  foreign  competi- 
tion and  to  strike  out  new  lines  of  advance  for  itself.  We  all  know  how 
far  we  were  left  behind  in  the  days  before  the  war  and  this  time  it  is  up 
to  us  to  make  g"ood  once  for  all. 

I  wish  I  could  come  myself,  but  I  am  deeply  eng:aged  on  that  day.  It  is 
a  Rreat  thinpr  that  you  and  your  colleagues  should  put  yourselves  at  the 
head  of  such  a  movement." 


CONSTRUCTION   AND   APPLICATIONS  3 

I  think  we  all  feel  stimulated  by  such  encouraging  words  from  a 
man  like  Lord  Burnham,  who,  while  not  a  scientist  or  technician, 
sees  the  great  importance  of  this  movement. 

It  is  also  a  great  satisfaction  to  find  so  many  well-known  repre- 
sentatives of  science  and  technology  taking  part  in  our  Symposium 
to-day.  America  has  contributed  several  valuable  communications, 
including  those  of  Prof.  Sauveur,  who  has  done  so  much  for  the 
microscope  and  metallography,  Dr.  Zay  Jeffries,  who  has  made  the 
subject  of  grain  size  peculiarly  his  own,  and  others. 

We  have  imjDortant  communications  from  France  and  Italy  in 
the  papers  of  Monsieur  Eugene  Schneider,  Prof.  H.  le  Chatelier, 
Signor  Giolitti,   and  others. 

As  regards  our  own  country,  I  venture  to  say  that  the  host  of 
Addresses  and  Papers,  some  forty  in  all,  are  unique,  and  of  a 
most  valuable  nature.  The  Addresses  include  those  to  be  presented  by 
Sir  Herbert  Jackson,  Mr.  Barnard,  Prof.  Cheshire,  and  Prof.  Con- 
rady,  each  of  them  meriting  commendation  of  the  highest  kind.  As 
regards  the  authors  of  the  large  number  of  papers  presented,  it  is 
not  possible  to  mention  here  the  names,  for  they  are  so  numerous, 
but  it  can  be  added  that  the  general  standard  of  the  papers  is  ex- 
ceedingly high,  and  we  thank  those  many  confributors  most  heartily 
for  the  trouble  and  pains  they  have  taken  in  preparing  their  com- 
munications. 

May  I  say,  too,  on  your  behalf,  how  extremely  grateful  we  are 
to  the  authors  of  the  Addresses  and  Papers,  also  to  the  Exhibitors 
and  the  many  others  who  have  worked  with  such  energy  to  make 
the  Symposium  not  merely,  I  trust,  a  succiess,  but  one  from  which 
will  spring  benefits,  both  scientific  and  practical,  of  the  highest  order. 

I  wish  to  add  one  word  with  regard  to  the  most  valuable  his- 
torical collection  submitted  by  the  Education  Department.  I  refer 
to  that  from  the  Science  Museum,  South  Kensington.  I  also  take 
this  opportunity  of  offering  our  heartiest  congratulations  to  Sir 
Erancis  Ogilvie,  the  Director  of  that  Museum,  ujDon  his  recent  well- 
deserved  Knighthood. 

We  have,  too,  with  us  this  evening  many  important  Members 
and  visitors  who  have  done  much  for  the  microscope.  Amongst  them 
is  my  friend  Dr.  J.  E.  Stead,  w^ho  has  greatly  helped  metallography. 
I  am  sure  you  will  all  be  glad  to  learn  that  he  is  in  May  next  to 
"become  President  of  that  important  body,  the  Iron  and  Steel  Insti- 
Utte.  We  wish  him  health  and  strength  and  a  most  successful  term 
of  office. 

I  am  sure  I  shall  be  excused  for  referring  to  family  matters.  Of 
course,  as  family  matters  are,  it  is  strictly  private,  but  as  we  are 
one  big  family  to-night  we  should  like  you  all  to  share  in  our  joys. 
It  is  not  often  that  after  quite  a  considerable  interval  of  time  it 
is  possible  to  bring  together  the  Founders  of  a  Society.  The 
changes  and  chanoes  of  this  mortal  life  step  in  and  sadly  break  con- 
tinuity, but  in  this  special  case  I  am  glad  to  tell  you  we  have  present 
with  us  this  evening,  with  one  unavoidable  exception — and,  happily, 
this  is  not  owing  to  the  member  in  question  not  being  in  the  land  of 
the  living — all  the  Founders  of  the  Faraday  Society.  I  refer  to 
Mr.  Sherard  Cowper-Coles,  Mr.  W.  R.  Cooper,  Prof.  F.  G.  Donnan, 
Dr.   F.   M.   Perkin,  Mr.   Alexander  Siemens,   Mr.  James  Swinburne 


4  THE    MICROSCOPE 

and  Mr.  F.  S.  Spiers.  It  must  be  a  great  satisfaction  to  them  to 
see  this  magnificent  meeting,  as  one  of  the  fruits  of  their  labours 
in  the  past;  that  is,  in  seeing  the  Society  they  founded,  aided  by  the 
sister  Societies,  in  the  earnest  set  i3urpose  of  assisting  our  Empire 
in  this  important  question  of  improving  our  resources  in  optical 
matters.  All  honour  to  the  men  mentioned,  and  I  am  sure  that  I 
shall  be  voicing  your  feelings  in  offering  them  our  heartiest  congratu- 
lations. 

Whilst  this  is  a  meeting  of  the  "  Micro-Intellectuals,"  may  I 
now  descend  to  earth  and  remind  you  that  our  full  programme  has 
its  drawbacks.  We  have  the  time  limit  to  consider,  and  I  beg 
that  this  be  borne  in  mind.  If  I  have  occasionally  to  use  the 
closure  it  will  not  be  because  the  words  being  uttered  are  not  con- 
sidered words  of  wisdom,  but  that  the  evening  is  not  long  enough. 
I  will  now  try  to  set  the  example  by  making  my  own  remarks  as 
brief  as  pos.^ible. 


Sir  Robert  Hadffeld  then  presented  the  following 
*'  Introductory  Address,"  to  the  salient  features  of  which  he 
briefly  drew^  attention. 


INTRODUCTORY    ADDRESS 

By    SIR    ROBERT    HADFIELD.    Bart..    D.Sc,    D.Met.,    FR.S. 
President  of  the  Faraday  Society. 


SECTION   L— INTRODUCTION. 

As  the  result  of  some  suggestions  I  made  several  months  ago  to  the 
Council  of  the  Faraday  Society,  it  was  arranged  to  hold  this  present 
Symposium  on  "The  Microscope  and  its  Applications."  The  Royal 
Microscopical  Society  (Mr.  J.  W.  Barnard,  President) :  the  Optical 
Society  (Professor  F.  J.  Cheshire,  President) ;  and  the  Photomicro 
graphic  Society  (Mr.  F.  Martin  Duncan,  President)  all  most  cordially 
approved  and  agreed  to  co-operate  with  us.  In  view  of  the  fact 
that  the  objects  of  the  Faraday  Society,  as  set  forth  in  its  Con- 
stitution, are  not  only  to  promote  the  study  of  Electrochemistry, 
Electrometallurgy,  Physical  Chemistry  and  Kindred  Subjects,  but  also 
Metallography  this  Symposium  is  specially  appropriate.  It  is  only, 
or  at  any  rate  chiefly,  the  last  named  Branch  of  Research — Metal- 
lography— m)^  own  remarks  are  meant  to  cover,  that  is,  I  do  not 
pretend  in  this  Address  to  deal  with  the  Work  of  the  Microscope  as 
employed  by  the  Geologist,  the  Zoologist,  the  Biologist,  and  other 
Branches. 

During  the  preparation  of  this  Address  I  found  the  interesting 
frontispiece  of  the  Book  by  George  Adams,  "  ESSAYS  ON 
THE  MICROSCOPE."  This  was  published  July  1st,  1787,  and 
contains  a  Practical  Description  of  the  Most  Improved  Microscopes, 
revised  by  Frederick  Kanmacher,  F.L.S.,  1798.  I  thought  this 
illustration  particularly  appropriate  to  form  the  frontispiece  to 
this  present  Address  of  mine.  The  quaint  wording  at  the  foot 
of  the  Engraving 

''  9trutlj  trisrotr^rmg  to  ®im£,  S^runa  tnstnuting  Ijer 
fflljtltrr^n  in  tljt  SltnproiJBm^nts  an  iljt  Jltirrnsrop^/' 

w^ell  describes  the  object  of  our  present  Symposium. 

As  regards  the  modern  application  of  the  Microscope  including 
that  to  Metallography,  below  is  a  portion  of  the  preface  to  Monsieur 
Felix  Robin's  Work  "  Treatise  on  Metallography,"  contributed  by 
Professor   F.  Osmond,    who  did  so    much  for  Metallurgy,    and  from 


6  INTRODUCTORY   ADDRESS: 

whose  work  we  are  to-day  greatly  benefiting.  Robin  has,  alas,  himself 
passed  away  during  the  Great  War,  gloriously  devoting  his  life  on  the 
Field  of  Battle  on  behalf  of  his  Country.  I  make  no  apologies  for 
referring  to  this  tribute  to  the  Metallographist  and  for  quoting  in 
full  the  wise  words  of  Osmond.  These  are  well  worthy  of  consideration 
to-day,  and  the  reasons  given  by  him  will,  I  trust,  cheer  many  an- 
author  and  many  a  worker  in  the  fields  of  research. 

Osmond  said:  "To  write  a  treatise  on  a  branch  of  Science  in  process 
of  active  development  is  an  arduous  task,  especially  when  the  author  is 
not  a  professor  and  the  book  not  the  natural  synthesis  of  the  course. 
It  is  also  a  thankless  task,  for  the  work  of  to-morrow  will  amplify  and 
correct  that  of  to-day.  In  a  few  years'  time,  too,  the  old  edifice  must 
be  rebuilt  because  the  new  generation  no  longer  deems  it  sufficiently 
comfortable  in  its  old  form.  We  ought,  therefore,  to  be  indebted  to  those 
who  have  the  courage — which  I  have  always  lacked — to  collect  and 
collate  scattered  material.  Those  who  continue  the  work  are  thereby 
saved  the  trouble  of  lengthy  visits  to  libraries  and  the  search  for  docu- 
ments of  sometimes  questionable  value  disseminated  in  the  periodicals  of 
all  civilised  countries.  But  M.  Robin's  book  is  not  a  mere  compilation. 
The  author,  whose  numerous  papers  have  evoked  the  attention  of,  and 
have  been  the  subject  of  numerous  awards  by,  the  British  Iron  and 
Steel  Institute  and  others,  has  been  working  whole-heartedly  for  some 
years  past  in  the  direction  of  extending  our  knowledge  of  Metallography 
and  its  kindred  Sciences.  His  contributions  to  this  Science  have  been 
most  useful,  and  he  is  thus  in  a  position  to  enrich  the  present  treatise 
by  his  personal  experience  and  minute  observations,  to  the  great  benefit 
of  those  who  will  follow  him." 

''La  science  est  un  pays  plein  de  terres  desertes ; 
"  Tous  les  jours  nos  auteurs  y  font  des  decouvertes. 
"  Mais  ce  chajnp  ne  se  pent  tellement  moissonner, 
''Que  les  dernier s  venus  riy  trouvent  a  glaner.'^ 


Work  of  the  Various  Societies  taking  part 
IN  THIS  Symposium. 

The  Faraday  Society. — Turning  to  the  work  of  each  of  the 
Societies  taking  part  in  this  Symposium,  I  deal  with  that  of  the 
Faraday  Society  in  a  separate  paper  presented  to  this  Sym- 
posium, entitled  "  The  Work  of  the  Faraday  Society  and  a  brief 
Reference  to  Michael  Faraday."  I  will  therefore  not  add  anything 
further  here.     (See  Appendix  II.  p.  254). 

Royal  Microscopical  Society. — The  Royal  Microscopical  Society  was 
established  in  1839.  The  late  Dr.  H.  C.  Sorby,  F.R.S.,  of  Sheffield, 
the  Founder  of  Modern  Metallography  and  of  whom  a  portrait  is 
given  in  Fig.  1,  was  President  of  this  Society  in  1876  and  1877. 
The  famous  Microscopist,  Dr.  W.  Dallinger,  F.R.S.,  of  whom  a 
portrait  is  given  in  Fig.  2,  and  who  lived  in  Sheffield  for  a  number 
of  years,  was  also  President,  in  the  years  1884-7. 


SIR     ROBERT     HADFIELI),     BART.  7 

Amongst  other  Past  Presidents  of  this  important  Society  have 
been  Sir  Richard  Owen,  1840 ;  Edwin  Lankester,  1858  ;  John  Thomas 
Quekett,  1860  ;  Lord  Avebury,  1907  ;  Sir  Edwin  Ray  Lankester, 
1909;    Prof.   H.  G.   Plimmer,'  1911  ;    and  to-day  Mr.  J.  E.  Barnard. 

It  was  in  November,  ]  866,  that  Mr.  Secretary  Walpole  notified  the 
President  that  Her  Majesty  had  been  graciously  pleased  "  to  command 
that  the  Society  shall  be  styled  the  Royal  Microscopical  Society." 

Singular  to  say,  notwithstanding  his  early  work  in  1857-1863,  Dr. 
Sorby,  even  in  his  own  Presidential  Addresses  in  1876-1877  to  the  Royal 
Microscopical  Society,  made  no  reference  to  the  use  of  the  Microscope 
for  Metallurgical  Research.  Apparently,  he  himself  had  not  then 
applied  his  method  of  study,  but  the  germ  was  there  waiting 
to  be  developed.  Professor  W.  G.  Fearnsides  has  pointed  out 
in  his  interesting  account  of  Sorby's  lifework  in  the  first 
Sorby  Lecture  delivered  before  the  Sheffield  Society  of  Engineers 
and  Metallurgists  in  1914,  "  On  some  Structural  Analogies  between 
Igneous  Rocks  and  Metals,"  that  it  w^as  in  the  year  1885,  by  the 
use  of  Lenses  of  high  resolving  power  and  comparatively  large  magni- 
fication, Sorby  first  saw  the  true  composite  nature  of  the  "pearly 
constituent "  of  Steel  as  an  aggregate  of  parallel  plates.  This 
discovery  was  the  earliest  recognition  of  the  formation  of  crystals 
from  a  solid  solution,  and  may  be  regarded  as  the  crowning  achievement 
of  his  microscopical  research.  He  announced  this  discovery  to  the  Iron 
and  Steel  Institute  in  1886,  and  in  1887  presented  to  the  same  Institu- 
tion his  historical  Paper  on  "  The  Microscopical  Structure  of  Iron  and 
Steel,"  which  gave  a  full  account  of  his  methods  and  the  results  he 
had  obtained. 

A  well-known  American  WTiter,  in  a  biographical  sketch  of  Sorby 
published  in  "  The  Metallographist "  for  April,  1900,  stated :  "Whatever 
has  been  accomplished  since  in  Microscopic  Metallography  has  been 
done  by  following  in  his  footsteps.  To  Dr.  Sorby,  and  to  him 
alone,  is  due  the  pioneer's  honour." 

I  had  at  first  intended  to  include  in  this  Address  my  remarks 
regarding  the  great  work  performed  by  Sorby  for  "  The  Metallo- 
graphist."' In  view,  however,  of  the  importance  of  the  subject,  and 
that  some  of  our  younger  members  may  not  be  aware  of  the  facts, 
I  have  thought  it  best  to  embody  and  present  these  in  a  separate 
short  communication  entitled  "  The  Great  Work  of  Sorby." 

Optical  Society. — As  regards  the  Optical  Society,  which  now  has 
its  Headquarters  at  the  Imperial  College  of  Science  and  Technology  at 
South  Kensington,  this  was  founded  in  1899,  its  first  President  being 
Mr.  W.  H.  E.  Thornthwaite,  F.R.A.S.  Subsequent  Presidents  have 
been  Dr.  R.  M.  Walmsley,  Professor  Silvanus  Thompson,  Dr.  W. 
Rosenhain,  Sir  Richard  Glazebrook,  Sir  David  Gill,  and  to-day  Pro- 
fessor Cheshire,  C.B.E.,  who  did  such  excellent  work  in  the  War. 

Photmnicrographic  Society. — The  Photomicrographic  Society  was 
founded  in  1911  by  a  small  band  of  Microscopists  and  Photographers, 
including  Fellows  of  both  the  Royal  Microscopical  and  Photographic 
Societies,  having  for  its  objects,  to  quote  from  its  Rules,  "  the  study 


8  INTRODUCTORY   ADDRESS: 

of  Photomicrograpliy  and  the  discussion  and  demonstration  of  any 
subjects  of  interest  concerning  it."  From  the  first  the  Society  was  a 
success,  as  evidenced  by  continual  increase  of  Membership,  and  this  is 
perhaps  due  to  the  wide  field  in  Research,  Engineering,  Natural  History, 
Industrial  and  other  Processes,  in  which  the  Microscope  is  essential. 
This  is  also  shown  in  the  diverse  nature  of  the  subjects  in  which 
individual  members  are  specially  interested,  but  who  alike  have  to 
record  their  observations  by  Photography.  Others  again  are  interested 
purely  in  the  optical  equipment  of  the  Microscope  and  the  special 
problems  presented  to  the  photomicrographic  worker.  The  essential 
importance  of  correct  microscopic  technique,  especially  proper 
illumination  to  obtain  a  correct  image,  has  always  been  recognised, 
and  great  attention  has  been  paid  to  the  mechanical  side,  as  shown 
by  apparatus  designed  and  built  by  several  members  and  exhibited 
from  time  to  time. 

Mr.  F.  Martin  Duncan  now  occupies  the  Presidential  Chair,  and 
Mr.  J.  E.  Barnard  was  President  in  1915-16.  A  Medal  is  awarded 
annually,  for  the  best  results  in  Photomicrography  from  both  the 
microscopical  and  photographic  point  of  view. 

The  Society  meets  twice  monthly  at  King's  College,  and  has 
papers  on  the  many  subjects  in  which  the  use  of  the  Microscope  is 
essential,  together  with  other  meetings  of  a  less  formal  character 
for  discussion,  exhibition  of  photomicrographs,  and  apparatus 
connected  with  Photomicrography. 

For  the  foregoing  information  I  am  indebted  to  the  Honorary 
Secretary  and  Treasurer,  Mr.  J.  G.  Bradbury,  who  has  done  so  much 
good  work  on  behalf  of  this  useful  Society. 

British  Science  Guild. — The  Committee  on  the  Microscope  appointed 
by  this  Body,  with  its  Chairman,  Dr.  Walmsley,  have  also  been  kind 
enough  to  give  much  useful  help  with  regard  to  our  Symposium. 


It  will  be  seen  therefore  that  the  Faraday  Society  has  been 
successful  in  enlisting  the  co-operation  and  aid  of  the  various  special 
Societies  who  are  also  immediately  interested  in  improving  Research 
Work  in  Microscopy. 

Objects  of  the  Symposium. — The  objects  of  the  Symposium 
are  : — 

(a)  Improvement   in   the   technique   of   the   Microsco])e  itself, 
including  its  manufacture. 

(b)  Improvement  in  Lenses  including  Eye-pieces  and  Objectives 
of  High  Power. 

(c)  Improved  application  of  the  Microscope  for  Research  in 
Ferrous  and  Non-Ferrous  Metallurgy. 

AVith  these  objects  all  will  be  in  agreement,  and  if  as  a  result 
of  this  Symposium  they  are  successfully  carried  out  and  attained, 
as  I    am  confident  will  be  the  case,  our  gathering  will  be  not  only 


SIR     KOBERT     HADFIELD,     BART.  9 

noteworthy,  but  will  prove  to  be  of  great  service  to  those  interested, 
in  our  own  Country,  America,  and  elsewhere. 

Present  and  Future  Work. — As  regards  the  particular  direc- 
tion in  which  Metallurgists  should  look  in  the  future  for  further  help 
from  the  Microscope,  may  I  suggest  that  one  of  the  objects  we 
ought  to  have  in  view  should  be  to  obtain  increased  knowledge 
from  examinations  at  higher  magnifications,  that  is  to  say,  5,000, 
8,000  and  still  higher.  This  may  seem  ambitious,  and  I  may  be 
wrong  as  to  the  value  of  the  knowledge  to  be  so  obtained,  but 
I  hope  not.  If  there  is  anything  in  my  behef,  a  wide  vista  opens 
out  for  further  Research  Work. 

I  am  contributing  along  with  Mr.  T.  G.  Elliot,  F.I.C.,  a  special 
paper  on  this  important  aspect  of  the  subject,  entitled  "  Photomicro- 
graphs of  Steel  and  Iron  at  High  Magnification,"  which  I  hope  will 
be  of  interest  to  our  members. 

In  the  past  both  in  England  and  in  America  there  has  been  far 
too  much  dependence  on  Germany  and  Austria  for  the  supply  of 
the  best  type  of  Microscope,  including  constructional  details, 
and  high-quality  Objectives  and  Eye-pieces.  It  is  most  desirable 
that  in  future  this  situation  should  be  avoided.  Forewarned  is  fore- 
armed, and  every  possible  means  must  be  taken  in  a  fair  and  open 
manner  to  remedy  this  situation  by  private  enterprise  and  research, 
and  if  necessary  by  Research  Associations  aided  by  the  grants 
allocated  by  Parliament  for  such  purposes. 

To  show  that  it  is  of  the  highest  importance  that  this  Country 
should  be  independent  of  foreign  aid  in  its  supplies  of  this  nature, 
it  may  be  added  that  had  it  not  been  for  the  enterprise  of  just 
one  British  Firm  with  regard  to  the  supply  of  Optical  Glasses  at 
the  outbreak  of  War,  we  might  have  been  absolutely  stranded  in 
the  supply  of  the  necessary  products,  both  for  apparatus  and  glass- 
ware, so  essential  in  sighting  and  other  instruments  of  observation 
used  in  Modern  Warfare. 

By  these  remarks  I  do  not  wish  to  disparage  the  work  of  those  who 
until  recently  have  been  Enemies,  and  who  in  the  past  wisely  equipped 
themselves  by  means  of  Apparatus  and  Appliances  of  all  kinds  as  well 
as  by  encouraging  scientific  development.  Good  work  proceeding  from 
any  nationality  stands  fast  for  all  time.  Let  us,  however,  now  learn 
the  lesson  and  benefit  from  the  experience  gained  by  us  during  the 
War  at  such  bitter  cost.  It  has  to  be  admitted  that  our  Instru- 
ment Makers  w^ere  then  necessarily  largely  employed  in  other 
directions  and  were  unable  to  cater  for  the  requirements  of  the 
Microscopist.  They  could  not  therefore  devote  the  time  so  essential 
for  improving  not  only  the  mechanical  but  the  optical  details  of  the 
Microscope,  including  its  Objectives  and  Eye-pieces.  Notwithstanding 
the  many  advances  made  during  the  War  by  the  Chemist,  the  Elec- 
trician, the  Metallurgist,  the  Engineer,  and  others,  no  special  claim 
can  be  made  that  much  progress  has  been  made  by  the  Microscopist. 
As  far  as  can  be  gathered,  the  methods  and  appliances  now  used 
<do  not  show  great  advance  on  those  prior  to  the  War.      In  saying 


10  INTRODUCTORY   ADDRESS: 

that  it  is  not  meant  to  indicate  that  knowledge  has  not  been  accumu- 
lated and  that,  for  example,  we  shall  in  the  future  be  dependent 
upon  foreign  supplies  as  in  the  past ;  it  is  hoped  quite  the  contrary. 
It  is  one  of  the  main  objects  of  this  Symposium  to  bring  forth  and 
prove  that  all  these  requirements  can  and  will  be  met  by  the  Anglo- 
Saxon,  or  at  any  rate  that  this  will  be  possible  in  the  immediate  future. 

It  should  be  added  that  there  stands  out  very  prominently  in 
this  connection  the  important  work  done  on  behalf  of  Glass  Tech- 
nology by  Sir  Herbert  Jackson,  K.B.E.,  to  whom  we  are  greatly 
indebted,  and  who  will  give  us  an  important  Address  this  evening. 

Reference  should  also  be  made  to  the  excellent  work  carried  out  on 
this  subject  by  the  National  Physical  Laboratory,  where  systematic 
work  on  the  attack  of  various  refractory  bodies  by  molten  glass  under 
carefully  standardised  conditions  has  been  continued,  together  with 
work  on  the  production  of  crucibles  increasingly  resistant  to  such 
attack.  Progress  has  been  made  in  the  application  of  fused  zirconia 
as  a  lining  for  crucibles.  In  the  course  of  this  work  special  phenomena 
have  been  observed  in  the  attack  which  occurs  in  some  cases  at  the 
bottom  of  the  crucible,  and  in  others,  at  the  level  of  the  surface  of  the 
glass.  These  phenomena  have  been  studied  by  means  of  experiments 
on  the  mode  of  solution  of  such  substance  as  wax,  naphthaline  and 
plaster-of-paris  in  ordinary  solvents  at  room  temperature  where  the  phe- 
nomena could  be  observed.  Most  of  the  features  met  with  in  the  attack 
of  molten  glass  on  crucibles  have  been  reproduced  in  such  experiments, 
and  a  method  of  preventing  the  worst  features  of  such  attack  has  been 
tried  and  found  successful  in  the  model  experiments.  In  addition 
reference  should  be  made  to  the  valuable  work  done  by  the  Society 
of  Glass  Technology  at  the  University  of  Sheffield,  in  which  Dr.  W.  E.  S. 
Turner,  the  honorary  secretary,  has  played  so  important  a  part. 

It  is  certainly  most  necessary  that  we  should  not  be  behind 
but  abreast  of  our  Foreign  competitors  in  the  making  of  Microscopes 
and  Lenses  or  their  use.  One  of  the  prominent  objects  in  holding  the 
Symposium  is  to  arouse  still  more  interest  in  the  advancement  of  this 
work. 


SECTION  II.— HISTORY  OF  THE  MICROSCOPE. 

Ancient  Times  to  1600  a.d. 

If  the  Microscope  is  considered  as  an  Instrument  consisting  of  one 
Lens  only,  it  is  not  at  all  improbable  that  it  was  known  to  the  Ancients, 
and  even  to  the  Greeks  and  Romans.  The  minuteness  of  some  of  the 
pieces  of  workmanship  of  the  Ancients  would  appear  to  indicate  that 
they  must  have  been  executed  by  the  use  of  Magnifying  Glasses. 
Many  passages  in  the  Works  of  Pliny,  Plutarch,  Seneca,  and  others 
clearly  indicate  this. 

There  is  reason  to  believe  that  the  magnifying  power  of  transparent 
media  with  convex  surfaces  was  known  very  early.  The  convex  Lens 
of  rock  crystal  was  found  by  Layard  among  the  ruins  of  the  Palace  of 
Nimrod.  Seneca  describes  hollow  spheres  of  glass  filled  with  water 
as  being  mainly  used  as  magnifiers.       It  is  practically  certain  that 


SIR     ROBERT     HADFIELD,     BART.  11 

the  perfect  gem  cutting  of  the  Ancients  could  not  have  been  attained 
without  the  use  of  magnifiers. 

In  the  Book  "  Essays  on  the  Microscope  "  by  George  Adams, 
Mathematical  Instrument  Maker  to  His  Majesty  (1787),  being  "  A 
Practical  Description  of  the  Most  Improved  Microscopes,"  which  was 
one  of  the  Standard  Works  at  that  time,  Adams  said  :  "  It  is  generally 
supposed  that  Microscopes  were  invented  about  the  year  1580,  a 
period  fruitful  in  discoveries.  The  honour  of  the  Invention  is  claimed 
by  the  Italians  and  the  Dutch  ;  the  name  of  the  Inventor  appears, 
however,  lost." 

With  regard  to  the  many  interesting  facts  relating  to  the  early 
History  of  the  Microscope,  two  valuable  contributions  have  been  made 
by  Dr.  Charles  Singer,  M.D.,  "  Notes  on  the  Early  History  of  the 
Microscope  "  read  before  the  Royal  Society  of  Medicine  in  1914,  and 
"  The  Dawn  of  Microscopical  Discovery,"  before  the  Royal  Micro- 
scopical Society  in  1915. 

In  giving  the  following  information  I  have  taken  the  liberty  of 
freely  making  use  of  the  valuable  Researches  of  Dr.  Singer,  who  points 
out  that  there  have  been  three  main  epochs  in  the  History  of  Micro- 
scopical Discovery.  There  was  the  Pioneer  Period,  extending  to 
about  1660,  the  Classical  Period,  covering  half-a-century  or  more  from 
about  1660,  and  including  the  work  of  the  great  Microscopists,  Hooke, 
Grew,  Malpighi,  Leeuwenhoek  and  Swammerdam,  and  finally  the 
Modern  Period,  dating  from  the  Optical  Discoveries  of  Newton. 

The  earliest  microscopical  observation  known  is  stated  by  Dr. 
Singer  to  be  of  Seneca  (circa  A.D.  63)  who  in  his  "  Quaestiones  Natur- 
ales  "  said  that  "  Letters,  however  small  and  dim,  are  comparatively 
large  and  distinct  when  seen  through  a  glass  globe  filled  with  water." 

The  properties  of  curved  reflecting  surfaces,  and  even  to  some 
extent  of  Lenses,  were  known  to  the  ancients,  and  to  some  mediaeval 
writers,  such  as  Roger  Bacon.  The  invention  of  convex  spectacles 
is  attributed  to  Salvino  d'Amarto  degli  Armata,  of  Florence,  and  to 
Alessandro  de  Spina,  of  Pisa,  about  the  year  1300,  and  these  aids  to 
vision  were  familiar  to  many  throughout  the  fourteenth,  fifteenth 
and  sixteenth  centuries.  During  this  period  the  optical  properties 
of  Lenses  were  investigated  by  the  penetrating  genius  of  Leonardo  da 
Vinci  (1452-1519)  and  by  the  mathematical  skill  of  Maurolico  (1494- 
1575).  while  convex  spectacles  must  have  been  on  the  nose  of  many  a 
careful  illuminator  of  manuscripts. 

Up  to  this  time  Dr.  Singer  points  out  there  is  no  single  instance 
on  record  of  these  glasses  having  been  used  for  the  investigation  of 
nature  and  that  even  the  many  illuminated  manuscripts  of  the  fifteenth 
and  sixteenth  centuries,  especially  of  the  Flemish  school,  do  not  suggest 
the  use  of  magnifying  glasses. 

The  first  illustrated  publication,  for  which  there  is  evidence  of  the 
use  of  a  magnifying  glass,  appeared  in  the  year  1592  at  Frankfort, 
bearing  the  name  of  George  Hoefnagel  (1545-1600).  The  volume 
consisted  of  a  series  of  plates  engraved  on  copper,  illustrating  common 
objects  of  nature,  but  drawn  with  exceptional  skill  and  minute  accuracy. 
Some  few  of  these  drawings  revealed  enlarged  details  which  would 


12  INTRODrCTORY   ADDRESS: 

have  been  hardly  distinguishable  to  the  unaided  eye.  These  remark 
able  figures  are  stated  to  have  been  the  work  of  Hoefnagel's  son, 
Jacob  (1575). 

It  must  be  remembered,  however,  that  the  occasional  use  by  a 
naturalist  of  a  simple  Lens  of  low  magnifying  power  could  have  but 
little  influence  on  the  advance  of  knowledge.  It  was  not  until  the 
Classical  Period  with  the  invention  of  Lenses  of  very  short  focus  that 
the  simple  Microscope  became  a  valuable  means  of  Research.  In  the 
Pioneer  Period  it  was  rather  the  discovery  that  Lenses  could  be  combined 
into  the  Telescoj^e  and  the  Microscope  that  gave  the  first  stimulus  to 
investigation.  These  compound  instruments  were  invented  about 
the  vear  1610. 


1600  TO  1700  A.D. 


The  Dutchman  Zacharias, "  miscalled  Jansen,  and  his  son  made 
Microscopes  before  the  year  1619.  It  was  he  who,  whilst  still  a 
lad,  had  worked  with  his  father,  who  was  a  spectacle  maker,  and 
appears  to  have  discovered  accidentally  the  principle  of  a  Telescope 
by  placing  two  Lenses  together  in  a  tube.  The  invention  of  the 
Microscope  followed  about  that  time,  though  the  exact  date  is  un- 
known. In  the  year  1619,  Cornelius  Drebbel,  of  Alkomar,  brought 
a  Microscope  which  was  made  by  the  Jansens  with  him  into  England 
and  showed  it  to  William  Boreel,  who  was  Dutch  Ambassador  tc 
France,  and  eventually  to  England.  It  is,  however,  added  that 
Drebbel's  instrument  was  not  strictly  what  is  now  meant  by  the 
Microscope,  but  was  rather  a  kind  of  Microscope-Telescope,  somewhat 
similar  in  principle  to  certain  apparatus  described  by  Mr.  Aepinus 
in  a  letter  to  the  Academy  of  Sciences,  St.  Petersburg.  This  was 
formed  of  a  copper  tube  six  feet  in  length  and  one  inch  in  diameter. 
On  the  other  hand,  Dr.  C.  Singer,  in  his  interesting  Paper  on  "  The 
Historical  Aspect  of  the  Microscope,"  does  not  think  this  was  the  case. 

A  portrait  of  Jansen  is  given  in  Fig.  3.  A  photograph  is  also 
given  of  Hans  Lipperhey  (Fig.  4),  who  is  described  as  the  inventor 
of  the  second  Microscope,  Jansen  being  referred  to  as  the  inventor 
of  the  first  one,  that  is  of  the  special  type  described  probably  in  the 
beginning  of  the  Seventeenth  Century. 

Dr.  Hooke,  the  author  of  the  famous  "  Micrographia  "  in  1665, 
described  means  of  utilising  small  drops  or  globules  of  glass  in  a 
Microscope,  and  said  that  by  means  of  this  he  had  been  able  to  dis- 
tinguish the  particles  of  bodies  not  only  a  million  times  smaller  than 
the  visible  points,  but  even  to  make  these  visible  whereof  millions  of 
millions  would  hardly  make  up  the  bulk  of  the  smallest  visible  grain 
of  sand  ;  so  prodigiously  do  these  exceedingly  small  globules  enlarge 
our  prospect  into  the  more  hidden  recesses  of  Nature.  Di  Torre  of 
Naples  also  largely  made  use  of    these  globules  for  his  well-known 


investigations. 


As  regards  Hooke's  Book  referred  to,  it  may  be  interesting  to  give 
a  facsimile  (Fig.  5)  of  the  title  page  as  it  appeared  in  1665."  Hooke 
was  a  Fellow  of  the  Royal  Society,  and  a  facsimile  of  his  signature  as  it 
appears  in  the  famous  "  Roll  Call  of  Fellows  "  is  given  at  the  foot  of 
the  front  page,  in  Fig.  5. 


SIR     ROBERT    HADFIELD,     BART.      "  13 

As  an  interesting  example  of  the  examination  done  by  Hooke  in 
1664,  and  simple  as  this  may  seem  now,  I  give  in  Fig.  6  the  result 
of  an  investigation  he  carried  out  on  the  point  of  a  small  needle, 
which  to  use  his  own  words,  was 

made  fo  fharp  that  the  naked  Eye  is  unable  to  diftin- 
guifli  any  of  its  Parts.  This,  notwithftanding,  appeared  before  his  Microfcope  as  in  the 
Figure  at  a  a,  where  the  very  Top  of  the  Needle  is  {hewn  above  a  Quarter  of  an  Inch 
broad  j  not  round  or  flat,  but  irregular  and  uneven. 

The  whole  Piece  we  have  here  the  Pidure  of,  (according  to  the  Scale  given  with  it) 
is  little  more  than  the  twentieth  Part  of  an  Inch  in  Length,  and  appeared  to  the  naked 
Eye  exquifitely  fmooth  and  polifhed  ;  but,  as  feen  by  the  Microfcope,  what  a  Multitude  of 
Holes  and  Scratches  are  difcovered  to  us.?  How  uneven  and  rough  the  Surface!  how  void 
of  Beauty  !  and  how  plain  a  Proof  of  the  Deficiency  and  Bunglingnefs  of  Art,  whofe  Pro- 
ductions when  mofi;  laboured,  if  examined  with  Organs  more  acute  than  thofe  by  which 
they  were  framed,  lofe  all  that  fancied  Perfe<5tion  our  Blindnefs  made  us  think  they  had ! 
Whereas,  in  the  Works  of  Nature,  the  farther,  the  d.=eper  our  Difcoveries  reach,  the 
more  fcnfible  we  become  of  their  Beauties  and  Excellencies. 

But  to  return  to  the  Objed  now  before  us ;  A,  B,  Q  reprefent  large  Hollows  and 
RoughncfTes,  like  thofe  eaten  into  an  Iron-Bar  by  Ruft  and  Length  of  Time.  D  is  fome 
fmall  adventitious  Body  flicking  thereto  by  Accident. 

b.  b.  b.  fliew  the  End  where  thii  Tmall  Piece  of  Needle  v/as  broken  ofr,  in  order  to 
take  the  better  View  of  it. 

Ai  ihirp  as  a  Needle  is  a  common  Phrafe,  whereby  we  intend  to  exprefs  the  mofl  ex- 
quifite  Degree  of  Sharpnefs ;  and,  indeed,  a  Needle  has  the  moft  acute  Point  Art  is  ca- 
pable of  making,  however  rude  and  clumfy  it  appears  when  thus  examined.  But  the  Mi- 
crofcope can  afibrd  us  numberlefs  Inftmces,  in  tlie  Hairs,  Brifilc?,  and  Claws  of  Infeds  ; 
and  alfo  in  the  Thorns,  Hooks,  and  Hairs  of  Vegetables,  of  vifible  Points  many  Thou- 
fands  of  times  fharper,  with  a  Form  and  Polilh  that  proclaim  the  Omnipotence  of  the:- 
Maker. 

Another  investigation  was  carried  out  by  Hooke  on  the  "  edge  of 
a  razor,"  and  to  quote  his  words. 

Figure  reprefents  the  Edge  (about  half  a  Quarter  of  an  Inch  long)  of  a  very 
{harp  Razor  well  fet  upon  a  good  Hone,  and  fo  placed  between  the  Objed-Glafs  and 
the  Light,  that  there  appeared  a  Rertedion  from  the  very  Edge,  which  is  fhewn  by  the 
white  Line  a,  b,  c ,  d,  e,  f. 

When  we  fpeak  of  any  thing  as  extremely  keen,  we  ufually  compare  it  to  the  Edge 
of  a  Razor  J  but  we  find,  wiicn  examined  thus,  how  far  from  Sharpnefs  even  a  Razor's 
Edge  appears :  That  it  feems  a  rough  Surface,  of  an  unequal  Breadth  from  fide  to  fide, 
but  fcarce  any  where  narrower  than  the  Back  of  a  pretty  thick  Knife  :  That  it  is  neither 
fmooth,  even,  nor  regular ;  for  it  is  fomewhat  fharper  than  elfewhere  at  d,  indented  about 
/>,  broader  and  thicker  about  c,  unequal  and  rugged  about  e,  and  mofl:  even  between  ^,  b^ 
and  f-,  f^  though  very  far  in  any  Place  from  being  really  firaighr. 

The  Side  immediately  below  the  Edge,  and  what  the  naked  Eye  accounts  a  Part  of  it, 
^,  h^y^  k,  had  nothing  of  that  Polifh  one  would  imagine  Bodies  fo  fmooth  as  a  Hone  and 
Oil  (liould  give  it ;  but  was  full  of  innumerable  Scratches  crofling  one  another,  w^ith  Lines 
here  and  there,  more  rugged  and  deep  than  the  relf,  fuch  as  g,  h,  y,  /',  a,  occafioned  pro- 
bably by  fome  fmall  Duft  falling  on  the  Hone,  or  fome  more  flinty  Part  of  the  Hone 
itfelf. 

The  other  Part  of  the  Razor  L  L,  which  had  been  poliflied  on  a  Grind-flone,  appeared 
like  a  plowed  Field,  full  of  Ridges  and  Furrows. 

The  irregular  dark  Spot  w,  w,  feemed  to  be  a  little  Speck  of  Ruft ;  corrofive  Juices  ge- 
nerally  working  in  fuch  a  manner. 

This  Examination  proves,  how  rough  and  unfeemly  (had  we  microfcopic  Eyes)  thofe 
Things  would  appear,  which  now  the  Dulnefs  of  our  Sight  makes  us  think  extremely 
neat  and  curious :  And,  indeed,  it  feems  impofllble  by  Art  to  give  a  perfedl  Smoothnefs 
to  any  hard  and  brittle  Body  ;  for  Piitt\\  or  any  other  foft  Pov/der,  employed  to  polifli 
fuch  Body,  mufl:  neceflarily  confifb  of  little  hard  rough  Particles,  each  whereof  cut- 
ting its  Way,  muft;confequently  leave  fome  kind  of  Furrow  behind  Jt.  In  fliort,  this  Ed^^e 
of  a  Razor,  had  it  been  really  as  the  Microfcope  fliews  it,  would  fcarce  have  ferved  to  chop 
Wood,  inllead  of  (having  a  Man's  Beard. 


14  '  INTKODUCTOKY   ADDRESS: 

In  the  Bibliography  accompanying  the  present  Address  will  be 
found  reference  to  some  of  the  writings  of  other  early  workers  with 
the  Microscope.  For  example,  Antony  van  Leeuwenhoek,  born  at  Delft 
in  1632,  constructed  the  first  practical  microscope  and  established  the 
art  of  properly  grinding  and  polishing  the  Lenses. 

Leeuwenhoek  w^as  offered,  and  accepted,  the  post  of  Chamberlain 
of  the  Sheriff  of  the  town  of  Delft,  worth  £26  annually,  and  held  this 
for  39  years.  Li  February,  1680,  he  was  made  a  Fellow  of  the  Eoyal 
Society.  Although  he  never  came  to  London,  the  Diploma  of  Fellowship 
was  sent  to  him  in  a  silver  box,  having  the  Arms  of  the  Society  graven 
on  it.  An  interesting  account  of  his  life  is  given  by  the  President  of  the 
Royal  Microscopical  Society,  Professor  H.  G.  Plimmer,  F.R.S.,  in  his 
Presidential  Address  in  1913. 

Leeuwenhoek  did  wonderful  work  with  his  simple  or  singular 
Microscope.  The  largest  magnification  he  obtained  was  about  160 
in  one  of  his  Microscopes  :  his  twenty-six  other  Microscopes  varied 
from  40  to  133  magnifications.  With  this  simple  instrument,  as 
Professor  Plimmer  points  out  in  his  address,  Leeuwenhoek  discovered 
a  new  world,  in  fact  new  w^orlds,  for  us.  He  saw  for  the  first  time 
Infusoria,  Rotifers,  and  Bacteria.  It  is  interesting  to  note  in  this 
connection  that  Charles  Darwin  took  no  compound  Microscope,  but 
only  a  simple  one,  with  him  on  his  famous  "  Beagle  "  Voyage. 

So  important  was  Leeuwenhoek's  w^ork  that  I  give  a  portrait  of 
him  (Fig.  8). 

In  the  paper  "  On  the  Construction  of  the  Compound  Achromatic 
Microscope "  by  Charles  Brooke,  M.A.,  F.R.S.,  read  before  the 
Royal  Institution  of  Great  Britain,  March  10th,  1854,  he  states 
that  the  first  compound  Microscopes^  on  record,  such  as  that  of 
P.  Bonnani,  about  1697,  which  was  placed  horizontally,  and  that  of 
J.  Marshall  in  the  beginning  of  the  eighteenth  century,  which  was 
vertical,  were  furnished  with  central  condensers.  In  later  years  the 
development  of  the  illuminating  apparatus  has  by  no  means  kept  pace 
w^ith  that  of  the  ocular  portion  of  the  Microscope,  though  scarcely  of 
less  importance  in  attaining  the  highest  perfection  in  the  vision  of 
microscopic  objects. 

On  the  authority  of  Adams,  the  first  three  compound  Microscopes 
were  said  to  be  those  of  Hooke,  Eustachio  Divinis  and  Phili]^ 
Bonnani.  An  account  of  Divinis'  Compound  Microscope  was  read 
before  the  Royal  Society  in  1668  (Philosophical  Transactions  No,  42). 

It  must  be  borne  in  mind,  too,  that  the  progress  made  in  the  science 
of  Optics  was  largely  aided  by  the  great  work  of  Sir  Isaac  Newton, 
Delavel  and  Herschel. 


1700  TO  1800  A.D. 

It  is  stated  by  Roberts-Austen  also  in  his  *'  Metallurgy  "  that  the 
Microscope  was  first  apj^lied  to  the  Examination  of  L'on  and  the 
first  records  go  back  to  1722  when  Reaumur  described  the  structure 
of  Chilled  Castings  under  the  Microscope.       Franyois  in   1832  took 


SIR     ROBEET     HADFIELD,     BART.  15 

the  ini.eresting  case  of  the  direct  reduction  of  Iron  from  its  Ores,  and 
followed  the  successive  changes  by  the  aid  of  the  Microscope.  Roberts- 
Austen  also  claims  that  :  ''  If  to  these  analytical  data  observations 
under  the  Microscope  with  a  magnification  of  300  to  400  diameters  be 
added,  it  is  seen  that  ordinary  Iron  is  merely  a  metallic  network  with  a 
close-grained  tissue,with  submerged  scoriaceous  opaline,  sometimes  sub- 
crystalline,  portions,  and  with  little  globules  and  metallic  grains  ranged 
in  every  direction.  Sometimes  nests  of  translucent  prismatic  and 
bacillary  crystals,  with  metallic  portions  adhering,  are  noticed  hidden 
in  the  paste.  These  are  the  grains  of  Steel  which  can  be  made  to 
•disappear  by  heating." 

Roberts-Austen  thought  that  Modern  Metallography  owed  some 
of  its  development  to  the  use  made  of  it  in  the  Study  of  Meteoric 
Irons,  also  that  it  is  quite  possible,  as  has  often  happened  in  the 
History  of  Science,  that  there  are  several  independent  origins. 


From  1800  A.D.  Onwards. 


It  is  interesting  to  note  that  in  1808,  Widmanstatten  oxidized  a 
heated  specimen  and  took  polished  sections  of  meteoric  iron,  thus 
originating  what  is  now  termed  "  Metallography." 

Sorby  in  1856  founded  Petrography,  employing  sliced  sections  in 
connection  with  the  Microscope  for  the  study  of  rocks,  the  structures 
of  which  are  in  some  cases  analogous  to  those  of  metallic  alloys. 
In  the  year  1864  he  made  an  examination  of  meteoric  iron, 
also  studying  various  metallurgical  products ;  while  in  1885  he 
discovered  Pearlite  When  Sorby  proposed  for  the  first  time 
to  submit  a  specimen  of  rail,  which  had  broken  and  caused  an  accident, 
to  a  microscopic  analysis,  he  was  told  that  it  was  an  insane  idea.  Sorby 's 
method  has  since  been  invaluable  for  this  very  purpose — in  fact  in 
this  Country  and  in  America  and  elsewhere  tens  of  thousands  of 
photomicrographs  have  been  prepared  in  connection  with  the  investiga- 
tion of  broken  and  other  rails. 

Mr.  J.  Stuart— himself  a  veteran  of  some  eighty-four  years — 
•of  the  Clapham  Common  Optical  Works  of  Messrs.  Ross,  told 
nie  recently  that  in  the  'seventies  of  the  last  Century  he  had  repeated 
visits  from  Dr.  Sorby,  who  brought  various  specimens  of  Steel  for 
examination  under  the  Microscope.  Mr.  Wenham,  Vice-President 
of  the  Royal  Microscopical  Society  and  the  Inventor  of  the  Binocular 
Microscope,  as  well  as  of  other  microscopical  apparatus,  was  at  that 
time  working  w4th  Messrs.  Ross  as  their  Scientific  Adviser.  Mr. 
Wenham  was  also  interested  in  the  study  of  the  structure  of  steel  and 
had  many  conversations  with  the  late  Dr.  Sorby,  in  fact,  constructed 
for  him  a  high  power  Binocular  which  Mr.  Stuart  believes  was  the  first 
to  be  used  in  connection  with  the  examination  of  Steel. 

Incidentally  it  may  be  useful  to  refer  to  the  fact  that  the  invention 
of  the  Oil  Immersion  Objective  was  not,  as  is  often  imagined,  of  foreign 
origin,  but  was  originated  by  Mr.  AVenham  in  1870,  that  is,  six  or  seven 


16  INTRODUCTORY   ADDRESS: 

years  before  Oil  Immersion  Objectives  were  constructed  at  Jena  hy 
Professor  Abbe.  In  a  Paper  read  by  Mr.  Wenham,  entitled  "Remarks 
on  High-power  Definition,"  at  a  meeting  of  the  Royal  Microscopical 
Society  in  June  of  that  year  1870,  he  says  :  "Of  course  there  is 
no  optical  advantage  attendant  upon  the  use  of  water  in  immersion 
lenses.  If  a  medium  of  the  same  refractive  power  as  the  glass  were 
to  be  emj^loyed  the  result  would  be  better.  Water,  having  a  low 
refractive  index,  an  adjustment  is  required  for  each  thickness  of  cover, 
and  a  difference  of  adjustment  is  not  so  marked  and  sensitive  as  in  the^ 
ordinary  dry  objective  ;  but  if  a  medium  of  similar  refraction  to  the 
glass  were  to  be  used,  no  adjustment  would  be  required  for  any  thick-, 
ness  of  cover,  supposing  the  test  obj  ects  to  be  mounted  thereon  (which 
they  generally  are),  for,  in  fact,  we  should  then  view  them  all  with  a 
front  of  the  same  thickness — considering  the  cover,  the  front  lens  and 
the  interposing  medium  as  one." 

In  addition  to  reading  this  Paper,  Mr.  Wenham  exhibited  at  the 
same  Meeting  an  Oil  Immersion  Lens  using  Cedar  Oil  and  an  illuminated 
object  showing  great  brilliancy.  It  appears,  however,  he  did  not 
at  the  time  realise  that  his  Oil  Immersion  could  have  yielded  the  great 
numerical  aperture  which  it  afterwards  gave  in  the  hands  of  Professor 
Abbe. 

Another  interesting  point  is  the  fact  that  Andrew  Ross,  the  founder 
of  the  firm  of  Messrs.  Ross,  discovered  the  system  of  the  Collar 
Adjustment  for  Water  Immersion  Lenses  and  that  Mr.  Wenham 
was  the  Discoverer  of  the  Oil  Immersion  which  required  no  Collar 
Correction. 

To  show  how  little  was  thought  of  the  Microscope  as  a  scientific 
instrument  in  connection  with  the  study  of  Iron  and  Steel,  reference 
may  be  made  to  a  Book  which  I  have  often  found  useful,  namely^ 
Ferdinand  Kohn's  "  Iron  and  Steel  Manufacture,"  published  about 
1868  and  based  upon  a  series  of  valuable  articles  on  "  The  Manufacture 
of  Iron  and  Steel,"  which  appeared  in  "  Engineering."  In  this 
book  Kohn  says,  in  the  chapter  devoted  to  "  Steel  under  the 
Microscope,"  "An  experienced  steelmaker  can  estimate  very  closely  the 
ferrous  quality,  chemical  composition,  tensile  and  compressive  strength 
of  any  sample  of  steel,  and  even  the  mode  of  treatment  which  it  has 
undergone,  by  looking  at  its  fracture  under  the  Microscope." 

It  appears,  however,  this  only  meant  a  small  hand  Microscope.  The 
following  are  the  words  :  "A  Pocket  Microscope  of  this  kind  ought  to 
be  the  companion  of  every  man  interested  in  Steel  or  Steel  Manufacture. 
Lenses  of  the  usual  kind,  even  if  piled  up  in  sets  of  three  or  four,  are 
entirely  insufficient.  The  Lens  must  be  of  a  very  small  focus,  and 
properly  achromatic.  A  little  practice  is  sufficient  to  enable  the  user 
to  "  see  "  through  this  Lens  ;  but  it  is,  of  course,  not  quite  so  easy 
to  learn  the  meaning  of  what  is  seen,  and  to  estimate  from  the  appear- 
ance the  quality  of  the  steel  inspected." 

Special  reference  was  made  to  some  investigations  then  being 
carried  out  (1868)  by  Mr.  Schott,  the  Manager  of  Count  Stolberg's 
Foundry  at  Islenburg,  upon  the  appearance  of  liquid  and  solidifying 
Cast  Iron  imder  the  Microscope.      Mr.  Schott  contended  that  each 


SIR     ROBERT     HADFIELD,     BART.  17 

crystal  of  iron  is  a  double  pyramid  upon  a  flat  square  base,  and  that 
the  ratio  of  height  to  base  of  the  pyramid  is  proportional  to  the  carbon 
content.  In  Cast  Irons  and  hard  Steel  the  crystals  approach  the 
cubical  form,  whilst  in  Wrought  Iron  the  pyramids  are  almost  flattened 
down  into  leaves.  In  addition  the  quality  of  a  steel  is  shown  by  the 
arrangement  of  the  crystals.  The  highest  quality  of  steel  has  its 
crystals  in  parallel  positions  with  their  axes  in  the  direction  of  the 
pressure  exerted  on  them  in  working.  An  examination  of  the  fracture 
of  a  good  steel  in  reflected  light  shows  a  series  of  parallel  streaks  on 
the  surface,  whereas  in  a  bad  steel  several  systems  of  parallel  lines 
can  be  seen. 

The  presence  of  segregated  material  and  size  of  the  grain  can 
also  be  seen  under  the  Microscope.  The  absence  of  the  former  and 
the  fineness  of  the  latter  indicate  good  material. 

The  qualities  of  parallelism  of  the  material  and  fine  grain  seem  to 
be  due  to  difterent  causes.  The  former  seems  to  be  caused  by  the 
action  of  heat,  and  repeated  melting  is  the  great  panacea  in  this 
respect,  whilst  the  latter  is  brought  about  largely  by  w^orking  the 
material ;  on  the  other  hand  working  the  material  seems  to  prove 
that  parallelism  and  high  temperature  bring  about  the  coarsening  of 
grain. 

Singular  to  say,  Kohn  does  not  make  a  single  reference  to  the  work 
of  Sorby,  which  was  evidently  then  only  knowTi  by  few  people. 

Dr.  Dallinger,  F.R.S.,  who  resided  many  years  in  Shefiield,  gave 
in  the  Journal  of  the  Royal  Microscopical  Society,  Vol.  17, 
1877,  page  224,  a  "  Note  on  the  Ultimate  Limit  of  Vision "  as 
applied  to  modern  Microscopical  Lenses.  He  reasoned  that  mathe- 
maticians of  the  first  order,  notably  Helmholtz,  had  concluded  that 
the  limit  of  vision  had  been  reached  and  that  the  Optician  could 
practically  give  no  further  aid.  Dr.  Dallinger  considered  that  the 
limit  marked  out  was  about  the  one-hundred-and-eighty-thousandth 
of  an  inch,  and  added  that  he  did  not  consider  the  limit  of  visibility 
had  been  reached. 

Dr.  Sorby  in  a  Paper  on  the  "  Limit  of  the  Powers  of  the 
Microscope "  to  the  same  Society  in  1875  referred  to  an  experi- 
ment of  Dr.  Royston-Pigott  w^hich  showed  that  the  smallest  visual 
angle  he  could  ever  distinctly  appreciate  was  a  hole  1 J  in.  in  diameter 
at  a  distance  of  1,000  yards,  which  corresponds  to  about  6  seconds  of 
arc.  This  visual  arc  in  a  Microscope  magnifying  1,000  linear  would 
correspond  to  about  three-millionths  of  an  inch. 

Tchernoff  took  up  the  study  of  crystallization  of  Steel, 
his  work  being  brought  before  this  Country  by  the  late  Sir 
William  Anderson.  In  1878  Wedding  studied  Steel  by  the  aid 
of  the  Microscope.  The  work  of  these  investigators  caused  rapid 
increase  of  interest  in  this  subject. 

Dr.  Martens  of  Berlin  rendered  further  valuable  services,  in  fact  was 
one  of  the  first  to  introduce  the  practical  study  of  Iron  and  Steel  by 
Metallography.  Martens'  w^ork  commenced  about  1878,  when  he 
published  notes  on  the  Microstructure  of  Steel. 


18  INTRODUCTORY   ADDRESS: 

In  1880  tlie  use  of  the  Microscope  was  introduced  at  Le  Creusot 
Works,  and  important  investigations  by  Professors  F.  Osmond  and 
J.  Werth  were  started,  and  from  that  date  were  carried  out  on  the 
lines  first  indicated  by  Dr.  Sorby. 

In  his  Book  on  "  How  to  Work  with  the  Microscope,"  1880  edition, 
Dr.  Lionel  S.  Beale,  F.R.S.,  a  former  President  of  the  Microscopical 
Society,  gave  an  interesting  statement  as  to  the  methods  of  preparing 
specimens  when  examining  the  Microstructure  of  Iron  and  Steel. 

Roberts- Austen  in  his  book  already  quoted  does  just  credit  to  the 
important  work  carried  out  in  this  Country  by  Professor  J.  0.  Arnold, 
F.R.S.,  who  had  the  great  advantage  of  being  in  touch  and  collaborating 
with  the  late  Dr.  H.  C.  Sorby — in  fact  the  mantle  of  Sorby  descended 
upon  him.  Arnold  commenced  his  work  about  1890,  and  the  World 
is  under  a  debt  of  gratitude  for  the  important  results  obtained  by  his 
valuable  labours  in  this  field  of  research. 

Professor  Arnold  tells  me  that  his  first  association  with  Sorby  was 
about  1885  at  the  Natural  Science  Section  of  the  Literary  and  Philoso- 
phical Society  in  Sheffield,  where  I  also  met  him.  When  Arnold  was 
appointed  to  the  Chair  of  Metallurgy  in  the  University  of  Sheffield  in 
1889  he  persuaded  Sorby  to  resume  his  micrographic  work  on  Steel  in 
conjunction  with  his  (Arnold's)  work  on  Chemical  Analysis,  Recales- 
cence  and  Mechanical  Testing,  feeling  sure  that  micro  work  was  a 
vital  factor,  necessary  to  render  more  complete  our  knowledge  of 
steel.  However,  Sorby  stated  he  had  so  much  on  hand,  and  his 
eyesight  was  failing,  that  he  was  not  able  to  take  up  the  work 
again,  but  how  glad  he  was  to  find  that  his  pioneer  work  was  con- 
sidered to  be  helpful  to  Metallurgy.  Sorby  lent  Arnold  all  his  pioneer 
sections  during  his  lifetime  and  in  his  Will  left  them  to  the  Metallur- 
gical Department  of  the  University  of  Sheffield.  Sorby  also  gave 
Arnold  his  various  data  and,  on  several  occasions,  went  through 
his  different  sections,  which,  singular  to  say,  were  afterwards  destined 
to  be  Arnold's  for  eleven  years.  Through  the  kindness  of  Professor 
Ripper  these  specimens  are  exhibited  this   evening. 

It  may  be  added  that  Sorby  discovered  at  least  five  constituents 
of  Steel,  Stead  three,  and  the  Sheffield  University — largely  the  work 
of  Arnold  himself — was  responsible  for  many  of  the  others  now  known 
to  the  World.  It  was  also  Arnold  who  determined  the  quantitative 
composition  of  Sorby 's  Pearlite  and  Harden  ite. 

Dr.  J.  E.  Stead,  F.R.S.,  also  at  an  early  date  saw  the  great  im- 
portance of  this  branch  of  investigation,  and  by  his  lucid  papers  and 
research  work  has  greatly  aided  the  progress  of  Metallography. 

Osmond's  unrivalled  research  work  further  established  modern 
Metallography  in  1895.  He  discovered  successively  the  constituents 
of  Quenched  Steel  and  accurately  determined  the  critical  points  of 
Iron.  Moreover  he  had,  along  with  Werth,  previously  described 
the  cellular  structure  of  metal.  As  vSauveur  says,  if  Sorby  was  the 
pioneer  of  Metallography  and  Tchernoff  its  father,  Osmond  has  been 
its  torch-bearer. 

The  work  of  the  Nomenclature  Committee  on  Metallography  is 
useful  to  those  interested  in  this  subject,  and  will  be  found  in  Vol.  I 


SIR     ROBERT    HADFIELD,     BART.  19 

of  the  Iron  and  Steel  Institute  Journal,  1902,  comprising  some  twenty- 
three  pages  in  its  Glossary  of  Terms. 

In  addition  to  the  main  Societies,  who  have  assisted  in  developing 
Microscopy,  have  been  the  following :  The  Sorby  Scientific  Society, 
comprising  The  Sheffield  Microscopical  Society,  and  The  Sheffield 
Naturalist's  Club,  which  were  amalgamated  on  January  1st,  1918 ; 
the  Quekett  Microscopical  Club  ;  the  Dublin  Microscopical  Club,  and 
the  Photomicrographic  Society. 

Special  reference  may  be  made  to  the  excellent  work  of  the 
Quekett  Club,  which  is  probably  the  most  active  Microscopical 
Club  in  any  Country.  Its  Headquarters  are  in  London,  and  Meetings 
are  held  from  time  to  time.  The  present  occupant  of  the  Presi- 
dential Chair  is  Dr.   A.  B.  Rendle,  M.A.,  F.R.S. 


SECTION  III.— MODERN  WORK  ON  MICROSCOPES, 
OBJECTIVES  AND  EYE-PIECES. 

Mr.  Conrad  Beck,  F.R.M.S.,  many  years  ago  did  valuable  work 
on  behalf  of  Microscopy  in  his  Cantor  Lectures  before  the  Royal  Society 
of  x4.rts,  1907,  on  "  The  Theory  of  the  Microscope."  Previous  to  these 
Lectures,  Mr.  John  Maynall,  junr.,  gave  Mvo  excellent  series  of  Lectures 
on  the  same  subject,  entitled  "  The  History  of  the  Microscope,"  before 
the  same  Society. 

An  able  Address  was  read  by  Air.  Joseph  E.  Barnard,  now 
President  of  the  Royal  Microscopical  Society,  in  February,  1919, 
on  "  The  Limitations  of  Microscopy."  Everyone  interested  in  this 
subject  should  read  the  Address,  which  is  divided  into  various 
subjects,  dealing  with  dimensions  met  with  in  Microscopy,  a  discussion 
on  the  resolving  power  and  limits  of  resolution  and  visibility  ;  also 
descriptions  of  the  Ultra-Microscope  and  of  experiment  sillustrating 
its  use,  together  with  a  discussion  of  the  advantages  of  ultra-violet 
light  in  ordinary  Microscopy  ;  and  finally  suggestions  as  to  future 
lines  of  Research. 

As  this  paper  points  out,  the  limit  of  resolution  may  be  said  to 
have  been  reached  when  it  is  not  possible  to  distinguish  the  details  of 
the  specimen  under  examination.  The  limit  of  visibility  is,  however, 
lower  than  this,  for,  although  no  detail  can  be  seen,  the  specimen  can 
be  made  visible  as  a  spot  in  the  field  of  view. 

The  question  of  Resolution  is  touched  upon,  from  which  it  appears 
that  under  the  most  favourable  circumstances,  the  practical  limit  is 
reached  when  objects  in  a  row  are  about  "20  micron  (1/50,000  cm.) 
apart.  If  the  body  is  less  than  this  size  under  the  best  microscopic 
conditions  now  available  no  detail  can  be  distinguished. 

The  Ultra-Microscope  shows  the  presence  of  much  smaller  dimensions 
than  those  mentioned  above,  that  is,  as  bright  specks  on  a  dark 
background,  but  it  shows  none  of  the  internal  features,  and  no  matter 
what  the  shape  or  nature  of  the  object  under  view,  it  always  appears 
circular.  The  smallest  particle  observable,  that  is,  in  the  Ultra- 
Microscope,  is  that  of  colloidal  gold,  about  5  micromilHmeters 
(1/2,000,000  cm.)  in  diameter.  Thus  the  Ultra-Microscope  can  dis- 
tinguish particles  about  forty  times  smaller  than  those  which  can  be 
resolved  under  the  ordinary  Microscope. 


20  INTRODUCTORY   ADDRESS: 

Mr.  Barnard  showed  in  his  Address  that  whilst  the  resolving  power 
of  a  given  instrument  depends  upon  its  design,  it  also  depends  upon 
the  w^ave-length  of  the  light  used  to  illuminate  the  object  under 
examination.  Thus,  if  the  object  is  illuminated  with  ultra-violet 
rays  greater  resolution  still  can  be  obtained,  but,  of  course,  the  results 
are  not  directly  visible  and  must  be  recorded  photographically. 

In  a  paper  recently  read  before  the  Royal  Microscopical  Society  by 
Colonel  J.  Clibborn,  CLE.,  B.A.,  on  "  A  Standard  Microscope,"  it  was 
stated  by  Mr.  Conrad  Beck  that  the  Manufacturers  of  Microscopes 
worked  under  great  difficulty  during  the  War.  It  was  not  until  after 
the  11th  November,  1918,  that  any  Microscopes  were  allowed  to  be  made, 
all  the  Factories  being  fully  engaged  on  other  Optical  Instruments. 
It  is  interesting  to  note,  however,  that  these  Firms  are  now  spending 
large  sums  in  manufacturing  tools  for  the  production  of  Microscopes, 
many  of  them  to  be  made  under  the  Specifications  brought  forward 
by  the  Committee  on  Microscopes  appointed  by  the  British  Science 
Guild. 

At  the  recent  British  Scientific  Products  Exhibition  an  excellent 
set  of  Exhibits  was  shown  by  the  British  Optical  Instrument  Manu- 
facturers' Society,  Ltd.  Some  dozen  or  more  of  the  principal  firms 
exhibited  Optical  Instruments  and  Glasses. 

As  pointed  out  in  the  valuable  Catalogue  of  that  Exhibition,  the 
Optical  Instrument-making  Industry  originated  in  most  of  its  Branches 
in  Great  Britain.  Newton,  Young,  Faraday,  Clerk  Maxwell  and  Rayleigh 
were  the  pioneers  of  Optics.  The  Achromatic  Telescope  was  invented 
by  DoUand,  and  the  modern  form  of  Achromatic  Microscope  by  Lister. 
Let  us  therefore  show  that  we  are  trying  to  be  worthy  successors  of 
these  great  men. 

The  Optical  Association  has  published  an  illustrated  booklet  on 
Scientific  Instruments,  which  includes,  with  a  brief  description,  the  name 
of  every  known  instrument  both  current  and  obsolete,  together  with  a 
key  to  the  British  Makers.  The  Trade  has  set  up  a  powerful  Research 
Association  and  has  participated  in  the  inauguration  of  a  Scheme  of 
Education  in  Optical  Engineering  which  is  being  developed  by  the 
Imperial  College  of  Science  and  Technology  at  South  Kensington. 
It  may  be  mentioned  that  the  Governing  Body  of  the  Imperial 
College  of  Science  and  Technology  recognises  the  importance  of 
Technical  Optics  in  their  relation  to  the  needs  of  the  Nation  by  pro- 
viding in  the  Estimates  of  their  new  Scheme  of  Development  the  sum 
of  £50,000  for  expenditure  on  Land,  Buildings  and  Equipment,  and  the 
sum  of  £4,000  annually  for  maintenance  and  carrying  on  the  work. 

Messrs.  Chance  Brothers  commenced  the  manufacture  of  Optical 
Glasses  in  England  in  1848.  During  the  recent  War  they  increased 
their  output  some  twenty-fold.  They  make  something  like  seventy 
different  types  of  Optical  Glasses  together  with  a  number  of  new  types 
which  have  been  recently  introduced.  They  have  rendered  great 
service  to  our   Empire. 

Professor  J.  C.  McLennan,  F.R.S.,  of  the  University  of  Toronto,  who 
was  in  England  during  the  War,  informed  me  that  he  had  examined 
the  Fluorite  from  South  Africa  and  found  it  to  be  excellent  in  quality. 


SIR     EGBERT    HADFIELD,     BART.  21 

If  this  Fluorite  can  be  used  in  the  manufacture  of  Glass  suitable  for 
High  Power  Objectives,  then  the  South  African  source  of  supply 
should  be  borne  in  mind.  It  is  also  stated  that  Fluorite  exists  in 
Canada,  and  our  Honorary  Treasurer,  Dr.  Robert  Mond,  is  inves- 
tigating this  matter, 

The  King  recently  visited  the  Leicester  Works  of  Messrs.  Taylor 
and  Hobson,  the  f-amous  Lens  experts.  He  there  saw  the  instru- 
ments by  which  vital  errors  of  a  few  milHonths  of  an  inch  are 
avoided,  and  had  explained  to  him  the  principles  of  the  use 
in  this  connection  of  light  interference,  which  w^as  first  studied  by 
Sir  Isaac  Newton  in  Soap  Bubbles.  This  Firm  also  make  the  "Aviar  " 
Lens,  which  through  repeated  calculations  and  readjustments  of 
formulae  enabled  the  British  Photographing  Aeroplanes  to  beat  the 
"  Archies." 

In  a  recent  number  of  the  "  Scientific  American  Supplement " 
(August  30th,  1919),  a  statement  is  made  that  in  spite  of  the  traditional 
superiority  of  the  German  Optical  Industry,  during  the  War  their 
Lenses  proved  distinctly  inferior  to  those  of  French  and  English  make. 
The  English  developed  superior  Lenses  during  and  under  the  stress  of 
the  War. 

In  a  perfect  High  Power  Objective  known  as  Apochromatic,  it  is 
desirable  this  should  give  :— 

(a)  Full  Resolution. — The  resolution  increases  with,  and  is  a 
function  of.  Numerical  Aperture.  The  number  of  lines  to  the  inch 
which  an  objective  w^ill  resolve,  if  perfect,  may  be  calculated  from 
the  Numerical  Aperture. 

(b)  Good  Definition. — Which  could  be  magnified  by  a  x  28 
eye-piece    or    its    equivalent  w^ithout  breaking  down. 

(c)  A  Perfectly  Flat  Field. — This  is  never  actually  obtained. 
{(l)    Freedom  from  Chromatic  Aberration. 

Achromatic  Lenses  generally  give  good  definition  and  their 
field  is  often  somewhat  flatter  than  in  that  of  the 
Apochromats.  They  do  not,  however,  give  such  good  resolution, 
and  are  only  partially  colour  corrected.  The  latter  failing  makes 
them  much  less  efficient  than  the  Apochromats  for  photographic 
work. 

The  foreign  2  mm.  Objective  used  in  the  Hadfield  Laboratory  is  a 
very  good  one  of  its  class.  Its  Numerical  Aperture  is  1.3,  and  there- 
fore according  to  the  formula  of  Professor  Abbe,  should,  if  perfect, 
resolve  about  92,000  lines  to  the  inch.  I  have  had  photographs  taken 
by  it  which  show  85,000  lines  to  the  inch  clearly  resolved.  Its 
definition  begins  to  break  dowTiwith  an  eye-piece  magnification  of  about 
15.  For  an  Apochromat  its  field  is  very  flat,  and  it  is  in  this  respect 
chiefly  that  we  found  it  superior  to  other  Apochromats  we  examined. 
Its  colour  correction  is  apparently  perfect. 

It  may  be  added  that  Messrs.  Watsons  supplied  to  the 
Research  Laboratory  of  my  firm   a  very  excellent  2  mm.  Objective. 


22  INTRODUCTORY   ADDRESS: 

In  fa?t  photomicrographs  ( btained  with  it  seemed  to  possess 
almost  equal  quality  to  those  from  the  lest  foreign  objectives. 
Fig.  13  is  a  photomicrograph  of  a  specimen  of  Steel  -  taken 
with  the  above-mentioned  foreign  2  mm.  Apochromat,  whilst  Fig. 
12  is  a  photomicrograph  of  the  same  section  under  exactly  similar 
conditions,  taken  with  the  Watson  2  mm.  Apochromit.  It  will  be 
seen  that  tliere  is  veiy  little  to  choose  between  the  two  photographs 
from  the  point  of  view  of  resolution  and  flatness  of  fieli.  There  is 
no  doubt  that  English  makers  can,  when  required,  produce  Objectives 
at  least  equal  in  quality  to  the  best  foreign  makes. 


SECTION   IV.— FERROUS  METALLOGRAPHY. 

Several  excellent  Works  have  been  published  on  the  important  sub- 
ject of  Metallography,  including  "  Physical  Metallurgy,"  by  Dr.  Walter 
Rosenhain,  F.R.S.,  which  has  proved  of  the  highest  service.  N'o  book,  too, 
on  the  subject  has  been  of  greater  use  in  the  past  than  that  by  Professor 
Albert  Sauveur,  of  Harvard  University,  "  The  Metallography  of  Iron 
and  Steel."  Great  advances  have  been  made  since  the  date  of  its 
first  publication,  and  in  the  second  edition,  1916,  it  remains  a 
standard  work  of  reference  and  a  model  for  books  on  a  special  subject 
• — excellent  matter,  well  printed  and  illustrated.  The  chapters  are 
divided  into  Lessons,  some  twenty-four  in  all,  commencing  with 
the  Study  of  Pure  Metals  ;  Pure  Iron  and  Steel,  up  to  High 
Carbon  Percentages  ;  the  Effect  of  Impurities  Upon  Steel  ;  Close 
Studies  of  Thermal  Critical  Change  Points  ;  the  Effect  of  Annealing, 
Hardening  and  Tempering  upon  both  ordinary  and  Special  Alloy 
Steels,  are  considered.  The  Metallography  of  Cast  Iron  also  receives 
attention.  Various  Apparatus  for  the  Metallographic  Laboratory, 
including  the  study  of  the  Microscope  itself,  and  the  Apparatus, 
Illumination,  Sources  of  Light,  Condensers,  and  Photomicrographic 
Cameras  ;  a  description  of  the  best  Methods  and  Manipulations  ;  also 
a  most  excellent  nomenclature  of  the  various  Microscopic  Constituents, 
including  Austenite,  Cementite,  Martensite,  Ferrite,  Osmondite, 
Ferronite,  Hardenite,  Pearlite,  Graphite,  Troostite,  Sorbite,  Manganese 
Sulphide,  and  Ferrous  Sulphide. 

In  words  which  deserve  consideration  by  us  all,  so  I  quote  them 
in  full.  Professor  Sauveur  in  his  Introduction  and  Remarks  upon 
the  Industrial  Importance  of  Metallography,  points  out  : 

"Invaluable information  is  given  by  chemistry  without  which  both 
the  physicist  and  the  metallurgist  would  be  in  utter  darkness,  but  this 
science  throws  little  or  no  light  upon  the  anatomy  of  living  or  inanimate 
matter.  Its  very  methods,  which  call  for  the  destruction  of  the  ])hysical 
structure  of  matter,  show  how  incapable  it  is  to  render  assistance  in 
this,  our  great  need. 

The  parallel  drawn  here  between  metals  and  living  matter  is  not 
fantastic.  It  has  been  aptly  made  ly  Osmond,  who  said  rightly 
that  modern  science  was  treating  the  industrial  metal  like  a  living 
organism,  and  that  we  were  led  to  studv  its  anatomy,  that  is,  its  jiliy- 
sical  and  chemical  constitution  ;    its  biology,  that  is,  the  influence 


SIR    ROBERT    HADFIELD,     BART.  23 

exerted  on  its  constitution  by  the  various  treatments,  thermal  and 
mechanical,  to  which  the  metal  is  lawfully  subjected  ;  and  its  patho- 
logy, that  is,  the  action  of  impurities  and  defective  treatments  upon 
its  normal  constitution. 

Fortunately  Metallography  does  more  than  reveal  the  proximate 
composition  of  metals.  It  is  a  true  dissecting  method  which  lays 
bare  their  anatomy — that  is,  the  physical  grouping  of  the  proximate 
constituents,  iheir  distribution,  relative  dimensions,  etc.,  all  of  which 
necessarily  affect  the  properties.  For  two  pieces  of  steel,  for  instance,' 
might  have  exactly  the  same  proximate  composition — that  is,  might 
contain,  let  us  say,  the  same  proportion  of  pearlite  and  ferrite,  and  still 
differ  quite  a  little  as  to  strength,  ductility,  etc.,  and  that  because  of  a 
different  structural  arrangement  of  the  two  proximate  constituents  ; 
in  other  words,  because  of  unlike  anatomy. 

It  is  not  to  be  supposed  that  the  path  trodden  during  the  last  score  of 
years  was  at  all  times  smooth  and  free  from  obstacles.  Indeed,  the 
truth  of  the  proverb  that  there  is  no  royal  road  to  knowledge  was 
constantly  and  forcibly  impressed  on  the  minds  of  those  engaged  in 
the  arduous  task  of  lifting  metallography  to  a  higher  level. 

Its  short  history  resembles  the  history  of  the  development  of  all 
sciences.  At  the  outset  a  mist  so  thickly  surrounds  the  goal  that 
only  the  most  courageous  and  better  equipped  attempt  to  pierce  it 
and  perchance  they  may  be  rewarded  by  a  gleam  of  light.  This  gives 
courage  to  others,  and  the  new  recruits  add  strength  to  the  besieging 
party.  Then  follow  the  well-known  attacking  methods  of  scientific 
tactics  and  strategy,  and  after  many  defeats,  and  now  and  then  a 
victorious  battle,  the  goal  is  in  sight,  but  only  in  sight  and  never  to 
be  actually  reached,  for  in  our  way  stands  the  great  universal  mystery 
of  nature  :    what  is  matter  ?    what  is  life  ? 

Nevertheless  there  is  reward  enough  for  the  scientist  in  the  feeling 
that  he  has  approached  the  goal,  that  he  has  secured  a  better  point  of 
vantage  from  which  to  contemplate  it.  The  game  was  worth  the 
candle,  and  if  scientific  workers  must  necessarily  fail  in  their  efforts 
to  arrive  at  the  true  definition  of  matter,  whatever  be  the  field  of  their 
labour,  they  at  least  learn  a  great  deal  concerning  the  ways  of  matter, 
and  it  is  with  the  ways  of  matter  that  the  material  world  is  chiefly 
concerned.  Hence  the  usefulness  of  scientific  investigation,  hence 
the  usefulness  of  metallography." 

Among  the  many  workers  who  have  contributed  to  the  progress  of 
Metallography  may  be  mentioned : — Arnold,  Benedicks,  Belaiew, 
Brearley,  Carp3nter,  H.  LeChatelier,  Campbell,  Desch,  Edwards,  Elliot, 
Guillet,  Gulliver,  Giolitti,  Hatfield,  Honda,  Howe,  Humfrey,  Hudson, 
Zay  Jeffries,  Law,  Martens,  McCance,  Osmond,  Portevin,  Roberts- 
Austen,  Rosenhain,  Robin,  Sorby,  Sauveur,  Stead,  Thompson,  Werth. 

In  the  valuable  Pocket  Encyclopaedia  on  "  Iron  and  Steel  "  by 
Mr.  Hugh  P.  Tiemann,  B.S.,  A.M.,  with  an  introduction  by  Professor 
H.  M.  Howe,  some  thirty  pages  are  devoted  to  Metallography.  The 
book  contains  a  most  excellent  summary  of  the  terms  used  in  this 
Branch  of  the  Science  of  Metallurgy,  treating  of  the  constitution  and 
structure  of  Metals  and  Alloys,  also  their  relation  to  physical 
properties. 


24  INTRODUCTORY   ADDRESS: 

Tiemann  says  that  originally  the  term  Metallography  concerned 
principally  the  visual  examination  of  the  structure  of  metals,  and 
hence  was  divided  into  Microscopic  Metallography,  or,  briefly, 
Micrometallography,  where  Microscopes  were  used  to  secure  high 
magnifications,  and  Megascopic,  Macroscopic  or  Macro-Metallography, 
where  the  naked  eye  or  very  low  magnifications  were  used.  The 
terms  Microscopy  and  Micrography  are  also  used. 

With  reference  to  Metallographic  Examination,  Tiemann  considers 
that  the  methods  employed  may  be  classified  into  : — 

(1)  Optical  Analysis  :  Determining  the  Constituents,  struc- 
tures, forms,  appearances,  etc.,  by  the  eye  alone  or  assisted  by 
suitable  magnifying  devices. 

(2)  Thermal  Analysis  :  A  Study  of  the  nature  of  metals 
and  alloys  by  means  of  heating  and  cooling  curves,  changes  in 
specific  heat,  etc. 

(3)  Magnetic  Analysis  :  Determination  of  changes  in  nature 
affecting  the  magnetic  properties. 

(4)  Physical  Analysis:  Determination  of  the  properties  by  the 
usual  methods  of  testing. 

(5)  Chemical  Analysis:  Both  proximate  and  ultimate ;  generally 
in  conjunction  with  one  of  the  other  methods. 

He  defines  the  Microscope  as  follows  : — 

(a)  A  simple  Microscope  is  one  which  has  only  one  Lens  or 
set  of  Lenses  ;  a  compound  Microscope  has  two  such 
systems  of  Lenses,  one  near  the  object  (Objective)  and 
the  other   near  the  eye  of  the  observer  (Eyepiece). 

(b)  The  binocular  Microscope  consists  of  two  instruments 
mounted  to  give  a  stereoscopic   (perspective)  view. 

As  regards  the  minute  nature  of  matters  forming  metals  and  alloys 
of  metals,  an  interesting  statement  is  made  by  Mr.  Zay  Jeffries,  D.Sc, 
Cleveland,  U.S.A.,  who,  when  speaking  of  the  ageing  of  the  non-ferrous 
metal  known  as  Duralumin,  in  his  paper  on  "The  Micro-mechanism  of  the 
Ageing  of  Duralumin,"  says  that  when  it  is  cooled  from  500°  C.in  a 
furnace,  globules  of  CuAlg  large  enough  to  be  seen  easily  with  a  high 
power  Microscope,  are  formed.  In  the  same  sample,  however,  some 
globules  are  so  small  as  to  be  hardly  distinguishable,  and  others  too 
small  to  be  resolved  are  suggested  by  the  non-uniformity  of  the  surface 
appearance  of  the  section.  When  it  is  considered  that  the  smallest 
globule  of  CuAlj  resolvable  with  a  high  power  Microscope  contains 
about  2,000,000,000  molecules,  it  is  evident  that  with  rapid  cooling 
sub-microscopic  particles  of  CuAU  must  be  present  in  large  numbers  ; 
in  fact,  after  quenching,  the  average  size  of  a  particle  must  be  sub- 
microscopic.  The  whole  phenomenon  of  ageing  must,  therefore, 
involve  changes  which  cannot  be  studied  directly  with  a  Microscope. 

The  same  author  has  devoted  a  great  amount  of  time  to  the 
study  of  grain  sizes  and  their  measurement  in  metals.  He  has 
contributed  several  papers  to  the  Faraday  and  other  Societies  in 
this  country.  Much  vahiable  information  is  to  be  found  in  the  work 
done  by  Dr.  Zay  Jeffries. 


SIR    ROBERT    HADFIELD,     BART.  25 

Preparation  of  Specimens  and  Etching.— In  the  preparation 
of  specimens  for  micro-examination  great  skill  and  ingenuity  have  been 
displayed  by  numerous  investigators  from  the  time  of  Sorby  onwards. 

When  it  is  considered  that  a  maximum  magnification  has  now  been 
reached  of  about  8,000,  the  difficulties  to  be  overcome  will  be  readily 
recognised.  Supposing  the  surface  of  one  side  of  a  cube,  say  one 
twenty-fifth  of  an  inch  square,  to  be  under  examination,  this  ^  has 
meant  that  the  area  under  observation  has  been  multiplied  or  magnified 
to  a  surface  of  say  30  ft.  square,  or  about  900  square  feet.  It  will  be 
*  seen  how  the  slightest  scratch  or  groove,  imperfect  polishing,  bad 
etching,  or  other  defect  will  at  once  interfere  with  the  desired  results 
being  obtained. 

In  this  connection  I  should  like  also  to  call  attention  to  an 
interesting  Paper  read  by  Sir  G.  T.  Beilby,  F.R.S.,  before  the  Royal 
Society  in  February,  1914,  entitled  "  Transparence  or  Translucence 
of  the  Surface  Film  produced  in  Polishing  Metals."  Some  beautiful 
Photomicrographs  are  there  shown,  photographed  by  a  3  mm.  Oil  immer- 
sion Lens  of  1.4  N.A.  The  thickness  of  the  films  covering  the  slight  Pits 
on  a  Copper  surface  was  stated  by  Sir  George  to  be  probably  of  the 
order  of  10  to  20  micro-millimetres  i^^^^looo  ^^  1.200000  i^^^)- 

Although  if  it  was  possible  to  get  raw  surfaces  free  from  all  grooves, 
scratches,  and  other  blemishes,  some  structure  would  be  developed, 
it  must  be  remembered  that  not  even  the  finest  polishing  will  display 
structure,  therefore  etching  must  be  employed. 

The  etching  accomplishes  two  things  :  it  removes  the  amorphous 
layer,  and  then  attacks  the  various  constituents  differently.  The 
products  of  the  etching  attack  usually  differ  in  appearance  more  than 
the  original  constituents. 

For  high  power  the  etching  must  be  very  light,  that  is,  the  time 
of  etching  must  be  short.  A  5  per  cent,  solution  of  picric  acid  in 
alcohol  gives  the  best  results.  The  perfect  flatness  of  the  polished 
surface  must  be  retained,  and  only  the  lightest  possible  etching  is 
given.  In  low  power  w^ork  the  etching  is  fairly  strong  in  order  to- 
obtain  contrast  between  the  light  and  dark  portions. 

As  regards  the  effect  of  different  kinds  of  etching,  I  invite  attention 
to  Photomicrographs,  Figs.  9,  10  and  11.  These  are  from  a  Gun 
Tube  Steel  containing  .42  per  cent.  Carbon,  .74  per  cent.  Manganese, 
and  representing  material  as  forged,  that  is  without  further 
treatment. 

Fig.  9  was  etched  with  5  per  cent.  Picric  Acid  in  Alcohol. 
Fig.  10  was  etched  with  5  per  cent.  Nitric  Acid  in  Alcohol. 
Fig.  11  was  etched  with  5  per  cent.  Solution  Meta-Nitro-Benzol- 
Sulphonic  Acid. 

The  structure  shows  grains  of  Ferrite  on  a  ground  mass  of  Pearlite 
and  the  Photomicrographs  prove  that  the  Structure  developed  is  in  Ic- 
pendent  of  the  particular  etching  reagent  used.  The  number  of  etching 
reagents  might  be  extended  on  this  work  with  practically  the  same 
results  in  each  case.  Most  Alloy  Steels,  for  example.  Manganese 
Steels,  quenched  and  tempered.  Nickel  Chromium  and  other  Steels,. 


26  INTRODUCTORY   ADDRESS: 

require  extraordinary  en  re  in  the  etching  or  otherwise  the  structure 
will  vary  considerably  and  be  misleading.  Some  alloys,  for  example 
St^el  containing  high  percentage  of  Nickel,  are  not  attacked  by  any 
ordinary  etching  reagent. 

All  honour  to  Sorby,  the  man  who  led  the  way  in  this  branch  of 
Science,  and  started  us,  who  are  to-day  benefiting  in  such  a  remarkable 
manner  from  the  knowledge  he  first  originated  and  obtained  in  this 
important  and  complex  branch  of  Science.  All  honour,  too,  to  the 
band  of  willing  workers  who  have  accomplished  such  great  progress, 
^nd  who  have  surmounted  the  many  difficulties  in  their  path. 


SECTION  v.— STANDARD  MAGNIFICATIONS  FOR 
PHOTOMICROGRAPHS. 

The  question  of  the  Standardisation  of  Magnifications  for  Photo- 
micrographs of  Metals  and  Alloys  has  been  given  a  certain  amount  of 
discussion  both  in  this  Country  and  in  America. 

Committee  E-4  of  the  American  Society  for  Testing  Materials  has, 
in  fact,  drawn  up  tentative  '"'  Definitions  and  Rules  governing  the 
Preparation  of  Micrographs  of  Metals  and  Alloys,"  which  include 
Standard  Magnifications  for  general  use,  and  Ferrous  and  Non-ferrous 
Metals.  I  have  brought  this  matter  before  the  British  Engineering  Stan- 
dards Association,  who  are  considering  the  subject.  The  Institute  of 
Metals  in  this  Country  in  its  "Notes  for  Authors  "  also  specify  cer- 
tain Standard  Magnifications  which  it  is  desired  Authors  should  use. 

Whilst  not  wishing  in  any  way  to  hamper  the  Research  Worker, 
there  are  reasons  why  it  seems  strongly  advisable  that  for  general 
purposes  Standard  Magnifications  should  be  adopted  for  the  Photo- 
micrographs. Very  little  quantitative  data  is  forthcoming  from  the 
micro-examination  of  metals.  Where  the  grain  size  can  be  determined, 
this  is  often  distinctly  useful  and  worth  recording.  For  the  most 
part,  however,  the  Microscopist  is  dependent  on  a  trained  eye,  re- 
■sulting  from  prolonged  experience  in  the  examination  of  micro- 
structures  to  aid  him  in  their  interpretation.  It  would  seem  reasonable, 
therefore,  that  the  magnifications  used  should  be  standardised  and  as 
few  as  possible,  in  order  that  comparisons  between  the  structures  of 
different  specimens  may  h^  facilitated. 

I  would  therefore  like  strongly  to  urge  that  the  various  Societies 
interested  in  M^^tallography  should  join  in  drawing  up  rules  governing 
the  reproduction  of  photomicrographs,  which  should  be  of  certain 
Standard  Magnifications  and  naturally  should  be  reproduced  full  size. 

Surely  there  is  every  reason  for  having  an  International  Standard; 
at  any  rate,  Great  Britain  and  America  could  work  together.  It 
might  well,  indeed,  be  made  a  matter  for  Allied  consideration,  or 
one  for  consideration  in  connection  with  the  movement  for  the 
formation  of  International  Unions  in  which  the  Conjoint  Board  of 
Scientific  Soc'eties  is  interestinsr  itself. 


SIR     ROBERT     HADFIELD,    BART.  27 


SECTION  VL— CRYSTALLOGRAPHY. 

As  crystallography  is,  if  not  directly  then  indirectly,  related  to  the 
work  of  the  microscope,  I  have  asked  my  friend,  Dr.  A.  E.  H. 
Tutton,  F.R.S.,  the  eminent  crystallographist.  to  communicate  sugges- 
tions to  this  Symposium  by  way  of  a  Paper  or  to  the  Discussion 
from  his  point  of  view. 

During  the  recent  Meeting  at  Bournemouth  of  the  British  Associa- 
tion, Miss  Nina  Hosali,  B.Sc.  of  the  University  of  London,  exhibited 
interesting  Models  of  Crystals.  This  worker  has  most  kindly  sub- 
mitted her  collection  this  evening  and  I  am  sure  they  will  be  found 
useful. 

As  explained  by  Miss  Hosali,  the  object  of  these  models  is  to 
illustrate  : — 

(a)    The  forms  possible  to  crystals. 

(6)    The  different  kinds  of  symmetry  possessed  by  these  forms. 

(c)     How  the  forms  are  referred  to  crystallographic  axes. 

Each  model  illustrates  one  of  the  thirty-two  classes  of  symmetry, 
and  represents  several  crystal  forms  correctly  orientated  with  regard 
to  crystallographic  axes,  the  latter  being  shown  by  black  threads. 
A  model  consists  in  the  first  place  of  a  glass  envelope  whose  shape  is 
hat  of  some  simple  crystal  form,  and  within  this  envelope  two  or 
three  other  forms  are  represented  by  means  of  coloured  silk  threads 
stretched  over  frameworks  of  thin  copper  wire.  By  this  means  it  is 
■easy  to  make  the  forms  intersect  if  necessary,  and  they  are  readily 
■distinguished  from  one  another  by  the  use  of  differently  coloured 
threads. 

The  symmetry  elements  of  the  class  represented  by  any  model  are 
shown  as  follows  : — 

(a)    The  traces  of  the  Planes  of  Symmetry  on  the  Glass  envelope 
are  shown  by  steel  wires. 

(6)    Axes  of  Symmetry  are  shown  by  white  threads. 

The  set  of  24  models  exhibited  represents  21  out  of  the  32  classes 
and  over  70  different  forms.  In  many  cases  different  varieties  of  the 
forms  may  be  produced  by  rotating  or  inverting  the  models,  or  by 
reflecting  them  in  a  mirror,  and  when  these  modifications  are  taken 
account  of ,  the  number  of  the  forms  shown  is  brought  up  to  about  140. 

It  may  be  interesting  to  add  that  there  has  been  recently  developed 
and  described  by  the  Research  Committee  of  the  American  Society  ot 
Mechanical  Engineers  an  instrument  called  the  Microcharacter  (from 
the  Greek — to  engrave  or  scratch  on  a  small  scale).  This  instrument 
-determines  that  characteristic  of  a  crystal  which  is  the  combination 
of  three  of  the  five  fundamental  conceptions  of  hardness,  namely, 
the  combined  effect  of  cutting,  scratch,  and  penetration  hardness. 
It  can  be  employed  for  determining  the  hardness  of  the  micro-con- 
stituents of  steel  and  .should  be  very  useful  to  the  Metallographist. 
This  Apparatus  should  be  very   useful  to   the  Metallographer,  as  the 


28  INTRODUCTORY  ADDRESS: 

point  used  is  practically  sharp  under  a  magnification  of  no  less  than 
2000  diameters.  By  this  method  these  combined  characteristics  can 
be  obtained  for  any  individual  crystal,  a  point  of  great  importance. 


SECTION  VIL— THE    ULTRAMICROSCOPE. 

Much  study  has  been  given  to  the  Ultramicroscope,  which  was 
introduced  about  the  year  1905  by  Siedentopf  and  Zsigmondy. 

In  an  article  which  appeared  in  "  The  Scientific  American,"  October 
2nd,  1915,  it  was  stated  that  the  limits  of  microscopic  observation 
with  direct  illumination  is  about  ^~^  mm.  and  with  oblique  illumina- 
tion by  means  of  violet  rays  and  with  the  aid  of  monobromated 
naphthalene  immersion  ^qoooq  mm.  The  observation  of  particles 
below  this  may  be  termed  ultramicroscopic.  According  to  Siedentopf, 
particles  may  be  perceived  which  have  a  diameter  of  about  ^  qooooq 
to  ^  OOP  OOP  nim.  These  are  magnitudes  which  approach  very 
closely  to  molecular  dimensions  of  complicated  compounds,  in  some 
cases  even  attain  them. 

According  to  0.  E.  Meyer,  the  molecule  of  Hydrogen  has  a  diameter 
^^  10.000.000  ^"^-j  ^^^^^  according  to  Jaeger,  the  molecule  of  (a) 
ethyl-alcohol  has  a  diameter  of     p^  ^ —   mm.  ;    (b)  chloroform  has 

X  1  o.ooo.ooo  '     ^    ' 

a  diameter  of   ^-5-^^-^^   mm.      According  to  Lobry  de  Bruyn,  the 

molecule  of   starch  has  a  diameter  of  ^ mm.      Consequently 

.     .    1 .000,000  ^         / 

the  molecule  of  starch  must  be  within  the  leach  of  ultramicroscopic 
perception. 

The  investigator  has  therefore  before  him,  subject  to  increased 
intensity  of  light  and  dark  field,  the  possibility  of  seeing  molecules 
which  seemed  beyond  reach  of  human  sight,  and  the  hope  of  following 
the  play  of  their  attractive  and  repellant  forces.  The  brightness  of 
ultramicroscopic  particles  begins  to  decline  with  the  6th  power  of  the 
diameter. 

If  it  should  prove  possible  to  obtain  this  deeper  insight  into  the 
form  and  structure  of  matter,  a  positive  service  will  be  done  to  philo- 
sophy permitting  of  the  observation  of  particles  which  were  formerly 
far  below  the  limits  of  ordinary  microscopic  observation.  If  the 
methods  which  it  renders  possible  can  be  extended  and  applied  to 
Metallurgy,  then  the  Metallurgist  will  doubtless  be  possessed  of  still 
further  means  to  enable  him  to  advance  further  our  knowledge  of 
the  structure  of  metals  and  their  alloys. 


SECTION  VIII.— CONCLUSION. 

I  must  now  bring  these  remarks  to  a  close.  The  subject  is  a 
fascinating  one,  and  it  has  been  a  labour  of  love  to  trace  the  History 
of  the  Microscope  and  its  great  development  into  the  wonderful 
Scientific  Instrument  of  to-day,  capable  of  resolving  even  over 
100,000  lines  per  inch. 


SIR    ROBERT    IIADFIELD,     BART.  29 

If  Sorby  could  have  been  with  us  this  evening  it  would  be 
a  special  satisfaction  to  him  to  see  the  child  of  his  brain  grown 
to  the  giant  it  now  is,  I  mean  in  the  application  of  the  Microscope 
to  the  examination  of  Metals  and  their  Alloys.  In  a  separate  com- 
munication entitled  "  The  Great  Work  of  Sorby,  of  Sheffield,"  I  have 
dealt  briefly  with  his  Researches  in  this  field. 

In  addition  to  this  present  Address,  I  am  contributing  to  the 
Svmposium  a  Paper  on  the  Faraday  Society  and  its  Work ;  also  jointly 
with  Mr.  T.  G.  Elliot,  F.I.C.,  a  Paper  on  ''Photomicrographs  of  Steel 
and  Iron  Sections  at  High  Magnification,"  as  well  as  a  Bibliography 
from  1665  down  to  the  present  time,  which  although  not  claimed  to 
be  complete  may  be  found  useful  to  those  interested. 

I  trust  that  in  each  of  these  contributions  will  be  found  some 
information  that  may  be  of  interest  and  give  encouragement  to 
pursue  our  Researches  in  this  valuable  field  of  Scientific  Investigation. 


30 


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Hadfteld.-l. 


Dr.   H.  C.  SORBY.  F.R.S.,  of   Sheffield. 

President  of  the  Royal  Microscopical  Society  in  1875-7. 
Figure  i. 


Hadfield  — 2. 


DR.   W.    H.   DALLINGER,   F.R.S. 
Figure  2. 


HadJield      3. 


ZACHARI  A  S      I  AN  S  EN, 


Figure  3. 


Hadfield -4. 


HANS       LIPPERHEY, 


Figure  4. 


Hadfield. 


MICROGRAPHIA: 

OR     SOME 

Phyjiological   Vefcripions 

O  F 

MINUTE    BODIES 

M  A  D  E     B  Y 

MAGNIFYING    GLASSES- 

WITH 

Observations  and  I n  clu tries  thereupon. 

By  R,  HO  0  KE,  Fellow  of  the  Royal  Society. 

NonpoJJttoculo  quantum  contendere  Linceus^ 
Nontamenidcirco  contemnas  LJppus  inungi,  Horat.  Ep.  lib.  i. 


LONI>ONi?nntcd  by  Jo.  Martyn^  and  Ja.  Alleftry^  Printers  Co  die 

Royal  Societ  Y,andare  to  befoldat  their  Shop  at  the  5e^  in 

S^Paurs  Church-yard.   M  DC  LX  V. 


(f{eb'MTtf^i  ' 


Figure  5. — Representing:  the  front  pagre  of  Hooke's  ''  Micrographia,' 
published  in    1665. 


Figure  6. 


Point  of  a  needle,  magnified. 
Reproduced  from  a  Dra^Ying•  made  by    Hooke  in  the  year  1665. 


Figure  7. 

Edge  of  a  razor,  magnified. 
Reproduced  from  a  Drawing  made  by    Hooke  in  the  year  1665. 


These  Figures  are  about  three-fifths  size  of  Hooke's  enlargement. 


Hadfield.--7. 


^^s^^m^^^mi^H'^M- 


JiMT.  TT  ^^jE>'H  1 31LK . 


Figure  8. 


Hadfield.-8. 


Magnification    lOO. 
Etched  with  5%  Picric  Acid  in  Alcohol 


Ahignihcation    lou. 

I'^tchcd    with    5",,    Nitric   Acid   in    Alcohol. 

Figures  0  and  10. 

PhotomicroRrai)hs  showinR  that  the  Structure  of  a  Gun  Tube  Steel  is 

indei)endent    of   the   etching:   reag-ent. 


Hadftcld.— 9. 


^ 


Analysis:    C.  .42,  Mn.   .74%. 

Treaiment:    As   Forg-ed. 

The  Structure  shows  grains  of  Ferrite  on  a  ground  mass 
of  Pearlite. 


Magnification   100. 


Etched  with  5%  Solution  Meta-Nitro-Benzol-Sulphonic 
Acid. 


Figure  it. 

Photomicrog-raphs  showing-  that  the  Structure  of  a  Gun  Tube  Steel  is 
independent  of  the  etching  reagent 


Hadfield.     10- 


o  o 
J-    o 


^,       W 


u=; 


THE  PRESENT  POSITION  AND  THE  FUTURE  OF  THE 
MICROSCOPE— A  GENERAL  SURVEY. 

By  J.  E.  Barnard, 

President  of  the   Royal  Microscopical   Society. 

Mr.  J.  E.  Barnard,  President  of  the  Royal  Microscopical 
Society,  then  delivered  an  address,  of  which  the  following 
is  a  condensed  report,  in  which  he  indicated  future  lines  of 
development  in  microscope  design  and  in  microscopy. 


On  behalf  of  the  Royal  Microscopical  Society,  I  trust  I  may 
be  allowed  to  convey  to  Sir  Robert  Hjadfield  the  expression  of  my 
great  appreciation  of  the  efforts  he  has  made,  resulting  in  the 
holding  of  this  Symposium.  The  subject  is  one  that  is  in  need  of 
discussion;  but,  had  it  not  been  for  Sir  Robert's  scientific  insight 
and  energy,  it  is  unquestionable  that  the  meeting  would  never 
have  taken  place.  As  the  time  that  is  allotted  to  me  is  of  necessity 
short,  it  will  be  impossible  to  give  anything  like  a  full  survey  of 
the  subject  of  microscopy.  I  shall,  therefore,  be  compelled  to  limit 
myself  to  such  points  as  appear  to  me  to  be  of  interest,  although 
I  admit  that  I  am  not  always  selecting  the  ones  of  greatest  impor- 
tance. 

An  examination  of  the  programme  of  this  Symposium  might 
lead  to  the  conclusion  that  the  subject  of  metallography  was  the 
most  important  branch  of  microscopical  research.  In  point  of  fact 
this  is  not  so.  Although  the  importance  of  the  subject  is  admitted, 
yet  the  amount  of  attention  given  to  it  is  not  anything  like  so 
great  as  that  devoted  to  biological  researches.  It  is  therefore  pro- 
bably quite  true  that  ninety  per  cent,  of  the  microscopes  in  use 
at  the  present  time,  whether  in  this  or  any  other  country,  are  in 
the  hands  of  those  who  are  working  at  biological  subjects.  Even 
of  this  class,  the  science  of  medicine  will  absorb  the  greater  portion ; 
and  it  is  therefore  unfortunate  that  the  medical  side  of  the  subject 
is  treated  so  lightly — at  least,  if  we  may  judge  from  the  programme. 
It  is,  I  am  afraid,  only  in  accordance  with  the  accustomed  atti- 
tude in  medical  circles  for  little  interest  to  be  taken  in  pure  micro- 
scopy, although  in  diagnostic  work  the  importance  of  the  micro- 
scope has  never  assumed  a  larger  place. 

In  view  of  the  paucity  of  contributions  on  the  biological  side, 
I  shall,  therefore,  direct  more  attention  to  this  than  I  should  other- 
wise have  done,  and  the  few  remarks  X  make  will  be  more  par- 
ticularly in  relation  to  the  microscope  as  used  for  biological  research. 

37 


38  THE    PRESENT    POSITION    AND    THE 

A  consideration  of  the  microscope  resolves  itself  of  necessity 
into  two  parts,  the  mechanical  and  the  optical.  From  the  mech- 
anical standpoint  there  are  two  designs  in  general  use — those  referred 
to  as  the  Continental  and  the  English  form  of  microscope.  In  the 
Continental  type  it  has  usually  been  customary  to  have  what  is 
known  as  the  horseshoe  foot,  mainly,  I  imagine,  because  of  its  ease 
of  construction  by  mechanical  engineering  methods;  whereas  the 
English  design  of  microscope,  which  has  hitherto  been  mainly  made 
by  hand,  is  of  a  more  steady  type,  and  the  points  of  support  are 
so  distributed  as  to  give  more  stability  to  the  instrument  in  any 
position. 

The  essential  parts  of  the  instruments  are  a  coarse  adjustment, 
to  give  the  body  tube  a  quick  motion  in  the  direction  of  the  optic 
axis,  and  a  fine  adjustment,  which  gives  it  a  much  slower  motion 
in  the  same  direction.  The  tube  is  adjustable  in  length,  to  enable 
correction  to  be  made  for  varying  thicknesses  of  cover  glass,  althoiign 
a  large  number  of  workers  appear  to  regard  it  as  a  ready  method 
of  obtaining  greater  or  less  magnification,  with  disastrous  effects 
on  the  resulting  image. 

There  is  only  one  fixed  part  of  a  microscope  which  is  used  for 
biological  purposes,  and  that  is  the  stage.  But  metallographers 
require  that  the  stage  shall  also  be  adjustable  in  the  direction  of 
the  optic  axis.  The  body  tube  itself  should  be  made  so  that  it 
can  be  closed  to  a  length  of  140  millimetres,  including  any  objective 
changing  device  that  may  be  on  the  nose-piece ;  and  it  should  be 
possible  to  lengthen  it  to  at  least  200  millimetres  or  250  millimetres 
if  long-tube  objectives  are  used. 

All  these  adjustments  are  in  the  direction  of  the  optic  axis  of 
the  instrument.  Two  others  are  usually  provided,  which  are  at 
right  angles  to  this  direction — that  is,  a  mechanical  stage  for  actuat- 
ing the  object,  and  in  certain  of  the  best  class  instruments  an 
arrangement  for  centering  the  sub-stage  condenser  to  the  axis  of 
the  objective.  While  there  are  many  points  which  might  be  raised 
on  the  mechanical  side,  there  are  only  one  or  two  that  I  have  time 
to  mention.  The  main  points  about  most  microscopes  appears  to 
be  that  they  are  unstable.  I  have  a  considerable  number  in  my 
own  possession,  but  I  do  not  think  I  have  one,  even  now,  which, 
if  I  centre  an  object  on  the  stage  with  the  instrument  in  a  vertical 
position,  still  maintains  its  centration  accurately  if  the  instrument 
is  put  into  the  horizontal.  The  probability  is,  therefore,  that  there 
are  few  microscopes  made  at  the  present  time  that  exactly  fulfil 
the  conditions  necessary  for  high-class  photomicrographic  work,  or 
for  observational  microscopic  work  of  an  exacting  order.  I  trust, 
however, that  an  instrument  exhibited  at  this  Symposium  will  embody 
LJie  necessary  improvements  to  rectify  this  matter. 

Some  misa})])rehension  a])])ears  to  me  to  exist  also  as  to  the  rela- 
tive purpose  of  the  coarse  and  the  fine  adjustments.  The  coarse 
adjustment  should  be  sufficiently  well  made,  and  if  the  user  is 
sufficiently  expert,  to  enable  him  to  bring  into  view  any  object, 
whether  it  is  being  observed  with  a  low  or  a  high  power  objective. 
The  fine  adjustment  is  then  used  for  accurate  focussing  and  for  get- 
ting a  conception  of  the  object  in  de])th.  In  biological  work,  at  any 
rate,  this  is  very  rarely  the  state  of  affairs  as  carried  out.     In  using 


FUTUllE    OF    THE    MICKOSCOPE  39 

an  oil  immersion  objective,  for  instance,  a  common  method  is  to 
immerse  tke  objective  and  then  lower  it  so  that  it  all  but  touches 
the  top  surface  of  the  cover  glass.  The  objective  is  then  raised 
by  means  of  the  fine  adjustment  until  the  object  comes  into  view. 
While  this  may  act  fairly  well  with  very  thin  cover  glasses,  it  is 
a  haphazard  method  when  cover  glasses  of  varying  thicknesses  are 
used.  It  should  be  realised  that  when  microscope  users  are  sufii- 
ciently  educated,  they  will  be  able  to  tell  how  far  they  are  from 
the  actual  image  by  the  appearance  of  the  light  in  the  field  of  view, 
that  is,  if  the  object  is  illuminated  with  reasonable  accuracy. 

Mechanical  stages  also  appear  to  me  to  need  some  consideration. 
The  stages  which  will  on  actuation  cause  no  shift  of  the  object 
other  than  in  the  direction  intended,  or  any  alteration  of  focus, 
are  rare.  Further,  those  in  which  the  screws  project  over  the  side 
for  a  considerable  distance  with  the  result  that  any  slight  jar  or 
knock  causes  them  to  be  displaced,  and,  it  may  be,  actually  bent, 
are  objectionable  when  used  under  laboratory  conditions. 

There  is,  I  think,  much  to  be  said  for  the  type  of  stage  which 
has  either  co-axial  milled  heads  on  a  vertical  axis,  or,  if  incon- 
venient to  make,  milled  heads  which  are  on  separate  axes.  This 
method  of  construction,  I  think,  of  necessity  results  in  a  much 
stiffer  and  more  stable  stage.  There  is,  in  fact,  a  general  lack  of 
stability  going  through  nearly  all  parts  of  a  microscope.  But  it 
is  significant  that,  even  so  long  ago  as  the  beginning  of  last  century, 
the  instrument  as  then  designed  had  much  greater  attention  paid 
to  this  point.  The  microscope,  an  illustration  of  which  I  show  on 
the  screen,  is  to  my  mind  an  embodiment  of  a  principle  that  should 
receive  attention.  So  soon  as  English  makers  are  in  a  position  to 
consider  the  production  of  an  instrument  of  a  special  type,  it  is 
my  intention  to  have  one  made.  In  this  the  general  principle  is 
that  all  the  optical  parts  are  carried  on  a  bar  which  is,  in  effect, 
an  optical  bench,  and  that  this  is  strutted  in  such  a  way  as  to  give 
stiffness  to  the  instrument  as  a  whole.  The  only  effort  that  I  am 
aware  of  that  has  been  made  in  this  direction  is  in  the  microscope 
designed  by  Dr.  Rosenhain,  partichiarly  for  metallography,  but 
which  is  adaptable  for  ordinary  work.  This  instrument,  to  my 
mind,  is  such  an  improvement  on  any  other  type  of  stand  that  I 
am  at  a  loss  to  understand  why  metallographers  have  not  more 
generally  taken  it  up.  It  might  appear  that  I  am  exaggerating 
the  importance  of  stability  in  the  stand.  But  it  should  be  realised 
that  any  want  of  centration  in  the  optical  parts,  or  want  of  align- 
ment in  the  optic  axes  of  these  parts,  results  in  more  serious  dete- 
rioration of  the  resulting  microscopic  image  than  any  other  single 
factor.  The  optical  parts  of  a  microscope  are  the  objective, 
for  obtaining  the  primary  magnified  image  of  the  object  :  the 
ocular,  for  further  enlarging  that  image  and  transmitting  it  to  the 
eye ;  and  the  sub-stage  condenser,  for  illuminating  the  object  with 
a  larger  or  smaller  cone  of  light.  The  limitations  of  time  will  pre- 
vent me  from  doing  more  than  refer  very  briefly  to  some  properties  of 
the  optical   parts. 

It  is  generally  assumed  that  magnification  is  the  primary  func- 
tion of  an  objective.  But  in  point  of  fact  the  main  point  is  not 
magnification  but  resolution.     By  resolution  is  meant  the  power  the 


40  THE    PRESENT    POSITION    AND    THE 

objective  has  of  separating  and  forming  correct  images  of  fine  detail. 
That  known  as  the  Abbe  Diffraction  Theory,  is  the  theory  on 
which  modern  optical  calculations  are  based,  and  it  is  safe  to  say 
that  it  was  never  more  fully  accepted  and  never  rested  on  a 
surer  basis  than  at  the  present  time.  There  has  been  much  dis- 
cussion in  this  country  of  that  theory,  and  probably  a  good  deal 
of  misconception  has  arisen  from  its  inapt  designation;  for  the 
term  "  Diffraction  Theory  "  is  perhaps  somewhat  unfortunate.  I 
cannot  do  better  than  quote  the  late  I-iord  Rayleigh  in  refer.ence 
to  this  matter.  He  said:  "  The  special  theory  initiated  by  Professor 
Abbe  is  usually  called  the  Diffraction  Theory,  a  nomenclature  against 
which  it  is  necessary  to  protest.  Whatever  may  be  the  view  taken, 
any  theory  of  resolving  power  of  optical  instruments  must  be  a 
diffraction  theory  in  a  certain  sense,  so  that  the  name  is  not  dis- 
tinctive. Diffraction  is  more  naturally  regarded  as  the  obstacle 
to  fine  definition,  and  not,  as  with  some  exponents  of  Professor 
Abbe's  theory,  the  machinery  by  which  good  definition  is  brought 
about." 

This  very  clearly  and  accurately  sums  up  the  position.  The 
Abbe  theory  tells  us  that  there  are  two  main  factors  determining 
resolution:  that  is,  the  numerical  aperture  of  the  objective  used, 
and  the  wave-length  of  the  light.  Numerical  aperture  is  determined 
for  us  by  the  optician,  and  it  is  well  known  that,  with  an  oil- 
immersion  objective,  a  numerical  aperture  of  1.4  is  at  the  present 
time  the  practical  limit.  Metallographers  are  in  a  somewhat 
stronger  position,  as  a  mono-bromide  of  naphthaline  immersion 
objective  was,  and  presumably  still  is,  made  by  Zeiss,  which  had 
a  numerical  aperture  of  1.6.  This  represents  the  absolute  limit  at 
the  present  time,  and  there  is  no  indication  that  numerical  aper- 
ture will  be  incneiased  in  this  sense  by  present  methods. 

The  other  factor  governing  resolution  is  the  wave-length  of 
light,  and  in  this  connection  it  must  be  borne  in  mind  that  to 
resolve  a  regularly  marked  structure,  the  distance  between  the 
markings  must  be  more  than  half  a  wave-length.  Under  ordinary 
conditions  of  illumination  we  cannot  go  very  far  in  the  direction 
of  increased  resolution  unless  we  have  resort  to  an  illuminant  such 
as  a  mercury  vapour  lamp,  which  is  rich  in  blue  and  violet  radia- 
tions. There  is  much  room  for  investigation  in  this  direction,  as 
the  ideal  ilkmiinant  for  microscopic  work  has  3/et  to  be  found.  But 
I  do  not  know  of  any  one  that  approaches  so  nearly  to  it  as  the 
one  I  have  mentioned — the  mercuiy  vapour  lamp.  It  suffers  only 
from  one  disadvantage  that  I  can  see,  and  that  is  that  the  differ- 
entiation due  to  staining  is  not  so  clearly  brought  out  as  when 
ordinary  light  is  used.  But  as  staining  is  itself  an  artificial  process, 
and  is  simply  done  to  differentiate  structures,  it  only  means  a  certain 
amount  of  education  to  enable  us  to  appreciate  the  differences,  even 
under  the  light  from  this  lamp.  The  only  stains  which  it  does 
not  show  quite  well,  or,  rather,  in  which  the  colour-tint  is  altered, 
ai'e.  tho?e  in  which  red  ])redoini nates.  Anv  other  colour  is  shown 
perfectly  and  in  reasonable  gradation.  The  advantages  of  this 
illuminant  are  that  it  is  even  and  uniform.  It  has  a  fairly  large 
area,  and  can  be  used  therefore  for  any  class  of  wcrk.  It^  intensity 
can  be  varied  within  considerable  limits  by  having  a  resistance  in 
series,   so  that  the  current  density   is  altered  to   suit  the   particular 


FUTUKE    OF    THE    MICROSCOPE  41 

work  under  observation.  Further,  it  is  possible,  by  interposing 
neutral  screens,  to  vary  the  light  intensity  if  the  electrical  method 
is  inconvenient.  Owing  to  its  possessing  practically  no  red  radia- 
tions, its  mean  wave-length  is  shorter,  and  by  using  suitable  screens 
light  which  is  truly  monochromatic,  green,  blue  or  violet,  can  be 
obtained  at  will.  These  lamps  are  made  both  in  glass  and  quartz, 
but  the  quartz  ones  are  preferable,  because  they  admit  of  the  use 
of  heavier  current,  with  greater  luminosity;  and  further,  they  have 
a  much  longer  life.  I  have  exhibited  two  of  these  lamps,  because 
1  regard  them  as  far  in  advance  of  any  other  form  of  light  avail- 
able tc  the  microscopist  at  the  present  time,  whether  he  is  a  biolo- 
gist or  a  metallographer. 

The  whole  subject  of  illumination,  so  far  as  the  illuminant  is 
concerned,  needs  investigation  also,  because  there  is,  I  think,  little 
doubt  that  a  modification  in  the  intensity  of  the  illumination  of 
any  particular  object  enables  us  to  use  a  larger  light  cone  than 
we  could  do  under  ordinary  circumstances.  That  is,  variation  of 
the  intensity  is  an  alternative  to  the  use  of  the  iris  diaphragm  in 
the  sub-stage  of  the  microscope.  But  it  is  in  the  direction  of  using 
invisible  radiations  in  the  ultra-violet,  or,  it  may  be,  radiations 
which  are  still  shorter  than  the  ultra-violet,  that  developments  in 
microscopic  work  are,  in  my  opinion,  likely  to  occur. 

There  are  two  other  points,  which  I  can  only  refer  to,  but  which, 
I  trust,  may  be  dealt  with  more  fully  in  the  succeeding  papers. 
One  is  that,  while  the  resolution  limits  are  so  inflexible,  that  does- 
not  by  any  means  apply  to  mere  visibility.  By  illuminating  small 
particles  by  means  of  an  annular  cone  of  rays,  that  is,  what  is 
ordinarily  known  as  dark  ground  illumination,  or  by  illuminating 
them  at  right  angles  to  the  optic  axis  of  the  microscope — what  is 
known  as  the  ultra-microscopic  method — particles  of  a  very  much 
smaller  order  of  siz.e  can  be  made  visible.  But  we  cannot  tell  any- 
thing about  their  form,  nor  can  we  accurately  tell  their  size.  We 
are  only  conscious  of  their  mere  existence. 

Another  point  to  remember  is  that  magnification  is  definitely 
limited  to  something  like  750  diameters  with  microscopes  under 
ordinary  conditions,  if  we  want  to  get  the  best  optical  effect.  We 
may,  as  a  matter  of  convenience,  have  still  higher  magnifications, 
because  it  is  not  given  to  everybody  to  appreciate  fine  detail  unless 
an  image  is  somew^hat  enlarged.  But  it  must  be  appreciated  that 
any  increase  beyond  750  or  800  diameters  does  not  result  in  us 
seeing  anything  more.  It  simply  allows  us  to  see  the  object  on  a 
somewhat  larger  scale.  We  may  therefore  summarise  as  follows:  — 
An  object  which  is  much  smaller  in  size  than  the  resolution  limit 
can  be  rendered  visible,  providing  the  light  with  which  it  is  illuiu- 
inated  is  of  sufficient  intensity,  and  it  is  sufficiently  different  in 
refractivity  from  the  medium  in  which  it  lies.  To  resolve  a  series 
of  equi-distant  points  or  lines  in  an  object,  their  distance  apart 
must  exceed  half  a  wave-length  of  light  in  the  medium  in  which 
the  object  is  immersed.  Johnstone  Stoney  has  shown  that  a  pair  of 
lines  or  objects  can  be  separated  when  their  distance  apart  is  rather 
smaller  than  the  resolution  limit  required  for  a  number  of  points 
or  lines  in  a  row.  But  it  should  be  borne  in  mind  even  here  that 
the  resolution  limits  apply  if  a  definite  standard  of  definition  is 
required.      An  isolated  object,    or   pair   of    objects,    are    not   so  well 


42       THE    PRESENT    POSITION    AND    THE    FUTURE. 

defined  if  they  exceed  the  resolution  limits  as  laid  down  for  recur- 
ring structures.  It  cannot  be  too  fully  appreciated  that  illum- 
ination is  the  keynote  of  all  sound  microscopic  work,  and  this  applies 
whether  the  illumination  is  by  means  of  visible  radiation  under 
ordinary  conditions  of  w^ork,  or  whether  it  is  in  experimental  work 
in  which  the  use  of  invisible  radiations  are  concerned. 

There  is  much  room  for  research  in  this  direction,  and  it  is  to 
be  hoped  that  this  is  one  of  the  points  which  will  be  seriously  taken 
up.  Apart  from  any  question  of  research,  the  education  of  the 
user  is  perhaps  of  vital  importance.  It  is  little  use  for  opticians 
to  make  great  efforts  to  turn  out  a  satisfactory  instrument  if  the 
user  is  incapable  of  taking  advantage  of  the  quality  of  the  optical 
or  other  parts.  I  trust,  therefore,  that  this  Symposium  will  give 
an  impetus  in  this  direction,  and  that  it  will  help  microscope  users 
to  realise  how  much  remains  to  be  done. 


ADDRESS  BY  SIR  HERBERT  JACKSON,  K.B.E.,  F.R.S. 


At  this  stage  Sir  Herbert  Jackson  delivered  an 
Address,  which  is  printed  on  page  218  of  this  Report,  owing 
to  an  unavoidable  delay  in  preparing  it  for  publication. 


Professor  F.  J.  Cheshire,  C.B-.E.,  President  of  the 
Optical  Society,  read  a  paper  on  "  The  Mechanical  Design 
of  Microscopes." 

THE  MECHANICAL  DESIGN  OF  MICROSCOPES. 

By  Professor  F.  J.  Cheshire,  C.B.E., 
President  of  the  Optical  Society. 


The  optical  industry  in  this  country,  as  the  result  of  war  expe- 
rience, has  been  specially  recognised  by  the  Government  as  a 
key  industry,  which,  in  the  national  interests,  therefore,  must  be 
encouraged  and  preserved. 

Now  the  microscope,  whether  considered  from  the  point  of  view 
of  the  great  and  increasing  demand  which  it  makes  upon  the  highest 
technical  knowledge  and  skill  of  the  optician  and  the  mechanician, 
the  importance  of  the  work  which  it  is  called  upon  to  do,  or  the 
great  demand  for  it,  stands  forth  as  the  most  important  of  all  optical 
instruments.  It  is  thus  the  keystone  of  the  arch  of  a  key  industry. 
The  optical  industries  of  any  country  which  is  producing  micro- 
scopes for  which  there  is  a  world's  demand  must  be  in  a  healthy 
and  thriving  condition.  Conversely,  any  country  which  fails  to 
produce  a  microscope  to  meet  the  world's  demands  is  very  unlikely 
to  have  the  reputation  for  producing,  on  a  commercial  scale  at 
at  any  rate,  important  optical  instruments  of  any  kind.  The 
production  of  the  microscope  may  therefore  be  accepted  as  the  touch- 
stone of  national  success  in  optical  activities  generally.  The  impor- 
tance of  this  point  must  be  insisted  upon — when  England  can  pro- 
duce microscopes  in  large  numbers  for  the  world's  markets,  the 
success  of  her  industries  will  be  assured.  Until  it  does  so,  that 
success  cannot  be  accepted  as  assured. 


44       THE  MECHANICAL  DESIGN  OF  MICROSCOPES: 

The  development  of  a  mechanical  invention  which  is  ultimat-ely 
required  to  meet  a  big  demand,  usually  follows  upon  well  defined 
lines.  At  the  beginning,  when  the  demand  is  small,  the  labour 
of  highly  skilled  craftsmen  is  necessary  and  sufficient  for  its  pro- 
duction, but  later,  when  the  demand  has  increased,  it  is  found  that 
for  efficient  production  the  skilled  craftsman  is  no  longer  sufficient, 
but  special  machinery  must  be  put  down  to  replace  him.  In  other 
words,  artistic  production  is  followed  by  machine  production. 

As  an  illustration  of  production  in  the  artistic  period,  I  cannot 
do  better  tt.an  tell  you  a  story  that  was  told  to  me  some  years  ago 
by  the  late  Dr.  Czapski,  Dr.  Czapski  upon  one  occasion  visited 
Hartnack,  the  famous  maker  of  microscope  water-immersion  objec- 
tives. He  found  him  sitting  on  a  stool  in  front  of  a  window,  busily 
engaged  assembling  the  systems  of  his  objectives  with  the  aid  of 
a,  microscope  and  a  test-object.  On  the  table  by  his  side  were  a 
lumber  of  grooved  sticks,  each  filled  with  a  number  of  a  particular 
lens  wanted  in  a  ceitain  objective  combination.  Hartnack,  with 
his  great  knowledge  and  skill,  was  able  to  look  at  a  critical  object 
and  decide  from  its  appearance  what  lens  in  a  given  combination 
was  likely  to  be  responsible  for  the  observed  defects.  He  would 
then  try  another  and  slightly  different  one  in  its  place.  In  this 
way  he  would  try  combination  after  combination,  until  a  satisfactory 
result  was  obtained.  Occasionally  by  a  fortuitous  accident  he  would 
obtain  an  objective  much  superior  in  its  performance  to  the  general 
run.  These  were  carefully  put  on  one  side,  and  although  Hart- 
nack charged  a  uniform  price  for  all  his  objectives,  he  was  very 
careful  to  allow  none  but  serious  workers  to  obtain  possession  of 
the  best  quality  lenses.  Now  Abbe  realised  that  this  method  of 
production,  making  such  great  demands  upon  unique  knowledge  and 
skill,  could  not  possibly  meet  the  growing  world's  demand  for  micro- 
scope objectives,  and  therefore  that  the  highly  skilled,  technical 
artist  must  be  dispensed  with  and  replaced  by  mechanical  processes 
capable  of  producing  to  a  high  order  of  accuracy  predetermined 
elements.  This  was  done,  and  that  success  which  is  now  a  matter 
of  history,  achieved.  Some  time  ago  I  was  discussing  this  subject 
with  Sir  Howard  Grubb,  and  he  gave  me  a  remarkable  instance 
from  his  own  experience.  He  told  me  that  before  the  war  he  em- 
ployed a  skilled  man  to  rough  out  certain  lenses  by  hand  at  the 
rate  of  about  a  dozen  per  week.  When  the  war  broke  out  it  was 
realised  that  something  must  be  done  to  expedite  production,  and 
Sir  Howard  Grubb  invented  a  special  machine,  attended  by  a  girl, 
to  psrform  the  necessary  operation.  The  result  was  that  the  girl  and 
the  machine  turned  out  more  than  a  thousand  of  these  lenses  per 
week. 

It  follows  from  what  has  been  said  that  the  microscope  must 
meet  nc^t  only  the  demands  of  the  user,  it  must  meet  al?o  those  of 
the  manufacturer.  I  suggest,  therefore,  that  a  well  designed  com- 
mercial microscope  may  be  defined  as  one  that  can  be  made  both 
accurately  and  cheaply,  and  that  secures  in  its  use  "  the  greatest 
happiness  of  the  greatest  number."  First,  it  must  be  a  commercial 
article,  one  made  in  great  numbers  to  compete  in  the  markets  of 
the  world.  Secondly,  it  must  be  made  accurately  and  cheaply. 
These  requirements  necessitate  on  the  part  of  the  manufacturer 
specialisation,    standardisation,   production   by    repetition    machinery 


PROFESSOR    F.     J.     CHESHIRE  45 

of  the  most  modern  types,  attended  by  unskilled  labour;  the  whole 
of  these  activities  being  directed  by  the  highest  technical  knowledge 
and  skill.  Thirdly,  a  well  designed  microscope  must  confer  the 
greatest  happiness  upon  the  greatest  number  of  its  users.  In  other 
words,  it  must  meet  to  the  fullest  possible  extent,  the  needs  and 
demands  of  its  users.  But  these  demands  are  constantly  changing 
and  increasing.  Demands  resulting  from  war  experience,  for  ex- 
ample, are  already  of  a  formidable  nature,  and  are  certain  to  become 
greater.  One  fundamental  difFiculty  in  design  must  be  noted.  A 
good  design  having  been  evolved  to  meet  existing  requirements, 
there  is  always  a  strong  temptation  to  meet  new  requirements  by 
a  modification  of  the  old  design.  In  any  particular  case  this  may 
or  may  not  be  satisfactory,  but  one  is  often  inclined  to  wonder 
whether  this  subservience  to  tradition  has  not  resulted  in  the  per- 
petuation of  designs  which,  however  good  they  may  have  been  at 
one  time,  are  now  ill-adapted  to  meet  more  exacting  requirements. 
A  thorough  overhaul  of  the  design  of  the  microscope  by  thoroughly 
skilled  mechanicians,  without  reference  to  old  and  traditional 
designs,  might  lead  to  startling  and  valuable  results.  This  is  a 
point  of  great  importance  to  the  trade.  So  long  as  a  manufacturer 
confines  himself  to  the  production  of  well-known  designs,  he  must 
of  necessity  meet  with  keen  competition.  Should  he,  however,  be 
successful  in  introducing  new  and  valuable  features,  his  chance 
of  success  is  very  greatly  increased.  This  danger  of  too  close  an 
observance  of  traditional  designs  is  unfortunately  enhanced  by  mass 
production,  because  when  a  manufacturer  has  laid  down  expensive 
plant  to  produce  a  given  design,  it  often  pays  him — or  he  thinks  it 
does — to  buy  up  patents  for  improvements  upon  it,  and  throw  them 
into  the  waste-paper  basket. 

Again,  in  the  elaboration  of  a  standard  design  we  all  agree  that 
the  faddist  must  not  be  considered — the  greatest  happiness  of  the 
greatest  number  must  be  sought  for.  Here,  again,  the  matter  is 
not  so  easy  in  practice.  We  are  now  told  that  the  bullet  which 
eventually  brought  down  the  ZepiDclin  so  ignominiously  was,  in  the 
first  case,  refused  as  the  suggestion  of  a  crank.  Many  valuable  sug- 
gestions for  the  improvement  of  the  microscope  must  also  have  been 
turned  down  for  the  same  reason  in  the  past. 

Time,  unfortunately,  does  not  permit  of  any  consideration  or 
criticism  of  the  design  of  the  details  of  the  microscope,  but  there 
is  one  matter  of  some  importance  to  which  I  should  like  to  draw 
your  attention.  In  the  early  days  of  the  microscope  the  illuminating 
apparatus  was  of  the  simplest  kind,  generally  nothing  more  than 
t.he  sky  or  a  common  lamp,  the  light  from  which  was  thrown  upon 
the  object  by  a  simple  mirror.  Modern  work,  however,  demands 
a  well-corrected  condenser  of  large  aperture — or  it  may  be  a  dark- 
ground  illuminator — working  in  conjunction  with  a  small  and  intense 
light  source  accurately  adjusted  in  the  axis  of  the  complete  illumin- 
ating and  observing  systems.  Now  this  adjustment  of  the  light 
source  is  tiresome  in  the  case  of  an  expert,  and  difficult  in  the 
case  of  a  tyro,  and,  when  made,  a  touch  of  the  mirror,  or  a  slight 
accidental  displacement  of  the  microscope  or  the  lamp,  necessitates 
the  work  being  done  again.  This  difficulty  could  be  largely  removed 
by  the  simple  expedient  of  resting  the  microscope  and  the  lamp  on 
geometrical   bearings    of    the    three-radiating   groove   type.      In    the 


46         THE    MECHANICAL   DESIGN    OF    MICROSCOPES. 

case  of  the  microscope  these  grooves  could  be  cut  in  the  foot  of 
the  instrument  to  rest  upon  and  engage  with  three  studs  on  the 
table.  This  arrangement  would  be  simple  and  cheap,  and  would 
have  the  further  advantage  that  it  would  not  in  any  way  interfere 
with  the  use  of  the  microscope  in  the  usual  way — the  grooves  when 
not  in  use  would  not  scratch  the  table  top.  In  this  simple  way  the 
placing  of  th&  lamp  and  the  microscope  in  a  fixed  position  with 
respect  to  one  another,  would  be  secured.  It  would  then  only  be 
necessary  to  fix  the  mirror,  as  has  been  suggested  by  Mr.  J.  E. 
Barnard,  and  the  microscopist  would,  in  a  few  seconds,  be 
able  to  ensure  that  a  beam  of  light  was  being  thrown  accurately 
along  the  axis  of  his  microscope,  a  necessary  condition,  for  ex- 
ample, of  the  efficient  use  of  the  dark  ground  illuminator  in  bac- 
teriological work. 

I  have  not  been  able  to  say  much,  ladies  and  gentlemen :  the 
time  has  been  too  short,  but  I  hope  that  I  have  been  able  to  say 
something  which  will  assist  you  to  realise  the  national  and  far- 
reaching  importance  of  the  subject  with  which  we  are  concerned  at 
this  Symposium  to-day. 


Mr.  F.  Martin  Duncan,  President  of  the  Photomicro- 
graphic  Society,  then  gave  a  resume  of  his  paper,  "  Some 
Notes  on  the  History  and  Design  of  Photomicrographic 
Apparatus." 

SOME  NOTES    ON  THE  HISTORY  AND  DESIGN  OF 
PHOTOMICROGRAPHIC  APPARATUS. 

By  F.  Martin  Duncan,  F.R.M.S.,  F.R.P.S.,  F.Z.S. 
President  of  the  Photomicrographic  Society. 


No  survey  of  the  present  position  of  microscopy  would  be  complete 
without  a  reference  to  the  very  important  part  which  photomicro- 
graphy plays  as  a  means  of  accurately  recording  the  various  objects 
which  are  submitted  to  microscopic  examination.  To  the  investigator 
in  bacteriology,  biology,  and  metallography,  a  photomicrographic 
apparatus  is  to-day  an  essential  p?.rt  of  his  microscopic  outfit,  and 
therefore  the  consideration  of  the  design  of  such  apparatus  has 
become  a  matter  of  prime  importance. 

Scientific  workers  were  quick  to  realise  the  value  of  photography 
as  a  means  of  obtaining  an  unbiased  graphic  record  of  their  observa- 
tions, and  it  was  only  the  limitations  and  technical  difficulties  of 
the  early  processes  that  prevented  its  wider  use.  From  the  time  of 
its  first  discovery  there  have  been  microscopists  who  have  employed 
photography  in  preference  to  the  pencil.  Thus  in  1845  Doune  and 
Foucault  illustrated  their  ''Atlas  of  ^licroscoj^ic  Anatomy"  by  etch- 
ings from  photomicrographs  taken  on  Daguerreotype  plates,  while  as 
early  as  1835  Fox-Talbot  had  obtained  images  of  objects  in  the 
solar  microscope  by  means  of  his  recently  discovered  process.  It 
would  be  out  of  place  here  to  enter  into  a  description  of  the  early 
pioneers  of  photography,  intensely  interesting  though  the  subject  be, 
b_it  in  passing  one  cannot  heap  feeling  proud  of  the  fact  that  the 
discovery  of  photography  was  due  to  British  and  French  scientists 
alone,  and  that  the  first  to  apply  it  successfully  to  the  recording  of 
microscopic  objects  were  Fox-Talbot  in  England,  Daguerre  in  France, 
and  Draper  in  America.  And  since  those  first  days  of  the  history 
of  photomicrography,  it  has  been  in  France,  in  Great  Britain,  and 
in  America  that  the  greatest  experts,  the  most  notable  advances  and 
inventions,  and  the  most  perfect  apparatus  for  photomicrography 
have  been  produced."^ 

Naturally  the  apparatus  used  in  the  early  stages  of  the  application 
of  photography  to  microscopy  was  of  a  somewhat  crude  character. 
The  earliest  cameras  were  little  more  than  light-tight  boxes,  while 
many  of  the  pioneers  dispensed  with  any  form  of  camera  at  all,  the 

*  For  a  short  accooint  and  early  bibliography  see  an  article  entitled 
"Chapters  in  Photomicrography,"  which  I  contributed  to  the  British 
Journal  Photogra-phic  Almanac  for   1903,   pp.  691-725. 


48       SOME    NOTES    ON    THE    HISTORY    AND    DESIGN 

eye-piece  end  of  the  microscope  being  insetted  through  a  circular  hole 
in  the  wall  of  the  dark-room,  aud  the  Daguerreotype  plate,  or  the 
wet  collodion  plate  placed  upon  a  board  in  the  dark-room,  on  which 
the  image  formed  by  the  microscope  had  previously  been  focussed. 
Considerable  difficulties  had  to  be  overcome  in  obtaining  the  correct 
adjustment  that  would  yield  a  sharp,  crisp  image,  owing  to  the,  at 
that  time,  imperfect  corrections  of  microscope  objectives;  but 
gradually  from  such  crude  beginnings  the  practice  of  photomicro- 
graphy has  attained  to  its  present  high  standard  of  technique.  That 
the  rapid  improvement  and  high  standard  of  perfection  to  which 
microscope  objectives,  eye-pieces,  and  substage  condeinsers  have  leached 
are  largely  due  to  the  investigations  and  labours  of  Abbe,  Schott, 
and  Zeiss,  all  microscopists  will  readily  admit;  but  that  is  about  all, 
though  admittedly  it  is  a  very  important  contribution,  that  can 
honestly  be  claimed  by  Germany  as  her  share  towards  the  perfection 
of  photomicrography. 

I  know  that  opinions  are  very  sharply  divided  on  the  subject  ot 
the  microscope  stand  as  made  by  British  and  German  manufacturers, 
and  I  feel  that  much  of  the  criticism  that  has  been  levelled  at  the 
British  manufacturers  is  grossly  unfair  and  inaccurate,  because  in 
nine  cases  out  of  ten  the  would-be  critic  is  already  prejudiced  in 
favour  of  the  German,  has  not  a  thorough  technical  knowledge  or 
experience,  and  frequently  has  never  used  a  really  first-class  British 
stand.  I  am  quite  ready  to  admit  that  the  British  maker  has  turned 
out  some  very  poor  models,  but  so  has  the  German;  but  because 
the  Britisher  has  producfeid  some  cheap  models  of  poor  quality,  surely 
that  is  no  reason  for  damning  at  sight  everything  he  produces.  You 
are  not  going  to  encourage  home  enterprise  or  industry  by  such 
methods.  I  have  now  used  the  microscope  practically  daily  for  over 
thirty  years  in  my  biological  investigations,  and  during  that  time 
models  by  all  the  leading  British  and  Continental  manufacturers  have 
passed  through  my  hands,  and  have  been,  I  hope  and  believe, 
honestly,  critically,  and  impartially  tested.  Out  of  that  long  experi- 
ence I  am  bound  to  say  that  for  comfort  in  working,  rigidity,  and 
perfection  in  design  and  workmanship,  I  have  yet  to  see  the  German 
or  Continental  model  that  will  touch  the  very  best  productions  of  our 
leading  British  manufacturers.  In  no  branch  of  microscopy  is  the 
superiority  of  the  first-class  British  microscope  stand  more  readily 
demonstrated  and  realised  than  in  critical  high-power  photomicro- 
graphy, for  to  produce  the  best  results,  rigidity,  whether  in  the 
vertical  or  horizontal  position  of  the  microscope  body,  and  ease  of. 
manipulation  of  the  mechanism  of  the  substage  and  the  top  or 
object  stage  are  factors  of  vital  importance — factors  which  are  not 
present  in  the  horseshoe  foot,  or  the  finicky  studs  and  knobs  provided 
for  the  adjustment  of  substage  and  substage-condenser,  and  mech- 
anical stage,  in  the  German  models.  Even  the  large  Zeiss  model 
specially  designed  by  that  firm  for  photomicrography,  though  of  good 
workmanship,  suffers  from  these  inherent  defects  of  the  Continental 
model,  its  substage  mechanism  being  very  cramped,  and  the  mech- 
anical stage  provided  with  wretchedly  small  pinion  heads. 

The  microscope  stand  intended  for  critical  photomicrography  and 
orisfinal  research  should  have  a  solidly  cast  broad  tri]:)od  foot,  such 
as  is  present  in  the  large  research  model  of  Swift,  the  R.M.S-  model 


OF    PPIOTOMICROGRAPHIC    APPARATUS  49 

of  Baker,  or  the  Royal  a^d  Van  Heurck  models  of  Watson.  The 
focussing  of  the  substage  condenser  should  be  by  a  stout  pinion  of 
such  a  length  that  the  hand  does  not  have  to  grope  for  it  beneath 
the  stage,  and  should  be  provided  with  a  good  milled  head.  Fairly 
stout  pinions  and  milled  heads  should  also  be  provided  for  controlling 
the  vertical  and  transverse  movements  of  the  mechanical  stage,  while 
the  body-tube  should  be  of  large  diameter  to  admit  the  use  of  low- 
power  objectives  required  when  photographing  comparatively  large 
fields.  ■ 

Between  the  years  1889  and  1899,  Messrs.  Swift  and  Messrs.  Baker 
produced  two  very  fine  photomicrographic  cameras  that  might  well 
to-day  rank  as  standard  models  for  critical  high-power  work.  That 
made  by  Messrs.  Swift  incorporated  designs  suggested  by  Mr.  Andrew 
Pringle,  and  that  by  Messrs.  Baker  the  ideas  of  the  late  Mr.  C.  Lees 
Curties — both  experienced  microscopists  and  photomicrographers.  The 
essential  features  of  each  outfit  are  very  similar,  and  consist  of  (1)  a 
long  solid  baseboard  forming  a  rigid  foundation  on  which  the  whole 
apparatus  is  built;  (2)  a  substantial  square-bellows  camera  travelling 
on  a  wide  base  and  capable  of  considerable  extension;  and  (3)  a 
substantial  turntable  for  the  support  of  the  microscope  condensers 
and  illuminant.  On  account  of  the  wide,  solid  base  on  which  the 
square-bellows  camera  travelled,  the  camera  could  be  extended  to  its 
fullest  degree  and  used  in  that  position  without  fear  of  vibration 
during  long  exposures.  With  such  apparatus  the  formidable  task 
of  obtaining  sharp  negatives  at  a  magnification  of  upward  of  two 
thousand  diameters  linear,  could  be  accomplished  with  certainty, 
and,  given  the  necessary  technical  knowledge,  celerity  and  ease.  It 
is  no  light  task  to  be  called  upon  to  produce  large  numbers  of  photo- 
micrographic negatives  at  such  high  magnifications,  when  the  work 
has  to  be  carried  out  in  a  house  past  which  heavy  street  traffic  is 
continually  travelling,  yet  such  formed  a  part  of  my  duties  during 
the  terrible  years  of  the  war,  and  was  made  possible  only  by  the 
use  of  apparatus  of  the  design  I  have  just  described.  Before  the 
work  was  placed  in  my  hands,  attempts  had  been  made  to  carry  it 
out  with  photomicrographic  apparatus  mounted  on  iron  rods,  the 
typical  German  design;  and  therefore,  of  course,  supposed  to  be 
vastly  superior  to  anything  British.  The  failure  was  due  to  no  want 
of  skill  on  the  part  of  the  users  of  the  apparatus,  but  to  its  inherent 
faulty  design,  for  it  is  obvious  that  vibration  will  be  more  readily 
conducted  and  its  amplitude  increased  along  the  rods  than  through  a 
solid  base.  Both  from  long  pre-war  experience  and  from  the  result 
obtained  in  that  part  of  my  war  work  just  described,  I  feel  that  I 
am  fully  justified  in  stating  that  the  right  design  for  photomicro- 
graphic apparatus  intended  for  critical  high-power  work  is  on  the 
lines  of  the  Pringle-Lees  Curties  models,  or  the  more  recent  designs 
of  Singer  made  by  Messrs.  Watson,  and  Sons,  and  of  Barnard,  made 
by  Messrs.   Baker. 

It  frequently  is  necessary  to  take  photomicrographs  with  the 
microscope  in  the  vertical  position,  and  here  again  to  employ  a  camera 
clamped  to  an  upright  iron  rod  is  asking  for  trouble,  to  say  the  least, 
yet  that  is  the  design  dear  to  the  heart  of  the  German  manufacturer. 
Many  years  ago  now,  Messrs.  Watson  and  Sons  placed  on  the  market 
a  vertical  model  made  to  the  design  of  the  veteran  microscopist,  the 


50  PHOTOMICROGRAPHIC    APPARATUS 

late  Dr.  Van  Heurck.  The  apparatus  consists  of  a  vertical  box-form 
camera  supported  on  four  stout  square  legs,  between  which,  and 
immediately  beneath  the  camera,  the  microscope  is  placed.  The 
whole  is  very,  rigid,  and  we  all  know  the  magnificent  work  Dr.  Van 
Heurck  and  others  produced  with  it.  The  chief  objection,  and,  when 
considered  on  optical  grounds,  to  my  mind  not  a  very  real  one,  is 
that  it  precludes  the  employment  of  extended  camera  lengths.  But 
ten  inches  from  the  eye  lens  of  the  eye-piece  to  the  focussing  screen 
of  the  camera  is,  I  believe,  the  ideal  extension  for  critical  work  with 
modern  objectives.  In  the  Journal  of  the  Royal  Microscopical  Socictij 
for  1916,  pages  258-9,  I  have  figured  and  described  a  simple  home- 
made vertical  stand  to  carry  microscope  and  camera,  and  although 
there  shown  as  used  for  stereo-photomicrography,  I  have  since  used 
it  successfully  for  high-power  work  with  the  monocular  microscope 
with  magnifications  up  to  two  thousand  diameters. 

A  vertical  apparatus  of  good,  rigid  design  is  of  such  importance 
for  a  great  deal  of  microscopical  research  work  that  is  being  carried 
out  to-day,  that  it  is  a  matter  deserving  the  immediate  and  serious 
consideration  of  our  British  manufacturers. 


Dr.  Charles  Singer  presented  the  following  paper  on 
''  The  Earliest  Steps  in  the  Invention  of  the  Microscope." 
The  paper  was  taken  as  read. 


THE  EARLIEST  STEPS  IN  THE  INVENTION  OF  THE 
MICROSCOPE. 

By  Charles  Singer,  M.A.,  M.D.Oxford,  F.R.C.P.Lond.,  F.S.A. 


The  microscopes  and  the  microscopic  work  of  the  classical 
observers,  Leeuwenhoek,  Malpighi,  Hooke,  and  Kircher,  have  been 
frequently  described  and  figured.  These  descriptions  are  readily- 
accessible,  and  I  shall  therefore  confine  myself  to  the  earliest  stages 
in  the  discovery  of  the  microscope,  which  is,  of  course,  intimately 
connected  with  the  invention  of  the  telescope.  About  these  early 
stages  vague  statements  are  often  made,  but  the  actual  data  do 
not  seem  to  have  been  put  together. 

(1)  Eiirlid  (third  century,  B.C.),  in  his  Optics,  considered  that 
light  passed  in  straight  lines,  and  regarded  an  object  seen  as  formed 
by  a  cone  with  its  base  at  the  object  and  the  apex  at  the  eye.  The 
Euclidian  origin  of  this  work  is  disputed  by  some,  who  hold  that 
is  is  by  Theon  of  Alexandria,  who  lived  in  the  fourth  century,  A.D., 
and  was  perhaps  the  father  of  Hypatia.  The  most  recent  edition  is 
by  G.  Ovio,  UOttica  di  Euclide,  Milan,  1918. 

(2)  Ptolemy  (died  about  155  A.D.),  in  his  Optics,  began  the 
study  of  refraction,  and  applied  the  experimental  method  to  this 
subject.  He  showed  that  luminous  rays,  in  passing  from  one 
medium  to  another  are  deflected,  and  he  attempted  to  measure  the 
deflection.  This  work  of  Ptolemy  was  written  in  Greek,  and  has 
been  lost.  It  was  translated  from  Greek  into  Arabic,  and,  in  the 
twelfth  century,  from  Arabic  into  Latin.  Only  the  Latin  version 
survives,  and  its  attribution  to  Ptolemy  is  doubtful.  The  best 
edition  is  by  G.  Govi,  Turin. 

(3)  Alhazen  (Abu  Ali  Al-Hazan  Ibn  Alhasan,  965-1038),  was 
an  Arab  of  Basra,  who  abstracted  the  work  of  the  older  Greek 
optical  writers.  He  devoted  much  space  and  skill  to  the  develop- 
ment of  the  effects  of  curved  mirrors.  He  had  a  fairly  clear  notion 
of  the  nature  of  refraction,  and  improved  the  apparatus  of  Ptolemy 
for  measuring  the  angle  of  refraction  in  different  media.      He  had 


52         THE   EARLIEST   STEPS   IN  THE   INVENTION   OF 

ideas  on  the  structure  of  the  eye  that  wero  an  improvement  on 
those  of  his  predecessors,  but  he  had  little  knowledge  of  lenses,  except 
in  connection  with  that  organ.  He  does,  however,  refer  to  the 
magnifying  power  of  segments  of  a  glass  sphere.  He  considered  that 
vision  resulted  from  rays  coming  to  the  eye  from  the  object,  and 
opposed  the  view,  which  held  the  tield  till  the  seventeenth  qentury  and 
later,  that  explained  vision  as  a  result  of  something  emanating  from 
the  eye.  There  are  editions  of  Alhazen's  work  printed  in  the  six- 
teenth century.  These  represent  a  translation  into  Latin  by  an 
unknown  writer  of  the  late  twelfth  or  early  thirteenth  century 
(sec   4). 

(4)  Witchj  (first  half  of  the  thirteenth  century)  was  a  Pole,  who 
studied  in  great  detail  the  work  of  Alhazen.  His  own  work 
grew  out  of  this,  and  is  perhaps  an  improvement  on  it.  Thus 
he  drew  up  a  table  of  refractions  for  the  three  media — air,  water, 
and  glass — from  which  it  could  be  seen  that  the  angle  of  refraction 
did  not  vary  according  to  the  angle  of  incidence.  It  is  doubtful, 
however,  to  what  extent  these  tables  were  original  or  the  results  of 
direct  observation.  The  works  of  Alhazen  and  of  Witelo  were  printed 
together  by  F.  Risner  at  Bale,  1572.  An  interesting  account  of 
Witelo,  together  with  a  reprint  of  his  Perspectiva  from  the  MSS. 
has  been  recently  s,e.t  forth  by  Clemens  Bauemker  in  his  Beitnuje 
zur  Geschichte  der  Philosopliie  des  Mittelalters,   Munich,    1908. 

(5)  Roger  Bacon  (1214-1294)  accomplished  real  advances  in  the 
knowledge  of  optics.  His  work  was  based  primarily  on  Latin  trans- 
lations of  Arabian  writers,  and  especially  on  Witelo's  version  of 
Alhazen.  He  is  distinguished  from  his  predecessors,  however,  by 
his  clear  conception  of  the  value  of  experiment,  and  by  the  evidence 
in  his  works  that,  having  made  a  serious  and  continuous  effort  to 
discover  the  laws  of  the  refraction  and  reflection,  he  sought  to  apply 
his  knowledge  to  the  improvement  of  the  power  of  vision.  In  this 
he  is  a  real  pioneer,  and  is  in  the  truest  sense  the  father  of  micro- 
scopy. 

But  it  is  easy  to  exaggerate  the  claims  of  Bacon,  and  the  wildest 
statements  are  often  made  about  his  discoveries.  It  is  a  fact  that 
there  is  no  evidence  that  he  ever  made  a  telescope  nor  any  micro- 
scope, save  a  simple  one.  But  he  had  a  clear,  though  not  wholly 
accurate  idea  of  the  nature  and  properties  of  lenses,  and,  groping 
with  the  instinct  of  genius,  he  did  vaguely  foresee  both  telescope 
and  microscope.  The  following  passages  will  serve  to  indicate  the 
stage  he  had  reached  in  optical  knowledge.  I  have  purposely 
selected  passages  containing  some  errors.  It  will  be  observed  that 
in  the  first  of  these  passages  Bacon  refers  to  and  figures  the  object 
as  though  it  were  itself  in  the  denser  medium  of  which  the  lens  is 
composed.  In  doing  this  he  is  confusing  the  optical  action  of  a 
lens  with  that  of  a  liquid  in  which  an  object  is  immersed.  The 
optical  results  of  immersion  in  a  liquid  had  been  investigated  by 
his  predecessors,  and  were  perhaps  familiar  to  Aristotle. 

If  anyone  examines  letters  and  other  minute  objects  through 
the  medium  of  crystal  or  glass  or  other  transparent  substance,  if 
it  be  shaped  like  the  lesser  segment  of  a  sphere,  with  the  convex 
side  towards  the  eye,   and  the  eye  being  in  the  air,  he  will  see  the 


THE    MICROSCOPE:    CHARLES   SINGER  53 

letters  far  better,  and  they  will  seem  larger  to  him.  For,  according 
to  Canon  5  (see  Fig.  1)  concerning  a  spherical  medium  beneath 
which  the  object  is  placed,  the  centre  being  beyond  the  object,  the 
convexity  being  towards  the  eye,  all  causes  agree  to  increase  the 
size,  for  the  angle  in  which  it  is  seen  is  greater,  the  image  is  greater, 
and  the  position  of  the  image  is  nearer,  because  the  object  is 
between  the  eye  and  the  centre.  For  this  reason  such  an  instrument 
is  useful  to  old  persons  and  to  those  with  weak  eyes.  For  they  can 
see  any  letter,  however  small,  if  magnified  enough.  But  if  a  larger 
segment   of    a   sphere   be   employed,    then,    according     to     Canon     6 


Eur  IV  R&rer  t^edtum. 


Fig.  1 


(Fig.  2),  the  size  of  the  angle  is  increased,  and  also  the  size  of  the 
image,  but  propinquity  is  lost  because  the  position  of  the  image  is 
beyond  the  object,  the  reason  being  that  the  centre  of  the  sphere 
is  between  the  eye  and  the  object  seen.  Therefore  such  an  instru- 
ment is  not  of  so  much  use  as  the  smaller  portion  of  a  sphere." 

"  Objects  are  greater  when  the  vision  is  refracted;  for  it  easily 
appears  by  the  above-mentioned  canons  that  very  large  objects  may 
seem  to  be  very  small  and  conversely,  and  those  at  a  great  distance 
away  may  seem  very  near  and  conversely.  For  we  can  so  form 
glasses  and  so  arrange  them  with  regard  to  our  sight  and  to  objects 
tha^  the  rays  are  refracted  and  deflected  to  any  place  we  wish,  so 
that  we  see  the  object  near  at  hand  or  far  away  beneath  whatever 
angle  we  desire.  And  so  w^e  can  read  the  smallest  letters  or  count 
grains  of  sand  or  dust  from  an  incredible  distance,  owing  to  the 
magnitude  of  the  angle  beneath  which  we  see  them,  while  we  can 
scarcely  see  the  largest  objects  close  at  hand,  owing  to  the  smallness 
of  the  angle  beneath  which  we  view  them  ;  for  distance  does  not  affect 
this  kind    of   vision   save   7?er    accidens,    but    the   size    of    the    angle- 


54         THE   EARLIEST  STEPS   IN  THE   INVENTION   OF 

(does  so  affect  it).  So  a  boy  can  appear  a  giant,  a  man  seem  a 
mountain,  and  in  any  size  of  angle  whatever,  just  as  we  can  see 
a  man  under  so  large  an  angle  like  a  mountain  and  as  near  as  we 
desire.  So  a  small  army  might  seem  very  large,  and  though  far 
away  appear  near,  and  conversely :  so  too  we  could  make  sun, 
moon,  and  stars  apparently  descend  herei  below,  and  similarly  appear 
above  the  heads  of  our  enemies,  and  many  other  similar  marvels 
could  be  brought  to  pass,  so  that  the  ignorant  mortal  mind  could 
not  endure  the  truth."     (Opus  Ma  jus,  Part  V). 

''And  what  is  causally  manifest  with  regard  to  double  refraction 
we  can  verify  in  many  ways  by  the  results  of  experiment.  For  if 
anyone  holds  a  crystal  ball  or  a  round  urinal  flask  filled  with  waler 
in  the  strong  rays  of  the  sun,  standing  by  a  window  in  face  of  the 


Fig  2. 


rays,  he  will  find  a  point  in  the  air  between  himself  and  the  flask 
at  which  point,  if  any  easily  combustible  substance  is  placed,  it 
will  catch  fire  and  burn,  which  would  be  impossible  unless  we  sup- 
pose a  double  refraction.  For  a  ray  of  the  sun  coming  from  a 
point  in  the  sun  through  the  centre  •  of  the  flask  is  not  refracted, 
because  it  falls  perpendicularly  on  flask,  water,  and  air,  passing 
through  the  centre  of  each  (Fig.  3).  .  .  .  But  all  the  (other) 
rays  which  are  given  forth  at  the  same  point  in  the  sun  from 
which  this  perpendicular  ray  comes  are  necessarily  refracted  on 
the  body  of  the  flask,  because  they  fall  at  oblique  angles,  and  since 
the  flask  is  denser  than  air,  the  refraction  passes  between  the  straight 
path  and  the  perpendicular  drawn  from  the  point  of  refraction 
to  the  centre  of  the  flask.  And  when  it  passes  out  again  into  the 
air,  then,  since  it  comes  upon  a  less  dense  body,  the  straight  path 
passes  between  the  refraction  and  the  perpendicular  drawn  from 
the  point  of  refraction,  so  that  the  refracted  ray  may  fall  upon 
the  first  perpendicular  which  comes  without  refraction  from  the  sun. 
And   suice  an  infinite  number   of  ^^ays  are   given   off   from   the  same 


THE    MICROSCOPE:    CHARLES   SINGER 


55 


point  of  the  sun,  and  one  only  falls  perpendicularly  on  the  flask, 
all  the  others  are  refracted  and  meet  at  one  point  on  the  perpen- 
dicular ray  which  is  given  off  along  with  them  from  the  sun,  and 
this  point  is  the  point  of  combustion,  because  on  it  are  collected 
an  infinite  number  of  rays,  and  the  concentration  of  light  causes 
combustion.  But  this  concentration  would  not  take  place  except 
by  double  refraction,  as  shown  in  the  diagram."  (Opus  Mains y 
Part  VII). 

Glasses  (per  spicy  a)  can  be  so  constructed  that  objects  at  a 
very  great  distance  appear  to  be  quite  close  at  hand,  and  conversely. 
Thus  we  read  the  smallest  letters  from  an  incredible  distance,  number 
objects,  however  small,  and  make  the  stars  appear  as  near  as  we 
wish.      .     .      ,      Also   objects   can   be  made   to   appear  so   that   the 


FIG   3. 


greatest  seems  the  least,   and  conversely;  what  are  high  appear  low 
and  short,  and  conversely ;  and  what  is  hidden  appears  manifest.     .     . 

But  among  the  more  subtle  powers  of  construction  is  this  of 
directing  and  concentrating  rays  by  ^means  of  (instruments  of) 
different  forms  and  reflections  at  any  distance  we  wish,  where  what- 
ever is  subjected  to  them  is  burned.  .  .  .  But  greater  than 
any  such  design  or  purpose  is  that  the  heavens  might  be  portrayed 
in  all  their  length  and  breadth  on  a  corporeal  figure  moving  with 
their  diurnal  motion,  and  this  would  be  worth  a  whole  kingdom  to 
a  wise  man.  Let  this,  then,  be  sufficient  as  an  example,  although 
an  infinite  number  of  other  marvels  could  be  set  forth."  (De 
Secretis  Operihus  Artis  et  Naturae.) 

It  is  a  remarkable  thing  that  no  complete  edition  of  the  works 
of  Roger  Bacon  has  ever  been  prepared,  nor  any  important  work 
by  him  translated  into  English.  The  above  passages  I  have  trans- 
lated from  J.  H.  Bridges,  The  Opus  Majus  of  Rogerh  Bacon,  Oxford, 
1897,  and  J.  S.  Brewer,  Fratris  Roger  Bacon  opera  quaedam  hactenust 
inedita,  London,  1859. 


56  THE   EARLIEST   STEPS   IN  THE   INVENTION   OF 

(5)  John  Peckham  (died  1292),  Archbishop  of  Canterbury,  was 
the  author  of  a  work  on  optics  entitled  Persyectiva  communis.  His 
views  were  very  similar  to,  and,  perhaps,  taken  from.  Bacon.  He 
is  important  only  as  having  drawn  wide  attention  to  optical  prin- 
ciples. His  work  exists  in  a  number  of  manuscripts,  and  has  often 
been  printed.     The  first  edition  is  dated  from  Milan,  1482. 

(6)  The  names  of  Salvino  d'Amarto  degli  Amarti  of  Florence 
and  Alessandro  de  Spina  of  Pisa  (both  circa  1300)  have  become 
associated  with  the  special  application  of  lenses  for  use  as  spectacles. 
Lenses,  as  we  have  seen,  were  known  to  Roger  Bacon,  who  suggested 
also  their  use  in  aiding  vision.  D'Amarto  and  Spina  applied  the 
principle  thus  suggested.  From  about  1300  onward  convex  lenses 
for  use  as  spectacles  were  well  known, 

.  The  question  of  the  invention  of  spectacles  has  been  frequently 
discussed.  One  of  the  latest  writers  who  has  traversed  this  field 
is  V.  Rocchi,  Appunti  di  storia  critica  del  microscopio,  in  the 
Eevisfs  di  Storia  critica  delle  Scietize  Mediche  e  Xatiirali,  January, 
1913. 

(7)  Leonardo  da  Vinci  (1452-1519)  had  sounder  ideas  than  any 
of  his  predecessors  on  the  structure  of  the  eye,  on  binocular  vision, 
on  refraction  and  diffraction.  He  developed  a  practical  camiera 
ohsciua,  and  gives  a  hint  of  a  ''  glass  to  see  the  moon  enlarged." 
His  work,  though  original  and  valuable,  remained  inaccessible  for 
nearly  four  centuries,  and  had  no  influence  on  his  contemporaries. 

Leonardo  left  his  scientific  remains  in  a  state  of  confusion,  and 
they  have  suffered  much  by  time  and  misuse.  It  is  impossible  to 
give  a  bibliography  here,  but  his  optical  results  are  summarised  by 
E.  Solmi,  Leonardo  da  Vinci  e  il  tnetodo  sperimentale  nelle  ricerche 
fisiche,  in  the  Atti  e  niemorie  della  R.  Accademia  Virgiliaiio  di 
Mantova,  Mantua,  1905,  and  by  O.  Werner,  Zur  Physik  Leonardo 
da  Vincis,  Berlin,  1911. 


(8)  Girolamo  Fracastoro  (1478?-1553)  was  a  suggestive  writer 
who  devoted  considerable  space  to  a  rather  confused  account  of 
refraction.  In  the  course  of  this  discussion  he  has  the  following 
passage: — "  (Not  only  the  character  but)  also  the  position  of  the 
medium  affects  the  appearance  of  the  objects  seen,  as  may  be  observed 
with  spectacle  lenses  {in  specillis  ocularihus).  For  if  the  lens  be 
placed  midway  between  eye  and  object,  it  appears  much  larger 
than  if  the  lens  is  made  to  approach  the  object  or  the  eye.  {//omo- 
centrlca  II,  8).  .  .  .  Glasses  {xpecUla  ocularia)  may  be  arranged 
of  such  density  that  if  anyone  looks  through  them  at  the  moon  or 
at  any  star  they  appear  near  and  hardly  higher  than  the  steeples. 
{Ilomocentrica,  III,  23)."  It  is  possible  that  he  was  here  con- 
templating a  bilenticular  apparatus.  The  TI oworentrica  in  which 
these  passages  occur  was  first  printed  at  Venice  in  1538.  The 
scientific  value  of  this  work  is  discussed  by  the  present  writer  in  an 
article  in  the  Arnuds  of  Mfdicfd  Ilixtori/,  Vol.  I,  p.  1,  New  York, 
1917. 


THE    MICROSCOPE:    CHAKLES   SINGER  57 

(8)  Francesco  Mauroiico  (1494-1575)  was  perhaps  the  first  after 
Roger  Bacon  to  attempt  a  mathematical  analysis  of  the  optics  of 
the  lens.  He  is  thus  the  predecessor  of  Kepler.  His  work,  rhotismi 
de  lumine  et  umbra,  was  printed  at  Venice  in  1575. 

(9)  Leonard  Dujyes  (died  1571  ?)  was  the  first  to  whom  can  be 
definitely  attributed  the  construction  of  a  bilenticular  system.  The 
evidence  for  this  statement  rests  on  the  following  passage  in  a  work 
by  his  son,  Thomas  JJigges  (died  1595):  — 

"  Marueylouse  are  the  conclusions  that  may  be  perfourmed  by 
glasses  concaue  and  conuex  of  circulare  and  parabolicall  fourmes, 
using  for  multijolication  of  beames  sometime  the  ayde  of  glasses 
transparent,  which  by  fraction  should  unite  or  dissipate  the  images 
or  figures  presented  by  the  reflection  of  other.  By  these  kinds  of 
glasses  or  rather  frames  of  them,  placed  in  due  angles,  ye  may  not 
only  set  out  the  proportion  of  an  whole  region,  you  represent  before 
your  eye  the  lively  image  of  euery  towne,  village,  etc.,  and  that 
in  as  little  or  great  space  or  place  as  ye  will  prescribe,  but  also 
augment  and  dilate  any  parcell  thereof,  so  that  whereas  at  the 
firste  apparance  an  whole  towne  shall  present  it  selfe  so  small  and 
compacte  together  that  ye  shall  not  discerne  any  dijBference  of  streates, 
ye  may  by  applycation  of  glasses  in  due  proportion  cause  any 
peculiare  house  or  roume  thereof  dilate,  and  shew  it  selfe  in  as 
ample  fourme  as  the  whole  towne  first  appeared,  so  that  ye  shall 
discerne  any  trifle  or  reade  any  letter  lying  there  open,  especially 
if  the  Sonne  beames  may  come  unto  it,  as  playnly  as  if  you  wer 
corporally  present,  although  it  be  distante  from  you  as  farre  as  eye 
can  discrye.  But  of  these  conclusions  I  minde  not  here  more  to 
intreate,  hauing  at  large  in  a  volume  by  it  selfe  opened  the  miracu- 
lous effectes  of  perspective  glasses."  Digges's  system  appears  to 
have  been  combined  in  some  manner  with  a  camera  ohscura.  Un- 
fortunately, his  further  description  of  it  was  never  published.  The 
work  of  Thomas  Digges  in  which  this  passage  occurs  is  entitled  A 
Geometrical  Practise  named  Pantometria,  and  was  printed  in  London 
in   1571. 

(10)  Gianhattista  della  Porta  (1540-1615)  is  the  first  to  whom 
can  be  attributed  the  actual  combination  of  lenses  in  the  form  of 
a  microscope.  This  statement  rests  on  the  evidence  of  the  following 
passages  in  his  Magia  naturalis: — "  Concave  lenses  enable  one  to  see 
far  off  more  clearly,  while  convex  ones  make  near  objects  more 
discernible."  He  was  apparently  myopic,  for  he  goes  on  to  say 
that  ''  with  a  concave  lens  you  see  things  afar  smaller  but  plainer, 
with  a  convex  lens  you  see  them  larger  but  less  distinct.  If,  how- 
ever, you  know  how  to  combine  the  two  sorts  properly,  you  will 
see  near  and  far  both  large  and  clear."  In  later  years,  when  the 
microscope  became  a  recognised  instrument,  much  larger  claims 
were  made  by  and  for  Porta,  but  there  is  no  real  evidence  that 
he  made  any  effective  practical  application  of  his  idea.  The  Magia 
naturalis  was  first  printed  at  Naples  in  1558,  but  the  passages  in 
question  do  not  occur  in  it,  nor  in  any  edition  of  the  w^ork  that 
appeared  before  that  of  1588. 

{\l\  Zach arias,  son  of  Jan,  and  known  as  Jansen  (1580-16?), 
of  Middelburg,  is  usually  regarded  as  the  first  who  actually  con- 
structed    a   microscope.       His   first    attempt   was   the   result    of     an 


58  THE   EARLIEST  STEPS   IN  THE   INVENTION   OF 

accident.  It  appears  that  while  still  a  lad  and  at  work  in  the 
shop  of  his  father,  who  was  a  spectacle  maker,  he  happened  to 
place  two  lenses  in  a  tube  and  found  that  they  acted  as  a  microscope 
or  telescope.  Effective  instruments  were  constructed  by  him  in  the 
first  decade  of  the  seventeenth  century.  The  evidence  that  Jansen 
was  really  the  first  consti'uctor  of  these  bilenticular  instruments  rests 
on  the  testimony  of  Willem  Boreel  (1591-1668),  the  Dutch  Ambas- 
sador to  France,  Boreel's  evidence  is  given  in  a  letter  by  him  to 
Pierre  Borel  (1620-1671),  which  runs  as  follows:  — 

"  1  am  a  native  of  Middelburg,  the  capital  of  Zeeland,  and 
close  to  the  house  where  I  was  born  .  ,  ,  there  lived  in  the 
year  1591  a  certain  spectacle  maker,  Hans  by  name.  His  wife, 
Maria,  had  a  son  Zacharias,  whom  I  knew  very  well,  because  as  a 
neighbour  and  from  a  tender  age  I  constantly  went  in  and  out 
playing  with  him.  This  Hans,  or  Johannes,  with  his  son  Zacharias, 
as  I  have  often  heard,  were  the  first  to  invent  microscopes,  which 
they  presented  to  Prince  Maurice,  the  governor  and  supreme 
commander  of  the  united  Dutch  forces,  and  were  rewarded  with 
some  honorarium.  Similarly,  they  afterwards  offered  a  microscope 
to  the  Austrian  Archduke  Albert,  supreme  governor  of  Holland. 
When  I  was  Ambassador  to  England  in  the  year  1619,  -the  Dutch- 
man Cornelius  Drebbel  of  Alkomar,  a  man  familiar  with  many 
secrets  of  nature,  who  was  serving  there  as  mathematician  to  King 
James,  and  was  well  known  to  me,  showed  me  that  very  instrument 
which  the  Archduke  had  presented  as  a  gift  to  Drebbel,  namely^ 
the  microscope  of  Zacharias  himself.  Nor  was  it  (as  they  are  now 
seen)  with  a  short  tube,  but  nearly  two  and  a-half  feet  long,  and 
the  tube  was  of  gilded  brass,  two  fingers  breadth  in  diameter,  and 
supported  on  three  dolphins  formed  also  of  brass.  At  its  base  was 
an  ebony  disc,  containing  shreds  or  some  minute  objects  which  we 
inspected  from  above,  and  their  forms  were  so  magnified  as  to  seem 
almost  miraculous."  This  passage  is  contained  in  a  work  by  Pierre 
Borel,  De  vero  telescopii  inventoi'e  ciim  brevi  omnhim  conspiciliorum 
historia,  The  Hague,   1655. 

(12)  Jan  Lij)j)ershey  of  Wessel  (flourished  1608)  is  another 
candidate  for  the  same  honours  as  Zacharias.  In  October,  1608,. 
a  man  named  Lippershey  applied  at  the  Hague  for  a  monopoly 
in  the  making  of  a  bilenticular  apparatus  for  examining  objects  at 
a  distance.  Even  at  that  date,  however,  it  appears  from  the  evidence 
that  such  instruments  were  already  known.  The  story  of  Lippershey's 
discovery  is  suspiciously  like  that  told  of  Zacharias.  The  application 
and  findings  of  the  committee  that  sat  on  it  were  still  in  existence 
in  the  early  part  of  the  nineteenth  century,  and  were  published  by 
J.  H.  van  Swinden.  See  S.  Moll,  Journal  of  the  Royal  Institution,. 
Vol.  1,  1831. 

(13)  Jacoh  Andrianzoon,  otherwise  James  Metius  of  Alkmaar, 
was  a  younger  brother  of  a  distinguished  geometrician.  Of  him 
Descartes,  in  his  Diopfrique,  published  in  1637,  writes  as  follows:  — 
"  It  is  about  30  years  since  one  named  Jacques  Metius,  an  unlearned 
man,  but  one  who  loved  to  make  mirrors  and  burning  glasses,  having 
by  him  glasses  of  various  shape,  thought  of  looking  through  two 
of  them,  of  which  one  was  convex,   and  the  other  concave,   and  he 


THE    MICROSCOPE:    CHARLES   SINGER  59 

luckily  put  them  in  the  ends  of  a  tube,  and  thus  the  first  tele- 
scopes were  made."  Metius  also  applied  for  a  patent,  and  £u  copy 
of  his  application  has  survived  among  the  MSS.  of  Christion  Huygens 
(1629-1695). 

(14)  Galileo  (1564-1642)  was  the  effective  discoverer  of  the  micro- 
scope, a  discovery  which,  as  in  the  other  cases,  was  bound  up  with 
that  of  the  telescope.  The  event  may  be  referred  to  the  early  part 
of  1609,  and  the  story  may  be  told  in  a  translation  of  his  own 
words :  — 

"  About  ten  months  ago,"  he  says,  "  a  rumour  reached  me  of 
an  ocular  instrument  made  by  a  certain  Dutchman  by  means  of 
which  an  object  could  be  made  to  appear  distinct  and  near  to  an 
eye  that  looked  through  it,  although  it  was  really  far  away.  .  .  . 
And  so  I  considered  the  desirability  of  investigating  the  method, 
and  I  reflected  on  the  means  by  which  I  might  come  to  the  inven- 
tion of  a  similar  instrument.  A  little  later,  making  use  of  the 
doctrine  of  refractions,  I  first  prepared  a  leaden  tube,  at  the  ends 
of  which  were  placed  two  lenses,  each  of  them  flat  on  one  side,  and 
as  to  the  other  side  I  fashioned  one  concave  and  the  other  convex. 
Then,  moving  the  eye  to  the  concave  one,  I  saw  the  objects  fairly 
large  and  nearer,  for  they  appeared  three  times  nearer  and  nine 
times  larger  than  when  they  were  observed  by  the  naked  eye.  Soon 
after  I  made  another  more  exactly,  representing  objects  more  than 
sixty  times  larger.  At  length,  sparing  no  labour  and  no  expense, 
I  got  to  the  point  that  I  could  construct  an  excellent  instrumeno 
so  that  things  seen  through  it  appeared  almost  a  thousand  times 
greater  and  more  than  thirty-fold  nearer  than  if  observed  by  the 
naked  eye."     (Siderius  Xuncius,  Venice,  1610). 

In  another  work  he  says :  ' '  Some  would  tell  me  that  it  is  of 
no  little  help  in  the  discovery  and  resolution  of  a  problem  to  be 
first  of  all  in  some  way  aware  of  the  true  conclusion  and  certain  of 
not  being  in  search  of  the  impossible,  and  that  therefore  the  know- 
ledge and  the  certainty  that  the  microscope  had  indeed  been  invented 
had  been  of  such  help  to  me  that  perchance  without  that  I  should 
not  have  discovered  it.  To  this  I  reply  that  the  help  rendered  me 
by  the  knowledge  did  indeed  stimulate  me  to  apply  myself  to  the 
notion,  and  it  may  be  that  without  this  I  should  never  have  thought 
of  it.  Beyond  this  I  do  not  believe  that  knowledge  to  have  facili- 
tated the  invention.  But,  after  all,  the  solution  of  a  problem, 
thought  out  and  defined,  is  a  work  of  some  skill,  and  we  are  not 
certain  that  the  Dutchman,  the  first  inventor  of  the  telescope,  was 
not  a  simple  maker  of  ordinary  lenses,  who,  casually  arranging 
glasses  of  various  sorts,  happened  to  look  through  the  combination 
of  a  convex  and  a  concave  one  placed  at  various  distances  from  the 
eye  and  in  this  way  observed  the  effect  that  followed  thereon.  But 
I,  moved  by  the  knowledge  given,  discovered  it  by  a  process  of 
reasoning."     (II  snggiatore,  Rome,   1623.) 

(15)  Galileo's  account  of  the  path  of  light  in  the  bilenticular  sys- 
tem is  unsatisfactoiy,  but  was  improved  by  Kepler  in  his  Dioptrice 
(Cologne,  1611),  who  at  the  same  time  suggested  that  form  of 
microscope  consisting  of  two  convex  lenses  which  has  developed  as 
our  modern  instrument. 


Professor  A.  E.  Conrady  contributed  some  *'  Notes  on 
Microscopical  Optics,  "  which  were  communicated  by 
Professor  Alfred  W.  Porter,  F.K.S. 


NOTES  ON  MICROSCOPICAL  OPTICS. 
By  a.  E.  Conrady. 


It  is  manifestly  impossible  to  give  an  exhaustive  treatise  on 
microscopical  optics  in  a  short  paper,  but  a  brief  indication  of  wnat 
has  been  done  and  what  is  likely  to  be  accomplished  in  the  near 
future  may  be  acceptable. 

The  resolving  and  defining  power  of  the  microscope  depends 
primarily  on  the  high  correction  of  spherical  aberration  in  cones  of 
rays  of  very  large  angular  aperture.  The  first  approximation  methods 
which  are  useful  in  arriving  at  preliminary  designs  of  telescope 
objectives  will  only  give  rough  indications  of  the  required  forms  of 
components  even  in  the  lower  powers  of  microscope  objectives,  and 
they  are  quite  useless  in  the  case  of  the  higher  powers. 

Exact  trigonometrical  ray-tracing  must  therefore  form  the  founda- 
tion of  the  designer's  work.  It  is  not,  however,  desirable  to  depend 
entirely  upon  this  method,  for  the  real  desideratum  in  every  lens 
system  is  that  all  the  light  from  an  object-point  should  reach  the 
image  point  along  paths  of  the  same  optical  length,  and  according 
to  the  classical  ITmit  recommended  by  the  late  Lord  Rayleigh,  this 
equality  of  optical  paths  should  not  be  departed  from  to  a  greater 
extent  than  J  wave-length,  say  five  one-millionth  of  an  inch.  It 
used  to  be  thought  by  practical  opticians  that  this  represented  a 
perfectly  absurd  and  unattainable  degree  of  perfection,  but  I  showed 
long  ago  (Monthly  Notices  R.A.S.,  April,  1905),  that  so  far  is  this 
from  being  true  that  the  Rayleigh  limit  really  represents  a  far 
more  generous  allowance,  in  the  ratio  of  about  4  to  1,  than  the 
union  of  the  geometrical  rays  within  a  "  circle  of  confusion  "  equal 
to  the  resolving  power  of  an  objective,  which  latter  condition  was 
looked  upon  as  practicable.  Quite  recently  the  fulfilment  of  the 
Rayleigh  condition  in  good  telesco]}e  and  microscope  cbjectives  has 
been  put  to  the  direct  experimental  proof  by  that  valuable  innova- 
tion :  the  Hilger  Lens-Interferometer.  In  the  paper  quoted  above 
I  gave  a  trigonometrically  exact  method  of  detcrminitiy  the  phase- 
relation  in  which  rays  arrive  at  a  focus.  I  had  used  the  method  for 
about  10  years  at  the  time  of  its  publication,  and  all  my  designs 
of  microscope  objectives  are  based  on  its  use :  but  up  to  the  time  when 
I  began  lecturing  at  the  Imperial  College  I  was  probably  the  only 
designer  who  took  advantage  of  this  method,  which  is  not  only  the 
soundest  from  the  theoretical  point  of  view,  but  also  by  far  the 
easiest   and   quickest.      As    it   gives    the    exact    amount    of   spherical 


A.    E.     CONKADY'  61 

aberration  arising  at  each  surface  in  the  absolute  measure  of  wave- 
lengths, it  also  enables  a  designer  to  avoid  the  unnecessary  piling  up 
of  huge  aberrations  such  as  are  met  with  in  the  lens  systems  designed 
by  purely  geometrical  ray-tracing. 

Recently  (Monthly  Notices,  June,  1919),  I  have  rounded  off  this 
earlier  work  by  determining  the  complete  light-distribution  in  the 
"  spurious  disc  "  which  results  when  residuals  of  aberration  are 
present,  so  that  the  designer  using  the  optical  path  method  can  now 
state  definitely  to  what  extent  the  image  points  obtained  with  a 
given  system  fall  short  of  the  full  brightness  and  sharpness  which 
would  result  in  a  theoretically  perfect  instrument. 

The  chromatic  aberration  of  microscopic  objectives  is  also  best  and 
most  conveniently  determined  in  terms  of  differences  of  optical  paths 
(Monthly  Notices,  January  and  March,  1904).  By  applying  the 
simple  formulae  to  both  marginal  and  paraxial  rays,  a  reliable 
measure  of  the  higher  chromatic  aberrations,  the  so-called  spherical 
variation  of  chromatic  correction,  is  obtained,  and  this  can  then, 
by  suitable  alterations  of  lens  curvatures,  etc.,  be  kept  within  those 
narrow  limits  which  distinguish  "  semi-apochromatic  "  objectives 
from  earlier  types  in  which  this  variation  frequently  reached  very 
serious  amounts. 

A  microscope  objective  perfectly  free  from  spherical  and  chromatic 
aberration  may  yet  be  absolutely  useless  for  practical  purposes  on 
account  of  such  amounts  of  coma  in  the  images  of  extra-axial  object 
points  that  sharp  definition  is  limited  to  an  almost  infinitesimally 
small  area  in  the  exact  centre  of  the  field.  One  of  Abbe's  first 
attempts  at  the  designing  of  microscope  objectives  purely  by  calcula- 
tion appears  to  have  resulted  in  a  particularly  bad  specimen  of  this 
type.  The  search  for  the  cause  of  the  defect  led  him  to  the  inde- 
pendent discovery  of  the  famous  "  Sine-Condition,"  also  announced 
almost  simultaneously  by  Helmholtz,  and  previously  discovered — 
without  attracting  the  attention  of  opticians — by  Clausius.  In  an 
approximate  algebraical  form  it  also  figured  as  the  second  of  the 
famous  5  conditions  of  Seidel.  The  realisation  of  its  immense  value, 
however,  dates  undoubtedly  from  the  announcements  by  Abbe  and 
Helmholtz  in  1873.  Since  that  time  it  has  saved  an  incalculable 
amount  of  time  and  trouble  to  the  designers  of  telescope  and  micro- 
scope objectives,  as  it  indicates  the  presence  or  absence  of  coma  in 
the  central  part  of  the  field  by  a  simple  comparison  of  figures  taken 
directly  from  the  trigonometrical  computations.  I  gave  a  simple 
and  fairly  exhaustive  proof  and  discussion  of  this  theorem  in  Monthly 
Notices  for  March,  1905,  and  to  that  paper  those  interested  may 
refer. 

If,  and  only  if,  the  foregoing  defects  (spherical  and  chromatic 
aberration  within  the  Rayleigh  limit  and  coma)  are  properly  cor- 
rected, then  another  defect  of  all  ordinary  lens  systems  will  become 
obvious  and  objectionable,  viz.,  the  secondary  spectrum.  This  is 
duB  to  the  fact  that,  as  compared  with  ordinaiy  crown  glasses,  the 
heavy  flint  glasses  which  have  to  be  used  to  compensate  the  primary 
chromatic  aberration  disperse  the  blue  end  of  the  spectrum  too  much 
and  the  red  end  too  little.  The  result  is  that  flint  lenses  of  the 
proper  power  to  secure  achromatism  for  the  brightest  yellow  and 
green  region  of  the  spectrum  overcorrect  the  dispersion  of  the  crown 


62  NOTES    ON    MICROSCOPICAL    OPTICS: 

in  the  blue  and  violet  end  and  undercorrect  it  in  the  orange  and 
red  end.  As  the  crown  lenses  alone  would  bring  violet  to  a  shortest 
and  red  to  a  longest  focus,  the  effect  is  that  the  achromatic  com- 
bination brings  both  ends  of  the  spectrum  to  a  longer  focus  than 
its  central  part.  Therefore  there  is  a  minimum  distance  of  the  focus 
for  yellow-green,  and  at  that  focus  the  light  from  both  ends  of  the 
spectrum  is  diffused,  and  causes  a  halo  of  a  purple  or  claret  tint. 
This  halo  is  objectionable  even  in  visual  observations,  because  it 
falsifies  the  true  colour  of  the  observed  objects,  but  the  difference 
of  focus  to  which  it  is  due  becomes  a  grave  defect  when  the  object 
is  to  be  photographed,  unless  a  strong  screen  is  used  which  cuts  off 
both  ends  of  the  spectrum,  but  more  particularly  the  dark  blue  and 
violet  light.  Such  a  screen  greatly  increases  the  required  time  of 
exposure,  and  may  be  inadmissible  in  the  case  of  stained  or  naturally 
strongly  coloured  objects,  because  these  may  be  either  opaque  or  too 
transparent  to  yellow-green  light. 

The  attempts  to  produce  varieties  of  glass  free  from  this  secondary 
spectrum  have  been  unsuccessful  as  far  as  the  microscope  is  con- 
cerned, for  the  existing  crowns  and  flints  with  proportional  dispersion 
have  so  little  difference  in  dispersive  power  that  an  impracticable 
number  of  lenses  would  have  to  be  used  to  secure  the  desired  effect. 
We  therefore  still  depend  on  the  material  whose  value  for  this  pur- 
pose was  discovered  by  Abbe,  the  natural  mineral  fluorite,  used 
instead  of  crown  glass  in  combination  with  heavy  crown  glasses  or 
very  light  flint  glasses  in  place  of  ordinary  dense  flint  glass.  It  was 
by  the.  use  of  fluorite  that  Abbe  produced  the  apochromatic  objectives, 
and  fluorite  of  good  optical  quality  must  be  used  to  this  day  to 
secure  the  result.  Apart  from  the  difficulty  of  finding  this  material 
there  is  no  obstacle  to  the  designing  by  exact  calculation  of  apo- 
chromatic objectives. 

I  now  coniie  to  a  defect  of  nearly  all  microscope  objectives,  and 
especially  of  highly  corrected  ones,  which  is  well  known  to  all  prac- 
tical microscopists,  namely  the  pronounced  curvature  of  the  field, 
invariably  in  the  sense  of  requiring  a  shortening  of  the  distance 
from  object  to  lens  in  order  to  obtain  a  sharp  focus  in  the  outer 
parts  of  the  field  of  view.  The  general  theory  of  the  primary  aberra- 
tions of  oblique  pencils  shows  that  any  lens  system  when  freed  from 
astigmatism  will  have  the  curvature  of  field  defined  by  the  Petzval 
theorem,  and  that  in  the  presence  of  astigmatism  the  two  focal  lines 
which  then  represent  the  strongest  concentration  of  the  light  always 
lie  both  on  the  same  side  of  the  Petzval  curve  and  at  distances  from 
it  which  are  in  the  approximate  ratio  of  three  to  one.  When  the 
astigmatism  is  undercorrected  the  natural  curvature  of  the  field 
defined  by  the  Petzval  equation  becomes  aggravated  whilst  over- 
corrected  astigmatism  tends  to  flatten  the  field,  and  is  deliberately 
introduced  for  this  purpose  in  ordinary  photographic  objectives.  The 
presence  of  considerable  amounts  of  astigmatism,  of  course,  renders 
really  sharp  marginal  images  impossible  in  either  case,  so  that  its 
absence  or  better  still  a  modest  amount  of  overcorrected  astigmatism 
must  be  regarded  as  the  ideal  in  microscope  objectives.  Unfortunately 
this  desirable  state  cannot  be  reached  in  the  existing  types  of 
objectives.  The  binary  low  power  objectives  up  to  the  ordinary  one 
inch  and  2/3  inch  come  nearest  to  it,  and  are  therefore  justly  liked 


A.    E.     CONHADY  63 

by  microscopists  for  all  work  for  which  they  are  sufficiently  powerful. 
In  the  ordinary  ternary  objectives  of  the  1/6  inch  type,  with  approx- 
imately plano-convex  components,  the  curvature  of  tlie  field  is  also 
of  reasonably  moderate  amount.  But  it  is  a  general  experience 
that  highly  corrected  objectives  are  very  much  worse  as  regards 
curvature  of  field.  In  the  light  of  my  most  recent  work  on  the 
general  theory  of  lenses  (Monthly  Notices,  November,  1919),  this 
curious  and  objectionable  peculiarity  is  easily  explained,  and  becomes 
revealed  as  a  7iecessary  consequence  of  high  spherical  and  chromatic 
correction  if  the  usual  number  of  components  is  adhered  to.  In 
the  Lister  and  Amici  types  of  ordinary  objectives,  which  are  fairly 
satisfactory  as  regards  curvature  of  the  field,  the  front  lens  is  of 
such  a  form  as  to  produce  strong  outward  coma  and  there  is  in  the 
back  lens  or  lenses  a  corresponding  amount  of  inward  coma.  The 
simple  extensions  of  Seidel's  theory  given  in  the  paper  last  referred 
to  show  that  this  is  the  state  of  affairs  which  tends  to  diminish 
undercorrected  astigmatism  or  even  to  reverse  it  into  the  more 
desirable  over-corrected  form.  High  correction  of  the  zonal  spherical 
aberration,  and  to  a  still  greater  extent  complete  removal  of  the 
spherical  variation  of  chromatic  correction  necessitate  a  more  or 
less  complete  reversal  of  the  coma  effects  in  front  and  back  com- 
ponents. In  other  words,  with  the  usual  types  of  objectives,  reduction 
of  curvature  and  apochromatic  or  semiapochromatic  correction  are 
completely  antagonistic  and  incompatible :  what  benefits  one  correc- 
tion is  detrimental  to  the  other.  Fortunately  the  extended  theory 
also  indicates  a  way  out  of  this  dilemma.  It  appears  fairly  certain 
that  by  building  the  objective  itself  on  the  lines  required  by  the 
apochromatic  condition,  but  leaving  it  spherically  undercorrected, 
perhaps  also  chromatically  overcorrected  to  a  moderate  extent,  and 
with  a  considerable  amount  of  outward  coma  (this  is  the  most 
important),  and  by  correcting  these  residuals  in  a  widely  sejparated 
additional  back  lens,  it  will  be  possible  to  combine  moderate  curvature 
of  field  with  apochromatic  perfection  and  thus  to  remove  the  worst 
outstanding  defect  of  the  best  objectives. 

Condensers  for  the  proper  well-regulated  illumination  of  micro- 
scopic objects  are  identical  in  optical  design  with  objectives,  the  only 
difference  being  that  the  light  passes  through  in  the  reverse  direction 
and  that  a  lower  degree  of  correction  is  sufficient  not  only  on 
theoretical  but  also  on  practical  grounds,  for  nearly  always  condensers 
are  used  in  conjunction  with  the  "  plane  "  mirror,  which  invariably 
is  very  far  from  optical  perfection,  and  so  introduces  irregular  aberra- 
tions of  unknown  magnitude  and  kind,  and  moreover  the  light  from 
the  condenser  has  to  pass  through  the  slide  on  which  the  object  is 
placed.  This  slide  is  practically  little  better  than  window  glass  as 
far  as  optical  quality  and  perfection  of  surfaces  is  concerned,  and 
the  great  variation  in  thickness  is  another  source  of  imperfection, 
especially  with  dry  condensers  of  high  N.A. 

Moderate  amounts  of  residual  aberrations  in  condensers  can 
always  be  effectively  neutralised  by  using  a  sufficiently  large  source 
of  light  of  uniform  brightness  or  by  magnifying  the  source  by  a 
sufficiently  well-corrected  "  bull's-eye,"  if  the  source  of  light  is 
naturally  small. 


64  NOTES    ON    MICROSCOPICAL    OPTICS: 

A  great  and  very  serious  defect  in  the  construction  of  nearly  all 
condensers  of  the  present  day,  with  the  exception  of  the  modest 
''Abbe  "  Condenser  of  two  simple  uncorrected  lenses,  is  that  the  Iris 
and  the  ring  for  dark  ground-stops  are  placed  too  far  from  the  back 
lens  instead  of  being  close  to  the  anterior  focal  plane  of  the  con- 
denser. It  is  easily  shown  that  such  a  remote  Iris-opening  or  dark 
ground-stop  produces  decidedly  oblique  illumination  of  the  extra- 
axial  points  of  the  object.  With  direct  light  this  leads  to  an 
undesirable  variation  of  the  type  of  image  and  of  resolving  power 
in  different  parts  of  the  field.  With  dark  ground  illumination  the 
result  is  even  more  serious,  for  it  is  then  necessary  to  use  a  far 
larger  central  stop  to  secure  a  dark  background  over  the  whole  field 
than  would  suffice  if  the  stop  were  placed  close  to  the  anterior  focal 
plane  of  the  condenser :  such  an  unnecessarily  large  stop  is  highly 
objectionable,  because  it  reduces  the  visibility  of  the  coarser  struc- 
tures in  the  object. 

The  increasingly  bad  position  of  the  iris  in  the  condensers  of 
higher  power  and  shorter  focal  length  supplies  practically  the  whole 
explanation  of  the  universal  experience  that  high-power  condensers 
will  not  work  satisfactorily  with  low  power  objectives,  especially  for 
dark  ground  illumination. 

The  great  thickness  of  the  mechanical  stage  in  English  stands 
of  the  highest  quality  is  the  chief  reason  why  the  iris  and  "  turn- 
out-ring "  of  high-power  condensers  have  to  be  mounted  so  far 
below  the  back  lens  and  a  profound  modification  of  the  design  of 
the  stage  with  a  view  to  making  the  part  projecting  over  the  con- 
denser as  thin  as  possible  therefore  appears  to  be  the  most  desirable 
improvement  of  microscope  stands  from  the  optical  designer's  point 
of  view. 

In  concluding  these  remarks  on  the  optical  design-  of  microscope 
lenses  I  wish  to  point  out  that  the  whole  subject  is  adequately  dealt 
with  in  my  lectures  and  classes  at  the  Imperial  College,  and  that 
students  attending  these  for  two  or  three  years  will  be  turned  into 
competerit  designers,  provided  that  they  have  a  liking  and  natural 
aptitude  for  applied  mathematics,  are  good  at  numerical  calculations, 
and  of  an  inventive  type  of  mind. 

As  regards  the  (icfiidl  iiuihiiKj  of  iniriosropc  object  ires,  it  must 
be  borne  in  mind  that  the  excellence  of  a  computed  lens  system  may 
be  completely  swamped  by  comparatively  slight  imperfections  of 
workmanship,  and  that  high  accuracy  in  this  respect  is  therefore  of 
the  utmost  importance.  In  lenses  of  high  N.A.  computation  shows 
that  a  departure  from  the  prescribed  radii  and  thicknesses  by  a 
fraction  of  a  thousandth  of  an  inch  may  lead  to  a  notable  loss  of 
perfection,  and  the  polished  surfaces  must  also  be  truly  spherical 
within  less  than  half  a  wave-length  of  light.  These  limits  can  be 
easily  observed  if  modern  methods  of  gauging  and  measuring  are 
adopted,  and  if  all  surfaces  are  polished  to  accurately  made  and 
conscientiously  used  test-])lates.  In  the  later  years  of  my  connection 
with  the  optical  industry  quite  large  batches  of  lenses  used  to  be 
made  directly  from  purely  theoretical  calculations  of  objectives  of 
new  types  without  any  preliminary  trials  and  without  any  experi- 
mental changes  in  the  finished  objectives,  95  or  more  per  cent,  of 
which  would  be  found  satisfactory  in  all  respects  just  as  they  came 


A.    E.     CONRADY  65 

from  the  mounters'  lathes.  The  tools  and  methods  employed  in 
really  manufacturing  lenses  on  this  system  were  shown  by  Messrs. 
W.  Watson  and  Sons,  Ltd.,  at  the  exhibition  at  King's  College  in 
January,  1917,  and  will  be  found  described  and  illustrated  in  the 
record  of  that  exhibition. 

Ill  old  English  practice  the  component  lenses  of  microscope 
objectives  and  condensers  used  to  be  fixed  in  their  cells  by  cement 
of  the  sealing-wax  type.  Many  old  lenses  which  are  still  found  in 
perfect  adjustment  50  or  more  years  after  being  mounted  demonstrate 
that  the  cement  may  hold  the  lenses  in  correct  position  almost  inde- 
finitely :  but  other  experiences,  especially  with  lenses  used  in  tropical 
countries,  suggest  that  shifting  may  occur,  and  it  is  therefore  to  be 
strongly  urged  that  all  microscope  lenses  should  be  held  between 
metallic  shoulders  at  both  ends  by  being  bezelled  into  their  cells, 
care  being  naturally  required  to  avoid  pressure  and  distortion  through 
too  tight  a  fit. 

A  few  words  may  usefully  be  addressed  to  the  users  of  microscope 
objectives.  All  the  higher  powers  are  very  sensitive  (the  more  so 
the  more  perfect  the  spherical  correction)  to  the  thickness  of  the 
coverglass  ylus  any  mounting  niediuni  intervening  between  object 
and  coverglass,  and  also  to  variations  of  tube-length,  and  the  best 
result  can  only  be  obtained  by  adapting  the  tube-length  (or  the 
adjustment  of  the  correction-collar  if  there  is  one)  to  the  individual 
coverglass.  It  is  grossly  unfair  to  interchange  one  objective  with 
another  of  similar  power  but  different  make  on  the  tube-length 
suiting  the  objective  treated  as  the  standard  and  then  to  condemn 
the  new  objective  (usually  an  English  one !)  because  it  gives  an 
obviously  inferior  image.  It  is  not  even  fair  merely  to  find  the  best 
tube-length  for  the  new  objective,  for  if  the  change  of  tube-length 
is  considerable  and  in  the  direction  of  lengthening,  the  total  mag- 
nification will  be  much  higher  and  the  image  correspondingly  duller 
and  more  fuzzy.  To  make  the  comparison  fair,  each  objective  should 
be  tried  at  its  own  best  tube-length,  and  with  such  an  eye-piece  as 
to  give  practically  the  same  total  magnification. 

Another  point  on  which  users  of  objectives  err  to  their  own 
detriment  is  an  excess  of  faith  in  numerical  aperture,  I  have  heard 
microscopists  boast  of  possessing  an  objective,  say,  of  1.43  N.A., 
whereas  somebody  else  had  one  of  only  barely  1.40,  and  a  careful 
test  would  show  that  whilst  the  1.43  was  an  indifferent  lens,  the 
1.40  was  excellent.  The  fancied  advantage  of  2  per  cent.,  then,  is 
really  a  disadvantage  of  perhaps  25  per  cent,  or  more. 

One  of  the  few  disservices  which  Abbe  did  to  microscopy  was 
the  pushing  of  the  N.A.  of  dry  lenses  to  .95  and  to  a  lesser  extent 
the  increase  of  that  of  oil-lenses  to  1.40.  The  extreme  marginal  zone 
of  the  apochromatic  dry  objectives  of  .95  N.A.  is  particularly  badly 
corrected,  so  much  so  that  the  lenses  will  only  bear  a  solid  illumin- 
ating cone  of  about  .65  N.A.  even  on  the  Abbe  test-plate,  and  that 
with  annular  light  bringing  only  the  marginal  zone  into  action 
correction-collar  and  tube-length  combined  do  not  allow  of  reaching 
a  point  of  good  spher^'cal  correction.  There  is  no  doubt  that  Abbe's 
own  earlier  dictum  still  holds,  to  the  effect  that  beyond  about  .85 
N.A.  the  higher  aberrations  become  unmanageable  unless  the  free 
working  distance  is  reduced  to  a  very   few  thousandths  of  an  inch. 


66  NOTES    ON    MICROSCOPICAL    OPTICS 

A  carefully  computed  objective  of  .85  N. A.  will  bear  a  full  illumin- 
ating cone  on  suitable  objects,  and  can  thus  realise  its  fullest 
resolving  power.  An  objective  of  .95  with  a  condenser  of  .65  has 
the  resolving  power  of  the  mean,  or  of  .80  N.A.,  and  is  thus  actually 
inferior  except  for  freak  resolutions  with  extremely  oblique  light. 
Oil  objectives  over  1.30  or  at  most  1.35  N.A.  are  also  of  very 
doubtful  added  value. 

In  closing  this  section  I  will  once  more  quote  without  comment 
an  anecdote  of  Fraunhofer,  who  received  a  complaint  that  a  tele- 
scope supplied  by  him,  although  giving  magnificent  images,  displayed 
certain  hne  scratches  when  examined  with  a  magnifying  glass  !  The 
reply  sent  by  Fraunhofer  is  reported  to  have  been : 

'■  We  have  constructed  the  telescope  to  be  looked  thrciigh,  not 
to  be  looked  at." 

A  few  sentences  may  perhaps  be  added  as  to  the  prospects  for 
further  improvements  of  microscopic  performances.  I  have  already 
stated  in  the  first  section  that  there  is  a  bright  ray  of  hope  with 
regard  to  diminishing  the  curvature  of  field  without  loss  of  definition. 
Advances  in  numerical  aperture  offer  very  little  attraction.  Abbe, 
in  my  opinion,  carried  the  N.A.  too  far  rather  than  not  far  enough, 
and  I  am  not  aware  that  any  notable  discovery  has  been  achieved 
with  the  few  monobromide-immersion  objectives  of  N.A.  1.60  which 
he  designed. 

The  use  of  shorter  wave-length,  i.e.,  ultra-violet  light,  is  a 
little  more  promising.  There  would  be  none  but  technical  difficulties 
in  the  construction  of  lenses  suitable  for  this  work.  But  as  only 
very  few  microscopists  would  be  likely  to  go  to  the  trouble  of 
working  in  invisible  light  and  of  passing  through  a  long  apprentice- 
ship in  mastering  the  difficulties,  apparatus  of  this  description  would 
necessarily  be  extremely  costly,  as  the  whole  expense  of  designing 
and  of  constructing  special  tools  would  fall  on  a  small  number  of 
outfits,  or  possibly  on  only  a  single  one.  And  there  would  still  be 
the  grave  drawback  that  the  vast  majority  of  objects  would  be 
opaque  to  extreme  ultra-violet  rays,  and  would  only  yield  black-and- 
white  outline  pictures. 

The  so-called  ultra  microscope  does  not  represent  any  advance  in 
resolving  power  at  all,  but  most  decidedly  the  reverse.  It  is  highly 
valuable  for  the  detection  of  very  minute  particles  and  of  their 
movements,  which  it  achieves  simply  by  intense  darkground  illumin- 
ation, but  the  structure  of  the  particles  remains  unrevealed,  and 
only  that  would  amount  to  an  advance  in  resolving  power.  The 
seeing  of  these  minute  particles  is,  in  fact,  of  precisely  the  same 
kind  as  the  seeing  of  stars  subtending  less  than  .001  second  of  arc 
at  nighb  with  the  naked  eye,  the  resolving  power  of  wliich  is  of 
the  order  of   60   seconds. 


Professor  Alfred  W,   Porter,  D.Sc,  F.R  S.,  spoke  on 
*'  The  Resolving  Power  of  Microscopes." 

NOTES  ON  THE  RESOLVING  POWER  OF  MICROSCOPES. 
By  Alfred  W.  Porter,  D.Sc,  F.R.S. 


The  question  of  resolving  power  was  first  of  all  discussed  in  con- 
nection with  telescopes;  but  the  problem  for  microscopes  is  essen- 
tially identical  with  that  for  telescopes.  The  fact  that  telescopes 
of  large  aperture  gave  smaller  star-images  than  those  with  small 
aperture  was  first  demonstrated  by  W.  Herschel  (1805)  and  later  by 
Foucault  (1858).  The  explanation  was  given  in  terms  of  the  wave 
theory  of  light  by  Fraunhofer  (1823)  and  by  Airy  (1834).  Owing 
to  the  wave  structure  of  light,  each  image  of  a  luminous  point 
formed  by  a  lens  is  found  (both  experimentally  and  by  the  wave 
theory  as  developed  by  Fresnel)  to  be  a  circular  bright  disc  sur- 
rounded by  dark  and  bright  rings  of  intensity  diminishing  outwards. 
If  there  are  two  bright  sources  sufficiently  close — two  stars,  for 
example — their  individual  discs  may  overlap;  and  for  a  certain 
degree  of  closeness  the  confusion  is  so  considerable  that  it  is  im- 
possible to  detect  the  double  nature  of  the  source. 

Some  convention  had  to  be  adopted  in  specifying  the  limit  at 
which  separation  between  the  discs  can  be  appreciated.  The  con- 
vention actually  adopted  has  been  based  on  the  fact  that  if  the 
centre  of  the  image  of  one  star  falls  on  the  first  dark  ring  of  the 
other,  then  the  brightest  part  of  the  combined  image  will  be  a 
figure-of-eight  disc  having  a  faint  diminution  of  intensity  at  its 
middle,  which  reveals  its  composite  character.  Now  the  radius  of 
the  first  dark  ring  (as  calculated  by  Fraunhofer)  is 

1.22  XF 
B 
where  B  is  the  diameter  of  the  object-glass  and  X  the  wave-length 
of  the  light  received.  The  angular  separation  of  the  stars  when 
just  resolved  (according  to  the  convention)  is  obtained  (in  radians) 
by  dividing  this  by  the  focal  length  of  the  lens.  The  reciprocal  of 
this  is  the  angular  resolving  power.  Practice  has  shown  (Dawes; 
E.  M.  Nelson)  that  resolution  is  obtained  when  the  sources  are 
more  than  25  per  cent,  closer  than  this.  It  was  shown  theoretic- 
ally by  A.  W.  Porter  (R.  Micr.  J.,  1908,  Part  I.)  that  the  true 
limit  (for  which  there  would  be  no  diminution  in  intensity  at  the 
middle  of  the  double  image)  corresponds  to  a  closeness  of  the  stars 
for  which  the  intensity  curves  would  cross  at  their  points  of  inflexion ; 
this  limit  corresponds  very  nearly  to  that  obtained  from  observation. 

The  question  of  resolving  power  is  not,  however,  an  exact  branch 
of  science.  It  is  the  *'  thing  seen  '"'  with  which  we  are  concerned, 
and  this  depends  upon  who  sees.     The  human  element  enters  ;   and 


68  NOTES  ON  THE  RESOLVING  POWER  OF 

ill  consequence  no  exact  statements  can  be  made.  All  we  can 
get  is  rough  estimations  by  which  the  quality  of  oj^tical  instruments 
can  be  compared.  The  conventional  limit  probably  supplies  this 
desideratum  as  well  as  any  other,  and  since  it  possesses  greater 
convenience,  it  may  continue  to  be  adopted,  except,  perhaps,  in 
special  problems. 

The  problem  of  the  microscope  has  been  studied  specifically  bv 
Helmholtz  (1874),  Abbe  (1873),  and  by  the  late  Lord  Rayleigh. 
The  name  of  the  late  Lord  Rayleigh  may  be  repeated,  because  he 
has  dealt  with  the  whole  problem  in  all  its  ramifications  in  a  way 
which  no  other  investigator  has  done.  In  particular  may  be  men- 
tioned the  following  pajDers  by  him:  ''  On  the  Diffraction  of  Object- 
glasses,"  Coll.  Papers,  Vol.  I.,  163  (1872),  "  Investigations  in 
Optics,"  I.,  415  (1879-1880),  ''  Resolving  Power  of  Telescopes," 
I.,  488  (1880),  "  Wave  Theory  Light,"  III.,  47-187  (1888),  "  The 
Theory  of  Optical  Images,  with  special  reference  to  the  Microscope," 
IV.,  235  (1896),  Ditto  (supplementary  paper),  V.,  118  (1903). 

The  microscope  problem  possesses  several  peculiarities  which  are 
not  met  with  in  stellar  observation.  In  the  first  place  the  object  is 
never  self-luminous  like  a  star,  and  much  depends  upon  the  char- 
acter of  the  light  transmitted  through  the  object  when  it  is  semi- 
transparent  or  reflected  from  it  when  it  is  opaque.  Again,  the 
object  seldom  consists  of  points  (which  would  be  imaged  as  dif- 
fraction discs  and  rings),  but  may  be  isolated  or  series  lines  or  may 
be  of  any  other  shape;  and  in  each  case  may  be  either  bright  or 
dark  compared  with  the  "  background  ";  each  case  requires  specific 
consideration.  No  one  has  worked  these  cases  out  in  full  except 
Lord  Rayleigh,  and  reference  must  be  made  to  his  papers  cited 
above  for  the  full  investigations.  We  can  deal  here  only  with  some 
general  considerations. 

In  the  first  place  the  essential  difference  in  detail  between  a 
telescope  and  microscope  arises  from  the  object  being  near  the 
objective.  It  becomes  convenient  to  refer  to  the  semi-anr/Ie  that 
the  objective  subtends  at  the  object  and  the  distance,  e  (instead 
of  the  angle)  between  the  two  sources  which  are  here  separated. 

Now  for  two  independent  points  the  distance  e  for  which  resolu- 
tion will  occur  is  for  a  rectangular  opening 

\ 

2  n  sm  a 

where  n  is  the  refractive  index  between  the  object  and  objective  and 
X  is  the  wave-length  of  the  light  employed.  On  the  other  hand, 
Abbe,  by  considering  a  series  of  linear  openings  as  object,  found 
if  the  phase  of  the  light  passing  through  each  opening  is  the  same 
for   all 

X 

6   =  — . ; 

n  sm  a 
which  is  twice  as  great  as  before.  The  quantity  n  sin  (t  he  called 
the  Numerical  Aperture,  and  the  reciprocal  of  e  the  resolving- 
power.  These  two  examples  bring  out  a  necessary  condition  for 
securing  fine  resolution.  The  value  of  e  is  half  as  great  as  when  the 
lights  from  different  points  of  the  object  are  independent,  as  when 
they  are  isophasal.  Now  this  independence  can  be  fairly  secured 
by  focussing   a   source   of   light   by   means   of   a  condenser   upon   the 


MICEOSCOPES:    ALFRED   W.    PORTER 


69 


object.  The  condenser  itself  is  an  optical  instrument  to  which  the 
principles  of  resolution  apply.  The  greater  the  Numerical  Aperture 
(N.A.)  of  the  condenser,  the  more  nearly  will  each  point  of  the 
object  be  seen  by  light  from  a  distinct  point  of  the  source;  but 
perfect  independence  is  never  secured.  On  the  other  hand,  if  no 
condenser  is  used,  or  if  it  be  not  focussed  for  the  object,  each  point 
of  the  source  will  send  light  practically  in  one  phase  to  a  large 
patch  of  the  object.  Other  points  will  do  the  same.  Thus  the 
independence  between  the  lights  at  different  points  of  the  object 
breaks  down,  and  Abbe's  result  will  be  approximated  to.  That 
is,  for  a  dry  objective  (n  =  1),  instead  of  being  able  to  resolve 
lines  separated  by  X/2  if  sin  a  =  1,  their  distance  apart  will 
require  to  be  at  least  X.  It  is  this  halving  of  resolving  power 
which  is  brought  about  by  replacing  proper  by  random  illumination. 


The  difference  between  these  two  cases  may  to  some  appear 
obscure.  It  depends  on  the  fact  that  the  light  which  passes  through 
neighbouring  openings  in  the  object  spreads  out  by  diffraction  and 
the  diffracted  beams  overlap  in  the  field  of  view.  If  there  is  no 
definite  phase  relationship  between  these  beams  the  case  is  analogous 
to  that  of  illumination  by  two  candles — the  intensities  of  light 
can  then  be  simply  added  together.  When  there  is  a  phrase  relation- 
ship this  is  not  lihe  case.  At  points  where  there  is  an  opposition 
in  phase  the  resultant  amplitude  may  be  zero.  At  intermediate  points 
the  phase  difference  may  be  zero  or  a  whole  number  of  periods.  In 
this  case  the  resultant  amjiUtude  is  the  sum  of  the  separate  ampli- 
tudes and  the  intensity  is  the  square  of  the  amplitude.  For  the 
sake  of  illustration  two  such  superposed  illuminations  are  shown 
in  the  figure.  The  dotted  curve  represents  the  components  placed 
so    that    the  maximum    of    one    occurs    at  zero    of    the  other.      The 


70  NOTES  ON  THE  RESOLVING  POWER  OF 

curve  A  is  the  resultant  wlieu  the  separate  illuminations  are  inde- 
pendent, while  B  is  the  resultant  when  they  are  taken  to  be  in 
the  same  phase.  From  A  it  might  be  inferred  that  the  object  was 
double  from  the  presence  of  the  two  maxima  in  the  resultant  curve ; 
in  B  the  two  maxima  have  merged  into  one  and  the  resolution  has 
vanished. 

Examining,  then,  the  case  of  two  bright  lines  as  the  standard, 
it  is  seen  that  for  a  dry  objective  they  must  not  be  closer  than  half 
a  wave-length  for  resolution  under  the  best  conditions  of  illumina- 
tion. For  the  middle  of  the  visible  spectrum  this  means  e  = 
.000025  cms.  For  an  immersion  objective  with  immersion  medium: 
of  refractive  index  n  this  should  be  divided  by  n.  For  light  of 
shorter  wave-lengths,  e  is  proportionately  less.  Since  this  value 
is  calculated  (for  simplicity)  from  the  assumption  that  the  lens 
aperture  is  rectangular,  instead  of  circular,  it  differs  very  little 
from  the  limit  given  by  the  modified  definition  given  by  me  and 
quoted  near  the  beginning  of  this  paper. 


Magnification . 

When  an  image  is  resolved  it  does  not  follow  that  it  will  be 
seen  to  be  resolved.  The  division  marks  on  a  scale  may  be  perfectly 
separate  lines  (much  more  so,  in  fact,  than  most  optical  images) ;. 
yet  they  will  not  be  seen  separate  if  placed  too  far  from  the  eye. 
It  was  stated  by  Helmholtz  that  they  must  subtend  an  angle  between 
one  and  two  minutes  of  arc  in  order  to  be  seen  as  separate  lines.  In 
my  own  case  and  in  those  of  about  ten  others  recently  tested  the 
separation  begins  at  about  two  minutes,  i.e.,  at  shortest  distance  of 

V 

clear    vision,   V,    the    lines    must    be    separated    about  .       This 

'      '  ^  1800  ^ 

statement,  of  course,  assumes  that  the  eye  can  focus  the  lines  in 
the  position  at  which  they  are  placed  either  without  artificial  aid 
or  with  the  appropriate  spectacles.  It  is  also  assumed  that  the 
illumination  is  good  reading  light.  If  the  two  lines  in  the  image- 
just  resolved  by  a  microscope  objective  subtend  less  angle  than  this, 
they  will  not  be  seen  resolved.  We  can  calculate,  therefore,  the 
limiting  magnification  necessary.  An  approximate  calculation  is 
sufficient. 

With    a    total    magnification    of   MiMj    the    size   of    the    image^ 
formed  by  the  eye-piece  is 


\ 


It  is  this  that  must  be 


M.M,.-. 

V 

1800' 

ication 

V 

1800' 

2 

X 

25  cms 

900X5.0X10 

'cms 

10* 

18 

.  =  555    nearly. 

MICROSCOPES:    ALFRED    W.    PORTER  71 

This  is  the  least  total  mgignification  necessary  to  reveal  the 
structure  in  the  case  of  this  very  successful  resolution  with  a  xiry 
objective  (N.A.  —  1);  and  it  is  important  to  observe  that  it  will 
only  just  reveal  it.  Now  to  see  scale  divisions  well  we  do  not  place 
the  scale  so  that  they  are  only  just  separable.  Even  double  the 
angular  limit  is  advisable — and  in  some  cases  more.  We  may  safely 
then  take  more  like  1,000  magnifications  for  N.A.  —  1,  and  up 
to  1,500  for  N.A.  =  1.5.  This  is  precisely  one  of  those  data  that 
cannot  be  definitely  stated.  We  may,  in  fact,  use  10  times  the 
above  minimum  magnification  in  certain  cases  with  advantage.  But 
attention  must  be  paid  to  one  consideration  in  regard  to  which  the 
graduated  scale  analogy  is  misleading.  We  bring  a  scale  nearer 
not  only  to  see  the  graduations  easily,  but  to  estimate  small  fractions 
of  a  division  correctly.  This  presupposes  that  the  marks  are  very 
fine — much  finer  than  the  interval  between  them.  Now,  in  the 
image  of  an  object  whose  structure  is  comparable  with  e  —  X/2 
there  may  be  detail,  but  this  detail  is  quite  unlike  the  object.  The 
artificial  detail  may  be  made  clearer  by  extra  magnification;  but 
if  the  purpose  of  the  observer  is  to  find  what  the  object  is  like^ 
and  not  that  of  an  investigator  of  the  errors  of  optical  images,  the 
revelation  of  this  artificial  detail  is  useless  and  misleading.  The 
only  justification  for  excessive  enlargement  is  when  the  image  is 
thrown  on  a  screen  for  inspection  by  a  class,  or  similarly  when 
a  photographic  print  is  made  for  the  same  purpose.  In  these  cases 
it  is  intended  to  be  observed  from  a  distance;  and  the  useful  mag- 
nification is  then  such  as  will  enable  the  true  detail  to  be  seen 
while  the  finer  false  detail  will  be  blurred  and  inconspicuous.  We 
must,  therefore,  distinguish  between  useful  and  useless  magnifica- 
tion. It  ought  to  be  observed  that  it  does  not  matter  so  far  as 
this  question  is  concerned  whether  the  magnification  is  chiefly  or 
entirely  due  to  the  objective.  The  eye-piece  may  be  disp\ensed  with, 
as  is  sometimes  done  in  photomicrography;  the  calculation  will  not 
need  any  change. 

This  question  should  also  be  looked  at  from  another  standpoint. 
The  eye-piece  forms  an  image  of  the  back  lens  of  the  objective- 
outside  itself;  this  is  the  "  bright  spot,"  or  Ramsden  circle.  The 
rays  that  go  through  the  bright  spot  are  all  those  which  penetrate 
the  objective   and    a.re   not  stopped.      The    diameter    of   this  spot  i^ 

approximately     -  x    diam.    of   back    lens   of    objective,   where    T    is 

the  tube  length  and  f  the  focal  length  of  the  eye-piece.  Now  irt 
telescopes  this  can  be  larger  than  that  of  the  normal  eye-pupil  with 
low  powers,  and  in  such  a  case  only  a  part  of  the  diameter  of  the- 
object-glass  is  used.  This  can  only  happen  with  very  low  powers 
in  microscopy.  But  with  high  powers  (f  small)  the  bright  spot 
is  very  small,  so  that  only  a  part  of  the  pupil  is  effective.  Now 
Helmholtz  concluded  that  the  normal  eye-pupil  will  not  bear  much 
reduction  without  the  image  seen  deteriorating,  owing  to  imperfec- 
tions in  the  eye.  This  point  is  not  easy  to  demonstrate,  because  reduc- 
tion in  the  aperture  of  the  eye  at  first  improves  definition,  since  the 
eye  is  by  no  means  free  from  aberrations.  In  my  own  case  a  fine 
line  begins  to  be  impaired  when  the  pupil  is  limited  to  2  mm.  dia- 
meter   by   an    artificial    diaphragm.        The     decrease     in     sharpness 


72  NOTES  ON  THE  RESOLVING  POWER  OF 

proceeds  only  slowly  at  first,  as  the  diaphragm  is  further  reduced, 
and  it  is  not  until  about  one  millimetre  diameter  that  very  con- 
siderable deterioration  is  noticed.  The  eye  is  itself  an  optical 
instrument.  The  radius  on  the  retina  of  the  first  dark  ring  of  a 
point  source  is  about  0.01  mm.  when  the  diameter  of  the  effective 
pupil  is  1  mm.  This  is  about  eight  times  the  diameter  of  a  retinal 
cone.      But  the  total  magnification 

T  V 
M=:MiM2=TT.  J  nearly 

V    diam.  back  lens  of  obj. 

F.  diam.   bright  spot       ; 

or  taking  V  =  25  cms.  and   2  mm.  as  the  diameter   of  the   bright 

spot,  the  magnification  becomes 

diam.   back  lens  obiective 
M  =  125 p ^— 

For  the  case  F  =  0.2  cms.,  back  lens  =  0.6  cms.  diam. 

M  =  375  diameters. 
If  we  suppose   a  reduction  of  the  bright  spot  to  0.1   cm.   diam.  to 
be  permissible  M  =  750  diameters. 

These  results  are  of  the  same  order  as  before. 

In  the  case  of  photomicrography,  as  we  have  seen,  the  per- 
missible magnification  is  the  same  whether  an  eye-piece  is  used  or 
not.  There  is  the  added  advantage  that  the  photographic  image 
can  be  examined  with  the  eye  at  best  ajperture.  On  the  other 
hand,  there  is  deterioration  in  the  image  due  to  the  grain  in  the 
plate,  by  an  amount  varying  much  for  different  plates.  Where  the 
finest  representation  is  required,  it  should  not  be  forgotten  that 
the  old  "  wet  "  process  could  be  resorted  to;  or,  failing  that,  process 
plates  are  the  next  best. 

The  attainment  of  as  close  an  approach  as  possible  to  perfect 
images  is  limited  by  the  extent  of  the  elimination  of  all  the  aberra- 
tions calculated  by  methods  of  geometrical  optics.  Professor  A.  E. 
Conrady  emphasises  the  fact  that  extension  of  numerical  aperture 
has  surpassed  the  value  warranted  by  the  existing  design  and  con- 
struction of  lenses.  The  same  may  be  said  concerning  condensers 
€ven  more  emphatically.  Pioneer  investigations  on  waves  of  non- 
spherical  form  were  made  by  Lord  Rayleigh  and  others.  The  varia- 
tion of  the  intensity  in  the  focal  plane  of  a  planoconvex  lens  has 
been  worked  out  by  L.  Silberstein  (Phil.  Mag.,  Jan.,  1918),  who 
at  the  same  time  exhibits  the  general  method  by  which  all  such 
problems  can  be  attacked  ;  and  the  same  kind  of  question  has  been 
worked  out  by  graphical  integration  by  Professor  A.  E.  Conrady 
(Monthly  Not.,  R.  Astr.  Soc,  June,  1919).  Not  only  are  the 
aberrations  of  the  "  lenses  "  important.  The  performance  of  a 
condenser  is  modified  by  the  presence  of  a  slide  of  very  imperfect 
optical  quality.  So  far  as  its  inequalities  in  thickness  are  concerned, 
the  errors  arising  are  much  reduced  by  the  immersion  medium 
when  used  with  the  condenser;  a  similar  remark  holds  in  regard  to 
the  objective  and  cover  glass. 

With  biological  speciniensi  the  objective  "  focusses  "  only  a  thin 
layer.  If  this  is  near  the  top  of  the  specimen,  the  light  from  the 
condenser  is  scattered  by  the  layers  beneath ;  if  it  is  near  the  bottom 


MICROSCOPES:  ALFRED  W.  PORTER        73 

then  the  same  applies  to  the  emergent  light.  In  either  case  there 
must  be  diminution  of  resolution.  In  the  case  of  metallurgical 
specimens  these  defects  are  absent.  The  light  is  reflected  from 
almost  a  mathematical  surface.  It  may  easily  be,  therefore,  that 
for  such  specimens  fullest  advantage  may  be  taken  of  permissible 
magnifying  power,  especially  where  the  detail  is  of  a  simple  char- 
acter. This  is  seen,  for  example,  in  Figure  23  of  the  contribution 
by  Sir  R.  Hadfield  and  Mr.  Elliot,  where  the  line  markings  of 
Pearlite  are  very  clearly  portrayed.  On  the  other  hand,  in  Figures 
24  and  25,  where  there  is  evidently  much  fine  detail  below  the 
resolution  limit,  it  is  not  clear  that  the  high  magnification  used  is 
any  advantage.  Even  if  this  fine  detail  appeared  sharp,  it  w^ould 
have  no  significance. 

In  the  metallurgical  case  it  must  be  borne  in  mind  that  if  the 
mirror  or  prism  in  the  vertical  illuminator  is  opaque,  it  blocks  out 
part  of  the  aperture.  The  resolution  of  lines  (such  as  those  of 
pearlite)  will  be  different,  according  to  the  azimuth  in  which  they 
lie.  Taking  the  aperture  as  semi-circular,  the  character  of  the 
image  of  a  point  is  a  central  oval  (instead  of  circle),  the  minor  axis  of 
the  oval  being  parallel  to  the  bounding  diameter  of  the  opening,  and 
about  half  the  length  of  the  major  axis  (Struve,  Mem.  de  I'Acad. 
des  Sc.  de  St.  Petersburg  (7),  XXX.,  No.  8  (1882);  Bruns,  Astr. 
Nachr.,  CIV.,  1  (1883);  Straubel,  Inaug.  Disert.,  Jena  (1888); 
Scheiner  and  Hirayama,  Abhand.  Gesell.,  Berlin  (1894);  P.  F. 
Everitt,  R.  Soc.  Proc,  A83,  302  (1910).  Scheiner  gives  a  photograph 
of  the  diffraction  figure.  Everitt  gives  also  a  diagram  of  lines  of 
constant  intensity). 

Ultramicroscopy . 

The  considerations  of  this  paper  give  no  indication  of  the  visi- 
bility of  isolated  particles,  but  only  of  the  possibility  of  detecting 
their  shape.  If  each  gives  sufficient  light  (either  by  self-luminosity, 
as  in  the  case  of  stars,  or  by  illumination  by  a  powerful  beam 
athwart  the  line  of  vision,  as  in  ultramicroscopy),  it  will  be  seen. 
The  amount  of  light  it  scatters  is  proportional  to  the  sixth  power 
of  its  radius  when  it  is  small  compared  with  the  wave-length.  Its 
image  is  almost  independent  of  its  shape  under  the  same  condition. 
Under  strong  illumination  larger  particles  (  <X)  give  complicated 
diffraction  figures;  but  not  much  can  be  learned  from  attempts  to 
interpret  them.  The  visible  disc  is  certainly  much  larger  than  the 
geometrical  image  of  the  particle.  Similarly,  a  luminous  line  gives 
an  image  much  wider  than  its  geometric  image.  This  case  and  that 
of  an  isolated  dark  line  of  finite  width  on  a  bright  background  have 
been  worked  out  by  Lord  Rayleigh.  In  the  latter  case,  when  the 
background  consists  of  light  all  in  one  phase,  he  concludes  that 
the  bar  might  w^ell  remain  visible  when  the  width  of  the  bar  is 
only  one  thirty-second  part  of  the  minimum  distance  between  two 
lines  for  resolution.  The  slightly  darkened  image  of  the  bar  has 
then  a  width  equal  to  about  sixteen  times  that  of  its  geometrical 
image  and  its  apparent  width  is  therefore  quite  illusory.  In  the 
case  of  a  self-luminous  background  {i.e.,  with  phases  completely 
independent),  a  bar  of  the  same  width  has  only  half  the  visibility 
of  the  previous  case,  but  it  should  bs  easily  recognisable  when  its 


74  THE   RESOLVING  POWER  OF  MICROSCOPES 

width  is  one-third  of  the  minimum  interval  for  resolution.  He  cites 
the  following  simple  experiment :  "In  front  of  the  naked  eye  was 
held  a  piece  of  copper  foil  perforated  by  a  fine  needle  hole.  Ob- 
served through  this,  the  structure  of  some  gauze  just  disappeared 
at  a  distance  from  the  eye  equal  to  17  inches,  the  gauze  containing 
46  meshes  to  the  inch.  On  the  other  hand,  a  single  wire  .034  inches 
in  diameter  remained  fairly  visible  up  to  a  distance  of  20  feet  or 
240  inches.  The  ratio  between  the  angles  subtended  by  the  periodic 
structure  of  the  gauze  and  the  diameter  of  the  wire  was  thus 

^^240 

.034      17 
He  finds  for  the  proportionate  loss  of  illumination  at  the  centre  of 
the  wire  in  this  case 

■        '-'-0.11 


I'- 

about  what  might  have  been  expected. 

The  moral  of  these  results  is  the  recommendation  of  caution  in 
interpreting  even  the  width  of  the  bars  causing  the  streaking  in 
microphotographs  of  pearlite,  etc. 

Besides  the  references  in  the  text,  the  following  may  be  given. 

Airy,  Tracts,  4th  edit.,  p".  316  (reprinted  as  "  Undulatory  Theory 
of  Optics  ");  Astr.  Monthly  Notices,  XXXIII.,  1872;  Camb.  Phil. 
Trans.,  1834. 

Foucault,  Ann.  de  I'Observ.  de  Paris,  t.v.,  1858. 

Verdet,  Legons  d'Optique,  t.l,  p.  265. 

Dawes,  Mem.  Astron.  Soc,  XXXV. 

Ch.  Andre,  Etude  de  la  Diffraction  dans  les  Instruments 
d'Optique,  Ann.  de  I'Ecole  Norm.,  1876. 

U.  Behn,  u.  W.  Heuse,  Zur  demonstrations  der  Abbeschen 
Theorie  des  Mikroskops,  Ber.  d.  deutsch  Physik  Ges.  4,  1906. 
Physik  Z.  Schr.  7,  750,  1906. 


Dr.  R.  Mullineux  Walmslcy,  Chairman  of  the  Technical 
Optics  Committee  of  the  British  Science  Guild,  outlined 
the  work  of  that  Committee. 


I  shall  not  detain  you  more  than  a  few  minutes.  I  attend  this 
afternoon,  as  you  know,  as  representative  of  the  British  Science 
Guild,  and  I  thank  the  President  for  his  kind  reference  in  his  Address 
to  that  Guild.  The  Symposium,  I  take  it,  and  I  hope  we  all  take 
it,  will  be  an  epoch  marking  symposium  in!  the  development  of  the 
microscope.  If  it  be  not  that,  I  very  much  fear  that  all  the  labour 
which  you,  Sir,  have  put  so  fully  into  the  organisation  of  this  Sym- 
posium will  not  have  answered  its  full  object.  That  being  so,  how- 
ever, I  .think  it  is  only  right  to  the  Guild  that  I  should  give  just 
the  bare  facts  of  its  connection  with  the  development  of  the  micro- 
scope in  order  that  they  may  be  placed  on  record  in  the  Minutes. 

It  was  on  14th  May,  1915,  that  the  British  Science  Guild  called 
a  Conference  of  manufacturers  and  users  of  microscopes  to  ascertain 
what  was  necessary  to  secure  to  the  British  Empire,  and  particu- 
larly to  the  British  Isles,  the  trade  in  these  valuable  instruments,  a 
large  part  of  which  for  so  long  a  period  had  gone  to  other  lands. 
Great  Britain  is  historically  and  in  many  ways  the  home  of  the 
microscope.  The  Conference  met.  It  was  attended  by  representa- 
tives of  the  leading  makers  of  microscopes  in  England  and  by  repre- 
sentatives of  Government  Departments,  including  the  "War  Office, 
the  Admiralty,  the  Colonial  Office,  and  the  India  Office,  and  by  cer- 
tain well-known  private  users  of  microscopes.  The  necessity  for 
standardisation  was  the  first  point  discussed,  and  was  very  generally 
recognised;  I  think  there  was  not  a  single  dissentient.  Details  were 
asked  for,  and  a  Committee  was  appointed,  which  met  quite  quickly, 
and  elected  for  its  Chairman  Sir  Ronald  Ross,  one  of  the  most 
distinguished  users  of  the  microscope  that  we  have.  The  Committee 
did  not  lose  much  time.  The  Conference  was  held  in  May,  the  Long 
Vacation  intervened,  but  the  Committee  reported  in  October,  1915. 
It  published,  for  further  discussion,  its  draft  specifications  of  three 
types  of  microscope,  one  for  general  use,  and  not  very  expensive ; 
another  type  for  advanced  pathological  work,  and  a  third  type  for 
research  work.  It  is  not,  perhaps,  surprising  that  with  a  distin- 
guished medical  man  at  its  head,  the  Committee  had  devoted  special 
attention  to  pathological  work. 

These  specifications  were  published,  and  criticisms  came  in.  It 
was  pointed  out  that  they  did  not  cover  the  whole  ground,  and 
therefore  the  Guild  appointed  another  Committee  to  consider  what 
other  microscopes  should  be  submitted  to  standardisation  by  definite 
official  specifications.  A  Committee  for  Microscopes  for  Special  Pur- 
poses was  appointed,  of  which  I  have  the  honour  to  be  the  Chairman. 
This  Committee  was  appointed  in  the  late  part  of  1915,  and  it  re- 
ported during  1916.  The  original  Committee  had  confined  its 
recommendations  in  regard  to  pathological  work  to  expensive  micro- 


76  DK.     R.     MULLINEUX    WALMSLEY 

scopes  for  advanced  and  research  work.  The  new  Committee,  assisted, 
as  was  its  predecessor,  by  manufacturers  and  distinguished  users  of 
the  microscope — and  for  their  assistance  at  both  Committees  the 
Guild  is  very  grateful  indeed^ — produced  a  specification  for  a  student's 
petrological  microscope,  another  one  for  general  use  in  chemical 
laboratories,  the  cost  of  which  was  not  to  exceed  £3  at  pre-war  prices  : 
and,  finally,  a  microscope  for  metallurgical  work,  in  connection  with 
which  it  had  the  assistance  of  distinguished  metallurgists.  These 
specifications  were  published  during  1916  and  circulated,  but  the 
trade  determined  that  during  the  continuance  of  the  war  nothing 
could  be  done  in  the  direction  of  standardisation  until  more  quiet 
times  came.  The  interval  was  not  altogether  lost,  for  these  draft 
specifications  were  subject  to  criticism,  and  amended  specifications, 
embodying  considered  modifications,  have  been  drawn  up,  which  we 
hope  will  be  satisfactory  to  the  trade  and  to  users.  The  specifica- 
tions will  be  published  shortly. 


A  group  of  papers  on  aspects  of  the  manufacture  of  the 
microscope  was  then  read  by  Mr*  Conrad  Beck,  Mr.  F, 
Watson  Baker  and  Mr.  Powell  Swift,  and  discussion  on 
these  papers  ensued. 


A   STANDARD  MICROSCOPE. 
By  Conrad  Beck. 

The  British  Science  Guild  having  prepared  a  specification  for 
a  standard  microscope,  we  have  been  engaged  for  a  year  in  working 
out  the  manufacturing  processes  necessary  to  produce  on  a  productive 
scale  a  microscope  that  should  fulfil  the  requirements  of  tnis  specifi- 
cation. The  instrument  has  also  certain  additional  new  features 
which  will  be  appreciated  by  microscopists. 

The  stand,  limb  and  body  are  of  a  very  solid,  well-finished  type, 
with  the  horseshoe  base,  jointed  pillar  and  Jackson-shaped  limb. 
The  base  and  stage  are  both  coated  with  a  thick  surface  of  ebonite, 
the  body  has  a  larger  tube  than  is  customary;  the  drawtube  is 
graduated,  and  gives  a  mechanical  tube  length  of  from  140  to  200 
millimetres.  The  standard  length  of  160  mm.  has  been  adopted 
for  which  all  object  glasses  are  corrected.  The  thickness  of  cover 
glass  for  which  dry  object  glasses  are  corrected  is  .15  mm.,  or 
.006  inch.  All  object  glasses  except  the  very  lower  power  are  of 
such  lengths  as  to  be  in  focus  when  used  on  a  nose-piece  or  an 
objective  changer.  The  fine  adjustment  is  of  entirely  new  design, 
the  two  milled  heads,  one  on  each  side  of  the  limb,  are  on  the  came 
axis,  but  each  milled  head  actuates  a  different  lever,  and  thus  there 
are  two  different  speeds,  one  of  which  is  double  as  fine  as  the  other, 
both  of  which  are  always  in  operation.  The  convenience  of  this  is 
apparent  to  those  who  use  object  glasses  of  different  powers.  A 
fine  adjustment  that  is  sufficiently  fine  for  delicate  examinations 
with  1/12  object  glass  is  frequently  troublesome  in  focussing  1/6  inch. 

The  action  of  the  slow  motion  is  by  a  screw  with  a  point  imping- 
ing on  a  lever.  This  method  has  been  considered,  and  iri  our  opinion 
correctly  so,  the  only  known  method  of  obtaining  an  absolutely  free 
movement  without  sag  or  backlash. 

The  base  of  the  microscope  is  provided  with  three  rubber  pads 
which  remove  vibration,  but  which  can  be  detached  if  a  rigid 
contact  with  the  table  is  preferred. 

The  instrument  is  supplied  in  its  simplest  form  with  a  plain 
tubular  substage  with  an  iris  diaphragm,  but  t"his  substage  can  be 
removed  by  the  microscopist  himself  and  replaced  by  any  of  the 
three  more  elaborate  forms  of  substage,  thus  converting  the  instru- 
ment into  a  complete  bacteriological  or  research  instrument. 

With  the  same  end  in  view,  a  detachable  mechanical  stage  can 
be  attached  at  any  time  by  the  worker  himself.  All  parts  are  made 
to  standard  gauges. 


78  A     STANDARD    MICROSCOPE 

The  base  measures  6^   x  4  x   1  inch. 

The  distance  of  the  stage  from  the  table  is  4|  inches,  which 
allows  more  room  for  substage  apparatus  than  has  been  generally 
given. 

The  diameter  of  the  mirrors  is  2  inches,  and  they  have  a  vertical 
adjustment  of  H  inches. 

The  stage  is  4  inches  across,  and  there  is  a  free  distance  of 
3  inches  between  the  optic  axis  and  the  limb. 

The  instrument  will  carry  the  ordinary  double  and  triple  nose- 
pieces,  but  we  have  taken  up  a  new  object  glass  changer  invented 
by  Mr.  Sloan,  of  Birkenhead,  which  we  have  found  by  prolonged 
use  to  possess  many  advantages  over  a  revolving  nose-piece,  and  by 
putting  down  tools  we  have  been  able  to  produce  it  at  a  very 
moderate  price.  The  design  is  so  simple  and  rigid  that  almost 
absolute  accuracy  of  centering  can  be  permanently  maintained,  and 
the  errors  of  mounting  of  individual  object  glasses  can  be  compen- 
sated. TTiere  are  no  slides,  but  the  adjustment  throughout  is  made 
by  screwed  abutment  pins  with  clamping  screws.  Once  these  are 
adjusted  and  fixed  they  cannot  shift,  and  the  utmost  error  we  have 
been  able  to  detect  in  the  alignment  of  the  optic  axis  by  the  tightness 
or  looseness  with  which  the  clamp  by  which  the  object  glass  and  its 
fitting  is  secured  to  the  microscope  is  about  1/6  part  of  the  field 
of   1/6. 

We  have  introduced  a  new  micrometer  eye-piece  and  a  new  system 
of  measurement  which  appears  to  be  in  advance  of  previous  methods. 
The  object  glasses  are  all  engraved  with  an  initial  magnifying  power, 
which  is  the  magnifying  power  at  the  first  image  formed  by  the 
object  glass  with  a  tube  length  of  160  mm.  We  have  designed  a 
new  vernier  scale  for  measuring  objects,  with  a  special  positive 
€iye-piece  which  is  entirely  above  the  scale,  and  when  this  is  placed 
in  the  microscope  the  scale  is  in  the  exact  position  occupied  by  the 
image  which  is  formed  by  the  object  glass  when  the  medium  power 
eye-piece  is  used.  The  object  under  examination  is  measured  in 
1/10  of  a  millimetre  on  this  scale,  and  the  result  divided  by  the 
figure  engraved  on  the  object  glass  gives  the  actual  size  of  the  object. 
If  a  stage  micrometer  be  placed  under  the  microscope,  the  initial 
magnifying  power  of  the  object  glass  may  be  checked,  though  this 
will  only  be  necessary  for  very  exact  work.  If  a  Sloan  object 
changer  is  used,  the  drawtube  must  be  set  to  150  mm.,  or  if  a 
nose-piece  is  used  it  must  be  set  to  145  mm.  to  compensate  for  the 
increase  in  tube  length  produced  by  these  pieces  of  apparatus. 


At  the  conclusion  of  his  paper  Mr.  Conrad  Beck  spoke 

on  "  Research  in  the  Use  of  the  Microscope." 

RESEARCH  IN  THE  USE  OF  THE  MICROSCOPE. 
By  Conrad  Beck. 

In  a  series  of  lectures  on  the  Theory  of  the  Microscope  which  I 
delivered  at  the  Society  of  Arts  in  the  years  1907-8,  1  concluded 
with  some  remarks  on  the  necessity  for  research  on  the  use  of  the 
microscope.  The  methods  upon  which  we  now  rely  for  the  finest 
results  obtained  with  high  powers  and  for  the  best  methods  of 
illumination  obtained  with  low  and  moderate  powers  are  chiefly  due  to 
the  work  in  the  past  of  British  amateur  microscopists  who  have 
worked  at  the  subject  as  a  hobby  and  not  as  a  profession.  Now 
that  the  simpler  problems  have  been  solved,  further  improvements  can 
only  be  looked  for  as  the  result  of  a  combination  of  theory  and 
practice  which  we  can  scarcely  expect  from  any  but  trained  research 
workers  who  can  bring  to  the  subject  a  combination  of  high  optical 
knowledge  and  great  skill  in  manipulation.  Such  work  will,  no 
doubt,  require  the  co-operation  of  the  manufacturer,  but  it  is 
hopeless  to  expect  that  the  manufacturer  himself  w^ll  have  time  to 
devote  to  the  elucidation  of  the  problems  themselves.  At  the  present 
time  there  are  a  large  number  of  questions  which  will  have  to  be 
solved  before  any  very  considerable  progress  is  made  in  the  science 
of  microscopy. 

In  the  lectures  to  which  I  refer  I  indicated,  as  an  example  of 
a  possible  direction  for  study,  the  ingenious  suggestion  of  Mr.  J.  W. 
Gordon  for  reducing  the  size  of  the  diffraction  disc  by  the  use  of 
annular  beams  of  light.  This  was  only  one  point  to  illustrate  the 
need  of  microscopical  research.  It  is  well  understood  that  high 
power  resolution  depends  on  the  aperture  of  the  object  glass,  and 
yet  in  the  new  and  extremely  promising  field  of  work  opened  up 
by  dark  ground  illumination,  we  are  deliberately  reducing  the  aper- 
ture of  our  object  glass  to  .9  or  even  .7  numerical  aperture.  There 
is  no  essential  reason  why  an  illuminator  could  not  be  devised  by 
which  much  larger  angles  could  be  used  in  the  object  glass. 

In  the  study  of  bacteria  by  dark  ground  illumination  the 
diffraction  images  caused  by  the  micro-organisms  are  extremely  con- 
fusing, and  there  is  room  for  research  as  to  whether  these  images 
could  not  be  profoundly  modified  by  different  methods  of  illumina- 
tion, and  to  what  extent  the  diffraction  images  indicate  the  struc- 
ture of  the  organisms. 

Another  question,  which,  in  my  opinion,  calls  for  serious 
research,  is  whether  and  to  what  extent  a  wide  angle  cone  of  light 
used  in  examining  a  histological  specimen  reveals  or  diseuises  struc- 
ture, and  to  what  extent  the  increase  in  brilliancy  of  ilhmiination 
induced  by  opening  up  the  aperture  of  the  condenser  increases  or 
reduces  the  perfection  of  the  image.  I  do  not  think  there  has  been 
a    satisfactory   investigation    on   the    examination   of    this    class    of 

79 


80       KESEAKCH   IN   THE   USE   OF   THE  MICROSCOPE 

object  with  different  apertures  in  the  condenser  when  a  proper 
compensating  apparatus  for  keeping  the  intensity  of  the  light  the 
same  with  all  apertures  in  the  condenser  is  employed.  Neither  has 
there  been  sujSicient  attention  paid  to  the  question  of  increasing  or 
reducing  the  brilliancy  of  the  illumination  without  varying  the 
aperture  of  the  condenser. 

In  metallurgical  work,  the  method  of  throwing  the  light  through 
the  object  glass  on  to  the  object  is  undoubtedly  very  effective,  but 
every  convex  surface  that  the  light  meets  in  passing  through  the 
object  glass  must  of  necessity  throw  back  a  proportion  of  the  light, 
thus  fogging  the  final  image.  There  is  room  for  research  as  to 
another  means  of  illuminating  the  opaque  objects  to  eliminate  this 
element  of  flare  and  ghost  images. 

This  short  paper  is  written  to  indicate  by  a  few  suggestions  that 
we  are  more  likely  to  obtain  real  advances  in  microscopy  by  setting 
up  researches  on  the  use  of  the  instrument  than  by  devoting  the 
whole  of  our  time  to  the  discussion  of  the  mechanical  details  of  a 
slow  motion  or  the  most  convenient  diameter  of  a  milled  head.  I 
cannot  believe  that  we  are  likely  at  the  present  time  to  find  a 
body  of  disinterested  amateurs,  with  the  required  scientific  training, 
to  take  up  these  difficult  subjects.  The  subjects  I  have  mentioned  do 
not  begin  to  cover  the  field  of  research  that  is  required,  and  if  this 
meeting  could  be  made  instrumental  in  the  inauguration  of  this 
class  of  research,  it  will  have  accomplished  an  extremely  valuable 
piece  of  work. 


PROGRESS  OF  MICROSCOPY 
FROM    A     MANUFACTURER'S     POINT     OF     VIEW. 

By  F.  Watson  Baker. 

The  manufacturer,  of  necessity,  is  acquainted  with  the  trend 
of  microscopical  development  in  every  direction,  for  he  is  beset 
with  suggestion  and  demand  from  workers  throughout  the  world. 
The  instruments  he  designs  are  largely  moulded  on  his  interpreta- 
tion of  such  demands. 

To  a  great  extent  there  must  be  uniformity  of  design,  but  the 
expert,  being  usually  a  specialist,  finds  from  experience  that 
methods  of  work  which  he  adopts  as  his  own  entail  alterations  of 
construction,  and  there  is  a  tendency  for  such  workers  to  attach 
importance  to  these  details,  and  to  recommend  their  incorporation 
in   standard   models. 

It  would  be  a  matter  of  interest  to  see  what  the  result  would 
be  if  six  independent  leading  workers  were  to  prepare  a  specification 
of  an  ideal  ^^iicrcscops   and  Photomicrographic  Camera. 

English  manufacturers  have  been  in  a  position  to  meet  the 
varied  wishes  of  their  patrons,  because  much  of  their  work  has 
been  done  bv  hand,  and  whereas  with  the  machine-made  micro- 
scope of  the  Continent  and  America  the  pattern  has  had  to  be 
taken  as  it  stood,  stipulations  have  invariably  accompanied  orders 
for  all  classes  of  English  microscopes  that  certain  features  should 
be  varied  to  suit  the  special  views  of  those  with  whom  the  order 
rested. 

Manufacturing  in  this  manner  has  not  tended  to  economic  pro- 
duction, and,  judging  by  the  fact  that  it  is  possible  to  count  all 
the  manufacturers  in  Great  Britain  on  the  fingers  of  one  hand  at 
the  present  time,  it  will  be  fair  to  assume  that  such  work  is  either 
unremunerative  or  involves  difficulty  or  some  disadvantage  which 
discourages  enterprise. 

Past  history  reveals  the  fact  that  the  development  of  the 
mechanical  part  of  the  microscope  especially  has  been  due  to  the 
British  manufacturer,  who  has  been  largely  directed  and  aided  by 
notable  progressive   w^orkers. 

It  is  therefore  not  without  interest  to  mention  that  thirty-eight 
years  ag^o  microscopes  meeting  fully  to-day's  needs,  both  in  accuracy 
of  working  movements  and  stability  of  design,  were  made  in  this 
country. 

When  apochromatic  objectives  were  first  introduced,  the  only 
microscope  stand  on  which  they  could  be  advantageously  used  was 
a  British-made  one.  This  alone  had  a  fine  adjustment  worthy  of 
its  name  and  an  efficient  achromatic  condenser. 

Apochromatic  substage  condensers  with  means  of  centering  them 
to  the  objective,  the  mechanical  drawtube  and  the  incorporated 
mechanical  stage,  together  with  the  tripod  form  of  foot,  which 
alone  gives  stability  in  the  instrument,  were  first  made  in  this 
country. 


82  PROGRESS     OF    MICROSCOPY: 

The  British  maker  has  always  excelled  in  microscopes  of  high 
class,  involving  skilled  hand-work.  No  instruments  in  the  world 
to-day  vie  with  the  beautiful  hand-made  first-class  microscope  stands 
which  have  emanated   from  British  workshops. 

There  is  no  question  that  this  procedure  has  been  highly  approved 
by  expert  workers,  who  found  in  the  best  English  microscopes  the 
power  to  use  their  optical  systems  with  an  exactness  and  variety 
of  adjustment  which  is  not  supplied  so  completely  in  instruments 
of  other  countries. 

Students'  microscopes,  made  by  the  same  methods  with  constant 
variation,  could  not  compete  with  standard  models  made  by 
machinery. 

It  became  evident,  therefore,  to  those  who  were  anxious  to 
establish  the  English  microscope  on  a  sound  basis,  that  a  definite 
model  for  a  definite  purpose  must  be  made,  and  a  specification  for 
€ach  type  not  subject  to  variation  drawn  up  to  the  satisfaction 
of  those  who  directed  the  purchase  and  use  of  microscopes,  thus 
justifying  manufacturers  in  putting  down  plant  for  their  production 
in  large   quantities  under  economical  conditions. 

A  Committee  was  accordingly  formed  by  the  British  Science 
Ouild,  consisting  of  representatives  of  the  many  branches  of  Science 
and  Industry  and  Government  Departments  for  which  microscopes 
were  required,  and  eventually  definite  specifications  for  students, 
research  and  other  instruments  were  prepared,  which  have  received 
universal  approval. 

This  was  a  great  step  in  a  forward  direction  for  the  optical 
manufacturers.  Works  and  manufacturing  facilities  had  grown 
very  substantially  during  the  war,  but  the  hand- workers  of  the 
past  had  been  greatly  reduced  by  dispersal  and  death,  and  it  was 
no  longer  possible  to  make  microscopes  in  sufficient  quantity  in  the 
customary  manner  of  bygone  days.  They  were  therefore  able  to 
apply  much  of  their  plant  and  machinery  to  the  production  of 
machine-made  microscopes  for  students'  use  while  reserving  for 
the  few  hand-workers  available  the  refined  special  work  of  first-class 
instruments. 

The  amateur,  who  has  not  had  his  requirements  satisfied  for 
several  years,  is  pressing  for  supplies  of  the  best  patterns  of  English 
microscopes,  but  the  quantity  demand  comes  from  teaching  institu- 
tions, and  particularly  from  medical  workers.  Of  these  latter 
there  are  a  larger  number  than  in  pre-war  days,  and  it  is  believed 
that  the  machine-made  microscopes  on  the  specifications  referred 
to  will  be   found   satisfactory. 

On  the  optical  side,  the  production  of  microscope  objectives 
and  achromatic  condensers  has  been  fraught  with  difficulty.  Very 
little,  if  any,  of  the  pre-war  optical  glass  remained,  and  the  nearest 
substitutes  had  to  be  used  instead,  until  such  time  as  the  British 
glassmakers  were  able  to  give  all  the  varieties  that  were  required 
for  the  purpose.  Honour  is  due  to  them  for  the  success  they  have 
achieved  in  making  nearly  all  the  types  of  glass  that  have  been 
called  for. 

Even  for  a  fresh  melting  of  the  same  glass  it  is  generally 
necessary,  on  account  of  slight  differences,  to  make  changes  in  curves 
or   distances    of    components,   but  when    several   glasses    by    a    fresh 


F.     WATSON     BAKER  8a 

maker  are  dealt  with,  the  sum  of  the  differences  in  their  constants,, 
although  the  glasses  are  of  the  same  tyyes,  necessitates  the  complete- 
reconstruction  of  the  objective.  This  is  actually  what  is  happen- 
ing. It  has  only  been  during  the  last  few  months  that  the  varieties, 
of  glass  necessary  have  been  delivered. 

The  computation  of  a  high  power  objective  usually  occupies  several 
weeks,  and  when  this  is  done,  proof  plates  and  tools,  which  also 
require  great  care  and  a  considerable  amount  of  time  in  prepara- 
tion, have  to  be  made. 

The  full  programme  in  this  direction  has  not,  therefore,  been 
completed,  but  rapid  progress  is  being  made.  The  manufacturer  is. 
compelled  to  give  priority  to  the  production  of  objectives  that  are 
in  most  urgent  demand,  and  those  which  by  comparison  are  not  so 
important  will  be  made  in  full  quantity  as  time  progresses. 

If  the  English  microscope  is  to  be  firmly  established,  it  requires 
now  the  whole-hearted  support  and  recommendation  of  leaders  in 
this  country,  and  a  generous  patience  while  the  preparation  and 
supply  of  all  that  is  needed  is  taking  place. 

The  technical  side  of  microscopy  has,  in  this  country,  hitherto 
depended  on  two  or  three  men  whose  names  are  well  known.  The- 
means  of  education  in  practical  optical  science  have  been  excejed- 
ingly  limited  hitherto,  but  it  may  be  hoped  that  the  instruction 
now  being  given  in  this  subject  will  place  at  the  disposal  of  the 
optical  houses  in  the  near  future  an  increasing  number  of  capable 
opticians.  Such  men  must  possess  high  technical  and  mathematical 
attainments,  combined  with  practical  knowledge  which  can  only  be- 
obtained  in  the  workshop. 

There  is  one  more  point.  The  chief  reason  why  the  microscope- 
is  not  manufactured  by  a  larger  number  of  firms  in  this  country 
is,  not  merely  on  account  of  its  technical  difficulties,  but  because  it 
is  regarded  as  unremunerative.  One  large  optical  firm,  at  least, 
had  microscopes  in  its  post-war  programme,  but  on  studying  the 
question,  it  was  found  to  offer  such  small  prospect  of  return  for 
the  effort  and  outlay  that  the  project  was  abandoned,  and  financial 
men  show  no  disposition  to  embark  capital  in  a  business  of  so 
highly  technical  a  character.  So  it  comes  about  that  manufacturers 
are  thrown  very  much  on  their  own  resources,  and  it  is  suggested 
that  progress  could  be  hastened  and  the  whole  business  in  micro- 
scope manufacture  established  in  the  fullest  manner,  so  that  it 
could  stand  four  square  to  the  competition  of  other  countries,  if" 
capital  were  forthcoming  on  a  generous  scale  for  the  purpose. 


A    NEW    T^ESEARCH    MICROSCOPE. 
By  Powell  Swift. 


We  have,  in  connection  with  Messrs.  R.  &  J.  Beck,  been  in 
consultation  with  Sir  Herbert  Jackson  and  Mr.  J.  E.  Barnard 
concerning  the  requirements  of  a  better  research  microscope  for 
all  classes  of  exacting  work  than  has  hitherto  been  made.  This 
consultation  has  proceeded  only  so  far  as  to  deal  with  certain  impor- 
tant aspects  of  the  case.  We  think  the  advances  that  are  likely 
to  be  made  in  the  microscope  will  be  due  to  constant  discussions 
between  the  users  and  the  manufacturers  of  the  instruments,  and 
in  order  that  the  discussions  which  have  up  to  the  present  taken 
place  should  be  materialised  into  something  definite,  we  have  pre- 
pared a  model  embodying  the  points  that  have  been  so  far  settled 
and  which  should  form  a  stepping  stone  towards  further  progress. 

Whereas  a  standard  microscope  can  be  produced  which  may 
satisfy  the  requirements  of  the  ordinary  worker  for  a  reasonably 
long  period,  we  do  not  think  that  the  best  type  of  instrument  is 
likely  to  remain  stationary  as  long  as  scientific  progress  takes  place. 

Therefore,  in  putting  before  you  this  stand,  although  we  think 
it  marks  a  distinct  improvement  due  to  the  helpful  suggestions  that 
we  have  already  received,  we  must  take  entire  responsibility  ourselves 
for  the  details,  and  merely  express  our  thanks  for  the  valuable 
assistance  we  have  received  from  Sir  Herbert  Jackson  and  Mr.  J.  E. 
Barnard,  without  its  being  supposed  that  they  can  be  held  respons- 
ible for  an  instrument  which  we  have  made  in  order  to  exhibit  at 
this  meeting,  without  having  had  time  to  discuss  the  final  details 
with  them. 

The  first  point  which  was  considered  was  rigidity,  and,  while 
adopting  the  general  principle  of  our  "  Wales  "  model,  with  its 
curved  limb  and  radial  means  of  inclination,  the  casting  had  been 
made  with  a  metal  tie  of  great  strength  to  connect  the  portion 
carrying  the  body  with  that  carrying  the  stage,  so  that  when  moving 
from  the  vertical  to  the  horizontal  position  there  should  be  no 
alteration  in  focus,  due  to  the  slight  torsion  which  is  otherwise 
produced  in  the  curved  limb. 

The  body  is  2  inches  in  diameter,  so  that  a  photographic  lens 
placed  in  its  interior  enables  a  large  field  to  be  obtained  and  not 
cut  off  by  the  margin  of  the  tube.  A  rack  and  pinion  drawtube 
and  supplementary  sliding  drawtube  are  provided,  so  that  the 
mechanical  tube  length  can  be  varied  from  140  to  250  mm.  The 
fine  adjustment,  which  is  of  the  twin  side  rnilled  head  type,  is  fitted 
with  IMessrs.  Beck's  new  double  lever  adjus'tment,  providing  in  this 
manner  two  very  delicate  adjustments,  one  of  which  is  five  times 
as  fine  as  the  other. 

The  entire  stage  is  carried  on  a  very  massive  right  angle  cradle, 
and  racks  up  and  down,  with  all  its  apparatus  for  metallurgical 
work  having  a  travel  of  2^^  inches.  This  is  more  solidly  constructed 
than  has  been  the  case  with  such  instruments,  so  that  there  shall 
be  perfect  rigidity. 

84 


POWELL     SWIFT  85 

The  mechanical  stage,  which  rotates  concentrically,  and  is 
provided  with  centering  screws  for  adjusting  it  to  the  optic  axis,  is 
a  modification  of  that  of  our  "  Premier  "  model.  The  substage 
introduces  an  entirely  new  feature.  It  is  provided  with  two  cradles 
on  the  principle  of  the  Sloan  Objective  Changer,  introduced  by 
Messrs.  Beck,  so  that  the  whole  of  the  substage  apparatus,  when 
mounted  in  interchangeable  fittings  with  centering  adjustments,  can 
be  instantly  inserted  in  the  substage,  two  pieces  of  apparatus  being 
capable  of  insertion  at  one  time.  The  body  of  the  microscope  is 
provided  with  a  similar  cradle,  so  that  nose-pieces  of  a  special 
character  can  instantly  be  interchanged  if  desired.  For  instance, 
the  plain  nose-piece  may  be  replaced  for  petrological  work  with  a 
nose-piece  containing  an  analysing  prism,  Bertrand  lens,  quartz 
plate,  etc.,  or  with  a  nose-piece  containing  a  high  power  vertical 
illuminator  or  other  apparatus.  The  advantage  of  this  system  is 
applicable  also  to  a  great  deal  of  physics  research,  as  by  introducing 
special  apparatus  into  the  substage  or  nose-piece,  as  occasion  may 
require,  a  most  perfect  optical  bench  can  be  produced  for  general 
experimental  work.  There  is  a  considerable  class  of  delicate  optical 
research  which  calls  for  an  optical  bench  possessing  the  perfect 
adjustments  of  a  microscope,  and  we  believe  that  hitherto  this 
requirement  has  not  been  met.  By  examination  of  the  instrument 
it  will  be  seen  that  almost  any  class  of  apparatus  could  be  applied 
to  the  stand  for  making  small  and  accurate  measurements  in  physics, 
and  although  the  chief  object  of  this  instrument  is  to  provide  the 
most  perfect  microscope  that  can  be  required,  the  other  function 
for  such  an  instrument  has  been  borne  in  mind. 

The  base  of  the  microscope  is  of  the  English  tripod  pattern,  but 
has  been  provided  with  a  new  feature  which  is  specially  useful  for 
photomicrography  and  optical  bench  work,  which  will  also  be  appre- 
ciated by  the  ordinary  observer.  A  hook  shape  casting  is  supplied 
which  can  be  screwed  down  to  the  bench  or  camera,  and  an  eccentric 
bar  passing  through  the  centre  of  the  base  w^ill  slide  underneath 
this  hook,  when,  by  a  slight  motion  of  a  lever  at  the  side,  the  base 
of  the  microscope  is  locked  firmly  down  in  an  exact  position.  Another 
lever  between  the  uprights  of  the  base  clamps  the  joint  by  means 
of  a  right  and  left  hand  screw. 

We  have  not  alluded  to  the  rack  and  pinion  adjustments  of  the 
hody,  the  stage,  and  the  substage,  which  are  of  the  usual  spiral 
type,  but  might  well  call  attention  to  the  great  width  of  the  slides 
employed  to  give  great  stability  to  these  adjustments. 

It  was  decided  in  the  consultations  which  took  place  towards  the 
production  of  this  microscope  that  while  Messrs.  Beck  were  employed 
on  their  standard  instrument,  we  should  undertake  the  manufacture 
of  this  special  type,  which  would  in  all  probability  be  sold  by  both 
the  firms  by  whi^h  i't  is  manufactured. 


General  Discussion. 

The  Chairman  invited  discussion  on  the  group  of 
papers  just  presented,  and  he  called  on  Mr.  Barnard  to 
make  an  announcement. 


Mr.  J.  E.  Barnard :  The  point  that  I  wish  to  raise  will  only  take 
a  few  moments.  It  is  this,  that  Messrs.  Swift,  I  understand, 
have  quite  recently  manufactured  a  series  of  apochromatic  objectives. 
There  is  no  particular  innovation  in  that,  because  they  have  made 
them  for  years,  but  I  believe  that  they  admit  that  in  some  small 
particulars  they  come  short  of  the  German  standard.  They  are  so 
conscious  of  the  superiority  of  these  new  objectives,  however,  that 
they  are  anxious  that  a  Committee  should  decide  as  to  whether  these 
new  objectives  are  the  equals,  and  we  sincerely  hope  we  may  say  the 
superiors,  of  those  of  German  manufacture.  For  this  purpose,  there- 
fore, they  have  suggested,  and  after  consulting  with  Sir  Robert 
Hadfield  we  have  agreed,  that  a  Committee  should  be  asked  to  adju- 
dicate upon  them,  and  therefore  Sir  Robert  Hadfield,  as  President 
of  the  Faraday  Society,  the  Presidents  for  the  time  being  of  the 
Royal  Microscopical  Society,  the  Optical  Society,  and  the  Photo- 
micrographic  Society,  and  perhaps  such  an  eminent  authority  in  the 
application  of  objectives  to  metallography  as  Sir  George  Beilby  and 
one  or  two  others,  are  to  be  asked  to  go  into  the  question  of  the 
actual  value  of  these  objectives,  I  feel  quite  sure  that  that  is  a 
proposition  that  will  appeal  to  the  meeting  for  the  part  it  will 
play,  apart  from  any  other  question,  in  perpetuating  the  work  of 
this  Symposium.  Therefore,  even  if  the  results  arrived  at  are  not 
all  we  hope,  this  Committee  and  its  conclusions  will  form  a  very 
valuable  connecting  link  between  this  Symposium  and  any  succeeding 
work.  I  therefore  have  pleasure  in  moving  that  this  Committee  be^ 
authorised  to  proceed  with  this  question. 

Mr.  P.  Watson  Baker  (Messrs.  W.  Watson  and  Sons):  May  I 

enquire  whether  apochromatic  objectives  of  other  English  firms  can- 
also  be  included  ?  We  have  made  apochromatic  objectives  for  some- 
years,  and  are  quite  willing  to  submit  them. 

Mr.  Barnard:  T  should  say  there  is  no  question  about  that.  The- 
reason  T  brought  this  up  was  that  Messrs.  Swift  are  the  only  ones 
who  submitted  objectives  under  the  conditions  set  out,  but  if  any 
other  firm  is  in  the  position  to  submit  some,  the  Committee  will  be 
only  too  anxious  to  consider  them. 

Dr.  R.  Mullineux  Walmsley :  I  am  most  interested  in  this  ques- 
tion from  the  educational  side.  One  of  the  main  questions  before 
the  Symposium  is  the  production  of  microscopes  in  large  quantities, 
and  I  venture  to  suggest  that,  as  ^\v.  Watson  Baker  says  at  the 
end  of  his  paper,  the  colleges  concerned  must  give  him  the  necessary 


DR.    R.  M.   WALMSLEY,   LT.-COL.    GIFFORD  87 

men  for  that  work.  I  take  that  to  be  an  absolute  condition  if  we 
are  to  turn  out  instruments  of  high  precision  of  this  nature  in  quan- 
tity. The  key  of  the  situation  lies  in  the  inspection  room  of  the 
factory,  and  unless  the  inspection  room  is  adequately  staffed  with 
thoroughly  trained  men,  the  microscope  manufacturers  of  this  country 
cannot  hope  to  rival  what  has  been  done — to  which  I  refer  with 
some  diffidence  in  the  presence  of  the  President — in  the  engineering 
industry.  Every  engineer  knows  that  the  production  of  apparatus 
and  machinery  by  the  engineering  industiy — high-speed  steam  engines 
and  things  like  that — has  been  due  to  efficient  inspection  by  highly 
trained  men  in  the  inspection  department.  Parts  are  made  in  quan- 
tity, and  are  interchangeable,  and  the  thing  to  aim  at  is  to  take 
the  parts  from  store  and  have  them  fitted  together  without  further 
adjustment  by  skilled  workmen,  and  so  to  produce  the  finished 
article  or  machine.  If  the  inspection  department  does  its  duty,  we 
need  not  fear  the  competition  of  America  or  of  France,  both  of 
which  will  be  more  serious  than  that  of  Germany  in  the  near  future; 
we  need  not  fear  it  at  all.  The  British  microscope  will  then  stand 
before  the  world  and  hold  its  own. 

Lieut. =Colone!  Gifford :  In  my  experience  I  have  worked  out  a 
good  many  apochromatic  combinations,  chiefly  for  telescopes,  but  I 
have  never  found  any  three  glasses  which  gave  a  sufficiently  long 
focus  for  microscopic  objectives.  That  has  led  me  to  believe  that 
the  so-called  apochromatic  objectives  for  microscopes,  excellent  as 
they  are,  are  not  true  apochromatics ;  I  mean  lenses  which  combine 
foci  for  three  different  portions  of  the  spectrum.  Whether  that  is 
so  or  not,  I  do  not  know,  but  I  have  met  many  people  who  know 
something  of  the  subject  who  confirm  me  in  this  opinion. 

Instructor=Commander  M.  A.  Ainslie :  This  matter  of  the  apo- 
chromatic objective  has  been  occupying  my  attention  for  about  12 
years,  mainly  from  the  point  of  view  of  what  they  would  do  in  the 
resolution  of  very  fine  structure,  and  from  the  point  of  view  of 
comparison  between  different  types  of  objective.  What  put  it  into 
my  mind  to  address  the  meeting  was  the  fact  that  Mr.  Swift  just 
now  was  referring  to  his  own  objective.  Mr.  Swift  a  year  or  two 
ago  was  good  enough  to  send  me  two  4  mm.  objectives,  one  of  which 
was  entirely  the  equal  of  a  perfect  Zeiss  4  mm. ;  and  I  have  some 
knowledge  of  Zeiss  4  mm.  objectives,  because  I  have  used  18  of 
them  on  the  same  specimen,  and  I  know  that  specimen  by  heart. 
One  of  the  objectives  sent  me  by  Mr.  Swift  was  fully  equal  to  any- 
thing that  Zeiss  had  done,  but  the  other  one  was  not.  I  presume 
that  our  English  opticians  are  working,  so  to  speak,  to  a  standard. 
I  know  that  they  can  turn  out  work  which  is  in  every  way  as  good 
as  anything  that  has  ever  been  turned  out  in  other  countries ;  but 
while  Continental  opticians  seem  to  have  a  habit  of  turning  ,out 
what  I  might  call  objectives  of  80  to  85  per  cent,  perfection,  our 
English  opticians  seem  sometimes  to  turn  out  something  which  is 
very  fine — 95  per  cent. — but  they  often  also  turn  out  something 
which  is  about  60  per  cent,  perfection.  In  my  experience  in  an 
amateur  way,  I  have  tested  a  very  large  number  of  immersion  objec- 
tives, and   of  dry  objectives  with   apertures  from    .4   to   .95.      I   am 


88     INST. -COM.   M.  A.   AINSLIE,  DR.  E.   C.   BOUSFIELD 

bound  to  say  that  the  English  and  other  opticians  I  have  had  the 
pleasure  of  dealing  with  have  put  these  lenses  at  my  disposal  without 
stint,  but  I  feel  that  we  want  to  strike  a  far  higher  average  of 
excellence.  We  do  not  want  95  per  cent,  perfection  in  10  per  cent, 
of  the  cases,  and  the  remainder  under  60  per  cent.  We  want  to 
strike  a  90  per  cent,  average  and  depend  upon  it.  I  want  to  mention 
that  point  because  of  apochromatic  objectives  which  I  have  seen 
made  by  English  manufacturers.  I  can  single  out  a  4  mm.  of  Mr. 
Swift's,  a  4  mm.  .85  aperture  of  I\Ir.  Watson  Baker,  and  a  2  mm. 
of  Mr.  Watson  Baker.  I  cannot  tell  you  much  about  the  latter, 
because  I  do  not  know  what  became  of  the  lens,  but  it  was  a  very 
perfect  one  indeed.  I  can  fully  echo  any  remarks  that  have  been 
made  as  to  the  high  quality  of  possible  w^ork  of  English  opticians, 
but  I  also  should  like  to  mention  that  I  wish  they  would  always 
do  it. 


Dr.  E.  C.  Bousfield :  The  few  remarks  that  I  shall  make  to-night 
have   been    prompted    by    what   has  already    fallen,    especially    from 
Mr.   Barnard,  with  regard  to  apochromatic  lenses.     I  think  perhaps 
my  experience  of  them  is  longer  than  that  of  anyone  here,  since,  in 
conjunction  with  my   friend,  the  late  Mr.    Lees   Curties,   whose   loss 
so  many  of  us  deplore,  the  first  photographs  made  in  this  country 
with  Zeiss   apochromatic   lenses  were   made  in   my  own  house,    on  a 
dining-room  table,  incidentally  with  the  tunnel  built  up  with  books 
between  the  microscope  and  the  camera,  and  the  result  was  perfectly 
satisfactory.      I  think  success  in  this  matter  depends  comparatively 
little  upon  the  brasswork,  but  a  great  deal  upon  the  glasswork,   and 
almost  most    of    all   upon    the    operator.      The    apochromatic    lenses 
which  were  at  first   supplied  were   of  the   finest   possible  quality.      I 
think  I  have  seen  nothing  better  than  the  first  2  mm.  apochromatic 
lens  which   I  had    from  Zeiss,   but,  unfortunately,  as   was  the   case 
with  all  these  early  lenses,  the  glass  was  very  soon  attacked  by  the 
atmosphere,  and  in   substituting  a   glass  which   was   more   resistent, 
the  qualities    of   the    lens    suffered    very    considerably,   and    when    it 
was  returned  to  me  the  field  was  very  much  less  flat  than  it  had  been 
in  the  first  instance.     There  is  one  maker  who  has  not  been  referred 
to  to-night,  but  who  was  absolutely,   I   believe,  the  pioneer  of  apo- 
chromatic  lens  work    in  this   country — I   mean    the    firm    of    Powell 
and  Leeland.     Certainly  they  turned  out — and  I  say  it  without  any 
disrespect  to  anyone  else-  —the  very  finest  work  in  the  shape  of  glass- 
work  that  has  ever  been  used   in  the  world,  and   British   glass-work 
has  been  of  remarkable  excellence.     They  supplied  me,  for  trial,  with 
an  apochromatic  lens  of  their  own  manufacture,  which  was  calculated 
in    England    and  made   in    England,    and  it   was  absolutely  perfect, 
but  it  had  the  same  fault  that  the  Zeiss  lenses  had,  in  being  made 
of  unstable  glass.     None  of  the  2  mm.  lenses  that  I  have  seen  made 
of  the  more  resistent  glass  are  at  all  free  from  roundness  of  field.     I 
notice  that  in  one  of  the  papers  that  is  to  be  laid  before  us  reference 
is  made  to  this  roundness  of  field,  and  in  actual  working,   those  of 
us  who  have  tried  it  with,   say,    1,000  diameters,  will  agree  that  it 
is  a  very  serious  trouble  indeed,  and  I  do  not  see  any  way  of  getting 
over  it.     Lower  magnification  and  a  longer  camera  does  not  do  so. 
T  suppose  the  reasons  are  mathematical   ones,  which  are  beyond  me. 


LT.-COL.    GIFFORD,    J3K.    W.    ROSENHAIN  89 

I  can  only  state  the  fact  that  if  you  get  the  same  magnification 
with,  say,  a  J-inch  lens  and  a  long  camera  that  you  were  getting 
with  a  1-inch  lens  and  a  short  camera,  you  will  hardly  get  more 
flatness  of  field  in  the  one  case  than  in  the  other. 

There  is  just  one  other  point,  and  that  is  that  in  all  the  photo- 
micrographic  apparatus  which  I  have  seen  and  possessed,  there  is 
one  fault  which  seems  to  be  inseparable  from  the  instruments,  and 
that  is,  with  an  extended  camera,  the  connection  between  the  operator 
and  the  focussing  portion  of  the  microscope,  especially  with  lateral 
focussing  milled-heads.  These  are  extremely  convenient,  no  doubt, 
for  bench  work  in  the  laboratory,  but  for  ordinary  purposes  of  photo- 
micrography it  is  extremely  difficult  to  connect  them  satisfactorily 
with  any  form  of  extended  focussiug  arrangement,  and  in  any  photo- 
micrographic  apparatus  which  may  be  put  forward  that  point  should 
certainly  be  kept  in  mind.  The  most  efficient  contrivance,  I  think, 
that  I  have  ever  seen — and  the  hint  may  be  of  use  to  some  here, 
perhaps — was  that  of  my  friend,  Dr.  Neuhauss,  of  Berlin,  who  was 
well  known  as  one  of  the  very  first  photoinicrographers  in  Germany. 
He  simply  carried  a  straight  arm  down  from  the  axial  focussing  head 
of  the  fine  adjustment,  and  attached  a  string  to  the  lower  end,  with 
a  weight  on  one  side  and  a  drum  on  the  other,  and  so  he  managed 
to  get  his  focussing  fairly  accurate.  In  conversation  with  Dr.  Czapski 
once,  when  he  came  to  see  me,  I  pointed  out  to  him  that  I  found 
it  impossible  to  get  accurate  focussing  without  tapping  the  bench,  to 
make  sure  that  the  last  adjustment  was  as  delicate  as  possible,  and 
he  said,  "  Oh,  that  is  quite  the  regular  way  for  giving  the  final  touch 
in  delicate  measurement  " ;  so  that  I  presume  I  had  not  gone  very 
far  wrong. 

Lieut. =ColoneI  Gifford  :  I  have  in  my  possession  two  of  these  early 
Zeiss  lenses.  The  late  Mr.  C.  Lees  Curties  procured  them  for  me 
at  a  very  early  period.  One  is  marked  No.  2,  and  is  a  6  mm.  of 
0.95  N.A.,  and  the  other  is  a  3  mm.  of  1.40  N.A.,  and  is*  marked 
No.  34.  Neither  of  them  have  suffered  in  the  slightest,  and  I  use 
them  to-day  as  well  as  I  did  originally.  On  the  other  hand,  I 
have  Powell  objectives.  One  of  them  is  a  1/10  of  1.5  N.A. — a  very 
large  aperture  indeed — and  the  other  is  1/20  of  the  same  N.A.  The 
1/10  became  entirely  obscured  about  two  or  three  years  ago.  That, 
however,  has  been  renovated  by  the  present  Mr.  C.  Lees  Curties. 
The  other  one,  the  1/20,  has  stood  all  through.  At  the  same  time, 
if  you  compare  the  two  makers,  T  am  afraid  we  must  prefer  the  Zeiss. 
Eoth  lenses  which  I  possess  of  that  make  are  simply  perfect  ;  I  sup- 
pose they  could  not  be  quite  perfect,  but  they  are  as  perfect  as  they 
possibly  can  be.     They  stand  any  power  you  like  to  apply  to  them. 

Dr.    W.    Rosenhain,    F.R.S.:   I  want  to  draw  attention  to   one 

particular  point  about  the  discussion  which  has  impressed  itself  upon 
me  in  listening  to  it,  and  that  is  that  there  seem  to  be  two  totally 
distinct  questions  being  discussed  in  a  rather  confused  manner.  The 
one  is  the  question  of  establishing  a  commercial  and  industrial  pro- 
duction of  microscopes  by  mass  production.  This  is,  no  doubt,  a 
very   excellent  and  valuable  industrial   step,  with  which,   of  course. 


90  MR.    A.     C.     BANFIELD 

every  sympathy,  and  I  wish  it  every  success,  and  shall  be  glad  to 
do  anything  to  assist  it.  That  is  one  thing,  but  the  progress  of 
the  microscope  as  an  instrument  of  research  and  an  instrument  of 
precision  is  quite  another  thing,  and  we  must  not  forget  the  one  in 
view  of  the  other.  It  was  particularly  gratifying  to  find  that  whilst 
two  of  our  manufacturing  friends  were  good  enough  to  come  here 
this  evening  and  to  speak  almost  entirely  of  mass  production,  the 
third  gave  us  some  prospect  of  work  which  was  directed  towards 
achieving  the  best  possible  that  could  be  acKieved,  and  I  hope  that 
it  will  not  only  receive  the  acknowledgment  which  I  am  sure  it 
will  deserve  at  the  hands  of  all  users  of  the  microscope,  but  that 
all  manufacturers  will  feel,  I  think  I  may  say,  that  it  is  their 
duty,  to  look  after  that  side  of  the  thing,  just  as  much  as  to  send 
out  a  cheap  microscope  by  the  thousand ;  I  hope  they  will  succeed 
in  both. 

Mr.  A.  C.  Banfield  {C ommunicated). 

War  considerations  and  other  matters  have  prevented  any  active 
participation  on  my  part  in  things  microscopical  for  the  last  five 
years,  yet,  once  having  used  a  microscope,  it  is  impossible  entirely 
to  lose  one's  interest  in  this  important  aid  to  scientific  research. 

One  of  the  main  objects  of  this  Symposium  is  to  suggest  possible 
means  of  improvement  to  this  instrument,  and  I  will  confine  my 
remarks  entirely  to  certain  points  which  have  occurred  to  me  at 
various  times. 

(1)  It  is  the  custom  at  present,  in  all  high  grade  microscopes, 
to  supply  them  with  two  slides,  which  carry  respectively  the  coarse 
and  fine  adjustments.  This  is  an  expensive  form  of  construction, 
and  as  I  am  one  of  those  persons  of  opinion  that  very  little  is 
mechanically  impossible,  it  should  be  possible  to  eliminate  one  of 
these  slides,  making  the  single  slide  do  duty  for  both  adjustments. 
Also,  as  constructed  at  present,  the  fine  adjustment  slide  is  nearest 
to  the  limb,  thus  causing  the  delicate  micrometer  screw  or  lever  to 
carry  the  weight  of  the  parts  necessary  to  operate  the  coarse  move- 
ment in  addition  to  that  of  the  body  tube — the  only  part  the  fine 
adjustment  should  move. 

(2)  It  is  hard  to  explain  the  preference  which  undoubtedly  exists 
in  this  country  for  the  tripod  foot,  rightly  termed  the  *'  English  " 
foot,  for  it  exists  in  no  other  country.  Many  English  manufacturers 
enthuse  on  "  the  beautiful  hand  work  "  to  be  found  in  their  instru- 
ments, and  I  imagine  that  the  tripod  foot  is  especially  designed  to 
show  this  off.  Now  the  universal  trend  in  all  modern  manufacturing 
is  to  eliminate  entirely  all  possible  hand  work;  nothing  adds  more 
to  the  total  cost  of  any  article  than  operations  which  have  to  be 
carried  out  entirely  by  hand.  My  indictment  of  the  tripod  foot  is 
that  it  is  of  a  shape  which  is  difiicult  to  cast,  and  impossible  to 
machine.  It  is,  furthermore,  very  bulky,  and  seriously  interferes 
with  the  efficient  operation  of  the  sub-stage  when  the  microscope  is 
in  a  vertical  position.  A  greater  rigidity  is  claimed  for  this  foot ; 
this  certainly  is  correct  if  one  wants  to  lean  on  the  instrument, 
otherwise  there  is  no  advantage  over  the  horse-shoe  foot,  resting  on 
its  three  milled  pads. 


MR.    A.     C.     BANFIELD  91 

(3)  In  most  microscopes  that  I  have  used,  the  slides  have  been 
located  in  a  position  too  near  to  the  stage;  the  Continental  makers 
are  the  worst  sinners  in  this  respect.  The  result  of  this  practice  is 
that  when  an  object  is  focussed,  the  body  tube  has  to  be  very  con- 
siderably racked  out,  so  that  the  slides  only  engage  for  about  a 
third  to  half  of  their  possible  bearing.  This  does  not  add  to  the 
rigidity.  The  instrument  should,  of  course,  be  designed  in  such 
a  manner  that  with  an  objective  in  place  on  a  changer,  and  focussed 
on  an  object,  the  male  and  female  elements  of  the  slide  should  be 
in  complete  engagement  throughout  their  length. 

(4)  Even  at  the  present  state  of  mechanical  advance,  makers  are 
still  to  be  found  preaching  the  virtues  of  the  sprung  slide.  In  the 
whole  world  of  mechanics  there  is  no  more  horrible  device  than 
this.  It  is  supremely  inaccurate  and  unreliable,  and  is  merely  adopted 
as  an  expedient  to  cover  a  state  of  residence  in  the  dark  ages  of 
mechanics.  Incidentally,  I  may  remark,  there  seems  a  strange  dis- 
inclination on  the  part  of  instrument  makers  to  adopt  modern  manu- 
facturing methods,  the  broaching  machine,  with  the  wonderful  possi- 
bilities it  holds  out  in  the  direction  of  dovetail  and  other  slides,  and 
eye-piece  fittings  appear  to  be  quite  unknown.  Again,  take  such  a 
simple  job  as  a  body  tube.  The  common  practice  is  to  skim  this 
in  a  bench  lathe,  then  with  the  aid  of  a  file  and  French  cloth  bring 
it  to  the  lacquering  stage — a  tedious  job,  taking  quantum  sufficit, 
according  to  the  workman.  The  whole  job  can  be  don©  on  a  modern 
grinder  in  a  minute  and  a-half . 

(5)  Regarding  the  oblique  illumination  of  metallographic  speci- 
mens under  high  powers,  it  occurs  to  me  that  advantage  may  occur 
by  reviving  that  old  idea  of  fifty  years  ago  in  a  modern  form.  If 
a  glass  rod,  say  a  quarter  of  an  inch  in  diameter  and  four  inches 
long,  is  taken,  and  the  ends  squared  and  polished,  it  will  serve  to 
convey  light  from  a  source  to  an  object  with  practically  no  loss. 
One  end  may  almost  touch  an  open  arc,  for  instance,  thus  gathering 
rays  at  a  high  angle.  These  rays  are  carried  along  the  rod  by 
internal  reflection  (there  is  no  need  to  silver  the  rod  externally), 
emerging  at  the  far  end  in  a  beautifully  diffused  bunch.  This  is 
no  novelty  to  most  of  you,  but  I  suggest  that  a  variation  of  this 
idea  may  be  of  use  in  metallography.  Take  a  worked  slip,  like  a 
small  Lummer  plate,  say  4  mm.  wide  and  J  mm.  thick.  On  one 
end  balsam  a  hemi-cylindrical  lens  of  3  or  4  mm.  radius.  The 
other  end  can  be  introduced  well  under  an  immersion  objective, 
not  quite  under  but  probably  far  enough.  For  this  purpose,  the 
slip  would  have  to  be  silvered,  except  at  the  ends,  otherwise  the 
light  would  leave  the  slip  at  the  first  contact  with  the  oil.  At 
the  other  end,  parallel  rays  are  directed  from  some  powerful  source. 
I  merely  suggest  this  expedient  for  your  consideration,  as  there 
appears  to  be  a  necessity  for  it  at  times. 

(6)  I  have  no  practical  acquaintance  with  metallography,  but  a 
specimen  was  sent  to  me  a  few  days  ago  by  a  Sheffield  firm.  Now 
this  specimen  is  distinctly  spherical,  and  if  specimens  of  this  descrip- 
tion   are  the    rule  and  not   the    exception,    I    do   not   wonder    that 


92  MR.    A.     C.     BANFIELD 

complaints  "  that  the  objective  has  not  a  flat  field  "  are  so  common. 
The  objective  is  computed  for  a  mathematically  flat  object;  if  the 
specimen  deviates  from  a  true  plane,  then  definition  is  bound  to 
suffer.  I  merely  refer  to  this  point  because  it  suggested  to  me  an 
idea  which  it  may  profit  some  capable  mathematician  to  investigate, 
which,  briefly.,  is  this:  — 

It  is  just  as  easy  to  prepare  a  metal  specimen,  worked  to  a 
definite  radius,  as  it  is  to  work  it  to  a  plane.  Unfortunately,  I 
am  not  a  mathematician,  but  I  suggest  that  by  adopting  some  small 
concave  radius  for  a  metal  specimen,  say  10  mm.,  it  may  be  possible 
greatly  to  improve  the  metallographic  objective.  The  improvement 
may  possibly  take  the  form  of  a  greatly  simplified  construction, 
or  it  may  prove  a  means  of  increasing  the  N.A.  of  a  lens.  Person- 
ally, were  I  capable  of  it,  I  should  compute  it  first  of  all  unachro- 
matised  for  use  with  the  well-known  Mercuiy  line  5461,  a  powerful 
source  of  monochromatic  light  easily  isolated.  It  could,  if  it 
showed  promise,  be  further  computed  (all  fluorite  construction)  for 
the  powerful  ultra-violet  radiation  at  1851.  This  would  bring  the 
N.A.   for  a  2  mm.  lens  to  somewhere  about  3.5. 

(7)  I  have  suggested  the  above  (under  6)  as  a  possible  source  of  an 
improved  objective  for  metallurgical  purposes,  but  by  working  a 
specimen  to  a  radius,  it  is  possible  to  compensate  an  apochromatic 
or  other  objective  which  lacks  flatness  of  field,  by  applying  the  well- 
known  sphereometer  formula. 

Take  a.  ruled  stage  micrometer,  focus  the  centre  of  the  field,  and 
note  reading  on  micrometer  drum  of  the  fine  adjustment,  after  which 
take  the  reading  of  the  alteration  necessary  to  render  the  lines  at 
the  edge  of  the  field  sharp.  Then  if  S  is  the  semi-diameter  of  the 
circle  in  the  object  plane  represented  by  the  field  of  view,  we  can 
immediately  say  that  if  the  object  be  given  a  curvature  whose  radius 

the  field  of  view  will  be  in  focus  simultaneously  at  the  centre  and 
margin,  d  is,  of  course,  the  difference  between  the  two  readings  of 
the  fine  adjustment  drum. 


A  further  group  of  papers  dealing  with  various  general 
aspects  of  microscope  design  and  construction,  presented  by 
M.  Eugene  Schneider,  Professor  Alexander  Silverman, 
Dr.  R.  E.  Slade  and  Mr.  G.  I.  Higson,   and  Mr.  R.  J.  E. 

Hanson  were  taken  as  read. 


NOTES  ON  THE   FUTURE   OF   THE   MICROSCOPE. 
By  Eugene  Schneider. 

A.  Mechanical  Improvement. — It  is  very  difficult  to  make  precise 
suggestions  as  to  mechanical  improvement.  The  stands  of  the 
diti'erent  constructors  are  approaching  a  type,  wliich  in  a  measure, 
tends  to  become  classical.  The  initiative  will  in  this  development 
apparently  have  to  be  taken  by  the  scientists  and  industrials. 
They  will  point  out  to  the  designers  the  defects  of  their  instruments, 
and  will  indicate  the  modifications  which  technical  progress  requires. 
Yet  we  may  specify  one  detail  of  improvement  which  might  easily 
be  realised.  For  a  long  time  all  designers  have  adopted  the 
standard  ''  universal  screw  "  for  the  objectives.  Nothing  analogous 
has  yet  been  done  for  the  tubes  in  which  slide  the  eye-pieces  and 
condensers.  This  is  frequently  a  matter  of  inconvenience  to  the 
microscopist,  who  possesses  several  instruments  or  who  wishes  to  fit 
eye-pieces  and  condensers  of  different  styles  into  his  microscope  and 
stand. 

B.  Optical  Improvements,  a.  Eye-pieces. — As  regards  the  optical 
parts,  the  microscopist,  whatever  his  speciality,  has  all  the  necessary 
instruments  at  his  disposal.  At  the  outside,  one  might  wish  for 
eye-pieces  of  larger  field  for  dissection  or  for  the  study  of  larger 
slides.  That  however,  would  necessitate  a  larger  tube  diameter. 
The  field  of  the  actual  objectives  is,  moreover,  of  considerable  curvature 
already,  and  one  would  gain  little  by  trying  to  carry  the  observations 
to  parts  far  away  from  the  central  portion. 

h.  Objectives. — Abbe  has  shown  that  the  definition  of  the  micro- 
scope is  limited  by  diffraction  effects,  not  on  the  edge  of  the  objective, 
but  on  the  object.  He  has  established  that  the  definition — which  is 
frequently  styled  resolving  power — is  proportional  to  what  he  has 
termed  "  the  numerical  aperture,"  which  he  defined  by  the  expression : 
numerical  aperture  =  n  sin  u.  There  u  is  the  semi-angular  aperture, 
that  is  to  say,  half  of  the  apex  angle  of  the  cone  of  rays  passing 
through  the  object  and  admitted  into  the  objective  (Fig.  1),  while  n 
is  the  refractive  index  of  the  medium  surrounding  the  front  lens  of 
the  objective.  More  strictly  expressed,  n  is  the  index  of  the  least 
refractive  substance  which  is  found  between  the  object  and  the  second 
element  of  the  front  lens. 

But  n  is  a  function  of  the  wave-length.  In  order  to  increase  the 
numerical  aperture,  and  at  the  same  time  the  theoretical  range  of 
definition,  we  may  hence  increase  u,  or  increase  n,  or  decrease  A 

Dry  Systems  of  Objectives. — The  object  itself  is  immersed  in  a 
medium  of  some  refractive  power,  water,  glycerin,  Canada  balsam, 
etc.  But  a  cushion  of  air  is  always  left  between  the  cover-glass  and 
the  lens.  As  the  refractive  power  of  the  air  is  taken  as  unit  by 
opticians,  the  n  in  that  cushion  has  the  value  1,  and  hence  the 
numerical  aperature  is  equal  sin  u.  In  certain  dry  systems  of 
apochromatic  objectives,  the  numerical  aperture  attains  the  value  0.95. 

93 


94       NOTES  ON  THE  FUTUKE  OF  THE  MICROSCOPE  : 

which  corresponds  to  an  angular  aperature  of  144°  (compare  Fig.  2). 
To  go  further  in  this  respect  appears  to  be  impossible.  On  the  one 
hand  the  rays  would  no  longer  issue  from  the  point  lens ;  on  the 
other  hand,  the  most  oblique  rays  like  01.  (Fig.  2)  would  strike  the 
first  dioptric  plane  at  almost  grazing  incidence,  and  the  losses  by 
reflection  would  become  very  considerable. 

Immersion  Objectives — Keeping  the  angular  value  of  the  aperture 
constant,   the  immersion    increases    the    magnitude  of    n    (Fig.    3). 

Cedar  wood  oil  (n  =  1.52)  is  mostly  m.ade  use  of;  it  is  interposed 
between  the  glass  cover  and  the  front  lens.  The  numerical  aperture 
may  be  raised  to  1.40.  In  the  great  majority  of  cases  nothing  will 
be  gained  by  exceeding  this  limit.  Medical  men,  botanists,  histolo- 
gists  and  bacteriologists  study  their  specimens  when  immersed  in  water, 
glycerin,  salt  solutions  and,  more  rarely,  Canada  balsam.  Only 
in  this  last-mentioned  case  they  really  utilise  the  total  numerical 
aperture  of  their  objective.  For  instance,  when  the  object  is  placed 
in  water,    with  a   numerical    aperture    of    1.40,    we  have    numerical 


Fig.  I. 


Fig.  2. 


Fig.  3. 


aperture  utilised  =  1.33/1.52  of  total  aperture  =  1.22.  The  conclu- 
sion to  be  drawn  is  that,  taking  into  consideration  only  the  theo- 
retical definition  and  the  customary  practice,  one  may  say  that  the 
microscopic  definition  has  already  reached  its  limit.  We  have  not 
referred  to  the  variation  of  A  ;  that  point  will  be  discussed  when  we 
pass  to  microphotography. 

Special  Cases,  {a)  Diatoms. — For  diatoms  and  in  general  for  very 
fine  and  refractory  objects,  w^e  can  make  use  of  a  medium  and  an 
immersion  liquid  of  very  high  index.  For  the  silica  test  of  diatoms, 
e.f/.,  we  can  apply  a  solid  medium  of  relatively  high  melting-point, 
as  silica  will  stand  high  temperatures.  In  this  way  Zeiss  has  arrived 
at  an  objective  of  a  numerical  aperture  of  1.60  in  making  use  of  a 
dens©  flint  (for  slip  and  cover)  of  monobromonaphthalene  (immersion 
fluid),  and  a  solution  of  arsenic  sulphide  in  bromine  (as  medium). 
There  again  we  seem  to  have  reached  the  limit. 

(6)  Metallogrnphy. — In  metallography  the  immersion  liquid 
touches  the  object  directly  without  interposition  of  any  lamella.  In 
this  case  there  is  no  theoretical  reason  against  the  application  of 
extreme  numerical  apertures ;  unfortunately  the  illumination  problem 
becomes  particularly  difficult. 


EUGENE    SCHNEIDER  95 

Aberrations. — To  a  certain  numerical  aperture  corresponds  a  certain 
limit  of  definition.  But  this  limit  is  not  always  attained;  in  most 
cases  aberrations  distort  the  image,  and  the  microscope  proves  inferior 
to  what  one  might  hope  for. 

Spherical  Aberration. — This  aberration  can,  in  general,  fairly 
well  be  corrected  for  a  given  radiation.  The  properties  of  the  apla- 
natic  points  in  the  front  lens  facilitate  the  task  of  the  constructor  in 
a  singular  measure.  When  we  consider  rays  of  one  colour  only,  there 
is  little  more  to  be  achieved  from  this  point  of  view  with  well- 
•constructed  objectives. 

Sine  Condition. — This  condition — which  says  that,  central  aberra- 
tion having  been  corrected  for,  the  point  images  outside  the  axis 
are  exempt  from  coma — is  equally  satisfied  in  all  good  instruments. 

Curvature  of  Field. — As  regards  flatness,  everything,  or  nearly 
■everything,  remains  to  be  done.  The  field  of  better-class  objectives 
is  curved  to  a  deplorable  degree,  so  that  it  is  impossible  to  make  a 
useful  observation  on  the  borders  of  the  field  when  adjustment  is  made 
for  the  central  portion.  The  manipulation  of  the  micrometer  screw 
no  doubt  admits  of  rapid  focussing  and  facilitates  the  successive 
exploration  of  different  portions  of  the  field.  Yet  there  remains 
a  loss  of  time  and  a  certain  difficulty  "in  steadying  the  ensemble.  The 
defect  becomes  more  pronounced  in  photomicrographic  work,  though 
it  can  be  mitigated  by  the  aid  of  a  projection  lens,  suitably  corrected. 
Eut  one  must  not  indulge  in  illusions.  As  matters  are  and  w4th  the 
materials  at  the  disposal  of  the  optician,  it  is  impossible  to  assert  that 
w^e  shall  some  dav  succeed  in  completelv  correcting  for  curvature  of 
field. 

Chromatism. — Chromatism  is  never  eliminated,  though  it  may  be 
toned  down.  The  so-called  achromatic  objectives,  cut  out  of  the 
customary  glasses,  always  show  more  or  less  troublesome  coloured 
fringes  on  the  outlines  of  objects.  Much  has  been  written  about  the 
correction  for  n  radiations  by  the  aid  of  72-  glasses.  When  several 
conditions  are  written  for  achromatisation  it  can  easily  be  recognised 
that  the  roots  are  real  only  for  certain  values  of  the  co-efficients  of 
partial  dispersions  of  the  glasses.  In  the  very  simple  case  of  two 
glasses  we  may  write :  9i     ,     <^2    _    o 

or  in  another  form  ±1=  —^ 

where  (j^,  =  the  focal  power  of  the  convergent  lens,  cji.-,  =  the  focal 
power  of  the  divergent  lens,  v.-,  —  the  ratio  of  {?i2  —  1)  to  the  dis- 
persion  between  the  two  radiations  to  be  achromatised  : 

V2    =     —'j~     -  for  the  divergent  lens, 

«2      —    ^2 

and  j/j    =  the  same  ratio    — ^ ,,    for  the  convergent  one.     If  we 

rii  —  iti 
possessed  pairs  of  materials  such  that  the  ratio  were  independent 
of  the  chosen  interval,  we  might  with  two  glasses  achromatise 
all  the  radiations.  The  pupils  of  Abbe  have  worked  out 
this  problem.  The  Jena  glassworks  have  produced  materials 
which  satisfy  the  condition  defined  above  imperfectly,  but 
better     than     the     usual     glasses.       The     term     apochromatic     has 


96       NOTES  ON   THE   FUTURE   OF   THE   MICROSCOPE  : 

been  reserved  for  these  instruments.  Unfortunately  the  new  flints, 
the  telescope  flint,  boro-silicate  flint,  borate  flint,  etc.,  have  small 
dispersive  power.  The  lens  curvatures  have  to  be  exaggerated,  the 
zonal  aberrations  become  disturbing,  their  correction  is  troublesome, 
the  objectives  are  difficult  to  construct,  and,  in  spite  of  their  very- 
real  superiority  over  the  ordinary  achromatic  objectives,  the  price  of 
the  apochromatc  sometimes  makes  the  buyer  hesitate. 

In  our  opinion,  the  progress  of  the  microscope,  as  to  easy  and 
compact  correction  of  aberration,  will  depend  much  m,ore  upon  the 
work  of  the  glass-maker  than  upon  the  calculations  of  the  optician. 

We  can  now  form  a  clearer  opinion  concerning  the  interest  which 
extreme  magnifications  of  5,U00,  10,000  diameters  and  more  can 
present.  On  Abbe's  theory  M.  von  Rohr  has  fixed  the  smallest  dis- 
tance that  an  objective  of  aperture  1.40  can  resolve  at  0.00015  mm. 
The  eye  can  separate  about  1  in^h,  say  0.1  at  a  distance  of  33  mm. 
An  enlargement  of  700  diams.  enables  us  to  see  all  the  details  of  an 
object.  A  more  powerful  eye-piece  only  enlarges  the  image  without 
bringing  out  any  further  detail.  The  image  which  the  observer 
examines  may  be  less  perfect  than  the  normal  view;  on  the  other 
hand,  the  eye  is  fatigued  by  being  strained  to  its  maximum  effort. 
For  this  reason,  one  has  gone  up  to  enlargements  of  2,000  and  3,000 
diameters.  This  latter  magnification  is  excessive,  however,  and  we 
have  never  seen  it  applied  for  any  useful  purpose  in  microscopy.  In 
microphotography,  on  the  other  hand,  it  is  sometimes  serviceable  to 
magnify  10,000  times  and  to  use  even  higher  powers — for  instance, 
when  the  image  is  to  be'  exhibited  in  the  lecture  theatre,  or  when 
one  wishes  to  touch  up  a  proof  or  to  put  references  on  it. 

Photomicrography . — So  far  we  have  presumed  working  in  ordinary 
light.  As  the  photographic  plate  is  sensitive  to  ultra-violet  radiations, 
we  can  in  photomicrography  obtain  higher  definition  by  diminishing 
the  ^-  One  difficulty  creeps  up  at  once,  however:  most  of  the 
optical  materials  are  opaque  to  ultra-violet  radiations.  Rohr  built  up 
the  whole  optical  system  out  of  fused  quartz  ;  there  was  no  correction 
for  chromatism,  and  illumination  was  effected  b}"  one  of  the  aluminium 
radiations.  The  index  of  quartz  for  D  rays  is  n  =  1.54;  for  the  ray 
AIs2,  the  index  rises  to  1.69.  The  immersion  liquid  is  glycerin;  one 
is,  in  many  cases,  restricted  by  the  opacity  of  the  preparation  itself. 
In  these  respects  the  limit  seems  to  have  ah^eady  been  attained,  or 
nearly  been  attained. 

Condensers. — As  regards  condensers,  the  constructors  may  be  said 
to  have  preceded  the  microscopist.  For  delicate  researches,  non- 
corrected  condensers  are  frequently  used;  yet  they  should  be  achro- 
matic. The  theory  of  Abbe  assumes  that  the  object  is  placed  in  the 
image  of  the  luminous  source.  That  is,  with  ordinary  condensers, 
obviously  possible  only  for  one  single  radiation,  and  one  point  of  the 
field.  A  bad  illumination  is  so  disastrous  that,  even  at  the  present 
hour,  many  investigators  are  by  no  means  convinced  of  the  superiority 
of  the  apochromatic  instrument.  One  cannot  tell  them  often  enough 
that  this  defect  is  solely  due  to  the  insufficiency  of  their  condenser 
and  to  the  poor  choice  of  a  luminous  source.  Achromatic,  and  even 
apochromatic  condensers  are  in  existence,  and  a  deplorable  misjudg- 
ment  alone  has  prevented  their  general  use. 


EUGENE    SCHNEIDER  97 

M et alloy raphij. — In  metallography  the  objective  serves  as  con- 
denser. The  illumination  thus  obtained  may  be  perfect  (especially 
with  apochromatics),  but  the  lenses  are  more  or  less  marked,  which 
somewhat  impairs  th^eir  definition.  In  any  case,  it  is  the  illumina- 
tion which  will  have  to  be  studied  for  improvements.  The  problem 
appears  to  be  singularly  arduous,  and  a  long  time  will  no  doubt 
elapse  before  the  introduction  of  notable  perfections  can  be  hoped 
for. 

Coiichision. — In  a  general  way  mechanical  perfections  of  the 
microscope  will  naturally  result  from  progress  in  micrographic  tech- 
nics. From  the  optical  point  of  view  we  are  restricted,  at  least  in 
usual  practice,  by  the  impossibility  of  going  beyond  the  numerical 
aperture  of  1.40.  Better  correction  of  the  aberrations  and  especially 
of  the  field  curvature  seem  only  to  be  possible  by  the  creation  of  new 
optical  materials.  Finally,  the  use  of  ultra-violet  rays  admits  of  in- 
creasing the  definition  to  a  considerable  degree;  but  the  insufficient 
transparency  of  the  media  frequently  imposes  a  limit. 


A  NEW  MICROSCOPE  ILLUMINATOR. 

By  Alexander  Silverman 
(University  of  Pittsburgh,   U.S.A.) 

The  device  here  described  has  already  come  into  extensive  use 
in  the  United  States.  The  illuminator*  and  this  paper  are  submitted 
for  consideration  by  interested  British  societies. 

The'Lamy. — This  consists  of  a  quarter-inch  glass  tube  containing 
a  single  tungsten  filament.  The  tube  is  bent  into  a  circle  of  one- 
inch  inside  diameter,  and  one  and  one-half  inch  outside  diameter. 
It  is  made  of  colourless  or  blue  (daylight)  glass,  and  silvered,  so 
that  light  is  reflected  downward  from  the  circular  source  to  the 
object  being  examined.  The  possibility  of  silvering  the  entire  lamp 
and  cutting  a  lateral  line-slit  in  the  mirror  at  the  smallest  diameter 
is  under  consideration  to  determine  the  possibility  of  producing 
through  a  plane  of  light  a  sort  of  ultra-microscope  effect  for  the 
examination  of  bacteria. 

The  lamp  is  operated  at  0.9  ampere  and  13.5  volts  for  visual 
work,  and  1.06  amperes  and  18  volts  for  photographic  work.  Current 
from  an  ordinary  lighting  circuit  is  utilised,  and  controlled  through 
a  special  rheostat  (Fig.  1),  which  contains  a  push-button  swit^'h  for 
the  lower  current  and  a  spring-contact  for  the  higher  one. 

The  Holder. — An  automatically  adjustable  support  (Fig.  2), 
provided  with  three  iris-like  fingers,  controlled  by  springs,  is  attached 
concentrically  about  the  objective.  The  lamp  is  held  to  the  underside 
of  the  support  by  two  curved  prongs  and  a  perforated  spring  clip 
which  slips  over  the  exhaust  protuberance  of  the  lajiip.  The 
terminal  wires  from  the  lamp  are  attached  to  binding  posts  which 
are  so  constructed  that  they  will  also  receive  the  brass  pegs  attached 
to  the  cord  coming  from  the  rheostat.  These  pegs  may  be  inserted 
vertically  or  horizontally. 

For  general  observation  the  lower  portion  of  the  lamp  is  in  a 
plane  with  the  flat  face  of  the  objective  lens,  but  it  may  be  raised 
or  lowered  to  meet  the  needs  of  the  operator. 

Binocular  Microscopes. — While  the  lamp-holder  is  clamped 
directly  to  the  objective  on  monocular  (Fig.  1),  and  single-objective 
binocular  microscopes  when  16  mm.  or  higher  power  objectives  are 
employed,  a  stage  support  (Fig.  3)  is  provided  for  use  with  low 
power  objectives  and  the  Greenough  binocular  microscope.  Lateral 
adjustment    of    the    stage    adapter    centres    the    light    and    vertical 


*  U.S.  Patents  1,311,185,  1,311,186  and  1,257,287,  British  Patent 
125,187,  Caniadian  Patent  185,283,  Italian  Patent  48/485,  French  Patent 
489,304.     Other  foreign  patents  pending. 


9« 


BY  ALEXANDER  SILVERMAN  99 

adjustment    enables   the  operator  to   keep    the    lamp    at    a   constant 
distance  from  the  object  under  examination. 

The  Shutter. — A  shutter,  which  slips  inside  the  lamp  circle,  may- 
be placed  under  the  lamp  to  cut  off  the  light  from  one-half  of  the 
circle,  so  as  to  produce  oblique  illumination  where  this  is  desirable. 
Where  depth  without  shadows  is  desired  the  shutter  is  unnecessary. 

The  Absorjition  Disc. — This  is  a  dull  black  disc  for  covering 
highly  polished  surfaces,  so  that  only  the  small  portion  under  exam- 
ination is  exposed  to  the  light. 

Photomicroyrafhy . — For  photomicrographic  work  the  illuminator 
is  attached  as  already  described,  and  the  camera  employed  without 
lenses,  except  those  contained  in  the  objective  and  ocular.  For 
work  done  in  this  laboratory  the  camera  shutter  was  left  wide  open. 
16  and  32  mm.  objectives  were  employed  wdth  a  lOx  ocular.  As 
most  microscopes  are  now  equipped  with  vertical  illuminators,  the 
tube  of  such  microscopes  should  be  extended  about  16  mm.  when 
the  vertical  illuminator  is  removed  and  the  new  one  attached. 
It  is  also  desirable  to  use  a  Davis  shutter  in  conjunction  with  the 
objective.  Hammer  ortho  extra  rapid  plates  were  exposed  for  from 
10  to  40  seconds,  depending  on  the  nature  of  the  object  photographed. 

Low  Power  Work. — Excellent  results  have  been  obtained  with 
low  power  objectives  from  60  mm.  to  16  mm.  By  using  the  stage 
adapter  for  32  mm.  and  less  powerful  objectives,  it  is  possible  to 
place  the  lamp  about  one-quarter  of  an  inch  from  the  object  and 
obtain  beautiful  effects.  This  is  of  advantage  also  with  the  double 
objective  binocular  microscope. 

High  Power  Work. — The  illuminator  has  proven  satisfactory  for 
oil-immersion  work  with  a  1.8  mm.  objective  and  15  x  ocular  (1,425 
diameters).  The  markings  on  diatoms  and  structure  of  fine-grained 
alloys  show  clearly. 

liedf  of  the  Lamp. — To  allay  any  fear  concerning  the  heat 
radiated  or  conducted  from  the  lamp,  the  writer  begs  to  state  that 
in  his  laboratory  the  lamp  was  attached  to  various  objectives  and 
run  continuously  at  100  per  cent,  over-voltage  for  more  than  half 
an  hour  without  doing  any  harm  to  the  objectives.  Dr.  E.  M. 
Chamot,  of  Cornell  University,  conducted  an  independent  series  of 
experiments  in  which  he  drilled  a  hole  in  the  side  of  the  objective, 
inserting  a  small  pyrometer  tube  between  the  lenses.  He  burned 
<ihe  lamp  continuously  over  '  long  periods,  and  pronounced  it 
harmless. 

Advantages. — The  new  illuminator,  when  used  for  the  examina- 
tion of  opaque  objects  and  others  which  may  be  viewed  by  reflected 
light,  shows  a  greater  wealth  of  detail  than  is  obtainable  by  older 
methods. 


100  A   NEW  MICROSCOPE    ILLUMINATOR 

It  is  of  special  value  for  examining  objects  whicli  possess  light- 
absorbing  surfaces,  invisible  under  vertical  light,  which  are  beautiful 
under  the  new  light.  This  is  easily  verified  by  viewing  papers, 
textiles,  leaf  rusts,  insect  wings,  potato  mould,  etc. 

In  metals  and  alloys  it  shows  the  depth  of  penetration  of  the 
etching  medium,  contrast,  colour,  and  as  Director  Stratton,  of  the 
U.S.  Bureau  of  Standards,  has  pointed  out,  it  enables  one  to  see 
the  slag  content  of  pits  which  appear  black  under  vertical  light. 

The  new  illuminator  may  be  used  without  removing  the  vertical 
illuminator.  By  switching  the  respective  lights  on  in  turn,  valuable 
comparative  studies  may  be  made. 

The  illuminator,  when  attached  to  the  objective  or  to  a  special 
arm  of  the  stage  adapter,  may  be  lowered  into  hollow  objects,  such 
as  the  steel  test  dishes  used  in  the  enamel  industry,  or  vessels  used 
for  the  study  of  pond  life,  etc. 

The  illuminator  is  attached  to  the  microscope,  which  may  be 
moved  without  throwing  the  light  out  of  adjustment.  In  photo- 
graphing it  vibrates  with  the  microscope  should  the  latter  be  jarred. 

The  new  illuminator  eliminates  eye  strain.  The  intensity  of 
iiffht  which  reaches  the  eye  is  lower  than  that  produced  by  other 
methods.  There  is  no  polished  disc  to  interfere  with  the  vision,  and 
only  rays  reflected  by  the  object  examined  strike  the  retina. 

Acknowledgvients. — The  writer  desires  to  express  his  appreciation 
of  the  generous  co-operation  of  microscopists  who  have  experimented 
with  the  new  device.  He  desires  especially  to  thank  your  Mr.  S.  C. 
Akehurst  for  the  pleasure  of  his  company  and  valuable  suggestions 
made  during  his  visit  to  the  States,  and  for  his  kindness  in  presenting 
this  paper  before  the  members  of  your  society. 


Silverman.     1. 


^'^^ 


Fig  I, 


•P^HC 


Fig.  2. 


SUverman.— 2. 


Fig.  3. 


SOME  PROBLEMS  IN  HIGH  POWER  PHOTOMICROGRAPHY. 

By  R.  E.  Slade,  M.C,  D.Sc,  F.I.C.,  and  G.  t.  Higson,  M.Sc, 

A. I.e. 


In  an  investigation  of  photographic  emulsions  we  have  found  it 
necessary  to  take  photomicrographs,  using  the  greatest  resolving  power 
which  we  could  obtain.  In  our  attempts  to  overcome  various  difficul- 
ties inherent  in  different  forms  of  apparatus,  we  have  constructed  an 
apparatus,  which  we  believe  contains  some  novel  features. 

The  source  of  illumination  is  a  100  c.p.  "  Pointolite  "  lamp  con- 
tained in  a  light  tight  box,  a  light  tight  connection  being  made  between 
this  box  and  the  sub-stage  condenser  of  the  microscope,  which  is  used 
in  a  horizontal  position.  Although  this  box  is  not  ventilated  we  have 
not  been  troubled  by  heat  from  the  lamp.  No  optical  system  or  heat 
absorbing  cell  is  interposed  between  the  Pointolite  lamp  and  the  con- 
denser, but  an  arrangement  is  fitted  for  introducing  a  colour  screen  in 
this  position.     The  microscope  is  used  with  or  without  an  eye-piece  in 


^     ^.    Black  CAi.0  3o»\«.o 
/  \        V  Flap 


Action       of       V  \  6RftTioNL£Ss 


a  room  which  is  totally  dark,  and  the  image  is  projected  on  to  the 
plate,  placed  in  a  holder  about  one  foot  from  the  microscope,  no 
camera  being  used.  The  whole  apparatus  is  mounted  on  a  solid  block 
of  ash.  Focussing  is  done  direct  on  to  a  piece  of  white  card  placed  in 
the  plate  holder,  a  shutter  is  then  brought  down  just  in  front  of  the 
eye-piece  of  the  microscope,  a  plate  put  into  the  plate  holder,  and  the 
exposure  made. 

This  shutter,  which  is  mounted  quite  separately  from  the  base  of 
the  apparatus,  consists  of  a  roller  blind  shutter  release,  to  the  teat  of 
which  is  attached  "a  flap  of  black  card  (see  Fig.),  which  is  lifted  clear 
of  the  path  of  the  light  rays  by  pressing  the  bulb  of  the  release,  ex- 
posure thus  being  made  with  complete  absence  of  vibration. 


101 


102  HIGH    POWEK    PHOTOMICROGRAPHY 

In  order  to  surmount  the  difficulty  of  imperfect  achromatisation  ol 
the  lenses,  a  green  hlter  is  used  and  photographs  are  taken  on  process 
plates  sensitive  to  this  light.  In  all  apochromatic  lenses  there  is 
always  a  good  deal  of  curvature  of  field,  and  we  should  like  to  suggest 
that  for  photomicrographic  purposes  it  would  be  useful  to  have  a  lens 
without  any  colour  correction,  if  the  elimination  of  other  forms  of 
aberration  and  curvature  of  field  would  be  thereby  facilitated. 

The  illumination  used  is  always  what  is  usually  termed  critical, 
fehat  is  to  say,  the  light  source  is  in  focus  on  the  plate  at  the  same  time 
as  the  object  being  photographed,  this  being  rendered  possible  by  the 
uniformity  of  illumination  over  the  whole  of  the  hght  source.  In  this 
connection  we  should  like  to  put  forward  a  theory  of  the  well-known 
phenomenon  of  the  flooding  of  light  over  the  image  at  critical  illumina- 
tion when  the  aperture  of  the  condenser  is  fully  open.  \Ye  believe  that 
the  explanation  of  at  any  rate  a  part  of  this  is  that  the  miage  of  the 
light  source  which  lies  in  the  plane  of  the  object  is  not  an  infinitely 
thin  plane,  and  there  is  so  little  depth  of  focus  with  a  high  power 
objective  that  we  have  the  effect  of  the  image  of  a  bright  surface 
lying  just  in  front  or  just  behind  the  object  and  out  of  focus  on  the 
plate,  producing  the  so-called  flooding  effect.  If  we  cut  down  the 
aperture  of  the  condenser  we  eventually  use  only  light  which  is  almost 
parallel,  and  therefore  obtain  a  shadow  photograph  which  is  absolutely 
free  from  flooding.  If  we  cut  down  the  aperture  only  a  small  amount 
we  may  do  so  sufficiently  to  make  the  effect  of  flooding  negligible.  In 
support  of  this  we  may  mention  that  flooding  is  not  obtained  if  the 
image  of  the  light  source  is  very  much  out  of  focus.  In  the  "  Pointo- 
lite  "  lamp  the  curvature  of  the  light  source  will  contribute  to  this 
effect. 

In  some  of  our  earlier  work  we  used  an  achromatic  lens  between 
the  "  Pointolite  "  lamp  and  the  condenser,  but  it  was  the  light  source 
which  was  always  brought  to  a  focus  on  the  screen,  and  not  the  image 
of  a  diaphragm  over  the  lens,  as  is  sometimes  done.  This  lens  was 
used  to  magnify  the  image  of  the  light  source  so  that  a  larger  part  of 
the  object  could  be  illuminated,  but  the  same  effect  is  now  secured  by 
bringing  the  lamp  as  close  as  possible  to  the  condenser.  In  this  way 
we  can  illuminate  an  area  of  the  object,  which  is  a  little  larger  than  the 
flat  part  of  the  microscopic  field.  This  increases  the  ease  of  aligning 
the  optical  system,  and  moreover  slightly  increases  the  working  dis- 
tance of  the  condenser,   which,   however,   is  never  much  more  than 

1  mm. 

The  exposure  with  the  orthochromatic  process  plates  in  use,  with 
the  green  filter  and  a  magnification  up  to  2,000  diameters,  varies  from 

2  to  10  seconds.  In  this  connection  it  is  important  to  note  that  for 
all  work  requiring  the  greatest  resolution  process  plates  (i.e.,  plates 
with  a  hard  working  emulsion*)  must  be  used.  (Goldberg,  P.  J.,  52, 
302  (1912).) 

Laboratory  of  the  British  Photographic  Research  Association, 
Chemical  Department, 

University  College, 

Gower  Street. 


•■    In   the   December   number   of   the    Photographic   Journal    we  have 
shown  what  type  of  emulsion  is  required  to  make  a  good  process  plate. 


FATIGUE  FACTOES  INCIDENTAL  IN  THE  USE  OF 
CERTAIN  OPTICAL  INSTRUMENTS. 


By  Surgeon-Commander  R.   J.   E.   Hanson,  O.B.E., 
M.A.    (Cantab.),   R.N.V.R. 


Fatigue — when  it  exceeds  physiological  limits — is  one  of  the  most 
potent  drawbacks  to  industrial  efficiency. 

Moreover,  it  is  usually  of  no  sudden  onset  after  commencing  the 
use  of  optical  instrument  or  projection  apparatus,  but  is  rather  the 
result  of  summation  of  effect. 

The  causation  of  undue  fatigue  may  be  summarized  under  three 
headings : — 

Section  1. — Faulty  environment. 

(A)  Mai  Hygiene  of  the  home. 

(B)  Mai  Hygiene  of  the  workshop. 

(In  connection  with  "A,"  the  influence  of  day  and  continuation 
school  conditions  to  be  reckoned  with. 

Section  2. — Defects  in  the  Eye. 

(A)  Extrinsic,   e.g.,   Heterophoria. 

(B)  Intrinsic,  e.g.,  Ametropia,  etc. 

Section  3. — Central  and  Psychological. 
(Or  a  combination  of  any,  or  all,  the  above.) 

The  illuminating  engineer  is  at  work  to  secure  good  lighting 
conditions,  with  beneficial  results  in  many  directions.  Of  great 
importance  also  are  satisfactory  conditions  of  ventilation,  tem- 
perature and  hygrometry. 

In  this  short  communique,  I  desire  particularly  to  consider 
defects  in,  or  misuse  of,  the  muscular  mechanism  of  eye  movement, 
resulting  in  mal-orientation  of  the  eyes,  i.e..  Section  2  (A). 

In  the  use  of  the  bioscope  one  has  opportunity  to  study  the  fatigue 
resulting  from  flicker;  excessive  contrast  (defective  retinal  adapta- 
tion) ;*  inadequate  stimulation  of  the  retinal  periphery,  and  dis- 
proportion between  dimensions  and  illumination  of  screen  picture 
and  the  distance  therefrom  of  the  seat  occupied  by  the  observer. 

The  distance  between  audience  and  picture  screen  should  not  be 
less  than  3  x  D  (D  =  diagonal  measurement  of  the  picture). 

*  The  retinal  periphery  is  best  stimulated  by  means  of  clusters  of 
frosted  ruby  (Fig-,  i)  coloured  lamps  suspended  on  brackets  at  intervals 
along-side  the  auditorium. 

103 


104       FATIGUE   FACTORS   INCIDENTAL   IN   THE    USE 

If  an  observer  sits  in  the  "  auditorium  "  below  the  level  of  the 
centre  of  the  pictorial  field  of  action,  he  is  soon  fatigued,  and  brow- 
ache  and  discomfort  ensue,  for  observation  requires  him  to  extend 
his  head  slightly  from  the  "  primary  position,"  to  raise  his  eyelids 
and  rotate  his  eyes  upwards. 

If  now  he  reseats  himself  at  a  higher  level  ("  dress  circle  "  angle), 
these  factors  disappear,  for  now  his  head  is  in  the  "  primary 
position,"  or  slightly  flexed,  a  position  assumed  by  gravitation  and 
requiring  very  little  muscular  effort  for  its  maintenance. 

It  has  been  suggested  that  the  lower  seats  in  a  bioscope  theatre 
should   be   tilted  backwards  with   head   rests,  so  that  the  necessary 


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1600 

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Fig.  1. 


Diagram  to  indicate  that  the  periphery  of  the  retina  is  relatively  less  irrit- 
able to  impact  of  radiant  energ-y  causing-  sensation  of  RED  light,  compared 
with  the  FOVEA  (direct  vision),  observing  that  the  Ada-ptation  -phase  [Dark 
or  Light  adapted)  of  the  Retina  does  not  affect  the  Red  threshold.  The 
orange-yellow  and  blue  (A600-400)  require  the  same  number  of  energy 
anits  at  their  threshold  of  Perception,  and  are  affected  by  the  phase  of 
adaptation  of  the  Retina. 

slightly  extended  position  of  the  head  may  be  attained  without 
muscular  effort  and  so  avoid  mal-orientafion  of  the  head  and  eyes. 
However,  the  promiscuous  use  of  a  head-rest  in  a  place  of  public 
resort  is  not  a  feasible  or  pleasant  proposition. 


Fatigue  factors,  in  connection  with  the  observer's  posture  in 
using  the  microscope,  are  also  present,  and  for  him  no  facility  is 
provided  for  resting  his  head  and  neck  muscles,  and  insufficient  atten- 
tion is  paid  to  the  angle  formed  between  the  ocular  and  the  vertical 
plane  of  the  observer's  head. 


OF  CERTAIN  OPTICAL  INSTRUMENTS 


105 


In  order  to  avoid  mal-orientation  and  resulting  fatigue,  it  is 
necessary  to  provide  the  observer  with  a  working  bench  of  adequate 
height,  correlated  height  and  'position  of  chair,  suited  to  the  physique 
of  each  observer. 


Fig.  2. 


Dyoptikon   (Pivotal)   Head-Rest 

(Universal  Letters  Patent). 

Scale  -One-Half. 


106        FATIGUE  FACTORS   IN  OPTICAL  INSTRUMENTS 

I  have  put  in  as  an  exhibit  a  working  model  of  a  headpiece 
attachable  to  any  standard  tube  microscope  without  necessitating  any 
structural  alteration  in  existing  patterns,  although  it  is  intended  to 
arrange  a  bracket  with  attachment  at  or  below  the  trunnion,  in 
any  new  pattern  microscope  available.  Diagram  and  models  illus- 
trating application  of  this  dyoptikon  head-rest  (eye-piece)  to  tele- 
scopes, etc.,  are  also  shown.      (Fig.   2.) 

I  am  also  showing,  by  permission  of  Professor  A.  D.  Waller, 
F.R.S.,  his  early  ajid  original  negatives  showing  the  electrical 
response  of  retina  to  impacts  of  radiant  energy  of  short  duration; 
also  solution  of  so-called  "  Visual  purple  "  which  exists  in  colloidal 
solution  bathing  the  receptor  organ  (retinal  cones  and  rods),  a 
photochemical  substance  which  under  the  above  circumstances  of 
external  stimuli  presents  a  balanced  reversible  reaction,  and  has  been 
shown  to  flow  into  the  central  fovea  where  no  rods  exist.  Its 
"  sensitivity  "  is  in  accordance  with  Planck's  minimum  quantum  of 
energy,  and  has  been  shown  by  Victor  Henri  to  be  several  thousand 
times  more  sensitive  to  light  than  the  most  sensitive  photographic 
plate,  on  rapid  exposure.  Spectroscopically,  "  Visual  purple  "  shows 
no  absorption  bands. 


A  group  of  papers  by  Dr.  M.  W.  Travcrs, 
F.R.S.,  Dr.  W.  E.  S.  Turner,  Mr.  Robert  Mond,  and 
Mr.  F.  Twyman,  dealt  with  Optical  Glass. 

GLASS   FOR   OPTICAL   PURPOSES. 
By  Morris  W.  Travers,  D.Sc,  F.R.S. 

I  have  beeii  associated  witli  the  glass  industry  since  the  outbreak 
of  war,  but  the  manufacture  of  optical  glass  in  this  country  has 
been  a  matter  of  secrecy,  and  only  officials  have  been  admitted  to 
the  works,  so  that  persons  like  myself  can  know  only  of  what  has 
been  done  indirectly  and  by  rumour,  British  scientific  literature 
contains  one  or  two  papers,  indirectly  connected  with  the  subject, 
and  the  public  and  semi-scientific  press  contains  only  references  to 
claims  to  discoveries  of  "  German  secrets  "  by  British  scientists — 
and  denials  that  there  were  any  secrets  to  discover.  I  hope  that 
the  claims  are  of  a  more  substantial  character  than  those  put  forward 
in  connection  with  scientific  glassware. 

During  the  past  autumn  I  made  a  tour  of  America,  where  I 
visited  several  of  the  new  optical  glass  plants,  to  which  I  was  freely 
admitted,  and  met  many  of  the  men  who  had  been  engaged  in 
the  development  of  the  industry.  During  the  early  years  of  the 
war  the  manufacture  of  optical  glass  had  been  carried  on  in  a 
rather  desultory  fashion,  but  in  April,  1917,  American  industry 
was  suddenly  called  upon  lb  meet  an  enormous  demand  for  optical 
glass.  It  might  have  been  thought  that  America  would  have  made 
use  of  the  information  gathered  in  this  country,  but  an  American 
scientist  who  took  a  leading  part  in  developing  the  industry  told 
me  that  this  was  not  the  case,  for  "  we  understood  that  your  Govern- 
ment had  a  lot  of  information  on  the  subject  of  optical  glass,  but 
we  could  get  nothing  out  of  them  at  all." 

America  was,  however,  in  a  very  advantageous  position  from 
which  to  attack  the  problem.  In  the  first  place  there  were  ample 
funds  for  research,  administered  by  a  thoroughly  scientific  body^ 
the  National  Research  Council,  and  not  by  a  Government  Depart- 
ment, scientific  only  in  name.  In  the  second  place  there  already 
existed  the  organisation  of  the  Geophysical  Laboratory  of  the 
Carnegie  Institution.  Of  the  work  of  this  institution  the  Report 
of  the  Director  for  the^  year  1918  speaks  as  follows: — "  Suffice  it 
to  say  that  with  a  group  of  20  scientifically  trained  men,  all  trained 
in  handling  silicate  solutions  at  temperatures  required  for  the  making 
of  glass,  and  familiar  with  the  control  of  most  of  the  important 
factors  in  the  problem,  it  proved  practicable  to  make  rapid  pro- 
gress, and  in  June  following,  after  two  months  of  concentrated 
effort,  the  gross  production  of  glass  by  a  leading  manufacturing 
firm  had  increased  from  15,000  to  28,000  pounds  per  month,  and 
in  quality  had  improved  to  such  an  extent  that  rejections  by  Govern- 
ment inspectors  became  comparatively  rare."  The  results  are  really 
expressed  in  the  last  sixteen  words  of  the  quotation. 


108  GLASS    FOR    OPTICAL    PURPOSES 

The  rapid  progress  made  in  America  was  largely  due  to  the  fact 
that  the  scientists  of  the  Geophysical  Laboratory,  and  of  the  Bureau 
of  Standards,  were  not  content  to  sit  on  High  Olympus  in  the  suburbs 
of  Washington,  but  did  their  work  in  the  manufacturing  plantsy 
from  which  the  results  of  their  researches  are  issued.  Thus  science 
and  industry  co-operated  in  the  closest  possible  manner,  with  results 
which  speak  for  themselves;  for  not  only  were  the  practical  results 
aimed  at  actually  achieved,  but  a  very  large  volume  of  scientific 
research  was  carried  out,  much  of  which  has  already  been  published 
in  American  scientific  literature,  while  much  more  awaits  publication. 

We  have  certainly  done  good  practical  work  in  a  limited  field 
in  this  country,  and  nothing  pleased  me  more  than  to  hear  the 
quality  of  some  of  our  British  scientific  glass  praised  in  America. 
The  greater  credit  to  those  to  whom  the  results  are  due,  who  have 
worked,  as  Englishmen  often  work  best,  in  face  of  difficulties.  Given 
the  opportunity,  the  British  scientist  is  equal  to  any  in  knowledge, 
and  superior  to  most  in  grit;  but  the  policy  adopted  by  our  Govern- 
ment Departments  of  attempting  to  monopolise  science,  and  draw 
a  dividing  line  between  science  in  the  university  laboratory  and 
science  in  the  works,  is  fatal  both  to  scientific  and  industrial 
progress. 


GLASS  FOR  OPTICAL  PURPOSES. 

By  W.  E.   S.   Turner,  D.Sc,  M.Sc, 
Of  the  Department  of  Glass  Technology,  Sheffield  LTniversity. 


Ifc  is  with  great  reluctance  that  I  find  I  must  forgo  the  pleasure 
of  being  present  at  the  Symposium  on  Wednesday  next. 

I  am  glad  to  know  that  some  members  of  the  Society  of  Glass 
Technology  will  be  present  and  take  part  in  the  proceedings.  The 
fine  array  of  papers  is  a  tribute  to  the  great  efforts  Sir  Robert  Hadfield 
has  made  to  direct  the  attention  of  scientific  men  to  the  importance 
of  encouraging  the  production  of  all-British  optical  instruments. 

Amongst  the  large  number  of  papers,  however,  I  do  not  find  a 
single  one  dealing  with  the  manufacture  of  optical  glass.  It  is,  in 
my  opinion,  unfortunati^  that  there  should  not  be  as  free  and  ready 
a  discussion  of  this  subject  as  had  taken  place  in  America  in  these 
past  three  years. 

I  should  like  to  make  some  remarks  of  a  very  general  character 
to  indicate  to  makers  and  users  of  instruments  the  position  in  which 
optical  glass  makers  frequently  find  themselves.  There  is,  in  my 
mind,  not  the  slightest  doubt  that  we  can  produce  in  this  country  all 
the  types  of  glass  requisite  for  microscopes  and  other  optical  instru- 
ments. The  long  experience  of  Messrs.  Chance  Bros.,  and  the  splendid 
achievements  of  the  new  Derby  Crown  Glass  Co.  undoubtedly  demon- 
state  this. 

The  amount  of  optical  glass  in  any  one  instrument  is,  as  a  rule, 
quite  small,  whilst  for  the  instruments  of  high  precision,  even  the 
total  amount  of  glass  called  for  by  manufacturers  is  very  small.  The 
glass  maker,  however,  knows  that  in  order  to  ensure  homogeneity, 
freedom  from  striae,  etc.,  from  the  glass,  he  must  make  a  melt  on  a 
considerable  scale.  Further,  some  designers  of  optical  instruments 
will  call  for  a  new  glass  of  special  properties,  may  be,  for  example, 
one  which  is  successful  in  eliminating  light  rays  between  certain  wave- 
lengths. The  production  of  such  a  glass  calls  for  considerable  research 
on  the  part  of  the  glass  manufacturer,  and  he  usually  cannot  expect 
to  sell  but  a  very  small  quantity  when  produced,  whilst  the  instru- 
ment maker  is  not  prepared  to  cover  the  cost.  Such  a  demand  cannot 
always  be  met  by  the  glass  manufacturer;  it  is  in  no  sense  a  com- 
mercial proposition.  For  some  reason,  connected  probably  with,  the 
early  days  of  German  competition,  the  manufacture  even  of  the  well- 
known  varieties  of  optical  glass  has  never  been  remunerative,  although 
with  the  recent  American  products  the  prices,  I  believe,  have  had  a 
more  reasonable  relation  to  the  cost.  One  American  manufacturer 
stated  that  he  was  prepared  to  continue  the  manufacture  of  optical 
glass  if  the  loss  was  not  greater  than  10,000  dollars  per  annum, 
although  he  was  hoping,  eventually,  the  factory  costs  might  be 
balanced  by  income. 


110  GLASS    FOR    OPTICAL    PURPOSES 

There  is  an  obvious  remedy  for  the  unremunerative  rates  for 
optical  glass,  namely,  that  instrument  makers  should  be  prepared  to 
pay  prices  sufficient  to  make  the  industry  financially  sound.  There 
is  also  a  means  by  which  special  glasses,  required  only  in  small 
quantities,  may  be  made  without  asking  glass  manufacturers  to  go 
to  unnecessary  trouble  and  expense.  It  lies  in  the  use  of  the  joint 
resources  of  the  laboratories  of  the  British  Optical  Instrument  Manu- 
facturers' Research  Association,  under  Sir  Herbert  Jackson,  and  of 
the  Department  of  Glass  Technology  in  the  University  of  Sheffield. 

The  last-named  Institution  has  been  equipped  in  such  a  manner 
as  to  be  admirably  adapted  for  making  special  glasses  in  smaller 
quantities  than  the  manufacturer  can  consider  worth  while,  and 
meltings  up  to  two  cwt.  in  size  can  be  undertaken.  Where  it  is  a 
matter  of  importance  that  a  special  glass  shall  be  worked  out,  I  urge 
most  strongly  that  the  joint  resources  of  the  two  laboratories  be 
employed. 

In  regard  to  crystals  of  calcium  fluoride,  I  heartily  concur  with 
Sir  Robert  Hadfield's  views  that  it  would  be  strange  if  the  mineral 
resources  of  the  Empire  could  not  furnish  our  requirements.  Some 
time  ago  I  received  from  a  merchant,  Mr.  B.  Moss,  21,  King  Street, 
Covent  Garden,  London,  W.C.,  a  beautiful  specimen  of  crystalline 
calcium  fluoride  from  a  mine  in  the  neighbourhood  of  Johannesburg. 
I  am  forwarding  specimens  of  this  to  you.  When  I  say  that  the 
specimen  was  sent  with  the  object  of  obtaining  a  market  amongst 
manufacturers  of  common  glass  articles  only,  it  will  be  agreed  that 
the  source  may  be  worth  further  exploitation  for  optical  specimens. 

The  manufacture  of  optical  glass  in  America,  taken  up  only 
during  the  war,  is  still  a  long  way  behind  ours  in  output  and  variety. 
Recently  I  was  able  to  visit  practically  all  of  the  war  plants.  The 
number  of  types  of  glass  made  so  far  is  limited,  and  in  the  last  few 
months  all  the  plants  except  that  of  the  Spencer  Lens  Co.,  at 
Hamburg,  New  York,  and  the  new  experimental  plant  at  the  Bureau 
of  Standards,  Washington,  have  closed  down.  For  a  long  time, 
therefore,  there  should  be  in  America  an  important  market  for  optical 
glass  made  in  this  country. 


NOTE    ON    FLUORITE. 
By  Robert  L.   Mond. 

Our  Chairman,  Sir  Robert  Hadfield,  has  asked  me  to  ascertain 
whether  crystals  of  fluorite  suitable  for  optical  purposes,  of  which 
there  is  a  great  shortage,  are  obtainable  in  the  Dominion  of  Canada. 

I  at  once  got  into  communication  with  my  friend,  Mr.  C.  V. 
Corless,  the  General  Manager  of  our  nickel  mines  in  Canada,  who 
succeeded  in  ascertaining  for  me  the  following  facts. 

Crystallised  fluorite  is  exceedingly  scarce  in  Canadian  deposits, 
and  there  only  appears  to  be  one  property  of  any  promise  in  Canada. 
Mr.  Gavin  M.  Wallbridge,  owner  of  the  Wallbridge  Mine,  Madoc, 
Ontario,  has  sent  me  one  crystal,  which  I  herewith  submit.  In 
this  mine  there  are  two  veins,  which  contain  some  beautiful,  pure 
white  crystals;  he  has  supplied  some  of  these  crystals  to  Messrs. 
Bausch  and  Lomb,  of  New  York,  The  crystal  he  has  sent  me  he 
states  to  be  from  the  second  vein.  This  property  is  flooded  at 
the  present  moment,  and  he  cannot  work  it  until  next  Spring.  If 
material  slightly  off  colour  would  be  suitable,  he  would  be  in  a 
position  to  supply  straight  away,  but  the  clear  white  he  could  not 
supply  before  next  Spring. 

The  vein  is  a  closely  packed  one,  tight  from  wall  to  wall,  and 
in  using  dynamite  to  loosen  the  ore,  all  the  crystals  within  a  few 
feet  of  the  shot  hole  are  shattered.  He  is  sometimes  able,  however, 
to  locate  a  rough  hole  after  mucking  operations,  and  with  great 
care  and  a  lot  of  time  he  is  able  to  save  some  beautiful  specimens. 
He  continues  to  state  that  the  price  which  he  obtained  last  year 
was  so  much  less  than  the  value  stated  by  the  Bulletin  issued  in 
Washington  that  he  became  disgusted,  and  did  not  bother  to  make 
any  attempt  to  save  the  crystals. 

He  further  states  that  he  has  not  an  expert  there  to  place  a 
value  on  the  crystals,  and,  in  consequence,  must  trust  to  the  business 
honesty  of  the  consignee.  He  has  no  doubt  that  a  British  firm 
would  "  play  the  game."  He  is  much  interested  in  the  crystals  end 
of  the  business,  and  would  be  very  pleased  to  hear  if  the  slightly 
off -coloured  crystals  would  be  of  any  use,  and  what  would  be  the 
smallest  size  worth  submitting. 

I  am  also  in  receipt  of  a  letter  from  Mr.  Thos.  Gibson,  Deputy 
Minister  of  Mines,  who  has  interviewed  the  brother  of  Mr.  Wall- 
bridge.  He  informs  us  that  the  deposit  is  very  limited,  and  that 
the  deposit  not  now  being  worked  was  much  more  promising.  Mr. 
Gibson's  impression  is  that  we  cannot  count  upon  the  Madoc  Mine 
furnishing  any  commercial  supply  of  the  special  type  of  fluorite, 
unless  the  demand  is  extremely  small. 

The  material  is  undoubtedly  fluorite,  and  I  have  submitted  the 
sample  to  Messrs.  Swift  and  Sons,  who  propose  cutting  a  lens  or 
prism  from  it  to  ascertain  its  optical  properties. 

Although  the  actual  specimen  is  a  large  crystal,  there  are  only 
relatively  small  portions  of  it  which  appear  to  me  suitable  for 
optical  use.  As  this  crystal  was  sent  to  me  from  Canada  in  a  canvas 
bag,  it  may  have  suffered  crushing  in  transit. 

I  regret  I  have  not  been  more  successful  in  obtaining  information 
as  regards  the  occurrence  of  this  mineral. 


THE  ANNEALING  OF  GLASS. 

By  F.  Twyman. 

Although  owing  to  the  small  sizes  of  microscope  lenses,  and  the  fact 
that  they  are  usually  cut  out  of  comparatively  massive  pieces  of  glass, 
want  of  annealing  is  very  unlikely  to  cause  the  microscope  maker  any 
trouble,  yet  a  few  remarks  relative  to  the  principles  underlying  the 
annealing  of  optical  glass  may  be  of  interest,  if  for  no  other  reason  than 
that  the  same  principles  underlie  the  efficient  moulding  of  glass  (or 
indeed  of  other  materials),  and  there  is  no  reason  why  an  appreciable 
saving  in  the  cost  of  manufacture  of  microscope  objectives  might 
not  be  effected  by  high  quality  moulding. 

When  the  Eesearch  Laboratory  of  Adam  Hilger,  Limited,  took  up 
the  question  of  annealing  glass  in  1915,  we  were  unable  to  discover  that 
any  research  work  of  a  fundamental  character  had  been  done  on  the 
subject.  We  were  unable  to  find  even  a  clear  presentation  of  the 
cause  of  faulty  annealing.  For  various  reasons  we  have  not  published 
a  full  account  of  the  work,  but  the  principles  involved  and  some 
of  the  results  as  applied  to  glassware  will  be  found  sufficiently  fully 
described  in  a  paper  read  before  the  Society  of  Glass  Technology  in 
1917.  C  The  Annealing  of  Glass,"  by  F.  Twyman.  Trans.  Soc. 
Glass  Technology,  1917.     I.  61,  e^  seq.) 

The  phrase  "  badly  annealed  "  when  applied  to  glassware  implies 
the  presence  of  internal  stress. 

When  glass  is  in  a  definitely  molten  condition  there  can  be,  of  course, 
no  permanent  internal  stress.  Moreover,  it  can  be  shown,  by  keeping 
a  suitable  glass  object  under  observation  in  a  tube  furnace,  that  even 
when  the  glass  is  cool  enough  to  be  practically  solid  under  such  stresses 
as  are  occasioned  by  its  own  weight,  it  may  yet  be  mobile  enough  for 
severe  internal  stresses  to  disappear  in  a  few  minutes.  On  the  other 
hand,  at  ordinary  air  temperatures  glass  is  almost  (though  not  quite) 
perfectly  elastic. 

But  between  this  high  temperature,  w^iere  the  glass  is  so  mobile  that 
internal  stresses  are  evanescent  in,  at  most,  a  few  seconds,  and  the 
low  temperatures,  where  the  glass  behaves  as  an  elastic  solid,  is  a  region 
where  internal  stresses  take,  say,  a  minute,  or  an  hour,  or  a  few 
hours,  to  die  out.  It  is  this  range  of  temperature  which  is  important 
in  annealing,  and  an  accurate  knowledge  of  the  mechanical  properties 
of  the  glass  throughout  this  region  is  necessary  if  we  are  to  attain  any 
specified  perfection  of  annealing  in  a  minimum  time,  and  without  dis- 
tortion of  the  articles.     This  region  I  call  the  annealing  range. 

If  it  were  possible  to  cool  any  glass  object  from  the  high  temperature 
down  to  ordinary  air  temperature  in  such  a  way  that  the  temperature 
remained  uniform  throughout  the  mass,  then  no  matter  how  fast  the 
cooling  the  glass  would  be  well  annealed. 

What  actually  happens  is  that  differences  of  temperature  exist 
while  the  glass  is  cooling.  The  stresses  so  caused  are  transient,  so 
long  as  the  glass  is  within  the  annealing  range  ;  but  when  eventually 
it  becomes  cold  and  the  temperature  uniform,  there  are  present 
permanent  stresses  depending  on  the  variations  of  temperature 
throughout  the  mass  which  existed  while  the  glass  was  cooling. 


F.     TWYMAN  113 

To  anneal  glass,  then,  it  is  necessary  to  keep  it  within  the  annealing 
range  till  the  stresses  have  died  out,  and  then  to  cool  it  with  sufficient 
slowness.  No  kind  of  heat  treatment  which  does  not  raise  a  badly 
annealed  sample  of  glass  to  within  this  range  will  greatly  affect  its 
condition  of  internal  stress,  w^hether  for  good  or  ill,  in  any  reasonable 
time. 

The  method  developed  in  our  laboratory  for  determining  the 
annealing  temperature  will  be  found  in  the  paper  cited  above.  The 
steps  in  the  argument  may  be  briefly  summarised. 

The  degree  of  annealing  to  be  attained,  and  the  time  in  which  it 
is  to  be  accomplished  must  be  defined.  For  glassware  we  have  laid 
down  the  condition  that  at  the  annealing  temperature  95  per  cent, 
of  the  original  stress  must  disappear  in  three  minutes.  For  optical 
glass  appropriately  modified  stipulations  are  adopted. 

The  case  of  the  disappearance  of  stress  in  a  viscous  body  was  con- 
sidered by  Maxwell,*  who  gave  an  exponential  expression  applicable 
to  such  cases  connecting  stress  with  time,  thus 

F-ESe-^ 
where  S  is  a  distortion  or  strain  of  some  kind  produced  in  the  body 

by  displacement,  F  is  the  stress  thus  excited,  E  is  the  co-efficient 
of  elasticity  for  that  particular  kind  of  strain,  t  the  time,  and 
T  a  time  named  by  Maxwell  the  time  of  relaxation,  which  depends 
on  the  nature  of  the  body. 

The  product  ET  he  calls  the  co-efficient  of  viscosity,  since  in  the 
case  of  steady  progressive  strain  or  distortion  produced  by  constant 
stress  the  rate  of  strain  multiplied  by  this  product  gives  the  stress. 

It  is  obvious,  then,  that  by  defining  the  annealing  temperature 
in  the  way  we  do,  we  have  at  the  same  time  defined  a  viscosity. 
All  we  have  to  do,  then,  is  to  find  the  temperature  at  which  the 
glass  has  the  viscosity  so  defined,  and  we  have  the  annealing  tem- 
perature. 

For  details  of  apparatus  and  method  the  paper  mentioned  above 
must  be  referred  to;  but  one  point  may  be  of  interest. 

It  was  found  by  us  that  in  the  neighbourhood  of  the  annealing 
range  most  glasses  examined  double  in  mobility  for  every  8°  C  rise 
of  temperature,  approximately.  If  then  an  attempt  were  made  to 
anneal  at  500°  C.  a  glass  whose  annealing  temperature  (as  defined 
above)  is  580°  C,  the  glass  would  require  to  be  left  one  thousand 
times  as  long  in  the  former  case  as  in  the  latter. 

The  Eesearch  Laboratory, 
Adam  Hilger,  Ltd. 

*  Phil.   Mag.   S4,    Vol.  35,  Feb.,   1868,   p.    i2g. 


APPLICATIONS  OF   THE    MICROSCOPE. 

The  following  papers  and  communications  dealt  with 
recent  developments  in  the  applications  of  the  microscope, 
particularly  in  industry. 

This  portion  of  the  Symposium  was  introduced  by  the 
presentation  of  a  paper  on  "  The  Great  Work  of  Sorby,"  by 
Sir  Robert  Hadfield,  Bart.,  F.R.S. 

THE    GREAT    WORK    OF    SORBY. 

Bi/  the  President   of  the  Faraday  Society 
(Sir  Robert  Hadfield,  Bart.,  D.Sc,  D.Met.,  F.R.S.). 


Early  Work ;  Researches  on  Metals ;  Researches  on  Rock  Sections  ; 
Work  on  Meteorites  ;  Application  of  Sorby's  Work  to  Metallurgy. 


In  the  First  Sorby  Lecture  "  On  Some  Structural  Analogies  between 
Igneous  Rocks  and  Metals,"  read  before  the  Sheffield  Society  of 
Engineers  and  Metallurgists  in  February,  1914,  Professor  W.  G. 
Fearnsides,  M.A.,  F.G.S.,  rightly  said  that  the  audience  had  met  to- 
gether to  honour  the  father  of  Modern  Petrography,  tliat  citizen  of 
Sheffield,  Henry  Clifton  Sorby.  Professor  Fearnsides  has  dealt  with 
the  subject  in  such  an  excellent  manner  and  given  so  much  valuable 
information  in  his  lecture  that  I  quote  him  very  fully. 

Early  Work. — Sorby 's  earliest  Research  Work  was  in  1849  when  he 
prepareii  the  first  rock  slice  ever  made,  and  his  first  microscopical  study 
of  igneous  rocks  was  presented  in  his  historic  Paper  read  before  the  Geo- 
logical Society  of  London  on  December  2nd,  1857.  His  attempts  were 
received  almost  with  derision,  some  of  the  Members  present  saying 
that  he  was  drawing  largely  on  their  credulity.  Later  he  was  thoroughly 
avenged  by  the  Geologists  of  all  Nations  who  assembled  to  celebrate 
the  Centenary  of  the  Geological  Society  of  London  when  Sorby  on  the 
results  which  were  formerly  derided  was  acknowledged  and  acclaimed 
by  them  to  be  the  founder  of  modern  Petrography, 

Researches  on  Metals. — Sorby  began  his  work  on  Metals  in  1863  and 
lectured  about  it  in  Sheffield  before  the  Literary  and  Philosophical 
Society  in  February,  1864  ("On  a  New  Method  of  Illustrating  the 
Structure  of  Various  Kinds  of  '  Blister  Steel '  by  Nature  Printing," 
Sheffield  Lit.  &  Phil.  Soc,  1864).  Unfortunately  there  is  no  trace  of 
this  in  the  Proceedings.       My  own  impression  is  that  this  Paper  was 

114 


SIR    ROBERT    HADFIELD,     BART.  115 

one  which  was  read  before  the  National  Science  Section  of  that 
Society,  but  no  copy  was  kept  of  it.  When  residing  chiefly  in 
Sheffield  I  was  a  Member  of  this  Section,  often  meeting  Dr.  Sorby 
there.     It  is  now  no  longer  in  existence. 

Later  on  Sorby  communicated  his  results  at  the  Bath  Meeting  of 
the  British  Association  ("  On  Microscopical  Photographs  of  Various 
kinds  of  Iron  and  Steel,"  B.A.  Report,  1864,  Pt.  II,  page  189).  In  this 
Paper  the  Author  briefly  explained  how  sections  of  Iron  and  Steel 
might  be  prepared  for  the  Microscope  so  as  to  exhibit  their  structure 
to  a  perfection  that  left  little  to  be  desired.  He  also  exhibited 
a  series  of  photographs  taken  by  Mr.  Charles  Hoole  illustrating 
the  various  stages  in  the  manufacture  of  Iron  and  Steel  and  describing 
the  structures  which  they  presented.  They  showed  various  mixtures 
of  Iron,  of  two  or  three  well-defined  compounds  of  Iron  and  Carbon, 
of  Graphite,  and  of  Slag  ;  and  these,  being  present  in  different  propor- 
tions and  arranged  in  various  manners,  gave  rise  to  a  large  number 
of  varieties  of  Iron  and  Steel  differing  by  well-marked  and  very  striking 
peculiarities  of  structure. 

For  22  years  the  observations  attracted  little  or  no  attention  and 
when  in  1877  Professor  Martens,  Berlin,  and  later  M.  Osmond  and  M. 
Le  Chatelier,  Paris,  began  to  study  metals  with  the  Microscope  they 
had  to  develop  independently  and  anew  the  craft  which  Sorby  had 
invented  many  years  before.  Sorby  lectured  on  "  The  Microscopical 
Structure  of  Iron  and  Steel  "  at  Firth  College,  Sheffield,  in  October, 
1882,  and  stated  that  in  view  of  the  knowledge  of  fresh  facts  he  had 
re-examined  the  whole  of  his  specimens  with  improved  Apparatus. 
In  1885  by  the  use  of  Lenses  of  high  resolving  power  and  large 
magnification  he  first  discovered  the  true  composite  nature  of  the 
"  Pearly  Constituent  "  of  steel  as  an  aggregate  of  parallel  plates, 
which  discovery  may  be  reckoned  the  crowning  achievement  of  his 
microscopical  research.  Sorby  announced  this  discovery  to  the  Iron 
and  Steel  Institute  in  1886,  "  On  the  Application  of  Very  High  Powers 
to  the  Study  of  Microscopical  Structure  of  Steel,"  Journal  of  the  Iron 
and  Steel  Institute,  Vol.  I,  1886,  pages  140  to  144.  Subsequently 
he  presented  to  the  same  Institution  his  great  Paper  "  The  Micro- 
scopical Structure  of  Iron  and  Steel,"  giving  a  full  account  of  his 
methods  and  the  results  he  had  obtained.  (Journal  I.S.I. ,  Vol.  I, 
1887,  pages  255  to  288).  These  Papers  proved  to  be  the  signal  for 
great  activity  in  the  field  which  he  had  so  brilliantly  started  to  explore, 
but  it  was  really  far  back  in  the  'sixties  that  Sorby  originated 
the  Science  of  Metallography.  His  work  at  this  period  gave  cause 
for  an  American  writer  in  1900  to  say  of  him  (in  the  "  Metallographist" 
of  April,  1900,  Boston,  U.S.A.):  "  Whatever  has  been  accomplished 
since  in  microscopic  metallography  has  been  done  by  following  in  his 
footsteps.     To  Dr.  Sorby  and  to  him  alone  is  due  the  pioneer's  honour." 


Researches  on  Rock  Sections. — At  the  period  (1849)  when  Sorby 
began  his  researches  on  rocks,  the  only  available  knowledge 
of  the  constitution  of  igneous  rocks  was  that  gained  either 
by  the  field-worker  with  his  hammer  or  by  the  indoor  Geologist 
by   the    tedious   processes   of    chemical    analysis.       Slices    of    rock 


116  THE    GREAT   WORK    OF    SORBY  : 

ground  to  a  thinness  of  about  one-thousandth  of  an  inch  allowed 
light  to  pass,  and  with  the  Microscope  it  became  possible  to  see  their 
structure  more  clearly  than  the  texture  of  the  coarsest  granite  had 
hitherto  appeared.  Rock-slices,  having  been  ground  down  flat, 
were  admirably  adapted  to  the  application  of  polarized  light,  and  to 
one  who  had  already  a  working  knowledge  of  optics,  the  vagaries  of 
the  vector  variations  of  the  optical  properties  of  minerals  proved  to 
be  no  deterrent.  Finding  no  treatise  on  this  subject  ready-made, 
Sorby  designed,  and,  with  his  own  hands  constructed,  a  polariscope 
to  work  either  with  parallel  or  with  convergent  light,  and  the  very 
instrument  which  he  then  made  is  still  in  use  in  the  Sheffield 
University  Physical  Laboratory. 

Researches  on  Me«eon7e5.— Subsequent  to  his  early  Petrological 
Researches,  Sorby  turned  his  attention  to  the  Microscopical  Study 
of  Meteorites. 

In  his  Paper  "  On  the  Microscopical  Structure  of  Meteorites  " 
(Royal  Society  Proceedings,  1864,  p.  333)  he  pointed  out  that  he  had 
applied  to  the  Study  of  Meteorites  the  principles  he  had  made  use  of 
in  the  investigation  of  terrestrial  rocks  described  in  his  various  Papers 
and  specially  in  that  on  the  Microscopical  Structure  of  Crystals  (Quar- 
terly Jnl.  Geol.  Soc.  1858,  Vol.  XIV,  p.  453).  He  there  showed  that 
the  presence  in  Crystals  of  "  fluid,  glass,  stone,  or  gas  cavities  "  enabled 
the  conditions  under  which  the  crystals  were  formed  to  be 
satisfactorily  determined.  There  were  also  other  methods  of 
enquiry  still  requiring  much  investigation  and  a  number  of  experi- 
ments to  be  made,  but  not  wishing  to  postpone  the  publication  of 
certain  facts  he  gave  a  short  account  of  them  in  this  Paper. 

This  Paper  was  followed  by  another  "  On  the  conclusion  to  be 
drawn  from  the  Physical  Structure  of  some  Meteorites"  (B.A.  Report,. 
1864,  p.  70),  in  which  Sorby  pointed  out  that  he  had  previously  ^  ho wn. 
that  the  earliest  condition  of  meteorites  of  which  their  microscopical 
structure  furnishes  evidence  was  that  of  igneous  fusion.  There 
were,  however,  some,  like  the  Pallas  Iron,  consisting  of  a  mixture  of 
Iron  and  Olivine  which  apparently  strongly  opposed  this  view  if 
judged  from  what  occurred  when  melted  artificially  ;  for  then  the 
Iron  being  so  much  more  dense  would  sink  to  the  bottom  and  the 
Olivine  rise  to  the  top  like  slag  in  a  furnace.  The  object  of  thi& 
Paper  was  however  to  show  that  this  difference  in  density 
depended  on  the  force  of  gravitation  and  that,  on  the  surface 
of  a  small  planetary  body,  or  towards  the  interior  of  a  larger 
planetary  body,  Iron  and  Olivine  might  remain  mixed  in  a. 
state  of  fusion  long  enough  to  allow  of  gradual  crystallisation. 
Such  meteorites  should  therefore  be  considered  evidence  of  fusion 
where  the  force  of  gravitation  was  very  small  ;  and  this  conclusion 
might  be  valuable  in  deciding  between  rival  theories  of  their  origin. 

Application  of  Sorby's  Work  to  Metallurgy.— At  the  time  these 
researches  were  carried  out,  although  the  Science  of  Metallurgy  had 
advanced  at  a  great  rate,  Chemical  analysis  remained  the  ultimate 
arbiter  of  the  quality  of   any  metal.    The    work,   however,   of    Gore, 


SIR     ROBERT    HADFIELD,     BART.  117 

Barrett  and  Tchernoff  on  the  intimate  relationship  existing  between 
recalescence  and  the  hardening  of  steel,  and  also  the  work  of  Guthrie 
oneutectics  led  to  the  idea  that  both  igneous  rocks  and  alloyed  metal 
are  the  products  of  the  crystallisation  of  mixed  solutions.  Bunsen, 
and  subsequently  Vogt  of  Christiania,  called  attention  to  the  laws 
which  control  the  crystallisation  of  minerals  in  slag,  and  when  Teall 
in  1888  pointed  out  the  similarities  of  structure  between  graphic 
intergrowths  and  Guthrie's  eutexia  of  Metals,  the  application  of  the 
solution  hypothesis  to  rocks  became  apparent.  In  the  domain  of 
Metallurgy,  the  introduction  of  the  Thermocouple  by  Professor 
le  Chatelier  led  to  the  study  of  the  Thermal  Changes  which  accompany 
physical  or  chemical  variations  of  constitution  within  the  metal. 

Sorby,  in  his  Paper  contributed  to  the  Iron  and  Steel  Institute 
in  1887  and  published  in  Vol.  I  of  the  Journal  for  that  year,  stated  : 

''It  is  now  twTuty  years  since  I  commenced  to  carefully  study 
the  microscopic  structure  of  Iron  and  Steel.  The  first  object  was 
the  study  of  meteoric  iron,  but  I  soon  found  that  the  results  were  of 
even  more  value  in  connection  with  practical  metallurgy." 

Again,  on  page  276  of  the  same  volume,  he  says  : 

"  I  regard  that  even  a  power  of  400  linear  fails  to  show  whether 
the  pearly  constituent  remains  unaltered  or  broke  up  into  verv  fine 
laminae  when  very  suddenly  cooled.  It  either  does  not  or  the  laminae 
are  too  thin  to  be  recognised.  The  changes  in  structure  produced  by 
hardening  deserve  far  more  study,  but  will  I  fear  tax  to  the  utmost 
the  capabilities  of  the  Microscope  since  the  constituent  grains  of 
hardened  steel  are  so  extremely  minute." 

At  this  stage  Sorby's  work  on  Metals  received  recognition  and 
exerted  a  powerful  influence.  It  became  evident  that  the  mechani- 
cal properties  of  Iron  and  Steel  depend  upon  the  properties  of  their 
crystalline  constituents,  and  at  this  period  the  nomenclature  of  metal- 
lography was  developed.  The  subsequent  work  of  Raoult,  Van't 
Hoff,  Gibbs,  etc.,  led  to  a  tendency  to  decry  the  nomenclature  as 
unscientific.  Nevertheless,  it  is  still  used  and  serves  well  for  the  ready 
specification  of  different  qualities  of  steel. 

Professor  Judd,  who  was  a  friend  of  Sorby,  has  given  some  inter- 
esting reminiscences  of  the  conditions  under  which  Sorby  worked. 
Apropos  of  Sorby's  Laboratory,  he  remarked :  "  You  speak  of  Sorby's 
laboratory.  All  his  work,  when  I  knew  him,  was  done  in  a  private 
room  in  his  house  ;  there  everything  was  as  simple  as  WoUaston's 
— a  table  with  his  Microscope,  and  a  few  bits  of  apparatus  lying 
about." 

In  the  same  connection,  Judd  also  remarked  :  "  I  went  to  Sheffield, 
as  a  Chemist  to  the  Cyclops  Works,  straight  from  the  Jermyn  Street 
School  of  Mines  in  the  Summer  of  1864,  and  at  once  met  Sorby.  He 
not  only  taught  me  to  make  rock-sections,  but  showed  me  what  he  was 
doing  with  artificial  irons— led  to  it  by  his  studies  of  iron-meteorites. 
Mr.  George  Wilson,  then  manager  of  Cammells,  a  very  enlightened 
man,  gave  me  permission  to  supply  Sorby  with  any  irons  that  I 
analysed,  for  his  work,  so  that  I  saw  the  beginning  of  his  Metallurgical 
work — a  very  pleasant  reminiscence.      Down  to  the  time  that  Ward 


118  THE   GREAT   WORK   OF    SORBY 

and  I  left  the  Geological  Survey,  in  1871,  Microscopic  Petro^ 
was  always  ridiculed  by  '  the  powers  that  were.'      They  always  sai( 
'  You  can't  study  mountains  through  Microscopes.'  " 

The  following  appreciation  of  Sorby's  work  is  made  by  M.  Ch. 
Fremont,  the  well-known  French  Engineer  and  Metallurgist : — 

"  It  was  Sorby's  discovery  of  the  method  whereby  the  structure 
of  a  metal  was  laid  bare  to  microscopic  examination  that  gave  him 
the  right  to  the  title.  The  method  he  used  to  prepare  his  rock  sections 
failed  him  with  metals,  because  the  latter,  even  in  very  thin  sections, 
are  not  transparent.  Sorby,  however,  discovered  that  by  suitably 
etching  a  perfectly  polished  surface  of  metal  the  structure  was  revealed 
to  microscopic  examination."  The  great  merit  of  Sorby  consisted 
in  having  applied  to  Metallurgy  the  Micrographic  method  he  had  dis- 
covered and  introduced  in  the  study  of  Mineralogy. 

Our  Meeting  this  evening  is  a  living  evidence  of  ''  Great  is  the 
Truth  and  it  will  Prevail."  From  the  humblest  of  beginnings  this 
method  of  research  has  grown  into  a  giant.  It  will  still  further 
help  to  add  to  the  sum  total  of  human  knowledge  from  which  all 
may  benefit.  All  honour  to  this  Great  Englishman  for  the  magnificent 
work  he  accomplished. 


THE     REQUIEEMENTS     OF     THE     PETROLOGICAL 
MICROSCOPE. 

By  Dr.  J.  W.  Evans,  F.R.S. 


The  Petrological  microscope  is  constructed  to  serve  two  purposes. 
It  is  employed,  in  the  first  place,  as  an  ordinary  microscope,  to 
observe  the  form  and  structure  of  the  smaller  features  of  rocks ;  and  it 
is  also  used  as  an  optical  instrument  for  studying  the  action  of  minute 
crystals  on  light  with  a  view  to  their  identification.  The  latter 
function  requires  special  features  of  greater  or  less  complexity.  The 
exact  nature  of  these  arrangements  depends,  however,  to  some  extent 
on  whether  the  material  is  examined  in  the  form  of  a  thin  section 
of  a  rock,  or  in  minute  grains  or  fragments. 

In  all  petrological  microscopes  provision  is  made  for  the  examina- 
tion of  the  object  between  crossed  nicols,  and  for  the  rotation  of  these 
or  of  the  stage  or  of  both  alternatively.  The  advantage  of  a  rotating 
stage  and  stationary  nicols  is  so  great  from  the  point  of  view  of  sim- 
plicity of  construction,  that  it  is  always  adopted  in  the  cheaper  in- 
struments, and  it  is  quite  satisfactory  in  all  eases  where  the  work  is 
confined  to  thin  sections  and  methods  involving  certain  special  acces- 
sories or  arrangements  are  not  required  to  be  employed. 

On  the  other  hand,  for  the  examination  of  grains  mounted  in  oil 
or  other  highly  refracting  medium,  the  use  of  a  stationary  stage  and 
rotating  nicols  is  practically  a  necessity,  if  high  powers  are  to  be 
employed,  unless  the  Nachet  device  is  adopted,  by  which  the  objective 
is  attached  to  the  stage  and  rotates  with  it.  Rotating  nicols  are  also 
necessary  for  the  more  complex  optical  methods,  especially  those  that 
require  an  axis  of  rotation  at  right  angles  to  the  optical  axis  of  the 
microscope,  as  when  the  optical  characters  of  crystals  are  studied  by 
means  of  the  theodolite  or  "  universal  "  stage.  It  deserves  considera- 
tion whether,  when  rotating  nicols  are  employed,  a  rigid  connection 
T^etween  them  should  not  be  substituted  for  the  gearing  employed 
by  Dick,  even  although  the  former  is  open  to  the  objection  that  a 
rotation  through  a  complete  circle  is  not  possible.  This  course  has 
been  occasionally  followed. 

Where  crushed  material  or  small  grains  are  examined  in  oil  or 
micro-chemical  tests  are  applied,  the  microscope  should  be  protected 
by  a  shallow  glass  bath  with  a  plane  floor,  large  enough  to  hold  the 
glass  slip. 

There  should  be  a  ''  mechanical  stage  "  providing  for  the  move 
ment  of  the  object  in  two  directions  at  right  angles  to  each  other  and 
to  the  optic  axis  of  the  microscope,  so  that  the  position  of  the  object 
may  be  varied  while  its  orientation  remains  unaltered.  These  move- 
ments and  the  fine  adjustment  should  be  accurately  graduated. 

Arrangements  should  also  be  made  by  which  a  nicol  may  be  placed 
in  a  position  above  the  eye-piece.  At  the  same  time  a  slot  should 
be  provided  at  the  focus  of  the  eye-piece,  so  that  accessories,  such 
as  quartz  wedges,  may  be  inserted  in  focus.  The  upper  nicol  or 
analyser,  wherever  placed,  should  be  capable  of  rotation,  either  simul- 

119 


120      THE  REQUIREMENTS  OF  THE  PETROLOGICAL 

taneously  with  the  lower  nicol  or  polariser  or  independently  of  it, 
and  there  should  be  special  facilities  for  adjusting  it  at  small  angles 
of  divergence  from  3  to  6  degrees  from  the  position  of  crossed  nicols.* 
This  is  useful  in  determining  the  exact  position  of  extinction. 

Greater  facilities  should  be  given  for  the  study  of  the  interference 
figures  in  the  "  directions  image  "  in  polarised  light.  It  is  difhcult  to 
exaggerate  the  value  of  the  purely  qualitative  results  described  by 
Beck,  a"s  well  as  the  quantitative  methods  which  involve  careful 
measurements  of  the  "  isogyres  "  or  dark  bars,  f  For  these  purposes 
immersion  objectives  with  an  especially  wide  angle  should  be  used 
with  highly  refracting  liquids,  and  a  corresponding  wide-angled 
illumination  should  be  provided.  It  is  absolutely  necessary  that  the 
student  should  be  in  a  position  to  isolate  the  light  from  minute 
crystals  surrounded  by  others  of  different  composition  or  with  differ- 
ent orientation.  Among  othr  examples  may  be  mentioned  the  zones 
and  twin  lamellae  of  plagioclase.  By  far  the  best  means  of  effecting 
this  is  by  inserting  a  diaphragm  in  the  focus  of  the  eye-piece  and 
a  Becke  lens  placed  above  it.t  This  should  be  a  recognised  accessory 
with  all  except  the  most  elementary  petrological  microscopes.  Pro- 
vision should  be  made  to  enable  the  exact  course  of  the  isogyres  to 
be  measured.  There  is  no  space  here  to  discuss  the  mei'its  of  the 
different  devices  which  have  been  suggested,  including  one  for  which 
I  am  responsible.  § 

Some  arrangements  should  also  be  available  for  the  study  of  the 
object  in  linear  convergent  light,  which  is  advantageous  for  various 
purposes.  It  can  be  obtained  by  employing  an  ordinary  convergent 
system  and  inserting  a  narrow  slit  in  a  focus  conjugate  to  infinity,  with 
such  orientation  relatively  to  the  object  as  may  be  required. || 

Provision  should  also  be  made  for  the  use  of  monochromatic  light 
when  desired.  The  slit  already  referred  to  may  be  employed  for  the 
purpose  in  conjunction  with  a  prism  ;  or  some  form  of  monochromator, 
or  a  colour  screen  may  be  substituted,  unless  coloured  flames  be 
preferred. 

I  have  not  attempted  to  deal  with  all  the  numerous  accessories 
which  have  been  employed  or  suggested  in  petrological  work,  but 
have  confined  myself  mainly  to  variations  of  construction  necessitated 
by  special  methods. 

Reference  may  be  made  to  the  report  of  the  Microscope  Committee 
of  the  British  Science  Guild  giving  a  specification  of  a  student's  petro- 
logical microscope.^ 

A  serious  difficulty  is  presented  by  the  high  cost  of  petrological 
microscopes  constructed  so  as  to  allow  of  the  application  of  advanced 
methods  of  research.  This  is  inevitable  so  long  as  the  number  of 
instruments  inanufactured  is  too  small  to  justify  the  employment 
of  systematic  standardisation  with  interchangeable  parts. 


"•■   F.  E.  Wright,  Am.  Journ.  Sci.,  Vol.  26.,  ipp.  340-368,  380-386  (iqoS). 
t  M.in.  Mag.,  Vol.  XIV,  pp.  230-234,  276-281  (1Q07);  Min.  Pair.  Mitt., 
Vol.   XXIV,   pp.    1-34   doos). 

t  Min.  Mag..  Vol.   XVHI,  pp.  45-51  (1916). 

§  VTin  era  logical  Magazine,  Vol.  XVIII,  pp.  52-57  (1916), 

II   Min.   Mag.,  Vol.  XVIII,  pp.   130-132   (1917). 

51  Journ.    Brit.   Sci.    Guild;   November,    1916,  pp.   28-31. 


MICROSCOPE:    DR.  J.   W.   EVANS  121 

There  are  two  directions  in  which  we  may  look  for  an  increase 
in  the  demand  for  instruments  of  this  type.  The  first  is  the  general 
adoption  by  chemists  of  optical  methods  of  studying  crystalline 
chemical  products,  and  the  second,  the  stimulation  of  the  demand 
for  British  instruments  in  other  countries.  Every  encouragement 
should  be  given  to  those  engaged  in  original  scientific  work  to  design 
new  or  improved  types  of  microscopes  or  accessories,  and  each  new 
type  should  be  fully  described  in  the  scientific  and  technical  journals 
by  the  inventor,  whether  he  is  a  member  of  the  staff  of  a  University 
or  of  that  of  an  optical  factory.  If  this  policy  is  effectively  pursued, 
other  countries  will  turn  to  British  makers  for  the  supply  of  instru- 
ments of  the  latest  and  most  novel  patterns. 

It  was  by  such  methods  that  the  well-known  German  makers 
obtained  the  commanding  position  they  held  before  the  war,  and  it 
is  only  on  these  lines  that  our  country  can  hope  to  take  the  place 
that  it  ought  to  have  in  the  manufacture  of  specialised  types  of 
microscopes. 

The  working  out  of  new  ideas  involves,  however,  considerable 
expense,  far  greater  than  is  afterwards  required  to  construct  similar 
instruments  when  standardised  and  produced  on  a  large  scale,  and 
it  is  absolutely  necessary  that  pecuniary  assistance  should  be,  in  the 
first  place,  forthcoming,  if  success  is  to  be  ultimately  achieved. 


APPLICATION  OF  THE  MICROSCOPE  TO  THE  SELECTION 
AND  CONTROL  OF  YEAST  EMPLOYED  FOR  BREWING 
PURPOSES. 

By  A.  Chaston  Chapman. 


The  application  of  the  microscope  to  the  selection  and  control  of 
yeast  in  the  brewery  may  be  said  to  date  from  the  publication  in 
1876  of  Pasteur's  "  Etudes  sur  la  Biere."  In  this  he  made  his 
famous  pronouncements  *'  That  every  unhealthy  change  in  the  quality 
of  beers  coincides  with  the  development  of  micro-organisms  foreign  to 
brewer's  yeast  properly  so-called,"  and  that  "  the  absence  of  change 
in  wort  and  beer  coincides  with  the  absence  of  foreign  micro-organ- 
isms." 

By  "  foreign  micro-organisms  "  in  the  above  statements  Pasteur 
referred  solely  to  bacteria,  and  it  w^as  some  years  later  (1879)  that 
Hansen  outlined  his  method  of  making  pure  cultures  of  yeast  starting 
from  a  single  cell.  As  a»  result  of  the  application  of  this  method,  he 
showed  that  some  of  the  yeast  species  which  were  frequently  present, 
both  in  the  pitching  yeast  of  the  brewery  and  in  the  air,  were  capable 
of  producing  "  diseases  "  in  beer  quite  as  serious  as  those  produced 
by  bacteria.  By  a  study  of  ascospore  formation  and  other  biological 
characters  of  the  various  species,  it  was  found  possible  to  make  a 
distinction  between  the  culture  yeasts  and  the  so-called  "  wild  " 
yeasts  sufficiently  definite  to  enable  one  cell  of  the  latter  to  be  detected 
in  the  presence  of  at  least  100  cells  of  culture  yeast.  By  means  of 
the  microscope,  therefore,  it  is  possible  to  detect  the  contamination 
of  the  pitching  yeast,  not  only  with  bacteria,  but  also  with  other 
undesirable  yeast  species,  and  to  take  the  necessary  steps  to  purify  it. 

Lantern  slides  representing  culture  yeasts  and  a  number  of  the 
"  wild  "  yeasts  in  illustration  of  the  above  statements  were  shown. 


IL'2 


THE    MICROSCOPIC    OUTFIT    OF    A  TEXTILE    RESEARCH 

LABORATORY. 


By  R.   S.  Willows,  M.A.,  D.Sc. 

In  the  interests  of  brevity  I  will  confine  my  remarks  closely  to 
the  requirements  of  a  research  worker  in  the  textile  industry.  The 
materials   to  be   examined   are   fabrics,   yarns,   fibres,    starches,   and 

Objectives. 

The  objectives  used  will  be  from  2  in.  down  to  an  oil  immersion, 
and  for  certain  purposes  an  ultra-microscope  of  the  cardioid  or 
similar  type,  while  for  special  work  an  immersion  ultra-microscope 
may  be  a  great  advantage.  The  most  useful  lenses  are  the  16  mm., 
the  6  mm.,  and  in  a  less  degree  the  4  mm.  and  an  oil  immersion. 
The  first  is  most  useful  for  examining  single  fibres,  while  the  second 
will  do  most  of  the  routine  work  on  sections,  especially  if  it  will 
stand  a  high  power  eye-piece.  Strange  to  say,  at  least  one  English 
maker  of  high-class  lenses  does  not  produce  a  6  mm.  lens.  I  have 
found  certain  English  apochromats  excellent  in  flatness  of  field  and 
definition,  but  they  have  the  disadvantage  of  a  short  working 
distance ;  it  is  fair  to  add  that  in  the  last  respect  they  are  no  worse 
than  Continental  types.  For  most  purposes  I  find  some  semi- 
apochromats  in  my  possession  are  all  that  is  required ;  the  field  is 
not  very  flat,  but  the  definition  in  the  centre  is  excellent,  their 
working  distance  is  large,  they  will  stand  an  x  18  eye-piece,  and 
they  are  comparatively  inexpensive. 


Stands. 

1  prefer  the  English  type  of  stand  to  the  Continental  model, 
on  account  of  the  better  distribution  of  weight  and  consequent 
greater  stability,  and  also  for  the  greater  space  for  the  substage. 
The  tube  must  rack  out  to  take  a  2  in.  objective,  and  in  this 
connection  it  is  a  great  advantage  if  the  stage  can  also  be  racked. 
The  latter  movement  is  also  very  useful  w^hen  it  is  required  to  use 
vertical  illumination.  A  mechanical  stage,  centering  substage,  and 
high-class  condenser  are  taken  for  granted,  even  on  the  simplest 
types  of  stand.  Very  frequently  a  considerable  portion  of  the  slide 
has  to  be  examined ;  this  should  be  possible  without  fouling  the 
condenser. 

As  the  material  to  be  examined  has  frequently  to  be  submitted 
to  the  action  of  acids  and  alkalis  while  it  is  on  the  stage,  the  latter 
should  be  made  of  a  suitable  material,  and  should  be  designed  so 
as  to  eliminate  as  far  as  possible  the  chance  of  injury  to  the 
instrument.  Apart  from  material  used,  the  design  of  such  a  stage 
appears  to  have  received  little  attention.  It  is  in  such  examinations 
that  a  large  working  distance  for  the  objective  is  so  markedly 
advantageous. 


124         THE   MICROSCOPIC   OUTFIT  OF  A   TEXTILE 

Polarisation  Apparatus. 

This  is  often  extremely  crude.  Types  which  require  the  analyser 
to  be  screwed  on  behind  the  objective,  or  in  which  the  polariser 
replaces  the  condenser,  not  only  waste  much  time  in  making  the 
necessary  changes,  but  the  illumination  is  cut  down  badly.  The 
analyser  should  be  built  in  the  body  tube,  should  be  capable  of 
being  swung  or  slid  out  when  not  required,  and  the  analyser  should 
come  below  the  condenser  and  should  have  the  swing-out  motion. 

Ultra-microscope. 

An  efficient  and  easily  handled  form  of  ultra-microscope  is  urgently 
required,  not  only  for  general  scientific  research,  but  also  in  several 
branches  of  textile  work,  especially  on  the  sizes  and  dyes. 

Fhotomicrograjjhic  A pparatus. 

It  is  on  this  side  that  English  apparatus  is  most  defective.  V/here 
it  is  not  a  frank  imitation  of  foreign  types,  it  shows  no  evidence  of 
design  as  a  whole,  and  in  a  number  of  small  details  is  so  defective 
that  I  sometimes  doubt  if  its  makers  have  ever  used  it  to  take 
photographs  under  the  varied  conditions  that  exist  in  a  works 
research  laboratory.  For  my  own  purposes  I  desire  an  equipment 
fulfilling  the  following  conditions:  — 

(1)  As  it  will  be  used  where  there  is  considerable  vibration,  the 

mechanical  design  should  be  such  as  to  reduce  the  effects 
of  this  vibration  to  a  minimum.  That  eliminates  the  type 
where  camera  and  microscope  are  on  separate  stands. 

(2)  It  should  be  easy  to  make  a  visual  examination  before  the 

photograph  is  taken.     This  is  most  readily  done  by  swinging 
the  optical    system    and    microscope    out    of    line    with   the 
camera.      It   may    be    difficult    when  the   light   source    is    a 
large    arc   surrounded   by    a  lantern,    but    is   comparatively 
easy    if    a    "  Point.olite  "    set    is  used.      I   have    found    this 
source    most    efficient    and    handy.      It    consists,   as    is    well 
known,  of   a  tungsten  arc  in   nitrogen;   it  burns  for   hours 
witKout    the    slightest    attention,    and   as    the    spectrum    of 
tungsten  is  exceptionally  rich  in  the  photographically  active 
rays,    it  is    more    powerful    than     a     simple     candle-power 
measurement   indicates.      May    I   suggest   to   manufacturers 
that    before    it    is   fixed    on    the    optical    train    they    should 
discover   in   what   direction  it  emits   most   light,    and   fix  it 
accordingly  ?      At    present    the    direction    used    appears    to 
depend  on  other  considerations  altogether. 
(3)  It   should   be  possible   to   pass    from    transmitted   to   vertical 
illumination  quickly  and  without  having  to  make  a  number 
of  delicate  adjustments.     Among  the  unsatisfactory  methods 
at  present  put  on  the  market  I  have  come  across  the  follow- 
ing: — (a)  Change  the  microscope  to  a  vertical  position  and 
use  a  vertical  camera ;  (b)  swing  the  optical  train  through  a 
right    angle    round    a    vertical   axis;    (c)    move    the    optical 
bench  parallel  to  itself  and  insert  a  mirror  inclined  to  the 
beam  at  45°.     The  last  is  undoubtedly  the  method  requiring 
the   least   complication   of  apparatus   if   properly   designed; 


RESEARCH  LABORATORY  :  R.  S.  WILLOWS    125 

but  some  of  the  applications  of  it  are  very  crude.  A  fourth 
method  appears  to  be  possible,  viz.,  to  keep  the  optical  train 
fixed,  but  to  deflect  the  light  three  times  at  right  angles 
by  total  reflexion  prisms,  and  so  throw  it  into  the  vertical 
illuminator.  As  the  last  prism  would  be  a  small  one,  it 
could  well  be  carried  by  the  moving  part  of  the  microscope ; 
it  would  not  then  require  adjustment  as  the  microscope  is 
f  ocussed . 

(4)  It  would  be  a  great  advantage  where  the  action  of  solutions 
is  to  be  followed  and  recorded,  if  a  horizontal  camera  could 
be  used  when  the  slide  carrying  the  object  is  horizontal; 
this  would  combine  the  advantages  of  a  horizontal  camera 
and  a  vertical  position  for  the  microscope  tube.  I  have 
not  seen  any  attempt  at  this  in  an  English  apparatus. 

In  conclusion,  may  I  say  that  the  textile  industries  in  the  past 
have  been  among  the  least  scientific  of  the  large  trades,  but  the 
need  for  research  is  now  fully  recognised.  In  such  research  the 
microscope  and  physical  apparatus  generally  must  play  an  important 
part.  As  one  who  is  keenly  interested  in  the  technical  applications 
of  science,  I  hope  instrument  makers  will  make  themselves  acquainted 
with  the  requirements  of  the  industry  and  will  endeavour  not  only 
to  meet  them,  but,  if  possible,  to  anticipate  them.  As  a  small 
step  in  this  direction  I  suggest  that  The  Journal^  of  the  Textile 
Institute  should  find  a  place  on  the  shelves  of  their  works  library. 


126  DR.     W.     ROSENHAIN 


A  series  of  papers  dealt  with  the  use  of  the  microscope 
in  metallurgy.  The  subject  was  introduced  by  Dr.  W. 
Rosenhain,    F.R.S. 

In  view  of  the  lateness  of  the  hour,  there  will  not  be  time  for  me 
to  read  the  paper  which  I  have  prepared ;  therefore  I  will  only  deal 
with  one  or  two  points  which  I  think  are  more  relevant  to  the  aspects 
of  the  whole  question  which  have  already  been  discussed.  I  should 
like  to  say  one  or  two  words  with  regard  to  the  question  of  increased 
magnification  and  increased  resolving  power  for  metallurgical  work. 
There  can  be  no  question  that  we  are  dependent  to  a  large  extent 
for  further  progress  in  certain  directions  in  metallography  on  obtain- 
ing higher  resolution  and  higher  magnification,  but  it  has  been  clear 
to  many  of  us  for  a  long  time,  and  to  those  to  whom  it  has  not 
been  clear  it  will  be  so  after  having  listened  to  these  discussions,  that 
magnification  alone  is  quite  useless,  and  that  what  we  must  look 
for  is  higher  resolving  power.  Mr.  Barnard  has  emphasised  the 
theoretical  possibilities  of  using  a  much  shorter  wave-langth.  No 
doubt  in  the  future  it  may  be  possible  to  do  that,  and  Mr.  Barnard 
himself  has  been  singularly  successful  in  utilising  the  short  wave- 
length of  invisible  light  for  photoniicrographic  work  on  transparent 
sections.  About  seven  or  eight  years  ago  I  was  able  to  obtain  at 
the  National  Physical  Laboratory  a  complete  outfit  of  Zeiss  apparatus 
for  this  purpose,  and  I  spent  a  large  amount  of  time — over  a  year — 
in  endeavouring  to  use  it  for  metallographic  purposes,  but  the  result 
on  the  whole  was  extremely  disappointing.  I  succeeded  in  getting 
a  few  photographs,  but  the  time  occupied  and  the  labour  involved 
were  enormous,  and  when  I  did  succeed  it  was  only  with  moderate 
magnifications.  The  attempt  to  use  high  power  monochromatic 
immersion  lenses  failed  entirely,  owing  to  the  fact  that  I  always  got 
milky  images.  Fluorescence  occurred  whenever  the  ultra-violet  light 
struck  any  object  within  the  tube.  When  the  beam  of  ultra-violet 
light  has  to  be  sent  through  a  reflector  and  through  the  objective, 
fluorescence  occurs  on  the  objective  itself,  and  as  a  result  the  light 
reflected  from  the  back  of  the  objective  all  over  the  tube — the  actual 
visible  lis^ht  due  to  that  fluorescence — became  very  serious  in  its 
actinic  effect  on  the  photographic  plate,  and  I  felt  the  only  possi- 
bility of  proceeding  at  all  would  be  if  a  filter  could  be  obtained 
which  would  exclude  visible  light  and  transmit  the  ultra-violet  light 
almost  undiminished.  Prof.  R.  W.  Wood,  of  Baltimore,  suggested 
the  silvering  of  one  of  the  lenses,  but  that  increased  the  exposure 
so  enormously  that  it  was  hopeless.  Other  circumstances  arose,  and 
the  matter  had  to  be  left  aside.  I  hope  someone  mav  succeed  in 
overcoming  these  difficulties,  but  I  am  not  sanguine  of  the  results 
which  can  be  obtained  with  any  kind  of  invisible  radiation,  and  my 
reason  is  that  such  methods  will  only  yielH  photographs.  Photo- 
graphs are  extremely  useful  as  a  record  of  w^hat  you  have  seen, 
but  as  a  means  of  actual  microscopic  examination  they  are  not 
satisfactory.  I  always  think  it  is  necessary  to  examine  successively 
large  areas,  and  that  you  cannot,  by  using  a  few  photographs  of 
small  areas,  form  a  really  good  opinion. 


DR.   W.   ROSENHAIN  12T 

There  is  one  other  direction  in  which  I  think  that  higher  resolving 
power  is  at  any  rate  conceivable.  Resolving  power  is  a  function 
of  the  nuiQerical  aperture  expressed  in  terms  of  u  sin  a.  Sin  a 
cannot  be  increased  very  much,  but  what  about  u  ?  The  immersion 
liquid  is  a  difficulty,  but  I  think  that  a  higher  refractive  index  for 
the  front  glass  is  at  any  rate  a  thing  where  there  is  hope  of  success 
as  the  result  of  research.  I  agree  with  Sir  Herbert  Jackson  that 
research  will  make  it  possible  to  make  glasses  of  almost  any  desired 
kind;  there  is,  however,  a  good  deal  of  emphasis  to  be  placed  on 
the  "  almost,"  because  the  range  of  possible  glasses  is  strictly  con- 
fined within  certain  limits  of  refractive  index.  I  have  on  a  previous 
occasion  given  the  values  of  these  limits,  and  the  limitation  is  due 
apparently  to  quite  definite  physical  and  chemical  causes.  Glasses 
having  very  low  refractive  indices  or  high  ones,  and  having  abnormal 
optical  properties,  are  virulent  chemical  agents  in  their  action  on 
everything  they  may  come  in  contact  with,  including  air.  They  are 
rapidly  attacked  by  moist  air,  and  they  crystallise  during  manufac- 
ture. There,  I  think,  lies  the  solution  of  the  problem.  When  we 
look  for  substances  which  have  high  refractive  indices,  we  find  them 
in  crystals,  and  I  want  to  carry  that  suggestion  one  step  further.  I 
made  it  many  years  ago,  but  with  the  renewed  stimulus  to  research 
in  this  direction,  it  is  worth  making  it  again.  The  time  has  surely 
come  when  we  should  meet  this  question  of  crystalline  substances 
for  optical  purposes  by  attempting  to  grow  crystals  artificially.  I  am 
quite-  sure  that  it  can  be  done,  and  it  ought  to  be  done.  I  have 
made  a  few  preliminary  experiments  of  that  kind,  and  have  succeeded 
in  producing  some  small  calcium  carbonate  crystals.  They  were 
small,  but  they  were  large  enough  for  short- focus  lenses,  and  I  think 
the  idea  of  growing  crystals  is  not  altogether  out  of  the  range  of 
practical  possibilities  to-day. 


THE    METALLURGICAL    MICROSCOPE. 

By  Walter  Rosenhain,  D.Sc,  F.R.S. 
(The  National  Physical  Laboratory.) 


In  a  paper*  presented  to  the  Royal  Microscopical  Society  in  1906, 
the  present  author  has  described  a  Metallurgical  Microscope  in  the 
design  and  construction  of  which  an  effort  has  been  made  to  apply 
certain  principles  which  he  regards  as  fundamental  for  the  construc- 
tion of  scientific  instruments  in  general  and  of  microscopes  in  par- 
ticular. These  principles  have  previously  been  discussed  in  a  paperf 
presented  to  the  Optical  Convention,  1905.  For  the  purposes  of  the 
present  discussion,  therefore,  it  will  not  be  necessary  to  do  more  than 
to  summarise  briefly  some  of  the  principal  points  affecting  the  metal- 
lurgical microscope. 

In  regard  to  mechanical  design,  the  primary  consideration  i3 
that  of  providing  adequate  strength  and  stiffness  not  only  in  the 
base  and  limb,  but  also  in  the  working  joints,  such  as  that  upon 
which  the  limb  turns.  The  design  of  such  an  instrument  should,  in 
fact,  in  the  author's  opinion,  be  based  rather  upon  that  of  a  machine 
tool  than  on  the  unduly  delicate,  sometimes  flimsy,  and  often  un- 
mechanical  devices  which  are  to  be  found  in  some  scientific  instru- 
ments. One  fruitful  source  of  lack  of  rigidity  may  be  found  in 
the  presence  of  unnecessary  movements ;  for  instance,  it  is  now  fairly 
generally  accepted  as  an  essential  feature  of  metallurgical  microscopes 
that  the  focussing  movement,  at  all  events  so  far  as  the  coarse 
adjustment  is  concerned,  should  be  applied  to  the  stage.  The  pro- 
vision of  a  coarse  focussing  movement  for  the  body  tube  as  well, 
therefore,  constitutes  an  undesirable  duplication.  If  the  fine  adjust- 
ment is  also  applied  to  the  stage,  as  has  been  done  in  the  author's 
design,  then  the  body  tube  can  be  rigidly  attached  to  the  limb, 
with  a  corresponding  gain  in  rigidity. 

Another  source  of  unsteadiness  lies  in  the  manner  in  which  the 
so-called  vertical  illuminator  is  frequently  attached.  Where  this 
fitting  is  screwed  to  the  nose-end  of  the  body  tube  and  the  objective 
is  screwed  into  the  illuminator,  a  certain  amount  of  play  is  liable 
to  occur.  The  author,  therefore,  very  much  prefers  an  arrangement 
by  which  the  objective  is  screwed  direct  to  the  body  tube,  and  the 
illuminator  is  inserted  into  the  body  tube,  by  means  of  a  slide  or 
otherwise,   through  a  lateral  aperture. 

The  apj^lication  of  the  fine  focussing  adjustment  to  the  stage 
offers  a  further  advantage  which  is  of  some  importance,  as  by  this 
ai-raiigeiiieut  the  fine  focussing  movement  can  be  placed  in  an  axial 
position.  If  this  is  done  there  is  no  overhang  to  magnify  the  slight 
play    which    is    unavoidable    on    all    smooth    running    slides.      This 

*  "On  an  Improved  Form  of  Metal lungical  Microscope,"  Journal 
Royal  Microscopical   Society,    iqo6. 

t  "The  Mechanical  Design  of  Instrumemts,"  Piroc.  Optical  Con- 
vention, Vol.   I,  1005. 

128 


WALTER    ROSENHAIN  129 

difficulty  might  perhajDs  be  overcome  in  another  way  by  adopting 
geometrical  contacts  instead  of  plain  sliding  contacts.  The  advan- 
tage of  this  system  has  long  been  recognised  in  theory,  but  instrument 
makers  do  not  appear  to  have  seen  their  way  to  its  adoption 
on  any  large  scale. 

The  illuminator  and  its  adjustments  deserve  a  little  further  con- 
sideration. Both  for  visual  and  photographic  purposes  the  author 
has  found  it  a  very  great  advantage  to  have  an  illuminator  whose 
position  is  capable  of  a  very  considerable  range  of  adjustment. 
Whatever  form  of  reflector  be  employed,  it  is  always  an  advantage 
to  be  able  to  adjust  its  position  not  merely  by  rotation  but  by  lateral 
and  longitudinal  movement  in  the  tube.  This  is  important,  not  only 
for  the  purpose  of  securing  illumination  at  the  precise  incidence  best 
suited  for  showing  any  particular  feature,  but  also  for  the  purpose 
of  eliminating  that  most  fruitful  source  of  difficulties — internal 
reflections  from  the  lenses  of  the  objective. 

Two  further  features  of  the  mechanical  design  are  of  some  impor- 
tance. The  first  of  these  is  the  provision  for  a  large  working  distance 
between  stage  and  objectives.  This  is  necessary  not  only  to  provide 
for  the  examination  of  thick  specimens,  but  also  because  for  many 
purposes  the  use  of  long  focus  objectives  is  necessary.  This  latter 
aspect  of  metallurgical  work  is  assuming  increasing  importance  at 
the  present  time  owing  to  the  fact  that  the  study  of  macro-structures 
is  now  demanding  much  greater  attention.  In  many  cases  these 
macro-structures  are  large  enough  to  be  photographed  with  an 
ordinary  camera  or  even  to  be  reproduced  by  means  of  direct  contact 
printing.  There  are,  however,  many  conditions  in  which  the  macro- 
structure  is  still  sufficiently  small  to  require  magnifications  of  from 
2  to  10  diameters,  and  it  is  very  convenient  for  those  who  are  not 
in  a  position  to  set  up  a  separate  apparatus  for  this  purpose  if  their 
metallurgical  microscope  is  capable  of  being  used  with  long  focus 
objectives   working   either  with   or   without    an   eye-piece. 

Another  matter  of  some  convenience  in  the  metallurgical  micro- 
scope is  the  provision  of  a  complete  rotation  of  the  stage  together 
with  a  simple  centering  device  attached  either  to  the  stage  or  to  the 
nose-end  of  the  body  tube.  Rotation  of  the  specimen  is  important 
for  two  reasons: — In  the  first  place  under  oblique  illumination  the 
aspect  of  an  .etched  surface  varies  in  a  most  instructive  manner  with 
varying  incidence  of  the  light,  and  it  is  sometimes  convenient  to 
apply  coloured  illumination  from  two  or  more  directions,  and  to 
be  able  to  rotate  the  specimens  under  such  illumination.  In  the 
second  place,  when  a  vertical  illuminator  is  used  which  covers  one- 
half  of  the  aperture  of  the  objectives,  the  resolving  power  is  much 
greater  in  the  direction  parallel  to  the  edge  of  the  illuminator  than 
in  the  direction  at  right  angles  to  it. 

Consequently  in  examining  such  a  structure  as  finely  laminated 
pearlite,  this  may  appear  uniform  or  "  sorbitic  "  when  viewed  in 
the  one  position,  while  it  becomes  clearly  resolved  into  laminae 
when  turned  through  a  right  angle.  This,  of  course,  applies  mainly 
to  work  at  high  magnifications  under  lenses  of  large  resolving  power. 

Turning  to  the  optical  equipment  of  the  metallurgical  microscope, 
there  can  be  no  question  that  the  requirements  of  metallurgy  demand 
the  best  and  even  more  than  the  best  that  optical  achievements  can 


130  THE     METALLURGICAL     MICROSCOPE: 

provide.  The  requirements  themselves  are  mainly  those  common 
to  all  microscopic  work  of  the  most  exacting  kind.  In  regard  to 
the  provision  of  the  most  critical  definition,  the  highest  possible 
resolving  power  and  the  largest  and  flattest  field,  together  with  the 
greatest  possible  approach  to  freedom  from  colour  and  the  elimina- 
tion of  differences  of  actinic  and  visual  focus,  hitherto  tHe  best 
appo-chromatic  lenses  have  provided  the  nearest  approach  to  a 
fulfilment  of  these  requirements.  Metallurgical  progress,  however, 
undoubtedly  tends  increasingly  to  the  production  of  materials  having 
an  extremely  minute  micro-structure,  and  the  differentiation  of 
these  and  the  reading  of  their  life  history  from  their  structure,  makes 
increasing  demands  upon  the  resolving  power  of  our  lenses.  The 
provision  of  a  resolving  power  which  should  allow  the  employment 
of  a  much  higher  useful  magnification  becomes,  therefore,  of  very 
considerable  practical  importance.  Whether  or  not  such  an  achieve- 
ment is  within  the  range  of  possibility  is  a  matter  for  the  optician 
rather  than  the  metallurgist.  The  difficulties  of  the  problem  must, 
however,  be  very  fully  recognised ;  one  of  the  most  important,  no 
doubt,  resides  in  the  difficulty  of  finding  an  immersion  liquid,  of 
very  much  higher  refractive  index  than  the  cedar-wood  oil  commonly 
employed.  The  use  of  monobromonaphthalen©  immersion  objectives 
has  been  tried,  but  they  do  not  appear  to  have  achieved  any  wide- 
spread use.  An  effort  has  also  been  made  to  meet  this  requirement 
by  the  use  of  light  of  much  shorter  wave-length.  The  author  has 
spent  a  considerable  amount  of  time  in  endeavouring  to  use  the  Zeiss 
ultra-violet  microscope  for  metallurgical  purposes,  and  has  succeeded 
in  obtaining  a  few  micrographs  by  this  means.  He  has,  however, 
abandoned  his  efforts,  because  the  expenditure  of  time  required  was 
much  too  great,  while  the  results  themselves  were  not  particularly 
satisfactory.  One  of  the  main  difficulties  in  his  experience  arose 
from  the  internal  scattering  of  the  ultra-violet  light  and  the  occur- 
rence of  fluorescence  within  the  microscope  tube.  Even  should  it 
be  possible  to  overcome  these  difficulties,  a  process  which  is  entirely 
photographic,  and  in  which  the  systematic  visual  examination  of 
relatively  large  area  of  specimens  is  impossible,  does  not  promise  a 
very  large  range  of  utility. 

Reverting  to  the  requirements  for  objectives  of  the  ordinary  type 
intended  for  metallurgical  use,  there  is  one  point  which  requires 
special  emphasis  and  attention.  Clear  images,  whether  visual  or 
photographic,  can  only  be  obtained  if  serious  reflections  of  light  from 
the  back  surface  of  the  objectives  can  be  avoided.  As  has  been 
indicated  above,  this  is  partly  a  question  of  careful  adjustment  of 
the  light  and  of  the  illuminator.  With  the  best  of  facilities  in  that 
direction,  however,  the  author's  experience  has  shown  very  clearly 
that  different  lenses  of  the  same  focal  length  differ  very  widely  in 
respect  of  this  matter  of  internal  reflections.  This  appears  to  be 
a  question  of  the  shape  of  the  back  lens  of  the  objective,  and  especially 
of  the  outer  surface.  Where  this  is  plane  it  appears  to  be  possible 
to  catch  the  whole  of  the  reflected  light  on  the  mirror  or  prism  of 
the  illuminator,  but  where  the  back  surface  is  convex  this  becomes 
impossible,  and  a  milky  image  is  very  apt  to  result. 

In  regard  to  eye-piece  requirements  for  metallurgical  work,  these 
do  not  appear  to  differ  from  those  of  other  microscopical  purposes; 
there  is,  however,  from  the  user's  point  of  view,  a  distinct  objection 


WALTER    ROSENHAIN  131 

to  the  use  of  eye-pieces  such  as  the  compensating  eye-piece  of  Zeiss, 
which  can  only  be  used  with  a  particular  series  of  objectives.  Unless, 
therefore,  such  an  arrangement  is  really  essential  to  allow  the  best 
results  to  be  obtained,  it  will  be  very  much  preferable  to  have 
eye-piec€g  and  objectives  self-contained  and  interchangeable,  not  only 
with  other  lenses  of  the  same  series,  but  as  nearly  as  may  be 
universally.  It  may  be  desirable  to  state  from  the  author's  practice 
and  experience  the  most  useful  focal  lengths  for  objectives  and 
magnifications  for  eye-pieces.  It  should  perhaps  be  said  that  it  is 
not  suggested  that  any  rigid  standardisation  of  magnifications  should 
be  adopted  by  metallurgists.  While  a  certain  degree  of  uniformity 
of  practice  and  especially  the  avoidance  of  odd  magnifications  are 
no  doubt  desirable,  any  attempt  to  tie  down  microscopists  to  a  few 
specified  magnifications  is  eminently  undesirable,  since  the  magnifica- 
tion for  each  subject  should  be  chosen  specifically  to  suit  that  subject. 
A  range  of  objectives  and  eye-pieces  is,  therefore,  in  the  author's 
opinion,  desirable,  which  will  allow  of  almost  any  desired  magnifica- 
tions being  obtained  in  a  satisfactory  manner,  that  is,  by  use  of  an 
objective  of  adequately  resolving  power  and  without  employing  a 
high  eye-piece  or  an  unduly  extended  camera,  where  photographs 
are  concerned. 

The  lenses  ordinarily  used  by  the  author  have  focal  lengths  of:  — 
16  mm.  I 
8  mm.  rdry  series. 
4  mm.  ) 

2  mm.  ,    .,   . 

o  oil  immersion. 

3  mm.  I 

Eye-pieces — x  8,    x  12,    x  18. 

These  lenses  have  been  used  because  they  have  been  commercially 
available  in  those  makes  which  have  in  the  past  produced  the  finest 
results.  So  far  as  the  objectives  of  the  dry  series  are  concerned, 
the  focal  lengths  stated  fulfil  all  ordinary  requirements,  although 
a  4  mm.  dry  objective  is  not  easy  to  use  and  requires  a  great  deal 
of  stopping  down  of  the  beam  of  incident  light.  For  this  reason, 
the  author,  some  time  ago,  suggested  the  desirability  of  an  immersion 
lens  of  from  5  to  7  mm.  focus.  This  would  have  the  great  advantage 
of  affording  a  greater  depth  of  focus  than  the  4  mm.  dry  objective, 
but  it  might  prove  difficult  to  use  in  a  horizontal  position  unless  a 
special  device  were  provided  for  holding  the  oil  in  place. 

With  regard  to  the  immersion  objectives,  that  which  has  given 
the  finest  results  for  the  highest  magnifications  in  the  author's 
practice,  has  been  a  lens  of  3  mm.  focus  with  N.A.  1.40.  Unfor- 
tunately, these  lenses  are  very  delicate  in  use,  and  require  not  only 
protection  from  mechanical  injury,  but  also  from  any  agency  which 
affects  the  cement  with  which  the  front  lens  is  attached  to  the  mount 
and  from  prolonged  exposure  to  contact  with  immersion  oil.  If 
the  latter  is  not  of  precisely  the  right  quality,  this  is  alone  sufficient 
to  do  damage.  If  this  oil  is  wiped  away  very  gently  with  a  soft  cloth 
and  the  surface  of  the  lens  is  then  wiped  lightly  with  an  old  hand- 
kerchief slightly  moistened  with  benzol,  damage  to  the  cement  may 
be  avoided  for  a  long  time. 


132 


THE     METALLURGICAL     MICROSCOPE 


Beyond  the  objectives  named  above,  a  demand  exists,  and  is 
becoming  increasingly  important,  as  indicated  above,  for  first-class 
objectives  of  long  focus.  The  author  would  welcome  such  objectives 
having  focal  lengths  of  30  mm.,  50  mm.  and  75  mm.,  suitable  mainly 
for  photographic  purposes.  It  would,  however,  be  an  advantage  if 
they  could  be  designed  to  work  with  a  low  power  eye-piece  so  that 
they  could  also  be  used  for  visual  work 

The  accessories  required  in  metallurgical  microscopy  are  of  some 
importance.  A  satisfactory  illuminant  is  essential  to  all  good  w^ork 
of  this  kind.     For  visual  purposes,  the  requirements  are  easily  met. 


Fig.  I. 


since  it  is  only  necessary  to  place  opposite  to  the  lateral  aperture  of 
the  illuminator  an  uniform  source  of  light  having  a  reasonable  area 
(about  2  centimetres  in  diameter).  Such  a  source  of  light  may  be 
obtained  by  placing  a  suitable  burner  or  electric  lamp  behind  either 
very  finely  ground  glass  or  a  thin  piece  of  opal  shade.  If  the 
luminous  surface  thus  produced  is  placed  to  one  side  of  the  micro- 
scope in  such  a  position  that  its  distance  from  the  illuminator  mirror 
is  equal  to  the  distance  from  that  mirror  to  the  back  focus  of  the 
objective,  the  result  is  an  approach  to  the  conditions  of  "  critical 
illumination,"  and  for  visual  purposes  these  are  certainly  the  best 
conditions  obtainable.  This  arrangement  has  the  further  advantage 
that  no  lenses,  condensers,  etc.,  are  required,  and  that  an  iris 
diaphragm  placed  just  outside  the  illuminator  aperture  is  all  that 
is  needed  to  regulate  the  illumination.  The  whole  arrangement  can 
be  very  simply  made  by  mounting  the  lamp  with  a  short  external 
tube  through  which  the  light  passes  to  the  illuminator,  the  rest  of 


WALTER    ROSENHAIN  13^ 

the  lamp  being  enclosed  in  a  light,  tight,  but  suitably  ventilated, 
case.  If  the  lateral  tube  through  which  the  light  passes  is  made  of 
the  right  length,  all  that  is  necessary  for  setting  up  the  illuminating 
arrangement  is  to  switch  on  the  lamp  and  to  place  the  small  tube 
almost  but  not  quite  in  contact  with  the  rim  of  the  iris  diaphragm 
outside  the  illuminator.  A  diagrammatic  section  of  this  whole 
arrangement  is  given  in  Fig.  1,  and  a  photograph  is  shown  in  Fig.  2. 

For  photographic  purposes,  the  intensity  of  the  illumination 
obtainable  in  this  way  is  not  large  enough  to  be  convenient.  The 
author  has  endeavoured  to  use  one  of  the  small  tungsten  arc-lamps 
known  as  ''  Pointolite,"  as  the  source  for  critical  illumination  in 
photography,  by  placing  the  lamp  itself  in  the  conjugate  focu^ 
position.  But  with  the  largest  size  of  this  type  of  lamp  at  present 
available,  the  illuminated  area  is  not  large  enough.  It  is  to  be 
hoped,  however,  that  a  larger  form  of  this  lamp  may  become  avail- 
able, and  in  that  case  it  will  be  possible  to  carry  out  the  best  kind 
of  micrographic  work  without  the  use  of  a  system  of  condensers, 
such  as  are  employed  at  present. 

The  arrangements  for  fine  focussing  of  the  microscope  when  used 
for  photographic  purposes  frequently  present  imperfections  which  are 
annoying  in  use,  and  are  liable  to  lead  to  the  loss  of  photographic 
material.  Whether  gearing  or  a  cord  serving  as  a  belt  are  employed, 
there  is  always  apt  to  be  some  degree  of  lateral  pull  applied  to  the 
microscope  when  the  fine  adjustment  head  is  turned  by  the  operator 
working  from  the  screen  end  of  the  camera.  The  author  has  devised 
a  very  simple  means  of  avoiding  this  difficulty  and  of  leaving  the 
microscope  free  as  soon  as  the  operator's  touch  is  removed  from  the 
focussing  rod.  For  this  purpose,  the  focussing  rod,  extending  along 
the  length  of  the  camera,  operates  by  means  of  a  small  belt,  a 
rotating  spindle  attached  to  an  independent  bearing  carries  on  a 
separate  stand.  This  rotating  spindle  is  so  placed  as  to  be  axial 
with  the  fine  adjustment  of  the  microscope,  in  whatever  position 
this  may  be  situated.  The  end  of  the  spindle  nearest  the  microscope 
merely  carries  a  cross-piece  consisting  of  a  thin  rod.  Fixed  to  the 
fine  adjustment  head  of  the  microscope  itself  is  a  light  tube  of  brass 
or  aluminium.  In  this  tube  are  two  longitudinal  slots  diametrically 
opposite  one  another.  The  independent  spindle  above  mentioned 
runs  down  the  axis  of  this  tube,  but  the  transverse  rod  has  its  ends 
projecting  through  the  slots  of  the  tube,  the  slots  being  made  a 
little  wider  than  the  diameter  of  the  rod.  If  now  the  spindle  is 
rotated  bv  the  operator  turning  the  focussing  handle,  no  pull  what- 
ever is  placed  upon  the  fine  adjustment  of  the  microscope — the  motion 
of  the  spindle  being  transmitted  to  the  fine  adjustment  through  the 
slots  in  the  tube.  In  these  circumstances,  a  pure  turning  moment 
or  torque  is  applied  to  the  fine  adjustment,  so  that  there  is  no 
tendency  to  displace  the  microscope.  Further,  if  the  belt  connecting 
the  focussing  handle  to  the  moving  spindle  is  slightly  elastic,  the 
moment  the  pressure  of  the  operator's  hand  is  removed  from  the 
focussing  handle,  the  spindle  and  the  transverse  rod  which  it  carries 
will  spring  back  by  a  very  small  amount.  In  this  way,  the  rod  is 
brought  out  of  contact  with  the  tube,  and  the  microscope  is  left 
entirely   free  from  contact  with  the  focussing  gear. 


134  THE      METALLURGICAL     MICROSCOPE 

If  the  fine  adjustment  of  the  microscope  is  of  the  ordinary  type 
in  which  the  head  has  only  a  very  small  longitudinal  niotion,  the 
tube,  slots,  and  spindle  mentioned  above  also  need  only  be  very 
short.  On  the  other  hand,  in  the  type  of  microscope  designed  by 
the  author,  in  which  the  fine  adjustment  may  be  moved  through 
considerable  distance  by  the  coarse  focussing  of  the  stage,  the  tube, 
slots,  and  spindle  must  have  a  length  of  several  inches.  This  focussing 
device,  which  is  somewhat  difficult  to  describe  in  words,  is  very 
simple  and  efficient  in  action.  It  is  illustrated  in  the  photograph, 
Fig.   3. 

Finally,  reference  may  be  made  to  another  matter  which  some- 
times gives  difficulty  in  metallurgical  microscopy.  This  is  the 
mounting  of  specimens  with  their  surfaces  accurately  at  right  angles 
to  the  optic  axis  of  the  microscope.  Mechanical  levelling  deyices  of 
various  kinds  have  proved  more  or  less  successful,  but  they  all  have 
the  serious  disadvantage  that  the  carefully  prepared  surface  of  the 
specimen  must  be  placed  in  contact  with  some  part  of  the  apparatus, 
and  when  this  is  done  there  is  considerable  risk  of  damaging  the 
surface.  The  author,  therefore,  has  devised  an  optical  levelling 
appliance  in  which  the  surface  of  the  specimen  is  utilised  as  a 
reflector.  The  specimen  is  approximately  mounted  on  a  glass  slip 
by  means  of  plasticine,  wax  or  other  soft  substance.  It  is  then 
placed  under  the  instrument,  and  its  position  is  adjusted  with  the 
fingers  until  the  reflection  is  seen  opposite  a  cross-wire.  When  this 
position  has  been  obtained,  the  specimen  is  accurately  level,  and 
the  manipulation  is  so  easy  that  it  rarely  occupies  more  than  five 
seconds.  A  more  detailed  description  of  this  device  has  been  given 
in  the  author's  paper  on  ''  Some  Appliances  for  Metallographic 
Research."* 


*  Journ.   Institute  of  Metals,   igis,  I. 


Kosenhain.~l. 


F.G.    2. 

Independent  Focussing  Device  applied  to  Metallurgical  Microscope 
as  used  for  Photography. 


Fig.    2. 


NOTES   ON   THE  CONSTRUCTION  AND  DESIGN  OF 
METALLURGICAL  MICROSCOPES. 

By  Prof.  Cecil  H.  Desch,  Glasgow. 


The   use  of  the   microscope    in   the    examination  of   metals,    first 
introduced  by  Sorby  more  tJian  50  years  ago,  has  become  so  wide- 
spread* that  a  microscope  is  now  an  indispensable  item  in  the  equip- 
ment    of     a     metallurgical   works,    whilst     the     recognition     of     its 
importance  to  engineering  works  and  other  places  in  which  metals 
are  employed   for  constructional  purposes  is  rapidly   extending.      It 
is  therefore  essential  to  the  conduct  of  these  industries  that  instru- 
ments should   be   available  which  will   allow   of  the   rapid   and  con- 
venient examination  of    such    metals    as    present    themselves    in    the 
course    of  routine    testing,    whilst     it     is     obviously    desirable     that 
elaborate  and  detailed  investigation  of  specimens  of  special  interest 
should  be  possible.      It  is  quite  true  that  any  ordinary  microscope 
of  good  construction  may  be  used  for  metallographic  work,  provided 
that   the   higher   power  objectives   are   duly   corrected   for   uncovered 
objects,  but  the  increased  convenience  of  a  properly  designed  instru- 
ment is  so  great  as  to  justify  its  use,  even  for  routine  work.     There 
are  now  many  patterns  of  metallurgical  microscopes  on  the  market, 
and   the   following  remarks  are  based  on  an  experience  of  some   12 
or    13   types  of   instrument,  and  the   examination   of   the   details   of 
many   others.      The  writer  has  been  reluctantly  forced   to   the   con- 
clusion   that,    in    spite    of   many  excellent   features    in   some    of    the 
British  microscopes,  the  German  instruments  have  proved  better  in 
use,  and  that  their  superiority  is  more  marked,  the  longer  the  micro- 
scopes are  used.     The  British  designs  are  often  good,  and  the  work- 
manship, so  far  as  the  cutting  of  racks  and  screw-threads,   etc.,   is 
concerned,  is  often  quite  satisfactory,  but  in  the  course  of  prolonged 
use    the    mechanical    arrangements    show    defects,    racks    and   screws 
becoming  loose,  and  the  accurate  focussing  of  high  power  objectives 
becoming   troublesome,   to   an  extent  which  is  not   met  with  in   the 
German  microscopes.      The  cause  of  this  looseness  after  use  appears 
to  be  insufficient  attention  to  the  quality  of  the  metal  employed  in 
construction.      A   rack  cut   in  soft  brass,  however   accurate   at  first, 
becomes    loose    through     wear,    and   no   compensation   by   means   of 
adjusting    screws    can    be    quite    satisfactory.      The    fact    that    such 
screws    are    provided     seems    to  be   a  confession   of  weakness,  since 
the  writer  has  used  a  Zeiss  microscope,  without  such  screws,  for  years 
continuously  without  any  sign  of  play  in  the  mechanical  movements. 
Racks  should   be  cut  in  hard,   incorrodible  metals  or  alloys  instead 
of  in  soft  brass,   whilst  the   pinions  might   also  be  of   much  harder 
metal  than  is  usually  the  case.      It  is  probable  that  manufacturers 
have  been  too  much  guided  by  tradition  in  the  choice  of  the  metals 
to    be    used    in    the   construction    of    scientific    instruments,    witness 
the  tendency,   only   now  disappearing,   to  use  highly  polished   brass 
for  heavy  portions  where  cast  iron  would  serve  the  purpose  equally 
well. 

135 


136     NOTES   ON   THE    CONSTKUCTION    AND    DESIGN 

The  principal  parts  of  the  metallurgical  microscope  may  now  be 
considered  in  succession. 

(a)  The  Stand. — There  is  no  reason  why  the  shape  of  the  medical 

or  biological  microscope  should  be  slavishly  copied  in  the 
construction  of  metallurgical  instruments,  whilst  there  are 
many  reasons  for  choosing  a  different  form,  especially  when 
there  is  a  possibility  of  large  specimens  being  examined. 
The  tripod  form  of  foot,  so  convenient  in  work  by  trans- 
mitted light,  is  awkwardly  in  the  way  when  examining 
metals  and  having  occasion  to  use  the  rackwork  movement 
for  raising  and  lowering  the  stage.  The  Jackson  foot  is 
better,  and  a  heavy  horseshoe  foot  still  better,  as  heavy 
specimens,  such  as  rail  sections,  may  be  laid  on  it  for 
examination  under  low  powers.  This  is  further  facilitated 
by  making  the  bracket  which  holds  the  stage  capable  of 
swinging  to  one  side,  and  leaving  a  clear  space  between 
the  objective  and  the  heavy  horseshoe  foot,  as  in  the  old 
vertical  Reichert  microscope.  Special  forms  of  foot,  as  in 
the  Beck-Rosenhain  microscope,  have  the  advantage  of 
great  rigidity  in  both  the  vertical  and  horizontal  positions. 
This  stand  is  the  most  rigid  of  those  examined.  The  design 
of  Sauveur's  universal  Metalloscope  is  also  unconventional, 
and  appears  to  be  good,  but  the  writer  has  no  actual  experi- 
ence of  it.  For  photographic  work  the  form  adopted  in  the 
Zeiss-Martens  instrument  and  in  Watson's  horizontal  micro- 
scope is  both  convenient  and  steady. 

The  inverted  stand,  due  to  Le  Chatelier,  has  been 
copied  by  several  makers,  but  the  construction  is  apt  to  be 
flimsy,  and  the  writer  has  found  great  difficulty  in  moving 
even  small  specimens  on  the  stage  without  altering  the 
focus,  the  light  arms  which  support  the  optical  parts  being 
liable  to  whip.  This  could  perhaps  be  overcome  by  better 
engineering  design,  and  the  type  is  certainly  preferred  in 
some  works  on  account  of  the  rapidity  with  which  specimens 
can  be  inserted  and  examined.  The  optical  conditions  of 
this  form  are  discussed  below.  It  is  probable  that  for 
the  larger  instruments  to  be  used  for  photography  the 
ordinary  type  of  stand  might  be  departed  from  entirely, 
and  an  arrangement  modelled  on  the  optical  bench  adopted, 
the  various  optical  parts  and  specimen  carriers  being  sup- 
ported in  such  a  way  as  to  move  freely  along  a  heavy  bar 
of  geometrical  form  to  preserve  alignment. 

(b)  Codixc    Adjiixiinini. — The    rack    and    pinion   should   be    geo- 

metrically cut  in  metal  of  sufficient  hardness  to  withstand 
prolonged  usage  without  working  loose.  The  improvement 
in  the  methods  of  gear  cutting  in  engineering  practice  has 
been  so  great  in  recent  years  that  much  would  be  gained 
by  adopting  the  methods  of  marine  engineering  shops  in 
the  instrument  maker's  workshop.  In  large  instruments, 
the  length  of  travel  might  well  be  greater  than  at  present, 
so  as  to  allow  of  a  wide  range  of  objectives,  and  stops 
should  be  provided  at  the  ends  of  the  rack  to  prevent  over- 


OF  METALLURGICAL  MICROSCOPES  137 

racking.  This  is  particularly  desirable  in  students'  micro- 
scopes, as  it  would  prevent  a  common  accident  in  labora- 
tories where  inexperienced  students  use  the  instruments. 

(c)  Fine   A(/ji/st/KCfif. — This   does   not  call    for   much  remark,    as 

there  are  several  good  forms  in  use.  The  speed  is  some- 
times made  too  great  for  comfortable  focussing  of  high 
powers.  The  side  arrangement  of  small  milled  heads  ia 
perhaps  the  most  convenient. 

(d)  Bodf/   Tube. — This  should  be  of  the  short  Continental  form, 

and  preferably  of  wide  diameter.  The  latter  condition  is 
essential  in  instruments  to  be  used  for  photographic  work, 
and  should  always  be  adopted,  but  it  has  also  great  advan- 
tages for  visual  observation,  and  can  be  introduced  without 
interfering  with  the  general  design. 

(e)  T/ie  Sf((f/e. — A  plain  stage  of  fairly  large  size  is  suitable  for 

most  ordinary  work.  It  should  be  provided  with  a  rack- 
work  focussing  movement,  but  a  fine  adjustment  is  un- 
necessary. A  central  hole,  sufficiently  large  to  allow  an 
objective  to  pass  through  it,  allows  of  the  examination 
of  heavy  specimens  resting  on  the  foot,  unless  the  support 
of  the  stage  be  arranged  to  swing  aside  entirely,  as 
mentioned  above.  Levelling  stages  are  a  nuisance,  and 
should  never  be  used.  The  specimen  should  always  be 
levelled  before  placing  on  the  stage,  either  by  means  of 
plasticine  and  one  of  the  usual  mounting  devices,  or  by 
mea,ns  of  Dr.  Rosenhain's  auto-collimating  instrument. 
Mechanical  movements  to  the  stage  are  essential  for  high 
power  work,  and  rotation  is  also  a  very  great  convenience, 
but  when  both  are  provided  the  rotation  should  be  con- 
centric. A  rotating  plate  which  is  carried  by  the  traversing 
movements  is  useless.  When  a  microscope  is  intended  to 
be  used  in  the  horizontal  position,  it  is  desirable  to  provide 
the  mechanical  movements  with  clamping  screws,  as  other- 
wise a  heavy  specimen  may  cause  a  gradual  downward  slip 
during  the  exposure  of  a  photograph,  pulling  down  the 
rackwork  by  its  own  weight.  This  has  often  been  noticed 
when  photographing  at  high  magnifications.  The  rotating 
circle  should  have  a  clamping  screw.  The  Zeiss-Martens 
stand  has  a  very  convenient  rotating  and  traversing  stage^ 
but  the  range  of  movement  is  too  limited. 

The  examination  of  fractures,  large  crystals  in  ingot 
sections,  and  other  things  requiring  very  low  powers  and 
great  distances,  is  troublesome  when  an  ordinary  microscope 
is  used,  and  it  is  often  preferable  to  employ  a  camera 
with  a  landscape  or  copying  lens  instead  of  a  microscope. 
The  telephoto  attachment  of  the  Davidson  microscope  gives 
good  results  in  this  kind  of  work,  and  the  arrangement 
in  the  recent  pattern,  by  which  the  object  is  carried  on 
a  separate  stand,  movable  along  a  base  board,  is  con- 
venient.    On  the  other  hand,  the  writer  does  not  approve 


138     NOTES   ON   THE    CONSTRUCTION    AND    DESIGN 

of  the  "  super-microscope  "  arrangement,  by  which  the 
image  formed  by  one  objective  is  magnified  by  a  second 
objective. 

(f)  The    Vertical   lllumnidtor. — Whilst   the    prism    form    has    the 

advantage  for  visual  work  of  causing  much  less  loss  of 
light  than  the  transparent  plate,  it  is  unsuitable  for  high 
powers,  on  account  of  the  fact  that  it  only  uses  one-half 
of  the  aperture  of  the  objective,  and  is  consequently  liable 
to  produce  false  images  of  fine  structures.  The  same 
objection  applies  to  silvered  half-discs  or  other  similar 
devices.  The  Beck  or  transparent  illuminator  is  the  only 
suitable  form  for  photographic  work  at  any  but  low  mag- 
nifications. The  mistake  is  very  commonly  made  of  fitting 
a  small  cover  glass,  which  only  imperfectly  covers  the  back 
lens  of  the  objective,  into  such  illuminators.  A  plate  of 
larger  size  should  be  used.  Moreover,  cover  glasses  are  not 
accurately  flat,  and  have  no  advantage  except  cheapness 
and  thinness.  A  large,  optically  worked  plate  is  used  in 
the  Conrady-Watson  illuminator  and  in  the  Jackson  and 
Blount  microscope.  The  writer  has  found  the  thin,  square 
plates  used  for  counting  blood  corpuscles  very  suitable, 
being  sufficiently  flat  and  so  thin  as  not  to  produce  doubling 
of  the  image.  The  plate  should  be  capable  of  at  least 
partial  rotation,  and  should  have  a  sufficiently  large  milled 
head  to  allow  of  delicate  adjustment.  Vertical  illuminators 
often  leave  much  to  be  desired  in  regard  to  mechanical 
construction. 

The  inverted  or  Le  Chatelier  type  of  microscope  calls 
for  a  different  form  of  illuminator.  As  usually  constructed, 
the  numerous  reflections  required  tend  to  injure  the  defini- 
tion of  the  image  and  to  cause  loss  of  light.  To  a  great 
extent  this  might  be  obviated  by  better  optical  workman- 
ship, the  prism  being  made  in  one  piece  with  accurately 
ground  faces,  as  in  the  modern  range  finder.  The  possi- 
bilities of  new  optical  arrangements  for  illumination  are 
not  exhausted. 

(g)  The    Objectives. — It    is    now     generally     agreed     that     short 

mounts  are  to  be  preferred  for  metallographic  objec- 
tives. A  high  numerical  aperture  is  necessary  for  the 
highest  powers.  Apochromats  are  usually  recommended  for 
the  medium  and  high  powers,  but  such  objectives  are 
commonly  deficient  in  flatness  of  field,  a  very  desirable 
quality  in  metallographic  work,  and  it  may  be  questioned 
whether  good  achromats,  giving  flat  fields,  are  not  to  be 
preferred  for  photographic  purposes.  It  is  usual  to  insert 
a  colour  screen  when  making  such  photographs,  and  now 
that  screens  which  transmit  so  narrow  a  band  of  the  spec- 
trum that  they  may  be  regarded  as  practically  mono- 
chromatic are  obtainable,  it  seems  of  less  importance  that 
the  colour  correction  of  the  objectives  should  be  perfect. 
Oil  immersion  objectives  are,  of  course,  necessary  for  the 
highest  magnifications. 


OF  METALLURGICAL  MICROSCOPES  139 

(h)  Eye-pieces. — These  give  the  least  trouble  of  all  the  parts  of 
the  microscope,  the  quality  being  usually  satisfactory. 
Projection  eye-pieces  are  to  be  preferred  for  photographic 
work. 

These  few  notes  are  presented  by  way  of  suggestions  for  dis- 
cussion. Each  worker  will  have  formed  some  opinion  on  the  points 
mentioned,  and  a  comparison  of  such  opinions  may  be  of  assistance 
to  manufacturers  in  determining  the  design  of  their  future  instru- 
ments. There  is  a  large  demand  for  metallographic  microscopes  at 
present,  whilst  the  supply  is  very  limited,  and  the  time  seems  appro- 
priate for  a  consideration  of  the  question  whether  improvements 
might  not  be  made  in  the  light  of  experience. 


SOME  NOTES  ON  THE  METALLURGICAL 
PHOTOMICROSCOPE. 

By   J.    H.   G.    MONYPENNY. 

(Chief  of  the  Research  Laboratory,  Brown  Bayley's  Steel 

Works,  Ltd.) 


The  technique  of  the  photomicrography  of  metals  has  advanced 
very  much  during  the  last  ten  or  twenty  years,  but  there  are  still 
very  marked  evidences  that  many  who  take  up  microscopic  work 
in  connection  with  metallurgy  appear  to  study  the  microscope  itself 
either  not  at  all  or  only  to  a  very  small  extent.  The  consequence 
is  that  statements  are  made  about  the  structures  of  various  metals 
which  are  not  correct;  the  presence  in  sections  of  minute  particles 
or  membranes  of  constituents  other  than  those  stated  to  be  there 
has  been  missed  simply  because  the  operator  did  not  know  how  to 
use  his  microscope  properly.  Again,  photographs  are  published 
which  have  only  a  slight  resemblance  to  the  structures  photographed, 
in  some  cases  the  definition  is  so  bad  that  the  reproductions  are 
not  worth  the  paper  they  are  printed  upon.  One  has  only  to 
look  through  the  Journals  of,  for  example,  the  Iron  and  Steel 
Institute  to  see  how  true  this  is. 

Even  when  a  metallurgist  has  devoted  a  considerable  time  to  the 
study  of  the  microscope,  mistakes  may  arise  in  the  interpretation  of 
structures.  For  example,  it  has  been  stated  that  iron  carbide 
(cementite)  is  not  attacked  by  sodium  picrate  when  its  thickness  is 
less  than  0.001  mm.  (this  statement  is  repeated  in  one  of  the  most 
recently  published  treatises  on  metallography).  This  is  quite  incor- 
rect. Not  only  are  the  carbide  laminae  of  pearlite  attacked  when 
considerably  thinner  than  this  (certainly  not  more  than  one-tenth  of 
the  thickness  mentioned),  but  also  the  minute  granules  in  sorbite, 
produced  on  tempering  hardened  steel  at  about  600°  C.  Possibly 
the  reason  the  above  misstatement  was  originally  made  was  either 
that  the  aperture  of  the  objective  used  was  not  sufficiently  high  or 
that  the  resolving  power  was  much  reduced  by  the  use  of  a  prism 
illuminator  or  both. 

In  the  following  pages  the  author  has  attempted  to  set  out 
some  of  the  conditions  which  appear  to  him  to  be  necessary  to  secure 
good  photomicrographs  of  metals  and  the  means  he  has  devised  from 
time  to  time  to  fulfil  these  conditions. 

(a)  The  lllmniiKint  and  Condensing  Si/stem. — Few  who  have  had 
any  experience  in  photomicrography  will  disagree  with  the  statement 
that  the  illumination  of  the  specimen  is  of  fundamental  importance 
in  the  production  of  a  good  photomicrograph.  Good  illumination 
should   comply   with   the   four   following   conditions:  — 

(1)  The  whole  surface  which  is  required  to  be  reproduced  should 

be  evenly  illuminated. 

(2)  The  lighting  should  be  such  that  the  whole  aperture  of  the 

objective  may  be  utilised. 

140 


J.    H.     G.     MONYPENNY  141 

(3)  The  wave-length  of  the  light  used  should  be  that  for  which 

the  objective  is  corrected. 

(4)  The  wave-length  of  the  light  used  should  be  suitable  to  the 

colour  of  the  specimen. 

Fortunately,  in  most  metallurgical  work  the  specimens  rarely 
call  for  the  use  of  any  definite  colour  of  light,  and  hence  the  neces- 
sity for  complying  with  condition  No.  4  does  not,  in  general,  arise. 
This  is  a  great  advantage,  as  it  enables  one  to  adjust  the  colour  of 
the  light  to  fulfil  condition  (3).  In  other  branches  of  microscopic 
work  {e.g.,  in  connection  with  Biology),  it  may  easily  occur  that 
the  requirements  under  conditions  (3)  and  (4)  are  opposite,  and 
then  the  photomicrographer  has  either  to  use  a  colour  for  which  the 
objective  is  not  adequately  corrected  or  which  is  not  best  suited  to 
the  specimen. 

In  metallurgical  work  the  objective  acts  as  condenser,  and  it  is 
well  known  that  to  produce  "'  critical  illumination  "  the  illuminant 
should  be  focussed  on  the  section,   and  should  therefore  occupy  the 


Fig.  I. 

Diagram  showing-  conditions 
for  critical  illumination. 


position  L  shown  in  Fig.  1,  so  that  the  distances  x  and  y  are  equal. 
Practically  it  is  found  that  the  illuminant  may  be  to  some  extent 
out  of  focus  without  producing  any  bad  effect,  providing  the  objective 
transmits  a  full  solid  cone  of  light.  This  may  be  judged  by  looking 
at  the  back  lens  of  the  objective  after  removing  the  eye-piece,  when 
(the  iris  on  the  vertical  illuminator  being  open)  the  back  lens  will 
be  full  of  light  and  evenly  bright  if  critical  illumination  has 
been  obtained.  The  fact  that  the  illuminant  may  be  to  some  extent 
out  of  focus  is  of  great  value  in  allowing  one  to  get  rid  of  the  effect 
of  small  surface  markings  on  the  illuminant  itself. 

Placing  the  illuminant  in  such  a  position  has  obvious  disadvan- 
tages, e.g.,  it  would  be  inconveniently  close  to  the  microscope  and 
the  heating  effect  produced  on  the  latter  would  be  considerable. 
Again,  to  illuminate  the  whole  visible  field  in  the  microscope,  the 
illuminant  would  have  to  have  an  evenly  bright  area  at  least  as 
large  as  the  diaphragm  of  the  ocular  in  use  (say  7  to  8  mm.), 
obviously,  therefore,  illuminants  of  small  area  {e.g.,  Nernst  or  Arc 
lamps)  could  not  be  used  in  this  way. 


142  SOME    NOTES    ON    THE    METALLURGICAL 

As  regards  the  illuminant,  the  author  prefers  the  500  C.P. 
Pointolite  Lamp  (a  tungsten  arc  lamp  made  by  the  Ediswan  Co.)  to 
any  other  type  of  lamp  made;  the  intensity  of  the  light  is  very 
great,  and  it  is  absolutely  steady.  It  requires  direct  current,  and 
where  this  is  available  the  author  has  no  hesitation  whatever  in 
recommending  it  in  preference  to  any  other  form  of  illuminant. 
Previous  to  this  lamp  being  on  the  market  (about  1917),  the  author 
had  tried  a  Nernst  lamp,  an  arc  lamp,  and  lime-light,  and  had  for 
some  years  used  the  last  in  preference  to  the  first  two.  The  intensity 
of  the  light  given  by  the  lime  is  not  nearly  so  great  as  with  the  arc 
lamp,  but  on  the  other  hand  it  is  perfectly  steady,  and  this  cannot 
be  said  of  the  arc  lamp. 

Coming  to  the  condensing  system,  probably  one  of  the  simplest 
arrangements  is  that  shown  in  Fig.  2.  In  this  case  the  condenser 
C  forms  an  enlarged  image  of  the  illuminant  L  at  Li,  the  correct 
distance  from  the  illuminator  to  give  critical  illumination  as  described 
earlier.  By  this  means  the  area  of  the  illuminant  is  spread  out, 
and  with,  for  example,  lime-light,  one  may  obtain  perfectly  even 
illumination  even  when  photographing  at,  say,  5  or  6  times  the 
initial  power  of  the  objective.     The  effect  of  any  slight  irregularities 


^ 


Fig.  2. 
Condenser  System  No,   i. 

on  the  surface  of  the  illuminant  may  be  avoided  by  forming  the 
image  Li  about  1  in.  nearer  the  microscope  than  its  correct  position, 
as  mentioned  earlier.  It  is  advisable  to  have  an  iris  diaphragm 
at  Li  and  to  close  it  until  only  slightly  more  than  the  area  to  be 
photographed  is  illuminated.  This  cuts  off  a  lot  of  stray  light  which 
would  otherwise  reduce  the  contrast  by  giving  a  general  fog  over 
the  whole  section.  This  iris  should  be  focussed  fairly  accurately 
on  the  section,  otherwise  there  is  a  gradual  falling  off  of  the  illumina- 
tion on  the  edge  of  the  field  instead  of  a  sharply  defined  edge  to 
the  illuminated  area. 

While  this  method  is  perfectly  satisfactory  for  use  with  lime-light 
— the  author  has  taken  several  hundred  photographs  at  magnifica- 
tions ranging  from  30  to  2,000,  using  an  arrangement  of  this 
description — it  has  certain  drawbacks;  for  example,  a  great  deal 
of  light  is  wasted,  and  with  an  illuminant  of  small  area  it  is  difficult 
to  fill  the  field  evenly  unless  a  very  long  optical  bench  is  used. 

These  defects  are  obviated  in  the  following  arrangement.  In 
this,  advantage  is  taken  of  the  fact  that  if  a  biconvex  lens  is  held 
between  the  eye  and  a  light  {e.g.,  a  candle  flame)  in  such  a  manner 
that  the  eye  and  flame  occupy  the  position  of  conjugate  foci  then  the 
lens  itself  will  appear  to  the  eye  as  an  evenly  illuminated  disc,  and 


PHOTOMICROSCOPE :    J.    H.    G.    MONYPENNY         143 

for  the  purposes  of  microscopic  work  may  be  looked  upon  as  an 
illuminant.  There  is  one  essential  point,  however,  the  beam  of  light 
thrown  by  the  lens  must  cover  the  whole  surface  of  the  back  lens 
of  the  objective,  otherwise  some  of  the  aperture  of  the  latter  is  lost. 

In  Fig.  3,  A  represents  a  lens  of  about  6  in.  focus,  placed  at 
the  requisite  distance  from  the  microscope  to  give  critical  illumina- 
tion, as  described  earlier;  the  objective  therefore  uses  this  lens  as 
the  illuminant,  and  forms  an  image  of  it  in  the  field  (if  any  slight 
scratches  are  present  on  the  surface  of  the  lens,  it  should  be  moved 
very  slightly  out  of  focus).  Condenser  B  (about  25^  in.  focus  and 
2j/8   in-    diameter)    is  placed   at  such    a    distance   from   A  that    the 


■  Troujtl 


Fig.  3- 
Condenser  System  No.  2. 

latter  focusses  B  approximately  on  the  objective.  Finally  B  forms 
an  enlarged  image  of  the  illuminant  on  A.  This  sounds  rather 
complex,  but  the  result  is  that  if  the  eye  be  placed  at  A,  B  appears 
as  an  even  disc  of  light,  and  similarly  to  an  eye  placed  against 
the  objective  A  appears  as  an  even  disc.  As  mentioned  above,  the 
only  point  that  must  be  carefully  watched  is  that  the  image  of  B- 
formed  by  A  on  the  objective  must  at  least  cover  the  back  lens  of 
the  latter.  The  figures  given  above  refer  to  the  author's  arrange- 
ment, and  in  this  case  the  image  is  rather  more  than  two-thirds  of 
an  inch  diameter,  and  therefore  amply  large  enough  for  any  objective- 
in  use.  Condenser  A  need  not  be  more  than  1  in.  diameter,  but 
the  image  of  the  light  formed  on  this  lens  by  B  should  completely 
fill  it.  This  condenser  (A)  should  have  an  iris  diaphragm  for 
limiting  the  area  of  the  field  illuminated  as  described  earlier.  An 
iris  is  not  required  on  condenser  B,  except  for  centering  and  focussing 
purposes. 

Using  this  arrangement,  one  is  able  to  illuminate  evenly  the- 
section,  and  also  provide  critical  illumination.  It  will  be  found 
that  if  condenser  A  is  used  without  B,  unless  the  illuminant  has- 
a  large  area  or  is  placed  very  near  to  A,  the  conditions  of  critical 
illumination  are  not  obtained,  the  beam  of  light  not  being  sufiicieni 
to  fill  the  back  lens  of  the  objective.  The  effect  is  equivalent  to- 
cutting  down  the  aperture  of  the  objective,  with  all  the  bad  effects 
produced  thereby.  The  author  has  seen  more  than  one  metallurgical 
photomicroscope  in  use  in  which  this  condition  of  things  has  obtained. 

It  is  obvious  from  Fig.  3  that,  using  an  illuminant  of  small  area, 
such  as  the  Pointolite,  condenser  B  should  have  a  short  focus,  and 
also  the  better  corrected  it  is  the  more  light  will  be  available — the 
author   uses   the   Watson-Conrady   condenser,    and    finds    it   excellent 


144  SOME    NOTES    ON    THE   METALLURGICAL 

for  the  purpose.  Doubtless  other  opticians  could  supply  similarly 
corrected  condensers.  Condenser  A  has  a  longer  focus  (the  actual 
focal  length  will  depend  on  the  tube  length  employed  and  the  distance 
between  the  condensers),  and  as  it  need  only  be  of  small  diameter, 
such  a  high  degree  of  correction  as  in  B  does  not  seem  necessary. 

(b)  The  Vertical  Illuminator. — The  author  does  not  propose  to 
enter  into  the  question  of  prism  versus  disc  illuminator  to  any 
great  extent.  The  fact  that  with  high  powers  a  disc  illuminator 
must  of  necessity  give  and  does  give  far  better  definition  and 
much  more  detail,  is  evident  to  anyone  who  has  studied  the  subject 
or  who  has  critically  compared  the  two  illuminators  with  the 
same  lens  on  the  same  field.  Examples  of  this  have  been  pub- 
lished independently  by  Rosenhain  and  by  Benedicks;  the  author 
(who  was  unaware  of  Rosenhain' s  work)  investigated  the  matter 
before  Benedicks'  paper  was  published,  and  his  results,  though 
not  published,  were  communicated  to  some  of  his  friends.  It  is 
probably  not  so  well  known,  however,  that  the  results  with  low 
power  lenses  show  the  same  differences,  though  not  in  so  marked 
a  manner.  The  differences  produced  for  any  given  objective  depend 
on  the  fineness  of  detail  in  the  section.  Other  things  being  equal, 
the  superiority  of  the  disc  becomes  more  marked  as  the  detail  to 
be  reproduced  becomes  finer.  The  author  always  uses  a  disc 
illuminator  even  with  the  lowest  powers,  except  under  exceptional 
circumstances.  (Such  may  arise  in  a  low  power  photograph  of  an 
object  showing  no  fine  detail  and  possessing  very  little  con1:rast.) 

While,  however,  the  author  is  convinced  of  the  superiority  of 
the  disc  illuminator,  he  has  found  that  many  individual  discs  are 
very  poor  specimens,  and  in  this  respect  he  would  urge  on  instrument 
makers  the  necessity  for  more  care  in  choosing  material  for  the 
"  disc."  In  many  cases  the  glass  is  so  thick  and  so  uneven  that 
the  definition  of  even  a  low  power  lens  in  absolutely  ruined.  The 
author  a  few  years  ago  received  an  illuminator  from  one  of  the 
largest  microscope  makers  in  England — he  returned  it  at  once  with 
a  note  that  it  was  useless  owing  to  the  bad  glass  (giving  them  details 
of  the  behaviour  of  the  disc).  The  illuminator  was  returned  to 
him  with  a  fresh  glass  fitted,  which  was  every  bit  as  bad  as  the  first 
one.  The  effect  of  this  bad  disc  is  shown  in  Figs.  4  and  5.  These 
represent  the  same  field  taken  with  the  same  objective,  ocular,  plate, 
and  screen,  in  fact  every  condition  the  same,  except  that  in  Fig.  4 
the  disc  was  a  good  one,  while  in  Fig.  5  the  disc  was  the  bad  one 
mentioned  above.  It  was  absolutely  impossible  to  get  any  sharper 
definition  than  that  shown  in  Fig.  5.  The  author  suggests  that  this 
is  a  point  to  which  instrument  makers  should  give  far  more  attention 
than  they  do — there  is  no  doubt  at  all  that  many  of  the  glasses 
supplied  with  disc  illuminators  are  far  too  thick,  and  they  are  often 
uneven.  It  is  evident  also  that  the  discs  cannot  be  very  carefully 
examined  by  the  makers  before  being  put  into  stock,  otherwise 
such  defects  would  be  quickly  discovered. 

It  may  be  of  interest  to  mention  that  the  bad  disc  mentioned 
above  had  far  more  effect  on  the  performance  of  the  1  in.  and  \  in. 
objectives  than  on  the  l-6th,  probably  owing  to  the  larger  area 
of  the  glass  used  by  the  former  lenses.     Probably  this  fact  and  the 


PHOTOMICKOSCOPE :    J.    H.    G.    MONYPENNY         145 

prevalence  of  unsuitable  material  for  the  disc  may  account  for  the 
opinion  frequently  held  that  for  such  low  powers  the  prism  illuminator 
gives  the  better  effect.  A  prism  would  give  a  much  better  result 
man  Fig.   5. 

There  are  three  other  points  in  connection  with  the  vertical 
illuminator  that  the  author  would  like  to  mention. 

(1)  The  illuminator  is  rarely  made  large  enough  to  fill  the  back 
lenses  of  the  lower  power  objectives — for  example,  the  24  mm. 
N.A.  .30  or  the  12  mm.  N.A.  .65.  The  only  disc  illuminator  known 
to  the  author  which  is  large  enough  for  these  lenses  is  the  large 
pattern  made  by  Watsons,  London. 

(2)  The  illuminator  should  be  fitted  with  an  iris  diaphragm, 
which  should  have  some  type  cf  centering  adjustment.  ihis  iris 
is  used  in  the  same  manner  as  the  iris  on  a  substage  condenser,  and 
should  therefore  close  absolutely  central  with  the  objective.  Such 
adjusting  movements  as  are  found  on  the  Watson  pattern  mentioned 
above  are  suitable. 

In  connection  with  the  prism  illuminator  it  is  curious  that  in 
the  pattern  as  ordinarily  sold,  the  iris  diaphragm  closes  concentrically 
with  the  middle  of  the  front  face  of  the  prism,  and  therefore  with 
a  line  about  one-eighth  of  an  inch  from  the  centre  line  of  the 
objective.  The  iris  should,  of  course,  close  concentrically  with  the 
middle  of  the  bottom  edge  of  the  prism,  as  shown  in  Fig.  6,  where 
A  indicates  the  centre  line  of  the  iris  as  ordinarily  fitted,  and  B 
the  line  on  which  it  should  close.  The  effect,  on  the  performance  of 
an  objective  of  short  focal  length,  of  closing  the  iris  about  line  A 
can  be  imagined. 

(3)  One  of  the  great  defects  of  the  disc  illuminator,  especially 
with  the  lower  power  objectives,  is  the  presence  of  flare  due  to 
the  reflection  of  the  incident  light  by  the  outer  surface  of  the  back 
combination.  This  is  a  matter,  however,  which  could  probably  be 
remedied  to  a  great  extent  by  the  objective  designer.  It  will  be 
obvious  that  (other  things  being  equal),  the  more  convex  this  back 
surface  is,  the  less  the  amount  of  flare,  since  more  of  the  reflected 

light  will  ibe  reflected  on  to  the  inner  surface  of  the  draw  tube 
(and  be  absorbed  by  the  blackened  surface),  and  less  will  reach  the 
eye-piece.  The  author  has  one  lens  in  his  possession  in  which  the 
back  surface  is  apparently  slightly  concave,  and,  owing  to  the 
amount  of  flare  caused  thereby,  the  lens,  though  a  magnificent  one 
from  every  other  point  of  view  (it  is  the  Zeiss  12  mm.  Apochromat 
N.A.  .65)  is  not  so  valuable  metallographically.  The  author  would 
suggest  that  this  is  a  point  to  which  opticians  could  usefully  give 
their   attention  in  computing   objectives  for  metallurgical  work. 

It  is,  of  course,  obvious  that  with  the  present  method  of  con- 
struction of  objectives  there  is  much  more  likelihood  of  flare  being 
obtained  with  apochromatic  objectives  than  with  achromatic — 
especially  with  the  lower  powers.  In  the  former  the  back  com- 
bination has  very  little  magnifying  power,  its  function  being  chiefly 
that  of  correcting  the  aberrations  and  other  faults  of  the  front 
combinations.  In  the  simpler  achromatic  the  back  combination 
frequently  has  a  considerable  magnifying  power.  The  more  convex 
back  surface  of  the  latter  type  of  lens  will  therefore  cause  less 
flare  than  the  less  convex  surface  of  the  more  highly  corrected 
combination.      The  author  has  frequently  noticed  this  difference  in 


146  SOME    NOTES    ON    THE   METALLURGICAL 

comparing  the  different  types  of  lenses.  Very  often  the  effect  of 
the  flare  can  be  overcome  by  using  a  combination  of  plate  and 
developer  which  gives  contrast  easily;  for  example,  such  methods 
succeed  perfectly  with  the  24  mm.  Zeiss  apochromat;  with  the 
12  mm.,  however,  as  stated  above,  the  flare  is  so  great  that  the 
author  uses  for  preference  a  very  good  achromatic  lens  of  the  same 
aperture. 

(c)  Colour  Screens. — As  mentioned  earlier  in  the  paper,  the  use 
of  colour  screens  in  metallurgical  work  is  simplified  very  much,  as  it 
is  only  on  very  rare  occasions  that  a  section  is  obtained  which  requires 
light  of  some  definite  wave-length  in  order  to  get  the  best  results,, 
consequently  the  whole  attention  can  be  given  to  using  the  light 
most  suited  to  the  lens. 

If  the  objective  is  apochromatic,  light  of  any  colour  may  be  used, 
but  it  is  generally  advisable  to  use  blue  light  in  preference  to  green 
or  red  (especially  with  the  higher  powers),  as  the  resolving  power  is 
thereby  increased.  It  is  always  advisable,  however,  even  with  the 
best  apochromats,  to  focus  with  the  same  colour  light  as  is  used 
for  photographing.  The  author's  general  practice  in  this  case- 
is  to  focus  with  a  blue  screen  in  position  (generally  the 
Wratten  tricolour  blue),  and  then  remove  the  screen  and  expose 
on  a  non-colour  sensitive  plate  (all  blue  screens  increase  the  exposure 
rather  considerably).  This  method  is  perfectly  satisfactory  for  the 
Zeiss  apochromats,  even  at  the  highest  magnifications. 

With   achromatic,   or  semi-apochromatic  lenses,   one  has  not  the 

same  freedom.      Owing   to   the  simpler   construction   of   these  lenses 

the   correction   for  -spherical   aberration   is   taken  to   a   high   degree 

of  perfection  for  light  of  one  colour  only  (generally  yellow  green), 

and  the  best  results  are  only  obtainable  by  using  this  colour.     The 

author  has  examined  such  objectives  made  by  most  of  the  leading 

makers  in  England,  and  has  never  met  one  in  which  the  correction 

for   spherical   aberration   for  blue   violet   light   was  sufficiently   good 

(compared   with   that   for   green     light)     to     make     it    worth   while 

taking    photographs    with    such    light.      Some   lenses    were    certainly 

better  than  others,  and,  curiously  enough,  some  of  the  lenses  which 

were   very  poor   with   blue  light   worked   quite  well   with   red   light. 

The   author  is  of  opinion   that  it  would  be   far  better  if  this  fact 

were   more  widely   acknowledged     by    the    makers.       To    read     the 

catalogue  descriptions  of  some  of  the  lenses  one  would  imagine  that 

they  would  perform  perfectly  without  any  screen  at  all.     The  author 

has  known  of  cases  where  objectives  by  well-known  English  makers 

have    been    purchased     and    used    in    the    belief    that    they    would 

perform  well  under  these  conditions.      After   seeing   the  results  the 

purchaser    came    to  the  conclusion  that   the    lenses    were    very    poor 

specimens.      In    one  case   which    occurred    recently   the    author    was 

able   to   convince   the   purchaser   that   the   type   of   lens   in   question 

would   give   very   fine   results  if   used    with  a  suitable   colour  screen 

instead    of    in    the   manner    suggested    by    reading    the    maker's   too 

optimistic  description.      Probably  one  of  the  best  screens  to  use  for 

such  lenses  is  one  of  the  tricolour  green  type.     The  author  uses  the 

one  made  by  Wratten,  along  with  the  Allochrome  plate  by  the  same 

maker.     Such  a  plate  as  this  (sensitive  to  yellow  green)  is  preferable 

for  this  purpose  to  a  panchromatic  plate,  as  the  red  sensitiveness  of 

the  latter  is  no  advantage — rather  the  reverse. 


PH0T0:^1ICR0SC0PE :    J.    H.    G.    MONYPENNY         147 

(d)  The    Relationship    of    AjJerture    a7id    Magnification. — With 
the  author's  arrangement  of  condensers,  the  beam  of  light  entering 
the    vertical    illuminator    is   rather   larger    than   the     largest   back 
lens  of   any  objective  he   has;    it   is   therefore   necessary  to    use   the 
iris  diaphragm   on  the   illuminator  (D,   Fig.    3).     His  practice  is   to 
cut   down     as    little    as    possible.       Generally    he     leaves    the     back 
combination  5-6ths  full;  it  is  only  on  rare  occasions  that  he  reduces 
below  this.     If  the  aperture  is  cut  down  much  more  than  this,  any 
surface    irregularities    due    to    scratches    are    shown    up    in    a    very 
prominent  manner,   owing  to  diffraction  bands.     For  this  reason,  of 
course,   it  is  well  to  reduce  the  aperture  to  less  than  5-6ths  when 
any  relief  effects  in  the  structure  have  to  be  emphasised.     The  effect 
of   gradually   reducing   the    aperture    of   an   objective    has   probably 
been   studied   mostly    from  the    point   of  view  of    the  higher    power 
objectives.     The  bad   effect  produced  on  the  images  given  by  such 
lenses  owing  to  such  reduction  is  probably  well  known,  though  the 
fact    that    photomicrographs    of    metals    showing    diffraction    effects 
caused   by   such   reduction    are   still   published  shows   that    this  bad 
effect  is  not  always  sufhciently  appreciated.     With  lower  power  lenses 
the  effects  are  not  so  marked  metallurgically,   since,  generally,   the 
photographs  taken  with  such  lenses  give  a  general  view  over  a  large 
field,  and  are  not  intended  to  show  fine  detail.     In  addition  to  this, 
such    low   power    lenses   {e.g.,    1   in.    or    2-3rds)    have    in    general    a 
higher  ratio  of  N.A.  to  magnification  than  the  higher  powers.     For 
example,  the  N.A.  of  the  lenses  mentioned  above  is  generally  between 
.24  and   .30,  and  they  are  used  for  photographs  at,  say,  50  to   150 
diameters.     On  the  other  hand,   twelfths   used   at   1,000   and    1,500 
diameters   have   at  the  most    1.4   N.A.,   and  frequently   only   1.2   to 
1.3.     Consequently   there   is   more   latitude  with  the   stopping  down 
of   low  power  lenses,   but  still   it   should   be  remembered   that  with 
these  lenses  diffraction  effects  are  produced,  and  there  is  a  limit  to 
the  reduction  of  the   aperture  beyond  which  it  is  not  advisable  to 
go.     By  suitable  stopping  down,  however,  one  can  often,  with  these 
low  powers,  obtain  a  larger  field  sharp  all  over — frequently  of  great 
importance. 

Under  present  conditions  nothing  is  gained  by  photographing 
at  any  higher  magnifications  than  about  1,500;  with  the  present 
maximum  aperture  available  (N.A.  1.40),  all  detail  which  can  be 
shown  is  visible  at  this  magnification.  Any  higher  magnification 
is  of  the  nature  of  an  enlargement,  and  can  be  obtained  equally  as 
well  by  photographing  at  this  magnification  (x  1,500),  and  enlarging 
from  the  negative,  as  by  taking  the  negative  direct  at  the  higher 
magnification.  There  is  no  doubt  that  for  many  metallurgical  pur- 
poses a  higher  magnification,  coupled  with  greater  resolvingf  power, 
would  be  of  great  value.  This  could  be  obtained  either  by  using 
light  of  very  short  wave-length,  with  its  attendant  difficulties  of 
focussing,  and  also  the  necessity  of  special  lenses  capable  of  trans- 
mitting light  of  su/^h  short  wave-length  or  by  increasing  the  aperturo 
of  the  objective.  With  regard  to  the  latter,  the  author  believes 
the  firm  of  Zeiss  produced  some  years  ago  a  2.5  mm.  objective 
working  at  about  N.A.  1.65.  This  objective  had  a  front  of  flint 
glass,  and  used  as  immersion  fluid  monobromide  of  naphthaline. 
Its  use,  however,  for  transparent  work  was  attended  with  great 
difficulties   and   expense,   inasmuch   as  the  slip   and  cover  glass   had 


148  SOME    NOTES    ON    THE   METALLURGICAL 

to  be  of  flint  glass.  With  metallurgical  work,  however,  these  diffi- 
culties would  not  occur,  and  it  seems  to  the  author  that  such  a 
lens  would  be  of  value  in  elucidating  some  of  the  finer  structures 
met  with  in  metals.  If  such  a  lens  could  be  made  it  should  prefer- 
ably be  apochromatic,  but,  if  not,  it  might  be  advisable  to  correct  it 
for  blue  violet,  as  the  "  preferred  colour,"  in  order  that  the  highest 
resolving  power  could  be  obtained  photographically. 

It  is  obvious  that  at  the  highest  powers  the  apochromatic  lens 
has  a  much  greater  resolving  power  than  the  semi-apochromatic  of 
the  same  aperture,  owing  to  its  capability  of  working  with  blue  violet 
light.  It  should  be  emphasised  that,  other  things  being  equal,  using 
light  of  wave-length  4,500  A.U.  instead  of  5,500  A.U.  is  equivalent 
in  its  effects  to  increasing  the  N.A.  approximately  25  per  cent. 

(e)  Eximsure  and  Vibration  Effects. — In  metallurgical  photo- 
microscopes  for  use  in  works'  laboratories  it  is  very  important 
that  the  exposure  required,  especially  with  high  magnifications, 
should  be  as  short  as  possible  in  order  to  avoid  the  effects  of 
unavoidable  vibrations.  For  such  purposes  an  intense  illuminant 
is  required,  and  such  lamps  evolve  a  very  considerable  amount 
of  heat,  which  may  easily  cause  trouble  with  the  cement  used  in 
the  various  combinations  of  the  objective.  It  is  very  necessary  in 
such  cases  that  an  adequate  cooling  trough  be  placed  in  the  beam 
of  light  before  it  reaches  the  microscope.  The  heat  evolved  also 
causes  trouble  owing  to  the  expansion  effects  produced  in  different 
parts  of  the  microscope  and  camera. 

Even  when  the  exposures  are  comparatively  short  (e.g.,  a  few 
seconds),  they  still  give  plenty  of  time  in  the  case  of  the  higher 
powers  for  vibration  to  have  considerable  effect.  The  author  has, 
however,  been  able  to  overcome  this  completely  by  swinging  the 
whole  photomicroscope  on  springs,  as  shown  in  Fig.  7.  It  will  be 
noticed  that  the  author's  camera  is  vertical.  This  position  has 
several  advantages  from  a  works'  point  of  view ;  obviously  it  occupies 
less  floor  space  than  the  horizontal  pattern,  and  is  probably  more 
easily  swung  than  the  latter.  It  may  be  mentioned  that,  with  the 
suspension  system  used,  photographs  at  1,000  and  1,500  diameters 
were  successfully  taken,  although  the  laboratory  was  within  50  yards 
of  four  8-ton  steam  hammers,  and  also  adjoined  three  sets  of 
railway  lines  running  into  the  works. 

(f)  Low  Fower  Photography. — It  is  frequently  desirable  to  be 
able  to  reproduce  at  low  magnifications  fairly  large  areas  under 
vertical  illumination.  With  ordinary  low  power  objectives  {e.g., 
2  in.  or  3  in.),  it  is  possible  to  take  photographs  at,  say,  20  or  30 
diameters,  but  in  general  the  field  is  only  small,  about  \  in.  or 
tV  in.  diameter.  If  attempts  are  made  to  get  a  larger  field, 
trouble  is  at  once  experienced  with  the  illumination,  and  often 
with  the  definition  falling  off.  Frequently  a  very  large  field  is 
required  if  the  photograph  is  to  s.erve  its  purpose,  as,  for  example, 
with  groups  of  flaws,  very  coarse  structures,  and  segregated  areas. 

Some  ten  or  twelve  years  ago  the  author  devised  an  arrangfement 
for  this  purpose,  and  as  he  has  found  it  exceedingly  useful,  he 
puts  it  forward  in  the  hope  that  it  may  be  of  use  to  others.  There 
is  nothing  really  novel  in  the  method,  it  is  a  combination  of  several 


*      PHOTOMICROSCOPE :    J.    H.    G.    MONYPENNY         149 

ideas,  but  so  far  as  the  author  is  aware,  such  an  arrangement  has 
not  been  described  before,  nor  has  he  heard  of  any  similar  apparatus. 

For  such  work  the  ordinary  low  power  objective  is  not  suitable — 
its  "  field  "  is  not  big  enough.  The  lens  the  author  uses  is  the 
35  mm.  projection  lens  made  by  Zeiss,  though  probably  equally 
good  results  could  be  obtained  with  some  of  the  very  short  focus 
photographic  lenses  made  by  various  opticians.  As  illuminator  he 
uses  a  piece  of  niicroscopic  cover  glass  1^  in.  x  IJ  in.,  mounted 
in  a  light  brass  frame  which  fits  on  to  the  objective.  The  frame 
is  pivoted,  allowing  the  illumination  to  be  adjusted  to  a  nicety. 
This  disc  is  used  between  the  objective  and  the  section. 

If  one  is  using  an  enlarging  lantern  or  a  projection  lantern,  then, 
in  order  to  get  satisfactory  lighting,  as  is  well  known,  the  condenser 
must  be  close  to  the  negative  or  slide  and  must  focus  the  illuminant 
on  the  projection  lens.  The  same  principle  is  used  for  photographing 
metal  sections,  and  the  arrangement  of  condensers  is  shown  diagram- 
matically  in   Fig.   8,   which  shows  the   35   mm.    lens  A   attached   to 


«rtle-  t'ov^ 


Fig.  8. 

Condenser  system  for  low  power  photography 


the  microscope  tube  and  the  section  B  on  the  stage  (the  microscope 
used  is  the  large  "  Works  "  model  made  by  Watsons,  London, 
which  has  a  very  wide  tube — the  inner  draw  tubes  are  removed  for 
use  wdth  this  lens).  The  condenser  D  forms  a  considerably  enlarged 
image  of  the  illuminant  C  (the  500  C.P.  Pointolite  Lamp)  at  E 
close  up  to  the  second  condenser  F,  and  the  latter  in  turn  focusses 
the  image  (after  reflection  at  the  45°  cover  glass  reflector  G  and 
the  surface  of  the  specimen)  on  the  lens  A,  as  indicated  roughly 
by  the  dotted  lines.  The  condensers  used  are  2J  in.  diameter,  and 
it  is  possible  to  illuminate  evenly  a  section  about  1  in.  diameter; 
this  is  more  than  required,  as  the  field  of  the  lens  is  only  about 
f  in.  diameter.  Fig.  9  shows  the  apparatus  set  up,  and  Figs.  10 
and  II  some  of  the  results  obtained. 

It  is  obvious  that  these  low  powers  are  of  special  value  where 
either  the  structure  is  very  coarse,  or  where  one  wishes  to  show 
the  variation  of  structure  over  a  fairly  large  area.  For  example, 
Fig.  10  (x  15  diameters)  shows  far  better  than  a  photograph  at,  say, 
100  diameters,  the  structure  of  the  sample  of  overheated  steel 
from  which  it  was  taken.  Fig.  11  (  x  15  diameters)  illustrates  another 
type  of  photograph  for  which  the  ordinary  microscopic  objective 
would  be  quite  useless;  this  shows  the  size  and  distribution  of 
carbon  in  an  unsound  segregated  area.  This  actual  example  is 
rather  unique,  showing,  as  it  does,  high  and  low  carbon  areas  in 
close  proximity. 


150  METALLURGICAL    PHOTOMICROSCOPE : 

With  the  author's  camera  and  microscope,  magnifications  ranging 
from  9  to  23  can  be  obtained,  but  with  a  longer  camera  it  would 
be  quite  possible  to  reach  30  or  40  diameters.  As  mentioned  above, 
the  tube  of  the  author's  microscope  is  very  wide  and  comparatively 
short  (2  in.  diameter  and  4|  in.  long),  and  this  enables  one  to 
use  practically  the  full  field  of  the  35  mm.  lens;  with  a  narrower 
tube,  of  course,  part  of  the  field  would  be  cut  off.  In  such  cases 
one  may  do  without  the  microscope  and  mount  the  lens  on  a  small 
fitting  (with  either  spiral  or  rackwork  focussing)  on  the  front  of 
the  camera.  In  one  or  two  cases  the  author  has  done  this,  and 
has  succeeded  in  obtaining  a  6 J  in.  circle  at  9  diameters  (i.e.,  a  field 
of  .72  in.).  The  definition  in  this  case  was  not  quite  perfect  round 
the  edge,  but  it  was  sufficiently  good  for  the  purpose. 

It  may  not  be  out  of  place  to  mention  that  when  taking  a 
photomicrograph  without  using  an  eye-piece  it  is  necessary  to  avoid 
reflection  from  any  metallic  surface  inside  the  microscope  tube. 
The  latter  should  be  coated  with  a  dull  black  varnish,  but  it  is 
generally  advisable  to  put  in  a  lining  of  black  cloth.     Such  a  lining 


^sr 


Fig.    12. 
Illuminating-  system  for  lowest  powers   (up  to  about    X5). 


can  be  easily  made  by  gumming  a  piece  of  black  cloth  of  the  required 
size  on  to  a  similar  piece  of  fairly  stiff  paper,  then  rolling  into  a 
cylinder  (cloth  inside),  which  can  be  slid  into  the  microscope  tube. 

For  still  lower  powers  one  may  use  a  photographic  lens  of  3  in. 
to  5  in.  focus;  the  one  used  by  the  author  is  a  5^  in.  Holostigmat 
by  Watson,  and  with  this  he  can  reproduce  from  natural  size  up 
to  about  4  diameters.  In  this  case  a  different  system  of  illumination 
is  employed.  For  the  45°  reflector  a  thin  lantern  slide  cover  glass 
is  used.  (It  is  possible  to  obtain  thin  microscopic  cover  glasses 
in  sizes  up  to  4J  in.x3:J  in.,  but  such  glasses  are  very  fragile.)  A 
large  piece  of  ground  glass  is  mounted  close  to  the  section  as  shown 
at  A  in  Fig.  12,  and  the  condenser  B  throws  a  parallel  or  slightly 
divergent  beam  of  light  on  this.  The  idea  is  to  produce  an  evenly 
illuminated  disc  of  light  on  the  ground  glass,  and  the  light  from  this 
is  reflected  on  to  the  section  by  the  45°  reflector  C.  Such  low 
magnifications  are  es])ecially  valuable  with  sections  etched  with  one 
of  the  "  copper  "  reagents  (such  as  Stead's,  Rosenhain's,  or  Le 
Chatelier's),  which  require  a  low  magnification  as  a  general  rule. 
Fig.  13  is  an  example  of  this — it  represents  a  section  (x4  diameters) 
from  a   small  sample   ingot   (taken   for  analytical   purposes   from   an 


Monypenny. — 1. 


Fig.  4. 
Ferrite  and  Pearlite,  using  good  disc. 


Fig.  5- 

Same  field  as  No.  4,  but  taken 
with  bad  disc.      x   100. 


Monvpenny.     2. 


\^^im 


Fig.  6. 


Fig.  7. 

Photomicroscope  showing  spring 
susi^ension. 


Monypenny.— 3 


Fig.  q. 
Microscope  and  condenser  arranged  for  low  power  photography 


Monypenny.— 4. 


""^I'r  ^ 


Fig.   10. 
Overheated  Mild  Steel,  x  15  diam. 
(Reproduced  half  size— 7.e  ,  x  yl,  diam.j 


Fig.    II. 
Segregated  Core  in  Mild  Steel  Bar  x   15  diam. 
(Reproduced  half  size— i  e.,  x   7!  tliam.) 


Monypenny. — 5. 


Fig.   13. 
Chill  crystals  in  small  steel  ingot  (etched  cupr'c  reagent) .  X4. 


Fig.    14. 

Section  of  Burnt  File  Blank  showing 
decarburisation,  x  3. 

(Reproduced  half  size). 


Monypenny— 8 


.^^' 


- ...   s- 


Vx^.^ 


A. — Laminated  lY^aiiite  and  Feiritc. —  x  3,500  reduced  to  3,000 
Zeiss    2    m/m.    apochromat.     N.A.    1.4.,    nonochromatic   blue 

lig-ht.     (Neg-ativc   x  1,000  and  enlarged.) 
B. — Pearlite    (finer  than   A)    and   Ferrite. —  x  3,500  reduced   to 
3,000.     Watson    2    m/m.    "  Holos  "    N.A.    1.35,   yellow    green 

light.      (Negative    x  1,400  and  enlarged.) 


J.     H.    G.    MONYPENNY  151 

electric  furnace),  and  shows  the  development  of  long  chill  crystals. 
Fig.  14  (from  a  file  blank  burnt  in  forging)  was  also  taken  by  this 
method,  and  shows  (x3  diameters)  the  decarburisation  Tormed  both 
in  the  skin  and  round  the  cracks. 

A  method  of  illumination  similar  to  the  last  one  was  described 
by  F.  B.  Foley  in  "  Metallurgical  and  Chemical  Engineering  " 
(August  1st,  1919).  He  used  it  for  low  power  photomicrographs  (at 
about  7  diameters).  For  this  purpose,  however,  the  author  prefers 
the  arrangement  shown  in  Fig.  8,  as  it  gives  better  detail  at  these 
magnifications. 

In  conclusion,  the  author  wishes  to  thank  the  Directors  of  Messrs. 
Brown  Bayley's  Steel  Works,  Ltd.  (and  in  particular  Mr.  H. 
Brearley)  for  permission  to  publish  the  photographs  accompanying 
this  paper,  and  also  to  Messrs.  F.  S.  and  W.  H.  Nicholds  (members 
of  the  Laboratory  Staff)  for  their  assistance  in  preparing  the  photo- 
graphs and  diagrams. 


METALLURGICAL  MICROSCOPES  AND  THEIR  DEVELOP- 
MENT. 

By  Leslie  Aitchison,  D.  Met.,  B.Sc,  A.I.C.,  and  F.  Atkinson. 


It  is  assumed  that  the  primary  function  of  this  symposium  is  to 
bring  out  the  present  position  in  regard  to  microscopes  and  also  to 
elicit  those  improvements  which  could  well  be  introduced  into  micro- 
scopes with  a  view  to  improving  the  instruments,  making  them  more 
convenient  to  employ,  and  also  elaborating  the  uses  to  which  they  can 
be  put.  The  present  notes  are  written  from  the  point  of  view  of  the 
metallurgist,  and  primarily  from  that  of  the  working  metallurgist,  to 
whom  the  microscope  is  of  constant  value  and  usefulness.  No  attempt 
is  made  to  discuss  the  questions  from  the  optician's  standpoint,  but 
rather  to  indicate  the  needs  of  the  metallurgist  in  the  hopes  that  the 
optician  and  miscroscope  manufacturer  will  be  able  to  meet  more  and 
more  of  these  requirements. 

In.  saying  anything  of  modern  microscopes  it  is  difficult  to  avoid 
constant  reference  to  the  products  of  the  Continental  makers,  and  to 
make  comparisons  between  their  microscopes  and  those  produced  in 
this  country.  This  has  reached  the  stage  at  which  comparisons  usually 
take  the  form  of  stating  how  near  the  British  article  approaches  to  the 
Continental.  The  position  will  not  be  really  satisfactory  until  the 
reverse  of  this  position  is  the  true  one,  i.e.,  until  the  British  article  is 
compared  with  tlie  Continental  on  the  basis  of  the  superiority  of  the 
former  and  not  upon  its  inferiority. 

Speaking  as  users  of  microscopes  and  microscopic  outfits,  one  of 
the  first  points  that  requires  attention  is  the  more  prompt  incorporation 
in  the  instrument  of  those  details  and  fittings  which  make  the  use 
of  a  microscope  less  laborious.  The  Continental  makers  were  always 
ready  to  adopt  and  to  incorporate  these  details,  and  it  would  be  of 
great  assistance  if  the  British  manufacturers  would  do  the  same. 
For  instance,  the  Continental  makers  would  supply  a  stage  micrometer 
in  metal  (a  great  improvement  upon  those  made  in  glass),  marked  in 
tenths  and  hundredths  of  a  millimetre.  The  British  manufacturer 
has  up  to  the  present  given  us  one  marked  only  in  tenths  of  a  milli- 
metre. 

A  similar  matter,  and  one  that  causes  a  good  deal  of  trouble,  is 
the  lack,  upon  photomicrographic  outfits,  of  a  really  good,  reliable 
and  workable  fine  focussing  arrangement  which  can  be  operated  from 
the  camera  end.  This  objection  applies  to  (ill  microphotographic 
outfits,  British  and  Continental,  as  none  of  those  made  give  real 
satisfaction.  For  inetalhirgical  work  photomicrography  is  of  great 
importance,  and  if  photographs  are  to  be  taken  at  high  powers, 
e.(f.,  up  to  1,000  diameters,  the  focussing  apparatus  is  of  vital  im- 
portance. Those  at  present  manufactured  do  not  work  really  well, 
and  cause  a  great  deal  of  irritation  to  the  operator. 

152 


LESLIE   AITCIIISON  AND   F.    ATKINSON  153 

Connected  with  the  photomicrograph ic  outfit  is  the  trouble  which 
is  experienced  because  of  the  lack  of  adequate  devices  for  the  preven- 
tion of  vibration  of  the  apparatus.  The  greatest  proportion  of  metal- 
lurgical photomicrography  has  to  be  done  in  works.  Such  places  are 
always  subject  to  a  fair  amount  of  vibration,  which  is  usually  trans- 
mitted in  a  greater  or  less  degree  to  the  apparatus.  This  almost 
renders  high  power  photography  of  the  higher  order  impossible.  The 
problem  of  vibration  is  not  new,  and  various  efforts  have  been  made 
to  solve  it  by  the  makers,  but  up  to  the  present  these  efforts  have  not 
proved  at  all  successful.  The  existence  of  the  vibration  is  one  of  the 
factors  which  limits  the  development  of  higher  powers  in  industrial 
microphotography. 

Photomicrography  is  not  possible  at  all  unless  the  source  of  light 
is  good  and  reliable.  The  arc  lamp  is  not  good  for  photography.  It 
is  too  uncertain.  It  is  very  prone  to  flicker,  and  also  to  give  a 
wandering  source.  Further  than  that,  it  requires  a  good  deal  of  atten- 
tion— replacing  and  adjusting  of  carbons — whilst  it  also  usually  in- 
volves the  use  of  a  mechanical  device  for  keeping  the  arc  in  its  correct 
situation.  Lime-light  does  not  suffer  from  these  defects,  but  it 
presents  the  other  difficulty,  namely,  that  it  is  not  sufficiently  intense 
to  provide  a  good  illumination  at  high  powers,  and  therefore  to  allow 
of  short  exposures.  The  specially  designed  sources  of  illumination, 
such  as  the  Pointolite,  are  distinctly  better,  and  it  is  considered  that 
this  is  the  form  of  illumination  which  will  best  repay  development. 

It  is  obvious,  of  course,  that  the  improvements  indicated  above 
are  of  little  value  unless  they  are  accompanied  by  excellence  in  the 
more  purely  optical  parts  of  the  outfit.  The  critical  part  of  the  micro- 
scope is  undoubtedly  the  combination  of  the  lenses,  and  it  is  probably 
in  this  part  of  the  equipment  that  the  standard  Continental  makes  are 
most  missed.  There  are  numerous  points  about  the  lenses  which  could 
be  considered,  but  one  of  them  can  be  selected  as  typical.  This  is 
the  production  of  a  flat  field.  In  this  respect  the  Continental  outfits 
showed  a  great  superiority,  as  they  permitted  photographs  to  be  ob- 
tained perfectly  sharp  at  really  low  magnification  (10).  This  was  of 
immense  importance  in  the  study  of  cast  metals  and  in  watching  the 
persistence  of  the  primary  crystallisation  of  a  metal  through  all  the 
subsequent  stages  of  working  and  treatment.  Unfortunately  no  such 
good  results  can  be  obtained  with  the  usual  British  lenses. 

The  usual  range  of  magnification  of  the  modern  microscope  ends  at 
about  1,500  diameters — particularly  in  so  far  as  photography  is  con- 
cerned. Unfortunately  there  are  many  things  which  this  magnifica- 
tion does  not  reveal,  and  which  the  metallurgist  would  be  glad  to 
investigate.  It  seems  that  it  might  be  useful  to  indicate  a  few  of 
the  points  which  the  invention  of  a  "  metallurgical  ultra-microscope 
might  be  expected  to  make  plain. 

Several  such  points  arise  in  connection  with  tempered  steel,  and 
although  it  is  not  possible  to  make  their  significance  entirely  plain 
without  introducing  a  good  deal  of  matter  apart  from  microscopical, 
they  may  be  taken  as  typical  problems.  As  is  w^ell  known,  hardened 
steel  consists  essentially  of  a  solid  solution  of  iron  carbide  in  iron.  If 
this  solution  be  tempered,  a  certain  change  takes  place  in  it,  which  is 
reflected  in  the  mechanical  properties  of  the  steel,  which  becomes  softer 
and  tougher.     This  change  is  usually  (and  probably  quite  correctly) 


154 


METALLURGICAL    MICROSCOPES 


ascribed  to  the  S2)litting  up  of  the  solid  solution,  the  iron  carbide  being 
precipitated  in  a  fine  state  of  division  throughout  the  solvent  iron. 
That  this  explanation  is  correct  in  its  outline  is  more  than  probable,  and 
when  the  tempering  has  proceeded  to  something  like  completion  the 
presence  of  the  carbide  is  easily  detected.  The  early  stages  of  the 
decomposition  are  practically  incapable  of  observation  v^ith  the  present 
microscopic  means  which  are  available,  but  this  is  the  portion  of  the 
process  which  is  of  the  greatest  interest  and  importance.  It  is  almost 
impossible  at  the  present  time  to  say  at  what  temperature  the  decom- 
position of  the  solid  solution  commences  or  how  it  proceeds.  In  many 
carbon  steels  the  maximum  stress,  which  in  the  ordinary  way  is 
supposed  to  decrease  when  the  tempering  temperature  increases, 
actually  increases  at  tempering  temperatures  near  to  400°  C.  Typical 
results  are :  — 


Table  i. 


Steel 

Heat  Treatment 

Max.  Stress 
tons/sq.  inch. 

0.3% 

Quenched  85o''C.     ...        temp. 

i5°C. 

50.5 

carbon 

ioo°C. 

49.6 

,, 

200°C. 

49  4 

,, 

300°C. 

47.1 

40o''C. 

50.1 

., 

500^0. 

46.8 

It  is  quite  likely  that  if  the  constitutional  changes  going  on  within 
the  Steel  could  be  examined  microscopically,  and  a  better  idea  of  these 
changes  formulated,  the  explanation  of  the  peculiar  happenings  would 
be  found.  This  would  require  a  very  high  power — something  probably 
of  the  order  of  ten  times  as  great  as  the  present  powers. 

Similiar  problems  arise  in  connection  with  the  tempering  of  the 
alloy  steels.  In  the  nickel  chromium  steels,  for  instance,  a  property 
known  as  temper  brittleness  is  shown  by  steels  which  cool  slowly  from 
or  through  a  certain  range  of  temperature,  e.g.,  425°  C.  to  550°  C, 
In  all  other  respects  the  mechanical  properties  of  the  steels  are  the 
same  whether  cooled  quickly  or  slowly.  The  effect  of  different  methods 
of  cooling  from  this  temperature  upon  the  toughness  is  shown  in 
Table  2. 

It  is  inconceivable  that  there  is  no  difference  at  all  in  the  con- 
stitution of  the  two  steels,  but  the  present  microscopic  methods  fail 
entirely  to  detect  the  difference  (see  Figs.  1  and  2).  It  is  possible  that 
higher  powers  would  make  the  detection  possible.  The  same  powers 
might  also  give  an  explanation  of  the  peculiar  impact  values  which  are 
obtained  from  the  alloy  steels  by  tempering  at  comparatively  low 
temperature,  e.g.,  150°  to  350°  C.  The  accompanying  curve  (Fig.  3) 
shows  the  values  which  are  customarily  obtained,  and  in  addition  shows 


Aitchison  and  Atkinson.     1. 


Fig.  I. 


Fig.  2. 


100°  200°  500°  400°  500°  600' 

-TEMPERING  TEI^PERATURES /C  - 

Fig.  3. 


LESLIE    AITCHISON    AND    F.    ATKINSON 


155 


the  form  of  the  curve  which  might  reasonably  be  expected.  Here 
again  there  is  surely  some  constitutional  alteration  taking  place,  and  it 
might  reasonably  be  hoped  that  a  sufficiently  high  powered  Microscope 
would  reveal  it. 

The  theory  which  has  probably  had  as  much  effect  as  any  other 
upon  recent  scientific  metallurgy  is  that  known  as  the  "  amorphous 
cement  "  theory.  This  theory  postulates  the  existence,  between  the 
crystals  of  a  metal,  of  a  thin  layer  of  amorphous  material  which  both 

Table  2. 


Notched  bar  value  on 

tempered  specimens. 

Tempering    Temperature. 

Cooled  in  air  after 
tempering. 

Cooled   in    water 
after  tempering. 

40-a°C. 

8 

8  , 

5oo°C. 

18 

18 

550°C. 

7 

30 

6oo°C. 

8 

41 

6so°C. 

8 

53 

separates  and  binds  together  the  individual  crystals.  The  properties  of 
this  amorphous  metal  are  necessarily  different  fi"om  those  of  the 
crystals  which  it  surrounds.  The  evidence  for  the  existence  of  this 
layer  is  largely  circumstantial,  and  though  the  evidence  is  powerful 
it  would  be  decidedly  stronger  if  the  cement  could  actually  be  revealed. 
If  a  power  of  10,000  failed  to  produce  any  further  evidence  of  its 
existence  it  would  seem  difficult  to  imagine  that  it  is  really  there . 

Duralumin  is  a  metal  which  has  distinctly  peculiar  properties.  If 
duralumin  be  quenched  in  water  from  a  suitable  temperature  it  is  soft 
at  first,  but  after  standing  for  a  time,  e.g.,  24  hours,  the  metal  becomes 
quite  hard.  This  change  of  properties  is  bound  to  be  accompanied  by 
some  change  of  constitution,  and  a  possible  explanation  of  this  change 
has  recently  been  put  forward  by  Dr.  Jeffries.  It  seems  certain,  how- 
ever, that  the  application  of  higher  powers  of  microscopic  examination 
would  help  materially  in  the  investigation  of  this  problem. 


PHOTOMICROGRAPHS    OF    STEEL    AND    IRON    SECTIONS 
AT    HIGH    MAGNIFICATION. 

By  Sir  Robert  Hadfield,  Bart.,  D.Sc,  D.Met.,  F.R.S., 
AND  Mr.  T.  G.  Elliot,  F.I.C. 


Owing  to  the  importance  of  the  study  of  Microstructure  much 
attention  has  been  given  to  this  subject  since  the  days  when  the  late 
Dr.  H.  C.  Sorby,  F.R.S.,  of  Sheffield,  originated,  in  1857,  this  method 
of  examining  structures  of  various  materials,  including  Iron  and  Steel. 
Indeed,  one  of  the  most  striking  features  of  the  progress  of  Metallurgy 
in  recent  years  is  the  great  development  of  the  use  of  microscopical 
methods  of  investigation.  We  submit  some  photomicros,  Figs.  1  and 
2,  Plate  A,  representing  some  of  the  early  work  of  Dr.  Sorby  at 
9  magnifications.  We  also  submit  as  a  comparison,  and  in  order  to 
demonstrate  the  great  advance  in  Metallography,  Photomicrographs 
Figs.  3  to  25  showing  later  work  of  the  writers  of  this  Paper,  in  which 
magnifications  are  dealt  with  of  100  and  up  to  no  less  than  8,000. 

In  carrying  out  this  work,  our  best  thanks  are  due  to  Mr.  H. 
Wrighton,  B.Met.  for  the  assistance  he  has  rendered  and  for  the  care 
and  skill  he  has  exercised  in  preparing  the  Photomicrographs  accom- 
panying our  Paper. 

One  of  us  well  remembers  his  conversations  with  Dr.  Sorby 
regarding  the  micro  study  of  his  own  early  specimens  of 
Manganese  Steel,  in  1883-1887.  Dr.  Sorby  never  turned  away  the 
youngest  enquirer,  and  he  little  imagined  when  first  describing  his 
method  in  1857  what  an  important  aid  this  would  eventually  prove  to 
Metallurgy.  This  is  another  instance  of  the  great  value  to  the  Metallur- 
gist of  original  work  by  the  pure  Scientist.  Next  to  Sorby,  this 
important  branch  of  investigation  owes  more  for  its  development  to 
Arnold  and  Osmond  than  any  others.  It  has  been  further  advanced 
by  Sauveur,  Stead,  Le  Chatelier,  Carpenter,  Howe,  Martens, 
Robin,  Rosenhain,  and  many  others. 

Sorby  bequeathed  £15,000  to  the  Royal  Society  for  the  establish- 
ment of  a  Fellowship  for  the  carrying  on  of  original  Scientific  Research, 
the  object  specified  being  "  to  promote  the  discovery  of  new  facts 
rather  than  the  teaching  of  what  is  known,"  and  stated  that  as 
far  as  possible  the  Researches  should  be  carried  out  at  the  University 
of  his  own  native  City,  Sheffield.  To  this  Englishman,  Sorby,  the 
whole  world  has  fully  and  freely  given  the  credit  of  originating  this 
important  form  of  research  which  enables  the  structure  of  Iron  and 


156 


SIR  R.  HADFIELD  AND  MR.  T.  G.  ELLIOT,  F.I.C.       157 

its  Alloys,  including  in  that  term  the  material  generically  known  as 
"  Steel,"  to  be  examined  and  understood  in  a  manner  which  was 
before  not  possible.  "  Steel  "  is  a  wide  term  and  to-day  covers 
material  w^hich  is  practically  pure  Iron,  for  example,  products  contain- 
ing 99.9  per  cent,  of  Iron  w^hich  offer  high  resistance  to  corrosion  and 
oxidation  and  containing  practically  no  Carbon,  up  to  the  material 
used  for  wortle  or  drawing  plates  which  contain  even  more  than  2 
per  cent,  of  Carbon. 

Twenty-five  years  ago  there  were  scarcely  half-a-dozen  Steel 
Works  in  the  country  which  could  lay  claim  to  the  possession  of 
a  Microscope  suitable  for  metallographical  examination.  At  the 
present  time  it  may  be  safely  said  that  no  steel  works  of  any  size  is 
without  one.  Nor  is  the  use  of  the  Microscope  confined  to  the  ex- 
amination of  Iron  and  Steel  sections,  for  those  engaged  in  the  investiga- 
tion of  non-ferrous  metals  and  alloys  find  its  aid  equally  useful. 

The  history  of  Metallography,  short  as  it  is,  is  beyond  the  scope  of 
the  present  paper.  Naturally  such  history  to  be  complete  would 
record  the  improvements  w^hich  have  taken  place  in  the  construction 
of  Lenses  for  metallographic  work.  One  of  the  most  important  of 
these  was  the  introduction  of  the  Apochromatic  Objective  by  means 
of  W'hich  increased  resolution  was  obtained,  an  absolute  necessity  for 
successful  high  power  photomicrography.  Unfortunately,  as  this 
Country  had  occasion  to  find  out  on  the  outbreak  of  War,  the  making 
of  these  objectives  has  in  the  past  been  largely  in  foreign  hands.  Steps 
are  being  taken  to  remedy  this,  and  there  is  every  reason  to  hope  that 
here,  as  in  other  directions,  in  future,  we  shall  be  rendered  entirely 
independent  of  the  foreigner. 

Great  as  have  been  the  advances  made  in  the  microscopical  ex- 
amination of  Iron  and  Steel,  there  still  remains  a  wide  field  for 
exploration ;  for  example,  as  regards  methods  w^hich  wdll  enable  increased 
magnifications  to  be  obtained.  It  is  w^onderlul  what  can  be  accom- 
plished by  the  aid  of  the  human  eye  alone,  and  even  to-day  the  finest 
quality  of  crucible  cast  steel  is,  in  its  ingot  form,  first  packed  or  sorted 
over  in  this  manner.  It  is  stated  that  an  experienced  workman  can, 
hy  the  eye,  detect  from  the  appearance  of  the  fracture  differences  as 
small  as  .05  per  cent,  to  .10  per  cent,  of  Carbon.  No  doubt  for  many 
purposes  an  ordinary  strong  magnifying  glass  will  tell  much  and 
more  than  the  unaided  eye  can  do,  but  when  it  is  desired  to  reveal 
structures  minutely,  then  the  microscope  is  called  in  with  great 
advantage.  Magnifications  of  10  or  less,  upwards  to  1,000  or  1,500 
are  those  most  commonly  used  in  metallography.  Photomicrographs 
of  larger  magnifications  than  1,500  have  been  rarely  published.  The 
Authors  have,  however,  carried  out  experiments  in*  order  to  obtain 
photographs  of  5,000  and  even  8,000  magnification,  w^hich  may  be  of 
interest  to  this  Society. 

The  very  fine  structures  met  with  in  alloy  steels  have  made  it 
.•desirable  and  induced  the  Authors  to  prepare  in  their  research 
photomicrographs  at  higher  magnifications  than  have  hitherto 
been  obtained.  With  great  care  and  attention  to  necessary  details, 
particulars  of  .w^hich  are  described  in  this  Paper,  we  have  been  able  to 


158         PHOTOMICROGRAPHS  OF  STEEL  AND  IRON 

obtain  photographs  of  Iron  and  Steel  sections  at  the  high  magnification 
of  8,000  diameters.  To  give  an  idea  of  what  this  means,  it  may  be 
mentioned  that  the  diameter  of  the  actual  field  shown  in  a  3J"  circle 
photograph  at  this  magnification  is  only  .00041"  or  1/2460".  The 
actual  area  of  this  field  examined  is  .00000013  square  inches.  The 
polished  section  under  micro-examination  is  usually  about  J  in.  square. 
If  the  whole  of  this  area  w^ere  magnified  8,000  times  it  would  yield 
a  square  about  55  yards  by  55  yards,  occupying  an  area  of  approxi- 
mately 3,000  square  yards,  that  is  to  say,  not  far  away  from 
three-quarters  of  an  acre. 

As  is  well  known,  the  modern  Microscope  consists  of  two  systems 
of  lenses,  the  objective  and  the  eye-piece.  The  objective  gives  an 
enlarged  image  of  the  object,  and  the  eye -piece  further  magnifies  this 
image.  The  high  power  photomicrographs  given  in  this  Paper  are  simply 
high  magnifications  by  means  of  the  eye-piece  and  extra  camera  ex- 
tension of  the  image  given  by  a  2  mm.  objective,  or  in  the  case  of  the 
8,000  magnifications  by  a  1.5  mm.  objective.  Whatever  may  be  the 
quality  of  the  image  given  by  the  objective — for  example,  as  regards 
resolution — that  quality  is  reproduced  in  the  magnified  image  of  the 
eye-piece.  Thus,  if  the  objective  gives  a  blurred  image,  the  blur  is 
simply  magnified.  In  other  words,  it  is  just  as  though  a  lantern 
slide  were  projected  on  the  screen  ;  if  the  slide  is  a  good  one  we  get 
a  good  picture,  but  if  bad  the  picture  will  be  no  better  because  it  is 
magnified.  The  essential  aim,  therefore,  is  to  get  a  very  clearly  resolved 
image.  This  needs  a  special  quality  or  virtue  in  the  objective,  and 
this  virtue  is  called  its  resolving  power. 

For  photomicrography  at  high  magnifications,  it  is  specially  essential 
that  an  objective  of  high  resolving  power  should  be  used.  The  effect 
of  magnification  without  resolution  is  well  illustrated  by  Figs. 
3,  4  and  5  on  Plate  B.  These  photographs  are  all  at  600  magnifications, 
but  taken  by  objectives  of  low,  medium,  and  high  power  respectively. 
In  No.  3  the  dark  ground  mass  is  left  unresolved.  No.  4  shows 
some  resolution  of  this  dark  ground  mass,  but  in  No.  5  it  is  practically 
completely  resolved  into  its  two  constituents,  Ferrite  and  Cementite 
in  lamellar  form.  In  the  course  of  a  search  for  a  really  good  2  mm. 
oil  immersion  objective,  for  photomicrographic  research,  we  found  that 
results  obtainable  with  a  moderate  Achromat,  compared  with  those 
obtained  with  a  good  Apochromat,  showed  difterences  at  least  as 
great  as  is  illustrated  in  Figs.  4  and  5. 

An  illustration  of  the  microstructure  of  an  Annealed  Alloy  steel, 
containing  .84  per  cent.  Carbon  and  1.12  per  cent.  Chromium,  is  shown 
at  four  different  magnifications  in  Figs.  6,  7,  8,  and  9  on  Plate  C. 
Although  the  resolution  of  the  structure  is  the  same  in  Figs.  7  and  8^ 
because  the  same  objective  was  used  in  each  case,  the  eftect  of  the 
increased  magnification  is  to  show  in  a  striking  manner  the  alternate 
white  and  dark  constituents  of  the  lamellar  pearlite.  This  effect  is 
further  emphasised  in  a  photograph  of  the  same  section  at  8,000  magni- 
fications, shown  in  Fig.  9.  There  is  no  doubt  that  this  magnification 
taxed  the  lens  somewhat  beyond  its  capacity;  however,  the  photograph 
is  certainly  a  good  one  and  worth  including,  if  only  to  show  the  limit 
obtainable  with  the  apparatus  available  at  the  present  time. 


SECTIONS   AT   HIGH   MAGNIFICATION  159 

Photomicrographs  of  Diatoms  at  5,000  magnifications  and  over, 
taken  by  transmitted  light,  have  been  published  ;  but  so  far  as  we  are 
aware  steel  sections  at  such  a  high  magnification  have  not 
been  available.  This  may  be  easily  accounted  for  by  the  difficulties 
in  the  way.  Although,  unfortunately,  we  are  unable  to  indicate 
an  easy  path  by  w^hich  these  difficulties  may  be  avoided,  we  propose 
to  show  the  means  by  which  we  endeavour  to  overcome  them. 

We  have  already  laid  stress  on  the  need  for  an  objective  of  high 
resolving  power  capable  of  giving  good  definition  when  combined 
with  a  properly  compensated  eyepiece  of  high  magnifying  power. 

Probably  the  next  most  essential  point  is  that  the  specimen  to  be 
photographed  be  properly  etched.  Deep  etching  is  fatal ;  it  causes 
pits  and  furrows  in  the  surface  of  the  piece  which  extend  beyond  the 
range  of  depth  of  focus,  which  with  a  high  power  objective,  is  naturally 
very  limited.  Therefore  the  most  delicate  etching  is  necessary,  and 
this  we  find  is  usually  best  obtained  with  5  per  cent.  Picric  Acid  in 
Alcohol.  "  _ 

The  illumination  of  the  specimen  for  photography  is  the  next 
subject  for  attention.  For  high  power  photography  the  lighting 
should  be  as  intense  as  possible.  We  use  a  20  ampere  arc  lamp  of  the 
hand  fed  type,  and  this  is  found  preferable  to  one  mechanically 
fed.  It  is  simple,  has  no  mechanism  to  get  out  of  order,  and  the 
carbons  are  not  liable  to  re-adjustment  at  the  critical  moment,  just 
when  the  plate  is  being  exposed.  Moreover,  mechanically  fed  carbons 
are  never  so  firm  and  free  from  vibration  as  those  of  the  hand  fed 
types.  Alternating  current  at  about  70  volts  can  be  used  with  perfect 
success  on  a  20  ampere  hand  fed  lamp,  if  cored  carbons  are  used. 
This  is  a  point  on  which  emphasis  should  be  laid,  for  the  makers  of  our 
apparatus  have  always  laid  stress  on  the  necessity  for  direct  current  for 
photomicrographic  work.  Tungsten  Arc  and  Mercury  Vapour  Lamps 
have  been  more  recently  introduced  for  photomicrographic  work, 
but  we  have  had  no  opportunity  of  testing  them. 

The  vertical  illuminator  attached  to  the  Microscope  should  be  a 
plain  glass  disc.  We  find  a  prism  unsatisfactory  for  this  work.  The 
light  should  be  focussed  on  the  diaphragm  of  the  vertical  illuminator, 
and  of  course  it  must  be  perfectly  central  with  the  Microscope  and 
the  camera. 

The  iris  diaphragm  of  the  illuminator  should  only  be  closed  as  much 
as  is  necessary  to  get  sufficient  of  the  field  sharp.  Further  closing 
of  the  diaphragm  not  only  interferes  with  the  resolution,  but  produces 
false  images.  An  example  of  this  effect  is  shown  in  Figs. 
10  and  II,  Plate  D.  Fig.  10  illustrates  the  result  produced  by 
closing  the  diaphragm  too  much,  and  Fig.  11  shows  a  correct  image 
obtained  by  proper  adjustment. 

The  diaphragm  in  the  condenser  system  should  be  closed  so  that 
only  the  area  to  be  photographed  is  illuminated. 

For  apochromatic  objectives,  a  blue  screen  as  a  light  filter  should 
be  used,  and  ordinary  photographic  plates.  The  specimen  is  focussed 
first  of  all  on  the  ground  glass  screen  of  the  camera,  and  finally  adjusted 


160         PJIOTOMICROGRAPHS  OF  STEEL   AND  IRON 

with  the  clear  glass  screen  and  the  aid  of  the  focussing  magnifier. 
There  is  one  point  that  has  not  been  mentioned,  which  is  quite  obvious, 
and  that  is  the  necessity  that  the  mounting  of  the  whole  photomicro- 
graphic  apparatus  should  be  perfectly  rigid  and  free  from  vibration. 

We  have  selected  a  few  photomicrographs  in  order  to  show  the 
effect  of  increasing  magnifications  on  the  same  section,  and  also  to 
illustrate  well-known  types  of  microstructure  at  high  magnifications. 
The  objectives  used  in  obtaining  photographs  at  1,500  and  over  are 
stated  on  the  plates. 

The  photographs  on  plates  A,  B,  C  and  D  have  already  been  dealt 
with  in  the  text. 

PLATE  E.  — Figs.  12,  13,  14  and  15,  show  the  microstruc- 
ture of  a  Nickel  Chromium  Alloy  Steel  in  two  different  conditions. 
Even  at  1,500  magnifications  the  structure  is  seen  to  be  very  fine  and 
close  textured  ;  it  is  rather  more  clearly  defined  at  5,000  magnifications, 
but  a  structure  of  this  kind  is  very  difficult  to  photograph  owing  to 
the  want  of  contrast  obtained  even  with  the  most  careful  etching. 

PLATE  F.  —  Figs.  16,  17,  18  and  19  show  the  structure 
of  Grey  Cast  Iron.  The  black  constituent  is  Graphite,  and  the  ground 
mass  Pearlite.  The  four  photographs  on  this  plate  illustrate  very 
strikingly  the  advantage  of  higher  magnifications  in  order  to  see 
clearly  the  details  of  a  fine  Pearlitic  structure. 

An  additional  photograph  (Fig.  19a)  is  given  on  Plate  F,  which  has 
been  obtained  by  making  an  enlargement  of  the  negative  from  which 
Fig.  18  was  obtained.  The  enlargement  has  been  so  adjusted 
that  its  magnification  is  5,000  ;  a  comparison  is  therefore 
obtainable  with  that  of  Fig.  19,  which  has  been  obtained  by 
the  direct  method.  There  does  not  appear  to  be  much  to  choose  between 
the  two  Photographs  in  this  instance,  but  in  the  case  of  more  com- 
plicated subjects  such  as  those  illustrated  in  Figs.  20  to  22  on  Plate  G, 
the  direct  method  of  photomicrography,  although  very  much  more 
difficult  than  the  indirect  one  of  enlargement,  is  far  preferable  to  the 
latter  because  the  choice  of  field  to  be  photographed  is  made  at  high 
magnification — an  important  advantage. 

PLATE  G.  —  Figs.  20,  21  and  22.  Photographs  20  and 
21  show  the  microstructure  of  a  Carbon-Chromium  steel  in  two  different 
conditions,  magnified  8,000  diameters.  The  former  is  a  Sorbitic 
Pearlite  structure,  and  the  latter  consists  of  Martensite  and  Troostite 
(black  areas).  —  Fig.  22  shows  the  microstructure  of  a  quenched 
Carbon  steel  at  8,000  magnifications,  and  is  Troosto-Martensite. 

PLATE  H.  —  Fig>s.  23,  24  and  25.  These  photographs  show 
the  microstructure  at  5,000  magnifications  of  a  steel  containing 
1.41  per  cent.  Carbon  in  three  different  conditions.  Fig.  23  is 
a  typical  Pearlite  and  Cementite  structure  ;  Fig.  24  a  Martensitic 
structure,  and  Fig.  25  a  structure  of  mixed  Troostite  and  Cementite. 

The  value  of  higher  magnification  especially  as  illustrated  in 
Figs.  8,  9  and  19  can  be  emphasised  as  a  result  of  this  research. 
These  Photographs  at  higher  magnifications  show  in  a  striking  manner 
the  details  of    a    structure  which   at  lower  magnifications  are  only 


PLATE  A. 

Examples  of  early  Photomicrographs  from  Sorby's  Paper  to  the 

IroD  aud  Steel  Institute,  1887,  '•  On  the  Microscopical  Structure 

of  Iron  and  Steel." 

Figure  i. 


Photomicrog-raph  by  Sorby. 
Magnification  q. 


FlGUUE  2. 


Photomicrograph  by  Sorby 

Magnification  q. 

Blister  Steel,  Longitudinal  Section. 


Magnifirati.m  600. 
MM.  APOCIIKOMAT. 


The   Steel    used   in    ihis    F.xiK-iinient    had    the    folio 
r.       Si.         S.  P.  Mn. 

.48       .17       ■o:!o       .034       i-co?^ 


aphs  showing  the  Effect  of  Magnification  without  liesolu 


L. 


PLATE    D. 


Photoniic  logiaphs   showing-,   respectively,   the  effect  of  Incorrect  and  Correct  use  of  the  Iris  Diaphragm. 


» 


ANNEALED. 


FINE   LAMELLAR   AND  SOKBITIC 
in  this  Lxreriment  had  the  following  composition : 


ITE  AND  SORBITE. 


OF   PKAKUn;    \ND    ORAPIIITE. 


C.        Gr.        Si. 


■  ''^*-- 

^H 

P^^ 

^? 


enlari,i:mknt  from  negauve  of  phot 


u,    AI'OCIIROM 

souniTE. 

hp-A  and  Tempered. 


C.       Si.        S. 


Macnificalion  8, 

1,1   MM.    .\P0CHl<OM..Vt 
M.MtTF.NSITI'.  AND  TROOSTl 
Quenched. 


.0:,        .3,       2.5,% 


\nnriiRnMAT 


SECTIONS   AT   HIGH   MAGNIFICATION  161 

very  indistinctly  seen ;  at  the  same  time  we  are  quite  alive  to  the 
fact  that  they  have  not  led  us  to  any  absolutely  new  discovery  in  the 
microstructure  of  Steel,  and  it  is  quite  evident  that  there  is 
an  important  field  open   for   further   investigations  in  this  direction. 

During  the  last  few  months  we  have  been  prosecuting  enquiries 
in  different  directions  with  a  view  to  obtaining  apparatus  which  would 
enable  us  to  attain  much  higher  resolution  than  has  been  practicable 
with  that  at  our  disposal.  While  so  far  we  have  not  been  able  to 
do  this,  several  makers  of  apparatus  and  objectives  in  this  Country 
are  working  at  the  problem,  which  we  feel  sure  will  soon  be  solved. 

We  have  also  been  specially  interested  in  the  possibilities  that 
might  lie  in  the  use  of  Ultra-violet  Light  for  Photomicrography  applied 
to  Metal  Sections.  Who  knows  what  new  order  of  Phenomena  may  not 
be  brought  within  our  vision  by  the  use  of  such  apparatus.  Researches 
are  being  made  in  this  new  field,  and  we  all  hope  that  such  labours 
will  be  crowned  with  success. 

In  conclusion  it  is  hoped  that  by  presenting  these  Photomicrographs 
interest  will  be  aroused  in  this  special  subject  and  that  others  will 
press  forward  investigations  from  which  our  general  knowledge  of  the 
subject  will  benefit ;  also  that  the  makers  of  the  necessary  Apparatus, 
whether  Microscopes,  Lenses  or  Lighting  Appliances,  will  come  forward 
with  new  developments  which  will  enable  still  further  fields  to  be 
explored  in  the  now  Unknown. 


THE   HIGH-POWER   PHOTOMICROGRAPHY  OF  METALS. 

By  F.  C.  Thompson,  D.Met.,  B.Sc.   (Lecturer  on  Metallurgy  in  the 
University  of  Sheffield). 

I. — General. 

The  high-power  microscopical  examination  of  metals  is  a  matter  of 
the  greatest  importance. 

As  Prof.  Abbe  has  pointed  out,  however,  and  this  forms  practically 
the  whole  of  the  sermon  which  the  author  desires  to  preach,  "  empty 
magnification  "  unaccompanied  by  a  corresponding  resolving  power 
is  of  no  service  whatever  to  the  metallographer. 

As  is  well  known,  it  is  impossible  to  produce  a  microscopical 
rendering  of  a  point  other  than  as  a  disc  of  definite  dimensions  the 
size  of  which  depends  on  (1)  the  numerical  aperture  of  the  objective, 
(2)  on  the  wave-length  of  the  light  employed,  and  (3)  on  the  magnifica- 
tion. The  diameter  of  this  spurious  disc  D  =  — ^  .  where  m  is  the 
magnification,  X  the  wave-length  of  the  light  used,  and  N.A.  the 
numerical  aperture  of  the  objective.  It  will  be  at  once  seen  that 
the  image  becomes  less  and  less  sharp  as  the  wave-length  of  the  light 
increases  and  as  the  ratio  of  the  total  magnification  to  that  produced  by 
the  objective  itself  is  raised. 

As  shown  in  Fig.  1,  a  succession  of  points  may  thus,  if  sufficiently 
near  each  other,  merge  into  an  apparently  continuous  line,  the  trao 
structure  of  which  would  never  be  realised.  Sorbite  might  in  this 
way  simulate  pearlite.  A  very  beautiful  illustration  of  this  effect 
in  a  diatom  is  given  by  Spitta,  "  Microscopy,"  Fig.  3A,  Plate  I. 
It  will  further  be  evident  that  a  sorbite  in  which  the  diameter  of 
the  spurious  disc  exceeds  the  distance  between  the  carbide  globules 
will  appear  practically  structureless,  Fig.  2A,  and  that  pearlite,  tie 
distance  between  the  laminae  of  which  does  not  exceed  tins  diameter, 
will  lose  its  structure.  Fig.  2B.  The  matter,  therefore,  is  of  very 
real  practical  import. 

Abbe  has  shown  that  in  the  absence  of  certain  diffraction  spectra 
a  line  may  be  duplicated,  or  even  rendered  as  three.  Although  in 
metallurgical  work  such  results  are  unlikely — they  would,  for 
instance,  double  or  treble  the  fineness  of  a  laminated  eutectic — the 
possibility  of  such  spurious  effects  at  very  high  magnifications  should 
always  be  borne  in  mind. 

According  to  Spitta  the  limit  of  magnification  to  which  it  is 
permissible  to  go  with  light  of  wave-length  540  ium-  must  never 
exceed    1,000   times  the  numerical   aperture  of  the  objective. 

It  would  thus  appear  that  the  best  method  of  approach  to  the 
very  high  magnifications  suggested  lies  at  the  present  time  in  the 
use  of  ultra-violet  "  light  "  of  very  short  wave-length.  Since  glass 
is  opaque  to  such  vibrations,  quartz  or  fused  silica  must  be  used  as 
the  optical  material  of  all  lenses,  vertical  illuminators,  etc.  In 
connection  with  metallographic  work,  since  the  objective  acts  as  its 
own  condenser,  and  since  no  slips  or  cover  glasses  are  required,  such 
a   system   is  much   cheaper  than   it   can   be   when   using   transmitted 

162 


Thompson.— 1. 


Fig.  I. 

Effect  of  Halo  in   Producing-  a 
Spurious  Lamination. 


A  B 

Fig.  2. 

Structureless    Rendering-    of    Sorbite 
or  Pearlite. 


Fig.  3. 
Effect  of   Prism   Illuminator. 


F.   C.    THOMPSON  163 

light."  The  lenses  in  the  objective  are  constructed  of  fused  silica, 
those  of  the  eye-piece  of  quartz.  A  mixture  of  glycerine  and  water 
of  the  required  refractive  index  is  used  as  an  immersion  liquid,  and 
focussing  is  carried  out  by  the  use  of  a  fluorescent  screen.  So  far 
as  the  author  is  aware  the  highest  power  silica  objective  so  far  made 
is  the  1.7  mm.  with  1.25  JST.  A.  In  virtue,  however,  of  the  shortness 
of  the  wave-length  used,  275  jufi,  this  is  equivalent  to  about  2.5  N.A., 
using  white  light,  and  according  to  the  rule  given  above  could  be  used 
for  critical  work  up  to  2,500  diams.,  which  would  be  obtained  with, 
say,  a  x  15  eye-piece  and  a  camera  length  of  31  c.m.s.  There  appears 
to  be  a  very  big  field  of  usefulness  for  this  system  in  metallographic 
research  work. 


II. — The    Davidson    "  Super-Microscope." 

The  claims  made  for  this  instrument  in  connection  with  very 
high  magnifications — up  to  15,000  diams. — render  a  consideration  of 
its  capabilities  germane  to  this  paper.  In  essence,  an  image  is 
formed  in  the  usual  manner  by  a  microscope  objective,  which  image 
is  then  magnified  by  a  second  microscope,  with  or  without  an  eye- 
piece. Such  a  procedure  demands  for  the  highest  magnifications 
an  amplification  of  the  primary  image  so  high  that  no  objective  at 
present  made  will  stand  it.  In  theory  the  instrument  is  unsound, 
and  in  practice,  so  far  as  the  author's  observations  go,  the  results 
at  high  magnifications  are  very  poor.  Through  the  kindness  of  Sir 
Robert  Hadfield  the  apparatus  was  sent  to  the  author  some  two  or 
three  years  ago  for  investigation.  Since  then  the  mechanical  side 
has  been  considerably  improved,  the  optical  arrangement  remaining, 
however,  unchanged.  Quite  recently  another  opportunity  has  arisen 
for  his  observation  of  the  instrument,  but  his  view  is  unchanged. 
In  the  trial  two  test  objects  were  chosen,  one  a  very  fine  eorbitic 
structure  in  a  quenched  and  tempered  tool  steel,  the  other  a  normalised 
Bessemer  steel  with  0.4  per  cent,  carbon,  and  1  per  cent,  manganese, 
the  pearlite  in  which  was  finely  laminated.  With  a  magnification 
of  1,000  diams.,  using  Zeiss  lenses  and  the  ordinary  apparatus,  both 
objects  were  easily  resolved.  At  the  same  magnification,  however, 
the  "Super-microscope"  failed  entirely.  The  sorbitic  material 
appeared  structureless,  while  in  the  case  of  the  pearlite  only  the 
faintest  suggestion  of  lamination  could  be  detected.  At  higher 
magnifications  the  apparatus  is  utterly  valueless. 

The  very  claim  put  forward  for  the  instrument  that  it  possesses 
great  depth  of  focus  is  in  itself  an  admission  that  the  resolving  power 
is  poor,  since  these  two  factors  vary  inversely  as  each  other.  Since 
for  the  purpose  at  present  under  consideration,  viz.,  high  magnification 
of  metalhc  structure,  depth  of  focus  is  of  no  importance,  while 
resolution  is  a  matter  of  prime  weight,  the  remarks  previously  made 
are  still  further  substantiated. 

For  other  purposes,  as  a  telescope,  or  for  low  power  examination 
of  a  metallic  fracture  where  great  depth  of  focus  is  quite  necessary, 
the  apparatus  probably  offers  very  real  advantages.  In  particular, 
perhaps,  may  be  mentioned  direct  measurements  from  some  distance 
of  changes  in  length,  such  as  are  needed  in  a  determination  of 
co-efficient  of  thermal  expansion. 


164  THE  HIGH-POWER   PHOTOMICROGRAPHY 

III. — The    Reichert    Microscope. 

This  instrument,  which  is  too  well  known  to  need  description 
here,  has  often  been  regarded  as  a  convenient  apparatus  for  use  in 
those  industrial  establishments  where  convenience  and  rapidity  of 
working  are,  perhaps,  of  somewhat  greater  importance  than  the  very 
finest  definition  and  resolving  power.  An  investigation  recently  made 
by  Professor  Carl  Benedicks  and  E.  Waldow  (Jern-Kontorets 
Annaler,  1918,  537)  has  shown,  however,  that  far  from  such  being 
the  case,  photographs  of  the  very  highest  quality  can  be  obtained. 
Several  micrographs  published  by  these  workers  at  1,200  diams.  leave 
little  or  nothing  to  be  desired.  The  perfection  is  further  illustrated 
by  an  enlargement  at  3,500  diams.  which  constitutes  one  of  the  most 
excellent  photomicrographs  of  steel  at  such  a  magnification  ever 
obtained.  This  magnification,  however,  has  only  been  used  to  show 
what  sort  of  effect  is  the  best  at  present  obtainable,  and  does  not 
represent  one  which  will  yield  critical  results.  Around  the  globules 
and  laminae  of  FcaC  are  thick  black  halos  up  to  and  exceeding 
0.5  mm.  thick. 

The  authors  point  out  the  much  lower  quality  of  picture  obtained 
when  the  prism  vertical  illuminator  is  used  as  compared  with  that 
when  the  plain  disc  is  chosen.  '  This  fact,  first  pointed  out  by 
Professor  Benedicks  himself,  is  one  of  prime  importance  in  connection 
with  high  power  microscopy.  Since  in  one  direction  the  prism  cuts 
off  half  of  the  back  lens  of  the  objective,  the  resolving  power  is 
curtailed  accordingly.  To  pay  big  prices  for  Zeiss  lenses  of  high 
N.A.  and  then  deliberately  to  cut  down  by  the  prism  illuminator  the 
resolving  power  to  much  less  than  that  obtainable  with  a  lens  of 
similar  focal  length  at  a  fraction  of  the  cost,  argues  a  very  poor 
acquaintance  with  the  theory  of  the  instrument.  Since  this  loss  of 
resolution  operates  chiefly  in  one  direction,  there  is  a  tendency  for  a 
circular  object  to  be  drawn  out  into  an  ellipse.  Further,  rows  of 
globules  oriented  in  the  direction  of  the  longer  axis  of  the 
ellipse  are  much  more  likely  than  ever  to  be  rendered  as  a  continuous 
band,  while  laminated  structures  maj'  appear  structureless  or  be 
correctly  resolved,  according  to  the  direction.  Fig.  3.  The  marked 
superiority  of  the  disc  should  need  no  further  emphasis. 

As  one  would  expect,  the  strength  of  the  source  of  light  is  shown 
to  be  without  effect  on  the  quality  of  the  photograph  produced.  When 
vibration  is  considered,  however,  and  this  is  rarely  absent  from 
steel  works  laboratories,  the  much  shorter  exposure  required  with 
powerful  arc  illumination,  renders  it  then  possible  to  obtain  sharper 
negatives  than  with  weaker  lighting.  In  connection  with  vibration 
it  is  suggested  that  the  objective  should  be  separated  from  the  body 
tube,  which  will  result  in  a  considerable  decrease  of  mass  in  those 
parts  specially  sensitive  to  vibration,  whereby  the  amplitude  of  the 
latter  will  be  reduced  and  non-recurring. 

While  considering  this  point,  the  following  is  of  importance. 
Given  a  certain  primary  image,  this  can  be  magnified  in  two  ways.  In 
the  first  place,  it  may  be  eye-pieced  strongly,  or  alternatively,  an  eye- 
piece of  lower  magnification  can  be  used  with  a  long  camera  extension. 
Given  absolutely  rigid  conditions  there  does  not  appear  to  be  very  much 
to  choose  between  the  two  methods,  although  perhaps  the  long  camera 


OF  METALS:    F.  C.   THOMPSON  165 

is  better  since,  in  general,  a  larger  field  would  be  obtained.  In  cases 
where  vibration  may  make  its  influence  felt,  long  camera  lengths 
rarely  yield  satisfactory  results,  since  the  extent  of  the  oscillations 
increases  with  the  length.  It  would -appear,  therefore,  that  in  this 
case  on  the  few  occasions  when  it  is  necessary  to  push  the  magnifica- 
tion of  a  given  image  as  far  as  possible,  it  is  advisable  to  use  a  high 
eye-piece  and  short  camera  extension  rather  than  the  reverse. 

In  connection  with  the  use  of  the  projection  eye-pieces  it  was 
discovered  that  the  setting,  i.e.,  the  relative  positions  of  eye  and 
field  lens,  which  requires  adjustment  for  different  lengths  of  camera, is 
dependent  not  only  on  this  and  on  the  ocular  used,  but  also  upon 
the  objective.  The  effect  of  the  latter  is  shown  to  be  considerable, 
and  the  statement  made  that  "  the  possibility  of  movement  of  a 
projection  eye-piece  is  practically  superfluous,"  must  be  admitted  to 
carry  weight,  although  it  is  at  variance  with  present  notions.  Four 
diagrams  are  given  in  which  the  camera  length  is  related  to  the  best 
setting  of  the  eye-piece  for  objectives  of  different  focal  lengths. 

In  conclusion,  another  direction  in  which  modifications  of  existing 
methods  might  be  of  value  may  be  pointed  out.  Cases  may  welt 
arise  in  which  extremely  oblique  rays  would  reveal  a  structure  in 
what,  when  viewed  directly,  appears  to  be  a  structureless  constituent. 
The  insertion  of  suitable  diaphragms  behind  the  back  lens  to  effect 
this  would  facilitate  at  times  the  resolution  of  a  "  line  "  into  its 
component  dots.  The  general  rendering  of  an  object  would  be 
deleteriously  effected  by  such  a  procedure,  but  in  certain  cases  distinct 
advantages  might  be  gained. 


ILLUMINATION  IN  MICRO-METALLOGEAPHY 
By  Henry  M.   Sayers. 


In  discussing  this  subject  before  this  audience  it  is  only  necessary 
to  set  out  certain  propositions  as  assumed  and  accepted  to  give  form 
and  cohesion  to  the  whole  treatment.  These  assumed  propositions 
are  as  follows  :  — 

1.  Correct  illumination  is  essential  to  obtain  the  best  results  of 
which  the  objectives  and  oculars  used  are  capable. 

2.  The  principles  of  correct  illumination  are  the  same  for  the 
examination  of  opaque  objects  such  as  those  studied  in  metallography 
and  that  of  the  (partially)  transparent  objects  examined  by  transmitted 
light. 

3.  The  illumination  which  permits  of  the  utilisation  of  the  maxi- 
mum potential  resolving  and  defining  power  of  any  objective  is  given 
by  an  dmage  of  the  source  of  light  projected  on  to  the  object,  formed 
by  cones  of  light  with  apex  angles  approximating  to  the  angular 
aperture  of  the  objective  in  the  medium  used. 

4.  Micro-metallography  implies  the  use  of  the  highest  optical  power 
available — though  not  necessarily  in  every  case — and  the  use  of  photo- 
graphic records. 

5.  Micro-metallography  implies  the  use  of  some  form  of  "  vertical 
illuminator,"  and  of  the  objective  as  a  condenser,  in  all  but  quite 
low-power  work. 

6.  It  is  desirable  to  shorten  photographic  exposures  as  much  as 
possible,  especially  at  high  magnifications,  and  to  avoid  "glare"' 
which  reduces  contrast  and  obscures  fine  detail. 

7.  The  present  effective  magnification  has  an  upper  limit  of  about 
1,000  diams.,  due  to  the  limitation  of  the  N.A.  of  objectives  to 
a  maximum  of  about  1.4  by  the  optical  constants  of  the  glasses  and 
immersion  media  available.  Any  increase  in  N.A.  and  effective 
magnification  will  require  a  corresponding  increase  in  illumination 
efficiency. 

Proposition  5  sets  out  two  conditions  which  constitute  important 
differences  in  the  application  of  correct  illumination  to  opaque  and 
to  transparent  objects,  and  give  rise  to  the  principal  difficulties  in 
attaining  good  illumination  in  metallography.  The  vertical  illuminator 
entails  a  great  loss  of  light.  The  use  of  the  objective  as  the  condenser 
also  entails  limitations  which  do  not  arise  in  the  same  degree  when 
these  two  components  of  the  optical  system  are  independent. 

If  a  total  reflection  prism  is  used  as  the  vertical  illuminator  it  may 
reflect  nearly  100  per  cent,  of  the  light  falling  on  it  into  the  objective, 
but  it  intercepts  all  the  light  from  the  objective  passing  towards  the 
image  plane  which  falls  on  it.  In  the  best  case  the  prism  occupies 
half  the  objective  aperture,  only  half  the  objective  receives  light  from 
it,  and  half  the  light  going  to  th^  image  is  intercepted.  Hence  only 
25  per  cent,  of  the  illuminating  beam  can  be  utilised  in  the  image.  If 
the  prism  is  either  larger  or  smaller  the  percentage  of  light  getting 
through  to  the  image  is  less  than  25  per  cent. 

166 


HENRY     M.     SAYERS  167 

Similarly,  if  a  cover-glass  type  of  reflector  is  used  the  maximum 
illumination  possible  theoretically  would'  be  given  if  the  reflector 
reflected  50  per  cent,  of  the  light  and  transmitted  50  per  cent.  The 
result  would  be  25  per  cent,  of  the  light  utilised.  No  cover-glass 
type  reflector  does  nearly  so  well  as  this.  Measurements  of  a  clear 
cover-glass  have  given  me  a  reflective  power  of  13.8  per  cent,  com- 
pared with  a  silvered  total  reflection  prism,  and  a  transmission  of 
66  per  cent.,  with  the  glass  inclined  at  45°  to  the  beam.  The 
resultant  for  the  image  illumination  is  therefore  13.8  x  66  per  cent, 
or  9.2  per  cent,  for  the  image.  A  semi-platinised  cover-glass  (not 
made  for  the  purpose)  gave  38  per  cent,  reflection,  but  only  21.5  per 
cent,  transmission  or  8.17  per  cent,  for  the  image.  The  light,  too, 
was  brownish  yellow. 

The  prism  reflector,  while  much  superior  to  the  cover-glass  in 
respect  to  illumination,  cuts  down  the  effective  aperture  of  the  objec- 
tive, both  as  a  condenser  and  as  an  objective,  and  does  this  unsym- 
metrically  to  the  detriment  of  its  resolving  power.  This  is  probably 
the  reason  why  prism  reflectors  are  never  made  to  cover  nearly  so 
much  as  half  the  objective  aperture,  and  they  are  consequently  not  in 
practice  much  better  than  cover-glasses  in  respect  to  brightness  of 
image. 

The  diminution  of  light  intensity  in  the  image  compared  with  that 
reflected  by  the  object  is  proportional  to  the  square  of  the  lineal  magni- 
fication, increased  by  absorption  and  reflection  in  the  optical  system. 
With  100  diameters  the  light  intensity  at  the  image  is  under  one  ten- 
thousandth,  and  with  1,000  diameters  under  one-millionth  part  of  the 
light  reflected  by  the  object.  Allowing  for  the  loss  due  to  the  vertical 
reflector  it  is  for  the  two  magnifications  mentioned  less  than  one  forty- 
thousandth  and  one  four-millionth  part  respectively  of  the  light  inten- 
sity of  the  source  for  any  part  of  the  object  which  has  perfect  reflecting 
power,  assuming  that  the  image  of  the  source  is  as  bright  as  the  source 
itself.  As  these  small  fractions  are  on  assumptions  of  100  per  cent, 
efficiency  for  every  stage  of  reflection  and  refraction  between  the 
source  and  the  image,  which  is  unattainable  everywhere,  it  may  be 
roughly  estimated  that  the  actual  fractions  of  the  source  brightness  in 
the  brightest  points  of  the  image  will  be  more  nearly  one  ten-thousandth 
and  one  ten-millionth  respectively.  The  most  obvious  improvement 
would  be  the  devising  of  a  vertical  reflector  giving  an  efficiency  of  com- 
bined reflection  and  transmission  approximating  to  25  per  cent,  without 
cutting  down  the  objective  aperture. 

The  exposure  required  is  that  for  the  "  shadows  "  of  the  object, 
i.e.,  for  the  darkest  parts  which  show  perceptible'  detail.  It  follows 
that  to  get  reasonable  exposure  times  only  light  sources  of  great 
intrinsic  brilliancy  are  of  practical  use  for  photographic  work.  The 
total  candle-power  of  the  radiant  is  no  criterion  by  itself,  it  is  candle- 
power  per  unit  area  of  radiating  surface  which  counts. 

Of  the  available  sources  the  positive  crater  of  the  carbon  arc  is 
the  most  brilliant.  After  that  come  in  descending  order  the  Nernst 
lamp,  the  tungsten  arc  (or  Pointolite),  the  half-watt  metal  filament 
lamp,  and  the  oxy-hydrogen  lime-light.  The  last  named  is  the  only 
light  source  depending  on  combustion  at  all  suitable  for  the  purpose, 


168     ILLUMINATION    IN    MICRO-METALLOGRAPHY: 

but  it  requires  cumbersome  accessories  and  so  much  attention  that  it 
need  hardly  be  considered  unless  an  electric  supply  is  quite  out  of 
reach. 

The  mercury  vapour  lamp  ought  to  be  mentioned,  but  the  writer 
has  no  experience  of  it,  can  find  no  information  as  to  its  intrinsic 
brilliancy,  and  has  seen  no  form  of  the  lamp  which  is  convenient  for 
metallography.  The  nearly  monochromatic  quality  of  the  light  is  in  its 
favour,  and  it  is  probably  capable  of  being  put  into  a  very  useful  and 
efficient  shape  for  the  purpose. 

The  arc  crater  gives  the  highest  light  intensity.  With  the 
requisite  attention  it  is  unsurpassable  in  rapidity  and  quality  of  nega- 
tives. But  it  has  some  disadvantages.  The  positive  crater  is  somewhat 
obscured  by  the  tip  of  the  negative  carbon,  the  crater  surf  ace  is  not  always 
of  uniform  brilliancy  all  over,  and  the  crater  may  shift  during  an  exposure 
from  one  part  of  the  carbon  to  another.  Such  unsteadiness  may  arise 
from  the  arc  length  being  too  great  from  an  endeavour  to  get  the 
negative  tip  out  of  the  field  of  view;  from  impurities  in  the  carbons, 
or  from  draughts.  The  arc  length  has  to  be  adjusted  at  intervals  of 
a  few  minutes.  The  arc  does  not  steady  down  until  it  has  been  burning 
for  several  minutes.  It  is  therefore  an  item  of  the  equipment  to  be 
attended  to  and  Waited  on.  The  arc  gives  off  a  large  amount  of 
radiant  heat  which  has  to  be  considered  in  relation  to  any  auxiliary 
lens  system  required.  It  therefore  leaves  something  to  be  desired  in 
point  of  convenience  and  its  rapidity  in  photographing  is  subject  to 
some  discount  for  the  time  taken  in  attending  to  it. 

The  Nernst  lamp  is  excellent  in  many  ways.  It  requires  no  globe, 
no  attention,  and  is  quite  steady.  It  gives  off  relatively  little  radiant 
heat.  It  can  be  used  on  either  continuous  or  alternating  current.  The 
shape  of  the  radiant  surface,  a  rod  of  quite  small  diameter  is  some- 
what inconvenient,  as  it  calls  for  very  accurate  centering  of  any  auxi- 
liary lens  system.  It  has  been  unobtainable  in  this  country  for  some 
years,  as  it  is  made  only  in  Germany.  The  small  diameter  of  the  rod 
obliges  one  to  magnify  it  considerably  by  the  auxiliary  lens  system 
used,  so  that  the  effective  brilliancy  is  not  so  great  as  might  appear. 
With  a  one-ampere  Nernst  lamp  I  have  done  a  good  deal  of  work  on 
steel  at  700  to  1,000  diameters,  and  find  the  exposure  required  to  be 
from  five  to  ten  minutes  at  such  powers,  using  fast  plates  and  a  light 
filter. 

The  Pointolite  or  tungsten  arc  is  free  from  the  inconveniences  of 
the  carbon  arc.  The  source  of  the  light  is  a  small  ball  of  tungsten 
which  appears  in  the  field  of  view  as  a  disc  of  uniform  brilliancy  fixed 
in  position.  Its  intrinsic  brilliancy  from  some  rough  tests  of  my  own 
seems  to  be  about  one-third  that  of  the  carbon  arc  crater.  It  lights 
up  at  once,  is  normal  in  a  few  seconds,  requires  no  adjustment  or 
attention,  and  gives  off  a  relatively  small  amourit  of  radiant  heat.  It 
is  very  promising  and  the  larger  sizes  which  are  being  developed  may 
prove  to  be  as  quick  in  work  as  the  carbon  arc,  when  the  absence  of 
attention  and  unsteadiness  are  taken  into  account.  Like  the  carbon 
arc,  it  requires  continuous  current  for  its  operation. 

Half-watt  lamps  with  straight  filaments  as  made  for  motor-car 
head  lights  are  quite  useful.  Their  intrinsic  brilliancy  is  little  inferior 
to  that  of  the  tungsten  arc.  The  small  diameter  of  the  coiled  filament 
is  open  to  the  same  objection  as  the  Nernst  filament,  i.e.,  it  has  to  be- 


HENRY     M.     SAYERS  169 

much  magnified  to  fill  the  field  of  view,  so  that  the  effective  brilliancy 
is  reduced.  Moreover  the  separate  turns  of  the  spiral 
become  visible  in  a  critical  image.  These  small  lamps 
can  be  run  from  a  few  ignition  cells,  so  that  they  are 
convenient  for  portable  use.  Run  from  an  ordinary- 
supply  circuit  they  require  either  a  resistance  or  a  transformer  to 
reduce  the  pressure  to  6  or  8  volts.  Good  work  has  been  done  at  high 
powers  on  steel  with  a  6-volt  4-ampere  half-watt  lamp,  but  the 
exposure  is  two  to  three  times  as  great  as  with  a  Nernst  lamp.  Up  to  150 
diameters  this  exposure  is  reckoned  in  seconds,  so  the  difference  is 
not  important,  but  for  high  powers  the  exposure  goes  up  to  several 
minutes  (15  to  20),  it  counts  where  much  work  has  to  be  done.  Long 
exposures  are  objectionable  not  only  because  they  limit  the  speed  of 
work;  but  also  because  they  increase  the  risk  of  disturbance  of  the 
image  by  vibration. 

The  illuminations  needed  to  give  short  exposures  are  far  too  bright 
for  comfort  in  visual  examination.  The  interposition  of  a  piece  of 
fine-grained  ground  glass  is  a  simple  remedy.  It  can  be  put  anywhere 
betw^een  the  light  source  and  the  vertical  reflector  and  no  adjustment 
is  disturbed.  The  final  focussing  must  be  done  on  the  ground  glass  of 
the  camera,  whore  the  full  illumination  will  not  be  found  excessive  for 
the  purpose. 

Anyone  starting  on  micro-naetallography  will  find  his  initiation 
much  easier  if  he  tries  first  visual  and  photographic  work  by  trans- 
mitted light  on  transparent  objects.  As  the  sub-stage  condenser  is 
independent  of  the  objective  it  is  much  easier  to  try  variations  of  focus 
and  illumination,  and  the  knov/ledge  so  gained  helps  very  much  to 
recognise  proper  and  improper  condition  in  opaque  v/ork.  Good  objects 
for  such  training  are  section  of  Echinus  spine  for  low  powers,  and 
diatoms  of  various  fineness  of  structure  for  the  higher  ones,  A  student 
who  can  get  a  good  dark  round  negative  of  Echinus  spine  at  100- 
diameters,  and  good  "  black-dot  "  negatives  of  Pleurosigma  Angulatum 
or  Surirella  Gemma  at  1,000  diameters  with  an  oil  immersion  objective 
will  find  work  on  metals  much  simpler  than  if  he  came  to  it  without 
such  practice.  The  superior  resolving  power  and  definition  of  a  given 
objective  with  the  sharp  image  of  the  illuminant  focussed  on  the 
object  from  a  sub-stage  condenser  of  aperture  comparable  to  that  of 
the  objective  will  be  appreciated. 

In  metallography  (excepting  with  the  very  low  powers)  the  objec- 
tive plays  the  part  of  the  sub-stage  condenser  as  well  as  its  own.  Tc^ 
obtain  a  sharp  image  of  the  source  of  light  upon  the  object  when  the 
object  is  focussed  to  the  eye-piece,  certain  distance  relations  betrCveen 
the  illuminant,  the  objective,  the  object,  and  the  image  plane  must  be 
observed.  They  are  simple.  The  light  source  must  be  at  the  same 
distance  from  the  back  lens  of  the  objective  as  the  image  plane,  the 
distances  being  measured  along  the  path  of  the  light  in  each  case. 
Obviously  the  source  and  its  image  on  the  object  are  at  the  conjugate 
focii  of  the  objective;  and  the  object  and  its  image  are  at  equal  conjugate 
focii.  An  immediate  consequence  of  this  relation  is  that  the  illumi- 
nated field  or  useful  part  of  the  image  formed  by  the  objective  is  of 
the  same  dimensions  as  the  source  (real  or  virtual)  of  light  itself.  If, 
for  example,  the  source  of  light  is  the  crater  of  an  arc, one-tenth  of  an 
inch   in   diameter,   the   usefully  illuminated   part   of  the   real  image 


170     ILLUMINATION    IN    MICRO-METALLOGRAPHY: 

formed  by  the  objective  will  also  be  one-tenth  of  an  inch  in  diameter. 
This  identity  of  dimensions  is  independent  of  the  power  of  the  objective. 
A  two-third  inch  with  a  power  of  8  and  a  one-twelfth  inch  wath  a  power 
of  100  with  both  give  an  illuminated  circle  of  one-tenth  inch  diameter 
in  the  image  plane,  provided  that  the  conditions  of  critical  illumination 
are  observed.  If  the  total  magnification  on  the  camera  screen  is  ten 
times  the  objective  image  magnification,  the  effective  field  will  be  one 
inch  in  diameter.  This  is  generally  too  small  for  practical  use,  and 
is  much  smaller  than  the  field  which  the  objective  can  cover.  One 
wants  a  field  at  least  three  inches  in  diameter  to  cover  a  quarter  plate. 
The  assumed  magnification  of  ten  due  to  the  ocular  and  camera  length 
combined  is  about  as  much  as  the  best  objectives  will  usefully  stand. 
So  that  to  cover  a  quarter  plate  the  radiant  should  be  from  a  third  to 
a  half  inch  in  diameter. 

Unfortunately  the  available  sources  of  light  are  of  small  area.  An 
arc  crater  of  a  quarter-of-an-inch  diameter  corresponds  to  an  arc  cur- 
rent of  30  to  40  amperes,  and  is  not  really  large  enough.  As  the 
crater  diameter  increases  only  as  the  square  root  of  the  current,  one 
would  require  a  searchlight  arc,  with  many  tens  of  amperes  to  give  a 
crater  three-quarters  of  an  inch  in  diameter,  which  is  about  the  ideal 
size  to  fill  an  eye-piece.  Such  an  arc  is  not  practicable.  Even  a-  40 
ampere  arc  gives  out  too  much  radiant  heat  to  be  brought  within 
the  few  inches  of  the  microscope  corresponding  to  the  posterior  focus 
of  the  objective.  The  same  difficulty  of  small  area  is  true  of  the 
ether  available  sources.  The  100  candle-power  Pointoliteihas a  radiant 
surface  about  one-tenth  of  an  inch  diameter.  The  Nernst  and  half- 
watt  lamps  have  filaments  of  much  smaller  diameter.  There  seems 
no  good  reason  why  a  half-watt  spiral  lamp  filament  should  not  be  made 
one-third  or  one  half-inch  diameter.  There  may  be  manufacturing 
difficulties,  or  it  may  be  that  the  makers  have  not  seen  that  there  is 
any  use  for  such  lamps.  If  made  the  spiral,  or  rather  helix  should  be 
flattened  to  bring  the  radiant  surface  as  nearly  as  possible  into  a  plane. 

The  actual  radiant  surface  therefore  has  to  be  magnified  in  some 
way  to  give  a  field  of  sufficient  area.  The  simplest  way  is  to  use  a 
short  focus  condenser  to  project  near  the  upper  lens  of  the  objective 
an  image  of  the  radiant.  This  can  be  focussed  on  to  the  stop  of  the 
vertical  illuminator,  and  the  fine  focussing  done  by  eye.  The  image 
thrown  on  the  object  is  that  of  the  aperture  of  the  condensing  lens 
which  is  then  at  the  posterior  focus  of  the  objective.  A  condenser  of 
the  Nelson  type  of  two  inches  full  diameter,  stopped  down  to  one 
inch  aperture  works  well.  It  must  be  carefully  centered toithe radiant, 
and  both  must  lie  on  a  Hne  at  right  angles  to  the  optical  axis  of  the 
microscope.  To  make  these  adjustments  readily,  some  form  of 
mounting  equivalent  to  an  optical  bench,  with  vertical  and  horizontal 
movements  to  either  the  lamp  or  the  lens  is  necessary.  If  the  lens 
is  always  used  for  the  same  stand,  it  can  be  fixed  at  the  height  of  the 
optical  axis,  and  the  adjustments  for  centering  made  on  the  lamj)  car- 
rier. Movement  to  and  from  the  microscope  to  adjust  the  lens  dis- 
tance to  the  optical  tube  length  in  use — which  may  be  different  with 
diff^e'rent  combinations  of  objectives  and  oculars — and  some  movement 
parallel  to  the  body  to  allow  for  the  range  of  movement  of  the  illumi- 
nator aperture,  are  necessary.  These  statements  hold  true  for  any  of 
the  auxiliary  arrangements  described. 


HENRY    M.     SAYERS  171 

The  condenser  must  be  of  short  focus  in  order  to  take  in  a  large 
cone  of  hght  from  the  radiant.  The  Nelson  condenser  mentioned  has 
a  working  distance  of  about  one-and-a-half  inches.  This  is  too  short 
for  an  arc  of  even  ten  amperes,  but  with  a  Nernst  or  half-watt 
lamp  up  to  100  candle  power  the  heat  will  not  injure  it.  The  Pointo- 
lite  lamp  of  100  candle  power  has  a  bulb  which  is  just  too  large  for 
such  a  condenser  to  focus  at  the  required  distance. 

Another  arrangement  is  to  set  up  a  screen  with  an  aperture  of  the 
required  size,  say  seven-eighths  inch  to  one  inch,  which  may  con- 
veniently be  an  iris,  at  the  required  distance  and  to  throw  on  that 
aperture  a  magnified  image  of  the  radiant.  The  image  formed  by  the 
objective  on  the  object  will  then  be  a  reduced  one  of  the  radiant.  This 
arrangement  takes  up  a  good  deal  of  room.  Thus  if  the  aperture  is 
one  inch  in  diameter  and  the  radiant  quarter-inch  diameter,  and  a 
lens  of  four  inches  focal  length  is  used,  the  total  distance  from  the 
microscope  body  will  be  from  32  to  36  inches,  which  is  awkward 
for  making  the  adjustments,  attention  to  the  arc,  etc.  It  is  doubtful 
whether  a  lens  of  four  inches  focal  length  could  be  safely  used  with  an 
arc  giving  a  quarter-inch  diameter  crater.  A  six-inch  or  eight-inch 
focus  would  probably  be  required  and  proportionately  more  distance 
occupied.  It  follows  that  there  is  not  really  much  advantage  in  using 
radiants  larger  than  those  which  permit  of  the  use  of  lenses  of  about 
two  inches  focus.     More  light  is  produced,  but  no  more  is  utilised. 

A  third  method  is  to  present  to  the  objective  a  virtual  image  of 
the  radiant,  i.e.,  to  use  an  auxiliary  lens  as  a  simple  magnifier,  the 
objective  taking  the  place  of  the  eye.  The  focal  length  difficulty  comes 
in  again,  as  the  lens  must  be  closer  to  the  radiant  than  its  focal  length, 
A  lens  combination  with  its  equivalent  plane  well  in  front  of  it,  so 
that  the  working  distance  from  the  radiant  is  greater  than  the  focal 
length,  gets  over  this.  Such  a  combination  which  I  have  used  with 
success  is  a  Nelson  condenser  with  a  flint  concave  between  it  and  the 
microscope.  The  combination  is  really  a  microscope  of  the  Brucke 
type.  The  concave  is  placed  close  up  to  the  aperture  of  the  vertical 
illuminator,  and  focussed  by  moving  the  radiant  to  or  from  it.  As  the 
radiant  and  condensing  combination  are  both  within  a  few  inches  of 
the  microscope  body,  adjustments  are  easily  made  while  observing  the 
object.  The  image  given  by  the  objective  is  a  real  imiage  of  the  radiant. 
The  magnification  may  easily  be  ten  times. 

Whatever  arrangement  is  used  there  should  be  provision  for  inter- 
posing a  ground  glass  or  hght  filter  in  the  path  of  the  beam.  For 
metallography  a  light  filter  is  not  needed  for  securing  contrast  as  in 
stained  specimens  photographed  by  transmitted  hght,  but  for  cutting 
out  the  chromatic  residuals  given  by  even  the  best  objectives.  The 
sharpest  visual  focussing  on  the  camera  screen  without  a  filter  fails 
to  give  an  equally  sharp  negative.  A  green  filter,  such  as  the  F  line 
filter,  or  a  malachite  green  gives  sharper  results  without  a  great  in- 
crease in  exposure. 

With  either  of  the  two  first  named  auxiliary  arrangements  a  glass 
micrometer  can  be  placed  in  the  focal  plane  which  is  the  virtual 
radiant  and  the  scale  image  focussed  on  the  specimen  can  be  photo- 
graphed at  the  same  time.  This  is  equivalent  to  an  eye-piece  micro- 
meter.    Its  size  on  the  camera  screen  is  a  measure  of  the  magnification 


172     ILLUMINATION     IN    MICRO-METALLOGRAPHY: 

due  to  the  ocular  and  camera  length.  Like  any  eye-piece  micrometer, 
its  actual  value  needs  to  be  calibrated  against  a  stage  micrometer, 
but  it  is  available  with  any  eye-piece. 

There  remains  the  difficulty  of  "glare."  The  worst  source  of 
this  trouble  is  reflection  from  the  surfaces  of  the  objective  lenses.  The 
upper  convex  surfaces  are  the  strongest  reflectors.  Fortunately  the 
condition  that  the  illuminating  beam  should  fall  as  if  it  proceeded  from 
the  image  plane,  means  that  it  is  made  up  of  divergent  rays  which  a 
convex  reflector  cannot  bring  to  a  focus,  but  reflects  with  an  increased 
divergence.  Consequently  with  the  light  focussed  correctly  only  a 
small  spot  of  glare  light  appears  at  the  apex  of  the  upper  objective 
lens.  The  bulk  of  the  reflected  light  is  scattered  to  the  tube  sides. 
Obviously  the  objective  mount  and  body  tube  should  be  well  blacked 
inside.  Reflections  from  the  inside  of  lamp  bulbs  and  other  stray  light 
may  give  trouble.  It  is  best  to  keep  all  these  away  by  a  screen,  which 
may  be  the  mount  of  the  auxiliary  lens  or  aperture.  Another  source 
of  glare  is  reflection  from  the  front  lens  of  the  objective.  It  is  only 
troublesome  with  dry  objectives  of  short  working  distance.  With 
those  of  2/3  inch  and  over  it  is  not  serious,  but  it  is  hardly  possible 
to  get  negatives  with  good  contrast  with  dry  objectives  of  1/4  or  1/6 
inch.  Perhaps  this  is  one  reason  for  the  fact  that  very  little  metal 
work  is  done  at  magnifications  between  150  diameters,  the  upper  limit 
of  a  2/3  inch  or  16  mm.  objective,  and  700  diameters  corresponding  to 
a  1/12  inch  or  2  mm.  oil  immersion.  One  can,  of  course,  get  inter- 
mediate magnifications  by  using  low  ocular  and  camera  length  with 
an  oil  immersion,  but  the  field  covered  is  too  small  for  the  general 
view  required.  The  Zeiss  3|  mm.  or  1/7  inch  oil  immersion  fills 
the  gap  very  well.  I  have  tried  to  get  English  firms  to  make  a  similar 
lens,  and  one  maker  listed  a  1/6  inch  oil  immersion  for  metallurgical 
purposes  before  the  war,  but  has  ceased  to  make  it.  I  would  suggest 
that  a  6  mm.  or  8  mm.  oil  immersion  should  be  mad©  for  the  work. 
The  working  distance  need  not  be  too  great  for  the  oil  contact,  no 
cover  glass  has  to  be  allowed  for,  conditions  favourable  to  giving  the 
objective  a  relatively  large  N.A.  without  introducing  specially  great 
manufacturing  difficulties.  The  Zeiss  lens  mentioned  was  quite  cheap, 
and  of  excellent  performance.  A  one  inch  or  2/3  inch  of  about  .30 
N.A.,  a  1/3  or  1/4  inch  oil  immersion  of  about  .70  N.A.,  and  a  1/12 
inch  of  1.3  to  1.4  N.A.  would  furnish  a  metallographer  with  a  bat- 
tery serving  all  the  purposes. 

For  low  power  work  there  is  room  to  put  the  vertical  illuminator 
below  the  objective,  and  it  can  be  arranged  to  give  either  vertical  oi* 
oblique  light.  Even  here  it  will  be  found  advantageous  to  use  an 
image  of  the  radiant  formed  by  an  auxiliary  lens. 

To  sum  up  the  above,  it  may  be  said  that  the  items  in  which 
improvement  is  desirable  are  the  following:  — 

1.  A  transparent  vertical  illuminator  which  shall  get  nearer  the 
theoretical  perfection  of  reflecting  50  per  cent,  and  transmitting  50 
per  cent,  of  the  light  incident  on  it  at  45°,  without  colouring  the 
transmitted  light.  Optically  worked  glass  lightly  platinised  seems 
the  most  promising. 

2.  A  light  source  of  uniform  and  steady  high  brilliancy  presenting 
an  area  of  half-an-inch  square  or  a  little  more,  to  which  a  condenser 
of   2   inch   working   distance  can   be    focussed   without   damage   from 


HENRY    M.     SAYERS  173 

radiant  heat.        Either  the  half-watt  or  the  Pointolite  lamp  may  be 
able  to  meet  this.       The  limitation  of  bulb  size  is  important. 

3.  Oil  immersion  objectives  intermediate  in  focal  length  and 
aperture  between  the  2/3  inch  and  the  1/12  inch,  well  corrected  for 
colour.  If  anything  can  be  done  to  reduce  glare  from  internal 
reflection  in  the  objectives  designed  for  metallography  it  will  be  an 
advantage. 

4.  An  auxiliary  condenser  combination  with  a  long  working 
distance  compared  with  its  focal  length  to  be  used  to  present  a 
magnified  virtual  image  of  the  radiant  to  the  objective.  Suitable 
specification  would  be:  — 

Focal  length,  1|  inches  to  2  inches, 

Working  distance — anterior — 3  inches  to  4  inches. 

Clear  aperture,  f  inch  to  1  inch. 

Well  corrected  spherically  and  chromatically. 

Mounted  with  a  flange  or  a  flanged  collar. 

Cost  reasonable. 

5.  A  simple  firm  optical  bench  or  geometric  slide  arrangement 
with  carriers  for  lamp  and  condenser  at  heights  corresponding  to  those 
of  usual  microscopic  axes  when  in  the  horizontal  and  vertical  positions. 
The  whole  bench  or  slide  to  be  capable  of  movement  parallel  to  the 
microscope  axis  for  2  or  3  inches. 


THE  USE  AND  NEED  OF  THE  MICROSCOPE  IN 
ENGINEERING  WORKS. 

By  S.  Whyte,  B.Sc. 


It  is  not  necessary  in  these  days  to  set  out  in  detail  the  practical 
help  which  is  defived  from  the  use  of  the  microscope  in  engineering. 
Everyone  knows  the  great  benefit  it  has  been  in  controlling  the  question 
of  steel  supplies  and  their  heat  treatment.  By  its  means  inherent 
defects  in  the  steel  are  discovered.  Troubles  may  arise  at  the  steel 
works  through  bad  ingot  pouring,  and  any  pipes  or  seams  which  occur 
in  the  portion  of  the  ingot  which  is  used  finds  its  way  into  the  billets 
and  bars.  Also,  faults  may  arise  in  the  forging  or  stamping  of  the 
steel  w^hich  are  difficult  to  detect  without  a  microscope.  For  finislied 
parts  the  microscope  is  almost  essential  in  working  out  and  standard- 
ising the  best  methods  of  heat-treatment,  and  in  the  event  of  failures 
of  these  parts  in  service,  in  helping  to  discover  the  processes  by  which 
these  failures  originate  and  develop.  This  by  no  means  exhausts  the- 
list  of  uses  to  which  the  microscope  can  be  applied  in  examination  of 
metals  for  engineering  works,  as  the  properties  of  castings — both 
ferrous  and  non-ferrous — can  be  co-related  with  their  various  micro- 
constituents  and  their  distribution  or  crystalline  arrangement. 

The  writer  does  not  propose  dealing  in  detail  with  the  various 
branches  in  which,  from  his  own  experience,  he  has  found  the  micro- 
scope to  be  of  great  value.  It  is  sufficient  to  say  in  passing  that  the 
microscope  ought  to  be,  and  will  be  in  the  near  future,  an  essential 
part  of  the  average  engine'ering  works  equipment,  especially  where  the 
products  being  manufactured  are  subjected  to  live  loads,  and  on  which 
the  safety  of  life  depends. 

The  purposes  for  which  the  microscope  is  used,  as  outlined  above, 
are  three-fold,  and  endless  examples  could  be  given. 

First,  in  the  examination  of  raw  material,  as  supplied  by  the  steel 
makers  and  stampers.  It  is  not  enough  in  all  cases  to  buy  merely  to 
chemical  specifications,  as  two  pieces  giving  the  same  analysis  may 
differ  in  their  usefulness.  One  may  be  sound,  while  the  other  shows 
segregations  and  results  of  ingot  piping.  Faults  such  as  these,  how- 
ever, are  becoming  rare,  as  the  improvements  in  recent  years,  specially 
in  regard  to  ingot  casting,  have  done  much  to  eliminate  them.  It  is, 
however,  still  important  that  samples  of  new  types  of  stampings,  as 
they  come  from  the  makers,  should  be  examined  for  incipient  cracks 
or  "  laps  "  of  oxide  driven  into  the  material,  specially  when  the 
stampings  are  intricate,  and  the  steels  used  are  alloy  steels.  It  is 
impossible  to  tell,  other  than  by  the  microscope,  that  some  of  these 
flaws  exist,  and  it  will  help  the  stamper  to  correct  his  dies,  and  will 
save  time  and  expense  and  the  possibility  of  subsequent  failures  from 
this  cause,  if  defects  can  be  detected  from  the  beginning.  Micro.  No.  I. 
is  an  example  of  this  type  of  defect. 

Secondly,  and  what  is  more  important  from  the  engineer's  ])oint  of 
"'iew,  the  microscoj^e  is  a  great  help  in  arriving  at  the'  best  heat-treat- 
ment temperatures  for  his  steel.  It  is  absurd  to  buy  expensive  high- 
grade  alloy  steels,  and  not  use  every  means  of  obtaining  the  best  results 
from  them.     It  is  equally  extravagant  to  buy  high-speed  steel  for  tools 

174 


S.    WHYTE,   B.Sc.  175 

and  waste  it,  and  much  time  in  the  machine  shop,  through  bad  harden- 
ing. For  machine  parts,  pyrometers  and  testing  machines  are  neces- 
sary in  standardising  methods  after  the  temperatures  have  been 
estabhshed,  but  with  high-speed  steel,  where  the  hardening  tem- 
peratures are  usually  high,  the  recording  of  these  temperatures  is  not 
so  rehable  and  calls  for  all  the  more  precaution  in  testing  the  con- 
ditions by  micro-examination  of  the  steel  after  hardening.  Micros. 
Nos.  II.  and  III.  show  the  structure  of  an  18  per  cent,  tungsten  steel 
heated  to  a  satisfactory  temperature,  and  overheated,  respectively. 
The  overheated,  or  burnt  structure  of  No.  III.,  shows  the  large  crystals 
of  austenite  with  oxide  beginning  to  form  round  their  boundaries.  On 
the  other  hand,  the  best  cutting  properties  of  the  steel  are  not  brought 
out  unless  the  steel  is  heated  to  a  temperature  high  enough  to  diffuse 
all  the  free  iron  tungstide,  which  is  present  in  the  annealed  condition. 
Micro.  No.  IV.  shows  the  same  high  speed  steel  where  the  hardening 
temperature  has  not  been  high  enough  or  the  time  of  soaking  not  long 
enough,  and  too  much  free  tungstide  is  still  present. 

Thirdly,  and  most  important  for  the  engineer,  is  the  use  of  the 
microscope  in  helping  to  locate  the  causes  of  failures,  and  in  working 
out  the  processes  by  which  these  fractures  develop.  The  causes  of 
failure  are  numerous,  and  apart  from  those  due  to  inherent  defects  in 
"the  steel  as  mentioned  above,  the  principal  one  is  that  of  "  fatigue." 
In  "  fatigue  "  fractures,  the  origin  is  usually  found  in  a  weakness  of 
design  or  in  using  steel  of  too  low  an  elastic  limit.  Sometimes  a  piece 
of  non-elastic  slag,  occuring  at  a  point  of  maximum  stress,  sets  up 
local  stresses  high  enough  to  start  a  fracture.  In  designing  machines, 
a  radius  replaces  a  sharp  corner  whenever  possible,  when  working 
stresses  are  set  up  at  these  points,  so  mat  the  stresses  shall  be  dis- 
tributed as  evenly  as  possible.  Sometimes  one  finds  an  accidental 
notch,  such  as  a  file  mark,  in  a  radius,  which  sets  up  a  "  fatigue  " 
fracture.  An  example  of  this  may  be  given,  as  it  brings  out  points 
in  connection  with  the  microscope  objectives,  which  appear  to  be 
■worthy  of  consideration.  Micro.  No.  V.  shows  such  a  V-notch, 
accidentally  made  by  a  file  in  the  radius  at  the  foot  of  a  stop  in  a 
machine  gun  lock  mechanism,  which  received  rapidly  repeated  blows. 
The  notch  has  concentrated  the  stresses  to  such  an  extent  that  over- 
straining of  the  material  has  taken  place,  and  a  crack  is  seen  originat- 
ing at  the  apex  of  the  notch.  The  crack,  as  it  develops,  is  seen  to  be 
deflected  through  a  slag  inclusion,  Micro.  No.  VI.,  and  in  other  places 
in  the  same  specimen  it  was  noticed  that  "  strain  picture  "  was 
highly  developed  round  these  slag  inclusions,  although  fracture  had 
not  commenced. 

In  microphotograph  No.  VII.  this  strain  structure  is  also  seen 
around  the  end  of  the  crack  which  had  penetrated  about  1-16  in. 

It  is  in  cases  such  as  the  above  that  good  objectives  are  necessary, 
and  more  so  when  alloy  steels  are  being  examined.  In  non-ferrous 
metals  the  crystal  grains  are  usually  much  larger,  and  strain  structure 
is  easily  resolved  with  comparatively  low  magnifications.  Microphoto- 
graph No,  VIII.  shows  a  brass  which  had  been  strained  during 
machining. 

It  is  in  photographing  the  fine-grained  steels  that  the  differences 
in  the  microscope  objectives  show  up.  In  photographing  Micro.  No. 
VII.  the  secondary  spectrum  of  the  achromats  would  give  bad  defini- 
tion but,  with  the  elimination  of  this  in  the  apochromats,  by  the  union 


176      THE    MICROSCOPE    IN    ENGINEERING    WORKS 

of  three  colours  of  the  spectrum  at  one  point  instead  of  two  in  the 
achromats,  a  great  improvement  is  effected.  This,  with  the  correction 
for  spherical  aberration  in  two  colours,  gives  an  image  of  greater  sharp- 
ness for  either  white  or  monochromatic  light. 

For  low  power  work,  however,  and  for  certain  subjects  on  higher 
power  work,  a  flatter  field  and  better  results  can  often  be  obtained  by 
achromatic  objectives,  as  the  larger  aperture  of  the  apochromats  tends 
to  give  a  slight  curvature  of  the  image,  which  even  the  compensating 
or  projection  ocular  cannot  entirely  correct. 

At  the  same  time  it  is  felt  that  even  the  best  made  German  objec- 
tives do  not  give  enough  magnification  for  micro-photography,  as  the 
very  fine  structure  of  some  alloy  steels  are  at  present  most  difficult  to 
resolve,  and  much  that  is  now  impossible  to  see  might  be  brought  out 
under  higher  magnifications.  Microphotographs  Nos.  IX.  and  X. 
show  "  etch  figures  "  in  crystals  of  pure  nickel.  These  serve  to 
determine  the  crystalline  system  to  which  nickel  belongs.  The  crystal 
in  Photograph  No.  IX.  shows  a  twinning  plane,  and  the  consequent 
difference  of  orientation  as  shown  by  the  "  etching  pits."  It  is  im- 
possible to  say  what  internal  structures  might  be  brought  out  in  heat- 
treated  alloy  steels  by  higher  magnifications,  as  the  crystal  grains  are 
so  much  smaller  than  those  of  the  nickel  shown  in  Photographs  IX. 
and  X. 

For  metallographic  work  the  following  provisions  on  thei  micro- 
scope seem,  to  the  writer,  to  be  advisable  for  good  work.  The  micro- 
scope should  be  usable  in  the  horizontal  position. 

The  stage  should  have  a  mechanical  movement  in  two  directions,  at 
right  angles  to  each  other.  The  stage  should  also  have  a  racking 
motion  for  focussing,  as  it  is  usually  more  suitable  to  rough  focus  by 
this  means  in  preference  to  that  on  the  tube,  as  it  does  away  with  the 
necessity  of  altering  the  position  of  the  optical  bench.  The  fine  adjust- 
msdnt  is  usually  on  the  tube  of  the  microscope,  and  this  is  the  most 
convenient  place. 

Ordinary  Huygenian  eye-pieces  are  most  suitable  for  achromatic 
objectives,  while  for  the  apochromatic  objectives  special  compensating 
eye-pieces  are  necessary.  For  photography  a  projection  eye-piece 
gives  the  best  results. 

The  disc  illuminator  gives  most  satisfactory  results  and,  with  a 
diaphragm  between  it  and  the  source  of  light,  good  definition  can  be 
obtained. 

The  objectives  as  mentioned  previously  should  be  used  according 
to  the  subject — the  achromats  give  every  satisfaction  for  the  general 
run  of  metallurgical  work  and,  even  in  photography,  are  often  prefer- 
able to  the  apochromats,  by  giving  a  flatter  field.  However,  when 
photographic  records  of  very  fine  detail  are  desired  there  is  no  doubt 
of  the  superiority  of  the  apochromats  for  the  purpose. 

It  seems  to  be  desirable  to  be  able  to  obtain  much  higher  magnifica- 
tions than  are  at  present  obtainable  by  the  present  objectives,  but,  in 
all  probability,  improvements  in  the  methods  of  polishing  the  specimens 
will  also  have  to  be  developed  to  secure  a  surface  good  enough  to  bear 
the  higher  magnification. 

There  is  undoubtedly  a  great  future  before  the  microscope  in  its 
application  to  engineering  work,  in  relation  to  designs,  steel  and  its 
heat-treatment. 


"Whyte.— 1. 


^1^:- 


.C'Ai, 


Fig.  I. 

Spec. :   Small  Forging. 

Ilium. :    Vertical. 

Camera:  66  cms.     Obj. :  20  mm. 

Ocu. :  Projn.     Mag. :  qo  diams. 

Etched:   Picric  Acid. 

Remarks:     Slag    driven    into    steel 

along      ^vith      some      decarbonised 

layers   from   the   surface.     .42%    C. 

steel. 


Fig.  2. 

Spec. :  High-speed  Steel. 
Ilium. :    Vertical. 
Camera:  78  cms.     Obj.:  4  mm. 
Ocu. :  Projn.     Mag. :   500  diams. 
Etched:   Picric  Acid. 

Remarks:   Fine  Grains  of  Austenite 

with  traces  of  free  tungstede  steel 

unabsorbed.      (White  globules.) 


Fig.  3. 

Spec. :  High-speed  Steel. 
Ilium.  :    Vertical. 
Camera:  66  cms.     Obj.:  2  mm. 
Ocu. :  Projn.    Mag.:  1,000  diams. 
Etched:   Picric  Acid. 

Remarks:  Large  grains  of  Austenite 
surrounded  by  oxide. 


Fig.  4- 

Spec. :  High-speed  Steel. 

Ilium. :    Vertical. 

Camera:  78  cms.     Obj.:  4  mm. 

Ocu. :   Projn.     Mag. :   500  diams. 

Etched:   Picric  Acid. 
Remarks:   Fine  grains  of  Austenite 
with    considerable    amount    of    free 

tungstede.      (White  globules.) 


\Vhyte.^2. 


Fig.  5. 

Spec. :  Machine  Gun  Mechanism. 
Ilium. :    Vertical. 
Camera:  78  cms.     Obj. :  4  mm. 
Ocu. :  Projn.     Mag. :   500  diams. 
Unetched. 
Remarks;    File    mark    in    radius  at 
bottom  of  extractor  stOp. 


Fig.  6. 

Spec. :  Machine  Gun  Mechanism. 
Ilium. :    Vertical. 
Camera. :  61  cms.     Obj. :  2  mm. 
Ocu.:  Projn.    Mag-.:  i,oco  diams, 
Unetched. 
Remarks:    File  mark  in   radius   de- 
flected alongside  slag  patch. 


^' 


■M, 


Fig. 


7. 


Spec. :  Machine  Gun  Mechanism. 

Ilium. :    \^ertical. 

Camera:  Q2.5  cms.    Obj.:  2  mm. 

Ocu.:  Projn.    Mag.:  1,500  diams. 

Etched:   Picric  Acid, 
Remarks:   Strain  in  structure  round 
crack  in   .50%   C.   steel.     Troostitic 
condition. 


Fig.  8. 

Spec. :   B.  Brass. 

Ilium.  :    \'crtical. 

Camera:   55  cms.      Obj.:  4  mm. 

Ocu.  :   Projn.      Mag.  :   250  diams. 

Etched:    .Ammonium  h>'drate. 
Remarks:    Shows   junction   of  three 
crj'stal  grains.     Each  \vith  own  sys- 
tem of  slip  bands. 


Whyte.— 3. 


Fig.  q. 

Spec. :  Nickel  Rolled  Bar. 
Ilium. :    Vertical. 
Camera:  02.5  cms.    Obj.  :  2  mm. 
Ocu. :  Projn.    Mag-.:  1,500  diams. 
Etched:    Nitric  Acid. 

Remarks:     Etching-    pits    in    nickel 
crystals. 


Fig.    10. 

Spec. :   Nickel  Rolled  Bar. 

Ilium.  :    \'ertical. 

Camera:  92.5  cms.     Obj.:  2  mm. 

Ocu. :  Projn.    Mag-. :  1,500  diams. 

Etched:    Nitric  Acid. 
Remarks:   Twinning-  plane  in  nickel 
crystal  with  resulting  difference  in 
orientation. 


SUGGESTED  IMPROVEMENTS   IN  THE    METALLURGICAL 
MICROSCOPE 

By  Professor  H.  Le  Chatelier  (Paris). 


The  writer  has  for  some  considerable  time  been  endeavouring  to 
extend  the  use  of  the  Microscope  in  Metallurgical  Works.  No  one 
to-day  will  contest  the  services  that  Metallography  renders  to  Industry, 
and  it  is  possible  that  the  sphere  of  usefulness  of  this  method  of 
investigation  could  be  still  further  extended  by  improvements  in 
detail. 

The  object  of  this  brief  note  is  to  point  out  two  possible  improve- 
ments. 

In  the  first  case,  to  obtain  good  photomicrographs  the  use  of 
apochromatic  objectives  is  necessary.  These  are  very  costly  and 
many  workers  hesitate  to  incur  the  expense  of  providing  them.  Would 
it  not  be  possible  to  persuade  Manufacturers  to  design  Objectives 
corrected  for  some  single  wave-length  of  the  spectrum  ? — viz.,  the 
blue  line  of  the  Mercury  Vapour  Lamp,  which  is  easily  separated  from 
the  other  rays  and  which  moreover  has  a  considerable  actinic  effect. 
Such  simple  objectives  in  which  it  would  only  be  necessary  to  take 
into  account  corrections  for  spherical  aberration  could  be  manufactured 
as  a  single  lens  and  would  thus  be  comparatively  cheap. 

The  second  improvement,  which  it  is  desirable  to  introduce  into 
an  objective  used  for  the  examination  of  metals  is  to  give  to  the  radius 
of  curvature  of  the  back  surface  such  a  value  as  to  prevent  concentration 
of  the  light  reflected  from  this  surface.  In  all  Metallurgical  Micro- 
scopes illumination  must  necessarily  be  effected  through  the  objective. 
This  is  a  new  condition  and  consequently  one  complication  more  in 
the  construction  of  objectives,  but  perhaps  it  may  not  be  insuperable. 

From  an  entirely  opposite  point  of  view  it  would  be  very  useful 
if  a  small  handbook  were  drawn  up  for  the  use  of  those  who  employ 
the  Microscope,  as  well  as  for  a  few  of  the  Manufacturers,  such  a 
manual  explaining  the  essential  properties  of  the  instrument.  Every 
day  the  grossest  errors  are  made  in  this  connection.  A  great  number 
of  experimenters  imagine  that  a  Microscope  Objective  can  be  used 
like  a  thin  lens.  They  forget  that  every  objective  is  constructed  to 
give  an  image  at  a  fixed  point,  this  being  16  or  25  centimetres  according 
to  the  country  of  manufacture.  We  frequently  see  photographs 
taken  wuth  a  Microscope  objective,  in  whicn  the  adjustment  (tube 
length)  is  changed  so  as  to  project  the  image  a  greater  or  lesser  distance 
according  to  the  magnification  it  is  desired  to  obtain.  Now,  on  the 
contrary,  the  extension  of  the  Microscope  should  always  remain 
invariable  and  a  projection  eye- piece  used  for  taking  the  photomicro- 
graph. The  distance  of  the  two  lenses  of  this  eye-piece  should  be 
adjusted  according  to  the  magnification  desired. 

177 


178  METALLURGICAL    MICROSCOPE 

Another  practice  which  should  be  no  less  condemned  when  using 
the  Metallurgical  Microscope  is  that  of  reflecting  the  luminous  pencil 
at  right  angles  by  means  of  a  total  reflection  prism  placed  in  the  path 
of  the  pencil  of  light,  instead  of  employing  a  silvered  reflecting  mirror. 
The  former  method  completely  changes  the  working  of  an  objective  by 
making  the  pencil  of  rays  pass  through  a  piece  of  glass  many  centi- 
metres thick.  The  objective  is  calculated  for  working  in  air  and  not 
in  glass. 

These  errors  are  not  very  important  when  the  examination  is 
simply  by  the  naked  eye,  because  the  eye  has  an  extraordinarily  high 
degree  of  accommodation.  This,  however,  is  not  the  case  in  photo- 
graphy. Frequently  the  sharpness  of  image  that  ought  to  be  possible 
where  objectives  are  properly  used  is  far  from  being  obtained. 

To  sum  up  :  hitherto  Microscopes  have  only  been  seriously  investi- 
gated for  the  examination  of  transparent  objects  and  it  would  be 
highly  desirable  if  this  study  could  be  resumed  and  extended  with 
a  view  to  the  examination,  by  reflection,  of  polished  opaque  bodies 
like  metals. 


SUGGESTED     ALTERATIONS     IN     THE     DESIGN     OF     THE 
LE  CHATELIER  TYPE    OF  METALLURGICAL  MICROSCOPE, 

By  Professor  F.  Giolitti  {Italy). 

It  is  well  known  that  the  principles  laid  down  by  Le  Chatelier  for 
the  design  of  his  instrument  have  been  applied,  with  different  con- 
structional details,  by  various  Makers  and  it  is  also  recognised  that 
the  design  of  the  Le  Chatelier  Microscope  which  has  found  greatest 
favour  is  that  adopted  by  Pellin  of  Paris  and  Dujardin  of  Diisseldorf. 

I  have  had  long  and  practical  experience  of  this  latter  type  of 
design,  and  I  do  not  think  I  am  wrong  in  stating  that,  even  though 
the  Le  Chatelier  Microscope  offers  the  best  solution  of  problems 
connected  with  the  microscopic  examination  of  metals,  and  is  much 
preferable  to  all  similar  types  of  apparatus  on  the  market,  it  has 
two  disadvantages,  which,  however,  are  quite  easy  to  rectify  by 
means  of  some  simple  modifications  in  constructional  detail. 

The  first  of  these  disadvantages  consists  in  the  fact  that  the  rack 
which  supports  the  stage  is  directly  fixed  "  on  one  side  "  of  the  stage, 
so  that  the  weight  of  the  stage  and  of  the  object  placed  upon  it  tends 
to  produce  a  sagging  of  the  rack. 

This  sagging  effect  becomes  more  and  more  pronounced  as  time 
goes  on,  and  prevents  the  focussing  of  the  whole  of  the  metallic  section 
under  examination.  It  is  intensified,  and  in  a  short  time  may  seriously 
damage  the  instrument  when  it  is  required  to  examine  fairly  heavy 
specimens,  and  this  is  a  case  which  frequently  occurs  in  practice. 

The  second  disadvantage  consists  in  the  absence  of  an  apparatus, 
w^hich,  like  the  revolving  objective  holder  in  the  ordinary  Microscope, 
permits  of  rapidly  and  easily  changing  the  objective.  In  the  Le 
Chatelier  instrument,  in  order  to  change  the  objective,  it  is  necessary 
to  raise  the  stage,  unscrew  the  first  objective,  screw  the  second  objective 
into  the  place  of  the  first,  lower  the  stage,  and  refocus.  This  operation 
is  very  long  and  tedious,  and  it  is  even  more  so  when,  with  a  view  to 
preventing  the  inconvenience  of  allowing  the  various  objectives  to 
remain  uncovered  on  the  work  table,  it  is  necessary  each  time  to  put 
back  into  its  case  the  objective  which  has  been  removed  from  the 
Microscope  and  take  out  of  its  box  and  fix  on  the  instrument  the  new 
one  required.  And,  of  course,  it  is  often  necessary  to  examine  each 
metallic  section  under  various  magnifications,  in  order  to  find  out  with 
accuracy  the  true  significance  of  the  various  structural  elements,  and 
eliminate  errors  in  the  interpretation  of  the  structure. 

For  these  reasons  I  have  studied,  with  the  help  of  Dr.  A.  Filippini 
of  Genoa  (to  whom  I  extend  my  heartiest  thanks  for  his  valuable 
collaboration),  a  type  of  Microscope  which,  while  still  preserving  the 
-extremely  useful  fundamental  principle  of  the  "  vertical  "  observation 
which  makes  the  Le  Chatelier  Microscope  so  practical,  gets  over  the 
disadvantages  to  which  I  have  referred. 

The  new  Instrument  differs  from  similar  apparatus  principally 
by  the  addition  and  different  arrangement  of  a  few  of  the  external 
parts,  which  are  clearly  shown  in  the  illustration.  Fig.  I. 

I  will,  therefore,  only  refer  very  briefly  to  the  features  of  these 
parts,  without  touching  upon  anything  regarding  the  other  components 
of  the  Microscope — such  as  method  of  illumination,  system  of  pro- 
jection, etc. — which  do  not  differ  essentially  (except  for  the  special 

179 


180  METALLURGICAL    MICROSCOPE 

design  rendered  necessary  owing  to  the  new  type  of  construction) 
from  the  corresponding  parts  of  other  similar  apparatus. 

As  is  clearly  shown  in  the  illustration,  in  the  new  instrument  I 
have  endeavoured  to  eliminate  the  first  of  the  two  disadvantages 
mentioned,  by  supporting  the  stage  by  a  bar  fixed  to  it  at  two  opposite 
points.  The  bar  is,  in  its  turn,  supported  by  the  rack,  the  axis  of 
which  coincides  with  the  perpendicular  of  the  stage,  carried  through 
the  centre  of  the  stage  itself.  It  is  evident  that  in  this  way  the  defects 
due  to  the  sagging  of  the  rack  are  eliminated,  provided  care  is  taken 
in  centreing  the  objects  to  be  examined  in  the  middle  of  the  stage. 

In  the  instrument  constructed  by  Messrs.  Reichert  it  is  possible 
to  support  on  the  stage  specimens  weighing  several  kilogrammes, 
without  any  appreciable  deviation  from  the  normal  between  the 
optical  axis  and  the  plane  of  the  polished  surface  resting  on  the  stage. 

Owing  to  the  frequency  of  cases  in  which  in  practice  it  is  necessary 
to  place  very  heavy  objects  on  to  the  stage,  I  have  thought  it  necessary 
to  take  the  weight  of  the  object  off  the  fine  focussing  micrometer 
screw,  by  fixing — as  will  be  seen  in  the  photograph — the  screw  itself 
to  the  slide  which  carries  the  tubes  of  the  visual  and  projecting  eye- 
pieces. The  result  is  that  the  coarse  movements  and  approximate 
focussing  are  effected  by  moving  the  stage,  while  the  comparatively 
delicate  movements  required  for  very  fine  focussing  are  made  by 
manipulating  the  eyepiece  tubes.  It  will  be  recognised,  owing  to  the 
smallness  of  the  movements  necessary  to  bring  the  objects  into  correct 
focus,  that  such  a  modification  does  not  detract  from  the  proper 
illumination  of  the  object. 

I  have  overcome  the  second  disadvantage  mentioned  by  adding 
to  the  microscope  a  proper  revolving  holder  for  4  objectives.  The 
use  of  the  revolving  holder  offers  some  difficulties  in  this  case  ;  both 
owing  to  the  necessity  for  fitting  it  in  such  a  way  as  not  to  hamper 
the  various  functions  of  other  components  of  the  instrument,  and 
with  a  view  to  preventing  any  modification  in  the  characteristic 
dimensions  of  the  objectives  by  deviating  from  those  w^hich  give  the 
best  results  in  the  examination  of  opaque  metallic  specimens  illumin- 
ated by  reflected  light.  The  first  difficulty  has  been  overcome  by 
replacing  obliquely  the  bar  which  supports  the  stage,  in  the  manner 
shown  in  the  photograph.  The  second  difficulty  has  been  eliminated 
by  giving  to  the  revolving  objective  holder  the  special  shape  repre- 
sented in  the  same  illustration. 

The  above  description  refers  to  the  design  of  instrument  for  visual 
observation.  The  complete  apparatus  as  used  for  Photomicrography 
is  showTi  in  Fig.  2. 

In  addition  to  the  advantages  mentioned  above,  the  new  Microscope 
offers  still  another — not  indispensable — of  permitting  the  oblique 
illumination  of  the  specimen  examined  with  the  low  power  objectives. 
The  adjustment  for  oblique  lighting,  which  already  existed  in  the 
Metallurgical  Microscope  designed  by  Martin,  had  to  be  abandoned, 
from  considerations  of  manufacture,  in  that  of  Le  Chatelier,  but  it 
has  been  satisfactorily  applied  in  the]_new  instrument,  thanks  to  the 
special  design  of  its  essential  parts. 

For  the  reasons  already  referred  to,  it  is  unnecessary  for  me  to 
describe  the  new  instrument  in  more  detail.  I  would  only  add  that  in 
practical  application  the  features  of  design  which  I  have  briefly 
outlined  above   have  shown  themselves  to  be  extremely  useful. 


Giolitti.— 1. 


Fig.  I, 


Fig.  2. 


IMPROVEMENTS    IN    METALLURGICAL    MICROSCOPES. 

By    Albert   Sauveur    (Harvard   University). 


At  the  kind  request  of  Sir  Robert  Hadfield,  I  am  submitting 
this  slight  contribution  to  the  symposium  on  the  microscope  and  its 
applications.  Referring  first  to  the  minor  improvements  I  have  been 
able  to  introduce  into  the  construction  of  metallurgical  microscopes, 
I  venture  to  mention  the  following  points. 

It  is,  I  believe,  at  my  suggestion  that  microscopes  for  metallur- 
gical work  were  first  constructed  by  the  Bausch  and  Lomb  Optical 
Company,  of  Rochester,  New  York,  with  a  stage  that  could  be 
racked  up  and  down  in  a  manner  similar  to  the  substage  attachment, 
thus  affording  greater  working  distance,  and  doing  away  with  the 
necessity  of  ever  having  to  displace  the  vertical  illuminator,  the 
condensing  train  and  the  source  of  light  as  objectives  of  varying 
focal  lengths  are  used.  It  is  also  at  my  suggestion  that  in  inverted 
microscopes  and  in  the  vertical-horizontal  type  herewith  illustrated 
a  totally  reflecting  prism  was  attached  to  a  horizontal  draw  tube, 
affording  a  ready  means  of  pushing  it  in  or  drawing  out  of  position 
as  desired. 

The  two  types  of  metallurgical  microscopes  used  almost  exclu- 
sively in  the  United  States  are  shown  in  Figs.  1  and  2,  special 
attention  being  called  to  what  may  be  called  the  horizontal-vertical 
type  (Fig.  1),  in  which  a  vertical  microscope  is  used  for  visual 
work,  while  a  permanently  connected  horizontal  camera  is  used 
for  photographic  work.  It  is  believed  that  this  arrangement  presents 
some  decided  advantages  over  the  vertical  type  as  well  as  over  the 
inverted  type.  I  do  not  believe  that  these  instruments  have  ever 
been  surpassed  by  those  of  German  manufacture. 

The  magnetic  holder  which  I  designed  many  years  ago  for 
holding  iron  and  steel  specimens  has  proved,  I  believe,  very  service- 
able, and  is  widely  used  in  the  United  States. 

As  to  the  directions  in  which  metallographic  investigation  should 
be  stimulated  as  more  likely  to  bring  valuable  results,  I  am  not 
one  of  those  who  believe  that  much  is  to  be  expected  from  examina- 
tion at  greatly  increased  magnifications.  Confining  my  remarks 
to  iron  and  steel,  with  the  exception  of  the  occurrence  of  carbon,  we 
are  still  greatly  handicapped  by  the  lack  of  methods  by  which  other 
constituents  and  impurities  can  be  identified  and  their  occurrence 
studied,  and  it  seems  to  me  that  we  should  endeavour  to  remedy 
this  condition.  Let  us  briefly  consider  the  various  elements  or 
chemical  compounds  present  in  industrial  iron-carbon  alloys. 

Carbon. — We  have  at  our  command  satisfactory  means  of  distin- 
guishing under  the  microscope  the  various  forms  in  which  carbon 
occurs  in  these  alloys.  I  am  not  of  the  opinion  that  carbon  may  be 
present,  as  some  believe,  in  a  much  greater  number  of  varieties 
than  we  are  now  able  to  identify,  and  I  do  not  believe  that  examina- 
tion under  greatly  increased  magnification  or  other  methods  would 
advance  much  further  our  knowledge  of  the  behaviour  of  that  vital 

]81 


182  METALLURGICAL    MICROSCOPE 

element.  Carbon  is  present  in  iron-carbon  alloys  either  as  graphite, 
or  as  the  carbide  FesC,  which  may  be  free  or  which  may  form  with 
iron  a  solid  solution.  I  am  not  attempting  at  present  to  distinguish 
between  solid  solutions  and  colloidal  solutions  or  emulsions.  I 
believe  that  the  hardening  of  steel  is  due  to  the  retention  of  the 
carbide  FcaC  in  a  solid  solution,  but  I  also  believe  that  the  solution 
thus  retained  by  rapid  cooling  is  allotropically  different  from  the 
solid  solution  stable  above  the  thermal  critical  stage. 

Phosphorus. — It  is  believed  on  good  grounds  that  phosphorus 
exists  as  FeaP  in  iron,  but  unless  there  is  a  considerable  percentage 
of  carbon  present  one  cannot  under  the  microscope  detect  the  presence 
of  that  compound,  owing  to  the  fact  that  it  forms  with  ferrite  a 
solid  solution.  A  method^by  which  steel  high  in  phosphorus  could 
be  differentiated  under  iWe  microscope  from  one  low  in  phosphorus 
would  be  of  great  service.  To  be  sure,  it  is  believed  that  segrega- 
tion of  phosphorus  may  be  detected  by  the  Stead's  reagent  or  by 
similar  reagents,  but  in  the  light  of  recent  research  we  are  in  doubt 
ivhether  the  segregation  which  we  have  been  in  the  habit 
of  attributing  to  the  occurrence  of  phosphorus  may  not  be 
due  in  some  cases  to  the  presence  of  some  other  element  or  elements  •, 
for  instance,  to  the  presence  of  oxygen.  Obviously  better  means  of 
identification  are  needed. 

Sulphur. — We  have  satisfactory  ground  for  our  belief  that 
sulphur  in  steel  unites  with  some  of  the  manganese  present  to  form 
particles  of  manganese  sulphide  distributed  somewhat  irregularly 
in  the  metal,  and  that  it  may  also  form  a  sulphide  of  iron.  These 
can  be  detected  quite  readily  under  the  microscope.  It  is  not 
certain,  however,  that  the  dove-coloured  inclusions  generally  assumed 
to  be  manganese  sulphide  contain  no  other  constituents,  nor  do 
we  know  positively  that  sulphur  forms  no  other  compound  and  that 
it  is  not  present  in  any  of  the  other  constituents  detectable  under 
the  microscope. 

Manganese. — We  believe  that  some  of  the  manganese  present 
in  steel  forms,  as  stated  above,  manganese  sulphide,  as  well  as 
manganese  carbide,  and  also  that  some  of  it  is  present  in  solild 
solution  in  iron,  but  with  the  exception  of  manganese  sulphide  it 
is  not  possible  to  detect  the  presence  of  manganese  in  any  of  its 
other  forms  under  the  microscope. 

Silicon. — Silicon  is  generally  supposed  to  be  present  as  an  iron 
silicide  dissolved  in  iron.  It  is  not  possible,  however,  to  verify  by 
the  microscope  the  accuracy  of  this  belief. 

Special  Elements. — Microscopical  evidences  of  the  form  in  which 
special  elements,  such  as  nickel,  chromium,  tungsten,  vanadium, 
etc.,  occur  in  steel  are  lacking. 

I  believe  that  the  discovery  of  etching  or  other  methods  that 
would  permit  a  more  thorough  and  more  exact  microscopical  analysis 
of  iron  and  steel  and  of  their  inclusions  would  be  of  great  assistance 
in  the  further  development  of  metallography. 


Sauveur.— 1. 


Fig.  I. 


Fig.  2. 


SOME  POINTS  CONCERNING  SHARPNESS  IN 

HIGH  MAGNIFICATION  MICROGRAPHS. 

By  Carl  Benedicks  and  Erik  Walldow  (University  of   Stockholm) 

1.  Microscope  and  accessoi'ies  used. 

The  following  will  give  a  short  account  of  some  optical  studies 
executed  by  us,  using  the  new-constructed  metallographical  micro- 
scope of  C.  Reichert  of  Vienna. 

The  most  prominent  feature  of  the  new  microscope,  which  is 
constructed  according  to  the  Le  Chatelier  type,  is  the  very  con- 
venient interchangeability  of  the  plain  glass  illuminator  and  the 
prism  illuminator.  This  interchangeability  was  introduced  in  con- 
sequence of  a  short  paper  by  one  of  us,*  in  which  evidence  was  given 
of  the  superiority  of  the  former  illuminator  at  high  magnifications. 
Another  innovation  is  the  very  convenient  adjustment,  with  index 
and  scale,  of  the  position  of  the  prism — which  is  of  the  Le  Chatelier 
type,  v/ith  two  reflecting  surfaces — so  as  to  enter  more  or  less, 
according  to  the  focal  length  of  the  objective. 

Another  detail  of  the  construction  is,  that  the  coarse  adjustment 
is  operated  by  a  rack  and  pinion  motion  of  the  stage  on  which  the 
specimen  rests  (face  downwards),  whilst  the  fine  focussing  is  obtained 
by  a  micrometer  slide  motion  of  the  objective  and  tubes.  The 
advantage  is,  that  a  heavy  weight  on  the  stage  will  have  no  influ- 
ence on  the  delicate  slide  motion. 

For  photographic  work,  a  green  glass  filter  was  used,  giving  a 
rather  well-defined  wave  length  of  0.5-0.6  fj-.  Orthochromatic 
plates  (Wellington,  anti-screen,  backed)  were  used,  and  an  arc  lamp 
of  about  350  c.p.,  the  duration  of  exposure  was  increased  by  this 
filter  in  the  ratio  10:1.  The  regular  exposure  (with  filter)  was 
20  sees,  when  the  glass  slide  illuminator,  4  sees,  when  the  prism 
illuminator,  was  used. 

The  test  specimen  was  a  lamellar  pearlite  of  0.90  per  cent,  carbon 
content,  polished  in  bas-relief  on  parchment. 

2.  Arc  lamp  and  incandescent  lamp. 

Fig.  1  gives  the  specimen  at  a  magnification  of  1,200  (arc  lamp; 
immersion  apochromatic  f  =  2  mm..  Num.  aperture  1,30;  projection 
eye-piece  Nr.  2;  camera  length  65  cm.). 

In  Fig,  2  a''  Half- Watt  "  incandescent  lamp  of  60  c.p.  was 
used;  of  course,  several  advantages  are  obtained  by  a  less  intense 
source  of  light.  The  exposure  had  to  be  prolonged  36  times,  to 
12  min. 

The  optical  quality  of  Fig.  2  is  still  good,  but  the  definition  is 
impaired  by  a  general  want  of  sharpness  due  to  vibration  during 
the  long  exposure. 

It  must  be  pointed  out,  however,  that  under  quieter  conditions 
photographs  were  obtained  with  the  incandescent  lamp  of  the  very 
highest  sharpness,  which  in  no  respect  differed  from  Fig.  1.  This 
proves  that  the  candle  poiver  of  the  lamp  has  no  influence  on  the 
image  quaVity — a  point  which,  though  very  natural,  scarcely  has 
been  proved  so  far  as  yet. 

'^  C.  Benedicks,  Metalhirgie,  Vol.  6,  p.  320,  iqoq. — Dr.  W.  Rosenhain 
made  some  remjarks  in  the  same  direction  in  /.  Iron  and  Steel  hist., 
1Q06,  II,  p.   180  {see  Metallurgies  Vol.  8,  p.   136,  1911). 

183 


184       SOME  POINTS   CONCERNING   SHARPNESS   IN 

The  mirror  reflecting  arrangement  provided  with  the  camera 
proved  to  be  of  value,  especially  at  long  exposures,  as  it  provides 
the  possibility  of  a  control  of  the  proper  focussing  during  a  long 
exposure,  without  having  any  disturbing  effect. 

3.  Influence  of  vibrations  and  its  avoidance. 

Even  at  short  exposures  with  the  arc  lamp  the  sensitiveness 
for  vibrations  is  very  undesirable.  The  whole  instrument  being  very 
rigidly  constructed,  the  cause  of  this  sensitiveness  was  by  no  means 
obvious.  After  a  detailed  examination,  it  was  found  that  the 
comparatively  great  mass  of  the  tube-carrying  upright,  with  the 
two  tubes  (ocular  and  photographic),  illuminator  and  objective,  was 
responsible  for  the  vibration  sensitiveness.  The  remedy  was  possible 
to  indicate :  the  objective  is  to  be  mounted  by  itself,  on  a  special 
upright  with  little  mass,  and  must  have  no  direct  connection  with 
the  tubes;  if  this  be  the  case,  then  the  inevitable  vibrations  of  the 
tubes  will  be  of  no  direct  influence  on  the  distance  between,  objective 
and  specimen — which  is  the  most  sensitive  point  as  regards  sharp- 
ness. A  slight  disadvantage  introduced  by  this  modification  is  that 
the  distance  between  the  illuminator  and  the  objective  will  be  sub- 
jected to  small  changes;  these,  however,  seem  to  be  of  little  con- 
sequence in  comparison  with  the  considerable  increase  in  insensi- 
bility to  vibrations  which  probably  will  result.  Of  course,  even  in 
works  laboratories  it  is  important  to  be  able  to  produce  good  high 
magnification  photographs  without  too  much  trouble. 

In  this  connection  the  following  may  be  added. 

If  the  ground  of  the  laboratory  is  not  sufficiently  free  from 
disturbance  it  is  necessary  to  mount  the  apparatus  on  some  vibra- 
tion-damping device.  Now,  it  has  been  found  from  investigations 
executed  in  this  laboratory  by  I.  Malmborg*  that  the  simplest  thing 
is  to  mount  the  instrument  on  a  solid  plate,  resting  on  a  thick 
layer  of  felt;  this,  however,  must  not,  as  is  ordinarily  the  case,  be 
used  in  a  dry  condition,  but  moistened  with  a  viscous  liquid,  such 
as  vaseline.  The  energy  of  the  disturbances  is  then  absorbed 
through  the  forced  motion  of  the  liquid  in  the  interstices  of  the 
felt.     This  method  has  been  used  with  great  advantage.! 

4.  Disposition  of  diaphragms. 

In  the  metallographic  microscope  the  cutting  off  of  side-rays  by 
diaphragms  is  well  known  for  several  reasons  to  be  of  great  impor- 
tance. As  a  general  principle  it  can  be  said  that  the  beam  of 
light  is  to  be  reduced  as  much  as  possible  without  interfering  with 
the  intensity  and  uniform  distribution  of  the  light,  or  with  the 
necessary  extension  of  the  image. 

Fig.  3  gives  diagrammatically  the  illuminating  arrangement.  In 
order  to  work  properly,  the  image  of  the  source  of  light — as  which 
the  opening  of  the  diaphragm  B  is  to  be  considered — must  fall  on, 
or  at  least  near,  the  illuminator  P,  and  the  image  of  the  iris 
diaphragm  I  must  fall  on  the  surface  of  the  specimen  T.  The 
first  item,  brought  about  by  the  lenses  L  and  F,  is  necessary  in 
order  to  be  able  to  use  the  whole  of  the  light  power  available,  and 

♦  Ann.  d.  Physik  {4),  Vol.  44,  p.   337,  1914. 
tBenedicks,  /.  Iron  and  Steel  Inst.    1Q14.   I,    p    407  (424). 


I 


HIGH  MAGNIFICATION  MICROGRAPHS  185 

to  obtain  a  syst(6inatic  centering  of  the  light;  the  second  item, 
effected  by  lens  F  and  objective  O,  is  necessary  in  order  to  limit 
properly  the  image  on  the  plate,  and  to  cut  off  false  light  so  far 
as  possible. 

There  is,  in  our  view,  no  reason  why  the  parts  of  this  optical 
system  should  be  differently  arranged  (sliding  of  L)  when  using  a 
plain  glass  reflector  or  a  prism  reflector;  nevertheless,  on  the  micro- 
scope examined,  as  well  as  on  other  Continental  microscopes,  such 
a  difference  has  been  introduced  intentionally.  As  a  matter  of  fact, 
it  was  found  quite  practicable  to  obtain  correct  results,  so  far  as 
the  illumination  is  concerned,  with  both  kind  of  reflectors,  without 
any  variation,  in  the  position  of  L  (lens  F  had  to  be  changed). 

T 
0 


P 


Fig.  3. 


5.   Comparison  between  Le  Chatelier  prism  and  45°  prism. 

The  Le  Chatelier  prism  being  so  constructed  that  the  lens  F  is 
formed  in  the  same  piece  of  glass  as  the  reflecting  surface  P — 
which,  in  fact,  is  made  up  of  two  planes  giving  successive  reflection 
— it  was  to  be  expected  that  it  would  produce  sensibly  better  con- 
trasts than  a  45°  prism  with  separate  lens  F,  as  in  this  case  more 
reflections  must  occur. 

A  careful  comparison  was  carried  out.  The  result  was  that  it 
was  not  possible  for  us  to  trace  any  difference  in  the  working  of 
the  two  kinds  of  prisms:  the  45°  prism  is  practically,  so  far  as 
contrasts  are  concerned,  not  at  all  inferior  to  the  Le  Chatelier  prism. 

All  comparative  experiments  were  so  made,  by  a  special  projec- 
tion arrangement,  that  both  prisms  (or  metal  mirror)  were  exactly 
in  the  same  position,  covering  the  half  of  the  back  lens  of  the 
objective. 

It  was  found  that  for  lower  magnifications  than  with  the  apo- 
chromatic  f  =  2  mm.,  the  Le  Chatelier  prism  has  a  decided  advan- 
tage over  the  45°  prism  in  so  far  as  it  is  not  necessary,  for  obtaining 
a  uniform  illumination,  to  cover  so  much  as  half  of  the  light  area 
with  the  Le  Chatelier  prism  as  with  the  45°  prism.  Thus  at  lower 
magnifications  the  aperture  is  better  utilised  with  the  Le  Chatelier 
prism.  The  arrangement  mentioned  above  serves  the  purpose  of 
easily  obtaining  for  each  objective  the  proper  position  of  the  prism. 

6.   Influence  of  the  aperture. 

As  already  remarked,  it  has  been  pointed  out  by  Dr.  Rosenhain 
and  by  one  of  the  present  authors  that  the  definition  of  the  image 
at  high  magnification  is  considerably  lessened  when  half  of  the 
aperture  of   the   objective   is   covered  by    a  prism   or   by   an   opaque 


186       SOME  POINTS   CONCERNING   SHARPNESS   IN 

mirror,  the  resolving  power  being  reduced  to  one-half  in  the  direc- 
tion, at  right  angles  to  the  mirror  edge.^ 

This  fact  is  amply  borne  out  by  our  new  comparative  experi- 
ments. Thus,  Fig.  4  shows  the  very  best  definition  to  be  obtained 
with  a  prism  illuminator.  A  comparison  with  Fig.  1,  which  was 
obtained  with  the  plain  glass  illuminator,  gives  evidence  of  the  much 
higher  quality  of  the  image  obtained  in  the  latter  case,  thus  laying 
stress  on  the  fundamental  condition  for  obtaining  sharp  high  mag- 
nification micrographs:  the  full  utilisation  of  the  aperture  of  the 
objective. 

7.  CoiniKir'iaon    heiween    prism    and   metal    mirror. 

It  is  obvious  that  with  reflecting  glass  prisms — as  well  the  Le 
Chatelier  as  the  45°  prism — inner  reflections  cannot  be  entirely  got 
rid  of.  On  the  other  hand,  with  a  metal  mirror,  such  undesirable 
reflections  do  not  occur,  and  it  is  to  be  expected  that  the  contrasts 
will  improve. 

As  the  result  of  some  direct  comparisons,  it  was  actually  found 
that  an  indisputable,  though  slight,  increase  of  the  contrasts  was 
to  be  seen  on  the  micrographs  obtained  with  the  metal  mirror.  Thus, 
a  metal  mirror  illuminator  may  be  of  some  use  whenever  particularly 
strong  contrasts  are  desired. 

8.  Influence  of  the  thickness  of  the  jilain  glass. 

The  glass  slide  provided  with  the  microscope  used  was  0.45  mm. 
thick.  It  may  be  questioned  whether  this  thickness,  on  account 
of  the  astigmatism  introduced,  is  not  too  high.  On  using  a  very 
thin  glass,  0.10  mm.,  as  a  matter  of  fact,  a  slight  improvement  of 
the  sharpness  occurred;  this,  however,  was  so  insignificant  that 
practically  the  use  of  the  thicker  glass  must  be  considered  to  be 
quite  justified. 

If  one  is  at  liberty  to  choose,  a  thinner  glass,  of  course,  should 
be  preferred  to  a  thicker. 

9.  Astigmatism  introduced  hy  the  right  angle  reflecting  prism. 

It  seems  by  no  means  excluded,  that  sensible  astigmatism  could 
not  be  introduced  by  the  right  angle  prism  used  in  the  Le  Chatelier 
microscope  in  order  to  reflect  horizontally  the  vertical  beam  of  light 
issuing  from  the  specimen.  However,  the  excellent  definition 
obtained,  as  in  Fig.  1,  shows  that  this  undesirable  influence  of  the 
prism  can  be  entirely  neglected.  Of  course,  it  is  essential  that 
the  prism  be  of  a  very  high  optical  finish,  and  carefully  adjusted. 

10.  Platinised  plain  glass  illuminator. 

As  ])ointed  out  on  an  earlier  occasion, f  it  might  be  possible  to 
increase  the  light  intensity  obtained  with  the  plain  glass  illuminator 
by  using  a  thin  silver  or  platinum  coating.  Obviously,  the  thick- 
ness of  the  metal  layer  must  not  exceed  a  definite  value;  otherwise 
a  decrease  of  intensity  will  result. 


*  See   for    instance    Dr.    Ro'Sienhain's   An    Introduction    to    the   Study 
of  Physical  Metallur^yj  London,  1Q14,  p.   52. 
t  C.  Benedicks.  I.e. 


Benedicks  &  Walldow.-l. 


Fig.  1. 
Plain  glass  illuminator,  Arc  lamp  ;  20  sees,   x   1200 


Fig.  2. 
Plain  glass  illuminator,  "  Half- Watt  lamp"  ;   12  mins.    x    1200. 


Benedicks  &  Walldow.     2. 


Fig.  4. 
Le  Chatelier  prism  illuminator.  Arc  lamp  ;  4  sees,    x    1200 


Fig.  5. 
Plain  glass   platinised,  Arc  lamp  ;   20  sees,   x   1200 


HIGH  MAGNIFICATION  MICROGRAPHS  187 

Fig.  6  reproduces  a  micrograph  obtained  with  a  platinum  layer 
of  a  definite  thickness,  scarcely  providing  any  appreciable  increase 
in  light  intensity;  exposure  20  sees.,  as  in  the  other  cases.  A 
somewhat  thinner  coating  might  have  been  desirable. 

It  is  of  interest  to  note,  however,  that  the  micrographs  obtained 
in  this  way  were  characterised  by  an  unusually  large  extension  of 
the  sharp  image.  The  contrasts  seem  to  be  somewhat  weaker  than 
those  obtained  with  the  other  illuminators,  and  possibly  this  is  the 
reason  why  on  Fig.  5  (in  original)  are  to  be  seen  details,  e.ff.,  some 
characteristic  irregularities  in  the  ferrite  ground  mass,  which  scarcely 
are  to  be  seen  on  any  other  of  the  micrographs  taken. 

Thus  it  was  found  from  these  experiments  that  any  essential 
gain  in  light  intensity  is  difficult  to  obtain  by  platinum  coating, 
but  on  the  other  hand  a  more  detailed  investigation  is  required  to 
find  out  whether  the  filtering  of  the  light  on  passing  through  the 
thin  metal  coating  might  possibly  be  of  some  advantage  when  it 
is  a  question  of  bringing  out  a  maximum  of  detail. 

11.   Further  remarks. 

It  has  to  be  added  that  every  exposure  w^as  repeated  several 
times,  and  found  consistent  with  similar  experiments,  so  that,  not- 
withstanding the  obvious  difficulty  of  avoiding  focussing  errors,  the 
results  obtained  appear  to  be  quite  reliable. 

A  detailed  account  of  these  investigations  has  been  published  in 
Swedish  in  Biharig  till  Jernkontorets  Annaler,  Vol.  19,  p.  537,  1918. 

A  detailed  account  will  also  probably  appear  in  Zeitscfirift  fur 
Wissenschaftlich e  Mikroskopie . 


Summary. 

The  investigations  were  started  as  a  detailed  and  critical  ex- 
amination of  the  new  Reichert  microscope,  which  is  of  the  Le  Cha- 
telier  type.  It  was  found  to  produce  excellent  results  at  the  very 
highest  magnifications. 

Then  some  points  of  a  more  general  character  were  examined, 
as: 

(1)  The  using  of  an  arc  lamp  (350  c.p.)  or  of  an  incandescent 
lamp  (50  c.p.)  gave  exactly  the  same  result. 

(2)  A  modification  of  the  microscope  is  proposed  in  order  to 
diminish  its  vibration  sensitivity. 

(3)  The  proper  arrangement  of  the  diaphragms  is  discussed. 

(4)  A  Le  Chatelier  prism  and  a  45°  prism  give  at  high  magnifi- 
cation exactly  the  same  result. 

(5)  A  metal  mirror  gives  slightly  better  contrasts  than  a  prism. 

(6)  In  the  plain  glass  illuminator  a  thickness  of  0.45  mm.  does 
not  injure  sensibly  the  image  quality. 

(7)  A  slightly  platinised  glass  illuminator  gave  somewhat  finer 
details  than  any  other  illuminator  used;  this  question,  however, 
needs  further  research. 


AN   ORDINARY   MICROSCOPE   ADAPTED   TO 
METALLOGRAPHY. 

By  F.   Ian  G.   Rawlins,  F.R.M.S. 


The  purpose  of  the  following  brief  note  is  to  draw  attention  to 
certain  details  of  a  more  or  less  minor  nature,  which,  when  incor- 
porated into  an  ordinary  microscope  stand,  render  it  decidedly 
efficient  for  metallographical  work,  where  an  elaborate  outfit  is  not 
desired.  Although  post-war  models  are  now  appearing  by  the  leading 
makers  for  this  branch  of  microscopy,  there  is  a  decided  advantage 
in  being  able  to  use  an  ordinary  stand,  and  the  expense  involved 
in  the  modifications  is  very  moderate.  Lastly,  the  additions  are 
such  that  they  can  be  easily  carried  out,  even  in  the  present  abnormal 
state  of  the  trade;  and  they  are  no  detriment  to  work  on  trans- 
parent objects. 


n 


Fig.   I. 

Vertical     and    Horizontal     Sections 
of    Plug. 

(1)  Siihstage  Fitting. 

The  point  of  this  is  to  overcome  the  trouble  inherent  in  the  use 
of  ordiiiary  stands  for  opaque  objects  with  the  vertical  illuminator, 
/.r.,  that  on  re-focussing,  the  centering  of  the  illuminator  and  light- 
source  is  disturbed.  Assuming  that  the  stand  possesses  no  substage 
appaiat  IS  (a])art  from  the  mirror),  a  focussing  substage  is  fitted, 
provided  with  coarse  adjustment,  rack  and  pinion.  Instead  of  the 
usual   condenser,    a   solid     brass     plug     (circular,    and    of   the   shape 

188 


F.    IAN    G.    RAWLINS  189 

sketched  in  vertical  section,)  is  inserted  into  the  ring.  The  top  is 
provided  with  a  slightly  bevelled  edge,  into  which  fits  a  glass  slip  on 
which  the  plasticine  holding  the  specimen  is  placed  as  usual.  This 
can  then  be  focussed  upwards  and  downwards,  avoiding  any  move- 
ment of  the  body-tube.  To  substitute  another  specimen,  all  that 
is  needed  is  to  rack  down,  swing  the  fitting  out  of  the  optic  axis, 
take  out  the  plug,  insert  another  levelled  specimen  as  already 
described,  re-insert  the  plug,  and  focus  as  before.  Of  course,  if 
only  objectives  are  being  changed,  the  focus  can  be  re-set  at  once. 
An  adapter  fitted  to  the  body-tube  may  be  wanted  if  the  rackwork 
on  the  stand  is  limited.  The  central  aperture  in  the  stage  is 
generally  too  small,  and  should  be  enlarged  for  these  additions. 
In  the  event  of  transparent  work  with  condenser,  polariser,  etc., 
being  contemplated,  the  focussing  substage  is  ready  at  hand,  the 
appropriate  fitting  being  substituted  for  the  afore-mentioned  plug. 

(2)  Objectives. 

Mounting  in  short  barrels  is  very  desirable  for  use  with  the 
vertical  illuminator.  There  is  often  considerable  difficulty  in  obtain- 
ing objectives  so  arranged  from  the  makers.  The  following  alteration, 
easily  carried    out,    may    assist.      The    lower    part    of  the    barrel    is 


a 


Fig.  2. 


Carrier   and   Unscrewed    Part  of 
Objective. 

unscrewed,  and  then  inserted  into  a  carrier  bodily,  which  latter  is 
provided  with  a  standard  thread,  attaching  to  the  vertical  illuminator, 
and  bringing  the  back  lens  of  the  objective  very  close  to  the  reflector. 
Two  lenses  so  treated,  a  ^  inch  and  a  ^  inch,  in  the  writer's 
possession    give  excellent  results  in  practice. 

(3)  Illumination. 

A  type  of  "  Half- Watt  "  lamp  made  in  Holland  has  been  found 
admirable.  The  200  candle-power  size  is  amply  sufficient.  By  noting 
that  the  ring-filament  in  these  lamps  gives  a  very  solid  and  concen- 
trated area  of  light,  and  using  a  bull's-eye  condenser  of  small  aperture, 
it  is  possible  to  get  effects  closely  resembling  a  "  point-source  " 
of  light.  The  very  moderate  cost  of  these  lamps  compared  with, 
say,  a  "  Pointolite,"  is  greatly  in  their  favour,  and  they  are  quite 
powerful  enough  for  magnifications  up  to  600  diameters  in  metallo- 
graphy. 

In  conclusion,  apart  from  general  ideas,  the  author  disclaims 
any  question  of  having  originated  the  above  improvements.  His 
thanks  are  due  to  Messrs.  H.  F.  Angus  and  Co.  for  their  skilled 
assistance. 


THE   MICROSCOPE   IN   METALLURGICAL   RESEARCH. 
By  E.  F.  Law. 

It  would  be  difficult  to  over-estimate  the  importance  of  the 
part  played  by  the  microscope  in  metallurgical  research  during  the 
last  15  years.  Its  introduction  threw  a  flood  of  light  on  problems 
hitherto  unsolved,  and  it  was  not  surprising  that  the  early  work 
of  the  pioneers — Sorby,  Osmond,  Roberts- Austen  and  others — was 
followed  by  a  rush  of  eager  recruits  anxious  to  take  part  in  the 
campaign.  Nor  was  it  surprising  that  this  display  of  zeal  should 
be  followed  by  a  lull,  if  not  an  actual  reaction;  such  periods  in- 
variably follow  a  period  of  exceptionally  rapid  progress,  and  when 
they  occur  it  is  wise  to  take  stock  of  the  existing  position  and 
endeavour  to  prepare  the  way  for  the  next  advance.  With  that 
object  in  view  we  may  briefly  consider  the  metallurgical  problems 
which  have  already  been  solved  by  means  of  the  microscope,  and 
then  turn  to  some  of  those  which  are  awaiting  solution  and  which 
require  either  more  knowledge  or  more  perfect  instruments. 

Frohlems  Solved. — Before  the  introduction  of  the  microscope  we 
knew  from  the  chemical  analysis  of  an  alloy  its  ultimate  chemical 
components,  but  we  did  not  know  in  what  form  those  components 
occurred.  Probably  the  only  exception  to  this  rule  was  to  be  found 
in  the  case  of  carbon  in  cast  iron,  which  was  invariably  divided  into 
free  or  graphitic  carbon  and  combined  carbon.  The  microscope 
altered  all  this,  and  explained  not  only  the  relationship  between 
the  structure  of  the  alloy  and  its  mechanical  properties,  but  the 
structural  alterations  and  consequent  changes  in  mechanical  proper- 
ties produced  by  heat  treatment. 

Problems  to  he  Solved. — With  very  few  exceptions,  it  may  be 
«aid  that  the  finer  or  smaller  the  structure  of  an  alloy,  the  more 
useful  it  is  from  a  commercial  standpoint ;  and  it  frequently  happens 
that  the  best  of  our  commercial  steels  possess  so  fine  a  structure 
that  they  are  imperfectly  resolved  by  the  highest  powers  of  the 
microscope  now  available.  How  often  do  we  read  in  descriptions 
of  microstructures  such  expressions  as  "a  confused  groundmass  *' 
or  "a  matrix  whose  structure  is  not  resolved  by  the  microscope  "  ? 
Another  problem  awaiting  solution  is  to  be  found  in  the  inter- 
crystalline  weakness  of  metal.  During  the  last  few  years  a  wonderful 
edifice  of  hypotheses  has  been  erected  on  the  foundation  of  a  so- 
called  amorphous  phase  which  is  said  to  exist  between  the  crystals 
of  a  metal,  and  this  amorphous  material  is  made  to  serve  as  an 
explanation  either  of  its  strength  or  weakness. 

Unfortunately,  there  is  very  little  direct  evidence  in  support  of 
these  theories ;  but  with  a  higher  degree  of  magnification  it  is  possible 
we  may  learn  more  of  the  intercrystalline  structure  of  metals.  Even 
of  the  crystalline  structure  we  know  very  little,  and  there  is  scope 
for  much  research  on  the  "  dendritic  "  structure  which  is  shown 
on  heat-tinting,  and  which  has  been  so  beautifully  developed  by 
Humfrey. 

For  these  and  other  investigations  we  require  instruments  which 
will  give  us  a  higher  degree  of  magnification,  and  we  look  to  the 
manufacturers  for  their  assistance.  But,  if  we  are  provided  with 
such  instruments,  we,  on  our  part,  must  be  prepared  to  supply  a 
much  higher  degree  of  skill  in  the  preparation  of  samples  for  exam- 
ination than  is  commonly  met  -with. 

190 


DEVELOPMENT  OF  THE  METALLURGICAL  MICROSCOPE 
AND  ITS  SUGGESTED  APPLICATION  TO  SOME  UN- 
SOLVED PROBLEMS. 

By  Herman   A.    Holz,    New   York. 

Every  step  forward  in  the  development  of  apparatus  for  metal- 
lurgical research  work  is  followed  by  an  increase  of  our  knowledge 
of  the  particular  field  of  metallurgy  for  which  the  instrument  serves. 
In  other  words,  suitable  apparatus  have  to  be  developed  to  a  high 
stage  of  perfection  before  we  can  make  accurate  and  reliable  deter- 
minations which  enable  us  to  gain  valuable  knowledge  of  certain 
facts  which  were  unknovt^n  to  us  before  or  about  which  we  were  not 
quite  certain. 

The  development  of  the  thermo-electric  pyrometer  by  Le  Cha- 
telier  enabled  us  to  find  the  transformation  regions  in  steel,  Sir 
William  Roberts-Austen's  apparatus — making  us©  of  thermo-elec- 
tric forces — permitted  us  to  determine  these  transformation  regions 
with  great  accuracy  and  in  a  convenient  manner,  resulting  in 
systematic  research  work  which  forms  the  basis  of  the  art  of  heat- 
treating  steel. 

The  most  important  apparatus  which  enable  the  metallographist 
to  find  the  way  towards  improvements  in  the  structural  details  of 
steel  and  to  control  the  correct  thermal  treatment  to  which  he 
subjects  the  material,  are  the  microscope  and  the  permeameter. 
The  microstructure  of  steel  can  be  observed  and  photographed  by 
means  of  the  microscope,  while  it  can  be  measured  and  expressed 
in  definite  figures  by  means  of  the  permeameter,  thus  permitting 
quantitative  determinations.  The  success  gained  in  recent  years  in 
obtaining  higher  efficiency  from  definite  alloys,  especially  alloy 
steels,  and  in  developing  steels  and  bronzes  ot  greater  strength,  has 
been  due  to  systematic  metallographic,  especially  microscopic, 
research  work. 

As  the  methods  of  microscopic  investigation  have  been  improved 
by  the  development  of  more  efficient  etching  processes,  so  have  the 
design  and  construction  of  metallurgical  microscopes  been  gradually 
developed  to  a  high  stage,  in  regard  to  the  quality  of  lenses,  source 
of  light,  vertical  illuminators,  etc.,  as  well  as  to  rigidity  an.1 
usefulness  of  mechanical  arrangements.  While  the  pioneer  work 
on  the  microstructure  of  metals  was  carried  on  by  means  of  ordinary 
(bacteriological)  microscope  stands,  it  was  soon  found  that  the 
investigation  of  opaque  substances,  without  using  cover  glasses  over 
the  object,  necessitated  changes  in  the  illuminating  system  and  in 
the  grinding  and  mounting  of  the  objectives.  The  vertical  illumin- 
ators now  largely  used  for  this  purpose  were  developed  in  England 
(45  degree  plane  glass  reflector  by  Beck)  and  France  (prism 
reflector  by  Le  Chatelier,  first  made  by  Pellin  and  Nachet).  The 
objectives  used  in  connection  with  these  illuminators  have  to  be 
mounted  as  short  as  possible;  the  nearer  the  reflecting  surface  stands 

191 


192         DEVELOPMENT    OF    THE   METALLURGICAL 

to  the  objective,  the  more  even  is  the  illumination  obtained.  In 
the  method  of  plane  glass  reflection,  the  rays  of  illumination  and 
of  the  image  penetrate  the  entire  objective  simultaneously;  the  final 
image  suffers  somewhat  thereby,  and  does  not  appear  as  sharp  as 
with  the  prism  illuminator.  This  disadvantage  can  be  remedied 
somewhat  by  decreasing  the  opening  angle  of  the  objective.  The 
important  advantage  of  the  45  degree  plane  glass  illumination  is 
that  the  light  strikes  the  etched  surface  at  exactly  90  degrees,  ro 
that  with  the  highest  magnifications  and  in  working  with  very  fine, 
slightly  etched  specimens  images  richer  in  detail  and  free  from 
spectral  colours  are  obtained;  the  rays  of  light  are,  in  this  case, 
uniformly  distributed  over  the  entire  field  covered  by  the  objective. 
In  applying  the  Le  Chatelier  prism  illuminator,  one  half  of  the 
objective  serves  for  illuminating  the  specimen,  the  other  half  for 
producing  the  image.  This  arrangement  offers  the  advantage  thit 
by  dividing  the  function  of  the  objective  the  formation  of  reflexes 
is  reduced  and  the  full  angle  of  opening  of  the  objective  is  utilised. 
The  images  thus  obtained  are  clearer  and  sharper,  of  special  advan- 
tage in  photography.  On  the  other  hand,  fine  details  of  structuT-e 
may  be  lost  through  the  one-sided  illumination  striking  the  etch<3d 
surface  at  an  angle.  Since  both  forms  of  vertical  illuminators  possess 
certain  distinct  advantages  and  disadvantages,  it  will  be  found 
very  convenient  to  be  able  to  change  quickly  from  one  to  the 
other,  and  to  select  the  one  which  will  give  the  more  satisfactory 
image,  depending  upon  the  nature  of  the  microstructure  under 
investigation  and  upon  those  points  that  the  metallographer  desires 
to  bring  out  more  prominently  in  his  micrographs.  The  latest 
metallographic  outfit  brought  on  the  American  market  by  my  firm 
possesses  this  important  feature  of  *'  selective  "  vertical  illumination. 

Many  of  the  steel  works'  metallographers  prefer  now  the  inverted 
form  of  microscope,  first  designed  by  Le  Chatelier  and  first  made 
by  Pellin.  I  desire  to  mention  here  that  the  original  Le  Chatelier- 
Pellin  outfit  carried  a  stage  supported  on  one  point  only,  which 
was  easily  bent  out  of  focus,  and  did  not  possess  sufficient  rigidity. 
Le  Chatelier  designed  in  1911  another  and  very  much  improved  inverted 
stand,  also  made  by  Pellin,  which  carries  a  firmly  supported  stage 
and  which  was  imitated  by  German  and  Austrian  manufacturers. 
Nevertheless,  the  largest  number  of  German  steel  works,  amongst 
them  the  Krupp  works,  preferred  the  new  Le  Chatelier-Pellin  stand 
which  was  marketed  in  1912  and  1913  with  much  success  in  Ger- 
many by  Dujardin,  who  imported  the  microscopes  from  Paris  and 
fitted  them  with  Zeiss  apochromatic  objectives,  thus  combining  best 
mechanical  design  with  good  optical   equipment. 

Returning  to  the  question  of  metallurgical  microscope  stand 
design,  I  want  to  say  that  the  popular  form  of  inverted  stand  really 
has  only  the  one  advantas^e  of  eliminating  the  necessity  of  levelling 
the  specimen,  and  this  advantage  disappears  mostly  in  using  an  oil 
immersion  lens.  The  disadvantages  of  the  inverted  stand  are  the 
limited  field  which  can  be  observed,  the  large  leverage  of  the  stage 
resulting  in  magnification  of  vibrations,  and  the  impossibility  of 
working  with  daylii^ht.  Microscope  stands  have  been  successfully 
designed  (Felix  Robin's  outfit,  formerly  made  by  Collot,  Paris), 
which  combine  the  advantage  of  horizontal  camera  with  firmly  sup- 


MICROSCOPE:    HEKMAN   A.    HOLZ  193 

ported  stage  below  the  objective,  thus  permitting  the  convenient 
investigation  and  photography  of  heavy  specimens,  observation  of 
their  edges,  use  of  daylight,  and  large  reduction  of  vibrations. 
While  these  outfits  are  not  available  any  longer,  it  seems  to  me 
that  the  development  of  satisfactory  photomicrographic  apparatus 
for  metallography  should  follow  this  general  design,  and  not  the 
inverted  design,  which  possesses  several  disadvantages  more  impor- 
tant than  its  one  single  advantage. 

Amongst  other  microscopic  problems  awaiting  further  develop- 
ment, besides  higher  magnification,  are:  the  utilisation  of  polarised 
light  for  metallographic  investigations  and  the  application  of  kine- 
niatographic  work  to  the  study  of  structural  changes  in  metal 
sections  exposed  to  mechanical  stresses  or  varying  temperatures. 
The  pioneer  work  in  solving  the  apparatus  development  problems 
for  these  studies  has  been  successfully  carried  out,  and  the  high 
value  of  such  investigations  will  be  appreciated.  It  is  to  be  hoped 
that  research  workers  will  take  up  systematically  this  work,  which 
has  been  successfully  started.  Further  microscope  development, 
offering  no  more  difficulties,  will  be  in  the  direction  of  stereoscopy. 
We  are  born  with  two  eyes,  and  used  to  see  with  both  of  them; 
mon-objective  binocular  microscopes,  for  work  with  the  highest  mag- 
nifications, have  been  successfully  developed,  and  there  seems  to  be 
no  reason  why  this  instrument  development  should  not  be  applied 
to  advantage  to  metallographic  practice.  I  believe  that  the  near 
future  will  see  a  large  extension  in  the  use  of  binocular  optical 
instruments. 

I  would  not  like  to  omit  here  to  mention  some  important  pro- 
gress made  in  Great  Britain  in  the  development  of  metallographic 
equipment:  The  Edison-Swan  "  Pointolite  "  (tungsten  arc)  lamp, 
which  is  the  ideal  source  of  light  for  photomicrographic  work,  and 
the  Wratten  and  Wainwright  light  filters  and  special  plates  for 
photomicrography.  These  products  represent  the  best  that  has  ever 
been  developed  in  their  respective  lines,  and  every  metallographer 
will  find  the  use  of  these  appliances  extremely  valuable  in  his  work. 

In  ending  my  contribution,  I  want  to  make  a  few  additional 
remarks  about  the  importance  of  "  magnetic  analysis  "  in  metallo- 
graphic research  and  routine  work.  The  use  of  higher  magnifica- 
tions in  microscopic  investigation  will  most  probably  lead  to  valuable 
results,  although  we  must  always  remember  that  the  higher  we 
magnify  the  less  we  see,  i.e.,  the  field  of  observation  is  getting 
smaller  with  the  use  of  objectives  of  higher  powers.  Magnetic 
analysis  (the  accurate  determination  of  the  various  magnetic  proper^ 
ties  of  iron  and  steel  by  means  of  a  standard  permeameter)  enables 
us  to  draw  distinctions  between  steels  where  the  present  methods 
(microscopic,  hardness,  tensile  tests)  fail  to  make  differentiation. 
Microscopic  investigation  of  steel  gives  results  which  are  qualita- 
tive, rarely  quantitative.  The  preparation  of  micro-sections  often 
releases  stresses  in  the  metal  to  be  studied,  and,  in  general,  tests 
of  this  kind  require  a  great  deal  of  individual  judgment  and  experi- 
ence. Magnetic  data  permit  quantitative  measurements  of  the  state 
of  micro-structure  and  the  interpretation  of  test  data  leaves  no  room 
for  conjecture. 


194  THE   METALLURGICAL    MICROSCOPE 

Such  magnetic  investigations  can  be  carried-  out  successfully 
only  by  means  of  a  perfectly  reliable  permeameter  and  only  by 
determination  of  all  the  magnetic  characteristics  of  the  material 
under  investigation.  Permeameter  equipment  has  been  recently 
developed  to  a  high  stage  of  perfection,  combining  simplicity  of 
operation  with  perfect  accuracy  of  measurements  (Fahy  Simplex 
Permeameter),  and  since  then  the  application  of  magnetic  analysis 
to  metallographic  investigations  has  made  rapid  progress  in  the 
L^nited  States,  It  is  to  be  hoped  that  British  metallurgists  will 
apply  this  excellent  method  to  the  solution  of  their  problems,  and 
will  co-operate  with  American  research  workers,  to  considerable 
mutual  benefit. 


General  Discussion. 

In  inviting  Dr.  W.  H.  Hatfield  to  offer  some  remarks 
on  the  metallograpliical  side  of  microscopy,  the  Chairman 
suggested  that  in  view  of  the  short  time  available  for 
general  discussion  of  the  many  important  papers  presented 
on  this  subject,  the  discussion  be  continued  at  Sheffield, 
and,  if  possible,  also  at  Glasgow. 


Vr.  W.  H.  Hatfield:  I  should  like  to  say  that  I  know  I  should 
be  expressing  the  general  feeling  of  the  Council  of  the  Metallurgical 
Society  at  Sheffield  in  saying  that  we  have  great  pleasure  in  accepting 
your  invitation.  If  you  will  let  us  have  copies  of  these  papers, 
particularly  the  metallurgical  section  of  them,  we  will  have  them 
thoroughly  discussed,  and,  if  you  desire  it,  we  will  send  Mr.  Spiers 
a  copy  of  the  discussion. 

Speaking  on  the  papers,  I  think  one  can  safely  say  that  we  have 
in  Sheffield  many  large  firms  who  have  well  equipped  laboratories 
where  these  different  types  of  microscopes  are  in  use  every  day.  I 
should  like  to  congratulate  the  President  on  the  interesting  paper 
by  Mr.  Elliot  and  himself.  I  think  that  the  work  contained  in 
this  paper  typically  represents  what  we  are  able  to  do  with  the  micro- 
scope in  our  study  of  steel.  We  (Brown-Firth  Research  Laboratory) 
have  some  photomicrographs  upstairs;  they  are  really  on  the  same 
lines  as  those  of  Sir  Robert  Hadfield,  but  we  have  gone  as  far  as 
8,000  magnifications.  I  think  Sir  Robert  will  probably  agree  with 
me  when  I  say  that  1,000  diameters  really  represents  the  limit  of 
adequate  resolution  which  we  are  able  to  obtain  in  our  general  prac- 
tice, and  that  if  we  go  in  for  these  higher  so-called  magnifications — I 
refer  both  to  his  illustrations  and  to  ours — we  are  getting  enlarged 
pictures,  but  we  do  not  obtain  really  much  more  information  as  to 
the  structure  of  our  materials,  and  from  that  point  of  view  it  is 
interesting  to  refer  to  the  paper  on  Dr.  Sorby  which  the  President 
has  put  before  us.  I  notice  there  that  Sorby  made  great  advance 
in  the  'eighties  because  he  was  able  to  use  sufficiently  high  magnifica- 
tion' to  see  the  structure  of  the  pearlite.  Every  time  that  we  have 
been  able  to  get  a  still  higher  resolution  we  have  obtained  more 
fundamental  knowledge  with  regard  to  steel,  and  whilst  I  feel  that 
1,000  is  at  present  our  practical  limitation,  I  am  certain  that  if 
only  you  experts  in  the  construction  of  the  microscope  can  go  still 
further,  we  shall  obtain  still  more  fundamental  information.  For 
instance,  I  remember  studying  what  we  know  as  black  steel  at  250 
to  500  diameters,  but  we  got  inconclusive  information,  but  as  soon 
as  we  got  to  1,000  diameters  we  had  definite  information  and  a 
complete  solution  of  our  difficulty.  There  are  two  problems  which 
I  would  like  to  point  out  to  you  microscopists,  or  rather  to  the  makers 
of  microscopes,  which  are  awaiting  solution.  One  l3r.  Aitchison 
deals  with  very  ably  in  his  paper,   i.e.,   notched   bar  brittleness.     I 

195 


196  DK.  W.  H.  HATFIELD 

will  not  go  into  it  except  to  say  that  there  are  two  fundamentally 
different  conditions  of  the  same  steel,  which  at  present  we  are  not 
able  to  obtain  the  reason  for  by  means  of  the  microscope,  and  I 
think  we  have  a  right  to  feel  that  we  should.  I  do  not  hesitate  to 
make  a  confession  to  you.  An  artilleryman  does  not  worry  unduly 
as  to  how  the  gun  was  made  or  who  made  it.  I  represent  exactly 
that  type  of  scientific  investigator  who  uses  a  microscope,  and,  like 
the  artilleryman,  I  am  telling  you  what  we  would  like  to  do  with 
the  gun.  Therefore,  I  think  it  is  up  to  the  makers  of  the  microscope 
to  help  Sir  Robert  Hadfield  and  many  people  like  myself  who  are 
engaged  in  these  investigations,  out  of  our  difficulties.  In  conclusion, 
I  would  tell  you  that  all  metallui'gists,  whether  they  be  working 
on  steel  or  non-ferrous  metals — brass,  copper,  gold — are  faced  with 
the  difficulty  of  obtaining  an  adequate  solution  as  to  the  cause  of 
the  effect  of  cold  work  on  metals.  We  discuss  the  amorphous  theory ; 
many  of  us  believe  in  it;  we  ought  to  be  able,  by  means  of  the 
microscope,  if  you  will  give  us  a  suitable  tool,  to  obtain  an  adequate 
solution  of  that  problem.  Why  has  cold  work  the  great  effect  it  has 
in  hardening  metals?  Gentlemen,  I  consider  the  solution  of  that 
problem  is  awaiting  the  excellence  of  your  products. 


ME.  A.  T.  ADAM  AND  MR.  F.  S.  MEKKiLS  197 


The  following  contributions  have  been  received  to  the 
discussion  on  the  paper  by  Sir  Robert  Hadfield  and 
Mr.  T.  G.  Elliot. 


Mr.  A.  T.  Adam  and  Mr.  F.  S.  Merrils:  In  studying  the  micro- 
structure  of  steel  wires  we  have  found  it  necessary  to  employ  high 
magnification.  The  difficulty  in  resolving  the  structure  of  carbon 
steel  wires  is  due  in  the  first  place  to  the  nature  of  the  chief  con- 
stituent in  properly  heat-treated  wire,  viz.,  "  Sorbite,"  or  "  Sorbitic 
pearlite,"  and  secondly  to  the  minuteness  of  the  structure  caused 
by  cold  work. 

Some  time  ago  we  were  fortunate  in  securing  a  very  good  Leitz 
1/12  in.  oil-immersion  achromatic  objective,  N.A.  1.3,  which  has 
enabled  us  to  obtain  sharp  photographs  of  wire  up  to  a  magnifica- 
tion of  2,500  diameters.  This  we  have  found  to  be  about  the  highest 
magnification  at  which  good  definition  and  detail  are  retained  with 
this  objective.  In  certain  special  cases  we  have  gone  up  to  about 
5,000  diameters  with  distinct  advantage. 

One  of  the  contributors,  being  engaged  in  an  investigation  on 
''  The  Relation  of  Heat  Treatment  to  Cold  Work,"  has  foinid  these 
photographs  of  great  service  in  illustrating  the  effect  of  cold  work 
on  the  structure,  and  hopes  to  have  them  published  in  the  Carnegie 
Scholarship  Memoirs  of  the  Iron  and  Steel  Institute  this  year. 

It  is  admitted  that  there  is  a  certain  loss  of  detail  in  these 
photographs  as  compared  with  visual  examination,  but  this  detail 
is  lost  in  any  photograph  where  an  ordinary  eye-piece  is  used.  On 
the  other  hand,  certain  features  which  are  barely  visible  in  a  photo- 
graph at,  say,  1,500  diameters,  are  more  pronounced  in  the  enlarge- 
ment obtained   by  increased   camera  length. 

In  view  of  these  attempts  at  high  power  photomicrography,  we 
are  therefore  extremely  interested  in  the  authors'  work  in  this 
direction,  and  we  are  in  entire  agreement  with  them  in  the  belief 
that  there  is  a  great  field  for  further  exploration  in  this  direction. 

One  or  two  examples  of  photomicrographs  at  high  magnification 
are  given  below  with  details.  The  source  of  illumination  used  is 
a  tungsten  arc  500  candle-power  "  Pointolite,"  made  by  the  Edison 
Swan  Electric  Co.,  Ltd.  With  this  source  of  light  it  is  only  neces- 
sary to  use  a  single  condenser  to  focus  the  image  of  the  incandescent 
arc  on  to  the  plain  glass  illuminator.  It  may  be  of  interest  to  add 
that  Wratten  and  Wainwright  colour  filters,  M  series,  were  used 
with  Wratten  M  Panchromatic  Plates  in  taking  these  photographs. 

Fig,  1  shows  that  it  is  possible  to  obtain  good  definition  in  a 
photograph  at  this  magnification.  The  subject  is  possibly  not  one 
that  requires  high  magnification  in  itself,  but  it  is  useful  for  pur- 
poses of  comparison  with  subjects  that  do  require  such  magnifica- 
tions, e.g..  Fig.  3. 

Apart  from  this,  it  appears  to  show  that  **  pearlite  "  is  a  more 
complex  constituent  than  lower  power  photographs  indicate.  The 
contributors  have  always  considered  the  idea  that  *''  pearlite  "  is 
constructed  of  alternate  layers  of  ferrite  and  iron  carbide  completely 


198  MR.   HENRY   M.  SAYERS 

separated,  to  be  rather  vague.  This  photograph  suggests  that  com- 
plete separation  has  not  taken  place  in  the  laminated  form,  and 
occurs  only  in  the  spheroidised  form;  e.g.,  Fig.   2. 

The  appearance  of  sub-laminations  in  Fig.  1  is  not  a  false  effect 
due  to  excessive  cutting  down  of  the  iris  diaphragm,  as  no  dia- 
phragm was  used  in  this  instance.  A  slightly  false  effect,  due  to 
this  cause,  is  evident  in  Fig.  5,  which  was  taken  expressly  for  this 
contribution. 

Fig.  3  shows  a  subject  in  which  the  laminations  are  too  fine  to 
be  clearly  photographed  at  a  niagnification  of  1,500  diameters.  The 
photograph  demonstrates  that  even  air  cooling  a  rod  about  \  in. 
diameter  is  not  sufficiently  rapid  to  arrest  the  partial  production 
of  **  pearlite.*'  It  will  be  noticed  that  the  constituent  which  we 
have  called  **  sorbitic  pearlite  "  is  partly  cellular. 

The  difference  between  these  structures  is  not  apparent  at  lower 
powers. 

Fig.  4  is  to  be  compared  with  Fig.  5.  In  spite  of  the  slightly 
false  effect  in  the  latter,  caused  by  the  iris  diaphragm,  it  draws 
attention  to  the  existence  of  a  feature  which  might  easily  escape 
notice,  but  which  is  apparent  on  closer  examination,  in  Fig.  4, 
namely,  the  sub-laminations. 


Mr.  Henry  M.  Sayers  :  These  photomicrographs  of  steel  at  5,000 
and  8,000  diameters  are  very  fine,  and  testify  to  the  skill  and  patience 
of  the  authors.  They  confirm  the  accepted  theory  that  no  new  details 
can  be  revealed  by  magnifications  incommensurate  with  the  N.A.  of 
the  objective.  With  an  N.A.  of  1.4,  1,000  diameters  shows  all  that 
can  be  seen,  but,  of  course,  greater  amplification  may  be  useful  for 
diagrams  to  be  displayed  to  large  numbers  of  people,  at  once,  just 
as  lantern  slides  are  magnified  by  projection. 

The  authors  state  that  the  illuminant  used  was  a  20  ampere  alter- 
nating current  arc,  the  arc  being  focussed  on  the  stop  or  aperture  of 
the  vertical  illuminator.  Presumably  one  or  other  of  the  carbons 
was  so  focussed.  This  adds  to  the  merit  of  the  work,  for  certainly 
an  A.C.  arc  is  less  satisfactory  in  intensity  and  form  of  the  radiant 
than  a  C.C.  arc  crater. 

It  will  probably  be  found  that  one  of  the  larger  tungsten  arc 
lajnps  is  better  than  an  A.C.  arc.  It  is  true  that  the  tungsten  arc 
requires  continuous  current,  but  this  can  be  got  from  an  A.C.  supply 
with  a  simple  form  of  auto-transformer  and  rectifier.  A  nominal 
100  c.p.  Pointolite,  taking  about  \\  amperes,  gives  satisfactory 
negatives  of  steel  with  5  minutes*  exposure,  at  1,200  diameters, 
using  a  light  filter  denominated  "  5  times,"  and  Wellington  "Anti- 
Screen  *'  plates. 

The  Pointolite  lamp  is  somewhat  more  convenient  for  the  neces- 
sary source  emplifying  lens  system  than  an  arc.  The  exposures  above 
mentioned  were  taken  with  a  combination  which  magnified  the  source 
about  three  diameters,  giving  a  field  of  3  in.  diameter,  i.e.,  com- 
fortably filling  a  quarter  plate.  With  no  amplifier  the  field  on 
the  plate  was  only  about  1  in.  diameter.  Greater  amplification  can 
be  obtained  if  required  by  varying  the  lens  distance  of  the  combina- 
tion. 


Adam    and    Merrils.     1. 


Fig.  I. 

.2  per  cent.  Carbon  Steel,  annealed.     Mag-nificatidn  5.000  diams.  approx. 

K.I   Colour  Filter. 


Fig.  2. 

1.2     per    cent.     Carbon     Steel    Wire.     Re-heated    at    650°    C,     showing 

Spheroidised  Cementite.     Magrnification  -|..oco  diams.  approx.     Red  Colour 

Filter  A,  showing-  maximum  detail. 


Fig.  3. 

900°  C,  showing-  Sorbitic  Pearlite.     Magnification  3.000  diams.     Orange 
0.85  per  cent.  Carbon  Swedish  Steel.     No.  5  S.W.G.  Rod.     Air-cooled  from 

Colour  Filter  G. 


Adam  and  Merrils.  -2. 


Fig.  4. 

0.5   per  cent.    Carbon    Steel  Bar,   annealed.        Magnification    i.i<>f>  diams. 
Red  Colour  Filter  A. 


Fig.   5. 
Portion  of  same  field.     Magnification  4,500 diams.     K.i  Colour  Filter. 


XoTE.— These   reproductions   have   been    reduced   ])y   one-third    from   the 
original  photographs. 


PROFESSOR  H.  M.  HOWE  i9y 

Professor  H.  M.  Howe  {communicated). 

All  our  present  conceptions  of  the  nature  of  alloys  are  due  to 
the  microscope.  The  labours  of  Sorby,  of  Osmond,  and  of  Le 
Chatelier,  brought  us  to  the  point  at  which  we  recongise  pearlite  as 
an  eutectoid,  the  great  turning  point  in  the  progress  of  our  concep- 
tions. 

One  finds  important .  problems  solved  quickly  and  surely  by  means 
of  a  magnification  of  2,000  which  ' completely  baffled  us  when  our 
magnification  was  confined  to  200  diameters.  Thus,  just  as  the  first 
step  of  slight  magnification  opened  up  a  new  world  to  us,  so  a  second 
step  has  brought  new  and  important  conceptions  of  great  potential 
service. 

Have  we  not  good  reason  to  hope  from  the  past  that  like  impor- 
tant knowledge  awaits  further  increase  in  our  powers  of  magnifica- 
tion? Have  we  not  every  reason  to  believe  that  this  knowledge  is 
there  to-day,  behind  that  closed  door,  awaiting  its  unlocking  by 
him  who  shall  devise  the  key  ?  No  doubt  the  technical  difiiculties 
are  extreme,  but  surely  the  reward  which  awaits  success  should  be 
proportionally  great. 


A  group  of  papers,  presented  and  taken  as  read,  discussed 
various  other  aspects  of  the  microscope,  its  use  and 
applications. 


THE    MEASUREMENT    OF    GRAIN    SIZE. 

By  Zay  Jeffries,  Cleveland,  Ohio. 


Just  as  the  telescope  has  given  us  certain  information  in  astronomy 
which  we  know  no  other  way  of  obtaining,  so  the  microscope  has 
permitted  us  to  obtain  direct  knowledge  concerning  many  things 
unresolvable  with  the  naked  eye.  Much  of  the  knowledge  gained  with 
microscopes  would  not  be  obtainable  in  any  other  way.  For  example, 
the  quantitative  determination  of  grain  size  of  fine  grained  metal  is 
only  possible  because  of  the  microscope.  The  purpose  of  this  brief 
note  is  to  point  out  a  case  in  which  chemical  analysis  varies  but  little, 
and  success  or  failure  depends  on  the  grain  size  which  can  be  deter- 
mined only  with  a  microscope. 

In  the  mechanical  working  of  tungsten  it  was  found  that  some  lots 
of  metal  would  work  well,  and  some  only  with  great  dif&culty.  Some- 
times the  metal  would  be  so  hard  that  it  could  not  be  drawn  to  the 
smaller  sizes ;  it  would  either  break  too  frequently  or  the  die  wear  would 
be  so  great  that  it  could  not  be  tolerated.  A  careful  study  of  these 
materials  was  made  from  both  chemical  and  physical  standpoints.  The 
chemical  analysis  was  found  to  be  so  nearly  constant  that  errors  of 
analysis  would  mask  any  differences  wdiich  might  actually  be  present. 
It  is  not  maintained  that  slight  differences  in  analysis  did  not  exist, 
but  only  that  the  determination  of  the  impurities  which,  aside  from 
thoria,  probably  did  not  exceed  0.05%,  gave  no  definite  clue  to  the 
difficulty. 

It  was  found  that  the  variation  in  grain  size  was  greater  than  the 
variation  of  any  of  the  chemical  or  physical  properties,  and  that  the 
working  properties  varied  with  the  grain  size.  The  larger  grains  had 
more  ability  to  stand  extreme  deformation  than  the  smaller  ones.  On 
the  other  hand  the  tendency  to  break  in  the  early  stages  of  w^orking  was 
greater  in  the  coarse  grained  material.  If  the  grains  were  too  small 
in  the  tungsten  metal  containing  0.75,  per  cent.  ThOa  the  wires  broke 
frequently  in  the  smaller  sizes  and  the  die  wear  was  excessive.  In  this 
metal  the  danger  line  is  reached  if  the  number  of  grains  per  square 
millimetre  exceeds  about  6,000.  On  the  other  hand,  it  is  desirable 
that  the  tungsten  metal  have  an  inherent  high  resistance  to  grain  growth 
to  insure  a  long  life  in  the  lamps.  This  factor  is  usually  satisfied  if 
the  number  of  grains  per  square  millimetre  exceeds  1,500.  It  is, 
therefore,  desirable  to  control  the  grain  size  between  1,500  and  6,000 
grains  per  square  millimetre  in  the  ingot. 

In  the  early  days  of  working  tungsten  no  such  control  was  exercised 
and  lots  of  metal  were  encountered  which  were  unworkable,  and  no  one 
knew  the  reason.  The  inference  now  is  that  the  ingots  were  too  fine 
grained  since  it  is  possible  to  reproduce  these  results  with  fme  grained 
metal  to-day.  A  contributing,  and  sometimes  the  major  cause  of 
trouble  was  the  failure  to  eliminate  the  oxide  of  tungsten,  but  even  this 
is  more  readily  detectable  with  the  microscope  than  by  chemical  analysis. 

Every  lot  of  tungsten  metal  made  at  the  Cleveland  Wire  Division 
of  the  General  Electric  Company  is  now  tested  for  grain  size ;  in  fact, 
treated  to  give  the  proper  grain  size  in  many  cases.     The  lots  not  falling 


200 


ZAY    JEFFRIES  201 

witliin  the  proper  limits  of  grain  size  are  not  subjected  to  the  working 
process,  which  costs  on  the  order  of  twenty  times  as  much  as  the 
preparation  of  the  ingot. 

The  method  of  quantitatively  determining  the  grain  size  has  been 
described  by  the  author  in  the  Transactions,  of  tJie  Faraday  Society.^ 
A  circle  79.8  millimetres  diameter  is  drawn  on  a  ground  glass,  and  the 
image  of  the  properly  etched  sample  is  brought  into  good  focus.  The 
grains  intersected  by  the  circumference  of  the  circle  are  counted  and 
multiplied  by  .5  (in  the  paper  above  mentioned  this  factor  was  given  as 
.6,  but  later  results  show  that  .5  is  both  more  accurate  and  simpler  to 
use),f  and  this  product  is  added  to  the  number  of  grains  completely 
included.  The  sum  is  the  number  of  whole  grains  within  the  area 
represented  by  the  circle. 

It  is  true  that  the  determination  of  grain  size  in  other  metals,  such 
as  alpha  brass,  has  been  used  as  a  help  to  works  control,  but  the 
application  of  this  is  not  very  extensive  and  not  as  necessary  as  with 
tungsten.  Other  differences  are  manifest  which  may  be  easier  to  deter- 
mine than  the  grain  size.  Several  metallographists  have  told  the 
writer  that  they  had  investigated  the  variations  in  grain  size  and  found 
that  the  physical  properties  did  not  vary  greatly  with  considerable 
variations  in  grain  size,  and  hence  they  had  concluded  that  the  test  was 
not  suitable  for  their  purposes.  It  is  for  this  very  reason  that  the 
writer  believes  that  many  other  special  cases  will  arise  in  which  a 
considerable  change  in  grain  size  will  correspond  to  but  slight  differ- 
ences in  certain  other  properties  (like  the  working  properties  in  tung- 
sten), and  these  properties  may  be  controlled  within  narrow  limits  by 
controlling  grain  size.  In  fact,  metals  or  alloys  other  than  tungsten 
have  certain  properties  which  can  be  controlled  only  by  controlling 
grain  size  or  other  structural  features,  but  these  structures  are  pro- 
duced by  uniform  processing  determined  by  experience,  and  the  actual 
quantitative  determination  of  grain  size  is  not  necessary.  With  the 
modern  demand  for  uniformity  of  product  and  high  standards,  the 
manufacturing  tolerances  will  be  reduced,  and  extended  use  of  grain 
size  control  may  be  expected.  Even  now  the  defective  loss  in  the 
mechanical  working  of  metal  could  be  reduced  in  many  instances  by 
properly  controlling  the  grain  size  in  the  various  stages  of  processing. 
In  large  plants  the  lessening  of  the  defective  loss  a  fraction  of  one  per 
cent,  would  more  than  pay  the  cost  of  investigation  and  upkeep  of 
these  control  methods. 


*  Vol.   XII,  Part  I,   iQi/,  p.  40. 

t  Metallurgical  &  Chemical  Engineering,  p.  185,  Feb.  15,  1918. 
Also  Sano  and  Ohashi,  Proc.  of  the  Physico-Mathematical  Society  of 
Japan,  3rd  Series,  Vol.  I,  No.  7,  p.  216,  treat  this  method  of  grain  size 
determination  mathpmatically,  and  conclude  that  "Jeflfiries' formula  .  .  . 
is  quite  sufficient  for  practical  purposes." 


NOTE   ON   MICEOSCOPE  MICEOMETEY. 
By  Professor  W.  M.  Thornton,  D.Sc. 

Ill  the  increasing  use  of  the  microscope  by  engineers  for  the 
measurement  of  small  objects  which  cannot  be  dealt  with  by  usual 
micrometric  methods,  the  need  is  occasionally  felt  of  a  means  of 
calibrating  the  eye-piece  micrometer.  For  this  purpose-  it  is  convenient 
to  have  a  scale  one  centimetre  long  photographed  on  a  glass  slide,  and 
divided  into  millimetres,  half  millimetres,  tenths,  hundredths,  and 
possibly  thousandths. 

This  is  covered  with  a  thin  slip  of  mica  or  glass  cemented  on  round 
the  edges. 

The  object  of  this  note  is  to  call  attention  to  the  convenience  of 
the  combination  of  such  a  scale  with  a  fully  divided  ocular  micrometer 
as  a  means  of  calibrating  rapidly  and  with  sufficient  accuracy  for  most 
purposes,  any  system  of  eye-piece  and  object  at  any  extension,  in  micro- 
scopes not  fitted  with  travelling  micrometer  stages.  The  idea  is  no 
doubt  old,  but  enquiry  over  a  wide  area  has  shown  that  it  is  not  in 
use  by  those  making  daily  observations,  and  to  engineers  and  physicists 
who  are  not  in  immediate  touch  with  microscope  theory  and  formulae 
it  may  be  useful  to  have  both  a  loose  scale  in  the  eye-piece  and  a- 
graduated  slide  for  calibration. 

Dr,  Maurice  Langeron,  Chief  of  the  Laboratory  at  the 
Medical  Faculty,  Paris,  presented  the  following  papers  on 
behalf  of  Dr  R.  Bazin. 

MAKING  ENLAEGED-SCALE   DEA WINGS  AFTEE  BAZIN. 

The  device  dispenses  with  a  camera  lucida,  and  consists  of  an 
ordinary  biconvex  lens  A,  giving  a  virtual,  erect  and  enla¥ged 
image  of  the  object  00,  which  is  placed  between  the  lens  and  its 
focus;  Fig.  1  explains  the  arrangement.  An  image  of  the  paper 
and  of  the  point  of  the  pencil  C  is  formed  on  the  plane  on  which 
the  object  rests,  being  produced  by  the  plano-convex  lens  B  of 
short  focus;  this  image  is  real,  reversed  and  reduced  in  size,  because 
the  paper  is  at  great  distance  beyond  the  focus.  The  biconvex  lens 
A  enlarges  both  the  small  image  of  the  pencil  point  and  the  object 
itself,  which  are  in  the  same  plane.  In  drawing  one  has  merely  to- 
trace  the  outline  of  the  image. 

EYE-PIECE  GRATICULE  FOE  DE AWING,  MEASUEING 
AND  COUNTING. 

(Bazin's  Rtseau  Ocnlaire.) 

When  painters  wish  to  copy  a  picture  on  a  different  scale,  they 
divide  the  photograph  of  the  picture,  as  well  as  the  canvas  on 
which  they  are  going  to  paint,  into  small  squares.  Each  little  square 
is  then  filled  up. 

The  reseau  oculaire,  or  eye-piece  graticule,  consists  of  a  plate 
on  which  lines,  very  fine,  yet  as  distinct  as  possible,  form  a  system 
of  squares  of  1  mm.  size.  This  plate  is  placed  on  the  diaphragm 
of  the  eye-piece. 

202 


DR.    R.    BAZIN 


203 


In  drawing  one  makes  use  of  squared  paper,  and  the  microscopic 
image  is  reproduced  in  the  way  that  the  painter  copies  his  picture. 
To  facilitate  taking  measurements,  one  of  the  squares  in  the  centre 
(see  Fig.  2)  is  subdivided  into  four  smaller  squares,  and  one  of  the 
small  squares  is  again  subdivided  in  the  same  way,  with  the  aid  of 
a  micrometer  objective.     Thus  measurements  can  easily  be  made. 


A.    Biconvex  lens 

aa' 

Focus  of  A 

B      Plano-convex  lens  of  short  focus 

ff' 

Focus  of  B 

and  o.o    erect  and  enlarged 

C. 

Pencil  Point 

I.      Vertical  Imagfe 

c. 

Imagre  of  Pencil  Point 

O.O.     Object 

KiG.    I 

When  particles  are  to  be  counted,  the  diluted  blood  or  bacteria- 
preparation  is  placed  in  some  cell  which  need  not  be  squared;  the 
thickness  of  the  cell  must  be  known.  It  will  be  possible  to  count 
the  number  of  globules  approximately,  provided  that  one  can  get 
them  displayed  in  a  single  layer.  The  volume  of  the  little  drop 
adhering  to  the  pipette  being  knowm,  the  area  which  the  drop  occu- 
pies can  be  measured  with  the  aid  of  the  graticule ;  by  counting  the 
mean  number  of  red  corpuscles  per  square,  an  approximate  estimate- 


204 


BAZIN'S   CAPILLARY   CHORESIMETER 


can  further  be  formed  of  the  number  of  elements  containd  in  the 
drop.  In  the  same  way  2)arasitic  organisms  and  leucocytes  can  be 
counted. 

The  reseau  also  serves  as  a  reference  system  of  co-ordinates,  and 
can  replace  the  pointer  of  the  eye-piece.  (The  device  was  described 
in  the  Bulletin  de  la  Soclett  cle  Pathologic  Exotique,  Vol.  XII., 
p.  135,  1919.) 


/ 

i\ 

! 
i 

4- 

\ 

:   / 

Fig.  2. 


BAZIN'S  CAPILLARY  CHORESIMETER. 

The  haematocrite  makes  use  of  centrifugal  force  for  the  purpose 
of  counting  the?  number  of  blood  globules.  With  a  similar  apparatus 
bacteria  suspended  in  distilled  water  can  be  counted ;  their  small 
size  calls  for  a  special  device,  however, 

A  glass  flask,  of  a  capacity  of  20  cub.  cm.,  is  terminated  by 
a  capillary  tube,  0.2  mm.  bore,  4  cm.  long:  The  extremity  of  the 
tube  is  closed  by  a  rubber  disc  kept  in  position  by  a  stirrup  which 
can  be  turned  about  its  axis  (see  Fig.  3).  The  stirrup  is  supported 
by  a  metal  collar  encircling  the  neck  of  the  flask.  The  upper 
aperture  of  the  flask  is  hermetically  closed  by  a  metal  stopper,  which 
is  provided  with  a  rubber  packing  and  screwed  into  the  collar. 
To  prevent  any  slipping  of  the  stirrup  during  the  centrifugation, 
the  capillary  tube,  to«:ether  with  the  stirrup,  is  enclosed  in  a  sleeve 
of  copper  or  brass.  The  capillary  tube  is  filled  with  distilled  water, 
the  rubber  disc  is  applied  to  its  lower  end,  and  the  stirrup  turned 
down.  The  bacteria  suspension  is  poured  into  the  flask,  the  stopper 
screwed  in,  and  the  sleeve  mounted.  The  apparatus  is  then  placed 
in  the  container  of  the  centrifugal  machine,  which  is  turned  for  ten 
minutes  at  7,000  revolutions.      The  bacteria  collect  in  the  capillary 


DK.    R.     BAZIN 


205 


tube,  and  are  watched  through  the  two  symmetrical  slots  in  the 
sleeve.  Measurements  are  taken  with  the  aid  of  a  vernier  and  a 
lens.  The  apparatus  is  calibrated  with  the  aid  of  bacteria  suspen- 
sions  of  known  numbers. 

The  capillary  tube  should  neither  be  too  fine  nor  too  coarse ;  in 
the  former  case  the  capillary  might  become  clogged,  in  the  latter 
the  precision  of  the  measurement  would  be  impaired.      The  dilution 


r^=^3=^ 


Flask  and     Graduated    Stirrup  and 
Capillary  Brass  Sleeve      Stopper 
Tube         with  Slot 

Fig.  3. 


of  the  suspension  must  also  be  suitable,  as  a  concentrated  prepara- 
tion would  entirely  fill  the  capillary.  The  distilled  water  used  should 
carefully  be  filtered,  since  a  small  particle,  e.g.,  of  cotton,  would 
stop  the  tube.  In  order  to  facilitate  comparative  determinations,  a 
standard  tube  containing  a  suspension  of  known  titre,  of  particles 
of  known  dimensions  and  density,  should  be  used ;  porphyrised 
kaolin  may  serv^  for  this  purpose,  after  levigation  and  filtration. 


THE  GRAYSON  RULINGS 
By  Dr.  A.  E.  H.  Tutton,  F.R.S. 

It  must  have  been  with  the  deepest  regret  that  workers  with  the 
microscope  heard  of  the  premature  demise  of  Prof.  II.  J.  Grayson, 
of  Melbourne,  the  remarkably  gifted  maker  of  the  well-known 
"  Grayson  Rulings."  Those  who  have  used  the  rulings  have  been 
struck  with  both  their  accuracy  as  regards  spacing,  and  the  extra- 
ordinary sharpness  of  each  individual  line,  especially  in  the  case  of 
those  on  speculum  metal.  The  truly  wonderful  guiding  of  the 
diamond  point  by  the  late  Prof.  Grayson's  own  unique  master  hand, 
no  less  than  the  perfect  construction  of  his  ruling  machine,  which 
enabled  such  accurate  spacing  to  be  obtained,  have  never  ceased  to 
impress  those  who  have  worked  with  these  rulings.  Their  merit 
begins  at  the  point  where  the  other  rulings  so  well  known  to  us,  such 
as  those  of  Rowland  and  of  Michelson,  leave  the  field,  namely,  above 
20,000  to  the  inch.  His  extreme  rulings  of  120,000  to  the  inch, 
are  a  direct  challenge  to  the  microscope,  for  they  represent  its 
highest  resolving  power.  While  these  wonderful  rulings,  and  those 
only  a  degree  less  impressive  of  100,000  and  80,000  to  the  inch,  are 
of  great  use  to  us  in  studying  high  resolution,  with  natural  micro- 
scopic objects  presenting  detail  of  great  minuteness,  and  also  in 
actual  calibration  and  measurement  of  the  detail  of  objects  of  sucH 
extreme  minuteness,  it  is  probably  with  the  more  moderately  spaced 
rulings  of  60,000  and  40,000  to  the  inch  that  the  most  important 
work  is  to  be  done. 

The  writer  has  already  called  attention,  in  his  memoir*  to  the 
Royal  Society  on  the  Interference  Comparator  for  Standards  of 
Length,  to  the  fact  that  the  Grayson  rulings  of  40,000  to  the  inch 
spacing  are  capable  of  becoming  of  great  importance  in  metrology, 
as  fiducial  marks,  the  middle  one  of  five  such  rulings  forming  an 
excellent  signal-mark.  For,  as  was  pointed  out  in  the  memoir,  the 
40,000th  of  an  inch  is  the  wave-length  of  red  light,  very  close  indeed 
to  the  exact  wave-lengths  of  the  red  hydrogen  (.^Jyo  iiich)  or  the 
red  cadmium  (..yj^y  inch)  line.  Thus,  the  space  between  any 
two  successive  lines  of  the  40,000  to  the  inch  rulings  corresponds 
practically  exactly  to  the  passage  of  two  interference  bands  (two 
complete  interference-band  spacings)  in  red  hydrogen  or  cadmiuni 
light.  That  this  is  true  of  the  late  Prof.  Grayson's  rulir^ 
labelled  by  him  as  40,000  to  the  inch,  has  been  proved  by  the 
writer  by  direct  measurement  against  the  interference  bands,  on 
the  Comparator  at  the  Standards  Department.  These  more 
moderately  finely  spaced  rulings  are  admirably  resolved  by  the 
l/15th  inch  dry  objective  supplied  for  the  purpose  by  Mr.  Conrad 
Beck.     The  lines,  indeed,  as  seen  through  the  fine-movement  micro- 

*  Phil.  Trans.,  A.,  1910,  210,  30. 

206 


DR.    A.    E.    H.   TUTTON  207 

scope,  are  as  clear  as  the  interference  bands  in  the  interferometer  of  the 
Comparator,  and  the  writer  expressed  hopes  in  his  memoir  to  be  able 
to  carry  out  with  their  aid  the  determination,  by  this  original  method, 
of  the  exact  nnmber  of  red  cadmium  wave-lengths  in  the  British 
Yard.  Such  a  determination  would,  indeed,  be  quite  simple  and 
straightforward,  with  the  proviso  that  an  adequate  supply  of  the 
rulings  required  for  the  stepping  off  process  could  be  obtained. 

The  writer  also  hopes  to  use  them  as  fiducial  marks  in  connection 
with  interferometric  fine-measurement  in  general,  and  a  General 
Interferometer,  involving  the  same  type  of  travelling  fine-movement 
microscope  as  those  (the  pair)  on  the  Comparator,  is  being  con- 
structed for  him  for  the  purpose  at  this  moment. 

The  breaking  out  of  the  great  war,  and  now  the  unhappy  death 
of  Prof.  Grayson,  have  delayed  the  possibility  of  further  work  on 
the  subject,  and  as  doubtless  other  workers  in  high  power  microscopy 
are  also  at  present  unable  to  carry  out  their  own  particular  researches 
for  which  the  higher  rulings  are  essential,  the  writer  considers  it 
desirable  that  the  position  shall  be  discussed  at  this  Symposium  of 
Microscopists. 

The  writer's  suggestion  is  that  the  Symposium  should  address 
to  the  Governing  Body  or  Council  of  the  University  of  Melbourne  a 
letter  of  condolence,  expressing  firstly  the  unanimous  opinion  of  the 
great  body  of  Microscopists  and  Scientific  workers  here  assembled 
of  the  very  great  loss  which  the  University  has  suffered  by  the  demise 
of  Prof.  Grayson;  and,  secondly,  the  hope  that  the  University  will 
do  all  that  is  possible  to  ensure  that  Prof.  Grayson's  ruling  machine 
shall  still  be  available  for  the  production  of  the  '"'  Grayson  Rulings." 
It  may  be  that  Prof.  Grayson  had  trained  one  or  more  members  of 
his  staff  in  his  method,  and  if  so  it  should  not  be  difficult  to  arrange 
for  the  most  highly  desirable  continued  production  of  the  rulings. 

The  writer  took  the  opportunity  of  mentioning  the  matter  to 
General  Sir  John  Monash,  the  gallant  Commander  of  the  Australian 
Forces,  and  a  member  of  the  Governing  Body  and  Council  of 
Melbourne  University,  on  his  recent  visits  to  London  and  Oxford  on 
the  conclusion  of  the  War,  and  he  kindly  undertook  to  go  into  the 
question  on  his  return  to  Melbourne,  Possibly  General  Monash's 
relative.  Dr.  Rosenhain,  whom  we  know  to  be  interested  so  keenly  in 
the  subject  from  the  microscopical  point  of  view,  and  who  has  intimate 
connections  with  Melbourne  and  its  University,  will  also  be  inclined 
to  assist  in  carrying  the  subject  further. 

The  continued  production  of  the  Grayson  Rulings,  especially 
those  of  the  40,000  to  the  inch  spacing,  is  so  important  a  matter 
that  the  writer  has  felt  sure  that  the  Symposium  would  wish  hira 
to  bring  it  forward. 


THE  TESTING  OF  MICROSCOPE  OBJECTIVES  AND 
MICROSCOPES  BY  INTERFEROMETRY. 

By  F.  Twyman. 


My  firm  has  no  commercial  interest  in  microscopes,  and  so  far  1 
have  not  succeeded  in  interesting  any  microscope  makers  in  the  methods 
of  test  I  shall  describe.  We  have,  therefore, not  done  much  more  on  the 
subject  than  to  test  a  few  microscope  objectives,  and  these,  although 
by  makers  of  repute,  not  of  high  power.  They  show  aberrations  of 
wave  surface  not  exceeding  about  5  wave-length  for  monoclrromatic 
light  (wave-length  5461).  It  will  be  remembered  that  if  aberrations 
do  not  exceed  ^  wave-length,  the  resolving  power  of  an  optical  system 
is  practically  perfect.  This  was  found  by  Rayleigh  to  be  the  case  in 
certain  cases  calculated  by  him,  and  general  experience  shows  it  to 
be  a  sound  rule. 

The  interferometer  used  for  microscope  lenses  was  a  side  issue 
in  the  development  of  other  forms.* 

An  image  '  of  a  monochromatic  light  source  is  thrown  on  a 
diaphragm  which  has  a  small  hole.  The  light  passes  to  a  half- 
silvered  mirror  (Figure  1).  A  portion  of  the  light  is  reflected 
from  there  to  a  concave  mirror  so  situated  that  the  diaphragm  is 
approximately  at  its  centre.  From  the  concave  mirror  the  rays  are 
reflected,  and  a  portion  of  the  light  passes  through  the  half -silvered 
mirror,  and  is  focussed  on  the  eye  of  the  observer.  The  light  which, 
on  meeting  the  half-silvered  mirror  passes  through  it,  proceeds 
through  a  compensating  plate  as  in  the  Michelson  Interferometer; 
then  through  the  objective  under  test.  The  rays  pass  on  through  the 
image,  and  are  reflected  back  on  their  own  path  from  a  concave  mirror. 
Eventually  the  two  beams  of  light  combine  at  the  surface  of  the 
half -silvered  mirror,  and  pass  on  together  to  the  eye.  In  these 
circumstances  interference  effects  are  observed  which  appear  to  the 
observer  as  if  located  on  the  back  len?  of  the  objective  under  test, 
and  which  represent  a  contour  map  to  a  scale  of  half  wave-lengths 
of  the  aberrations  of  wave  surface  produced  by  the  objective  under  test. 

If  desired,  an  entire  optical  instrument,  such  as  a  microscope,  can 
be  tested,  in  which  case  the  arrangement  is  as  shown  in  Figure  2. 


*  Described  by  the  present  writer  in  the  Phil.  Mag.,  Vol.  XXXV., 
January,  IQ18,  "  Interferometers  for  the  experimental  study  of  optical  systems 
from  the  point  of  view  of  the  wave  theory." 

208 


F.     TWYMAN 


209 


cc    n 
O 


210 


TESTING     BY    INTERFEROMETRY 


U 

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o 
u 


> 


AN  ACCURATE  METHOD  OF  OBJECTIVE  AND   SUBSTAGE 
CONDENSER  TESTING. 

By  H.  Hartridge,  M.A.,  M.D., 
Fellow  of  King's  College,  Cambridge. 


Freliminary  C omviunication. 

The  methods  of  objective  testing  at  present  in  use  do  not  give 
quantitative  data,  and  depend  to  a  great  degree  on  the  keenness  of 
vision,  skill    and  memory  of  the  observer. 

A  method  which  does  not  suffer  from  these  defects  consists  in 
measuring  with  a  suitable  micrometer  the  position  the  image  pattern 
when  different  parts  of  the  objective  aperture  are  used.  If  the  lens 
is  perfect  and  in  correct  focus  no  movement  of  the  image  pattern 
occurs.  If  there  is  movement,  however,  and  if  the  micrometer  reading 
be  plotted  against  the  N.A.  of  the  part  of  the  objective  aperture  in 
use,  then  the  graph  thus  obtained  shows  the  aberrations  that  are 
present  and  their  amount, 

A  suitable  method  of  isolating  objective  apertures  of  given  N.A. 
was  obtained  by  moving  by  means  of  a  graduated  micrometer  screw 

a  slit-sliapsd  aperture  placed  below  an  oil  immersion  condenser.  The 
method  of  calibrating  the  micrometer  in  terms  of  N.A.  has  been 
previously  described. (1) 

The  best  eye-piece  magnification  was  found  to  be  about  100 
diameters;  this  was  obtained  by  a  2-3  in.  objective  and  a  x  10 
eye-piece. 

The  glass  plate  micrometer  proved  most  suitable  for  measuring 
the  displacements  of  the  image  patterns. 

The  method  of  illumination  has  already  been  described. (2) 

The  typical  graphs  obtained  for  certain  aberrations  may  now  be 
briefly  described. 

Centre  of  Field. 

Perfect  lens  (a)  correct  focus: — a  straight  vertical  line;  (b)  in- 
correct focus: — a  straight  inclined  line;  (c)  incorrect  tube-length:  — 
S-shaped  line. 

Imperfect  lens  (a)  sj^herical  aberration: — a  sinuous  line  (not  of 
regular  S-shape),  and  never  a  straight  line;  (b)  central  astigmat- 
ism :  — a  different  curve  in  one  azimuth  to  that  given  by  another. 


(i)  Hartridge,  Journ.  Roy.   Micro.   Soc.,   1918,  p.  337. 
(2)  Hartridge,    Journ.    Quekett   Micro.   Soc,  Nov.    iqiq. 

211 


212  OBJECTIVE  AND  SUBSTAGE  CONDENSER  TESTING 
Periphery  of  Field. 

A  straight  vertical  line  indicates  perfect  lens  in  correct  focus, 
(b)  An  inclined  straight  line  shows  perfect  lens  in  incorrect  focus. 
If  the    inclination    is    different    to    that    found    at    the    centre,    the 
difference  shows  the  degree  of  curvature  of  field. 

(c)  A  bent  line  denotes  presence  of  aberrations: — disobedience  of 
sine  conditions,  etc. 

Experience  shows  that  "  performance  curves  "  for  the  centre  of 
the  field  show  almost  at  a  glance  the  aberrations  present,  and  their 
degree.  Interpretation  of  curves  for  the  periphery  of  the  field  is 
more  difficult. 

Colour  filters  only  have  so  far  been  used  for  obtaining  approxi- 
mately monochromatic  li^ht,  a  prismatic  spectral  illuminator  would 
be  a  valuable  addition. 

It  will  be  observed  that  this  method  of  objective  testing  has  been 
developed  from  the  method  of  adjusting  tube  length  described  in  a 
previous  paper.  (3) 


(3)  Hartridge,  Journ.   Roy.   Micro.   Sac,    1919,  p.    i  ig. 


KEMAKKS  BY  SIR  HERBERT  JACKSON,  K.B.E.,  F.R.S.* 

By  the  courtesy  of  the  Chairman  1  was  able  to  see  in  advance  a 
great  number  of  the  interesting  papers  which  have  been  prepared 
for  this  meeting  to-day,  and  when  I  looked  at  them  I  discovered 
that  practically  everything  that  I  intended  to  say  was  included  in 
those  papers.  1  have  decided,  therefore,  that  it  would  be  better 
for  me  to  be  brief,  and  deal  very  generally  with  perhaps  only  two 
or  three  points. 

I  take  it  that  one  of  the  chief  reasons  for  this  Symposium  is  to 
consider  methods  for  promoting  the  study  of  the  microscope  and 
methods  for  extending  its  use  in  science,  in  industries,  and  in  educa- 
tion, I  should  like  to  mention  first  the  position  which  we  are  in  at 
the  present  day  with  regard  to  one  of  the  most  vital  parts  of  the 
microscope,  namely,  the  optical  glass.  I  should  like  this  meeting 
to  know  that  through  the  enterprise  of  British  manufacturers  we 
have  produced  and  we  can  produce  optical  glass  in  this  country  of 
a  quality  equal  at  least  to  the  very  best  that  was  ever  obtained 
from  abroad.  I  should  like  also  to  say  that  I  have  had  it  from 
the  manufacturers  themselves  that  they  are  perfectly  prepared  to 
do  their  very  best — and  they  have  already  shown  that  they  can  do  it 
— to  produce  any  glass  which  may  be  called  for.  There  is  a  great 
deal  yet  to  be  done,  not  on  their  part  so  much,  perhaps,  as  on  the 
part  of  those  whose  duty  it  is  to  make  investigations  with  the  object 
of  obtaining  new  glasses  with  optical  constants  differing  from  those 
which  have  been  made  hitherto,  so  that  combinations  can  be  made 
of  even  higher  quality  than  those  which  we  are  familiar  with  in  the 
best  lenses  that  exist.  I  think  also  that  it  should  be  well  known 
that,  till o ugh  the  efforts  of  the  Department  of  Scientific  and  Indus- 
rial  Research  and  in  other  ways,  mathematical  investigation  on 
methods  of  designing  lenses  are  in  progress,  and  I  think  we  may 
look  definitely  from  these  investigations  for  results  which  will  make 
a  heavy  demand  again  upon  the  skill  and  the  enterprise  of  the  manu- 
facturers of  optical  instruments. 

I  will  not  speak,  as  I  had  intended  to  do,  on  some  comparisons 
between  the  results  of  the  work  of  British  and  foreign  manufacturers, 
except  to  say  that  it  is  certainly  true  that  we  have  produced  optical 
trains  in  this  country  comparing  favourably  with  any  produced 
anywhere  else,  but  we  do  not  always  produce  them  with  that  constant 
accuracy.  I  think  it  is  fair  to  say  that  while,  in  the  early  history 
of  the  microscope  we  took  the  initiative,  in  later  years  there  has  been 
a  tendency  to  follow  rather  than  lead.  At  least,  that  is  true  of  some 
of  the  chief  developments  of  the  instrumental  part  of  the  micro- 
scope. Now,  what  we  have  to  do  is  no  longer  to  copy,  but  to  aim 
at  improvements  by  independent  research  and  invention.  There 
exists  at  the  present  time,  fostered  by  the  Department  which  I  have 
just  mentioned,  an  all-round  spirit  of  research  and  enterprise.  With 
out  elaborating  the  point,  one  can  now  express  the  hope  that  a 
bright  promise  of  future  development  will  not  fail  of  fulfilment 
through  lack  of  means  on  the  one  hand  to  attract  the  brains  and 
skill  which  are  abundant  in  this  country,   and  on  the  other  hand  to 

"••■■  See  above,  p.  43. 

213 


214  SIR    HERBERT    JA'CKSON 

make  possible  the  large  amount  of  expsrimental  work  which,  is  needed 
and  which  of  necessity  cannot  be  made  to  pay  except  indirectly,  and 
in  the  course  of  time.  Unless  we  can  get  experiments  of  that  kind 
made  by  the  people  in  the  factories,  the  hoped-for  advances  from 
the  instrumental  side  will  not  be  fulfilled,  at  least  to  the  extent  which 
some  of  us  think   and   believe   to   be   possible. 

I  turn  for  the  moment  to  the  point  of  view  of  education.  The 
growing  use  of  scientific  instruments  in  industry  definitely  calls  for 
some  systematic  education  in  the  theory  of  them  and  in  their  prac- 
tice. There  has  recently  been  created  a  School  of  Technical  Optics 
under  the  Directorship  of  my  friend  Professor  Cheshire.  We  may 
therefore  look  confidently  to  having  opportunities  afforded  for  a 
thorouo-h  and  systematic  education,  now  so  much  needed,  in  the 
subject  of  the  microscope  and  its  use.  That  need  existed  over  25 
years  ago,  but  I  do  not  know  that  any  marked  efforts  have  been  made 
to  give  the  systematic  education  required.  Take  the  difference 
between  the  subject  of  spectroscopy  and  microscopy.  In  spectroscopy 
the  work  of  educating  the  student  is  carried  out  in  a  systematic 
way.  There  is  lecture  work  and  laboratory  work,  and  I  think  the 
student  of  spectroscopy  knows  his  instrument  and  his  subject  as  well 
as  it  is  possible  to  do  in  the  time  he  is  required  to  spend  on  it.  It 
is  difficult  to  believe  that  the  student  of  microscopy  ever  had  a 
chance  of  knowing  his  subject  so  systematically  and  thoroughly. 
Therefore  I  plead  very  strongly  for  the  greatest  possible  support 
for  Professor  Cheshire,  so  that  he  may  bring  this  question  of  educa- 
tion in  the  microscope  to  a  really  practical  and  successful  issue.  Of 
the  many  possible  forms  of  propaganda,  none  is  likely  to  have  a 
better  or  more  lasting  influence  in  the  direction  of  arousing  interest 
in  the  subject  and  extending  the  use  of  the  instrument.  How 
many  of  us  have  seen  people  who  begin  with  the  microscope  and 
abandon  it  very  soon  after  taking  to  it,  and  in  nearly  all  cases  it 
A3LS  been  due  to  this,  that  they  have  had  nobody  to  show  them  how 
to  use  the  instrument  or  to  make  them  understand  what  the  micro- 
scope is,  what  it  is  in  theory  and  in  practice,  and  they  have  often 
not  been  able  to  interpret  what  they  see. 

We  have  listened  to  an  Address  by  Mr.  Barnard  which  is  very 
interesting  to  me,  because  I  have  had  the  opportunity  of  seeing  his 
work,  and  I  think  he  is  to  be  congratulated  on  the  scientific  work 
he  has  done  in  extending  the  u?e  of  the  microscope.  But  it  is  more 
than  that,  Mr.  Barnard  has  that  spirit  of  research  and  that  spirit 
also  of  rcali'^ing  that  there  is  to  be  interpreted  in  the  microscope  a 
groat  deal  that  has  escaped  observation,  although  it  may  have  been 
seen  dozens  and  even  thousands  of  times.  What  T  want  to  see  is,  in 
addition  to  the  necessary  lectures  on  the  theory,  the  formation  of 
classes  in  the  use  of  the  microscope  where  objects  are  studied  at  low 
powers  and  low  numerical  apertures,  and  at  high  powers  and  high 
numerical  apertures,  by  transmitted  light,  on  a  black  ground,  and 
by  opaque  illumination ;  and  each  appearance  critically  examined 
and  described. 

There  is  a  definite  lesson  as  to  how  each  type  of  image  is  to  be 
interpreted.  May  I  take  one  or  two  instances.  If  a  well-known- 
diatom,  picnrnxit/nia  (UK/iildf utn ,  is  examiued  with  an  illuminating- 
cone  of  not  more  than  .3  to  .4  N  A  ,  and  with  a  lens  like  a   1  inch. 


SIR    HERBERT    JACKSON  215 

by  ordinary  transmitted  light,  what  is  seen  is  a  brown  or  yellow- 
brown  object.  I  am  not  going  into  the  theory  or  the  details,  because 
it  would  take  too  long,  and  I  am  speaking  to  experts  who,  I  am 
quite  certain,  know  perhaps  better  than  I,  what  is  the  explanation 
of  the  brown  colour.  But  how  many  people  who  have  looked  at 
it  simply  as  an  object  have  asked  "  Why  is  it  brown?  "  If  you 
take  that  same  object  with  a  black  ground  illumination  and  a 
low  angle  objective,  using  an  illuminating  cone  of  .4  numerical 
aperture,  all  you  see  is  the  outline  of  the  specimen- 
Yet  what  a  wealth  of  information  is  to  be  gained  from 
an  investigation  of  the  inside  of  that  outline;  Mr.  Barnard 
has  well  indicated  that  when  he  was  speaking  of  work  in 
connection  with  the  yeast  cells.  If  you  raise  that  cone  to  .65 
with  a  black  ground  illumination,  with  the  sam<e  objective, 
the  object  then  is  a  beautiful  blue  or  violet  colour.  Raise  it  still 
higher  and  it  gets  nearer  to  a  greenish  colour,  and  if  you  put  on 
a  little  higher  angl,e  lens  with  an  immersion  condenser,  the  object 
looks  very  nearly  white;  raise  the  angle  still  a  little  higher  and  the 
image  is  white.  That  is  an  illustration  of  why  every  change  should 
be  explained  and  interpreted.  Take  another  illustration:  tous-les- 
mois  starch  grains  mounted  in  water.  With  a  black  ground  and  an 
objiective  of  a  numerical  aperture  of  .26,  it  is  really  a  pretty  object. 
The  grains  are  nearly  all  pearly  white,  and  the  concentric  rings  can 
be  seen  quite  well.  If  you  keep  the  same  objective,  but  raise 
the  numerical  aperture  of  the  condenser,  all  the  beautiful  light  goes, 
and  nothing  more  than  a,  mere  outlin^e  can  be  seen ;  it  looks  like  a 
little  ring  of  light  with  nothing  inside.  Raise  the  aperture  of  the 
objective  and  use  an  immersion  condenser,  and  you  begin  to  see 
a  little  more  showing  up  inside,  and  that  is  the  first  indication  of 
the  existence  of  a  structure  there.  I  should  like  the  same  thing  to 
be  taken  with  an  opaque  illuminator  and  examined.  Opaque  illum- 
ination, except  in  the  examination  of  metals,  has  not  had  the  atten- 
tion paid  to  it  that  it  should  have  because  we  have  not  laid  sufficient 
stress  on  the  necessity  of  looking  at  the  object  from  all  points  of 
view,  so  as  to  deicide  by  a  careful  comparison  of  the  appearances  in 
every  possible  form  of  illumination,  the  correct  and  proper 
interpretation.  The  student  might  be  encouraged  to  go  through  a 
systematic  course  of  theoretical  and  practical  microscopy,  applying 
what  he  learns  in  lectures  to  the  study  of  objects  of  comparatively 
well-known  structure  by  their  examination  with  optical  systems  of 
increasing  power  and  with  various  forms  of  illumination  until  he  has 
gained  a  real  knowledge  of  what  can  be  revealed  by  the  microscope 
and  of  what  are  its  limitations.  With  this  experience  he  would  be 
in  a  position  to  proceed  to  research  work  equipped  with  sound  theory 
and  the  fundamental  practical  knowledge  necessary  for  the  inter- 
pretation of  what  he  sees  and  the  avoidance  of  hasty  judgment 
through  incomplete  observations. 

If  we  could  look  forward  to  educational  work  somewhat  on  these 
lines  in  the  future,  people  who  wanted  to  study  microscopy  would 
find  there  was  a  great  deal  of  valuable  work  to  be  done  in  extending 
the  use  of  the  instrument.  The  brilliant  work  which  Mr.  Barnard 
is  doing  in  connection  with  ultra-violet  light  and  increased  resolving 
power  cannot  but  help  us  very  much  in  interpreting  many  things 
which  we  have  seen  but  have  not  understood. 


:216  LT.-COL.     GIFFORD 

The   following    papers    are     extended     descriptions    of 
.exhibits  shown  before  the  meeting. 


NOTE  ON  LIGHT  FILTERS  FOR  THE  MICROSCOPE  AND 
PHOTOMICROGRAPHY. 

By  Lt.-Col.  Gifford. 


As  far  back  as  1894  it  was  found  that  a  solution  of  malachite 
green  in  glycerine  absorbed  all  the  visual  spectrum  except  a  broad 
band  in  the  region  of  the  F  line  of  the  solar  spectrum,  and  a 
narrow  red  band  near  B  (J.R.M.S.,  1894,  pp.  164-7),  and  that  such 
a  solution  placed  in  a  glass  trough  was  eminently  effectual  as  a 
light  filter  for  microscopic  use,  especially  when  the  red  band  was 
removed  by  inserting  a  piece  of  signal  green  glass  into  the  fluid. 

The  year  following,  a  screen  similarly  constructed,  but  with  a 
solution  of  methyl  violet  for  use  in  photomicrography,  was  described 
(J.R.M.S.,  1895,  pp.  145-7).  In  recent  years  it  has  been  found 
that  peacock-green  glass  possessed  the  same  properties  as  signal 
green  to  a  greater  extent,  and  the  use  of  the  latter  has  therefore 
been  dropped. 

Instead  of  the  glass  trough  with  the  signal  green  placed  in  it, 
the  form  these  light  filters  have  recently  taken  is  as  follows :  — Discs 
of  peacock-green  glass  about  0.06  in.  thick  and  of  diameter  to  fit 
into  the  substage  condenser  are  cut  out.  On  these  discs  are  built 
up  cells,  using  gold  size  and  soft  metal  rings,  or  the  former  alone, 
just  like  those  made  for  mounting  microscopic  objects  in  fluids.  If 
a  metal  ring  is  used,  then  a  coat  of  size  must  be  given  to  the  top 
of  it  and  be  allowed  to  dry.  Then  a  final  coat  must  be  placed 
on  that  and  allowed  to  get  tacky.  Then  place  rather  more  than 
sufficient  dye  solution  in  the  cell  near  the  edge.  The  glycerine 
will  cause  it  to  stand  up  beyond  the  top  of  the  cell.  Take  a  clean 
glass  cover,  make  contact  with  the  tacky  gold  size  at  a  point 
nearest  the  drop  of  dye.  The  point  of  contact  will  act  as  a  hinge. 
Now  allow  and  assist  the  cover  to  fall  until  in  contact  with  the 
gold  size  all  round  the  ring.  While  the  cover  is  falling  and  this 
contact  is  extending,  the  dye  solution  will  flow  forward  and  out 
in  a  wave.  When  contact  is  made  with  the  top  of  the  cell  all 
round,  take  any  blunt  instrument  and  press  the  cover  down  in 
the  middle  until  still  more  dye  flows  out.  While  this  is  being  done 
adjust  the  cover  on  the  ring  if  necessary,  by  the  direction  of  the 
pressure.  Quite  a  considerable  pressure  may  be  used,  cover  glasses 
are  very  flexible.  When  enough  dye  has  passed  out  to  leave  the 
cover  slightly  concave,  and  you  are  assured  that  the  adjustment 
•is  correct,  suddenly  remove  the  pressure.  Pneumatic  action  will  at 
once  take  place,  owing  to  the  resilience  of  the  indented  cover,  and 
the  edge  of  the  latter  will  adhere  so  tightly  to  the  gold-sized  ring 
•that  it  is  possible  to  wash  under  the  tap  with  a  full  stream  of 
water  at  once.  If  made  as  described,  the  cell  will  not  give  out. 
Light  filters  made  in  this  way  are  shown;  one  of  them  has  been 
made  and  used  for  more  than  20  years. 


MICROSCOPE    FOR  MEASURING    BRINELL  IMPRESSIONS. 

(Constructed  by  the   Societe  d'Optique  et  de  Mecanique 
de  Haute  Precision,  Paris.) 

The  apparatus  consists  of  two  principal  parts :  the  microscope 
properly  speaking,  and  the  limb  or  support. 

The  microscope  itself  comprises  a  mount  D,  carrying  below  an 
objective  0,  and  above  a  micrometer  P  and  an  eye-piece  Q.  The 
objective  is  aplanatic  and  achromatic,  and  yields  a  linear  magnifica- 
tion of  2.5.     The  micrometer  has  a  length  of  20  mm.,  which  is  divided 


ifcwvvv « Ezaaaji 


/^ 


into  160  equal  parts;  numbers  from  0  to  8  are  marked  every  20th 
division,  so  that  a  diameter  of  8  mm.  maximum  can  be  measured 
within  1/20  mm.  The  positive  eye-piece  imparts  to  the  whole  system 
a  total  magnification  of  21.  The  eye-piece  rests  in  a  small  mounting 
M,  which  can  glide  in  the  tube  D  for  adjusting  the  eye-piece  with 
respect  to  the  micrometer. 

217 


218  MEASURING    BRINELL    IMPRESSIONS 

The  support  A  consists  of  the  foot,  a  mount,  a  split  collar  provided 
with  a  clamping  screw  and  a  handle.  The  microscope  fits  with 
gentle  friction  into  the  collar,  so  as  to  be  definitely  adjustable  with 
respect  to  the  impression  to  be  measured;  it  is  then  fixed  in  that 
position  by  means  of  a  screw  C.  In  the  base  of  the  support  is 
encased  a  disc  of  fibre  B,  which  is  provided  with  a  central  aperture 
through  which  the  impression  to  be  measured  can  be  examined. 
This  fibre  washer,  as  shown  in  the  annexed  diagram  and  in  the  model, 
may  be  replaced  by  a  washer  of  suitable  shape,  so  as  to  be  adaptable 
to  the  piece  to  be  examined  by  the  microscope.  The  microscope 
weighs  0.390  kg.;  the  mahogany  case  weighs  0.650  kg. 


THE  DAVON   PATENT   MICRO-TELESCOPG   AND    SUPEK 
MICROSCOPE. 

Exhibited  by  F.  Davidson. 

This  apparatus  combines  in  standardised  and  instantly  inttr- 
changeable  iorm  the  functions  of  the  microscope,  telescope,  camera  and 
projecting  lantern  for  laboratory,  educational  and  industrial  purposes. 

The  principle  employed  is  the  utilisation  of  an  "  air  "  image  of  a 
more  or  less  distant  object  projected  to  the   plane  of  the  microscope 
stage  by  means  of  lens  attachments  which  are  inserted  into  the  "  Abbe 
rim  of  the  microscope  stand,   and  tiien  using  the  microscope  itself  as 
an  eye-piec8. 

Three  different  attachments  are  brought  into  requisition,  viz.  the 
long  focus  attachment,  the  short  focus  ditto,  and  a  micro  object  glass 
forms  the  third.  The  first  transforms  the  microscope  into  a  telescope 
with  a  range  of  vision  of  from  six  feet  to  infinity,  and  magnifications 
of  20  to  50  diameters.  The  second  is  used  for  objects  which,  by  reason 
of  their  size  or  shape,  cannot  be  examined  on  the  stage  of  the  micro- 
scope, such  as  minerals,  metal  fractures,  etc.,  the  visual  range  being 
from  three  feet  to  one  foot  from  the  stage  of  the  microscope  and 
magnification  from  30  to  90  diameters.  The  third  in  combination 
with  the  microscope  itself  forms  the  super  microscope.  Magnifica- 
tions of  from  75  to  150  diameters  with  working  distances  of  from 
four  to  two  inches  or  of  1,500  diameters  with  working  distance  of 
^  in,  are  characteristic  features. 

Either  attachment  may  be  used  for  photography.  With  the  first, 
photographs  have  been  taken  at  distances  of  6  feet  and  70  miles,  with 
the  same  combination;  with  the  second,  insects  at  from  18  ins.  to 
24  ins. ;  and  with  the  third  attachment,  photomicrography  of  a  wide 
variety  of  subjects  at  various  magnifications  from  1  to  3,000 
diameters  with  excellent  results. 

The  outstanding  feature  of  all  views  and  all  photographs  is  the  very 
great  "  depth  of  focus."  This  is  so  good  that  everything  is  shown  in 
apparent  stereoscopic  relief. 

The  principle  of  photography  with  either  attachment  is  the  same, 
and  consists  of  substituting  a  camera  for  the  body  tube  of  the  microscope 
and  virtually  using  a  microscope  objective  as  the  eye-piece.  No  long 
extension  camera  is  therefore  necessary,  exposures  are  shortened  and 
vibration  minimised  in  high  power  photomicrography.  Photographs 
of  Himalayan  Peaks  60  miles  away,  and  blood  corpuscles  at  a 
magnification  of  3,250  diameters  have  been  taken  in  a  ^  plate  without 
more  than  the  ordinary  extension. 

The  illuminant  is  arranged  in  an  optical  lantern  with  a  4  in. 
condenser  and  a  supplemental  condenser  in  a  mount  which  fits  the 
Abbe  "  rim  of  the  microscope.  For  projecting  light  on  to  a  more  or 
less  distant  object  the  4  in.  condenser  is  used  alone.  For  photomicro- 
graphy the  supplemental  condenser  only  is  used,  while  with  the  two 
in  combination  effective  micro-projection  may  be  done  without  any 
accessories. 

It  is  impossible  in  a  briefly  outlined  description  of  the  apparatus  to 
indicate  the  wide  variety  of  uses  to  which  the  apparatus  lends  itself, 
and  it  is  no  exaggeration  to  say  that  a  new  and  wider  field  of  observation 
and  utility  is  opened  up  in  many  directions. 

219 


DISCUSSION    AT    SHEFFIELD. 

Tuesday,  February  141  Ji.   iqio. 

At  a  meeting  of  the  Sheffield  Association  of  MetaUur- 
gists  and  Metalhirgical  ('hemists  held  at  the  Eoyal  Victoria 
Hotel,  Sheffield,  on  Tuesday,  February  :24th,  1920,  further 
discussion  took  place  on  those  papers  presented  at  the 
Symposium  at  London,  on  January  14th,  which  dealt  with 
the  use  of  the  microscope  in  Metallurgy  and  Metallography. 

The  meeting  was  held  in  co-operation  with  the 
Faraday  Society  and  it  was  attended  by  members  of  other 
local  bodies  and  by  the  members  of  the  local  sections  of 
the  Institute  of  Metals  and  the  Society  of  Chemical 
Industry. 

Mr.  J.  H,  S.  Dickenson,  President  of  the  Sheffield 
Association  of  Metallurgists  and  Metallurgical  Chemists, 
was  in  the  chair  and  he  presided  over  a  large  audience. 

Thp  Chairman,  having  explained  the  objects  of  the 
meeting,  called  upon  Dr.  F.  C.  Thompson,  Mr.  T.  G. 
Elliot,  Mr.   J.  H.  G.  Monypcnny  and  Mr.  F.  Atkinson 

to  introduce  briefly  the  papers  they  had  contributed  to  the 
Symposium  in  London.  Other  papers  were  distributed  in 
proof  form. 

Dr.  Thompson's  paper  was  entitled  ''  The  High 
Power  Photomicrography  of  Metals." 

Sir.  PiOBERT  Hadfield  and  Mr.  T.  (1.  Elliot's 
))aper  was  on  "  Photomicrographs  of  Steel  and  Iron 
Sections  at  High  Magnification," 

Mr.  J.  H.  G.  Monypenny's  paper  was  entitled 
"  Some  Notes  on  the  Metallurgical  Photomicroscope." 

The  i)aper  by  Mr.  L^lte  Aitchisok  and  jMr.  F. 
Atkinson  was  entitled  "  Metallurgical  Microscopes  and 
their  Development." 

220 


DISCUSSION   AT   SHEFFIELD  221 

Discussion. 

Dr.  W.  H.  Hatfield  did  not  think  that  there  was  any  point 
on  which  he  joined  serious  issue  with  the  authors  of  the  papers  read 
that  evening.  Mr.  Mony penny  said  that  many  people  used  the 
microscope  and  did  not  properly  understand  it.  That  was  so.  But 
looking  at  it  from  another  point  of  view,  there  were  people  who  regar- 
ded the  microscope  as  a  tool  and  looked  to  the  manufacturers  and  tho 
optician  to  further  extend  its  usefiihiess.  That  was  his  position,  and, 
generally  speaking,  the  position  most  metallurgical  investigators  would 
take  up.  From  that  point  of  view  one  could  tell  the  people  who 
were  making  a  speciality  of  the  microscope  what  the  metallurgist 
wanted.  We  might  first  of  all  tell  them  what  we  could  do.  From 
his  C'wn  metallurgical  experience  he  could  obtain  delightful  micro- 
photographs  under  ordinary  conditions,  and  with  ten  magnifications 
get  excellent  empirical  microphotographs.  This  was  also  the  case 
with  50,  100,  and  up  to  1,000  magnifications — excellent,  almost  per- 
fect definition  could  be  obtained.  Beyond  1,000  diameters,  how- 
ever, we  could  not  do  so,  and  that  was  an  essential  thing  to  put 
before  the  people  who  wore  out  to  assist  us  in  the  use  of  the  micro- 
scope. 

There  were  a  whole  series  of  problems  awaiting  adequate  solu- 
tion, including  the  recrystallisation  of  cold-worked  material,  and 
solutions  could  only  come  when  we  have  better  facilities  for  definite 
and  accurate  information  as  to  the  internal  architecture  of  the 
material  at  magnifications,  well  above  a  thousand.  We  had  produced 
very  pretty  photomicrographs  up  to  three  thousand  diameters — Sir 
Robert  Hadfield  has  produced  excellent  ones  up  to  eight  thousand — 
but  these  magnifications  did  not  give  us  much  more  information 
than  we  could  obtain  by  a.  clear  definite  picture  at  a  thousand.  If 
the  Symposium  had  brought  those  facts  before  the  notice  of  manu- 
facturers of  the  rnicroscope,  it  would  have  served  a  great  purpose 
to  metallurgists. 

Dr.  P.  Rogers  thought  that  the  theory  of  lens  design  had  been 
evolved  much  further  than  the  theoretical  side  of  metallurgy  itself, 
heretical  as  that  might  seem.  In  reference  to  the  high,  magnificatioji 
work  done  by  Sir  Robert  Hadfield  and  Mr.  Elliot,  he  emphasised 
that  w^hilst  magnifications  of  8  to  10  thousand  were  interesting  as 
pictures,  they  did  not  contain  any  more  detail ;  they  were,  in  fact, 
of  no  greater  value  than  enlargements.  Nevertheless,  he  welcomed 
this  high  magnification  as  a  progressive  step,  even  though  the  result 
as  regards  detail  w^as  a  negative  one. 

He  put  in  a  jjlea  to  metallurgists  that  they  should  make  their 
pho'tomicrographs  bigger;  if  they  were,  an  advantage  would  be 
gained.  Such  enlargements  were  better  understood  by  the  non-expert, 
even  if  perhajDS  as  a  record  they  were  not  so  good.  In  regard  to  fuie 
structures  in  the  alloy  steels — especially,  for  instance,  in  the  study  of 
temper  brittleness — he  would  welcome  anything  which  would  give 
further  resolution  of  detail.  This  information,  he  felt,  was  hidden 
away  from  them  just  at  the  limit ^ of  what  the  microscope  could  do. 
He  thought  the  microscope  would  ultimately  contribute  to  the  solution 
of  that  problem. 


222  DISCUSSION   AT   SHEFFIELD 

Mr.  J.  N.  Greenwood  referred  to  the  difiiculty  of  discussing 
the  many  points  at  issue.  First  of  all  there  was  the  perfecting  of 
the  design  of  the  optical  system  of  the  microscope  itself.  That  was 
definitely  a  question  to  be  tackled  by  the  opticians.  On  the  other 
hand  there  was  the  question  of  the  use  of  the  microscope,  and  in 
that  connection  there  were  very  great  improvements  necessary  in  a 
good  many  cases.  As  regards  the  question  of  vibration,  one  speaker 
suggested  that  the  people  who  supply  the  microscopes  should  supply 
some  means  of  getting  over  this  trouble.  But  the  trouble  could  only 
be  rectified  by  each  user  of  the  microscope  himself,  because  at  the 
various  laboratories  where  the  microscope  was  found  the  component 
vibrations  were  ditYerent.  Sometimes  it  was  the  vertical  which  pre- 
ponderated and  sometimes  the  horizontal,  and  the  question  of  the 
situation  and  the  type  of  machinery  close  by  had  to  be  gone  into 
before  the  vibration  should  be  overcome. 

As  regards  magnification,  a  good  many  metallurgists  were  ex- 
pecting more  from  the  microscope  than  was  likely  to  be  forthcoming 
in  the  near  future.  As  far  as  he  could  see,  unless  there  were  some 
absolutely  new  development  in  the  way  of  objectives  we  were  not 
likely  to  get  anything  approaching  the  increase  of  magnification 
and  resolving  power  which  some  metallurgists  desired.  Magnifica- 
tions of  1,500  were  now  quite  possible,  and  every  one  obtained  them 
more  or  less  easily.  But  to  get  at  the  bottom  of  such  problems  as 
})rittleness  and  cold  working  we  should  have  to  get  far  beyond  what 
we  had  been  doing  and  approach  molecular  dimensions :  even  at  t«n 
thousand  we  were  still  a  very  long  way  from  seeing  molecules.  It 
seemed  to  him  that  something  like  100,000  would  be  nearer 
the  mark,  and  he  could  not  see  how  from  the  present  system  and 
using  reflected  light  that  we  were  likely  to  get  anything  of  that  order. 
If  the  opticians  gave  us  10,000,  then  they  would  have  reached 
their  limits  with  the  present  methods.  He  thought  there  was  more 
prospect  of  getting  information  by  examining  other  physical  proper- 
ties apart  from  or  in  conjunction  with  the  microscope.  He  con- 
cluded by  saying  that  during  the  past  five  weeks  he  had  given  more 
time  and  study  to  the  microscope  than  he  had  during  the  last  five 
years,  so  that  in  fixing  attention  on  points  like  this,  such  dis- 
cussions are  invaluable,  because  few  people  had  time  to  gather 
iaformation  of  this  kind. 

Note  added  March  ^iJi. — It  has  been  suggested  that  I  am  pessi- 
mistic with  regard  to  possibilities  of  higher  magnification.  I  do 
not  wish  to  convey  the  idea  that  I  do  not  look  for  any  improvement 
in  magnification,  but  rather  than  in  the  two  problems  mentioned 
the  probable  improvements  in  the  microscope  will  scarcely  go  far 
enough.  On  the  other  hand,  there  is  an  enormous  field  of  utility 
for  magnifications  (with  correspondingly  high  revolving  power)  of 
the  order  of  5,000,  in  defining  the  structures  of  special  steels. 

Mr.  G.  R.  Bolsover  said  the  papers  resolved  themselves  into 
three  types.  A  certain  section  dealt  with  the  historical  side, 
another  with  the  utility  of  the  microscope,  aud  the  third  with  the 
microscope  as  an  instrument.  The  historical  side  was  dealt  with 
mainly  by  Sir  Kobert  Hadfield  in  two  papers.     He  suggested  that  in 


DISCUSSION   AT   SHEFFIELD  223 

dealing  with,  the  work  of  Sorby  that  account  could  with  advantage 
be  extended  to  include  not  only  the  work  of  Sorby,  but  his  life  as 
well.  In  the  case  of  a  man  who  had  done  fo  much  for  science  and 
incidentally  for  civilisation  as  a  whole,  we  should  have  a  permanent 
record  of  this  man's  birth,  training,  and  career  in  detail  up  to  his 
death,  apart  from  the  question  of  his  work. 

As  regards  the  microscope  as  an  instrument,  he  agreed  that  it 
was  the  optician's  affair.  There  were  many  comments  in  the  papers 
on  the  different  forms  of  microscopes.  His  experience  had  been  that 
there  were  many  microscopes  on  the  market  capable  of  giving 
excellent  results  when  properly  used,  but  they  were  not  made  to  meet 
the  particular  fads  of  individual  workers.  Results  were  dependent 
more  on  the  individual  than  upon  the  particular  type  used.  There 
was  in  use  in  his  laboratory  four  different  microscopes — one  Austrian, 
one  French,  one  modern,  and  one  ancient  British.  It  was  possible 
to  get  good  results  from  all  of  these.  The  two  oldest  were  the 
Austrian  and  the  old  British.  The  latter  was  perfect  in  almost 
every  respect,  whilst  the  stage  of  the  Austrian  could  be  moved 
through  quite  a  considerable  angle  in  the  direction  in  which  it  should 
be  perfectly  rigid.  He  did  not  think  they  need  fear  much  from 
the  superiority  of  the  Austiian  make  of  microscope. 

With  regard  to  stages,  he  uttered  a  word  of  warning — do  not 
get  a  levelling  stage.  It  was  a  distinct  advantage  to  have  an  up- 
and-down  movement  of  the  stage  in  order  to  avoid  altering  the 
light  sources  for  sections  of  varying  thickness.  On  the  question  of 
light  there  were  a  number  of  elaborate  schemes  for  lighting  for 
visual  work,  but  they  got  excellent  results  with  the  ordinary  electric 
bulb  with  the  interposition  of  a  ground  glass  screen.  One  could 
get  a  light  sufficient  to  show  all  detail,  and  it  did  not  tire  one's 
eyes.  As  to  the  source  of  light  for  photographic  work,  he  was 
rather  interested  in  some  of  the  papers  in  which  it  was  suggested 
that  the  arc  was  too  uncertain  a  source  and  suffered  from  flickering. 
They  had  tried  both  the  arc  and  the  ''  Pointolite,"  but  preferred 
the  arc,  and  got  excellent  results  from  it. 

Mr.  Atkinson  pointed  out  that  the  focussing  arrangement  for 
long  distance  work  was  one  that  required  a  great  deal  of  attention. 
At  times  a  considerable  extension  of  bellows  is  required  to  take  a 
photograph,  and  unless  a  really  good  apparatus  for  focussing  was 
available,  it  was  very  difficult  to  get  a  fine  adjustment. 

With  regard  to  higher  magnification,  one  direction  in  which  he 
anticipated  this  would  be  an  advantage  was  in  the  disproving  of 
certain  theories  at  present  in  vogue  with  regard  to  crystallisation, 
but  there  was  still  a  tremendous  field  to  be  explored  with  the  facili- 
ties which  were  now  available.  Another  difficulty  with  regard  to 
Mgher  magnifications  was  the  question  of  polishing  and  etching. 
With  the  present  method  of  polishing  it  was  practically  impossible 
to  get  a  plain  surface  to  examine,  and  when  one  came  to  etoh  the 
difiiculties  were  increased.  The  difficulties  were  really  enormous, 
and  until  they  were  removed  there  would  be  great  difficulty  in 
examining  steels,  let  alone  photographing  them  at  high  magnifica- 
tion. 


224  DISCUSSION   AT   SHEFFIELD 

The  Chairman :  Dr.  Tkompson  refers  to  the  Reicliert  microscope, 
and  says  very  good  results  can  be  obtained  when  the  disc  illuminator 
is  used  instead  of  the  pair  of  prisms  ordinarily  fitted.  Does  he 
know  whether  such  a  microscope  has  been  made  by  Reichert? 

Dr.  F.  C.  Thompson:  Benedicks  has  adapted  one  himself  for 
that  purpose 

The  Chairman :  Another  point  is  with  regard  to  vibration,  and 
regarding  this  I  would  point  out  that  Dr.  Rogers  would  not  use  a 
four-metres  extension  if  his  apparatus  was  established  near .  a  steam 
hammer.  Usually  in  a  works  it  is  necessary  to  use  a  short  extension 
for  this  reason. 

Dr.  F.  Rogers:  There  is  a  good  deal  in  that.  I  am  glad  that 
the  discussion  is  touching  on  the  question  of  vibration.  It  has 
been  suggested  to  me  that  the  whole  apparatus  should  be  afloat  on 
water  or  oil.  It  seems  to  me  a  rather  good  idea,  but  I  don't  sug- 
gest that  you  should  have  to  swim  to  it.  I  have  not  worked  out  th.© 
detail,  but  I  think  the  problem  will  be  ultimately  solved  in  that 
way,  perhaps  combined  with  springs  or  india-rubber  moorings. 

Dr.  W.  H.  Hatfield:  Arising  out  of  this  discussion  there  is 
one  thing  I  should  like  to  say  with  regard  to  my  experience.  I 
have  done  a  great  deal  of  photomicrography,  and  for  one  period 
of  something  like  six  or  seven  years  I  used  a  Watson  microscope. 
Now,  that  microscope  cost  about  50  to  55  guineas,  whereas  the  Zeiss 
cost  about  100  guineas.  I  produced  well-nigh  perfect  pictures  at 
1,000  and  slightly  over.  In  fact,  the  work  v/as  equal  to  that  given 
by  the  Zeiss,  and  I  shall  be  glad  to  show  anyone  the  slides.  I 
mention  this  because  so  much  has  been  said  about  the  German 
manufactured  article  being  better  than  the  British,  and  I  think  it 
is  oniy  fair  that  we  should  put  that  on  record. 

Mr.  L.  Dufty  drew  attention  to  the  different  magnifications 
given  in  the  various  papers,  and  suggested  that  it  would  be  a  great 
improvement  if  standard  magnifications  were  adopted.  Another 
thing  that  should  be  stated  in  the  papers  was  what  objectives  and 
eye-pieces  were  used.  It  would  be  a  great  advantage  if  these  were 
given   when  stating  the  magnifications. 

The  Chairman :  The  matter  of  standard  magnifications  is  men- 
tioned in  Sir  Robert  Iladfield's  Introductory  Address.  The  Ameri- 
can Society  for  Testing  ]\laterials  has  issued  a  list  of  standard  magni- 
fications which,  as  far  as  my  recollection  goes,  runs  in  fifties.  It  is 
open  to  every  investigator  to  work  to  simple,  round  figure,  magni- 
fications. 

Mr.  L.  Dufty  :  Yes,  but  you  will  see  investigators  often  work  in 
anything  except  round  figures. 


DISCUSSION   AT   SHEFFIELD  225 

The  Chairman :  I  am  sometimes  ashamed  of  some  which  I  see 
hanging  in  my  laboratory  which  are  marked  "  x  117.5,"  but  these 
were  taken  18  years  ago,  and  we  have  noM^  for  many  years  worked 
to  a  few  fixed  round-figure  magnifications. 

Dr.  T.  Baker:  Those  of  us  who  have  had  the  opportunity  of 
examining  the  work  of  old  masters  in  the  art  of  photomicrography 
I  think  will  agree  that  they,  with  imperfect  apparatus,  turned  out 
much  morp  satisfactory  work  than  many  of  us  to-day  do  with  a 
much  more  perfect  equipment.  A  great  deal  depends  on  the 
operator,  and  a  closer  study  of  the  construction  of  the  microscope 
would  assist  him  in  avoiding  the  pitfalls  into  which  a  good  many 
metallurgical  microscopists  are  apt  to  fall.  There  is  a  great  tendency 
to  make  the  metallurgical  microscope  too  complex;  amongst  the 
fittings  to  be  avoided  are  levelling  stages  and  centering  nose-pieces  ; 
a  centering  stage  is  much  better  than  the  latter,  since  it  can  be 
much  more  substantially  constructed. 

As  regards  objectives,  apochromats  are  without  doubt  a  valuable 
asset  to  the  skilled  worker,  but  how  many  can  distinguish  between 
the  image  formed  by  a  good  achromatic  and  that  given  by  an  apo- 
chromatic  objective,  without  the  assistance  of  the  inscription  on 
the  mount;  then,  again,  by  far  the  greater  part  of  the  work  of  a 
laboratory  does  not  call  for  the  use  of  apochromats. 

As  regards  magnification,  it  is  generally  stated  in  the  standard 
works  on  the  subject  that  little  if  anything  is  gained  by  using 
magnifications  greater  than  1,000  times  the  numerical  aperture  of  the 
objective,  so  that  until  the  resofving  powers  of  objectives  are  in- 
creased there  seems  to  be  little  advantage  in  pushing  magnifications 
much  beyond  1,500  diameters. 

As  an  illuminant  the  speaker  prefers  the  direct  current  arc  to 
the  ''  Pointolite  "  lamp,  in  spite  of  the  fact  that  the  latter  has 
several  points  in  its  favour,  such  as  steadiness  and  constancy  of 
brilliancy.  The  prism  form  of  vertical  illuminator  appears  to  have 
fallen  into  bad  repute;  the  speaker,  however,  prefers  it  to  the 
cover-glass  type,  in  spite  of  the  fact  that  it  reduces  the  numerical 
aperture  of  the  object  by  one-half  in  one  direction,  a  weakness  which 
is  not  such  a  serious  matter  as  many  try  to  make  out, 

Mr.  H.  Wrighton  said  he  had  considerably  reduced  the  flare  in  a 
4  mm.  .95  N.A.  objective  by  blacking  the  inside  of  the  mounts 
near  the  front  of  the  objective,  which  were  brightly  polished.  He 
produced  further  photographs  of  a  very  fine  pearlitic  structure,  and 
said  he  considered  that,  taken  at  8,000  magnifications,  was  better 
than  the  corresponding  photograph  of  the  same  field  at  x  1,500,  as 
the  details  of  the  structure  could  be  more  plainly  seen.  A  Zeiss 
X  12  compensating  eye-piece  was  used  in  obtaining  the  photoprraphs 
at  8,000  magnifications.  He  submitted  photographs  of  a  long  distance 
fine  focussing  adjustment  he  had  fitted  to  his  Zeiss-Martens  hori- 
zontal microscope,  and  found  to  be  quite  satisfactory, 

Mr.  J.  H.  G.  Monypenny,  referring  to  the  capabilities  of  differ- 
ent stands,  said  he  had  never  met  one  to  equal  the  large  "  Works  " 
model  made  by  Watson.  He  had  used  one  of  these  stands  fifteen 
years,  and  it  was  still  in  perfect  condii^ion.     He  had  tried  a  number 


226  DISCUSSION  AT   SHEFFIELD 

of  other  stands,  including  the  Zeiss-Martens,  but  had  not  seen  one 
to  equal  the  Watson.  Opinions  differed  as  to  the  relative  wearing 
qualities  of  British  and  German  stands;  there  was  no  doubt,  however, 
that  the  better  quality  British  stands  were  good  instruments,  and 
would  stand  a  great  amount  of  use;  at  the  same  time  they  could 
be  improved  by  using  more  suitable  kinda  of  metal  for  the  moving 
parts,  such  as  pinions  and  racks. 

With  regard  to  objectives,  the  English  achromatic  lenses  worked 
perfectly,  providing  they  were  used  with  yellow-green  light,  and 
with  low  and  medium  powers  one  could  obtain  results  comparable 
with  those  given  by  Zeiss  apochromats.  For  low  power  work  they 
had  the  advantage'  of  possessing  a  much  flatter  field  than  the  apo- 
chromats, but  they  did  not  work  well  with  blue-violet  light.  Some 
of  the  new  apoohromats  made  by  Watson  and  Swift  were,  he  believed, 
very  good  lenses,  but  he  had  not  tried  them.  For  the  highest  powers 
the  apochromat  was  much  superior  to  the  achromat,  though  good 
results  could  be  obtained  with  the  latter. 

Several  remarks  were  made  about  fine  focussing  arrangements. 
Nearly  all  his  work  had  been  done  with  a  vertical  camera,  and,  being 
endowed  with  a  rather  long  arm,  he  had  not  needed  any  extended 
arrangement  for  focussing.  The  arrangements  he  had  seen  have  been 
rather  a  nuisance,  and  probably  the  worst  was  the  one  fitted  to  the 
Zeiss-Martens  stand. 

For  veiy  low  power  work  he  did  not  think  any  ordinary  type  of 
microscopic  objective  suitable  if  one  required  a  large  field.  Some 
type  similar  to  the  Zeiss  projectioij  lens  was  much  better;  with  such 
a  lens  one  could  easily  obtain  a  field  up  to  ^   in,   diameter. 

With  regard  to  the  use  of  prism  or  disc  illuminators,  in  spite 
of  what  had  been  said,  he  believed  the  disc  was  very  much  better 
than  the  prism  for  high  power  work.  Providing  the  structure  was 
switable  and  the  detail  in  the  section  arranged  in  the  right  direction 
(that  is,  with  respect  to  the  prism),  one  could  obtain  very  good 
photographs  with  the  prism  illuminator,  but  in  most  specimens,  for 
example,  of  pearlite,  the  laminae  were  arranged  at  different  angles 
in  various  part  of  the  field,  and  it  was  impossible  to  arrange  it  so 
that  each  set  of  laminae  was  in  the  best  position  to  be  resolved.  For 
low  power  work  there  was  no  doubt  that  the  prism  was  superior 
to  many  individual  discs  on  the  market  for  the  reasons  given  in 
his  paper. 

Reference  was  made  in  one  of  the  papers  to  the  impossibility  of 
obtaining  good  contrast  with  medium  power  dry  objectives,  such,  as 
the  l/6th  inch,  owing  to  flare  due  to  reflection  of  the  incident  light 
at  the  front  surface  of  the  objective.  He  had  used  a  Zeiss  4  mm. 
apochromat  for  some  years  for  metallurgical  work,  and  found  it 
quite  easy  to  obtain  sufficient  contrast.  It  would  be  very  incon- 
venient to  have  to  use  an  immersion  lens  for  such  powers. 

Several  references  had  been  made  during  the  discussion  to  the 
various  types  of  metallurgical  stands.  Many  of  the  new  fancy  stands 
were  no  improvement  on  the  old  type,  and  very  often  they  were 
much  worse.  In  a  metallurgical  stand,  the  stage  should  have  a 
coarse  adjustment,  but  the  fine  adjustment  should  be  on  the  tube. 
In  any  case,  the  milled  head  for  the  fine  adjustment  should  not  be 
fixed  to  a  movable  part  of  the  stand   (such  as  the  stage),   as,  if  so, 


DISCUSSION   AT   SHEFFIELD  227 

tlie  flexure  due  to  the  pressure  of  the  hand  might  be  sufficient  to 
affect  the  focus  of  a  high  power  objective.  In  this  respect  it  might 
be  mentioned  that  when  using  a  2  mm.  immersion  objective  of 
N.A.  1.40  a  nioveinent  of  ~J-  of  an  inch  along  the  optical  axis 
was  sufficient  toi  put  the  field  out  of  focus. 

With,  regard  to  Dr.  Thompson's  remarks  on  the  halo  produced 
round  the  fine  detail  in  photographs  at  very  high  magnifications, 
while  agreeing  that  such  halos  were  produced,  he  thought  their 
width  was  rather  less  than  stated  by  Dr.  Thompson. 

Mr.  Birch  pointed  out  that  by  the  use  of  different  screens 
photographs  were  obtained  which  seemed  to  represent  two  totally 
different  things.  The  whole  process  of  photography  should  be  under- 
stood besides  the  optical  system. 

Dr.  W.  H.  Hatfield  said  that  with  regard  to  the  standardisation 
of  magnifications  in  his  laboratory,  they  had  found  it  helpful  to 
standardise  to  10,  50,  100,  500,  and  1,000  diameters.  It  would 
be  very  helpful  in  studying  the  w^ork  of  other  people  if  the  photo- 
graphs were  of  the  same  magnifications. 

Mr.  J.  N.  Greenwood:  The  question  of  the  size  of  reproduction 
also  arises. 

Dr.  W.  H.  Hatfield:  I  suggest  that  the  matter  is  worthy  of 
consideration. 

The  Chairman :  Such  standards  have  been  laid  down  in  America. 

Mr.  T.  G.  Elliot:  Sir  Kobert  Hadfield  has  taken  a  great  interest 
in  the  question  of  standard  magnifications  for  photomicrographs,  and 
he  long  ago  decided  to  use  standard  magnifications  in  his  own  re- 
search laboratory.  He  took  a  practical  interest  in  the  work  of  the 
Committee  of  the  "American  Society  for  Testing  Materials,"  which 
was  responsible  for  drawing  up  the  report  on  "  Magnification  Scales 
for  Micrographs,"  which  has  already  been  mentioned  this  evening , 
and  several  of  his  suggestions  were  adopted  and  are  included  in  the 
revised  report,  published  in  June,  1918.  In  that  year,  too,  Sir 
Robert  endeavoured  to  get  the  British  Engineering  Standards  Com- 
mittee to  take  up  the  subject  in  this  country.  After  due  con- 
sideration, however,  they  decided  against  it,  because  they  felt  it 
w^ould  be  impossible,  at  that  time,  to  standardise  the  lenses  to  be  used 
in  obtaining  the  magnifications,  without  which  the  standardisation 
of  magnifications  would  be  useless.  It  was  also  thought  that  this 
matter  and  the  related  one  of  the  full-sized  reproduction  of  photo- 
micrographs might  well  be  left  to  the  Publications  Committees  of 
the  various  Societies  interested. 

The  Chairman  said  that  in  his  laboratoiy  they  had  adopted  100, 
250,  and  750  as  standard  magnifications. 

Dr.  F.  Rogers  advocated  the  adoption  of  round-number  standard 
magnifications  for  reproduction  and  report  purposes. 


228  DISCUSSION   AT   SHEFFIELD 

Dr.  F.  C.  Thompson  said  it  was  at  times  very  difficult  to  confine 
oneself  to  given  magnifications.  The  Institute  of  Metals  had  brought 
out  a  list  of  magnifications  seven  or  eight  years  ago,  and  authors 
of  papers  were  requested  to  confine  themselves  to  those  standards, 
but  no  attempt  appears  to  have  been  made  by  the  Publication  Com- 
mittee to  enforce  these,  and  he  did  not  think  they  were  being 
observed  now. 

With  regard  to  stands,  in  his  experience  the  English  stand  was 
absolutely  unsurpassed.  They  had  some  very  old  Beck  stands  at  the 
University  which  had  been  subjected  to  extremely  hard  work,  and 
even  now  those  stands  were  in  excellent  condition.  The  samei  applied 
to  geological  and  other  stands  by  Watson's,  which  were  being  sub- 
jected  to  equally  hard  work.  They  appeared  to  be  a  distinct  im- 
provement on  anything  that  foreign  countries  could  supply. 

With  regard  to  objectives,  the  position  was  not  quite  the  same. 
For  lower  power  English  objectives  were  most  admirable,  but  he 
agreed  with  Mr.  Monyjoenny  that  above  one-sixth  the  Zeiss  was 
much  better.  Dealing  with  illumination,  the  arc  lamp,  if  it  was 
working  well,  did  quite  admirably.  Small  arcs,  however,  were  very 
unsatisfactory.  If  it  were  not  for  the  increased  amount  of  atten- 
tion required,  the  ideal  illuminant  was  the  lime  light.  One  got 
large  area  of  illumination  of  high  actinic  value  if  one  took  the 
necessary  trouble. 

A  Member  remarked  that  if  a  standard  for  magnifications  was 
fixed  there  should  also  be  a  standard  of  objectives  for  each  magnifi- 
cation. 

The  Chairman :  On  this  matter  of  standard  magnification  this 
Association  might  very  well  have  the  views  of  all  our  members  using 
microscopes  ascertained   and  a  memorandum   prepared, 

Mr.  F.  S.  Spiers  said  that  an  important  factor  in  determining 
the  size  of  reproductions  was  that  of  cost.  Anyhow,  that  placed  an 
added  difficulty  in  the  way  of  standardisation.  With  the  permission 
of  the  meeting  he  would  like  to  bring  up  the  subject  before  the  Council 
of  the  Faraday  Society,  and  perhaps  some  steps  might  be  taken 
in  the  direction  of  standardisation.  There  were  one  or  two  things 
mentioned  in  the  discussion  in  London  which  he  thought  it  of 
interest  to  bring  forward,  notably  the  suggestion  to  form  a  standing 
committee  to  undertake  proper  tests  of  objectives  now  being  manu- 
factured. It  was  hoped  that  would  settle  once  and  for  all  the  ques- 
tion, of  the   merit   of   British  objectives. 

The  Chairman :  It  appears  that  members  of  our  Association 
are  not  quite  unanimous  on  certain  points.  In  the  first  place,  as 
regards  the  question  of  disc  versus  prism  illumination.  I  may  have 
been"  unfortunate  in  my  experience  of  prisms,  but  I  always  find 
that  I  can  get  better  photographs  with  even  ordinary  covered  glasses 
than  from  any  prism,  and,  judging  not  only  by  my  own  results,  but  by 
those  of  my  friends,  I  must  say  the  glass  disc  illuminator  is  much 
to  be  preferred  to  the  prism.  The  other  point  on  which  there  is 
a  sharp  difference  of  opinion  is  with  regard  to  illuminants.      I  have 


DISCUSSION   AT   SHEFFIELD  229 

found  the  "  Pointolite  "  extremely  useful  and,  if  properly  used,  it 
gives  excellent  results.  It  gives  a  very  steady  and  strong  illumina- 
tion, and  may  be  used  for  everything  except  screen  projection,  when 
the  greater  power  of  the  arc  lamp  is  required. 

I  think  rather  too  much  has  been  said  to-night  with  regard  to 
photomicrography,  and  too  little  about  the  use  of  the  microscope 
for  purposes  of  examination  and  study,  especially  at  high  powers. 
Actual  research  work  is  not  done  by  examining  photomicrographs, 
but  by  prolonged  visual  inspection  of  structures  under  the  micro- 
scope. It  is  rather  the  tendency  nowadays  to  take  a  photograph 
and  hardly  look  at  the  specimen  at  all;  but,  after  all,  photographs 
are  only  imperfect  illustrations  necessary  for  reports  and  publications. 

As  regards  the  present  indifferent  construction  of  microscopes, 
I  consider  that  it  is  for  the  metallurgical  engineer,  who  should 
know  what  he  really  requires,  to  design  the  mechanical  details  of 
his  microscope,  leaving  the  optician  only  to  deal  with  the  optical 
system.  Further,  with  regard  to  existing  microscopes,  I  quite  agree 
that  English  microscopes  have  been  very  unfairly  condemned  in 
comparison  with  Continental  instruments,  although  as  regards  objec- 
tives English  makers  do  not  seem  to  be  able  to  keep  up  to  the  same 
standard  of  excellence  as  Continental  makers,  but  they  occasionally 
turn  out  lenses  which  are  as  good  as  can  be  obtained  anywhere. 
Then,  as  regards  enlarged  photomicrographs,  I  must  say  that  I  fail 
to  see  any  point  in  enormously  high  magnifications  obtained  by  this 
means.  Such  photomicrographs  at,  say,  5,000  diameters  magnifica- 
tion, give  no  information  which  cannot  be  obtained  from  a  photo- 
micrograph at  1,000  diameters. 

Dr.  F.  Rogers  :  As  an  enlarged  photograph  it  is  of  some  use. 

The  Chairman :  Yes,  as  a  picture  for  hanging  on  a  wall.  You 
can,  of  course,  go  up  to  enormous  enlargements  by  the  use  of  a 
lantern,  but  this  only  assists  by  permitting  more  people  to  see  the 
photograph  at  one  time. 

Mr.  T.  G.  Elliot:  A  photograph  taken  at  5,000  magnifications 
has  this  advantage  over  an  enlargement,  that  before  taking  the 
photograph,  you  select  your  field  at  this  magnification,  and,  as  we 
say  on  page  5  of  our  paper,  "  we  consider  this  an  important  point." 
We  quite  agree  with  Mr.  Dickenson  and  other  speakers  who  have 
criticised  the  use  of  very  high  magnifications,  that  nothing  new  has 
been  learnt  from  them  ;  although  we  submit  that  inasmuch  as  they 
do  enable  one  to  see  the  details  of  the  structure  easier,  they  have 
this  important  advantage  over  photographs  taken  at  lower  magnifi- 
cation. It  was  partly  because  Sir  Robert  Hadfield  believed  that 
we  had  got  as  far  as  was  practicable  with  the  apparatus  available, 
that  he  suggested  a  Symposium  on  the  Microscope,  in  the  hope  that 
it  would  focus  attention  on  this  point  and  lead  to  increased  effort 
to  obtain  apparatus  which  would  open  up  new  fields  of  investigation. 

Dr.  F.  C.  Thompson,  replying  to  the  discussion,  said  that  as 
the  wave-length  of  light  decreased  the  resolving  power  was  increased. 
TJp  to  the  present  ultra  violet  lisfht  had  been  unsatisfactory  with 
metallurgical  specimens,   though   there   was    no  obvious   reason  why 


230  DISCUSSION   AT   SHEFFIELD 

this  should  be  so.  With  regard  to  Mr.  Monypenny's  criticism  of 
the  diameter  of  the  halos,  he  had  formed  his  conclusions  on  the 
ordinary  laws  of  optics,  and  there  was  no  very  obvious  reason  for 
departing  from  it. 

Mr.  J.  H.  G.  Monypenny  said  he  was  quite  in  accord  with  what 
had  been  said  with  regard  to  magnification,  that  the  limit  is  reached 
at  1,500  diameters.  The  only  advantage  in  photographing  above 
1,500  (apart  from  photographs  for  reproduction  purposes — in  which 
case  enlargement  is  sometimes  desirable),  might  be  in  the  case  of 
a  man  whose  vision  was  not  as  good  as  it  might  be,  or  who  did 
not  wish  to  tire  his  eyes  examining  every  detail. 

The  Chairman,  in  concluding  the  meeting,  said  :  We  are  very 
glad  to  have  had  the  opportunity  of  discussing  in  Sheffield  the  papers, 
on  microscopy  which  were  recently  read  before  the  associatie-d  Socie- 
ties in  London,  and  I  think  I  may  say  that  this  Association  is 
grateful  to  Sir  Robert  Hadfield  for  making  the  suggestion  that  such 
a  further  discussion  should  take  place.  If,  and  when,  the  Faraday 
Society  has  another  Symposium  on  some  other  subject,  this  Associa- 
tion will,  I  am  sure,  be  pleased  to  arrange  for  another  joint  local 
meeting  on  the  lines  of  that  held  to-night. 


ADJOUKNED   DISCUSSION    IN    LONDON. 

April  2ist,   1920. 

The  Koyal  Microscopical  Society  held  a  special 
meeting  on  April  21st,  1920,  in  the  Rooms  of  the  Society 
at  20,  Hanover  Square,  London,  W.,  in  conjunction  with 
the  Optical  Society  and  the  Faraday  Society,  to  discuss  the 
papers  presented  to  the  Symposium  which  dealt  with  the 
"  Mechanical  Design  and  Optics  of  the  Microscope." 

Professor  John  Eyre,  President  of  the  Eoyal  Micro- 
scopical Society,  who  was  in  the  Chair  during  the  first  part, 
of    the    proceedings,    opened    the    Discussion    with    the 
following  remarks  : — 

The  object  of  our  meeting  this  evening  is  not  to  initiate  a  fresh 
discussion  on  the  microscope,  but  to  continue  the  work  which  was 
commenced  at  the  Symposium  held  in  January  last.  The  volume 
of  communications  which  was  simply  poured  upon  the  Symposium 
was  so  great  that  it  was  impossible  to  discuss  more  than  a  very  few 
of  them,  and,  indeed,  many  papers  were  only  presented  in  abstract, 
but  in  order  to  correlate  the  views  of  all  the  workers  in  this  branch 
of  science,  we  are  arranging  a  series  of  short  meetings  in  which 
spe-cially  selected  papers  can  be  discussed,  and  the  results  of  the 
discussion  recorded  for  publication.  During  the  course  of  the  evening 
my  two  confreres,  Sir  Robert  Hadfield,  President  of  the  Faraday 
Society,  and  Mr.  R.  S.  "Whipple,  President  of  the  Optical  Society, 
will  each  take  the  Chair  for  a  period,  in  order  that  the  members  of 
their  Societies  may  feel  that  they  are  adequately  represented. 

The  Chairman  then  called  upon  Mr.  J.  E.  Barnard  to  give  a 
General  Survey  of  the  subject  (see  page  37),  after  which  abstracts 
of  the  following  papers,  read  at  the  original  meeting,  were  presented" 
by  their  respective  authors  : 

THE  MECHANICAL  DESIGN  OF  THE  MICROSCOPE. 

(a)  General. 

Professor  F.  J.   Cheshire,  C.B.E.,    "  The  Mechanical  Design 
of  Microscopes." 

Mr.  Conrad  Beck,  C.B.E.,  ''  The  Standard  Microscope." 

Mr.  F.  W.  Watson  Baker,    "  Progress  in  Microscopy   from  a 
Manufacturer's  Point  of  View." 

Mr.  Powell  Swift,   "A  New  Research  Microscope." 

231 


232  ADJOURNED    DISCUSSION    IN    LONDON 

(b)  Metallurgical . 

Dr.  W.  Rosenhain,  F.R.S.,   "  The  Metallurgical  Microscope." 

Professor  Cecil  H.    Desch,    D.Sc,    "  The  Construction  and 
Design  of  Metallurgical  Microscopes." 

Mr.  E.  F.  Law,  "  The  Microscope  in  Metallurgical  Research." 
Mr.  H.   M.    Sayers,    "  Illumination  in  Micro-metallography." 


(c)  Petrolo(/icaI. 

Dr.    J.    W.    Evans,    F.R.S.,    ''  The  Requirements   of  a  Petro- 
logical  Microscope." 


Sir  Robert  Hadfield,  F.R.S,,  in  taking  the  Chair  during 
the  reading  of  the  metalhirgical  papers,  said  : 

I  do  not  intend  to  take  up  much  of  your  time,  but  should  like 
to  say  in  a  few  words  how  very  gratified  I  feel  to  see  this  important 
gathering  continuing  the  work  we  tried  to  do  a  couple  of  months 
ago.  We  then  had  something  like  40  papers  presented,  and  as,  of 
course,  it  was  quite  impossible  to  do  more  than  touch  upon  the  fringe 
of  the  discussion  of  them,  I  may  also  add  that  out  of  that  large 
gathering  in  the  Rooms  of  the  Royal  Society  we  have  had  a  con- 
tinuation of  the  same  work  in  the  cities  of  Sheffield  and  Glasgow. 
That  will  show  you  that  we  did  really  stir  up  not  only  the  metro- 
polis, but  also  the  north  and  the  far  north.  As  I  am  taking  the 
Chair  during  the  reading  of  the  papers  in  the  metallurgical  section, 
I  would  like  to  say  how  very  important  we  find  the  microscope  as 
regards  metallurgical  operations  and  investigations.  My  friend  Mr. 
Barnard  has  said  that  we  do  not  think  sufficiently  of  resolution  and 
that  we  are  rather  too  fond  of  magnification.  I  still  have  a  little 
feeling  for  magnification,  but  cannot  help  thinking  that  we  shall, 
aided  by  resolution — the  double  resolution  of  the  microscope  and 
our  own  resolution — find  out  improved  methods  of  handling  steel. 
That  is  a  matter  I  am  specially  interested  in.  The  more  one  studies 
the  structure  of  iron  and  steel,  the  more  fascinating  it  becomes.  To 
use  an  illustration  in  which  I  have  been  concerned  very  much  during 
the  war,  i.e.,  the  production  of  the  large  calibre  armour  piercing 
shell,  we  could  not  really  have  obtained  a  shell  of  the  requisite 
quality  without  the  use  of  the  microscope.  When  one  considers 
that  the  18-inch  gun  carried  a  projectile  with  a  muzzle  energy  of 
150,000  foot-tons,  oii.e  can  imagine  the  tremendous  stresses  which 
occur  when  that  shell  is  suddenly  brought  to  rest  by  the  armour 
attacked,  and  yet  it  must  not  break.  Out  of  those  war  reF^earches  are 
proceeding  further  investigations  which  will  apply  that  information  to 
the  arts  of  peace,  and  I  do  not  think  it  will  be  found  that  we  have 
wasted  our  time.  W^e  in  England  were  not  behind,  but  we  wanted 
stimulating  a  little,  and  a  great  deal  of  investigation  work  was 
carried  out  during  the  war  which  would  not<  have  been  done  other- 
wise, because  in  times  of  peace  the  money  could  not  be  found. 


ADJOURNED    DISCUSSION    IN    LONDON  233 

Discussion. 

Commander  M.  A.  Ainslie,  R.N.:  With  regard  to  design,  the 
principle  of  the  optical  bench  seems  to  me  exactly  the  principle  needed 
in  order  that  you  may  build  up  in  bits  the  apparatus  you  want 
for  any  particular  research,  so  that  everything  may  fall  naturally 
into  alignment.  Each  piece  of  apparatus  should  be  on  a  separate 
saddle  of  its  own.  I  would  even  have  the  eye-piece  on  a  separate 
saddle,  with  a  separate  coarse  adjustment  of  its  own;  this  may  sound 
revolutionary,  but  I  believe  it  to  be  perfectly  sound.  Then,  again, 
I  think  we  ought  to  have  a  longer  range  to  the  draw-tube ;  as  a 
rule,  it  is  quite  insufhcient,  especially  when  high  power  dry  objec- 
tives are  in  use.  An  ordinary  dry  3  mm.  objective  requires  a  change 
of  about  20  mm.  in  the  tube-length  to  compensate  for  a  change  of 
.01  mm.  in  the  thickness  of  the  cover  glass;  and  although  objec- 
tives of  lower  power  are  less  sensitive,  objectives  of  low  power  and 
large  aperture  are  not  very  easy  to  obtain. 

With  regard  to  the  size  of  illuminant  required  in  photomicro- 
graphy, whether  of  metals  or  of  other  objects,  this  is  settled  by  a 
very  simple  relation.  If  d  be  the  diameter  of  the  light-source,  and 
B  that  of  the  illuminated  area  on  the  object  slide,  and  if  B  be  the 


^° 


angle  made  with  the  axis  of  the  extreme  ray  entering  the  optical 
system  and  0  that  of  the  extreme  ray  falling  on  the  object,  the  latter 
being  supposed  in  a  medium  of  refractive  index  //,  then  we  always 
have 

d  sin  0  =  /J-  D  sin  0, 
which  is,  of  course,  merely  the  well-known  ''  optical  sine  law  "  ;  it 
really  amounts  to  saying  that  the  product  of  the  diameter  of  the 
light-source  into  the  N.A.  of  the  collecting  lens  is  equal  to  the  dia- 
meter of  the  circle  of  illumination  on  the  object,  multiplied  by  the 
N.A.  of  the  condenser.  You  cannot  get  away  from  this  relation; 
it  settles  once  for  all  the  diameter  of  the  illuminated  field,  and  it  is 
true  for  any  optical  system  whatever  between  the  light-source  and 
the  condenser. 

If  you  are  going  to  use  a  metal  filament  lamp,  you  are  con- 
fronted with  one  of  two  things;  either  you  are  going  to  project 
an  image  of  the  filament  on  your  object,  or  else  you  are  going  to 
project  this  image  into  the  plane  of  the  objective  aperture,  filling 
it  irregularly;  a  state  of  things  which  Professor  Conrady  long  ago 
show^ed  to  be  incorrect.  The  diameter  of  the  filament  is  far  too 
small,  having  regard  to  the  relation  I  mentioned  just  now;  and 
of  course  one  does  not  want  an  imago  of  the  filament  on  the  photo- 
graph. 

With  regard  to  the  intensity  of  the  arc,  what  decides  the  ex- 
posure is  the  intrinsic  brilliancy  and  not  the  total  power  of  the 
arc.     As  to  the  heating  effect,  I  have  used  a  25  ampere  arc  within 


234  ADJOURNED    DISCUSSION    IN    LONDON 

IJ  inch,  of  one  of  the  solid  glass  rods  supplied  by  Messrs,  Beck,  for 
half  an  hour  at  a  time,  without  the  slight-est  damage  to  the  glass, 
and  I  am  inclined  to  think  that  this  "  bogey  "  of  the  danger  to 
your  collecting  lens  is  somewhat  over-rated. 

Mr.  C.  Beck:  Has  Commander  Ainslie  tested  the  amount  cf 
light  lost  by  absorption  from  glass  to  glass.     Is  it  75  per  cent.  ? 

Commander  Ainslie :  Yes,  of  course,  a  great  deal  of  light  is 
lost.  It  was  a  question  of  the  capability  of  the  glass  to  withstand 
heat.  It  is  a  question  of  the  size  of  the  illuminant.  I  have  seen 
a  piece  of  ground  glass  as  the  source  of  illumination  instead  of  the 
crater  of  the  arc  itself. 

Mr.  Maurice  Blood :  You  can  use  a  large  collecting  lens. 

Commander  Ainslie :  But  you  will  not  get  more  light,  because 
it  is  the  intrinsic  brilliancy  of  the  light  that  counts. 

Dr.  R.  Clay:  The  feature  that  pleases  me  most  in  the  micro- 
scopes that  Mr.  Beck  has  show^n  is  the  provision  that  he  has  made 
by  which  one  can  start  with  a  simple  form  and  gradually  build  it 
up.  I  have  been  advocating  this  for  some  time,  and  I  am  very  glad 
to  see  it  is  accomplished  here.  That  a  student  who  has  not  too  much 
money  can  commence  with  an  inexpensive  instrument  and  add  to  it 
as  he  goes  along,  and  as  he  feels  the  necessity  for  and  understands 
the  use  of  improved  apparatus,  is  a  very  great  advantage. 

I  was  very  much  interested  in  Commander  Ainslie's  formula 
connecting  the  area  illuminated  by  a  substage  condenser  and  the 
aperture  of  the  condenser.  I  think  it  is  one  of  the  most  important 
things  that  has  been  brought  forward  during  this  Symposium,  because 
there  is  quite  a  lot  of  nonsense  talked  about  the  illumination  of 
microscope  objects,  and  that  formula  puts  the  whole  in  a  nutshell. 
I  was  also  interested  in  the  paper  on  the  illumination  of  metallurgical 
specimens,  as  I  think  it  is  possible  with  a  prism  that  I  devised  some 
time  ago  for  another  purpose  to. give  the  50  per  cent,  illumination 
that  has  been  asked  for  in  that  paper. 

Mr.  W.  R.  Traviss:  I  should  like  to  mention  that  it  is  over  35 
years  ago  since  I  introduced  to  Messrs.  Swift  and  Son  a  microscope 
on  the  lines  of  the  one  that  the  last  speaker  has  said  he  would  like 
to  see,  viz.,  an  instrument  that  could  be  commenced  in  a  small  way 
and  gradually  built  up  as  time  goes  on. 

The  simplest  form  had  a  firm  tripod,  of  which  the  toes  of  the 
legs  were  cork-filled  to  give  firmness.  The  stage  was  a  cut-open  form 
recommended  by  the  late  Dr.  Dallinger  and  Mr.  E.  M.  Nelson. 
The  coarse  adjustment  was  made  by  the  body  sliding  in  a  cloth  lined 
fitting.  The  screwed  holes  for  the  attachment  of  the  limb  or  arm 
to  the  stage  were  made  a  standard  distance  from  the  optical  centre, 
so  that  a  coarse  adjustment  with  rack  and  pinion  movement  could 
be  exchanged.  The  side  edges  of  the  stage  were  grooved  for  the 
vertical  movement  of  a  mechanical  stage  or  roller  sliding  bar  which 


ADJOURNED    DISCUSSION    IN    LONDON  235 

-could  be  easily  slipped  on  and  off.  The  under-stage  tube  was  fixed 
to  a  plate;  this  could  be  replaced  by  a  centering  motion,  rack  and 
pinion  sub-stage.  The  sliding  draw-tube  could  be  replaced  with  a 
rack  and  pinion  draw-tube  divided  into  mm. 

Another  addition  which  is  added  to  a  small  portable  microscope, 
and  would  be  useful  to  all  plain  stage  microscopes,  whoever  the  maker 
might  be,  is  a  very  simple  and  efficient  finder,  and  is  standardised 
as  follows :  — 

Each  maker  has  a  3  x  1  in.  piece  of  metal  1  mm.  thick.  At 
equal  distances  from  the  ends  and  sides  is  made  a  small  hole  (A) 
1  mm.  diameter,  and  another  hole  the  same  size,  made  exactly  1  in. 
distance  from  the  centre  hole  and  equal  distance  from  the  sides  (B), 
thus : — 


When  an  instrument  is  assembled  and  completed  ready  for  sale 
the  above  plate  is  placed  on  the  stage  of  the  microscope  resting 
against  the  sliding  bar  or  mechanical  stage,  or  a  mechanical  square; 
then  with  a  2 /3rd  or  1  in.  objective  the  hole  A.  is  brought  into 
the  centre  of  the  field  of  the  eye-piece;  the  metal  3  x  1  is  held 
firmly  by  the  stage  springs  or  clips,  and  a  small  sharp  drill  is  passed 
through  the  hole  B  and  a  few  twists  given,  which  will  make  a 
drill  mark  on  the  stage.  This  is  then  filled  in  with  Plaster  of  Paris, 
thus  giving  a  white  dot  over  a  black  stage. 

Now  suppose  we  have  a  scattered  slide,  and  some  part  (or  parts) 
has  some  object  of  special  interest  which  one  wishes  to  find  quickly 
at  some  future  time — all  that  is  needed  when  the  object  is  squarely 
•on  the  stage  is  to  make  an  ink  dot  on  the  slide  exactly  over  the 
white  dot  on  the  stage.  Other  dots  can  be  made  if  needed,  and 
marked  A,  B,  C,  etc.  Then  for  the  future  all  that  is  necessary  is 
to  place  dot  A,  B,  or  C  over  the  white  dot  on  the  stage,  and  the 
•desired  part  is  in  the  centre  of  the  field  of  the  eye-piece. 

With  regard  to  Dr.  Evans's  paper,  he  has  specially  mentioned 
•crystals,  but  I  do  not  think  any  instrument  is  so  efficient  for  examin- 
ing minute  crystals  as  the  one  introduced  by  Mr.  Allan  B.  Dick. 
In  this  instrument  you  can  introduce  a  minute  crystal  on  the  cross 
■wire,  and  it  does  not  alter  its  position  at  all. 

Dr.  J.  W.  Evans  :  No  one  appreciates  more  than  I  do  its  valu- 
able qualities,  but  it  is  impossible  to  apply  the  methods  devised  by 
Professor  Beck  for  the  study  of  interference  figures  to  a  microscope 
■with  rotating  nicols,  at  any  rate  without  very  considerable  modifica- 
tion, and  in  the  second  place  the  small  upper  Bertrand  lens  cannot 
compare  in  convenience  and  effectiveness  for  the  examination  of  the 
interference  figures  of  minute  objects  with  a  Beck  lens  placed  above 
the  eye-piece,  in  conjunction  with  a  diaphragm  placed  in  the  focua 
of  the  latter. 


236  ADJOURNED    DISCUSSION    IN    LONDON 

Col.  J.  Clibborn :  We  have  heard  to-night  an  immense  amount 
of  detailed  information  as  to  what  is  desirable,  but  nobody  has 
suggested  yet  the  means  by  which  we  may  attain  our  object.  I  do 
not  think  there  is  any  doubt  that  what  is  desirable  is  that  we  should, 
at  all  events,  have  one  standard  microscope  which  will  fill  the  con- 
ditions that  have  been  mentioned.  We  should  at  all  events  have 
one  pattern — it  is  possible  that  we  may  require  other  patterns — 
but  we  at  any  rate  require  one  pattern  of  standard  microscope,, 
because  it  is  only  possible  to  manufacture  in  very  large  quantities. 
These  instruments  cannot  be  manufactured  cheaply,  even  in  large 
numbers,  unless  you  have  suitable  machines,  and  the  question  is 
how  are  we  going  to  arrive  at  this  condition  of  things.  I  do  not 
think  it  can  be  done  by  separate  manufacturers,  because  it  is  not 
possible  that  the  patterns  will  all  agree.  The  manufacturers  might 
all  join  together  and  form  a  combination,  and  perhaps  it  might 
be  done  in  that  way,  but  I  think  the  best  way  is  what  I  suggested 
12  months  ago,  namely,  that  a  Committee  should  be  appointed  of 
the  ablest  men  interested  in  the  question,  inside  and  outside  the 
Society,  to  devote  themselves  to  the  design  of  the  standard  micro- 
scope. It  should  undergo  as  much  criticism  as  can  be  brought  to 
bear  upon  it,  and  then  we  should  endeavour  to  get  an  instrument 
made  and  tested.  If  we  do  not,  I  am  perfectly  certain  that  the 
manufacture  of  the  microscope  will  leave  this  country  and  go  to 
the  Continent. 

Dr.  J.  R.  Leeson :  An  important  question  is  that  of  price.  I 
have  been  trying  for  four  years  to  fit  up  my  little  laboratory  with 
microscopes,  but  I  cannot  get  them;  at  least,  if  I  can  get  them  I 
cannot  find  the  heart  to  pay  for  them.  Scientists  are  not  rich  people,, 
and  if  you  are  going  to  popularise  the  microscope,  you  must  have 
an  instrument  that  is  within  the  reach  of  the  ordinary  individual. 
If  you  do  not,  then  the  trade  will  again  leave  this  country. 

Dr.  R.  Mullineux  Walmsley :  The  last  speaker  and  the  last 
speaker  but  one  have  referred  to  matters  with  which  I  have  been 
somewhat  associated  through  the  British  Science  Guild.  A  Com- 
mittee has  been  proposed  here  to-night,  but  I  would  like  to  inform 
the  proposer  that  the  work  he  suggests  has  already  been  done.  The 
British  Science  Guild  first  of  all  invited  well-known  users  of  micro- 
scopes to  schedule  their  requirements.  Having  collected  and  col- 
lated these  schedules,  we  asked  the  manufacturers  to  join  the  Com- 
mittee and  tell  us  whether  it  was  possible  from  their  point  of  view 
to  produce  microscopes  which  would  fulfil  their  requirements.  Even- 
tually by  the  combination  of  the  scientific  men  who  were  using  the 
microscopes  and  of  the  manufacturers,  we  drew  up  and  published 
specifications  for  three  or  four  standard  instruments  for  different 
purposes.  We  wei-e  in  the  middle  of  the  Great  War  at  the  time, 
and  the  object  was  to  see  whether  manufacturers  would  consider 
placing  such  instruments  on  the  market,  when  peace  came,  with 
such  added  modifications  as  the  progress  of  time  might  render  desir- 
able. The  question  of  price  was  not  overlooked,  although  I  do  not 
know  that  the  prices  we  put  down  in  1917  can  be  held  to  at  the 
present  time. 


ADJOUKNED    DISCUSSION    IN    LONDON  237 

The  evidence  of  the  work  is  on  record,  both  in  the  Journal  of 
the  British  Science  Guild  and  the  Royal  Microscopical  Society,  and  I 
fancy  that  the  manufacture  of  both  instruments  exhibited  to-night 
were  to  some  extent  influenced  by  the  specifications  prepared  by 
the  Committee. 

Mr.  Conrad  Beck  said  that  the  standard  instrument  made  by 
his  firm  was  made  to  the  specification  of  the  British  Science  Guild 
Committee,  but  the  larger  one,  made  by  Messrs.  Swift,  was  quite  a 
different  matter.  The  latter  was  more  of  a  special  research  type. 
He  certainly  welcomed  the  suggestion  that  a  small  sum  of  money 
should  be  put  up  to  assist  in  manufacturing  microscopes.  But  what 
was  meant  by  a  small  sum  ?  In  some  instances  upwards  of  £20,000' 
had  been  spent  in  tools  and  machinery;  Messrs.  Watson  and  his 
own  firm  had  each  expended  an  enormous  amount  of  money  on 
machinery  and  tools  which  it  was  hoped  in  course  of  time  would  be- 
found  advantageous  to  microscopical  work,  and  if  a  small  sum  meant 
something  of  this  nature  it  was  an  excellent  proposition. 

Mr.  Watson  Baker :  The  microscope  which  our  firm  has  made 
according  to  the  specification  of  the  British  Science  Guild  is  not 
here  to-night,  but  I  am  glad  to  take  this  opportunity  of  saying 
that  we  should  welcome  any  members  of  the  Royal  Microscopical 
Society  to  our  works  to  see  exactly  what  is  being  done. 

I  believe  that  Col.  Clibborn  himself  would  be  pleased  to  see 
that  microscopes  are  being  made  by  machinery  in  a  manner  not 
hitherto  done  in  this  country.  It  has  taken  us  12  months  to  put 
up  a  new  building  and  make  the  necessaiy  tools,  but  we  have  accom- 
plished it,  and  if  British  users  could  be  induced  to  visit  us  and 
se©  what  we  have  done  and  what  it  has  involved,  we  should  be  very- 
pleased. 

Mr.  Perkins :  I  was  struck  by  the  remark  of  Professor  Desch  in 
his  paper  when  he  said  that  microscopes  wear  because  of  the  bad 
material  of  racks  and  pinions.  I  have  found  in  a  fairly  long  ex- 
perience of  microscope  repair  that  sometimes  the  German  slides  are 
softer  than  the  English  slides,  so  that  does  not,  in  my  opinion^ 
account  for  the  fact  that  the  English  microscope  wears  quicker  than 
the  German.  It  has  always  seemed  to  me  that  the  English  makers, 
in  spite  of  their  undoubted  ability,  overlook  the  fact  that  if  you 
want  to  reduce  wear  on  the  slides  of  a  microscope,  they  must  bear 
properly  upon  each  other.  It  is  no  good  putting  in  slides  which 
bear  at  points,  as  in  Fig.  1.  Wear  very  quickly  takes  place  at  those 
points  and  develops  a  shake,  and  you  get  a  loss  of  stability,  such 
as  Professor  Barnard  spoke  of.  The  closest  analogy  I  can  put  forward 
is  an  ordinary  bearing.  If,  for  argument's  sake,  the  inner  bearing 
is  much  smaller  than  the  outer  (Fig.  2),  you  get  point  metal  to 
metal  contact  and  quick  wear.  If,  however,  it  fits  as  in  Fig.  3, 
the  lubricant  stops  in  in  an  unbroken  film,  and  you  get  long  and 
efficient  wear.  I  have  seen  microscopes  20  years  old  which  have  no 
shake  in  them  and  still  fit  perfectly  all  over.  Then,  again,  the 
weakness  of  design  of  the  usual  spring  fitting  is  another  point  which 


238 


ADJOURNED    DISCUSSION    IN    LONDON 


in  my  opinion  English  manufacturers  have  always  overlooked.  If 
you  spring  at  four  corners,  like  a,  b,  c,  d  (Fig.  4),  the  fitting  E 
has  got  to)  be  a  very  fine  fit,  and  also  the  fitting  F,  but  directly  you 
start  springing  E  you  distort  F  at  once.  I  have  seen  it;  l"  have 
spent   hours  over    it   worrying    about    it,    but     English    makers    are 


Fic.Z 


Fig. 3 


Fig.  I 


.E^^=MI|3, 


Fig. 4 


Fig   5 


gradually  waking  up  to  the  fact  that  you  have  got  to  have  your 
slides  in  a  springless  chunk  of  metal,  something  like  that  shown 
in  Fig.  5,  so  that  when  you  do  the  screws  up,  the  chunk  of  metal 
remains  as  it  was  and  does  not  distort.  Again,  how  can  you  effi- 
ciently remove  the  grinding  material  from  the  springing  slots,  which 
is  another  obvious  source  of  wear. 


Mr.  Beck :  Was  the  microscope  20  years  old  which  you  referred 
to  German  or  English? 

Mr.  Perkins:  It  was  German.  I  am  not  saying  that  I  have 
not  seen  an  equally  good  English  instrument  20  years  old,  but  I 
am  speaking  of  English  instruments  as  a  body.  Another  point  is 
that  English  makers  must  now  see  to  it  that  they  have  an  efficient 
system  of  inspection.  The  Germans  have  a  very  efficient  system  of 
inspection,  and  English  makers  must  see  that  nothing  leaves  their 
factories  which  is  not  perfect.  When  you  have  got  to  that  point, 
but  not  before,  then  success  is  assured. 

Mr.  Harold  Wrighton  :  It  fell  to  my  lot  to  prepare  the  photo- 
micrographs which  were  shown  in  the  paper  given  by  Sir  Kobert 
Iladfield  and  Mr.  T.  G.  Elliot  at  the  Symposium.  These  photographs 
were  taken  on  a  Zeiss-Martens  horizontal  machine.  In  order  to 
obtain  them  I  found  it  necessary  to  alter  radically  the  long  distance 
fine  focussing  adjustment.  Even  in  the  best  patterns  of  photomicro- 
graphic  apparatus  the  design  and  efficiency  of  this  long  distance 
focussing  fittings  seems  to  receive  very  little  attention.  Possibly  a 
description  of  the  new  arrangement  may  be  of  interest  to  some 
gentlemen  who  have  a  similar  Zeiss-Martens  outfit. 


ADJOURNED    DISCUSSION    IN    LONDON 


239 


The  arrangement  shown  in  the  accompanying  sketch  was  made 
in  the  w^orks  at  very  small  cost,  and  has  proved  very  satisfactory. 
The  short  metal  rod  which  fitted  into  the  socket  on  the  focussing  rod 
has  been  replaced  by  a  longer  rod,  J  in.  square  in  cross  section. 
A  IJ  in,  pulley  wheel,  turning  on  flanges,  is  mounted  on  a  bracket 
at  the  corner  of  the  microscope  base.  A  square  hole  through  the 
pulley  wheel  is  just  large  enough  to  allow  of  very  slight  play  between 
the  wheel  and  the  square  rod.  As  the  square  rod  w^ill  pass  along 
through  the  pulley  wheel,  horizontal  traverse  of  the  microscope  stage 
is  not  interfered  with.     A  long  rod  is  mounted  in  brackets  screwed 


to  the  base,  which  carries  the  camera.  This  rod  has  a  2  iii-  pulley 
wheel  at  one  end,  which  is  connected  by  cord  to  the  other  wheel. 
At  the  other  end  is  a  2  in.  milled  brass  head,  for  turning.  The 
two  grooved  wheels  over  which  the  cord  passes  are  milled  inside  the 
grooves,  thereby  preventing  slip.  The  arrangement  as  made  to 
dimensions  given  above  further  reduces  the  speed  of  fine  adjustment 
by  one  half.  The  main  advantage  is  that,  owing  to  slight  play 
between  wheel  and  square  rod,  any  slight  torsion  produced  whilst 
turning  the  rod  can  ease  itself  when  the  hand  is  removed,  without 
turning  the  fine  adjustment  and  disturbing  the  focus. 

Another  matter,  referred  to  by  a  previous  speaker,  is  the  lack 
of  contrast  in  most  metallurgical  specimens  as  compared  with  a 
biological  section.  This  is  one  of  our  difficulties,  and,  as  a  matter 
of  fact,  most  of  our  photomicrographs  show  considerably  more  con- 
trast than  is  actually  present  in  the  specimen. 


Mr.  T.  Smith :  I  would  like  to  have  spoken  on  the  optical  side 
■of  the  discussion,  but  there  is  one  matter  I  will  refer  to.  We  have 
Iveen  given  some  figures  by  Commander  Ainslie  based  on  a  displace- 
ment of  1/100  mm.,  and  some  further  results  on  a  basis  of  the  same 
magnitude,  with  the  displacement  along  the  axis,  may  be  of  interest. 


240  ADJOURNED    DISCUSSION    IN    LONDOK 

I  have  worked  out  some  figures  relating  to  a  2  mm.  objective. 
N.A.  =  1.4,  whicli  gives  perfect  definition  when  used  properly. 
With  the  object  displaced  1/100  mm.  from  its  proper  posi- 
tion, I  find  that  the  marginal  rays,  instead  of  converging  to  the 
paraxial  image  point,  get  farther  and  farther  away  from  the  axis. 
This  indicates  how  accurately  it  is  necessary  to  focus  at  high  magnifi- 
cations. Therefore  I  would  like  to  suggest  that  manufacturers  of 
apparatus  for  high  power  work  and  particularly  for  ultra-violet 
microscopy  should  pay  special  attention  to  the  problem  of  adjusting 
the  specimen  accurately  in  relation  to  the  objective.  Particularly 
when  short  wave-lengths  are  being  used,  as  in  ultra-violet  micro- 
scopy, is  this  necessary  if  much  time  is  not  to  be  wasted  in  taking 
useless  photographs. 

The  Chairman  :  We  now  proceed  to  the  discussion 
of  the  Optics  of  the  Miceoscopk,  and  I  will  ask 
Mr.  Whipple,  President  of  the  Optical  Society,  to  take 
the   Chair. 

Mr.  R.  S.  Whipple :  I  think  that  at  this  stage  of  the  proceedings 
w©  ought  to  congratulate  Messrs.  Beck  on  the  fact  that  they  have 
been  able  to  produce  a  standard  microscope  and  that  they  have 
been  able  to  keep  their  promise  to  produce  it  this  month.  As  a 
manufacturer  I  know  the  difficulty  of  keeping  a  promise  of  this  kind, 
and  it  is  greatly  to  their  credit  that  they  have  been  able  to  keep 
to  time.  As  a  manufacturer,  I  also  know  some  of  the  difficulties 
involved  in  the  production  of  a  new  instrument.  They  have  covered 
the  foot  of  the  stand  with  ebonite.  To  do  this  is  in  itself  an  achieve- 
ment; they  have  introduced  this  ingenious  geometric  arrangement 
for  holding  the  objectives,  another  considerable  achievement.  Thus 
in  this  apparently  simple  looking  article  there  are  a  number  of 
mechanical  achievements — I  venture  to  say  great  achievements — 
which  a  few  years  ago  would  have  been  regarded  as  impossible.  I 
think,  therefore,  that  it  is  not  right  to  pass  from  the  mechanical 
side  of  the  microscope  without  expressing  our  indebtedness  to  them 
for  what  they  have  done  so  far,  and  to  wish  them  and  other  English 
microscope  makers  every  success  in  the  future. 

Abstracts  of  the  following  papers  were  then  presented  :  — 
THE  OPTICS  OF  THE  MICROSCOPE. 

Professor  A.  E.  Conrady,  "  Microscopical  Optics." 

Dr.  H.  Hartridge,  M.A.,  "An  Accurate  Method  of  Objective 
Testing." 

Mr.  H.  S.  Ryland,  "  The  Manufacture  and  Testing  of  Micro- 
scope Objectives." 

Mr.  F.  Twyman,  "  Interferometric  Methods." 

Discussion. 

Mr.  Conrad  Beck :  I  have  been  greatly  interested  in  the  Hart- 
ridge test  for  microscope  object  glasses.  Whether  the  graphs  that 
you  get  are  any  value  or  not,  it  is  impossible  to  say.  I  should  not 
at  present  like  to  express  the  slightest  opinion ;  all  I  can  say  is  that 
I  was  interested  to  find  that  the  graphs  which  we  took  in  succession 


ADJOURNED    DISCUSSION    IN    LONDON  241 

one  after;  the  other  with  the  same  object  glass  were  fairly  consistent, 
which,  considering  the  conditions  under  which  these  observations 
are  made,  is  rather  remarkable,  because  one  is  using  an  extremely 
small  portion  of  the  object  glass  at  one  time.  The  principle  is  that 
by  the  use  of  a  small  diaphragm  you  are  illuminating  a  small  zone 
of  the  object  glass,  and  the  numerical  aperture  of  the  portion  you 
are  illuminating  is  very  small.  I  did  not  expect  that  our  results 
would  agree,  because  of  the  extremely  inferior  image  produced  with 
such  a  small  portion  of  the  object  glass  being  used  at  one  time.  In 
discussing  this  matter  with  Dr.  Hartridge,  he  pointed  out  that  his 
microscope  was  not  nearly  sufficiently  rigid  for  the  purpose.  The 
matter  has  been  considered  by  my  firm,  and  they  came  to  the  con- 
clusion that  there  was  no  microscope  sufficiently  rigid  for  the  pur- 
pose, and  consequently  for  the  last  eight  weeks  we  have  been  design- 
ing an  instrument  which  I  am  proposing  to  make  for  my  own  personal 
use  that  I  hope  and  think  will  be  the  most  perfect  microscope  stand 
ever  made.  I  shall  show  it  to  the  Society  as  soon  as  it  is  made. 
Those  who  use  the  microscope  for  general  work  may  consider 
it  too  elaborate  and  expensive  for  ordinary  purposes,  but  I  am  not 
sure.  It  will  have  some  features  about  it  that  will  make  it  unusually 
rigid.  Its  construction  is  an  interesting  engineering  problem,  and 
whether  anybody  will  ever  order  a  similar  one  may  be  doubtful, 
because  the  cost  will  be  very  great. 

There  is  one  point  made  by  Dr.  Hartridge  in  his  paper  which 
I  think  is  an  obvious  error,  and  if  it  were  pointed  out  I  think  he 
would  admit  it.  The  method  of  testing  the  object  glass  is  only  a 
test  to  see  whether  the  light  from  a  lens  is  going  to  one  point.  It 
is  not  a  test  of  the  sine  condition.  That  must  be  carried  out  as  a 
separate  test,  and  I  am  bound  to  say  that  my  own  impression  is 
that  when  the  Hartridge  test  is  worked  out  and  his  method  of  cali- 
brating and  plotting  out  has  been  done,  we  shall  find  we  are  testing 
an  important,  but  not  by  any  means  the  most  important,  correction 
on  an  object  glass.  The  important  points  about  an  object  glass, 
apart  from  achromatic  corrections,  are  firstly,  that  the  light  from 
the  whole  object  glass  shall  go  on  to  a  point,  and  secondly,  that 
the  focal  length  of  every  zone  in  the  glass  shall  be  the  same,  and 
it  is  this  latter  point  that  the  sine  condition  guarantees.  Mr.  Hart>- 
ridge's  test  has  some  analogy  to  the  Hartmann  test;  it  measures  the 
lateral  shift  of  the  uncorrected  rays  instead  of  the  longitudinal  error. 

Commander  M.  A.  Ainslie,  R.N.:  I  should  like  to  concentrate 
attention  on  the  subject  of  the  condenser.  Professor  Conrady  refers 
to  the  incorrect  position  of  the  iris  diaphragm;  this  is  certainly 
most  marked,  but  there  are  one  or  two  points  to  be  considered  in 
this  connection.  There  is  no  reason  why  the  iris  diaphragm  should 
not  be  placed  between  the  top  lens  of  the  condenser  and  the  next 
lens,  or  perhaps  a  little  lower  down;  at  any  rate,  much  higher  up 
that  it  is  at  present.  The  diaphragm  could  be  very  well  worked  by 
means  of  a  bevel  wheel  and  a  pinion  coming  out  radially;  the  only 
thing  against  this  is  that  the  stage  is  so  thick.  It  would  be  quite 
impossible  on  the  standard  instrument  here  shown,  but  if  we  were 
to  return  to  the  "  horseshoe  "  type  of  stage  designed  by  Nelson, 
it  could  be  done  perfectly  easily.  Presumably,  however,  the  exit 
pupil   of   the  objective   is  in   the   neighbourhood    of  its    upper    focal 


242  ADJOURNED    DISCUSSION    IN    LONDON 

plane;  as  a  general  rule  I  fancy  it  is  rather  lower  down,  but  the 
position  does  not  seem  to  be  constant,  even  in  objectives  of  the  same 
type.  If  the  obliquity  of  illumination  at  the  margin  of  the  field 
mentioned  by  Professor  Conrady  is  to  be  avoided,  the  iris  will  have 
to  be  in  the  back  focal  plane  of  the  condenser;  if  that  is  the  case, 
no  lateral  movement  of  the  condenser  will  affect  the  position  of  the 
image  of  the  iris-aperture  in  the  back  lens  of  the  objective,  and  it 
will  be  impossible  to  judge  of  the  centering  by  looking  down  the  tube. 

Again,  I  think  that  both  opticians  and  users  of  the  microscope 
are  content  with  too  little  in  connection  with  the  performance  of 
the  condenser;  and  I  should  say  that  the  objection  that  the  slide  is 
composed  of  "  window  glass  "  introduces  another  "  bogey/'  The 
area  involved  is  always  small,  and  if  an  oil  immersion  condenser  is 
used,  the  surfaces  of  the  slip  cease  to  exist  optically.  At  any  rate, 
with  a  first  rate  modern  achromatic  condenser,  such  as  the  Watson 
"  Parachromatic,"  it  is  possible,  when  the  light  source  has  a  screen 
extending  half  w^ay  across  it,  to  focus  with  such  sharpness  an  image 
of  the  edge  of  this  screen  on  the  object  that  one  row  of  dots  on, 
say,  Pleurosigma  Angulatum  shall  be  in  full  light  and  the  next  in 
"  full  darkness  *' — and  this  with  an  N.A.  in  use  of  not  less  than 
0.7.  This  means  that  it  is  possible  to  get  sharpness  of  the  order  of 
^ —    of   an   inch.      But  this  is  only   done   on   one   condition,  and 

50,000  -^  ^ 

that  is  that  the  distance  of  the  light-source  is  carefully  adjusted  to 
the  thickness  of  the  slip;  as  carefully  as  we  adjust  tube-length  to 
the  thickness  of  the  cover  glass.  This  point  is  almost  universally 
avoided  by  the  text-books,  and  I  want  to  bring  it  forward  as  strongly 
as  possible. 

Mr.  T.  Smith:  With  regard  to  increasing  the  resolving  power 
of  microscope  objectives,  there  is  little  doubt  that  the  numerical 
aperture,  as  it  is  ordinarily  understood,  can  hardly  be  increased 
with  advantage,  buti  there  is  considerable  prospect  of  obtaining  in- 
creased resolving  power  by  using  shorter  wave-lengths  of  light.  There 
are  very  considerable  difficulties  at  present  in  the  way,  but  I  see  no 
reason  why  they  should  not  be  overcome,  although  an  extraordinary 
amount  of  experimental  work  will  be  involved.  It  is  necessary  to 
know  the  properties  for  such  light  of  a  very  great  variety  of  materials. 
Where  we  already  possess  some  knowledge  of  the  behaviour  of  certain 
materials  with  regard  to  ultra-violet  light,  this  information  must 
become  much  more  precise  than  at  present  before  it  can  be  con- 
sidered adequate,  and  I  should  like  to  see  some  definite  encourage- 
ment given  to  researches  of  this  character,  because  they  can  hardly 
fail  to  lead  to  results  of  value  to  the  microscope  user.  Coming  now 
to  objectives  and  their  design,  it  seems  to  me  that  this  subject  has 
never  been  investigated  systematically,  but  that  new  objectives  have 
generally  been  a  further  development  of  old  designs  on  known  lines. 
I  should  like  to  see  systematic  investigations  undertaken,  so  that  we 
may  know  what  prospect  there  is  of  effecting  real  improvements  in 
the  corrections.  For  example,  in  a  high  power  objective  we  have  a 
lot  of  lenses  placed  very  close  together,  though  I  am  not  aware  of 
any  thorough  investigation  which  justifies  adherence  to  this  arrange- 
ment. There  are  obvious  difficulties  in  the  way  of  large  separations; 
nevertheless,  there  would  appear  to  be  some  decided   advantages  to 


ADJOURNED    DISCUSSION    IN    LONDON  243 

be  gained.  At  present  with  apochromatic  lenses  the  curvature  of 
the  field  is  due  to  the  properties  of  the  transparent  materials  we 
employ.  In  general  they  have  very  similar  properties  as  regards 
relative  dispersion,  and  this  imposes  very  severe  limitations  on  what 
can  be  achieved;  but  these  limitations  no  longer  hold  if  the  lenses 
are  well  separated,  and  it  is  possible  that  material  improvements 
may  be  effected  by  radical  alterations  in  the  type  of  objective.  There 
would  be  difficulties  in  doing  this  with  objectives  for  ordinary  use, 
but  they  would  hardly  apply  at  all  for  a  special  instrument  required 
to  give  vei-y  great  magnification,  such  as  the  metallurgists  ask  for, 
and  I  think  these  investigations  might  very  well  be  made  in  regard 
to  objectives  for  this  particular  purpose.  In  fact,  I  think  we  want 
to  see  a  very  great  deal  more  of  the  design  and  manufacture  of 
objectives  for  special  purposes  instead  of  expecting  one  objective  of 
a  given  focal  length  to  do  any  and  every  job.  It  ought  to  be  realised 
more  generally  that  an  objective  of  high  resolving  power  difiEers 
markedly  from  a  so-called  universal  objective  like  a  photographic 
anastigmat.  A  microscope  objective  of  large  N.A.  is  necessarily  a 
very  poor  instrument  for  any  conditions  but  precisely  those  for 
which  it  is  designed.  There  are  many  other  points  to  which  atten- 
tion might  be  called,  but  it  must  suffice  now  to  mention  one.  A 
great  deal  has  been  said  about  the  variation  in  the  definition  given 
by  similar  objectives  made  by  the  same  firm  from  similar  glass,  w^hich 
ought  therefore  to  be  identical  in  performance,  I  want  to  suggest 
that  a  possible  contributory  cause  may  be  insufficiently  accurate 
centering  of  the  surfaces.  I  do  not  think  that  investigations  have 
ever  been  carried  out  on  methods  of  getting  surfaces  centered  to  an 
extraordinary  degree  of  accuracy,  yet  a  veiy  high  degree  of  accuracy 
is  obviously  required  in  a  microscope  objective.  I  have  seen  photo- 
graphic lenses  under  examination  with  the  interferometer,  and  thes9 
have  shown  marked  irregularities  in  the  wave  front  towards  the 
periphery  of  the  lens.  When  we  seek  the  highest  possible  resolving 
power,  it  is  the  periphery  of  the  lens  that  is  all  important,  so  I 
think  we  want  to  see,  among  other  things,  an  investigation  into 
methods  of  getting  surfaces  centered,  not  twice  as  accurately  as  we 
do  them  at  present,  but  perhaps  10  or  even  100  times  as  well.  If 
any  manufacturer  were  able  to  effect  such  an  improvement,  he  would 
probably  find  that  his  lenses  would  realise  a  much  more  uniform 
standard  of  excellence  than  those  produced  at  the  present  time.  I 
very  much  hope  that  in  some  of  the  directions  I  have  indicated  the 
National  Physical  Laboratory  may  be  able  to  give  assistance  to  our 
own  manufacturers. 

Mr.  J.  E.  Barnard:  Mr.  Smith  has  just  referred  to  the  question 

of  investigation  by  the  use  of  radiations  of  short  wave-length.  I 
should  have  hesitated  to  bring  the  subject  up  again  had  it  not  been 
that  Professor  Conrady  also  referred  to  it  in  his  paper,  and  by  a 
curious  chance  he  has  dropped  into  a  not  unusual  error.  He  says 
that  the  limitations  of  the  work  are  in  part  laid  down  by  the  opacity 
of  bodies  to  ultra-violet  light.  When  you  get  down  to  the  dimen- 
sions with  which  we  are  dealing  in  a  microscopic  object  which  is  at 
or  beyond  the  ordinary  resolution  limits,  opacity  is  almost  non- 
existent.     Sir  George  Beilby  has  shown  that  veiy   thin  metal  films 


244  ADJOUENED    DISCUSSION    IN    LONDON 

are  almost  perfectly  transparent,  and  yet  metals  are  the  most  opaque 
of  substances.  Latterly  I  have  been  endeavouring  to  photograph  by 
means  of  ultra-violet  light  some  exceedingly  small  organisms,  some 
of  which  are  beyond  the  limits  of  resolution,  and  the  difficulty  has 
been  that  with  any  wave-length  I  have  at  present  available,  the 
organism  is  transparent.  The  radiations  pass  completely  through, 
and  I  am  unable  to  get  an  image  of  any  description  whatever.  So 
that  to  say  that  the  limitations  of  the  work  are  largely  governed  by 
the  opacity  of  small  bodies  is  not  in  accordance  with  practical 
•experience  or  theoretical  expectations.  It  may  possibly  arise  if  we 
use  radiations  of  much  shorter  wave-length  than  those  at  present 
available,  but  in  that  case  we  shall  be  working  with  a  microscope  in 
vacuo,  and  I  do  not  think  it  is  a  point  which  is  likely  to  arise  in 
practice  for  some  time  to  come,  although  it  may,  and  probably  will, 
arise  at  a  later  stage. 


Mr.  L.  C.  Martin:  I  was  interested  in  the  description  of  the 
Hartridge  test  for  the  microscope  objective,  but  I  should  like  to  say 
that  it  is  not  often,  I  believe,  that  a  man  testing  a  microscope  objec- 
tive wishes  to  know  the  aberration  to  any  great  accuracy,  but  rather 
whether  the  microscope  objective  is  sufficiently  good  for  the  purpose. 
Therefore  a  somewhat  easier  quantitative  test  is  to  be  desired.  At 
the  present  time  I  have  been  doing  a  certain  amount  of  work  as  a 
sort  of  preliminary  study  of  the  star  test,  and  I  thiiik  that  possibly 
the  so-called  Rayleigh  condition  of  less  than  one  quarter  wave-length 
a  speedy  test  of  the  aberrations  of  a  microscope  objective. 

Professor  Conrady  remarks  in  his  paper  that  the  fulfilment  of 
the  so-called  Rayleigh  condition  of  less  than  one  quarter  wave-length 
difference  of  optical  paths  between  paraxial  and  marginal  rays  iu 
good  telescope  and  microscope  objective,  has  been  demonstrated  by 
the  Hilger  interferometer.  It  is  easy  to  understand  that,  imagining 
a  perfectly  spherical  mirror  in  the  interferometer  and  a  means  of 
controlling  the  position  of  such  a  surface  to  correspond  with  any 
particular  focus  of  the  test  lens,  such  a  perfect  demonstration  could 
be  given.  It  is  not  easy  to  understand,  however,  when  we  consider 
that  the  errors  of  the  surface  of  a  mirror,  which  may  be  of  the  order 

<5i    —  or  even  more,  are  doubly  important  in  such  a  case,   and  that 

the  position  of  the  test  focus  has  to  be  obtained  by  trial.  It  is  only 
when  we  consider  a  fact  which  was  hinted  at  by  Lord  Rayleigh  in 
1879,  and  worked  out  by  Professor  Conrady  in  his  paper  on  Star 
Discs,  viz.,  that  the  effects  of  spherical  aberration  can  often  be 
countered  very  completely  by  changes  of  focus  (or  in  mathematical 
language  that  we  can  partly  balance  the  terms  of  the  fourth  and 
higher  orders  in  the  aberration  expression  by  a  change  of  the  co- 
efficient of  the  second  order),  that  we  can  realise  that  the  indications 
of  the  interferometer  are  trustworthy  even  to  the  extent  previously 
indicated.  It  is  necessary  to  bear  in  mind,  however,  that  there  is 
nothing  magically  sensitive  in  the  interferometer  tests  as  compared 
with  star  tests,  for  example,  if  these  are  performed  with  the  maxi- 
mum of  care.  Those  who  expect  them  to  give  tremendously  sensi- 
tive results  far  excelling  all  other  tests  are  doomed  to  disappointment. 


ADJOURNED    DISCUSSION    IN    LONDON  245 

Mr.  Beck:  Will  you  explain  to  us  whether  a  quantitative 
aneasurement  is  obtained  in  the  star  test.  The  star  test  has  been  in 
use  with  the  microscope  objective  ever  since  the  achromatic  micro- 
scope objective  was  known,  in  the  form  of  a  minute  mercury  globule 
reflecting  a  small  source  of  light  which  makes  practically  an^  artificial 
star. 

Mr.  Martin :  The  work  I  have  been  doing  is  in  a  very  unad- 
vanced  stage,  but  I  hope  it  will  be  possible  to  obtain  a  rough  esti- 
mate of  the  variation  of  the  spherical  aberration. 

Commander  Ainslie:  I  had  the  curiosity  to  test  a  low  power 
objective  on  the  well-known  AVassel  method,  and  it  was  easy  to 
-obtain  (by  this  particular  method  of  the  extinction  of  the  two  sides 
of  a  zone  simultaneously,  with  a  screen),  numerical  values  for  the 
different  foci  of  the  different  zones.  I  was  only  using  a  low  power 
•objective,  an  half -inch  apochromat,  and  it  would  Be  difficult  vdth 
liigh  powers,  unless,  perhaps,  an  auxiliary  telescope  is  used. 

Mr.  T.  Smith :  Mr.  Beck  said  that  the  Hartridge  test  would 
not  give  coma.  May  I  suggest  that  it  is  quite  easy  to  get  coma  by 
plotting  the  spherical  aberration  for  two  somewhat  different  magnifi- 
cations. From  these  numerical  values,  the  deduction  of  the  coma 
is  quite  easy. 


Professor   Eyre,  in  bringing  the  discussion  to  a  close, 
said  : 

The  time  has  now  come  when  I  must  close  the 
meeting.  It  is  very  difficult  at  the  end  of  an  evening  o 
this  character  to  sum  up  with  anything  like  precision  or  to 
offer  an  opinion  that  has  any  value  on  the  work  that  has 
been  presented.  There  is,  however,  one  outstanding 
feature,  namely,  that  workers  are  willing  and  anxious  to 
state  their  requirements  to  the  manufacturers,  and  I  think 
we  have  evidence  that  the  manufacturers  on  their  side  are 
willing  to  do  all  in  their  power  to  help  meet  these  needs. 
We  cannot  expect  perfection  at  once.  As  Mr.  Watson 
Baker  has  said,  it  has  taken  quite  a  year  to  get  his  factory 
and  the  machinery  ready.  It  has  been  the  same  with  all 
manufacturers  and  I  do  trust  now  that  the  necessities  of 
the  workers  have  been  placed  clearly  before  the  manu- 
facturers that  we  shall  soon  reach  a  stage  when  we  shall 
have  an  instrument  of  our  own  manufacture,  not  only  for 
home  use,  but  one  which  will  also  enable  us  to  capture 
the  world's  trade  in  microscopes. 


APPENDIX   I. 


Catalogue  of  Exhibition, 

Held    in    connection    with 

THE     SYMPOSIUM    AND    GENERAL    DISCUSSION 

O  N 

The    Microscope :     Its    Design, 
Construction   and    Applications, 

On  Wednesday,  January  14th,  1920,  in  the  Rooms  of  the  Royal  Society, 
Burlington    House,    Piccadilly.    W.l. 


GROUND  FLOOR. 

A  Selection  of  Mickoscopes  from  the  Collection  in  the 
Science  Museum,  South  Kensington. 

Lent  hij  the  Board  of  Education. 

The  instruments  selected  are  arranged  in  clironological  order,  and 
illustrate  the  development  of  the  compound  microscope  from  the  end 
of  the  sixteenth  century  imtil  towards  the  middle  of  the  nineteenth 
century. 

Jansen's  microscope  (1590)  is  represented  by  a  facsimile  copy, 
and  Hooke's  microscope  (1665)  by  a  photograph  of  the  Plate  in 
his    "  Micrographia." 

The  rest  are  chiefly  examples  of  the  work  of  the  leading  English 
opticians  of  the  eighteenth  and  early  nineteenth  centuries,  viz., 
Marshall,  Culpeper,  Cuff,  Martin,  Adams,  Mann,  Watkins,  Bleuler, 
Dollond,  Smith,  Ross,   Powell,   Tulley,   and  Pritchard. 

To  mark  the  introduction  of  the  apochromatic  objective  a 
microscope  by  Zeiss,  made  in,  1888,   is  also  shown. 

These  instruments,  which  are  not  the  property  of  the  Board, 
are  exlubited  by  permission  of  the  owners,  Mr.  Thomas  H.  Court 
and  Mr.    Edward    M.    Nelson. 

Descriptive  labels  are  shown  with  the  instruments. 

LIBRARY. 

(First  Floor.) 

Mr.  Charles  Baker. — Demonstration  of  photomicrographic 
apparatus,  equipped  for  metallurgical  research  work,  ultra-con- 
denser, concentric  dark  ground  illuminator,  and  recent  introduc- 
tions  of  new   microscopes    and    objectives. 

247 


248  APPENDIX    I. 

Mr.   a.  C.  Banfield. — Thirty  glass  transparencies  illustrating 

the   application  of   the  microscope  to   low    power    stereoscopy.      The 

subjects  shown  range  in  magnification  from  four  diameWs  to 
seventy. 

Mr.    J.    E.   Barnard    and   Mr.   F.    Welch. — Quartz   and   glass 
mercury  vapour  lamps  as  illuminants  for  the  microscope. 
Professor  W.  M.  Bayliss,  E.R.S. — 

(a)  Ultra-microscope      of      Siedentopf-Zsigmondy      pattern, 
showing  Brownian  movement  in  colloidal  gold. 

(b)  Heating  chamber  for  us©  with  "  cardioid  "   condenser, 
showing  cessation  of  Brownian  movement  on  gelatin. 
Messrs.   R.   and  J.   Beck,  Ltd. — The  Beck   Standard  London 

Microscope  to  specification  of  the  British  Science  Guild.  Sloan 
object  changer.  High-power  dark  ground  illuminator.  Beck  micro- 
meter eye-piece. 

Messrs.  Bellingham  and  Stanley,  Ltd. — Instruments  for 
measuring  refractive   indices. 

Improved  Abbe  ref ractometer ;  all  British  design,  enables  re- 
fractive indices  of  solids  or  liquids  to  be  determined  at  average  ac- 
curacy of  two  units  in  the  fourth  place.  The  partial  dispersion  C — F 
can  also  be  measured.  The  immersion  refract ometer  shown  is  iden- 
tical in  principle,  but  is  designed  for  use  with  liquids,  being  suitable 
for  alcohol  determinations.  Refractive  index  plays  an  important 
part  in  microscopy,  not  only  for  materials  used  in  objectives,  but  also 
in  the  case  of  various  mounting  media. 

Messrs.  Boots'  Pure  Drug  Company,  Ltd. — The  use  of  the 
microscope  in  pharmacy  and  pharmaceutical  chemistry. 

Messrs.  British  Colloids,  Ltd. — Colloidal  suspensions  under 
dark-ground  illumination,   to   show  Brownian  movement. 

Messrs.  British  Dyestuffs  Corporation  (Huddersfield), 
Ltd. — Dyestuffs  used  for  staining. 

Basic  Colours'. —  Acid  Colours:  — 

Auramine  O.  Nigrosine  G.    Crystals. 

Bismarck  Brown  R.IOO.  Orang©  G. 

Magenta  Crystals. 
Malachite   Green  Crystals 

A  25  per  cent. 
Methvl  Violet  2B. 
Methylene  Blue  2B. 

Messrs.  The  Cambridge  and  Paul  Instrument  Company,  Ltd. 
— Reading  microscope.  Microscope  used  in  the  accurate  cutting  of 
screw  threads.     Microtomes. 

Messrs.  Chance  Bros,  and  Company,  Ltd.  (Mr.  F.  E.  Lamp- 
lough). — Optical  glass. 

Mr.  a.  Chaston  Chapman,  F.I.C. — Some  cultivated  and 
''wild  "  yeasts  in  pure  culture;  the  former  are  used  for  brewing 
and  distilling  purposes;  some  of  the  latter  are  frequently  a  source 
of  trouble  in  the  brewery. 

INIessrs.  Co-operative  Wholesale  Society,  Ltd.  (Dr.  Geof- 
frey Martin,  F.I.C). — The  use  of  the  microscope  in  the  preparation 
of  foodstuffs. 


APPENDIX    I.  249 

Messrs.  Courtaulds,  Ltd. — The  use  of  the  microscope  in  the 
textile  industry. 

Exhibit  A . — Samples  of  artificial  silk  and  cloth,  and  microscope 
with  sample  of  cloth  under  low  power,  illustrating  employ- 
ment for  studying  character  of  textiles. 
Exhibit    B. — Microscope    with    sample    of    natural    sou  pie    silk 

stained  blue,  illustrating  identification  of  fibres. 
Exhibit  C. — Microscope    with  cross-sections    of    modern  viscose 
artificial  silk,  and  photomicrographs  showing  differences  in 
cross-sections  of  typical   artificial  silks,  illustrating  identifi- 
cation of  origin  and  method  of  manufacture. 
Messrs.    F.    Davidson   and   Company. — The  "  Davon  "    patent 
super-microscope    and    optical    bench    for    direct    visual   observations 
under  high   power,    large    field    and  great   ''  depth    of    focus,''    and 
embodying  a  new  method  of  photomicrography. 

Mr.  D.  Finlayson,  F.L.S.,  and  Mr.  Raymond  Finlayson, 
F.R.]\r.S.,  F.Z.S. — The  microscope  and  its  uses  in  seed  analysis. 
Identification  and  comparison  of  different  species  of  seeds  and  their 
adulterants,  by  means  of  a  revolving  disc  attachment  to  stage  of 
microscope. 

The  Geological  Survey  and  Museum  (Sir  Aubrey  Strahan, 
F.R.S.). — A  series  of  photomicrographs  to  illustrate  the  minera- 
logical  constitution  and  structure  of  rocks  as  revealed  by  the 
petrological  microscope,  and  specimens  to  illustrate  the  mode  of 
preparation  of  thin  rock-sections  for  microscopical  examination. 

Lieut. -Col.  William  Gifford. — Monochromatic  light  filters  for 
use  in  high-power  microscopy  and  photomicrography.  F  line  for 
visual  work,  G  for  photography. 

Messrs.  Flatters  and  Garnett,  Ltd. — Photographs  of  textile 
fabrics  and  fibres. 

Mr.  J.  W.  Gordon. — Demonstration  of  the  principles  of  illu- 
mination in  the  microscope,  with  special  reference  to:  — 

1.  Wide-angled  lighting. 

2.  Narrow-angled  lighting. 

3.  Wide-angled  vision. 

4.  Narrow-angled  vision. 

Messrs.  Hadfields,  Ltd. — Photomicrographs  of  iron  and  steel. 
Mr.  R.  J.  E.  Hanson,  F.R.C.S.— 
Dyoiitikon  {Eye-'piece)  Headrest. 

[Applicable  to  any  existing  standard  microscope.] 
A  sliding  headrest  is  provided,   with  rubber  tubular  buffer 
— to  lessen  fatigue  and  mal-orientalion  of  the  eyes  and  to 
r>ecure    effective    retinal    adaptation   and    stimulation    of   (R 
and  L)  visual  cortex. 
A  Solution  of  Visual  Puvple. 
Dr.  H.  Hartridge. — 

(1)  Apertometry  by  means  of  the  descending  light-path. 

(2)  Water-soluble  immersion  medium  for  use  with  high-power 
objectives. 

(3)  Critical  illumination  with  immersion  condenser,  the  light 
source  being  attached  to  and  forming  part  of  the  micro- 
scope. 


250  APPENDIX    1. 

Dr.  AV.  H.  Hatfield. — Photomicrographs  ilhistrating  applica- 
tion of  microscope  to  metallurgical  work. 

Mr.  E.  Hatschek. — Ultra-filters  for  retaining  ultra-microscopic 
particles.  Collodion  membrances  are  used  as  septa :  according  to 
the  method  of  preparation  they  may  be  used  with  pressure  (Bechhold) 
or  they  may  work  with  hydrostatic  head  only  (Wo.  Ostwald). 

Messrs.  Hawksley  and  Sons. — Microscopes  by  the  Spencer 
Lens  Company  suitable  for  research  work,  students'  models,  also 
travelling  moclel  in  all-metal  case.  Blood  examination  apparatus. 
Thoma-Hawksley  haemacytometers  with  various  rulings. 

Mr.  C.  F.  Hill  and  Mr.  H.  C.  Lancaster. — The  use  of  the 
microscope  in  the  metallography  of  lead.  Typical  samples  of  lead, 
containing  antimony,  tin,  copper,  and  zinc.  Also  a  new  bearing 
metal,  made  of  lead,  containing  calcium  and  barium. 

Miss  Nina  Hosali. — Models  illustrating  crystalline  form  and 
symmetry. 

Messs.  Ilford,  Ltd.  (Mr.  F.  F.  Renwick). — Exhibit  arranged 
to  show  the  range  and  spectrum  of  thirty  colour  filters,  including 
a  set  of  nine  micro-filters,  eight  spectrum  (single-band)  filters,  tri- 
colour filters  and  their  complementaries,  mercury  vapour  lamp  filters 
and  photographic  correction  filters. 

Jaeger  Laboratory  (Mr.  A.  E.  Garrett). — • 

Exhibit  Illustrating  the  Analysis  of  Textiles. 

The  microscope  is  the  final  Court  of  Appeal  in  the  testing  of 
textile  materials  in  so  far  as  the  nature  of  their  constituent  fibres 
is  concerned. 

There  is  no  difficulty  in  dividing  the  more  generally  used  fibres 
into  the  following  distinct  classes:  — 

1.  Wool   and   other   animal  hairs. 

2.  Silk. 

3.  Cotton. 

4.  Other  plant  fibres  (flax,  ramie,  jute,  etc.). 

Classes  1  and  4  are,  however,  as  indicated,  subject  to  much 
subdivision. 

Class  1  contains  wool,  camel  hair,  alpaca,  vicuna,  cashmere, 
mohair,  and  a>  few  less  well-known  hairs.  Class  4  contains  all  the 
multi-cellular  fibres  obtained  from  the  stems  or  leaves  of  plants, 
and  their  number  mounts  up  considerably,  especially  if  those  em- 
ployed for  sacking,  rope,  etc.,  are  included. 

The  distinguishing  features  in  Class  1  are  the  diameter  of  the 
fibres,  the  colour  of  the  pigment  when  present,  the  distribution  of 
the  pigment  cells,  and  scale  structure  or  other  surface  markings. 

In  Class  4  the  diameter  of  the  fibres,  the  nature  of  the  cell 
walls — uniform  thickness,  etc. — the  size  of  the  lumen,  and  super- 
ficial markings  help  in  the  recognition  of  the  fibre.  Polarised  light 
will  often  assist  in  this  section. 

The  microscope  can  also  be  used  to  determine:  — 

(a)  Whether  the  fibres  are  in  their  normal  state  or  have 
undergone  treatment  which  has  altered  their  shape. 
IMercerised  cotton  is  a  good  example. 


APPENDIX    I.  251 

(b)  Whether  coloured  fibres  owe  their  tint  to  natural  pigment 
or   dye.      The   pigment  cells   appear   as   separate   units, 
while  the  dyed  fibres  appear  of  uniform  tint  through- 
out. 
Messrs.    Jeyes'    Sanitary     Compounds     Company,    Ltd.    (Mr. 
W.  C.  Reynolds,  F.I.C). — Illustrating  the  theory  of  emulsions. 

Messrs.    Kodak,   Ltd. — Filters  for   photomicrography,   spectro- 
scopy,   tri-colour   photography,    filter-holders   and    other   photomicro- 
graphical  accessories,  plates  for  photomicrography. 
The  Photomicrographic  Society. — 

Mr.     F.     Martin     Duncan,    F.R.M.S.,    F.R.P.S.,    F.Z.S.— 
Prints  of  low  and  high  power  photomicrographs,   includ- 
ing bacteria,  etc. 
Dr.  G.  H.  Rodman,  F.R.P.S. — Transparencies  of  photomicro- 
graphs of  a  variety  of  subjects,  in  viewing   frame. 
Mr.    E.    a.    Pinchin,    F.R.M.S. — Transparencies     of     photo- 
micrographs of  diatoms,  in  viewing  frame. 
Mr.  F.  Ian  G.  Rawlins. — A  moderate-sized  "  ordinary  "  micro- 
scope, modified  for  use  in  metallography. 
Features  : — 

(a)  Substage    arrangement. 

(b)  Modified    objectives     (converted     to    short     barrel   from 
standard    lenses). 

(c)  Half -watt     lamp,    affording    sufficient    illumination    at 
minimum  expense  and  trouble. 

Mr.   J.  Rheinberg. — Some  Applications  of:  — 

(1)  Filmless  photography. 

(2)  Grainless  photography. 

(3)  Platinised   and  semi-platinised   surface   mirrors. 

Mr.  Sydney  W.  Ross,  F.R.M.S. — A  new  apparatus  for  the 
microscopic  examination  and  photomicrography  of  metallic  specimens 
{two  forms,   drawings  only). 

Research  Department,  Woolwich. • 

(1)  Microscope  with  filar  micrometer  eye-piece,  used   for   the 

measurement  of  small  Brinell  ball  hardness  impressions 
(0.2  to  0.8  millimetre  in  diameter)  to  0.001  millimetre. 

(2)  Photomicrographs  of  structures  found  in  gun-steel,  shell- 

steel,   etc. 
M.    Eugene    Schneider   and   M.    Charles    Florian. — A  micro- 
scope for  measuring  Brinell  depressions.     (Constructed  by  the  Societe 
<l'Optique   et  de  Mecanique  de  Haute  Precision,   Paris.) 

Sheffield  University,  by  kind  permission  of  the  Yice-Chan- 
•cellor,  Sir  W.  H.  Hadow  (Professor  W.  Ripper,  and  Dr.  J.  O. 
Arnold,  F.R.S.). 

Original   Spcriwens    Belonginrf   to    Soil]/. 
(1)  The  following   is   a   description    of     the     Sorby   micro-sec- 
tions :  — 

Dr.  PI.  C.  Sorby's  pioneer  micro-sections  of  iron  and 
steel,  made  in  1863-5. 

Lent  in  1889,  for  Dr.   Sorby's  lifetime,  to  Professor 
J.  O.  Arnold,  F.R.S.,  and  bequeathed  on  Dr.   Sorby's 


252  APPENDIX    I. 

death,  in  1908  to  the  Metallurgical  Department  of  the- 
University  of  Sheffield. 

(Prepared    by   Dr.    H.    C.    Sorby,    F.K.S.,    at 
''  Broomfield/'    Sheffield,   1863-5.) 

(2)  The   gold    copper   series    of     micro-sections     prepared     by 
Professor  J.   O.   Arnold,   F.R.S.  :  — 

Pioneer  sections  made  by  Professor  J.  O.  Arnold,. 
F.R.S. ,  and  Mr.  Joseph  Jefferson  in  1893,  showing 
the.  micrographic  influence  of  small  amounts  of  impuri- 
ties on  the  structure  of  pure  gold  and  copper,  hence 
the  discovery  of  brittle  intercrystalline  cements. 

These     were    fully     described     in     Engineering, 
February   7th,   1896. 

(3)  Framed    signed    portrait   of   the   late    Dr.    H.    C.    Sorbv^- 

F.R.S. 

Professor  Alexander  Silverman  (University  of  Pittsburgh). 
— A  new  illuminator  for  opaque  objects.  (Exhibited  by  Mr.  S.  C,'. 
Akehurst.) 

Dr.  J.  E.  Stead,  F.R.S. — An  improved  form  of  workshop 
microscope  designed  by  Dr.  J.  E.  Stead  and  Messrs.  J.  Swift 
and  Son. 

Series  of  heat-tinted  specimens,  showing  the  structure  of  phos- 
phor etic  steels  and  metals. 

Dr.  Marie  Stores. — The  microscope  as  applied  to  coal  research. 
Illustrated  by  thin  sections  of  coal,  showing  differences  in  texture- 
and  of  plant  content. 

Mr.  J.  Strachan. — The  use  of  the  microscope  in  the  examina- 
tion of  paper-making  materials. 

(1)  A  series    of    slides   showing    various    paper-making    fibres. 

including  both  those  in  common  use  and  a  few  unusual 
fibres  used  during  the  war. 

(2)  A    series    of    slides  showing  dendritic  growths  of  copper 

compound  in  paper,  illustrating  the  application  of  the 
microscope  to  the  study  of  chemical  changes  taking 
place  in  paper  after  its  manufacture. 

Messrs.  James  Swift  and  Son,  Ltd. — Microscopes  for  metal- 
lurgy   and    mineralogy  and    apochromatic  objectives. 

]\[essrs.    Taylor,    Taylor  and    TIgbson,    Ltd. — 

A  microscope  for  measuring  the  diameters  of  depressions  made 
when  testing  the  hardness  of  metals  by  the   Brinell   method. 

The  magnilication  is  16  diameters. 

A  graticule  is  incorporated  enabling  diameters  up  to  about 
7  mm.  to  be  measured. 

The  microscope  stands  on  three  feet,  one  of  them  beiug  a 
cloven  foot,  within  the  notch  of  which  the  object  is  easily  centred 
in  the  field  of  the  microscope.  The  other  two  feet  are  adjustable  up 
and  down  bv  means  of  a  knurled  nut. 


APPENDIX    I.  253 

The  focal  plane  of  the  microscope  coincides  at  all  times  with 
that  of  the  underside  of  the  cloven  foot,  so  that  no  focussinir  is 
iiecessary. 

The  optical  system  is  contained  in  a  single  tnbe,  and  niay  be 
removed  as  a  sepai'ate  unit.  The  ^ield  and  object  glasses  and  the 
graticule  are  held  in  the  tube  l)y  a  novel  and  very  simple  means 
(patented)  without  screws. 

Accuracy  of  the  instrument  is  gnaranteed   within    .01    mm. 

Messrs.  W.  Watson  and  Sons,  Ltd. — Microscopes,  ol)jectives 
aiul  accessory  apparatus. 


APPENDIX    II. 

THE    WORK    OF    THE    FARADAY    SOCIETY, 

And    a    brief    relerence    to    Michael    Faraday, 
BY    THE    PRESIDENT    OF    THE    FARADAY    SOCIETY 

(SIR    ROBERT  HADFIELD,  Bart.,  D.Sc.  D.Met..  F.R.S.) 


As  in  addition  to  our  own  Members,  we  have  a  large  number  of  visitors 
present  to-day,  I  thought  it  would  be  of  interest  to  write  a  short 
account  of  the  work  of  our  Society,  which  takes  its  name  from  one  of 
the  greatest  of  the  Scientific  Inunortals — Michael  Faraday.  I  need 
hardly  say  how  glad  we  shall  be  to  receive  an  access  to  our  Membership 
of  those  interested  in  the  work  we  are  trying  to  accomplish,  which  is 
not  only  that  of  covering  certain  ground  not  dealt  with  by  other 
Scientific  Societies,  but  also  of  arousing  interest  in  the  minds  of  the 
younger  men  in  our  great  Metropolis  and  elsewhere  with  regard  to 
Scientific  developments. 

I  also  take  this  opportunity  of  saying  a  few  words  about  Faraday, 
who  devoted  his  life  to  Science,  with  but  one  single  aim — to  advance 
its  position  in  the  world,  and  to  benefit  Mankind  without  fear  or 
favour  to  rich  and  poor  alike.  No  monetary  or  selfish  considerations 
ever  entered  his  mind. 

At  the  time  I  accepted  the  invitation  of  the  Council  in  1914, 
conveyed  through  my  friend,  Professor  A.  K.  Huntington,  to  be  your 
President,  I  was  not  in  good  health,  and  the  duties  seemed  to  be 
far  too  great  for  me  to  undertake.  I  felt,  however,  that  it  was  a  special 
honour  and  privilege  to  be  asked  to  follow  in  the  footsteps  of  some 
of  our  great  Masters  of  the  Past — Kelvin,  Swan,  and  others— so  I 
accepted. 

When  delivering  my  Presidential  Address  in  June,  1914,  I  little 
dreamt  that  our  Empire  was  so  soon  to  pass  through  a  time  of  un- 
exampled stress.  Notwithstanding  the  difficulties  with  which  those  five 
troublous  years  were  surrounded,  I  am  glad  to  say  our  work  never 
relaxed,  and  I  do  not  think  we  suspended  a  single  meeting, 
Council,  Committee,  or  General.  Thanks  to  the  willing  help  given 
on  all  hands,  whether  by  the  Council,  by  the  Members,  or  by  our 
Secretary,  Mr.  F.  S.  Spiers,  it  has  given  me  no  little  satisfaction  to 
think  that  the  younger  men  amongst  us  have  bivn  aided  in  their 
work  by  our  Society  and  its  gatlioiings. 

My  work  with  the  Faraday  Society  has  been  a  labour  of  love. 
The  time  is,  however,  coming  when  I  am  sure  you  must  think  it 
only  right  that  another  of  your  Members  should  take  my  place  as 
President.  Let  me  add  that  I  have  only  been  too  glad  to  give  any 
help  in  my  power,  and  its  future  will  always  have  the  warmest  interest 
of  my  heart. 

254 


APPENDIX    II.  255 

Our  Society  owed  its  origin  in  1902,  chiefly  to  a  little  band  of 
workers  who  met  together  to  advance  the  great  cause  of  Scientific 
Knowledge.  It  was  founded  on  February  4th,  1903  at  a  meeting 
in  the  rooms  of  the  now  defunct  Faraday  Club,  held  at  St.  Ermin's 
Hotel,  Westminster.  Amongst  its  founders  were  Mr.  Sherard  Cowper- 
Coles,  Mr.  W.  R.  Coo^Dcr,  Professor  F.  G.  Donnan,  Dr.  F.  M.  Perkin, 
Mr.  Alexander  Siemens,  Mr.  James  Swinburne,  and  Mr.  F.  S.  Spiers, 
our  present  Secretary,  to  whom  we  owe  a  deep  debt  of  gratitude  for 
his  indefatigable  work  on  behalf  of  our  Society,  and  to  whom  there 
should  be  accorded  a  crown  of  laurels.  To  each  of  these  Founders  I 
have  sent  a  special  invitation  asking  them  to  be  present  this  evening. 

Our  first  President  was  Sir  Joseph  Swan,  F.R.S.,  later  Lord  Kelvin, 
followed  by  Sir  William  Perkin,  F.R.S.,  Sir  Oliver  Lodge,  F.R.S., 
Mr.  J.  Swinburne,  F.R.S.,  and  Sir  R.  T.  Glazebrook,  F.R.S.,  whose 
portraits  are  given  in  the  accompanying  plate.  The  objects  of  the 
[  Society  as  originally  defined  were  to  promote  the  study  of  Electro- 
^  chemistry,  Electrometallurgy,  Physical  Chemistry,  Metallography, 
and  kindred  subjects. 

I  venture  to  think  that  we  are  accomplishing  the  objects  for  which 
its  founders  set  out,  and  that  the  Faraday  Society  will  continue  to 
increase  and  flourish.  It  is,  however,  very  desirable  that  we  should 
extend  our  Membership,  and  I  trust  a  great  effort  will  be  made  by 
every  present  Member  to  bring  in  at  least  another  new  Member, 
also  that  many  of  our  Visitors  to-night  will  join  our  Roll  Call. 
Stagnation  in  any  Society  means  final  decay.  If  we  fulfil  a  useful 
purpose,  as  we  undoubtedly  do,  then  the  aim  I  have  set  forth  of  a 
large  increase  in  Membership  ought  to  be  possible.  In  one  important 
Technical  Society  in  America,  I  learn  they  have  this  year  increased 
their  Roll  Call  by  no  less  than  one  thousand  new  Members. 

Our  Society  is  honoured  and  recognised  in  the  Councils  of  the 
larger  and  parent  Societies.  It  has  a  seat  on  the  Conjoint 
"  Board  of  Scientific  Societies  and  is  consulted  along  with 
other  Societies  on  tlie  special  subjects  with  which  we  deal 
and  are  acquainted.  The  fact  that  the  Royal  Society  has  this  evening 
granted  us  the  privilege  of  holding  our  Symposium  in  its  historic 
building  also  shows,  I  venture  to  think,  that  our  work  meets  with  the 
approval  of  this  great  parent  body  of  Scientists. 

Nitrogen  Products  Com^nittee. — I  will  refer  to  one  subject  in  which 
we  gave  a  helj^ing  hand  during  the  War — in  fact  it  might  be  said  that 
the  Faraday  Society  originated  this  special  Research  in  this  Country, 
namely,  that  relating  to  Nitrogen  Products,  which  mainly  through  our 
suggestion  was  taken  up  by  the  Munitions  Inventions  Board .  My  friend, 
Professor  Huntington,  of  King's  College,  worked  in  season  and  out  of 
season  to  get  the  Government  Department  concerned  interested.  He 
finally  succeeded  in  persuading  the  Munitions  Inventions  Department 
to  appoint  a  Special  Nitrogen  Products  Committee,  who  in  their  turn 
were  instrumental  in  establishing  a  Research  Department.  As  Mr. 
H.  W.  Dickinson,  Secretary  of  the  M.I.D.,  points  out,  so  much  spade 
work  was  done  by  the  Department  with  regard  to  this  subject  that 


256  APPENDIX    it. 

when  at  a  later  date  owing  to  the  submarine  campaign  the  policy  of 
the  Ministry  changed  and  it  was  decided  to  go  to  new  sources  for 
Nitrogen  supply,  the  results  of  the  research  work  and  of  the  informa- 
tion gathered  by  the  Research  Department  mentioned  were  ready  to 
hand  and  enabled  practical  work  on  a  large  experimental  scale  to  be 
conmienced  at  once. 

It  should  be  added  that  tlic'work  was  taken  up  for  the  Conunittee 
by  one  of  our  Members  of  Council,  Dr.  J.  A.  Harker,  F.R.S.,  who  was 
aih)wedby  the  National  Physical  Laboratory  to  assist  in  this  important 
development,  his  labours  being  of  the  highest  value.  The  Country  is 
greatly  indebted  to  him  for  the  untiring  devotion  he  has  shown  in 
working  out  this  special  and  important  subject  to  a  successfid  issue. 
Our  Council  hope  that  before  long  they  will  be  able  to  jn-esent  a  Report 
to  us  describing  in  detail  the  work  carried  out.  The  Report  of  the 
Committee  itself  is  shortly  to  be  published,  and  it  will  probably  be 
one  of  the  most  remarkable  documents  in  regard  both  to  scope  and 
matter  that  has  been  issued  by  a  Government  Department  during 
those  troublous  times. 

The  work  done,  although  not  immediately  made  use  of  for  War 
jHirposes,  as  the  Armistice  rendered  any  help  needless  in  this  quarter, 
will,  without  doubt,  bear  great  fruit  in  the  future  ;  in  fact,  the  Nitrogen 
Factory,  which  was  being  started  during  the  War,  has  already  been 
taken  over  by  a  private  organisation.  It  is  therefore  probable  that 
the  Nitric  Acid  required  in  this  Country  for  making  explosives,  dyes 
and  drugs  will  be  produced  synthetically  in  this  manner. 

Sijinposia  jjreviously  held. — Since  the  formation  of  the  Faraday 
Society,  we  have  had  approximately  330  papers  presented  to  us,  most 
of  them  fully  discussed.  During  my  own  term  of  office — 1914  to  I9I9 
— some  180  papers  have  been  read,  and,  including  the  present  one, 
there  have  been  fifteen  Symposia  held,  attended  by  considerably 
over  3,'XO  Members  and  Visitors.  The  following  shows  these  in 
tabular  form  : — 

Title. 

The  Hardening  of  Metals. 

The  Transformations  of  Pure  Iron. 

The  Corrosion  of  Metals. 

Methods    and   Appliances    for   the  Attainmeiif    of 
High  Temperatures  in  the  Laboratory. 

Refractory  Materials. 

The  Training  and  Work  of  the  Chemical  Engineer. 

Osmotic  Pressure. 

Pyroineters  and  Pyrometry. 

The  Setting  of  Cements  ami  Plasteis. 

lOlectric  Furnaces.     (Synq)osium  at  Manchester.) 

The  (V)-()rdination  of  Scientific  Publication. 

The  Occlusion  of  Gases  by  Metals. 

The  Present  Position  of  the  Theory  of  lonisation. 

Radiometallogr.iphy. 


No. 

Date. 

1 

Nov., 

J911 

2 

Oct., 

1915 

3 

Dec, 

1915 

I 

Mar., 

1916 

5 

Nov.. 

1910 

0 

Mar., 

1917 

7 

May, 

1917 

8 

NoV.. 

1917 

9 

.Jan.. 

1918 

10 

K.'b.. 

1918 

11 

Mav, 

1918 

1-J 

Nov., 

1918 

13 

Jan., 

1919 

14 

April 

,  1919 

THE    FARADAY    SOCIETY 

and  six  of  its  Past  Presidents. 


Sir  JOSEPH   SWAN 
(First  President) 

V.m     1904 


Lord  KELVIN 
(Second  I'resident) 

i905-l'JU7 


Sir  WILLIAM  PEKKIN 

1907  -1908 


Sir  OLIVER   LODGE 

190.S-1909 


MICHAEL  FARADAY 

17;JI-1«G7 


JAMES  SWINBURNE 

1910-1911 


Sir  RICHARD  GLAZEBROOK 

191^-1913 


APPENDIX    II.  257 

It  is  hoped  that  the  present  Symposium  will  be  no  less  successful  than 
previous  ones.  Many  Members  and  others  at  home  and  abroad  have 
expressed  their  thanks  for  the  useful  work  done  by  our  Society.  We 
have  also  tried  to  give  a  ]iel]iino  liand  and  encouragement  to  the 
younger  men  in  our  midst.  This  lias  been  one  of  the  chief  objects 
we  have  always  had  specially  in  mind.  Let  our  motto  be  "  Thorough- 
ness," and  we  shall  continue  to  flourish  and  do  still  better  work  in 
the  future. 

The  Woi'h  of  Michael  Faraday. — Turning  now  for  a  moment  to 
Michael  Faraday,  from  whom  our  Society  takes  its  name,  I  will 
a  little  later  on  refer  to  one  of  the  descriptions  of  the  Great  Scientist, 
by  Professor  John  Tyndall,  F.K.S.,  in  his  lecture  before  the  Koyal 
Institution  in  January,    1863,    on  "  Faraday  as  a  Discoverer." 

De  la  Rive,  the  well-known  French  Scientist  in  his  "  Notice  on 
Faraday's  Life  and  Work,"  Archives  des  Sciences  de  la  Bibliothcque 
Universelle,  October,  1867,  stated  that  the  number  of  Faraday's 
Memoirs  from  1820  to  1855,  all  of  these  important,  was  almost  in- 
credible. 

Faraday  w^as  born  at  Newington  Butts  on  the  22nd  September, 
1791,  aiid  finally  passed  away  at  Hampton  Court  on  the  25th 
August,  1867. 

Tyndall  said  that  it  seemed  desirable  to  give  the  world  some 
image  of  Michael  Faraday  as  a  scientific  investigator  and  discoverer. 
He  regarded  the  attempt  to  respond  to  this  desire,  whilst  a  labour  of 
difficulty  in  adequately  jjresenting  a  history  of  this  great  man,  as  also 
a  labour  of  love.  However  well  acquainted  he  might  be  with  the 
researches  and  discoveries  of  the  great  mastei' — however  numerous 
the  illustrations  which  occur  to  him  of  the  loftiness  of  Faraday's 
character  and  the  beauty  of  his  life — still  to  grasp  him  and  his  re- 
searches as  a  whole  ;  to  seize  upon  the  ideas  which  guided  him  and 
connect  them  ;  to  gain  entrance  into  that  strong  and  active  brain 
and  read  from  it  the  riddle  of  the  world — was  a  work  not  easy  of 
performance.  As  he  was  a  believer  in  the  general  truth  of  the  doctrine 
of  hereditary  transmission,  Tyndall,  w^ho  shared  the  opinion  of  Carlyle 
that  a  really  able  man  never  proceeded  from  entirely  stupid  parents — 
said  that  he  once  used  the  privilege  of  his  intimacy  with  Faraday  to 
ask  him  whether  his  parents  showed  any  signs  of  unusual  ability.  He 
could  remember  none.  His  father  was  a  great  sufferer  during  the  later 
years  of  his  life,  and  this  might  have  masked  whatever  intellectual 
power  he  possessed.  When  thirteen  years  old,  that  is  to  say  in  1804, 
Faraday  was  apprenticed  to  a  book-binder  in  Blandford  Street, 
Manchester  Square  ;  here  he  spent  eight  years  of  his  life,  after  whi(h 
he  worked  as  a  journeyman  elsewhere. 

Faraday  was  only  22  years  of  age  when  he  obtained  a  position  in 
the  Royal  Institution.  His  first  contribution  to  Science  appeared 
in  the  Journal  of  the  Royal  Institution  in  1816,  that  is,  in  the  publica- 
tion known  as  the  "  Quarterly  Journal  of  Science."  I  thought  it  might 
be  of  interest  to  give  the  following  summaries  by  Tyndall  of  (1) 
Researches  by  Faraday,  and  (2)  Discoveries  by  Faraday  :-^ 


258 


APPENDIX    II. 


RESEARCHES  BY   FARADAY 


PUBLISHED 
from 


First    contribution    to    Science — Analysis    of    Caustic    Li 
Tuscany 

Experiments  on  Sounding  Flames 

Vaporisation  of  Mercury  at  Ordinary  Temperatures    ... 

On  the  Limits  of  Vaporisation 

Experiments  on  Alloys  of  Steel 

ATbrating    Surfaces 

On  the   Quantitative   Comparison  of  different   forms  of  Electricity 

On.  the  Absolute  Quantiy  of  Electricity  associated  Avith  the  particles 
or  Atoms  of  Matter        

The   Power  of  Metals  and  other  Solids  to   induce  the  combination 
of    gaseo'us    Bodies 

Extra  Current — The  influence  by  induction  of  an   Electric  Current 
upon   itself 

On    Frictional    Electricity,    Induction,    Conduction,    Sj^ecific    Con- 
ductive  Capacity,  and  Theory  of    Contiguous   Particles      1835  to  1838 

Further  Researches  on  Liquefaction  of  Gases — 

Establishing  the  fact  that  Gases  are  vapours  of  Liquids  possess 
ing  very  Ioav  boiling  points 

Speculations  on  the  Nature  of  Matter  and  Lines  of  Force    ... 

On  the  Diamagnetic  Condition  of  Flame  and  (lases 

On  Magne-Crystallic  Action  and  Lines  of  Force 

Magnetism  of  Gases ... 

Atmospheric  Magnetism 

Electricity   of   Gymnotus      

Source  of  Power  of  the  Hydro-Electric  Machine 

Regelation 


1816 
1818 
1821 


182Q 
1833 


1835 


1844 

...     1846 

...     1847 

1848  to  1851 

...      1850 


DISCOVERIES   BY  FARADAY. 


-Chlorine.   Carbon  and   Iodine 


PUBLISIJED 
Carbon  and 


Two  ,new  Compounds 

Hydrogen 

Alloys  of  Steel  

Magnetic   Rotations     ... 
Liquefaction    of    Gases 

Change  of  colour  of  Glass  in   Sunlight  

New  Compounds  of  Hydrogen  and  Carlx)n       

Benzol       

Improvements     in     manufacture    of    Glass    for    Optical     purposes. 

.■\fterwards  the  foundation  of  most  important  Discoveries,  e.g., 

Magnetisation  of  Light  ... 
Peculiar  class  of  optical   deceptions~<)i)tical   toy,   the   Chromotrope 

owed  its  origin  to  this     ... 
Magneto-Electric      Induction — Tyndall      says  :      '-Greatc^st     experi- 
mental   result   ever  obtained  by   an    invesiigator.      The    '  Mont 

lilanc'  of   Faraday's   achievements"... 

Terrestrial    Magneto-Electric    Induction  

Identities  of   I'Jcctricities — Static,   Voltaic,   M: 

New  Law  of  IClectric  Induction 

Laws  of   Electro-Chemical   l)ec<jm|)o>iti()ii    -  |)(>iinite   l-.lec  tro-Chemi- 

cal  J)ecomposition.      Tyndall  ->ays  :   "This  Law   ranks  in  im])ort- 

ancc    with     that    ^d'     llic     Ddiniic     Combining     I'l  opoi  tions    in 

Chemistry" 

Origin    of   Power  in   the   Voltaic   Pile      

Magnetisation    of.  Light    and    th<^     illumination    of    the 

Magnetic   Force.      In    other  words,    the    Rotation    of 

of  Polarisation 
Diamagnetism  or  the  Magnetic  Condition  of  all  Matt(>r 
Atmospheric   Magnetism        , 


Lines    of 
the    Plane 


1820 
1821 

1823 
1825 
1826 


1820 


neto,   Thermo,    etc.      1833 


1834 

1845 
1850 


APPENDIX    II.  259 

SUMMARY    OF    FARADAY'S    WORK. 

I  will  also  (juote  Tyndairs  Suniiuary  of  Faraday's  work  sojiKnvhal 
fully  as  it  is  indeed  worth  reading.  It  is  a  stimulus  to  each  of  us 
according  to  his  light  to  go  and  try  to  do  likewise,  even  if  in  a  smaller 
and  humbler  way. 

Tyndall  says  : 

"  When  from  an  Alpuie  height  the  eye  of  the  climber  ranges  over 
the  mountains,  he  finds  that  for  the  most  part  they  resolve  themselves 
into  direct  groups,  each  consisting  of  a  dominant  mass  surrounded 
by  peaks  of  lesser  elevation.  The  power  which  lifted  the  mightier 
eminences,  in  nearly  all  cases,  lifted  others  to  an  almost  equal  height. 
And  so  it  is  with  the  discoveries  of  Faraday.  As  a  general  rule,  the 
dominant  result  does  not  stand  alone,  but  forms  the  culminating  point 
of  a  vast  and  varied  mass  of  enquiry. 

In  this  way,  round  about  his  great  discovery  of  Magneto-Electric 
Induction,  other  weighty  labours  grouped  themselves.  His  investiga- 
tions on  the  Extra  Current  ;  on  the  Polar  and  other  conditions  of 
Diamagnetic  Bodies  ;  on  Lines  of  Magnetic  Force,  their  definite 
character  and  distribution ;  on  the  employment  of  the  Induced  Magneto- 
Electric  Current  as  a  measure  and  test  of  Magnetic  Action  ;  on  the 
Repulsive  Phenomena  of  the  Magnetic  Field,  are  all,  notwithstanding 
the  diversity  of  title,  researches  in  the  domain  of  Magneto-Electric 
induction. 

Faraday's  second  group  of  Researches  and  Discoveries  embraced 
the  chemical  phenomena  of  the  current.  The  dominant  result  here 
is  the  great  Law  of  Definite  Electro-Chemical  Decomposition,  around 
which  are  massed  various  Researches  on  Electro-Chemical  Conduction, 
and  on  Electrolysis  both  with  the  Machine  and  with  the  Pile.  To 
this  group  also  belong  his  Analysis  of  the  Contact  Theory  ;  his 
Inquiries  as  to  the  Source  of  Voltaic  Electricity,  and  his  final  develop- 
ment of  the  Chemical  Theory  of  the  Voltaic  Pile. 

His  third  great  discovery  is  the  Magnetisation  of  Light,  which  may 
be  likened  to  the  Weisshorn  among  mountains — high,  beautiful, 
and  alone. 

The  dominant  result  of  his  fourth  grou])  of  Researches  is  the  dis- 
covery of  Diamagnetism,  announced  in  his  Memoir  as  the  Magnetic 
Condition  of  all  Matter,  round  which  are  grouped  his  enquiries  on 
the  Magnetism  of  Flame  and  Gases  ;  on  Magne-Crystallic  Action, 
and  on  Atmospheric  Magnetism,  in  its  relation  to  the  annual  and 
diurnal  variation  of  the  needle,  the  full  significance  of  which  is  still 
to  be  shown. 

These  are  Faraday's  most  massive  discoveries,  and  upon  them 
his  fame  must  mainly  rest.  But  even  without  them,  sufficient  would 
remain  to  secure  for  him  a  high  and  lasting  scientific  reputation. 
We  should  still  have  his  Researches  on  the  Liquefaction  of  Gases  ; 
on  Frictional  Eie  t  ricity  ;  on  the  Electricity  of  the  Gymnotus  ;  on 
the  Source  of  Power  in  the  Hydro-Electric  Machine  ;    on  the  Electro- 


260  APPENDIX    II. 

Magnetic  Rotations  ;  on  Regelation  ;  all  his  more  purely  Chemical 
Researches,  including  his  discovery  of  Benzol.  Besides  these  he 
published  a  multitude  of  minor  papers,  most  of  which  in  the  same 
way  illustrate  his  genius." 

Tyndall  adds  that  no  allusion  is  here  made  to  his  power  as  a 
Lecturer.  Taking  him  all  in  all,  it  will  be  conceded  that  Michael 
Faraday  was  probably  the  greatest  experimental  Philosopher  the 
world  has  ever  seen.  The  progress  of  future  research  will  tend  not 
to  dim  or  diminish,  but  to  enhance  and  glorify  the  labours  of  this 
mighty  investigator. 

Speaking  with  regard  to  my  own  lines  of  research,  as  repre- 
senting the  Faculty  of  Metallurgy,  I  may  mention  that  Faraday, 
in  his  experiments  on  Alloys  of  Iron  with  other  Elements,  in  other 
words  the  production  of  Alloy  Steel,  carried  out  in  1821  and  1822, 
showed  that  a  remarkable  inspiration  evidently  existed  in  his 
mind  as  to  the  great  future  this  line  of  research  work  presented. 
Singular  to  say  it  is  just  about  100  years  ago  that  Faraday  wrote 
several  letters  from  the  Royal  Institution  (in  April  and  June,  1820). 
to  his  Swiss  friend  De  la  Rive,  Professor  of  Chemistry,  Geneva,  in 
which  he  gave  an  account  of  some  experiments  on  Steel  made  by 
himself  and  Stodart.  The  world's  great  technical  advances  during 
the  last  thirty  years  have  been — and  I  say  it  unhesitatingly — in  a 
large  measure  due  to  the  introduction  of  Alloy  Steels  such 
as  Faraday  had  in  mind.  As  already  mentioned,  Faraday, 
with  Stodart,  started  these  researches  at  the  Royal  Institution, 
finally  completing  the  experiments  by  sending  his  various 
mixtures  to  be  melted  at  the  Sanderson  Works  in  Sheffield,  this  Firm 
being  still  in  existence  to-day.  The  specimens  had  to  be  sent  by 
coach,  the  work  being  given  to  a  trusty  assistant  who  had  to  go 
down  and  see  the  experiments  put  in  hand  and  completed. 
Beyond  the  work  of  Mushet  this  particular  land  of  Research  lay 
fallow  for  many  years,  in  fact  it  was  my  own  discovery  and 
invention  of  Manganese  Steel  in  1882  which  showed  that  the 
new  world  already  indicated  by  Faraday  was  there  ready  to  be 
explored.  This  exploration  has  rapidly  taken  place  during  the 
last  thirty  years,  including  the  discovery  and  invention  of  Chromium 
Steel,  Silicon  Steel,  Nickel  Steel,  Tungsten  Steel,  High-speed  Tool 
Steel,  Non-corroding,  and  many  other  types  of  Steels. 

Almost  as  important  was  the  fact  that  Alloy  Steel  necessitated 
special  heat  treatment,  which  again  recjuired  and  called  for  the  use  of 
scientific  methods  for  the  determination  of  temperatures,  critical  points, 
microstructure  study,  improved  analytical  methods,  media  nical 
testing,  hardness  determination,  observation  of  electrical  conductivity, 
magnetic  susceptibility,  electrical  resistance,  hysteresis  effects  and 
other  qualities. 

In  conclusion,  this  Society  is  indeed  honoured  in  being  allowed  to 
Ijear  the  name  of  so  great  a  man  as  Faraday,  whose  work  is  still 
benefiting  our  Empire. 


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