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Officers and Cofncil, 1923-24 v 

Local Officers. -Liverpool, 1923 vii 

Sections and .Sectional Officers, Liverpool, 1923 viii 

Annual Meetings : Places and Dates, Presidents, Attendances, 
Receipts, Sums paid on account of Grants for Scientific 
Purposes (1831-1923) x 

Report of the Council to the General Committee (1922-23) xiv 

British Association Exhibitions xviii 

General Meetings, Scientific Exhibition, and Soiree at Liverpool xviii 

Public Lectures in Liverpool and Neighbourhood xix 

Children's Lectures in Liverpool xx 

General Treasurer's Account (1922-23) xxii 

Research Committees (1923-24) xxvi 

Caird Fund xxxi 

Resolutions and Recommendations (Liverpool Meeting) xxxii 

The Presidential Address : 

The Electrical Structure of Matter. By Sir Ernest Rutherford, 

F.R.S 1 

Sectional Presidents' Addresses : 

A. — On the Origin of Spectra. By Prof. J. C. McLennan, F.R.S. . . 25 

B. — Some Aspects of the Phj'sical Chemistry of Interfaces. Bjf Prof. 

F. G. Donnan, F.R.S 59 

C. — Evohitional Palaeontology in Relation to the Louver Pala'ozoic 

Rocks. By Dr. Gertrude L. Elles, M.B.E 83 

D. — Modern Zoology : Some of its Developments and its Bearings on 

Human Welfare. By Prof. J. H. Ashworth, F.R.S 108 

E. — The Geographical Position of the British Empire. By Dr. 

Vaughan Cornish 126 

F. — Population and Unemployment. Bv Sir W. H. Beveridge, 

K.C.B ". 138 

A 2 



G. — Transport and its Indebtedness to Science. By Sir Heney 

FowLEK, K.B.E 162 

H. — Egypt as a Field for Anthropological Research. By Prof. P. E. 

Newberry, O.B.E 175 

I. — Symbiosis in Animals and Plants. By Prof. G. H. F. Nuttall, 

'F.R.S. 197 

J. — The Mental Differences between Individuals. By Dj. C. Burt 215 

K.— The Present Position of Botany. By A. G. Tansley, F.R.S.. . 240 

L.— Education of the People. By Principal T. P. Nunn 261 

M. — Science and the Agricultural Crisis. By Dr. C. Ckowther .... 273 

Reports on the State of Science, etc 283 

Sectional Transactions 424 

References to Publication of Communications to the Sections . . 503 

Remarks on Quantisation. By Prof. P. Ehbsnfest 508 

The Structure of Atoms and their Magnetic Properties. By 

Prof. P. Langevin 511 

Corresponding Societies Committee's Report 512 

Conference of Delegates of Corresponding Societies 513 

List of Papers, 1922, on Zoology, Botany, and Prehistoric 

Archeology of the British Isles. By T. Sheppard 515 

Index 579 

Sritisb ^.ssatiatinn for Ibt ^bbaiucmcnt 
0f Sticntc. 




Professor Sir Ernest Et;thekford, D.Sc, LL.D., F.R.S. 

Major-Gen. yir David Bruce, A.:\r.S., K.C.B., D.Sc, LL.D., f.R.S. 


The Right Hon. the Lord Mayor of 

Liverpool (Frank C. Wilson). 
Tlie Right Hon. the Earl of Derby, 

KG., G.C.V.O., P.O. 
The Right Hon. the Earl of Sefton, 

The Lord Bishop of Liverpool (Rt. 

Rev. F. J. Chavasse. D.D.). 
The Archbishop of Liverpool (jNIost 

Rev. F. Wm. Keating, C.M.G.). 
The Rt. Hon. Viscount Leverhulme, 

Sir William Herdman, C.B.E., D.Sc. 

LL.D., F.R.S. 

The Vice-Chancellor of the Uni- 
versity OF Liverpool (J. G. Adami, 
C.B.E., M.D., Sc.D.,LL.D.,F.E.S.). 

The President of the Council of the 
University of Liverpool (Hugh R. 
Rathbone, jM.A.). 

The Chairman of the Mersey Docks 
AND Harbour Board (Thomas 

The Right Hon. the Marquis of 
Salisbury, K.G., G.C.V.O. 

The Right Hon. the Earl of Lathoji. 


H.E. the Governor-General op 

Canada (Rt. Hon. Lord Byng of 

ViMY, G.C.B., C^.C.M.G.). 
His Hon. the Lieutenant-Governor 

of Ontario (Harry Cockshut). 
Rt. Hon. the Prime JNIinister of 

Canada (W. L. [Mackenzie King, 

C.:\r.G., LL.D.). 
The Hon. the Speaker of the House 

OF Commons (Hon. Rodolphe 

Tlie Hon. the High Commissioner for 

Canada (P. C. Larkin). 
The Hon. the Prime ^Einister and 

iliNisTER OF Education, Ontario 

(G. Howard Ferguson, LL.B.). 
His Worsliip the ]\Iayor op Toronto 

(G. A. Maguire). 
'I'lie Chancellor of the University 

OP Toronto (Sir Edmund Walker, 

C.V.O., LL.D., D.C.L.). 

Tlie Chairman of the Board of 
Governors, University of Toronto 
(Rev. Canon H. J. Cody, B.D., 

The President of the University 
of Toronto (Sir Robert Falconer, 
K.C.IvI.G., D.Litt., LL.D.). 

The President of the Royal Canadian 
Institute (Prof. J. C. Fields, 
Ph.D., F.R.S.). 

The President of the Canadian 
National Railways (Sir Henry W. 
Thornton, K.B.E.). 

The President of the Canadian 
Pacific Railway (E. W. Beatty). 

The Chairman of the Local General 
AND Executive Committee (Prof. 
J. C. McLennan. C.B.E.. Ph.D., 
D.Sc. LL.D.. F.R.S.V 



E. H. Griffiths, Sc.B., D.Sc, LL.D., F.R.S. 


Professor J. L. Myres, O.B.E., M.A., I F. E. Smith, C.B.E., F.R.S. 
D.Sc, F.S.A., F.B.A. | 


0. J. R. HowARTH, O.B.E., M.A., Builingtoii House. Londuii, W. 1. 



Professor J. C. ^^IcLennan, F.R.S. 


Professor J. C. Fields. F.R.S. 
Profes,sor J. J. R. :\lACLEOn. M.B., Ch.B.. D.P.H. 

Major .J. :Sl. :\foOD, O.B.E., M.C. 


F. A. INrouRE. ^Ius.D(K-. 


Dr. F. W. Aston, F.R.S. 

J. Barcroft, F.R.S. 

Sir W. H. Beveridge, K.C.B., F.R.S. 

Rt. Hon. Lord Bledisloe, K.B.E. 

Professor W. Dalby. F.R.S. 

Professor C. H. Desch, F.R.S. 

E. N. Fallaize. 

Dr. J. S. Flctt. O.B.E., F.R.S. 

Professor H. J. Fleure. 

Professor A. Fowler, F.R.S. 

Sir R. A. Gregory. 

Sir Daniel Hall, K.C.B., F.R.S. 

C. T. Heycock, F.R.S. 

Dr. W. E. Hoyle. 

J. H. Jeans, F.R.S. 

Sir A. Keith. F.R.S. 

Sir J. Scott Keltie. 

Professor A. W. Kirkaldy. 

Dr. P. Chalmers Mitchell, C.B.E. 

F R S 
Dr.'c! S. Myers, F.R.S. 
Professor A. W. Porter, F'.R.S. 
Professor A. C. Seavard, 'F.R.S. 
Prof. A. Smithells, C.^M.G., F.R.S. 
A. G. Tansley, F.R.S. 
W. Whitaker, F.R.S. 


The Trustees, past Presidents of the Association, tlie President for tiie 
year, the President and Vice-Presidents for the ensuing Annual ^Meeting, past 
and present General Treasurers and General Secretaries, past Assistant General 
Secretaries, and the Local Treasurers and Local Secretaries for the Annual 
Meetings immediately past and ensuing. 


Major P. A. MacMahox, D.Sc, | Sir Arthur Evans. INl.A., LL.D., 
LL.D., F.R.S. I F.R.S., F.S.A. 


l.ft. ±i.i4.b., J^.S.A. 

. Sir Charles A. Parsons, K.C.B., LL.D., D.Sc, F.R.S. 



Sir A. Geikie, K.C.B., O.M., F.R.S. i Sir Arthue Schuster, F.R.S. 

Rt. Hon. the Earl of Balfour, O.M., ' Sir Arthur Evans, F.R.S. 

F.R.S. Hon. Sir C. A. Parsons, K.G.B., 

Sir E. Ray Lankester, K.C.B., F.R.S. F.R.S. 

Sir Francis Darwin, F.R.S. Sir William A. Herdman, C.B.E., 

Sir J. J. Thompson, O.M., F.R.S. F.R.S. 

Sir E. Sharpey Schafer, F.R.S. Sir T. Edward Thorpe, C.B., F.R.S. 

Sir Oliver Lodge, F.R.S. Prof. Sir V. S. Sherrington, G.B.E., 

Professor W. Bateson, F.R.S. Pres.R.S. 


Sir E. Sharpey Schafer, F.R.S. 
Dr. D. H. Scott, F.R.S. 
Dr. J. G. Garson. 

Major P. A. MacMahon. F.R.S. 

Sir W. A. Herdman, C.B.E., F.R.S. 

Professor H. H. Turner, F.R.S. 


Professor A. BowLEY. I Professor A. W. Kirkaldy. 



The Rt. Hon. tlie Lord ]Mayor. 


Sir William Herdman, C.B.E., D.Sc, LL.D., F.R.S. 
C. Sydney Jones, M.A. 


Alfred Holt, D.Sc. 

Walter ^NIoon, Town Clerk of Liverpool. 

Edwin Thompson. 


J. Howard Roberts. 

Charles Booth, ~S\.A. 





President.— Proi. J. C. McLennan, F.R.S. 

Vice-Presidents.— Fvoi: W. L. Bragg, F.R.S. ; Prof. G. H. Hardt, 'F.R.S.; 
Prof. A. W. Porter, F.R.S. ; Prof. J. Proudman; Prof. L. R. 


Recorder. — Prof. A. 0. Rankine. 

Secretaries.— M. A. Giblett ; Prof. H. R. Hasse; ,J. Jackson; Prof. A. 'M. 

Local Secretary. — J. Rice. 


President.— Vi-oi. F. G. Donnan, C.B.E., F.R.S. 

Vice-Presidents.— T)T. E. F. Armstrong, F.R.S. ; Prof. E. C. C. TJalv, 

C.B.E., F.R.S.; PrincipalJ. C. Irvine, C.B.E., F.R.S. 
Recorder. — Prof. C. H, Desch. 

Secretaries. — Dr. H. McCombie; Dr. E. H. Tripp. 
Local Secretary. — Prof. I. 'SI. Heilbron. 


President. — Dr. Gertrude Elles, ]M.B.E. 

Vice-Presidents.— Pi-oi. P. G. H. Bosvvell, O.B.E. ; Dr. J. S. Flett. O.B.E.. 

F.R.S. ; W. Hewitt; Prof. P. F. Kendall; Prof. W. J. Sollas. F.R.S. : 

Sir A. Strahan, K.B.E., F.R.S. 
Recorder. — Dr. A. R. Dwerrthouse. 
Secretaries. — Prof. W. T. Gordon: Prof. G. Hickling. 
Local Secretary. — W. Hewitt. 


President. — Prof. J. H. Ashwortji, F.R.S. 

Vice-Presidents.— Dr. E. J. Allen, F.R.S.: Prof. .J. Johnstone; Dr. T. 

Mor'tensen ; Prof. R. Newstead. 
Recorder. — Prof. R. D. Laurie. 

Secretaries. — 'F. Balfour Browne; Dr. W. T. C\lman. 
Local Secretary. — Prof. \Y. J. Dakin. 


President. — Dr. Vaughan Cornish. 

Vice-Pre.?idents. — Charles Booth; G. G. Chisholm ; Prof. H. J. Fleure : 
CoL H. G. Lyons, F.R.S.; Dr. :\Iarion Neweigin ; Prof. P. :M. Roxby. 
Recorder. — Dr. R. N. Rudmose Brown. 
Secretaries. — W. H. Barker ; F. Debenham. 
Local Secretary. — R. H. Kinvig. 


President.— Sir \\. H. Beveridge. K.C.B. 

Vice-Presidents. — J. Sandewan Allen ; Sir F. D.\nson ; Prof. E. Y. Edge- 
worth ; Prof. A. W. Kirkaldy : Prof. D. H. ]Macgregor ; Hugh 


Recorder. — Prof. H. 'SI. Hallsworth. 
Secretaries. — A. Radford ; R. B. Forrester. 
Local Secretary. — Prof. E. R. Dewsndp.. 


I'lcsident. — Sir H. Fowler, K.B.E. 
I'lce-Fiesidents. — Prof. T. Hudson Beare; J. A. Brodie ; Prof. F. C. Lka : 

T. M. Newell; Prof. W. H. Watkinson. 
Recorder. — Prof. G. W. 0. Howe. 
Secretaries. — Prof. F. Bacon ; J. S. Wilson. 
Local Secretary. — Prof. T. R. Wilton. 

President. —Frot. P. E. Newberry, O.B.E. 
Vice-Prc.^ideiif.-:. — Dr. R. Caton ; Prof. E. Ekwall ; Dr. J. Garstang ; Dr. 

A. C. Kedyt; H. J. E. Peake; E. Tord.iy. 
Recorder. — E. N. Fallaize. 

Secretaries. — Miss R. M. Fleming ; Dr. F. C. Shruesall. 
Local Secretary. — Prof. J. P. Droop. 


President.— FroL G. H. F. Nuttall, F.R.S. 

Vice-PresideJits.~J. Barcroft, F.R.S. ; Prof. E. P. Cathcart. F.R.S. ; 
Prof. J. B. Leathes; Prof. A. B. Macallum. F.R.S.; Prof. J. S. M.\c- 
donald, F.R.S.; Prof. J. J. R. Macleod ; Prof. Sir C. Sherrington, 
G.B.E., Pres.R.S. 

Becorder. — Prof. C. Lovatt Evans. 

Secretaries. — Dr. J. H. Burn ; Prof. H. S. Raper. 

Local Secretary. — Dr. F. A. Duffield. 

President. — C. Burt. 
Vice-Presidents. — Dr. J. Drever; J. C. Flugel; Prof. A. Mair ; Dr. G. H. 

Miles; Dr. C. S. Myers, F.R.S.; Prof. T. H. Pear. 
Recorder. — Dr. Ll. Wynn Jones. 

Secretaries. — -R. J. Bartlett ; Dr. Shephfrd Dawson. 
Local Secretaries. — A. E. Heath; G. C. Field. 


President.— A. G. Tansley, F.R.S. 

Vice-Pre.s:ide77ts.—T?Toi. V. H. Blackman, F.R.S. : Prof. H. H. Dixon, 
F.R.S.; Dame Helen Gwynne-Yaughan, G.B.E. ; Prof. W. H. L.\ng, 
F.R.S.; Prof. J. C. Priestley; Prof. F. E. Weiss, F.R.S.; J. A. 

Recorder. — F. T. Brooks. 

Secretaries. — Dr. W. Robinson ; Prof. J. ^McLean Thompson. 

Local Secretary. — Miss M. Knight. 


President.— Vroi. T. P. Nunn. 
Vice-Presidents.— Prof. E. T. Campagnac ; G. H. Gater, C.M.G., D.S.O. ; 

Sir R. A. Grfgory ; Prof. O. Jbspersen ; J. G. Legge. 
Recorder. — D. Berridge. 

Secretaries. — C. E. Browne ; Dr. Lilian Clarke. 
Local Secretary. — C. F. !Mott. 


President. — Dr. C. CRO^^■THER. 

Vice-Presidents. — Rt, Hon. Lord Bleihsloe. K.B.E. ; W. J. Fitzherbert 

Brockholes, C.B.E. ; Prof. T. B. Wood. C.B.E.. F.R.S. 
Recorder.— 0. G. T. Morison. 

Secretaries. — Dr. G. Scott Robertson; T. S. Dymond. 
Local Secretary. — E. H. Rideout. 



Date of Meeting 

Where held 


Old Life 

New Life 

1831, Sept. 27 

1832, June 19 

1833, June 25 


Viscount Milton, D.O.L., P.R.S 

The Rev. W. Buckland, P.B.S 

The Rev. A. Sedgwick, P.R.S. 




1834, Sept. 8 

1835, Aug. 10 

Sir T. M. Brisbane, D.C.L., P.R.S. 
The Rev. Provost LIoyd,LL.D., P.R.S. 




1836, Aug. 22 

1837, Sept. 11 . 


The Marquis of Lansdowne, P.R.S. 
The Earl of Burlington, P.R.S. . . 



1838, Aug. 10 

Newoastle-on-Tyne. . . 

The Duke of Northumberland, P.R.S. 

1839, Aug. 26 


The Rev. W. Veruon Harcourt, P.R.S. 


1840, Sept. 17 


The Marquis of Breadalbane, P.R.S. 



1841, July 20 

1842, June 23 

1843, Aug. 17 

1844, Sept. 26 

1845, June 19 

1846, Sept. 10 


The Rev. W. Whewell, P.R.S 

The Lord Prancis Egerton, P.G.S. ... 

The Earl of Rosse, P.R.S 

The Rev. G. Peacock, D.D., P.R.S. ... 
Sir John P. W.Herschel, Bart., P.R.S. 
Sir Roderick I.Murchison,Bart.,P.R.S. 









1847, June 23 

1848, Aug. 9 


Sir Robert H. Inglis, Bart., P.R.S. ... 



1849, Sept. 12 

1850, July 21 

1851, July 2 

The Rev. T. R. Robinson, D.D., P.R.S. 

Sir David Brewster, K.H., P.R.S 

G. B. Airy, Astronomer Royal, P.R.S. 

Lieut.-General Sabine, P.R.S 

William Hopkins, P.R.S 

The Earl of Harrowby, P.R.S. 
The Duke of Argyll, P.R.S. 



1852, Sept. 1 

1853, Sept. 3 

1854, Sept. 20 

1855, Sept. 12 




1856, Aug. 6 

1857, Aug. 26 

1858, Sept. 22 ... 

Prof. 0. G. B. Danbeny, M.D., P.R.S. 
The Rev. H. Llovd, D.D., P.R.S. 
Richard Owen, M.D., D.O.L., P.R.S. 





1859, Sept. 14... 

1860, June 27 

1861, Sept. 4 

1862, Oct. 1 

1863, Aui. 26 


H.R.H. The Prince Consort 




The Lord Wrottesley, M.A., P.R.S. 
William Fairbairn, LL.D,, P.R.S. . 
The Rev. Professor Willis,M.A.,P.R.S. 
SirWilliam G. Armstrong.O.B., P.R.S. 



Newcastle-on-Tyne. . . 

1864, Sept. 13 

1865, Sept. 6 

1866, Aug. 22 

1867, Sept. 4 

1868, Aug. 19 

1869, Aug. 18 

1870, Sept. 14 


Sir Charles Lyell, Bart.. M.A., P.R.S. 
Prof. J. Phillips, M.A., LL.D., P.R.S. 

William R. Grove, Q.C., P.R.S 

The Duke of Buccleuoh, E.C.B.,P.R.S. 

Dr. Joseph D. Hooker, P.R.S. 

Prof. G. G. Stokes, D.C.L., P.R.S. .. 
Prof. T. H. Huxley, LL.D., P.R.S. .. 









1871, Aug. 2 

1872, Aug. 14 

1873, Sept. 17 

1874, Aug. 19 . . 

1875, Aug. 25 .... 

1876, Sept. 6 .... 

1877, Aug. 15 

1 1878, Aug. 14 

Prof. Sir W. Thomson. LL.D., P.R.S. 

Dr. W. B. Carpenter, P.R.S 

Prof. A. W. Williamson, P.R.S 

Prof. J. Tyndall, LL.D., P.R.S 

Sir John Hawkshaw, P.R.S 

Prof. T. Andrews, M.D., P.R.S ','. 

Prof. A. Thomson. M.D., P.R.S 

W. Spottiswoode, M.A., P.R.S. . 








1879, Aug. 20 


Prof. G. J. Allman, M.D.. P.R.S. 



1 1880, Aug. 25 


A. C. Ramsay, LL.D., P.R.S 



1 1881, Aug. 31 


Sir John Lubbock, Bart., P.R.S. . 



1882. Aug. 23 . 


Dr. C. W. Siemens, P.R.S 



1883, Sept. 19 .. 


Prof. A. Oayley, D.O.L., P.R.S 



1884 Aug. 27 . 


Prof. Lord Rayleigh, P.R.S 



1885. Sept. 9 . .. 


Sir Lyon Playfair, K.C.B., P.R.S. . 



1886, Sept. 1 


Sir J. W. Dawson, C.M.G., P.R.S. . 



1887, Aug. 31 


Sir H. E . Roscoe, D.C.L., P.R.S. ... 



1888, Sept. 5 


Sir P. J. Bramwell, P.R.S 



1889, Sept. 11 

Newcastle-on-Tyne. . . 

Prof. W. H. Plower, O.B., P.R.S. 



1890, Sept. 3 


Sir P. A. Abel, O.B., P.R.S 



1 1891, Aug. 19 .. 


Dr. W.Huggins, P.R.S 



1892, Aug. 3 .... 


Sir A. Geikie, LL.D., P.R.S 



, 1893, Sept. 13 


Prof. J. S. Burdon Sanderson, P.R.S 



; 1894, Aug. 8 


The Marquis of Salisbury,K.G..P.R.S 



1895, Sept. 11 


Sir Douglas Galton, K.C.B., P.R.S. .. 



189S, Sept. 16 


Sir Joseph Lister, Bart., Pres. R.S. 



1897, Aug. IS ... . 

1 Toronto 

Sir John Evans, K.C.B., P.R.S. 



1898, Sept. 7 

1 Bristol 

Sir W. Crookes, P.R.S 



1899. Sent. 13 


Sir Michael Poster, K.C.B., Sec.R.S... 



* Ladies were not admitted by purchased tickets until 1843, f Tickets of Admission to Sections only. 

^Continued on j). xii. 



! Old 










Sums paid 
on account 




for Scientific 
























































922 12 6 









932 2 2 









1595 11 









1546 16 4 








1235 10 11 








1449 17 8 








1565 10 2 








981 12 8 







1079 • 

831 9 9 









685 16 








208 5 4 









275 1 8 









169 19 









346 18 









391 9 7 









304 6 7 


















380 19 7 








2311 U 

480 16 4 









734 13 9 









607 15 4 









618 18 2 









684 11 1 


, 177 







766 19 6 









1111 5 10 


' 150 







1293 16 6 








3640 (J 

1608 3 10 









1289 16 8 









1591 7 10 









1750 13 4 









1739 4 




















1 303 









1 311 







1472 2 6 


! 280 

























1151 16 











1 331 







1092 4 2 


I 238 







1128 9 7 









725 16 6 









1080 11 11 









731 7 7 









476 8 1 









1126 1 11 









1083 3 3 






26 & 60 H.J 



1173 4 


















995 6 









1186 18 









1511 5 









1417 11 









789 16 8 









1029 10 









864 10 









907 15 6 









583 15 6 









977 15 5 









not 6 1 









1059 10 8 


















1430 14 2 


J Including Ladies. 5 Fellows of tlie Amcri.'au Association were admitted as Hon. Members for tbis Meeting 

[Conti/iiied on j/. xiii. 


Table of 

Bate o£ Meeting 

1900, Sept. 5 .. 

1901, Sept. U.. 

1902, Sept. 10.. 

1903, Sept. 9 .. 

1904, Au?. 17... 

1905, Aug. 15... 

1906, Aug. 1 ... 

1907, July .SI ... 

1908, Sept. 2 ... 

1909, &.ug. 23... 

1910, Aug. 31 .. 

1911, Aug. 30.. 

1912, Sept. 4 ... 

1913, Sept. 10 ... 

1914, Jnlv-Sept 

1915, Sept. 7 ... 
1916, Sept. 5 . . 


1919, Sept. 9 ... 

Bradford Sir William Turner, D.C.L.. F.R.S. ... 

Glasgow Prof.A.W. Riicker, D.Sc. SecJl.S. . 

Belfast i Prof. J. Dewar, LL.D., F.R.S. 

Southport Sir Norman Lockyer, K.C.B., F.R.S 

Cambridge ■ Rt. Hon. A. J. Balfour, JI.P., F.R.S. 

South Africa ' Prof. G. H. Darwin, LL.D., F.R.S. .. 

York Prof. E.RavLankester, LL.D., F.R.S. 

Leicester Sir David Gill, K.O.B., F.R.S 

Dublin Dr. Francis Darwin, F.R.S 

Winnipeg Prof. Sir J. J. Thomson, F.R.S. ... 

Sheffield Rev. Prof. T. G. Bonney, P.R.S. 

Portsmouth ' Prof. Sir W. Ramsay, K.C.B., F.R.S. 

Dundee : Prof.E. A. Schafer, F.R.S 

Birmingham : Sir Oliver J. Lodge, F.R.S 

Austraha Prof. W. Bateson, F.R.S 

Manchester '.... Prof. A. Schuster, F.R.S 

Newcastle-on-Tync... \ 

(No Meeting) [ Sir Arthur Evans, F.R.S 

(No Meeting) I 

Bournemouth Hon. Sir C. Parsons, K.C.B.,F.R S 

Old Life 

New Life 


































1920, Auff. 24 


Prof. W. A. Herdman, C.B.E., F.R.S. 



192!, Sept. 7 


Sir T. E. Thorpe. C.B., F.R.S 



1922, Sept. 6 


Sir C. S. Sherrington, G.B.E., 

Pres. R.S 



1923, Sept. 12 


Sir Ernest Rutherford, F.R.S 




Annual Meetings — (continued). 

Old Xew 

Aimiial Annual 

Members i Members 

























































































Sums paiil 
on account 
of Grants 
for Scientific 












Annual Members 























£1072 10 
920 9 11 
845 13 2 
887 18 11 
928 2 2 
882 9 
757 12 10 
1157 18 8 

1014 9 9 
963 17 
845 7 6 
978 17 1 
1861 18 4' 

1569 2 8 

985 IS 10 
677 17 2 
326 13 3 

I 410 

1272 10 1251 13 0" 
2599 15 518 1 10 

2735 15 ' 777 18 6" 





' Including 848 Members of the South African Association. 

- Including 137 Members of the American Association. 

" Special arrangements were made for Members and Associates joining locally in Australia, see 
Report. 1914, p. 686. The numbers include 80 Members who joined in order to attend the Meeting of 
L'Assoeiatiou Fran(,'aise at Le Havre. 

" Including Students' Ticlsets, 10s. 

• Including Exhibitioners granted tickets without charge. 

'• Including grants from the Ciivd Fund in this and subsequent years. 

■ Including Foreign Guests, Exliibitioners, and others. 

" Tlie Bournemouth Fund for Research, initiated by Sir 0. Parsons, f-nab'.ed grants on account of 
scientific purposes to be maintained. 

' laoluding grants from the Caird Gift for research in radioactivity in this and subsequent ycar.<. 


I. Majov-General Sir David Bruce, K.C.B., F.E.S., has been unani- 
mously nominated by the Council to fill the office of President of the 
Association for the year 1924-25 (Toronto Meeting). 

II. The Council conveyed to Sir William Herdman their condolence 
on the lamented death of Lady Herdman, and to Lady Dewar on that 
of Sir James Dewar, ex-President. 

III. The Hon. Sir Charles Parsons, ex-President, and Dr. E. H. 
Griffiths, General Treasurer, represented the Association at the 
Centenary celebration of the Yorkshire Philosophical Society, Septem- 
ber 20, 1922, and presented an Address on behalf of the Council, in 
which it was stated that the Society ' is justly regarded by the Associa- 
tion as its mother-society. ' 

Eepresentatives of the Association have been appointed as follows : — 

Air Conference, Guildhall . . . Mr. F. E. Smith, Sir Eichard 

Gregory and tlie Secretary. 

Council of Honour, International Air 

Congress Mr. E. V. Southwell. 

Societa Italiana per il Progresso delle 

Scienze Professor J. L. Myres and Dr. 

Eandall Maclver. 

Congres International pour la Protection 

de la Nature Dr. P. Chalmers Mitchell. 

Eoyal Sanitary Institute Congress . Mr. W. Whitaker. 

Eoyal Institute of Public Health 

Congress Dr. C. S. Myers. 

Pan-Pacific Science Congress . . Professor W. A. Osborne. 

Advisory Council, Scientific Expedi- 
tionary Eesearch Association . . Mr. F. E. Smith. 

Massachusetts Institute of Technology ; 

Inauguration of President . . . Professor W. MacDougall. 

Huxley Centenary Committee . . . Professor E. B. Poultou. 

Association Fran^aise (Bordeaux Meet- 
ing) Dr. J. G. Garson. 

IV. The Council expressed to Sir Robert Hadfield the grateful thanks 
of the Association for his generous gift designed to enable necessitous 
students to obtain scientific books. The gift is of £50 in each of three 
years, and that sum, for the first year, has been distributed in grants 
of £10 to each of five universities or colleges selected by lot, y'va. 
University College of Bangor, North Wales ; University College, Cardiff ; 
Universities of Leeds, Liverpool, and Manchester. 

V. In furtherance of the movement to establish a central institution 
for the encouragement oi more general interest in anthropological studies 
(Report, Hull Meeting, p. xv., § III, g), it has been ascertained that the 
Eoyal Anthi'opological Institute is willing, under certain conditions, to 
undertake the functions of such an institution, and has established a 


Joint Committee for Anthropological Training and Eeseavcli, on which 
all other bodies concerned in these matters are entitled to representation 
by their delegates. The Joint Committee has already held its first 
meeting, and taken action in matters of immediate concern to the 
constituent bodies. 

VI. Eesolutions referred by the General Committee, at the Hull 
Meeting, to the Council for consideration and, if .desirable, for action, 
were dealt with as follows : — 

(a) On the instruction of the General Committee, the Council invited 
the co-operation of a number of societies in applj'ing to the Eailway Com- 
panies in Great Britain for a restoration of the travelling facilities and 
concessions allowed to members attending scientific meetings before the 
^Yar. The Council were gratified to learn that this had been granted 
to the Association, and returned a vote of thanks to the Companies. 

(b) The Council agreed to support Dr. Potts in an application to the 
Committee of the Institution of Civil Engineers on Sea Action for a 
grant in aid of his investigation into the life-history of Teredo. 
(Resolution of Section D.) 

(c) The Council felt that they could take no action upon a suggestion 
that a fund should be raised for the i-elief of distinguished aged scientific 
men in need as the result of conditions on the Continent of Europe. 
(Eesolution of Section G.) 

(d) The Council, after full inquiry, decided to take no action upon a 
proposal that the Association should join the Museums Association in 
moving for the appointment of a Eoyal Commission to investigate the 
work of museums in relation to industries and general culture. (Eesolu- 
tion of the Committee of Eecommendations.) 

(e) The Council made a standing order that if, in connection with 
any application for a grant from the funds of the Association, any 
payment of travelling expenses (fares only) is contemplated, the amount 
to be so allocated must be stated in the application, and the payment of 
such expenses expressly sanctioned by the Committee of Eecommenda- 
tions and the General Committee, or, in the event of subsequent 
emergency, by the Council. 

VII. The Council, on behalf of the Association, joined in protesting 
against proposed changes in the Egyptian laws relating to antiquities, 
and received, through the Foreign Office and the High Commissioner, 
the assurance that the Egyptian Government would not modify the 
existing law without further cai'eful consideration of protests received. 

VIII. The President signed, on behalf of the Council, a memorandum 
io the President of the Board of Education, urging that further accom- 
modation should be provided for the Science collections at the Victoria 
and Alhert Museum, the Association having been represented in 1909 
on a deputation to the Board dealing with this question. 

IX. The Council have received reports from the General Treasurer 
throughout the year. His accounts have been audited and are presented 
to the General Committee. 


The Council made the following grants to research committees from 
the Caird Fund : — 

Seismology Committee ... ... ... £100 

Naples Table Committee 
Bronze Implements Committee 
Tables of Constants Committee 


The General Treasurer was authorised to apply any balance of Caird 
Fund income to meeting other grants made by the General Committee 
at Hull. 

The third grant of £250 from the Caird Gift for research in radio- 
activity (for the year ending March 24, 1924) has been made to Professor 
F. Soddy. 

The British Association Exhibitions established in connection with 
the Hull Meeting were awarded to eighteen students nominated by the 
same number of universities and colleges, w'hile six of these institutions 
made equivalent allowances for eight additional students. All were 
entertained by the Local Executive Committee at Hull, were enabled 
to meet the President and General Officers, and through an elected 
representative communicated to the Press their appreciation of the 
opportunity afforded to them of attending the Meeting. The Council 
have every hope of maintaining this system of exhibitions, which has 
already proved its value. 

A small cost has been incurred for repairing the datum-level mark 
erected at Stogursey by the Association in 1837. 

X. The Council approved a number of resolutions from the Con- 
ference of Delegates of Corresponding Societies. (Report, Hull Meeting, 
p. xxxiii.) 

A number of societies have been, admitted to affiliation or association, 
including, at the instance of the Organising Committee of Section M 
(Agriculture), certain agricultural societies which have not previously 
been represented. 

Prof. H. H. Turner has been nominated as President, Prof. P. G. H- 
Boswell as Vice-President, and Miss E. Warhurst as Local Secretary of 
the Conference of Delegates at Liverpool. 

The Corresponding Societies Committee has been nominated as 
follows: The President of the Association (Chairman, ex officio), Mr. 
T. Sheppard (Vice-Chairman), the General Treasurer, the General Secre- 
taries, Dr. F. A. Bather, Mr. O. G. S. Crawford. Prof. P. F. Kendall, 
Mr. Mark L. Sykes, Dr. C. Tierney, Prof. W. W. Watts, Mr. W. 

XL The retiring Ordinary Members of the Council are: — 
By seniority : Sir A. Strahan, Sir S. F. Harmer. 
By least attendance : Dr. E. F. Armstrong, Sir J. Petavel, 
Sir W. J. Pope. 

The Council nominated the following new members : — 

Prof. W. Dalby, Dr. J. S. Fletfc, Mr. C. T. Heycock, 

leaving two vacancies to be filled by tEe General Committee without 
nomination by the Council. 


The full list of nominations of Ordinary Members is as follows : — 

Dr. F. W. Aston, F.R.S. > Sir A. Keith, F.R.S. 

Mr. J. Barcroft, F.R.S. i Sir J. Scott Keltic. 

Rt. Hon. Lord Bledisloe, K.B.E. ; Professor A. W. Kirkaldy. 

Professor W. Dalby, F.R.S. i Dr. P. Chalmers Mitchell, C.B.E., 

Mr. E. N. Fallaize. | F.R.S. 

Dr. J. S. Flett, F.R.S. Dr. C. S. Myers, F.R.S. 

Professor H. J. Fleure. Professor A. W. Porter, F.R.S. 

Professor A. Fowler, F.R.S. , Professor A. C. Seward, F.R.S. 

Sir R. A. Gregory. Professor A. Smithells, C.M.G., 

Sir Daniel Hall, K.C.B., F.R.S. i F.R.S. 

Mr. C. T. Heycock, F.R.S. Mr. A. G. Tansley, F.R.S. 

Dr. W. Evans Hovle. i :Mr. W. Whitaker, F.R.S. 

Mr. J. H. Jeans, F.R.S. 

XII. The General Officers have been nominated by the Council as 
follows : — 

General Treasurer, Dr. E. H. Griffiths. 

General Secretaries, Prof. J. L. Myres, Mr. F. E. Smith. 

XIII. The following have been admitted as members of the General 
Committee : — 

Dr. W. L. Balls. 
Professor J. W. Bews. 
Professor A. H. R. Buller. 
Mr. R. S. Clark. 
Mr. J. R. Clarke. 
Mr. N. M. Comber. 
Mr. J. T. Cunningham. 
Dr. E. M. Delf. 
ilr. E. A. Fisher. 
Miss R. ^I. Fleming. 
Dr. R. H. Greaves. 

Professor W. D. Henderson. 
Mr. Julian S. Huxley. 
Mr. H. Jeffreys. 
Dr. A. F. Joseph. 
Mrs. Forbes Julian. 
Dr. M. V. Lehour. 
Dr. E. B. R. Prideaux. 
Mr. J. Ramsbottom. 
Dr. E. J. Salisbury. 
Professor W. Wright Smith. 
Professor D. Thodav. 

XIV. The Council take pleasure in nominating M. le Comte de St. 
Perier to be an honorary corresponding member of the Association. 

XV. Arrangements for the Meeting in Toronto, 1924, are in progress, 
and the Council has appointed a committee to assist the General Officers 
in this matter, including Sir D. Bruce, Sir E. A. Gregory, Sir W. 
Herdman, Prof. A. W. Kirkaldy, Prof. J. 0. McLennan, Sir E. Euther- 
ford, Sir C. Sherrington, Prof. A. Smithells. 

The General Committee at Hull desired the Council to consider the 
possibility of a meeting being held in England in 1924, following and 
supplementary to the Toronto Meeting. The Council have done so, 
but do not see the way clear to carrying out the suggestion. 

XVI. The Council recommend the following change in Eule V., 1, 
in relation to ex-ofiicio members of the Council, viz. : — 

Present Rule. — The ex-officio members are . . . the President and 
Vice-Presidents for the year, the President and Vice-Presidents elect 
. . . and the Local Treasurers and Local Secretaries for the ensuing 
Annual Meeting. 

Amendment.- — The ex-officio members are . . . the President for the 
year, the President and Vice-Presidents for the ensuing Anntial Meeting 
. . . and the Local Treasurers and Local Secretaries for the Annual 
Meetings immediately past and ensuing. 

1923 B 



For the Liverpool [Meeting, British Association Exhibitions (refeiTed 
to in § IX. of t]ie above report) were awarded to twenty students 
nominated by the same number of universities and colleges. Their 
travelling expenses (railway fares) were met by the Association, which 
also- issued complimentary students' tickets oi membership to them; 
they were entertained in Liverpool by the Local Executive Committee 
at University hostels in Liverpool. Six of the universities or colleges 
allowed travelling expenses for thirteen additional exhibitioners, wlio 
also received the other facilities indicated above. The exhibitioners 
were enabled to meet the President and general officers. One of their 
number (Mr. W. W. Allen, of King's College, London) was elected 
secretary for the purpose of communication by the exhibitioners as a 
body with the- general officers. 




Inaugural General Meeting. 

On Wednesday, September 12, at 8.30 p.m., in the Philharmonic 
Hall, Prof. Sir Charles S. Sherrington, G.B.E., Pres.R.S., resigned 
tlie office of President of the Association tO' Prof. Sir Ernest Eutherfcrd, 
F.E.S.. who delivered an address on 'The Electrical Structure of 
]\Iatter ' (for which see p. T). 

The address was broadcast from all stations of the British Bread- 
casting Company, and was effectively heard in all parts of Great Britain ; 
it was also reported as clearly received by a listener in Switzerland. 
Arrangements for land-line transmission were made by the Western 
Electric Company, and these also enabled the address to be I'epeated 
in the Small Concert Eoom, St. George's Hall, Liverpool, where a 
duplicate set of the lantern-sides used by the speaker wns shown at 
the appropriate points in the address. 

Evening Lecture. 

On Friday, September 14, at 8.30 p.m., in the Philharmonic Hall, 
Prof. G. Elliot Smith, F.R.S., delivered a lecture on 'The Study of 

Scientific Exhibition. 

A Scientific Exhibition was opened in the Central Technical School 
from September 10 to 22, the public being admitted in addition to 


members of the Association. Exhibits wcro furnis'hed by upwards of 
sixty firms, institutions, and individuals, and demonstrations were given 
and lectures delivered throughout the period of the exhibition. 

Scientific Soiree. 

A Scientific Soiree was held in Liverpool University on Tuesday 
evening, September 18, at which a large number of exhibits, demonstra- 
tions, and short lectures, in all departments of science covei'ed by the 
Sections of the Association, illustrated recent advances. 

Concluding General Meeting. 

The concluding General Meeting was held in St. George's Hall on 
Wednesday, September 19, at 12 noon, when the following resolutions 
were adopted by acclamatio'n : — 


To express the thanks of the British Association to the City of Liverpool, 
through the lit. Hon. the Lord Mayor, for its hospitable welcome ; and to the 
City Council for its generous help, and the assistance afforded by its 
staff and various committees, especially the Sub-Committee for Technical and 
Commercial Education, which has allowed the Technical School to be used for 
the Scientific Exhibition, and the Tramways Committee, whicli has given free 
transport to members of the Association. 

To thank the University of Liverpool, through the Vice Chancellor, for the 
use of its buildings and scientific equipment, and for the friendly co-operation 

of its Professors and staff. 


To thank the Local Committee and its Vice-Chairmen, the Local Hon. 
Secretaries and Assistant Secretary, the Local Hon. Treasurer and Assistant 
Treasurer, and their staifs, for their provision for the needs of the Association 
and the entertainment of its members: the Chairman and Secretary of the 
Scientific Exhibition Committee and of the Scientific Soiree Committee for 
their work in connection with these interesting features of the meeting; the 
Liverpool Clubs for their hospitality, and the Overhead Railway for providing 
free transport; and generally to express the gratitude of tlie Association to all 
those who by throwing open works ov other enterprises for inspection, and in 
many other ways, have contributed to t!ie success of the meeting. 


PiCTON Hall, Liverpool. 

Tuesday, September 11, at 8 p.m. : Professor G. VV. 0. Howe on 'The Evolu- 
tion of the High Power Wireless Station.' 

Thursday, September 13, at 8 p.m. : Professor A. S. Eddington, F.R.S., on 
' Relativity.' 

Friday, September 14, at 8 p.m. : Sir Wm. Pope, K.B.E., F.R.S., on 'Colour 


Monday, September 17, at 8 p.m. : Mr. J. Barcroft, C.B.E., F.E.S., on 'The 

Study of Life on the Roof of the New World.' 
Wednesday, September 19, at 8 p.m. : Dr. F. A. E. Crew on ' The Riddle 

of Sex.' 

Arts The.\tre, University of Liverpool. 

Friday, September 14, at 5 p.m. : Dr. Johs. Schmidt on ' The " Dana " Expedi- 
tions and their work on the Life-History of the Eel.' 

Towx Hall, Hamilton Square, Birkenhead. 

Friday, September 14, at 7.30 p.m. : Professor A. C. Seward, F.R.S., on 

' Greenland : Its Ice, Flowers, and People.' 
Tuesday, September 18, at 3.30 p.m. : Professor E. B. Poulton, F.R.S., on 

' Mimicry in Insects ' (a Lecture for Young People). 

Town Hall, Bootle. 

Friday, September 14, at 8 p.m. : Professor T. H. Pear on ' The Acquisition 
of Skill in Work and Play.' 

Town Hall, Wallasey. 

Wednesday, September 12, at 8 p.m. : Professor A. Dendy, F.R.S., on ' The 
Evolution Tlieory of To-day.' 

Parr Hall, Warrington. 

Friday, September 14, at 7.30 p.m. : Sir John Russell, O.B.E., F.R.S. , on 

' Soil and Crop Growth.' 
Friday, September 14, at 3 p.m. : JMr. F. Balfour Browne on ' Wild Bees and 


Town Hall, St. Helens. 

^Monday, September 17, at 7. .30 p.m. : Professor P. M. Roxby on 'Regional 

iliNiNG and Technical College, Lirrary Street, Wigan. 

Monday, September 17, at 7.30 p.m. : Professor H. H. Turner, F.R.S., on 
' The Size of a Star.' 

Technical Institute, Runcorn. 

Monday, September 17, at 7.30 p.m. : ]\Iajor G. W. C. Kaye on ' X-rays and 
their Uses.' 


Arts Theatre, University of Liverpool. 

Thursday, September 13, at 3 p.m. : Professor Arthur Smithells, C.^I.G., 
F.R.S., on ' Flame.' 

Picton Hall, Liverpool. 

«riday, September 14, at 3 p.m. : Professor P. E. Newberry, O.B.E., on 
' Tovs and Games.' 


July 1, 1922, to June 30, 1923. 


Balance Sheet, 


To Sundry Creditors ..... 

„ Capital Account — 

General Fund per contra 

Caird Fund do. .... 

Sir F. Bramwell's Gift for Inquiry into 

Prime Movers, 19.31 — 
£50 Consols accumulated to June 30, 1923, 
as per contra ..... 

£ ,-. 


£ ■.■. 
87 U 

10.575 15 
9;582 16 



Caird Fund — - 

Balance as at July 1, 1922 

573 12 

^dd Excess of Income over Expend! - 

ture . ..... 

113 10 


(This is without allowance for Depreciation 
of Investments £1,861 10s. 3d.) 
Caird Gift— 

Radio-Activity Investisration, Balance at 

July 1. 1922 

Add Dividends on Treasury Bonds . 
Income Tax Recovered .... 

Less Grant to Sir E. Rutherford 

Sir Charles Parsons' Gift .... 

John Perry Guest Fund — ■ 

For cases of emersrency connected with 
Guests of the Association . 

Life Compositions as at July 1, 1922 
^Idd Received during year 

Legacy, T. W. Backhouse .... 
Income and Expenditure Account — 
Balance at July 1, 1922 

Add Excess of Income over Expendi- 
ture . .... 

1,046 IS 
38 2 
22 18 

1,107 19 



857 19 




2,621 19 


336 19 


2.958 19 


-The above is subject to Depreciation 
of Investments amounting to a net 
sum of £2,398 9s. 6d.) 

£ s. d. 

Ficures, 1!I22. 
S46 15 1 

10,575 15 2 
9,5S2 16 3 

1,046 IS 


£35,616 14 2 

S,35,271 10 11 

I have examined the foregoing Account with the Books and Vouchers, and certify the 



Jxilv 20, 192 3. 



July 1, 1922— June 30, 1923 


By Sundry Debtors ...... 

„ Investments on Capital Accounts — 

£+,651 10s. 5d. Consolidated 2 J per cent. 

Stock at cost ..... 3,942 3 3 
£3,600 India 3 per cent. Stock at cost . 3,522 2 
£879 14s. 9ri. £43 Great Indian Peninsula 

•' B " Annuity at cost . . . 827 1j 

£52 12s. Id. & £810 10s. 3d. War Stock, 

1929/47 at cost .... 889 17 6 

£1,400 War Loan Bonds 5 per cent. 1929/47 

atcost ...... 1,393 16 11 

a s. d. £ 8. d. 


FiRures. 1022. 

21 3 

45 13 4 

£7,634 ISs. 2d. Value at date, £7,955 10s. \d. 
Caird Fund — 

£2,627 Os.lOd.IudiaSipercent.Stockatcost 2,400 13 3 
£2,100 London, Midland and Scottish Rly. 

Consolidated 4 per cent. Preference 

Stock at cost ..... 2,190 4 3 
£2,500 Canada 3i per cent. 1930/50 

Regristered Stock at cost . . . 2,397 1 6 

£2,000 Southern Rly. ConsoUdated 5 per 

cent. Preference Stock at cost . . 2,594 17 3 

&7.359 16s. Id.Vcdne at datc,£7,721 6s. Od. 
Sir F. Bramwell's Gift — 

£50 2i per cent. Self -Cumulating Con- 
solidated Stock as per last Balance 
Sheet . . . . £111 11 1 

Add accumulations to 

June 30, 1923 . . 4 17 5 

10,575 15 2 

9,582 16 3 

£116 8 6 

£63 lis. Sd. Value at date, £68 7s. lid. 
Caird Gift— 

£1,000 Registered Treasury Bonds. 

£1,105. Value at date, £1,018 15s. Od. 
Sir Charles Parsons' Gift — 

£10,000 5 per cent. War Loan 

£.10,025. Value at date, £10,125. 
John Perry Guest Fund — 

£96 National Savings Certificates at cost 
Investments out of Income — 

£2,098 Is. M. Consolidated 2 J per cent. 
Stock at cost ..... 

£1,500 Registered Treasury Bonds at cost 

£2,S57 10s. Od. Value at date, £2,778 9s. Id. 
Life Compositions — 

£324 lis. 8(J. Local Loans at cost 

Value at date, £220 14s. id. 
Cash — On Deposit 
At Bank . 

Viz. : — Legacy 
Caird Fund 
Life Compositions 
John Pen-y Guest Fuud 

53 14 


2 16 


56 11 



74 8 











1,389 10 5 

Lrss Caird Gift 

General Pui'poses 


1,212 14 



1,070 13 
318 16 



£1,389 10 


10,075 li 

9,.iS2 16 3 




1,281 li U 

£35,616 14 2 \£35,271 JO 11 

same to be coiTCct. I have also verified the balances at the Bankers and the Investments. 

W. B. KEEN, 

Chartered Accountant. 


Income and 

FOR THE Year Ended 


£ s. d. S. s. d. S. s. d. 




, 19-2 


To Heat and Lighting .... 







„ Stationery ..... 







., Rent ...... 




„ Postases ....-■ 







, Electric Light Installation 




„ Refund, re Australian Meetiny 


„ Travelling Expenses .... 




\ 3S1 


„ Kxhibitioners ..... 




„ General Expenses .... 













„ Salaries and Wages .... 







,, Pension Contribution .... 



„ Printing, Binding, etc. 

. 1.396 








„ Sir Robert Hadfield's Gift : Grants to Univcr 



., Miss Stewardson, as per Contra 


„ Grants to Research Committees : — 

Absorption Spectra 


Stress Distributions 


Parthenogenesis .... 


Growth of Children 


Coldrum Megalithic Monument 


Geography Teaching 


Colloid Chemistry 


Old Red Sandstone of Bristol 


Stone Monuments 


Muscular StifEness. 


Corresponding Societies 


Bronze Implements 


Dei bysbire Caves 


Zoological Bibliosraphy 




Fossils ..... 


Uenothera ..... 




Conjoint Board .... 






„ Balance being excess of Income over Expei 


ture for the year .... 












(1) Postage of the Annual Report was formerly reckoned with the printing account. 

(2) The increase is mainly accounted for by the purchase of an addressing and listing machine, 
which helps materially to reduce the printing account. 

(3) Wages were formerly reckoned with General Expenses. 

To Grants paid — 

Tables of Constants Committee 
Naples Station Committee 
Seismology Committee 
Bronze Implements Committee 





Balance being 

Exces~ of Income over 


£ s. d. 


Expenditure Account 

June 30, 1923. 


By Life Compositions (Noiv Capitalised) 
„ Annual Members' Subscriptions, Regular — 

Including £7(), 1923/24, and £1, 1924/25 
„ Annual Members' Subscriptions, Temporary — 

(Including; .£111, 1923/24) . 
,, Annual Members' Subscriptions, with Report 

(Including -669 10s., 1923/24) . 
„ Transferable Tickets (Including: €2 10s., 1923/24) 
„ Students' Tickets (Including 1^2 10s.. 1923/24) 
,, Life Members' Additional Subscriptions . 
,, Donations ...... 

„ ,, (Miss Steivardson), as per contra 

,, Interest on Deposits .... 

,, Advertisements .... 

„ Sales of Publications .... 

„ Sir Robert Hadfield's Gift . 

,, Transfer from Caird Fund 

„ Unexpended Balance of grants returned 

„ Income Tax recovered 

„ Dividends : — 

Consols ..... 

India 3 per cent. .... 

Great Indian Peninsula " B " Annuity 

War Stock ..... 
,, ,, (Sir Charles Parsons' Gift) 

Treasury Bonds .... 

Local Loans .... 

116 14 
21 19 
96 10 


59 1 

I 16 

s. d. 


109 10 


10 17 
60 12 

802 8 

111 12 
117 15 

880 1 11 

£3,889 12 6 

£ s. d. 

Period. 1022. 





































£4,658 7 5 


By Dividends on Investments : — 

India 3 i per cent. . . . 

Canada 3 J per cent. .... 

London, Midland & Scottish Railway Con- 
solidated 4 per cent. Preference Stock . 

Southern Rail way Consolidated 5 per cent. 
Preference Stock .... 

,, Income Tax recovered ..... 

„ Balance being Excess of Expenditure over 

Income ... .... 

£ s. 
68 19 
65 12 









61 19 

73 15 




















Grants of money, ifany,fro7n the Association for e-rpenses connected 
ivith researches are inclicatecl in heavy type. 


Seismological Investigations. — Prof. H. H. Turner {Chairman), Mr. J. J. Shaw 
(Secretary), Mr. C. Vernon Boys, Dr. J. E. Crombie, Dr. C. Davison, 
Sir F. W. Dyson, Sir R. T. Glaze'brook, Prof. H. Lamb, Sir J. Larmor, Prof' 
A. E. H. Love, Prof. H. M. Macdonald, Prof. H. C. Plummer, Mr. W. E. 
Plummer, Prof. R. A. Sampson, Sir A. Schuster, Sir Napier Shaw, Dr. G. T. 
Wallier. £100 (Caird Fund grant). 

Tides. — Prof. H. Lamb {Chairman), Dr. A. T. Doodson {Secretary), Dr. G. R. 
Goldsbrough, Dr. H. Jeffreys, Prof. J. Proudman, Major G. I. Taylor, Prof. 
D'Arcy W. Thompson, Commander H. D. Warburg. 

Annual Tables of Constants and Numerical Data, chemical, physical, and technological. 
— Sir E. Rutherford (Chairman), Prof. A. W. Porter (Secretary), Mr. Alfred 
Egerton. £15 (Caird Fund grant, to be applied for from Council). 

Calculation of Mathematical Tables. — Prof. J. W. Nicholson (Chairman), Dr. J. R. 
Airey (Secretary), Mr. T. W. Chaundy, Prof. L. N. G. Filon, Prof. E. W. Hobson, 
Mr. G. Kennedy, and Profs. Alfred Lodge, A. E. H. Love, H. M. Macdonald, 
G. B. Mathews, G. N. Watson, and A. G. Webster. £35 (for printing). 

Determination of Gravity at Sea. — Prof. A. E. H. Love (Chairman), Dr. W. G. Duffield 
(Secretary), Mr. T. W. Chaundy, Prof. A. S. Eddington, Major E. O. Henrici 
Sir A. Schuster, Prof. H. H. Turner. 

Investigation of the Upper Atmosphere. — Sir Napier Shaw (Chairmnn), Mr. C. J. P. 
Cave (Secretary), Prof. S. Chapman, Mr. J. S. Dines, Mr. L. H. G. Dines. Mr. 
W. H. Dines, Sir R. T. Glazebrook, Col. E. Gold, Dr. H. Jeffreys, Sir J. Larmor^ 
Mr. R. G. K. Lempfert, Prof. F. A. Lindemann, Dr. W. Makower, Sir J. E. Petavel, 
Sir A. Schuster, Dr. G. C. Simpson, Mr. F. J. W. Whipple, Prof. H. H. Turner. 

To aid the work of Establishing a Solar Observatory in Australia. — Prof. H. H. Turner 
(Chairman), Dr. W. G. Duffield (Secretary), Rev. A. L. Cortie, Dr. W. J. S. Lockyer, 
Mr. F. McClean, Sir A. Schuster. 

To investigate local variations of the Earth'.s Gravitational Field. — Col. H. G. Lyons 
(Chairman), Capt. H. Shaw (Secretary), Prof. C. Vernon Boys, Dr. C. Chree, Col. 
Sir G. P. Lenox-Conyngham, Dr. J. W. Evans, Mr. E. Lancaster-Jones, the 
Director-General, Ordnance Survey ; the Director, Geological Survey of Great 
Britain. £50. 


Colloid Chemistry and its Industrial Applications. — Prof. F. G. Donnan (Chairman) 
Dr. W. Clayton (Secretary), Mr. E. Hatschek, Prof. W. C. McC. Lewis, Prof. J. w! 
McBain. £5. 

Absorption Spectra and Chemical Constitution of Organic Compounds. — Prof. I. M. 

Heilbron (Chairman), Prof. E. C. C. Baly (Secretary), Prof. A. W. Stewart. £10. 
The Position of the Quantum Theory in its relations to Chemistry. — Prof. W. C. 

McC. Lewis (Chairman), Dr. J. Rice (Secretary), Prof. E. C. C. Baly, Prof. F. A. 

Lindemann, Dr. E. K. Rideal, Dr. N. V. Sidgwick. £10. 



The Old Red Sandstone Rocks of Kiltorcan, Ireland. — Prof. Grenville Cole (Chair- 
man), Prof. T. Johnson (Secretary), Dr. J. W. Evans, Dr. R. Kidston, Dr. A. 
Smith Woodward. £15. 

To excavate Critical Sections in the Palseozoic Rocks of England and Wales. — Prof. 
W. AV. Watts (Chairman), Prof. W. G. Fearnsides (Secretary), Prof. W. S. Boulton, 
Mr. E. S. Cobbold, Prof. E. J. Garwood, Mr. V. C. lUing, Dr. J. E. Marr, 
Dr. W. K. Spencer. £5. 

"Tlie Collection, Preservation, and Systematic Registration of Photographs of Geo- 
logical Interest. — Prof. E. J. Garwood (Chairman), Prof. S. H. Reynolds (Secretary), 
Mr. G. Binsley, Messrs. C. V. Crook, R. Kidston. and A. S. Reid, Sir J. J. H. 
Teall, Prof": W.W. Watts, and Messrs. R. Welch and W. Whitaker. 

To consider the preparation of a List of Characteristic Fossils. — Prof. P. F. Kendall 
(Chairman), Mr. H. C. Versey (Secretary), Prof. W. S. Boulton, Dr. A. R. Dwerry- 
house. Profs. J. W. Gregory, Sir T. H. Holland, and S. H. Revnolds, Dr. Marie 
C. Stopes, Dr. .J. E. Marr, Prof. W. W. Watts, Mr. H. Woods, and Dr. A. Smith 
Woodward. £5. 

To investigate the Flora of Lower Carboniferous times as exemplitied at a newlv 
discovered locality at Gullane, Haddingtonshire. — Dr. R. Kidston [Chairman), 
Prof. W.T. Gordon (Secretary), Dr. .T. 8. I'ett, Prof. E. J. Garwood, Dr. J. Home, 
and Dr. B. N. Peach. 

To investigate the Stratigraphical Sequence and Paleontology of the Old Red Sand- 
stone of the Bristol district. — Dr. H. Bolton (Chairman), Mr. F. S. Wallis 
(Secretary), Miss Edith Bolton, Mr. D. E. I. Innes, Prof. C. Lloyd Morgan, Prof. 
S. H. Reynolds, Mr. H. W. Turner. £20. 

To investigate the Quaternary Peats of the British Isles. — Prof. P. F. Kendall (Chair- 
man), Mr. L. H. Tonks (Secretary), Prof. P. G. H. Boswell, Miss Chandler, Prof. 
H. J. Fleure, Dr. E. Greenly, Prof. J. W. Gregory, Prof. G. Hickling, Mr. J. de W. 
Hinch, Mr. R. Llovd Praeger, Mrs. Reid, Mr. T. Sheppard, Mr. J. W. Stather, 
Mr. A. W. Stelfox, Mr. C. B. Travis, Mr. A. E. Trueman, Mr. W. B. Wright. £50. 

Comparison of the Rocks of Pre -Cambrian and presumably Pre-Cambrian Inliers of 
England and Wales and the Dublin Area with the Rocks of the Mona Complex 
of Anglesey, with a view to possible correlation. — Dr. Gertrude Elles (Chairman), 
Dr. Edward Greenly (Secretary), Mr. T. ('. Nicholas, Prof. S. H. Reynolds, 
Dr. C. E. Tilley. £30 (including travelling fares). 

To investigate Critical Sections in the Tertiary Rocks of the London Area. To tabulate 
and preserve records of new excavations in that area. — Prof. W. T. Gordon (Chair- 
man), Dr. S. W. Wooldridge (Secretary), Miss M. C. Crosfield, Prof. H. L. Hawkins, 
Prof. G. Hickling, Mr. W. Whitaker. £15. 

To attempt to obtain agreement regarding the significance to be attached to Zonal 
Terms used in connection with the lower Carboniferous. — Prof. P. F. Kendall 
(Chairman), Mr. R. G. Hudson (Secretary), Mr. J. W. Jackson, Mr. W. B. Wright. 


To aid competent Investigators selected by the Committee to carry on definite pieces 
of work at the Zoological Station at Naples. — Prof. E. S. Goodrich (Chairman), 
Prof. J. H. Ash worth (Secretary), Dr. G. P. Bidder, Prof. F. O. Bower, Dr. W. B. 
Hardy, Sir S. F. Harmer, Prof.'S. J. Hickson, Sir E. Ray Lankester, Prof. W. C. 
Mcintosh. £100 from Caird Fund, subject to approval of Council. 

To summon meetings in London or elsewhere for the consideration of matters affecting 
the interests of Zoology, and to obtain by correspondence the opinion of Zoologists 
on matters of a similar kind, with power to raise by subscription from each 
Zoologist a sum of money for defraying cui'rent expenses of the organisation. — 
Prof. S. J. Hickson (Chairman), Mr. R. A. Wardle (Secretary), Prof. J. H. Ashworth, 
Prof. W. J. Dakin, Prof. A. Dendy, Prof. F. W. Gamble, Prof. J. Stanley Gardiner, 
Prof. W. Garstang, Sir S. Harmer, Sir W. A. Herdman, Prof. J. Graham Kerr, 
Prof. R. D. Laurie, Prof. E. W. MacBride, Prof. E. B. Poulton, Prof. W. M. 


Zoological Bibliography and Publication. — Prof. E. B. Poulton (Chairman), Dr. F. A. 

Bather (Secrelnry), Mr. E. Heron-Allen, Dr. W. E. Hoyle, Dr. P. Chalmers 

Mitchell, Mr. W. L. Sclater. £1. 
Parthenogenesis. — Prof. A. Meek (Chairman), Mr. A. D. Peacock (Secretary), Mr 

R. S. Bagnall, Dr. J. W. Heslop-Harrison. £5. 
To nominate competent Naturalists to perform definite pieces of work at the Marine 

Laboratory, Plymouth. — Prof. A. Dendy (Chairman and Secretary), Prof. J. H. 

Ashworth," Prof. W. J. Dakin, Prof. S. J. Hickson, Sir E. Ray Lankester. £25 

(Caird Fund grant, to be applied for from Council). 
To co-operate with other Sections interested, and with the Zoological Society, for 

the purpose of obtaining support for the Zoological Record. — Sir S. Harnier 

(Chairman), Dr. W. T. Caiman (Secretary), Prof. A. Dendy, Prof. E. S. Goodrich, 

Prof. D. M. S. Watson. £50 (Caird Fund grant, to be ajjplied for from 

Marme Biological Research in India. — Dr. E. J. Allen (Chairman), Dr. S. \( . Kemp 

(Secretary), Prof. J. H. Ashworth, Prof. J. Stanley Gardiner, Prof. E. S. Goodrich, 

Dr. P. Chalmers Mitchell. 


To consider the advisability of making a provisional Population Map of the British 
Isles, and to make recommendations as to the method of construction and 
reproduction. — Mr. H. O. Beckit (Chairman), Mr. F. Debenham (Secretary), 
Mr. J. Bartholomew, Prof. H. J. Fleure, Mr. R. H. Kinvig, Mr. A. G. Ogilvie, 
Mr. O. H. T. Rishbeth, Prof. P. M. Roxby. £5. 


To formulate suggestions for a syllabus for the teaching of Geography both to Matricu- 
lation Standard and in Advanced Courses ; to rejiort upon the present position 
of the geographical training of teachers, and to make recommendations thereon ; 
and to report, as occasion arises, to Council through the Organising Committee 
of Section E, upon the practical working of Regulations i.ssued by the Board of 
Education affecting the position of Geography in Training Colleges and Secondary 
Schools. — Prof. T. P. Nunn (Chairman), Mr. W. H. Barker (Secretary), Mr. L. 
Brooks, Prof. H. J. Fleure, Mr. O. J. R. Howarth, Sir H. J. Mackinder, Prof. 
J. L. Myres, and Prof. J. F. Unstead(/ro)H Section E) : Mr. Adlam, Mr. D. Berridge, 
Mr. C. E. Browne, Sir R. Gregory, Mr. E. Sharwood Smith, Mr. E. R. Thomas, Miss 
O. Wright (from Section L). 


To report on certain of the more complex Stress Distributions in Engineering Materials. 
—Prof. E. G. Coker (Chairman), Prof. L. N. G. Filon, and Prof. A. Robertson 
(Secretaries), Prof. T. B. Abell, Prof. A. Barr, Mr. Charles Brown, Dr. Gilbert 
Cook, Prof. W. E. Dalby, Sir J. A. Ewing, Sir H. Fowler, Mr. A. R. Fulton, 
Dr. A. A. Griffith, Mr. J. J. Guest, Dr. B. P. Haigh, Profs. Sir J. B. Henderson, 
C. E. Inglis, F. C. Lea, A. E. H. Love, and W. Mason, Sir J. E. Petavel, Dr. F. 
Rogers, Dr. W. A. Scoble, Mr. R. V. Southwell, Dr. T. E. Stanton, Mr. C. E. 
Stromeyer, Mr. G. I. Taylor, Mr. A. T. Wall, Mr. J. S. Wilson. £25. 


To report on the Distribution of Bronze Age Tmplen^jnts.- — Prof. J. L. Myres (Chair- 
man), Mr. H. Peake (Secretary), Mr. Leslie Armstrong, Dr. G. A. Auden, 
Mr. H. Balfour, Mr. L. H. D. Buxton, Mr. O. G. S. Crav^-ford, Sir W. Boyd 
Dawkins, Prof. H. J. Fleure, Mr. G. A. Garfitt, Prof. Sir W. Ridgeway. £100 
(including £()0 from Caird Fund, to be applied for from Council). 

To conduct Arch .Geological Investigations in Malta. — Prof. J. L. Myres (Chairman), 
Sir A. Keith (Secretary), Dr. T. Ashby, Mr. H. Balfour, Dr. R. R. Marett, 
Mr. H. Peake. 


To conduct Explorations with the object of ascertaining the Age of Stone Circles.— 
Sir C. H. Read (Chairman), Mr. H. Balfour [Secretary), Dr. G. A. Auden, Prof. 
Sir W. Ridgewav, Dr. J. G. Garson, Sir Arthur Evans, Sir W. Boj'd Dawkins, 
Prof. J. L. Myres, Mr. H. J. E. Peake. 

To excavate Early Sites in Macedonia. — Prof. Sir W. Ridgevay [Chairman), Mr. 
S. Casson [Serretari/). Prof. R. C. Bosanquet, Dr. W. L. H. Duckworth, Prof. 
J. L. Myres, Mr. M. Thompson. 

To report on the ClassiKcation and Distribution of Rude Stone Monuments. — Mr. 
G. A. Garfitt {Chairman), Prof. H. J. Fleure [Secretary), Mr. O. G. S. Crawford, 
Miss R. M. Fleming, Dr. C. Fox, Mr. G. Marshall, Prof. J. L. Mj'res, Mr. H. J. E. 
Peake. £5. 

The Collection, Preservation, and Systematic Registration of Photographs of Anthro- 
pological Interest. — Mr. E. Torday (Chairman), Mr. E. N. Fallaize (Secretary), 
Dr. G. A. Auden, Dr. H. A. Auden, Mr. E. Heawood, Prof. J. L. Myres. 

To conduct Archfeological and Ethnological Researches in Crete. — Dr. D. G. Hogarth 
{Chairman}, Prof. J. L. Myres (Secretary), Prof. R. C. Bosanquet, Dr. W. L. H. 
Duckworth, Sir A. Evans, Prof. Sir W. Ridgeway, Dr. F. C. Shrubsall. 

To co-operate with Local Committees in excavation on Roman Sites in Britain. — 
Prof. Sir W. Ridgeway (Chairman), Mr. H. J. E. Peake (Secretary), Dr. T. Ashby, 
Mr. Willoughby Gardner, Prof. J. L. Myres. 

To report on the present state of knowledge of the Ethnography and Anthropology 
of the Near and Middle East. — Dr. A. C. Haddon (Chairman), Mr. E. N. Fallaize 
{Secretary), Mr. S. Casson, Prof. H. J. Fleure, Mr. H. J. E. Peake. 

To report on the present state of knowledge of the relation of early Palseolithic 
Implements to Glacial Deposits. — Mr. H. J. E. Peake (Chairman), Mr. E. N. 
Fallaize (Secretary), Mr. H. Balfour, Prof. P. G. H. Boswell, Mr. M. Burkitt, Prof. 
P. F. Kendall, Mr. G. Lamplugh, Prof. J. E. Marr. £30. 

To investigate the Lake Villages in the neighbourhood of Glastonbury in connecti&Q 
with a Committee of the Somerset Archaeological and Natural History Society. — 
Sir W. Boyd Dawkins (Chairman^, Mr. Willoughby Gardner (Secretary), Mr. H. 
Balfour, Mr. A. Bulleid, Mr. F. S.' Palmer, Mr. H. J. E. Peake. 

To co-operate with a Committee of the Roya! Anthropological Institute in the explor- 
ation of Caves in the Derbyshire district. — Sir W. Boyd Dawkins (Chairynan), 
Mr. G. A. Garfitt [Secretary). Mr. Leslie Armstrong, Mr. M. Burkitt, Mr. E. N. 
Fallaize, Dr. Favell, Mr. Wilfrid Jackson, Dr. R. R. Marett, Mr. L. S. Palmer, 
Mr. H. J. E. Peake. £25 (including £16 45. 4rf. unexpended balance). 

To investigate processes of Growth in Children, with a view to discovering Differences 
due to Race and Sex, and further to study Racial Differences in Women. — Sir 
A. Keith (Chairman), Prof. H. J. Fleure (Secretary), Dr. A. Low, Prof. F. G. 
Parsons, Dr. F. C. Shrubsall. £20. (A proportion not exceeding two-thirds 
of this grant may be exjjended on railway fares incurred in course of the 

To conduct Excavations and prepare a Survey of the Coldrum Megalithie Monument. — 
Sir A. Keith (Chairman), Prof. H. J. Fleure (Secretary), Mr. H. J. E. Peake. 

To report on the existence and distribution of Megalithie Monuments in the Isle of 
Man.— Prof. H. J. Fleure (Chairman), Dr. Cyril Fox (Secretary), Mr. O. G. S. 
Crawford, Sir W. Herdman, Mr. P. M. C. Kermode, Rev. Canon Quine. 

To report on proposals for an Anthropological and Archaeological Bibliography, with 
power to co-operate with other bodies. — Dr. A. C. Haddon (Chairman), Mr. E. N. 
Fallaize (Secretary), Dr. T. Ashby, Mr. W. H. Barker, Mr. O. G. S. Crawford, 
Prof. H. J. Fleure, Prof. J. L. Myres, Mr. H. J. E. Peake, Dr. D. Randall-Maclver, 
Mr. T. Sheppard. 

To report on the progress of Anthropological Teaching in the present century. — 
Dr. A. C. Haddon (Chairman), Prof. J. L. Myres [Secretary), Prof. H. J. Fleure, 
Dr. R. R. Marett, Prof. C. G. Seligman. 


To conduct l*]thno{i;raphical investigations in British Columbia. — Prof. G. Elliot Smith 

{(Jhiiirmini), Dr. F. C Shrubsall (Secretary), Prof. H. J. Fleure, Prof. C. G. Seligman. 

To conduct Explorations on early Neolithic Sites in Holderness. — Mr. H. J. E. Peake 

(Chairman), Mr. A. Leslie Armstrong (Secretary), Mr. M. Burkitt, Dr. R. V. 

Favell, Mr. G. A. Garfitt, Mr. Wilfrid Jackson, Mr. L. S. Palmer. 


Muscular Stiffness in relation to Respiration. — Prof. A. V. Hill (Chairman), Dr. Ff. 
Roberts (Secretary), Mr. J. Barcroit. £25. 

The Cost of Cycling with varied rate and work. — Prof. J. S. Macdonald (Chairman), 
Dr. F. A. Duffield (Secretary). £50. 


The Place of Psychology in the Medical Curriculum. — Prof. G. Robertson (Chairman), 
Dr. W. Brown (Secretary), Dr. J. Drever, Dr. R. G. Gordon, Dr. C. S. Myers, Prof. 
T. H. Pear, Dr. F. C. Shrubsall. 

Vocational Tests. — Dr. C. S. Myers (Chairman), Dr. G. H. Miles (Secretary), Mr. C. 
Burt, Prof. T. H. Pear, Mr. F. Watts, Dr. LI. Wynn-Jones. 

The Character of a first-year University in Experimental Psycholoijy. — Dr. .J. 
Drever (Chairman), Dr. May Collins (Secretary), Mr. F. C. BartlettVMr. R. J. 
Bartlett, Dr. C. Burt, Dr. Shepherd Dawson, Mr. A. E. Heath. Dr. LI. Wynn- 
Jones, Prof. T. H. Pear. 

The uniformity of Terminology and Standards in the Diagnosis of Mental Deficiencj'. — 
Dr. C. Burt (Chairman), Miss Evel3Ti Fox (Secretary), Miss L. G. Fildes, Dr. 
Kennedy Eraser, Dr. F. C. Shrubsall. 


The Physiology and Life-history of Marine Algaj at Port Erin. — Prof. J. McLean 
Thompson (Chairman), Dr. M. Knight (Secretary), Prof. F. E. Weiss. £25 
(including £15 for travelling fares). 

Index Kewensis. — Sir D. Prain (Chairman), Dr. A. W. Hill (Secretary), Prof. J. B. 
Farmer, Dr. A. B. Rendle, Prof. W. Wright Smith. £60. 

Botanical Survey of Sherwood Forest. — Prof. R. H. Yapp (Chairman), Dr. H. S. Holden 
(Secretary), Mr. A. G. Tansley. £20 (including £5 for travelling fares). 


Training in Citizenship.— Rt. Rev. J. E. C. Welldon (Chairman), Mr. C. H. Blakiston, 
Mr. G. D. Dunkerley. Mr. W. D. Eggar, Mr. J. C. Maxwell Garnett. Sir R. A. 
Gregory, Miss E. P. Hughes, Sir T. Morison. (With jiower to retain balance in 
hand from proceeds of sale of reports.) 

To inquire into the Practicability of an International Auxiliary Language. — Dr. H. 
Forster Morley (Chairman), Dr. E. H. Tripp (Secretary), Mr. E. Bullough, Prof. 
F. G. Donnan, Prof. J. J. Findlay, Sir Richard Gregory, Mr. W. B. Hardy, Dr. 
C. W. Kimmins, Sir E. Cooper Perry, Mr. Nowell Smith,Mr. A. E. Twentj^man. £3. 

To consider the educational training of boys and girls in Secondary Schools for over- 
seas life. — Rev. H. B. Gray (Chairman), Mr. C. E. Browne (Secretary), Dr. J. 
Vargas Eyre, Sir R. A. Gregorj^ Sir J. Russell. £5. 


Corresponding Societies Committee. — The President of the Association (Chairman 
ex-officio), Mr. T. Sheppard (Vice-Chairman), the General Secretaries, the General 
Treasurer, Dr. F. A. Bather, Mr. 0. G. S. Crawford, Prof. P. F. Kendall, Mr. 
Mark L. Sykes, Dr. C. Tierney, Prof. W. W. Watts, Mr. W. Whitaker ; with 
authority to co-opt representatives of Scientific Societies in the locality of the 
Annual Meeting. £40 for preparation of bibliography and report. 


An Tinconditional gift of £10,000 was made to the Association at the 
Dundee Meeting, 1912, by Mr. (afterwards Sir) J. K. Caird, LL.D., of 

The Council, in its report to the General Committee at the Birming- 
ham Meeting, made certain recommendations as to the administration 
of this Fund. These recommendations were adopted, with the Report, 
by the General Committee at its meeting on September 10, 1913. 

The allocations made from the Fund by the Council to September 
1922 will be found stated in the Report for 1922, p. xxxi. 

In and since 1921, the Council have authorised expenditure from 
accumulated income of the fund upon grants to Research Committees 
approved by the General Committee by way of supplementing sums 
available from the general funds of the Association, and in addition to 
grants ordinarily made by, or applied for from, the Council. 

Sir J. K. Caird, on September 10, 1913, made a further gilt of £1,000 
to the Association, to be devoted to the study of Radio-activity. In 
1920 the Council decided to devote the principal and interest of this gift 
at the I'ate of £250 per annum for five years to purposes of the research 
intended. The grants for the year ending March 24, 1922 and 1923, 
were made to Sir E. Rutherford, F.R.S. The grant for the year ending 
March 24, 1924, was made to Prof. F. Soddy, F.R.S. 


The following Eesolutions and Recommendations were referred to 
the Council by the General Committee at Liverpool for co-nsideration 
and, if desirable, for action: — 

Resolutions Relating to Science Museum Building, South 

From Section A. 

(la) The Committee of Section A, having learned with regret that it is the inten- 
tion of the Government to complete at present only a portion of the accommodation 
for the science collections, which Sir Hugh Bell's Committee considered urgently 
required, request the Council to take such steps as may seem to them most 
suitable to secure a reconsideration of the question with a view to the early 
completion of the whole plan. 

■ From Section B. 

(lb) That in the opinion of this Section the establishment of a Science Museum, 
representative of all branches of Science, in which Chemistry shall be fully 
represented, is of great importance, and urges that the scheme proposed in 
1912 be carried out with the least possible delay. 

From Section C. 

(Ic) The Sectional Committee of Section C is strongly of opinion that the general 
scheme for museum buildings should be continued and regarded as urgent, and 
that, in particular, part of the scheme relating to the transfer of the Museum 
of Practical Geology and the offices of the Geological Survey should be effected 
without delay. 

The Committee believes that it would be of great advantage to the public 
that the stratigraphical, paleeontological, mineralogical, and economic exhibits 
in the National Museum should be housed in close proximity with one another. 

From Section D. 

(Id) That this Section hopes that the scheme of 1913 for the complete housing of 
the Science Museums in South Kensington be proceeded upon with all possible 

From Section E. 

(le) The Committee of Section E learn with regret that the science collections 
at the Science Museum, South Kensington, are being withdrawn from exhibition 
for a considerable period on account of lack of space. 

They recommend that the General Committee should urge strongly upon 
H.M. Govenmient the importance of completing the whole of the eastern block 
of the new Science Museum buildings forthwith, and of carrying out as soon as 
may be practicable th3 building scheme prepared by the Departmental Committee 
of 1910-12. 

From Section G. 

(It") The Committee, having considered the letter of Sir Hugh Bell, desire to 
place on record (1) their regret at learning that the already inadequate accom- 
modation of the Science Museum has been further curtailed to make room 


for the War Mujcuni, and (2) their disapproval of the delay in bringing the 
buildings and equipment of our National Museum of Science up to a standard 
commensurate with the national importance of pure and applied science. 

The Committee consider that the Council of the British Association should, 
either alone or in conjunction with other bodies, take steps to urge upon the 
authorities the vital importance of providing ade(]uate museum accommodation 
in subjects so fundamentally essential to our national development and well-being. 

From Section H. 

To recommend that the Council of the British Association urge upon the (1 2) 
Government the desirability of providing at not too distent a date adequate and 
suitable accommodation for the proper housing and display of the national 
scientific collections. 

From Section K. 

That the Council of the British Association urge the Government to expedite (Ih) 
the completion of the Science Museum and the transfer of the Jermyn Street 
Geological Museum to South Kensington as recommended in the Report pre- 
sented in 1911 and 1912 by the Departmental Committee. 

Fro))i Section L. 

That Section L cordially agrees with the pretest being presented against the v •' 
delay which has taken place in the completion of the scheme of the National 
Museum for Science. 

From Section M. 

The Committee of Section M is strongly of opinion that every effort should (Ik) 
be made at the present time to secure as rapidly as possible the accommodation 
necessary for the adequate housing of the Science collection. 

It is particularly anxious that suitable provision should be made for an 
agricultural exhibit worthy of the prominent position which agriculture occupies 
among the industries of this country. 

From the Conference of Delegates of Corresponding Societies. 
To represent to His Majesty's Government the urgent need for more ample (^J) 
provision for the Science Museum, and for closer co-ordination between the 
principal national collections of scientific material. 

Other Eesolutions. 

From Sections C, D, G, H, I, M, and the Conference of Delegates of 
Corresponding Societies. 

To represent to His Majesty's Government, in view of recent proposals to (2) 
utilise for naval, military, or commercial purposes sites of historic or scientific 
interest or of natural beauty, such as Avebury, Holmbury Hill, and Lulworth 
Cove and its neighbourhood, the urgent need of more effective protection of 
such sites from disfigurement or obstruction. 

From Sections C, E, G, H, I, M, and the Conference of Delegates of 
Corresponding Societies. 

To request the Director-General of the Ordnance Survey to reconsider his 
decision to discontinue the issue by the Ordnance Survey of quarter-sheets of 
the six-inch map on the ground that, if quarter-sheets are not available, teachers, 
students, and others engaged in various kinds of research on local and regional 
distributions will be put to expense and inconvenience in providing themselves 
with the sheets necessary for their work-' . c.^.j-.v't.; ,..:■,&*! itti-!: ■ ",, 

1923 r 



From Section E. 
(Aa) That this Committee of Section E recommends that the Report of the Research 
^ Committee on Geography be issued on sale as a Reprint of the British Associa- 

tion, and that the Secretary of the British Association be authorised to take 
such steps as are deemed necessary for the wide publicity of the pamphlet. 

From Section L. 
(4b) That the Report on teaching of Geography shall be included in the publica- 
tions of the Association. 



From Section G. 
That this Committee should endeavour to obtain a wider publication of the 
work of the Committee on Complex Stresses, and that with this object, in the 
first place, the Reports published in 1913 on the subjects of ' Combined Stresses ' 
and ' The Collapse of Tubes ' should be brought up to date by their authors, 
and, after discussion by the Complex Stress Committee, steps should be taken 
with a view to their republication. As a first step the Council of the British 
Association should be approached and its general approval of the foregoing 
proposal obtained. 

From Section H. 

The Sectional Committee recommends the adoption of the suggestion of the 
Committee on the Age of Stone Circles that ' finds ' from Avebury may be 
deposited in Devizes Museum and duplicates be distributed among other 
museums. It is recommended further that in the distribution of duplicates 
preference be given to museums in the vicinity. 

From the Conference of Delegates of Corresponding Societies. 

(7) To recommend that the publications of scientific societies should conform 
so far as possible to a standard size of page for convenience in dealing with 
off-prints ; and that for octavo publications the size of the British Association's 
Report be adopted as the standard. 

(8) To urge the adoption by scientific societies of the bibliographical recom- 
mendations contained in the current Report of the Zoological Publications 

(9) To call the attention of local scientific societies to the need for prompt 
and systematic supervision, in the interests of scientific record, of all sections 
and other excavations which were opened during the construction of new roads 
or other public works. 

'10) That this Conference suggests for the consideration of the Council that the 
change of the British gallon to 4 litres would be objectionable, because the gallon 
of water weighs 10 lb., which is an important fact in physical and engineering 

To recommend the General Committee to accept the invitation received from 
the President of the Museums Association to hold the Conference of Delegates 
in connection with that Association's meeting at Wembley in July 1924, without 
prejudice to any provision which may be possible for a Conference of Repre- 
sentatives of local societies at the Toronto meeting. 



Section A. — Extended Abstracts of Professor P. Ehrenfest's Paper, 
' Remarks on Quantisation,' and Professor Langevin's Paper on ' The Structure 
of Atoms and their Magnetic Properties.' 

B MAH24 P 



D.Sc, LL.D., Ph.D., F.R.S., 


It was in 1896 that this Association last met in Liverpool, under the 
presidency of the late Lord Lister, that great pioneer in antiseptic 
surgery, whose memory is held in aiifectionate remembrance by all 
nations. His address, wliich dealt mainly with the history of the 
application of antiseptic methods to surgery and its connection with 
the work of Pasteur, that prince of experimenters, whose birth has 
been so fittingly celebrated this year, gave us in a sense a completed 
page of brilliant scientific history. At the same time, in his opening 
remarks. Lister emphasised the importance of the discovery by Rontgen 
of a new type of radiation, the X-rays, which we now see marked the 
beginning of a new and fruitful era in another branch of science. 

The visit to your city in 1896 was for me a memorable occasion, 
for it was here that I first attended a meeting of this Association, and 
here that I read my fii'st scientific paper. But of much more import- 
ance, it was here that I benefited by the opportunity, which these 
gatherings so amply afford, of meeting for the first time many of the 
distinguished scientific men of this country and the foreign representa- 
tives of science who were the guests of this city on that occasion. The 
year 1896 has always seemed to me a memorable one for other reasons, 
for on looking back with some sense of perspective we cannot fail to 
recognise that the last Liverpool Meeting marked the beginning of what 
has been aptly termed the heroic age of Physical Science. Never before 
in the history of physics has there been witnessed such a period of 
intense activity when discoveries of fundamental importance have 
followed one another with such bewildering rapidity. 

The discovery of X-rays by Rontgen had been published to the 
world in 1896, while the discovery of the radioactivity of uranium 

c 2 


by Becquerel was announced early in 1896. Even the most imagina- 
tive of our scientific men could never have dreamed at that time of 
the extension of our knowledge of the structure of matter that was to 
develop from these two fundamental dascoveries, but in the records of 
the Liverpool Meeting we see the dawning recognition of the possible 
consequences of the discovery of X-rays, not only in their application 
to medicine and surgery, but as a new and powerful agent for attacking 
some of the fundamental problems of physics. The address of Pro- 
fessor J. J. Thomson, President of Section A, was devoted mainly to 
a discussion of the nature of the X-rays and the I'emarkable properties 
induced in gases by the passage of X-rays through them — the beginning 
of a new and fruitful branch of study. 

In applied physics, too, this year marked the beginning of another 
advance. In the discussion of a paper which I had the honour to 
read, on a new magnetic detector of electrical waves, the late Sir 
"William Preece told the meeting of the successful transmission of 
signals for a few hundred yards by electric waves which had been made 
in England by a young Italian, G. Marconi. The first public demonstra- 
tion of signalling for short distances by electric waves had been given 
by Sir Oliver Lodge at the Oxford Meeting of this Association in 1894. 
It is startling to recall the rapidity of the development from such small 
beginnings of the new method of wireless intercommunication over the 
greatest terrestrial distances. In the last few years this has been followed 
by the even more rapid growth of the allied subject of radiotelephony as 
a practical means of broadcasting speech and music to distances only 
limited by the power of the transmitting station. The rapidity of these 
technical advances as an illustration of the close interconnection that 
must exist between pure and appUed science if rapid and sure progress is 
to be made. The electrical engineer has been able to base his technical 
developments on the solid foundation of Maxwell's electromagnetic 
theory and its complete verification by the researches of Hertz, and also 
by the experiments of Sir Oliver Lodge in this University — a verifica- 
tion which was completed long before the practical possibilities of this 
new method of signalling had been generally recognised. The later 
advances in radiotelegraphy and radiotelephony have largely depended 
on the application of the results of fundamental researches on the 
properties of electrons, as illustrated in the use of the thermionic valve 
or electron tube which has proved such an invaluable agent both for 
the transmission and reception of electric waves. 

It is of great interest to note that the benefits of this union of pur© 
and applied research have not been one-sided. If the fundamental 
researches of the workers in pure science supply the foundations on 
which the applications are surely built, the successful practical applica- 
tion in turn quickejis and extends the interest of the investigator in 


the fundamental problem, while the development of new methods and 
appliances required for technical purposes often provides the investi- 
gator with means of attacking still more difficult questions. This 
important reaction between pure and applied science can be illustrated 
in many branches of knowledge. It is particularly manifest in the 
industrial development of X-ray radiography for therapeutic and indus- 
trial purposes, where the development on a large scale of special X-ray 
tubes and improved methods of excitation has given the physicist much 
more efficient tools to cany out his researches on the nature of the rays 
themselves and on the structure of the atom. In this age no one can 
draw any sharp line of distinction between the importance of so-called 
pure and applied research. Both are equally essential to progress, 
and we cannot but recognise that without flourishing schools of research 
on fundamental matters in our universities and scientific institutions 
technical research must tend to wither. Fortunately there is little 
need to labour this point at the moment, for the importance of a training 
in pure research has been generally recognised. The Department of 
Scientific and Industrial Research has made a generous provision of 
grants to train qualified young men of promise in research methods in 
our scientific institutions, and has aided special fundamental researches 
which are clearly beyond the capacity of a laboratory to finance from 
its own funds. Those who have the responsibility of administering the 
grants in aid of reseai'ch both for pure and applied science will need all 
their wisdom and experience to make a wise allocation of funds to 
secure the maximum of results for the minimum of expenditure. It 
is fatally easy to spend much money in a direct frontal attack on some 
technical problem of importance when the solution may depend on 
some addition to knowledge which can be gained in some other field of 
scientific inquiry possibly at a trifling cost. It is not in any sense my 
purpose to criticise those bodies which administer funds for fostering 
pure and applied research, but to emphasise how difficult it is to strike 
the correct balance between the expenditure on pure and applied science 
in order to achieve the best results in the long run. 

It is my intention this evening to refer very briefly to some of the 
main features of that great advance in knowledge of the nature of 
electricity and matter which is one of the salient features of the interval 
since the last meeting of this Association in Liverpool. 

In order to view the extensive territory which has been conquered 
by science in this interval, it is desirable to give a brief summary of 
the state of knowledge of the constitution of matter at the beginning 
of this epoch. Ever since its announcement by Dalton the atomic 
theory has steadily gained ground, and formed the philosophic basis 
for the explanation of the facts of chemical combination. In the early 
stages of its application to physics and chemistiy it was unnecessary 


to have any detailed knowledge of the dimensions or structure of the 
atom. It was only necessary to assume that the atoms acted as indi- 
vidual units, and to know the relative masses of the atoms of the 
different elements. In the next stage, for example, in the kinetic 
theory of gases, it was possible to explain the main properties of gases 
by supposing that the atoms of the gas acted as minute perfectly elastic 
spheres. During this period, by the application of a variety of methods, 
many of which were due to Lord Kelvin, rough estimates had been 
obtained of the absolute dimensions and mass of the atoms. These 
brought out the minute size and mass of the atom and the enormous 
number of atoms necessary to produce a detectable effect in any kind 
of measurement. From this arose the general idea that the atomic 
theory must of necessity for ever remain unverifiable by direct experi- 
ment, and for this reason it was suggested by one school of thought 
that the atomic theory should be banished from the teaching of 
Chemistry, and that the law of multiple proportions should be accepted 
as the ultimate fact of Chemistry. 

While the vaguest ideas were held as to the possible structure of 
atoms, there was a general belief among the more philosophically 
minded that the atoms of the elements could not be regarded as simple 
unconnected units. The periodic variations of the properties of the 
elements brought out by Mendeleef were only explicable if atoms were 
similar structures in some way constructed of similar material. We 
shall see that the problem of the constitution of atoms is intimately 
connected with our conception of tbe nature of electricity. The 
wonderful success of the electromagnetic theory had concentrated atten- 
tion on the medium or ether surrounding the conductor of electricity, 
and little attention had been paid to the actual carriers of the electric 
current itself. At the same time the idea was generally gaining ground 
that an explanation of the results of Faraday's experiments on electro- 
lysis was only possible on the assumption that electricity, like matter, 
was atomic in nature. The name ' electron ' had even been given to 
this fundamental unit by Johnstone Stoney, and its magnitude roughly 
estimated, but the full recognition of the significance and importance 
of this conception belongs to the new epoch. 

For the clarifying of these somewhat vague ideas, the proof in 
1897 of the independent existence of the electron as a mobile electrified 
unit, of mass minute compared with that of the lightest atom, was of 
extraordinary importance. It was soon seen that the electron must 
be of a constituent of all the atoms of matter, and that optical 
spectra had their origin in their vibrations. The discovery of the 
electron and the proof of its liberation by a variety of methods from 
all the atoms of matter was of the utmost significance, for it strength- 
ened the view that the electron was probably the common unit in the 


structure of atoms which the periodic variation of the chemical pi'o- 
perties had indicated. It gave for the first time some hope of the 
success of an attack on that most fundamental of all problems — the 
detailed structure of the atom. In the early development of this subject 
science owes much to the work of Sir J. J. Thomson, both for the 
boldness of his ideas and for his ingenuity in developing methods for 
estimating the number of electrons in the atom, and of probing its 
structure. He early took the view that the atom must be an electrical 
structure, held together by electrical forces, and showed in a general 
way lines of possible explanation of the variation of physical and 
chemical properties of the elements, exemplified in the periodic law. 

In tlie meantime our whole conception of the atom and of the 
magnitude of the forces which held it together were revolutionised by 
the study of radioactivity. The discovery of radium was a great step 
in advance, for it provided the experimenter with powerful sources of 
radiation specially suitable for examining the nature of the characteristic 
radiations which are emitted by the radioactive bodies m general. It 
was soon shown that the atoms of radioactive matter were undergoing 
spontaneous transfomiation, and that the characteristic radiations 
emitted, viz. the a, p, and y rays, were an accompaniment and conse- 
quence of these atomic explosions. The wonderful succession of changes 
that occur in uranium, more than thirty in number, was soon disclosed 
and simply interpreted on the transformation theory. The radioactive 
elements provide us for the first time with a glimpse into Nature's 
laboratory, and allow us to watch and study but not control the 
changes that have their origin in the heart of the radioactive atoms. 
These atomic explosions involve energies which are gigantic compared 
with those involved in any ordinary physical or chemical process. In 
the majority of cases an a particle is expelled at high speed, but in 
others a swift electron is ejected often accompanied by a yray, which is 
a very penetrating X-ray of high frequency. The proof that the a 
particle is a charged helium atom for the first time disclosed the import- 
ance of helium as one of the units in the structure of the radioactive 
atoms, and probably also in that of the atoms of most of the ordinary 
elements. Not only then have the radioactive elements had the greatest 
direct influence on natural philosophy, but in subsidiary ways they 
have provided us with experimental methods of almost equal import- 
ance. The use of a particles as projectiles with which to explore the 
interior of the atom has definitely exhibited its nuclear structure, has 
led to artificial disintegration of certain light atoms, and promises to 
yield more information yet as to the actual structure of the nucleus 

The influence of radioactivity has also extended to yet another field 
of study of fascinating interest. We have seen that the first rough 


estimates of the size and mass of the atom gave httle hope that we 
could detect the effect of a single atom, The discovery that the radio- 
active bodies expel actual charged atoms of helium with enormous 
energy altered this aspect of the problem. The energy associated with 
a single a particle is so great that it can readily be detected by a variety 
of methods. Each a particle, as Sir Wm. Orookes first showed, pro- 
duces a flash of light easily visible in a dark room when it falls on a 
screen coated with crystals of zinc sulphide. This scintillation method 
of counting individual particles has proved invaluable in many re- 
searches, for it gives us a method of unequalled delicacy for studying 
the effects of single atoms. The a particle can also be detected electri- 
cally or photographically, but the most powerful and beautiful of all 
methods is that perfected by Mr. C. T. R. Wilson for observing the 
track through a gas not only of an a particle hut of any type of pene- 
trating radiation which produces ions or of electrified particles along its 
path. The method is comparatively simple, depending on the fact, 
first discovered by him, that if a gas saturated with moisture is suddenly 
cooled each of the ions produced by the radiation becomes the nucleus 
of a visible drop of water. The water-drops along the track of the 
a particle are clearly visible to the eye, and can be recorded photo- 
graphically. These beautiful photographs of the effect produced by 
single atoms or single electrons appeal, I think, greatly to all scientific 
men. They not only afford convincing evidence of the discrete nature 
of these particles, but give us new courage and confidence that the 
scientific methods of experiment and deduction are to be rehed upon in 
this field of inquiry; for many of the essential points brought out so 
clearly and concretely in (these photographs were correctly deduced 
long before such confirmatory photographs were available. At the 
same time, a minute study of the detail disclosed in these photographs 
gives us most valuable information and new clues on many recondite 
effects produced by the passage through matter of these flying projec- 
tiles and penetrating radiations. 

In the meantime a number of new methods had been devised to 
fix with some accuracy the mass of the individual atom and the number 
in any given quantity of matter. The concordant results obtained by 
widely different physical principles gave great confidence in the correct- 
ness of the atomic idea of matter. The method found capable of most 
accuracy depends on the definite proof of the atomic nature of elec- 
tricity and the exact valuation of this fundamental unit of charge. 
We have seen that it was early surmised that electricity was atomic 
in nature. This view was confirmed and extended by a study of the 
charges carried by electrons, a particles, and the ions produced in gases 
by X-rays and the rays from radioactive matter. It was first shown 
by Tbwnsend that the positive or negative charge carried by an ion in 


gases was invariably equal to the charge carried by the hydrogen ion 
in the electrolysis of water, which we have seen was assumed, and 
assumed correctly, by Johnstone Stoney to be the fundamental unit 
of charge. Various methods were devised to measure the magnitude 
of this fundamental unit ; the best known and most accurate is 
Millikan's, which depends on comparing the pull of an electric field on 
a chai'ged droplet of oil or mercury with the weight of the drop. His 
experiments gave a most convincing proof of the correctness of the 
electronic theory, and gave a measure of this unit, the most funda- 
mental of all physical units, with an accuracy of about one in a 
thousand. Knowing this value, we can by the aid of electrochemical 
data easily deduce the mass of the individual atoms and the number 
of molecules in a cubic centimetre of any gas with an accuracy of 
possibly one in a thousand, but certainly better than one in a hundred. 
When we consider the minuteness oi the unit of electricity and of the 
mass of the atom this experimental achievement is one of the most 
notable even in an era of great advances. 

The idea, of the atomic nature of electricity is very closely connected 
with the attack on tlie problem of the structure of the atom. If the 
atom is an electrical structure it can only contain an integral number 
of charged units, and, since it is ordinarily neutral, the number of units 
of positive charge must equal the number of negative. One of the 
main difficulties in this problem has been the uncertainty as to the 
relative part played by positive and n,egative electricity in the structure 
of the atom. We know that the electron has a negative charge of one 
fundamental unit, while the charged hydrogen atom, whether in elec- 
trolysis or in the electric discharge, has a charge of one positive unit. 
But the mass of the electron is only 1/1840 of the mass of the hydrogen 
atom, and though an extensive search has been made, not the slightest; 
evidence has been found of the existence of a positive electron of small 
mass like the negative. In no case has a positive charge been found 
associated with a mass less than that of the charged atom of hydrogen. 
This difference between positive and negative electricity is at fu'st sight 
very surprising, but the deeper we pursue our inquiries the more this 
fundamental difference between the units of positive and negative 
electricity is emphasised. In fact, as we shall see later, the atoms are 
quite unsymmetrical structures with regard to the positive and negative 
units contained in them, and indeed it seems certain that if there were 
not this difference in mass bet\\'een the two units, matter, as we know 
it, could not exist. 

It is natural to inquire what explanation can be given of this striking 
difference in mass of the two units. I think all scientific men are 
convinced that the small mass of the negative electron is to be entirely 
associfuted with the energy of its electrical structure, so that the electron 


may be regarded as a disembodied atom of negative electricity. We 
know that an electron in motion, in addition to possessing an electric 
field, also generates a magnetic field around it, and energy in the 
electromagnetic form is stored in the medium and moves with it. This 
gives the electron an apparent or electrical mass which, while nearly 
constant for slow speeds, increases rapidly as its velocity approaches 
that of light. This increase of mass is in good accord with calculation, 
whether based on the ordinary electrical theory or on the theory of 
relativity. Now we know that the hydrogen atom is the lightest of all 
atoms, and is presumably the simplest in structure, and that the 
charged hydrogen atom, which we shall see is to be regarded as the 
hydrogen nucleus, carries a unit positive charge. It is thus natural 
to suppose that the hydrogen nucleus is the atom of positive electricity, 
or positive electron, analogous to the negative electron, but differing 
from it in mass. Electrical theory shows that the mass of a given 
charge of electricity increases with the concentration, and the greater 
mass of thei hydrogen nucleus would be accounted for if its size were 
much smaller than that of the electron. Such a conclusion is sup- 
ported by evidence obtained from the study of the close collisions of 
a particles with hydrogen nuclei. It is found that the hydrogen nucleus 
must be of minute size, of radms less than the electron, which is 
usually supposed to be about 10-" cms. ; also the experimental evidence 
is not inconsistent with the view that the hydrogen nucleus may 
actually be much smaller than the electron. While the greater mass 
of the positive atom of electricity may be explained in this way, we are 
still left with the enigma why the two units of electricity should differ 
so markedly in this respect. In the present state of our knowledge it 
does not seem possible to push this inquiry further, or to discuss the 
problem of the relation of these two units. 

We shall see that there is the strongest evidence that the atoms 
of matter are built up of these two electrical units, viz. the electron 
and the hydrogen nucleus or proton, as it is usually called when it 
forms part of the structure of any atom. It is probable that these two 
are the fundamental and indivisible units which build up our universe, 
but we may reserve in our mind the possibility that further inquiry 
may some day show that these units are complex, and divisible into 
even more fundamental entities. On the views we have outlined 
the mass of the atom is the sum of the electrical masses of the individual 
charged units composing its structure, and there is no need to assume 
that any other kind of mass exists. At the same time, it is to be borne 
in mind that the actual mass of an atom may be somewhat less than 
the sum of the masses of component positive and negative electrons 
when in the free state. On account of the very close proximity of the 
charged units in the nucleus of an atom, and the consequent disturbance 


of the electric and magnetic field surrounding them, such a decrease 
of mass is to be anticipated on general theoretical grounds. 

We must now look back again to the earlier stages of the present 
epoch in order to trace the development of our ideas on the detailed 
structure of the atom. That electrons as such were important con- 
stituents was clear by 1900, but little real progress followed until the 
part played by the positive charges was made clear. New light was 
thrown on this subjeot by examining the deviation of a particles when 
they passed through the atoms of matter. It was found that occa- 
sionally a swift a particle was deflected from its rectilinear path through 
more than a right angle by an encounter with a single atom. In such 
a collision the laws of dynamics ordinarily apply, and the relation 
between the velocities of the colliding atoms before and after collision 
are exactly the same as if the two colliding particles ai'e regarded as 
perfectly elastic spheres of minute dimensions. It musit, however, be 
borne in mind that in these atomic collisions there is no question of 
mechanical impacts such as we observe with ordinary matter. The 
reaction between the two particles occurs through the intermediary of 
the powerful electric fields that surround them. Beautiful photo- 
graphs illustrating the accuracy of these laws of collision between an 
a particle and an atom have been obtained by Messrs. Wilson, Blackett, 
and others, while Mr. Wilson has recently obtained many striking 
illustrations of collisions between two electrons. Remembering the 
great kinetic energy of the a particle, its deflection through a large 
angle in a single atomic encounter shows clearly that very intense 
deflecting forces exist inside the atom. It seemed clear that electric 
fields of the required magnitude could be obtained only if the main 
charge of the atom were concentrated in a minute nucleus. From this 
arose the conception of the nuclear ato^m, now so well known, in which 
the heart of the atom is supposed to consist of a minute but massive 
nucleus, cai'rying a positive charge of electricity, and surrounded at a 
•distance by the requisite number of electrons to form a neutral atom. 

A detailed study of the scattering of a particles at different angles, 
by Geiger and Marsden, showed that the results were in close accord 
with this theory, and that the intense electric forces near the nucleus 
varied according tO' the ordinary inverse square law. In addition, the 
experiments allowed us to fix an upper limit for the dimensions of the 
nucleus. For a heavy atom like that of gold the radius of the nucleus, 
if supposed to be spherical, was less than one thousandth of the radius 
of the complete atom surrounded by its electrons, and certainly less 
than 4xlO~'^cms. All the atoms were found to show this nuclear 
structure, and an approximate estimate was made of the nuclear charge 
of different atoms. This type of nuclear atom, based on direct experi- 
mental evidence, possesses some very simple properties. It is obvious 


that the number of units of resultan(t positive charge in the nucleus 
fixes the number of the outer planetary electrons in the neutral atom. 
In addition, since these outer electrons are in some way held in equili- 
brium by the attractive forces from the nucleus, and, since we are 
confident from general physical and chemical evidence that all atoms 
of any one element are identical in their external structure, it is clear 
that their arrangement and motion must be governed entirely by the 
magnitude of the nuclear charge. Since the ordinary chemical and 
physical properties are to be ascribed mainly to the configuration and 
motion of the outer electrons, it follows that the properties of an atom 
are defined by a whole number representing its nuclear charge. It 
thus becomes of great importance to determine the value of this nuclear 
charge for the atoms of all the elements. 

Data obtained from the scattering of a particles, and also from the 
scattering of X-rays by light elements, indicated that the nuclear charge 
of an element was numerically equal to about half the atomic weight 
in terms of hydrogen. It was fairly clear from general evidence that 
the hydrogen nucleus had a charge one, and the helium nucleus (the 
a particle) a charge two. At this stage another discovery of great im- 
portance provided a powerful method of attack on this problem. The 
investigation by Laue on the diffraction of X-rays by crystals had 
shown definitely tliat X-rays were electromagnetic waves of much 
shorter wave-length than light, and the experiments of Sir William 
Bragg and W. L. Bragg had provided simple methods for studying the 
spectra of a beam of X-rays. It was found that the spectrum in 
general shows a continuous backgi'ound on which is superimposed a 
spectrum of bright lines. At this stage H. G. J. Moseley began a 
research with the intention of deciding whether the properties of an 
element depended on its nuclear charge rather than on its atomic weight 
as ordinarily supposed. For this purpose the X-ray spectra emitted 
by a number of elements were examined and found to be all similar 
in type. The frequency of a given line was found to vary very nearly 
as the square of a whole number which varied by unity in passing 
from one element to the next. Moseley identified tliis whole number 
with the atomic or ordinal number, of the elements when arranged in 
increasing order of atomic weight, allowance being made for the known 
anomalies in the periodic table and for certain gaps corresponding to 
possible but missing elements. He concluded that the atomic number 
of an element was a measure of its nuclear charge, and the con'ectness 
of this deduction has been recently verified by Chadwick by direct 
experiments on the scattering of a particles. Moseley 's discovery is 
of fundamental importance, for it not only fixes the number of electrons 
in all the atoms, but shows conclusively that the properties of an atom, 
as had been surmised, are determined not by its atomic weight but 


by its nuclear charge. A relation of unexpected simplicity is thus 
found to hold between the elements. No one could have anticipated 
that with few exceptions all atomic numbers between hydrogen 1, and 
uranium 92, would correspond to known elements. The great power 
of Moseley's law in fixing the atomic number of an element is well 
illustrated by the recent discovery by Coster and Hevesy in Copen- 
hagen of the missing element of atomic number 72, which they have 
named 'hafnium.' 

Once the salient features of the structure of atoms have been fixed 
and the number of electrons known, the further study of the structure 
of the atom falls naturally into two great divisions : one, the arrange- 
ment of the outer electrons which controls the main physical and 
chemical properties of an element, and the either the structure of the 
nucleus on which the mass and radioactivity of the atom depends. On 
the nuclear theory the hydrogen atom is of extreme simplicity, con- 
sisting of a singly-charged positive nucleus with only one attendant 
electron. The position and motions of the single electron must account 
for the complicated optical spectrum, and whatever physical and 
chemical properties are to be attributed to the hydrogen atom. The 
first definite attack on the problem of the electronic structure of the 
atom was made by Niels Bohr. He saw clearly that, if this simple 
constitution was assumed, it is impossible to account for the spectrum 
of hydrogen on the classical electrical theories, but that a radical depar- 
ture from existing views was necessary. For this purpose he applied 
to the atom the essential ideas of the Quantum Theory which 
had been developed by Planck for other purposes, and had been 
found of great service in explaining many fundamental difficulties in 
other branches of science. On Planck's theory radiation is emitted 
in definite units or quanta, in which the energy E of a radiation is 
equal to 7?v where v is the frequency of the radiation measured by the 
ordinary methods and h a universal constant. This quantum of radia- 
tion is not a definite fixed unit like the atom of electricity, for its 
magnitude depends on the frequency of the radiation. For example, 
the energy of a quantum is small for visible light, but becomes large 
for radiation of high frequency corresponding to the X-rays or the 
f rays from radium. 

Time does not allow me to discuss the underlying meaning of the 
quantum theory or the difiiculties connected with it. Certain aspects 
of the difficulties werc. discussed in the Presidential Address before this 
Association by Sir Oliver Lodge at Birmingham in 1913. It suffices 
to say that this theory has proved of great value in several branches 
of science, and is supported by a large mass of direct experimental 

In applying the quantum theory to the structure of the hydrogen 


atom Bohr supposed that the single electron could move in a number 
of stable orbits, controlled by the attractive force of the nucleus, with- 
out losing energy by radiation. The position and character of these 
orbits were defined by certain quantum relations depending on one or 
more whole numbers. It was assumed that radiation was only emitited 
when the electron for some reason was transferred from one stable 
orbit to another of lower energy. In such a case it was supposed that 
a homogeneous radiation was emitted of frequency v determined by the 
quantum relation E = /iv where E was the difference of the energy of 
the electron in the two orbits. Some of these possible orbits are 
oircular, others elliptical, with the nucleus as a focus, while if the 
change of mass of the electron with velocity is taken into account' the 
orbits, as Sommerfeld showed, depend on two quantum numbers, and 
are not closed, but consist of a nearly elliptical orbit slowly rotating 
round the nucleus. In this way it is possible not only to account for 
the series relations between the bright lines of the hydrogen spectrum, 
but also to explain the fine structure of the lines and the very compli- 
cated changes observed when the radiating atoms are exposed in a 
strong magnetic or electric field. Under ordinary conditions the 
electron in the hydrogen atom rotates in a circular orbit close to the 
nucleus, but if the atoms are excited by an electric discharge or other 
suitable method, the electron may be displaced and occupy any one 
of the stable positions specified by the theory. In a radiating gas 
giving the complete hydrogen spectrum there will be present many 
different kinds of hydrogen atoms, in each of which the electron 
describes one of the possible orbits specified by the theory. On this 
view it is seen that the variety of modes of vibration of the hydrogen 
atom is ascribed, not to complexity of the structure of the atom, but 
to the variety of stable orbits which an electron may occupy relative 
to the nucleus. This novel theory of the origin of spectra has been 
developed so as to apply not only to hydrogen but to all the elements, 
and has been instrumental in throwing a flood of light on the relations 
and origin of their spectra, both X-ray and optical. The information 
thus gained has been applied by Bohr to determine the distribution of 
the electrons I'ound the nucleus of any atom. The problem is obviously 
much less complicated for hydrogen than for a heavy atom, where each 
of the large number of electrons present acts on the other, and where 
the orbits descrihe^ are much more intricate than the orbit of the 
single electron in hydrogen. Notwithstanding the great difficulties of 
such a complicated system of electrons in motion, it has been possible 
to fix the quantum numbers that characterise the motion of each 
electron, and to form at any rate a rough idea of the character of the 

These planetary electrons divide themselves up into groups, according 


as their orbits are characterised by one or more equal quantum 
numbers. Without going into detail a few examples may be given to 
illustrate the conclusions which have been reached. As we have seen, 
the first element hydrogen has a nuclear charge of 1 and 1 electron ; the 
isecond, helium, has a charge 2 and 2 electrons, moving in coupled 
orbits on the detailed nature of which there is still some uncertainty. 
These two electrons form a definite group, known as the K group, 
which is common to all the elements except hydrogen. For increasing 
nuclear charge the K group of electrons retain their characteristics, 
but move with increasing speetl, and approach closer to the nucleus. 
As w© pass from helium of atomic number 2 to neon, number 10, a 
new group of electrons is added consisting of two sub-groups, each of 
four electrons, togethea- called the L group. This L group appears in 
all atoms of higher atomic number, and, as in the case of the K group, 
the speed of motion of the electrons inci'eases, and the size of their 
orbits diminishes with the atomic number. When once the L group 
has been completed a new and still more complicated M group of 
electrons ibegins forming outside it, and a similar process goes on until 
uranium, which has the highest atomic number, is reached. 

It may be of interest to try to visualise the conception of the atom 
we have so far reached by taking for illustration the heaviest atom, 
uranium. At the centre of the atom is a minute nucleus surrounded 
by a swirling group of 92 electrons, all in motion in definite orbits, 
and occupying but by no means filling a volume very large compared 
with that of the nucleus. Some of the electrons describe nearly circular 
orbits round the nucleus; others, orbits of a more elliptical shape whose 
axfes rotate rapidly round the nucleus. The motion of the electrons 
in the different groups is not necessarily confined to a definite region 
of the atom, but the electrons of one group may penetrate deeply into 
the region mainly occupied by another group, thus giving a type of 
inter-connection or coupling between the various groups. The maxi- 
mum speed of any electron depends on the closeness of the approach 
to the nucleus, but the outemiost electron will have a minimum speed 
of more than 1,000 kilometres per second, while the innermost K elec- 
trons have an average speed of more than 150,000 kilometres per 
second, or half the speed of light. When we visualise the extraordinary 
complexity of the electronic system we may be surprised that it has 
been possible to find any order in the apparent medley of motions. 

In reaching these conclusions, which we owe largely to Professor 
Bohr and his co-workers, every available kind of data about the different 
atoms has been taken into consideration. A study of the X-ray spectra, 
in particular, affords information of great value as to the arrangement 
of the various groups in the atom, while the optical spectinim and 
general chemical properties are of great importance in deciding the 


arrangements of the superficial electrons. While the solution of the 
grouping of the electrons proposed by Bohr has been assisted by cori- 
siderations of this kind, it is not empirical in character, but has been 
largely based on general theoretical considerations of the orbits of 
electrons that are physically possible on the generalised quantum theory. 
The real problem involved may be illustrated in the following way. 
Suppose the gold nucleus be in some way stripped of its attendant 
seventy-nine electrons and that the atom is reconstituted by the succes- 
sive addition of electrons one by one. According to Bohr, the atom 
will be reorganised in one way only, and one group after another will 
successively form and be filled up in the manner outlined. The nucleus 
atom has often been likened to a solar system where the sun corresponds 
to the nucleus and the planets to the electrons. The analogy, however, 
must not be pressed too far. Suppose, for example, we imagined that 
some large and swift celestial visitor traverses and escapes from our 
solar system without any catastrophe to itself or the planets. There 
will inevitably result permanent changes in the lengths of the month 
and year, and our system will never return to its original state. Con- 
trast this with the effect of shooting an electron or a particle through the 
electronic structure of the atom. The motion of many of the electrons 
will be disturbed by its passage, and in special cases an electron may be 
removed from its orbit and hurled out of its atomic system. In a short 
time another electron will fall into the vacant place from one of the 
outer groups, and this vacant place in turn will be filled up, and so on 
until the atom is again reorganised. In all cases the final state of the 
electronic system is the same as in the beginning. This illustration 
also serves to indicate the origin of the X-rays excited in the atom, for 
these arise in the process of reformation of an atom from which an 
electron has been ejected, and the radiation of highest frequency arises 
when the electron is removed from the K group. 

It is possibly too soon to express a final opinion on the accuracy of 
this theory which defines the outer structure of the atom, but there can 
be no doubt that it constitutes a great advance. Not only does it offer 
a general explanation of the optical and X-ray spectra of the atom, but 
it accounts in detail for many of the most characteristic features of the 
periodic law of Mendeleef. It gives us for the first time a clear idea 
of the reason for the appearance in the family of elements of groups 
of consecutive elements with similar chemical properties, such as the 
groups analogous to the iron group and the unique group of rare earths. 
The theory of Bohr, like all living theories, has not only correlated a 
multitude of isolated facts known about the atom, but has shown its 
power to predict new relations which can be verified by experiment. 
For example, the theory predicted the relations wliich must subsist 
between the Eydberg constants of the arc and spark spectra, and generally 


between all the successive optical spectra of an element, a prediction so 
strikingly confirmed by Paschen's work on the spectrum of doubly 
ionized aluminium and Fowler's work on the spectnmi of trebly ionized 
silicon. Finally, it predicted with such great confidence the chemical 
properties of the missing element, number 72, that it gave the necessary 
incentive for its recent discoveiy. 

While the progress of our knowledge of the outer structure of atoms 
has been much more rapid than could have been anticipated, we clearly 
see that only a beginning has been made on this great problem, and 
that an enormous amount of work is still required before we can hope 
to form anything like a complete pictui'e even of the outer structure 
of the atom. We may be confident that the main features of the struc- 
ture are clear, but in a problem of such great complexity progress in 
detail must of necessity be difficult and slow. 

We have not so far referred to the very difficult question of the 
explanation on this theory of the chemical combination of atoms. In 
fact, as yet the theory has hardly concerned itself with molecular struc- 
ture. On the chemical side, however, certain advances have already 
been made, notably by G. N. Lewis, Kossel, and Langmuir, in the 
interpretation of the chemical evidence by the idea of shared electrons, 
wliich play a part in the electronic structure of two combined atoms. 
There can be little doubt that the next decade will see an intensified 
attack by physicists and chemists on this very important but undoubtedly 
very complicated question. 

Before leaving this subject, it may be of interest to refer to certain 
points in Bohr's theory of a more philosophical nature. It is seen that 
the orbits and energies of the various groups of electrons can be specified 
by certain quantum numbers, and the nature of the radiation associated 
with a change of orbit can be defined. But at the same time we cannot 
explain why these orbits are alone permissible under normal conditions, 
or understand the mechanism by which radiation is emitted. It may 
be quite possible to formulate accurately the energy relation of the 
electrons in the atom on a simple theory, and to explain in considerable 
detail all the properties of an atom, without any clear understanding of 
the underlying processes which lead to these results. It is natural to 
hope that with advance of knowledge we may be able to grasp the details 
of the process which leads to the emission of radiation, and to understand 
why the orbits of the electrons in the atom are defined by the quantum 
relations. Some, however, are inclined to take the view that in the 
present state of knowledge it may be quite impossible in the nature of 
things to form that detailed picture in space and time of successive 
events that we have been accustomed to consider as so important a part 
of a complete theory. The atom is naturally the most fundamental 
structure presented to us. Its properties must explain the properties 

1923 D 


of all more complicated stractures, including matter in bulk, but we 
may not, therefore, be justified in expecting that its processes can be 
explained in terms of concepts derived entirely from a study of molar 
properties. The atomic processes involved may be so fundamental that 
a complete understanding may be denied us. It is early yet to be 
pessimistic on this question, for we may hope that our difficulties may 
any day be resolved by further discovei'ies. 

We must now turn our attention to that new and comparatively 
unexplored territory, the nucleus of the atom. In a discussion on the 
structure of the atom ten years ago, in answer to a question on the 
structure of the nucleus, I was rash enough to say that it was a problem 
that might well be left to the next generation, for at that time there 
seemed to be few obvious methods of attack to throw light on its con- 
stitution. While much more progress has been made than appeared 
possible at that time, the problem of the structure of the nucleus is 
inherently more difficult than the allied problem already considered of 
the structure of the outer atom, where we have a wealth of information 
obtained from the study of light and X-ray spectra and from the chemical 
properties to test the accuracy of our theories. 

In the case of the nucleus, we know its resultant charge, fixed by 
Moseley's law, and its mass, which is very nearly equal to the mass of 
the whole atom, since the mass of the planetary electrons is relatively 
very small and may for most purposes be neglected. We know that 
the nucleus is of size minute compax'ed with that of the whole atom, 
and can with some confidence set a maximum limit to its size. The 
study of radioactive bodies has provided us with very valuable informa- 
tion on the structure of the nucleus, for we know that the a and ^ 
particles must be expelled from it, and there is strong evidence that the 
very penetrating y rays represent modes of vibration of the electrons 
contained in its structure. In the long series of transformations which 
occur in the uranium atom, eight a particles are emitted and six elec- 
trons, and it seems clear that the nucleus of a heavy atom is built up, 
in part at least, of helium nuclei and electrons. It is natural to sup- 
pose that many of the ordinary stable atoms are constituted in a similar 
way. It is a matter of remark that no indication has been obtained 
that the lightest nucleus, viz. that of hydrogen, is liberated in these 
transformations, where the processes occurring are of so fundamental a 
character. At the same time, it is evident that the hydrogen nucleus 
must be a unit in the structure of some atoms, and this has been 
confirmed by direct experiment. Dr. Chadwick and I have observed 
that swift hydrogen nuclei are released from the elements boron, 
nitrogen, fluorine, sodium, aluminium, and phosphorus when they are 
bombarded by swift a particles, and there is little room for doubt that 
these hydrogen nuclei form an essential part of the nuclear structure. 


Tlie speed of ejection of these nuclei depends on the velocity of the 
a particle and on the element bombarded. It is of interest to note that 
the hydrogen nuclei ai'e liberated in all directions, but the speed in the 
backward direction is always somewhat less than in the direction of 
the a particle. Such a result receives a simple explanation if we sup- 
pose that the hydrogen nuclei ai'e not built into the main nucleus but 
exist as satellites probably in motion round a central core. There can 
be no doubt that bombardment by a particles has effected a veritable 
disintegration of the nuclei of this group of elements. It is significant 
that the liberation of hydrogen nuclei occurs only in elements of odd 
atomic number, viz. 5, 7, 9, 11, 13, 15, the elements of even number 
appearing quite unaffected. For a collision of an a particle to be effec- 
tive, it must either pass close to the nucleus or actually penetrate its 
structure. The chance of this is excessively small on account of the 
minute size of the nucleus. For example, although each individual 
a particle will pass through the outer structure of more than 100,000 
atoms of aluminium in its path, it is only about one a particle in a 
million that gets close enough to the nucleus to effect the liberation of 
its hydrogen satellite. 

This artificial disintegration of elements by a particles takes place 
only on a minute scale, and its observation has only been possible by 
the counting of individual swift hydrogen nuclei by the scintillations 
they produce in zinc sulphide. 

These experiments suggest that the hydrogen nucleus or proton must 
be one of the fundamental units which build up a nucleus, and it seems 
highly probable that the helium nucleus is a secondary building unit 
composed of the very close union of four protons and two electrons. 
The view that the nuclei of all atoms are ultimately built up of protons 
of mass nearly one and of electrons has been strongly supported and 
extended by the study of isotopes. It was early observed that some of 
the radioactive elements which showed distinct radioactive properties 
were chemically so alike that it was impossible to effect their separation 
when mixed together. Similar elements of this kind were called 
' isotopes ' by Soddy, since they appeared to occupy the same place in 
the periodic table. For example, a number of radioactive elements in 
the uranium and thorium series have been found to have physical and 
chemical properties identical with those of ordinary lead, but yet to 
have atomic weights differing from ordinary lead, and also distinctive 
radioactive properties. The nuclear theory of the atom offers at once a 
simple interpretation of the relation between isotopic elements. Since 
the chemical properties of an element are controlled by its nuclear charge 
and little influenced by its mass, isotopes must correspond to atoms 
with the same nuclear charge but of different nuclear mass. Such a 
view also offers a simple explanation why the radiocative isotopes show 

D 2 


different radioactive properties, for it is to be anticipated that the stabiUty 
of a nucleus will be much influenced by its mass and arrangement. 

Our knowledge of isotopes has been widely extended in the last few 
years by Aston, who has devised an accurate direct method for showing 
the presence of isotopes in the ordinary elements. He has found that 
some of the elements are ' pure ' — i.e. consist of atoms of identical mass — 
while others contain a mixture of two or more isotopes. In the case of 
the isotopic elements, the atomic mass, as ordinarily measured by the 
chemist, is a mean value depending on the atomic masses of the indi- 
vidual isotopes and their relative abundance. These investigations have 
not only shown clearly that the number of distinct species of atoms is 
much greater than was supposed, but have brought out a relation between 
the elements of great interest and importance. The atomic masses of 
the isotopes of most of the, elements examined have been found, to an 
accuracy of about one in a thousand, to be whole numbers in terms of 
oxygen, 16. This indicates that the nuclei are ultimately built up of 
protons of mass very nearly one and of electrons. It is natural to 
suppose that this building unit is the hydrogen nucleus, but that its 
average mass in the complex nucleus is somewhat less than its mass in 
the free state owing to the close packing of the charged units in the 
nuclear structure. We have already seen that the helium nucleus of 
mass 4 is probably a secondary unit of great importance in the building 
up of many atoms, and it may be that other simple combinations of 
protons and electrons of mass 2 and 3 occur in the nucleus, but these 
have not been observed in the free state. 

While the mass of the majority of the isotopes are nearly whole 
numbers, certain cases have been observed by Aston where this rule is 
slightly departed from. Such variations in mass may ultimately prove 
of great importance in throwing light on the arrangement and closeness 
of packing of the protons and electrons, and for this reason it is to be 
hoped that it may soon prove possible to compare atomic masses of 
the elements with much gi'eater precision even than at present. 

While we may be confident that the proton and the electron are the 
ultimate units which take part in the building up of all nuclei, and can 
deduce with some certainty the number of protons and electrons in the 
nuclei of all atoms, we have little, if any, information on the distribution 
of these units in the atom or on the nature of the forces that hold them 
in equilibrium. While it is known that the law of the inverse square 
holds for the electrical forces some distance from the nucleus, it seems 
certain that this law breaks down inside the nucleus. A detailed study 
of the collisions between a particles and hydrogen atoms, where the 
nuclei approach very close to each other, shows that the forces between 
nuclei increase ultimately much more rapidly than is to be expected 
Ivora the law of the inverse squai-e, and it may be that new and unex- 


pected forces may come into importance at the very small distances 
separating the protons and electrons in rhe nucleus. Until we gain more 
information on the nature and law of variation of the forces inside the 
nucleus, further progress on the detailed structure of the nucleus may 
be difficult. At the same time, there are still a number of hopeful 
directions in which an attack may be made on tliis most difficult of 
problems. A detailed study of the y rays from radioactive bodies may 
be expected to yield information as to the motion of tlie electrons inside 
the nucleus, and it may be, as Ellis has suggested, that quantum 
laws are operative inside as well as outside the nucleus. From a 
study of the relative proportions of the elements in the earth's crust, 
Harkins has shown that elements of even atomic number are much 
more abundant than elements of odd number, suggesting a marked 
difference of stability in these two classes of elements. It seems 
probahle that any process of stellar evolution must be intimately 
connected with the building up of complex nuclei from simpler opes, 
and its study may thus be expected to throw much light on the evolution 
of the elements. 

The nucleus of a heavy atom is undoubtedly a veiy complicated 
system, and in a sense a world of its own, little, if at all, influenced by 
the ordinary physical and chemical agencies at our command. "When 
we consider the mass of a nucleus compared with its volume it seems 
certain that its density is many billions of times that of our heaviest 
element. Yet, if we could form a magnified, picture of the nucleus, 
we should expect that it would show a discontinuous structure, occupied 
but not filled by the minute building units, the protons and electrons, 
in ceaseless rapid motion controlled by their mutual forces. 

Before leaving this subject it is desirable to say a few words on 
the important question of the energy relations involved in the formation 
and disintegration of atomic nuclei, first opened up by the study of 
radioactivity. For example, it is well known that the total evolution 
of energy during the complete disintegration of one gramme of radium 
is many millions of times greater than in the complete combustion of 
an equal weight of coal. It is known that this energy is initially 
mositly emitted in the kinetic form of swift a and p particles, and the 
energy of motion of these bodies is ultimately converted into heat 
when they are stopped by matter. Since it is believed that the radio- 
active elements were analogous in structure to the ordinary inactive 
elements the idea naturally arose that the atoms of all the elements 
contained a similar concentration of energj', which would be available 
for use if only some simple method could be discovered of promoting 
and controlling their disintegration. This possibility of obtaining new 
and cheap sources of energy for practical purposes was naturally an 
alluring prospect to the lay and scientific man ahke. It is quite true 


that, if W6 were able to hasten the radioactive processes in uranium and 
thorium so that the whole cycle of their disintegration could be confined 
to a few days instead of being spread over thousands of millions of 
years, these elements would provide very convenient sources of energy 
on a sufficient scale to be of considerable practical importance. Un- 
fortunately, although many experiments have been tried, there is no 
evidence that the rate of disintegration of these elements can be altered 
in the slightest degree by the most powerful laboratory agencies. With 
increase in our knowledge of atomic structure there has been a gradual 
change of our point of view on this important question, and there is 
by no means the same certainty to-day as a decade ago that the atoms 
of an element contain hidden stores of energy. It may be worth while 
to spend a few minutes in discussing the reason for this change in out- 
look. This can best be illustrated by considermg an interesting analogy 
between the transformation of a radioactive nucleus and the changes in 
the electron arrangement of an ordinary atom. It is now well known 
that it is possible by means of electron bombardment or by appropriate 
radiation to excite an atom in such a way that one of its superficial 
electrons is displaced, from its ordinary stable position to another tem- 
porarily stable position further removed from the nucleus. This 
electron in course of time falls back into its old position, and its potential 
energy is converted into radiation in the process. There is some reason 
for believing that the electron has a definite average life in the displaced 
position, and that the chance of its return to its original position is 
governed by the laws of probability. In some respects an ' excited ' 
atom of this kind is thus analogous to a radioactive atom, but of course 
the energy released in the disintegration of a nucleus is of an entirely 
different order of magnitu<le from the energy released by return of the 
electron in the excited atom. It may be that the elements, uranium 
and thorium, represent the sole survivals in the earth to-day of types 
of elements that were common in the long distant ages, when the 
atoms now composing the earth were in course of formation. A frac- 
tion of the atoms of uranium and thorium formed at that time has 
survived over the long interval on account of their very slow rate of 
transformation. It is thus possible to regard these atoms as having 
not yeit completed the cycle of changes which the ordinary atoms have 
long since passed through, and that the atoms are still in the ' excited. ' 
state where the nuclear units have not yet arranged themselves in posi- 
tions of ultimate equilibrium, but still have a surplus of energy which 
can only be released in the form of the characteristic radiation from 
active matter. On such a view, the presence of a store of energy ready 
for release is not a property of all atoms, but only of a special class 
of atoms like the radioactive atoms which have not yet reached the 
final state for equilibrium. 


It may be urged that tlie ai'tificial disintegration of certain elements 
by bombardment with swift a particles gives definite evidence of a 
store of energy in some of the ordinary elements, for it is known that 
a few of the hydrogeii nuclei, released from aluminium for example, 
are expelled with such swiftness that the particle has a greater indi- 
vidual energy than the a particle which causes their liberation. Un- 
fortunately, it is very difficult to give a definite answer on this point 
until we know more of the details of this disintegration. 

On the other hand, another method of attack on this question has 
become important dui'ing the last few years, based on the comparison 
of the relative masses of the elements. This new point of view can 
best be illustrated by a comparison of the atomic masses of hydrogen 
and holiuiu. As we have seen, it seems very probable that helium is 
not an ultimate unit in the structure of nuclei, but is a very close com- 
bination of four hydrogen nuclei and two electrons. The mass of the 
helium nucleus, 4.00 in terms of = 16, is considerably less than the 
mass 4.03 of four hydrogen nuclei. On modern views there is believed 
to be a very close connection between mass and energy, and this loss 
in mass in the synthesis of the helium nucleus from hydrogen nuclei 
indicates that a large amount of energy in the form of radiation has 
been released in the building of thei helium nucleus from its components. 
It is easy to calculate from this loss of mass that the energy set free 
in forming one gramme of helium is large even compared with that 
liberated in the total disintegration of one gi-amme of radium. For 
example, calculation shows that the energy released in the formation 
of one pound of helium gas is equivalent to the energy emitted in the 
complete combustion of about eight thousand tons of pure carbon. 
It has been suggested by Eddington and Perrin that it is mainly to 
this source of energy that we must look to maintain the heat emission 
of the sun and hot stars over long periods of time. Calculations of 
the loss of heat from the sun show that this synthesis of helium 
need only take place slowly in order to maintain the present rate of 
radiation for periods of the order of one thousand million years. It 
must be acknowledged that these arguments are somewhat speculative 
in character, for no certain experimental evidence has yet been obtained 
that helium can be formed from hydrogen. 

The evidence of the slow rate of stellar evolution, however, certainly 
indicates that the synthesis of helium, and perhaps other elements of 
higher atomic weight, may take place slowly in the interior of hot stars. 
While in the electric discharge through hydrogen at low pressure we 
can easily reproduce the conditions of the interior of the hottest star 
as far as regards the energy of motion of the electrons and hydrogen 
nuclei, we cannot hope to' reproduce that enormous density of radiation 
which must exist in the interior of a giant star. For this and other 


reasons it may be very difficult, or even impossible, to produce helium 
from hydrogen under laboratory conditions. 

If this view of the great heat emission in the formation of helium 
be correct, it is clear that the helium nucleus is the most stable of all 
nuclei, for an amount of energy corresponding to three or four a par- 
ticles vs'ould be required to disrupt it into its components. In addition, 
since the mass of the proton in nuclei is nearly 1.000 instead of its mass 
1.0072 in the free state, it follows that much more energy must be put 
into the atom than will be liberated by its disintegration into its ultimate 
units. At the same time, if we consider an atom of oxygen, which 
may be supposed to be built up of four helium nuclei as secondary units, 
the change of mass, if any, in its synthesis from, already foi'med helium 
nuclei is so small that we cannot yet be certain whether there will be 
a gain or loss of energy by its disintegration into helium nuclei, but in 
any case we are certain that the magnitude of the energy will be much 
less than for the synthesis of helium from hydrogen. Our information 
on this subject of energy changes in the formation or disintegration 
of atoms in general is as yet too uncertain and speculative to give any 
decided opinion on future possibilities in this direction, but I have 
endeavom-ed to outline some of the main arguments which should be 
taken into account. 

I must now bring to an end my survey, I am afraid all too brief 
and inadequate, of this great period of advance in physical science. 
In th.e short time at my disposal it has been impossible for me, even 
if I had. the knowledge, to refer to the great advances made during 
the period under consideration in all branches of pure and applied 
science. I am well aware that in some departments the progress made 
may justly compare with that of my own subject. In these great 
additions to our knowledge of the structure of matter every civilised 
nation has taken an active part, but we may be justly proud that this 
country has made many fundamental contributions. With this 
country I must properly include our Dominions overseas, for they have 
not been behindhand in their contributions to this new knowledge. 
It is, I am sure, a matter of pride to this countiy that the scientific 
men of our Dominions have been responsible for some of the most 
fundamental discoveries of this epoch, particularly in radioactivity. 

This tide of advance was continuous from 1896, but there was an 
inevitable slackening during the War. It is a matter of good omen 
that, in the last few years, the old rate of progress has not only been 
maintained, but even intensified, and there appears to be no obvious sign 
that this period of great advances has come to an end. There has never 
been a time when the enthusiasm of the scientific workers was greater, 
or when there was a more hopeful feeling that great advances were 
imminent. This feeling is no doubt in part due to the great improve- 


ment during this epoch of the technical methods of attack, for problems 
that at one time seemed unattackable are now seen to be likely to fall 
before the new methods. In the main, the epoch under consideration 
has been an age of experiment, where the experimenter has been the 
pioneer in the attack on new problems. At the same time, it has 
been also an age of bold ideas in theory, as the Quantum Theory and 
the Theory of Relativity so well illustrate. 

I feel it is a great privilege to have witnessed this period, which 
may almost be termed the Renaissance of Physics. It has been of 
extraordinary intellectual interest to watch the gradual unfolding of 
new ideas and the ever-changing methods of attack on difficult problems. 
It has been of great interest, too, to note the comparative simplicity 
of the ideas that have ultimately emerged. For example, nO' on© could 
have anticipated that the general relation between the elements would 
prove to be of so simple a character as we now believe it to be. It is 
an illustration of the fact that Natm-e appears to work in a simple way, 
and that the more fundamental the problem often simpler are the con- 
ceptions needed for its explanation. The rapidity and certitude of the 
advance in this epoch have largely depended on the fact that it has been 
possible to devise experiments so that few variables were involved. For 
example, the study of the structure of the atom has been much facili- 
tated by thei possibility of examining the effects due to a single atom 
of matter, or, as in radioactivity or X-rays, of studying processes going 
on in the individual atom which were quite uninfluenced by external 

In watching the rapidity of this tide of advance in physics I have 
become more and more impressed, by the power of the scientific method 
of extending our knowledge of Nature. Experiment, directed by the 
disciplined imagination either of an individual, or still better, of a 
group of individuals of varied mental outlook, is able to achieve results 
which far transcend the imagination alone of the greatest natural philo- 
sopher. Experiment without imagination, or imagination without 
recourse to experiment, can accomplish little, but, for effective progress, 
a happy blend of these two powers is necessary. The unknown appears 
as a dense mist before the eyes of men. In penetrating this obscurity 
we cannot invoke the aid of supermen, but must depend on the com- 
bined efforts of a number of adequately trained ordinary men of scientific 
imagination. Each in his own special field of inquiry is enabled by 
the scientific method to penetrate a short distance, and his work reacts 
upon and influences the whole body of other workers. From time to 
time there arises an illuminating conception, based on accumulated 
knowledge, which lights up a large region and shows the connection 
between these individual efforts, so that a general advance follows. The 
attack begins anew on a wider front, and often with improved technical 


weapons. The conception whicli led to this advance often appears 
simple and obvious when once it has been put forward. This is a 
common experience, and the scientific man often feels a sense of dis- 
appointment that he himself had not foreseen a development which 
ultimately seems so clear and inevitable. 

The intellectual interest due to the rapid growth of science to-day 
cannot fail to act as a stimulus to young men to join in scientific investi- 
gation. In every branch of science there are numerous problems of 
fundamental interest and importance which await solution. We may 
confidently predict an accelerated rate of progress of scientific discoveiy, 
beneficial to mankind certainly in a material but possibly even more so in 
an intellectual sense. In order to obtain the best results certain condi- 
tions must, however, be fulfilled. It is necessary that our universities 
and other specific institutions should be liberally supported, so as not 
only to be in a position to train adequately young investigators of 
promise, but also to serve themselves as active centres of research. At 
the same time there must be a reasonable competence for those who 
have shown a capacity for original investigation. Not least, peace 
throughout the civilised world is as important for rapid scientific 
development as for general commercial prosperity. Indeed, science is 
truly international, and for progress in many directions the co-operation 
of nations is as essential as the co-operation of individuals. Science, 
no less than industry, desires a stability not yet achieved in world 

There is an eiTOr far too prevalent to-day that science progi^esses 
by the demolition of former well-established theories. Such is very 
rarely the case. For example, it is often stated that Einstein's general 
theory of relativity has overthrown the work of Newton on gravitation. 
No statement could be farther from the truth. Their works, in fact, 
are hardly comparable, for they deal with different fields of thought. 
So far as the work of Einstein is relevant to that of Newton, it is simply 
a generalisation and broadening of its basis; in fact, a typical case of 
mathematical and physical development. In general, a great principle 
is not discarded but so modified that it rests on a broader and more 
stable basis. 

It is clear that the splendid period of scientific activity which we 
have reviewed to-night owes much of its success and intellectual appeal 
to the labours of those great men in the past, who wisely laid the sure 
foundations on which the scientific worker builds to-day, or to quote 
from the words inscribed in the dome of the National Gallery, ' The 
works of those who have stood the test of ages have a claim to that 
respect and veneration to which no modern can pretend. ' 





Professor J. C. McLENNAN, F.R.S., 



The problem of the origin of spectra is intimately bound up with that 
of the constitution and structure of atoms. Models of atoms of different 
types have been proposed from time to time, and these all have served, 
in a measure, to explain some at least of the chemical, optical, and 
mechanical properties of matter. The conception, however, that in- 
spires and co-ordinates the whole of modern atomic physics in so far as 
radiation is concerned is the remarkably simple atomic model of Euther- 
ford and Bohr. 

According to this model the neutral atom consists of a central 
positively charged nucleus with dimensions of the same order as those 
of the electron itself (10"^'' cm.),' and surrounded by a system of elec- 
trons whose aggregate negative charge is equal in amount to that of the 
positive charge carried by the nucleus. The atomic immber — i.e. the 
number that indicates the places occupied by the element under con- 
sideration in the Periodic Tablei — gives for a neutral atom the number 
of electrons surrounding the nucleus, and is at the same time a measure 
of the positive electric charge carried by the latter. 

Eutherford, by his brilliant experiments on the scattering of alpha 
rays, has shown that the electric field due to the charge on the nucleus 
is central, and that it follows the inverse square law practically up 
to the effective boundary of the nucleus. Close to the nucleus the 
electric field is very intense, and therefore sufficient to produce those 
remarkably interesting deflections of alpha rays that are being studied 
so widely and so successfully at the present time by the use of 
C. T. E. Wilson's beautiful method of photograpliing cloud tracks. 

As regards the problem of the origin of spectra, but little progress 
was made so long as one limited oneself to the use of classical mechanics. 
"With the introduction of the theory of quanta into the mechanics of 
the atom it became possible to analyse in detail the structure of atoms 
and to make quantitative comparisons between the properties of matter 
and those deducible from the different atomic models. In the develop- 
ments that have taken place in this direction Niels Bohr has been the 
leader ; but very notable and important contributions to the theory have 

1 Neuberger, An7i. cler Phys., Bd. 70, Heft 2, p. 139, 1923. 


been made by Wilson, Sommerfeld, Ehrenfest, Kramers, Lande, and 

Bohr in his theory supposes that each electron in an atom describes 
a central or quasi-central orbit under the attraction of the nucleus 
in combination with the fields ol the other extra-nuclear electrons 
present in the atom. He imposes, moreover, upon these motions of 
the electrons in atoms something in the nature of a quantum censorship. 

As a generalised postulate it is laid down that from the continuous 
manifold of all conceivable states of motion that may be ascribed to 
an atomic system there exists a definable number of stationary states 
that possess a peculiar stability, and that arc of such a kind that every 
peiTnanent change of motion within the system must involve a complete 
transition from one stationary state to another. 

It is postulated further that while no radiation is emitted by the 
atomic system when it is in one of its stationary states, the process of 
transition from one stationary state to another is accompanied by the 
emission of monochromatic radiation with a frequency given by the 

V /i = Ei-E.2, 

where /i is Planck's constant and Ei and Eo are the values of the energy 
of the atom in the initial and final stationary states between which the 
transition takes place. Conversely, it is to be understood that the absorp- 
tion by the atomic system, of radiation with the frequency v given above 
results in a transition back from the final stationary state to the initial 
one. These postulates, it will be seen, form the basis of an interpreta- 
tion of the laws of series spectra, for the most general of these — the 
combination principle of Eitz — asserts that the frequency v of each of 
the lines in the spectrum of a selected element can be represented by 
the formula 

v = Ti-T.,, 

where Tj and T, are two spectral terms taken from a number that are 
characteristic of the element in question. 

On Bohr's theory" the intei^pretation of the law of Eitz would be 
that the spectrum of the element referred to must originate in transi- 
tions between statioinary states for which the atomic energy values are 
obtained simply by multiplying by Planck's constant the values of 
those spectral terms of which Tj and To are types. 

This, it is evident, indicates the feasibility of establishing a connec- 
tion between the series spectrum of an element and the constitution and 
structure of its atoms. From the spectrum of the element the series 
spectral terms can be selected and evaluated, and these values when 
multiplied by Planck's constant will give the various energy levels 
within and associated with the atom of the element. As the number 
of electrons within the said atom is given by the atomic number of the 
element, the problem becomes one of assigning toi these constituent 
electrons orbits of a size and form that will provide the values of the 
energy levels determined by the spectral series tenns. 

= Bohr, Nature. Supplement, July 7, 1923. 


The reciprocal nature of this relationship between the series spectrum 
of an element and its atomic structure will be evident. In a case where 
the series spectrum of an element is not known a knowledge of it 
may be obtained by deteiTnining the energy levels in the atoms of this 
element independently. This can be done after the manner of Moseley 
and Franck and Hertz by causing atoms to emit limited portions of its 
spectrum under bombardment by electrons of selected speeds. 

In illustration of the foregoing it may be pointed out that empirically 
determined spectral relationships obtained in a study of the radiation 
emitted by such elements as hydi^ogen and helium have enabled us to 
determine with some precision the constitution, structure, and stationary 
states of the atoms of these comparatively simple elements. Moi-eover, 
explicit and definite knowledge of the temporary modifications that 
can be impressed upon the structure of the normal atoms of these ele- 
ments has been acquired through spectral relationships estabhshed by 
observations on the fine structure of these spectral lines, and by a 
study of the resolutions of these lines obtainable through the application 
of external electric or magnetic fields. 

Stationary States — Qnantom Conditions. 

To illustrate the manner in which stationary states are defined on 
Bohr's theory we may take the simple case of an atom of hydrogen 
which consists of a nucleus with charge +e and an electron with 
charge- e. It is known that the frequencies of the series spectra of this 
element are given, with great accuracy by the generalised Balmer 

v = k(1,„-U . . . . (1) 

where n" and n' are two integers and K is the well-known Rydberg 
constant. From this formula we see that all the spectral terms are of 
the form K/»i^, and it follows at once that the energy coiTesponding to 
the various stationary states of the atom of hydrogen must be given by 
Khin with n having all possible integral values. 

Now it can be shown that when an electron describes an elliptic 
orbit about the nucleus of a hydrogen atom the major axis of the orbit 
described is inversely proportional to w the work required completely 
to remove the electron from the field of the nucleus. The major axis 

2 2 2 

is, in fact, given by 2a = - • If, therefore, we take 2fl = ^iiL we have 
w K /; 

determined for the hydrogen atom a set of clearly defined stationary 
states consisting of a series of elliptical orbits for which the major 
axis takes on discrete values proportional to the squares of the whole 
numbers. Transitions from one to another of such a set of stationary 
states will suffice on Bohr's theory to account for all the lines in the 
series spectrum of atomic hydrogen. 

In the early development of Bohr's theory it was noted that for 

2 2 

each value of n in the equation 2a = -— it was possible to have a 




number of orbits with the same major axis but with different eccen- 
tricities, while all were characterised by the same energy value. For 
each value of n the number of such orbits was given by the number of 
ways in which n could be made equal to the sum of two integers, 
including zero. For example, if n were equal to 1 only a single orbit 
could exist. If n were equal to 2, then since 2 = 2 + and 2 = 1 + 1 we 
could have two orbits. If n were equal to 3, we see again, since 3 = 3+0 
or 3 = 2+1 or 3 = 1+2, that we could have three orbits, &c. For 
each value of n there could exist a definite number of equivalent orbits. 
If we put n = n,i+n2 it can be readily shown that the eccentricities of 
these equivalent orbits are given by 

If 2& be taken to represent the minor axis of the different equivalent 
elliptical orbits, it follows that the ratio of the semi-axes is given by 

' = ? ..... (3) 

Fig. 1.— H Orbits. 

Illustrations of such equivalent orbits for the hydrogen atom with differ- 
ing values of n are shown in Fig I. On this view the Lymans spectral series 

v = k(i — ^) originates in transitions to the n = l orbit, the Balmer 
series v = K( 4, — ^) i"^ transitions to either of the n = 2 orbits, and the 

Paschen series v = K'( -s~ — » I in transitions to one or other of the orbits 

\3 mJ 
of the 11 = 3 group. 


Though the single principal quantum number suffices to define the 
energy levels for the atom of hydrogen, the introduction of the subordin- 
ate quantum numbers »i and n. extended the basis of the theory, and, 
as is well known, led to developments by Sommerfeld of profound 
importance in dealing with the question of the fine structure of spectral 

Bohr's theory of the origin of spectra as it exists to-day is 
approached from a somewhat different angle from that given above. 
Through extensions initiated independently by Wilson and by Sommer- 
feld the quantising conditions are made to apply to momentum rather 
than to energy, and in dealing with the problem of the stationary states 
of a system such as that of the hydrogen atom the angular and radial 
momenta of the electron in its orbit are both quantised. 

In more complicated systems the quantisation principle is extended 
to all degrees of freedom that are characteristic of the motion. The 
analytical conditions laid down are 

Ii = nji, Jo = nji Ijc^'nji where itiii^ », are quantum 

integers independent of each other, and where I^. = \j>cd^x integrated 
over a complete cycle with reference to the generalised co-oi'dinates 
p, and 9r ^^'^^^ describe the states and motions of the constituents of 
the system. 

If we confine ourselves to the use of the two conditions Ij = nji 
and ln = n.Ji, representing respectively the quantisation of the 
angular and radial momenta of a system consisting of a nucleus 
of mass M and charge Ni? and an electron of mass vi, we' find that the 
frequencies of the radiation that can be emitted are given by 

^_ 2Tc^NVMwf 1 1 ) , n_ r, . , , , , , 
7:^/T>T I — T I -7^2 ~ -72 1 where n —ih + n.^ and n = 7i i + n -2. 

This formula possesses the advantage that it enables us to evaluate 
the Eydberg constant K for the spectral terms of the hydrogen spectrum, 
or of any system consisting of a single nucleus and one electron. It 
will be recalled in this connection that through the use of this formula 
Fowler was able to evaluate the mass of an electron from experimentally 
determined differences in the values of the Eydberg constant in the 
spectral series of hydrogen and the atom ion of helivmi. 

Quantum Numbers and their Significance. 

From the illustrations that have been given in the previous section, 
it will be seen that for a given atomic system the quantum numbers 
define the stationary states, and the energy values and moments of 
momentum of the system in these states. ]\Ioreover, they define the 
kinematical character of the electron obits in the atomic edifice, and, 
on account of the simple relation connecting the values of spectral 
terms in the series spectrum of an element with the energy of the 
atom of this element in its various stationary states, they define these 
spectral terms and enable us to calculate their values. 

In the simplest possible treatment of a system such as that of the 
atom of hydrogen one quantum number n suffices to define the various 
factors just mentioned. In the theory of the fine structure of the 


spectral lines of hydrogen two quantum numbers n and k were required. 
In the case of a series spectrum of single lines two quantum numbers 
n and k are requisite to define its terms and the orbits corresponding 
to them. For a series spectrum consisting of doublets, triplets or 
multiplets, three quantum numbers are required, n, k and ;', to define 
its spectral terms and the con-esponding electronic orbits. In the case 
of the resolution of a spectral line by the application of an external 
magnetic field a fourth quantum number m is necessary in order to 
distinguish the stationary states and to evaluate the spectral terms 
corresponding to the Zeeman components. 

Taking the case of the stationary states associated with the outer 
electrons in an atom for illustration the kinematic significance of these 
quantum numbers is as follows : n characterises the orbit forms of these 
outer electrons, li n = k the orbit is circular, but if n > fc it is elliptical, 
having the greater eccentricity the greater n is compared with k. The 
quantum number k, on the other hand, connotes kinematically a rotation 
of the perihelion of the elliptical orbit confined in its own plane, and 
on account of this turning of the perihelion the orbit takes on the form 
of a rosette (as shown in Fig. 5). The normal to the orbital plane 
about which the perihelion is progressing is called the k axis. The 
quantum number j indicates the total moment of momentum of the 
atomic state at a given instant, and the axis of this moment is called 
the j axis. It is in general different from the k axis, and the orbital 
plane performs a turning or precession about the ; axis determined by 
the value of j the moment of momentum of the atom. If an atom 
endowed with the motions described above be situated in an external 
magnetic field, the whole system thus in motion will carry out a rotation, 
i.e. a Larmor precession about the direction of the lines of force of this 
magnetic field. The axis for this rotation is called the m axis, and m 
is a measure of the moment of momentum about it. 

In spectroscopy it has become customary, in order to distinguish 
series of different kinds, to designate singlet systems by the use of 
capital letters, doublet series by Greek letters, and triplet series by 
small letters. Thus : 

'P S D F = singlet systems. 
7r (T S 9 = doublet systems. 
p s d f = triplet systems. 
In the same way it has become customary to use the same letters 
to designate the spectral terms whose differences determine the fre- 
quencies of the lines in a series. As example we may cite IS, 2S, &c., 
iTT, 2TU, &c. ; Id, 2d, &c. ; and If, 2/, &g. 

Practically all efforts of spectroscopists towards arranging lines into 
series have had for their goal, even before the arrival of the quantum 
theory, in an unconscious way the establishment of the quantum 
numbers that define the various types of spectral terms indicated 
above. As a result of the progress that has been made in the last 
year or two, it is now generally agreed that the principal quantum 
number n determines the current number of the series term. For 

' Fowler, 'Report on Series in Line Spectra.' 


example, the IS term is defined by n = l, the 2P term by n = 2, the 3d 
term by n = 3, and the 4P term by 7i=4, &c. The azimuthal quantum 
number k indicates the type to which a term belongs. For fe = l an 
s, (J or S term is signified, for k = 2 a p, iz ov T term, for k = 3 a d,S D 
term, and for fc = 4 an/, 9 or F term. A 3, term, for example, would 
signify a 3s, a 3 ct, or a 3S term, and a 4^ term would be one which 
in spectroscopy is usually designated as a 4^0, 4^ or 4P term. We 
have then in the symbol n^ a means of defining a particular spectral 
term as well as a particular electronic orbit. 

Principles of Selection— The Correspondence Principle. 

In the early development of Bohr's theory it was found that the 
censorship imposed by the quantum conditions referred to above were 
not sufficiently drastic to account completely either for the observed 
complexity of the fine structure of spectral lines originating in the 
variation of the mass of an electron with its velocity or for the 
observed complexity and state of polarisation of the components of 
spectral lines that had their origin in the application of an external 
electric or magnetic field. 

To make up for this deficiency arbitrary Principles of Selection, 
involving such factors as intensity and polarisation, were brought 
forward by Eubinowicz and by Sommerfeld, thaL found immediate and 
remarkable verifications in the relativity fine structure of the Balmer 
lines, in the Stark effect, in the Zeeman effect, and in the spectra of 
rotation, i.e. the band spectra of Deslandres. 

Although these principles of selection furnished rul6s that have 
served as useful guides in unravelling the intricacies of various types 
of spectral resolution, it has all along been recognised by the proposers, 
as well as by others, that the principles as formulated rested upon a 
dynamical basis that was rather limited and scarcely adequate. 

The whole matter, however, was given an entirely new orientation 
and an enhanced significance by Bohr's enunciation of the Correspond- 
ence Principle. 

To elucidate this principle we may revert for a moment to the 
properties of the stationary orbits of the atom of hydrogen. It can 
be easily shown that the frequency with which the electron revolves 
in the nth orbit is given by 


CO ^^ — — 1 

(vi + MWh" 

and the fi-equency of the light emitted when a transition occurs of the 
electron from the nth to n'th orbit is given by 


7;;. + M h' 
From these two relations it follows that 



V 12 2 I I X 


If now n and n' be taken to be large integers and not very different 
from eacli other we have 

V = An . (0 numerically. 

As An must be an integer it follows that the fi-equencies of the 
light that can be emitted by the system under the conditions laid down 
are those of the harmonics of the frequency of the electron's orbital 

The explicit hypothesis made by Bohr in his Correspondence 
Principle is that what has been shown above to be true necessarily for 
very great orbital periods is also sensibly true for finite ones as well. 
To put the matter in another way — if the orbit described by an electron 
were carried out under a law of action proportional to the distance, the 
development of the law of motion in a Fourier series would permit 
the use of a fundamental term only. The Correspondence Principle 
would under these .conditions demand that the electron could pass 
spontaneously only from the nth quantum orbit to the n-1 quantum 
orbit immediately below it. If these conditions were to apply in the 
case of the hydrogen atom, for example, it would limit each series 
to a single wave-length, and the Balmer series would be reduced to its 
first component. 

The existence of series made up of numerous terms shows that the 
electronic orbits of an atom cannot be described under a central force 
varying as the direct distance, but points rather in the direction of the 
orbits being ellipses following approximately the Keplerian law. 

In general, if the electronic motion within an atom is periodic and 
not simply of a pure sinusoidal character, Fourier's theory shows 
that the vibration of the electron is represented by a superposition of 
pure periodic motions that are harmonics of a fundamental one. To 
this classical notion there corresponds in the theory of quanta the notion 
of transitions from one stationary state to another with variations in 
the quantum number no longer equal to one only. If the Fourier series 
representing the motion contains effectively an harmonic of rank, 
1, 2, 3 ... or m, for example, the Correspondence Principle postulates 
that the atom can be the seat of transitions corresponding to differences 
in the characterising quantum number of 1, 2, 3 ... or m. If on the 
contrary, the coefficient of a term in the Fourier series under con- 
sideration is small or equal to zero, this signifies that the probability 
of corresponding transitions in the atom becomes small or vanishes. 

The Correspondence Principle co-ordinates every transition process 
between two stationary states with a corresponding harmonic vibration 
component in such a way that the probability of the occurrence of the 
transition is dependent on the amplitude of this particular vibration. 
On the classical theory the intensity and state of polarisation in the 
wave system emitted by an atom as a consequence of the existence of 
some vibration component are determined respectively by the amplitude 
and certain other characteristics of this vibration. On the quantum 
theory the Correspondence Principle asserts that these other special 
characteristics of the vibration refeiTed to detennine in an analogous 
manner the state of polarisation of the radiation emitted during a transi- 


tion for whose occuiTence the amplitude of the vibration measures the 

With the aid of the Correspondence Principle it has been possible 
to develop a complete quantum theory of the normal Zeeman effect for 
the hydrogen lines, and in the case of the Stark effect for these lines, 
v/here the classical theoiy failed to provide an explanation, the quantum 
theory has been so developed that it is now possible, as Kramers has 
shown, to account with the aid of the Correspondence Principle for the 
polarisation of the different components into which the lines are split, 
and for the characteristic intensity distribution exhibited by these 

These and other equally interesting examples leave no doubt of the 
fecundity of the Correspondence Principle and of its far-reaching compass 
and applicability. It has endowed with precision the application of the 
principles of selection of Rubinowicz and Sommorfeld, and has eliminated 
the somewhat arbitrary formalism that has hitherto characterised them. 
Through its use Bohr has been able to show that the Quantum Theory 
can no longer be looked upon as displacing the Classical Theory, but 
must be considered to be a fruitful means of systematically amplifying 
and extending it. 

The Genesis of Atoms. 

One of the more intei-esting of the recent developments of Bohr's 
theory is that which concerns the genesis of atoms of different types. 
Bohr has put forward the view that the fundamental process that must 
apply consists in the successive binding of electrons one after another 
by a nucleus originally naked. 

On this view the electrons as they are successively bound to the 
n ulceus take up certain final and definite orbits that are characteristic 
of the particular atom selected in its iiormal state, and that can to a 
first approximation be specified by two quantum numbers — namely, the 
principal and subordinate quantum numbers n and h. This means that 
the motion of each single electron of the atomic system can be approxi- 
mately described as a plane periodic motion on which is superimposed a 
uniform rotation in the plane of the orbit. 

It is assumed as a general postulate that during the binding of 
an electron by a nucleus the values of the quantum numbers n and k 
that characterise the orbits of the earlier bound electrons remain un- 
changed, and that at most, apart from a few exceptional cases, the 
addition of the later bound electrons merely results in slight alterations 
in the orientations in space of the orbitsi of the electrons already bound. 

In arriving at his conclusions regarding the characteristics of the 
orbits of the bound electron Bohr has, of course, been guided in large 
measm'e by coinsiderations derived from a. study of the arc spectra of 
the different elements, a type of spectrum that it is now generally 
agreed is emitted during the process of binding the last electron in 
the formation of a neutral atom. Data derivable from the characteristics 
of the X-ray spectra of the elements have also been utilised by Bohr 
to check the validity of his conclusions regarding the characteristics 
of the orbits of the electrons bound in neutral atoms. As X-ray lines 
may be considered to give evidence of stages in a process by which an 

I 2 



Electeonic Orbits in Atoms of the Elements. 

V n 



3i Sj Sj 

4i 4, 4, 4, 

5i 5^ 5, 5^ 5^ 

6i 62 6, 64 65 65 



2 He 


3 Li 

4 Be 

10 Ne 





4 4 

11 Na 2 

12 Mg 2 

13 Al 2 

18 A 2 

4 4 
4 4 
4 4 

4 4 

2 1 

4 4 

19 K 2 

20 Ca 2 

21 Sc 2 

22 Ti 2 

29 Cu 2 

30 Zn 2 

31 Ga 2 

36 Kr 1 2 

37 Rb 2 

38 Sr 2 

39 Y 2 

40 Zr 2 

47 Ag 2 

48 Cd j 2 

49 In 2 

54 X 2 

4 4 4 4 
4 4 4 4 
4 4 4 4 1 
4 4 4 4 2 




2 1 

4 4 6 6 6 
4 4 1 6 6 6 
4 4(666 

4 4 6 6 6 

4 4 

4 4 
4 4 1 
4 4 2 

4 4 
4 4 
4 4 
4 4 

6 6 6 
6 6 6 
6 6 6 
6 6 6 




2 1 

4 4 

4 4 
4 4 
4 4 

4 4 

6 6 6 
6 6 6 
6 6 6 

6 6 6 

6 6 6 
6 6 6 
6 6 6 

6 6 6 

55Cs i 2 

56 Ba 1 2 

57 La 2 
58Ce 1 2 
59 Pr 2 

4 4 
4 4 
4 4 
4 4 
4 4 

6 6 6 
6 6 6 
6 6 6 
6 6 6 
6 6 6 

6 6 6 
6 6 6 
6 6 6 
6 6 6 1 
6 6 6 2 

4 4 
4 4 
4 4 1 
4 4 1 
4 4 1 




2 1 

4 4 

71 Lu 

72 Hf 

79 Au 

80 Hg 

81 Ti 

86 Nt 





4 4 
4 4 

4 4 
4 4 
4 4 

4 4 

6 6 6 
6 6 6 

6 6 6 
6 6 6 
6 6 6 

6 6 6 

8 8 8 8 
8 8 8 8 

8 8 8 8 
8 8 8 8 
8 8 8 8 

8 8 8 8 

4 4 1 
4 4 2 

6 6 6 
6 6 6 
6 6 6 

6 6 6 

87 — 

88 Ra 

89 Ac 

90 Th 

118 ? 





4 4 

4 4 
4 4 
4 4 

4 4 

6 6 6 
6 6 6 
6 6 6 
6 6 6 

6 6 6 

8 8 8 8 
8 8 8 8 
8 8 8 8 
8 8 8 8 

8 8 8 8 

6 6 6 
6 6 6 
6 6 6 
6 6 6 

8 8 8 8 

4 4 

4 4 
4 4 1 
4 4 2 

6 6 6 



4 4 


atom undei'gpes reorganisation after a disturbance in its interior, the 
energy levels obtainable for a neutral atom from the values of the 
frequencies of its X-radiation must agree with those representing the final 
orbits provided for this atom by the characteristics of its own arc 
spectrum as well as by those of the arc spectra of its ions or of the 
elements of lower atomic number. 

As stated above, the basis of Bohr's classification of the orbits of 
atoms in their normal state is largely of an experimental character. 
It is not altogether so, however, for he has been able in the case of a 
number of the simpler atoms to work out the relative stabilities of orbits 
that are conceivable ones for these atoms, and by the use of the quantum 
theory, supported by the Correspondence Principle, has obtained a 
theoretical justification for the classification that he has adopted. 

The results of Bohr's work in this direction are. given in Table I., 
where N denotes the atomic number and n and k give the values of 
the principal and subordinate quantum numbers respectively of the 
orbits indicated. According to the scheme, it will be seen, the orbits 
are divided into groups corresponding to the various values of the 
principal quantum number n, and into sub-groups designated by different 
values of the subscript quantum number k. While orbits for which 
n has the value 1 are all of one type, those for which n has the value 2 
are of two types, those for which n has the value 3 are of three types, 
and so on. 

Illustrations of the structure of a number of neutral atoms are given 
by the diagrams on Plates I. and II. These have been copied from 
a paper by Kramers* that has recently appeared, and are stated to be 
similar to those prepared by Bohr for use in his own lectures. The 
electron orbits in the neutral ato-ms selected are arranged in gi'oups 
from the centre of the atom outwards according to increasing values 
of the principal quantum number. The diagrams do not take account 
of the rotation of the orbits in their own plane, nor in the case of the 
heavier atoms is there any attempt to indicate the characteristics of 
the orbits close to the nucleus. They merely serve to illustrate in a 
general way Bohr's ideas regarding the genesis of atoms. A characteristic 
feature of the scheme is brought out by the illustrations of the orbits 
of the atoms of the* rare gases. These, it will be seen, provide for the 
recurrence of the structure of a lighter atom as a constituent part of 
the structure' of each of the heavier ones. 

An illustration given by Bohr of the process of binding an electron 
to a nucleus is shown in Fig. 2. In this diagram the representation is 
that of the stationary states corresponding to the emission of the arc 
spectrum of potassium. No attempt is made to depict the duplex 
character of each of the stationaiy states. The curves show the form 
of the orbits described in the stationary states by the last electron 
captured in the potassium atom. They can be considered to represent 
stages in the process whereby the 19th electron is bound after eighteen 
previous electrons have already been bound in their normal orbits. 
The orbits are marked with the symbol n,, where n and k are respectively 
the principal and subordinate quantum numbers. 

* Kramei's, Dir A^afvrifi.'i.irih'n-hriffrn, Hoft 27, July 6, 192.3. 



The states 4i 6i 61 . . . are tO' be considered as those which give rise 
to the a terms in the series arc spectrum of potassium. The states 
4; 5._ 63 connote the tt spectral terms, and the states 3,, A, the S 
spectral terms. The state 4:^ will give rise to one of the tf> or funda- 
mental terms in the series spectrum. 

Fig. 2.— Binding Potassium Orbits. 

Grotrian's method of exhibiting these relationships is instructive. 
Its application to the case of the stationary orbits of the potassium 
atom is shown in Fig. 3. 

A few outstanding features of the classification given in Table I. 
may be referred to. In the first place, the scheme provides for periodi- 
city in the properties of the elements. For example, in the case of 

2-5 3-0 -t 5 6 


I 4i-if- 

50000 40000 30000 20000 10000 

Fig. 3. — Grotrian Diagram. 

the heavier inert gases the outer group of electrons is made up of two 
sub-groups with four electronic orbits of the same type in each. For 
these sub-groups the subordinate quantum number has the values 1 and 
2. The principal quantum number increases by unity from element to 
element. Again, in the case of the alliali elements the outer group con- 
tains but one orbit. For it the subordinate quantum number k has 
the characteristic value 1, and the principal quantum number again 










" — - / 


s Pi 





increases by unity as we pass from a lighter to a heavier element in 
the alkali group. 

Another interesting feature of the classification is that in the genesis 
of the different kinds of atoms provision is mad© for the appearance 
at certain stages of sets of homologous elements such as those of the 
iron, palladium, platinum, and rare-earth groups. For example, the 
appearance of the iron group accompanies the establishment in the 
normal atojii of an inner gi-oup of orbits of the 83 type beginning with 
tlie element scandium. These 83 orbits begin in the fom-th period and 
differentiate it from the second and third because for the first time the 
charge on the nucleus is sufficiently great to make it possible for the 
successive atoms to differ by an extra electron in such an inner group 
instead of in an outer one. The appearance of the palladium group also 
is associated with the beginning of a development of inner orbits of the 
^3 type at a stage in the binding process when the outer orbits of the next 
lighter atoms consist of 5i quantum orbits. The appearance of the 
platinum and rare-earth groups of elements, too, it will be seen, is 
associated with the beginnings of developments of inner orbits of the 
5; and 4^ types respectively at stages in the binding process when 
the outer orbits of the neighbouring lighler elements are of the 61 type. 

56 Ba 



57 La 



58 Ce 



60 Ad 

9i U 

6/ - 

62 5m 


63 Eu 





67 Ho 














75 - 

— J 


77 J,- 



85 - 

86 Nt 

Fig. 4. — Elements. 


Argon (18) 


Xenon (5^ 

Plate II. 


These and other features of the classification that might be referred 
to are illustrated by the arrangement of the elements shown in Fig. 4. 
In this representation, it will be noted, those elements that belong to 
the same period are given in vertical columns, and those that from their 
chemical and optical properties can be considered homologous are 
connected with one another by straight lines. Groups of elements 
that possess analogous physical properties, and that differ from one 
another by variations in the number of electrons belonging to inner 
groups, are enclosed, as the diagram shows, by rectangular spacings. 

Peculiar interest attaches to the newly discovered element of atomic 
number 72, to which the name ' Hafnium '* has been given. Condi- 
tions imposed by the quantum theory, in Bohr's view, make it impera- 
tive to assign this element to the platinum group instead of to the rare- 
earth group, as Dauvillier ' and others have suggested. Theoretically, 
this element would appear to be a homologue of zirconium, and it is 
interesting to note that Coster and Henesy, who have been chiefly 
concerned with its discovery, have been able to obtain from zircon- 
bearing minerals considerable quantities of a substance whose chemical 
properties are similar to those of zirconium, and whose X-ray spectrum 
is that of an element with atomic number 72. 

In the remainder of my address I propose, with your permission, 
to deal with a number of matters that are closely associated with 
developments of the quantum theory of the origin of spectra and that 
appear to merit some special attention and consideration at the present 

The Fine Structure o£ the Balmer Lines of Hydrogen. 

In the simplest treatment by the quantum theory of the origin of the 
spectrum of atomic hydrogen no allowance is made for a variation 
in the mass of the electron with its speed. If this factor be taken into 
account, as it has been by Sommerfeld, it is found that the motion 
of the electron is reducible to a motion m an elliptic orbit upon which 
is imposed a slow rotation in its own plane about the nucleus as focus. 
The resulting orbit has the foi-m of a rosette, and is similar to that 
shown in Fig. 5. 

In this treatment the chief factor in determining the stationary 
states is the principal quantum number n, but the subordinate quantum 
number k is also contributory. The former practically determines the 
major axis and the period of the elliptical orbit, while the latter defines 
the parameter of the ellipse — i.e. the shortest chord through its focus. 
The subordinate quantum number k also determines the period of rota- 
tion of the elliptic orbit in its plane. The energy corresponding to 
each stationary state is in the main determined by the value of the 
quantum number n, but stationary states determined by the same value 
of n are characterised by energy values that vary shghtly with different 
values of the quantum number k. 

= Coster and Henesy, Nature, Jan. 20, Feb. 10, 24, and April 7, 1923. 
« Dauvillier, C.R., t. 174, p. 1347, May 1922; Urbain, C.E., t. 174, p 1349, 
May 1922, and t. 152, p. 141, 1911. 


The diagram showu in Fig. 1 represents an instantaneous aspect of 
the orbits of the different stationary states, and the designations ^7^ give 
the values of the quantum numbers characterising the different orbits. 

According to this treatment each of the numbers of the Balmer series 

1 1 

v=Ki , , 

V2 TO 

should consist of a doublet, and each of the components of these 
doublets should possess a fine structure. Calculations made by 
Sommerfeld showed, that the frequency difference for these doublets 
should be constant over the whole of the Balmer series, and should be 
equal to 0,36cm.-'. 

Fig. 5. — Rosette. 

As the theoiy applies equally well to the coi-responding series in the 
spectrum of positively charged helium, the doublets of this series were 
investigated by Paschen, and were found to have separations that led 
to a value of 0.3645 ±0.0045 for the frequency difference of the doublets 
of the hydrogen Balmer series. 

Since the publication of Paschen 's work on the helium doublets a 
number of investigators ' have attempted, from measurements on the 

' Micbelson and Morley, Phil. Mag., vol. 24, p. 46, 1887. 
Ebert, Wied. Ann., vol. 43, p. 800, 1891. 

Michelson, Bvr. Int. des Poids et Mesvres, vol. 11, p. 139, 1895. 
Houston, Pliil. Mag., vol. 7, p. 460, 1904. 
Fabry and Buisson, C.R., vol. 154, p. 1501, 1912. 
Paschen, Ann. dei Phys.. vol. 50, p. 933, 1916. 
Merton and Nicholson, Roy. Soc. Proc, A, vol. 93, p. 28, 1917. 
Merton, Roy. Soc. Proc, A, vol. 87, p. 307, 1920. 
Gehrcke and Lau, Pfiys. Zeit., vol. 21, p. 634, 1920. 
McLennan and Lowe, Roy. Soc. Proc, A, vol. 100, p. 217, 1921. 
Gehrcke and Lau, Phys. Zeit., vol. 22, p. 556, 1921. 
Oldenburg, Ann. der Phys., vol. 67, p. 69, 1922. 
Gehrcke and Lau, Ann. der Phys.. vol. 67, p. 388. 1922. 
Oldenburg, Ann. der Phys., vol. 67. p. 253, 1922. 
Geddes, Proc Roy. Soc. Edin., vol. 43, p. 37, 192.3. 


separations of H. and H^, and in some cases of H^ and K^, to look 
for evidence that would lead to a confirmation of Sommerfeld's theory. 
Up to the present the results obtained could not be considered as satis- 
factory. There was a lack of agreement in the values obtained for the 
separations by different investigators, and on the whole the values 
obtained were less than that demanded by the theory. The matter was 
reinvestigat-ed recently, at my suggestion, by one of the research workers 
in the Physical Laboratory of the University of Toronto, Mr. G. M. 
Shrum, and in his experiments he succeeded in eliminating practically 
the whole of the secondary spectrum, and as a result was able to include 
in his measurements of the doublet separations that of H. as well as 
those of H,, Hg, H,, and H*. 

The results are the following : — 



Separation of the Components 

Probable Error 





6562-79 A 
4861-33 „ 
4340-46 ., 
4101-73 „ 
3970-07 „ 

0-143 A 
0-085 „ 
0070 „ 
0061 „ 
0-055 „ 

0-33 cm.-i 
0-36 „ 
0-37 „ 
0-36 „ 
0-35 „ 

0-02 cm.-i 
0-01 „ 
0-02 „ 
0-02 „ 
0-02 „ 

It will be seen that as far as the doublet separations are concerned they 
afford a striking confirmation of Sommerfeld's theory. 

Model of the Atom of Helium. 

Ck>nsiderable interest attaches to the atom of Helium. From the 
chemical point of view it has been considered to be inert, and conse- 
quently not likely to enter into chemical combination. Of all atoms 
it is the most stable, for it has the highest ionisation potential, namely 
24.5 volts. A study of the X-radiation emitted by the elements gener- 
ally makes it appear that the configuration we assign to the electi-onic 
orbits in helium atoms is maintained intact throughout the whole of 
the remaining heavier elements. These orbits, as Table I. shows, 
constitute for all atoms the K X-ray group the innermost and most stable 
system. For these reasons it is highly desirable that a model of the 
atom of helium be realised possessing high stability endowed with the 
capacity to emit radiation exhibiting the characteristic features of the 
helium spectrum, and having energy values for its normal and tem- 
porary stationary states that fit in with the experimentally determined 
values of its ionisation, resonance, and other critical excitation 

The earher models of the atom of helium put forward failed entirely 
to meet these requii-ements. Models recently conceived by Lande * and 
by Bohr' are at the present time receiving considerable attention. In 
these the two electrons in the normal atom are taken to move in equiva- 
lent li orbits. As a first approximation these may be described as 

» Lande, I'hys. Zeit., No. 20. p. 228, 1919. 
' Bohr, Zeit. fiir Phys., No. 2, p. 464, 1920. 


cii'cuiar orbits with planes inclined at an angle to each other. Bohr 
assumes this angle to be 120°, and on account of the interaction between 
the two electrons the two orbits are supposed to be slowly turning 
about a fixed momentum axis in the atom. A diagrammatic representa- 
tion of this model is shown in Fig. 6. 

Such a model, however, will not account for the whole of the 
specti'um of helium, which is known to consist of two complete but 
separate sets of series, the one being made up of single lines and the 
other of doublets. An important feature of the spectrum of helium, 
too, is that it contains no lines that are the result of combinations 
between spectral terms belonging to one of the sets of series and those 
belonging to the other. The explanation put forward is that while 
helium in its noi-mal state exists in the form of atoms with crossed 
orbits, designated by the name pai'helium, it can also exist in a meta- 
stable form, known as orthohelium, as well. In the latter state the 
electronic orbits are supposed to he< in the same plane with the electrons 
revolving in the same direction. In the most stable form of ortho- 

Ftg. 6.— Helium Model. 

helium one of the electrons is supposed to move in a Ij orbit and the 
second in a 2i orbit. The singlet series in the spectrum of helium are 
assigned to parhelium and the doublet series tO' orthohelium. 

If parhelium be bombarded by electrons it appears to be possible to 
transform its atoms into the metastable foiTn, but once the atoms are 
in the latter state it does not seem to be possible for them to revert 
directly to the normal form by means of a simple transition accom- 
panied by the emission of radiation. They can only do so by a process 
analogous to a chemical reaction involving interaction with atoms of 
other elements. 

The fact that helium, under certain conditions, can be made to emit 
a band spectrum in addition to its line spectrum connotes the possi- 
bility of helium existing in the molecular form. Since helium in the 
form of orthohelium has its outer electron in a 2i orbit, the atoms of 
orthohelium in so far as chemical combination is concerned occupy a 
position analogous to atoms of lithium, which also possess a 2^ orbit 
in their noi'mal state. As this feature enables lithium to react 


vigorously with other atoms, one would expect orthohelium also to be 
capable of entering into chemical combinations. From this it would 
appear that molecular helium originates in atoms that have undergone 
a transition into the metastable state. As to the atoms of parhelium, 
there appears to be no warrant of this or any other character for sup- 
posing that they can participate in any kind of chemical union. 

It is probable that orthohelium, if obtainable in sufficient amounts, 
may be found to be more easily liquefied and solidified than parhelium. 
It would, however, in the liquid or sohd state be highly explosive. This 
will be seen from the data in Table II. A study of the band spectrum 
of helium or of its compounds at low temperatures would be interesting 
for what it might reveal regarding the origin of the spectrum of nebulae. 
The views just presented have gained strong support from Frank and 
Knipping's experiments on the excitation potentials of helium atoms 
by electronic bombardment, and by Lyman's recent work on the 
extreme ultra-violet spectrum of helium, in which it has been shown 
that radiation of the wave-lengths 600.5 A, 584.4 A, 537.1 A, 522.3 A, 
and 515.7 A are absorbed by helium in its normal state. The scheme ^° 
set forth in Fig. 7 and the data collated in Table II. are self-explanatory, 
and show how on the view just put forward the radiation whose wave- 
lengths were measured by Lyman can originate, and how the excitation 
potentials observed by Frank and Knipping can be realised. 

A*ccording to this scheme electrons with a speed con-esponding to a 
potential of 19.75 volts will be able to transform parhelium into ortho- 
helium, and those with speeds corresponding to 20.55 volts and 
21.2 volts will be able to lift the electrons from 1, S orbits to 2, S and 
2, P orbits respectively. Under bombardment by electrons with speeds 
the equivalent of 24.5 volts the helium atoms will be ionised. The 
scheme shown in Fig. 7 also indicates how the series spectrum of 
orthohelium originates. 

The considerations set forth above would seem to clear up some of 
the difficulties that have hitherto been encountered in realising a satis- 
factory model of the helium atom, and in reaching an explanation of 
the origin of the radiation that atoms of helium can emit. The com- 
plete solution of the problem, however, has received a set-back from 
the results of an investigation recently carried out by Kramers," for 
according to his calculations the ionisation potential of the crossed 
orbit model comes out 3.8 volts less than the experimentally determined 
value. His calculations also show that in a mechanical sense the 
crossed orbit model cannot be considered to be a stable one. Although 
real progress has been made, it cannot be said that finality has been 
reached in the determination of the form of a completely satisfactory 
model of the atom of so simple an element as helium. 

A somewhat novel aspect of the problem has recently been empha- 
sised by Silberstein.^^ He assumes the crossed orbit, model of the 
helium atom to be capable of taking up a number of stationary states 

1" Grotrian, Die Naturivlssenschaften, Heft 17, p. 321, 1923. 

" H. A. Kramers, Zeit. fiir Phys., vol. 13, p. .339. 1923. 

1= Silberstein, Nature, Ap. 28, p. 567, 1923, and July 14, p. 53. 1923. 



Nvith the planes of the orbits at a series of ungles other than 120°. On 
this basis he has been able, by taking for granted the dynamical legiti- 
macy of the crossed orbit system, to calculate values for the ionisation 



515 1 522-3 53J.1 

45 35 





50000 100000 150 000 

Fig. 7. — Scheme of He Lines. 

200 000 = 

and other excitation potentials that are in remarkably good agreement 
with the expeiimental values found by Prank and Knipping, Horton, 
and others. 





F. & K.'s 

by Lyman 





1, S-2, s 



Transition voltage connoting 
change from parhelium to ortho- 

600-5 A 




A weak radiation and one not pro- 
vided for by the principle of 

584-4 „ 




First member of absorption series 
of parhelium. 

537-1 „ 




Second member of absorption series 
of parhelium. 

522-3 „ 




Third member, &c. 

515-7 „ 

5,P-1, S 



Fourth member, &c. 

502-0 „ 

1, S 



Series limit and ionisation poten- 





Resonance and.Ionisation Potentials. 

The results of investigations on the absorption spectra of zinc, 
cadmium, and mercury, and on the resonance and ionisation potentials 
of these elements, have shewn that for this group of elements the 
ionisation potentials are given by V = /iv/e, where v is the frequency 
denoted by {n, S), namely, that of the last member of the series 
V = {n,Q) — {ni,V)}^ Tt is also known that their resonance potentials are 
given by the same relation with v having the value (n,S) — ( the 
frequency of the first member of a combination series. In the 
case of the alkahne earths similar relations obtain. With the alkali 
elements the frequencies that determine the resonance and ionisation 
potentials are given by v = (w, a) — («, tt)^* andv = (»,cr) respectively. 
It is, therefore, clear from the characteristics of the spectral terms 
involved that, while the electron concerned in phenomena associated 
with resonance and ionisation potentials must be the one that is most 
easily displaced in or removed from the atom, this electron must be 
bound in atoms of the elements mentioned — when these are in their 
normal state — in orbits of the iii type, i.e. in orbits for which the 
subordinate quantum number has the value 1. Now, a reference to 
Table I. will show that this characteristic is exactly the one possessed 
by the electron that is last bound in the atoms of the elements cited. 

It follows, then, that if we know the type of orbit occupied by the 
last bound electron in the normal atom of any element we can at once 
deduce the type of the series whose first and last members will enable 
us to calculate the resonance and ionisation potentials of the element. 
Moreover, the wave-lengths of such a series will be the ones that will 
be selectively absorbed by the vapour of the element, provided its tem- 
perature is sufficiently low to ensure that the atoms constituting the 
vapour are in their normal state. 

Previous to the publication by Bohr of the scheme in Table I. it 
had been thought that for all elements the resonance and ionisation 
potentials should be obtainable from spectral frequencies of the 
(«, <y) — {m, tt) or (w. S) — {m, P) type. Numerous attempts were made 
by investigators of the absoi-ption spectra of such elements as thallium, 
lead, tin, &c., to group the wave-lengths of the radiation absorbed into 
a principal series that would enable one to calculate the critical potentials 
for these elements. These efforts, however, ended in failure, for though 
wave-lengths were found that were selectively absorbed by the vapours 
of the elements refen'ed to, and though it was found possible to fit 
these partially at least into series, it was clear that the series obtained 
did not satisfy the conditions demanded by series of the principal type. 

By the publication of Bohr's scheme of atomic orbits, however, it 
became evident that since in the case of the aluminium group of 
elements, for example, the electron last acquired in making the atoms 
neutral is bound in an orbit of the n^ type, the first member of the 

'■■' According to Bohr's scheme n has the value 4 for Zn, 5 for Cd, and 6 
for Hg, while m has the value 2. 

1' In this formula n has the value 2 for Li. 3 for Na. 4 for K. 5 for Rb. and 
6 for Cs. 


spectral series that would enable us to calculate the resonance and 
ionisation potentials for this group of elements must be of the type 
v=^(»,Tc) - (to, .r) and not of the type v = (7i, a) - {m, n). Moreover, 
this makes it clear that the series of wave-lengths that should be selectively 
absorbed by vapours in the normal state of the elements of the 
aluminium group would be the first and second subordinate ones repre- 
sented by V = (n, Tc) — (m, o) and v = (n, 7c) — (in, 8). 

Recent experiments by Carroll ^'' and by Grotrian,'' as well as earlier 
ones by Wood and Guthrie '' and by the writer,'* show that the wave- 
lengths most readily absorbed by non-luuiinous thallium vapour all 
belong to the sharp or diffuse sulx>rdinate series in the spectrum of this 
element. With indium vapour Grotrian has obtained similar results. 
With aluminium, as with thallium, the wave-lengths absorbed by the 
comparatively cool vapour that surrounds an electric arc in the metal 
belong to the sharp and diffuse subordinate series. 

From these results it is clear that the evidence furnished by spectral 
data amply confirms the view put forward by Bohr that in the case 
of the heavier elements of the aluminium group at least, the electron 
last acquired by the neutral atom of the respective elements is bound 
in an orbit of the n, type. In the case of the light element boron, 
the series data available are so meagre that it is not possible as yet to 
affirm that the same law applies. 

From the known values of the frequency v = {n, tt,,) in the spectra 
of the elements aluminium, gallium, indium, and thallium, it follows 
that the resonance potentials for these elements are respectively 3.12 v., 
3.08 v., 3.00 v., and 3.26 v., and that the ionisation potentials are 
respectively 5.94 v., 5.96 v., 5.75 v., and 6.07 v. 

For thallium, the only element of this group as yet investigated 
by the method of electronic impact, Foote and Mohler found the reson- 
ance and ionisation potentials to have the respective values 1.07 v. 
and 7.3 v. The agreement, it will be seen, is not very close. It should 
be noted, however, that Foote and Mohler, in giving their results, 
indicate that they should be considered to be approximate only. 

Electronic Orbits of the Atoms of the Lead-Tin Group. 

It will be seen that the scheme of orbits given in Table I. makes 
no provision for the elements of the Lead-Tin group. The reason for 
. this is that hitherto but little spectroscopic data have been available 
for these elements. Besides, the development of the quantum theory 
does not appear to have been sufficiently advanced to include the atoms 
of these elements within the scope of its application. Progress with 
these elements is, however, now possible owing to the fact that 
Thorsen '° has been able to organise a part of the spectrum of lead 
into a triplet set of first and second subordinate series. These series 

'"■ Carroll, Proc. Roy. Soc, Series A. vol. 103, p. 334, May 1923. 

"■ (Irotiian, Zclf. fiir /'/m/x.. Bd. 12. ji. 218, 1923. 

" Wood and Guthrie, Asf. P/ij/s. .11., vol. 29, p. 211. 1909. 

1** McLennan, Young and Ireton, Proc. Roy. Soc. of Canada, Section III., 
p. 7, 1919. 

^^ Thorsen, DIr Nutiirwissen.'ichaff.en, Heft 5, Feb. 2, 1923. Recent experi- 
ments by Thoison load to the value of 9.18 v. for the ionisation potential of gold. 

192;j F 


have frequencies given by v = («, pj — (?«, .s)'° and "^ = {11, p^) — {rn, d) 
where x has the values 1, 2, 3. In all about 54 wave-lengths have been 
allocated into places in these series. In this connection it is of import- 
ance to note that Thorsen does not seem to have been able to assign 
any of the wave-lengths in the lead spectrum to a related principal series. 

Following up this work, Grotrian'' has recently pointed out that 
of the wave-lengths known to be selectively absorbed by non-luminous 
lead vapour, "' the prominent ones X = 2833'A, X=2170 A, X = 2063.8 A, 
and X = 3683 A were not included in the series formulated by Thorsen. 
He has been able to show, further, that they can be included in a more 
extended scheme of first and second subordinate series that includes, 
in addition to those of Thorsen, two others that have for their highest 
frequencies v = (2, p,) = 59826'cm"'andv = 2, p, = 5 L677 cm"'. According 
to this schemeX = 2833 A would have the frequency v = (2, p.,) — (2, s), 
X=2053 A the frequency v= (2,^4)- (3, s),X =2170 A the frequency 
V = (2, ijj - (3, di), and X="3683 A the frequency (2, pr) - (2, s) . These 
results lead at once to definite conclusions regarding the outermost orbit 
in the normal atoms of lead. Since^ all the wave-lengths absoi'bed 
are members of subordinate series, it follows that the electron last 
acquired by a neutral atom of lead must be bound in an orbit for which 
the subordinate quantum number k has the value 2. This leads to the 
conclusion that the scheme of orbits for lead will include two of the 
61 type and two of the 60 type. 

From the frequencies 

V = (2, 2h) - (2, s) = 35296cm-' and v = (2, j},) = 59826cm"' 
it follows that the resonance and ionisation potentials of lead should 
be respectively 4.35 v. and 7.4 v. As Foote and Mohler have found 
by the method of electronic impact these critical potentials to be 1.26 v. 
and 7.93 v., it will be seen that while the values for the resonance 
potentials show no agreement, there is a fair agreement in the case 
of the values of the ionisation potentials. 

As very little is known about the series spectra of tin " and german- 
ium, one cannot as yet write with precision about the outeiTnost orbits of 
the normal atoms of these elements. Considerations of periodicity make 
it highly probable that they will be of the same type as those of lead. 
This would mean that tin should have its two outermost electrons 
bound in the normal atoms of equivalent 5^ orbits, and the normal 
atoms of geiTnanium their two outermost electrons bound in 42 orbits. 
The results obtained with the series spectra of lead will no doubt lead 
immediately to the organisation 6i the spectral lines of tin and ger- 
manium into series. 

Though but little has been published about the series spectra of 
neutral atoms of silicon, Fowler reports that he has been able to show 
that the arc spectrum of this element includes a number of related 

-" According to Thorsen n has the effective value 2 in this formula. 

="1 Grotrian, Die Natiirwisaenscfiaften, Heft 13, March 30, 1923. 

22 McLennan and Zumstein, Proc. Boy. Soc. of Canada, Section III., 
vol. xiv., p. 9, 1920. 

-•' The writer has been able to show recently that the spectrum of tin 
includes series of the same type as those of lead. 


triplets. In this regard it is analogous to the spectrum of lead as 
originally classified into series by Thorsen. From general considera- 
tions the existence of these triplet series would connote that there are 
two valency electrons in the atoms of silicon. As the outei-most electron 
in normal atoms of aluminium is bound in a 3, orbit, the two outer- 
most electrons in the normal atoms of silicon would appear to be bound 
in equivalent orbits of this type. 

As to normal atoms of carbon, Bohr has expressed the opinion that 
the four last bound electrons may be expected to form an exceptionally 
synimetrical configuration, in which the normals to the planes of the 
orbits occupy positions relative to one another nearly the same as the 
lines from the centre to the vertices of a regular tetrahedron. Such 
a configuration would, it is evident, furnish a suitable foundation for 
explaining the structure of organic compounds. Thus, considerations 
of symmetry would undoubtedly lead to the view that the four outer 
electrons in carbon atoms were all bound in 1, quantum orbits sym- 
metrically arranged in space. 

This scheme of outer orbits is radically different from that ascribed 
above to the outer orbits of the atoms of lead, tin, germanium, and 
silicon, and the explanation of the difference is at yet not at all clear. 

The fact that the spectrum of lead has been shown to include at least 
five sharp subordinate series and four diffuse subordinate series suggests 
in a measure a parallel to the spectrum of neon for which Paschen -■• 
has identified at least thirty sharp series and seventy-two diffuse series. 
Multiple series of this character have also been shown by Meissner ^^ 
and by Nissen ^° to be included in the spectrum of argon. Though this 
parallel might be taken to indicate that the orbits of the four last 
bound electrons in the atoms of lead and in those of the allied elements 
are all of the n^ type, it would seem that since the wave-lengths selec- 
tively absorbed by lead vapour all belong to subordinate series, we must 
conclude that in the case of lead at least its outermost orbits must be 
two in number and of the 6, type. Carbon, too, in all probability will 
be found to have two of its outennost electrons in 2, orbits and two 
in 2; orbits. 

The Kossel-Sommerfeld Displacement Law. 

I have stated that Bohr in arriving at his scheme of atomic orbits 
was guided by the view that the fundamental process to keep in mind 
was that when a nucleus originally naked acquired electrons sufficient 
in number to neutralise its charge, it did so by binding them according 
to a programme that was definite and fixed for each value of the 
nuclear charge. 

If this view be accepted, it follows that if we were to detach from 
the neutral atom of an element its most loosely bound electron, we 
should expect to find that the orbits which remained were characterised 
by the same quantum numbers as defined them in the neutral atom. 
Moreover, except in certain special cases, these orbits would be identical 

^* Paschen-Gotze, Seriengesctze der Li?iienspel-tren, p. 30. 
^^ Meissner, .47!?!. d. Phys., Bd. 51, p. 95, 1915. 
*« Nissen, Phys. Zeit., vol. 21, p. 25, 1920. 

IT 2 


in type with those of the neutral atoms of the next hghter element. 
The exceptional cases would include tliose elements whose atomic 
structure involved the commencement of the development of an inner 
system of orbits, such as those of the 83, 4^, 4,i, &c., groups. Subject 
to these limitations, we should expect to find that if the 11 last-bound 
electrons were removed from a neutral atom of an element the orbits 
that remained ni this atom would be identical in type with those of 
the neutral atoms of the rfth lighter element. This would mean that 
the arc spectrum of the mono^"alent positive ion of arc element w^ould 
be identical as to types of series involved with the arc spectrum of the 
neutral atoms of the next lighter element. There would be this differ- 
ence, however, that in the series formulfe of the spectrum oi the ion 
the Eydberg constant) would be 4K, whereas in the series of the 
spectrum of the neutral atoms of the lighter element it would be K. 
Putting the matter as it is ordinarily stated, the spark spectrum of 
an element should be made up of series of the same type as those of the 
arc spectrum of the next lighter element. This is known as the Kossel- 
Sommerfeld Displacement Law. 

Numerous illustrations of this law might be cited. For example, 
the series in the spectrum of the monovalent positive helium ion are 
of the same type as those of the spectrum of atomic hydrogen. Again, 
the series in the spark spectra of the alkali elements have been shown 
to be similar in type to those of the arc spectra of the rare gases. In 
the case of potassium,-' it has been shown that in addition to its arc' 
spectrum it can, under moderate excitation, emit a series spectrum 
identical in type with that of the red spectrum of argon, and under 
violent excitation a spectrum having all the characteristics of the blue 
spectrum of this inert gas. In the case of the alkaline earths, the 
series spark spectra have the same characteristics as the arc spectra 
of the alkali elements. 

But perhaps the most striking confirTnation of tlie correctness of 
Bohr's view of the process of binding electrons to nuclei, and also at 
the same time of the validity of the Kossel-Rommerfeld Taw, is found 
in recent work by Paschen -* and by Fowler "' on the spectra of doubly 
ionised aluminium and trebly ionised silicon. 

It \vi\\ be recalled that Fowler some years ago showed that the wave- 
lengths of the spark spectrum of magnesium could be organised into 
series having 4K for their Rydberg constant. Early this year Paschen 
carried tlie matter farther by showing that under strong excitation 
aluminium emits a spectrum that can be arranged into series with a 
Rydberg constant equal to 9K. Now Fowler has capped it all by 
showing in a brilliant piece of work that in the spai'k spectnim of 
silicon certain wave-lengths can be grouped into series with a Eydberg 
constant of 16K. With both elements the series referred to are doublet 
series of the type obtained in the arc spectrum of sodium. 

27 McLennan, Proc. Hoy. Soc, vol. 100, p. 182, 1921, and Zeeman and Dik, 
Konin. Akad. Van Weten, Amsterdam, Proc, vol. xxv., p. 1, April 29, 1922, and 
Anv der Pfiys., Bd. 71, Heft 1/4, p. 188. 1923. 

-•'* Paschen. Ann. drr P/u/s.. Rd. 71. Heft 1;M. p. 142. Hett S. p. ,537. 1923. 

=» Fowler, Proc. Boy. Soc, vol. 103, No. A, 722. June 1923. 


In terms of Bohr's theory the 9-fold value of the Rydberg constant 
would be interpreted as meaning tliat aluminiLun atoms which emitted 
this spectrum had lost two electrons, and were represented by A1+ + , 
or, as it is now written, Al(in). The 16-fold Eydberg constant would, 
on the same theory, also be interpreted as meaning that the atoms of 
silicon which emitted this spectrum were those that had lost three 
electrons, i.e. Si(iv). Tliese results, it will be seen, amply confirm 
the view that the bound electrons in the neutral atoms of sodium, Na(i), 
are of the same type and are characterised by the same quantum 
numbers as those of the singly ionised atom of magnesium, Mg(n), 
of the doubly-ionised atom, of aluminium, Al(iJi), and of the trebly- 
ionised atom O'f silicon, Si(iv). 

What has been found to be true of the spectra of sodium, magnesium, 
aluminium, and silicon, will no doubt be found to be true of the spectra 
of the elements lithium, beryllium, boron, and carbon. The spectra 
of beryllium and boron are extremely meagre in wave-lengths, and but 
little is known of their spectral series. The specti-um of carbon, how- 
ever, especially in the extreme ultra-violet, has been well worked out 
by a number of observers, and particularly so by Simeon.^" 

In the spectrum of berylUum the doublet X = 3131.194 A, 
X =3130.546 A has been shown to be the first member of a principal 
and a second subordinate series of doublets. Moreover, Back/' who 
recently investigated its magnetic resolution, has found that the mag- 
netic components are of the Dj and D, type, just as Kent has shown 
the magnetic components of the close lithium doublet X = 6708 A 
to be. It will, therefore, probably be found when the spectrum of 
bei-yUium has been extended that the doublet X = 3131.194 A, 
X =3130.546 A will prove to be the first member of the doublet series 
of the positive singly-charged atom of beryllium, wath a Eydberg con- 
stant for the series of 4K. In the spectrum of boron the doublets 
X =2497.73 A, X =2496.78 A and X"=2089.49 A, X =2088.84 A, 
particularly the latter, merit attention in looking for a 9Iv series. In 
the ultra-violet spectrum of carbon there is a strong doublet at 
X =1335.66 A, X =1334.44 A, and another nearly as strong at 
X =1329.60 A, X = 1329.07 A. These two also merit attention in any 
attempt to identify 16K series for this element. 

In considering the general validity of the Kossel-Sommerfeld Dis- 
placement Law the recent work of Catalan ^" on the series spectra of 
manganese, chromium and molybdenum is of interest. 

The spectra of the neutral and singly ionised atoms of manganese, 
as well as that of the neutral atoms of chromium, have been shown 
by him to consist of sets of sharp diffuse and principal triplet series. 
Moreover, he has found that in all these spectra there are certain 
groups of prominent lines, to which the name ' multiplet ' has been 
given, that have similar characteristics, and that show similar varia- 
tions with changes in temperature. This has led Catalan to put forward 

••"' Simeon, Proc. JRoi/. Soc, A, vol. 102, p. 490, 1923. 
" Back, Ann. der I'hys., No. 5, p. 333, 1923. 

" Catalan, Phil. Trans., Noy. Soc. Series A, vol. 223. pp. 127-173, 1922; 
C.IL, .Jan. 8 and 22. and April ic. 1923. 


the view that the neutral atom of manganese has an outer system of 
two electrons, and that when this atom loses one of its most loosely 
bound ones another electron from the next inner system comes out to 
take its place in the outermost system, so that the latter again contains 
two electrons. The similarity of the spectra of the neutral and singly 
ionised atoms of manganese would thus be accounted for. By assuming 
that this final configuration of the orbits in the singly ionised atoms 
of manganese was the same as the configuration of the outer orbits 
in the neutral atoms of chromium, the similarity of the arc spectrum 
of chromium to those of the singly ionised and neutral atoms of man- 
ganese would also be explained. 

Catalan's series relations show that the two last acquired electrons 
in the neutral atoms of manganese and chromium are bound in equiva- 
lent orbits of the 4, type, and that as a consequence the ionisation 
potentials of these two elements are given by a frequency of the form 
V =(1.5), and have the values 7.4 v. and 6.7 v. respectively. 

In some later work Catalan" has shown that the scheme of series 
in the spectrum of molybdenum is identical with that which applies to 
the spectrum of chromium. With this element he deduced the value 
7.1 volts for the ionisation potential. The two last acquired electrons 
in the atom of molybdenum would appear to be bound in equivalent 
orbits of the 5^ type. 

From the considerations that have been presented in regard to the 
atoms and the spectra of chromium and manganese some deductions 
can be made regarding the spectrum and stationary orbits of the un- 
known element of atomic number 43. Its arc spectrum, and probably 
that of its singly charged positive ion too, will likely consist of triplet 
series. Its spectrum will also very likely include a set of multiplets, 
and its two outer electrons will probably be found in equivalent 5, orbits. 
Although some considerations recently put forward by Lande'* and by 
Back^^ may lead to modifications in the views expressed above, the 
possibility of making these deductions constitutes a rather remarkable 
testimony to the power of the methods that are being at present applied 
in unravelling the mysteries of atomic structure and of the origin of 

An interesting point in connection with the Kossel-Sommerfeld 
Displacem-ent Law arises in connection with the magnetic properties 
of the neutral atoms of argon, of the singly-charged positive atom ions 
of potassium, and of the singly-charged negative atom ions of chlorine. 
Eecent work by W. L. Bragg'' and Davey,^' as well as a report by 
Herzfeld,'* go to show that the ions referred to and the atom of argon 
have practically the same dimensions, with a radius of about 
1.56x10-' cm. It appears also from the work of Konigsberger," 

ss Catalan, Cli., April 16, 1923. 

3* Lande, Zeit. fur Phys., vol. 15, p. 189, 1923. 

3= Back, Zeit. f'iir Phys.. vol. 15, p. 206, 1923. 

S6 W. L. Bragg, Phil. Mag., vol. xl., p. 187, 1920. 

"■? Davey, Phys. Rev., vol. xviii.. p. 103, 1921. 

'« Herzfeld, Jahr. der Bad. und Elek.. Bd. 19, p. 259, 1922. 

s9 Konigsberger, Ann. der Phys., vol. 66, p. 713, 1898. 



St. Meyer,'" Curie," and Sone" that the atom ions of potassium and 
chlorine and the atoms of argon are diamagnelic. 

Since these ions and the atoms of argon contain the same number 
of electrons, and since the electrons in all three are supposed to be 
bound in orbits of the same type and of the same area, one would 
expect them to show identical diamagnetic properties. The experi- 
mental results, however, do not appear to support this view. While 
the specific magnetic susceptibility of argon has been shown 
by Sone to have the value 5.86x10-% that of the singly-charged nega- 
tive atom ions oi chlorine and of the singly-charged positive atom ions 
of potassium have been found from observations on the magnetic pro- 
perties of potassium chloride to be equal approximately to 0.65x10-% 
i.e. the diamagnetic susceptibility of argon is about ten times that of 
the ions of potassium and chlorine. As Pauh"^ has shown that this 
high value of the diamagnetic susceptibility of argon leads on certain 
simple assumptions to a value for the moment of inertia of the atoms 
of argon about ten times too great, it would appear that the discrepancy 
arises in connection with the evaluation of the diamagnetic susceptibility 
of argon. Although all the experimental v;ork involved appears to 
have been carefully done, it is evident that the investigation of the dia- 
magnetic properties of these elements will have to be carried further 
before the matter is finally cleared up. 

Quantisation in Space. 

One of the most surprising and interesting developments of the 
quantum theory is that which shows that quantum numbers determine 
not only the size and form of the electronic Keplerian orbits in atoms, 
but also the orientation of these orbits in space with regard to a favoured 
direction such as that provided by an intra-atomic or by an external 
magnetic or electric field of force. For any. arbitrary value of the 
azimuthal quantum number fc, the simple theory shows that there 
are exactly k + 1 quantum positions of the orbital plane characterised 
by whole numbers. For example, if /<; = 1 the normal to the orbit may 
be either parallel to the direction of the controlling field or at right 
angles to it. If fc = 2 the normal to the orbit may take up in addition 
to these two positions a third one, in which the normal to the orbit 
makes an angle of 60° with the field. For higher values of the quantum 
number fc, the possible orientations of the corresponding orbits become 
regularly more numerous. 

A striking confirmation of this theory is afforded by the very 
beautiful experiments of Gerlach and Stern." In these a stream of 
atoms of vaporised silver was allowed to flow past a wedge-shaped 
pole of an electromagnet which provided a radial non-uniform magnetic 

« St. Meyer, Ann. der Phys., vol. 69, p. 239, 1899. 

" Curie, .//. de Phys., 3, S. 4, p. 204, 1895. 

«2 Sone, Tohokv Univ. Sc. Tiep., vol. 8, pp. 115-167, Dec. 1919, and Phil. 
A/ ao., vol. 39, p. 305, March 1920. 

" Pauli, Zeit. iiir P/iys., Bd. Heft 2, p. 201, 1920. 

<■« Gerlach and Stern, Zeit. fiir Phys., vol. 7, p. 249, 1921: vol. 8, p. 110, 
1921 ; vol. 9, p. 349 and p. 353, 1922. 


field. The atoms were caught on a glass plate placed immediately 
behind the pole, and it was found that they were deposited in two 
distinct sharply defined layers, indicating that the atoms were sorted 
out into two distinct and separate beams. The positions of the bands 
on tiie plate showed that one of tlie beams was attracted by the pole 
and the other repelled by it, the attraction being slightly the greater in 
intensity. No evidence was obtained of an undefiected beam. From 
these results it was concluded that all the silver atoms in the stream of 
vapour possessed a definite magnetic moment, and that while the atoms 
were passing through ihe magnetic field their magnetic axes had two 
distinct orientations in space. 

By assuming the correctness of this interpretation, Gerlach and 
Stern found from measurements on the various magnitudes involved 
in the phenomenon that within the limits of error of their experiments 
the magnetic moment of the normal atom of silver in the gaseous 
state was that of one Bohr magneton. 

Bohr, also, has drawn attention to another possible illustration of 
the principle of the quantisation of orbits in space. It is known that 
all the rare gases do not exhibit the property of paramagnetism. From 
this fact the conclusion has been drawn that the atoms of these gases 
in their normal condition do not possess any angular momentum. 
According to the quantum Iheoiy, however, this conclusion may not be 
warranted, for we have seen that for an atom which has a finite angular 
momentum and, consequently,^ possesses a magnetic moment, the 
theory prescribes certain definite directions for the axis ox momentum 
relative to a magnetic field in winch the atom may be situated. If 
we assume that the atoms of the rare gases in a magnetic field can place 
themselves with their momentum axes perpendicular to the magnetic 
field, it follows that they could appear to be diamagnetic, and all indica- 
tion of paramagnetism on their part would be absent. In this connec- 
tion I may point out that Bohr has made the suggestion that evidence 
in support of the validity of this view is derivable from the results of 
an analysis, on the basis of the quantum theory, of the anomalous 
Zeeman effect shown by the rare gases. 

One point that may be worthy of notice in dealing with phenomena 
associated with the principle of space quantisation is that the permitted 
orientations depend only on the values of the quantum number involved, 
and not on the magnitude of the magnetic field applied. 

Orbit's characterised by certain definite values of the quantum number 
should take up their permitted orientations in weak magnetic fields as 
well as in strong ones, provided the time allowed for the process to 
take place was ample, and provided suitable pressures were used and 
disturbances arising from the presence of contaminating gases were 
eliminated. Such conditions as these have recently been realised by 
Gerlach and Schutz,^^ and they have been able to obtain with sodium 
vapour at low pressures in the absence of foreign gases remarkably 
striking manifestations of the magnetic rotation of the plane of 

<= Gerlach and Schutz, Die Naturivlisinschuiten, vol. 11, Heft 28, p. 638, 


polarisation of the light passing through the vapoui with magnetic iields 
as low as a lew tentlis ot a gauss. 

This idea of space quantisation may perhaps throw some light 
on the interesting and suggestive experiments of R. W. Wood and 
A. EUett ""^ on the polarisation of the resonance light eniitted by mercury 
and sodium vapom's. In their experiments, it will be recalled, strong 
polai'isation of the resonance light from mercury or sodium vapours 
could be produced by weak magnetic fields properly orientated. More- 
over, they found that the polarisation of the resonance light emitted by 
these vapours in the presence of the earth's magnetic field could be 
destroyed by applying a magnetic field of less than one gauss provided 
it was suitably orientated. It is highly desirable that the experiments 
of Wood and Ellett should be followed up in order that sufficient 
information may be gained to enable us to elucidate the principles 
underlying the modifications in the polarisation of the resonance light 
observed by them. 

It seems clear that atoms of sodium, for example, when excited 
by the absorption of resonance radiation would tend during the period 
of excitation to take up definite and characteristic orientations even in 
weak magnetic fields that would result in the polarisation of the re- 
sonance radiation emitted being different from that of the radiation 
emitted from atoms of the vapour situated in space in which absolutely 
no magnetic field existed. It should be remembered, too, that in the 
normal atom of sodium the orbit in which the valency electron is bound 
has the value 1 for its characteristic azimuthal quantum number k. 
When the atom is excited by the absorption of resonance radiation the 
azimuthal quantum number of the orbit, in which the valency electron 
becomes bound for a time, takes on the value 2. It seems clear then 
that the electronic orbit of the valency electron may be subject to 
different orientaticris relative to the rest of the atoin when the atom 
is in the excited state from what it would be with the atom in its 
normal state. These relative orientations, moreover, would again be 
different in the presence of even a weak external magnetic field from 
what they would be in the complete absence of such a field. It is, 
therefore, quite conceivable that changes in orientation of electron 
orbits may be able to account for the phenomena observed by Wood 
and Ellett, but at present the whole matter appears to be rather involved 
and rather difficult to clear up with the information as yet available. 

Qnantum Theory and the Zeeman Effect. 

Among the most fruitful of the prinfciples utilised by Bohr in the 
development of his theory of radiation is the Adiabatic Hypothesis 
enunciated by Ehrenfest.'" To this hypothesis Bohr has given the 
name the Principle of Mechanical Transformability. Numerous examples 
of the application of this principle might be cited, but the one that 
concerns us most here is that which deals with the effect of the 
establishment of a magnetic field on the electronic orbits in atoms. It 

« Wood and Ellett, Proc. Roy. Soe., A, June 1923, p. 396. 

*' Ehrenfest, Die A'atunri.'^.-<fn.-<r/i(iftcri, vol. 11, Heft 27, Julv 6. 1923, 
p. 543. 


IS well known that Larmor has shown that one result of the establish- 
ment of such a field is to endow an electronic orbit with a uniform 
rotation about the direction of the magnetic field, the angular velocity 

being given by w = ^- — . Langevin has also pointed out that the 

size and form of the electronic orbit remain unaffected by the magnetic 
field. Ehrenfest's hypotiiesis asserts that if the magnetic field be 
established slowly the energy of the electron in its orbital motion and 
the frequency ot its revolution in the orbit may be changed, but the 
nuviber of quanta defining its energy undergoes no modification. With 
the adoption of these principles it is an easy matter to show that when 
we quantise the angular momentum about the direction of the magnetic 
field the normal Zeeman components are exactly the same as those 
provided by the older classical theory of Lorentz. The singular beauty 
and simplicity of this method of explaining the normal Zeeman effect 
constitute one of the finest achievements placed to the credit of the 
quantum theory. 

Efforts to explain the abnormal Zeeman effect have not as yet met 
with the same success. Among the contributions made to this subject 
perhaps that of Heisenberg ''* is the most stimulating and suggestive. 
In addition to offering an explanation of the abnormal Zeeman effect 
it constitutes an attempt to account for the doublet and triplet structure 
of series spectra. 

Taking for example the case of an alkali element, Heisenberg 
postulates that through magnetic coupling a movement of rotation 
•witiiin an atom of these elements involves simultaneously the valency 
electron and the core of the atom as well. According to the theory it 
is supposed that in the various stationary states there is a partition 
of the angular momentum between the two, one-half an azimuthal 
quantum being assigned to the core and k-^ azimuthal quanta to the 
electron. The author supposes further that through space quantisation 
the two axes of rotation are in the same direction, and that the rotation 
of the core and that of the electron may take place either in the same 
sense or in opposite senses. As far as the radial quanta for the 
electronic orbits are concerned, it is assumed that they are given by 
n'-f--^ where n' has integral values. This device leads to the result 
that the total quantum number characterising the orbit of the electron 
is an integer n that is equal to the sum k + n' . In this way the author 
is enabled, at the same time, to characterise the spectral terms in the 
Eydberg series formulae by integral quantum numbers. 

This scheme, it will be noted, provides for the binding of the valency 
electron in one or other of two energy levels and reduces the frequency 
difference characterising the members of the doublet series of the spectra 
of the alkali elements to a manifestation of what is practically a Zeeman 
effect produced by an internal atomic magnetic field. To account for 
the triplet structure of series spectra such as we obtain with the 
alkaline earth elements, Heisenberg supposes the magnetic coupling 

*» Heisenbei-R, Zeit. fur Phi/s., No. 8, p. 257 and p. 278, 1922. 


to involve not only the core of the atom but the two outer valency 
electrons as well. It is shown when the theory is extended to take 
account of an external magnetic field in addition to the internal one, 
that the Zeeman separations of the magnetic components of doublet 
and triplet lines are in exact agreement with the laws formulated by 
Preston and Runge. 

When the external magnetic field is high compared with the internal 
one, the theory shows that for doublets and triplets the final result is 
a normal Zeeman triplet in complete accordance with the observations 
of Paschen and Back.^" 

To illustrate the validity of the theory Heisenberg used his formulae 
to evaluate t'le magnitude of the internal magnetic field of the atoms 
of hthium, and found that it led to a value of 32cm-' for the frequency 
difference characterising the doublets of the second subordinate series 
in the spectrum of this element. As the experimental value found by 
Kent^" is 0.34cm~', it will be seen that the agreement is good. 

Again, in connection with the matter of triplet series the theory 
shows that in the case of the p terms the ratio of the triplet frequency 
differences should be as 2:1, for the d terms it should be as 3:2, and 
for the / terms as 4:3. These deductions find ample verification in the 
measurements made on the frequency differences of triplet series in the 
spectra of such elements as magnesium, calcium, strontium, barium, 
zinc and cadmium. 

To say the least, the theory outlined above is extremely suggestive. 
It leads, however, to rather surprising results. If we are to account 
for doublet separations generally as being due to Zeeman separations 
produced by intra-atomic magnetic fields, it follows that with some 
atoms these must be exceedingly high. Taking the doublet separations 
of the second subordinate series in the spectra" of the alkali elements, we 
find the following values for the internal magnetic fields of the different 
atoms : — 


7,173 Gauss 

366,744 ., 

1,231,945 „ 

5,072,090 „ 

11,826,330 „ 

If it should turn out that magnetic fields so high as those given 
above are present in atoms of elements such as those in the alkali 
group, the results obtained by Wood and EUett would be easily explained. 

Whether the existence of a magnetic coupling between the valency 
electron and the atomic core justifies Heisenberg in adopting the artifice 
of partitioning the quanta of rotation between the electi'on and the 
atomic core is a debatable point. 

It does not appear to be permissible to adopt the value i for the 
azimuthal quantum number in defining the stationary orbits of a heavy 
atom such as that of uranium. In a recent paper by Eosseland," in 

*" Paschen and Back, Ann. der Phi/s., vol. 39, p. 897, 1912; vol. 40, p. 960, 

50 Kent, Ast. Phya. JL, vol. 40, p. 343, 1914. 
*' Rosseland, Nature, March 17," p. 357, 1923. 


. . . . Av, 


0-34 cm-> 


17-18 „ 

Potassium . 

57-71 „ 

Rubidium . 

. 237-6 „ 


. 554-0 „ 


which a suggestion is put forward that the phenomenon of radioactivity 
exhibited by the heavier atoms may be due to some interaction between 
the nuclear and the external electrons in these atoms, he finds that the 
nearest approach of an electron to the nucleus in the atom of uranium 
according to Bohr's scheme of orbits is 16 x 10-'^ cm. If the electronic 
orbit closest to the nucleus in the atom of uranium had i for the value 
of its azimuthal quantum number, it would mean that the shortes: 
distance of approach to the nucleus woulfl be equal to 4 x 10~'' cm. As 
the radius of the nucleus of the atom of uranium has been shown to 
be 6.5xlO~'^ cm. it is evident that such an orbit could not exist. For 
reasons of this character we are practically precluded from assigning 
to k, the azimuthal quantum number, a value less than 1 in defining the 
electronic orbits in atoms. 

In this paper an attempt has been made to outline some of the 
leading features of the quantum theory as it is being used to solve 
the problems of atomic structure as well as of those connected with the 
origin of radiations emitted by atoms. Other illustrations of special 
interest might have been drawn from the treatment of problems that 
have arisen in a study of band spectra*' and of fluorescence pheno- 
mena. °^ The recent work of Cabrera,*'' Epstein,** and Dauvillier,*" on 
paramagnetism, too, has a most interesting connection with the deve- 
lopment of inner systems of electronic orbits in atoms in Bohr's scheme 
of the genesis of atoms. 

I venture to think, however, that the few illustrations presented may 
serve, in a measure, to indicate the power and also the beauty of the 
methods being put forward to elucidate the problem of the origin of 

^- Kratzei', JJie Naturwissenschaftcn, vol. 11, Heft 27, p. 577, 1923. 
*3 Franck and Pringsheim, Die Natiirwisscnschaften, Heft 27, vol. 11, 
Julv 6, p. 559, 1923. 

5< Cabrera, Jl. de Pfiys.. t. 6, p. 443, 1922. 

« Epstein, Science, vol. Ivii., No. 1479, p. 532, 1923. 

•'8 Dauvillier, V.R., June 18, p. 1802, 1923. 





Professoe. F. G. DONNAN, C.B.E., F.R.S., 


It was at the last meeting at Liverpool, in 1896, that I first had the 
honour of attending a gathering of the British Association. On that 
occasion Dr. Ludwig Mond, F.R.S., was President of Section B, and 
I shall never forget the interest and pleasure I felt in listening to the 
Address of that great master of science and scientific method. Little 
did I dream that in 1923 I should have the honour and privilege of 
occupying the Chair of Section B at Liverpool. 

Looking back on the Liverpool Meeting of 1896, one can say now that 
it came at the dawn of a new era in the development of physico-chemical 
science. The X-rays had just been discovered by Eontgen. Perrin 
had proved experimentally (1895) that a negative electric charge was 
associated with the cathode rays and had surmised that these so-called 
' rays ' were constituted by electricity in motion, thus corroborating 
Crookes' brilliant views of a decade earlier and demonstrating that 
Lenard was wrong. Sir J. J. Thomson had just begun that splendid 
series of researches which resulted not only in the complete elucidation 
of the nature of the cathode 'rays,' but also in the discovei'y of the 
negative electron as a constant, universal, and fundamental constituent 
of all matter. 

The discovery of the chemically inert elementary gases by Rayleigh 
and Ramsay had l)egiin In 1^94, and the series of investigations wliich 
finally led to tlie recognition of the radio-active transformations of atoms 
and to the discovery of the nature and constitution of the atom itself, 
were just beginning. During the last twenty-fave years the influence 
of these discoveries on chemical science has been enormous. There 
has come about a fresh reunion of physics and chemistry, somewhat 
analogous to that which occuiTed in the days of VoUa and Davy. During 
the two decades preceding 1896, physical science had been largely con- 
cerned with the phenomena of the ' ether, ' with electric and magnetic 
fields, electromagnetic waves, and the identification of light and other 


forms of radiant energy as electromagnetic phenomena. Now that the 
physicists have brought physical science back to the close and intimate 
study of matter, physics and chemistry have come together again, and 
the old and homogeneous science of ' natural philosophy ' has been 
reconstituted. It is time that the walls which divide onr chemical and 
physical laboratories were broken down, and that the young men and 
women who come to our Universities to study physics or chemistry, 
should study the facts and principles of a fundamental science which 
includes both. 

Since the last meeting of our Section a number of eminent men 
of science have passed away. It is with great sorrow that I record the 
deaths of Professor Sir James Dewar, F.R.S., in our own country, and 
of Professors E. Beckmann, J. P. Kuenen, G. Lemoine, L. Vignon, 
and J. D. van der Waals on the Continent. Limits of time and space 
forbid me to attempt here any account of the great services to science 
rendered by these eminent men. As the successor of Tyndall, Sir 
James Dewar worked for over forty years at the Royal Institution, and 
by his investigations on the liquefaction of gases and the physical and 
chemicial behaviour of substances at low temperatures, upheld the 
famous ti'adition of the Royal Institution as a home of pioneer i-esearch 
in science. Beckmann 's name is well known for his researches on the 
effect of dissolved substances on the boiling- and freezing-points of 
solvents, and for the convenient form which he gave to the ' variable 
zero ' thermometer. He also devised useful and convenient forms of 
apparatus required in spectroscopic work. Lemoine was one of the 
pioneers in the study of chemical reaction velocities and equilibria in 
France, whilst Vignon was well known for his researches in organic 
chemistry. Kuenen was at one time Professor of Physics at Dundee, 
although at the time of his death he had been for many years one of 
the Professors of Physics at Leiden. He was particularly noted for 
his investigations on the equilibria occurring in the evaporation and 
condensation of liquid mixtures. His death at a comparatively early 
age is a very heavy loss to science in general, and to Holland in 
particular. In van der Waals there passes away one of the very greatest 
men of science. He was one of that group of Dutch men of science, 
including Cohen, Lorentz, Kamerlingh Onnes, van't Hoff, Roozeboom, 
Schreinemakers, and Zeeman, who have made Holland so famous as a 
centre of physical and chemical research during the last thirty or forty 
years. Van der "Waals was the great mathematical and physical inter- 
preter of the work begun by Thomas Andrews. 

In recent years a great deal of attention has been paid by chemists, 
physicists and physiologists to the phenomena which occur at the 
surfaces or interfaces which separate different sorts of matter in bulk. 
During the last quarter of the nineteenth century, both J. W^illard Gibbs 
and J. J. Thomson had shown clearly, though in different ways, the 
peculiar nature of these interfacial or transitional layers. It was 
evident that things could happen in these regions which did not occur 
in the more homogeneous and uniform regions well inside the volume 
of matter in bulk. Such happenings might, if they could be investi- 
gated, reveal molecular or atomic peculiarities which would be undetect- 


able in llie jostling throng of individuals inside. A surface or surface 
layer represents a soi-t of thin cross section which can be probed and 
examined much more readily than any part of the inside bulk. It is 
indeed only within comparatively recent years that the X-rays have 
provided a sufficiently fine probe for examining this bulk in the case 
of crystalline matter. 

The living organisms of plants and animals are full of surfaces and 
membranes. What can happen at surfaces is therefore a matter of great 
importance for the science of living things. We are bound to hold as 
long as possible to the assumption that the physico-chemical manifes- 
tations of life can be explained in terms of the potentialities of action 
inherent in electrons, atoms, and molecules. The drilled and disciplined 
soldiers of an army behave very differently from an undisciplined and 
disordered mob of the same men. Thus the modes of action 
of ordered arrays and marshallings of atoms and molecules are 
of extreme interest, since such modes of action will constitute pheno- 
mena non-existent in a disordered multitude of the same atoms and 
molecules with exactly the same individual powers and potentialities 
These phenomena may be intimately connected with the phenomena of 
living matter, and as the latter evidently require the existence of surfaces 
and membranes, the idea naturally suggests itself that the special array- 
ing or ordering of individuals occurs at, and may start from, such 

An essential characteristic of this ordering or arraying may consist 
in special orievtation. In the chemical and physical actions occurring 
in a volume of liquid whose bulk is large compared with its surface, 
the molecules or atoms probably move towards each other with every 
sort of orientation, no special type being privileged or distinguished. 
Should, however, some special orientation be characteristic of interfaces, 
then it is clear that such interfaces will exhibit new phenomena due 
to this special sort of arraying. Moreover, if we are dealing with 
molecules which are ionised into electrically polar constituents, or which, 
if not actually dissociated, can be treated as electrically bi-polar, it 
follows that, if orientation occurs at interfaces and surfaces, then 
electrical double layers and electrical potential differences may be set 
up at such boundaries. 

In the theories of Laplace, Gauss, and Poisson the field of force 
surrounding an attracting element or molecule was regarded as essentially 
uniform in its spatial relations, i.e. the equipotential surfaces were 
regarded as concentric spheres with the molecule as a small element at 
the centre. The only way in which the molecule could show its 
character was in affecting the intensity of this central force at a given 
distance and the rate at which the force falls off with increasing distance. 
The molecules were thought of as possessing what one might call a 
very 'rounded and somewhat monotonous ' physical ' personality or 
character as regards their fields of force. In recent years our views 
on such matters have undergone a somewhat radical transformation- 
The field of force surrounding a molecule may in reality be very 
'irregular,' and may be specially localised around certain active or 
' polar ' groups Its region of sensible magnitude may be very variable 


and relatively small compared with molecular dimensions. The chemical 
constitution of the molecule is now regarded as determining the varying 
nature of the field of force surrounding it, so that parts of the molecule 
possessing high ' residual chemical affinity ' give rise to specially power- 
ful regions of force. In this way the older ' physical ' theories of 
cohesion according to central forces with uniform orientation have been 
to some extent replaced, or at all events supplemented, by ' chemical ' 
theories according to which the attractive force-fields are highly 
localised round active chemical groups and atoms, are relatively minute 
in range, and can be saturated or ' neutralised ' by the atoms or groups 
of neighbouring or juxtaposed molecules. 

Dr. W. B. Hardy has been the chief pioneer in the development 
of these newer theories, having been led thereto by his researches on 
surface tension, surface films, composite liquid surfaces and static fric- 
tion and lubrication. As the matter is one of great importance, I shall 
take the liberty of giving two quotations from Hardy's scientific papers. 

' The corpuscular theory of matter traces all material forces to the 
attraction or repulsion of foci of strain of two opposite types. All 
systems of these foci which have been considered would possess an 
unsymmetrical stray field — equipotential surfaces would not be disposed 
about the system in concentric shells. If the stray field of a molecule, 
that is of a complex of these atomic systems, be unsymmetrical, the 
surface layer of fluids and solids, which are close-packed states of matter, 
must differ from the interior mass in the orientation of the axes of the 
fields with respect to the normal to the surface, and so form a skin 
on the surface of a pure substance having all the molecules oriented 
in the same way instead of purely in random ways. The result would 
be the polarisation of the surface, and the surface of two different fluids 
would attract or repel one another according to the sign of their surfaces. ' 
(Hardy, 1912.) 

These ideas are even more clearly expressed in the following passage. 
' If the field of force about a molecule be not symmetrical, that is to say, 
if the equipotential surfaces do not form spheres about the centre of 
mass, the arrangement of the molecules of a pure fluid must be different 
at the surface from the purely random distribution which obtains on the 
average in the interior. The inwardly directed attractive force along 
the normal to the surface will orientate the molecules there. The 
surface film must therefore have a characteristic molecular architecture, 
and the condition of minimal potential involves two terms — one relating 
to the variation in density, the other to the orientation of the fields of 
force.' (Hardy, 1913.) 

Hardy thus bases the notion of molecular orientation at the surface 
on the existence of unsymmetrical fields of force surrounding the mole- 
cule; in other words, the parts of the molecule possessing the most 
powerful stray fields will be attracted inwai^ds towards the bulk and 
thus cause a definite orientation of the whole molecule at the surface. 

If Y^ be the surface tension of a liquid A, y^ that of another prac- 
tically immiscible liquid B, and y^p the interfacial tension at the 
interface A/B, then the quantity W =y^-|-y3 — y^j, represents the de- 
crease of fi'ee surface energy, and therefore the maximum work gained, 


when a surface of A is allowed to approach normally and touch a surface 
of B at constant temperature. Comparing different liquids A with water 
as a constant liquid B, TIardy has shown that the quantity W is ex- 
tremely dependent on the chemical constitution of A, and is especially 
high when A contains the atomic groups characteristic of alcohols, acids, 
and esters. Thus, for such saturated substances as octane, cyclo- 
hexane, CS, and CCI.1, the values of W at ordinary room temperature 
lie between 21 and 24. Compare with these values the following : — 

(a) Introduction of a hydroxyl group : — 

Octyl Alcoliol '. . . .46 

Cyclohexanol .... 51.4 

{b) Introduction of a carljoxyl group : — 

?j— Caprylic acid . . . 46.4 

Oleic acid .... 44.7 

The natural inference from results such as these is that the 
cohesional forces are essentially chemical in origin and that they depend 
in large measure on the presence of ' active ' atoms or groups of atoms, 
namely those possessing strong fields of ' residual chemical affinity ' ; 
in other words, powerful and highly localised stray fields of electrical 
or electromagnetic force (or of both types). The existence of such atoms 
or atomic groups is strong presumptive evidence of the unsymmetrical 
fields of force postulated by Hardy and therefore of the molecular orienta- 
tion at surfaces. 

The conclusions drawn by Hardy have been amply confirmed by 
W. D. Harkins, and his collaborators, who in a long series of accurate 
measurements of surface and interfacial tensions have found that in 
the case of very many organic liquids the ' adhesional work ' towards 
water is greatly increased by the presence of oxygen atoms (as in 
alcohols, acids, and aldehydes). They find that the very symmetrical 
halogen derivatives CCI4 and C2H4Br2 (which possess specially high 
values for their own cohesional work) give markedly low values for 
their adhesional work towards water, and that in the case of unsymme- 
trical molecules, the adhesional work towards water is determined by 
the presence of certain active atoms or atomic groups. 

In his work on static friction and lubrication. Hardy has found 
that the influence of chemical constitution and the effects of active 
atomic groups are very pronounced. This, compMrmg aliphatic or open 
chain compounds, the co-efficient of static friction falls (and the lubri- 
cating power increases) as we pass through the series hydrocarbon — 
alcohol — acid. The corresponding ester is in this case a much worse 
lubricant than the related acid or alcohol. These results suggest, as 
Hardy has indicated, that friction is caused by the molecular cohesion 
of surfaces, and that in the action of such lubricants the molecules are 
oriented with their long axes normal to the surface, whereby the active 
atomic groups play an im]3ortant part in ' taking up ' or saturating a 
portion of the stray force-fields of the molecules of the solid surfaces, 
and in orienting and anchoring the lubricant molecules to these surfaces. 
Many facts lend strong support to Hardy's views. Thus it is true, 
I believe, that the addition of aliphatic esters improves the lubricating 

1923 o 


value of hydrocarbon oils, whilst H. Wells and W. Southcomb have 
demonstrated the marked improvement due to a small addition of a 
fatty acid. In this connection it is interesting to note that W. E. Garner 
and S. S. Bhatnagar have recently shown in my laboratory that the 
interfacial tension between mercury and B.P. paraf&n oil is markedly 
lowered by small additions of oleic acid. The oleic acid molecules are 
therefore absorbed or concentrated at the mercury-oil interface, an 
action which may well be due in part to the fixation and orientation of 
these molecules at the metal-oil interface. 

This question of the orientation of molecules at the surfaces of 
liquids has been greatly extended in recent years by a detailed study of 
the extremely thin and invisible films formed by the primary spreading 
of oily substances on the surface of water. In a continuation and 
development of the work of Miss Pockels, the late Lord Eayleigh showed 
many years ago that when olive oil forms one of these invisible films 
on water, there is no fall in surface tension until the surface concen- 
tration reaches a certain very small value. He made the highly interest- 
ing and important suggestion that this concentration marks the point 
where there is formed a continuous layer just one molecule thick. In 
the case of olive oil, he found this critical thickness to be lO"' cm., 
and concluded that this number represented the order of magnitude of 
the diameter of a molecule of the oil. Increase in surface concentration 
beyond this point causes the sm'face tension to fall, until a second point 
is reached, after which no further fall in surface tension occurs. Lord 
Eayleigh assumed that at the second point a layer two molecules thick 
is formed. This pioneer work of Lord Eayleigh was repeated and 
extended by H. Devaux and A. Marcelin, who showed the correctness of 
his first suggestion, namely that the primary film consists of a 
tmimolecidar layer. It appears, however, that the fall in surface 
tension which he ascribed to the building up of a bimolecular layer, must 
be ascribed to the closer packing of the molecules of the unimolecular 
layer, and that the second point occurs when these molecules are packed 
as tightly as possible- 

Instead of varying the surface concentration by adding more and 
more of the oily substance to a definite surface, we may attain the same 
end by means of a moving boundary and a variable surface, and study 
the relation between the force of surface-compression (difference between 
the surface tension of pure water and that of the contaminated surface) 
and the surface concentration. This method was greatly developed by 
Devaux. Although these researches had firmly established the theory 
of the formation of a unimolecular surface layer and therefore of the 
existence of a veiv ' tivo diviensional ' phase of matter, we owe it to 
I. Langmuir to have made a very important advance by connecting this 
conception with the ideas of chemically active groups and molecular 
orientation. Influenced, no doubt, by the ideas of Hardy, Langmuir 
reasoned that the formation of these primary unimolecular films must 
be due to the presence of active groups in the molecules, which are 
attracted inwards towards the water and thus cause the long open chain 
molecules of the fatty acids to be oriented on the water surface with 
their long hydrocarbon axes vertical and side by side. 



"Working by means of the method of Devaux, Langmuir put these 
ideas to the test of experiment, and determined the internal molecular 
dimensions of a unimolecular layer. The following is an excerpt 
from the results which he published in 1917: — 


Cross Section 


(sq. cms.) 




Length per 
C atom 


Palmitic Acid 
Stearic Acid . 
Cerotic Acid . 

22 X 10-16 


31 Ox 10-8 


It is at once evident that these results agree in a .wonderful manner 
both with the idea of a unimolecular layer and with that of molecular 
oi-ientation . The molecular cross section is practically constant, as we 
should expect, since it must represent the cross section either of a 
carboxyl or CH3 group. Since the molecular length is determined from 
the thickness of the layer, and is found to be five or six times the value 
O'f \/s (molecular ' thickness '), we perceive here the first actual experi- 
mental proof of the theory of molecular orientation. Another fact of great 
significance emerges from these results. If we calculate the average 
distance between two adjacent carbon atoms in the three acids, we 
obtain a value of 1.4 x 10"' cm. Now this distance must be of the order 
of magnitude of the distance between the centres of the carbon atoms 
in the crystal structure of a diamond. This latter distance is known to 
be 1.52x10"^ cm. The agreement is striking. 

These regularly oriented and unimolecular surface films on water 
have been recently investigated in a very detailed and careful manner 
by N. K. Adam, who has improved the method employed by Devaux and 
Langmuir. From a closer analysis of the relationship between the 
force of surface compression and the surface concentration (expressed 
as area occupied per molecule) he has shown that a distinction must be 
made between the close packing of the polar or active end groups (head 
groups) of the molecules and the subsequent close packing of the 
hydrocarbon chains. The following table contains a few of Adam's 
results for the higher aliphatic acids : — 

No. of 
C atoms 

Cross Section (sq. cms.) 







Myristic Acid 
Pentadecvlic Acid . 
Stearic Acid . 
Behenic Acid 





21 1 


Although these results must be considered as more accurate- and 
detailed than those of Langmuir, they provide an ample confirmation 

o 2 


of the theory of unimolecular films of juxtaposed and oriented molecules, 
[f we calculate the average distance between two carbon atoms for the 
four acids, we obtain the following results: — 

Distance|^(cms.)X 10'^ 
Myristic Acid .... 1'6 

Pentadecylic Acid .... 1'6 
Stearic Acid .... 1'5 

Behenic Acid .... V5 

As pointed out before, these values doi not deviate much fro'm the 
value for the distance between the carbon atom centres in the diamond 
(1.52x10"' cm.). Too much stress cannot, however, be laid on this 
point, since in calculating the lengths oi the oriented carbon chains an 
assumption has to' be made regarding the density of the film, because 
only its area and mass are given directly by experiment. 

Concerning this point some very interesting results have been 
recently obtained in Sir William Bragg's laboratory by Dr. A. Miiller. 
In these experiments layers of crystallised fatty acids on glass plates 
have been examined by an X-ray photogi-aphic method. From these 
results it appears that the unit cell is a long prism, the cross section of 
which remains constant for the substances investigated, whilst the 
length of the prism increases linearly with the number oi carbon atoms 
in the molecule. The increase in length of the unit prism per carbon 
atom in the molecule is found tO' be 2.0xlO~*cm. Since it appears 
likely that there are two molecules arranged along the long axis of each 
unit cell (prism), it would follow that the increase in the length of the 
molecule per carbon atom added is 1.0x10"* cm. Comparing this result 
with the value for the distance between the carbon centres in the 
diamond lattice, it would appear that the carbon atoms in the long 
hydrocai'bon chains of the higher saturated fatty acids are arranged in 
a zig-zag, or more probably in a spiral or helix. If this be the case, 
the closer packing or compression O'f the juxtaposed molecules in the 
unimolecular films, as revealed in the investigations of Devaux, Lang- 
muir, and Adam, may be to some extent explained by the straightening 
out of these zig-zags, or perhaps by the ' elastic compression ' of the 

As pointed out by Langmuir, the question of the formation of uni- 
molecular surface films can be attacked in a different manner. It is 
known that gases or vapours can be condensed or adsorbed by solid and 
liquid surfaces. The question then arises, does the formation of 
primary unimolecular films ever occur in such cases ? It will be recol- 
lected that Hardy made the suggestion that the formation O'f the 
primary unimolecular film in the spreading of oily substances on water 
might he due to adsorption from the vapour. In order to examine this 
question, Mr. T. Iredale has recently measui'ed in my laboratoiy the 
fall in the surface tension of mercury caused by exposing a fresh mercury 
surface tO' vapoui-s of increasing partial pressure. The excess surface 
concentration q of the adsorbed vapour can then be calculated by means 
of Gibbs' formula 

g= _p_l 



where Y=sui-face tension, and p and /; denote llic density and partial 
pressure of ttie vapour respectively. \\'orking with the vapour of methyl 
acetate, Iredale found in this way that at a temperature of 26° C. and 
a partial pressure of 62 mm. of mercury, g=4.5 x 10"' grm. per square 
centimetre of surface. From this result we can readily calculate that 
there are 0.37x10'-' molecules of methyl acetate adsorhed per square cm., 
and that the area per molecule is 27x10"'° sq. cm. As under the condi- 
tions corresponding to this calculation the molecular surface layer was; 
probably not quite saturated (in the unimolecular sense), we may expect 
the value found to be of the same order of magnitude })ut somewhat 
gi-eater tlian the values found by Adam for the cross section of the head 
group of the higher saturatexl iatty acids (25 x 10 -"-) and of tlie esters 
(22x10-" for ethyl palmitato and ethyl l)ehenate). We may, therefore, 
say that Iredale's results appear to indicate tiie foa'mation of a priniaiy 
unimolecular layer built up by adsorption from the vapour phase. 

Langmuir has measured the adsorption of a number of gases a>- 
low temperatures and pressures on measured surfaces of mica and glass, 
and has an-ived at the conclusion that the maximum quantities adsorbed 
are always somewhat less than the amounts to be expected m unimole- 
cular surface layer. E. K. Carver, who has measured the adsorption of 
toluene vapour on known glass surfaces, has arrived at a similar con- 
clusion. The view that the niaximuin adsorption from the gas phase 
cannot exceed a unimolecular layer has, however, been much criticised. 
Thus, for example, M. E. Evans and H. J. George, on the basis of 
their own measurements on the adsorption of gases on a known surface 
of glass wool, combined with, the data obtained by Miilfarth, have con- 
cluded that the adsorption layer may be several (and in some cases-. 
many) m_olecules thick. It may well be that the formation of a uni- 
molecular ' saturation ' layer only occurs in the case of molecules with: 
relatively very active atoms or atomic, whose strong localised 
fields of force suffice to produce powerful attraction and orientation: 
and an almost complete saturation of the ' stray ' fields of the surface 
molecules of the adsorbing surface, especially when the thermal tem- 
perature agitation is sufficiently small. In the case of molecules with 
weaker or more symmetrical fields of force, there may be relatively 
little orientation, and an extension of the attraction field of the adsor- 
bent thi-ough layers of the adsorbate many molecules thick. It would 
be rash to theorise too much on this subject until more data are accu- 
mulated, but it may be pointed out tliat in his investigations on the 
spreading of surface films and on the theory of lubrication, Hai-dy has 
been led to distinguish between primary spreading (primary unimole- 
cular films) and secondary spreading (secondary relatively thick sheets). 

Let us now consider another type of formation of surface layers at 
the surfaces of liquids — namely, the case where a substance dissolved 
in a hquid concentrates preferentially at the liquid-air or liquid-vapour 
interface. Gibbs, and later J. J. Thomson, have shown that if a 
dissolved substance (in relatively dilute solution) lowers the surface 
tension, it will concentrate at the surface. That such a phenomenon 
actually occurs has been qualitatively demonstrated in the experiments 
of D. H. Hall, J. von Zawidski, and P. B. Kenrick and 0. Benson, 

ET d log a 

IS (or for so-called ' ideal ' 

solutions) we 

1 dy __ _ c d-x_ 

RT d log c ET dc 


by the analysis of foams and froths. In 1908 S. E. Milner used 
the same method in the case of aqueous solutions of sodium oleate, 
and arrived at a mean value of 1.2x10"'" gram mols. excess concentra- 
tion per sq. cm. of surface. Now, in the case of dilute solution, we 
can calculate q, the amount concentrated or ' adsorbed ' in the sm-face 
per sq. cm. (excess surface concentration) by making use of the equa- 
tion of Gibbs, 

_ dy 

where Y = surface tension and A'=chemical potential of the adsorbed 
substance in the bulk of the solution. Writing p- = RT log a + k, 
where a = ' activity ' of the solute, and fc is a quantity dependent only 
on the temperature and nature of the solute and solvent, dj«=E T d 
log a, and so Gibbs' equation can be written in the form 

If for very dilute solutions 
put a = c, we can write 

In this v/ay Milner has calculated from Whatmough's data for aqueous 
solutions of acetic acid that the 'saturation' value of q is 3.3x10""'° 
mols. per sq. cm., from which it follows that the area per molecule in 
the surface is SOxlO"'*^ sq. cm. In a similar manner, Langmuir has 
calculated from B. de Szyszkowski's data for aqueous solutions of 
propionic, butyric, valeric, and caproic acids that the surface area per 
molecule adsorbed in the saturated layer is equal to 31x10"" sq. cm., 
whilst Harkins has arrived from his own measurements for butyric 
acid at the value 36x10"'^ sq. cm. 

In 1911 Dr. J. T. Barker and myself made a direct determination 
of q for a solution of nonylic acid in water. For a practically saturated 
surface layer it was found that q was about 1.0x10"' gi-m. per sq. cm., 
or 3.1x10" molecules per sq. cm. From this result it follows that 
the surface area per molecule is 26x10"'* sq. cm. 

If we consider these various values, it will be at once evident that 
they are not very different from the values found by Langmuir and 
by Adam for the oriented unimolecular layers of practically insoluble 
fatty acids resting on the surface of water. That in the present case 
some of the values are larger might easily be explained on the ground 
that these adsorption layers are partially, or completely, in the state of 
'surface vapours.' For Adam and Marcelin have recently made the 
important discovery that the unimolecular surface films investigated 
by them may pass rapidly on increase of temperature from the state 
of ' solid ' or ' liquid ' surface films to the state of ' vaporised ' surface 
films, in which the juxtaposed molecules become detached from each 
other and move about with a Brownian or quasi-molecular motion. 



probably communicaied to them by the thermal agitation of Iho water 
molecules to which they are attached. 

It is, indeed, highly probable that the molecules which are con- 
centrated in the surface from the state of solution in the liquid phase 
are not in quite the same situation as the molecules of practically 
insoluble substances which are placed on the surface. In the former 
case the molecules are still ' dissolved, ' so that they will be more 
subject to thermal agitation and less able to form a juxtaposed uni- 
molecular layer. They may also be 'hydrated.' The difference 
between the two cases is rendered very evident from the fact that in 
the production of surface layers from dissolved molecules of the fatty 
acids (and other ' surface active ' substances) there is a vei-y marked 
fall of surface tension, whilst the uncompressed unimolecular surface 
films placed on the surface from outside do not affect the surface ten- 
sion of the water. Thus the molecules of the surface-active substance 
in the former case are in much closer relation to the solvent molecules, 
and are in kinetic equilibi'ium with the molecules of both solvent and 
solute in the bulk of the liquid. Nevertheless, the agreement as 
regards order of magnitude in the values of the surface area per mole- 
cule in the two types of case is certainly very suggestive and significant. 
Moreover, the experiments of Mr. Tredale show that molecules which 
are adsorbed on the surface fi'om the vapour phase lower the surface 
tension, and are therefore from this point of view comparable with 
molecules concentrated in the surface from the bulk of the liquid phase. 

The question as to whether the simplified form of Gibbs' equation 
yields a sufficiently accurate value for the excess surface concentration 
can scarcely be decided without more experimental data. In the 
experiments made by Dr. Barker and myself, the values calculated 
from the surface tension- concentration curve were 1.3x10"' and 
0.6xl0~''grm. per sq. cm., according as the value of the van't Hoff 
factor i for the very dilute solutions of nonylic acid was taken as 1 or 2 
■ respectively ; whilst the corresponding directly determined value was 
about 1.0x10-' grm. per sq. cm. This discrepancy was probably well 
within the experimental error of our measurements. 

Let me now direct your attention to another very interesting 
phenomenon relating to the surfaces of liquids and solutions — namely, 
the existence of an electrical potential gradient or potential difference 
in the surface layer. These interfacial potential differences are of great 
importance, and play a fundamental role in determining the stability or 
instability of many colloidal states of matter. The Mquid-gas interface 
offers the simplest case of such interfaces, and so the investigation of 
the potential differences which may exist at this interface is a matter 
of fundamental interest. In 1896 F. B. Kenrick developed, on the 
basis of earher experiments of Bichat and Blondlot, an electrometric 
condenser method for the comparative determination of the gas-liquid 
P.D.'s. The results which he obtained show that substances (such as 
the aliphatic alcohols and acids) which concentrate at the surface pro- 
duce a very great change in the surface P.D., whilst highly dissociated 
univalent inorganic salts, such as KCl, do not. The results obtained 
by Kenrick have been much extended by an investigation carried out 



with the same type of apparatus by Professor Thorbergur Thorwaldson 
in my hiboratory. The general result of these experiments can be 
described in the following temis : — 
Consider the sj^'stem : 

Aqueous Solution of KCl 


I Aqueous Solution of KCl 
Air (conc. = c) 

I B 

The positive potential of A will be equal to that of B. If we now 
add to the solution B a small quantity of a substance S (generally a 
non-electrolyte or weak electrolyte) which has a sti'ong tendency to 
concentrate at the air-B interface, it is found that the positive potential 
of A rises markedly above that of B, the value of the quantity, positive 
potential of A minus that of B, varying with the concentration of S in 
the way that is chai-acteristic of adsorption phenomena. What is the 
interpretation of this phenomenon? If we were to assume that there 
was practically no P.D. at the interface A-air, it would follow that the 
effect of S is to make the positive potential of the bulk of B markedly 
below that of the air. The same result would follow if we were to 
assume that at the interface A-air there exists a P.D. which makes the 
positive potential of the bulk of A markedly below that of the air out- 
side. Both these assumptions would lead to the conclusion that in the 
surface layer of the solution at the A-air interface there must exist either 
no electrical double layer, or else one with its positive half oriented 
towards the air side. Now Quincke has shown that a bubble of air 
in water placed in an electrical potential gradient travels towards the 
anode — i.e. the bubble behaves as if it were negatively charged. From 
this it would follow that the P.D. at the air-water interface is such 
that the negative half lies towards the air side. As an electrolyte such 
as KCl is negatively adsorbed at an air-liquid surface, it is probable 
that a P.D. of the character indicated by Quincke's experiment exists 
at the A-air interface. If we accept this conclusion, it follows that the 
effect of S is markedly to reduce this P.D. (or to reverse it). Now the 
P.D. at the air-water interface is probably due to the existence of a 
double layer containing hydroxyl ions on the outside and hydrogen ions 
on the inside, or to oriented water molecules regarded as electrical 
bi-poles. If S is a non-electrolyte (or a substance which possesses 
little self-ionisation), we can understand why its concentration at the 
surface could result in the reduction of this P.D. 

The experiments of Thorwaldson show that a substance such as 
the hydrochloride of methyl violet has a powerful effect on the P.D. at 
the_ air-water interface. It is probable that in this case the complex 
basic dye cation is drawn into, or ' adsorbed ' in, the outside layer next 
to the air, the result of this being a reduction or possibly reversal of 
the original potential difference. 

Kenrick found that if gases such as hydrogen and coal gas be sub- 
stituted for air, there is no effect on the surface P.D. 

Within the last few years H. A. McTaggart has made a number of 
experiments on the electric cataphoresis of gas bubbles in aqueous solu- 
tions and other liquids. He finds that aliphatic acids and alcohols in 

aqueous solution reduce the surface P.D. and that this effect runs 
parallel with their influence on the surface tension of water. He also 
finds that acids reduce the P.D. These results may be regarded as a 
corroboration of those obtained by Kenrick. McTaggart has found that 
the nitrates of tri- and tetravalent cations have a powerful effect in not 
only reducing but reversing the P.D. {i.e. the bubble becomes posi- 
tively charged). His experiments also show that polyvalent negative 
ions, such as the ferrocyanide ion, act in the opposite direction to the 
polyvalent cations — i.e. they increase the negative charge on the bubble 
or diminish a previously existing positive one. These results are of 
great interest, inasmuch as they show the powerful effects produced by 
polyvalent ions on the P.D. existing in the surface layer of an aqueous 
solution. As wo shall see presently, very similar results have been 
obtained at liquid-liquid and solid-Uquid interfaces. But it is of gi-eat 
importance to know what happens at the air-liquid interface, since we 
can largely discount the chemical and physical influence of the gas 

Although the electrometric method employed by Kenrick and Tlior- 
waldson only gives comparative results (since two mterfaces must always 
be simultaneously used), whilst the cataphoresis methcx:! gives results 
for a single interface, it is necessary to observe that the electrometric 
method measures the total fall of potential from the bulk of one phase 
to the bulk of another. The cataphoresis method measures what 
Freundlich has called the ' electrokinetic ' P.D. — that is to say, the 
potential drop between the limiting surface of the ' fixed ' part of the 
double layer and the rest of the liquid. The two values need not neces- 
sarily coincide. 

When liquids are sprayed or splashed, or when gases are bubbled 
through liquids, it is known that the gas often acquires an electrical 
charge, whilst the liquid acquires an opposite one (so-called ' waterfall ' 
electrification). Since the pioneer work of Elster, Lenard, J. J. 
Thomson, Kelvin, Maclean, and Gait, very many investigators have 
dealt with this subject (Eve, Christiansen, Bloch, de Broglie, Zwaarde- 
makers, Coehn, &c.). Originally, Lenard thought that the effect was 
due to a ' contact electrical ' action between the gas and the liquid, 
whilst J. J. Thomson was inclined to ascribe it to a sort of partial 
chemical action between them. It is known that there are produced 
in the air or gas relatively slow-moving carriers, both positive and 
negative. Lenard has quite recently changed his views, and ascribes 
the origin of these carriers to the tearing off of very small portions of 
the outside layer of the electrical double layer existing in the surface 
of the liquid. It may be mentioned that Kenrick, Thorwaldson, and 
McTaggart came to the conclusion that the surface P.D.'s measured 
by them were not connected, or at all events not connected in any simple 
manner, with the phenomena of waterfall electrification. 

We may say, therefoi'e, that if there be a relation between these 
two types of phenomena, it is a complicated and still largely obscure one. 

The subjects which I have been discussing have an interesting bearing 
on the formation and stability of foams and froths. If air be violently 
churned up with water, only comparatively large bubbles are produced. 


and these quickly rise to the surface and burst. If now a very small 
quantity of a substance which concentrates at the air-water interface 
be added, an almost milk-white ' air emulsion ' of small bubbles is 
produced, which rise to the surface and produce a relatively durable 
froth. These phenomena were discussed by the late Lord Eayleigh 
in a veiy interesting Royal Institution lecture on 'Foam.' It is clear 
that the diminution in interfacial tension facilitates the subdivision or 
dispersal of the air. The existence of the surface layer will also confer 
a certain amount of stability on the resultant froth, since it will give 
rise to forces which resist the thinning of a bubble wall. Any sudden 
increase in the surface will produce a momentary diminution in 
the concentration or ' thickness ' of the surface layer, and hence 
a rise in surface tension, which will persist until the normal thick- 
ness or concentration is readjusted by diffusion of molecules from 
the inside volume — a process which in very dilute solution will occupy 
a perceptible time. That this explanation (due to the late Lord 
Eayleigh) is the correct one can be seen from the fact that very 
often stronger solutions of the same surface-active substance scarcely 
foam at all. In this case the readjustment of the equilibrium thickness 
or concentration of the surface layer occurs with such rapidity (owing 
to the greater concentration of the molecules in the inside volume) that 
practically no rise in surface tension, and hence no counteracting force, 
comes into play. These effects will be the more pronounced — other 
things being equal — the greater the mass and hence the smaller the 
motion of the solute units, as in the case of large molecules or colloidal 
micelles. It is probable, however, that the explanation of the stability 
of very durable forms, as, for example, those produced by the sea at 
the sea coast, by beer and stout, by aqueous solutions of soap or saponin, 
&c., is often more complex, and that we must seek it in the forma- 
tion of very viscous or semi-rigid or gel-like membranes at the interface. 
Moreover, small solid particles may contribute to the stabilisation of a 
froth, as in the case of the ' mineralised froths ' of the ore flotation 
process ; and the preferential aggregation of small particles in the inter- 
face between two phases has been demonstrated in the experiments of 
W. Reinders, P. B. Hofmann, and many others. 

Let us now inquire how far the phenomena which we have seen to 
be characteristic of a gas-liquid interface occur also at the interface 
between two immiscible or partially miscible liquids. Many years ago 
it was shown by Gad and by Quincke that a fatty oil (such as olive oil) 
is very readily dispersed in the form of an emulsion by a dilute solution 
of caustic soda. Some experiments which I once made showed that a 
neutral hydrocarbon oil could be similarly emulsified in a dilute aqueous 
solution of alkali if one of the higher fatty acids was dissolved in it, 
whilst the lower fatty acids do not produce a similar action. It was 
shown that the action runs parallel to the lowering of interfacial tension 
and must be ascribed to the formation of a soap, which lowers the inter- 
facial tension and concentrates at the interface. These phenomena 
have have been further investigated by S. A. Shorter and S. Ellings- 
worth, by H. Hartridge and R. A. Peters, and by others. 

If a substance which is dissolved in one liquid A, and which is 


practically insoluble m another liquid B, is found to have, in very dilute 
solutions, a strong effect in lowering the tension at the interface A-B, 
the following interesting questions arise: — 

(1) What is the amount of the surface concentration or adsorption 
per sq. cm. of interface? 

(2) Can it be calculated by means of the simplified Gibbs equation? 

(3) How does the surface adsorption vary with the concentration? 

(4) Does the ' saturation ' value correspond to the formation of a 
unimolecular layer? 

Some of these questions were experimentally investigated in my 
laboratory by W. C. McC. Lewis. For the liquid A water was chosen, 
and for B a neutral hydrocai-bon oil. Woi-king with sodium glycocholate 
as the surface-active subtance, it was found that the experimentally 
measured surface adsorption q was much greater than that calculated by 
means of the equation 

= -_^ ^ 
^ RT dc' 

For example, a 0.2 per cent, aqueous solution at 16° C. gave a directly 
measured value of g = 5xl0-' grm. per sq. cm., whilst the calculated 
value was 5 x 10~* grm. per sq. cm., practically a hundred times smaller. 
A similar type of discrepancy was found in the cases of Congo Eed and 
methyl orange. If we calculate from the experimentally found surface 
adsorption of sodium glycocholate the value of the surface area per mole- 
cule, we obtain about 0.9 x 10"'^ sq. cm. A similar calculation in 
the case of Congo Eed gives a correspondingly low figure. Now 
if we compare these values with those previously obtained for the air- 
liquid surface, it is clear that in the present case we are not dealing with 
simple unimolecular layers, but with adsorption layers or films many 
molecules thick. On the other hand, if we calculate from Lewis' 
results the surface ai'ea per molecule as deduced from the surface 
tension measurements by the simplified Gibbs formula, we arrive at 
values of the order of 90 x 10"" (sodium glycocholate) and 100 x 10"^" 
(Congo Red). These are values which are consistent with the gradual 
building up of a unimolecular layer (of possibly heavily hydrated mole- 
cules or micelles). It is possible, therefore, that the Gibbs equation 
gives the surface concentration of the primary unimolecular ' two 
dimensional ' surface phase, and that any building up of further con- 
centrations beyond this layer does not affect the surface tension. It is 
true that in the case of substances such as sodium glycocholate, and 
especially Congo Red, in aqueous solution, there is a considerable amount 
of uncertainty as to the nature and molecular weight of these sub- 
stances as they exist, not only in the bulk of the solution, but especially 
in the surface phase. In a later investigation Lewis determined the 
surface adsorption of aniline at the interface mercury-aqueous alcoholic 
solution, and found in this case a very fair agreement between the 
observed and calculated results. This case is more favourable, since 
we can be in little doubt concerning the molecular weight of the solute 
units. The mean observed value for the sm-face adsorption was 


2.7x10"^ grin, per sq. cm. Hence the number of molecules per 
sq. cm. of interface 

= |JxiO-'X6"06X10'' = 0"17X10'\ 

and the surface area per molecule = 58 x 10"^'^ sq. cm. Langmuir's 
calculation from Worley's measurements of the surface tensions of 
aqueous solutions of aniline gives at the air-water surface the value 
34 X 10"'^ sq. cm. for the area per molecule of aniline. We may con- 
clude, therefore, that Lewis' measurements in this case point to the 
building up of a primary unimolecular layer, unaccompanied by any 
further concentration or ' condensation ' of molecules or colloidal 

The relation between surface adsorption and fall of interf acial tension 
at a mercury -water interface was further investigated by W. A. Patrick, 
who concluded that, although there was a con-espondence between the 
two' phenomena, the surface adsorption could not be calculated from 
the simplified Gibbs equation. If we were to accept this conclusion 
as correct, we might find an explanation either in the suggestion made 
above, or in the possible invalidity of conclusions drawn from the use 
of the simplified Gibbs equation ; either because the simplifications intro- 
duced ai'6 not justified, or because the existence of electiical or other 
factors requires an extension or elaboration of the original equation. 
This matter has been discussed by Lewis, by A. "W. Porter, and by 
various investigators of electro-capillary phenomena. 

From very accurate measurements of the interfacial tensions of the 
aqueous solution-mercury interface, W. D. Harkins has calculated (by 
means of the simple Gibbs equation) that when the interface is satu- 
rated as regards butyric acid molecules coming from the aqueous 
solution, the surface area per molecule is 36xlO~" sq. cm. 

Here, again, we see that a calculation by means of the Gibbs equa- 
tion seems to point to the formation of a primary unimolecular layer. 
Experiments similar to those of Lewis have been very recently made by 
E. L. Griffin, who has measured directly the adsorption of soaps from 
aqueous solutions at a mineral oil-water interface. The results obtained 
are as follows : — • 

Average Surface per jNIolecule 

Substance adsorbed 

Sodium Oleate . . . . 48 X 10"'" sq. cm. 

Potassium Steai'ate . . . 27X lO^"' sq. cm. 

Potassium Palmitate • • . 30 X 10~'^ sq. cm. 

These figures are very interesting, for they would appear to indicate 
the formation of unimolecular surface layers. It m.ay be mentioned 
here that T. E. Briggs has investigated the adsoiption of sodium oleate 
at a benzene-water interface, and finds that the amount of soap adsorbed 
at the interface increases rapidly at first with small increases in the 
concentration of the solution, and then remains very nearly constant 
while the concentration of the solution undergoes great increase. This 
is just what one would expect from the building up of a saturated 
surface or surface layer (whether unimolecular or otherwise). 


We have seen that in the case of the air-water surface there exists 
an electrical separation or potential difference in the surface layer, and 
that certain substances can produce pronounced variations, or even 
reversals in sign, of this electrical double layer. It becomes a matter, 
therefore, of great interest to inquire whether similar phenomena occur 
at the interface between two immiscible- liquids, and, if so, to ascertain 
whether such electiical charges or double layers bear any relation to 
the ' stability ' of pure emulsions, or fine dispersions of one liquid in 
another. It is well known that those disperse or finely heterogeneous 
states of matter known as colloidal solutions depend in part for their 
stability on the existence of such electrical potential differences. We 
might expect, therefore, that an investigation of these emulsion systems 
would throw some light on the general theory of what are called ' sus- 
pensoid ' or ' lyophobic ' colloidal states. Investigations with these 
objects in view were carried out some years a,go in my laboratory by 
E. Ellis and F. Fowis. The method employed was to measure directly 
by means of a microscope the motion of minute globules (suspended in 
water) under the influence of a known electric field. This procedure may 
be regarded as an extension and development of the work of Quincke. 
From the measured velocity and potential gradient the interfacial P.D. 
and the electrical charge can be calculated from the theories of Helm- 
holtz. Lamb, and Stokes. The microscopic method has the advantage 
that the P.D. between the aqueous solution and the glass wall (cover 
glass or object glass) can be simultaneously detemiined It is a remark- 
able fact that the P.D. between various types of hydrocarbon oils (puri- 
fied from acid as far as possible) and water was found to be 0.045 — 0.053 
volt, the oil being negative — that is to say, 'the oil droplet moving towards 
the anode. If we compare this with the value recently calculated by 
McTaggart for the P.D. between an air-bubble and water (deduced from 
a precisely similar type of measurement), namely 0.055 volt, we can 
draw the conclusion that the potential difference is due to an electric 
double layer residing in the surface layer of the water. The oil droplet 
moves, therefore, with an attached negative layer or surface sheet, 
probably determined by hydroxy 1 ions, this being balanced by a positive 
layer whose charge is determined by hydrogen ions. If hydrochloric 
acid be added to the water the interface P.D. rapidly falls, and appears 
asymptotically to approach zero. If, on the other hand, caustic potash 
be added, the P.D. at first rises, reaches a maximum at a concentration 
of about one thousandth molar, and then falls with increasing concen- 
tration, but nothing like so sharply as in the case of the acid. Similar 
results hold good for the glass-water interface. From the results 
recently obtained by H. E. Kruyt (by means of the stream method) it 
is probable that at very low concentrations of acid there also occurs 
an initial increase in the interfacial P.D. The influence of salts is 
very remarkable. Thus at low concentrations potassium chloride and 
potassium ferrocyanide increase the P.D., whilst at higher concenti-a- 
tions they reduce it, just as in the case of the acid and the alkali. The 
initial increase caused by potassium ferrocyanide is markedly greater 
than that caused by potassium chloride. The effect of the valency of 
the salt cation is very pronounced. Thus barium chloride at very low 


concentrations probably causes a very small rise of the P.D., but at 
quite low concentrations its effect is to reduce it, and this effect increases 
rapidly with rising concentration, and is much more marked than in 
the case of potassium chloride. The lowering effect of aluminium 
chloride at low concentrations on the P.D. is much more pronounced 
than in the case of barium chloride, and this effect becomes still greater 
with thorium chloride. Both aluminium chloride and thorium chloride 
at low concentrations reverse the sign of the P.D., the oil side of the 
double layer becoming positive. In these cases the positive charge of 
the oil droplet reaches a maximum with increasing concentration of 
the salt, and then appears to fall slowly towards zero. No second 
reversal of sign has ever been observed. So far as the solid-liquid 
interface is concerned, these results have been in general confirmed by 
the electroendosmotic experiments of G. v. Elissafoff (carried out in 
Freundlich's laboratory) and by the stream-potential measurements 
of Kruyt. It may also be remarked that Loeb has recently obtained 
similar results in the case of collodion particles, using the micro- 
cataphoresis method. Perhaps the most remarkable result which has 
emerged from these electrical investigations of oil suspensions is the 
relation between the stability of the emulsion and the potential difference 
of the interfacial double layer. The minute oil globules are in constant 
Brownian motion and must frequently collide. Why do the forces 
of cohesion not produce agglomeration or coalescence (coagulation or 
clearing of the emulsion)? We should expect that under determinate 
conditions a certain fraction of these collisions would give rise to coher- 
ence. Is there any other factor besides orientation of path and kinetic 
energy which affects the probability of coherence following an encounter? 
At distances great in comparison with their own dimensions the electric 
double layers will act practically as closed systems. But when two 
oil drops approach sufficiently near each other the conditions will be 
different, since we must expect a repulsive force when two similarly 
charged outer layers just begin to interpenetrate each other. Hence 
the answer to the question asked above is that the third factor is the 
potential difference or electric density of the interfacial double layer. 
Other things being equal, the probability P of an encounter leading 
to coherence will be a diminishing function of the electric intensity tc 

of the similarly constituted double layers, i.e. j- will be negative. 

Hence of the total number of encounters in a given small period of 
time the number which lead to coherence should be a maximum at the 
point of zero potential difference (iso-electric point of Hardy). 

Now the experiments of Powis brought out the very important fact 
that when the interfacial P.D. (whether positive or negative) is above 
a certain value, which was about 0.03 volt for his conditions, the rate 
of coagulation or coherence of the oil drops is relatively small, but 
rapidly increases when the P.D. falls inside the zone -0.03 to +0.03 
volt. Under definite conditions there exist, therefore, what we may, 
speaking broadly, call a critical potential and a critical potential zone. 
When the P.D. is outside this zone the emulsion is comparatively very 
'stable.' Very small concentrations of electrolytes, which, as we 


liave seen, increase the P.D., increase this stability. As soon as llie 
concentration of any electrolyte is sufficient to bring the P.D. into 
the critical zone, the stability of the emulsion undergoes a sudden and 
very marked decrease, and relatively rapid coagulation occurs. Take, 
for example, the case of thorium chloride. On increasing the concen- 
tration we find that the interfacial P.D. traverses successively the 
following regions: — 

(1) Above the critical value (and negative). 

(2) Inside the critical zone (negative and positive). 

(3) Above the critical value (and positiA^e). 

(4) Below the critical value (and positive). 

In exact correspondence with this series we find that the emulsion 
goes through the following states: — 

(1) Stable (oil particles ' negative '). 

(2) Unstable and flocculating (oil particles negative or positive). 

(3) Stable (oil particles positive). 

(4) Unstable and flocculating (oil particles positive). 

Here we see a very striking analogue and explanation of the pheno- 
mena observed by Joly in studying the effect of aluminium salts on the 
sedimentation of clays, and of the numerous examples of the so-called 
' irregular series ' observed in the fiocculation of suspensoid hydrosols 
by salts with polyvalent cations. 

As Linder and Picton showed, when two suspensoid hydrosols, one 
negative and the other positive, are mixed, then, depending on the 
ratio, a stable hydrosol (either positive or negative) can be obtained. 
In continuation of this work, "W. Biltz demonstrated the existence in 
such cases of a 'zone of coagulation,' i.e. a zone of concentration 
ratios leading to coagulation. A study of the mutual behaviour of a 
negative oil emulsion and the positively charged ferric oxide hydrosol 
provides a complete explanation of this curious phenomenon. When 
increasing amounts of the iron oxide hydrosol are added to the oil 
emulsion it is found that the interfacial P.D. falls to zero, and then 
reverses its sign, becoming increasingly positive — an action which is 
due to the adsorption of the positively charged micelles at the oil-water 
interface. When the P.D. is above a certain value (positive or nega- 
tive) the system is stable. But within the critical zone a rapid and 
relatively complete nmtual coagulation takes place. 

These studies of oil emulsions (and of the glass-water interface), 
by means of the micro-cataphoresis method, have thrown a great deal 
of light on many previously ill-understood points in the theoiy of 
colloids. If, for example, the P.D. between the particles of a suspen- 
soid hydrosol and tlie aqueous fluid is not above the ci"itical potential, 
coagulation will occur. But very small concenti'ations of certain 
electrolytes can raise the P.D. and stabilise the hydrosol. This is the 
explanation of the well-knov/n ' peptising ' action. Higher concentra- 
tions of even the same electrolytes will reduce the P.D. below the 
critical potential, and produce fiocculation. We see also that rapid 
coagulation will occur before the P.D. becomes zero. This was 
])roved for arsenic sulphide hydrosol by Powis. Later experiments 
')f Kruyt have confirmed these conclusions. It is obvious, therefore, 



that coagulation of a lyophobic hydrosol will occur before the iso-electric 
point is reached, and that Hardy's famous rule requires revision. 

The following table contains the concentrations (in millimols per 
litre) of certain electrolytes required to reduce the potential of a certain 
hydrocarbon oil emulsion from its ' natural ' value (against pure water) 
of 0.046 volt to the critical value, 0.03 volt: — 


Eatios of 

KCl . . . 
BaOla . 
AlCls . 
ThCli . 



These results show the enormous influence of the valency of the 
cation in a series of salts with the same univalent anion, and explain 
in a striking manner the analogous effects in the coagulation of lyophobic 
hydrosols. The exact value of the critical potential and the range 
of the critical zone will depend, of course, on the experimental defini- 
tion ol 'rapid coagulatio'U,' and on the concentration, nature, and 
degree of dispersion of the hydrosol. It is not to be supposed, there- 
fore, that these critical values are constants except under very definite 
conditions. The fundamental fact is that under given conditions the 
rate of coagulation of the pai-ticles of an oil suspension or of a lyophobic 
hydrosol undergoes a relatively sudden and very great increase when 
the inter facial P.D. falls below a certain finite value (positive or 

There is not time or space at my disposal to enter into the much 
discussed question as to the inner mechanism of the action whereby 
ions (and electrically charged micelles) set up or vaiy the potential 
difference in the interfacial layer. According to Freundlich's original 
theory we must ascribe an independent effect to each ion, which will 
depend on the sign of its charge, its specific adsorbability, and electro- 
valency and the nature of the already existing double layer. A different 
theory was proposed by Freundlich in order to explain the results 
obtained in the electroendosmotic experiments of Elissafoff. According 
to this point of view, the ' solid ' surface acts chemically (as an acid, 
base, ampholyte, or salt), whereby it may dissociate cfi an ion or ions, 
and itself become an ionised surface. Invading foreign ions may then 
alter this ionisation equilibrium ; or they may simply combine with 
the ionised surface and form neutral insoluble spots (compare the 
views of Freundlich, Gyemant, and Kolthoff). J. N. Mukherjee has 
suggested that ions are attached to the surface by chemical forces, and 
has attempted to work out an electro-kinetic theory of ion adsorption. 
It is probable that surfaces very often do act ionically or chemically, 
and that specific actions of this sort must often be taken into account 
in dealing with the great variety of material presented in the study 
of surface actions. Nevertheless, in the case of the hydrocarbon oil 
'droplets studied by Ellis .and Powis, or the gas-liquid interface studied 


by Kenrick, Thorwaldson, and McTaggart, any specific chemical 
activity or ionisation of the oil or gas would seem improbable. Any 
theory which attempts a general treatment of the problem must be 
prepared to deal with cases such as these. 

Many measurements have been made of tlie potential differences 
between solids and liquids, or between pairs of immiscible (or partly 
miscible) liquids, using electrometric methods. Thus Haber and 
Klemensiewicz determined the potential difference at a glass-water 
solution interface, and found the glass to act like a hydrogen electrode. 
Their results have been recently confirmed by W. S. Hughes. It will 
be at once obvious that these results are not in agi'eement with those 
obtained by cataphoretic and electroendosmotic methods. A somewhat 
similar type of discordance has been observed in the electrometric 
measurements of the potential difference between solid paraffin and an 
aqueous solution made by G. Borelius, and of the P.D.'s between pairs 
of liquids made by E. Beutner, E. Baur, and others. Freundlich and 
Gyemant have drawn attention to the fact that in all such electrometric 
measurements, where in the process of the measurement an electric 
current must pass from one phase to the other, we measure the total 
or ' thei-modynamic ' potential difference between the phases in bulk, 
whereas in determinations by the methods of electroendosmose and cata- 
phoresis, we measure only a portion of this total potential difference. 
These 'electro-kinetic ' P.D.'s, altho'Ugh of fundamental importance in 
relation to the stability of suspensoid (lyophobic) systems, need not, 
and in general will not, coincide in value with the total (thermodynamic) 
potential differences. It will be recollected that I drew attention to a 
quite analogous difference in discussing the measurements of the 
potential differences at gas-water interfaces made by Kenrick and by 

We may illustrate this point by considering the P.D. between two 
immiscible phases, Li and L,, in equilibrium with each other, and 
each of which contains dissolved in it the electrolyte KA. If s denote 
the positive potential of L. above Lj, and P the quantity of electricity 
associated with an ionic gi'am equivalent, then by a virtual variation 
of the equilibrium system it follows that 

((^k)i - (!^k)2 = Fe = ([Xa).2- (t^.v)! 

where the subscripts refer to the cation or anion and to the phases 
Li or L2, and the j«'s denote the chemical potentials per gram equivalent 
(partial equivalent free energies) of the ionic constituents in the bulk of 
the two phases. Whatever may be the ' electro- adsorption ' or ion 
adsorption of K and A at the interface I^i-L,, it is clear that e depends 
only on the ' bulk " values of the respective chemical potentials, which 
likewise determine the surface concentrations. If the phases L, and 
Ijj be. not in equilibrium, then velocity or diffusional terms will enter 
into the equations, and the potential difference will be partly or wholly a 
'diffusional potential.' These relationships were clearly established 
many years ago by E. Luther. 

In discussing the ' stabilities ' of hydrocarbon oil emulsions, it must 
not be forgotten that I was dealing with very dilute suspensions of oil 

1923 Vi 


in water, produced by mechanical agitation without the addition of any 
' emulsifier. ' I pointed out that in the emulsification of oils in water 
by means of soap, the soap lowers the interfacial tension and concen- 
trates at the interface. When we wish to produce oil emulsions in the 
ordinary sense of the tenn we must use some such emulsifying agent, 
and for this purpose many substances are employed, such as soap, 
gum acacia, gelatine, casein, starch, &c., &c. All these substances 
concentrate or condense on the surfaces of the oil globules. If we may 
regard these surface films as very mobile from the molecular-kinetic 
point of view, it is clear that they will confer an increased degree of 
stability on the emulsion. For any sudden decrease of interface 
(caused, for example, by coalescence or partial coalescence of two 
adjacent globules) will produce a momentary increase in the surface 
concentration or thickness of the adsorption layer, and so a decrease in 
the interfacial tension, if the surface layer is not saturated. It may 
require a perceptible time for the molecular-kinetic motion (especially 
in the case of large molecules or hydrated micelles) to readjust the 
equilibrium between the surface layer and the bulk. 

It is probable, however, that the stability of the emulsion is in many 
cases due to the fact that the sui'face films possess a very viscous, 
quasi-rigid, or gel-like character, so that a more mechanical explanation 
is necessary. As S. U. Pickering showed, oils may be emulsified in 
water by the gels of certain basic salts; and A. U. M. Schlaepfer has 
shown that emulsions of water in kerosene oil may be obtained by means 
of finely divided. ' carbon.' Nevertheless, even in cases where an 
emulsifier is used, we may hope to succeed in obtaining a more precise 
physical analysis of the system. It is interesting in this connection to 
note that Mr. W. Pohl has recently found in my laboratory that when 
a neutral hydrocarbon oil is emulsified in water by means of sodium 
oleate, the electrical potential difference at the oil-water interface is 
almost doubled, and that the effects of alkalies and salts on this potential 
difference are very similar to those found in the case where no emulsifier 
is employed. 

I cannot conclude this account of certain aspects of surface actions 
and properties without making a passing, though all too brief, refer- 
ence to the beautiful investigations of Sir George Beilby on the amor- 
phous layer. He has shown that when the surface of crj'stalline matter 
is subjected to shearing stress there is produced a sm-face layer of 
a vitreous or amorphous character — a ' flowed ' surface — in which the 
particular ordered arrangement of the molecules or atoms which is 
characteristic of the cn'stalline matter largely disappears. Working at 
University College, London, Dr. Travers and Mr. R. 0. Eay have 
recently obtained a very interesting confirmation of the Beilby Effect. 
The heats of solution (in kilogram calories per gi-am mol) of vitreous 
silica and silver sand (silica as crystalline quartz) in aqueous hydro- 
fluoric acid were found to be 37.24 and 30.29 respectively. After 
gi'inding for fifteen hours the corresponding values were 36.95 and 
32.46 respectively. If we assume that the internal energy of the amor- 
phous phase produced by grinding is the same as that of the vitreous 
silica (silica glass), we can calculate from these results that about 31 per 


cent, of the crystalline silica has been converted by gi'inding into 
' amorphous ' silica. The densities of silica glass and silver sand were 
found to be 2.208 and 2.638 respectively. After fifteen hours' grinding 
the density of the latter was lowered to 2-528. On the same assump- 
tion as before, it follows that about 26 per cent, of the quartz has been 
converted into the vitreous condition. The difference between the 
figures 31 and 26 is doubtless due to the approximate character of the 
assumption underlying tTie calculations and to experimental en^ors. 
There seems little doubt-, however, about the soundness of the main 
conclusion — namely, that the mechanical action of shearing stress on 
crystalline matter is to produce a random molecular or atomic 
distribution in the surface layers. 

This discussion, necessarily brief and limited, of certain aspects of 
the properties of surfaces — molecular orientation, surface concentra- 
tion or adsorption, electrical or ionic polarisation- — has dealt very largely 
with states of thermodynamic equilibrium. The chief interest of such 
studies has always appeared to me to lie in their possible ultimate 
bearing on the phenomena of life. We must remember, however, that 
the activities, and indeed the very existence, of a living organism depend 
on its continuous utilisation of an environment that is not in thenno- 
dynamic equilibrium. A living organism is a consumer and trans- 
fonner of external free energy, and environmental equilibrium means 
non- activity, and eventual death. 

It is probable, therefore, that along and across ' living surfaces ' 
there is a continual flux of activity. Does the very existence of these 
surfaces depend on some special sort of activity ? Questions such as 
these must make us cautious as regards any premature generalisation 
from simple physico-chemical results. But there is encouragement if 
we may assume that the physico-chemical manifestations of life are 
functions of the same powers and potentiahties of electrons, atoms, 
ions, and molecules that we find in what we call inanimate environ- 
ments. Life would then be simply a new functional relationship of 
veiy old parameters, at all events in so far as its various physico- 
chemical ' mechanisms ' are concerned. 

In the totality of its activities and relationships, however, a living 
organism is an individual, and to arrive gradually at an understanding 
of this ' individualisation ' it will be necessary to study very carefully 
the laws pertaining to the intimate and particlar modes of action of 
simpler individuals. The actions of an individual are conceived by 
science as determined by its internal state and by its relation to its 
environment. As we pass from certain peculiar atomic states, where 
the actions appear to have no relation to environment, to molecules, 
colloidal micelles, and living cells, the effects of the environment in 
determining activity seem to become more and more pronounced. 

The internal state of a living cell or organism may arrive from time 
to time at ' critical ' points and ' critical ' transformations. Whatever 
may be the relation of such possible critical states to the previous cell- 
environment reactions, the resulting events will be immediately deter- 
mined by the special internal nature and sctivity of the cell itself. Is 
tbis ' special internal nature and activity ' simply a special type of 


organisation or arrangement of the positions, shapes, sizes, orientations 
and motions of electrons, atoms, ions, and molecules? To this oft-put 
question the answer of physico-chemical science is still in the affirma- 
tive. More complex individuals are not cloaked in any mysterious 
' law of complexity. ' 

Probably future progress will depend more on the investigation of 
the special nature, situation, and action of individuals than on the 
statistical thermodynainic treatment of the average behaviour of the 
' .crowd- ' 







It is just twenty-seven years since the British Association last met in 
Liverpool, and in casting my mind back over the intervening years 
and thinking how our Science stands to-day with regard to its position 
then, it has appeared to me that one at any rate of the most important 
lines along which progress has been achieved is due to the growth of 
what may be termed the genetic pi'inciple. This would seem to be 
equally true both aiS regards Petrology and Palaeontology, for it is 
becoming increasingly evident that conceptions and classifications, 
whether they be of rocks or of fossils, if they are to be natural, must 
be based fundamentally upon origin and descent. Therefore, situated' 
as we are here in Liverpool, almost within sight of the Welsh Hills, 
on the one hand and the Lake District Fells on the other, both classic 
areas so far as the Lower Palseozoic rocks are concerned, it may perhaps 
be appropriate to see how far this principle may be applied to the eluci- 
dation of problems connected with these Lower Palaeozoic rocks, to 
note what has been achieved in this respect, and how much yet remains 
to be done. The subject, therefore, of my address to you to-day is 
' Evolutional Palaeontology in Eelation to the Lower Palaeozoic Eocks.' 

Problems of the Older Rocks. 

As I interpret the facts, the chief problems still awaiting solution 
are both fundamentally stratigraphical : on the one hand there are 
problems relating to classification, that is, of subdivisions of the forma- 
tions on a basis that shall be of wide application, and render possible 
correlation of beds in areas far removed from one another; on the 
other, there is the actual structural relationship existing between these 
beds as seen in the field, which, when rightly intei'preted, makes 
evident the nature and extent of those deformational strains that have 
from time to time so profoundly affected the rocks of the Earth's crust. 
With regard to classification, the problems are of different degrees of 
magnitude; there are, for example, those larger difficulties relating 
to the satisfactory determination of the upper and lower limits of the 
formations ; there are also those connected with the correlation of all 
those smaller local subdivisions of formations with which Strati- 
graphical Geology is becoming increasingly overburdened without any 
prospect of compensation unless a fresh principle be inti'oduccd. 



Moreover, the interpretations of structural details must to a large 
extent depend upon the satisfactory elucidation of these problems of 
classification, so that the solutions of the two really go together. It 
is my firm conviction that the most satisfactory solution of the first, 
and therefore also of the second, of these problems will be found in the 
application of the principles of evolutional Palaeontology. 

Variation iu Shallow-water Fauna. 

As regards the more fundamental of the two problems, a general 
principle seems to be involved, demanding the recognition of the rela- 
tive values of faunal changes in shallower and deeper waters respec- 
tively. The faunas of the shallow seas must of necessity be subject 
to far greater degrees of physical change than those of the deeper 
waters, and, thanks to the excellent work done at the Danish Biological 
Station ^ in carrying out investigations on the bottom faunas of different 
Danish waters, we now know a good deal as to the extent to which 
the distribution of modern faunas is governed by physical conditions. 
Some of the more important conclusions reached by the Danish investi- 
gators may be summarised as follows : — 

1. That certain characteristic animal communities undoubtedly 
exist under certain physical conditions, and when these conditions 
remain constant even over wide areas the same community will be 
found, but each community is bounded by those physical conditions. 

2. That change in physical conditions brings about a change in the 
characteristic animal community, though certain organisms may be 
found in more than one community. 

3. The physical changes to be correlated with the change in com- 
munity are those of temperature, salinity, and clearness of the water; 
depth as depth seems tO' be less important than the factors which go 
with depth, such as temperature, amount of light, character of the sea 
bottom, and quietness of the water. Thus along a section in the 
N. Kattegat at depths varying only between 7 and 50 metres, five 
different animal communities have been recognised: — 



Character of Bottom 



1. Echinocardium Community . 

7 metres 

Fine sand 

2. Echinocardium - Turritella 

12-19 metres 

Dark sand with 
fine detritus 


3. Brissopsis - Turritella - Echino- 
cardium Community (transi- 

24.5 metres 

Fine sand with fine 

14° C. 

4. Brissopsis - Turritella Com- 

35 metres 

Grey Kattegat Clay 

13.4° C. 

5. Brissopsis-Nucula Community 

50-52 metres 

Light Kattegat Clay 

8° -6° C. 

1 1913, Petersen, C. G. J Report of the Danish Biological Station. 



That depth is not the determining factor is clearly indicated by 
another section taken in the Sams f Belt : — 


1. Macoma Community (No 

8 metres 

Character of Bottom 

18.5° C. 

Pure sand 

2. Calcarea Community . 

IS metres 

Light mixed clay 
and sand 

10.1° C. 

3. Rich Modiola Eohinodeini 

18 metres 

Coarse gravel with 
sand, clay, pebbles 

10.3° C. 

This Macoma community is very well known, as it occurs ni all 
the more sheltered waters of the Danish Fjords, and can be directly 
observed and examined at low-water. It is seen to present many 
facies, and to vary greatly according to whether the bottom is sandy, 
stony, muddy, or soft, and according to whether it is exposed to the 
action of currents and to varying conditions of temperature and salinity. 
The fauna in bulk, apart from those characteristic species which belong 
to the community as a whole, varies considerably in different localities, 
and, as the author of the Eeport expresses it, ' the real matter for 
wonder is that there are some species common to all these localities 
and different conditions. ' 

The difference between the characteristic animals of the communi- 
ties living in waters of different depth is so great that none of the 
animals are common to both. This does not mean that no speciesare 
common to shallower and deeper waters, but that no characteristic 
species as such. 

Now the interest for the geologist in all this lies in the fact, as, 
Petersen has pointed out, that these ' characteristic animals ' are 
closely akin to the ' characteristic fossils ' of the geologist, and we may 
ask ourselves whether the variations which can be seen to exist in the 
contemporaneous shallow-water fossil assemblages of past ages may 
not be recoo-nised as brought about by the same factors as those that 
can be seen operating to-day. 

Our ancient Lower Palaeozoic faunas were composed in the main 
of trilobites, brachiopods, and corals, both solitaiy and reef-building. 
The distribution of coral reefs at the present day is governed by three 
cardinal factors^: — 

(1) Uniformly warm waters, the temperature of which does not i 
fall below 22° C. on an average throughout the year ; 

(2) A depth not exceeding 14 fathoms ; 

(3) Clear waters, i.e. those free from mud in suspension; 

and there is every reason to believe that formations containing the 
remains of coral reefs were laid down under very similar conditions to 
these; hence reef -building corals might be expected to have flourished 

- 1923, Potts, F. A. 
Review, Feb. 1923. 

The Distribution of Coral Reefs.' Srhool Science 


best in clear, warm seas of moderate depth, and sucli trilobites and 
brachiopods as occur abundantly associated with them might be pre- 
sumed to have floui-ished also under these conditions ; other brachiopods 
and trilobites would appear to have attained their greatest development 
on sandy shores, whilst others, again, seem to have lived in greatest 
numbers in muddy waters, no great change in depth being necessi- 
tated. Unfavom-able conditions seem to be indicated by the dwarfing 
( of a fauna as a whole, the extreme of such conditions being attained 
I when salinity of the waters resulting from desiccation reached such a 
pitch that abnormally distorted forms predominate. Moreover, in the 
case of faunas inhabiting the actual coastal region, it is obvious that 
even slight changes in the relative levels of sea and land will be very 
effectively felt, since these may be sufficient to bring about permanent 
submergence or emergence, and thus induce a total change of environ- 
ment; also since shore lines tend more particularly to be the lines 
along which migrations take place between the faunas of one area 
and another a further factor coniributing to heterogeneity may thereby 
be introduced. 

It is therefore obvious that there are many factors tending to give 
different aspects to shallow-water faunas in different places, hence a 
certain amount of Lateral Variation or lack of uniformity is only to 
be expected amongst those of the same age when seen in different 
locahties. There may also be considerable Vertical Variation in the 
type of shallow-water fauna of successive ages, either in response to 
changes in the physical conditions of one and the same area, or as the 
result of migration ; and if the surroundings are variable it may happen 
that two faunas separated in time may bear a greater degree of 
resemblance to each other than two successive famias, the similarity 
being induced by a return to similar conditions. Vertical Variation has 
long been recognised and understood in principle by geologists, but I 
do not think the same can be said of Lateral Variation. 

Since then a greater or lesser degree of variation is to be expected 
even in ancient shallow-water faunas that ai'e contemporaneous, it is 
in their case too the resemblances that should be considered remarkable 
rather tlian the differences, since close resemblance would seem to 
indicate one of two things, either a wonderful degree of uniformity of 
conditions over a wide area, or else the occuiTence of a large proportion 
of those fossils that I have elsewhere^ called ' successful types,' these 
possessing amongst other characteristics the property of being, in some 
cases at any rate, less susceptible to differences of physical condition. 
Thus in comparing the contemporaneous shallow-water faunas of the 
past in different areas it would seem that all we are entitled to expect 
is a general resemblance rather than a particular, and this at best will 
probably show itself in generic rather than specific agreement, a fact 
well illustrated by the trilobite faunas of the Keisley and Chair of 
Kildare Limestones of Ashgillian age; the general aspect of these 
faunas is really far closer than any fossil list would indicate, 
since the species are often different, though the faunas agree in the 

' 1922, Elles, G. L. ' The Graptolite Faunas of the British Isles.' Proc. 
Geol. Ass., 1922, vol. xxxiii. 

C\— GfiOLOGY. 87 

occurrence of riunlerous Cheirurids, Lichads, and Remopleurids. In 
many cases, therefore, where there is considerable hiteral variation in 
faunas, and also where the fragmentary condition of the specimens 
renders specific determination impossible, or where the assemblage is 
insufficient to determine the horizon, the recognition of the evolutional 
stage reached by an organism may prove to be of greater significance 
than specific determination, in that it is essentially independent of any 
nomenclature, however much such a nomenclature may in the past 
have been forced upon it. 

Moreover, since all shallow-water faunas will be liable to be affected 
to a greater or lesser extent by the different factors enumerated above, 
difficulties in correlation are bound to occur; these may be obviated in 
two ways, either by studying the faunas from the evolutional stand- 
point, and noting the stage reached, or by determining where possible 
the relation of each separate fauna to its deeper-water equivalent ; for 
it is obvious that the faunas of the deeper-water areas where conditions 
are more uniform should furnish the standard for purposes of classifica- 
tion. Since the physical conditions in such areas are far more constant, 
and the sediments of more uniform type, any change in the character 
of the fauna that does take place is almost bound to be of real signifi- 
cance, and probably in many cases indicates the attainment of an 
important stage in the evolution of the group or groups of organisms 
concerned. Every modern classification of strata should surely take 
these data into- account. It is not that I undervalue the importance 
of local changes — they have their own significance — but just because 
they are bound to be more or less entirely local they are useless for 
purposes of international correlation. 

Principles of the Modern Classification of Strata. 

It can hardly be doubted at the present day that the most efficient 
classification of strata is that based upon the palseontological principle • 
of the coming in of new forms, hut if the classification is to be of wide- 
application and to be^ depended upon, this coming in of new forms must 
not be directly connected with changes in the character of the sedi- 
mentation. Physical causes which induce changes in the nature of 
the sediments are no doubt important, and probably give great impetus 
to evolutionary development, but to be depended upon they must be re- 
flected in those faunas of the deeper parts of the epicontinental seas 
where sedimentation continues apparently unaltered; in other words, 
where the change in the fauna shows primarily as an advance in the 
evolutional stage. The factors that have to be considered render the 
international classification of our great foraiations a matter of con- 
siderable difficulty. This is well illustrated by the differences of opinion 
that exist as to where the upper limit of the Silui'ian should be placed, 
and in spite of all that has been urged by Stamp,* I am not yet con- 
vinced that his claim that the boundary should be shifted to the base 

( 1920. Geol. Mag., vol. Ivii, p. 164. 
* Stamp, L. D. j 1922. Bull. Soc. Beige de Geologie, vol. xxxi, p. 87. 
[ 1923. Geol. Mag., vol. Ix, p. 92 and p. 276. 


of the Downtoniaii rests upon a satisfactory basis. Towards the close 
of the Silurian, as is perfectly well known, far-reaching changes in 
physical conditions took place, necessaiily involving changes in the 
character of the shallow-water fauna whenever and wherever these 
occurred, and the coming in of fishes appears to be directly connected 
with them. That these changes took place simultaneously over wide 
areas is in the highest degree improbable, and having had some experi- 
ence of the behaviour of these rocks in the field I have felt that tiie 
evidence at times so strongly suggested that the Downtonian was essen- 
tially a fades formation that the possibility of its horizon being eventu- 
ally found to be almost as inconstant as that of the Millstone Grit was 
far from improbable. That there may appear to be a similar change 
of conditions in parts of Britain and France at about the same time is 
not really the point; it is not the succession of shallow-water marine 
faunas that is important from the point of view of classification, but 
how far these are really of the same age in different places, and how 
much change is reflected in the fauna of the more stable deeper-water 
beds. The author may be perfectly right in his contention, only up 
to the present as I see the problem he has not proved his case. 

So, too, at the lower limit of the same Silurian formation ; at 
present the top of the Ashgillian needs clearer demarcation, and I 
have endeavoured to show elsewhere that on palseontological grounds 
the most satisfactory place at which to draw the line is at the horizon 
where Monograptus makes its first appearance in force in the deeper- 
water sediments of the period, a well-defined faunal change indicative 
of the attainment of an important evolutional stage, of world-wide 
significance, and independent so far as can be detei-mined of any change 
in the nature of the sedimentation. This appears also to be the horizon 
of the entrance in force of the true Pentamerids (Barrandella) amongst 
the faunas of shallow-water type. 

With regard to these general principles of modern classification, 
there would appear also to be only one really effective way of rescuing 
our Science from the increasing burden of local nomenclature ; this has 
had its uses undeniably in indicating the exact nature of local successions 
and developments, and at present cannot be avoided in unfossiliferous 
rocks such as those of Pre-Cambrian age, but for the rest of our Lower 
Palaeozoic rocks surely the time is coming, if, indeed, it has not already 
come, when there may be detected emerging from all this wealth of 
local detail a general palseontological sequence that may be of wide and 
possibly even of international application. 

There will, no doubt, be those who will object on the grounds that 
in adopting such a classification the geological world might be at the 
mercy of the whims of a few palaeontologists ; this should not be the 
case if the evolutionary principle be adopted, for the choice of fossil 
indices should then be limited to those fossils that are of the nature 
oi stable or successful types, for these are likely to be the only forms 
with a sufficiently wide distribution in space to be really useful, whilst 
in widely remote areas, should these fail, corresponding forms at a 
similar general stage of evolution should be utilised in their stead. 

The mo5t reliable classification for shallow-water beds would then 


be that based upon the evolutional sequence of the members of one or 
more species-groups ^ belonging to genera possessing considerable 
possibilities of variation (variation gradient) so long as such members 
continue to be important and characteristic members of the fauna ; when 
they fail in this respect they should be replaced by the members of 
another species-group that succeeds in importance. Thus, as will be 
shown in the sequel, the evolutional series comprised within the species- 
group of Calymene cainbrensis might well be adopted for classifying 
the lower part of the Ordovician in our own coantry, whilst in the upper 
pai't members of the species-group of C blurnenbachi might be utilised. 
It may prove advisable in some cases to choose genera belonging to two 
distinct phyla to serve as a check upon each other such as, in the case 
of certain of the Lower Palaeozoic rocks, might be afforded by Trilobita 
and Brachiopoda; in other cases species-gi'oups of either of these phyla 
might prove sufficient. 

Deeper-water Faunas of the Lower Palaeozoic. 

We must now pass on to the consideration of some Lower Palaeozoic 
Faunas, and see what has been achieved by regarding them from the 
evolutional standpoint; and since, for reasons already given, it would 
seem that the faunas of the deeper waters must be taken as the standard 
for purposes of classification, these will be considered first. 

Throughout the greater part of Lower Palaeozoic time the Graptolite 
Shales constitute the typical deposit of the deeper waters of our epi- 
continental seas, the factors controlling their accumulation being not 
depth as such, but rather the factors that are closely associated with 
depth, especially quietness of the water, and absence of coarse sediment. 
Strictly speaking, I suppose the graptolite fauna does not belong to the 
Black Shale, since it is in all probability pseudo-planktonic ; but owing 
to similar conditions governing its distribution the two are alm.ost 
invariably associated and may be taken in that sense to belong ; in any 
case, its occurrence is independent of those factors which make for 
heterogeneity in the faunas of the shallower waters, so that the 
Graptolite Shales furnish the standard sequence for purposes of 
classification. As regards the study of this highly interesting group of 
organisms, it is as well to note at the outset their extraordinarily favour- 
able position from the evolutionary standpoint ; for though we may not 
know the complete story of the whole class of the Graptolithina, since 
at present its actual beginning is uncertain, we do appear, at any rate, 
to have a more or less complete history of the more important order, 
the Graptoloidea, comprised within the rocks of Lower Palaeozoic age; 
so that here, if anywhere, we ought to be able to study the various forms 
in their true relationship to each other. To a large extent this can be 
done, and the honour of its first conception belongs to Nicholson and 

5 Species-group or gens may be considered to be the aggregate of all the 

species which possess in common a large number of essential properties and « 

are continuously related in space or time. Vaughan, Q.J.G.S., 1905, vol. Ixi, 
p. 183. 


Marr, who in 1895' pointed out the evolutional importance of the 
simplification of branching ; the work is still far from complete, though 
more lines of evolutional importance have been added to that of 
Nicholson and Marr. At the present day we can study the lines along 
which general development took place, see how different species-groups 
arose, reached their acme, and diminished in importance as they were 
succeeded by those of the next evolutional stage ; and we can note the 
horizons at which the more important of these evolutional stages were 

Looked at purely from the evolutional standpoint there seem to be 
at least three main lines along which the graptolites evolved as a 
whole: — 

1 1. Change in direction of growth. 
! 2. Simplification in branching. 
j 3. Elaboration of cell type. 

' The first of these brings about a change from the primitive pendent 
or hanging form to the scandent or climbing position, and appears to 
be brought about by the necessity for the better protection of the nema 
or attachment organ, and would, therefore, seem to arise in direct 
response to environment. 

The second line of development eventually results in reduction of 
the total number of stipes or branches of the rhabdosoma to one; the 
earliest attempt in this direction, where the tendency to reduction out- 
distances that of change in position of growth, appears to be unsuc- 
cessful, since the fomis are all ' dead ends ' undergoing apparently no 
further development of any kind [Azygograptus). The later attempt is 
combined with further change in the position of growth, so that the 
forms which result are scandent one-branched graptolites with a well- 
protected nema ; these are obviously highly successful, undergoing a 
rapid development in many different directions. 

This simplification in branching may, as suggested by Nicholson and 

t Marr, be the impression of the struggle for an adequate food supply. 

The third line also occurs in what may be termed two episodes, 

and is of a somewhat different nature each time ; the earliest elaboration 

affects the cell as a whole, whereby the cell with a bend or sigmoid 

curve in it is gradually evolved from a straight tubular cell, the curvature 

eventually becoming so pronounced that there is torsion of the whole 

apertural region. Since the development of a cell of this type would 

allow of closer packing, its evolution, like that of the simplification in 

branching, may be the impression of the struggle for food ; if so this type 

of cell elaboration may result in response to conditions of environment. 

In the second episode the elaboration is of a totally different nature, 

and seemingly results as the expression of two definite tendencies or 

trends within the organism, one a trend towards lobation, the other 

a trend towards isolation. 

So it comes about that the broad outline of the Graptolite History 
is found to be comprised within four chapters, all dealing with different 

" 1895, Nicholson and Marr, ' Phylogeny of the Graptolites.' Geol. Mag., 
dec. 4, vol. ii. 


evolutional stages, each chapter being capable of further divisions into 
sections and sub-sections. 

The four chapters of the story may be summarised as follows:' — 

1. General simplification of branching coupled with change in direc- 
tion of growth. Attainment of unsuccessful one-branched form, which 
undergoes no further development. Characteristic of Arenigian and 
Llanvirnian beds. 

2. Commencement of elaboration of cell type (first episode) 
Characteristic of Llandilian beds. 

3. Widespi'ead attainment of the scandent position by two-branched 
forms. Characteristic of Caradocian and Ashgillian beds. 

4. Widespread attainment of one-branched stage by scandent forms 
which undergo conspicuous elaboration of cell type (second ^episode). 
Characteristic of the whole of the Silurian. 

The first chapter deals mainly with the many-branched graptolites, 
of which the best known is the 8-branched form Didiograptus, and the 
most obvious changes shown are those tending in the direction of the 
reduction of number of stipes or branches. Thus the 32-stiped forms 
are gradually succeeded in time by those with 16 stipes {Logano- 
graptus), the 16-stiped by those with 8 (Didiograptus), the 8 by 4 
(Tefragraptus), and the 4 by 2-branched forms (Didymograptus). Thus 
the simpler forms succeed the more complex, and at the same time 
there is a gradual change from the pendent through the horizontal to 
the scandent position of gi'owth ; by the time this is attained the number 
of stipes is reduced to four, so that such forms are essentially scandent 
or climbing forms of Tetragraptus, though they are more familiar under 
the name of Pliyllograptiis . 

This, the first attainment of the scandent position of growth, is an 
evolutional stage of considerable significance, and differentiates the upper 
part of this first or Dichograptid fauna from the lower containing the 
many-branched graptolites ; the 2-branched horizontal Didymograpti 
become abundant at the same horizon (zone of D. extensus), so that it 
is easy of recognition without any knowledge of graptolite species. The 
PhyUograptus stage is short ; there is a certain degree of elaboration, 
and then further reduction in the number of stipes to two follows on, 
and the place of PhyUograptus is gradually taken by Glossograptus, a 
gi'aptolite common for the first time in the Llanvirn rocks, and often a 
conspicuous element in the faunal assemblages of that age. The struc- 
ture of the proximal end of these two graptolites is so peculiar and so 
alike that there can be no doubt of their relationship ; moreover, I regard 
the septal spines of Glossograptus as possibly representing the last 
vestiges of the thecse of the third and fourth stipes of PhyUograptus. 
Structural resemblances of such a kind may naturally be made out in 
the laboratory or museum, but the realisation of the true connection 
between them and their proper place in the evolutional line only becomes 
obvious when they are seen gradually replacing each other in the field 
with all the intermediate stages. 

If now simplification in branching be accepted as a line of evolution, 
how does it come about that many-branched graptolites are often found 
occurring on the same slabs of rock as those with four or even with 


only two branches? Field evidence supplies the answer to this very 
natural query. Whilst the earliest graptolite with which we are 
acquainted was a pendent form, there very quickly followed other 
graptolites in which a horizontal direction of growth replaced the earlier 
pendent direction, though both occur side by side in rocks of the same 
age; the horizontal growing forms we term Clonograptus, the pendent 
Bryograptus. Now it is perfectly obvious from observation in the field 
that as regards simplification of branching the same plan of evolution 
was followed in both these groups, though there is always a tendency 
for development to lag behind and go slower in the pendent line, 
whereas development is so rapid in the horizontal line that many Clono- 
grapti persist alongside the 8-branched Dichograpti, though when 
Dichograpti persist alongside the 4-branched Tetragrapti they are most 
commonly those in which a certain amount of simplification has already 
taken place, since they are, as a rule, forms with only six or five stipes 
instead of eight ; owing, however, to the unequal rate of development in 
the two groups there is a characteristic association of pendent 4-branched 
graptolites with horizontal 2-branched forms of the type of D. extensus, 
whilst horizontal d-branched forms have become rare. 

The apparent anomaly is thus clear when followed out step by step. 
This greater rapidity of development in one group seems to indicate that 
these horizontal -growing forms were the more successful of the two ; and 
it is, therefore, perhaps only to be expected that almost all the later 
graptolites are developed from ancestors within that group, the excep- 
tions being those whose ancestry is at present obscure, but there is no 
indication that these arose from any member of the pendent group ; I 
have so far been utterly unable to find any graptolites in later beds 
which seem to be connected with these. If I am right in supposing 
that the change in direction of growth of the rhabdosoma was connected 
with the protection of the hollow thread-like nema (virgula auctorum), 
which is the attachment organ so vitally necessary to the colonial organ- 
ism, the forms belongring to the pendent group may be regarded as 
unsuccessful because they fail utterly to secure this necessary protec- 
tion, and, therefore, the members of this group come entirely to an end 
at the top of the Llanvirnian. Within the other group protection is 
better achieved, since in many cases at any rate the horizontal-growing 
stipes appear to have been plastered on to foreign bodies or suspended 
therefrom by short threads, and the nema would, therefore, in most 
cases have been short. Within this horizontal group the goal in simpli- 
fication would seem to have been reached early in the one-stiped Azygo- 
graptus of the Middle Arenig; this type is repeated more than once at 
slightly higher horizons, but appears to be in no case a successful form ; 
individuals are very commonly broken in the region of the sicula, which 
is in itself suggestive, and they, like the pendent Didymograpti, appear 
to be 'dead ends.' The successful one-stiped form is attained much 
later by very devious routes through the scandent or climbing grapto- 
lites, and in all of them the attachment organ is very perfectly pro- 
tected, partly by being buried within the rhabdosoma for the whole of 
its initial region, and partly by the development of a special encasing 
tube or sheath. 


Pi'actically all the graptolites referred to above, which are the pre- 
dominating element in the fauna, are characterised by simple cells — 
i.e. at most a reproduction of the embryonic sicula slightly modified in 
respect of relative length and breadth — and they follow what I have 
called elsewhere the Dichograptus plan of development; they may, 
therefore, be regarded as constituting the first or Dichograptid Fauna, 
which is pre-eminently characteristic of the rocks of Arenigian or 
Llanvirnian age. Without any special knowledge of species or genera, 
the horizon of this fauna may be recognised by the presence of branched 
graptolites with simple thecfe, the presence of scandent fonns being 
indicative of the higher beds. 

In all the earlier graptolites, as has been shown, the cell type is 
simple, but soon after the two-stiped horizontal Didymograpti have 
developed a slight change begins to be apparent in the thecae of some 
forms ; this shows itself in a drawn-out curvature of the cell wall and a 
turning in of the apertural margin, which gives a most striking and 
characteristic appearance to the cell after compression. This is first 
apparent in the thecfe in the region of the sicula, and becomes less 
conspicuous as the stipe grows in length ; for it may be noted at this 
point that all progressive development (anagenesis) is first indicated in 
the proximal and, therefore, youthful region of the rhabdosoma, and 
when retrogi"ession (catagenesis) occurs, it is in this same proximal 
region that signs of former elaboration are retained. 

Throughout the earlier rocks of Llandilian age the great majority 
of the graptolites have cells of this slightly elaborated type and two 
stipes only, which are reclined or re flexed in their position of growth ; 
but gradually in some forms an increasing degree of curvature of the 
walls of the cells becomes apparent, and the incurving of the apertural 
region is accompanied by a degree of torsion that after compression 
causes a very different appearance according to whether the rhabdosoma 
is viewed from the front (obverse) or back (reverse). This is the 
DiceUographis stage, and so distinct is the appearance of this graptolite 
from any Didymoqraptus that it would never be considered related if the 
successive stages had not been followed step by step. It may be noted, 
too, that whilst this cell elaboration is in progress evolution along other 
lines seems to be temporarily arrested, but is resumed when the elabora- 
tion has reached its acme, especially towards the attainment of the 
scandent position of growth ; this is at first only partial, as in Dirrano- 
graptus, but is eventually complete, as in the closely related Clima- 
cograpti, which are scandent throughout. The relationship of 
Climacograptu-s is clearly with Dicranograptus and Die ellograptus rather 
than with Divhgraphis. with which up to the present it has been invari- 
ably grouped. The only connection it really has with Diplograptus is 
that, being a biserial scandent form, it is at a similar evolutional stage. 

Since the simpler type of thecal elaboration is characteristic of the 
graptolite Leptoqraptns, the various forms in which this type of theca 
is found may suitably be regarded as constituting the second or Lepto- 
GBAPTlD F.-kUNA, and its occurrence, whether in simpler or more complex 
forms, may be taken as indicating rocks of Llandilian or Caradocian 
age. As will be. shown later, other feitui-es more particularly charac- 


teristic of the Caradocian will serve readily as a guide to discriminate 
between tliese two, whilst the degi'ee of elaboration shown will afford 
some indication as to whether the lower or upper part of the Llandilian 
is indicated. 

There is no new element definitely to be associated with the third 
chapter of the graptolite story, and yet perhaps the opening paragraphs 
are as striliing as anything in the whole narrative. A featm'e that 
cannot fail to arrest the attention of eveiy field worker is surely that 
extraordinary development ol large Diplograpti and Climacograpii that 
characterises the junction of the Llandilian and Caradocian rocks. So 
far as can be determined from field evidence this swarai of Diplograpti, 
particularly of Orthographis type, is due to development along at least 
two lines reaching their acme at approximately the same time, and 
when these meet the CUmacograptus lines the result is bound to be 
very striking; moreover, since most of these are clearly highly success- 
ful forms, giving origin to numerous varietal modifications, the pre- 
dominance of the scandent biserial graptolites is pre-eminently the 
distinctive feature of the rocks at this horizon. Hence the various 
associated gi'aptolites may be regarded as belonging to the third or 

In the lower beds belonging to this fauna the complex-celled Dicello- 
grapti and Dicranograpii still persist, but the association of the large 
Orthograpti is sufficient to differentiate the horizon from the Llandilian. 
This is the association characteristic of the Caradocian. 

So far as the graptolite faunas are concerned there is obviously a 
close connection between the Caradocian and the Ashgillian, the pre- 
dominance of the Orthograpti continuing to be a characteristic feature; 
in the lower beds regarded as Ashgillian there is some evidence of 
retrogression as respects the Dicellograpti and Climacograpti, hcAh. 
showing a return to the simpler type of cell; the stages of this, how- 
ever, have not as yet been completely worked out. The highest beds, 
which from the point of view of their graptolites should logically be 
gi'ouped with this 1hird fauna, include some at present very generally 
grouped with the Silurian. In these Diplograpti (Orthograpti) and 
Climacograpti are still predominant, though the Dicellograpti have 

The next striking feature is the coming in of Monograptus, or, if 

expressed evolutionally, the uniserial (one stiped) scandent graptolite, 

a very important and easily recognised evolutional stage. This marks 

the successful attainment of the end along two lines of development: 

I simplification in branching, and change in direction of growth. It is 

' pre-eminently characteristic of Silurian rocks. 

In the earliest graptolites reaching this stage there is nothing new 
as respects the cells ; all arei ' old-fashioned ' types seen previously in 
Diplograptns, CUmacograptus, Leptograptus , or Dicellograptus ; but 
with the attainment of the uniserial scandent form the organism seems 
to have had its energies set free to follow further trends, these being 
in the main in the direction either of lobation or isolation, but they do 
not keep quite apart ; a certain degree of lobation creeps into the line of 
isolation, and a certain amount of isolation is clearly discernible in the 


lobate line; nevertheless, one or other trend is always the more con- 
spicuous and the more definitely followed. In both these lines the 
trend continues to the point where, as Lang ' has so ably described it, 
' their exaggeration puts the organism so much out of harmony with its 
environment as to cause extinction ' ; the lobation is developed till tho 
aperture of the cell is practically closed (Monog. lobiferus), and isola- 
tion is carried to such a pitch that the cells seem readily to have fallen 
apart from each other altogether, so extremely slender is the connecting 
portion {Rastrites maximus). The hooked variant of the lobate line, 
however, fares much better, and can be seen to work steadily up to its 
acme {M. priodon), and as steadily decline until the cell-form is seen 
to have returned tO' the point from which it started. 

These are the general facts concerning the evolution of the group 
as a whole. "We may now see the way this works out along a few 
particular lines. 

1. Bryograptus to Didymog. indentus. 

2. Clonograptus to Didymog. hirimdo. 

3. Monog. cyphus to Monog. tumescens. 

In the first of these lines the evolution is purely in the direction of 
simplification in branching, the thecal being practically identical 
throughout and the pendent position of growth unchanged. Thus we 
pass successively from Bryograptus kjeriilfl to Tetragraptus pendens 
by failure of branching, and thence to the two-branched Didymog. 
nanus, which by slight modification seems to pass into the form known 
as D. indentus; this is really only a late mutation* of D. namis. In 
the second case there is simplification of branching combined with 
change in direction of growth and some increase in the size of the 
thecfe. The first conspicuous cbange is the change in position of 
growth from pendent to horizontal, resulting in Clonograptus flexilis, a 
32-stiped graptolite, thence by gradual stages to Loganograptus logam, 
a 16-branched form, and by further reduction in the number of branches 
to 12, 11, 10, and 9 an important stage is reached in the well-known 
8-branched form Dicliograptus octobrachiatus. This passes succes- 
sively through what may be termed septad, hexad, and pentad stages 
before attaining another important stage, that of the 4-branched form 
Tetragraptus quadribrachiatus, a horizontal form with perfect sym- 
metry. It may be noted that the commoner and more widespread 
forms are always those in which there is symmetry. Now such a form 
as T. quadribrachiatus has two obvious lines of variation : it may con- 
tinue the process of simplification in branching or it may change its 
position of growth. It appears to do both, and so two lines diverge 
at this point with very far-reaching results. 

(a) follows the tendency for change in position of growth, and 
passing through the reclined forms Tetrag. amii and T. serra leads into 
that scandent Tetragraptus which we know better as Phyllograptus, the 
earliest scandent graptolite, and a very important form indeed; for 

' 1923, Lang. 'Evolution; a Resultant.' Proc. Geol. Ass., 1923, vol xxxiv 
p. 11. 

" Mutation. — This term is used throughout in Waagen's sense and not i/i 
that of De Vries. 

1923 I 


simplification in branching follows whereby the stipes are reduced to 
two, and an entirely new factor supervening in localisation of thicken- 
ing in the graptolite wall, the hne diverges in one direction and leads into 
the Eetiolitidse, a quite distinct species-group. 

(b) follows the tendency to simplification, and passes into the two- 
stiped form Didymog. extensus, and thence to an unsuccessful one- 
stiped graptolite Azygog. eivionicus. The two-stiped form undergoes 
also various modifications in the packing of the cells, and passes 
through Didymog. nitidus, a very variable graptolite, into D. hirundo, 
a more stable form, which is, however, apparently a dead end. In 
others of this Didymog. extensus type an actual modification of the cell 
structure supervenes as an entirely new factor, so that the cell, instead 
of being a simple tube, is gradually bent and twisted and its aperture 
turned in. The details of this have yet to be worked out completely, 
but the general plan is perfectly clear, and leads first into the Leptograpti, 
and thence into the Dicellograpti, Dicranograpti, and Climacograpti 
in turn. 

Lastly, we may study the elaboration of the cell as seen in the 
second episode, the evolution of the hooked variant of the apertural 
lobe. Here, starting from Monog. cyphus, which has the old-fashioned 
Dichograptus type of cell, we find the first traces of a hook in the 
closely related M. revoluhis, and can trace its gradual development in 
the proximal region of the rhabdosoma in M. difformis and M. argenteus, 
in which, though the hook is well developed proximally, the distal 
thecse are still simple ; gradually the hook-form invades the whole 
rhabdosoma (M. clingani and M. sedgwicki), and taking on its most 
distinctive features in M. marri, reaches its acme in M. priodon, per- 
haps one of the best-known graptolites all over the world. Thereafter 
retrogression sets in, the hook becomes less pronounced in M. flemingii 
S.S., and a small, highly characteristic variety is seen occurring side 
by side with the larger form ; this smaller variety gradually gives way 
to Monog. colonus, in which only the proximal thecee retain -any signs 
of their former elaboration, and M. colonus itself is replaced by Monog. 
tumescens, where all thecse are once more of the unhooked type just 
as in Monog. cyphus, though the form of the rhabdosoma of M. colonus 
is retained. This is one of the latest graptolites with which we are 

Shallow-water Faunas of the Lower Palaeozoic. 

The case of the shallow-water faunas of Lower Palaeozoic age must 
now be considered; and here, in spite of a vast amount of work that 
has already been accomplished, much remains to be done, but from a 
different standpoint and along very different lines. There exists already 
a great mass of more or less purely descriptive literature, accompanied 
in general by illustrations of varying degrees of merit. All this has a 
value of its own; it provides descriptions which aid identification of 
fossils, and in many cases gives an excellent idea of the variety of the 
brachiopods, trilobites, or corals represented in a certain bed or set of 
beds; but, looked at broadly, is not its value to a great extent purely 
numerical, giving an idea mainly of the relative abundance of certain 


fossils at certain horizons and their relative scarcity at others? Since 
such work has too often unfortunately been carried out in the museum 
or laboratory by workers unacquainted with the fossils in their natural 
environment, it is liable to fail to take note of pecuUarities of preserva- 
tion and condition that may be significant, and new names have in the 
past been sometimes given to the same fossil in different conditions of 
preservation, or to other forms which owe their apparent peculiarities 
to the deformation of the rocks in which they lie. As is perfectly well 
known, the older rocks of this country have almost always suffered 
more or less considerably in this respect, though in the case of some 
rocks, such as mudstones, it is exceedingly difficult to estimate the 
degree of such deformation in hand specimens removed from their 
proper surroundings. So, too, the relative sizes of fossils may take on a 
totally new aspect when seen in the field. In such a connection we 
may note the characters of the Caradocian faunas of Shropshire and 
North Wales respectively. Similar fossils from the two areas differ 
so much in size that the existence of small Welsh varieties is inevitably 
suggested, until it is realised when the faunas are seen in the field that 
the whole Welsh fauna is of smaller size though otherwise very similar, 
therefore obviously we are here dealing not with any true varieties but 
rather with a whole fauna living under less favourable conditions. 

The pity of it is that, in spite of all the labour and skill that has been 
expended, we are still left so largely in ignorance of the crucial facts 
that in these days we want to know. There is a very real need at the 
present time for the co-ordination of these descriptions so far as possible 
on genetic lines. The difference between the past and future palseonto- 
logical work appears to me to be just this: the older type of work is 
too dead, whilst the palaeontology of the future must be essentially 
alive; it must vitalise fossil organisms, and regard them as parts of 
once-living entities possessing definite ancestors and descendants, 
developing along definite lines which are the result partly of internal and 
partly of external forces.' The biologist will find his interest in the 
degree of relationship between species-group and species -gi'oup, or in 
the precise relationship between ancestor and descendants within the 
species-group, but the value of the work to the geologist will lie rather 
in the determination of the definite lines along which evolution takes 
place and the horizons at which important and easily recognised evolu- 
tional stages are reached. 

It may pei-haps be argued that the geological record is so imperfect 
that our story can at the best be of little value, because it will be so 
incomplete; to that I would reply that such features as have been 
sufficiently pennanent in any organism to impress themselves upon the 
hai'd parts that are all that remain to us are likely to be those of 
enduring significance, and therefore particularly reliable so far as they 
go. We mav miss detail, but the main facts of the stoi-v should be 
beyond question. Up to the present time resemblances and differences 
existing between certain fossils have often been noticed as points to 
render identification more accurate, but their true significance has too 

' Lang, loc. cit. 



often been missed. Classifioations have also been given claiming to 
be genetic, but too often all that has been done has been the placing in 
the same group or class, foi-ms that have reached a parallel evolutional 
stage, and since many of the more conspicuous evolutional stages 
appear to be reached at approximately the same time, even though along 
different lines, such a classification is chronological rather than bio- 
; logical. Frora the geological standpoint a chronological classification 
' is valuable, but the biological side must not be ignored. Thus we have 
seen in the classification of the Graptoloidea, Climacograptus and 
Diflograptus are both included in the family of the Diplogra'ptidce , 
presumably because they are both biserial and have both attained the 
scandent position of growth; they have no other connection and appear 
to have totally different lines o-f descent. The same is to a large 
extent true of Pompeckj's classification of the Calymenes.^" Thus 
Pompeckj divides the Calymenes proper into two sub-genera, Pharo- 
stoma and Cahpnene. The forms included under the s.g. Pharostoma 
are stated to be characterised by the presence of long genal spines and 
the termination of the facial suture at the posterior margin. These 
two are closely connected, for the presence of genal spines seems to 
inhibit the facial suture coming out at the genal angle as in the s.g. 
Calymene; hence if, as Pompeckj himself suggests, the possession of 
spines is a primitive character, it cames with it a notable stage in the 
development of the facial suture, since until the spines have dis- 
appeared the facial suture cannot come out at the genal angle. Hence 
the rounding of the angle and the position of the tei-mination of the 
facial suture together mark an evolutional stage that is regarded, as 
characteristic of the s.g. Calymene. He also places Calymeyres of the 
tristani type in a totally different section from the Calymenes of the 
type of C. camhrensis (Calymsne s.s.), for he holds that the lobing of 
the glabella is so different that 'relationship' is not to be thought of,' 
whereas I hope to be able to show that, looked at evolutionally, these 
forms may be regarded as belonging to different points along a special 
trend line, that of evolution of the glabella lobes, and the appearance 
of bifurcation in the glabella furrows upon which he lays such stress 
as a feature of importance in classification appears to me to be a neces- 
sary stage in the lobal evolution, and therefore only highly developed at 
a certain stage. 

On the other hand, Calymene caractaci, which he places in the 
same group as C. cambre^isis, apparently chiefly on the grounds of the 
course ol the facial suture and number of glabella lobes, does not 
appear to me to be so closely related from the genetic point of view, 
since these two differ markedly in other characters that must, I think, be 
considered 'essential,' and therefore belong more likely to different 

A glance at the table given at the end of his paper will sei-ve to show 
how largely this classification is chronological. It is probably true that 
the greater number of our fossil ' genera ' at the present day are poly- 
phyletic, and cut across true lines of evolution, as can be demonstrated 

^^ 1898, Pompeckj, J. F. ' On Calvmene Brongniarti.' Jahrh. f. Mineral , 
(^eol. ,f; Pal., vol. i, p. 187. 


in the case of the Corals, Trilobites, and GraptoHtes. The true relation- 
ship existing between individual fossils and fossil-groups will probably 
only become manifest after searching examination in the field, and 
whilst many of the species previously established will no doubt stand, 
others will probably be found to be more truly related to certain central 
forms as space or time variants (mutations), and may or may not be 
worth specific rank. So that the evolutional work that is required 
must be carried out primarily in the field, though supplementary work 
will have to be carried out in the museum or laboratory ; but the value 
of different features can, I believe, be only tmly estimated when they 
are seen making their first appearance, gradually coming to their acme, 
and then dying away to be replaced by others. Thus we may study 
in the field all the stages between fossil A and fossil B, whose relation- 
ship to A would probably otherwise never have been suspected, so 
different do the two extreme types appear. It was indeed truly said 
by your President three years ago^^ 'that not until we have linked 
species into lineages can we group them into genera, not until we have 
unravelled the strands by which genus is connected with genus can 
we draw the limits of families, not until that has been accomplished 
can we see how lines of descent diverge or converge so as to wan'ant the 
estabhshment of orders.' This is equally apphcable to shallow- and 
deeper-water faunas alike, but the time and space variants are best 
seen in shallow-water faunas, where the variation gradient being spread 
out over thicker deposits is less steep than it is in the deeper-water 
faunas, where it is often so steep that the time-variants tend tO' become 
ahsorbed in genera. 

The facts just dealt with concern the more purely biological side of 
the question, but for the geologist there is more in the evolutional 
method of work than this. Bearing in mind that Palaeontology fulfils 
one of its chief functions as the handmaid or helper of Stratigraphy, 
we may ask how far evolutional work will accomplish that object. 
The answer is clear and definite. The Lower Palaeozoic faunas, as has 
already been stated, are essentially Brachiopod-Trilobite faunas 
together with Corals where the seas were sufficiently clear to peiTnit of 
their growth and development. 

As regards the Corals, the kind of work required is that initiated by 
Vaughan, and most ably extended by Dixon, Carruthers, Stanley Smith, 
and others. Lang ^- has recently perfonned splendid service in the 
cause of evolutional palaeontology in putting forward his Doctrine of 
Trends, and showing how Carboniferous Corals follow what he terms 
Programme Evolution, since coral stocks continually developed along 
parallel lines so that different lineages may go through the same 
sequence of changes. We may hope that some such trends may be dis- 
cernible amongst the corals of Lower Palasozoic age, and Carruthers ^^ 
has shown us how best to obtain the knowledge we require. In 

" 1920, Bather, F. A. Pres. Address to Section C, Cardiff. 

" 1923, Lang, W. D. 'Trends in British Carbonif. Corals.' Proc. Geol. 
Ass., vol. xxxiv, pt. 2, p. 120. 

" 1910, Carruthers, R. G. 'Evolution of Zaphrentis delanouei.' Q.J.G.S., 
vol. Ixvi, p. 523, &c. 


his most admirable account of the evolation of Zaphrentis delanouei 
Carruthers has shown the importance of cutting serial sections, for 
the stages seen in the adult of early forms are often characteristic of 
adolescence in. forms at higher horizons. Thus in Z. delanouei evolu- 
tionary stages are confined to the shape of the cardinal fossula and 
the length of the major septa, and different time-variants (mutations, 
Waagen) show striking differences between these. 

In Z. delanouei s.s., which occm's in the Cementstone Group 
300-400 ft. below the base of the Fells Sandstone, the transverse 
sections show septa meeting in the centre of the corallum and a large 
cardinal fossula expanded towards the inner end ; together with this 
form there occur others which agi^ee with Z. delanouei in their adolescent 
stage, but in the adult a stage is reached in which the walls of the 
fossula become parallel and finally show a tendency to constriction at 
the inner end. Since this mutation marks an important evolutional 
change as regards the fossula, it is termed Z. parallela. 

At a considerably higher horizon, in the Lower Limestone Group, 
the cutting of sections of a fresh mutation foreshadowed in the Cement- 
stones reveals no trace remaining of what may be termed the delanouei 
stage; but the parallela stage is distinct, and with growth the inner end 
of the fossula narrows, whilst in sections of the adult stage the con- 
striction becomes very pronounced, the septa being, however, still joined 
together in the centre of the corallum. Again, on account of a further 
change in the character of the fossula this mutation may be distin- 
guished as Z. constricta. Within the Lower Limestone Group are also 
found forms representing a further change ; these do not pass through 
the parallela stage, but start at the constricta stage, and on further 
growth the septa shorten until they separate at the centre of the 
corallum. This again is an important and easily recognised stage 
(Z. disjuncta), and this mutation is said by Carruthers to show amplexoid 
characters ( = amplexoid trend, Lang). The geological value of these 
changes lies mainly in the fact that they are continuous in time and 
characteristic of different stratigraphical "horizons, apart from whether 
t"hey are progressive or retrogressive, but it is clear that careful dis- 
crimination may at times have to be made between these. 

At the mere thought of coping with the many evolutional problems 
connected with the Lower Palaeozoic Brachiopods the heart of the most 
vigorous palseontologist amongst us might well fail liim. I suppose 
that there is no single woi'ker on the Lower Palaeozoic rocks who has 
not at one time or another realised the stupendous nature of the pi'oblem 
that awaits us here. We have, I feel sure, all been conscious of the 
fact that many of the so-called long-ranged species are not really quite 
the same, but show certain differences at different horizons with which 
in the course of our field-work we have become familiar and can recog- 
nise, so that for the sake of our own convenience we have often given 
them the field-names ; but when we try to analyse these differences 
palseontologically each character seems so slight as to be trivial and 
unimportant ; nevertheless, in bulk they may be important and the two 
extremes quite distinct. This may well be illustrated by the case of 
the Dalmanellas as represented by the species D. clegantula, a name 


C— GEOLOGY. 101 

which as at present used does not define a species but an important 
species-group, the earhest members of which occurring low down in the 
Ordovician are certainly markedly different even as regards the 
external ribbing of the shell from those occurring at the base of the 
Silurian, though all have been included in the same diagnosis. Up to 
the present all we can do in naming such a fossil is to term it, in despair, 
Dalmanella of elegantula type. 

This work can and must be tackled group by group ; it will demand 
an amount of careful field-collecting, in the first place, of specimens 
showing internal as well as external characters, for these last are by 
no means to be neglected, since they often reflect changes in internal 
characters, though they do not do so invariably; hence it will be neces- 
sary to distinguish between those possessing different internal and 
external characters and those which differing in their internal 
characters yet may have the same external characters. 

Field palaeontology, when it has a definite aim of this sort in view, 
becomes a fascinating and absoi^bing study, and a fresh zest is given to 
the somewhat monotonous task of mere fossil-collecting. 

Kiaer, in his classic memoir on the Silurian Eocks of the Christiania 
Basin," has indicated to us how this work may be carried on. He was 
fortunate in that the rocks in the area where he did his work are biit 
slightly inclined and are affected only by faulting and nob by folding, 
so that there can be no doubt as to the order of succession of the various 
beds. To a large extent Kiaer has applied the principles of evolutional 
palaeontology with great success ; he notes the appearance of early muta- 
tions and their gradual evolution at successive horizons up to and beyond 
the development of the typical form. Thus he utilises the evolution of 
the septum in the Pentamerids of the species group of P. oblongus ; he 
notes how this septum is short in BarrandelJa undata, the earliest of the 
true Pentamerids, and shows how this gives place upward to another 
mutation, P. horealis, with a septum which, though rather longer, is 
nevertheless shorter than that of P. oblovgus s.s., which is next 
developed. At a still definitely higher horizon is found P. gotlandicus, 
probably to be regarded as a late mutation of P. ohlongus, in which 
the septum is still further developed. 

Having arranged these Pentamerids in order, Kiaer is able to throw 
light on the development and relation of the Stricklandinias, among 
which there has been and still is much confusion in this country. He 
shows that Stricklandinia hns makes its appearance in the Cliristiania 
Basin with the horealis mutation of P. oblongus, and is followed at a 
slightly higher horizon by a mutation of its own, whereas S. lirata does 
not occur till the horizon of the galeatus mutation. 

For purposes of congelation, however, Kiaer notes the position of 
the beds containing the fossils in relation to the deeper-water Graptolite 
Shales. Thus, for example, beneath his zone of BarranddJa undata he 
recognises the zone of C/. normalis, the equivalent of our British zouft 
of Diplog. acummalus, and some little way above his zone of PenUt- 
mcrus ohlongjts he notes the graplolite zone of Cyrtog. Murchisoni, 

'* 1908, Kiaer, J. 'Das Obersilur im Kristianiagebiet.' 


and taking that rightly as representing the base of the Weulock, he 
concludes that all the zones of ' shelly ' beds in between must belong 
to the Valentian. 

In the course of work amongst the rocks of Ordovician age I have 
been struck with distinct evolutional trends amongst some of the com- 
moner trilobites, the stages of wliich have proved valuable as indices 
of age. In illustration of this I may quote two: — 

1. The evolution of the glatella lobes in a species-group of Calymene. 

2. The relation between the segments of the side lobes and axis in 
the pygidia of Encrinurus. 

With regard to the first of these, the evolution of the lobe, two things 
have to be noted : — 

(a) The number of the lobes. 

(b) Their character — i.e. the degree of rounding off into a real lobe. 
The number of lobes appears to increase steadily in proceeding from 

older to newer beds; thus, for example, Silurian forms in general have 
more lobes than those of Ordovician age. The actual character of the 
lobe is to a large extent determined by the state of development, both 
as regards depth and breadth, of the curved glabella furrows. Primarily 
the lobation seems to arise as the necessary result of the development 
of such curvatm-e ; the glabella f m-rows appear to develop gradually in 
width from above downwards, and at the same time increase in breadth; 
the lobation of the basal lobe, for example, is complete when the down- 
ward curvature of the first furrow cuts into the upward curvatui'e of 
ihe neck furrow, and the furrow is deep and broad tkroughout its extent ; 
but before this stage is attained there are many degrees in the develop- 
ment from an incompletely developed furrow through one where, though 
more or less complete, it is still so shallow for a part of its course that 
the lobe is not cut off, but appears definitely attached to the rest of the 
glabella by a ' neck ' or bridge. 

The Calymenidae appear in part at any rate to be derived from the 
Olenidse, and starting with the earliest known Calymene occurring in 
our British rocks of Ordovician age we may note that the general form 
of the glabella is still definitely oval or parabolic in outline, the neck 
fm-row incompletely developed, and the two glabella furrows fairly 
deep but short and oblique, giving more the idea of indenting the general 
outline of the glabella than of cutting off a lobe ; the outer edge of the 
segment too, being still that of the outline of the glabella, is straight ; 
there is, moreover, at this stage no very conspicuous difference in size 
between the two segments, though there is a tendency for the posterior 
pair to be slightly the larger of the two. This is the form known as 
Calymene tristani, which is characteristic of the trilobitic beds imme- 
diately below and associated with the graptolite zone of Didymog. 
extensus. At a slightly higher horizon, that of the graptolite zone of 
Didymog. hirundo, there is found a similar form hardly to be distin- 
guished fi'om C. tristani except for the greater distinction of the basal 
lobe and the curvature of the seco^nd pair of glabella furrows (C parvi- 
frons), whilst another type with a less parabolic glabella more' truncated 
in front makes its first appearance (vav. Murchisoni). Within the 
Ordovician up to this horizon, despite various descriptions hinting the 

C— GEOLOGY. 103 

contrary, I have never observed any Calymene which had any indication 
of more than two glabella segments, but in higher beds the equivalents 
of the zone of Didymog. bifidus there may be detected in some foi-ms, 
otherwise very closely allied to the C. parvifrons of the horizon of the 
zone of Didymog. hirundo, the occasional presence of a third glabella 
furrow; this is, however, always obscure, and its presence is generally 
accompanied by a very definite difference in size in the glabella seg- 
ments, largely induced by the increase in breadth of the furrows, the 
basal segment at this stage being very decidedly the larger. By the 
time the horizon of the Llandilo Limestone is reached (zone of Didymog. 
Murchisoni) this third lobe, minute though it be, is constant and per- 
fectly definite in form ; also the proximal pair of glabella furrows are 
now curved to such an extent that the basal segment may be regarded 
as constituting a pair of basal lobes; the curved furrow is, however, so 
shallow for part of its course in the middle that there is still a distinct 
' neck of attachment.' The so-called bifurcation of the glabella furrow, 
to which much importance has been attached in classification, seems to 
arise as a direct consequence of this tendency to lobation; the lobation 
of the basal segment is not, however, yet complete; there is still 
some angularity on the outer side, the oval parabolic outline of the 
glabella as a whole being still obvious. 

This stage, the development of a basal lobe and the presence of a 
third segment, seems to mark a definite advance and to constitute a^ 
very successful form, for this Calymene, C. cambrensis, is very stable ' 
in its characters in many different kinds of sediment, and has a wide 
distribution in space. In our own countiy it is one of the few trilobites 
found in both the Scotch and Welsh types of the Llandilian. 

All the Calym^enes hitherto dealt with are characterised by the 
possession of a broad frontal region, which has, however, st-eadily 
decreased in size relatively to the glabella, but at this horizon there 
appear to be two forms to both of which the name C. cam'brensis seems 
to have been applied, in one of which thei'e is a far more conspicuous 
diminution in breadth of the margin than in the other, though both 
are at the same stage of evolution as respects their glabella lobes. 
This suggests that the marginal development is going to be a factor 
of importance, and from what happens later it is clear that this is the 
case, and when it takes place some retardation may be expected on the 
older line, either as regards the number of the lobes or as regards the 
perfection of their development. 

In Calymene planimarginafa, the common Caradocian form which 
retains its broad margin, further development on the old lines takes 
place; the third lobe, though still small, becomes more definite; there 
is marked disparity in size as between segments 1 and 2, both of which 
are distinctly more lobate in character, having lost to a large extent the 
ang-ularity of the outer margin, though those specimens characteristic of 
the lower part of the Oaradocian (alternata beds) are distinctly less per- 
fectly lobate than those of the higher chasm.Ofs beds ; in the lower beds 
the third segment, though definite, is not lobate at all, whilst at the 
higher horizon it is lobate but with a definite neck of attachment. Both 
those forms of C. planimarginata are characteristic of the horizon of the 



graptolite zone of Dicranog. clingani, but others also occur showing 
that the hne has begun to branch in various directions leading into 
different species-groups, the details of which have still to be worked 
out. It is, however, clear, I think, that the state of evolution of the 
glabella lobes may afford a valuable index of the age of the beds in 
which it occurs. 

Further investigation is required to show how far this parallel 
evolution takes place at approximately the same time in remote areas 
in different species-groups. So far as I have investigated the problem 
it would appear to be broadly true in the case of the deeper-water 

1. Calymene tristani. 
(Zone of D. extensus.) 

2. Calymene parvifrons. 
(Zone of D. hirundo.) 

3. Calymene parvifrons mut. 
(Zone of D. bifidus.) 

4. Calymene cambrensis. 
(Zone of D. Murchisoni.) 

5. Calymene planimarginata. 
(Zone of Dicranog. clingani.) 

faunas, for so far as the graptohtes are concerned the outstanding stages 
in evolution are reached in the majority of cases at approximately the 
same time along many different routes, thO'Ugh there are some excep- 
tions, for which the reason is, however, usually obvious. So far as 
the Calymcncs are concerned it is of great interest to note that those 
of Bohemia, though constituting a different species-group from those 
found in this country, undergo a precisely similar evolution at the 
same time; thus C. arago of D.l. y shows a. very slight and faint indi- 
cation of a third lobe with a straight outer edge to the glabella, a pre- 
cisely similar stage to that of C. parvifrons in this country; so, too. 



C. parvula of D.d.2. is at a stag© of development similar to that of 
C. cambrensis, as is also C. pulchra at the same horizon in yet another 

It would, I believe, be perfectly possible to adopt a classification of 
the whole of the Ordovician based upon the evolutional sequence of the 
various Calymenes. 

All these facts illustrate that even from the purely palaeontological 
standpoint much field knowledge is essential if a right conception is to 
be gained of the true relationship existing between species and species. 
It appears to be also in the highest degree necessary to view a succes- 
sion of forms like those I have quoted in order to determine what 
characters are really of importance in the recognition of species. 

Also, when lines of evolution result in the attainment of successful 
forms, not only do these appear to be numerically abundant, but it 
would seem also that they have a wide distribution in space. 

So much, then, for a possible line of evolution in the head of a ji 
trilobite; we may next consider the evolution of the pygidium in a 
very different form. An interesting study of this appears to be afforded I 
by the species-group of Encrinurus -punctatus. As is well known in ' 
the commonest type of this trilobite occurring in the Wenlock Lime- 
stone of Dudley, the axis of the pygidium shows a far greater degree 
of segmentation than do the lateral lobes; this may be interpreted 
as implying that numerous segments have been incorporated into the 
tail with a greater degree of fusion in the side lobes than in the axis. 
The species, moreover, is commonly recognised as possessing two well- 
marked varieties, var. arenaceus and var. calcareus, differing chiefly 
from each other in the possession of a definite mucro in var. calcareus, 
which has been interpreted as being connected, with the supply of 
calcareous matter available, but, viewing the species-group as a whole, 
it would seem rather to be the natural culmination or acme of a definite 
tendency to fusion which is developed, with increasing persistence 
throughout its history in time so far as I have been able to study it. 

The earliest forms which I have examined are to be found at the 
horizon of the Stinchar Limestone in Scotland and the Derfel Lime- 
stone of Wales. The graptolite shales associated with these limestones 
prove their age to be Llandilian. At this horizon the relation between 
the segments of the axis and the lateral lobes of the pygidium never 
exceeds 2:1, whilst in the two earliest segments the proportion is very 
clearly 1:1; in the Caradocian the proportion rises to 3 : 1 for segments 
6 and 6, whilst the Ashgillian forms {muliis eg mental us stage) show 
'2 : 1 for segment 2 and still 3:1 for segments 5 and 6. In the Lower 
Valentian segment 4 has risen to 3:1, whilst in the Upper 
Valentian it is commonly the third, though there is some variation, 
since in some cases all that it is possible to make out is that there are 
five segments in the axis compared with two (2 and 3) in the lateral 
lobes. In the succeeding Wenlock forms the culmination is reached with 
3:1 for segments 2-5, and 4:1 at the sixth; in all these later fonns 
there is a tendency to fusion of the later lateral lobes with the axis, 
partially, as in the case of 7 and 8, throughout their length, and more 
definitely at their terminations. 







































'iCaa Aopu^irj ■d[i 









'spag; uBSaawBO 









'spaa IIIH qSnBs 









'spaa THH q^tiBS 









'spaa lOH qsoiinK 






































naxo aAiMqx 
'spajj JiooratnxuQ 









'spaa apBis 









'spaa 3P«IS 














^naa ■BIB a axppjiM 











•^srj jBqonpg 









■(jst; JBqoni^s 









•!>si lajjaa 










Segments on 

side lobes of 






1— 1 






C— GEOLOGY. 107 

The species-group of Encrinurus sexcostatus would appear to show 
a similar evolutional stage at similar horizons, though in this the 
line at present is incomplete. 

Facts such as I have enumerated in the different groups of fossils 
with which we have mainly to deal in Lower Palaeozoic X'ocks show 
that, if viewed from the evolutional standpoint, even the most meagre 
fauna may yet in many cases be made to yield a considerable amount 
of information as to the age of the beds containing it, for the evolu- 
tional succession, once established, can be applied anywhere, and the 
explanation of any apparent anomalies will be more correctly sought 
in the mutual relations of the rocks than in the faunas they contain. 

Moreover, as regards the varying shallow-water faunas, even those 
which have a generally similar aspect may be shown definitely to be 
of different ages when one as a whole contains fossils at a different 
stage of evolution from the other, and the apparent similarity, so 
striking upon superficial examination, will then be regarded as deter- 
mined by physical conditions and not by contempoi-aneity. Working 
on lines such as these we shall be enabled to visualise more definitely 
the conditions which governed the distribution of the different faunas 
in the remote past, and thereby acquire a more accurate conception of 
the changes in physical geography that must have taken place with the 
progress of time. 






Zoology has far outgrown its early boundaries when it could be defined 
simply as a part of natural history, and at no period has its growth 
been more rapid or more productive in results of scientific and practical 
importance than in the interval since our last meeting in this city. 
It is however impossible, even if time permitted, for nny one observer 
to survey the many lines of activity in zoology or to record its contri- 
butions to knowledge in this fruitful period. I have thought it might 
be profitable to endeavour to take in retrospective glance the broad out- 
lines of development of zoology during the last two or tlxree decades, 
and then to limit our further consideration more especially to some of 
the relations of zoology to human welfare. The period under review 
has witnessed a growth of our knowledge of the living organism of the 
same order of im.portance as the progress in our knowledge of the atom. 
Never have investigators probed so deeply or with so much insight into 
the fundamental jDroblems of the living animal ; the means for observa- 
tion and recording have become more delicate, and technique of all 
kinds more perfect, so that we can perceive details of structure and 
follow manifestations of activity of the organism which escaped our 

At the time of the last Liverpool Meeting and for some few years 
previously, a distrust of the morphological method as applied to the 
study of evolution had been expressed by a number of zoologists. At 
that meeting Professor MacBride put forward an able defence of morpho- 
logy while recognising that the morphological method had its limita- 
tions, which must be observed if the conclusions are to rest on safe 
ground. Through undue zeal of some of its devotees morphology had 
been pushed too far on arid and unproductive lines, and rash speculation 
based on unsound morphology brought discredit on this branch of our 
science. It is now fully recognised that the observed resemblances 
between animals are due, some of them to genetic relationships, and 
others to convergent evolution, and therefore that the conclusions 
drawn from the study of morphology are to be interpreted with the 
greatest circumspection. There are some groups of animals, e.g. the 
earthworms, in regard to the evolutionary history of which we can 
never hope to receive help from palaeontology ; we must perforce make 
the best use we can of the morphological method applied, be it under- 
stood, with wide knowledge and deep insight. That careful systematic 
work, coupled with the skilful application of sound morphological 

1).— ZOOLOGY. 109 

principles, is capable of yielding results of specific and general import- 
ance is well illustrated by the researches of Michaelsen and of Stephen- 
son on Indian Oligochaetes ; these authors have been able to trace the 
lines of evolution of the members of the family Megascolecidae so com- 
pletely that we know their history as well as we know that of the 
Equidse. Again, to take an example from a different category, the fine 
morphological work on the cell and on the nucleus and its chromosomes 
which we owe to Hertwig, Flemming, Boveri, van Beneden, Wilson 
and others, made possible the modern researches and conceptions in 
regard to inheritance and sex. The danger that morphology will be 
pushed to excess is long past ; the peril seems to me to be rather in the 
opposite direction, i.e. that some of our students before passing on to 
research receive too little of that training and discipline in exact morpho- 
logy by which alone they can be brought to appreciate how the com- 
ponents of the living organism are related to one another and to those 
of allied species or genera, and how they afford, with proper handling, 
many data for the evolutionist. I plead, therefore, for the retention 
of a sound and adequate basis of morphology in our zoological courses. 

No one who engages in the study of morphological problems can 
proceed far without meeting questions which stimulate enquiry of a 
physiological nature, and, where means are available, resort to experi- 
mental procedure is the natural mode of arriving at the answer. That 
morphology is detrimental to or excludes experimental or physiological 
methods is entirely contrary to present day experience, and indeed the 
fruitfulness of the combination of morphology and physiology could 
have been amply illustrated any time during the last eighty years simply 
by reference to the work of Johannes Miiller. The structure of an 
organism must be known before its co-ordinat«d movements can be 
adequately appreciated — morphology must be the forerunner of 

Another of the basal supports of our science an appreciation of 
which, or better still a training in some branch of which, we must 
encourage is the systematic or taxonomic aspect. The student or 
graduate who is proceeding to specialise in experimental zoology or in 
genetics particularly requires a sound appreciation of the fact that the 
accurate determination of the genus and species under investigation is 
a primary requisite for all critical work — it- is part of the fundamental 
data of the experiment and is essential, if for nothing else, to permit 
subsequent observers to repeat and perhaps to extend any given series 
of observations. Moreover, the systematic position of an animal is an 
expression of the final summary of its morphology and its genetic 
relationships, and it is from such summaries that we have to attempt 
in many cases — as, for example, in the Oligochaetes already cited — to 
discover in a restricted group or order the probable course of evolution, 
though the method of evolution may not be ascertainable. From these 
summaries prepared by systematists issue problems for the experimental 
evolutionist and the geneticist. As Mr. Bateson has pointed out. it is 
from the systematist who ' has never lost the longing for the truth 
about evolution that the raw materials for genetical researches are to 
be drawn, and the separation of the laboratory men from the systematists 
imperils the work and the outlook of both. 


Among the notable features of zoological activity during the last 
twenty-five years the amount of work on the physiology of organisms 
other than mammals must attract early notice in any general survey of 
the period. Eighty years ago Johannes Miiller's physiological work 
was largely from the comparative standpoint, but for some years after 
his death ihe comparative method fell into disuse, and the science of 
physiology was concerned chiefly with the mode of action of the organs 
of man or of animals closely related to man, the results of which have 
been of outstanding importance from their bearing on medicine. Interest 
in the more general applications of physiology was revived by Claude 
Bernard (' Le9ons sur les phenomenes de la vie,' 1878), and the appear- 
ance of Max Verworn's ' General Physiology,' in 1894, was in no incon- 
siderable measure responsible for the rapid extension of physiological 
methods of enquiry to the lower organisms — a development which has 
led to advances of fundamental importance. Many marine and fresh- 
water organisms lend themselves more readily than the higher verte- 
brates to experimentation on the effects of alterations in the surround- 
ing medium, on changes in metabolic activity, on the problems of 
fertilisation and early development, on the chemistry of growth and 
decline, and to the dii'ect observation of the functioning of the individual 
organs and of the effects thereon of different kinds of stimuli. The 
study of these phenomena has greatly modified our interpretation of 
the responses of animals and has given a new impetus to the investiga- 
tion of the biology and habits of animals, i.e. animal behaviour. This 
line of work — represented in the past by notable contributions such as 
those by Darwin on earthworms, and by Lubbock on ants, bees and 
wasps — has assumed during the last two or three decades a more 
intensive form, and has afforded a more adequate idea of the living 
organism as a working entity, and revealed tTie delicacy of balance 
which exists between structure, activity and environment. This closer 
correlation of form, function and reaction is of the greatest value to 
the teacher of zoology, enabling him to emphasise in his teaching that 
for the adequate appreciation of animal structure a clear insight into 
the activities of the organism as a living thing is essential. 

The penetrating light of modern investigation is being directed into 
the organism from its earliest stage. During the summer of 1897 
Morgan discovered that the eggs of sea-urchins when placed in a two 
per cent, solution of sodium chloride in sea-water and then transferred 
to ordinary sea-water would undergo cleavage and give rise to larv;n, 
and J. Loeb's investigations in this field are familiar to all students of 
zoology. Artificial parthenogenesis is not restricted to the eggs of 
invertebrates, for Loeb and others have shown that the eggs of frogs 
may be made to develop by pricking them with a needle, and from such 
eggs frogs have been reared until they were fourteen months old. The 
application of the methods of microdissection to the eggs of sea-urchins 
is leading to a fuller knowledge of the constitution of the egg, of the 
method of penetration of the spenn, and of the nuclear and cytoplasmic 
phenomena accompanying maturation and fertilisation, and will no 
doubt be pursued with the object of arriving at a still closer analysis of 
the details of fertilisation. 



The desire for more minute examination of developing embryos led 
to the more careful study of the egg-cleavage, so that in cases suitable 
for this method of investigation each blastomere and its products were 
followed throughout development, and thus the individual share of the 
blastomere in the cellular genesis of the various parts of the body was 
traced. This method had been introduced by Whitman in his thesis 
on Clepsine (1878), but it was not until after the classical papers of 
Boveri on Ascaris (1892) and E. B. Wilson on Nereis (1892) that it 
came into extensive use. About the time of our last meeting here, and 
for the next twelve or fifteen years, elaborate studies on cell-lineage 
formed a feature of zoological literature and afforded precise evidence 
on the mode of origin of the organs and tissues, especially of worms, 
molluscs and ascidians. A further result of the intensive study of egg- 
cleavage has been to bring into prominence the distinction between 
soma-cells and germ-cells, which in some animals is recognisable at a 
very early stage, e.g. in Miastor at the eight-cell stage. The evidence 
from this and other animals exhibiting early segregation of germ-cells 
supports the view that there is a germ-path and a continuity of germ- 
ceils, but the advocates of this view are constrained to admit there are 
many cases in which up to the present an indication of the early differen- 
tiation of the gei'm-cells has not been forthcoming on investigation, and 
that the principle cannot be held to be generally established. 

A cognate line of pi'ogress which, during the period under review, 
has issued from the intensive study of the egg and its development is 
experimental embryologv — devoted to the experimental investigation of 
the physical and chemical conditions which underlie the transformation 
of the egg into embrvo and adult. By altering first one and then another 
condition our knowledge of development has been greatly extended, by 
artificial separation of the blastomeres the power of adjustment and 
regulation during development has been investigated, and by further 
exploration of the nature of the egg the presence of substances fore- 
shadowing the relative propoi'tions and positions of future organs has 
been revealed in certain cases, the most striking of which is the e^^ of 
the Ascidian Cynthia partita (Conklin, 1905). Still further intensive 
study of the cytoplasm and nuclei of eggs and cleavage stages is required 
to throw light on the many problems which remain unsolved in this 

Progress in investigation of the egg has been paralleled by increase 
in oiu' knowledge of thp germ-cells, especially during their maturation 
into eggs and sperms, the utmost refinements of technique and observa- 
tion having been brought to bear on these and on other cells. During 
the last thirty years, and especially during the latter half of this period, 
cytologv has developed so rapidlv that it has become one of the most 
important branches of modern biology. One of the landmarks in its 
nrogress was the appearance, at the end of 1896. of E. B. Wilson's 
book on ' The Cell,' and we look forward with great expectations to the 
new edition which, it is understood, is in an advanced stage of prepara- 
tion. A great stimulus to cytological work resulted from the rediscoverv 
i" 1900 of the principle of hevpditv published bv M^^ndpl in ISfi.'i wh'Vh 
fallowed that a relatively simple onnceptfon wns siiflirient to fxpl.iin Ihf 

192.3 K 


method of inheritance in the examples chosen for his experiments, for 
in 1902 Sutton pointed out that an application of the facts then known 
as to the behaviour of the chromosomes would provide an explanation 
of the observed facts of Mendelian inheritance. In the same year 
McClung suggested that the accessory chromosome in the male germ- 
cells is a sex-determinant. These two papers may be taken as the 
starting-point of that vast series of researches which have gone far 
toward the elucidation of two of the great problems of biology — the 
structural basis of heredity and the nuclear mechanism correlated with 
sex. The evidence put forward by Morgan and his colleagues, resulting 
from their work on Drosophila, would seem to permit little possibility 
of doubt that factors or genes are carried in the chromosomes of the 
gametes, and that the behaviour of the chromosomes during maturation 
of the germ-cells and in fertilisation offers a valid explanation of the 
mode of inheritance of characters. The solution of this great riddle of 
biology has been arrived at through persistent observation and experi- 
ment and by critical analysis of the results from the point of view of 
the morphologist, the systematist, the cytologist, and the geneticist. 

Among other important developments in the period, reference may 
be made to the great activity in investigation of the finer structure of 
the nerve-cell and its processes. By 1891 the general anatomical rela- 
tions of nerve-cells and nerve-fibres had been cleared up largely through 
the brilliant work of Golgi and Cajal on the brain and spinal cord, and 
of von Lenhossdk, Retzius, and others on the nervous system of annelids 
and other invertebrates. In these latter had been recognised the receptor 
cells, the motor or effector cells, and intermediary or internunciary 
cells interpolated between the receptors and effectors. In June 1891 
Waldeyer put forward the neurone theorv, the essence of which is that 
the nerve-cells are independent and that the processes of one cell, though 
coming into contiguous relation and interlacing with those of another 
cell, do not pass over into continuity. He foimded his views partly 
upon evidence from embryological researches by His, but chiefly on 
results obtained from Golgi preparations and from anatomical investiga- 
tions by Cajal. The neurone theory aroused sharp controversy, and 
this stimulus turned many acute observers — zoologists and histologists — 
to the intimate study of the nerve-cell. First among the able opponents 
of the theorv was Apathy, whose well-known paper, published in 1897. 
on the conducting element of the nervous system and its topographical 
relations to the cells, first m.ade known to us the presence of the neuro- 
fibrillar network in the body of the nerve-cell and the neurofibrils in the 
cell-processes. Apdthy held that the neurofibrillar system fomned a 
continuous network in the central nervous system, and he propounded 
a new theory of the constitution of the latter, and was supported in 
his opposition to the neurone theory by Bethe. Nissl, and others. The 
controversy swune to and fro for some years, but the neurone theory — 
with certain modifications — seems now to have established itself as a 
working doctrine. The theory first enimciated as the result of morpho- 
logical studies receives support from the experimental proof of a slieht 
arrest of the nerve-impulse at the synapse between two neurones, which 
causes a measurable delay in the transmission. The latest development 

■p.— ZOOLOGY. 113 

in morphological work on nerve-elements is iho investigation of thf 
neuromotor system in the Protozoa. Sharp (1914), Yocom (1918), and 
Taylor (1920), working in Kofoid's laboratory, have examined this 
mechanism in the ciliates Diplodinium and Euplotes and they describe 
and figure a mass — the neuromotorium — from which fibrils pass to the 
motor organs, to the sensory lip, and, in Diplodinium, to a ring round 
the oesophagus. The function of the apparatus is apparently not sup- 
porting or contractile, but conducting. By the application of the 
finest methods of micro-dissection specimens of Euplotes have been 
operated upon while they were observed under an oil-immersion objec- 
tive. Severance of the fibres destroyed co-ordination between the mem- 
bra.nelles and the cini, but other incisions of similar extent made 
without injuring the fibrillar apparatus did not impair co-ordination, 
and experiments on Paramsecium by Eees (1922) have yielded similar 
results. While the experimental evidence is as yet less conclusive than 
the morphological, it supports the latter in the view that the fibrils have 
a conducting, co-ordinating function. Progress in our knowledge of 
the nervous system is but one of many lines of advance in our under- 
standing of the correlation and regulation of the component parts of 
the animal organism. 

The ciliate protozoa have been the subject during the last twenty 
years of a series of investigations of great interest, conducted with the 
purpose of ascertaining whether decline and death depend on inherent 
factors or on external conditions. While these researches have been 
in progress we have come to realise more fully that ciliatos are by no 
means simple cells, and that some of them are organisms of highly 
complex structure. Twenty years ago Calkins succeeded in maintaining 
a strain of Parameecium for twenty-thi-ee months, during which there 
were 742 successive divisions or generations, but the strain, which had 
exhibited signs of depression at intervals of about three months, finally 
died out, apparently from exhaustion. From this work, and the pre- 
vious work of Maupas and Hertwig, the opinion became general that 
ciliates are able to pass through only a limited number of divisions, 
after which the animals weaken, become abnormal and die, and it was 
believed that the only way by w-liich death could be averted was by a 
process of mating or conjugation involving an interchange of nuclear 
material between the two conjugants and resulting in a complete re- 
organisation of the nuclear apparatus. Jennings has show-n that con- 
jugation is not necessarily beneficial, that the ex-conjugants vary greatly 
in vitality and reproductive power, and that in most cases the division 
rate is less than before conjugation. Woodruff has since May 1, 1907, 
kept under constant conditions in culture a race of Paramaecium. 
During the sixteen years there have been some ten thousand generations, 
and there seems no likelihood of or reason for the death of the race so 
long as pi'oper conditions are maintained. The possibility of conjuga- 
tion has been precluded by isolation of the pi'oducts of division in the 
main line of the culture, and the conclusion is justifiable that conjuga- 
tion is not necessary for the continued life of the organism. The 
criticism that Woodruff's stock might be a non-conjugating race wa? 
met bv placing the Paramfpcia, left r^v^x from the direct line of culture 

K 2 


under other conditions when conjugation was found to occur. Later 
obsen-ations by Erdmann and Woodnaff show that a reorganisation of 
the nuclear apparatus of Paramaecium takes place about every twenty- 
five to thirty days (forty to fifty generations). Tliis process, termed 
endomixis (in contrast to amphimixis), seems to be a normal event in 
the several races of Paramaecium which Erdmann and Woodruff have 
examined, and it is proved to coincide with the low points or depressions 
in the rhythm exhibited by Paramaecium. The occurrence of endomixis 
raises the question, to which at present there is no answer, as to whether 
this process is necessary for the continued health of the nuclear 
apparatus and of the cytoplasm of Paramaecium. 

Enriques (1916) maintained a ciliate — Glaucoma ■pyriformis — 
through 2,701 generations without conjugation, and almost certainly 
without endomixis. From a single ' wild ' specimen he raised a large 
number and found that conjugating pairs were abundant, so that the 
objection could not be made that this was a non-conjugating race. 
Em-iques then began his culture with one individual, and examined the 
descendants morning and evening, removing each time a specimen for 
the succeeding culture. The number of divisions per day varied from 
nine to thirteen, and as there was no break in the regularity and rapidity 
of division, and no sort of depression, Eni'iques concluded that neither 
endomixis nor conjugation could have occurred, for these processes take 
some time and would have considerably reduced the rate of division. 
These results, especially if they are confirmed by cytological study of 
preserved examples, show that for Glaucoma neither conjugation nor 
endomixis is necessary for continued healthy existence. Hartmann's 
observations (1917) on the flagellate F,uclnr'ma eleaans extend the con- 
clusion to another class of Protozoa. He followed this flagellate thi'ough 
550 generations in two and a-half years. The mode of reproduction 
was purely asexual, and there was no depression and no nuclear re- 
organisation other than' that following fission. The evidence seems 
sufficient to confirm the view that certain Protozoa, if kept under favour- 
able conditions, can maintain their vigour and divide indefinitely, without 
either amphimixis or endomixis. 

Child (1915^) states as the result of his experiments that the rate of 
metabolism is highest in Paramfecium and other ciliates immediately 
after fission — ' in other words, after fission the animals are physiolo- 
gically younger than before fission.' This view, that rejuvenescence 
occurs with each fission, derives support from the observations of 
Em-iqucs and Hartmann, for no other process was found to be taking 
place and vet the vigour of their oi'ganisms in culture was unimpaired. 
If, then, fission is sufficiently frequent — that is, if the conditions for 
growth remain favourable — the protoplasm maintains its vigour. If 
through changes in the external conditions the division rate falls, the 
rejuvenescence at each fission mav not be sufficient to balance the 
deterioration taking place between the less frequent divisions. TJnder 
such conditions endomixis or conjugation may occur with beneficial 
results in some cases, but if these procppses are precluded there is 
nT)ri^i''^nt1v pot-iiincr to arrest thp progressive decline or ' ageing ' obsprvorl 
bv ivlq-up^s aP''! otliprc?. But fnrthpr invo^l-isrations are rennirpd on the 
physiology and morphology of decline in the protozoan individual. 


D.— ZOOLOGY. 115 

The culture of tissues outside tiie body is throwing new light ou the 
conditions requisite for the multiplication and diffeientiation of cells. 
R. G. Harrison (1907) was the first to devise a successful method by 
which the growth of somatic cells in culture could be followed under 
the microscope, and he was able to demonstrate the outgrowth of nerve- 
fibres from the central nervous tissue of the frog. Burrows (1911), 
after modifying the technique, cultivated nervous tissue, heart-cells, 
and mesenchymatous tissue of the chicli in blood-plasma and embryonic 
extract, and this method has become a well-established means of 
investigation of cell-growth, tissues from the dog, cat, rat, guinea-pig, 
and man having been successfully grown. One strain of connective 
tissue-cells (fibroblasts) from the chick has been maintained in culture 
in vigorous condition for more than ten years, that is for probably some 
years longer than would have been the normal length of life of the cells 
in the fowl. Heart-cells may be grown generation after generation — all 
traces of the original fragment of tissue having disappeared — the cells 
forming a thin, rapidly growing, pulsating sheet. Drew (1922) has 
recently used instead of coagulated plasma a fluid medium containing 
calcium salts in a colloidal condition, and has obtained successful growth 
of various tissues from the mouse. He finds that epithelial cells when 
growing alone remain undifferentiated, but on the addition of connective 
tissue differentiation soon sets in, squamous epithelium producing 
keratin, mammary epithelium giving rise to acinous branching struc- 
tures, and when heart-cells grow in proximity to connective tissue they 
exhibit typical myofibrillse, but if the heart-cells grow apart from the 
connective tissue they fox'm spindle-shaped cells without myofibrillas. 
This study of the conditions which determine the growth and diffei-entia- 
tion of cells is only at the beginning, but it is evident that a new line 
of investigation of great promise has been opened up which should lead 
also to a knowledge of the factors which determine slowing do^^'n of the 
division-rate and the cessation of division, aird finally the complete 
decline of the cell. 

For many lines of work in modern zoology biochemical methods are 
obviously essential, and the applications of physics to biology are like- 
wise highly important — e.g. in studies of the form and development of 
oi'ganisms and of skeletal structures. Without entering into the vexed 
question as to whether all responses to stimuli are capable of explanation 
in terms of chemistry and physics, it is very evident that modern develop- 
ments have led to the increasing application of chemical and physical 
methods to biological investigation, and consequently to a closer union 
between biology, chemisti-y, and physics. It is clear also that the 
association of zoology with medicine is in more than one respect 
becoming progressively closer — comparative anatomj' and embryology, 
cytology, neurology, genetics, entomology, and parasitology, all have 
their bearing on human welfare. 

Some Bearing's of Zoology on Human Welfare. 

The bearings of zoology on human welfare — as illustrated by the 
relation of insects, protozoa and helminthes to the spread or causation 
of disease in man — have become increasingly evident in these later years 


and ,1,'e familiar to every student of zoology or of medicine. At the 
tim/, of our last meeting in Liverpool, insects were suspected of acting 
as transmitters of certain pathogenic organisms to man, but these cases 
v\^ere few and in no single instance had the life-cycle of the organism 
been worked out and the mode of its transmission from insect to man 
ascertained. The late Sir Patrick Manson, working in Amoy, had shown 
(1878) that the larvae of Filaria bancrofti undergo growth and metamor- 
phosis in mosquitoes, but the mode of transference of the metamorphosed 
larvae was not determined until 1900. Nearly two years after our last 
meeting here the part played by the mosquito as host and transmitter of 
the parasite of malaria was made known by Eoss. In addition to these 
two cases at least eight important examples can now be cited of arthro- 
pods proved to act as carriers of pathogenic organisms to man — e.g. 
Stegomyia — yellow fever, Phlebotomus — sandfly fever, tsetse-flies — 
sleeping sickness, Conorhinus — South American trypanosomiasis 
(Chagas' Disease), Chrysops — Filaria (Loa) loa, the flea Xenopsylla 
cheopis — plague, the body-louse — trench fever, relapsing fever and 
typhus, and the tick Ornithodorus — Afiican relapsing fever. In select- 
ing examples for brief consideration I propose to deal very shortly with 
malaria, although it is the most important of the insect-carried diseases, 
because the essential relations between the Anopheles mosquito and the 
parasite are known to everyone here. There still remain lacunae in our 
knowledge of the malarial organisms. Eoss and Thomson (1910), 
working in this city, showed that asexual forms of the parasite tend to 
persist in small numbers between relapses, and suggested that infection 
is maintained by these asexual stages. Such explanation elucidates 
those cases in v/hich relapses occur after short intervals, but the recur- 
rence of the attacks of fever after long intervals can only be explained 
by assuming that the parasites lie dormant in the body — and we know 
neither in what part of the body nor in what stage or condition they 
persist. Nevertheless, the cardinal points about the organism are estab- 
lished, and preventive measures and methods of attack based on a 
knowledge of the habits and bionomics of Anopheles have been fruitful 
in beneficial results in many parts of the world. 

If we desire an illustration of the vast difference to human well-being 
between knowing and not knowing how a disease-germ is transmitted 
to man, we may turn to the case of yellow fever. When this pestilence 
came from the unknown, and no one knew how to check it, its appear- 
ance in a community gave rise to extreme despair and in many cases 
was the signal for wholesale migration of those inhabitants who could 
leave the place. But with the discovery that Stegomyia was the trans- 
mitting agent all this was changed. The municipality or district took 
steps to organise its preventive defences against a now tangible enemy, 
and the successful issue of these efforts, with the consequent great saving 
of life and reduction of human suffering in the Southern United States, 
in Panama, in Havana and in other places, is common knowledge. 
It is a striking fact that diuring 1922 Central America, the West Indies, 
and all but one country of South America were free from yellow fever, 
which has ravaged these regions for nearly two centuries. The cam- 
paign against Stegomyia is resulting, as a recent Eockefeller report 


D.— ZOOLOGY. 117 

points out, in yellow I'ever being restricted to rapidly diminishing, 
isolated areas, and this disease seems to be one which by persistent effort 
can be brought completely under control. 

In 1895 Bruce went to Zululand to investigate the tsetse-fly disease 
which had made large tracts of Africa uninhabitable for stock, and 
near the end of the same year he issued his preliminary report in which 
he showed that the disease was not caused by some poison elaborated 
by the fly — as had been formerly believed — but was due to a minute 
flagellate organism, a trypanosome, conveyed from affected to healthy 
animals by a tsetse-fly (Glossina morsitans). In 1901 Forde noticed 
an active organism in the blood of an Englishman in Gambia suffering 
from irregularly intermittent fever, and Dutton (1902) recognised it 
as a trypanosome, which he named Trypanosoma gambiense. In 1902 
Castellani found trypanosomes in the blood and cerebro-spinal fluid of 
natives with sleeping sickness in Uganda, and suggested that the 
trypanosome was the causal organism of the disease. The Sleeping 
Sickness Commission (Bruce and his colleagues) confirmed this view, 
and showed that a tsetse-fly, Glossina palpalis, was the transmitter. 
Since then much has been learnt regarding the multiplication of the 
trypansosome in the fly and its transference to man. For some years 
this was believed to take place by the direct method, but in 1908 Kleine 
demonstrated * cyclical ' transmission, and this was shown later to be 
the principal means of transference of T. gambiense. In 1910 
Stephens and Fantham described from an Englishman, who had 
become infected in Ehodesia, a trypanosome which, from its morpho- 
logical characters and greater virulence, they regarded as a new species, 
T. rhodesiense, and its ' cyclical ' transmission by Glossina 7noTsitans 
was proved by Kinghorn and Yorke. Eecent reports by Duke 
and Swynnerton (1923) of investigations in Tanganyika Territory suggest 
that direct rather than cyclical transmission by a new species of Glossina 
is there mainly responsible for the spread of a trypanosome of the 
rhodesiense type. The impossibility of distinguishing by their morpho- 
logy what are considered to be different species of trypanosomes, and 
the difficulty of attacking the fly, are handicaps to progress in the 
campaign against sleeping sickness, which presents some of the most 
subtle problems in present day entomology and protozoology. Here 
also we come upon perplexing conditions due apparently to the different 
vii'ulence of separate strains of the same species of trypanosome and 
the varying tolerance of individual hosts — on which subjects much 
further work is required. 

The relation of fleas to plague provides one of the best and most 
recent illustrations of the necessity for careful work on the systematics 
and on the structure and bionomics of insects concerned in carrying 
pathogenic organisms. Plague was introduced into Bombay in autumn 
1896, and during the next two years extended over the greater part 
of Bombay Presidency and was carried to distant provinces. The Indian 
Government requested that a Commission should be sent out to investi- 
gate the conditions. This Commission, which visited India in 1898-99, 
came to the conclusion (1901) that rats spread plague and that infection 
of man took place through the skin, but — and this is amazing to us at 


the present day — ' that suctorial insects do not come under consideration 
in connection with the spread of plague. ' Further observations, how- 
ever, soon showed this conclusion to be erroneous. Liston found in 
Bombay in 1903 that the common rat-flea was Pulex (Xenopsylla) 
cheopis, that it was present in houses in which rats had died of plague 
and in which some of the residents had become infected, that the plague- 
bacillus could multiply in the stomach of this flea, and that the flea would 
— in the absence of its usual host — attack man. These observations 
pointed to the importance of this flea in the dissemination of plague, 
and the Second Plague Commission, which was appointed and began 
work in 1905, definitely proved that Xenopsylla cheopis is the trans- 
mitter of the plague-organism from rat to rat and from rat to man. 
The mechanism of transmission of the plague-bacillus was worked out 
by Bacot and Martin in 1913. They showed that in a proportion of 
these fleas fed on the blood of septicsemic mice the plague-bacilli 
multiply in the proventriculus — which is provided with chitinous pro- 
cesses that act as a valve to prevent regurgitation of the blood from 
the stomach — and a mass of bacilli is formed which blocks the proven- 
triculus and may extend forward into the oesophagus. Fleas in this 
condition are not prevented from sucking blood because the pharynx 
is the suctorial organ, but their attempts to obtain blood result only in 
distending the oesophagus. The blood drawn into the oesophagus is 
repeatedly forced backwards into contact with the mass of plague-bacilli 
and on the sucking action ceasing some of this infected blood is expelled 
into the wound. The transmission of plague depends on the peculiar 
structure of the proventriculus of the flea and on the extent to which, 
in certain examples, the plague-bacilli multiply in the proventriculus. 
Such ' blocked ' fleas being unable to take blood into the stomach are 
in a starved condition, and make repeated attempts to feed, and hence 
are particularly dangerous. 

Until 1913 it was believed that all the fleas of the genus Xenopsylla 
found on rats in India belonged to one species — cheopis, but in that 
year L. F. Hirst reported that the rat-flea of Colombo was X. astia, 
which had been taken off rats in Rangoon, and described by N. 0. Eoth- 
schild in 1911. Hirst ascertained that this flea did not readily bite man 
if the temperature were above 80° F. A collection of 788 fleas from 
Madras City proved to consist entirely of X. astia, and Hirst suggested 
that the explanation of the immunity of Madras and Colombo from 
plague was the relative inefficiency of X. asiia as a transmitter. Cragg's 
examination (1921, 1923) of 23,657 fleas obtained from rats in all parts^ 
of India shows that they include three species of Xenopsylla — ^namely, 
cheopis, astia, and brasiliensis. This last species is common in the 
centraland northern uplands of peninsular India, but its bionomics 
have not yet been investigated. Cheopis is the predominant species 
in the plague areas, while astia is the common flea in those areas which 
have remained free from plague or have suffered only lightly. In 
Madras City, for instance, during the twenty-one years, 1897-1917,' 
plague has occurred in twenty of these years, but the average mortality 
was only .013 per thousand — that is, though the infection has been 
repeatedly introduced there, it failed each time to set up an epidemic. 



The significance of an imported case of plague depends in large measure 
on the local species of Xenopsylla. Hirst has made numerous attempts 
during the plague season in Colombo to transmit plague by means of 
X. astia from rat to rat, but with negative results, and X. astia, was 
never found to behave like a ' blocked ' cheopis. 

The distinction of X. cheopis from X. astia is not an entomological 
refinement with purely systematic significance, bub corresponds with a 
different relation of the species to the epidemiology of plague, and 
hence becomes a factor of great practical importance. If through these 
researches it has become possible by examination of the rat-fleas of a 
locality to estimate accurately its liability to plague, anti-plague 
measm^es may henceforward be restricted to those areas in which plague 
is Hkely to occur, i.e. where cheopis is the predominant flea. Thus a 
great economy of effort and of expenditm'e and a higher degree of 
efficiency may be achieved; in fact, the problem of the prevention or 
reduction of plague may be brought from unwieldy to practicable pro- 
portions. When it is remembered that since we last met in Liverpool 
some ten and a quarter millions of people have died in India from 
plague we have a more than sufficient index of the importance of a 
precise knowledge of the systematics, structure, and bionomics of the 
insect-carrier of Bacillus pestis. 

Another of the outstanding features of the period under review has 
been the extensive and intensive study of the Protozoa. The structure 
and the bionomics and life-history of these organisms have been investi- 
gated with the help of the finest developments of modern technique. 
It is fitting here to record our acknowledgment to two staining methods — 
Heidenhain's iron-haematoxylin and the Eomanowsky stain (including 
Giemsa's and Leishman's modifications), which have added greatly to 
our technical resources. 

There is time to refer only to certain of the Protozoa which directly 
affect man. Twenty years ago our knowledge of the few species of 
Protozoa recorded from the human alimentary canal was defective in 
two important respects — the systematic characters and the biology of 
the species — so there was much confusion. Subsequent investigations, 
and especially those of the last ten years (by Wenyon, Dobell, and 
others), have cleared up most of the doubtful points, but owing to the 
difficulties of size and the paucity of characters available it is by no 
means easy in practice to distinguish certain of the species. Of the 
seventeen species now known to occur in the intestine of man 
Entamosba histohjtica has received particular attention. This organism 
lives as a tissue parasite in the wall of the large intestine, where, as a 
rule, the damage caused is counterbalanced by the host's regenerative 
processes. But when the destruction outstrips the regeneration intes- 
tinal disturbance i-esults, leading to the condition known as amcebic 
dysentery. The specific characters and the processes of reproduction 
and encystment of E. histolytica are now well ascertained, and it is 
realised that in the majority of cases the host is healthy, acting as a 
' carrier ' dangerous to himself, for he may develop into a case 
of acute dysentery, and to the community — for he is passing in his 


faeces tlie encysted stage which is capable of infecting other persons. 
Whether an infected person will suffer from dysentery or act as a 
healthy ' carrier ' apparently depends upon his own susceptibility rather 
than on any difference in the virulence of different strains of the 

In all work with human Entamoebse there is need for critical deter- 
mination of the species, for, in addition to E. histolytica, a closely 
similar species, £'. coli, is a common inhabitant of the intestine. This, 
however, is a harmless commensal, feeding on bacteria and fragments 
derived from the host's food. The distinction between the two species 
rests chiefly upon the characters of the nuclei and of the mature cyst — 
quadrinucleate in histolytica and octonucleate in coli — and considerable 
care and technical skill are requisite in many cases before a diagnosis 
can be given. And yet this distinction is definitely necessary in prac- 
tice, for indiscriminate treatment of persons with Entamceba is indefen- 
sible; treatment is only for those with histolytica; it is useless for those 
with coli, and subjects them needlessly to an unpleasant experience. 

A notable result of recent work is the proof that the more common 
intestinal Protozoa, formerly believed to be restricted to warmer coun- 
tries, occur indigenously in Britain. This was first established by a 
group of observers in this city, and has been confirmed and extended by 
subsequent workers. There is good reason for believing that in this 
country the incidence of infection with E. histolytica is about 7 to 
10 per cent., and with E. coli about five times as great (Dobell). 

The discovery (1903) of Leishmania, the organism of kala azar and 
of oriental sore, added another to the list of important human patho- 
genic Protozoa, but the mode of transmission of this flagellate has not 
yet been proved. 

Of the problems presented by the parasitic worms the most momen- 
tous are those associated with Ancylostoma and its near relative 
Necator, which are prevalent in countries lying between 36° N. and 
30° S. — a zone which contains more than half the population of the 
earth. Heavy infection with Ancylostoma or v/ith Necator produces 
severe ansemia, and reduces the host's physical and mental efficiency 
to a serious degree. Until 1898 there was no suggestion that infection 
was acquired in any other way than by the mouth, but in that year Loess 
pubHshed his fii'st communication on the entry of the larvae of Ancy- 
lostoma through the skin, and in 1903 gave an account of further experi- 
ments which proved that dermal infection resulted in the presence 
of worms in the intestine. At the meeting of this Association in Cam- 
bridge in 1904 Looss demonstrated to a small company his microscopical 
preparations showing the path of migration of the larvae. His investiga- 
tions sei-ved to establish the importance of the skin as the chief portal 
of entry of Ancylostoma, and pointed the way to effective methods of 
prevention against infection. 

Another notable advance in helminthology is the working out of the 
life-cycle of Schistosoma (Bilharzia)— a genus of trematode worms 
causing much suffering in Egypt and elsewhere in Africa, as well as 



in Japan and other parts of the world. These worms when mature hve 
in pairs, a male and female, in the veins of the lower part of the 
abdomen, especially in the wall of the bladder and of the rectum. The 
eggs, laid in large numbers by the female worm, provoke inflammatory 
changes, and cause rupture of the veins of the organs invaded. Until 
about ten years ago the life-history of Schistosoma had been traced 
only as far as the hatching of the ciUated larva or miracidium which 
takes place shortly after the egg reaches water, but it was then shown 
that this larva is not, as had been held by Looss, the stage which infects 
man. Miyairi and Suzuki (1913) found that the miracidium of Schisto- 
soma japonicurn entered a fresh-water snail which acted as the inter- 
mediate host, and Leiper and Atkinson (1915) confii-med and extended 
this observation, and showed that the miracidia develop into sporocysts 
in which cercarise are formed. We owe chiefly to Leiper's work (1915- 
1916) our knowledge of the life-history and method of entry into man 
of the Egyptian species of Schistosoma. He demonstrated that two 
species of this parasite occur in Egypt, and established that the miracidia 
develop in different intermediate hosts: those of S. viansoni enter 
Planorbis, while those of S. hcBmatohium penetrate into BuUinus — the 
molluscs being abundant in the irrigation canals. The sporocysts 
produce cercariae, which escape from the snails and gather near the 
surface of the water, and experiments with young mice and rats showed 
that the cercariae attach themselves to the skin, enter, and reach the 
portal system from which they travel to the veins of the lower part 
of the abdomen. Infection of man takes place chiefly through the skin 
when bathing or washing in water containing the cercariae, though infec- 
tion may also occur through drinking such water. And so, at last, 
these worms which have troubled Egypt for at least thirty centuries 
have become known in all their stages, and measures for preventing 
infection — which were of great use during the War — have been devised, 
and curative treatment introduced. 

Other recent helminthological researches deserve consideration did 
time permit, for there has been much excellent work on the life-history 
of the liver-flukes and lung-flukes of man, and the life-cycle of the 
tape-worm, Dibothriocephalius latus, was worked out in 1916-17. 
Mention should also be made of Stewart's investigations (1916-19) on 
the life-histoi-y of the large round-worm Ascaris lumbricoides, during 
which he made the important discovery that the larvae on hatching in 
the intestine penetrate into the wall and are carried in the blood to the 
liver, and thence through the heart to the lungs, where they escape from 
the blood-vessels, causing injuiy to the lungs. The larvae, now about 
ten times their original size, migrate by way of the trachea and pharynx 
to the intestine, where they grow to maturity. During last year Dr. 
and Mrs. Connal have worked out the life-history of Filaria (Loa) loa 
in two species of the Tabanid fly, Chrysops, and investigations on other 
Filarias have thrown light on their structure, but there is still need for 
further researches on the conditions governing the remarkable periodi- 
city exhibited by the larvae of some species (e.g. F. bancrofti; in some 
parts of the world the larvae of this species are, however, non-periodic). 
The period under review has obviously been one of great activity in 


researcli on lielinintlies, and feitile in measures tending to reduce tlis 
risks of infection. 

Insects, protozoa and helminthes not only inflict direct injury on 
man; they also diminish his material welfare by impairing the health 
or causing the death of his horses, cattle and sheep, by destroying food 
ci'ops during growth and, in the case of insects, by devouring the 
harvested grain. The measure of control which man can gain over 
insects, ticks and endoparasitic organisms, will determine largely the 
extent to which he can use and develop the natural resources of the 
rich tropical and sub-tropical zone of the earth. 

Other applications of zoology to human well-being cannot be dealt 
with owing to lack of time, but mention should be made of two — the 
researches on sea-fisheries problems which have foraied an important 
branch of the zoological work of this country for forty years, and the 
studies on genetics which made possible an explanation of the mode of 
inheritance of a particular blood-group, and of some of the defects 
(e.g. colour-blindness and hsmopliilia) and malformations which appear 
in the human race. 

Maintenance of Correlation between the Branches o£ Zoology. 

The rapid expansion of zoology has brought in its train the difficulty 
of maintaining the connection between its different branches. There is 
not only the mental divergence of the different workers, due to the 
necessity for specialised reading, thinking, and technique, but also in 
some cases spatial separation, and this seems to me to be the factor 
of greater importance. When modern developments of the subject 
necessitate expansion of the staff and of the working facilities it has 
not infrequently happened that one of the newer branches of the subject 
has been placed in another building, and unless careful arrangements 
are devised the dissociation tends to become more marked, so that, to 
take Mr. Bateson's exarnple, the geneticist becomes separated from 
his colleague whose interests are more largely in systematic zoology, 
to their mutual disadvantage. 

The actively growing physiological branch of zoology will, it is 
tO' be hoped, remain an integral part of our subject; for while there 
are close and friendly relations between the Department of Zoology and 
the Department of Physiology, the latter is mainly concerned with the 
training of medical students, and the teaching and reseai'ch are conse- 
quently, in most Universities, chiefly directed to the physiology of 
mammals and of the frog. The medical physiologist cannot be expected 
to prosecute researches on the invertebrates— these are as a iiile too far 
removed from the matters with which he is especially concerned — and 
yet many of the invertebrates iiave been found to be especially favour- 
able for the investigation of fundamental problems which the morpho- 
logist with physiological leanings and training seems most fitted to 
undertake. It is a good sign that more students of zoology are including 
a course of physiology in tlieir curriculum for the science degree, thus 
preparing themselves for work in comparative morphology and com- 
parative physiology. 


D.— ZOOLOGY. 123 

The association of zoology with physiology, and with botany through 
common problems in genetics and in general physiology, is becoming 
more intimate. The association o! zoology with medicine has become 
of such importance, especially in regard to its parasitological and its 
physiological aspects, that clearly collaboration with our medical col- 
leagues in teaching and in research should be as close as possible. 

Zoology in the Medical Curriculum. 

Much has been written and said in recent years about the place of 
zoology in the medical curriculum, and the present seems a favourable 
opportunity to reconsider the position and to ascertain the general 
opinion of the body of zoologists on this important matter. There can, 
I think, be no doubt that the value of zoology taught in its modem 
significance is being increasingly appreciated by the majority of our 
medical colleagues. The minority consists of two categories — those 
who have not taken the trouble to inform themselves of the subjects 
nowadays brought to the notice of medical students in the course of 
zoology, and who apparently consider that this is the one subject in the 
curriculum in which there has been no evolution since they were them- 
selves first-year students thirty or forty years ago, and those who feel 
that the increasing pressure in the curriculum calls for curtailment of 
the teaching in what they believe to be the less important subjects. The 
first of these categories need not detain us, for an opinion based on 
obsolete data is valueless. Those in the second category merit serious 
consideration, but I believe even many of these would change their views 
if they knew more fully what is being done in the modem course of 
zoology to give the medical student a broad, scientific outlook. Even 
if the course on zoology were cut out the time would not be wholly 
gained for other work, because many of the subjects now dealt with 
in the course would require consideration in the teaching of anatomy 
and physiology. The attention of the medical student is nowadays 
directed in his course of zoology not so much to the study of details of 
' types ' as to the principles which certain chosen animals serve to 
illusti'ate. A reasonable knowledge of structure is obviously requisite 
before the working together of the parts can be understood, and before 
general principles can be profitably discussed. The student at that 
early stage of his education must have concrete examples to enable 
him to grasp the functions of organs, development, ideas as to the 
relationships of animals, heredity, evolution, and so on, and his work 
in the laboratory should give him the opportunity of observing for 
himself the important structural points on which the principles are 
based. The practical work cannot Be limited to what the student can 
do for himself, for at this stagre of his training there are many things 
which he ought to see but which are beyond his technical powers to 
prepare for himself, so that a good series of demonstration objects is 
necessary, care being taken that the student not only sees the specimens 
but appreciates their significance. As the time given to zoology* is 
limited, the examples for study and the principles to be illustrated are 
to be carefully chosen, for the course in zoology is not only a discipline 


but should give basal knowledge of value in the subsequent years of 
study; and, moreover, if the student can see that his zoological work 
bears on his later studies he will take much more interest in it. It is 
important, therefore, that the points of contact of his present with his 
future work should be successively indicated. 

The details of the course of zoology for the first-year medical student 
will vary in the hands of different teachers, and it is well that they 
should be to some extent elastic. In a minimum course will be included 
the consideration of two or three protozoa, a ccelenterate, an annelid, 
an arthropod — and especially the features in which it presents advance 
as compared with an annelid, an elasmobranch fish, and a frog, the 
primitive features of the fish being emphasised, and the chief systems of 
organs of both vertebrates compared with each other and with those of 
a mammal. The functions of the principal organs of all these examples 
will be dealt with so far as they can be understood from the account of 
structure — this latter being sufificient to illustrate the principles involved, 
care being taken not to over-elaborate structural details. Man's place 
in nature should be considered either in the course of zoology or in 
that of anatomy. Other opportunities occur during the course in 
anatomy, and still more in physiology, for refei'ence to the conditions 
in lower animals, and if more use could be made of these oipportunities 
the linkage between zoology and the second-year subjects would become 
much more perfect, and would help in doing away with the water- 
tight compartments into which the average student considers his early 
medical education to be divided. 

The course in zoology should be planned so as to give the student a 
wide outlook on structure and function, adaptation and environment, 
some knowledge of the germ-cells and their maturation, of fertilisation, 
growth, regulation, regeneration, decline and death, and an introduction 
to evolution, heredity and genetics — in general, it should aim at afford- 
ing a broad conception of the activities and modifications of the organism 
as a living thing, and should educate the student to manipulate, to 
observe and record, and to exercise his judgment in matters of inference 
and of theory. 

While some reference may be made in the first-year course to insects 
and parasitic organisms to indicate the relationship between zoology and 
pathology and public health, it has seemed to me for some years that 
the real instruction in entomology and parasitology should be given in 
the later part of the third or early in the fourth year along with the 
course in bacteriology. The first-year student, although keenly inter- 
ested in the direct applications of zoology to medicine, is not competent 
at that early stage of his career to obtain full advantage from studies 
on parasites. In most Universities a certain amount of time is already 
set aside in the third year for the study of protozoa, and of helminthes 
and their eggs, and I have suggested to some of my colleagues in Edin- 
burgh that the teaching on these subjects in the first and in the third 
year should be brought together in the latter year and remodelled to 
form a short course of lectures, demonstrations, and practical work to 
cover the essentials required for general practice in this country. By 
this time the student is much better fitted to appreciate the bearings of 

D.— ZOOLOGY. 1 25 

this work. I am also inclined to the opinion that a short course of 
six or eight lectures — on which attendance might be voluntary — on 
heredity and genetics would be of value in the fourth year to the good 
student who has a little time at his disposal. 

I should be glad if my colleagues would give the Section the benefit 
of their views on the first-year course of zoology for medical students, 
and on the provision of a course on entomology and parasitology about 
the third year of medical study. 





Part I. — The Position which has been occupied. 

The British Empire, although situated in every contiuent, with shores 
on all the oceans, is seen to have a definite geographical position when 
we consider the ports of call which unite its lands and the naval stations 
which guard the communications. During the growth of the Empire 
eastward and westward from Great Britain, numerous harbours were 
held at different times, those retained being a selection uni-ivalled by 
the ports of any other State in commercial and strategic position. Our 
many oceanic islands give us, moreover, an important advantage in the 
selection of maritime stations for aircraft. 

The naval station of Bennuda, well withdrawn from aerial attack, 
has a central position in the great western embayment of North 
America intermediate between the ocean routes which connect 
Great Britain with Canada and the West Indies. No foreign ports 
flank the route between Canada and the west coast of Great Britain. 
At the western gateway of the South Atlantic we have excellent harbour- 
age in the Falkland Isles. Malta, the capital of our Fleet in the 
Mediterranean, has a commanding position at the Straits which connect 
the eastern and western basins, and the naval station at Gibraltar helps 
to ensure the junction of the Home and Mediterranean Fleet and to 
protect the Cape route. Our status in the Sudan, the vulnerable fron- 
tier of Egypt, is still maintained, and the British army which is kept 
in Egypt as garrison of the Suez Canal ensures our use of this gateway 
as long as we can navigate the Mediterranean. If that navigation be 
interrupted we can still oppose the seizure of the Isthmus, for we are 
able to send reinforcements by way of the Eed Sea. East of Egypt 
the British island of Perim stands in the Straits of Bab-el-Mandeb, 
and the garrisoned fuelling station of Aden provides the necessary 
port of call on the routes to Bombay and Colombo. Colombo, in the 
Crowti Colony of Ceylon, is at the parting of the ways for Austraha 
and the furthest parts of our Asiatic possessions, and Singapore stands at 
the naiTow gateway of the shortest route between India and the Far East. 

E.— nEOdRAPIIY. 127 

'I'ho C'apti route t<» India ami Australasia is iiupiovod by Britifili 
ports of call in Sierra Leouo, St. Helena, and LMauritius, and is more 
effectively dominated from British South. Africa than at first appeal's, 
for although there is open sea to the south there are no useful harbours 
in the Antarctic continent, and on the African coasts the harbours are 
under British control for a thousand miles from Cape Town. 

Oi the six great foreign Powers the French alone are posted on the 
flank of both routes lietween Great Bi'itain and the Indian Ocean, and 
no (jreat .Power lias its licjuie territory on that; ocean, or railway con- 
nection thereto from its liomo territory. 

Tiius the principal lands of the British Empire — Canada, the British 
Tsles, Soiitli Africa, India, and Australasia. — have good, communications 
with one another across tlie Atlantic and Indian Oceans both in peace 
and war. 

Tlie conditions of strategic communication across the North I'acific, 
on tlie contrary, are. adverse to us, owing nuiinly to tlie circumstance 
tliat we opened up Britisli ( 'olunihia across the jirairies and l)y the coast- 
ing Voyage. Had our I'olcjuisinu- route been across the Pacilic. the 
Hawaiian Islands, whicli were first brought into touch with the Western 
world by the ships of the Eoyal Navy, would have been, a British sett.le- 
ineiit and one of oui- fiist-class naval stations. As things happened, 
however, these islands were fii-st needed by the Americans, and now 
fonu the essential western outpost of the United States Navy. Between 
tliem and British Columbia the ocean is empty of islands, and Fanning 
Island, south-west of Hawaii, with the adjacent small coral islands in 
our possession, are no adequate substitute, even apart from overshadow- 
ing by a first-class naval station in the neighboui-hood. Thus there is 
no good strategic comnmnication between Australasia and Canada across 
the North Pacific. In this connection it must be remembered that 
cousinship does not relieve the American Government from the obliga- 
tions which international law imposes upon neutrals. It was not until 
three years after the outbreak of the Great War that America could 
offer us any facilities in the harbour of Honolulu which were not equally 
open to Germans. It must also be noticed that we have no control of 
the Panama route between New Zealand and Great Britian. 

Turning to the question of communication between British Columbia 
and India, it is important to realise that the Pacific coasts of North 
America and Asia are in a direct line with one another, forming part 
of a Great Circle, so' that there is no short cut across the ocean, as the 
map misleadingly suggests. Thus the course between Vancouver and 
Hong Kong is not only very long, but also closely flanked by the home 
ports of Jajian and many outlying Japanese islands, so tliat its sccuritv 
in time of war depends ujion tlie attitude of the Japanese. 

When, therefore, we differentiate the routes on which we have well- 
placed naval stations and recruiting bases from those dominated by the 
ports of some other Great Power, we see that the lands of the Empire are 
united by the Atlantic and Indian Oceans and strategically separated 
by the North Pacific. Thus the form in which the Mercator rnap is 
usually drawn by British cartogi-aphers with Canada in the upper left 
find Australasia in the lower right corner is a. good rbpresentation of our 
)!)2;l ,. 


maritime Empire. It shows the lands as connected by the Atlantic 
and the Indian but not by the Pacific Ocean; Great Britain, the naval 
and military headquarters of the Empire, on the central meridian ; and 
Port Said and Cape Town as connecting positions between the western 
and eastern parts of the Empire. 

Upon this map a symmetrical distribution of our lands is 
revealed when a Great Circle is drawn connecting Halifax in Nova 
Scotia, the eastern texminal port of the Canadian Pacific Eailway, 
with Fremantle, the western terminal port of the Australian railway 
system. This truly direct line, twisted on Mercator's map into the 
form of the letter S, extends just half-way round the meridians but is 
somewhat shorter than the semi-circumference of the globe, the differ- 
ence of latitude between Hahfax, N.S., and Fremantle being less than 
ninety degrees. The line passes through Lower Egypt close to the Suez 
Canal following the general direction of the Main Track of the Empire, 
which is the steaming route from Canada to Great Britain, and thence 
by the Suez Canal to India and Australia. At one end of the line lies 
the Canadian Dominion, and at the other Australasia, to the north 
the British Isles, and to the south the Union of South Africa, 
the chief homes of the British nation. Our coloured peoples are also 
distributed symmetrically about the line, India being on the east, the 
Crown Colonies and the Protectorates of Africa on the west, so that it 
is the axis of symmetry of the Empire. Not far from its middle point 
is the Isthmus of Suez, where our direct line of sea communication is 
crossed by the only coritinuous route for the international railways 
which will connect our Indian and African possessions, and adjacent to 
the Isthmus is the central station of our airways. 

Such is the form and position of the British Empire, regarded as a 
maritime organisatiom, which in fact it is. 

The Empire thus mapped has an Intermediate Position among the 
commercial, national, religious, and racial communities of the world 
such as is occupied by no other State. The ocean routes must always 
be the Link between the two great land ai'eas of the world, and in the 
present state of land communication provide the connection between 
the numerous independent systems of continental railways. The chief 
of these systems is based on the ports of Continental Europe, of which 
the greatest communicate with the ocean, and therefore with other rail- 
way'- systems, by way of the English Channel. Thus the island of Great 
Britain is intermediate between the principal termini of the European 
railways and the other railway systems. Its harbourage is unequalled 
by that of any country of Continental Europe, and its supply of ship- 
building material and coal exceptionally good. Thus the physical 
characters of the island accord with its position on the commercial map. 
and the Metropolitan British in their Intermediate Position have become 
the chief common carriers of international commerce. !Much of this 
profitable business used to be in the hands of smaller European States. 
whose commerce eventually suffered from their inability to defend them- 
selves against more powerful neighbours. Our merchant shipping is 
protected by the Eoyal Navy, but owing to the recent development of 
fighting aircraft, ships of war can no longer protect the island itself, 



and since the close of the recent war this ciluclel of the Empire, the 
home of two-thirds of the white population, has been more exposed to 
attack from the Continent tlian at any previous time during the last eight 
hundred years. 

The Suez Canal, where we have the principal control, is the gateway 
between the railway tennini of Europe, the greatest manufacturing 
centre of the world, and those of the monsoon region of Asia, the greatest 
centre of population. It is also on the shortest route between the rail- 
ways of North America and India. 

The commercial and strategic importance of Singapore as an Inter- 
mediate Position between India and the Far East is enhanced by the 
circumstance that railway communication between them is debarred by 
the greatest mountain r.ystem in the world. 

Hong Kong, at the chief gateway of Southern China, is typical of 
Bi-itisli maritime stations both in its Intermediate Position and in the 
facilities provided for the ships ol other nations, which swell the vast 
tonnage entered and cleared at the port. 

How far-reaching is tiie effect of our Intermediate Position is re- 
vealed by the important but little recognised fact that it is the British 
naval stations which would, if available, provide America with the 
best line for reinforcement of the Philippines, the Achilles' heel of the 
Eepublic. The distance of Manila from the naval shipbuilding yards of 
the United States is almost exactly the same by Suez and Panama, but 
the Pacific connection has never been good owing to the great distance 
between stations, and is now worse than before the Great War on 
account of the island mandates acquired by the Japanese. The relation 
of Port Said and Singapore to America and the Philippines is only one of 
many cases in which our position is intei^mediate between the home and 
Colonial possessions of a white nation. Thus the important French 
possession of Indo-China has to be reached from France either by way 
of the Suez Canal where we maintain a garrison, or by rounding the 
Cape where we have a national recruiting base, as vv^ell as a station of 
the Royal Navy. The true significance of our Intermediate Position 
has, however, been generally missed owing to a one-sided interpretation 
of strategical geography. An intermediate station, particularly a naval 
station, has commonly been regarded as a blocking position, a Barrier 
where freedom of movement can be interfered with. The historical fact 
is, however, that the harbours of the British Empire have also been a 
Link between nations. In the Great War the British Empire v/as the 
Link of the Allied and Associated Powers, and its geographical position 
is unequalled for making a benevolent alliance effective or checkmating 
the action of an alliance formed with n sinister purpose. 

The British Empire provides in Canada the one Link between the 
European and American divisions of the white race, for public opinion 
in the United States adheres to the view that the New World, in the 
sense of North and South America, should be shut off and sheltered 
from the evils of a bad Old Europe. 

In Tropical Australia the British, in the exercise of their discretion, 
have set up a Barrier between the white and coloured races. Australia 
is a land almost empty of aboriginals, which has for the most part 

L 2 


;i climaio in wliic-li Britisl'i children thnvo and de\elop true to type. 
In the great basin of the MuiTay Eiver and its confluents, not far 
from the huge superficial deposit of brown coal in South Victoria, 
is a combination of fertile soil, forcing sun, water for irrigation and 
cheap electric power transmitted from the coal-field. This favoured 
region, the ' Heart of Australia,' as it has been called, with a population 
of only three million, is equal in size to France, Italy, and Gei^many 
combined, which have a population of more than one hundred and thirty 
million. The problem of Australian settlement is, however, complicated 
by the circumstance that the northern coast-lands lie in the Ti'opics, 
and have a climate which makes field work very arduous to white men. 
It is, moreover, uncertain if British families would continue true to 
ancestral type in this climate. If, however, settlers from the neighbour- 
ing monsoon lands of Asia be admitted, whose descendants would rapidly 
increase, it would be impossible to maintain a colour line between 
Tropical and Temperate Australia , and the rough labour of the Common- 
wealth would in time be done by coloured people. The fact that this 
labour is cheap would result in the employment of a gi'eat number of 
coolies instead of the use of machinery, and Australia might become a 
land of coloured workmen and white, overseers. Circumstances, there- 
fore, foiced the Australians to decide whether their tropical ])elt should 
be a Link or a Barrier between white and coloured labour. The decision 
to erect a Barrier was taken early, and has been consistently niaintiiined. 
The strategic responsibility of the decision is seen to be very great when 
we look into the future and reflect on the facts of population. 

Of the 1,650 million people in the world, the whites number about 
500 and the coloured 1,150. The foraner are mainly grouped on the two 
sides of the North Atlantic Ocean ; of the latter, the gi*eater part, about 
800 million, are in the monsoon region of Asia, which includes India, 
Indo-China, China proper, and Japan. The Australian British are far 
from the main body of the white race and fi'om Great Britain, the chief 
recruiting base of their own nation. On the other hand, the distance 
by sea between Townsville, Queensland, and the Japanese coast is no 
longer than the course of the coasting steamers from Fremantle to 
Townsville ; and the other lands of Monsoon Asia are even nearer than 

Enough is known of the relation between geographical environment 
and national well-being to declare with confidence that the decision to 
erect a Barrier against coloured labour in Tropical Australia is best both 
for the white race in Australia and for the coloured people of the 
monsoon region of Asia. Not only is Government much more difficult 
with a two-colour population, but the admission of coolie labour would 
deteriorate the national character of the Australians, for histoiy shows 
that the greatest nations are those which provide their own working 
class. Turning from the Occidental to the broader humanitarian view, 
it is only necessary to look ahead in order to see that the admission of 
Asiatic coolies to a British homeland is unkind to their descendants. 
Those that remain unmixed in race will have a stunted existence as a 
community cut off from full national life, whilst the case of mulatto 
descendants is almost worse, for the children are not brought up in the 


family of the British parent, and yet are cut off from the full tradition 
of Asiatic civilisation. Far better, then, that the Asiatic coolie should 
remain where the family life of his descendants will be part and parcel 
of national life. 

Neither should it be assumed that there is not room in Asia for a 
large additional population. The pressure of population in China is 
largely due to the undeveloped condition of mining, factories, and com- 
munications. The coal-fields are unsurpassed in the world, and iron ore 
is abundant; if they were worked, and factories were based upon them, 
the new occupations and improved market for agricultural produce would 
provide at home for many of those' who now migrate oversea. The rise 
in standard of living which may be expected to follow industrial develop- 
ment would also reduce coolie competition in the white boi'derlands of 
the Pacific. The furtlier development of manufacture in India would 
operate in the same direction. The growth of a manufacturing popula- 
tion in China and India would stimulate cultivation and stock-rearing 
in the sparsely inhabited region under Asiatic rule which runs diagonally 
across the meridians fi'om the Persian Gulf to the Amur, and includes 
the eastern provinces of Persia at the one end and Mongolia and Man- 
chm'ia at the other. This has for the most part a light rainfall, but 
comprises much fine prairie countiy and some good agx"icultural land, 
whilst in the more arid tracts there are many great rivers fed from snow- 
fields and glaciers which could be made to irrigate large areas where the 
sun is as strong as in Australia. Adjacent to the Indo-Chinese peninsula 
are the East Indies, whose chmate is suited both to Indians and Chinese, 
with great tracts of undeveloped land whose productivity is attested by 
luxuriant forest. The sparsely peopled regions of Asia near to India, 
China, and Japan by land and sea, and for the most part connected with 
them by ties of civilisation, provide an area for the overflow from these 
countries which is more than twice as large as Tropical Australia and 
British Columbia, together with California, Washington, and Oregon, 
the American frontier provinces of English-speaking labour. 

India includes one of the most important borderlands within the 
Orient, that of the Mohammedan and Hindu worlds. The Punjab, with 
its great rivers and plain, is in such striking contrast to the mountains 
and plateau of Iran that we are apt to lose sight of the fact that, climatic- 
alh% it more resembles the highland on the west than the rainy valley of 
the Gange.; on the east. It is an eastern borderland of Islam, a religious 
world which is mainly comprised in the belt of dry country which, 
stretches diagonally from the Atlantic shore of Morocco to the Altai 
Mountains. Delhi, under the Great Moghul, was an advanced capital 
of the Mohammedan world just within the Ganges valley, which is the 
headquarters of Hinduism. In this sub-imperial capital the two 
antagonistic civilisations are now linked 1o the govennncnt of (he 
United Kingdom, and the age-long wais between them have ceased. 

Up to the time of British predominance, India was the terniinal posi- 
tion of Continental conquerors unused to the sea, who did not develo]^ Iht; 
advantages of a salient maritime position. The ports of India lie con- 
veniently for a long stretch of coast-land on the great gulf which fomis 
the Indian Ocenn, and now. owing lo the facilities provided by British 


shipping, niucJi of this coast-land has easier communication with India 
than witii its own continental interior. Several British possessions in 
the parts of Africa adjacent to^ the Indian Ocean are in the Intermediate 
Position between the principal homelands of the black peoples and the 
overflowing population of India, and nowhere has the responsibility of 
our Intermediate Position called for more careful examination of the 
rights and interests of competing coloured races. The decision with 
reference to Kenya which has just been given by the home Government 
recognises the main physical regions in the coloured world as political 
divisions of the Empire within which the established races have special 

The Union of South Africa is the racial home of white men and of 
the more numerous coloured people who are indigenous to the country. 
It is, therefore, largely a land of white overseers and coloim-ed labour, 
but here, as in the other Britains beyond the seas, there is an opposition 
to the introduction of coloured blood into white families which is not 
met with where Latin races are similarly situated. The Dutch families 
are at one with those of British stock in the maintenance of this racial 

From the foregoing facts it is clear that the British people, Metro- 
politan and Colonial,' are in a greater degree than any other nation the 
doorkeepers of the world in respect of economic, strategic, and racial 

Part n.— The Consolidation of the Position. 

The consolidation of the position which the British Nation has won 
turns upon the future of colonisation within the Empire. We must 
therefore compare the number of the Metropolitan and Colonial British 
with that of other peoples within and without the Empire, and take 
account of the relation between the present population of the world 
and the area of its empty lands. The British Empire comprises the 
fourth pai-t of mankind, but the ratio of white to coloured people 
in the Empire is only about one to six. The former are mostly of 
British stock, and belong to the Christian world. The latter are of 
many stocks, differing physically from each other as much as from the 
white people, and belonging to diverse religions. Their population is 
steadily increasing under British rule, and some of them have recently 
made advances in political organisation and industrial efficiency. Conse- 
quently, if the Empire is to be guided by the British, the numbers of our 
race must also increase. There is, however, a school of thought which 
considers that if our ideals of ethics and efficiency are once accepted 
by the coloured peoples, the racial complexion of the Empire will be 
unimportant, as public affairs will be regulated by our principles. This 
point of view, which may be termed in a general sense the missionary 
standpoint, does not take account of the contingeiicy that Biitish ideals 
implanted in coloured stock may receive alien development in future 

^ The introduction of the term ' Dominion ' served to suggest emancipation 
from the Colonial Office, but the word Colonial as descriptive of a people has 
permanent historical value and therefore should not be allowed to lapse. 



generations owinp to l)iological causes. Our confidence in ^yeste^l 
culture in general, and the British version of that culture in par- 
ticular, is based more upon the power of adaptation which it has shown 
in our hands since the Kenaissance and tlio Era of Oceanic discovery 
than upon any system of which we can hand over a written prescrip- 
tion. It is only in our own national communities, mainly com- 
posed of British "stock, with minorities nearly akin, that we can be 
confident that British ideals will develop typically in the way of natural 
evolution. Therefore in our own interests and in that of the coloured 
races (who conflict among themselves) it is desirable to maintain the 
present pi-oportion of the British stock, to whoni the Empire owes the 
just administration of law and a progressive physical science. 

The co-operation of the Union of South Africa in the Great War 
only became possible after the failure of an insurrection by part of the 
Boers. Since the number of persons of Dutch and British stock is 
about equal, an influx of British colonists is required in order to ensure 
unanimity between South Africa and the rest of the Empire. 

Passing to the ratios between British population and foreign nations, 
we have to note that the population of Austraha stands to that of Japan 
as about one to ten The Japanese are a patriotic as well as an 
advanced nation, and claim equality with the white nations from 
patriotic motives. It is evident, therefore, that a strong I'einforcement 
of Bintish population is needed to maintain the doctrine of a white 
Australia. For the same reason New Zealand also needs reinforcement, 
since Australasia is strategically one. 

The number and density of the population of Canada is exceeded 
in the proportion of about ten to one by the white population of the 
United States, hence it is inevitable that there should be a large 
flow of people from the latter country to the Dominion. As it is essential 
to unanimity in the Empire that the Canadians should continue to be 
British in sentiment and not become pan-American, a large immigration 
from Great Britain is required in Canada. Moreover, the population 
of Continental Europe outnumbers that of Great Britain- in the propor- 
tion of something like ten to one, and as emigrants go to Canada from 
many European countries there is a further call for British immigrants 
to maintain the British character of the Dominion. 

We have next to note that the population of Great Britain, which 
is now forty-three million, outnumbers the combined population of 
Canada, Newfoundland. South Africa, Australia, and New Zealand in 
the proportion of two and a-half to one, and inci-eases more rapidly than 
that of all these Dominions, more than three and a-half million being 
added in the decade 1901-11, in spite of an emigration which nnich 
exceeded the immigration. Thus the chief soin-ce available for the 
Britisli pco]iling of the Dominions is the Metropolitan, not the Colonial, 

In 1891 the late Mr. G. Eavenstein calculated from the rate of 
increase of population the time which remained before the unoccupied 
lands of the woi4d would be settled and developed in accordance with 

* In the present condition of home affairs in Ireland it seems best to leave 
its population out of tlic numerical reckoning for Imperial purposes. 


theii' agricultui'al capabilities. This period he reckoned at about two 
centuries, by which time the population was calculated at 6,000,000,000 
instead of the 1,600,000,000 which it had reached in 1891. The figure 
must not be taken to indicate the final population of the world, about 
which we know nothing, but the epoch marks finality of a certain kind — 
namely, the end of the colonising period of history as colonising has 
hitherto been conducted. The world will then be completely parcelled 
out among the nations, and since it is very difficult to displace a nation, 
it is proibable that those which occupy the world at the end of the colonis- 
ing period w'ill remain in possession for a long time, even as time is 
reckoned in the pages of history. If we allow a generation for the set- 
back of the War we may roughly reckon our zero-time as 1923 instead of 
1891, which, on the basis of Mr. Eavenstein's figures, would still give 
about two centuries, or six generations, in which to provide the temperate 
climates of the British Empire with a sufficiency of British stock to 
ensure the continuance of their British character. 

There is, however, a school of thought which sees the salvation of 
the home country in a reduction of its population. I take their strategic 
argument first. It is contended that Gi^eat Britain would be safer in 
time of war if it had no more people tlian its farms can feed. Judging 
•by France and the fomier Austro-Hungarian Monarchy, this would 
be about one-half of our present population, for our country is small 
though fertile. The conditions of our strategic security have, however, 
undergone a great change since 1914. The best plan of campaign for a 
combination of European Powers bent on overthrowing the citadel of 
the Empire would be an attack by combined air-fleets, which could be 
concentrated on London, the gi'eat manufacturing towns, and the ship- 
building yards, wliolly destroying them one by one by intensive bom- 
bardment. This plan would be more effective than naval blockade, 
which it is very difficult to make complete, and is liable to bring in new 
belligerents owing to interference with neutral shipping. In order to 
have strategic security' in this island we must therefore be able to meet 
the air-force of a European combination as w'ell as carrj' out our tradi- 
tional plan of despatching a powerful expeditionary force for the support 
of a friendly Power. This active defence requires large population and 
high devlopment of technical industries, and therefore could not be 
sustained by a I'ural Britain. 

The economic argument for reduced population has received ready 
but uncritical assent owing to the great want of employment since the 
War. It is stated that this island will never be able to support in 
proper comfort a population of forty-three million, the present figure. 
But the population w^hich can be sustained in a country depends 
jointly upon internal resources and geographical )X)sition. The com- 
mercial position of Great Britain is more favourable than that of any 
other island of equal size, and the large amount of good coal, besides 
iron ore and beds of salt, enable full advantage to be taken of the 
geographical position in manufacturing for export. According to the 
estimate made in 1905 the stock of accessible coal in the United 
Kingdom is sufficient to last more than four hundred years at the present 
rate of output, and an estimate made in 1915 gives a yet larger stock. 


Moreover, no change in the distrihution of tiviuhil)lc minerals can ever 
do av\'ay with the commercial advantage confen'ed by our central and 
focal position on the natural maritime routes. Hence the population 
which can be supported in Great Britain depends upon services to 
outside nations to a much greater extent than in most countries. 

The population which can be maintained in our home country 
depends, therefore, to an exceptional degree upon the population and 
prosperity of the rest of the world, so that when the world again get<3 
into its stride there should be improved conditions here, and as the popu- 
lation of the world grows so should the number of jobs in llie country 
increase. There is, therefore, no sufficient ground for stating that we 
have passed or reached the limit of population which the island can 
ever support. 

Tlie teaching of those who advocate reduction of population as the 
salvation of Great Britain includes eugenic and ethical arguments. 
Thus it is said that very small families conduce to a high standard of 
civilisation since more care can be devoted to the child. This, however, 
leaves out of account the educative influence of the children of a family 
nix)n one another. Everyone knows that an only child is at a disadvan- 
tage in life. The world being of both sexes, and the society in which 
we move mainly of our own generation, the full home training for life 
is only obtained if each child have a brother and sister, which implies 
a family of at least four. 

The desirability of birth -restriction among the poorer classes is 
strongly pressed on the plea that we are breeding to an increasing 
extent from inferior stock, and thereby lowei'ing the national type. As 
far as the allegation relates to defectives, it is indisputable that most of 
them are among the poorest of the poor, and that their breeding is an 
injury to the community, as is also the admission of defective or criminal 
aliens, but these are categories quite apart from our great working-class 

The professional families are far too few to maintain the supply of 
original genius needed for this country's advance, for genius is largely 
in the nature of a sport, and has to be replenished from a verj* large 
reservoir of population. To recruit the professions entirely from the 
present professional families would, therefore, in the long nm be fatal 
to originality. On the other side of the picture, a working-class home 
is the best preparatory school for the colonial frontier, where to have few 
wants is better than ilie possession of many attainments. 

We are told that an increase of population in Great Britain will pack 
the slums and thereby reduce us to the ' 03 ' categoiy of physique, 
but this argument takes too little account of the redistribution of urban 
population which has been going on for the last forty years. The 
density of population in central t>ondon has diminished, and factories 
have sprung up along the railways which radiate from the town. Tn 
inil the five Counties surrounding T,ondon, with their two included 
County Boroughs, contained no less than one million residents born in 
London who had migi'ated into these more rural districts. Migration, 
it should bo observed, whether to or from the, town, prevents the close 
breeding which used to be a sei-ious disgenic factor in vilhi;,'cs. 


In 1911 the birth-rate in the towns of England and Wales was 
higher than in the rural areas, and the Eegistrar-General's Eeport states 
that even when these figures are corrected for the movement of the 
people the rural districts would only have increased at the same rate as 
the country at large, adding that ' these facts are worth noting in view 
of the assumption, sometimes loosely made, that the population of the 
towns would cease to increase if it were not recruited from the countiy. ' 
In this connection it should also be noted that the proportion of 
London residents who are London-born has steadily increased from 1881 

The growth of our towns is no longer haphazard, but has entered 
on the stage of planning. 

A great abatement of the contamination of town air by smoke has 
been shown to be practicable, and it is largely in the matter of smoke 
and crowding that towns have been hygienically inferior to the country, 
for counti7 cottages are often as bad in themselves as slum houses, 
and their water supply much inferior. Moreover, the hygiene of towns 
has always been dependent on the circumstance that hei'e the health of 
many people is affected by the carelessness of a few, and it follows that 
the hygienic conditions of urban life are capable of immense improve- 
ment when scientific knowledge becomes general. The experience of 
the War has shown that the popular notion of the inferior moral of 
townsmen was unduly pessimistic, for our urban regiments not only 
showed intelhgence, but exhibited a sustained valour which has seldom 
been surpassed in the long annals of military history. 

That emigration to the Dominions brings some economic benefit 
to the home country cannot be. gainsaid, for trade returns show that 
an emigrant to the Dominions buys as much here as eleven emigrants 
to the United States, and therefore as much as many foreigners; but 
those who fear additions to our people also fear the moral effects of 
emigration. They say that emigration will take the best and leave the 
worst, and so produce a disgenic effect in the home country. But the 
individual emigration of to-day differs in this respect from the group 
migrations under political compulsion, or for conscience sake, which 
inflicted eugenic loss upon Spain, France, and England in bygone 
days. The best lad for the Dominions is not necessarily the best for 
the home country, and an Empire which comprises urban as well as 
rural States requires young men whose business tenacity is sufficient to 
resist the restlessness of youth not less than those who are instinct with 
the spirit of the frontiersman. 

That a relative increase of female migi-ation would benefit national 
character cannot be gainsaid, for at present the Dominion frontiers lack 
the due weight of feminine influence, whilst in Great Britain many 
women are denied tlie full development of tlieir character whicli some 
natures only attain by wedlock and motherhood. The Census of 1911, 
unaffected by War losses, shows an excess of about 1.300,000 females 
in Great Britain and a deficiency of about 750,000 in the Dominions. 
The inequality of distribution as between Great Britain and the 
Dominions limits the possible mamage-rate, and therefore the total 
births, in a way to which no other nation is equally subject. If the 



numbers in the Dominions be equalised as the result of special en- 
couragement of female emigi'ation, there will still remain a large excess 
of women in Great Britain who cannot be paired in the Empire unless 
the stream of emigrants who now leave the Empire can be for the most 
part deflected to the Dominions. In Great Britain the total number 
of families is limited by the number of males. In dealing with the 
size of familj^ needed to maintain or increase population I do not reckon 
the present surplus of nearly two million women resulting from the 
joint effect of migration and war. At present our community appears 
to be in a transitional stage between the limitation of the family by 
chance and by choice, but the census shows, from the present age of 
marriage in Great Britain and the number of deaths before this age, 
that a general preference for the family of three children would not quite 
maintain the population, apart from migration. If, therefore, the size 
of family be universally decided by choice the number of the race cannot 
even be maintained, far less increased, under present conditions unless 
those who enter into matrimony cherish the ideal of a family of four 

Unless the British race increase we cannot insure the internal peace 
and external security of the Empire, or the continuance of its beneficent 
work of enlarging commerce and restricting the range of war. There- 
fore the birth-rate in Great Britain should be maintained above the 
death-rate at least until the British population in the Dominions exceeds 
that in the Mother Country. The maintenance of the race will then 
rest chiefly with our people oversea, and, with their great resources, it 
should be possible for them to keep pace with the other gi-owing nations. 




president of the SECTION. 

The impression that the civihsed world is ah-eady threatened with over- 
population is very common to-day. Many, perhaps most, educated 
people are troubled by fear that the limits of population, probably in 
Europe and certainly in this country, have been reached, and that a 
reduction in the rate of increase is an urgent necessity. Most, if they 
were asked to give reasons for their fear, would refer to one or both 
of two reasons : they would point to the enormous volume of unemploy- 
ment in this country ; they would say that economic science, at least at 
Cambridge, had already pronounced its verdict. I propose to begin 
by raising some doubts as to the validity of each of these arguments. 

Unemployment No Proof of Over-Population. 

The volume of unemployment in Britain is undoubtedly serious, and 
almost certainly unparalleled in past history. Those who see, as we 
now do, more than a million wage-earners whom our industry for 
years together is unable to absorb in productive employment may be 
excused if they draw the inference that there are too many wage-earners 
in the country. The inference, though natural, is unjustified. Un- 
employment in Britain can in any case prove nothing about the world 
as a whole. History shows that it does not prove over-population even 
in Britain. 

During the last half of the nineteenth century, the industry of the 
United Kingdom was finding room for a rapidly increasing number of 
wage-earners with an admittedly rising standard of production and 
comfort. Through the whole of that period there was unemployment 
in the country. The percentage of trade unionists out of work never 
fell to zero ; in no year since 1874 was it less than two ; at more than 
one crisis it reached a height comparable if not equal to that which 
we have just experienced. During 1922 this percentage has averaged 
fifteen; but it averaged over eleven in 1879 and over ten in 1886. These 
figxu-es are not on an identical basis and are therefore not absolutely com- 
parable. Taken for one year only, they understate the relatively greater 
seriousness of our recent experience, since the unemployment percentage 
was high through a large part of 1921 as well as in 1922, and still con- 
tinues high. But the difference is one of degree rather than of kind. 
The peril of inferring over-population from unemployment is conclu- 
sively shown. 

The experience of 1879 was up to then unparalleled; probably it 
was as much worse than anything previously recorded as the experience 

F.~EC0N0^rI(•s, 139 

of i;)2i^ appears wnrso ihau that cif ]87'-l. Tlic oxperioncfc of 1879, 
howover, tho record year of uneniploynient, heralded, not over- 
popidation and the downfall of British industry, hut a period of ex- 
pansion and prosperity which itself reached, if it did not pass, all 
previous records. 'Real wages,' which had risen thirty per cent, in 
the twenty years to 1880, rose even more rapidly in the next twenty 
years to 1900. Anyone wlio in 1879, looking at the half or three- 
quarter million unemployed, had argued that the existing population 
of the United Kingdom (then ahout thirty-four millions) was all that 
the country could support witlunit lowering its standards, would have 
heen lamentahly discredited at once. Ten years later he would have 
found a population nearly three millions more, enjoying a real income 
per head that was a fifth greater, with the iniemploymeut percentage 
ivdiiced to two. Ten years later still the ])opulation had grown further 
in size and in prosperity ; those trades had grown most rapidly in 
which there liad he^en and continued to he the largest jiercentagt^s of 

The prohlems of unemployment and of over-population are distinct; 
they are two problems, not one. Severe unemployment has occurred 
in the past without over-population, as a function of the orgaiusation 
and methods of industry, not of its size. On the other hand, it is very 
doubtful if excessive growth of population has ever shown itself or 
would naturally show itself by causing unemployment. A more pro- 
bable effect would be pi'essure to work more than before in order to 
obtain the same comforts ; a fall of real wages per hour, by inci-ease 
either of hours or of prices. 

The same dependence of unemployment on the organisation and 
methods of industry, rather than on its size, appears if we look, not 
backwards in time, but round ns in space. It has been pointed out 
by Professor Cannan that one of the few groups of economists who 
from our post-war sufferings can at least obtain the high intellectual 
satisfaction of saying ' I told you so, ' is that which maintains that 
changes in the purchasing power of money are the most potent causes 
of the fluctuations in prosperity known as cycles of trade or booms and 
depressions. ' In the pre-war period booms and depressions swept 
over the whole western world at once and left their causes obscure. 
In 1922 we have been treated to a sharp contrast between two groups 
of countries, one group having boom and full employment, the other 
depression and unemplojancnt, the difference being quite clearly due 
to the first group having continued the process of currency inflation, 
the other group having dropped it.' To bring this generalisation down 
to particular instances, we see in Central Europe a nation which 
assuredly sliould be suffering from over-population if any nation is; 
Germany, defeated in war, has been compressed within narrower limits, 
has lost its shipping and foreign investments, its outlets for emigration 
and trade, and now by high birth-rates is repairing with exceptional 
speed the human losses of the war. Cermany may or may not be 
suffering from over-population. She certainly has not suffered from 
unemployment; she has had a boom stimulated by inflation of the 
currency. We see on the other hand Britain, victorious in war, with 


expanded territories and the world open to her, pursuing a different, 
no doubt a better, currency policy and experiencing unexampled un- 
employment. To argue uncritically from unemployment to over- 
population is to ignore the elements of both problems. ' 

Europe before the War. 

Let us turn to the second argument, the argument from authority 
and, above all, from the authority of Mr. J. M. Keynes. No economic 
writing in our generation has obtained so wide a fame as that of Mr. 
Keynes on the ' Economic Consequences of Peace. ' None, on its 
merits, has deserved more. With its main argument neither I nor, 
I think, posterity will wish to quarrel. There ai'e, however, in that 
book certam phrases about population, used incidentally, almost casually, 
which have none of the weight of the main argument. To these almost 
more than to anything else is to be attributed the general dread of over- 
population to-day; these call for examination. 

In the second chapter of his book, Mr. Keynes paints a picture of 
Europe as an economic Eldoi'ado, now devastated beyond repair by 
war and the peace, but even before the ^Yar threatened by internal 
factors of instability — ' the instability of an excessive population de- 
pendent for its livelihood on a complicated and artificial organisation, 
the psychological instability of the labouring and capitalist classes and 
the instability of Europe's claim, coupled with the completeness of 
her dependence on the food supplies of the New World.' In naming 
the first of these factors of instability Mr. Keynes already passes the 
judgment that Europe's population was ' excessive.' Elsewhere in the 
same cliapter he is more specific : ' Up to about 1900 a unit of hibour 
applied to industry yielded year by year a purchasing power over an 
increasing quantity of food. It is possible that about the year 1900 
this process began to be reversed, and a diminishing yield of Nature 
to man's effort was beginning to reassert itself. But the tendency 
of cereals to rise in real cost was balanced by other improvements.' 
A few pages further on he passes from possibilities to positive asser- 
tion ; in the last years before the War ' the tendency towards stringency 
was showing itself . . . in a steady increase of real cost . . . the law 
of diminishing returns was at last reasserting itself, and was making it 
necessary year by year for Europe to offer a greater quantity of other 
commodities to obtain the same amount of bread.' In the seventh 
chapter is a wider and yet more explicit assertion of ' the increase in 
the real cost of food and the diminishing response of Nature to any 
further increase in the population of the world.' And so to Malthus. 
' Before the eighteenth century mankind entertained no false hopes. 
To lay the illusions which grew popular at that age's latter end, Malthus 
disclosed a Devil. For half a century all serious economical writings 

1 In the United States, which no one suspects of over-population, 'there 
seems good ground for believing that in actual diminution of employment, the 
depression of 1921 was almost twice as acute as that of 1908 ' (Berridge : f'l/clet 
of U ncmployment , p. 52). 1908 was one of the worst Hcpvpssions hitherto 
c.v) PI iencod in America. 







512,413 . 

18-83 1 

6-38 1 
10-89 ] 


« lit o 

•j ■* i> 
































1 1 1 


















9-0 1 





















1 1 1 1 1 


1 1 I 1 1 


1 1 1 




1 1 1 1 1 

II 11 1 



1 1 1 



































Total Production 
(1000 quarters). 


Bye . 


Four Crops . 

Area under Crop 

(1000 acres) 


1 Rye . 

j Barley 

Mai-ie . 

Four Crops . 

Tield per Acre 
Rye . 
Maize . 
Four Crops 

Tield per Head 
Hye . 
1 Maize . 
1 Four Crops . 

Production per Head 

Iron Ore 
Crude St€el . 


held that Devil in clear prospect. For the next half-century he was 
chained up and out of sight. Now perhaps we have loosened him again. ' 
These quotations set the problem. The question is not indeed 
whether Malthus' Devil is loose again. Mr. Keynes has seen to that; 
he stalks at large through our lecture-rooms and magazines and debating 
societies. The question is rather whether Mr. Keynes was right to 
loose this Devil now upon the public. Was there in Europe or in the 
world as a whole before the War clear evidence, first, of ' a diminishing 
yield of Nature to man's effort '; and, second, of a 'rising real cost ' 
of corn? 

The Course of Agricultural Production. 

The answer to the first question is given by the table of ' Agricul- 
tuial and other Production at certain Epochs ' wliich is printed above. 

Notes to Table. I. 

The figures of acreage and eorn production at the successive epochs are averages 
for the six years 1878-1883, 1888-1893, 1898-1903, 1908-1913, and for the two years 
1920-21, or for as many of those years as were available in each case. 

The populations are those given in censuses or official estimates relating to dates 
within six months of January 1, 1881, 1891, 1901, 1911 and 1921, or are estimated 
for about those dates (being the centre of the six years taken for averaging) where no 
such census was available. 

The figures for ' Europe ' relate to Austria, Belgium, Bulgaria, Denmark, France, 
Germany, Holland. Hungary, Italy, Roumania, Russia (with Poland), Serbia, Spain, 
Sweden, and the United Kingdom, containing between them 94% of the total popu- 
lation of Europe in 1910. Norway, Finland, Portugal, Switzerland, Greece, Turkey, 
Bosnia and Herzegovina and a few minor states alone are excluded. The figures for 
* Countries settled from Europe ' relate to Canada, United States of America, Argentina, 
Uruguay, Australia, and New Zealand. At the epochs 1900 and 1910 actual returns 
are available for all countries ; at the earlier epochs the yields or acreages or 
both have had to be interpolated for a few countries (of which Spain and Roumania 
are the most important). 

The yields, acreages, and populations for 1920-21 are ))ased on the statistics given 
in the year book for 1921 of the International Agricultural Institute. The yields and 
acreages for earlier years are based on the statistics in the aimual Agricultural Returns 
published by the English Board of Agriculture and Fisheries. The populations for 
these earlier years in Europe are based on the statistics compiled by the International 
Statistical Institute) Etat de la Population, published 1916). 

Weights have been converted into quarters on the basis of 480 lbs. to the quarter 
of wheat, rye, and maize, and 448 lbs. to the quarter of barley. 

The figures for coal, iron ore and steel production are five or three year averages 
centering on the years 1880, 1890, 1900, 1910. For Europe the production is actually 
that of Austria, Hungary, Belgium, France, Germany, Italy (not steel), Russia (not 
iron ore), Spain (not steel), Sweden, and United Kingdom. For European settlements 
the United States contribute all the steel and all but a little of the iron ore ; for coal 
Canada, Australia and New Zealand are included. The production ' per head ' is based 
on the same population.s as those used for agriculture in Europe and its settlements 

The population for Russia at January 1, 1911, is obtained (as 133,500,000) by 
interpolation from censuses and estimates for earlier years and from the oflBcial 
estimate of 130,820,000 at January 1, 1910, given both in the Agricultural Returns of 
the English Board of Agriculture from which the acreages and crops are taken, and in 
the Annitaire Statistique of 1916 {Etat de la Population). The 1921 year book of the 
International Agricultural Institute gives for January 1, 1911, an estimate of 
138,274,500. This is inconsistent both with the estimate for January 1, 1910, and 
with the census of 1897, requiring an impossible rate of increase. It must refer to an 
area larger than that covered by the crop returns. 

F.— Ef'ONOMICS. 14S 

The first section of this table shows at four successive epochs — 1880, 
1890, 1900, 1910 — the total yield and acreage of corn and the yield per 
acre and per head of population in Europe as a whole (including Britain), 
with corresponding figures for coal, iron ore, and steel. The second 
section gives coiTesponding facts for the principal countries settled from 
Europe — Australia, New Zealand, the United States, Canada, and parts 
of South America. The third section covers Eui'ope and its settlements 
together, practically the whole of the ' white man's countries.' The 
figurps for each epoch represent an average of years, genorally six, 
centering about the end of tlie year named. The records are not abso- 
lutely complete ; one or two small European countries have been left 
out altogether; one or two gaps at the earlier epochs have to be filled 
by estimate or interpolation. The substantial accuracy of the main 
results is beyond question. 

The European section shows at each successive epoch a greatly 
increased population and acreage under corn, and a production increasing 
faster than either, so that yield per head and yield per acre alike both, 
rise materially and steadily. Nature's response to human effort in 
agriculture, on each unit of soil and for each unit of total population 
in Europe, has increased, not diminished, up to the very e\e of the 
War. Needless to say, this greater production of corn has not Ijeen 
due to a shifting of population from industry to agriculture, and has 
not been offset by a decline of manufacturing. The general movement 
of population has probably been in the opposite direction, from agricul- 
ture to indu.stry ; the output of coal, iroii ore, and stoel, the hasio 
materials and products of industry, lias rison 3'fct moro rapidly than 
I lie output of corn. 

There is no trace of reaction, either in industry or in agriculture, 
in the last ten years of the table; nothing to suggest a turning-point at 
1900. It is true that the rate of increase in the yield of corn per head 
n,nd per acre from 1900 tO' 1910 is less than in tlio precetling decade, 
but it is as great as in the decade from 1880 to 1890. In any case, a 
slowing down in the rate of increase proves nothing. Corn is produced 
only to be consumed, and there is a limit to consumption. In 
the best and most progressive of all possible worlds, the consumption, 
and so the production, per head of wheat, rye, barley, and maize could 
not rise endlessly; when saturation-point had been reached the yield 
per head of these elementary necessaries would cease to rise, and the 
people would use their increasing powers over Nature to win luxuries 
and leisure. Something of this movement is already seen in the growth 
of wheat at the expense of rye between 1900 and 1910. 

The second section of the table, covering the countries settled from 
Europe, begins only in 1890, but can be continued to 1920. It shows 
a very similar picture, not a markedly better one, in agriculture up to 
the War. From 1890 to 1910 the yield per acre of wheat has increased 
in the settlements a little faster than in Europe (15 against 12* per 
cent.), but that of all crops taken together has increas^ more slowly 
(4 against 18 per cent.). The yield per head has also increased for 
wheat a little faster in the settlements than in Europe (25 against 
19 per cent.), and for all crops a little more slowly (11 against 12j per 

192.'? t. 


cent.). The actual yield per head is, of course, much higher in the 
settlements; the yield per acre is lower for wheat, though higher for 
the other crops. 

In general, as we find Euroi)ean agriculture! more progressive than 
might have been expected, so we find the superiority of the new lands 
in that field less clear. It is in the industrial field, with doubled or 
trebled output of coal, iron ore, and steel per head between 1890 and 
1910, that the progress of Europe's settlements is most marked. 

In the third section of the table, taking Europe and its settlements 
together, we see progress, botli in yield per acre and in yield per head 
of the four crops, more marked from 1900 to 1910 than from 1S90 to 
1900, and nothing to suggest a limit to the expansion of the white 
races in the countries which they hold. 

Tlie inclusion of Russia in nny statistical table induces an element 
of uncertainty; it is difficult to be sure that figures for successive years 
relate to the same area. As a check upon this a second table has been 
prepared, giving figures for ^Yestern and Central Europe ; that is, Eiu'ope 
without Russia and Poland. The broad results of this table from 1880 
to 1910 are the same as those for Euiope as a whole. The yield per 
acre for each crop and for all crops together is at each epoch higher 
than when Russia is included and has increased more rapidly. Tlie 
yield of all crops per head of population has also inci'eased, though 
less rapidly than for Europe as a whole; this is natural, for the exclusion 
of Russia means the exclusion of a country which has suffered least 
from urbanisation.- 

The main interest of the second table lies in the fact that it can be 
continued to a fifth epoch — 1920— after the War. It shows that at that 
epoch the total production of wheat in Western and Central Europe 
was back again near the ]joint where it stood in 1880; for the four 
crops together, production was about half-way between 1880 and 1890. 
In acreage under cultivation Europe had gone back still further, pro- 
bably fifty years at least ; the yield per acre was at the point whore it 
stood twenty or thirty years before. The population of course was 
much greater. Taking the years 1920-1921 together, two and three 
years after the last shot of the Great War had been fired. Western and 
Central Europe in total agricultural production had gone back a genera- 
tion ; in production per head of population it liad gone back fifty years 
and more. If Russia and Poland could be included the comparison 

=■ The maintained increase in the yield per acre and per head of total popu- 
lation in Western and Central EnrniDe i.i reniaikable. in view of the common 
assumption that in * old countries ' the point of maximum return to agriculture 
has lon£j been reached. Unfortunately actual census figures of occupations are 
available only for seven countries (Austria. Belgium, Denmark. France. Huncrary. 
Italy, and the United Kingdom), omitting all-important Oermanv : these show 
for the seven countries a stationary yield of corn per head of the total popula- 
tion and a markedly higher yield per head of the agricultural population in 
1910 than in 1900 or 1890. The figures themselves are open to criticism, but if 
seems safe to assume that in Western and Central Europe as a whole, with 
the great industrial states of Germany and Britain, the agriculturists form, 
from 1880 onwards, a diminishing proportion of the total copulation : per head 
of those actually employed on the land the yield must have risen yet more 
markedly than appears in the tables. 


















Total Production 

(1000 quarters) 

























Four Crops . 






Area under Crops 

(1000 acres) 

























Four Crops . 






Yield per Acre 


Wheat . 
























Four Crops . 






Yield per head 


Wheat . 
























Four Crops . 






Note to Table II. 

The countries included up to 1910 are those forming ' Europe ' in Table I, with the 
exception of' Russia and Poland. 

For 1920 the area is nearly but not quite the same. The Polish war gains from 
Germany and Austria, being reckoned with Poland in the latter year, are excluded. 
On the other hand, Bosnia, Herzegovina and Montenegro (now part of the Serbo-Croat- 
Slovene state), Bessarabia (gained by Rouraania from Russia), and the Serbian and 
Bulgarian gains since 1910 from Turkey are included. So far as can be judged, 
the excluded regions are somewhat less in area (122,000 square km. against 165,000) 
and somewhat greater in population (11,000,000 against 6,000,000 in 1911) than those 
included ; that is to say, the term ' Western and Central Eurojje ' in my table represents 
a slightly larger area and a slightly smaller population in 1920 than in 1910. The differ- 
ences, however, are unimportant ; substantially the exclusions and inclusions balance 
one another and the total regions remain comparable. 

M 2 


\\'ould bo worse. To' point the contrast, we Have the figures for Europe's 

settlements; from 1910 to 1920 a. further growth of acreage under 
crops and of crops per acre, and a yield per head of population only 
slightly less. 

This D'esiili is only incidental to tlie present inquiry. The main 
object of my calculations has been to test whether the facts suggested 
any diminution of returns to agriculture in Europe between 1900 and 
1910. Having regard to Mr. Keynes' words, I expected to find in the 
last years before the War a falling yield in Europe, balanced by increased 
drawing on the virgin lands of the new world. Actually we find in 
Europe, decade by decade to the) eve of war — jjopulatiou rising, acreage 
under corn rising, total production rising still more, sO' that we get a 
greater yield per acre and per head of the total population.^ 

The Movement of Corn Prices. 

The answer to our second question, as to the real cost of corn, is as 
certain and hardly less surprising. If before the War it was becoming 
' necessary year by year for Europe to offer a greater quantity of other 
commodities to obtain the same amount of bread,' the money price 
of corn must have been rising relatively to the money price of other 
commodities. There is no trace of such a rise; the movement was in 
the opposite direction ; up to the eve of war the price of com was falling 
relatively to the price of other commodities. 

Table III shows the movement of wholesale prices from 1871 to 
1913 as ]-ecorded in the two best-known Biitish indices : that of the 

3 Detailed examination of the figures yields a number of interesting results 
which can only be briefly indicated here : 

(1) The progress shown for all the countries taken together represents a 
general movement in the fifteen countries taken separately. Taking wheat 
alone, from 1880 to 1910 every country for which figures are available shows 
a large increase in the yield per acre, varying from 18 per cent, in France to 
68 per cent, in Germany, and averaging 43 per cent. ; the other countries show 
large increases from 1890 to 1910. Even from 1900 to 1910 of the fifteen countries 
every one but three sliows an increased yield per acre; ttie Qiiited Kingdom is 
stationary and France has a trifling decline ; the Danish figures are incomplete 
and abnormal. More surprising still, every one but four (Belgium, France. 
Holland and United Kingdom) shows an increase of wheat per head of total 
population in the decade. F<jr crops other tlian wheat the figures are less 
uniformly progressive; generally between 1900 and 1910 yield per acre increased 
in each country for eacli crop. excei>t barley (wliidi increased in eight and 
decreased in six countries), but yield per head of total population increased only 
for wheat. Tliis greater progress of wheat is in itself a sign of greater ease 
rather than stringency ; it represents a rising, not a falling, standard of life. 

(2) During tlie thirty years 1880 to 1910 the total acreage under each crop 
and the yield per acre, in Europe as a whole, have both grown. But the rates 
of growth for acreage and for yield per acre vary inversely. The acreage has 
increased most for barley (41 per cent.); next for wheat (38 per cent.); next 
for maize (33 per cent.) • and least of all for rye (2 per cent.). The yield per 
acre has risen most for rye (45 per cent.) ; next for maize (22 per cent.) ; next 
for wheat (19 per cent.) ; least for barley (13 per cent.). This is an interesting 
statistical confirmation of expectations based on economic theory. The greater 
total production has been secured in wheat and barley mainly by bringing fresh 
lands under cultivation ; in maize and rye, mainly by getting more out of lands 
already cultivated. 

Relative Movements in Wholesale Prices. 
Board of Trade Index. 


As percentages of all 


Meat & 


articles (Col. 1) 

























59 ! 
























76 1 






102 101 



.rbeck Index. 

As percentages of 





all articles 

(Col. 1) 

Vegetable j Minerals i 

Food 1 ! 

1 I 

' (1) 



(4) (5) 

1851-60 . 



































89 ! 122 ! 





87 126 1 





87 107 





90 1 117 





92 117 





82 104 

Board of Trade and that of Sauerbeck. Both indices refer formally to 
the United Kiu^^loni only, bub thcro can bo littlo danger in taking 
them as an indication of world conditions; United Kingtiom prices 
from 1871 to 1913 must have followed world pi-ices in all important 

From the early "seventies prices generally first fell heavily to alx>ut 
1896 and then rose, though not to the height from which" they had 
fallen ; that is to say, the value of money in reUition to commodities first 
rose and tlien fell. Through this complete reversal in the movement 
of prices generall}', the price of corn in relation to other articles has 
moved steadily — and downwards. Decade by decade from 1871 and 
to the last three years before the War the price of corn, as recorded by 
the Board of Trade, has fallen relatively to prices as a whole (column .5)"; 
with less reRuhirity, but even more markedly, the relative price of cord 
and metals has risen (column 7). The result of these two movements 
is startling; to get in 1911-13 the same amount of corn as in 1871-80 
or 1881-90, it would have Ijeen necessary to offer, not moi'e coal and 


metals at the later than at the earlier dates, but one-third less. The 
Sauerbeck index leads to substantially the same results ; it shows 
from 1871-80 onwards a steady fall in the price of vegetable food 
and an eA'en greater rise in the price of minerals relatively to all 
articles (columns 4 and 5); the cost in terms of minerals of a given 
quantity of vegetable food would have been one quarter to a third less on 
the eve of the War than it had been a generation before. Both indices 
point emphatically to a falling, not a rising, real cost of corn. 

Index numbers of wholesale prices are open to criticism, in tliis 
connection as in many others, because they refer mainly to raw products 
and give little or no representation to manufactured articles. It would 
be consistent with the figures quoted above to argue that though the price 
of coal and of other minerals, whicli are the basis of manufacturing, 
had risen relatively to corn, the price of manufactured articles them- 
selves as a whole had fallen relatively to corn. Such a result, para- 
doxical as it is, could occur in two ways : either if increases in manu- 
facturing efficiency reduced the cost of manufacture or distribution, 
or if a superfluity of labour fit only for industry, as distinct from 
agriculture, reduced the reward to sucli labour, by an anioant suflicient in 
each case to outweigh the increased cost of coal and other minerals. 
The first is a real possibility; it is just in the spheres of manufacturing 
and distribution that inci'eased efficiency most naturally accompanies 
a growth in population and that invention and organisation win their 
last victories over diminishing returns. But a cheapening of manu- 
facture in this way involves not a decreasing but an increasing return 
to each unit of labour in industry; it would cause a fall of the real 
cost of corn measured in labour. The second way assumes a fall in 
real wages of industrial workers both absolutely and relatively to those 
of agnculturists such as quite certainly has not taken place in Europe. 

In regard to Europe as a whole we find no ground for !Malthusian 
pessimism, no shadow of over-population before the War. Still less 
do we find them if we widen our view to embrace the world of white 
men. Mr. Keynes' fears seem not merely unnecessaiy but baseless; 
his specific statements are inconsistent with facts. Europe on the eve 
of war was not threatened with a falling standard of Ufe because Nature's 
response to further increase in population was diminishing. It was 
not diminishing; it was increasing. Europe on the eve of war was 
not) tlireiatened with hunger by a rising real cost of coi'n ; the real cost 
of corn was not rising; it was falling. 

Room for Expansion. 

I have dealt at some length with Europe before the War because 
that is Mr. Keynes' theme; in his view the society that seems bent on 
self-destruction by the Carthaginian peace tliat crowned the War was 
already in deadly peril from Nature. If now, with better assurance 
as to the past, we look for a moment at the distant future of the 
European races, the first though not the only point for consideration 
is the extent of the world's untouched or half-used resources in land 
and minerals. On tliis point, unfortunately, the existing information 
goes only part of the w-ay. It is certain that enormous areas of the 


earth which are fit for cultivation are not yet cuUivated at all, and that 
of other ai-eas only the surface has beeii scratched ; but it is not 
certain how great the areas that could l)e cultivated are; how much 
of the land that is now unproductive of anything must for ever remain so. 
In most European countries from 70 to 95 per cent, or more of the 
total area, is now classed as ' productive ' ; it is being turned to some 
use — as arable, pasture, forest, and the like. In nine provinces of 
Canada (excluding the desolate Yukon and North-^Yest Tonitorics) 
the percentage of all the land that now produces anything is 
8, in Siberia IS, in Australia 6, in South Africa 3. Even for the 
United States it is only 46, and for European Eussia 55.* 
Part, no doubt, of the ' unproductive area ' in all those countries is 
beyond possibility of cultivation; it is impossible on the piesent infor- 
mation to say how large a part. But the figures as they stand are 
eloquent of how little the European races have yet done to fill the 
lands that they hold; how ample the room for their expansion. Any 
suggestion that these races h.a.\e reached or are within sight of territorial 
limits lo their growth hardly deserves serious consideration. 

Material Progress in Britain. 

lb is reasonable to suppose, however, that Mr. Keynes, though he 
speaks throughout of Europe, though he emphasises his Euro^x^an 
standpoint, was at heart concerned mainly for his own country, and 
may thus have generalised impressions derived from Britain. For us 
;it least the position in these islands, rather than that in Europe or in 
the world as a wliole is of prime importance If we look at Britain in 
the last years before the \Yar and ask if all was then well and the 
prospect cheerful, we get no clear answer to our question. The picture 
that our economic records paint is half in shadows ; to many the shadows 
will seem ominous of ill. 

Unfortunately on this issue, so vital to our interests, the use of 
statistical tests is peculiarly difficult. The yield of our soil in agricul- 
ture is cleaiiy irrelevant; only less so is the yield in such elementary 
industries as coal or iron mining or pig-iron production. Britain is 
essentially a manufacturing, commercial, and financial country; the 
return to its labour is measured by its output or gain from finished 
articles and services which themselves, by their infinite variety, escape 
all measurement. Current statistics both of production and of prices 
refer mainly to raw materials or food ; they miss the main features of 
British economic life and service. 

With this warning I invite consideration of the accompanying table 
of 'Material Progress in tlie United Kingdom relative to Population.' 
The table shows at six successive epochs, beginning with 1860 and 
ending with 1910, the course of some of the most important indices of 
economic conditions. The figure for each epoch is an average for ten 
years in which tlie epocli is central ; thus for ' 186(1 ' the average of 
1855-64 is taken, for '1870' the average of 18()5-74, and so on; for 
the last epoch, ' 1910.' the average is for the nine years 1905-13 
alone ; all War years are omitted. The various indices cover the activity 
•* I nttr national Yearbook of Ai/iirn/hira/ Stafisfli-.s-^ VJ'21. pp. 20-21. 




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of five important industries (coal, pig iron, shipbuilding, cotton, wool), 
measured either by production or by consumption of raw material, and 
of our export trade as a whole ; the course of ' real wages ' and of ' real 
income,' i.e. of money rates of wages and of money income per head, 
corrected to allow for changes in the purchasing power of money ; the 
consumption of certain articles of food and drink; and housing. The 
influence of the growth of the population and the influence of fluctua- 
tions in prices have both been eliminated. The figures are presented 
in two ways; the upper half of the table gives actual figures of pro- 
duction, consumption or ' leal income ' per head; the lower half gives 
the same' figures as index niuriljei-s in which the figure for 1900 is 
taken = 100 and forms the basis. Comparisons with this critical epoch 
are thus made easy. What does the table show? 

It shows, first, for eveiy separate index a marked and almost un- 
broken rise, epoch by epoch, to the last but one in 1900. There are 
occasional reactions (as with pig iron from 1880 to 1890 or cotton in the 
following decade), but these are only ripples on a powerful and rapid 
stream. From starting-points of about 50 or 60 the various indices 
moved in fifty years to 100; the general progi-ess from 1890 to 1900 
was not less than in previous decades. Unquestionably up to 1900 
the average producti\ity and pi-0'S])erity of each unit of the jjopuhifiou 
rose as the number of units rose ; there was a rapidly increasing return 
to labour as a whole. This was the complacent Victorian Age which 
led the world in material progress and piled up savings without effort. 

The tabic sliows, next, from 1900 to 1910 a inore interesting but 
more dubious picture. With one exception — real wages — every index 
has risen, but with two exceptions — coal production and exports — the 
rise is slower than in previous decades, and in niore than one case 
is barely j)erceptib]e. Running our eyes along the last three lines of 
the table, we see pig iron going fi-om 93 in 1890 to 100 in 1900 and 
only 101 in 1910; shipbuilding goes 82, 100, 105; wool 96, 100, 102; 
real wages 91, 100, 100; real income 87, 100, 1D2; consumption of foo<l 
and drink 91, ]00, 102; housing 95, 100, 104. In index after index 
a ra])id rise to 1900 is followed by a smaller rise, or by no rise at all, 
to 1010. In cotton there had been reaction fi'om 1890 to 1900; the 
resumed progress to 1910 was at much below the former avcrnse rate. 
Only in coal production and exports is the rapid progress of Victorian 
days maintained or accelerated ; those two indices i-epresent largely one 
factor, not t\\-o, for coal more than anything else swelled our recent 
exports^ In every other case, rapid ceitain growth to 1900 gives place 

* Curiously enough coal is the product for which a diminishing return to 
labour in this country, not since I'JOO merely but long before, seems to be most 
detinitely established. In relation to the number of poisons actually employed 
in mining the output has fallen rapidly, from 32t tons per head per annum 
in lH81-a5, to 288 tons in l.Si)5-99 and 1.'51 tons in I'.tO'JV.i. If we conibino thesi? 
ligures with those showing the relative movement in the wholesale prices of 
coal and of corn, we find that the amount of corn that could be bought by 
one person's output of coal in a year rose 30 per cent, from 1881-85 to 1895-99, 
and was stationary from llien to 1909-i;5 : as tlie hours of work had been 
reduced between the two latter epochs, the real cost in mining laliour of a given 
quantity of corn had continued to fall slightly even in Britain. The increasing 
response of Nature to agricultural effort was just more than sufficient to out^ 
weight the effects of her diminishing response to the British miner. 


to small and dubious improvement in the next ten years. This is the 
cramped, uneasy, envious, but not impoverished age of Edward. 

None of the indices, indeed, records an actual decUne ; all still 
show progress however small. Even if the index of ' real wages ' 
— stationary from 1900 to 191(J — be accepted without question, the 
workman was slightly better off at the later epoch, since hours of work 
were less; he was getting the same wages for a shorter week. We 
cannot speak of a falling return to labour ; at most we see a lower rate 
of increase, such as might, or might not, precede an actual fall. The 
contrast, however, between the Victorian and the Edwardian ages is 
unquestionably disturbing. In Britain, if not in Europe as a whole, 
the tm-n of the century seems to bring a turn of fortune. What con- 
clusions are we to draw? What remedies, if any, can we apply? We 
shall find reasons for not being too ready to despair of the common- 

The Edwardian Age and its Meaning. 

In the hrst place, there is ground for optimistic doubts as to iho 
figures themselves. Several of them, particularly the indices of real 
income, real wages and consumption, are elaborate structures based 
largely on estimates; others are suspect for various reasons; none need 
be believed to the death.' And even if the structure be sound, no 
established index of material prosperity can be expected to rise in- 
definitely. Progress involves change. When a nation has reached a 
certain point in the consumption of necessaries, it will utilise further 
purchasing power, not in consuming more of those necessaries, but in 
other ways : in buying bananas and condensed milk instead of more 
bread or meat, in tasting leisure, education, travel, football, cinemas, 
and other delights which do not appear in any index. So there may be 
a saturation-point in production ; after putting its growing strength for 
many years into shipbuilding or cotton a nation may find greater need 
for its services in other directions — in transport, commerce, or finance. 

' Two special causes of doubt are worth mentioning : — 

(1) The presentation of the figures as averages for particular decades, 
necessary as it is in order to give witliin reasonable space a summary picture 
of the whole, is deceptive, because the various decades are unequally affected 
by the phases of the trade cycle. The years 1895-1904 contain but one year 
of sliglit depression (190-1) and an undue proportion of ' good ' years. The 
nine years 1905-13 contain the end of the slight 1904-5 depression and the 
whole of the exceptionally severe depression of 1908-9. Tlie course of cyclical 
fluctuation unfairly weights the comparison against the later epoch. 

(2) The falling off of cotton, not only in the last decade but ever since 1880. 
is in large part apparent only. British industry was concentrating more and 
more on fine counts, using more spindles and pioducing more value for tlie 
same weight of raw cotton. 

A point on tlie other side, i.e. making the comparison unduly favourable 
to later epoclis. is the change in tlie age-constitution of the population. The 
I)t)puhiliuii ill 1910 included a liir^ei' piopoititm of adults and a smaller pro- 
portion of children than that of 1900; production and consumption * per head' 
should have been slightly higher to maintain the same standard in relation 
to capacity. The correction to he applied on this account is too small to 
disturb the comparison appreciably. 


In the second place, even if we admit, as I, for one, am prepared 
to admit, that there was some real change in our conditions, some 
faltering in our progress in the first years of this century, it may yet 
he no more than a transient phenomenon, a result of special causes not 
pointing to permanent chiinge. At the turn of the centuiy we do in fact 
find special and temporary iiilluences disturbing our ordinary develop- 
ment. One of these is the South African War; that war, like other 
wars, probably caused a greater loss of savings than of human life; it 
would leave capital scarce relatively to labour and in a stronger position 
to bargain. Another is the change in the movement of prices. Just 
before 1900 the falling tide of prices turned. From 1900 to 191.3 we 
lived on a rising tide. This also is an element favouring capital as 
against labour, profits rather than wages. Yet another special intluence 
at the turn of the century is a change in the rate of labour supply, due 
partly to the course of birth- and death-rates more than twenty years 
before and partly to the development of compulsory education. This 
point calls for explanation. 

In 1876 the birth-rate in this country reached its maximum. At 
the same time, or just before, important steps were taken for the 
improvement of public health ; the death-rate, which had changed little 
for thirty years, began to fall, and fell steadily thercai'itcr. There 
followed a quarter of a century later, as a wave follows a distant earth- 
quake, an abnormal growth in the supply of adult labour. As has 
been pointed out by l\Ir. Yule, the number of males aged twenty to fifty- 
five rose 19 per cent, from 1891 to 1901, as compared ^vith a rise of 
14 per cent, from 1881 to 1891, and 10 per cent, in earlier decades.' 
If we take five-year averages the rate of natural increase (difference of 
birth- and death-rates) reached its highest points in the years 1 870-1880 
and 1881-1885. Normally, this wonld have shown itself first by large 
numbers of boys entering the labour market in the early 'nineilies. At 
the same time, however, the Education Acts were withdrawing more 
and more boys nnder fourteen into the schools. The State dammed 
up the rising flow of juvenile labour for a year or two. The main 
pressure in the labour market began to be felt latei-. i.e. about 
1900, and presented itself as the ' problem of boy labour," which was 
really the problem of those who had got boys' work easily enough 
between fourteen and twenty (replacing the younger children kept at 
school), but found themselves in difficulties when they reached man's 
estate. This abnormal movement was bound, for the time at least, to 
disturb the balance between the growth of capital needed to employ 
labour and the growth of labour seeking employment. Some temporary 
pressure in the labour market was inevitable. It might cause a check 
in economic progress as measured per head of the total population ; it 
would certainly, iTi the bargaining between labour and capital for the 
division of their joinlj product, make labour for the moment relatively 
weak and capital for the moment rolativily strong because scarce. 
Wages would lose relatively to profits. 

' See Mr. Yule's paper on 'Changes in tlip Birtli ;uk1 >t;ir liaise TJ.-itos' in 
the Journal of the TJoyal Statistical Society, March 1900. 


All these special influences favoui- capital against labour. It is in 
accord with them that, of all our economic indices, that which shows 
worst, the only one that shows no progress at all from 1900 to 1910, is 
real wages, the reward to labour; that which almost alone shows con- 
tinued progress at the full Victorian rate is exports, to be explained 
perhaps in large measure as the surplus profits of capital. 

With these points in mind, we reach an economic interpretation of 
the Edwardian age, i-easonable in itself and consistent with other than 
economic records. That age does not live in our memories and will 
not live in drama and fiction * as a season of hard living and hard labour. 
It comes back to us now rather in the guise of the ball before "Waterloo, 
as an episode of unexampled spending and luxury ; as the time when we 
saw om' roads beset by motors, our countryside by golfers, our football 
grounds by hundred thousand crowds and a new industry of book- 
makers, our ballrooms and dining-rooms by every form of extravagance. 
The smooth development of Victorian days was broken, but the charac- 
teristic of the time was rather inequality of fortune than general mis- 
fortune ; discontent rather than poverty ; a gain by capital in relation to 
labour, by profits in relation to wages, by some classes of workmen at 
the expense of others, even more than a check to our progress as a 
nation. Some check to our national progress there probably was, but 
we are not bound to believe that the check was permanent. The three 
factors described above — the earthquake wave of labour supply, the 
South African War, and the upward turn of prices — are all peculiar to 
their time. The relative shortage of capital would tend to produce its 
own corrective. Difficulty in absorbing an abnormal flood of new 
labour does not prove permanent over-population; if all the hundred 
million persons who now find room and growing opportunities in the 
United States had landed there at once they would all have starved.' 

In the last three years before the War we find in nearly all indices 
resumption of a rapid upward movement. What would have happened 
if the War had not come? Would the Edv/ardian age have proved a 
passing episode of unrest or the beginning of a serious threat to our 
prospeiity? This is one of many questions whose answer is buried 
in the common gi'ave of war. 

In the third place, even if the new century was to see in 
Britain a lasting and not a transient harshening of conditions, if the 
rich ease of the Victorian agei had gone for ever with Victoria, 
there is little ground for surprise. Malthus or no Malthus, it 
was not reasonable to expect Britain to keep up for ever the speed 
that marked her start in the industrial race. Providence liad not 
conceiitraled in these islands the coal and iron supplies of all tlie 
world. As the United States and Germany and France developed their 
o\yn mineral resources, Britain was destined to find her general indus- 
trial supremacy challenged, now in one field now in another; she 
would be driven to discover and maintain those branches of work in 

8 Sonia, hy Stephen McKenna ; Tono-Bunfjay, By H. G. Wells; The Reqent 
by Arnold Bennett. ' 

' This is pointed out by a recent author, Mr. H. Wright, in Population, 
p. 110 ( ' Cambridge Economic Handbooks,' 1923). 

F.— ECONOMICS. 1.'53 

which she had the gi'eatest economic advantage, and to withdraw from 
the rest. Tins pixjcass of challenge and adjustment was bound to 
occur irrespective of tlie growtli of population, and as it fK-ciUTcd to 
give rise to strains and pressures; when accomplished it might yet 
leave room for jnogress, if not at the full Victorian pace. 

Of Britain before the War we may conclude that the position called 
for serious thought, not tears or panic. The economic records are open 
to diverse readings. The check to material progress in the Edwardian 
age may in part have been less than appears, and in part real but due 
to transient causes. At worst our industrial rank was challenged, not 
destroyed; forgetting some of the slacknesses of oiu- easv davs, we 
might through science and system and industrial i>eace have won a 
new lease of rapid progress. In this direction lay our remedy; in this, 
I think, rather than in hastening the process of birth restriction which 
had begun a generation before. 

Britain and Austria after the War. 

Let us pass to Britain aiter tlie War. Here, statistical tests of 
progress must be abandoned altogether. War's disturbance of our 
economic life and all its standards and records is barely subsiding; to 
found judgments of the future on the course of production or wages 
or prices in the years of demobilisation is vanity. Judgment by re- 
corded results is impos!\ible ; we are driven baclv to general considera- 
tions for an estimate of prospects in this new but not better world. 

The first principle of population to-day is that under conditions of 
economic specialisation and international trade the population probk'm 
in any particular country cannot profitably bo considered without 
reference to other eoimtries. The pioblem iii e\ery country is a prob- 
lem of the distribution of the population of the world as a whole. The 
actual density in different regions of the earth varies fantastically, 
accoiding to the pait which that region ))lays in the life of the world, 
from less than one person per scpiare kilometre in Canada or three in 
the Argentine, through 186 in Britain, or 245 in Belgium, to 760 in 
Monaco or 3,538 in Gibraltar. '" The ' optimum density " " for any 
one country at each moment depends not solely or even mainly upon 
its own resources of natural fertility or mineral treasure, on its own 
achievements of technique or co-operation, but on how in each of these 
matters it compares with other countries, on whether other countries 
are prospering or depressed, on the relations of its own i>eople— in 
respect of peace or war, of trade or tariffs — towards other peoples. 

Britain illustrates this principle more clearly than any other great 

'° These figures relate to 1911 and are taken from Table I of the Inter- 
national Yearbook of Agricultural Statistics. A remarkable instance of the 
density possible to a purely agricultural population is presented liy Java and 
INladura, which in 1921 hada population of 35,000,000, living 26C to" the square 
kilometre, more than the most crowded industrial states of Europe. This 
involves of course a Chinese .standard of life. 

" That is. the density which will bring the largest return per head of the 
population. Of. Cannari, Wealth, p. 68, and Carr-Saunders, The Population 
Problem, pp. 200 seq. 


country, because of all great countries Britain has grown to be the 
least self-sufficient, the most highly specialised, the most dependent 
on trade and peace and world-wide co-operation. A pregnant analogy 
will make the position clear. 

In Central Europe, before the War, lived, undex" one dynastic ruler, 
a congeries of communities known collectively as the Austro-Hungarian 
Empire. Tliese communities formed together a single economic unit, 
a free-trade area with fifty million Inhabitants, in which eivei7 stag© of 
economic activity, from the simplest agriculture to the most developed 
finance, was strongly represented, in which all the separate functions 
came to be distributed locally according to economic advantage without 
regard to internal boundaries. Some regions — east and south — were 
predominantly agricultural ; in the north-west were extractive industries 
of coal and iion, and manufactures founded upon them; further south 
were other manufactures, and the main seat of commerce and finance. 
Here was timber; there water-power. Each industry tended to settle 
where it could most profitably be carried on. Within each industry 
local specialisation often went very far; th\is, in cotton, one region 
pi-edominated in the first and final processes (spinning and bleaching), 
another had m-ore than its share of intermediate processes (such as 
weaving) ; the locomotives for railways came to be built in one region 
and the waggons in another. In the centre lay Vienna, a natural 
meeting-point entrenched by art in a system of radiating railways, con- 
centrating on itself the most advanced stages of social life — fine manu- 
factures, commerce, distribution, transport, finance, administration — 
a large and prosperous head directing and nourished by a large body. 
While the Austro-Hungarian Empire lasted, this headship brought with 
it the first place in prosperity. The wealth, pleasure, and extrava- 
gance, no less than the govei'ument, education, science and art, of 
fifty millions made Vienna their centre. 

The War came and went, and with it went the Empire. The 
dynastic ruler disappeared; the congeries dissolved; each community 
became a separate body desiring and needing a separate head, aiming at 
self-sufiiciency, seeking it by economic barriers against intercourse. 
Tn that break-up the average prosperity of all the fifty millions has sunk. 
Nearly every region is in some way poorer than before. But no region 
has suffered as much as Vienna; in none does the loss take the 
characteristic appearance of over-population. Vienna remains a head 
grotesquely too large for the shrunken body of German Austria, mani- 
festly over-populated, as little able to support its former numbers at 
their former standard, as would be Monaco if the nations gave up 
gambling or Gibraltar if they gave up war. It is over-populated, not 
through exhaustion of its natural resources, not because in the past its 
people were too prolific, but because the world outside has changed 
too suddenly. 

Be vohift falnila — the fate of German Austria is the moral for Britain. 
No other country of comparable size is so highly specialised as Britain. 
None produces so small a proportion of the food that it requires, or 
of the raw materials of its industries. None is so pre- 
dominantly engaged in the advanced ranges of economic activity; 

F.— ECONOMIOS. l-'»7 

in industry ratliKsr than agriculture; in finisliing processeis 
rather than the extraction of raw material; in transport, commerce 
and finance', rather than manufacture. No other country, therefore, 
is so completely dependent upon the restoration of peace and ti'ade 
and economic eo-operation. None is destined to suffer so acutely from 
any general disorder. At this moment perhaps none is suffering so 

It is needless to seek in excessive fecundity an explanation of our 
present troubles. There are other reasons, enough and to spare, why 
we should expect now to suffer from unexampled unemployment. Two 
exceptional causes of unemployment are now added to the normal 
movement of cyclical fluctuation. One is the difficulty of passing from 
war and war industries to peace — the difficulty of making swordsmen 
into ploughhoys. The process of training and directing the new sup- 
plies of laliour to fit the changing needs of industry has been broken by 
the War; there is a maladjustment of quality between labour supply 
and labour demand. The second cause lies in the damage done 
by this War and its aftermath to the economic structure of 
the world; the destruction of capital, the relapse of great nations towards 
barbarism, the breaking of easy and friendly intercotu'se. the con- 
tiinuince of war measures, the smaller volume of internaiional trade 
and its shifting into new channels. The world has changed suddenly, 
if less completely, round us as round German Austiia. Many of our 
trades find their former customers dead or impoverished or cut off by 
new barriers; the labour trained to those trades cannot shift to fill the 
gap in production which is left by the disappearance of those customers 
and their work. In both these ways, in terms which I used in writing 
of unemployment fifteen years ago, we have leading instances of those 
'changes of industrial structure' which leave legacies of enduring un- 
employment, to be reduced only as the labour ill-fitted for new needs 
is slowly and individually absorbed again or is removed by death oi 
emigration. '- 

The fate of Austria has a bearing not on war alone. The world 
may change otherwise than by war. The ' optimum density ' of popu- 
lation for any country may be diminished not by anything happeninj^ 
in that country, but by the discovery and exploitation of resources in 
other countries; possibly even by tariff changes. The more any country 
is specialised in its economic functions, above all if it is specialised 
in the most developed rather than in the primary functions, the greater 
is its liabdity to such changes. Britain, becoming j'early less self- 
sufficient, setting each year a swiftly growing people to more and more 
specialised labour, increasing each year its inward and outward trade, 
was before the War taking more and more the Austrian risk. It is 
arguable that with this lesson before us we ought no longer to take 
the risk so fully; should retrace our specialisation and aim at self- 
sufficiency — in practical terms, under a system of tariffs or bounties, 

'- Uncertainty as to the couise of piice.s. with its paralysing effect on 
business enterprise, ought perhaps to be named as yet another special cause 
of post-war unemployment. Alternation of upward and downward movements 
of prices is, of course, one of the elements in normal cyclical fluctuation. 


should grow more coin find do less trade. The practical 
answer to that argument is that we are already too far from 
self-sufficiency to make worth while any attempt to return. Any 
change great enough to diminish seriously our dependence on overseas 
trade, in other words our exposure to the Austrian risk, would involve 
an impracticahle reduction in our total population and our average 
wealth. A middle course that is sometimes suggested is to aim at 
self-sufficiency in the British Empii'e, by tariff arrangements favouring 
Imperial rather than foreign trade. The adoption of such arrangements 
clearly depends more on the wishes of the Dominions than on those of 
Britain, and their value for the pm-pose in view upon the readiness 
of the Dominions to acquiesce in a division of economic functions which 
would leaA'e the most advanced and most profitable ones to the Bi-itish 
Isles. It is more than doubtful whether this is the Dominion view of 
Imperial economics. In the last analysis, the long road which Britain 
has travelled to dependence on international trade, as general and as free 
as possible, will, I believe, be found to be irretraceable. Like the hero 
of one of Mr. Wells' novels, the Britain that we know, the Britain 
of forty millions, has been made for a peaceful and co-operative world; 
slio must try to create such a world if she does not find it ready to hand. 


Lei jne try to gather together tlie threads of this long discussion. A 
further quolatiuu from j\'lr. Keynes' writings will serve for a starting- 
] Mil I it : — ■ 

'The most interesting question in the world,' he writes, '(of those 
at least of which time will bring us an answer) is whether, after* a 
short interval of recovery, material progress will be resumed, or 
whether, on the other hand, the magnificent episode of the nineteenth 
century is over. In attempting to answer this question it is important 
not to exaggerate the direct effects of the late War. If the permanent 
underlying influences are favourable, the effects of the War will be no 
more lasting than were those of the wars of Napoleon. But if even 
before the War the underlying influences were becoming less favour- 
able, then the effects of the War may have been decisive in settling 
the date of tlie transition from progress to retrogression.' '^ 

The warning deserves attention. Yet, as I am less inclined than 
Mr. Keynes to be pessimistic about the tendencies before the War, I 
feel perhaps more pessimistic than he is in this passage about the effects 
of the War, and the possibly enduring damage it may have done and 
be destined to do to humanity. 

Before the War, as I have tried to show, there is nothing to suggest 
that Europe had reached its economic climax: Malthus' Devil, unchained 
again or not, cannot be found where Mr. Keynes professes to find him. 
For the world of white men as a whole there is even less ground for 
pessimism; the limits of agricultural expansion are indefinitely far. If 
we regard only that part of this world wliich is known as Britain, 

'' 'An Economist's View of Population,' in the Manchester Guardian Eecon- 
struction Supplement, Section Six (1922). 


judgment is not so easy. Sonic cliniigo did come ovcf our ecoiiioniic life, 
or certain parts of it, witii the tiuu of the century; our effortless supre- 
macy was challenged. Eeasonahle men may dispute, and since the 
decisive evidence has perished will probably dispute for ever, whether 
the unrest and uncertainty of the Edwardian age marked a passing 
episode destined but for the War to give place to a fresh stage of swiftly 
rising prosperity, or, on the other hand, reconled the first shock of 
permanent forces working to make life in these islands less easy and 
to set a term to material progress. 

After the War — for that phase, if indeed we have reached it, I doubt 
whether we may find much comfort in Napoleo^nic pamllels. The 
Napoleonic wars were wars between Governments and armies rather 
than peoples; they did not bite deeply into economic life; they left it, 
possible for the best contemporary fiction to show a picture of English 
society in which the nuhtary iigure chiefly as dancing pai'tners.^'' The 
war of 1 914-1 S was waged on millions of non-combatants, as much as 
on armies; it is being continued in the same form to-day; the economic 
stiiicture of the world, battered out of shape by four years of open war, 
is still twisted by human passions. The lesson of compulsory self- 
sufficiency has been learnt too well; in all parts of the world, by new 
economic barriers, nations are endeavouring to safeguard, at the expense 
of their native and natural industries, the industries which were forced 
on them by the extremities of war. The world is poorer in resources 
by its lost years and ruined capital; of those diminished resources it 
makes worse use.'* 

To sum up, for Europe and its races the underlying influences in 
economics were probably still favourable when the War began. But 
the war damage was great and we are not in sight of its end. Man 
for his present troubles has to accuse neither the niggai'dliness of Nature 
nor his own instinct of reproduction, but other instincts as primitive 
and, in excess, as fatal to Utopian dreams. He has to find the remedy 
elsewhere than in birth control. 

The Population Problem Remains. 

Let me add one woid of warning before I finish. Such examination 
as I have been able to make of economic tendencies before the War 
yields no ground for alann as to the immediate future of mankind, no 
justification for Malthusian panic. 

It has seemed important to emphasise this, so that false diagnosis 
should not lead to wrong remedies for the world's sickness to-day. 
But the last thing I wish is to over-emphasise points of disagreement 
with Mr. Keynes. The limits of disagreement ai-e really narrow. The 
phrases which I have criticised are incidental, not essential, to 
Mr. Keynes' main argument as to the consequences of the War and 
the Peace. And whether Mr. Keynes was right, or, as I think, too 

'•« Jane Austen's first three novels were written during the Revolutionary 
Wars (179G to 1798) ; her last three between Wagram (1809) and Waterloo (1815) 

>- The recent development of prohibitive tariffs is very fully described in a 
special supplement by Dr. Gregory to the London and 'Cambridge Economic 




pessimistic in his reading of economic tendencies before the War, he 
will be regarded as imqueationably nght in calling attention again to 
the importance of tlie problem of jx^pulation. 

Nothing that I have said discreditrs the fundamental principle of 
Malthus, reinforced as it can be by the teachings of modern science. The 
idea that mankind, while reducing indefinitely the lisks to human life, 
can, without disaster, use to the full a power of reproduction adapted lo 
the i:)erils of savage or prehuman days, can control death by ait and 
leave births to Natui'e, is biologically absurd. The rapid cmiiidative 
increase following on any practical application of this idea would within 
measurable time make civilisation impossible in this or any other planet. 
In fact, this idea is no more a fundamental part of human thought 
than is the doctrine of laissez faire in economics, which has been its 
contemporary, alike in dominance and in decay. Sociology and history 
show that man has hardly ever acted on this idea ; at nearly all stages 
of his development he has, directly or indirectly, limited the number of 
his descendants." Vital statistics show that the European races, aft«r 
a phase of headlong increase, are returning to restriction. The revolu- 
tionary fall of fertility among these races within the past fifty years, 
while it has some mysterious features, is due in the main to practices 
as deliberate as infanticide. The questions now facing us are how far the 
fall will go; whether it will bring about a stationary white population 
after or long before the white man's world is full ; how the varying inci- 
dence of restriction among different social classes or creeds will affect 
the stock; how far the unequal adoption of birth control by different 
races will leave one race at the mercy of another's growing numbers, 
or drive it to armaments and perpetual aggression in self-defence. 

To answer these questions is beyond my scope, as it is beside my 
purpose to pass judgment on the practices from which they spring. 
The purpose of my paper is rather to give reasons for suspending 
judgment till we know more. The authority of economic science cannot 
be invoked for the intensification of these practices as a cure for our 
present troubles. But behind these troubles the problem of numbers w aits 
— the last inexorable riddle for niankind. To multiply the nation and not 
increase the joy is the most dismal end that can be set for human 
striving. If we desire another end than that, we should not burk dis- 
cussion of the means. However the matter be judged, there is full 
time for inquiry, before fecundity destroys us, but inquiry and frank 
discussion there must be. Two inquiries in particular it seems well to 
suggest at once. 

The first is an investigation into the potential agricultural resources 
of the world. There has been more than one elaborate examination of 
coal supplies ; we have estimates of the total stock of coal down to 
various depths in Britain and Germany, in America, China, and else- 
where; we can form some impression of how long at given rates of 
consumption each of those stocks will last ; we know that ' exhaustion ' 
is not an issue for this generation or many generations to come. There 
has been no corresponding study of agricultural resources ; there is not 

" See The Problem of Popvtation, by A. M. Carr-Saundcrs. 


iiialoiial oven for a "iioss at. wliali pi-opoilion of Ihc vast regions — in 
Canada, Siberia, South America, Africa, Australia — now used for no 
productive purpose could be made productive; at what proportion of 
all the ' productive ' but ill-cultivated land could with varying degrees 
of trouble be fitted for corn and pasture. Without some estimate on 
such points, discussion of the problem of wo)'ld population is mere 
groping in the dark. The inquiry itself is one that by an adequate 
combination of experts in geographic, agricultural and economic science 
— not by a commission gathering opinions ov an ofitice gathering statistical 
returns — it should not be difficult to make. 

The second is an investigation into the physical, psychological, and 
social effects of that restriction of fertility which has now become a 
leading feature of the problem. This also is a matter neither for one 
person — for its scope covers several sciences — nor for a (•oiiuiiissiiiii ; 
tacts rather than opinions or prejudices are required. 

If the question be asked, not what inquiries should be made but 
what action should now be taken, it is difficult to go beyond the trite 
generalities of leconstruction, of peace and trade abroad, of el'licieiu-y 
and education at home. The more completely we can restore the eco- 
nomic system under which our people grew, the sooner shall we absorb 
them again in productive labour. Unless we can make the world again 
a. vast cO'-operative commonwealth of trade, we shall not find it spacious 
enough or rich enough to demand from these islands the special services 
by which alone they can sustain their teeming population. Even if the 
world becomes again large enough to hold us, we shall not keep our 
place in it with the ease of Victorian days; we dare no longer allow, on 
either side of the wage bargain, methods which waste machinery or 
brains or labour. Finally, if there be any question of numbers, if there 
he any risk that our people may grow too many, the last folly that we 
can afford is to lower their quality and go back in measures of health or 
education. Eecoil from standards once reached is the gesture of a 
community touched by decay. 

V 2 



Sir henry FOWLER, K.B.E., 


I FEEL that it is right that the Engineering Section of the Association 
here in. Ijiverpool should (levolo one ol its sessions to the subjeict of 
traction. There is no city in the Empire, or in the world, which is so 
dependent on traction in one way or the other as the one in which we 
are meeting to-day, and I can also say without fear of contradiction 
that there is no city in the world which has acted as so great a pioneer 
in traction development as this one on the Mersey. 

Its very birth was caused by the physical features it presented at a 
time when the estuary of the Dee was silting up, whilst whatever may 
be the derivation of the first portion of its name, there is no question 
but that the latter portion refers to the advantages it offered for water' 

It is not necessary, nor am I qualified, to speak of the development 
of the ' pool ' into the port which means so much to Liverpool at the 
present day, but there are other methods of transport in which it has 
played an important part that I should like to mention. 

As early as 1777 Liverpool realised the necessity and advantages of 
easy and cheap transport, and the canal from Liverpool to the Trent 
was constructed at that date, having a length of ninety-six miles. This 
joined the Trent at Shai'dlow, not far from Nottingham, and it has 
recently been suggested the river should be canalised from there to the 
sea on the East Coast. 

More recently Liverpool has become connected with its sister city of 
Manchester by the Ship Canal, in the carrying out of which many 
interesting engineering problems were met and solved. 

Tlie better-i-emembered event is, however, in connection with trans- 
port by rail. It was the construction of the Liverpool and Manchester 
Railway in 1829 and its immediate success that more than anything 
else impressed on the country the fact that a new system of traction 
was opening out unheard-of possibilities. It is not too much to say that 
tlie production of the ' Rocket ' for the trials at.Rainhill in October 1829 
mai'ked the first step in the practical commercial success of railways. 

This, however, has not been the last association of the city in pioneer 
work on the rail in this country. In 1904 the Liverpool and Southport 
section of the Lancashire and Yorkshire Railway was electrified, this 
being the first inter-urban electric line in this country. The change 
was due to the enterprise and foresight of Mr. (Sir) John A. F. Aspinall, 


a distinguished son of Liverpool, and the Directors of the Lancashire and 
Yorkshire Eailway. The electrification of the line was preceded by 
exhaustive trials to determine the tractive force required to overcome 
the resistance on railways/ and with these trials I had the honour of 
being connected. 

The other matter in which Liverpool has done pioneer work on 
traction is that of heavy motor traffic. From its inception in 1895 
the Liverpool Self-propelled TraCfic Association was specially connected 
with this method of transport. Under the presidency of tlie late Sir 
Alfred Jones, with the guidance of Dr. Hele Shaw and under the 
qi'ganising ability of its enthusiastic and energetic secretary, Mr. E. 
Shrapnell Smith, it organised and carried out trials of commercial 
vehicles in 1898, 1899, and 1901. In May 1898 were carried out the 
first practical trials of these vehicles held in the country, and I had the 
honour of being the observer of the fu'st lorry to leave the yard. The 
Motor Car Act of 1903, which allowed a practical weight for commercial 
road motor vehicles, was the result of a deputation of the Liverpool 
Self-propelled Traffic Association waiting on the President of the Local 
Government Board (the Eight Hon. Walter Long, now Viscount Long) 
when he was on a visit to Liverpool. 

I think I have said enough to justify the statement I made that 
it is fitting that one of our sessions here in this city of Liverpool should 
be devoted to the question of transport, and I wish to speak of its 
indebtedness to Science, and trust I may be able to show that, as 
with other branches of engineering, its progress is due to science, and, 
in concluding, speak of how it may repay, if inadequately, the debt 
under which it is placed. 

We are perhaps too apt at the present time to forget the obligation 
which the world owes to transportation, so commonplace have the 
improved methods become. We are already forgetting the lesson that 
the submarine menace gave us on this matter during the War, and 
again looking upon the movement of matter from point to point as a 
commonplace occurrence. It has been said that effective transporta- 
tion is one of the great aids to civilisation, but it must not be forgotten 
that all movement of material from place to place is economically waste 
as far as the dissipation of work is concerned. Problems of transporta- 
tion have been solved mo)'e or less successfully in all ages, and some 
of them, such as the moving of the stone to Stonehenge, &c., still excite 
our wonder and admiration. Such works, and similar ones of much 
greater magnitude in the East, however, we feel as engineers could be 
accomplished by quite crude methods if there was unlimited labour 
available and if time were of no consequence. 

The transportation which aids civilisation is that which cuts down 
the wastage of power to a minimum and which reduces the time occupied 
in carrving this out. It is here that science has helped in times past, 
and will help increasingly in the future if we are to go forward. In no 
other branch is Telford's dictum that the science of engineering is ' the 
art of directing the great sources of power in Nature for the use and 

■ Sec Mr. (Sir) J. .\. F. .\spinair.'! paper on ' Train Resistance,' Proceedings 
of the Institvtion of Civil KvginceTs, vol. 147, 1901. 



convenience of man ' so well exemplified, and this utilisation has been 
carried forward at ever-increasing speed during the last hunth'ed years. 

If we take the definition of Science as ' ordered knowledge of natural 
phenomena and of the relations between them,' as given by W. 0. D. 
Whetham in the ' Encyclopaedia Britannica,' we shall easily see how 
transportation has been dependent upon it. 

It may be that some may not agree with tins definition of ' ordei'e<l 
knowledge of natural phenomena, ' but I feel that after thought it will 
be recognised that it covers very completely what we call Science. We 
are rather apt to confuse the knowledge with the means and apparatus 
applied in getting it. Eecently I have read an article which called 
attention to the dependence of science upon engineering or mechanical 
achievement, but surely the accuracy we get, the lack of which was 
such a great drawback to the investigations of a century to a century and 
a half ago, is itself based upon ' ordered knowledge.' 

Dealing with transport, it may be said roughly that it is mainly 
dependent upon three things — the method of propulsion, the material 
available for use, and the path over which traction takes place. I cannot 
deal fully even with one of these, and propose to confine my remarks 
to the first two, which are the ones I am best acquainted with. 

It may be said that advance in traction really became rapid when 
methods of propulsion other than those of animals and the force of the 
wind became available. The greatest step forward — wonderful as some 
of the achievements of aeronautics have been of recent years — came with 
the development of the steam-engine. 

Like most great achievements in the world, it was not a lucky 
and sudden discovery of one individual, although here as elsewhere 
we associate the work with the name of one man especially. This 
has usually been the case, and without wishing to detract from the work 
of the individuals who are fortunate enough to utilise the ordered know- 
ledge available to the practical use of man, one must not forget the 
labours of those who have sought out that knowledge and have given it 
freely to the world, thus placing it at the disposal of the one whose 
imagination and creative faculty were gi'eat enough to see how it could 
be utilised in the service of man. 

Tlie first attempt at traction by using a steam-engine was a failin-e 
because of the lack of tliis knowledge. I refer to the work of Jonathan 
Hulls and his attempt in 1736-7 to apply one to the propulsion of a boat 
on the Eiver Avon in Worcestershire. He failed because of the lack 
of that knowledge, although undoubtedly he possessed the necessary 

Although James Watt is not directly associated with traction, it was 
his application of science to practical use that finally gave the greatest 
impulse to transportation that it has ever had. No advance had taken 
place to Nowcomen's engine of 1720 until Watt's work of 1769. His 
knowledge of Black's work at Glasgow on the latent heat of steam and 
his own experiments with the Newcomen model led to tlie success of 
his itnprovements of the steam-engine. His scientific knowledge is 
clearly shown in his patents and publications, for he dealt with steam- 
jacketing in 1769, with expansive working in 1782, and he devised his 
]nirallel motion in 1784. His direct connection with transport includes 
the rcl'crenco lo' a stoani-cariiage and a screw-jn'opeller m 1781, wliilst 


the liiiu ol' Jioulluii it Watt cori-espotided with Fulton for a period 
extending from 1794 to 1805. 

Altiiougli Cugnot in 1770 and Murdoch in 17b6 had made models of 
vehicles propelled by steam, it was Richard Trcvithick with his stcam- 
earriagc in 1801 and 1803 and ill-fated railway in 1804 who first showed 
the practical application which could bo made. It is probable that the 
engine which his assistant, Steel, took to the wagon-way at Wylam in 
1805 turned the thoughts of George Stephenson to the work that has 
meant so much for us. No one can read the early life of the father of 
railways without appreciating that he was from young manhood a 
searcher after scientific knowledge. Doubtless he owed much to the 
friendship of Sir William Fairbairn, the President of our Association in 
]861. The ad^•a.nces he gave to the world of transport wei'e all duo 
to his pi-actical application of the knowledge he had obtained himself 
or had learned from others. It is so often thought that because the 
early inventors and engineers O'f the beginning of last century had not 
icceived what we now call a scientific education they were not in 
any sense of the term men of science. It must be remembered that at 
that time the knowledge of natural phenomena was very limited, and it 
was possible to know much more easily all the information available on 
a subject than at the present day, when we have such a mass of miscel- 
laneous information to hand on every conceivable subject. It was 
ordered knowledge which led Stephenson to adopt the blast-pipe of 
Trevithick. It was the desirability of obtaining ordered knowledge that 
caused him to carry out those experiments which showed to him the 
advantages of using rails, and it was the scientific appreciation of the 
necessity of increased heating surface that made him adopt the sugges- 
tion of using tubes through the water-space in the boiler of the ' Rocket.' 
His appreciation of the advantages of science was shown by his accept- 
ance of the Presidency of the Mechanical Science Section (then as now 
Section G) of our Association in 1838. It is interesting to note that 
one of the earliest grants in Section G was for a constant indicator (for 
locomotives) and dynamometric instruments in 1842-43, whilst 
Stephenson was still alive. Let me remind you of his ready grasp of 
the. application of a known principle to a different object by the story of 
the invention of the steaju-whistle. On the Leicester and Swanningtou 
Railway, which followed the Liverpool and Manchester, one of the 
Newcastle locomotive-drivers — R. Weatherhurn — at a level-crossing ran 
into the cart belonging to an old lady, destroying her eggs and butter. 
Upon his return to Leicester, and reporting this to Stephenson, he was 
at once told to go down the town to a trumpet-maker and get him to 
make a trumpet which could be blown by steam. None but a mind 
in which the knowledge of natural phenomena was very carefully ordered 
could have so readily solved such a problem. 

From the time of Stephenson the progress in propulsion on rails by 
steam-locomotives was steady if slow. The investigations for a long 
while were largely confined to' the question of expansion and condensa- 
tion, and although the results attained were noteworthy in the case of 
steamships, on the rail — to which for the moment I will confine myself — 
there was little advance in the principle of propulsion, but, as I shall 
show later, the improvements in materials allowed a steady growth in 



power and size. Although work was done by compounding and using 
higher pressures, the gi-eatest advance has come to stearn -locomotives 
by the use of superheated steam. This was no new thing, for Papin in 
1705 seemed to have an appreciation of its value. As pressures and the 
resultant temperatures increased there came difficulties with lubrication. 
With the increased use and knowledge of mineral lubricants Dr. Schmit 
was in 1895 able to devise methods of using superheated steam which 
have been of the greatest use to transport and to the community. 

The progress of transport on the rail has latterly strongly followed 
other hues, and I must for a few minutes go back again to the develop- 
ment of the use of steam in a turbine in order to speak of the subject 
of electric traction. 

In spite of the fact that the idea of the utilisation of steam for giving 
rotary motion is old, its commercial adaptation in the turbine is modern. 
Earely, if ever, has there been such a direct and instantaneous applica- 
tion of science to practice. We are too close at present to the matter 
to reahse what a change has taken place in the world owing to the 
introduction of the steam-turbinei. 

If we think for a moment we shall realise what a change has come 
over our lives, not only in an engineering but in a general sense, since 
the end of last century. It has ti'uly been said that this is very largely 
due to an Italian experimenting with Hertz waves, to numberless young 
men lying on their backs on muddy roads under motor-cars, and not 
least to a young Irish engineer who revolutionised transport. 

One realises the work done by De Laval, Curtiss, Eateau, and the 
brothers Ljungstrom, but the name which will always be associated with 
the steani-turbinei as firmly as that of James Watt is with the inception 
of the steam-engine is that of Sir Charles A. Parsons, our President 
for the Meeting of 1919 at Bournemouth. The success of his work is 
due to his application of scientific principles to the many points of the 
turbine and its accessones. Apart front its application to marine work, 
it is the turbine which has made possible tb.e economical production of 
electrical energy, which is doing so much, and will do so much more in 
the future, for rail transport. To-day it may be said, as it often has 
been, that there are no mechanical or electrical difficulties in the elec- 
trification of railways, the only difficulties being financial ones, although 
one could hope that the induction troubles could be overcome by a 
cheaper method than at present available. 

It is impossible here to trace the development of electrical science 
from the experiments described by Gilbert in 1600 to the equipment of 
electric locomotives on the railways of Switzerland and the United States 
of America. If we were able to trace this development we should see 
that it has been not only a gradual but a continuous and ordered increase 
of knowledge of natural phenomena. One must mention, however, 
what a change electrical traction by train and tube has made to our 
town life. It has rendered our large towns possible and given a chance 
to millions of our workers of a wider outlook on life and the opportunity 
of living amongst healthier and more pleasant surroundings. This, as 
just stated, is not the result of a sudden discovery of some fundamental 
principle, but to a studied advance, step by step, from very elementary 
knowledge to the information wo have available and at oui" disposal 


to-day. This is very largely the result of endless laboratory research 
and experiment. 

The last method of propulsion that I can deal with is that by means 
of the internal-combustion engine. This, as we almost universally have 
it to-day, is the result of the cycle adopted by N. A. Otto in his gas-engine 
in 1876. Here again the engines we have to-day are the result of careful 
and studied investigation. It may be truly said that the advance made 
has been so much more rapid than in the case of the steam-engine and 
electrical machinery because of the more advanced state of scientific 
knowledge, and it furnishes an example of the assistance which this 
gives to progress. 

In relation to transport the work has proceeded on two distinct lines, 
the Daimler and the Diesel engines. In 1885 Gottlieb Daimler produced 
the engine that is associated with his name, and which utilises a light 
spirit which supplies a carburetted air for the explosive mixture for the 
cylinder. The development of this engine has itself proceeded in two 
directions. In the one it has been made very much more flexible and 
silent in its adaptation to motor-car work, whilst in the other the great 
desideratum has been lightness and in association with the improvements 
in the necessai-y materials has rendered possible the aeroplane as we 
have it to-day. In both cases the development to the degree reached 
has been due to a careful study primarily of the pressures, compression, 
and composition of the mixture. 

The Diesel engine was invented in 1894 by Eudolph Diesel, and 
consists of the injection of oil or pulverised fuel into the engine cylinder. 
Its development has taken place both on the four- and two-stroke cycle, 
and although considerable progress has been made with land engines, 
it has chiefly been used for marine transport. 

The internal-combustion engine has not been largely used for rail 
transpoi't owing to its comparatively high cost of fuel per horse-power 
and its lack of flexibility. The latter is particularly the case when one 
remembers the high torque which is so desirable, and which can be 
attained in both the steam and electric locomotives in starting. 

Throughout these remarks on methods of propulsion I have dealt 
with the points connecting them with rail transport as they occurred, 
as this is not only the method with which I am most familiar, but is the 
oldest means of using mechanical power. I must, however, say a few 
words as regards transport by sea, road, and air in connection with 
methods of propulsion. 

I have already spoken of the early efforts of Hulls, and it was only 
natural that the woi'k of Watt on land should be followed by application 
of the new power available to propulsion on the water. Although the 
growth after the work of Symington, Fulton, and Bell may have seemed 
to be slow, it was continuous, and constant experiments and reseai'ch 
were made both in marine engines and in their application. Saving of 
fuel has played a much more important part here than with the loco- 
motive, whilst, more space being available and greater power required, 
the advantages of the expansion of steam were rendered more imperative 
and had greater scope than in the other long-established method of 
mechanical transport. The groat advance came with the turbine, and 
it is interesting to notice that wlicrons in early days engines wore geared 


up, most of them now are geared down to the screw. Scientific methods 
have been aj^phed to all those details of measurement and exjieriment 
that have led to transport by sea being carried on at increased speed 
and with decreased cost per ton carried. The application of liquid fuel 
and the introduction of Diesel engines, both with the object of increasing 
the space available for cargo, have been earned out on true scientific 

Of transport by road it may be said that its commercial inception 
came at a time wdien scientific knowledge was well advanced, and its 
progress was in consequence more rapid. It must not be forgotten that 
in the fairly early part of last century considerable work was done on 
scientific lines with steani-cars, only to be abandoned when legislation 
made its continuance impossible. The development of the motor-car 
engine from the small unit of Daimler to the present car is undeniably 
due to the use of ' ordered knowledge ' of the gaseous mixture, of its 
ignition, of the fuel itself, and of the compression that should be 
employed. Plere again we have a case of the careful application of the 
principle developed with ever-increasing care until we get engines as 
noiseless, as efficient, as reliable, and as flexible as we have them to-day. 
It is a case, too, where the development is so recent that many of us can 
remember the scorn and distrust that this method of traction excited 
even here in this city that was so prominent in its inception twenty-five 
years ago. 

Very much more could be said as to the indebtedness of aeronautics 
to science, but the fact that this indebtedness is so self-evident, as well 
as the question of space at my disposal to deal with a subject of such a 
size, make it impossible to attempt to do justice to this part of my 
subject. I will speak only of the, and its development has been 
even more rapid than that of the motor-car. I personally feel this when 
I remember that Mr. A. V. Eoe was one of my students here in 
Lancashire in the 'nineties. 

It was not until the development of the internal-combustion engine 
that the matter became a really practical one. The early work of Santos 
£)umont, Henry and Maurice Farman, Willjur and Orville Wright, 
A. Vernon Eoe, Cody, Rolls, Bleriot, Paulhan, and others led to the 
close scientific consideration of the whole problem. 

Step-by-step investigations have led towards the perfecting of this 
type of transpoi't. In all cases the developments have followed careful 
scientific research. Amongst our fellow-countrymen the work of Eolls, 
Godden, Cody, Busk, Keith-Lucas, Hopkinson, Pinsent, and others 
has unfortimntoly been terminated bv their deaths in the cause to which 
they were devoting their lives. In no other field has scientific work 
demanded so great a toll. This must lie so when one is dealing with 
transport in such a medium as air. The work of others, such as — to 
name but a few — -Bairstow, De TIavilland, Sopwith, Barnwell, Handley 
Pn^e, B. M. Jones, and O'Gorman, has fortunately continued. The 
War was naturally a great incentive to the advancement of our know- 
ledge of aeronautics, and I feel proud that at Farnborough, at the Eoyal 
.\ircraft Factory, I was allowed to be assocint-od with such men as 
Aston. Dobson, Farren. (ribson. Green, Grinstend, Llill, In'ing, Linder- 
man, Thompson, and McKinnon Wood. 


These weru scientific men working on scientific lines, and their work 
was put to full practical test at once. The mass of information collected 
and used has been immense. One cannot in any collection of names 
omit one to whom one must ever be grateful — Sir Richard Glazebrook, 
again a son of Liverpool, who not only as Director of the National 
Physical Laboratory, but also as chairman, under the presidency of 
Lord Rayleigh, of the Advisory Committee of Aeronautics, did so much 
to\varcis the (levek>pment of this method of transport. 

It is impossible to touch more than in the lightest possible manner 
on the developments which have taken place in aeronautics due to scien- 
tific work. In the means of propulsion research has given an engine 
of such size and so light in weight per horse-power that what was a 
laboured struggle against the effects of gravity has changed into the 
ability to rise at considerably over 1,000 feet per minute to heights where 
the rarefaction of the atmosphere renders it necessary for oxygen for 
breathing to be obtained aitificially. The safety of flying as the result 
of the work of Busk has rendered the machines stable even in such a 
medium as tlie air. There is no greater instance of the indebtedness of 
transport to science than the rapidity with which the possibilities of 
transport by air have advanced. That the realities have not advanced 
at the same rate is due to financial reasons. As a rule we have a close 
relationship between these two, but in this instance, owing to the de- 
mands of war, this has not been the case, for we have tbe knowIe<lge 
before we are financially able to use it to the greatest advantage. 

The other point I would deal with in some detail is the question of 
materials. Here we are dealing with a matter which has to be con- 
sidered in an entirely different manner. We to-day have no basic metal 
or material which was not known when transport first turned to 
mechanical methods for assistance. The change which has come about 
has been as largely due to the advances made in metallurgy as to the 
inventions in mechanics that have led to the improvements in means 
of propulsion and in machinery. I am aware that neither of these 
would have been of any use were it not for the increase in facilities of 
production, but most certainly the scientific work of the metallurgist is 
one of the many points which, taken together, have caused the resultant 
progiX'KS. Tlie early l)uikk'rs of steam-engines were not only ti'oubled 
through inability to get their engines machined properly, but also with 
the difficulties of obtaining suitable material for the parts they required. 
Steel has been known for thousands of years, but its rapid and economic 
pi'oduction is of very recent growth. It has very truly been said that 
every great metallurgical discoveiy has led to a rapid advance in other 
directions. I will as before deal with the railway as an example. We 
can hardly appreciate at this date the conditions which existed from a 
metallurgical standpoint on our railways when our first Meeting at 
Liverpool was held in 1837. Ti'on — inndo laboriously, heterogeneous 
in character and expensive of production not only in money 
but, owing to the heavy character of the methods employed, 
detrinieiitnl to tho very character ol the workman — was the only 
materiol available. Remember for a moment that tbis was not only 
tlie material employed for the various pai-ts of tho mechanism of the 
IdcoHiolivc, but for tlic rails. TT(v\vover iin])rove<l the nH'tl)o<ls of 


manufacture were, there could never have been a universal development 
of rail traction if it had depended upon material made in such a way. "We 
ai'e especially interested in the manner the growing demand was met, 
for it was at the Cheltenham Meeting of the Association in 1856 that 
Bessemer made public the invention he had already been woi-king on 
for two years, and which was to insure a cheap method of production 
of a material so essential to transport. One should mention with 
Bessemer the name of Mushet, whose work helped so materially in 
getting rid of the red shortness which in the early days gave such trouble. 
We are apt at the present day, I am afraid, to somewhat belittle the 
work of Bessemer in view of the more improved methods now employed, 
but his name must for ever stand out as the one which made cheap 
transport possible. After the use of manganese in one form or the 
other as a deoxidiser and a ' physic ' for sulphur, there, however, still 
remained the baneful effect, due to phosphorus, which prevented the 
use of the ores of more general occurrence. There have been few more 
epoch-making announcements made at meetings of technical subjects — 
although this was not appreciated at the time by many of the audi- 
ence — than S. G. Thomas's announcement of the discovery of the ' basic ' 
process, which he made at the meeting of the Iron and Steel Institute in 
March 1878. I say advisedly that many did not appreciate the news, 
for an old friend of mine who was present was impressed by the earnest- 
ness of the remarks of Thomas and the little notice taken of the short 
statement made. His work, associated with that of his cousin, Gilchrist, 
was the result of close scientific research. 

Another investigation which has given great results in transport has 
been the ever-growing use of alloy steels. For the scientific inception 
of these we owe a great debt to Sir Eobert Hadfield, whose inventive 
genius and scientific mind are still active in that field he has made so 
particularly his own. His first investigations materially affect transport 
to-day. It is true that Mushet had previously worked on self -hardening 
tool-steel containing tungsten, but the woyk was carried out only on a 
small scale. In 1882 Hadfield had produced manganese steel." This 
is a most remarkable product with its great toughness, and is exten- 
sively used for railway and tramway crossings, where resistance to 
abrasion is of great value. This was the first of that very remarkable 
series of alloys about which I must say a few words, for they have made 
possible the motor-car and the aeroplane as we have them to-day. 
Continuing his investigations, in 1889 Hadfield produced the compound 
of iron and silicon^ known as low hysteresis steel. Indirectly this is 
of the greatest interest from a transport standpoint, as when used in 
transformers it not only reduces the hysteresis losses, but allows of a 
considerable saving in the weight of core material. 

From these early uses of alloy steels there has grown up a large 
number of various alloys, many of which are of the very greatest use 
for various transport purposes. It is not too much to say that the 
modern aeroplane is the result of the material now at the designers' 
disposal both for the engine and for the structure itself. The strength 

= Iii'^f. of Civil Engineers, vol. 93, 1888. 

' Iron and Stcd Imtihitc, p. 222, Pt. II, 1880. 


of some of the chrome-nickel steels combined with their ductihty is 
extraordinary, and is due not only to the composition of the metal, but 
to the results which have been obtained by patient scientific investiga- 
tions x'elating to their heat-treatment. Taking one otlier example, one 
may quote the use of high clirome steel — for the early investigations 
into wliicli we owe so mucli to Brearley, and for its later developments 
to Hatfield also — for the valves of aeronautical engines, subjected as they 
are to high temperatures. At one time it looked as if the advantages 
which follow high compression and its resultant high temperatures 
might be lost owing to the inability of ordinary steels to resist this heat, 
but the employment of 13 per cent, chrome steel allowed work in this 
direction to be continued. Not only the aeroplane but the motor-car 
is, as has previously been s'aid, the result of the work done on alloy 

It is not only with steels that we have been benefited so much from 
research. The case is as marked with light alloys, which have alu- 
minium as a base. The latter itself is the result of investigation along 
scientific lines, and in aeronautical work particularly much has been 
done towards giving a metal both light and strong by the work of Walter 
Piosenhain, F. C. Lea, and others. 

It may be said that all I have dealt witli up to the present has been 
the result of special investigation, and that ' ordered knowledge ' is not 
of assistance to an everyday engineer such as myself. I may perhaps 
be forgiven if I refer to some personal work where the collection of that 
knowledge, with the assistance of rny colleagues, especially 1j. Arclibutt 
and H. A. Treadgold, has been of great assistance to that large transport 
institution, the Midland Railway, with which we were so long asso- 
ciated. I have dealt briefly with the subject in a general way in a paper 
I read a little while ago before the Institution of Locomotive Engineers,* 
but would like to speak of it in more detail and in view of the fresh 
information that is now available. I would first speak of the results 
obtained witli solid locomotive crank-axles. Here we have a large mass 
of metal which in the rough state w^eighs about 40 cwt. It is forged 
from the ingot into a block about 25 in. by 18 in. in section, and this 
is then worked down at the two ends and in the middle to about 11 in. 
in diameter, the pieces of the original section of the block remaining 
being the throws, wliich are twisted to an angle of 90° to each other. 
A block about li in. thick is slotted out of each web, and from these 
the tests to which the crank is subjected are taken. Sometimes a crank 
has to be taken out of service owing to the journal wearing down below 
a diameter at which it is judged sa.fe for it to run, but more often 
flaws are developed, which, liowever, are progi'essive, nnd with ordinarv 
examination can be detected before any risk is taken in running. A 
crank-axle is an expensive portion of a. locomotive, and its replacement 
is not only costly but takes n considerable amount of time, as the driving, 
wheels have to be removed and replaced. These considerations have 
led us to give a good deal of attention to this piece of mechanism 
on what we believe to be scientific lines. Careful note has been taken 
not only of flie mechanical tests made on the portion removed from the 

* ln.':t. of Loco. Englnfrrs, vol, 12, 1021. 


throws, but of the inicio-structuie of the metal itself. The fust questio.n 
which rises in our mind is why the cranks develop flaws at all. It is, of 
course, known that with ordinaiy structures one is able to calculate the 
stresses in them, but this is not so with a locomotive crank-axle. Not 
only is it being subjected to the stresses set up by revolving it while 
it is loaded with the weight of a portion of the locomotive on its axle- 
bearings and by the steam pressure on the pistons transmitted to the 
crank-pins, but it lias to withsta.nd the shocks set up by its running on 
the rails, which cannot be calculated. These include the pressure set 
up on the edge of the wheels when entering a curve at a speed other 
than that which the super-elevation is allowed for, running over uneven 
rail joints and ci'ossings, and also what I believe is one of the worst, if 
infrequent, the striking of check rails. These stresses and the resultants 
of them are most severe at the corners of the crank-pins and at the I'adii 
where tlie webs or thi'ows join the rounded portions of the axle. Tht«se 
are the points at which flaws usually occur. 

For about twenty years we have endeavoured to get the knowledge 
we have obtained into an ordei^ed state, from observation and discussion 
with the metallurgists attached to the various manufacturing firms. 
Certain points are obvious, such as the necessity of a good mici'o-struc- 
ture, and whilst the details in connection with exactly what mici'o- 
structure is the best are somewhat uncertain and open to debate, we 
can with confidence say that the steel ' shall be as free as possible from 
non-metallic enclosures, and that the micro-structure should show 
uniformly distributed pearlite in a sorbitic or very finely granular or 
lamellar condition and be free from any nodular or balled-up cementite. 
It must also be free from any signs of segregation and from any coarse 
or overheated structure. ' (Extract from Midland Eailway specification 
for crank-axle forgings.) The dimensions I have given of the size of 
the block of metal from which the axle is made show that it cannot have 
received much work, and therefore any non-metallic enclosures present 
will be only slightly drawn out, and will not occur as threads as they 
do in bars of small diameter and even in steel tyres. One of the first 
observations we deduced was that the life of the crank in miles had a 
direct relation to the ductility of the test-bar taken across the section 
of the throw and near the centre of the original ingot. This is the point 
at which non-metallic enclosures are most likely to be found, as well 
as that at which the greatest stress occurs. The inference is obvious 
that a flaw is likely to develop at some sharp corner of such an enclosure. 
In a section of steel such as that which must be used non-metallic 
enclosures are very likely to occur, and so steps had to be taken to 
ascertain what the best practical remedy was. With decreased carbon 
content greater ductility was likely to follow, and this has been shown 
to be the case. In a word, it is toughness rather than strength which is 
required, . and the studied consideration of these points has led to an 
increased life in miles of the crank-axles of the 3,000 loco-motives owned 
by the Company, in spite of the fact that they have been constantly 
growing in size, in pressure on the pistons, and in the work expected 
from them. This is shown in the following curves, which represent 
the mileage of crank-axles scrapped in the last twelve years. 

(J— KNTlTNKI'.niNfJ. 










































Average Mileage obtained from Crank -Axles for Years 1910 to 1921 inclusive. 

It will be appreciated that the above result, which is unquestionably 
the result of ' ordered knowledge of natural phenomena and the relation 
between them,' is only one example, if perhaps the most marked one, 
in our experience. A somewhat similar one could, however, be written 
on locomotive tyres and other matters if space and time permitted. 

This example finishes my general remarks, and I cannot do so with- 
out expressing the indebtedness I feel to the various members of 
the scientific staff of our great firms for all the assistance and help they 
have ever so readily given us in the case I have just quoted. 

One would like to press home strongly on engineers generally a point 
made by Dr. Maw in his Presidential Address to the Institution of Civil 
Enginegrs in November last. He pointed out the lai-ge amount ol 
scientific knowledge — much of which was accumulated during the War — 
which is available at the present day. Here is the knowledge if we will 
but apply it to the service of man. This is our function as engineers. 
In times past we have had to wait for this knowle<^lge, and, as I trust 
I have shown, as it slowly became available it has been used in our 
service and in that of the world. One great need is for men with the 
education, the capacity, and the imagination necessary to use this scien- 
tific knowledge for the advancement of our profession. T use these three 
requisites advisedly, for each one of them is necessaiy to take full • 
advantage of the opportunities which now exist. The trouble is that 
whereas we can supply education, can increase the capacity of the indi- 
vidual, it is difficult to instil or cultivate that imagination which allows 
one to see the way iri which the knowledge available can be applied in a 
practical way. 


I think I have shown adequately the debt which transport, as well 
as other branches of our profession, owes to the study of ' ordered know- 
ledge. ' That in the future this will be even more marked than at present, 
one can say without fear of contradiction. Not only so, Init there nnjst 
be more and more interdependence between science and engineering. 
More and more as we advance — as we are doing so rapidly — in the 
knowledge of natural phenomena will the necessity of the practical 
application of this knowledge on a large scale become necessary to 
confirm it and to bring out fresh features. One trusts that our Associa- 
tion, which has done so much in this direction in the past, may continue 
increasingly useful in the branch of its work which brings together those 
whose work is purely scientific with those who are applying that know- 
ledge to the direct service of man. Although the old idea of antagonism 
between the two has disappeared, we cannot but feel that in spite of the 
advance of recent years the extent to which the engineer depends on 
the scientist for knowledge, and the scientist depends upon the engineer 
for the practical application of the knowledge he has gathered, is not 
realised as fully as it should be by either. The terms scientific and 
practical should ]ye synonymous. 

One vv"ould like to feel that the meeting of our Association was more 
generally used as the occasion on which the scientist 'and the engineer 
would meet in larger numbers. I know that the scientist is often an 
engineer, and that the engineer has nowadays to be a scientist with a 
broad outlook, but the personal contact of the two which this meeting 
offers gives an opportunity the results of which would be incalculable if 
that opportunity were fully grasped. If one might use an illustration 
which I trust will not offend my scientific friends, scientific knowledge 
is a tool of infinite possibilities, and this knowledge is possessed by so 
many who attend here. The practical engineer is always attracted by 
tools. There is no better method of ascertaining what new and im- 
proved tools of this type are available than by coming here. Beyond all 
this, personal acquaintance is of greater and more permanent value 
from every point of view than a paper acquaintance. 

I would like, in closing, to make an appeal for a freer disclosure of 
results obtained in practical working. This can only be done by taking 
care in noting the behaviour of apparatus, material, &c., in use, and 
placing the results freely at the disposal of the man of science and of 
the manufacturers. At the present day there is no lack of those who 
are trained observers, and I believe one of the troubles often encountered 
by manufacturers who are applying some new method is the difficulty 
of getting dependable figures of performance. With transport companies 
this should not be a difficult matter, for one great advantage they have 
now is that there is no trade necessity to hide their results in any way. 
It is one small way in which they can repay the great debt they owe to 
science, which has allowed them to complete so satisfactorily their task. 
As Kipling has so rightly and concisely stated : 

' It is their care that the wheels run truly, it is their care 
to embark and entrain. 
Tally, transport, and deliver duly the Sons of Mary by 
land and main.' 



Professor P. E. NEWBERRY, M.A., O.B.E., 


When I received the honour of an invitation to preside at the Anthropo- 
logical Section of the British Association my thoughts naturally turned 
to the subject of the Presidential Address, which, if 1 accepted the 
invitation, it would be my duty to prepare. On looking back over the 
Addresses of past Presidents of this Section since its institution in 
1884 I found that no one had dealt with Egypt as a field for anthropo- 
logical research. It was because of this that I decided to accept the 
Council's invitation, and I am here to-day to bring before your notice 
some facts regarding the civilisation of the country with which I have 
long been associated, and in which I have spent many years of my life. 

In 1897, when the British Association last met in this great city on 
the Mersey-side, Sir Arthur Evans occupied the Presidential Chair of 
this Section, and the subject of iiis address was ' The Eastern Question 
in Anthropology.' Surveying the early history of civilisation as far as 
it was then known, he insisted tliat the adequate recognition of the 
Eastern background was essential to the right understanding of the 
iEgean. He laid stress on the part which Crete had played in the 
first emancipation ol the European genius, and pointed out that in 
Crete, far earlier than elsewhere, can be traced the vestiges of primeval 
intercourse with the Nile Valley. Nineteen years later, years that 
were extraordinarily prolific in archfeological discovery in every part of 
the Near East, Sir Arthur occupied the Presidential Chair of the IBritish 
Association at Newcastle. He then addresse.d us on ' New Arehteo- 
logical lights on the Origins of Civilisation in Europe.' Referring to 
his epoch-making discoveries in Crete he said, ' It is Interesting to note 
that the first quickening impulse came to Crete from the Egyptian 
and not iwm the Oriental side; the Eastern factor in it is of compara- 
tively late appearance.' By that time Sir Arthur's researches had led 
him to the ' definite conclusion that cultural influences were already 
reaching Crete from beyond the IJByan Sea, before the beginning of 
the Egyptian Dynasties.' He further said 'the impression of a very 
active agency indeed is so strong that the possibility of some actual 
immigration into the island of the older Egyptian element, due to the 
conquests of the first Pliaraohs, cannot be excluded.' 

I propose to-day to deal with some of the questions relating to the 
origins of the Egyptian civilisation, and incidentally shall touch upon 

102.'{ ' o 


this Cretan problem. At the end of my address I shall very briefly 
refer to the much-neglected modern Egyptia.ns, and to the need there 
is to study them. Much has been written during the last twenty years 
about the origins of the Egyptian civilisation, but there are some 
facts which, I think, have either escaped notice or have not been duly 
considered, and there are others upon which, in my opinion, insufficient 
stress has been laid. I am not going to deal with the physical charac- 
teristics of the people, for that is not my province. I shall confine 
myself to certain inferences that I believe can be drawn from the 
monuments of pre-dynastic and dynastic times. 

It is generally agreed that the habits, modes of hfe, and occupations 
of all communities are immediately dependent upon the features and 
products of the land in which they dwell. Any inquiry into Egyptian 
origins ought, therefore, to begin with the question, What were the 
physical conditions that prevailed in the Lower Nile Valley immediately 
preceding, and during, the rise of its civilisation? Until this question 
is answered I do nob think that w^e are in a position to deal with such 
important problems as, e.g. — agriculture, architecture, shipbuilding, 
tool-making, or weaving. The first thing that we ought to know is 
what were the kinds of trees, plants, and animals that were to be found 
in Egypt in the wild state, and what was the economic value of the 
indigenous flora and fauna. We ought, in fact, to know what the 
country was like in pre-agricultural days. If there was no timber in 
the country, then it may, I think, be confidently said that the art of 
the carpenter did not originate in Egypt ; that the architectural styles 
founded on wood construction could not have arisen there ; that the ait 
of shipbuilding (at all events of building ships of wood) did not originate 
there. Similarly, if there were no incense-bearing trees or shrubs in 
the country, it is difficult to imagine that the ceremonial use of incense 
arose there. Again, the art of weaving presupposes the presence of 
sheep or goats for wool, or of flax for linen thread. All these kinds 
of problems depend upon the natural products of a country, or they 
did so depend in the early days of civilisation. 

We are accustomed to regard Egypt as a paradise, as the most 
fertile country in the world, where, if we but scratch the soil and 
scatter seed, we have only to await and gather the harvest. The 
Greeks spoke of Egypt as the most fit place for the first generations 
of men, for there, they said, food was always ready at hand, and it 
took no labour to secure an abundant supply. But there can be no 
doubt that the Egypt of to-day is .a veiy different place from the Egypt 
of pre-agricultural times. There has been a great, but gradual, change 
in the physical condition of the whole country. In the mortuary 
chapels of tombs of the Old and Middle Kingdoms, as well as in many 
of the Empire, are scenes of papyrus swamps and reed marshes; in 
these swamps and marshes are figured the animals and birds that then 
frequented them. Among the animals are the hippopotamus and the 
wild boar, the crocodile, the ibis, and a great variety of water-fowl. 
These animals, and some of the birds, have now disappeared from the 
region north of the First Cataract. Only very recently has the croco- 
dile become extinct north of Aswan. It was still occasionally seen in 



tho Delta as late as the middle of the eigliteeiitli. eeutiuy, and il was 
fairly plentiful in Upper Egypt up to tho m'uUWv of the ninctocntli 
century, but it is now rarely, if ever, seen north of ^Vadi Haifa. It is 
the same with tlie liippopotamus. In the twelfth centuiy this mammal 
still fretiuented the Damietta branch oE the Nile, and two specimens 
wei'e actually ]<illed near Damietta by an Italian surgeon in the 
year J(3()0.' " In ihe Dongola. Province of Nubia it was very <'0iiunon 
at the beginning,' of last century, and Burckhavdt states that it was 
then a terrible plague there on account of its voracity. In 1812 several 
hippopotami passed the Second Cataract and made their appearance 
at Wadi Haifa and Derr, while one was actually seen at Darawi, a 
day's march north of Aswan. = The wild boar is apparently now extinct 
in Egypt, but specimens were shot in the Delta and in the region of 
the Vs'adi Natrun during last century. The ibis has gradually dis- 
appeared from the Lower Nile Valley, whei'e it was once so common. 
The last specimen of this bird recorded in Egypt was shot in 1877 
in Lake Menzaleh. It is sometimes seen in Lower Nubia, but has 
now entirely disappeared from Egypt proper. 

Much is known about the ancient fauna of the desert wadies from 
the paintings and sculptured scenes in the tombs of the Old and IMiddle 
Kingdoms and of the Empire. On the walls of many of these tombs 
are depicted hunting scenes,^ and among the wild animals figured in 
them ai-e the lion, leopai-d, Barbary sheep, wild ass, wild ox, hartebeeat, ' 
oryx, ibex, addax, dorcas gazelle, fallow deer, giraffe, and ostrich. As 
several of these animals are not now krtown in Egypt it has been 
argued that the scenes do not faithfully represent the ancient fauna 
of the country. But I can see no reason to doubt that the scenes 
depict actual hunts that took place in- tho Arabian and Libyan Deserts 
not far fi-om tliO' localities in wliicli the tonil)S figuring tlieni aie found. 
There is some corroborative evidence in the references in the ancient 
literature to the hunting of the wild animals that frequented Egypt. 
Thutmose IV., for example, hunted tiic lion and ibex in the desert 
plateau near Memphis; " .\menhotep III. killed 102 fiei'ce lions dui'ing 
the first ten years of his reign,' and in his second regnal year he hunted 
wild cattle in the desert near Keneh ; * he saw there a herd of 170, 
and of these he and his huntsmen captured 96. The desert to the east 
of Kuft was a fa.raous hunting-ground at the time of the Eighteenth 
Dynasty. At the present day all but one of the animals represented in 
these ancient hunting scenes are Tound in the Nubian Deserts to the 
south of Egypt. Tho exception is important; it is the fallow deer, 
which belongs to the Holarctic, not to the Ethiopian, zoological zone. 
Although most of the animals that wei'e hunted by the dynastic Egyp- 
tians have now d-isappeared from their northern home, many have been 
recorded in i-ecent years as occurring in the Arabian and Libyan Deserts. 
We can, in fact, follow them gradually receding southwards. The 
dorcas gazelle is still common in both deserts, and the addax some- 
times occurs in the region of the Wadi Natriln. The ibex is occasionally 
seen on the mountains nortli-east of Keneh. The Barbary sheep 
(Ammotrarius fraqela-plius) was observed by Dr. Schweinfurth in 1878 
in the Wadi Shietun. whicli opens on the Nile below Ekhmim.° 'Die 



wild ass was recorded by James Burton in 1623 in tlTe desert north-east 
of Keneh ; he remarks that then the Arabs of this part of the desert let 
their female donkeys loose to be served by the wild males/ Later, in 
1828, Linant de Bellefonds saw many wild asses in the region between 
Darawi and Berber; they were, he says, often trapped by the Bisharin, 
who used the flesh as food. During the first half of the eighteenth 
century the ostrich frequented the desert near Suez/ A hundred years 
later it was reported to be numerous in the Arabian Desert opposite 
Esneh, and there is a wadi, some distance south-east of Aswan, that 
is called by the Arabs Wadi Naam, 'the "Wadi of Ostriches.' In the 
Libyan Desert the bird was fairly common in the eighteenth century. 
W. G. Browne, who travelled along the coast west of Alexandria in 
1792, states that tracks of the ostrich wei-e frequently seen, and he noted 
also that the bird sometimes appeared in the neighbourhood of the 
Wadi Natrun." Geoffroy Saint-Hilaire in 1799 reported that it was tlien 
common in the mountains south-west of Alexandria.^" In 1837 Lord 
Lindsay saw the ostrich near Esneh," but the northern limit of the bird 
is now very much further south. The lion is mentioned by Sonnini at 
the end of the eighteenth century as one of the larger carnivora wliich 
then approached the confines of Egypt, but did not long remain in the 

Now the appearance of all these animals in Egypt and in its border- 
ing deserts in dynastic times presupposes that the vegetation of the 
wadies was mucli moi-e abundant then than now, and this again pre- 
supposes a greater rainfall than we find at present. The disappearance 
of the dynastic fauna is not, however, entirely due to the change in 
climatic conditions. The Arabs have a saving tliat it was the camel 
that drove the lion out of Egypt, and this is doubtless true. The 
lion depends mainly on the antelope tribe for its food supply. The 
antelopes, on tlie other hand, depend for their sustenance on herbage 
and givass, and this lias Been consumed to a great extent by the camels, 
which, since Arab times, have been bred in great numbers in the 
Arabian and Nubian Deserts. It is certain that the advent of the 
camel was a factor in driving southwards many of the wild animals 
tliat were at one time so common in Egypt, but are now characteristic 
of the Ethiopian region. 

The characteristic wild trees of the dynastic flora of Egypt, as we 
know from the remains of them that have been found in the ancient 
tombs, were the heglik (Balan'ites aqyptiaca), the seyal {Acacia seyal), 
the sunt {Acacia nilotica), the tamarisk {Tamarix nilotica), the nebak 
{Zizyphus spina-Christi), the sycomore-fig {Ficus sycomorus), and the 
moringa {Moringa aptera). The dom palm {Hyphtene tJiehaica) and 
the Dellach palm {H. argiin) were also common. The heglik does not 
now grow wild north of Aswan, and, of the other trees, only the sunt 
and the tamarisk are really common in the Lower Nile Valley. All 
these trees, however, now grow in abundance in the region north of 
the Atbara, and it is here, in what is called the Taka country, that we 
find also the fauna that was once so abundant in more northerly regions. 

But if the fauna and flora of the Arabian and Libyan Deserts in 
dynastic times approached more closely to that now seen in the Taka 



country, we have to go further south agaiu for the earhest pre-dyuastic 
fauna and flora of the Lower Nile Valley. This pre-dynastic fauna is 
particulai'ly interesting, l^ecause, in addition to several of the animals 
already mentioned as occurring in dynastic times, we meet with others, 
such as the elephant,'" the kudu (Stropceros Icudu),^' the gerenuk gazelle 
[Lithocranius tt'a/ier/)," a species of Sus^^ (which is certainly not the 
wild boar, i.e. Siis scrofa), and the marabou stork [Leptoptilns 
crumenifer).^^ From the nature and habits of these mammals and 
birds it is evident that there must have been a considerable rainfall in 
tlie Valley of the Nile north of Aswan when they frequented Egypt. 
V)v. Anderson has referred to this subject in his monograph on the 
Eeptilia of Egypt. He notes that the physical features on both sides 
of the Nile ' indicate the existence of a peinod long antecedent to the 
present, in which a considerable rainfall prevailed, as in the eroded 
valleys of the desert may be observed rocky ravines which have been 
cai"ved out by the action of water, which has left behind it diy channels 
over which waterfalls had once precipitated themselves, and others 
down which cataracts once raced. The rainfall of the present is not 
sufficient to account for such a degree of erosion. ''° This evidence 
sanctions the conclusion that a matenal change in the character of the 
climate of North-Eastern Africa, so far as its rainfall is concerned, has 
taken place since pre-dynastic days. The flora of the valley of the 
Tiower Nile also' points to the same conclusion. Dr. Schweinfurth" has 
drawn attention to the fact that many plants, now known in Egypt 
only under cultivation, are found in the primeval swamps and forests 
of the White Nile. He not unreasonably draws the inference that in. 
ages long ago the entire Nile Valley exhibited a vegetation harmonising 
in its character throughout nmch more than at present. The papyrus 
swamps and reed marshes that lined the Lower Nile Valley in prc- 
agricultural days have been changed into peaceful fields, in wliich now 
grow the cereal grains, wheat and barley, and the other crops that have 
made Egypt famous as an agricultural country. It was the canalisa- 
tion of the Valley, carried out by man, and the consequent draining 
of the swamps and marshes that displaced the ancient flora from its 
northern seat, and made it, as at the pi-esent day, only to be found 
hundreds of miles higher up the river. The land of Egypt has, in 
ifact, been drained by man ; each foot of ground has been Von by the 
sweat of his brow with difficulty from the swamp, until at last the 
wild plants and animals wliich once possessed it have been completely 
extemiinated in it. The agricultural Egypt of modern times is as 
much a gift of man as it is of the Nile. 

I have dwelt at some length on the ancient fauna and flora because 
I want to bring out as clearly as I can two facts concerning the Egypt 
of pre-agricultural days— the Egypt of the time before man began to 
win the alluvial soil for the pui'poses of agriculture. (1) The aspect of 
the Lower Nile nuist have been very different from wliat it is now; it 
was a continuous line of iiapynis swamps and marshes inliabited 'by 
liippopotami, wild boars, crocodiles, and immense flocks of wild-fowl 
of all kinds; it was singularly destitute of trees or plants that could 
be ]n\i to any useful purpose, and timber-trees were non-existent • its 


physical conditions resembled those prevailing on the banks of the 
White Nile to-day. (2) The deserts bordering the Lower Nile Valley 
on both sides were much more fertile, and their fauna and flora 
resembled that of the Taka country in Upper Nubia. Of the animals 
that frequented the wadies only the ass and the wild ox were capable 
of domestication. If man inhabited Egypt in pre-agricultural times — 
and there is no valid reason to suppose that he did not — he probably 
lived a wandering life, partly hunter, partly herdsman, in the fertile 
wadies that bordered the valley, only going down to the river to fish 
or to fowl or to hunt the hippopotamus. In the valley itself there 
was certainly no pasture-land for supporting herds of large or small 
cattle. It was probably also in these wadies that agriculture was first 
practised in Egypt. Even at the present day a considerable number 
of Ababdeh roam the wadies of the Arabian Desert between Keneh 
and the Eed Sea, where, at certain seasons of the year, there is fair 
pasturage for small flocks of sheep and goats. I have myself seen 
many of these people in the course of several journeys that I have 
undertaken to the Eed Sea coast. Some of these nomads sow a little 
barley and millet after a rain-storm, and then pitch tlieir tents for 
a wlrilei till the grain grows, ripens, and can be gathered. They then 
move on again with their little flocks. What the Ababdeh do on a 
very small scale the Hadendoa of the Taka country do on a much 
gi'eater one. 

If we turn to the Taka country we see tliere people living under 
much the same physical conditions as those which nmst have prevailed 
iu thci Arabian and Libyan Desei'ts in early times. Tlio inhabitants 
of the Taka country are Hamite, and, as Professor Seligman has pointed 
out,^* the least modified of these people are physically identical with 
the pre-dynastic Egyptians of Upper Egypt. I would suggest that 
they, like the fauna and flora of ancient Egypt, receded southwards 
under the pressure of the advance of civilisation, and that the physical 
conditions of the country have preserved them to a great extent in their 
primitive life and pursuits. The picture of the Taka as Burckhardt 
draws it would, I believe, desci'ibe almost equally well the earliest pre- 
dynastic Egyptians. This country, called El Gash by its inhabitants, 
has been described by Burckhardt." In liis day the peojjlo there were 
in the transition stage between the pastoral nomad and the agriculi 
turist. It was a fertile and ]x>pulous region. About the end of June 
largo tori'onts coming from thei south and south-west j)Our over the 
country, and in the space of a fortnight or so cover the whole surface 
with a sheet of water, varying in depth from two tO' three feet. These 
torrents were said to lose themselves in the eastern plain after inundat- 
ing the country, but the waters remained upwards of a month in Taka, 
and on subsiding left a thick slime or mud upon the surface. Imme- 
diately after the inundation was imbibed the Bedawln sowed their seed 
upon the mud, without any previous preparation whatever. The 
inundation was usually accompanied by heavy rains, which set in a 
short time before the immdation, and became most copious during its 
height. The rains lasted some weeks longer than the inundation ; they 
were not incessant, but fell in heavy showers at short inteiTals. In 



the winter and spring the people of Taka obtained their water from 
deep' wells, extremely copious, dispersed all over the country, but at a 
considerable distance from each other. The people appeared to be 
ignorant of tillage; they had no regular fields, and the millet, their 
only grain, was sown among thorny trees. After the harvest was 
gathered the peasants returned to their pastoral occupations. When 
Burckhardt visited this region in the hottest part of the year, just 
before the period of the rains, the ground was quite parched up, and 
he saw but few cattle; the herds were sent to the Eastern Desert, 
where they fed in the mountains and fertile valleys, and where springs 
of water were found. After the inundation they wei'e bi^ought back to 
the plain. The quantity of cattle, Burckhardt believed, would have 
been greater than it was had it not been for the wild beasts which 
inhabited the district and destroyed great numbers of them. The 
most common of these wild animals were the lion and the leopard. 
The flocks of the encampment were driven in the evening into the 
area within the circle of tents, which were themselves surrounded by 
a thorny enclosure. Great numbers of asses were kept by all these 
Bedawin. They alsO' possessed many camels. Tlie trees are described 
as being full of pigeons. The Hadendoa v/ere the only inhabitants of 
Taka seen by Burckhardt. Each tribe had a couple of large villages 
built in the desert on the border of the cultivable soil, where some 
inhabitants were always to be fo'und, and to which the population, 
'excepting those who tended the cattle in the interior of the desert, 
repaired during the rainy season. After the waters had subsided they 
spread over the whole district, pitching their camps in those places 
where they hoped for the best pasturage, and moved about from month 
to month, until the sun parclied up the herbage. The settlers in the 
villages meantime sowed the ground adjoining the neighbouring desert. 
The camps consisted of huts formed of mats; there were also a few 
huts with walls, resembling those in the countries of the Nile, but 
smaller. Even the settlers, however, preferred living in the open under 
sheds to inhabiting these close dwellings. 

It has often been stated that civilisation in Egypt spread from 
the south, and considerable stress has been laid upon the fact that so 
many pre-dynasiic and early dynastic remains have been found in Upper 
Egypt in the region between Edfu and Thinis, especially at Hierakon- 
polis and Naqada, and north of Naqada, in the neighl>ourhood of 
Abydos. Opposite Edfu is a desert route leading to the Red Sea; at 
Kilft, opposite Naqada, is the beginning of the road leading to Koscr, 
the port on the Eta Sea. It has been thought that the people who 
brought culture to Egypt reached the Nile Valley by one or by both 
these routes from a ' God's Land ' situated somewhere down the Eed 
Sea. coast. But throughout the whole liistory of Egypt cultui-o has 
always come from the north, and spread southwards. 

From a study of the monuments of the First Dynasty that had 
been found at Abydos and elsewhere in Upper Egypt I ventured, nearly 
twenty ye^rs ago,^" to suggest the existence in pre-dynastic times of 
a Delta civilisation which, in culture, was far advanced beyond that 
of Ujjper Egypt, and I pointed out that it \\as probably to a Delta 


civilisation that the Dynastic Egyptians owed their system of writing. 
I was led to this conclusion by the following facts. Although many 
pre-dynastic cemeteries had been thoroughly explored in Upper Egypt 
no grave had yielded a single fragment of hieroglyphic writing. The 
only inference that can be drawn from tliis is that hieroglyphic writing 
was unknown, or at all events unpractised, by the inhabitants of 
Upper Egypt before dynastic times. On tlie other hand, the dis- 
coveries at Naqada, Hierakonpolis, and Abydos had shown us that all 
the essential features of the Egyptian system of writing were fully 
developed at the beginning of the First Dynasty. Hieroglyphic signs 
were already in full use^ as simple phonograms, and their employment 
as phonetic complements was well established. Determinative signs 
are found beginning to appear in these early writings, but, as Erman 
and Griffith have noticed, even as late as the Fifth Dynasty their use 
was veiy restricted in the monumental inscriptions, although they were 
common in the cursive and freely writteu texts of the Pyramids. At 
the very beginning of the First Dynasty the lumierical system was com- 
plete up to millions, and the Egyptians had already worked out a solar 
year of 365 days. This was indeed a rcmaikabk' achievement. 

These facts are of great significance, for it is clear that the hiero- 
glypliic system of writing, as we find it at the beginning of the First 
Dynasty, must have been the growth of many antecedent ages, and 
yet no- trace of the early stage-s of its evolution have been found on 
Upper Egyptian soil. There is no clear evidence, however, that the 
system was borrowed from any country outside Egypt ; the fauna and 
flora of its characters give it every appearance of being indigenous. It 
is apparent, therefore, that we must seek the cradle of the Egyptian 
system of hieroglyphic writing elsewhere than in Upper Egypt, and 
as the fauna and flora of its characters are distinctly Egyptian the 
presumption is that it must be located to the Delta. An important indi- 
cation as to the original liome of Egyptian writing is given by the 
signs which, in histoi'ic times, were used to designate the points of the 
compass. The sign for * east ' was a drop-shaped ingot of metal upon 
a sacred perch, and this was the cult-object of a clan living in pre- 
dynastic times in the Eastern Delta. The sign for ' west ' was an 
ostrich feather placed in a semicircular stand, and this was the cult- 
object of the people of the Western Delta. The sign for ' south ' was 
a scirp us -reed; this was the cult-object of a elan which dwelt on the 
east bank of the Nile a little above the modern village of Sharona in 
Middle Egypt. The country south of the apex of the Delta was known 
as Ta Shema, ' Eeed Land.' It must, therefore, have been at some 
point north of the apex of the Delta that the scirpus-reed was first used 
to designate the south. It must also have been somewhere in the 
Central Delta that the cult-objects of the peoples of the Eastern and 
Western Delta were first used to designate ' east ' and ' west.' 

For the Delta being tlie early home of writing a.notlier fact lias to 
be taken into consideration. Thoth, the Ibis-god, was to Die Egyp- 
tians lliL' god of Nsiiting, and it was to liim that they attriliiited its 
invention. The principal seat of liis worsliip in historic times was 
Ilermopolis, in Middle Egypt. But Thoth 's original habitat was 


situated in the noitii-eiist corner of the Delta, where, in pre-dynastic 
tim'es, had resided an Ibis clan. The tradition that named Thoth as 
the god and inventor of writing would, therefore, point Delta-wards. 
This tradition is significant also in another way. Although we cannot 
doubt that the Egyptian system of writing was evolved in the Delta, 
the germs of writing may have come into Egypt from Western Asia 
via this north-east corner of the country. In this connection it may 
be pointed out that the hieroglyphic signs for ' right ' and ' left ' were 
the same as those for ' west ' and ' east ' ; the Eg\"ptia>ns who evolved 
the hieroglyphic system of winting orientated themselves facing south. 

It is remarkable that so little is known about the early history of the 
Delta. But few excavations have been carried out there, and nothing of 
pre-dynastic or early dynastic times lias, so far, been brought to light 
from the country north of Cairo. We do know, however, that before 
the arrival of the Falcon-kings from Hierakonpolis in the south, Middle 
and Ijower Egypt had been, probably for many centuries, united under 
one sceptre, and that before these two paxis of the country were united 
there had been a Delta Kingdom which had had its capital at Sais. The 
names of some of these early kings are presei-ved on the Palermo frag- 
ment of the famous Annals 'J'ablet, and the list there given would alone 
be enough to prove how ancient the Delta civilisation must have been. 
There was certainly nothing comparable with it in Upper Egypt in those 
far-off days. 

What were the physical conditions prevailing in the Delta and in 
the regions to the east and west of it immediately preceding Menes' 
arrival in Lower Egypt ? For the eastern side the evidence is exceed- 
ingly scanty, but there is one fact which is significant. The chief god 
of the eastern nomes of the Delta in the Pyramid Age was Anzety, a 
pastoral deity who was the prototype of Osiris. He is represented as a 
man holding in one hand the shepherd's crook, and in the other the 
goatherd's ladanisterion. There can be little doubt, therefore, that in 
the Eastern Delta there lived a pastoi-al people who possessed Hocks of 
sheep and goats, and this is evidence of a certain amount of grass-land. 
In the Central Delta at the same period thei'e lived a series of clans, 
among which a Bull Clan was predominant. In historic times in 
Egypt the ox is often figured roaming in papyrus and reed marshes, and 
it may be that the Central Delta marshes suppoi'ted herds of domesti- 
cated cattle. Much more is known about the western side of the Delta 
at the time of Menes. It formed, I helieve, part of what was called 
Tehenu-land; at all events this lutnie was given to the region innne- 
diately to the west of the Canopic branch of the Nile. There can be no 
doubt that this part of the country was a very fertile and prosperous 
region in the period immediately preceding the First Dynasty. Its 
name signifies 'Olive-land,' and we actually see these trees figured, 
with the name of tire country beside them, on a pre-dynastic Slate 
Palette; on this Palette, above the trees, are shown oxen, asses, and 
sheep of the type later known as «<? /--sheep. It was Menes,-' the Falcon- 
king of Upper Egypt, who coiicpu'red the people of Tehenu-land. This 
conquest is recorded on a small ivory cylinder that was found at 
nic)ak(jii[)olis. Another rccoid of the Southerner's triumph over these 


people is preserved on his famous Slate Palette; here the Upper Egyp- 
tian king is depicted smiting their Chieftain, while on the verso of the 
same Palette is the scene of a festival at the Great Port, which was 
perhaps situated near the Canopic branch of the Nile. The mace-head 
of Menes, which is now in the Ashmolean Museum at Oxford, has a 
scene carved upon it which shows the king assuming the Bed Ci'own of 
Sais, and the inscription accompanying it records that he had captured 
120,000 prisoners, 400,000 oxen, and 1,422,000 goats. This immense 
number of oxen and goats is clear evidence that the north-western 
Delta and the region to the west of it (Tehenu-land) must have included 
within its boundaries very extensive grass-lands. Several centuries after 
Menes, Sahm-e, a king of the Fifth Dynasty, captured in Tehenu- 
land 123,440 oxen, 233,400. asses, 232,413 goats, and 243,688 
sheep. Senusret I. also captured in the same region ' cattle of all kinds 
without number. ' This again shows how fertile the country must have 
been at the beginning of the Middle Kingdom. The history of this part 
of the Delta is most obscure. During the period that elapsed from the 
end of the Third Dynasty to the beginning of the Twenty-third, when 
Tefnakht appears upon the scene, we have hardly any information about 
it. What was happening at Sais and other great cities in the north- 
west of Egypt during the period from 2900 to 720 B.C. ? There is an 
extraordinary lacuna in our knowledge of this part of the country. The 
people- living there were certainly of Libyan descent, for even as late 
as the time of Herodotus the inhabitants deemed themselves Libyans, 
not Egyptians ; and the Greek historian says that they did not even 
speak the Egyptian language. The pre-dynastic people who inhabited 
the greater part of the Lower Nile Valley were apparently of the same 
stock as these Libyans. There- is a certain class of decorated pottery 
which has been found in pre-dynastic graves from Gizeh in the north 
toKostamneh in the south. On this decorated pottery are figured boats 
with cult-objects raised on poles. Altogether some 170 vases of this 
type are known, and on them are 300 figures of boats with cult-signs. 
Of these, 124 give the ' Harpoon ' ensign; 78 the 'Mountain ' ensign; 
and 20 the ' Crossed Arrows ' ensign. These cult-objects all survived 
into historic times; the 'Harpoon' was the cult-object of the people 
of the Mareotis Lake region ; the ' Mountain ' and ' Crossed Arrows ' 
were the cult-objects of the people dwelling on the right bank of the 
Canopic branch of the Nile. Thus it will be seen that out of 300 boats 
figured on vases found in graves in the Lower Nile Valley south of 
Cairo, 222 belong to cults which can be located in the north-western 
corner of the Delta. Twenty-two boats bear the ' Tree ' ensign, 
which was the early cult-object of the people of Herakleopolis, a city 
just south of the Fa yum. Ten bear the 'Thunderbolt' ensign of 
Ekhmim. The ' Falcon ' on a cui'ved perch appears on three boats, 
and this ensign undoubtedly represents the Falcon deity of Hierakon- 
polis. At the beginning of the historic period the cult-objects of the 
people of the north-western Delta included (1) the ' Harpoon,' (2) the 
figure-of-eight ' Shield with Crossed Arrows,' (3) the ' Mountain,' and 
probably (4) the Double Axe,"- and (5) a Dove or Swallow." With tlie 
exception of the ' Harpoon ' all these cult-objects ai"e also found in 


Crete, a fact which is significant in view of Sir Arthur Evans' remark, 
quoted at the beginning of my address, to the effect that he considers the 
possibiUty of some actual immigration into the Island of the older 
Egyptian element due to the first Phai'aohs. The ' Harpoon, ' it should 
be noted, is the prototype of the bident, and later, of the trident of the 
Libyan god Poseidon. 

Upon the mace-head of Menes the king is represented assuming the 
Crown of Neith of Sais. This is the eaiiiest representation of the 
famous Sed Festival which is generally held to be a survival, in a 
much weakened form, of the ceremonial killing of the king, its essential 
feature being regarded as the identification of the king with the god 
Osiris. The festival was, I believe, of Libyan origin, and, at all 
events in its origin, it was not connected in any way with Osiris. On 
this mace-head the Upper Egyptian conqueror is shown seated under a 
canopy upon a dais raised high above the gi'ound. He is clad in a long, 
close-fitting garment; upon his head is the Eed Crown of Sais, and in 
one of his hands is the so-called flail. Behind him is a group of 
officials, and upon either side of the dais ai'e two fan-bearers. In front 
of the king is a princess seated in a palanquin, and behind her are 
three men figured in the act of running. This is the earliest of a long 
series of representations of the festival, and we cannot doubt that the 
l)articular ceremony here depicted was the central one around which, 
in later times, the other ceremonies that we know were connected with 
it were grouped. There is no indication here of any ceremonial killing 
of the king, and the Red Crown which Menes wears is not charac- 
teristic of Osiris but of the goddess Neith of Sais. In the Mortuary 
Temple of Neuserre at Abusir, in the Temple of Amenhotep III. at 
Soleb in Nubia, and in the Temple of Osorkon III. at Bubastis, the 
Sed Festival is represented in far greater detail, but still there is no 
indication of the ceremonial killing of the king, or of his identification 
with Osiris. These later scenes show that the festival was a gi-eat 
national one that was attended by all the great dignitaries of State, and 
by the priests of the gods from all the principal cities of Egj'pt. In 
these later i-epresentations the king's daughters and the running men 
play an important part. Inscriptions accompanying the scenes at 
Soleb" and Bubastis state that the king at this festival assumed the 
protection of Egypt and of the sacred women of the Temple of Anion. 
The Queen at these periods of Egyptian histoiy was the High Priestess 
of Amon and the Head of the Harlm of the god. An important refer- 
ence to the festival is found in the inscription of Piankhy. This 
Ethiopian king, in his triumphant march from Thebes towards the 
Delta, had captured Hermopolis, the capital of a petty king named 
Nainlot (a Libyan Dynast), and when Piankhy made his entry into the 
city he was acclaimed by the people, who prayed that he would cele- 
brate there a Sed festival. ' His Majesty proceeded to the palace of 
Namlot, and entered every chamber. He caused that there be brought 
to him the king's wives and the king's daughters. They saluted His 
Majesty in the fashion of women,' but the Ethiopian says that he would 
not turn his face to them, and he did not celebrate a Sed festival. The 
most important point in connection with the festival is that at it the 


king assumed the protection of the land of Egypt. It was a kind of 
coi'onation festival. On Menes' mace-head the king is shown assuming 
the Eed Crown, \\ hile before him is the Piincess of the country that he 
had conquered, and below her is a statement of the number of piisoners 
and cattle captured by him in her country. 

Now what were the rules that regulated the succession to the king- 
ship in Ancient Egypt? It is often assumed that the kingship was 
hereditary in the male line, and that the son regularly succeeded his 
father on the throne. But we know that many Egyptian kings were 
not the sons of their predecessors. ^Ye also know that at some periods, 
at all events, the sovereign based his claim to the kingship upon the 
fact that he had ma)ried the Hereditaiy Princess. Harmhab, at the 
beginning of the Nineteenth Dynasty, tells us that he proceeded to the 
palace at Thebes, and there, in the Great House [pr-icr), married the 
Hereditary Princess. Then the gods, ' the lords of the House of Elame 
[pr-nsrt), were in exultation because of his coronation, and they prayed 
Amon that he would grant to Harmhab the Sed festivals of Ee. ' It 
was after his marriage to the princess that Harmhab's titulary was 
fixed. The refen-nce to the House of Flame is interesting because the 
kindling of fire was an important ceremony at the Sed Festival; it is 
figured at Soleb, and there a priestess called ' the Divine Mother of 
Suit ' plays an important role. This priestess may be compared willi 
Vesta, who always bore the official title of 'Mother,' never that of 
'Virgin.' It is unnecessaiy for me to speak of the King's Fire and 
the Vestal Virgins whose duty it was to keep the perpetual fire burning ; 
the material has been collected by Sir James Frazer. This ceremony 
of kindling fire suggests that the festival may have been a niarriuge 
festival, and the running men figured on the mace-head of Menes, and 
in later representations, also points to this inteipretation of it. There 
can be little doubt that it was a Libyan festival ; at all events it is first 
found when Menes assumed the Eed Crown of Neith of Sais. When 
Menes had conquered the north-western Delta, he married the 
Hereditaiy Piincess of the country. She was probably the eldest 
daughter, or perhaps the widow, of the Lower Egyptian king whose 
countiy he had seized. Marriage with the king's widow or eldest 
daughter carried the throne with it as a matter of right, and Menes' 
marriage, we can well believe, was a marriage of policy in order to 
clinch by a legal measure his claim to that crown which he had already 
won for himself in battle. Sir James Frazer has noted that sometimes 
apparently the right to the hand of the princess and to the throne 
has been determined by a race. The Ijibyan king Antseus placed his 
daughter Barce at the end of a race-course; her noble suitors, both 
Libyans and foreigners, ran to her as the goal, and the one who touched 
her first gained her in mariiage. The Alitemnian Libyans awarded 
the kingdom to' the fleetest runner. According to tradition, the earliest 
games at Olympia were lield by Endymion, wliO' set his sons to run 
a race for the kingdom. In all the ceremonies connected with the Sed 
Festival I can see no feature that suggests the Osirification of tlie king. 
When he wears the Eed Crown he assumes control of Lower Egypt; 
when ho wears the. White Crown he assumes control of Upper Egypt. 


Tlioro is nno furlliov point connect^l with Mio wofftorn nUh of tlio, Dolla 
that must be noted. Ghazeware (and glass) in Egyptian is called ielbeyil ; 
this was one of the chief articles of export of Tehenu-land. Just as we 
use the word ' china ' for a kind of porcelain which first came to us from 
China, so the Egyptians called glass thn.t after the country of the 
north-western Delta from which they derived it. Here in this western 
side of Lower Egypt is an almost wholly unexplored field for the 

I liave already referred to the pastoral deity Anzety, who, in the 
Pyramid Age, was Chief of the nomes of the Eastern Delta. Among all 
the nome-gods he is the only one that is figured in human form; he 
stands erect, holding in hig right hand the sheplierd's crook and in his 
left the goatherd's ladanisterion. On his head is a bi-cornute object 
that is connected with goats, and on his chin is a false beard curled 
at the tip. He was not an oxherd, but a shepherd and goatherd. In 
later times the figure of this deity, in hieroglyphic writing, is regularly 
used as the determinative sign of the word ity, ' ruling prince,' 
'sovereign,' a tenn tliat is applied only toi the living king. In tho 
Pyramid Texts, Anzety is entitled ' H-ead of the Eastern nomes,' and 
these included the ancient one of the Oxyrrhynchus-fish, where, later, 
the ram oi- goat was the cliief cult -animal. Neither the domosticatod 
sheep nor the goat can be reckoned as Egyptian in origin; they Ijoth 
came into Egypt from Western Asia. We have, therefore, in this 
pastornl deity Anzety evidence of immigration from the west. The 
only \sn\d sheep inhabiting the continent of Africa is the Bai-bary sheep, 
and this animal was not the ancestor of any domesticated breed. Both 
the sheep and the goat are essentially mountain animals, tliough sheep 
in the wild state do not as a rule frequent such rugged and precipitous 
ground as their near relatives the goats, but prefer more open country. 
Sheep browse in short grass ; goats feed upon the young shoots of slirubs 
and trees. The domesticated goat is generally recognised as descended 
from the wild goat {Gapra hirciis agaqrus) of Syi'ia, Asia Minor, Persia, 
and tlie IMeditcrranean Isles. Two breeds of domesticated sheep were 
known to the Egyptians. The sheep of the earliest liistorical period 
down to the Middle Kingdom was a long-legged variety {Ovis longipes), 
with horns projecting transversely and twisted. This breed was tlie 
only one known in the earlier periods of Egyptian history ; it was the 
predominant breed in the Middle Kingdom, but soon after the beginning 
of the Empire it appears to have become rare or extinct in Egypt, and 
was superseded by a variety with horns curving forwards in a sub- 
circular coil. Both varieties of domesticated sheep, according to 
Lydekker, were introduced into Egypt through Syria. 

Among the cult-objects of the cities over which tlie god Anzety pre- 
sided were t^vo which. I believe, can definitely be referred to trees 
that were not indigenous to the soil of Egypt but to Syria. One of 
tliese cult-objects is the so-called Ded-column. This was one of the 
holiest symbols of the Egyptian religion. It has four cross-bars at the 
top like superposed capitals. Sometimes a pair of human eyes are 
shown upon it, and the pillar is draped: sometimes a human foim is 
given to it by carving a grotesque face on it, robing tlie lower part, 


crowning the top with ram's horns, and adding two arms, the hands 
holding the crook and ladanisterion. Frazer has suggested that this 
object uiiglit very well be a conventional representation of a tree stripped 
of its leaves. That it was, in fact, a lopped tree is, I believe, certain. 
In the Pyramid Texts it is said of Osiris, ' Thou receivest thy two oars, 
the one of juniper (uan), the other of si-wood, and thou ferriest over 
the Great Green Sea. ' The determinative-sign of the word sd is a tree 
of precisely the same form as the Ded-column that is figured on early 
Egyptian monuments, i.e. it has a long, thin stem. This tree-name 
occurs only in inscriptions of the Pryamid Age, and it is mentioned 
as a wood that was used for making chairs, tables, boxes, and various 
other articles of furniture. In the passage quoted from the Pyramid 
Texts it is mentioned together with juniper, and the latter was employed 
in cabinet-making, etc., at all periods of Egyptian history. The>'e is 
no evidence that juniper ever grew in Egypt, but we have numerous 
records of the wood being imported fi-om the Lebanon region. The 
sd-tree, as we see from the detei'minative-sign of the name, had horizon- 
tally spreading branches, and was evidently some species of conifer. 
No conifers, however, are known from Egypt; the scZ-wood must, 
tlierefore, have been of foreign importation. As it is mentioned with 
juniper, whicOi we know came to Egypt from Syria, it is possible that 
it came from the same region. Among the trees of tlie Lebanon there 
are four that have horizontally spreading branches. These are the cedar 
(Cedrus libani), the Cilician fir, the Pinus laricio, and the horizontal- 
branched cypress (Cupressus sempervirens var. liorizontales). Much 
misconception at present exists with regard to the Lebanon Cedar, 
because the name ' cedar ' is applied to a large number of woods which 
are quite distinct from it, and the wood which we generally call cedar 
(e.g. the cedar of our ' cedar' pencils) is not true cedar at all, but 
Virginian junij^er. The wood of Cedrus libani is light and spongy, of a 
reddish-white colour, very apt to shrink and wai-p badly, by no means 
durable, and in no sense is it valuable. Sir Joseph Hooker, who visited 
the Lebanon in 1860, notes that the lower slopes of that mountain 
region bordering the sea were covered with magnificent forests of pine, 
juniper, and cypress, ' so that there was little inducement for the timber 
hewers of ancient times to ascend 6,000 feet through twenty miles of 
a rocky mountain valley to obtain cedar wood which had no particular 
quality to recommend it. The cypress, pine, and tall, fragi'ant juniper 
of the Lebanon, with its fine red heart-wood, would have been far more 
prized on eveiy account than the cedar.' The sd-tree was, I believe, 
the horizontal-branched cypress which is common in the wild state. 
In the Middle Ages this tree was believed to be the male tree, while the 
tapering conical-shaped cypress was considered to be the female. This 
is an interesting fact, because there is some evidence to show that the 
tapering variety was the symbol of Hathor-Isis, while the horizontal- 
branched one was the symbol of Osiris. 

In the Pyramid Age there are several records of the priests of the 
Ded-column. They were called ' priests of the venerable ded-column.' 
The seat of the cult was Dedu, or, as it was sometimes called, Pr-Wsr, 
' the House of Osiris,' the Greek Busiris in the Central Delta. At this 

ir.— ANTIlKOrOLOflY. 189 

city was ccWuiilcd ;\miiuilly a great, festival in lioiiour ot Osiris. It 
lastod many days, and tlie culmination of a loiij^- seiies of ceicnionivs 
was the raising of the dtd-column into an erect position. Osiris is 
intimately connected with this column; the Egyptians called it his back- 
bone. In the myth of Osiris, as recsorded by Plutarch, a. pillar played 
an important part. Plutarch says that the coffer containing the hodj 
of Osiris was washed up by the sea. at Byblos, the port of the T.ebanoii, 
and that a tree gi'ew up and concealed the coffin within itself. This 
sacred tree was cut down by Isis and presented to the people of Byblos 
wrapped in a linen cloth, and anointed with myrrh, like a corpse. It 
therefoi'e represented the dead god, and this dead god was Osiris. 

Not far from Dedu, the city of Osiris in the Delta, was Hebyt, tlie 
modern Behbeyt el Hagar. Its sacred name was Neter. Tho Eomans 
called it Iseum, or Isidis oppidum. It was the ancient seat of Isis 
worship in Egypt, and the ruins of its temple to that goddess still cover 
several acres of ^gi'ound in tlie neighbourhood. On the analogy of other 
sacred names of cities the primitive cult-object here was the ntr-pole. 
This was not an axe, as has so often been supposed, but a pole that was 
wrapped around with a band of coloured cloth, tied with cord half-way 
up tlie stem, witli the u])per part of tho band projecting as a flap at top. 
Dr. Griffith conjectured that it was a fetish, e.g. a bone carefully wound 
round with cloth, but he noted that ' this idea is not as yet supported 
by any ascertained facts.' As a hieroglyh this wrapped-up pole 
expresses ntr, ' god,' ' divine,' in which sense it is very common from 
the earliest times; gradually it became detenninative of divinity and of 
the divine names and ideographic of divinity. Another common ideo- 
graph of ' god ' in the Old Kingdom was the Falcon (Horus) upon a 
perch, and this sign was also employed as a determinative of divinity 
and of the names of individual gods; it even sometimes occurs as a 
determinative sign of the ntr -pole, e.g. Pyr. Texts, 482. This use of 
the Falcon indicates that in the early dynasties the influence of the 
Upper Egyptian Falcon-god (Horus) was paramount. But there is 
reason for believing that the ?(/r-pole cult had at an earlier period been 
the predominant one among the writing people of the Delta; this, I 
think, is shov\'n by the invariable use of the liir-pole sign in the words 
for priest {lim-ntr, ' god's servant '), and temple (lit-ntr, ' god's house '). 
Now, on a label of King Aha of the First Dynasty there is a representa- 
tion of the temple of Neith of Sais. Here two poles with triangular 
flags at top are shown on either side of the entrance. Later figui-es of 
the same temple show these poles with the rectangular flags precisely 
as we find in the ?2ir-sign. A figure of the temple of Hershef on the 
Palermo Stone shows two poles with triangular flags, while a Fourth 
Dynasty drawing of the same temple shows the same poles with 
rectangular flags. We see, therefore, that the triangular-flagged pole 
equals the rectangular-flagge<l one, and that the ntr is really a pole or 
mast with flag. Poles of this kind were probably planted before the 
entrances to most early Egyptian temples, and the gi'eat flag-masts set 
up before the pylons of the great temples of the Eighteenth and later 
dynasties are obviously survivals of the earlier poles. The height and 
straightness of these poles prove that they cannot have been produced 


by any native Egyptian tree ; in the Empire flag-staves were regularly 
imported from Syria ; it is probable therefore that in the earlier times 
they were introduced from the same source. A well-known name for 
Syria and the east coast of the Eed Sea, as well as of Punt, was Ta-ntr, 
' the land of the i!7r-pole.' This was the region in which the primitive 
Semitic goddess Astarte was worsliipped . In Canaan there was a 
goddess Ashera whose idol or symbol was the ashera pole. The names 
of Baal and Ashera are sometimes coupled precisely as those of Baal 
and Astarte, and many scholars have inferred that Ashera was only 
another name of the great Senu'tic goddess Astarte. The ashera-pole 
was an object of worship, for the prophets put it on the same line 
with the sacred symbols, such as Baal pillars : the ashera was, therefore, 
a sacred symbol, the seat of a deity, the mark of a divine presence. In 
late times these asherim did not exclusively belong to any one deity; 
they were erected to Baal as well as to Yahw. They were sign-posts set 
up to mark sacred places, and they were, moreover, draped. They 
con-espond exactly to the vtr-poies of Egyptian historic times. I have 
noted that these 7i/r-poles were tall and straight. What tree produced 
them? In Egyptian inscriptions there is often mentioned a tree named 
tr.t. It was occasionally planted in ancient Egyptian gardens, and 
specimens of it were to be seen in the Temple garden at Heliopolis. 
The seeds and sawdust were employed in medicine, and its resin was 
one of the ingi'edients of the Kyphi-incense. Chaplets were made of 
its twigs and leaves. The tree was sacred tO' Hathor ; branches of it 
wex'e offered by the Egyptian kings to that goddess. In a Saite text it 
is mentioned with three other trees — pine, yew, and juniper; these are 
all found in Nortliern Syria , where they grow together with the cypress ; 
the tr.t tree may therefore he the cypress. Evidence has been brought 
forward to show that the sJ-tree is the horizontal-branched cypress, 
which was believed to be a male tree, while the tapering, flame-shaped 
cypress was believed to be the female tree. The ded-column was the 
symbol of Osiris, and at Busiris was celebrated a festival of raising this 
column. The tr.t tree was sacred to Hathor, who is often identified 
with Isis, and there was a festival of raising the tr.t tree that was 
celebrated on the nineteenth day of the first month of the winter season. 
It is not known where this festival was celebrated, but it may well have 
been at Neter, the seat of the Isis cult near Dedu-Busiris. The two 
tree-cults point to Northern Syria as the country of their origin. 

In the architecture of ancient Egypt two distinct styles can be 
recognised. One is founded on wattle-and-daub, the other on wood 
consti'uction. Wattle-and-daub is the natural building material of the 
Nile Valley and Delta, and the architectural forms derived from it are 
certainly indigenous. Those styles derived from wood construction, 
on the other hand, could not have originated in Egypt, but must have 
arisen in a countiy where the necessary timber was ready at hand. 
Egypt produces no coniferous trees and no timber that is at all suitable 
for building purposes, or indeed for carpenter's work of any descrip- 
tion. The wood of the sycomore-fig is veiy coarse-grained, and no 
straight planks can be cut from it. The sunt-acacia is so hard that 
it requires to be sawn while it is green ; it is very irregular in texture, 

Tf.— AXTHllOPOLOOY. 1 01 

and on account of the numerous branches of the, trunk dt is impossible 
to cut it into boards more tlian a couple of feet in length, llie palaces 
of the early kings of tlie Delta were built of coniferous wood hung with 
tapestry-woven mats. The tomb of Menes' queen, Neith-hotep, at 
Naqadai, was built (rf brick in imitaition of one of these timber-con- 
structed palaces, and smaller tombs of the same kind are known from 
the Second and Third Dynasties, but not later. As early as the reign 
of King Den (First Dyn.) the palaces of this type were beginning to 
be built of the native wattle-and-daub in combination with wood, and 
by the end of the Pyramid Age the style disappears entirely, though the 
memory of it was presei'ved in the false-doors of the tombs and stela'. 
Brick buildings similar to those of the ' palace ' style of Egypt are 
also known from early Babyloinia, and they were at one time regarded as 
peculiarly characteristic of Sumerian architecture. These, obviously, 
must have been copied, like; the Egyptian, fi-OTii earlier timber fonns. 
In Babylonia, as in Egypt, timber was scarce, and there are records 
that it was sometimes obtained from the coast of Syria. This was the 
region from which the Egyptians throughout historic times obtained 
their main supplies of wood, so it is not improbable that they, as well 
as the Sumerians, derived this particular style of architectui'e from 
Northern Syria. I may observe in passing that an this ' palace ' style 
we have the transition fonn between the nomad's tent and the pennanent 
building of a settled people. The lack of native timber in Egypt is 
significant in another direction. Boats of considerable size are figiu'ed 
on many pre-dynastic monuments. They are long and naiTOW, and in 
the middle there is usually figured a reed or wicker-work cabin. In 
my view these l)onts were built, like many of those of later periods in 
Egypt, of bundles of papyrus reeds bound together with cord ; they were, 
in fact, great canoes, and, of course, were only for river traffic. They 
were not sailing boats, but were propelled by means of oars. No mast 
is ever figured with them, but they generally have a short pole amid- 
ships which is surmounted by a cult-object. On one pre-dynastic vase 
there is a figure of a saiHng ship, but this is totally different in build 
from the canoes, and it has a very high bow and stern with its mast 
set far forward in the hull. Similar vessels are figured on the ivory 
knife-handle of pre-dynastic date from Gebel el Araq, but these vessels 
appear to be in port and the sails are evidently lowered. I have already 
refeiTed to the Great Port mentioned on the Palette of Menes. A port 
implies shipping and trade relations with people dwelling along the coast 
or across the sea. It may be that the people of the north-western 
Delta built wooden ships, but if they did they must have procured their 
timber from some foreign source. Coniferous wood was already being 
imported into the Nile Valley at the beginning of the First Dynasty 
from the Lebanon region, and it must be remembered that the Egyptian 
name for n sea-going ship was kbnyt, from Kehen, ' Byblos,' the port 
of the Lebanon, where these ships must have been built and from whence 
they sailed. The sacred barks of the principal gods of Egypt in historic 
times were invariably built of coniferous wood from the Lebanon. 
Transport ships on the Nile were sometimes built of the native sunt- 
vvood, and Herodotus describes them as mad© of planks about two cubits 

192:5 p 


long which were put together ' brick-fashion.' No masts or sail- 
yards, however, could possibly be cut from any native Egyptian tree. 
In the Sudan at the present day masts are sometimes made by splicing 
together a number of small pieces of sunt and binding them with ox-liide, 
but such masts are extremely liable to start in any gale, and they would 
be useless for sea-going ships. It may be doubted whether the art of 
building sea -going ships originated in Egypt. It may be doubted also 
whether the custom of burying the dead in wooden coffins originated in 
Egypt. In countries where a tree is a rarity a plank for a coffin is 
generally unknown. In the Admonitions of an Egyptian Sage written 
some time before 2000 B.C., at a period when there was internal strife in 
Egypt, the Sage laments that ' Men do not sail northwards to 
[Byb] -los* to-day. What shall we do for coniferous treesf for our 
mummies, with the produce of which priests are buried, and with the 
oil of which [chiefs] are embalmed as far as Keftiu? They come no 
more. ' This ancient Sage raises another anthropological question when 
he refers to ihe oil used for embalming. The only oils produced by 
native trees or shrubs in Egypt were olive oil, ben oil from the moringa, 
and castor oil from the castor-oil plant. The resins and oils used for 
embalming were principally those derived from pines and other coni- 
ferous trees. Egypt produced no kinds of incense trees or shrubs. The 
common incenses were pine resin, ladanum, and myrrh, and all these 
were imported. It is difficult to believe that the ceremonial use of 
incense arose in Egypt. 

These are a few of the questions raised by a study of the material 
relating to the origins of the ancient civilisation of Egypt. There are 
numbers of others that are waiting to be dealt with. Egypt is extra- 
ordinarily rich in material for the anthropologist. It is a storehouse 
full of the remains of man's industry from pre-agricultural times right 
down to the present day. Almost every foot of ground hides some 
relic of bygone man. The climatic conditions prevailing there are excep- 
tional, and it is largely owing to the absence of rain that so full a record 
of man and his works has been preserved. For more than a centuiy 
excavators have been busy in many parts of the country, but there is 
yet no sign that the soil is becoming exhausted ; it is, in fact, almost 
daily yielding up its buried treasures. The past two or three decades have 
been prolific in surprises. Mines of hidden wealth have been unearthed 
where but a few years ago we only saw the sands and rocky defiles of the 
desert. Since we met at Hull last year, the most sensational archaeo- 
logical discovery of modern times has been made in a place that had 
been abandoned by many excavators as exhausted. This discovery, due 
to the untiring persistence of an Englishman, promises to yield results 
of extraordinary interest, but it will take years befoi'e they can be 
adequately published. Other discoveries have been made in Egypt 
during recent years which have opened out a vista of human history 
that we little dreamt of a quarter of a century ago. Three decades 

* This place-name ends -ny : ihe restoration [Kp-'\ny is due to Sethe and 
' suits the traces, the space and context quite admirably.' — A. H. Gardiner, 
The Admonitions of an Egyptian Sage, Leipzig, 1909, p. 33. 

t The word is as, a generic one for pines, fir, &c. 


ago not a single monument was known that could he ascribed with 
certainty to the period before the Third Egyptian Dynasty. To-day 
we possess a continuous series of written documents which carry 
us back to Menes, the Founder of the Monarchy, some 3,400 years 
or more before our era. These written documents, moreover, show 
clearly that Menes himself must have come at the end of a very 
long period of development. Egypt had already had a long history 
when the Upper and Lower Countries were first united under a singfe 
sceptre. From Upper Egypt we possess a continuous series of un- 
inscribed monuments which take us back far into prehistoric times. An 
immense Adsta has been opened out befoi'e our eyes by the discoveries 
of the last thirty years, and now, in Egypt better than in any other 
country in the world, we can see man passing from the primitive hunter 
to the pastoral nomad, from the pastoral nomad to the agriculturist, 
and then on to the civilised life which begins with the art of writing. 
We can see in the Delta and in the Lower' Nile Valley tnbes becoming 
permanently settled in fixed abodes around primitive cult-centres, and 
then uniting with others into one community. We can trace the fusion 
of several communities into single States, and then, later, the uniting 
of States under a supreme sovereign. What other country in the world 
preserves such a record of its early history ? 

I have but little time left to speak of the modern Egyptians, but to 
the anthropologist few people are more interesting. In almost every 
circumstance of daily life we see the Old in the New. Most of the 
ceremonies froni birth to burial are not Muslim, or Christian, or Roman, 
or Greek; they are Ancient Egyptian. In the transition of a people 
from one religion to another the important institutions of the older doc- 
trine are generally completely abolished; many ceremonies and mucii 
unessential detail, however, survive, and in the Delta and Lower Nilt> 
Valley survivals are extraordinarily numerous. It was Lady Duff 
Gordon who said that Egypt is a palimpsest in which the Bible is written 
over Herodotus, and the Koran over that ; the ancient writino- is still 
legible through all. Tliere is a passage in one of her letters whicli 
describes her visit to some Nubian women. Their dress and ornaments 
were the same as those represented in the ancient tomb-paintings. Their 
hair was arranged in little plaits, finished off with lumps of yellow clay 
burnished hke golden tags. In their house. Lady Duff Gordon sat on 
a couch of ancient Egyptian design, with a semicircular head-rest. 
They brought her dates in a basket such as you may see in the British 
Museum. So closely did they and their surroundings resemble the 
scenes of the ancient tombs that she says she felt inclined to ask them 
how many thousand years old they were ! The modern worship of the 
people is full of the ancient; many of the sacred animals and trees 
have taken service with Muslim Saints. Up to a few years aoo cats 
were still fed by the ' Sen^ant of Cats' in the Kadi's court in Cairo. 
Cobras are still held in great reverence in the City of the Khalifs. Some 
time ago the Director of the Zoological Gardens in Cairo told me that 
it was most difficult to procure cobras for the Gardens. It was not 
because they were scarce, but because the demand for them was so great 
that the price asked was far more than the Government would pay. 


Many cobras, I was told, were kept in the upper rooms of houses in the 
native quarters of the city. The funeral customs of the people through- 
out the country are much the same as those which prevailed in ancient 
times. It is not only among the merchant and agricultural classes that 
we find the Old in the New. Mrs. Poole, the sister of the Arabic 
scholar Edward Ijane, writing from Cairo in 1846, describes the scenes 
in one of Mohammed All's palaces on the death of a princess of the 
Royal Family. Immediately the royal lady breathed her last, her 
relations and slaves broke iip all the beautiful china and glass which 
had been her property. ' The destruction after a death,' Mrs. Poole 
remarks, ' is generally proportioned to the possessions of the deceased ; 
therefore, in this case, it was very extensive.' Many, perhaps most, 
of the festivals of the country are of ancient origin. In the Delta towns 
and villages there are several which are similar to those that were held 
there in ancient days. It is the same in Upper Egypt. Thebes still 
possesses its sacred boat, and on the festival commemorating the birth- 
day of Luxor's patron saint, Abu'l Haggag, this lineal descendant of the 
sacred bark of Amon decorated with flags and gaily coloured bits of 
cloth, is drawn around the town in procession, amid the acclamations 
of the people. Modern Egypt has hardly been touched by the anthro- 
pologist. The Government official usually holds himself far too aloof to 
ever really get into^ intimate contact with the native. Edward Lane did 
much to record the manners and customs of the Cairene Egyptian, but 
he never lived among the fellahin, and his book contains little about the 
modern dweller on the banks of the Nile outside Cairo. A rich harvest 
awaits any student who, kno>wing the language, will settle and live 
throughout the year among the peasants in any village or town in the 
Lower Nile Valley or Delta. It is only in this way that a real know- 
ledge of the people can be obtained. Far less is known about them 
than about many a tribe in Central Africa. 

Thucydides, in the preface to his ' History,' proposed tO' record past 
facts as a basis of rational provision in regard to the future, but he was 
not the first to whom this great thought had occurred. A thousand 
years before the Greek historian was born an old Vizier ol Egypt said 
of himself that he was ' skilled in the ways of the Past,' and that ' the 
things of Yesterday ' caused him ' to know To-morrow. ' Anthropology, 
the Science of Man and Civilisation, aims at discovering the general laws 
which have governed human history in the past and may be expected 
to regulate it in the future. The Egyptian Vizier had, at most, a couple 
of thousand years of recorded history before him. Since his time the 
area of histoi-y has been ever widening, and we ourselves can look back 
over nearly six thousand years of human endeavour. We know con- 
siderably more of the past than did our forefathers, and though those 
who hold the reins of government do not usually learn by experience, 
the anthropologist ought to be able to predict a little better than the 
politician about the future. For thousands of years Egypt has been 
under foreign rule. It has been under the yoke of Ethiopian and 
Persian kings, under the Greek and Eoman, Arab and Ottoman con- 
querors. Its people suffered three thousand years of oppression. For 
the last forty years it has had English justice. Egypt has this year 

U.— ANTHliOPOLUGY. li>5 

been handed back to the Egyptians. It is an Oriental country. What 
will be the immediate future of its people ? It is not difficult to predict. 
Seventy years ago, when Egypt was under the sway of Said Pasha, 
there was cui-rent among the feliahin of Thebes a little parable, and 
with this I will conclude. I quote it as it was taken down by Ehind 
in the fifties of last century, but the stoiy was still remembered when 
I lived among the natives of Upper Egypt twenty-eight years ago. It 
runs thus : — 

' It happened once that a Sultan captured a lion, which it pleased 
him to keep for his t'oyal pleasure. An officer was appointed especially 
to have in charge the well-being of the beast, for whose sustenance the 
command of His Highness allotted the daily allowance of six pounds 
of meat. It instantly occurred to the keeper that no one would be a 
bit the wiser were he to feed his dumb ward with four pounds, and 
dispose of the remaining two for his own benefit. This he did, until 
the lion gradually lost his sleekness and vigour, so as to attract the 
attention of his Eoyal Master. "There must be something wrong," 
said he ; "I shall appoint a superior officer to make sure that the former 
faithfully does his duty." No sooner was the plan adopted than the 
first goes to his new overseer, and convincing him very readily, that if 
the proceeds of two pounds be conveyed to their pockets, the meat 
would be far better employed than in feeding the lion, they agreed to 
keep their own counsel and share the profit between them. But the 
thirst of the newcomer soon becomes pleasantly excited by the sweets 
of peculation. He talks the matter over with his subordinate, and they 
have no difficulty in discovering that the lion might very well be reduced 
to three pounds a day. Drooping and emaciated, the poor beast pines 
in his cage, and the Sultan is more perplexed than before. " A third 
official shall be ordered, " he declares, " to inspect the other two " ; and so 
it was. But they only wait for his first visit to demonstrate to him the 
folly of throwing away the whole six pounds of meat upon the lion, 
when with so little trouble they could retain three, one apiece, for 
themselves. In turn his appetite is quickened and he sees no reason 
why four pounds should not be abstracted from his ward's allowance. 
The brute, he states to his colleagues, can do very well on two, and if 
not, he can speak to nobody in complaint, so why need they lose the 
gain? And thus the lion, reduced to starvation-point, languishes on, 
robbed and preyed upon by the overseers set to care for him, whose 
multiplication has but added to his miseries. ' 



(1) Buffon's Hist. Nat., vol. xii., 1764, p. 24. 

(2) Burckhardt, Travels in Nubia, 1819, p. 67. 

(3) For a characteristic hunting scene of the Pyramid Age see Borchardt, 
Grabdenkmal des Kbnigs Sahure ; for one of the Middle Kingdom, New- 
berry, El Bersheh I, pi. vii. 

(4) The Sphinx Stela, 1, 5. 

(5) Newberry, Scarabs, pis. xxxiii.-iv. 

(6) Giornale I'Esploratore, anno ii.,fasc. 4. 

(7) Brit. Mus., Add. MS., 25666. 

(8) Burckhardt, Travels in Syria, 1822, p. 461. 

(9) W. G. Browne, Travels in Africa, ttc. 

(10) Mem. sur I'Egypte, vol. i., p. 79. 

(11) Letters on Egypt, d;c., ed. 1866, p. 107. 

(12) Journal of Egyptian Archceology , vol. v., p. 234, pi. xxxiii. 

(13) Petrie, Abydos I, pi. L. 

(14) Lydekker, Brit. Mus., Guide to the Great Game Animals, 1913, p. 39, and 
figs. 21, 22. 

(15) Journal of Egyptian Archoiology, vol. v., pi. xxxiii., p. 227. 

(16) Anderson, Zoology of Egypt (Reptilia), p. xlvi. 

(17) Schweinfurth, Heart of Africa, vol. i., p. 69. 

(18) C. G. Seligman, Journal of the Anthropological Institute, vol. xliii., p. 595. 

(19) Burckhardt, I'ravels in Nubia, p. 387, ct seq. 

(20) Proceedings of the Society of Biblical Archeology, Feb. 1906, p. 69. 

(21) That Narmer was Menes is proved by a sealing published by Petrie in 
Royal Tombs of the Earliest Dynasties, pi. xiii., 93. His conquest of Tehenu- 
land is recorded oa an ivory cylinder published by Quibell, Hicrakonpolis I, 
pi. XV., 7. 

(22) The cults of the Double Axe and of the Dove or Swallow are found on 
monuments of the Pyramid Age. 

(23) I owe my knowledge of the greater part of the Soleb scenes to Prof. 
Breasted, who kindly showed me unpublished drawings of them when I 
visited him in Chicago in 1921. 



GEORGE H. F. NUTTALL, M.D., Ph.D., Sc.D., F.R.S., 

Quick Professor and Director of the Molteuo Institute for Research in 
Parasitology, Univei'sity of Cambridge, 



Introduction ............ 197 

I. Symbiosis in Plants : — 

(1) Lichens 197 

(2) Root-nodules of Leguminous Plants ...... 199 

(3) Significance of Mvcorhiza in various Plants .... 200 

(a) Orchids . ' 200 

(b) Origin of Tubers in various Plants ..... 202 

(c) Ericaceae 203 

(d) Club-mosses aud Ferns ....... 203 

II. Symbiosis in Animals : — 

(1) Algae as Symbionts in various Animals ..... 203 

(2) Symbiosis in Insects ........ 206 

(3) Micro-organisms in relation to Luminescence in Animals . . 209 

(a) Luminescence due to Parasitic Organisms . . .210 

(6) Luminescence due to Symbionts in Insects, Cephalopods, 

Tunicata (Pyrosomidae) and Fish .... 210 

Portier's Hypothesis 212 

Conclusion ............ 213 


The subject of symbiosis has been chosen for this address because of its 
broad biological interest, an interest that appeals equally to the physio- 
logist, pathologist, and parasitologist. It is, moreover, a subject upon 
which much work has been done of recent years in different countries, 
and this seems a fitting occasion upon which to give a brief summary 
of what is known to-day, especially since the literature relating to 
symbiosis is largely foreign, somewhat scattered and relatively 

I. Symbiosis in Plants. 

(1) Lichens. 

It is well known to botanists that the vegetative body (thallus) of 
lichen plants consists of two distinct organisms, a fungus and an alga. 
The alga, individual elements of which are called 'gonidia, ' is either 
scattered throughout the thallus or, as in most cases, it forms a well- 
defined layer beneath the surface of the thallus. The view that lichens 


consist of the two elements mentioned was advanced by Schwendener 
(1867-9)i who regarded the fungus as Uving parasitically upon the alga, 
a view which gained support from the researches of Bornet (1872), 
Voronin (1872), Treube (1873), etc., and especially of Bonnier (1886-9), 
wherein synthetic cultures were obtained by bringing together (a) various 
algae obtained in the open and (b) fungus-spores isolated from cultures 
of fungi forming the one component of certain lichens. 

Schwendener 's view, that the fungi are parasitic on the algse in 
lichens, was contested by Eeinke (1873) on the ground that a state of 
parasitism did not explain the long and apparently healthy hfe of the 
associated fungi and algas, a biological association for which the term 
Consortium was proposed by him, that of Homobium by Frank (1876), 
and that of Symbiosis by de Bary (1879), the latter term denoting a con- 
dition of conjoint life that is more or less benefixial to the associated 
organisms or symbionts. 

Investigation has shown that the relation or balance between the 
associated organisms varies in different lichens. Thus in some forms 
of Collemacea, as stated by Bornet (1873), the partners as a rule inflict 
no injury upon each other, whilst in some species of Collema occasional 
parasitism of the fungus upon the alga (Nostoc) is observable, since 
short hyphal branches fix themselves to the alga cells, these sw^elling, 
their protoplasm becoming granular and finally being voided. In 
Synalissa and some other lichens the hypha penetrates into the interior 
of the alga, where it swells and forms a sucker, or haustorium. EJenkin 
(1902-6) and Danilov (1910) take it as proved that lichens owe their 
origin to ])arasitism, the fungus either preying upon the alga or living 
as an ' endosaprophyte ' (Elenkin) upon the algfe that die. 

Therefore, we may find in lichens the condition of true symbiosis on 
the one hand, ranging to demonstrable parasitism on the other, and, 
conversely to what has been desci'ibed above, instances are known 
wherein algae are parasitic on fungi (Beijerinck, 1890). 

Pltysiology of Lichens. 

The mitrition of alga in lichens is similar to that of other chloro- 
phyllaceous plants, the most important work on the subject being that 
associated with the names of Beijerinck (1890) and Artari (1902). In 
respect to nitrogen supply, Beijerinck cultivated various green algae, 
as well as gonidia derived from Physcia parictina. The gonidia only 
multiplied rapidly in a malt-extract culture-medium to which peptones 
and sugar were added. This showed that the algfe associated with 
fungi as in lichens w^ere placed advantageously in respect to nitrogen 
supply. He termed such fungi 'ammonia-sugar-fungi,' because they 
extract nitrogen from ammonia salts and, in addition to sugar, form 
peptones. Artari showed that there exist two physiological races in 
green algae., those which absorb and those w'hich do not absorb peptones. 
He found that the gonidia (Cystococcus humicola) derived from Physcia 
parietina absorbed peptones, and he consequently referred to such algse 
as ' peptone-algae. ' Treboux (1912), however, denies the existence of 
peptone-sugar-races of algae, and regards the algae in lichens as the 
victims of jiarasitic fun.iri. Nevcrtlieless, tlu; im]iort;uit researc-lios of 

1.— PHYSlOLoaV. 11>9 

Chodat (1913) have deinuuslrated that cultivated guiiidia develop four 
times as well when supplied with glycocoll or peptone in place of 
potassium nitrate. 

The carbon supply of gonidia, according to Artari (1899, 1901), 
Radais (1900), and Dufrenoy (1918), is not derived photosynthetically, 
but from the substratum on which they grow. Whilst Tobler (1911), in 
his culture experiments with lichens, found that the gonidia obtain their 
carbon from calcium oxalate secreted by the fungus, Chodat (1913) 
observed that cultured gonidia grow but slowly without sugar (glucose), 
which he believes constitutes their main source of carbon supply. 

Whereas, accoi'ding to Chodat, the gonidia grow poorly on organic 
nitrogen in the absence of sugar, they develop rapidly when sugar is 
added. He therefore concludes that the gonidia lead a more or less 
saprophytic life in that they obtain from the fungus-hyphse both organic 
nitrogen and carbon in the form of glucose or galactose. 

The nutrition of fungi in lichens depends partly upon parasitism, 
when they invade the gonidia, and partly upon saprophytism, when 
they utilise dead gonidia (Chodat). 

In concluding this section, the hypothesis of M. and Mrne. Moreau 
(1921) demands mention, since it bears upon the manner in which 
lichens may have originated in nature. They regard the fungal portion 
as a gall-structure arising from the action of the associated alga. The 
Uchen, according to this view, is to be regarded as a fmigus that has 
been attacked by a chronic disease which has become generalised and 
necessary for the subsistence of the host-fungus. F. Moreau (1922) 
sums up this view as follows : ' The lichen-fungus appears as an 
organism characterised in its morphology by deformity due to an infec- 
tive agent, an alga. The history of the association existing in lichens 
may be described as that of a contagious malady marked by the invasion, 
development, inhibition, and death of the infective agent on the one 
hand, and on the other hand by the morphological reactions and defen- 
sive processes of the attacked organism. In conformity with the 
virulence and relative immunity of the two opponents, the struggle may 
be short, the association transitory, the' conflict may last indefinitely, 
and the association, rendered lasting, presents the appearance of a 
harmonious symbiosis.' 

(2) Tlic Eoot-nodides of Leguminous and other Plants. 
A well-known example of symbiosis is afforded by the presence of 
the bacteroids in the nodules of leguminoste, the micro-organisms being 
capable of fixing atmospheric nitrogen and thereby rendeiing nitrogen 
available for assimilation by the plant. This was demonstrated by 
Hellriegel and Willfahrt (1888), Schloesing and Laurent, whilst Beije- 
rinck cultivated Bacterium radicicola from the nodules and produced 
nodules synthetically by bringing the plant and bacterium together on 
previously sterilised soil. According to Pinoy (1913), the bacteroids 
are myxobacteria, and, in the case of one species which he has specially 
studied (Chondromyces crocatus), it was found essential for the 
successful cultivation of tlio micro-organism, apart from its host-plant 
and in vitrn, tlmt it should bo ltowii in nssnriiilion witli ;i siwcics of 


micrococcus ; similar observations have been made on other micro- 
organisms by bacteriologists, and some refer to the condition as one of 
symbiosis. Bacteriologists, I would note, are continuously misapplying 
the term symbiosis in referring to bacteria grown in mixed cultures, 
when there is no evidence whatever that the micro-organisms are 
mutually interdependent for their growth. In passing, it may be men- 
tioned that nodules on the roots of the alder are attributed to the presence 
therein of >Streptothrices, and that comparable nodules occur in 
Eleagnaceee. The nodules on the leaves of Eubiacese and tropical 
Myrsinaceae are also regarded as due to bacterial symbionts. 

(3) The significance of Mycorhiza in relation to various Plants. 

It has long been known that the roots of most perennial and 
arborescent plants are invaded by the mycelium of fungi known as 
Mycorhiza, and it is to Kamiensky (1881), and especially Frank (1885), 
to whom we owe the hypothesis that we are here dealing with symbiotic 
life. Frank distinguishes two forms of Mycorldza: (1) the ectotrophic, 
which surround the root externally like a sleeve and are found especially 
about the roots of forest trees (Conifers), and (2) endotrophic , which 
penetrate deeply into the root tissue and even into the cells of the root. 
The endotrophic Mycorhiza are derived from the outside ; their mycelium 
enters the root by penetrating the epidermal cells at the base of the 
root hairs, passes between the cells and into them where the mycehum 
branches dichotomously, and forms ultimately a much-branched intra- 
cellular gi'owth. By this time the fanc;us is no longer in communica- 
tion with the exterior of the root, and it nourishes itself within the 
host cell, only, however, by utilising the reserve substances stored there 
whilst avoiding the cell protoplasm or other living host elements. The 
host cell, after a period of inei'tia, exhibits a distinct reaction to the 
presence of the fungus, in that its nucleus becomes hypertrophied, 
divides repeatedly and becomes amoebiform in contour. The contained 
mycelial mass undergoes degeneration, is digested by the host, and the 
host-cell resumes its normal life. These root-Mycorhiza have not as 
yet been cultivated,* as have others to which reference will presently be 
made, and it is as yet impossible to assign them a place among known 
species of fungi. Further details regarding these forms will be found 
in the publication of Gallaud (1904). 

Mycorhiza in Orchids. 

The first to note the presence and to attempt to cultivate the fungus 
mycelium in the roots of orchids was Eeisseck (1846), and in 1881 
Kamienski advanced the hypothesis that the association was one of 
symbiosis. Wahrlich (1889) subsequently found symbionts in all 
species of orchids he examined, about 500 in number, thereby showing 
that their distribution is generalised. 

It is to the researches of Noel Bernard (1902 onward), however, that 
we are actually indebted for the complete demonstration of the true 

» Magrou (1921) reports that he isolated Mncor solarium n. sp. from Solarium 
dulca-mara, and he seems to have infected the potato plant with the fungus. 



relation existing between orchids and Mycorhiza, based as it is upon 
physiological studies. All who had to do with orchids in the last 
centuiy found the greatest difficulty in raising these plants from their 
seed; a successful result appeared to depend largely on chance. Culti- 
vators of orchids found that success was obtained more frequently by 
placing seed in soil upon which orchids had previously lived, and much 
secrecy was observed as to the methods employed by the more successful 

The seeds of orchids are exceedingly small — a million may be found 
in a single capsule of an exotic species; they possess no albumen and 
contain an embryo consisting merely of a mass of undifferentiated cells 
provided with a suspensor. The essential discovery of Bernard was that 
orchid seeds do not germinate in the absence of fungi belonging to the 
genus Rhizoctonia. The fungus enters the seed through its least 
resistant and highly permeable cells, which apparently emit a secretion 
that attracts the fungus. Each species of orchid, according to the subse- 
quent researches of Burgeff (1909), possesses a special species, variety, 
or race of fungus that is particularly adapted to it — he distinguishes 
filteen species of fungus. When mutually adapted orchid seed and 
fungus are brought together, the mycelium of the latter penetrates the 
suspensor cells by digesting their cellulose wall. The mycelium 
traverses the epidermal cells of the seed without undergoing development 
within them. As soon as the primary infestation has occurred, even 
where the mycelium has penetrated but slightly, the cells of the seed, 
situated at the posterior pole of each embryo, cease to be vulnerable. 
In other woi'ds, a local immunity appears to be established, this 
immunity lasting at any rate until new regions are attacked by the 
fungus. This, in Bernard's experience, is the general rule. The 
mycelium, having attained the parenchyma cells, develops into charac- 
teristic filamentous masses recalling the appearance seen in bacterial 
agglutination. Nevertheless, there comes a time, this varying according 
to the associated species involved, when the development of the fungus 
is arrestetl by the deeper parenchyma cells of the seeds. These' cells 
are altei'ed before they are penetrated by the fungus ; they become hyper- 
trophied and acquire large lobose nuclei. They digest the mycelium 
which enters their protoplasm, but the cell continues to harbour remains 
of the fungus (' corps de ddgenerescence ') which occur abundantly in 
the tissues of orchids. The seed now proceeds to sprout, giving rise to 
a small tubercle (' protocorm '), which only at a later period produces 
leaves and roots. 

The cidtivation of Rhizoctonia oi various species was earned out 
successfully by Bernai'd, the cultures being used to reproduce germina- 
tion in orchids. Orchid seeds alone remained unchanged for months in 
cultures on agar with salop-decoction added, but when pure cultures of 
Rhizoctonia mycelium were added to such orchid seeds, the latter were 
invaded by the fungus, germinated, and gave rise to a ' protocorm.' 
Bernard gives excellent figau-es illustrative of the development described. 

The relation between the fungi and orchids varies in different groups 
and plants. In primitive forms like Bletilla germination occurs in the 
absence of the fungus, but the ' protocorm ' does not develop ; the 


rhizome, to which the plant is periodically reduced, is only periodically 
attacked when fresh roots are formed. Bletilla, however, behaves in 
an exceptional manner. In other orchids {Ophrydece, Cattleyccr, Cypri- 
pedecB, &c.) the fungus is needed for germination, and the adult plant is 
fungus-free except when the orchid produces fresh roots. Therefore, 
in such cases symbiosis is intermittent. In higher orchids like the 
epiphytic Sarcanthinece the fungus is needed for germination, and, the 
roots being persistent, symbiosis is maintained continuously. Finally, 
in Neottia nidus-avis the symbiotic condition is maintained throughout 
the life-cycle of the orchid, the fungus being found in the roots, rhizome, 
and even in the flowers and seeds, and it is transmitted hereditarily. 

The activity or ' virulence ' of Rhizoctonia, according to Bernard, 
diminishes when the fungus is kept apart from the orchid, being prac- 
tically lost after two or three years. An attenuated fungus x-egains its 
activity in a measure after a sojourn of some weeks in a young orchid 
plant; a full degree of activity under symbiotic conditions is, however, 
only regained slowly. 

The germination of orchids in the absence of fungi was successfully 
induced by Bernard through cultivating them in concentrated nutrient 
solutions of a kind that does not occur in nature; such solutions, more- 
over, except under carefully carried out experimental conditions, would 
be rapidly vitiated through serving as a medium for the multiplication 
of different micro-organisms. The effect of increasing the concentration 
of the solution, offered to plants reared without fungi, corresponds to 
that obtained by raising plants with fungi of increasing activity or 
' virulence. ' It may be added here that when Rhizoctonia are cultivated 
on a medium containing sacchai'ose and the substance of orchid tubers — 
namely, salop — they cause an increase in the molecular concentration of 
the medium. It is possible that the fungi, when associated with the 
orchids, bring about a similar increase in the molecular concentration 
of the sap of the invaded plant. 

The Origin of Tubers in Various Plants. 

The occuri'ence of endotrophic Mycorhiza in the roots of species of 
Solanum has been recorded by Janse (1897) for S. verbascifolium in 
Java, by Bernard (1909-11) for ,S'. dulca-mara, by Mme. Bernard and 
Magrou (1911) for S. -inaglia collected in Chili, the last-named species 
having been regarded by Darwin as the wild type of S. tuberosum, our 
edible potato. 

Experimenting with the potato, MoUiard (1907, 1920) found that 
tubers were not formed in aseptic cultui'es in a poor nutrient medium, 
and that raising the concentration of the sugar in the sap artificially (as 
with the radish) led to tuberisation ; concentrating the culture-medium 
did not induce tubers. Magrou (1921) placed potato seeds in a poor 
soil and close to S. dulca-mara, which always contains fungi, and found 
that only when the fungus invaded the potato plant were tubers formed. 

Magi'ou also investigated tuberisation in Orobus tuberosus (Legu- 
minosae) and in Mercurialis perennis (Euphorbiacese), and from his 
collective studies the followincr conclusions mnv be drawn : — 

I.— rHYSIOI.OCJV. 203 

(1) When the potato phmt and Orobus are raised from seed, the 
estabhshment of symbiosis leads to tuberisation of the sprouts at the 
base of the stem ; tubers are not formed in the absence of symbionts. 
(2) Owing to developmental differences between the two plants, 
symbiosis in the potato plant is intermittent, whilst in Orobus it is 
continuous. (3) It follows that these plants may develoj-) in two ways : 

(a) when they harbour symbionts they produce perennial organs; 

(b) without symbionts they are devoid of perennial organs. (4) It is the 
rule for wild perennials to harbour symbionts, as Bernai'd has stated, 
whilst annuals are devoid of symbionts ; three species of annuals 
(Solanum nigrum, Orobus ccpcineus, and Mercurialis anmta) may be 
penetrated by endophytes, but they quickly digest the intruders. 
(5) These observations confii'm and supplement the view held by Bei-nard 
that tuberisation is due to the association of fungi with plants. 

Mycorhiza in Ericaccce. 

Eayner (1915-16) finds that Mycorhiza are constantly present in 
heathers. He isolated Mycorhiza (of the genus Phoma) from Calluna 
vulgaris, in which the fungus is widely distributed, being found in the 
I'oots, branches, and even in the cai'pels, so that it occurs within the 
ripe fruit and seed tegument. Calluna seeds, when grown aseptically, 
give rise to poor little plants devoid of roots, but, under like conditions, 
in contact with Phoma the plants develop normally and fomi many 

Mycorliiza in Club-mosses and Ferns. 

In Lycopodiaceae (Club-mosses) and Ophioglossac-efe (Ferns), accord- 
ing to Bernard, the perennial prothallus is infested, and the spores 
whence the plants emanate will not germinate except (as with orchid 
seeds) with the help of fungi. 

In concluding this part of my subject, dealing with symbionts of 
plants, I need scarcely emphasise the significance of symbiosis in the 
vegetable kingdom. I will close by mentioning the theoretical deduction 
of Bernard that vascular plants owe their origin in the past to the 
adaptation of certain mosses to symbiotic life with fungi. 

II. Symbiosis in Animals. 

(1) Alg(2 as Symbionts. 

Animals of widely separated groups characterised by their green 
colour have long been known. Already in 1849, von Siebold attributed 
the colour of Hydra viridis to chlorophyll which, for a period, was 
regarded as an anmial product. In 1876, Gesa Entz concluded that 
the chlorophyll is contained in vegetable cells living as parasites or 
commensals within the animals ; these cells were aptly named 
zoochJorella by Brandt (1881), whilst cells distinguished by their yellow 
colour wei'e subsequently called zocranthella, the latter having been 
first described by Cienkovsky (1871) as present in Eadiolaria. In the 


latter case the symbionts were found capable of surviving their host, 
of multiplying, and of assuming a flagellate stage. 

Zoochlorella occur mainly in fresH-water animals, zooxanthella 
mainly in marine animals, the symbionts, measuring 3-10 microns in 
size, being found in many Protozoa, Sponges, Ccelenterates, Cteno- 
phores, Turbellaria, Rotifers, Bryozoa, Annelids and Molluscs. 

Physiological relations between Animals and Symbiotic Algce. — In 
1879, Geddes showed that green animals give off O'Xygen, Convoluta 
roscofjensis (Turbellaria), when well illuminated, liberating gas con- 
taining 45-55 per cent, of oxygen. Engelmann (1881), by means of 
his bacteria-method, showed that Hydra viridis (Ccelenterata) and 
ParamcBcium bursaria (Protozoa) give off oxygen when exposed to light. 
Geddes (1882), working with a series of marine animals, found Velella 
gave off 21-24 per cent, of oxygen, and an Actinia (AntJwa cereus) gave 
off 32-38 per cent, of oxygen. Whereas animals harbouring green 
algae as symbionts always liberated oxygen, the colourless varieties of 
these animals never did so. Geddes regarded the association of animal 
and alga as being mutually helpful, the oxygen supplied by the alga 
to the animal and the carbon dioxide and nitrogen supplied by the 
animal to the alga being useful to the partners. He speaks of ' aninitil 
lichens ' and ' Agricultural Eadiolarians and Ccelenterates.' He found, 
moreover, that animals harboui'ing symbionts are much more resistant 
than those without symbionts : Medusae (Velella) survived 14 days in 
small beakers with symbionts, only 1-2 days without them. Proto- 
zoologists have, moreover, found that Protists harbouring symbionts 
are easier to rear in vessels than are those without symbionts. Brandt 
(1883) believes that the symbionts and host aid each other in nutrition. 
Green SpongiJla (fresh-water sponges) and Hydra viridis may live a 
long time in filtered water. He found that when starved green Actinia 
were (a) placed in the dark, they expelled their algae and died rapidly, 
being probably poisoned by the dead algee, but that when they were (b) 
placed in diffuse light they lived on. Actinia deprived of symbionts 
may become habituated in culture to live without them. Opinions 
(vide Buchner, 1921) are in conflict as to the exact relationship 
between the partners; in pome cases (Peneroplis and Trichosph(?,rium) 
the symbionts never appear to be injured, in Amoeba viridis, &c., a 
limited number of symbionts are digested at all times, whereas in some 
Radiolai'ians, &c., digestion only takes place at certain stages of their 
development. Nutritive substances pass from the algae into the host's 
cells ; thus starch granules, found alongside the algae, may be taken up 
by the animal cells. 

Using modern methods of gas analysis, Trendelenburg (1909) con- 
cludes that green Actinias (Anemonia sulcata) live in true symbiosis 
with algae, the algae supply oxygen to the animal by day and at night 
utilise the surplus oxygen evolved, whilst carbon dioxide is furnished 
to the alga, partly by the animal and partly by the water in which they 
are bathed. Eiitter (1911) studied the nitrogen metabolism and con- 
cludes (a) that the Actinia yields to the algae nitrogen in the form of 
ammonia for protein synthesis, and in darkness it adds carbon co^ntain- 
ing substances (nitrogen-free), whilst (/)) the alg;^ yield to the Actinia 



nitrogenous substances in the dark and by light carbon-containing 
substances. Organisms harbouring algte exhibit naturally a positive 

Symbiotic algsB are not usually transmitted hereditarily, each host- 
generation being usually infected afresh by algae, encountered about the 
host, which may be either free-living or possess a free-living stage in 
their development. Exceptions occur, however, where Protozoa multiply 
by division and the algae pass directly (as it were hereditarily) to 
succeeding generations. There are also cases of hereditary transmission 
in hosts that undergo sexual multiplication (as in Hydra viridis), the 
zoochlorella penetrating the egg on escaping from the host's endodermal 
cells after the manner of starch granules or other food reserve sub- 
stances (v. supra). Prom the circumstance that in most cases symbiotic 
algae are not transmitted hereditarily, we may explain the occasional 
occurrence of alga-free individuals in a species usually harbom'ing the 

Studies conducted on Tuebellaria are of special interest: These 
animals may contain either green or yellow symbionts, and, as in 
Protozoa, some allied species harbour the symbionts and others do not. 
The eggs of Turbellaria are symbiont-free, each generation becoming 
infected afresh, the symbiont either entering the host's mouth and 
remaining there, traversing the intestinal wall, or entering by the genital 
pore, according to the particular host-species it affects. 

The best-known example of symbiosis in Turbellaria is found in 
Convoluta roscojfensis, a species that has been well studied by Keeble 
and Gamble (1903-7). Its larvfe are colourless and infection occurs 
after hatching. Colourless larvae are obtainable by transferring freshly 
hatched examples immediately to filtered sea-water. The cocoon, on 
the day following its deposition, is already invaded by many algae having 
a very different structure from those found in Convoluta ; they possess 
four flagella and have been referred by Keeble and Gamble to the genus 
Carteria (allied to Chlamydomonas). The algae within the host possess 
a special structure, their contour is very irregular, they have no cellulose 
wall, the green colouring matter is unevenly distributed, being confined 
to chromatophore bodies surrounding the pyrenoid body, the nucleus is 
eccentric, and a number of examples are found with degenerating nuclei. 
Naturally all attempts to cultivate these obviously degenerating algte 
have failed. 

The physiological relatioins existing l)etweeu Turbellaria and algie 
differ according to the species. Thus in Vortex viridis symbiosis is not 
necessary, in Convoluta it> is necessary for both partners. Mature 
Convoluta are never found devoid of algae in nature. The young larva 
can only feed itself for a week; as it grows older it becomes infected 
progressively with algae and ceases to nourish itself otherwise than 
upon the products of its contained symbionts. Finally, having reached 
an advanced age, the animal becomes capable of digesting the algfe, as 
does Convoluta piradoxa under unfavourable conditions of life. Keeble 
and Gamble define four periods in the life of Convoluta, wliich they term 
respectively hetero-, mixo-, holo-, and auto-trophic, wherein the animal 


lives at the expense (1) of formed substances, (2) of these and alga- 
products, (3) of alga-products only, and finally (4) of the algse them- 
selves. This constitutes a true evolution in a species from a free 
existence, depending only on outside sources of food supply, to a 
symbiontic mode of life, and lastly one merging into parasitism. 

(2) Symbiosis in Insects. 

Among insects we find a whole series of progressive adaptations 
toward an association with micro-organisms of different categories: — 

Group I. — The utilisation by insects of micro-organisms cultivated 
by them outside their bodies. To quote three examples: (1) The larvae 
of the beetle Xyloteres lineatus (Bostrichidae) form galleries in the 
wood of Pines. The galleries have a characteristic blue colour, produced 
by the growth of the fungus Ambrosia upon their walls, the fungus 
being cultivated by the larva for food. The beetle is incapable of 
digesting cellulose. Analogous cases ofcur among Ants and Temiites 
thus : (2) Termes perrieri of Madagascar, studied by Jumelle and Perrier 
de la Bathie (cited by Portier, 1918), builds numerous chambers and 
galleries. The termites collect dead wood, chew it up finely, swallow 
it, the wood passing unaffected through their intestine and out in the 
form of small spherical masses (0.5 mm.) which are cemented together 
as porous cakes that are impregnated with digestive secretions. Fungi 
which develop upon the cakes serve as food for the termites, and in 
well -cared -for nests the gi'owth is harvested by the workers who triturate 
the mycelium and spores and feed the young larvae therewith, whilst 
older larvae receive spores, and large larvae receive mycelium and the 
triturated wood contained in the cakes. (3) A third example is that 
of ants belonging to the genus Atta which cultivate fungi over areas of 
5 to 6 square metres ; here the queen, when about to found a new colony, 
carries away a small ball of fungus in a corner of her mouth wherewith 
to start a fresh culture in the new habitat. 

Group II. — Sym,biotic organisms developing in the luvien of the 
intestine and its adnexa. As examples may be cited the bacteria 
occurring in the intestines of fly larvae (Musca, Calliphora, &c.), which 
aid the larva to digest meat; the bacteria associated with the olive- fly 
(Dacus olea) ; the Trychonymphids of xylophagous Termites [Leuco- 
termes lucifugus). 

Group III. — Intestinal symbionts situated in the epithelial cells of 
the digestive apparatus. The most striking instance is found in Anobium 
paniceuyn, a small beetle commonly occurring in flour, biscuits, dried 
vegetables, &c. In a part of its mid-gut are found cells filled with 
symbiotic yeasts undergoing multiplication (Escherich, 1900). The 
symbionts are not transmitted hereditarily but are acquired by the larva 
on hatching, being eliminated by the female beetle. 

In this connection may be mentioned with reserve the observation 
of Portier (1918) upon xylophagous Lepidoptera (Cossus, Nonagria, 
Sesia, &c.) which, according to that author, possess intestinal fungi 
[Isaria) that multiply in the gut and form spores that penetrate the 
intestinal epithelium and attain the perivisceral cavity, fat-body, and 


muscles of the insect. As CauUery points out, liovvever, the supposed 
spores closely resemble Microsporidia, and Portier's interpretation may 
be erroneous. In this category also belong the symbionts described as 
occurring in Glossina by Eoubaud (1919) and before him by Stuhlmann, 
these being found in certain hypertrophied cells of the intestinal epithe- 
lium. When liberated into the gut lumen, the symbionts are stated 
to multiply by budding after the manner of yeasts. Eoubaud regards 
the yeasts as fungi, allied to the Cicadomyces of SUI9, and finds that 
they are transmitted hereditarily from the adult to the egg, larva and 

Group IV. — Intracellular symbionts of deep tissues. This group 
of symbionts is most frequently found in insects, but their natm-e was 
not disclosed until recent years. Already, in 1858, Huxley described 
an organ whicli is constantly present close to the ovary in Aphis. 
Balbiani (1866) named it the pseudovitellus, or green body, and 
Metchnikoff (1866), who followed its development, named it ' secondary 
vitellus.' The function and structure of this organ were studied by 
subsequent authors without being understood until, in 1910, there 
appeared two important papers by Pierantoni (February 6), and Sulc 
(February 11), who demonstrated their symbiotic character, recognising 
the intracellular inclusions as yeasts whose evolution they completely 
followed. Their results have been confirmed by various authors, 
especially by Buchner, who' in a remarkable series of papers describes 
a number of associations existing between insects and micro-organisms 
and reaches important generalisations as to their significance. It is 
from a collective work on the subject by Buchner (1921) that most of 
our information regarding this class of symbionts is taken. 

Among the symbionts of deep tissues in insects are found a whole 
series of specialisations among the host-elements harbouring the 
symbionts. The least specialised instance is represented by Lecaniinse 
where the yeasts are distributed throughout the body (perivisceral fluid, 
cells of fat-body) ; the fat-bodv cells may be regarded here as facultative 
Mycetocytes. In cases like OrtheziU; symbiotic bacteria occur in certain fat 
cells which still contain fat droplets; this condition is also found in certain 
Cicadas, the yeasts being contained in fat cells which continue to 
accumulate fat, glycogen and urates. Finally cases occur as in Blattids 
where symbiotic bacteria arc found in special cells greatly resembling 
fat cells but already forming well differentiated Mycetocytes. This 
class is well represented in and about the digestive tract of Pediculidae 
(Hcgmatopinus) and certain ants (Campoiiotus). Still more advanced 
in specialisation are those cases in which the symbiont-oontaining cells 
(Mycetocytes) agglomerate to form true organs terme<l Mycetomas, 
organs that are surrounded by flattened epithelial cells, the component 
mycetocytes containing either yeasts or bacteria as symbionts ; such 
cases are found in Aphids, Cheniiids and Aleurodids. Mycetomas may 
occur singly or in numbers according to the nature of the host; the 
epithelial covering of the organ varies in its cell structure and pig- 
mentation, and tlie organ may be plentifully supplied with trachefo 
whose finest branches penetrate into the interior of the mycetocytes. 
Tlie relations between the mycetocytes or mycetomas and the other 

l'.)2:) Q 


organs of the host vary greatly ; in some cases they occur especially in 
the fatty tissue, in others near the gonads, in others, as in Pediculidae 
around or upon the intestine. In Pediculus and Phthirus, parasitic on 
man, the mycetoma is disc-shaped and lies centrally as a distinct milk- 
white structure upon and indenting the mid-gut. Transition foiTns 
between isolated mycetocytes and differentiated mycetomas' are found 
in various insects. 

The mode of transmission of intracellular symbionts of insects from 
generation to generation may take place in different ways as defined 
by Buchner (1921, somewhat modified) : 

I. The larva of each generation infects itself through the mouth 


II. Infection takes place hereditarily through the egg: 

1. By symbionts set free in the blood, or which leave mycetocytes 

or mycetomas and attain the egg as follows: — 

(a) by general infection of follicles and invasion of the egg, and 

finally establishing themselves at the posterior pole of 
the egg (Ants) ; 

(b) by penetrating special parts of the follicles, producing for 

a period bacterial vegetation upon the whole egg and 
finally concentrating at the egg's two poles (Blattidfe) ; 

(c) by entering the egg via its nutritive cells 

(a) only some isolated fungi entering (Ijecaniinaj) ; 

(b) a number of bacteria enter in the form of a gelatinous 

mass (Coccinse) ; 

(d) by entering the posterior pole of the egg : 

(a) as isolated fungi 

(a) which penetrate one after another (Aphids) ; 

(b) which accumulate in follicles and enter in a mass 

consisting of 

(a) one kind of symbiont (Icerj^a) ; 

(b) two kinds of symbiont (Cicada, Aphrophora) ; 

(c) three kinds of symbiont (Aphalara ?) ; 

(b) as bacteria united in several gelatinous masses 


2. By whole mycetomas entering at posterior pole of egg 


3. By isolated symbionts leaving special mycetomas situated at 

juncture of follicular tubes (Pediculidae). 

III. Embryonal infection as in parthenogenetic Aphids. 

It is difficult' to undeirstand the mechanism whereby the symbionts 
penetrate the egg in the insect's body ; in any case the complicated 
procedure must depend upon a mutual and parallel adaptation of the 
insects and micro-organisms concerned. 

During embryonal development the topographical distribution of the 
mycetocytes varies from one gix>up of insects to another. In Cam.- 


ponotus they occur dorsally upon tho mid-gut; in Blattidce the bacteria 
are at fii'sb localised in the intestinal lumen, passing thence through the 
intestinal epithelium and entering the fat-cells. In Hemiptera and 
Pedi'culidae the sym'bionts form a mass at the posterior pole of the 
germinal layer, and during version or unrolling of the embryo they 
penetrate in the ventral region of the abdomen. 

As already indicated, the symbionts may be Yeasts, Saccha- 
romycetes, Bacteria, or even Nitrobacteria. Their entrance into tho 
cells and their pi'esence therein even in large numbers does not in many 
cases pi-event multiplication of the invaded cells or affect their mitosis ; 
in other cases mitosis is more or less affected ; it may become multipolar 
and lead to synsytium formation ; and finally, cases may occur in which 
mitosis ceases and the symbiont-beai-ing cells divide amitotically. 

We know httle regarding the part played by symbionts in insects ; 
our infoi'mation relates almost exclusively to their morphology, mode 
of multiplication, and entry into the host during its development. 
There are no indications that the symbionts are injurious or pathogenic. 
It is evident, however, that they find in certain insects favourable 
conditions for growth, multiplication, and transmission from host to 
host. In these cases, therefore, we are dealing with a constant very 
harmonious association which excludes even a suspicion of there being 
any conflict between the associated organisms. We may well nsk 
ourselves what are the reciprocal advantages of this association, but this 
is a question that it is impossible to answer in view of our ignorance 
of physiological and biochemical processes in insects. 

Various hypotheses have been advanced to explain the possible func- 
tion of the symbionts. Symbiotic yeasts may decompose urates (SuIq.") ; 
they may produce an enzyme that aids in digestion of sugars, as in 
Aphids (Pierantoni) : they may aid in digestion of cellulose in xylo- 
phagous insects which alone cannot render cellulose assimilable 
fPortier); the Nitrobacteria found in various Hemiptera may fix frep 
nitrogen which, is conveyed to them through the host's trachefe. and 
thus supply the host with nitrogenous substances, thereby meeting a 
deficiency in its food supply. 

Phytopbasous Hemiptera nourish themselves chiefly upon leaf-sap 
without utilising the protoplosm of the plant-cells thev penetrate with 
their sucking mouthparts. The imbibed sap is rich in mineral sub- 
stances, carbohydrates and glycosides only. In these insects Peklo 
finds two different symbionts, Saccharomycetes and coccoid organ- 
isms, whilst Pierautoni attributes to symbionts the pigment production 
in Coccus cacti. 

(S) Micro-organisms in Belation to Luminescence in Animals. 
A fairly large number of organisms are known which have the 
faculty of emitting light. They are found among Bacteria, Fungi, 
Protozoa, Coelenterates, Echinoderms, Worms, Molluscs, Crustacea', 
Insecta, Tunicata, and Fish. As a rule luminescence' in animalp 
depends upon the action of luciferase on luciferin. but recently a number 
of cases have become known wherein light production has been traced 
to micro-organisms, and it is with these cases that we shall deal. 

Q ? 


Luminescent pathogenic bacteria may invade the host, as described 
by Giard and Billet (1889-90), for th© small marine amphipod, Talitrus, 
of which rare light-emitting examples may be found in nature. The 
affected crastacean dies in about six days. The pathogenic bacterium 
does not luminesce in cultures, but does so when inoculaited into 

Luminescent symbiotic bacteria present in various light-emittmg 
animals are, however, of direct interest to us, since theh- presence has 
been determined in luminescent organs of certain insects, cephalopoda, 
tunicates, and fishes: 

Insects: Pierantoni (1914) investigated the luminous organs of 
glow-worms {Lavifyms), and found them to consist of parenchjTna 
cells crowded with minute bodies having bacteria-like staining reactions, 
these bodies being also present m the beetle's egg, which is luminous. 
He cultivated two species of micro-organisms from the organs, buA does 
not distinctly establish their causal relationship. 

Cephalopods : We owe to Pierantoni (1917-20) and Buchner the 
discovery that luminescence in certain Cephalopofls is due to light- 
prcducing bacterial symbionts living in special organs of the host. 
These organs may be simple or otherwise. In Loligo the luminous 
organs, hitherto known as 'accessory nidamentary glands,' represent 
the simpler type of organ, this consisting merely of a collection of 
epithelial tubes suiTOunded by connective tissue. In cuttle-fish 
{Sepiola and Eondeleiia) the organs are more comphcated, the glands 
being backed by a reflector, and provided outwardly with a lens serving 
for the projection of the light rays generated by the symbionts within 
the tubes. The s>TnfBionts are- transmitted hereditarily when the 
Cephalopods lay their eggs. The symbionts of Loligo and Sepiola 
have been cultivated by Pierantoni and Zirpolo (1917-20); they 
inhabit the gland-tubes of the luminescent organs in lai'ge numbers, 
and produce light continuously, as do other luminescent bacteria in 

TuNicATA : The Pyrosomidse, all of wliich emit light and form 
tubular colonies, have long attracted the attention of biologists. Each 
individual in the colony possesses two fairly large luminescent organs, 
whose structure was studied by Panceri (1871-77), Kovalevsky 
(1875), and especially Julin (1909-12), who obsei-ved in the cells of 
the luminous organ riband-Uke structures appearing knott;ed here and 
there. Julin regarded the structures as mitochondria or chromidia, and 
it was left to Buchnea- (1914) to explain their trae nature; tliey are 
symbiotic fungi, and are transmitted hereditaiily. Buchner gives a 
detailed study of the symbiont and b^ review of the physiology of 
luminescence and of P\Tosomes which is well worth consulting by those 
interested in such problems. 

Fish : Of great interest are the researches of Harvey (1922) upon 
light prduction by two species of fish (Phoiohlepharon and Anomalovs) 
which occur in the sea about the Banda Islands, Moluccas. Their life- 
history is unknown. Thev measure up to about 11cm. in length. The 
author writes: ' In both fishes the luminous organ is a compact mass 
of white to cream-coloured tissue, flattened oval in shape, lying in a 


depi'ession just under the eye and in front of the gills. The organ 
looks as if made for experimentation, as it is attached only at the dorso- 
anterior end, and can he cut out with the gi'eatest ease, giving a piece 
of practically pure luminous tissue. The back of the organ is covered 
with a layer of black pigment, which serves to keep the light from 
shining into the tissues of the fish. In both fishes there is a mechanisin 
for obscuiing the light, but, curiously enough, the mechanism developed 
is totally different in the two species, notwithstantling the fact that in 
stiiictm'e the organ is identical in the two, and in every detail except 
proportion the fishes are very similar. In Anoinalopi; the organ is hinged 
at the a-ntero-dorsal edge, and can be turned downward until the light 
surface comes in contact with a fold of black pigmented tissue, forming 
a sort of pocket. The light is thus cut off. In PhotoUepharon a fold 
of black tissue has been developed on the ventral edge of the organ 
socket, which can be drawn up over the light surface like an eyelid, 
thus extinguishing the light.' The histological structure of this organ 
was worked out by Steche (1909). The organ is continuously 
luminous day and night, and independent of stimulation. According 
to Steche, AnomaJops constantly turns the light on and off (10" light, 
5" dark), the fish using it, he supposes, as a searchlight to a.ttract 
and mislead its prey. The natives use the amputated organ as a bait 
in night fishing; it maintains its luminosity for about eight hours. 
The organ is described by Steclie as composed of a great number of 
sets of parallel gland tubes (acinose), separated by connective tissue, 
and extending across the organ from the back pigmented surface to the 
front transparent surface, each set a)Tanged in a ring about a vessel 
which provides llieni with blood and oxygen. Near the surface a 
luunber of ihcsc li]l)t's unite into a. conunou resGrvoir openuig outwai'd 
through a mimite ]ior& which admits sea- water. A number of pores 
dot the surface of tjie organ. The luminous raateilal fills the lumen 
of the tubes ; it is extracellular but intraglandular, and is never voided 
from the ^land. Harvey states that the luminous material filling the 
tubes consists of an emulsion containing many granules and rods; the 
latter move about with a corkscrew-like motion, and are uiidoubtedly 
bacteria. The luminosity of the organ is due to these symbiotic bac- 
teria. _ An emulsion containing tlie symbionts behaves exactly hke an 
emulsion of luminous bacteria in being sensitive to lack oxygen, desic- 
cation, bacteriolytic agents, potassium cyanide, &c. The continuity of 
the light, independently of stimulation, is characteristic of luminous 
bacteria and fungi alone among organisms; this, and the circumstance 
that luciferin and luciferase could not be demonstrated, all go to confirm 
the correctness of Harvey's conclusions rcgardiug the cause of 
luminosity in these fish, notwithstandhig that he has failed hitherto to 
cultivate the bacteria found in the luminous organs. 

In concluding this section deaUng with light production by animals 
it may be repeated that we have to distinguish between (a) luminescence 
due to symbiotic organisms, such luminescence being contiimous in 
the presence of oxygen as in cultures of luminous bacteria (of which 
some thirty species are known), and (b) that due to animal cell-products 
known as luciferin and luciferase which are secreted and expelled 


at intervals, in response to a stimulus, from two kinds of gland cells, 
the secretions, when mixed, producing light. 

Portier's Hypothesis. 
The numerous cases in which symbiosis occars in nature have 
naturally led some biologists to ask if .symbiosis is not a phenomenon 
of general significance, and perhaps essential, in living organisms. In 
this connection reference must be made to the hypothesis advanced by 
Portier (1918), because it formulates extreme views. Starting from 
his studies of symbionts of leaf-mining caterpillars (Nepticida) and 
wood-devouring insect larvae {Cossus, Sesia, &c.), he sought to verify 
the work of Galippe (1891-1918) on micro-organisms occurring in verte.- 
brate tissues. Using methods he supposed to be adequate, Portder 
claimed that he could isolate various micro-organisms from vertebrate 
tissues. On faulty premises he built up an hypothesis that may be 
likened to a house of cards. He divides living organisms into two groups, 
autotrophic (bacteria only) and heterotrophic (all plants and animals), 
according as they are provided or not with symbionts. Whereas some 
symbionts are cultivatable, others have become so domesticated in 
respect to their hosts that they cannot be separated from them. The 
essential function of symbionts is to elaborate reserve substances so 
that they become assimilable to the host cell. The mitochondria that 
are present in all plant and animal cells, though not cultivatable, are, 
according to Portier, nothing but symbionts, the importance of their 
function having recently been i*evealed by Guillermond, Dubreuil, and 
others.* They are derived from food, and, if absent therefrom, illness 
supervenes, as shown by the bad effects of sterilised food, decorticated 
rice, &c. , causing deficiency diseases attributed to lack of vitamines, 
which, according to Portier, are nothing but symbionts. Where, as in 
Aphis, the animal feeds on plant sap that is filtered through a tube 
foiTned by tlo© insect's saliva — in other words, the insect imbibing food 
devoid of symbionts — the animal is of necessity provided with its own 
wtell-developed store of them. Portier applies his hypothesis to such 
varied prolalems as fecundation, parthenogenesis, tumor-formation, 
variation, and origin of species, in all of which mitochondria, that is, 
his supposed symbionts, play a part. His views aroused great con- 
troversy in France, so much so that it was thought necessary for the 
Society de Biologie de Paris (see O.E. Soc. Biol. LXXXITI., 654, 
May 8, 1920) to have a Committee examine the evidence. The Com- 
mittee, consisting on the one part of Portier and Bierry, and on the 
other of Martin and Marchoux (Institut Pasteur), by its report indicates 
the pitfalls, well known to bacteriologists, into which Portier was led, 
and thus disposes of the greater part of his far-reaching hypothesis. 
Nevertheless, like many exploded hypotheses, that of Portier has served 
a useful purpose through the discussion it has provoked and the interest 
in the subject ol symbiosis which it has stimulated. 

* Guillermond has shown that the mitochondria of the epidermal cells in 
Iris elaborates amyloplast and finally starch. Dubreuil (1913) found that 
mitochondria elaborate the fat in fat-cells. Other cytolosjists have shown that 
glandular secretions are similarly referable to mitochondria. 



The term ' symbiosis ' denotes a condition of conjoint life existing 
between different organisms that in a varying degree are benefited by 
tlie partnership. The tenxi ' symbiont, ' strictly speaking, applies 
equally to the partners; it has, however, come to be used also in a 
restricted sense as meaning the microscopic member or members of the 
partnership in contradistinction to the physically larger partners which 
are conveniently termed the ' hosts ' in conformity with parasitological 

The condition of life defined as symbiosis may be regarded as balancing 
between two extreuiea — complete immunity and deadly infective 
disease. A condition of perfect symbiosis or balance is realised with 
comparative rarity because of the many difficulties of its establishment 
in organisms that are either capable of living independently or are 
incapable of resisting the invasion of organisms imperfectly adapted to 
communal life. In these respects the conclusions of Bernard and 
Magrou in relation to plants apply equally to animals. It is difficult 
to imagine that symbiosis originated otherwise than through a pre- 
liminary stage of parasitism on the part of one or other of the associated 
organisms, the conflict between them in the course of time ending in 
mutual adaptation. It is, indeed, probable that some supposed sym- 
bionts may prove to be parasites on further investigation. 

In perfect symbiosis the associated organisms are completely 
adapted to a life in common. In parasitism the degree of adaptation 
varies greatly ; it may approach symbiotic conditions on the one hand, 
or range to vanishing point on the other by leading to the death of the 
organism that is invaded by a highly pathogenic animal or vegetable 
disease agent. There is no definite boundary between symbiosis and 
parasitism. The factors governing immunity from symbionts or para- 
sites are essentially the same. 

No final conclusions can as yet be reached regarding the function 
of symbionts in many invertebrate animals owing to our ignorance of 
the physiological processes in the associated organisms. The investiga- 
tion of these problems is one fraught with difficulties which we must 
hope will be surmounted. 

New knowledge is continually being acquired, and a glance into 
new and even recent publications shows that symbionts have been 
repeatedly seen and interpreted as mitochondria or chromidia. Thus 
in A-phis the long-known pseudovitellus has been shown to contain 
symbiotic yeasts by Pierantoni and Sulc, independently and almost 
simultaneously (1910) ; Buchner (1914) has demonstrated symbiotic 
luminiscent fungi in the previously well-studied pyrosomes, besides 
identifying (1921) as bacterial symbionts the mitochondria found by 
Strindberg (191.3) in his work on the embryology of ants. The increas- 
ing number of infective diseases of animals and plants, moreover, which 
have been traced, especially of )'ecent years, to apparently ulti'amicro- 
scopic organisms cannot but suggest that there may exist ultra- 
microscopic symbionts. 

From the foregoing summary of what is known to-dav of symbiosis 


we see that it is by no means so rare a phenomenon as was formerly 
supposed. Symbiosis occurs frequently among animals and plants, 
the symbionts (Algae, Fungi, Bacteria.) becoming in some cases per- 
manent intracellular inhabitants of their hosts, and at times being 
transmitted from host to host hereditarily. Among parasites, non- 
pathogenic and pathogenic, we know of cases wherein hereditary trans- 
mission occurs from host to host. 

It is evident that we are on the threshold of further discoveries. 
and that a wide field of fruitful research is open to those who enter 
upon it. In closing, it seems but fitting to express the hope that British 
workers may take a more active part in the elucidation of the interesting 
biological problems that lie before us in the study of symbiosis and the 
allied subject of parasitism. 

Aclmowledgnient. — I have pleasure in expressing my thanks to my 
colleague, Mr. David Keilin. for the very valuable aid he has given 
me in the preparation of this address. 






The most remarkable advances made by psychology during recent years 
consist in the rapid development of what threatens to become a. new and 
separate branch of science, the study of individual differences in mind. 
Down to the close of the nineteenth century psychologists were all 
pure psychologists. They confined themselves, with an air of chaste 
aloofness, to the discussion of mind m general ; they wrote and 
experim.ented solely on the abstract functions of consciousness as such. 
The varying eccentricities of minds in the concrete, how one man's con- 
sciousness might be unhke another's, were problems beneath their 
interest or beyond their ken. If, in some laboratoiy research, different 
pel-sons gave dissimilar reisults, either in the sharpness of their senses 
or the speed of their reactions, the divergencies \Aeie treated as no more 
thao unavoidable disturbances of measurement, vexatious errors to be 
eliminated by the method of averaging, not facts of special value to bo- 
examined in and for themselves. For the rest, the chief method of the 
psychologist was still introspection; and his chief subject, himself. 
Accordingly, although in this way he laid the necessary foundations of 
Si sound terminology and a safe technique, he nevertheless exposed him- 
self to the taunts of his literary colleagues, who knew that it takes all 
sorts to make a world. ' Les philosophes ' (laughs an early and un- 
orthodox observer) ' sont toujours trop occupes d'eux-memcs pour avoir 
le loisir dc penetrer ou de discerner les autres.' '■ 

Of late, however, a body of workers has arisen \\ho have turnrxl 
their attention more especially to the peculiarities of particular minds. 
The variations have attracted them more than the averages; and the 
mental disparities between childhood and age, between race and race, 
between one sex and tlie other, and between each unique individual and 
the rest, have formed their chosen topic. As a result of their labours, 
there has grown up, stop by step, a vast and miscellaneous accumulation 
of data wliich urgently demands to be sifted and systematised. The 
practical needs of applied psychology, in each of its fresh spheres — the 
■psychology of war, of edujcation, of industry, of mental disorder, defi- 
ciency and crime — all depend for their solution upon a sound doctrine of 
individual differences ; and their study in its turn has already contri- 
buted much welcome infomiation to the parent science. I propose, within 

1 La Bruyere, Les Curacteres (1687). 


the limits of the time allowed me, to attempt a summary of the chief 
problems and principles of this new branch; and, as methodically and 
as completely as is possible within so narrow a compass, to plot out the 
ground explored by recent work. 

Though the scientific study of individual minds is new, the popular 
interest in the practical issues has a long and venerable record; the 
ancient title of ' psychology ' is by comparison a woi'd of yesterday.' 
Time after time in the history of knowledge, the quack who has pandered 
to a. public want proves to have been the primitive precursor, the eai'liest 
avant-coureur, of what afterwards arrives as a respected and respectable 
science. Astrology was the foreiimner of astronomy, alchemy of chem- 
istry, and the lore of the bone-setter and the herbalist of modern surgery 
and medicine. In the same way the charlatan who reads your character 
from the lines on your hand or the bumps on your skull is caiTying on 
aJi antique tradition which embodies the first attempts at a psychology 
of individuals. He has seen the problem; he has met the demand; 
and, if his wares are sham and shoddy, he has at least thrown down a 
challenge to the slower and more sci-upulous disciple ol tnith. 

The blunders of pseudo-science, however, are never wholly unin- 
structive. Those who first practised I'art de connaitre les hommes — the 
physiognomists, the phrenologists, the palmists, and their successors — 
were all, in their crude and curious speculations, mainly guided, and 
mostly misled, by three fallacious assumptions. They looked for nothing 
but permanent and external signs ; they assumed nothing but constant 
connections between the outward and visible symptom and the inward 
and invisible state of mind ; and they classified both physical symptoms 
and mental qualities into arbitraiy and discrete types. Thus, your nose 
was either pointed or not pointed; and your temperament was either 
choleric or not choleric. If youi- nose was sharp, then your temper must 
be sharp as well ; for nasus acutus irascibiles notat. No graduations 
were recognised; no exceptions admitted. The correspondence was 
made perfect and invariable. Indeed, if the classes were not clear-cut, 
if the symptoms were not patent to superficial inspection, and if the con- 
nections between the two were not absolute and unifonn, how could 
there be any inference, any prediction, any science of whatever sort? 
The soul, sui-ely, must be a riddle which could never be read. 

The difficulty was solved by the discovery of a new technique. And 
this we owe to an original English thinker of the latter half of the nine- 
teenth century. Sir Francis Galton. To the general public, Galton is 
best known by his demonstration of the hereditary factors in individual 
genius — a doctrine that in his own person lie so remarkably exemplified. 

' I suppose tha earliest written recognition of the power of judging the 
quality of the mind from observable characteristics is to be found in the words 
of Nestor to the unknown Telemachus : ' By certain signs that I discern upon 
thy face, illustrious youth, I recognise what man thou art. Thy countenance 
is "proud and generous, thine eloquence great, and thy reasoning recalls to me 
thy father. What manner of youth could such a one as thou be, were he 
not the offspring of the great Ulysses? ' Homer. Odyssey, xi., 693. Those who 
care to trace the historical development of individual psychology will find most 
of the necessary materials and references collected in Mantegazza's Physiognomy 
and Ex2nes.shn' {V.)0'i] and Stern's Difft'renfieJIe PsyrJwlogie (1911). 


But his most fruitful contribution lay in the development of two tech- 
nical methods of inquiry, the statistical method of correlation, and the 
experimental method of psychological tests. These in turn rest upon a 
fundamental assumption, which i-ecent w^ork has verified — the con- 
tinuity of mental variation. Here stands the keystone of individual 
psychology as a science. The differences between one man and another 
are always (we shall find) a matter of ' more or less ' — seldom, if ever, 
a question of presence or absence, of ' all or none.' 

' Viiiuous and vicious ev'ry man must be, 
Few in tli' extreme, but all in a degi'ee.' ^ 
There are, in fact, no such things as mental types; there are only mental 
tendencies. And it becomes the main task of individual psychology, 
first, to catalogue and classify all the tendencies to be surveyed, and then 
to devise a method for the quantitative assessment of each. 

It follows from this initial postulate that the mind of eveiy individual 
has the same underlying structure. Men's minds are like their faces. 
Each seems at first unique. But patient analysis shows that the 
real component features are in every one the same. All have two eyes, 
two ears, a mouth, a forehead, and a nose. But the length, the width., 
and the prominence of each part may differ infinitely from man to man. 
Our business is thus tO' calculate the extent tO' which each known 
potentiality has been de'S'eloped or contracted, much as a surveyor marks 
down, at given stations upon his map, the eminences and depressions 
of the land. 

The Psychographic Scheme. 

Since the mental ground-plan is in all persons approximately the 
same, the same inventory of mental tendencies will serve, no matter 
which particular person we are about to analyse. An identical set 
of questions may be asked about each. An identical series of headings 
will recm' in our reports. Were our psychological catalogue exhaustive 
and complete, it would, in theory, be necessary only to measure in 
succession each particular capacity ; and so obtain a clear and quanti- 
tative specification of the idiosyncrasy of each individual. 

This view is more than a mere dogmatic postulate. It is confirmed 
by a close comparison of the literature in different psychological fields. 
It will be discovered that, whatever the nature of the case to be ex- 
amined — mental deficiency or supernoi'mal talent, educational back- 
wardness or vocational misfit, nem'otic disorder or propensity to crime 
— practical experience has forced each examining psychologist to work 
out very much the same main heads of inquiry as his colleagues in 
other lines. Such a working schedule ol mental characteristics may 
be termed a ' psychographic scheme.' The scheme that I shall follow 
here will be^ onei which I have found reappearing as a basis for my 
note-taking in investigating individuals in each of the foregoing groups, 
lu its broadest outlines every personal examination should pursue 
two chief directions: first, a retruspeclive inquiry into the past history 
of the person studied; and, secondly, what I niay call a conspective 

' Pope, Essaij on Man, 231. 


survey of his mental condition at the present tune. Viewing his whole 
life's story as a growing tree with ramifying roots and boughs, we 
take, as it were, first, a longitudinal section, and then one or more 
cross -sections, of the main trunk. 

I. Case-Histvry. 

The liistorical reta-ospect should embrace, first of all, a -personal 
history, based upon reports supplied by parents, teachers, and medical 
attendants, and reviewing such developmental features as conditions 
of birth, mental and bodily growth, past physical ailments, and early 
mental shocks and disorders, and general moral and intellectual pro- 
gress both at home and at school. 

The procedure of the modern psycho-analyst consists in little more 
than the taking of an elaborate mental case-history by means of a 
special technique. The discovery of early repressions and infantile 
complexes often sheds a bright flood of light upon the present mental 
make-up of an adult pei'son. Think, for example, what numerous 
characteristics may be explained when it is reported that a neurotic 
bachelor of thirty was the only son of his mother, and that she was 
a widow. Mill, who in this country was the first to raise the science 
of character to a level of philosophical respectability, regarded 
'ethology,' as he named it, as consisting principally in the deduction 
of present mental features from past encircling influences. 

But the inquiring psychologist must go further back still. He must 
jiass behind birth to ancestry; and to the jjersonal history of his subject 
prefix an account (where he can get it) of the family history. Here 
he obeys the lead of Galton rather than the logic of Mill ; and is seeking, 
by a. study of pedigrees, to infer the presence of hereditary factors. 
Of these the ultimate significance will he pi-esently apparent. 

n. Personal Examination. 

^Yhat• I have termed taking a cross-section must include an exami- 
nation of the person's present condition by the two chief instniments 
of all scientific inquiry — namely, observation and experiment. By 
whichever method they are reached the facts established will be brought 
together synoptically under a convenient system of tabulated heads. 
These headings will embrace external conditions as well as internal, and 
physical conditions as well as mental. 

A. Environment. 

The psychologist must never be content to look at nothing but the 
mind before him. It is his task to extend his survey to the surroimding 
influences that are making that mind what it is ; lie must ascertain the 
current situations and the crucial pi-oblems wliich that mind is called 
upon to meet. To study a mind without knowing its viiVwu is to study 
fishes without seeing water. 

Accordingly, as he turns from the past to the present, the human 
naturalist will commence with a review of the pereon's present environ- 
ment, of his material, physical, and moral circumstances, at home, at 
school, and at business. Eecent research upon milder abnormal states 




—particularly delinquency and neurosis — has shown very clearly that 
none of these is due exclusively to inborn constitution, nor yet entirely 
to shocks and mental traumata in the remote or immediate past ; they 
spring largely out of contemporaneous conditions and conflicts. Even 
with the noi-mal individual, simply to learn in what social class he 
moves, or in what city or street he lives, is to divine very plausibly the 
chief of his guiding habits and ideas — his code, his creed, and his 
customs. Strange persons are like strange words : their intentions 
are best guessed from their context. One incidental item of practical 
import rises to the surface in most of these investigations. Of all 
external factors home influences are paramount ; moral influonces are 
far more powerful tlian material, emotional than intellectual. With- 
out a knowledge of the emotional attitudes elicited in a person by the 
attitude of his parents, of his various relatives, and of others in daily 
contact with him, his standpoint towards life can never be properly 
envisaged or explained. 

B. Personality. 
1. — Physical Condition. 

Turning from the environment to the personality proper, from the 
f?6lbting to the gem, iti is essential to glance fu'sb at physical conditions 
before we pass to psychological ; to see what is reflected on the surface 
before we hold the centre to the light. That a man's body has a pro- 
found influence upon his mind has been realised in every age. But 
we are only just beginning to discover in definite detail how certain 
physical states and certain physical dlsoi'ders' are attended 'ny rortain 
psychical effects. 

Once more it is in pathology — w here more or less morbid conditions 
of body produce more or less morbid conditions of mind — that the most 
convincing instances are to be sc-en. At present, it is tnie, the ten- 
dency in the newer schools of psychology is to trace mental derange- 
ments, particularly in their milder forms, almost exclusively to mental 
origins. But those who deal daily with young children, where the 
causal factors can be more readily um-avelled, find it impossible to over- 
look the co-operation of such purely physical conditions as rheumatism, 
chronic catan-h, nasal obstruction in numerous forms, minor lesions of 
the brain, or the absorption of toxines from internal foci or superficial 

The study of juvenile delinquency shows, in most unexiiected direc- 
tions, the influence of physique upon character. Anvtliing that weakens 
physical health tends to weaken self-control. Anything that conduces 
to physical irritation tends to set up a mood of mental irritability. A 
holiday in the country is sometimes the best cure for crime. With 
the intellectually subnormal the efficacy of simple physical remedies is 
quite as striking as with those who are subnormal in character or tem- 
perament. The provision of spectacles, the extraction of teeth, the 
extirpation of tonsils and adenoid-growths, measures in themselves 
comparatively trifling, have often converted an alleged mental defective 
into a normal or nearly normal child. 


Of all the physical influences studied in recent years the most 
striking is that of the ductless glands * Every layman knows that 
thyroid insufficiency produces a cretinous type of mental defect, and 
that such, defect may be cured or alleviated by the administration of 
glandular extracts. And just as thyroid insufficiency depresses, so 
thyroid excess may heighten, emotional states and reactions. Of other 
glands belonging to this class — the pituitaiT, the adrenal, and the sex 
glands — we know far less. But recent work upon their internal secre- 
tions Has left no doubt as to their power over temperament and feeHngs. 
Shall we some day, when biochemistry is sufficiently advanced, be able 
to analyse the minute components of lymph, and blood, and diagnose 
from the chemical constitution of small samples whether a man is over- 
sexed, or easily fatigued, timorous, excitable, or blessed with high 
vitality ? 

The work upon these endocrine organs seems destined at length to 
provide a scientific basis for the doctrine of physical signs — the tradi- 
tion so dear to the popular mind-readers of every place and time. The 
physical signs recommended for inspection are of two kinds : thev refer 
either to the physique as a whole, or more specifically to the face or 

The ductless glands are closely connected with bodv metabolism as 
a whole. We seem hei-e to find an unexpected confirmation of the 
popular division of ' temperaments ' or ' constitutions ' into two or 
three chief types. The loose terms in vogue are, for the two extremes, 
' nutritional ' or ' vital," and ' nervous ' or ' mental ' ; and. for the inter- 
mediate, 'motive,' 'muscular,' or 'mixed.' ^ Three American physio- 
losrists — Brvant, Goldthwait, and Dunham — whose observations on this 
point are more careful than most, quaintly term the triad ' herbivorous,' 
'carnivorous,' and 'omnivorous' respectively, thus claiming a some- 
what speculative biological derivation for the supposed differences in 
digestion, metabolism, and general manner of life.'' Three Italian 
physiologists, Viola, Naccarati. and De Giovanni, term the two 
extremes— the Hamlets and the Falstaffs of the psychological caste — 
microsplanchnic and macrosplanchnic respectively, or fin language less 
technical but more Shakespearean) little -Mlied and bie-bellied. By 
means of careful statistical correlations thev have tried to prove that 
the ratio of height to weight, or better of limbs to trunk, mav be taken 
as a trustworthy index of the so-called 'morphological type,' and is 

* It is unfortunate for the general reader that the onlv systematic and non- 
technical account of the subject is the somewhat uncritical hook by Dr. Berman 
on The Glands Begulating Personality, a work as full of ingenious speculations 
as it is devoid of documented references. 

^ This threefold division is found in most phienoloeical handbooks. Of 
these the least iinscientific is Dr. Bernard Hollander's Scientific Plirenoloqy 
(a title which is something of a contradictin In adjcctiro) : see pn. 38-48). The 
distinction, in its modern form, seems to have originated with Dr. Alexander 
Walker, a Lecturer on Anatomy at Edinburgh Universitv. and contemporary 
of the English phrenologist Combe. It will be observed that the dichotomy 
is anparently a simnlification of the fourfold classification of temperaments, 
originating with Galen (a.d. 130). 

' For a, convenient summary of the American literature see Lewis, 
' Adolescent Physical Types.' Fed. Scm.. 1916. xxiii.. 3. 


demonstraBly associated with tested mental differences.' Fat and lean 
is an antithesis as old as the legend of Jack Spratt and his wife ; and 
modern physiology, it will be noted, agrees with the ancient rhyme in 
referring the difference largely to dietetic habits, and in connecting it 
in part with a difference in sex and the sex-glands. As to the con- 
comitant psychical differences, fancies on this subject (if Plutarch is to 
be trusted) were entei-tained by so eminent a master of men as Julius 
Caesar.' 'Your fat, sleek-headed men,' he is made to exclaim, 'I 
never reck of; they sleep o' nights. But these pale-visaged carrion, 
with the lean and hungry look, they think too much ; such men are 
dangerous.' That the new observers have confirmed the old is 
more than I venture to assert. But at least they have applied the 
proper method to the problem. 

Of their somewhat singular conclusions the real import lies in this : 
they emphasise, and justly emphasise, the supreme importance, for 
right psychological diagnosis, of viewing body and mind as a single 
unitaiy organism. A man is something more than a carcass loosely 
coupled with a ghost. Material and spiritual are reciprocally involved ; 
and the two together are to be treated as inseparable aspects of one 
hi'ghly complex whole. Thus, in both physical and mental working, 
the restless, unreliable, ' carnivorous ' type may be likened to a high- 
compression engine, capable of short but forcible output of energy, yet 
Tmsuited for long and steady running ; the plodding, sedentary, * herbi- 
vorous ' type, to a low-compression engine, with a lower maximum 
efficiency, but a more continuous level of sustained activity. And in 
each the mental and physical symptoms are joint products of one 
fundamental mechnnism. It will be remarked in passinij that, alike 
in mind and body, the formei- — the slender ' microsplanchnic ' type — ■ 
is suggestive of hyperthyroidism, and of the tall, long-headed, active 
races ; while the latter — the heavy ' macrosplanchnic ' type — is simi- 
larly suggestive of Rypothyroidisiri, and of the short, round-headed, 
stolid race. 

Possibly the sanie twofold hypothesis — of racial stock and glandular 
influences — may be adduced to explain what little correlations the 
nhrenologist ° can claim between mental characteristics and the con- 
formation of skull and face. The appearance of cranial types is cer- 
tainly suggestive of what is known of racial stocks. The doctrine of 
stigmata of degeneration also finds a partial explanation in the double 
effects of disturbances in the ductless grlonds, impairingr simultaneously 
the normal development of both skeleton and intelligence. Low, 
narrow, and bossed foreheads, broad, depressed, and upturned noses, 
narrow, high, and V-sfiaped palates, lobeless, projecting, and mal- 
formed ears, asymmetrical, misshapen, and small skulls — these 

^ See Naccarati, 'The Morphological Aspect of Intelligence,' Arch. Psych., 
No. 4.'5. 1921. The coefficients are low. .3.'5 or less. 

' The remark is freely paraplirasncl hv Sliakespeare, .Ti/llii.i CfrKor, I., ii.. ]9l. 

• Psychologists will be a.stonished to hear that in spite of all the recent work 
on intelligence-tests, one British Education Authority recently preferred to invite 
a practising phrenologist to assist in the examination of candidates for junior 
county scholarships. How many school medical officers still rely, in diagnosing 
mental deficiency, more npon stigmata than tests ? 


anatomical disfigurements were, until recently, the chief signs reUed 
upon in the diagnosis of mental defect. They are best seen in the 
rarer cUnical types of imbecility, in the mongol and the cretin, who, 
as already remarked, seem to suffer primarily from a deficiency of 
endocrine secretions.'" 

So far, it may be thought, bodily indications are of value only in 
cases of extreme pathological deviation — the obese, the emaciated, and 
the physically deformed; they are symptoms for the doctor, not signs 
for the plain man. Is there, then — 

' ... no art 
To find the mind's construction in the face '? ^^ 
And, if not, why do so many men and women of the world claim to 
divine character at a glance, and profess, on the basis of a firsit impres- 
sion and a short superficial inspection, to gauge intelligence and tem- 
perament, even among their normal fellow-creatures, with much the 
same exactitude which is conceded to the dog-fancier, the sheep-dealer, 
and the fellow with an eye for horseflesh in their somewhat lowlier 
spheres? That their intuitions (as they term them) often correlate 
highly with independent and trustworthy estimates has been shown 
statistically time after time. Upon what do they rely? Is there a 
sort of moral clairvoyance confined only to a gifted few? Or is the 
miracle of insight into another, a knack that each can achieve? In 
part these judges of men are aided, more than they themselves suspect, 
by semi-social criteria — accent, phraseology, mannei-s, the elegance 
of handwriting, and the tidiness of clothes. Stevenson, you will 
remember, has doclored ihafi ' an undoubted power of diagnosis i-osts 
with the practised Umbrella -philosopher; for, whereas a face is given 
us ready-made, each umbrella is selected from a shopful as being most 
consonant with the purchaser's disposition.' '" And other interviewei's, 
besides Sherlock Holmes, draw unpalatable inferences from our taste 
in hats, and socks, and coloured ties. For the rest, so far as their 
procedure is unprejudiced by pseudo-scientific reading, it seems to 
depend chiefly upon inferences, conscious or unconscious, not so much 
from bodily structure or build, as from bodily posture and movement, 
particularly the finer movements of the hand, of the eye, of the lips 
and mouth, and of the vocal organs in speech. And the principle is 
sound. If you are buying anything tliat works you ask first to see it 
working, be it only for a second, and only as a sample. So with the 
connoisseur of human creatures, it is function rather than fi'amework 
that should count. In the face, it is not the hard, immutable gristle 
and bone, but the soft and mobile mask of muscle that the sound 

1" ;\Iaiiy of the so-called stigmata, however, together witli the mental duliiess 
they are supposed to signify, are largely attributable to petty ailments of early 
childhood — rickets, chronic respiratory catarrh, and nasal obstruction from 
adenoid growths. 

"1 Macbeth, I., iv., 12. 

" College Papers, iv., 'The Philosophy of Umbrellas.' As to handwriting, 
those who smile at the claims of the grapliologist may be reminded that Binet, 
and^ many experimentalists and pathologists since, have not scorned to look for 
indications of character and mental derangement in the size, and shape, and 
steadiness of the letters we trace with the pen. 


physiognomist observes. The neuro-muscular tonus — the tightness 
around the eyeHds, the firmness of the Ups — is an index of the general 
state of health and vitality upon which a man's intelligence and atten- 
tion so much depend. The changes of look and glance afford a clue, 
however indirect, to the range, the liveliness, and even the character 
of his interests. Above all, it is to be remembei'ed, almost every human 
emotion has its instinctive facial expression, to which, by a sort of 
primitive sympathy, we ourselves as instinctively respond. The 
emotions (we shall see) are the foundations of character. And the 
emotional mood that predominates in a given person's life tends, by the 
simple law of habit, to leave its natural expression stamped upon the 
countenance, contracting almost peiTnanently the luiderlying muscles, 
and deepening the furrows and the finer lines upon the skin. Thus 
the bad-tempered bully comes to wear always a more or less angry 
scowl, and the anxious melancholic a worried look upon the brow." 
' In many's look the' false heart's history 
Is writ, in moods, and frowns, and wrinkles strange.''* 
In the main, however, the gist of recent scientific work on connec- 
tions between body and mind has been, from a practical though not 
from a theoretical standpoint, negative. Theories, such as that of 
Lombroso and his school — the notion of criminal, defective, neurotic, 
and supernormal types, each marked off from ordinary mankind by a 
specific combination of physical and mental traits — have been exploded 
by more careful statistical methods. The measurable correlations, 
though frequently positive, are almost always too slight to be trusted 
for the needs of diagnosis.'^ Thus a man's exterior is sometimes 
suggestive, but never conclusive. And so we reach the safe and central 
maxim of individual psychology of to-day: Judge mental functions by 
mental symptoms, not by physical. The worldly moralist agrees. ' 11 
ne fauti pas juger des hommes comme d'un tableau ou d'une vache ; 
il y a un interieur et un cceur qu'il faut toujours approfondir. ' " 

2. — Mental Condition. 

I proceed now to what consequently becomes the essential duty of 
the practical psychologist — the direct examination of the mental state. 

The positive foundations for a practical psychology of individual 
differences have been laid in three broad generalisations, each the 
separate suggestion of recent experimental work. They consist in 
a trio of important distinctions, the distinction between intellectual 
and emotional characteristics, between inborn and acquired mental 

*' These deductions can be verified by the method of correlation, see Child 
Study, June 1919, ' Facial Expression as an Index of Mentality ' ; also Langfeld, 
'Judgments of Emotions from Facial Expression,' .7. Afm. P.sych., xiii., 172, 
and Psych. Rev., xxv.. 488. The general principle underlying 'whatever truth 
the so-called science of physiognomy may contain ' is stated, as in the text, by 
Darwin, Expression of Emotions in Man and Animals, p. 388. 

'* Shakespeare, Sonnets, xciii. 

'* The labours of Karl Pearson and his students, following the methods of 
Galton, have been invaluable in this field. Goring's study of The En(jU.''h 
Convict is a model for inquiries upon these and kindred problems. 

•* La Rochefoucauld, Maximes Morales, cccxvii. 
1923 B 


tendencies, and between special and general capacities. Upon these 
three distinctions the essential portion of my ' psychographic scheme ' 
is based. The evidence for them, as yet presumptive rather than 
complete, I can but briefly touch upon in the appropriate place. 

a. — Intellectual Characteristics. 

With these distinctions, then, to mark our working rubrics, we 
begin by viewing any particular mind, that comes for valuation, as pre- 
senting two distinguishable aspects, the intellectual on the one side, 
and the emotional on the other. The divorce of vou; from 601x6.; is 
as old as Pythagoras. 

' Two principles in human nature reign ; 
Passion to urge, and reason to restrain.' 
The modern antithesis is something more than a convenient revival of 
the traditional contrast. It has a basis in recent statistical work." 
If a large group of individuals be ranked in order for all the psycho- 
logical characteristics that can be conceived, or at least conveniently 
estimated, and if the correlations between the several rankings, each 
with each, ]ye then computed, two striking facts are instantly perceived. 
First, nearly all the correlations are positive; excellence in one respect 
tends, on the average and in the long run, to go hand in hand with 
excellence in every other. But, secondly, the closeness of this corre- 
spondence varies suggestively in diffei-ent directions. Intellectual quali- 
ties are correlated fairly highly amongst themselves. Emotional qualities 
(so far as the more meagre evidence at present shows) are likewise corre- 
lated to nearly the same considei'able degree. But the correlations 
between intellectual qualities on the one hand and emotional on the 
other, though still as a rule positive, are by comparison conspicuously 
low. "We are warranted, therefore, in assuming that these two aspects 
are relatively independent, and in studying them separately and in 

i. Inborn Abilities. 

We proceed then to estimate, in the first place, the examinee's 
qualities of intellect. And here our second subdivision introduces 
itself — the distinction between what is inborn and what is acquired. 
Many independent researches agree in showing that intellectual charac- 
teristics are hereditary, and that to much the same extent as physical. 
Even if a capacity (or, more strictly, the strength of a capacity) be 
not hereditary, it may still be congenitally determined. What is 
inherited is necessarily inborn; but what is inborn is not necessarily 
inherited. In the latter case, however, to separate endowment from 
acquirement, mental capital from mental earnings, is a more pre- 
carious task. The discrimination, wherever it is possible, is of the 
greatest practical moment. If a child, for example, proves to be 
exceedingly backward in school work it is essential to decide whether 
this backwardness is a legacy from backward ancestors, or merely an 

^" See. amongst other studies. Webb. ' Character and Intelligence,' Brit. J. 
Psych. Mon., I. 


accidental consequence of conditions subsequent to birth. In the 
former case the backwardness, being inherent, is therefore incurable; 
in the latter, there remains at least a hope that, by amending the un- 
favourable circumstances, the backwardness may be partly remedied 
or even wholly removed. 

a. General Intelligence. 

We have now narrowed our scope for the moment to qualities that 
are intellectual and a,t the same time inborn ; at this point we may 
apply our third and last distinction. Inborn intellectual abilities are 
divisible, first, into a single central capacity, pervading all that we say 
or think or do; and, secondly, into a series of specific abilities, each 
entering only into processes of a more or less limited kind. 

For the existence of general inborn intellectual ability (known briefly 
as ' intelligence ') the statistical evidence is now pretty decisive. Even 
the critics of this so-called central factor no longer deny that, at least as 
a matter of mathematical interpretation, the empirical data may be 
formulated in these tei-ms ; and that this formulation, whatever its 
ultimate psychological explanation, is of the greatest value in practice, 
and, as a working hypothesis, works very well. 

If further proof were demanded, the indubitable success of intelli- 
gence-testing has supplied a widespread verification, sufficiently 
business-like to convince the plain man. Indeed, over the whole realm 
of mental science the outstanding feat of recent years has been the 
application and the multiplication of innumerable tests for measuring 
general ability. As everybody knows, during the War the intelligence 
of nearly two million recruits was tested by these means for the Army 
of the United States. And this spectacular achievement has probably 
bestowed on the practical applications of psychological methods a 
stronger impetus than any other single piece of work. 

Since intelligence, as we have defined it,^* is an inborn quantity, 
the amount possessed by a given individual should, in theory, remain 
constant through all the years of his life. It should thus be possible 
to predict, from quite an early age, what will be the probable intel- 
lectual level of a child when he is grown up. Within reasonable limits 
such forecasts can, in fact, be made. Numerous investigations have 
shown that what is called the ' mental ratio ' — the proportion, that is, 
between a child's mental age and his chronological age — tends to keep 
tolerably uniform throughout the years of growth. Hence it is safe 
to prophesy that a child (for example), aged five by the calendar, with 
a mental age of two (and a mental ratio, therefore, of J = 40 per cent.), 
will probably attain a mental age of four at the age of ten, and a mental 

'' The reader will understand that intelligence in this sense is not to be 
conceived as a concrete organ, entity, or power, but a purely abstract poten- 
tiality — like electrical energy or heat as conceived by the physicist — an entirely 
hypothetical quantity, postulated and defined, like most other scientific concepts, 
for the convenience of separate measurement. It is to be distinguished from 
manifested intelligence (the materialisation, as it were, of that abstract poten- 
tiality), which develops during childhood and decays with loss of health or 
advance of age, and is measurable in terms of mental years or of some more 
concrete unit, 

B 2 


age of six at the age of fifteen. Since beyond the stage of puberty 
inborn inteUigence does not develop to an appreciable extent (another 
startling paradox of psychological testing), such a person will never 
rise above the six-year level, and will remain mentally defective for 
the rest of his life. 

From the numerous results obtained from the widespread employ- 
ment of intelligence-scales, one fact of deep social significance emerges — 
the vast range of innate individual differences. A famous clause in the 
American Declaration of Independence proclaims that ' all men are 
created equal. ' In the psychological sense as distinct from the political, 
not only are men created unequal, but the extent of the inequality sur- 
passes anything before conjectured. In a survey carried out upon all the 
children in a representative London borough — a census covering more 
than 30,000 cases — it was found that, within the elementary schools, 
the mental ratios might vary from below 50 per cent, to above 150 per 
cent. ; that is to say, the brightest child at the age of ten had the mental 
level of an average child of fifteen, while the dullest had the mental 
level of a little child of only five.'' 

Over tliis vast scale the distribution of intelligence is neither flat 
nor yet irregular; it follows a simple mathematical law. Its frequency 
conforms to the so-called ' normal curve, ' and the abnormal and defec- 
tive are found to constitute no isolated types, but to be simply the tail- 
end of a chance distribution. Probably all or most of our mental capa- 
cities are distributed in the same fashion. This fact, if it be a fact, 
greatly simplifies the problem of mental measurement. It should be a 
recognised maxim of procedure to measure people, not by arbitrary 
marks between a conventional zero and an equally conventional maxi- 
mum, but by the degree of divergence above or below the average or 
middle line (much as we measure the depth of the ocean or the altitude 
of the hills from the intervening sea-level), the divergence being calcu- 
lated in terms of the standard deviation. This is a technical hint of 
special value in estimating quahties that lend themselves to no obvious 
quantitative units like mental ages or additive marks. 

Since variations in intelligence are so wide and so continuous, it 
becomes convenient to divide the entire population into about six or 
eight separate classes or layers. A classification of this kind, worked 
out empirically, for children, is already implicitly embodied in the 
organisation of our various schools. A second classification can be 
drawn up, on an analogous basis, for adults, and will be found, in the 
main, to reflect the amount of difficulty and responsibility entailed by 
their several occupations. It is interesting to find that the proportionate 
number of individuals falling into the parallel sections tallies pretty 
closely both for adults and for children (see Table T).^° Here, there- 
fore, lies a simple aim alike for educational administration and for 

i» The Distribvtion and Relations of Educational Abilities (London County 
Council Reports, 1917). Mental and Scholastic Tests (London County Council 
Reports, 1922). 

"" Compiled partly from data published in the L.C.C. Reports {loc. cif. xup.). 
and partly from a table recently included in a paper on The Princivhs of 
Vocational Guidance (Vllth Int. Congr. Psych.. 1923). The figures and categories 
given in the present table are round approximations only. 







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vocational guidance. It is the duty of the community, fii'st, to ascertain 
what is the mental level o£ each individual child; then, to give him the 
education most appropriate to his level; and, lastly, befoz'e it leaves 
him, to guide him into the cai-eer for which his measure of intelligence 
has marked him out. 

Of this programme, the educational part is already in execution. 
For the lowest section, the mentally deficient, we have begun to provide 
special schools and residential homes ; and, thanks to the advances of 
individual psychology, the means of diagnosis are now exact and just. 
There is a similar but newer movement towards the institution of special 
classes for the dull and backward. It is from this larger horde of 
moderate dullards, not from the tiny sprinkhng of the definitely defective, 
that the bulk of our inefficient adults — criminals, paupers, mendicants, 
and the great army of the unemployable — are ultimately derived. Nor 
will it do to confine official assistance solely to the inferior groups. The 
supernormal should also enjoy a special measure of care and treatment. 
Much is done for them by awarding free places at central and secondary 
schools. But both the methods for detecting them and the opportunities 
for educating them still admit of much improvement. Already in several 
foreign countries schools have been established for Begabte Kinder. In 
Berlin, the brightest children from the whole of the city are selected by 
means of psychological tests, and brought together at an early age to a 
special centre for individual supei'vision and training. 

The determination of intelligence is equally indispensable for proper 
vocational guidance. Eespecting intelligence, indeed, vocational psycho- 
logists seem unanimous that, as it is the easiest, so also it is the first and 
foremost factor to be tested. The worst misfits arise, not from forcing 
round pegs into square holes, but from placing large pegs in little holes, 
and small pegs in holes too big for them to fill. We have already seen 
that different occupational groups have different intellectual levels. For 
nearly every type of employment there exists a certain minimum of 
intelligence, below which a man is pretty sure to fail. For many, if not 
most, there is also, in all probability, an optimal upper limit. Just 
as some men are too dull for their jobs, so others are too clever. Hence, 
in the interests of the employer and of the employment, as well as of 
the emploj^ee and the general community, it is a blunder always to pick 
the brightest candidate who applies for a given job. 

In this country, for the purposes of vocational selection, the most 
extensive application of intelligence-testing has been the introduction 
of a psychological ' group-test ' into recent Civil Service examinations. 
The papers, comprising five or six graded speed-tests of well-known 
types, have been drawn up, after experimentation, by professional 
psychologists. Some 40,000 candidates have been tested in this way. 
And the calculated correlations demonstrate that the results of the new 
methods agree, both with the total marks from the whole examination 
and with subsequent reports on office-efficiency I'eceived fi'om Govern- 
ment departments, more closely than any other single paper set. 

Incidentally, the extensive data so secured ratify conclusions reached 
in other countries and by different means — namely, that the range of 
intelligence among adults is quite as wide as that observed among 



children, that the average level of inborn intelligence among adults 
aged twenty to fifty is but little above that of children of fourteen, and 
that the distribution of intelligence, among adults as among children, 
approaches pretty closely to the so-called ' normal curve.' (See fig. 1, 
which shows the distribution of marks in the intelligence-tests set at 
the last Civil Service examination — Clerical Class, 1922.) 

Number op 







Distribution of Intelligence. 

8599 ADULTS. 

(Civil Service Examination — July 1922. 

10 20 ho 40 M 60 70 80 «t) UW 110 120 150 140 ISO 160 170 l£0 190 ;00 

Scale of Harks. 

FIG. 1. 


p. Specific Abilities. 

With individual differences in genei'al intelligence I have dealt at 
disproportionate length, partly because intelligence is, in Galton's 
phrase, a human quality of the utmost ' civic worth, ' and partly because 
it is the one mental capacity upon which a prolonged and concentrated 
study has been focussed. 

Over specific inborn abilities I need not linger. For them effective 
tests have proved disconcertingly hard to contrive. Simple correlation 
is here inapplicable. General intelligence is always getting in our way. 
We think we have tested something specific. We find we have only 
hit upon another test of intelligence. Its ubiquitous influence can only 
be eliminated by some elaborate technical device, the procedure, f©r 
example, known as multiple correlation; and the complexity of the 
whole task bewilders even where it does not baffle. 

Nor do these special abilities, although pi-esumably inborn, declare 
themselves at so young an age as the more general. Specialisation 
during the first twelve years of childhood is the exception rather than 
the rule. 'Young turtle,' says Epicurus, ' is every kind of meat in 
one — fish, fowl, pork, and venison; but old turtle is just plain turtle.' 
Similarly, the young child contains in fresh and dormant essence the 
germ of every faculty. Age alone betrays our idiosyncrasies. 
Adolescence is pre-eminently the period when many of these localised 
talents and specialised interests seem for the first time to mature. 
Accordingly, efforts at vocational guidance and educational specialisation 
must not be forced at too early a stage. At present, for example, the 
system of junior county scholarships tends to sweep all our brightest 
children at the age of ten or eleven into secondary schools of a some- 
what academic type. When at a later period examinations are held for 
trade schools, most of the best instances of special talent are missing: 
they have already been creamed off and drafted into other directions less 
suited to their powers. 

So far as it has been successful, the results of multiple correlation, 
eked out by other scattered indications, point to the following abilities 
as depending upon factors relatively specific: arithmetical, manual 
(drawing, wi'iting, probably handwork of simpler kinds), verbal (reading 
and spelling), literary (composition in one's own tongue), linguistic 
(learning foreign languages), artistic, and musical, the last often appear- 
ing at an unusually early age. Of such specific or ' group ' factors 
the specificity is not complete. There is much overlap ; and, with every 
one of them, it is extremely hard to frame tests which depend mainly 
for success neither upon the ' central factor ' of general intelligence, nor 
yet upon some particular capacity, so limited and local that no inference 
can be made from one performance to another, even within the same 
presumable group. 

The abilities just enumerated seem undoubtedly specialised. But 
how far are they inborn ? In practice what is actually tested must turn 
largely upon acquired dexterity, knowledge, and interest. And acquire- 
ments (as the classical experiments on formal training have taught us) 
te>nd always to be circumscribed; they do not diffuse or spread. The 


old doctrine of native faculties is out of favour with the orthodox psycho- 
logist of to-day. We arc told that there is no such thing as memory : 
there are only memories ; that there is no such thing as a general power 
of muscular skill : there are only separate motor habits, each inde- 
pendently learnt. Nevertheless, the very way in which such acquire- 
ments are limited, particularly among individuals who have had iden- 
tical opportunities at school and at home, argues an innate basis; and 
inquiries into heredity confirm the suspicion. On the existence and 
nature, therefore, of these hypothetical ' group-factors ' — inborn powers 
that seem partly general but not entirely so, partly specific but not abso- 
lutely so— further research is imperatively needed. How far, for 
example, is there a group-factor underlying all kinds of memory, or all 
kinds of imagination, every form of mental quickness, every form of 
motor dexterity, and every form of apprehension through the several 
senses? Of the great difficulty of the problem, the prolonged work 
on mental imageiy is an excellent example. The early experiments of 
Galton convinced contemporary psychologists that individuals might be 
classified into fairly definite types — the eye-minded, the ear-minded, 
the motor-minded, and so forth. That these sharp lines of demarcation 
can be no longer drawn has since been amply proved. But yet, in 
spite of countless inquiries, no satisfactory tests have been devised even 
for a capacity so clearly definable as visualisation; nor can we guess 
how far it may be specific, and how far it may be inborn, nor 
how far it is a manifestation of something more general, or how far it 
is simply a question-begging term for an aggregate of yet more limited 
habits or tendencies, each specific in itself.^' 

ii. Acquired Attainments. 

I turn now from inborn abilities to those that are acquired. From 
a practical standpoint these may be broadly grouped into educational 
attainments and vocational attainments respectively. 

For the teacher one of the most helpful achievements of experimental 
psychology has been the recent elaboration of standardised scholastic 
tests. Simple foot-rules have been scientifically constructed for measur- 
ing a child's knowledge of the chief school subjects — reading, spelling, 
arithmetic, handwriting, drawing, composition, and the like. By the 
help of such age-scales — those, for example, published by the London 
County Council — it is now practicable to assign, in the space of a few 

-* To hereditary differences of race, sex, and social class I have no space 
to allude. The main conclusion that can be drawn from experimental work is, 
I think, the following : Innate group-differences exist : but they are small. 
Training and tradition account for the more conspicuous. The inborn mental 
differences between class and class, between nation and nation, and between 
women and men, taken on the average and in the gross, are swamped by the far 
wider differences among the individual members that make up any single group. 
As to the mental dift'erences between the two sexes — the topic upon which rather 
more experimental work has been done — the reader may be referred to the 
recent report of the Consultative Committee of the Board of Education on 
Sex-differences and fhe Scrondanj School Oiirrinilvm (H.M. Stationery Office, 



minutes, his mental level for every branch of the elementary 

To measure the effects of experience or training in a trade or business 
is almost as easy as to measure progress in school work. To determine 
the speed and accuracy with which a typist types, or a shorthand-writer 
takes down matter in shorthand, all that is needful is, first, to construct 
a simple test on scientific principles, and then to di'aw up, on the basis 
of actual experiment, standards of efficiency for work of differing diffi- 
culty. Tests for such acquirements are of use chiefly in vocational 
selection — where, that is to say, an employer desii-es to pick out for 
a given job the best in a list of applicants. Vocational guidance, on the 
other hand — where the adviser picks out for a given child the best of all 
possible jobs — is a far more intricate task. It demands the measure- 
ment, not of attainments, but of the underlying aptitudes. To test 
capacity is much harder than to test acquired knowledge or skill. This 
we have already seen. And to determine whether a child is endowed with 
sufficient intelligence, sufficient finger-dextenty, sufficient quickness in 
analysing sounds, for it to be worth while to train him as a shorthand- 
typist, is an infinitely harder affair than to discover whether, once his 
period of training is over, he has reached the minimum of practical 
skill that will be expected from an office clerk. Here then is yet another 
pressing problem for future experimental inquiry. The vocational 
psychologist must work backward from the measurement of acquired 
dexterities in every trade to the measurement of the related capacities. 
At present most tests that he administers hinge upon a blend of both. 
And, in spite of the theoretical difficulty of disentangling the two 
psychological components, the methods devised hitherto have already 
proved their value in factories, in workshops, and in commercial fii'ms. 
In this country vocational tests have been drawn up, and are now being 
still further refined, not only for different kinds of clerical work, but 
also for dressmakers, miners, and the various branches of the engineer- 
ing trades. The practical results, even in these early stages, are an 
unquestionable success.'^ 

b. Temperament. 
We have now reached the most delicate portion of every psycho- 
logical analysis. Hitherto we have been studying the man's intelli- 
gence, of which he is not likely to be ashamed. Now we have to study 
his character, which he naturally prefers to keep private. Having seen 
the full-length portrait exhibited to public gaze, our ruthless hands 
must lift the picture from the wall, and turn it over, that our prying 
eyes may look upon the back. 

^- The teacher, unacquainted with the newer methods, will find the best 
introduction to the subject in Dr. Ballard's excellent and attractive little book. 
Mental Tests. 

-^ Those desirous of further details may be referred to Professor Claparede's 
little pamphlet on Problems and Methods of Vocational Guidance (International 
Labour Office, Geneva, 1922) ; to Professor Muscio's Beview of the Literature 
on Vocational Guidance (Reports of the Industrial Fatigue Research Board, 
No. 12, H 'SI. Stationery Office, 1921) ; and to articles and reviews in the 
Journal of the National institute of Industrial Psychology. 



Character has been detined as the sum-total of all those individual 
qualities which do not constitute, or are not pervaded by, intelligence; 
to avoid the specifically moral implications that cling to the popular 
word ' character, ' I prefer to i-etain the old term ' temperament, ' and 
use it in the sense defined. The qualities thus negatively grouped apart 
are not without a positive aspect shared by them all. Though they 
exhibit low correlations with intelligence, they yet show tolerably high 
correlations amongst themselves. Analytically, they are marked by 
affective and conative elements rather than by cognitive ; by feeling 
rather than by knowledge; by will rather than skill. 

Temperament or character is always more difficult to assess than 
intelligence. Intellectual qualities are relatively constant. Emotional 
qualities are evanescent and evasive — hard to seize, and harder still to 
measure. It is significant to note that, though the idea of 
tem|M'ianie.ntal testing is almost as old as that of intelligence-testing, 
it has seen quite' ai different career. Every on© has heard of Binet's tests 
for intelligence. But most of us have forgotten his efforts to measure 
suggestibility, conscientiousness, and fidelity of report. Of late re- 
newed endeavours have been made to test the feelings and the will; 
and of these the most effective are the methods of associative reaction 
and the so-called psychoi-galvanic reflex. Pressey has tried to detect 
fears and repulsions by getting the examinee to pick out, from a pre- 
arranged list of words, those that have for him a special meaning, or 
suggest a special wori-y or dislike. Downey has tried tO' measure what 
she terms ' will-temperament ' by seeing ■ how far the candidate can 
modify at request his style of handwriting and manner of speech. 
Femald measures self-control by the time the candidate can balance 
himself upon the ball of the foot. The Porteus mazes are to some 
extent a test of recklessness and impulsiveness. And the variability 
in repeated tests of almost any simple kind (as measured, for example, 
by the standard deviation) seems partly correlated with instability. But 
no tests of temperament can claim to have passed beyond the stage of 
tentative experiment.-^ 

In assessing temperament, therefore, we must fall back upon the 
method of observation in place of the method of experiment. The 
personal interview is one recognised device ; and another is the collation 
of reports submitted by competent observers who have been acquainted 
with the examinee during a long portion of his life. Both interviewing 
and reporting has each its own technique ; and in either case the 
technique is susceptible of great improvement by the application of 
simple scientific principles. Much, indeed, has already been done by 
drawing up questionnaires of facts to be noted and observed,"^ and by 

-* A good summary of the literature, with a detailed bibliography, will be 
found in Cady's article on ' The Psychology and Pathology of Personality : A 
Summary of test-problems,' ./. DpIwi].. vii.,'225 (1922). 

-' Of these perhaps the most suggestive are those given by Webb, ' Character 
and Intelligence.' Brit. J. Psych. Mon., I., and Hoch and Amsden, 'Guide to 
the Descriptive Study of Personality,' Eev. Neur. Psych., xi., 577. Cf. Psych. 
Rev., xxi., 295. 


contriving rating-scales"'^ for the registration of such facts in terms of 
a comparable scheme. 

1. Inborn Emotional Qualities. 

As with intellectual qualities, so with emotional, it is both con- 
venient and legitimate to distinguish at the outset the inborn from the 
acquired; and, so far as possible, to judge each level independently. 
In both directions much light has recently been thrown by the work 
of living authors. The inborn mechanisms have been tentatively cata- 
logued and defined by McDougall ; the acquired mechanisms by Freud 
and his school. The former lays stress upon hereditary factors ; the 
latter upon developmental. But their views, however much opposed in 
general standpoint, are not so much incompatible as complementary. 
And they have this in common : both agree with one another in 
emphasising the dynamic elements in mental life, in contrast to the 
excessively intelloctualistic preoccupation of the traditional psychology 
of the past. Each doctrine, although developed primarily as a correc- 
tion of general psychological theory, is of the utmost practical value 
in studying the individual mind. 

To sift and winnow inborn tendencies from those that are acquired 
is even harder in the realm of character than in the field of intellect. 
With adults it is all but impossible. With the young a few suggestions 
can at times be gleaned from the family history, or from the early 
personal history of the child himself. With children, too, the dis- 
crimination is more important practically. To know whether a spiteful 
boy is inherently ill-tempered, or only venting some half-liidden griev- 
ance; to know whether an erring girl is constitutionally oversexed, or 
merely putting into practice what she has picked up' from corrupt com- 
panions ; tO' separate the nervousness left by a shock from a chronic neu- 
rosis rooted in the system and likely to merge into madness or hysteria ; 
toi discriminate the excitability that is but a brief and transitory episode 
of some pubertal crisis from the excitability that began at birth and may 
last a lifetime — these are distinctions that make a world of difference in 
the treatment of the delinquent or neurotic while he is young. 

a. Specific Inborn Emotions and Instincts. 
English writers, McDougall, Shand, Drever, and others, find the 
foundations ol human character in the instincts with their correlated 
emotions ; and, taking their cue very largely from William James, they 
have given us useful working classifications for our common instinctive 
tendencies — inventories sufficiently identical for the purposes of the 
practical man. The strength with which each instinct is inherited is 
of necessity itself inborn. Accordingly, before estimating the character 
of a given individual, the first step is to take the universal human 

"^ On rating persons either by ' relative position ' or by reference to ' key- 
subjects ' (a method elaborated with some success by the psychologists of the 
American Army) a rich literature has grown up. See, among other references, 
Tfie Personnel System of the U.S. Army, vols. i. and ii. ; Scott, Psych. Bull. xv. 
(1918); Thorndike, /. Appl. Psych., li. and iv. (1918 and 1920); and Rugg, 
7. Educ. Psych., xii. and xiii. (1921 and 1922). 


instincts one by one — pugnacity, fear, curiosity, disgust, sex, tender- 
ness, gregariousness, and the like; and to ask in order with what 
intensity he has inherited each. In a study of juvenile crime I have 
endeavoured to show what an essential part the strength of the several 
instincts plays in determining the commoner forms of naughtiness and 
wrong behaviour in the young; in the elderly, and in tlie apparently 
virtuous, whether old or young, the same fundamental motives come 
more obscurely into play. 

How can they be assessed? Not easily in the artificial and well- 
disciplined atmosphere of school or classroom ; but with fair success, 
at any rate for delinquent and neurotic children, under more natural 
conditions where behaviour is spontaneous, as at home, in the street, 
in the playground, and in places of amusement generally. ' A man's 
nature,' says Bacon, ' is best perceived in pinvateness, for there is no 
affectation; in passion, for that putteth a man out of his precepts; and 
in a new case or experiment, for there custom leaveth him.'"' The 
most serviceable method is to seek for certain standard situations, parti- 
cularly those calculated to excite instinctive reactions ; to observe the 
conduct of individual after individual ; and so to gain by experience a 
notion of different grades of response. When relating to situations 
equally definite, the reports of parents, teachers, and the child himself 
provide suggestive supplements. 

p. General Emotionality . 

In a paper read some time ago before what was then the Psycho- 
logical Sub-Section of this Association, I endeavoured to show that, in 
a random group, all emotional tendencies appeared to be correlated one 
with another in much the same way as intellectual. The child most 
prone to sorrow is often exceptionally prone to joy. The coward who 
bullies the weak is often the first to quake and quail before the strong. 
Correlations of this nature suggest the existence of a second central 
factor underlying the instincts and emotions, analogous to, but inde- 
pendent of, the factor termed intelligence. I have termed it ' general 
emotionality.' Those who manifest this inborn emotionality to an 
exceptional extent I call ' unstable ' ; and the most extreme cases 
'temperamentally deficient.' And, in varying degrees, the existence 
of an unstable constitution is the chief characteristic feature of most 
delinquents and nearly all neurotics. 

It is my view that a classification of the separate instincts, which 
shall be ultimately valid and convincing, can be reached only by the 
method of multiple correlation, by first eliminating, that is to say, the 
influence of the central factor, and then observing what specific factors 
remain, connecting particular forms of behaviour one with another.^* 
If one makes a hierarchical table for the instincts and emotions, taken 
each as a unity, one seems to perceive the presence of a third set of 
factors — ' group factors ' of an intermediate level. When the influence 

-~ Essai/s. xxxviii., 128. 

-* Onlv in this way can the issue between McDoueall and Thorndike — whether 
the specific innat* tendencies to behaviour are roughly six, or more nearly sixty 
or six hundred — be satisfactorily solved. 


of the general facter has been ehminated, there emerge positive and 
negative correlations of a ' partial ' order, which show that certain 
instincts tend to go more closely together than others. On the basis of 
such group -combinations we are led to distinguish certain broad 
emotional dispositions of at least two qualitatively differing kinds. On 
the one hand, the active or ' sthenic ' emotions — anger, assertiveness, 
curiosity, joy, and perhaps sex — appear specifically correlated; on the 
other hand, the passive or ' asthenic ' emotions — fear, submissiveness, 
disgust, sorrow, and perhaps gregariousness — seem in a similar way to 
be correlated with each other positively, but with the active or sthenic 
group negatively. Jung and his followers, working chiefly with 
abnormal 'patients, have recently thrown out some very suggestive 
speculations upon so-called emotional types. Their chief division con- 
sists in a revival and expansion of an old dichotomy. What have 
formerly been described as ' sensitive ' and ' excitable ' types, or 
' restrained ' and ' unrestrained ' types, or ' subjective ' and ' objective ' 
types, or latterly ' herbivorous ' and ' carnivorous ' types, are now re- 
named ' introverts ' and ' extroverts. ' Once more, I believe the method 
of multiple correlation will afford the best way to confii'm for the normal 
population these interesting deductions from pathology.-' 

ii. Acquired Emotional Characteristics. 

Besides reviewing the strength of the several instincts and emotions 
which a man inherits, we must also investigate the more complex 
emotional tendencies tliat he has, in the course of his life-history, pro- 
gressively acquired. These, according to the different angles from 
which they are regarded, and according to their own intrinsic nature, 
may be designated and sub-classified as habits, interests, sentiments, 
and complexes. We have, therefore, to inquire what habits each person 
has developed out of his instincts, what emotional attitudes he has 
unconsciously formed, what interests he has cultivated, and what ideals 
he has framed. These things are best ascei'tained through observation 
and interview. But the possibility of moral tests is already being 
investigated by the processes previously so successful in tests of intelli- 
gence. Attempts at measuring ethical discrimination, for example, 
have been made upon the following lines : a list of offences is drawn up, 
each described upon a separate card — breaking windows, scalding the 
cat, not going to church, stealing from a blind man's hat, flirting with a 
stranger, committing suicide, killing a thief, and the like; the examinee 
has to arrange them in order of wickedness. The arrangements of 
delinquents differ considerably from those of law-abiding childi^en.'" A 

-^ I have no space to allude further to attempts to classify the basal psycho- 
pathic and neurotic types I can only repeat that the trend of current work 
is to show that subnormalities in temperament and character, like subnormality 
in intellect, are extreme instances of milder deviations discoverable in the normal 
population. Useful references from the clinical standpoint are Wells. Mental 
Fegressinn : Its Concepts and Types ; Rosanoff, ' A Theory of Personality based 
on Psychological Experience, Psych. Bull., xvii.. p. 281; and Paton. Human 

30 Fernald. Anicr. J. Insanity. Ixviii.. .547: Haines, Psychol. Bi c. xxii.. 303. 


suggestive set of tests has been recently applied, by one American investi- 
gator, to a group of boy-scouts, and, by another, to groups of delinquent 
and non-delinquent children. The child is required to trace mazes with 
his eyes shut ; to fill up and correct completion-tests with the key 
temptingly handy on the back ; to state how much he knows of various 
topics, with the prospect of earning a box of confectionery if he obtains 
full marks. The measure is the number of times he cheats or over- 
states, and the results correlate with independent estimates of moral 
character to the extent of .42." Sometimes (as in the last research) the 
examinee is also given a syllabus of questions relating to his own 
character : ' What kind of amusements do you prefer ? Do you get 
on well with teachers and with other children? Would you like to 
wear jewellery and fine clothes? What do you think about when you 
are alone ? What would you do if a lot of money were left you ? ' As 
a rule, however, an indirect technique is far preferable to a direct. The 
moral test is, as it were, to be camouflaged in the guise of a test of 
intelligence or information. The optional question-paper is full of 
possibilities in this direction. Every teacher knows how, in examina- 
tions on languages or mathematics, the routine worker chooses the 
mechanical questions, while the more enterprising select the problems 
and the riders; the cautious prefer the prepared texts, the adventurous 
the unseen translations. It is an interesting exercise to collect a set 
of picture postcards, artistic, humorous, or informative, and to request 
the child to aiTange them in order of preference or merit. The influence 
of special interests, working quite unconsciously if the cards have been 
chosen with care, is nearly always obvious. 

Pew, however, would as yet pretend that such tests have more than 
an expei'imental interest. As Terman has put it : ' The reliability and 
validity of tests for moral traits have proved lower than an optimist 
might have hoped for. But the correlations obtained are quite as high 
as those yielded by the early intelligence tests of fifteen or twenty years 
ago. And this is no small achievement.' '^ 


Here, then, are the main items in the programme of the mental 
examiner. Here is my sketch of the skeleton of the mind. 

Having tested all that he can test, having measured all measurable 
capacities, having passed in review all available data that throw light 
upon the rest, the psychologist must in the end bring his mixed materials 
together in one synoptic survey. He must reconstruct the mind dis- 
sected. The most expedient w^ay of doing this is to plot out what is 
known in this country as a ' psychogram,' and elsewhere as a ' mental 
profile. ' The various findings are to be charted diagrammatically upon 
some uniform and comprehensive scale. If he takes for his unit the 
percentile or the standard deviation, there is no capacity, no tendency, 

" Voelker, ' The Functions of Ideals and Attitudes." Col. Univ. Contrib. Ed. 
(1921) ; Cady, ' The Estimation of Juvenile Incorrigibility, Journ. Delinq. Mon^ 

32 Preface to Cady's paper, loc. cit. sup., p. 4. 


no quality, in theory at any rate, that cannot thus be comparably 

In his conclusions he will beware of four temptations. First, he 
must never court the applause of the unlearned, and the sneers of the 
worldly-wise, by claiming to have caught a living soul, and to have 
caged it in a formula, however technical, however abstruse. The grow- 
ing mind is more than the sum of simple assignable elements; and all 
personal equations must issue in a surd. Similarly, he will avoid con- 
densing his data at any point into vague generalisations — the announce- 
ment of a type, an average, or a total. A composite of snapshots, each 
taken from a different angle — a side-view, a full-view, a half-turn, and 
the rest — is no photograph at all ; only an indecipherable blur. Thirdly, 
he must everywhe)-e shun the besetting sin of the mere literary 
biographer — the confusing of facts with hypotheses to explain those 
facts, or, worse still, the submission of bare subjective inferences 
fortified by a string of anecdotes ; data and interpretations the scientist 
keeps rigidly apart. Finally, throughout his inquiry, he must neither 
correct nor criticise, but coldly and calmly observe. His interest lies 
in realities, not in values ; and should be ' positive, ' as the philosophers 
say, not ' normative. ' The teacher may psychologise while he is teach- 
ing, but he must not teach while he is testing. Nor should he anticipate 
the judgment-day by seeking to award praise or blame. His humble 
function is that of the recording angel, who registers, like a watch or a 
weighing machine, without audible comment. 

There can be no denying that each inquiry will be slow, circuitous, 
and cumbersome. How long (it is sometimes asked) should it take to 
size up a single child? It was a tradition of the ancient world that no 
metamorphosis could hide a god from a god. And, upon a comple- 
mentary principle, it seems often assumed that no disguise or taciturnity 
can save defectives or delinquents from the penetration of the mental 
expert. He is expected to cast his eye round the classroom or the 
pi'ison, and to make a darting snapshot diagnosis on the spot. Our 
school doctors are given about ten minutes to decide whether a boy is 
deficient or not. Our magistrates take fifteen or twenty to determine 
what is best for a first offender. But the laboratory tester thinks himself 
a miracle of swiftness if he has measured a child's intelligence in less 
than an hour; and the psychoanalyst asks his startled patient for six 
months oi separate weekly sittings to unravel a single complex. A 
longer period still was required by Shakespeare : 

' It is not a year or two shows us a man. ' 

And Dr. Johnson thought the intimacy of a lifetime scarcely enough : 
' God Himself, sir, does not propose to judge man until the end of his 
days.' Whether they be normal or subnormal, backward, delinquent, 
or neurotic, or merely youthful applicants seeking their most appropriate 
career in after-life, we can deal with human beings fairly and efficiently 
only by making an intensive, individual study of each isolated mind ; 
there is no other way. Human personality, with all its infinite variety, 
is the most important single factor in all our social life ; and the 
expenditure pf time, however lavish, will never be lost. 


Where the exigencies of the case demand a speedy assessment, I 
recommend the practical psychologist to a-im chiefly at the so-called 
general factors. If I were permitted to measure no more than a pair 
of mental qualities, I should look first to the degree of a man's native 
intelligence — his ' genei-al ability,' with which more special capacities known to be correlated; and next to the degree of his native in- 
stability — his ' general emotionality,' with which his special instincts 
are apt to be in accord. Were I granted the grace of two or three 
additional estimates, they would still be of a general type — general 
physical health, general moral character, and general cultural 
attainments . 

It may be that I am too optimistic, and that my views are premature. 
But it is my personal conviction that the main outlines of our human 
nature are now approximately known, and that the whole territory of 
individual psychology has, by one worker or another, been completely 
covered in the large. We have viewed the whole continent from above 
by rapid aerial flights toiwards different quarters. It remains to link up 
and to co-ordinate the numerous reconnoitring pioneers ; then to descend, 
and, by the laborious method of exploring feature after feature, to 
correct up our maps in definite detail. Once its broad principles have 
been determined, it is from the close and microscopic detection of 
minutiae, of tiny items and small but telling indications, that every 
science is eventually built up. This must be the aim with individual 
psychology in the near future. We must discover what mental traits 
are relatively independent, and which are the general among the rela- 
tively specific ; we must construct precise working definitions for each, 
and hammer out by experiment upon experiment, research upon 
research, tests and rating-scales for everything that can be quantitatively 
expressed, inventing new tests for traits not hitherto tested, and refining 
the procedure of the old. Here rather than in any grand discovery 
must further progress lie. 

Finally, let me leave the would-be analyst of character with a 
repetition of a warning already uttered in another place. Individual 
psychology is not a code of niles and principles to be niast.ered out of 
hand in the lecture-room or laboratory. It is not an affair of text- 
book terminology or of a teachable technique. It is the product of 
worldly experience acting on an inborn interest — an enthusiasm for 
persons as persons, in the old nihil alienum spirit. To take an unknown 
mind as it is, and delicately one by one to learn its chords and stops, 
to ' pluck the heart' out of its mystery, and sound it from its lowest 
note to the top of its compass, ' is an art and not a science. The scientist 
may standardise the methods. To apply those methods, and appraise 
the results, demands the tact, the temperament, the sympathetic insight 
of the genuine lover of strange souls. 




A. G. TANSLEY, M.A., F.E.S., 


We meet to-day in a city wliich is one of the greatest seaports of the 
kingdom, traditionally the main channel of our commerce and inter- 
course with the great English-speaking republic across the Atlantic, and 
also the main centre of the import of cotton and of the export of cotton 
goods, with which the prosperity of Lancashire, and to no small degree 
of the country, is so intimately associated. To the enterprise and pubHc 
spirit of the citizens of Liverpool we owe the creation and development, 
within an astonishingly short period, of the distinguished university the 
hospitality of whose staffs, organisations, and buildings we shall enjoy 
during the coming week. Many of us can vividly remember the pride 
and satisfaction with which we saw arise, especially during the last 
decade of last century, one after another of the great institutes of 
research and teaching which have contributed so much to the advance- 
ment of science in the comparatively few years during which they 
have existed. In such surroundings we cannot but be stimulated afresh 
to labour to the limit of our abilities in the cause of that great human 
activity — ^the advancement of science in all its branches — which as 
members of the British Association we all have at heart. 

Since the last meeting of the Association we botanists have to mourn 
the loss of two striking and dominant personalities. Sir Isaac Bayley 
Balfour played a great and worthy part in that revival of scientific botany 
in this country which marked the last quarter of last century. During 
his long tenure of the Chair of Botany at Edinburgh and of the Director- 
ship of the famous Botanic Garden in that city, he was widely kno-wn 
for the ability and assiduity with which he carried out the work of one 
of the most important and onerous botanical positions in the kingdom, 
and for the native shrewdness and sanity, the ripe judgment and experi- 
ence, which he was always ready to place at the disposal of his col- 
leagues. Mr. Henry Elwes was a country gentleman of a type for 
which England has long been famous, who, like Lord Herbert of Cher- 
bury, conceived it ' a fine study and worthy a gentleman to be a good 
botanique that so he may know the nature of all herbs and plants, being 
oui- fellow creatures.' To tliis study Mr. Elwes brought the utmost 
energj' and vigour, pursuing to the remotest lands, both personally and 
by deputy, an rmtiring search for the objects of his attachment. He 

K.— BOTANY. 241 

will best be rememberetl by that magnificent work ' The Trees of Great 
Britain and Ireland,' which, in conjunction with Professor Augustine 
Henry, he pi'oduoed at his own expense on a splendid scale. 

I propose to deal this morning with some aspects of the development 
of pure botany during the last thirty or forty years, especially in this 
country, and with the bearing of these developments on the present 
position of the subject. In seeking for a suitable starting-point from 
which to begin the observations I have to make I naturally turned to 
the address delivered by my predecessor in this chair at the last meeting 
of the Association in this city. On that occasion, in 1896, the chair 
of Section K was occupied by Dr. D. H. Scott, and I found at once 
that the remai'ks with which he began liis Presidential Address were 
surprisingly apt for my purpose. For definiteness of outlook on the 
problems of pure botany and for lucidity of expi-ession they could not 
be surpassed, and their author will, I am sure, forgive me if I use his 
statement as the primary text from which to develop my critical 

' The object of modern morphological botany,' said Dr. Scott, ' is 
the accurate comparison of plants, both living and extinct, with the 
object of tracing their real relationships with one another, and thus 
of ultimately constructing a genealogical tree of the vegetable kingdom. 
The problem is thus a^ pui'ely historical one, and is perfectly distinct 
from any of the questions with wliich physiology has to do. 

' Yet there is a close relation between these two branches of biology, 
at any rate to those who maintain the Darwinian position. For from 
that point of view we see that all the characters which the morphologist 
has to compare are, or have been, adaptive. Hence it is impossible for 
the moi-phologist to ignore the functions of those organs of which he is 
studying the homologies. To those who accept the origin of species by 
variation and natural selection there are no such things as morpho- 
logical characters pure and simple. There are not two distinct cate- 
goi-ies of characters — a morphological and a physiological category — for 
all characters aUke are physiological.' And then the President pro- 
ceeded to quote, evidently with full agreement, from Professor (now 
Sir) Pay Lankester. ' According to that theory ' [i.e. the Darwinian 
theory] , wrote Professor Lankester in ' The Advancement of Science, ' 
' every organ, every part, colour, and peculiarity of an organism must 
either \ye of benefit to an organism itself, or have been so to its ancestors. 

. Necessarily, according to the tlieory of natural selection, struc- 
tures either are present because they are selected as useful, or because 
thev are still inherited from ancestors tO' whom they were useful, though 
no longer useful to the existing representatives of tho^se ancestors. ' And 
a little further on Dr. Scott said : ' Although there is no essential differ- 
ence between adaptive and morpliological characters, there is a great 
difference in the morphologist 's and the physiologist's way of looking 
at them. The physiologist is interested in the question how organs 
woi'k; the morphologist asks. What is their history? '' 

The way of looking at the science of biologv so clearly expressed 

' British Association Report, Liverpool Meeting, 1896, pp. 992, 993. 

s 2 


in these sentences was by no means exceptional. Indeed, it may be 
fairly called the orthodox view at that time. Thus five years earlier, 
in 1891, Professor Strasburger, perhaps the most brilliant and success- 
ful German botanist of what we must now speak of as the last generation, 
wrote in the preface to his great work on the structure and functions of 
the conductmg tissues : ' Morphology as such is a purely formal science, 
and thus ccn-esponds approximately with comparative grammar, in that 
it explains forms by deriving them. It need be as little influenced by 
the functions of the forms to be derived as comparative grammar is 
influenced by the meanings of words. Not that a physiological treat- 
ment of the external and internal structure of a natural body would be 
less fruitful than the morphological, but it forms a different discipline.' 
After referring to the unfortunate effect of physiological points of view 
on the work of the earlier anatomists, who called, for instance, the 
water-conducting elements of plants ' tracheal ' because they thought 
they were air passages, Professor Strasburger proceeded: 'With 
advancing enlightenment the provinces of morphology and physiology 
were separated from one another and developed on separate lines, with- 
out, of course, attaining complete independence ... in fact, organs and 
functions are not separated in nature, and are only logically distinguished 
in order to subserve the building up of science. . . . Morphology finds 
its task only in deriving one form from another, in tracing different forms 
to a common origin. When this is successful the goal is reached. . . . 
The way which leads to morphological -understanding is that of com- 
parison, but only because this way involves a phylogenetic significance. 
Since a direct phylogenetic proof of the origin of a given structure is not 
to be had, moi'phology remains tied to indirect methods. It is often 
supported in its task bv ontogeny, but only in so far as this is capable 
of giving phylogenetic points of view.' ^ Here we have the same insist- 
ence on the separateness of the two disciplines, morphology- and physio- 
logy, and the same clear statement that the object of morphology is 
the elucidation of phylogeny. We may note, however, one striking 
difference. Professor Strasburger thinks that morphology need be 
as little influenced by tTie functions of the forms to be derived as com- 
parative grammar by the meanings of words, and he does not claim, 
like Dr. Scott, that all features of an organism are, or have l^een in 
the past, adaptive. 

It is, I think, impossible to regard the views thus expressed by a 
representative English and a representative Geniian botanist three 
decades ago as representing to-dav an adequate outlook on the problems 
of botany as a whole ; and I shall be engaged this morning in endeavour- 
ing to expound the view w^hich I think w^e should put in its place. First, 
I must pay some attention to the causes of the orthodox attitude of the 
last generation, the generation in which I was botanically brought up, 
and whose orientation I fear I passively accepted. The main canse 
of the greatly intensified interest in comparative morphology which 
led to the claim that this subject represented a separate discipline, 

^ E. Strasburger, TJcher den Ban unci die Verrichtungen der Leitungsbahnen 
in den Fflanzen, Histologische Beitrags HI, Jena, 1891, p. vi. 



co-ordinate with physiology, was, of course, the general acceptance by 
biologists of the doctrine of descent with modification, popularly called 
evolution. Belief in the reality of this process at once invested the 
comparative study of structure with a new fascination. Every part, 
every organ of an animal or plant, could be interpreted in the light of 
the doctrine of descent. All the species of a group should, according 
to the theory of descent, be theoretically traceable to a hypothetical 
' common ancestor ' of the group, and these group ancestors again to 
remoter ancestors. Ultimately we should be able, theoretically at 
least, to reconstruct the whole genealogical tree of the plant and animal 
kingdoms. It was, of course, recognised that we could never hope to 
complete this task, even if we possessed an exhaustive knowledge of the 
structure and development of every kind of organism now living, for 
very many forms had been destroyed and had disappeared altogether 
in the course of the evolution of tlie organic world as it exists to-day. 
But the remains of many of the organisms which had lived in past ages 
were still preserved as fossils, and a knowledge of their structure would 
substantially help us on the way to the goal, even though that goal 
could never actually be reached. Though the geological record was 
extremely fragmentary, yet it did bring to our knov.'ledge many kinds 
of plants, some more or less closely allied to living fomis, others which 
could not be placed in any living group, and others, again, which sug- 
gested that- they might represent or at least stand near to the common 
ancestors of existing groups. 

If we consider the most recent developments of the subject we find 
that, on the whole, the search for common ancestors as such has been 
disappointing. The ' seed-bearing ferns ' (Pteridosperms) have turned 
out to be, so far as we can tell, a perfectly independent group having 
no demonstrable connection with the true ferns. The most primitive 
fossil ferns known (the Primofilices or Ccenopteridese of the Lower 
Carboniferous) certainly represent a very ancient group. But not only, 
according to Dr. Scott in his most recent statement,' do ' Pteridosperms 
and Ferns at all times show themselves perfectly distinct ' : 'we are 
dealing, in the Lower Carboniferous Primofilices, with early races 
already specialised on their own lines, arid probably only indirectly 
connected with the main current of Fern-evolution. ' 

The remarkable Ehynie fossils described by Kidston and Lang from 
the Lower Devonian — the oldest vascular plants with structure pre- 
sei-ved that are as yet known — have revealed in the genera Rhijnia and 
Hornea a leafless and rootless type with large simple terminal sporangia 
and a simple stele occupying the centre of the axis. These plants show 
striking points of agreement with the living Psilotales, but their dis- 
coverers, so far from being prepared to assert that they are prototypes 
of Psilotales, create for their fossils a new class, the Psilophytales. 
Thus we have now recognised six distinct classes or orders of living and 
fossil Pteridophytes,'' and parallel with these six distinct classes of non- 

' D. H. Scott, ' The Early History of the Land Flora,' Nature, Nov 11 
1922. ' 

■* Psilophytales, Psilotales, Sphenophytales, Equisetalos. Lycopodiales, 


angiospermous seed-plants, two wholly and others largely fossil/ In 
addition there are still a multitude of fossil forms, largely detached frag- 
ments such as sori, seeds, leaves, or wood, which are not sufficiently 
known or correlated to permit of their definite assignment to one or 
other of these classes. From these and for other discoveries it may 
well turn out to be necessary in the future to construct one or more 
new classes. 

Leaving these great series of vascular forms which played so 
dominant a part in the history of vegetation during the Primary and 
Secondary geological epochs, we may note that the gulf which has 
always existed for the phylogenist between Pteridophyta and Bryophyta 
is as wide and deep as ever, and that the same may be said of the gulf 
between the Bryophyta and the Alg£e. The attempts which have been 
made from time to time to derive various gro'ups of Fungi from various 
groups of Algse seem to me quite unconvincing. The phylogeny of the 
Fungi themselves remains obscure, though certain lines of advance 
among them and among the Algse are fairly probable. On the whole 
the most successful phylogenetic speculations seem to me to be those 
that trace some at least of the classes of Algse back to a common origin 
in the great plexus of the Flagellata, which may also, perhaps, be 
regarded as the likehest recognisable starting-point of the main lines 
of invertebrate evolution. Turning to the other extremity of the Plant 
Kingdom, to the characteristically modern dominant vegetation of the 
earth, we are scarcely able to form a trustworthy opinion as to the 
nature of the plants from which the two great modern groups of Angio- 
sperms sprang, though the speculations of one of my predecessors in 
this chair, the late Miss Sargant, founded on wide researches and elabo- 
rated with masterly ability, are certainly of great interest, and full oi 
suggestion as to what m.ay have occurred. The evidence from fossil 
Angiosperms is still unsatisfactory, and Mr. Hamshaw Thomas's inter- 
esting discoveries of Jurassic Angiosperms scarcely throw light on the 
problem of the descent of the gi'oup. It has been the invariable history 
of such researches, pursued with a view to tracing phylogeny, that the 
better a newly discovered group has become known the less probably 
it appears to represent the common anceistors O'f other existing or fossil 
groups. The points of origin, the roots, so to speak, oI each group 
have been constantly lengthened and shifted further back in geological 
time so that they become more definitely independent from one another 
and appear to issue separately from a past which remains obstinately 
obscure. ' It may be,' said Professor Seward recently," speaking from the 
fullness of a very wide knowledge of the floras of the past, ' that we shall 
never piece together the links in the chain of life, not because the missing 
parts elude om' search, but because the unfolding of terrestrial life in 
all its phases cannot be compared to a single chain. Continuity in some 
degree there must have been, but it is conceivable that plant life viewed 

5 Pteridospermese, Cordaitales, Cycadophyta, Goniferales, Ginkgoales, and 
Gnetales : see Seward, Fossil Plants, vols. III. and IV. 

" A. C. Seward, 'A Studv in Contrasts,' (Hooker Lecture), Joiini. Linn. Soc. 
Hot., October 1922, p. 238. 



as a whole may best be represented by separate and independent lines 
of evolution or disconnected chains which were never united, each being 
initiated by some revolution in the organic world.' And again/ the 
development of vegetation ' appears as a series of separate lines, some 
stretching into a remote past, others of more recent origin. ' ' It would 
almost seem that " missing hnks " have never existed.' ' There is no 
insui^erable objection to the conception that terrestrial vegetation 
received additions from upraised portions of the earth's crust at more 
than one epoch in the history of the earth. ' The picture of the history 
of evolution here suggested makes the search for common ancestors 
literally a hopeless quest, the genealogical tree an illusory vision. 

But there can be no doubt whatever that the great body of work 
originally stimulated and inspired by the ideal of the genealogical tree 
has added very greatly to our knowledge of the range of the forms and 
structures of plants, notably of vascular plants, and of the rise and fall 
of the gi'eat groups during the passage of geological time. In regard to 
the structures of plants, it has directed attention especially to the 
vascular system of the plants of the middle grades of organisation, and 
given us a much more extensive and accurate acquaintance with the 
larger features of its organisation and development throughout these 
grades. We have discovered that vascular structure shows a type of 
progression from simpler to more complex forms which is broadly 
identical along many different lines of descent, a progression closely 
paralleled in the ontogeny of the individuals belonging to species which 
exhibit the more complex adult stmcture; and w-e have thus learned to 
correct the one-sided emphasis that used to be placed on the reproductive 
organs as guides to evolution. Though these last remain, so far as we 
can tell, the most trustworthy indices of ajfinity, yet ' the characters 
of the vascular system,' says Professor Bower in his recently published 
book on the Ferns, are ' the most important structural features for the 
phyletic treatment of the Class.' ^ 

Without question, then, morphological and paliBobotanical w^ork, 
particularly in its extension to the internal structure of plants, has 
added greatly to our knowledge of the plant kingdom, and has given us 
a much fuller and juster appreciation of the range of the great middle 
groups, and to some extent of their relationship, or, as perhaps we 
should say, of their lack of relationship, to one another. One of the most 
striking results of this work as a whole has been the inci'easing doubt it 
has engendered as to whether many organs formerly regarded as homo- 
logous in the strict sense, i.e. homogenetic, of common origin in descent, 
are really homologous in this sense at all. The principle of homoplastic 
or parallel evolution has been more and more widely extended. And 
our increasing though still very iTidimentary knowledge of llie factors 
which determine organic form would suggest not only that parallel 
evolution has been determined by parallel conditions of life, an idea 
long familiar to biologists, but that we should expect a recurrence of the 
same formative factors, producing similar structures, on different lines 

' Presidential Address to the Geological Society, 1923. 
' F. 0. Bower, The Ferns {l<'i(icale.<!), 192.3, vol." I, p. 192. 


of descent, and to a laa-ge extent independently of particular life 

It seems to me that no structure which has been assumed to be 
homologous throughout a large seiies showing many gaps is really safe 
from the suspicion of having been developed independently on different 
lines of descent. In a recent paper Dr. Scott writes ' of the inference 
' that the Seed Plants, of which the Pteridosperms are among the earlier 
representatives, constitute an independent phylum, of equal antiquity 
with any of the recognised lines of Vascular Cryptogams. ' But is it 
at all certain that the Seed Plants really constitute a single phylum? 
Is it not perfectly possible that the seed with its attendant mechanisms 
has been independently evolved in some or aU of the six classes of 
Seed Plants which, apart from the Augiosperms, are now ]-ecognised '.' 
It is clear that the more such suspicions effect permanent lodgment in 
our minds the more uncertain ail wide positive phylogenetic conclusions 
must become. 

Meanwhile the whole of this branch of botany seems to leave the 
great majority of the younger botanists cold. No longen under the 
immediate influence of the j'evolution in biological ways of tliinking 
brought about by Darwin, they are not greatly interested in comparative 
morphology, nor in the attempts to disentangle the past history of the 
])lant kingdom, sustained and even magnificent as these attempts have 
been, and greatly as they have enriched oiu- knowledge of the past life 
of our world. There is, to many of them, an effect of hopelessness and 
even of futility in the effort to trace out the course of the threads in an 
intricately woven carpet, with no attainable certainty that we have got 
them right, however long and patiently the task is pursued, partly 
because so many of the threads, such large portions of the carpet, have 
been destroyed for ever, partly because, as Professor Seward suggests, 
we may, in effect, be dealing not with one carpet, but with many. 

While we may urge that far too much time has been, and in many 
places still is, devoted to the study of comparative morphology in 
elementary teaching, it is impossible to deny the great interest and 
importance of conclusions like those quoted from Dr. Scott and Professor 
Seward. From the point of view of the ideal of the ' genealogical 
tree ' these conclusions are negative, but they are none the less interest- 
ing and valuable, for they are giving us a truer view of the past history 
of plants. 

There has certainly been no loss of interest in the 'process of develop- 
ment, whether phylogenetic or ontogenetic. The unfolding of life upon 
the eaiiih, the marvellous story of development and change, of increasing 
complication and endless variation on the one hand, and on the other 
the great problem of how the complex organism comes to develop from 
the minute zygote, can never lose their fascination for the human 
mind. It is the formal comparison of the end results of this process, 
with a view to the determination of phylogenetic i-elationsliips, the treat- 
ment of the problem as'' a purely historical one,' which seems to so 
many of the keenest j^ounger biologists a hopeless and not a very 

' The Origin of the Seed Plants, p. 227. 

K.— BOTANY. 24T 

remunerative pursuit. Tlieir interest is in the process itself rather than 
in tlie phylogenetic connexions of its particular results. They want to 
Ivnow what brings about development and evolution, what are the 
driving forces behmd these processes. 

The orthodox ' Darwinian ' answer to tliis question, so far as it 
applies to phylogenesis, was 'natural selection.' The organism was 
supposed to be capable of indefinite ' spontaneous ' but heritable varia- 
tion in all directions and of various degrees, and those which happened 
to be useful to the organism by giving it a decisi\'e advantage in the 
struggle for existence were preserved because the individuals which 
showed them alone survived and produced offspring, which inherited 
the useful variations and thus modified the species. Two or more diver- 
gent sets of variations might happen to fit different individuals of a 
parent species to different sets of conditions, different habitats, into 
which they had wandered, while the parent species remained behind 
unmodified in the original habitat, and thus new varieties were supposed 
to originate. By the further development of the new characters, i.e. by 
the favouring of further variations in the same direction as the original 
ones, these varieties became distinct species. The same process further 
continued and involving also other structural features would lead to the 
wider divergence of the derivatives from the original stock, and this 
divergence would ultimately become so great that the different forms 
would be placed in distinct genei-a. The sharpness of the specific and 
generic distinctions would often be enhanced by the disappearance of 
the original or of intermediate forms, owing for instance to the physical 
conditions of life changing and becoming unsuitable for them or to 
their suppression by rivals whose variations had been more successful. 
In the course of a very long time, by a continuation of the same pro- 
cesses, the distinctions which were at first specific, and later generic, 
would become family distinctions, later again ordinal distinctions, and 
so on up to the gxeat phyla. 

Alongside of the evolution of new species, genera, and families in 
the same general environment, such for instance as the tidal zone, there 
had been a migration of some forms to the land, or perhaps, as Mr. 
Church would have us suppose, a gradual raising of the land bearing 
aquatic forms above the water-level. These aquatic forms had thus 
been faced by conditions of life vei-y different from the earher ones, so 
that the variations which vAere preserved and perpetuated were necessarily 
in new directions, and gradually built up the equipment of the land plant 
— the typical leaf and root, the vascular and aerating systems, the 
cuticle, the air-distributed spores. From these earlier land plants again 
by further variation the hetei'osporous forms were derived, and finally 
the seed and angiospermy, while various progressive complications and 
modifications of the primitive vascular tissue, including secondary 
thickening, had established both more copious and more efficient con- 
ducting and mechanical systems, and thus led to the quickly growing, 
largely upright, modern plants, extraordinarily ' flexible ' to various life 

I think this is a fair rougli statement of what was often known as 
the Neo-Darwinian account of evolution, as applied to plants, in the 


last decade of last century. It was not precisely Darwin's own position, 
but gained its great vogue, especially in this country, largely through 
the, writing of Alfred Eussel Wallace, and through the germ-plasm theory 
of August Weismann. All characters whatever, as Dr. Scott and Sir 
Eay Lankester said, were regarded as .adaptive or useful in the first 
instance, and as produced by the summation of small variations. The 
origin of these vai-iations was obscure. The fact that such variations 
occurred was sufficiently established, and their occurrence was simply 
taken as a datum on v/hich natural selection could woi-k by picking 
out and establishing the favourable ones. The only characters which 
were not considered adaptive at their first origin v^-ere covered by the 
conception of ' correlated variation,' i.e. structural or functional changes 
necessarily involved by the primary adaptive ones, though not in them- 
selves useful to the organism. Later on the structural changes which 
were at first useful might be so no longer, owing to their supersession 
by other structures or by a change of conditions. They were, however, 
or might be, still inherited, being incorporated in the constitution of 
the organism's germ-plasm, though superseded, so far as curx'snt adapta- 
tion went, by more recently acquired characters, as in the familiar case 
of the embryonic gill- slits of the higher vertebrates. Frequently an 
organ originally acquired for one purpose was diverted to different uses, 
as for instance the anterior fins of fishes, which became, in their modi- 
fied ten-estrial descendants, legs, arms, or wings. Thus the actual 
structui-e of an organism could only be explained by its ancestral history. 
The weak point of this theory of evolution, on the facts then known, 
apart from the obscurity sun'ounding the origin of variations, was tha 
difiiculty of understanding hew the first minimal variations, which were 
supposed to be the foundation oi new structures, could, at least in many 
cases, be of life-preserving value — ' survival value,' as the phrase goes — 
to the organism, and how they could avoid being ' swamped,' as it was 
supposed would happen, by intercrossing with other unmodified mem- 
bers of the species. Various theories of segregation, geographical or 
physiological, were proposed to get over this difficulty, but it was very 
doubtful if they could be considered as O'f sufficiently wide application 
for the pm'pose. Further, the theory required that the actual structural 
differences between species — apart from ' correlated variations ' — should 
always be adaptive; yet the greater number of naturalists who had a 
wide first-hand acquaintance with species as they exist in the field, and 
with the actual differences between allied species, could not find that 
this was the case. Some people attributed this scepticism to ignorance 
of the functions of particular structures which seemed to be useless, the 
Neo-Darwinians refusing to^ admit that constant characters might have 
no ' function ' after all, unless they wei'e vestigial or ' coi-related ' with 
others that had. The field naturalists, however, remained for the most 
part obdurate. One distinguished biologist, referring to the hope that 
all specific characters would ultimately be proved adaptive, added, 
' Time has been running now and the hope is unfulfilled.' Ingenious 
persons explained all sorts of peculiar structures and arrangements — 
' myrmecophily, ' the insectivorous habit of some plants, extra-floral 
nectaries, the long tips of certain tropical leaves, and countless others — 



•as of use to the species that exhibited them, always with the implication, 
and sometimes with the express assertion, that they had been developed 
because of then- survival values. One by one, in the hght of critical 
research, most of these ' explanations ' of structure have broken down. 
Not only is ' survival value ' almost impossible to prove in any given 
case, but many of these supposed adaptive structures or aiTangements 
have been shown not to^ work in the way they were supposed to work. 
Nevertheless, the habiti has remained, even up to this day, not only of 
looking for the ' use ' or ' function ' of every structural character — 
quite a legitimate proceeding in itself, if we are not wedded to the belief 
that it must have a ' use ' — but of considering its existence sufficiently 
' explained ' when such a use has been experimentally established or 
even more or less plausibly suggested. 

Eound about the beginning of the present century several publica- 
tions of first-rate importance began to put a new complexion on these 
problems. First there was De Vries's work on mutations," which claimed 
to show that discontinuous variation, whose widespread occurrence in 
nature had already been demonstrated by Bateson and suggested by him 
as the prime cause of the discontinuity of species,^' w^as the important 
factor in evolution. In 1903 Johannsen's work on ' pure lines "" showed 
in the most unmistakable manner in the case of the bean that theinini- 
mal ' fluctuating ' variations, on which Wallace and the Neo-Darwinians 
had been accustomed to rely as the material on which natural selection 
operates, are not inherited, so that if one breeds from a group of such 
variations which deviate from the mean of the pure line, thei-e is no 
establishment of a deviating mean in the descendants, but a regression to 
the original mean. Meanwhile, the rediscovery of the Mendelian pheno- 
mena and the rapid extension of the range of characters in which they were 
found to be exhibited had at last placed our knov/ledge of the mechanism 
of heredity and variation on a secm-e basis. The immense quantity of 
breeding and cytological work which has followed has given reality to 
the conception of ' genetic constitution,' or genotype as it is called in 
current terminology. W© now know that an ordinary ' Linnean ' 
species is, often at least, an aggregate or mixture of crosses from ' pure 
hnes ' in respect of different characters, each pm-e line with a specific 
genetic constitution based on the structure of the chromosome complex. 
New heritable variations of the stock are produced by redistribution of 
units within the chromosomes resulting from the crossing of individuals 
belonging to different pure lines or of their hybrid offspring. This 
apparently occurs in the stage of ' synapsis ' of tlie nuclei which are just 
entering upon the divisions that result in the tetrads of spores and 
gametes ; and it is followed by the ' reduction division ' of the mother 
cell of the tetrad, resulting in segregation of unlike units so that the 
gametes of a single tetrad bear different characters. Other internal 
changes in the chromosome complex may perhaps take place, but of 
these we can as yet say very little. 

'" Fublislicd in a series of papers culminating in his great work, Die 
.Miilatlniiythcoric. Leipzig. 1901. Vol. 11. 1903. 

'1 Bateson, Matcruilf: for the Study of Variations. London, 1894. 

1= Johannsen, Vebur Erblichkeit in Pofulationen vnd reinen Linien. Jena, 


It is to be noted that these great discovehes do not necessarily 
invaUdate the Neo-Darwinian position. It is still perhaps just possible 
to hold, so far as this new knowledge of the mechanism of variation 
and heredity is concerned, that in any given complex of forms which 
we call a species, only those variations are in the long run preserved 
which adapt the individuals that show them more closely to their condi- 
tions of life. But the more exact knowledge we now possess oi the 
way in which new heritable variations in the body of the organism 
ac^tually come to arise and maintain themselves has firmly established 
tiie tliesis, clearly stated by Bateson nearly thirty years ago," that the 
primary problem of evolution is the process of variation itself and not 
what happens to the variations in the struggle for life after they have 
appeared. Variations from type, more or less considerable, actually 
arise by new combinations of the primary chromosomal determinants — 
genes as they ai'e now called — -Ijy the loss (dropping out) of certain 
genes, or perhaps by actual changes in the nature of the genes or the 
appearance of new ones; and the variations so produced persist, or may 
persist, indefinitely, without any reference to selection. It is perfectly 
true, of course, and must always remain true, that every organism 
wliich survives must be viable and sufficiently adapted to the conditions 
of its existence. But it is not only unproved, it is a gratuitous belief 
unsupported by the evidence, that all new characters, all differences 
between species, are of survival value or owe their origin in any way 
to selection. 

The clearest and most plausible account of the origin of new species, 
in the light of our existing knowledge, is, it seems to me, that given 
by the Hagedooms." Any group of related individuals capable of 
interbreeding, so far as its somatic characters are genetically determined, 
owes those characters (phenotype) to the totality of the genes possessed 
by the zygotes from which they were produced (genotype). Some of 
the genes present m.ay not, however, affect the phenotype, because they 
do not meet with the developmental or environmental conditions necessary 
to enable them to find expression in the soma, or because some other 
gene or genes, interaction with which is necessary to phenotypic expres- 
sion, may be absent. The total actual 'genetic ' variability of the group 
is measured by the total range of phenotypic variability : the total poten- 
tial variability is greater than this because it includes the potential effects 
of the genes which are present, but which may, at any given moment, 
be inoperative for the reasons cited. The total potential variability is 
measured by the number of genes for which the group is not pure. 
If the whole group is pure, uniform and homozygous for all characters, 
it cannot, by hypothesis, vary genetically. The potential variability of 
the group is increased if there are taken up into it individuals which 
either possess a gene or genes not present in any member of the group 
or which lack genes that are the common property of all the original 
members of the group. Thus if fresh crossing takes place with fertile 
individuals outside the group, the potential variability of the original 

1^ W. Bateson, op. cit., p. 6. 

1* A. L. and A. C. Haeedoorn, The Relative Value of the Processes causing 
Evolution. The HaMe, 1921. 

K.— BOTANY. 25 1 

group is increased. But in the absence of this, in fact in all cases where 
the group is isolated, mechanically or otherwise, the potential variability 
constantly tends to decrease, because the offspring of any generation are 
normally produced from a small fraction only of the individuals of that 
generation, and this leads to the dropping out from the breeding stock 
of part of the total potential group variability. In the case of a self- 
fertilised plant the reduction of variabiirty will proceed even if all the 
individuals produce offspring, because Hendelian segi-egation will result 
in the daughter being heterozygous for only one-half the number of 
genes for which the mother was impure. In the absence of crossing 
with individuals having a different genotype, heterozygotes will produce 
some homozygotes, but homozygotes can never produce heterozygotes, 
so that the proportion of heterozygotes in such an exclusively self- 
fertilised race will steadily decrease. This is an intelligible view of 
the origin of the discontinuity of species. The mechanism will work 
whether natural selection is in play or not. 

Suppose, for instance, that from a breeding stock with a given total 
potential variability a number oi islands are colonised. The colony on 
each island will, on random selection, have a substantially smaller total 
variability than the original stock, because it will he derived from a. much 
smaller number of individuals, and a good part of the original variability 
will be lost. Further, if the colonising groups are selected haphazard 
the potential variability of each colony will be different, and the: offspring 
of the different colonies will form as many new 'species,' each of which 
will in successive generations increase in pm'ity. The differences 
between these species may, however, have, no relation whatever to adap- 
tation, because the characters in which the new species differ from one 
another and from the pai-ent species may have no survival value in any 
of the habitats. Many years ago J. T. Gulick called attention to the 
fact that the species of land molluscs on the Sandwich Islands showed 
differences which did not seem to be adaptive, but which were closely 
related to isolation." More recently Crampton has arrived at similar 
results in regard to the forms of another land snail, Parttda, and has 
actually shown that numerous ne-w forms have arisen, as he holds by 
mutation and isolation, since the distribution of the forms was accu- 
rately recorded in 1884." On the other hand, if the new habitats differ, 
and there is variability in the original genotype corresponding with 
phenotypic characters which have survival value in relation to the 
differences of habitat, selection will play its part in determining the 
genotypes of the new species. Thus we can understand why it is that 
geographically isolated but clearly allied species may or may not differ 
in ' adaptive ' characters. We can also understand how it is that 
different closely allied species come to exist in the same geographical 
area but in different habitats — different ' ecological niches ' as they have 
been called — ^between which the chances of crossing are at a minimum, 
either with or without specific adaptation to the habitat. It depends 

"J. T. Gulick, 'Divergent Evolution through Cumulative Segregation.' 
Jniirn. Livn. Soc. Zool., 20. "1888. 

'' H. E. Crampton, Stvdips on the Variation, Distribution and Evolution 
of the genus Partula. Carn. Inst, of Washington, 1917. 


upon whether the random selection of individuals which originally 
colonised these habitats varied from the genotype of the parent stock 
in characters of survival value in relation to those habitats or not. 
Where two such habitats abut on one another and there is no specific 
adaptation to the two habitats inteiTnediates of hybrid origin are often 
found along the line of contact. 

In plants which are self-fertilised as a rule, but in which crossing 
is not absolutely excluded, numerous species may come to exist in the 
same geographical area and the same habitat, for the changes in geno- 
type brought about by the occasional crossing will be fixed and the 
phenotype purified, i.e. rendered more homogeneous, by the subsequent 
isolation for many generations of the different families. It is in this 
way that the ' elementary species ' of such a form as Erophila vulgaris 
(Draba verna) may be supposed to have originated. The differences 
between these are small but constant, and they must be regarded as true 
species. A variety, on this view, is a relatively transitory form which 
may at any time be reabsorbed by crossing into the general stock of the 

"We cannot in the present state of knowledge reject altogether the 
possibility of other modes of formation of new species. Geneticists 
differ as to the occurrence of radical alteration in the nature of a gene, 
or of new genes arising de novo in the genotype, i.e. as to the occun-ence 
of ' mutations ' in the naiTowest sense, while the interaction of conjugat- 
ing chromosomes by ' crossing over ' is well recognised. We cannot, I 
think, exclude the 'possibility of long-continued action of the environ- 
ment actually altering genes or even creating new ones. Thus we have 
only shifted the problem of variation back. We cannot as yet express 
variation in terms of chemistry and physics. We do not know what 
genes are. They may be definite chemical substances, they may be 
physicoi-chemical complexes, or some may be of one, some of the other 
nature. It is certain that a great number must always be present, and 
that the phenotypic ' characters ' must depend on their interaction. 
We cannot analyse a. race of organisms genetically except in respect of 
those genes that may be present or may be absent. Many genes must be 
present invariably or the working mechanism would break down — the 
organism would be non- viable — and these we cannot separate by breed- 
ing methods. These things being so, we cannot wholly exclude the 
hypotheses of orthogenesis and of ephanriosis as causes of evolution, 
much as we may dislike them on account of their vagueness. Modern 
genetic research has been able to demonstrate to a very large extent 
the exact correspondence between changes in phenotype and the drop- 
ping out and new combinations of genes. But it is impossible at 
present to demonstrate exactly how such possible processes as ortho- 
genesis or epharmosis may work. We know nothing of oi-thogenesis 
except as a phenotypic phenomenon, though we can conceive the possi- 
bility that the genotype tends to undergo continuous progressive change 
in one direction, change which might depend, for instance, on an 
orderly series of dissociations of molecular complexes, and show itself 
by coiTesponding orderly change of the phenotype in one direction. 
Such a hypothesis would explain certain phyletic phenomena, bat we 

K.— BOTANY. 253 

do not know that it is necessary to explain them thus : they may be 
brought about in other ways. Epharmosis in the widest sense means 
simply the continuous adjustment of the organism to its conditions of 
life. It is often used with reference to external conditions only, but 
we should not forget that adjustment to external conditions cannot be 
separated, except by logical abstraction, from the total adjustment of 
the organism, internal and external. The ontogenesis of each indi- 
vidual is a continuous process of adjustment of every part of the organ- 
ism to its internal and external environment. So much follows from 
tlie universal law that eveiy physical system constantly tends to\\ards 
equilibrium, and the law is abundantly illustrated in the development 
of plants. The particular state of relative equilibrium represented by 
the adult individual is, however, as we know, mainly determined by 
the stock of genes contained in the zygote from which it is developed, 
though partly by the particular environment in which it grows up. 
Epharmosis as a theory of phylogenesis must depend on the belief 
that the genes themselves can be considerably, continuously, and per- 
manently altered by forces outside themselves — their environment in 
the wide sense — and it must be admitted that the evidence for such a 
belief is neither very abundant nor very conclusive. We certainly do 
not know that genes cannot be so altered ; but we cannot point to cases 
in which it is possible either to assert, definitely that they are or to 
explain plausibly how they may be. On this side the Neo-Darwinian 
position has not yet, as it seems to me, been successfully attacked, 
though few biologists who are interested in these questions and not 
wedded to a particular theorj' of evolution would now be greatly sur- 
prised if it eventually fell. 

How, then, are we to make progress to a fuller knowledge of the 
necessarily interlinked problems of phylogenesis and ontogenesis which 
together make up the problem of evolution? On the one hand we 
have the theoretically indispensable genes, of whose nature we have 
no certain knowledge, though we know a great deal now about the effect 
on the phenotype of various combinations and omissions of some among 
them. On the other we have the phenotype, built up from the genes 
by long and complicated processes of physical and chemical action and 
interaction l^etween the genes and their derivatives, between the sub- 
stances and structures of the developing organism, and between these 
and the environment. Of these ontogenetic processes we still know 
extraordinarily little. Until quite recently physiology has kept its face 
averted from such problems, partly as a result of that imfortunate 
divorce from morphology which we have seen emphasised as a cardinal 
principle of botanical metliodology by distinguished botanists. It must 
be admitted that these processes are difficult to disentangle, and it is 
only the great development of physical chemistrv. and of the so-called 
biochemistry which depends so closely upon it, that has opened up 
dunng the last Iwcnty years the avenues through which we may 
approach the problems in this field with any prospect of success. Thirty 
years ago plant phvsiologists were mostlv either occupying themselves 
with measuring the ' functions ' of the organs of the adult plant under 
diffex-ent conditions, or tliey were caught in the toils of the ' stimulus 


and reaction ' conception, with its postulate of a series of mysterious 
mechanisms, supposed to have been built up by natural selection, and 
apparently inaccessible to further analysis. That this conception was 
a necessary stage in the development of plant physiology we need not 
deny; but some physiologists, like some of their morphological col- 
leagues, seem to have rather mistaken a transitory stage of development 
for an ultimate condition of research. Within the last few years we 
have begun to get developmental physiological studies of all kinds, and 
some of these are at last beginning to give us some insight into the 
formative processes which result in the differentiated structures of the 
plant body. A number of years ago Goebel, in his ' Experimentelle 
Morphologic,' sketched the connexion between vai-ious characteristic 
external forms of plants and definite factors of the environment. In 
1916 one of my predecessors in this chair. Professor Lang, clearly 
outlined the ideal of ' causal moi-phology , ' and indicated lines on which 
he thought such investigations should proceed. It is, I think, quite 
possible to claim that ' causal morphology ' in the widest sense is 
morphology proper; to say, with Professor D'Arcy Thompson, that 
since the problems of form are in the first instance mathematical prob- 
lems, and the problems of growth are essentially physical problems, 
' the morphologist is ipso facto a student of physical science. ' ^' More 
recently, again. Professor Priestley and his collaborators have attacked 
with considerable initial success the question of the actual sequence 
of events leading to the differentiation of various tissues, more par- 
ticularly endodermis, cork and cuticle, and have perhaps opened the 
way to a causal ontogenetic understanding of the whole of the tissue 
systems of the higher plant. ^* 

It certainly seems a far cry from a causal knowledge of these onto- 
genetic processes, common to whole families or large groups of plants, 
to an understanding of the way in which the genes which determine 
the difference of phenotype between one species and another, or one pure 
line and another, bring about the development of the corresponding 
phenotype. Superficially at least the kind of character whose origin 
in the ontogeny Priestley and his fellow -workers have been investigating 
seems to differ in nature from the kind of character which commonly 
separates species and varieties. The one is built into the constitution, 
and helps to determine the economy not only of one species but of a 
wide range of related species or of great groups of plants ; the other, so 
far as the vital economy of the plant is concerned, often seems to be of 
no importance at all. To use a metaphor which is perhaps just per- 
missible, the difference is like the difference between the plumbing of 
a house and the decoration of its facade, or between the lay-out and 

" D'Arcy Thompson. O71 Growth and Form.. 1917, p. 8. 

^' I am aware that there are some physiologists who think that this line of 
attack is overbold, that our existing knowledge of biochemistry and physiology 
does not justify a direct attempt to grapple with such problems. I can only 
say that I am not in agreement with this criticism. The results reached seem 
to me already to iustify the methods employed, tliough. of course, it may well 
be that some of Professor Priestley's first conclusions will have to be reviserl 
in the light of future knowledge. 

K.— BOTANY. 255 

construction of its rooms and passages and the lighting of these by a 
few large windows or by many small ones, where the illumination 
required is equally well secured by either aiTangement. I cannot here 
undertake a discussion of the justification for separating the ' characters ' 
of organisms into different categoi'ies, as Professor Gates, for instance, 
has tried to do,'' nor of the related controversy between those who 
believe that a ' particulate ' theory of inheritance such as that which 
has been worked out by the Mendelians is a sufficient basis for explain- 
ing all the phenomena, and those who advocate the claims of the organ- 
ism to be considered ' as a whole, ' which usually means in this connexion 
cytoplasmic inheritance, through the egg and perhaps sometimes also 
through the pollen. We cannot wholly exclude the possibility of 
cytoplasmic inheritance, or an eventual effect on the genotype of cyto- 
genetic characters ; but from the bi'oad position I am now taking I see 
no good reason for supposing that the ontogenetic development of what, 
for want of a better word, I may call ' organisatory ' characters differs 
essentially from that of the characters which are commonly used to 
separate species and which obey the Mendelian laws. If we define a 
gene as some substance contained in the zygote which is a factor in 
the determination of the phenotype, we must believe that all hereditary 
phenotypic characters alike, internal or external, separating species or 
common to a great many species, important, indifferent, or disadvanta- 
geous in the life economy, are developed from the genotype, i.e. from 
the total stock of genes, whether contained in the chromosomes or not, 
by an inevitable series of chemical and physical processes, modified, of 
course, by differences of environment. Now my point is this. "We can 
only hope to connect the genotype with the phenotype by tracing out 
these processes in detail, by following the ontogenetic history, not only 
in teiTns of the production of organs and tissues, of cell division and 
growth, but in terms of physical and chemical changes, of such processes 
as pressures and filtrations, oxidations and reductions, hydrolyses and 
condensations, reversible reactions and catalyses. And I think we may 
perhaps begin to find a way which will ultimately lead to an under- 
standing of how the genes produce the characters of the organism, and 
thus of the nature of the genes themselves, by following the trail which 
has recently been opened, by studying the detailed processes which lead 
up to the appearance of a structure, over and above, or, as one should 
perhaps more fittingly say, ' under and below,' that reaction of struc- 
ture upon process which we have been used to call the ' function ' of 
the structure. It is only in this way, as T believe, that we are hkely, 
for instance, eventually to get more light on the problem of ontogenetic 
recapitulation, which has certainly not been rendered easier by the 
Mendelian results and the conception of tho ' species cell.' 

The botanists of seventy years ago, notably that great pioneer Sachs, 
in the spacious_ days of the new ' wissenschaftliche Botanik ' in the 
'fifties and 'sixties of the last century, had in some ways a view of the 
problems of structure clearer than that of their immediate successors. 
It is plain that the ovei-whelming effect of the theory of descent on the 

'" R. R. Gates, ' Mutations and Evolution,' Xcw Phyt. \0, pp. 317 et sea 19''0 
1923 ' " 


imagination of biologists, the first brilliant results of the evolutionary 
interpretation of the doctrine of homology, led to an interesst in structure 
for its own sake which could have but a limited fertiUty. This interest 
has in the long run been mainly important because it has immensely 
increased our actual knowledge of structure. At the same time the very 
human but really quite irrational desire to find a ' use ' for everything 
led to a facile and sweeping application of the theory of natural selection 
quite out of accord with the patent facts of nature. The physiologists, 
the people who really remained interested in tracing causal sequences, in 
finding out ' how things work,' and who retained the only sound method 
of discovering this- — the experimental" method — were rather cut off from 
the interpretation of structure by the assumption that it was causally 
' explained ' if it were shown or even plausibly believed to be useful to 
the organism, and tended to confine themselves to measuring and deter- 
mining the conditions of processes, mainly in the adult plant. Thus 
there came about that separation of morphology from physiology which 
was no doubt a sound methodological principle for the restricted purpose 
of increasing our knowledge of certain series of facts, but which in its 
general effect on botany has, I fear, tended not only to disruption but 
to sterilisation. The effect of the divorce between moi^^hology and 
physiology was just as bad for physiology as it was for morphology. 
As little accustomed as the morphologist himself to envisaging the plant 
in its entirety as a continuously developing complex of substances and 
structures, the average physiologist tended to limit himself, as has 
been said, to the recording and measuring under different conditions of 
arbitrarily selected functions or processes, with the result that his work 
was often at least as arid as the conventional descriptions and correla- 
tions of the morphologist. Needless to say, there were honom-able 
exceptions in both camps. 

It is instructive in this connexion to consider a W'Ork which pro- 
fessed to deal with tissue structure in the light of function or process — 
a book thorouglily characteristic of the period I have been considering, 
the first edition being published in 1884 and the latest (the fifth) in 1918 
— I mean Haberlandt's ' Physiologischa Pflanzenanatomie. ' This book 
describes and discusses each of the tissue systems of the higher plant 
from the point of view of the part which it plays in carrying on the 
life functions of the plant as a whole, an excellent aim, and one which 
is, in the main, admirably carried out. The author makes a great 
point of adducing experimental evidence for the ' functions ' of par- 
ticular tissues wherever possible. But there is always the implicit 
assumption that evei-y tissue must h-ave a ' function,' must be of some 
' use ' to the plant, and in his effort to find that use Haberlandt is 
often compelled to rely on unconvincing argument from structure or 
from analogy, sometimes on little more than guesswork. It scarcely 
seems to occur to him that a tissue may have no specific ' use ' at all, 
that structures are developed as the result of the processes which take 
place in the developing plant, and do not necessarily perform a definite 
function which is useful to the whole organism. Many of them do, 
of course ; but to confine oneself to the search for such ' functions ' is 



not the right way to get a real understanding of the structure of a plant. 
At last year's meeting of Section K the President, Professor Dixon, 
showed reason to believe that the sieve tubes of the phloem are in the 
cases which he considered quite inadequate for the purpose of carrying 
organic substances such as sugars from the leaves to the regions where 
they are used or stored, as, for instance, potato tubers. What, then, 
we may ask, is the ' function ' of sieve tubes ? It seems to me that 
we should not close our minds to the possibility that they may have 
no ' function ' in this sense, that cells having the characters of what 
we call sieve tubes may quite conceivably be formed simply as the result 
of the processes going on in certain tracts of developing tissue, without 
subsequently playing any essential part in the economy of the plant. 

The analogy of the machine made by man, in which each part is 
constructed with a definite object, may be very misleading if we allow 
ourselves to forget that an organism is not constructed in that way at 
all, but is the outcome of blind, inevitable processes, and may produce 
parts which are useless or even harmful to it, provided that the whole 
is still able to ' carry on ' and reproduce itself in its actual conditions 
of life. We should always approach structure through development, 
the mechanics, physics, and chemistiy of growth and differentiation. 
It is only thus that we can ever hope to ' explain ' structure in any real 
sense. It is only thus, I believe, that we can ever hope to get back 
to the real nature of the genes. 

The ' functions ' of the vanous organs and tissues — ' biological ' and 
' physiological ' functions in the old sense — will then appear in their 
proper places as those properties or activities which actually contribute 
to the growth, maintenance, and reproduction of the plant — for the 
plant must grow, maintain, and reproduce itself, or the race will die. 
The main essential activities are sufficiently obvious, and we can some- 
times say with confidence that if such and such a structure were absent 
or such and such a process did not take place, these essential activities 
would be fatally impaired. When a failure of this kind takes place 
owing to change of genotype or of environment we rarely see it, for it 
brings extinction in its train. ^° For the most part we cannot know 
that apparently useful characters could not have been dispensed with, 
or that metabolic processes might not equally well have taken some 
other course so far as the success of the plant in the struggle for exist- 
ence is concerned, while in regard to a multitude of characters there is 
not only no proof but not the smallest reason to suppose that they 
have now, or ever did have, any ' survival value ' at all. Like all 
structural features, they are simply products of the plant's activity, 
though they react in turn to a greater or lesser degree on that activity. 
Differentiation and so-called division of labour are the inevitable result 
of increase in size, and of the ensuing different relations of parts of 
the body to one another and to the surrounding medium. Every type 
of plant, whether it differs from its parents or not, does and must 

^'' In his ' lethai factors' the Mendelian geneticist has, however, succeeded 
in discoveringr definite heritable entities which lead to such failure and thus 
to death. The real nature of these may be eventually ascertainable alone the 
line of research indicated above. 

T 2 


' adapt itself ' during its development to its conditions of life. That is 
to say, it does and must react to the forces, external and internal, acting 
upon its several parts, and the result of the reaction must be to bring 
it into closer equilibrium with the whole of those forces. It is some-' 
times forgotten that ' adaptation ' in this sense is a wide physical con- 
ception which does not imply that the whole of the characters of an 
organism are ' useful ' to it in the sense in which all the parts of a man- 
made machine are useful. 

Thus we conclude that the central and vital part of botany as a 
science is, and must be, the study of process^ which creates and 
modifies structui'e as well as of process which is in its turn deter- 
mined by structure. In reality no line can be drawn between processes 
of these two kinds, for the development and metabolism of the plant 
foi-m a continuous connected history in wliich process and _ structure 
continually act and interact. Nevertheless, the ' physiological func- 
tions ' of adult structures certainly have a special position in that the 
processes of which they consist are, like the adult structures themselves, 
the cun-ent terms of ontogenetic development, the cun'ent stages of 
full expression of the given genotype under the given conditionsof life. 

The separation of morphology and physiology no doubt ultimately 
takes origin from the two distinct types of human interest in living 
organisms, characteristic of diffei'ent types of mind, the one attracted by 
the forms, formal relationships and classification of objects, the other 
by the understanding of process, the knowledge of working. The one 
naturally observes and classifies, the other observes and experiments. 
This kind of separation, clearly enough seen among the older naturalists, 
has been greatly enhanced on the one hand by the entliusiastic effort 
to trace phylogeny consequent on the acceptance of the doctrine of 
descent, on the other by the continuous complication of the physical 
and chemical knowledge and technique required by the study of physio- 
logical processes. It has had a profound effect on the teaching of 
botany during the past forty years. Botanists whose personal research 
lay in the one field have been less and less able to take an intelligent 
interest in the other, even' if they could understand the terms in which 
the results were expressed. The student has perforce come to regard 
and to study the two fields as wholly distinct, with very few points of 
contact, and his attention has been directed primarily to morphology 
largely because it is so much easier for the beginner to examine and 
cut sections of plants and draw" pictures of tliem than to study the 
processes which go to the making of them. Too little serious effort 
has been made to overcome the difficulties of teaching students to study 
process. The physiologists themselves have been too much absorbed 
in their apparatus to consider the bearing of their subject on general 
botany. In recent years the rise of new branches of study, such as 
cytology, genetics, and ecology, has added to the distraction of the 

The result has been to separate botany into disconnected parts and 
failure to give the student any unified notion of the subject. It is 
unnecessary to say that the growth of knowledge inevitably brings in 
its train ever-increasing specialisation in research, but that fact in no 



way absolves the teacher who is responsible for the introduction of 
students to the subject from the duty of displaying it as a whole, and 
this he can only do by making its most vital part, the study of process, 
the key to his exposition, by representing all structm'e as the result of 
process, and, in its turn, as limiting and directing process, rather than 
by concentrating the student's interest on structure and the comparison 
of structure for its own sake. It seems to me most misleading to 
represent morphology (in the sense in which it has come to be used) and 
physiology as if they v/ere equivalent branches of the subject between 
which the attention of students should be divided. It is only the most 
superficial view that can regard them as equivalent. Structures ai-e the 
end results of processes, and to understand them we must study process 
by observation and experiment. It is unnecessary to remark that 
thorough and accurate acquaintance with facts of structure is inci- 
dentally essential. But to claim the larger portion of the student's 
time and energy for the work of becoming acquainted with the details 
of structure of all the various groups of plants involves, in my view, 
a very serious misdirection of effort. 

There should be no division of elementary botany into morphology 
and physiology. In advanced work there must, of course, be differ- 
entiation, as there must in research, not into morphology and physio- 
logy, but into a great number of groups of connected phenomena, 
because of the vast number and complication of the phenomena of the 
plant world. Some minds find their satisfaction in studying structure 
for its own sake, so to speak, and in comparing the structm-es studied. 
Their research will naturally lie in that direction, and it is certain to 
increase, as it has in the recent past already vastly increased, our 
knowledge of the detailed facts of structure of the plant kingdom, 
to reveal unsuspected relationships, and to establish probabilities as to 
the lines evolution has followed. But this knowledge in itself, con- 
sidered in relation to the science as a whole, is, and must necessarily 
remain, superficial. Its conclusions even in regard to the lines which 
evolution has followed can at the best never attain to more than a con- 
siderable degree of probability. And its metho<ls and aims can never 
explain structure in any real sense. For that a study of process is 

The great development in morphological knowledge, especially of 
what I have called the middle grades of the plant kingdom, and of the 
great groups of fossil plants which belong to these grades, has, as we 
must all recognise, immensely increased om' acquaintance with the struc- 
ture of the plant world. It was a natural development of interest in 
the past history of plants, stimulated and directed by the acceptance 
O'f the doctrine of evolution. Looking back upon the history of botany 
during the past half-century we must be grateful to this movement, 
and proud of the leading and distinguished parti our countrymen have 
played in its development-. But I cannot think that it has had a wholly 
good influence on the progress of botany, particularly on botanical 
teaching and research in this country. This has remained too long 
dominated bv the ideal of tracing phylogeny, has given far too much 
time to the detailed morphology of the different groups which make up 


the plant kingdom, and has correspondingly neglected the newer know- 
ledge of process which must be the main avenue to a deeper under- 
standing of plants. Fortunately there are now many signs of impend- 
ing change. Meanwhile the younger workers, dissatisfied, especially 
during the last two decades, with the older outlook, have tm'ned more 
and more to specialised physiological research, to mycology or to 
genetics, with their outlets on practical life, but often without the 
grounding that only a thorough grasp of the essentials of the subject 
can give. One of the results has been that botany has to a large extent 
become disintegrated, workers in particular parts of the subject having 
little understanding and less interest in the results of their fellow- 
workers in other parts. It may be said that this is an inevitable result 
of the complication of the subject, and no doubt that is partly true. 
There is a type of professional worker who, having once got immersed 
in a particular line of research, resolutely refuses ever to come oiit of 
his groove and take a broader view. The subject no doubt owes a 
great deal of its energetic detailed development to such workers. But 
if botany, as the science of plants, is to retain any meaning as a whole, 
somebody must retain the power of looking at it as a whole. And if, 
as teachers, we fail to keep touch with the newer developments, and 
are consequently no longer able to focus the whole subject from a 
viewpoint determined by current knowledge, this power will come to 
be possessed by fewer and fewer botanists, and the subject will definitely 
and finally break up into a number of specialised and unco-ordinated 

Do we want that to happen? I think that most botanists would 
answer ' No ! ' I do not think there can be any question that the most 
advanced research worker, as well as the student who never goes on to 
i-esearch, benefits substantially by having had a training which is at 
once the broadest and the most vital that is possible. As science con- 
tinuously advances and necessarily specialises, the unexplored fields 
which lie between the traditional lines of research become of more and 
more relative importance. They cannot receive adequate attention — 
the student can, indeed, hardly become aware of their existence — unless 
his introduction to the subject is continuously informed by the widest 
outlook and the clearest apprehension of the essential relations of the 
phenomena of plant life. 





In consonance with the general aim of the British Association, the 
special purpose of our Section is the advancement of educational science. 
The Section owes its existence to a group of persons who saw clearly 
that in education, as in all the great fields of practice, there are, and 
must constantly arise, problems that can be solved only by patient 
application of the methods of science. The range and importance of 
these problems were illusitrated by Sir Eobert Blair in his Presidential 
Address to the Cardiff Meeting, but I do not propose working over 
any of the ground which my distinguished predecessor then surveyed. 
My intention is to take advantage of the customary right of a President 
to travel outside the strict bounds of his science and to deal with 
questions which, the results of inquiry within its limits illuminate but 
do not themselves answer. 

To a President of Section L the temptation to use this wider liberty 
must always be strong ; for, however far the scope of educational science 
may extend, the critical educational issues will always lie beyond it. 
If the term ' education ' is used, as it sometimes is, to include all the 
influences which affect mind and character, it is obviously much more 
than an applied science. But so it is if the term is restricted, as I 
shall restrict it, to those foi-mative influences which are brought to bear 
with some degree of purpose upon the minds of the young. In its 
origin education is a biological process found not only in all humaa 
societies, however primitive, but even in a rudimentary form among 
the higher animals. By calling it biological I mean that it is a native, 
not an acquired expression of the race's life, correlative to the race's 
needs ; that it does not wait for deliberation to call it into existence or 
for science to guide it, but has the inevitabihty of behaviour rooted 
in instinct. Thus, as I have argued elsewhere, educational science 
stands to education in much the same relation as hygiene stands to the 
physical life; it is a critic rather than an originator; it scrutinises and 
pronounces judgment upon ways and means, but does not and cannot 
prescribe the general direction which the educational process shall take. 
At most it can only help to stabilise the movement by lifting it from 
the level of instinctive impulse or vague opinion to the plane of ends 
clearly envisaged and consistently pursued. 

What is it, then, that determines the general character of the 
educational process at a given point in the history of a human society ? 


The answer is, briefly, that the same dan viial which brought the 
society to that point urges it so to train its young that they may 
maintain its tradition and ways of life. But this statement needs an 
important qualification. The consensus of a society never approves 
of all that goes on within its borders, and among the activities it treats 
as admissible sets a higher value upon some than upon others. Accord- 
ingly the biological impulse which is the mainspring of education tends 
to selecifc for the training of the young those activities which society 
judges, consciously or instinctively, to be of most worth. It follows 
that the education a nation gives its children is, perhaps, the clearest 
expression of its ethos and the best epitome of its scheme of life. Thus 
the ideas of too many of our Georgian forefathers upon the education 
of the masses corresponded faithfully with tlieir belief in the great 
principle of subordination about which Johnson and Boswell talked so 
often and agi'eed so satisfactorily. One remembers, for instance, how 
hotly Miss Hannah More denied the scandalous rumour that she was 
teaching the poor of Cheddar to write ! Similarly, the liberal curri- 
culum of our elementary schools reflects the prers'alence to-day of a 
widely different view of the nature and purpose of society. One is 
tempted to add that the misgivings v.'ith which that cuiTiculum is, here 
and there, still regarded may be largely due to the ideas of the 
eighteenth century dying hard in the twentieth. 

If what children are taught is but an expi^ession of the general 
mind of their time and nation, what guarantee is there that education 
shall be an ins,trument of social progress and not of retrogression ? It 
must be acknowledged that there is no such guarantee. Among the 
ideas and ideals, the modes of feeling and action current in a society, 
it is possible for the general mind to approve the worse rather than the 
better, and so to give a fatally wrong turn tO' the training and outlook 
of whole generations. Have not some of the great tragedies of history 
thus come about? Such disasters are, in fact, avoided only where the 
predominant mind of a people has a sufficient sense of the things that 
belong to its peace. It follows that the ideal ' educational authority ' 
would be neither the teacher with forty years' experience nor the 
■ brilliant exponent of educational science, but the phronimos — the per- 
fectly wise man who had grasped fully the meaning of man's existence, 
could see to the bottom of his people's life, appraise justly all its 
movements, and discern with sure eye its needs. Assuming that he 
could also communicate his vision to his fellow-citizens, we should do 
as well under his guidance as the imperfections of humanity would 

Unhappily the true fhronimos appears but rarely, and when he 
comes bears no unchallengeable certificate of authenticity. If he is 
not at hand or is unrecognised, we ordinary men and women must apply 
to our problems the best insight we can attain, trusting that in the 
conflict of sincere opinions the soundest will in the end prevail. For 
example, I have referred to the great change in the conception of 
popular education which has taken place in our time, and have con- 
nected it with the steadily growing belief, first, that every member of 
society has an equal title to the privileges of citizenzship ; and, secondly, 


that the corporate strength of society should be exerted to secure for 
him actual as well as theoretical possession ol his title. How the 
movement based upon that belief will ultimately affect the happiness 
of our people no one can with certainty foresee; nevertheless, if one is 
interested in the wider educational issues one must define one's own 
attitude towards it. I am, therefore, bound to record my opinion tha.t 
in its main tendency it ought wholeheartedly to be accepted. I think 
this cliiefly because it seems to be inspired by the Christian principle of 
the immense value of the individual life, or, if you prefer to put it 
so, by the Kantian principle that no man ought to be treated merely as 
a means but always also as an end in himself. But if the movement 
is accepted, public education must correspondingly assume a character 
which would follow neither from the principle of subordination nor 
from the principle of laissez fairs. The view I submit is that the educa- 
tion of the people should aim at enabhng every man to realise the 
greatest fullness of life of which he is by nature capable — ' fullness ' 
being, I add, measured in terms of quality rather than of quantity, by 
perfection of form rather than by amount of content. That view is the 
basis of all I have to say. 

Having adopted it, I am compelled at once to face the question, 
What are the essential qualities of a full life? It is just here that the 
judgment of the phronimos would be invaluable. In his absence I 
must hazard the conjecture that he would approve of at least the 
general drift of the following observations. During the last century 
we learnt, following Darwin, to look upon all biological phenomena 
as incidents in a perpetual struggle wherein the prizes to be won or 
lost were the smwival of the individual and the continuance of his 
species. Fro^m this point of view there: could be only one object of 
life, one causa, vivendi, namely, to continue living, and the means by 
which it was to be attained were adaptations to environment achieved 
by an individual, and perhaps handed on to its offspring, fortunate 
germinal variations, or lUcky throws of the Mendelian dice. It was 
natural, if not logically necessary, that the doctrine should fuse with 
the view, as old as Descartes, that life is but an intricate complex of 
physico-chemical reactions. Upon that view, even to speak of a 
struggle for existence, is to use a metaphor admissible only on account 
of its picturesque vigour; when we study the forms, processes, and 
evolution of living beings we are spectators merely of the operation 
of physical and chemical laws in peculiar forms of matter. Thus the 
occurrence and the phenomena of life are finally and wholly to be 
explained in terms of the statistical distribution of positive nuclei and 
their satellite electrons. 

These ideas, in either their more moderate or their more drastic 
form, affected the attitude of men towards matters lying far outside the 
special province of biology. National policies have been powerfully 
influenced by them, and it has been widely held that the education of 
children should be shaped mainly if not solely with a view to 
' efficiency ' in the struggle for existence. It is, therefore, relevant to 
point out what tremendous difficulties are involved in their thorough- 
going application. I will not speak of those which have driven 


physiologists of high standing to reject the mechanistic theory of life as 
unworkable, for I am not competent to discuss them, and they do not 
bear directly upon my argument. It will be both simpler and more to 
our purpose to raise, as William James did in the last chapter of his 
great treatise on psychology, the question of the higher aesthetic, moral 
and intellectual qualities and achievements of man, and to ask how 
these are to be brought under the conceptions before us. To be fair 
we will not press the question how the emergence, say, o-f Beethoven's 
Fifth Symphony is to be explained in terms of physics and chemistry ; 
for even the most sitalwaxt mechanists hardly expect that it will actually 
be done; they only believe that conceivably it could be done. But it 
is both fair and necessary to ask how the things of which the symphony 
is typical can be accounted for on the principle of sm-vival-value. 
James, facing this question with characteristic candour, felt bound to 
admit that they have ' no zoological utility. ' He concluded, therefore, 
that the powers and sensibilities which make them possible must be 
accidents — that is, coUaiteral consequences of a brain -structure evolved 
with reference not to them but only to the struggle for material exist- 
ence. The premises gi'anted, I do not see how the conclusion can be 
avoided; but surely it is extremely unaeceptable. If, with Hei-bert 
Spencer, we could regard art merely as sometliing wherewith to fill 
agreeably a leisure hour, we might be satisfied by the hypothesis that 
our sensibility to beauty in form, in colour and in sound, is an ' epi- 
phenomenon ' having no significance in relation to the real business 
of hfe. But when we think of men whose art was in truth their life, 
and consider how eagerly the better part of mankind cherishes their 
memory and their works, it is next to impossible to be satisfied with 
that view. Or take the case of science. Votaries of pui'e science often 
seek to justify their ways to the outer world by the argument that dis- 
corveries which seemed at first to have only theoretical interest have 
often disclosed immense practical utility. It is a sound enough argu- 
ment to use to silence the Philistine, but would the pursuit of science 
lose any whit of its dignity and intrinsic value if it were untrue ? For 
instance, would any member of this Association refuse his reverence 
to the great work of Albert Einstein even if it were certain that, in the 
words of the famous toast, it would never do anybody any good? I will 
not lengthen the argument by extending it to the saints and the philoso- 
phers, for its point should be already sufficiently plain. The activities 
of ' our higher gesthetic, intellectual and moral life ' have such intrinsic 
worth and importance that to regard their emergence as accidental and 
biologically meaningless is outrageously paradoxical. They must be 
at least of equal significance with anything else in man's life, and may 
not unreasonably be held to contain the clue to life's whole meaning. 

It may be helpful to put the conclusion in other language. Man's 
life is a tissue of activities of which many are plainly conservative in 
nature. By this I mean that their function is directly or indirectly 
to maintain the existence of the race and the individual. Agriculture, 
industry, defence, medicine, are obvious instances of the type, and the 
list could easily be extended. But there are other activities — I have 
taken art and pure science as capital instances — whose character, in 



contrast with the fonner, is best indicated by the term creative. The 
point 1 have tried to make is that in any sane view of human hfe as 
a whole the creative must be regarded as at least as significant and 
important as the conservative activities. 

Having travelled so far one must perforce go farther. Purely 
conservaitive and purely creative activities, if indeed they exist, are 
only limiting instances; in most, if not in all activities, the two 
characters are interfused. For example, the motive of pure science is 
unmistakably creative, yet its extrinsic consei-vative value is unlimited ; 
on the other hand, the vast industrial organisations of to-day exemplify 
activities which, though conservative in their genesis, yet have developed 
the creative character in an impressive degree. Considerations of this 
kind prepare one to see that the higher creative life, far from being 
merely a splendid accident, is really the clearest and purest expression 
of the essential character of life at all its levels. The poets are, as 
the Greeks called them, the supreme makers, for all making has in it 
something of the stuff of poetry. In short, there is no life, however 
humdrum, however crabbed by routine, which is not permeaited by 
the self -same element whose inflorescence is literature, art, science, 
philosophy, religion. 

The argument might rest here, but I am constrained to carry it 
still farther. I find it difficult to believe that whait is true of human 
life in its conscious aspect is not in some sense true of life as a whole. 
Competent observers, for instance Professor Garstang, hold that in 
the animal world there is something strictly comparable with festhetic 
creation, but I have in view an idea of wider scope. It is the idea 
developed with whimsical seriousness by Samuel Butler, namely, that 
the variations or mutations which in one form or another every theory 
of evolution postulates, are in essence acts of creation homologous 
with human inventions and works of art — ^that if, for example, we com- 
pare the emergence or modification of an animal organ, say, with the 
creation of Hamlet or the invention of the petrol-engine, the differences 
between the two things, vast as they may be, have yet less significance 
than the fundamental resemblances. This view, which is implicit in 
some of the older philosophies, is central in the speculations of 
M. Bengson; it is congruent with the ideas of several modem thinkers 
who are hardly to be called Bergsonians ; and I think it is beginning to 
invade orthodox biology. It is certainly incompatible with the mechan- 
istic theory of life, but nevertheless leaves room for all that the up- 
holders of the theory are entitled, and (I venture to think) are really 
concerned to claim. That the life of an organism, can be analysed 
exhaustively into physical and chemical factors is a proposition which 
it would be extremely rash to dispute; but it is, I think, plainly untrue 
that the behaviour of the organism as an integi-aled unit remains within 
the categories of physical science. Here I take my stand with Pro- 
fessor Alexander and Professor Lloyd Morgan, holding that life is 
not the mere sum of the physico-chemical reactions that occur in an 
organism but a constitutive quality of the complex of those reactions — 
a quality not ' epiphenomenal,' but substantial in the sense that it 
makes a difference to what Professor Stout has called the executive 


order of the world. In Dr. Lloyd Morgan's happy phraseology, the 
behaviour of an organism involves chemical and physical factors, but 
depends on the ' emergent ' quality which may properly be distin- 
guished as life. If that be the case, life may well exhibit throughout 
its i-ange the creativeness which, I have suggested, is one of its essen- 
tial characters. My educational argument does not stand or fall in 
accordance with the tnith or the falsity of this view ; but if the view 
were well founded the significance of the creative element in human 
life would be made clear beyond dispute, and the general force of the 
argument would be greatly strengthened. 

The foregoing discussion has wandered some distance from the 
class-room. Nevertheless it has, I think, a close bearing upon the 
questions what ought to be taught and in what spirit the teaching 
should be given. The- curriculum, we have seen, always will be a 
partial reflection of the actual life and traditions of a community, and 
ought to reflect all the elements tlierein which have the greatest and 
most pei-manent value and significance. Without doubt these will, in 
general, be the things that have the highest significance and value for 
the human family as a whole, but there can hardly be said tO' be a 
common human tradition. There exists, it is true, a common European 
tradition based mainly upon the Gr£eco-Eoman and Christianity, and 
it is vastly important for the happiness of the world to deepen and vivify 
men's consciousness of it. But even this lacks the concreteness needed 
to form the basis of popular education — as is seen by contemplation of 
France and England, two nations that have grown up in it and have 
influenced one another strongly for centuries, and yet have perfectly 
distinctive cultures. In short, a nation is the largest social unit whose 
etJios has the necessary individuality. Hence, though we should aim 
at making our young people ' good Europeans,' we can do so only by 
shaping them into that particular brand of good Europeans who are 
rightly to be called good Englishmen. Their education should be, in 
Professor Campagnac's illuminating phrase, a 'conversation with the 
world,' but the conversation must, in the main, be conducted in the 
native idiom. Hence the importance of fostering in our elementary 
schools the special traits of the English character at its best ; of giving 
English letters a chief place among the studies of our youth ; of cherish- 
ing the English traditions in the arts and crafts, including our once 
proud ai-t of music ; even (as Mr. Cecil Sharp rightly urges) of reviving 
the old dances which were so gracious and typical an expression of our 
native gaiety and manners. Lest this contention should be misunder- 
stood I add thait I preach neither the hateful doctrine that what is 
foreign should, as such, be excluded, nor the ignorant and presumptuous 
doctrine that what is our own is necessarily the best, and that we have 
nothing to learn from other peoples. The whole burden of my argu- 
ment is that the things which have universal human value are the 
things of most importance in education. But the universal can be 
apprehended only where it lives in concrete embodiments. In the 
cases we are concerned with, these are elements or organs of a national 
culture; and the only national culture to which a child has direct and 
intimate access is his own. He should be taught to see, as opportunity 


permits, how much of it is dei-ived from the common European tradi- 
tion and how much it owes to the influences of other national cultures; 
but it should, in its concrete individuality, be the basis of his education. 

Lastly, I have urged that among the strains or currents in a national 
tradition the highest value belongs to those that are richest in the 
creative element. These are themselves traditions of activity, practical, 
intellectual, aesthetic, moral, with a high degree of individuality and 
continuity, and they marlj out the main lines in the development of 
the human spirit. Consider what man has made of poetry and what 
poetry has made of him ; wha.t a noble world he has created out of the 
sounds of vibrating reeds, strings, and brass; think of the expansion ol 
soul he has gained through architecture and the arts of which it is the 
mother and queen ; of the achievements of liis thought, disciplined into 
the methods of mathematics, the sciences and philosophy. Do we not 
rightly measure the quality of a civilisation by its activities' in such, 
directions as these? And if so, must not such activities be typically 
represented in every education which offers the means to anything that 
can properly be called fullness of life ? 

If the force of the argument be admitted, the principles of the curri- 
culum, about which so' much has been written, take a clear and simple 
shape. A school is a place where a child, with his endowment of sensi- 
bilities and powers, comes to be moulded by the traditions that have 
played the chief part in the evolution of the human spirit and have the 
gi-eatest significance in the life of to-day. Here is the touchstone by 
which the claims of a subject for a place in the time-table can be infallibly 
tested. Does it represent one of the great movements of the human 
spirit, one of the major forms into which the creative impulses of man 
have been shaped and disciplined? If it does, then its admission cannot 
be contested. If it does not, it must be set aside; it may usefully be 
included in some special course of technical instruction, but is not 
qualified to be an element in the education of the people. 

The same criterion may be applied to the methods by which the 
subjects of the curriculum are taught. We are constantly told that the 
' educational value ' of a subject lies in the mental discipline it affords, 
and, from this point of view, a distinction is made between its educa- 
tional value and its import as an activity in the greater world; thus 
geometry is taught as a training in logic, the use of tools as ' hand and 
eye training,' and so forth. From the standpoint I ask you to adopt that 
distinction is unjustifiable and may be dangerously misleading; it has, I 
fear, often been a source of aridity and unfruitfulness in school teaching. 
The mistake consists in supposing that the disciplinary value can be 
separated from the concrete historical character of the subject as a 
stream of cultural tradition. The discipline of the school workshop 
consists in using the tools of the craftsman for purposes cognate with 
his and inspired by his achievements. It is because this has not always 
been done that methods of ' manual training ' have too often falsified 
the expectations of their advocates. Similarly the discipline of school 
geometry consists not in mastering an abstract scheme or formula of 
argumentation, but in steeping one's mind in a certain noble tradition of 
intellectual activity and in gradually acquiring the interests, mental 


habits and outlook that belong to it. To say this is not to minimise 
the importance of discipline or to expel from school studies the austerity 
which the grave old word suggests. How, for instances, could it be 
said that our school mathematics represented truly the genius of real 
mathematics if we neglected the element of laborious accuracy and pre- 
cision of thought which are essential to it? What is insisted on is that 
the several forms of mental discipline are characters of concrete types 
of creative activity, practical, aesthetic, intellectual, and that they influ- 
ence the mind of the learner favourably only in so far as he pursues 
those activities as adventures of the human spirit, laborious yet joyous 
and satisfying, and pursues them after the manner of the great masters. 
In short, trae discipline comes simply by tr}'ing to do fine things in the 
fine way. 

The foregoing principles, stated in a necessarily brief and crude 
manner, are open to misconceptions against which it is desirable to 
protect them. In the first place, it may seem that I am designing the 
education of the people upon a scale which may be magnificent but is 
certainly impracticable. Now I recognise the need of following the 
advice of a wise official friend who bids one always to bear in mind the 
magnitude of the educational problem — to remember the slum school 
and the remote village school as well as the happily placed schools of 
rich and progressive urban authorities. It is easy, no doubt, to form 
extravagant expectations, and by seeking to do too much to achieve 
nothing solid at all. But the argument is concerned far less with the 
standard to which school studies may be pursued than w-ith their proper 
qualities and the spirit that should inspire them. In particular, it is 
directed against the attitude expressed recently by a public speaker who 
asked what good is poetry to a lad who will spend his days in following 
the plough and spreading manure upon the fields. Against this attitude 
it urges that a man's education, whatever his economic destiny, should 
bring him into fruitful contact with the finer elements of the human 
tradition, those that have been and remain essential to the value and 
true dignity of civilisation. This ideal does not assume advanced 
scholarship or gifts beyond those of ordinary mortals ; it implies merely 
that the normal human sensibilities and powers should be directed along 
the right ways. 

But, it may be obi'ected, granted the soundness of the ideal as an 
ideal, tlie shortness of school life still makes it impracticable. This is 
a criticism to be treated with respect. It is true that a study, to be of 
real value, must be carried far enough and followed long enough to 
make a definite and lasting impression. It is also true that some studies 
can hardlv produce their proper effects at all imtil a certain level of 
maturitv has been reached. For example, there is much of vital 
moment in science which evokes no response in a pupil before the age 
of adolescence. But what is to be deduced from these admissions? 
Surely the conclusion, which the public mind is slowly accepting, that 
so long as children leave school for good at fourteen some of the best 
fruits of education will be unattainable and the security of the others 
precarious. It is not merely a question of length of time, but also, and 
even mainly, of psychological development. The more carefully youth 


is studied the more significant for after-life the experience during the 
years of adolescence is seen to be. Its importance is not a modern 
discovery; for even the primitive races knew it, and the historic Churches 
have always taken account of it in their teaching and discipline. But 
the problems of what has ever been a fateful period have acquired under 
modern conditions of life a new urgency. Parents and teachers have 
worried over them, devoted club-workers have wrestled with them, 
novelists and psychologists have studied them. In connection with the 
psychologists, mention of Dr. Stanley Hall's monumental work is as 
inevitable as it is now superfluous ; reference should, however, be made 
to the recent memoir in which Dr. Ernest Jones has freshly illuminated 
the old idea that the onset of adolescence marks a definite break and 
recommencement in mental growth. Especially interesting is the 
parallelism he establishes between the successive phases of childhood 
and the corresponding phases of youth. But though in a sense the 
adolescent retravels a psychological route which he has already traversed 
in childhood, he is, of course, capable of vastly deeper and wider vision 
and experience. The case for universal education beyond the age of 
fourteen depends ultimately upon the importance of shaping his new 
capabilities in conformity with the finer traditions of civilised life. 
Public opinion, regi-etting the generous gesture of 1918, has not at the 
moment accepted the larger view of the mission of education; but as 
the nation learns to care more for the quality of its common manhood 
and womanhood and understands more clearly the conditions upon 
which that quality depends, the forward movement, now unhappily 
arrested, will certainly be resumed. For that better time we must 
prepare and build. 

There is another objection to which I should think it unseemly to 
refer if it were not a stumbling-block to so many persons of srood will. 
A liberal public education will, they fear, make people unwilling to do 
much of the world's work which, though disagreeable, must still be 
carried on. The common sense of Dr. Johnson gave the proper reply 
a hundred and fifty years ago. Being asked whether the establishment 
of a school on his friend Bennet Langton's estate would not tend to 
make the people less industrious, ' No, sir,' said Johnson. ' while learn- 
ing to read and write is a distinction, the few who have that distinction 
may be the less inclined to work ; but when everybody learns to read 
and write it is no longer a distinction. A man who has a laced waist- 
coat is too fine a man to work ; but if everybody had laced waistcoats, 
we should have people working in laced waistcoats.' 

Lastly, complaint may be made that in all this discourse about the 
finer values nothing has been said about the ordinarv utilities, and the 
ironical may ask whether it is an error to suppose that the education 
of the people should furnish them with useful knowledge and abilities. 
Now the test of utility which the plain man applies to education is, in 
principle, sound and indispensable; it is, in fact, congruent with the 
biological origin and function of the educational progress. The only point 
doubtful is whether the test is always based upon a sufficiently broad 
idea of utility. The only satisfactory definition of the useful is that it 
contributes definitely and positively to fullness of life. From that point 


of view it is useful to teach a ploughboy to love poetry and not useful 
to teach a public schoolboy to hate Greek. This is not, I remark, an 
argument against teaching a subject whose disappearance from our 
education would be an irreparable disaster. It means merely that the 
literatures of the ancient world, when taught, should be taught in such 
a way as to contribute positively to the quality of a modern life. But 
the term ' useful, ' according to the definition, certainly includes utility in 
the narrower sense. The daily work of the world must be kept going, 
and one of the essential tasks of the schools is to fit the young to carry 
it on under the immensely complicated conditions of present-day civilisa- 
tion. Tliere is no incompatibility between this admission and the 
general line of my argument. The only relevant limitation imposed by 
the argument is that what is conservative in purpose shall be creative- 
in its method and, being so, shall embody some dignified tradition of 
practical, aesthetic, or intellectual activity. The condition may be 
satisfied by a technical education based upon many of the great historic 
occupations of men and women — for example, upon agriculture, build- 
ing, engineering, dressmaking — provided that inspiration is sought from 
the traditions of the industry or craft at their noblest. Anyone who has 
a wide acquaintance with the schools of the country will know some 
whose work accords with these high requirements and gives to prac- 
tically minded boys or girls an education truly liberal in aim — that is, 
an education which tends to free their minds from bondage to sordid 
tastes and petty interests and to make therh happily at home among 
large ideas and activities of wide and enduring importance. "What these 
schools have done and are doing should be borne in mind when Article 10 
of the Act of 1918 comes again to life or is replaced by legislative pro- 
visions of still bolder design. To conceive ' secondary education for all ' 
as meaning ' the grammar school curriculum for all ' would be to make 
a most serious blunder. The only mistake more serious would be to 
exclude adolescent boys and girls, even of the humblest station, from 
any essential part, of the national inheritance of culture. But this error 
may be avoided while full account is vet taken of the far-reachine differ- 
ences in the talents and ingenium of individuals and the rich diversity 
of the valuable currents, intellectual, practical, and pesthetic, in the life 
of the community, of which any one may be made the basis of a course 
truly liberal in quality. 

The eminent philosopher. Professor Giovanni Gentile, now Minister 
of Public Instruction in the Italian Government, has in more than one 
brilliant work — notably in his eloquent lectures on ' The Eeform of 
Education ' — expounded views largely congruent with those expressed 
in this paper. I welcome his agreement not merely because it may be 
presumed that the principles he upholds are the principles informing 
his administration, but even more because the philosophical positions 
from which we start are widely different. Signor Gentile holds, as I 
do, that the proper aim of education is to shape the activities of the 
individual spirit in accordance with the best traditions of the human 
movement. In particular, he does not shrink from insisting that the 
simplest instruction in the primary schools should be offered in the true 
spirit of culture. And he also maintains that the eduoa^tion of thp 


people must be national in its general setting. Indeed, I venture to 
think that he sometimes carries this idea too far — appearing to advocate 
as an end in itself what should surely be only the means to a broader 
end, and to forget his noble declaration that the teacher must always 
stand for the universal. This is an error hard to be avoided by a philo- 
sopher whose inspiration is largely Hegelian; moreover, it is easily 
pardonable in a patriotic speaker with the glorious cultural history of 
Italy behind him and before him the elementaiy school teachers of 
Trieste redenta. But although I regret Signor Gentile's adhesion to what 
I consider a false view of the relation between the individual soul and 
society, his book has high value, for it expresses a passionate conviction 
that during the last century the development of the great European 
peoples went in some respects sadly astray, and that their moral health 
can be restored only by education inspired from top to bottom by a trne 
judgment of values. Here he is, I believe, fundamentally right. The 
last hundred years have greatly accentuated the gravity of a problem 
which was discerned by the poet Schiller and diagnosed in the famous 
' Letters on iEsthetic Education ' he published in 1795. To this 
diagnosis Dr. 0. G. Jung has devoted an interesting chapter in his 
book on ' Psychological Types.' In Schiller's view the immense pro- 
gress of the modern nations has been purchased at the expense of the 
development of the individual soul, so that, in spite of the greatness of 
our achievements, we are, man for man, inferior to the various and well- 
rounded Athenians of the best days. It is the division of labour essential 
to a large scale organisation of society which has at once made general 
progress possible and individual impoverishment inevitable, for it has 
cut individual men off from experiences that are indispensable to the 
full well-being of mankind. If this was true in the days of the French 
Eevolution, how much more true it is to-day, and how mtich more grave 
the evil. We arei told that before the era of industrialism the gi'eat 
mass of our people enjoyed a culture which, though simple, was sincere 
and at least kept them in touch with the springs of beauty. What truth 
there is in the picture I do not know, but it is certain that with what is 
called the industrial revolution the conditions that make it credible 
largely disappeared. Torn from the traditions of the old nu'al life and 
domestic industry and herded into towns where in the fight for mere 
existence they lost their hold on all that gave grace to the former life, 
and where the ancient institutions which might have helped them to 
build up a worthy new one were themselves submerged in the rising tide 
of featureless and monotonous industrial activity, the folk who now 
constitute the bulk of our population were cut off effectually from 
' sweetness and light.' That was the situation when the task of public 
education was taken seriously in hand, and that, notwithstanding a great 
amelioration in details, is for far too many the situation to-day. There 
are some who think thnt +he only remedy is t<-i cry h^U to the modern 
movement and return deliberatelv to mpdic-r^valism. This is, I fear, a 
counsel of despair ; instead of indulging idle dreams it will be more profit- 
able, assuming the unalterable conditions of modern life, to consider 
how the rest may so be modified as to place the true dignity and grace 
of life within the reach of all who are qualified to achieve them. That 
1923 V 


can be done only by a system of education which brings the things of 
enduring and universal worth to the doors of the common people. It is 
what has been done by many an elementary school teacher, sometimes 
with scant assistance from public opinion, simply because, face to face 
with his helpless charges, he was impelled to give them the best he had 
to give. It will be done with increasing happy results the more clearly 
it is seen that the proper function of the elementary schools is something 
much more than to protect the State against the obvious danger of a 
grossly ignorant populace or to ' educate our masters ' in the rudiments 
of citizenship. And unless it is done, unless the natural hunger of the 
people for knowledge and beauty is wisely stimulated and widely 
satisfied, no material prosperity can in the end save the social body from 
irretrievable degradation and disaster. 





In addressing the Section as President I would confess at the very 
outset to a pride that I should be permitted to occupy a post of such 
great honour, for which my chief qualification must be that of having 
graduated through every other office provided for in the Sectional 

I could only have wished that the honour had fallen to me in any 
year other than the present, in which my energies have been fully 
absorbed by the duties of a new appointment of a peculiarly difficult 
character; and it is with some misgiving that I venture to address the 
Section to-day, being conscious of having nothing to offer but a few 
random thoughts, incubated at odd moments, and reduced to verbal 
form under conditions which have not permitted the careful revision 
that the occasion demands. 

For the second consecutive year the Section meets in a great sea- 
port, a city whose activities are written large across the liistory of 
British agriculture throughout the past century, and have contributed 
in no small degree to the anxieties with which the industry is beset at 
the present day. The part played by the port of Liverpool in shaping 
the fortunes — or misfortunes — of British agriculture might well have 
formed an appropriate subject for the Presidential Address to this Sec- 
tion, had I possessed the competence and leisure to deal with it effec- 
tively, but I must confine myself to matters falling more closely 
within the range of my everyday activities. 

When the Section met last year British agriculture was reeling 
under the shock of a second disastrous year, which in large sections of 
the industry, notably those dependent primarily upon the direct sale 
of crops, seemed likely to produce a crisis of the gravest character, 
and greatly accentuated the existing anxiety even in sections of the 
industry less directly affected. This atmosphere of crisis still unfortu- 
nately persists, though permeated now perhaps by a rather more 
optimistic note, and it must necessarily receive the consideration of this 
Section of an Association which aims at intimate touch with the every- 
day life of the nation. 

It is generally recognised that the primaiy causes of the present 
difficulties of British agriculture are strictly economic in character, and 
no(t due to any gross and general failure to apply present-day scientific 
knowledge to the technique of farming, although the great disparity 
which exists between the average production of the country and that 
secured by the more competent farmers on soils of the most diverse 

u 2 


natural fertility suggests that with a higher general level of technique 
and education the intensity of the crisis might have been sensibly 
reduced. So far, however, from there having been any appreciable 
lowering in the general standard of our farming, as measured by the 
application of the teachings of agricultural science, it is the common 
experience of those of us who are in close touch with the farming com- 
munity that recent years have witnessed a very marked and rapid 
development amongst farmers of interest in agricultural education and 
research. Throughout the more intelligent section of the older farmers 
and the whole body of the younger men the old antagonism between 
' practice ' and ' science ' is rapidly disappearing. Whether it be a 
case of the ' sick devil ' or not, the agricultural community is at present 
in a more receptive mood towards scientific advice than at any time T 
can recall in some twenty years' advisory experience, and I believe 
the moment to be opportune for a fonvard movement in agricultural 
education, which, if wisely developed, may remove the last vestiges 
of opposition and establish education and research firmly in their rightful 
places in our agricultural organisation. 

I have referred to the causes of the present crisis as being strictly 
economic, and such palliative measures as have been adopted or sug- 
o-ested have been almost entirely aimed directly at immediate economic 
relief. There is, indeed, the danger that if the exponents of agricultural 
science remain silent the impression may get abroad that we have 
nothing substantial to offer towards the alleviation of the crisis, and 
it is my main purpose to-day, therefore, to indicate some of the direc- 
tions in which I believe help can be given, and some of the lines along 
which development of our scientific and educational organisation is, 
in my opinion, more especially necessary at the present juncture. 

Our agricultural educational system may be likened to a pyramid 
with research at the apex, elementary education and general advisory 
work at the base, with intermediate education, higher education, and 
higher advisory work occupying the intervening parts. Our pyramid 
has grown within the last thirty years from a very modest structure of 
low elevation into an imposing edifice, which perhaps appeals to the 
mind's eye more through its height than its spread, the upward growth 
having taken place at a proportionately greater rate than the expansion 
of the base. Such, at least, it appears to me, and I shall suggest to you 
later that the essential need of the moment is a broadening of the base 
with a view to greater stability and a more effective transmission of the 
results of the activities of the upper portions to the maximum basal 
area over which they can beneficially react. 

For the purposes of my survey it will be convenient to follow the 
customary classification of our work into research, advisory work, and 
teaching. Of these three divisions I propose to deal but very briefly 
with the first, that of reseai'ch, since the potentialities of research for 
the advancement of agriculture are too patent to require exposition, 
the ultimate object of all agricultural research being the acquisition of 
knowledge which will enable the farmer to comprehend his task more 
fully, and to wield a more intelligent control over the varied factors 
which govern both crop production and animal production. 



Agricultural progress must be dependent upon research, and no 
phase of our agricultural educational system is so full of great promise 
for the future as the comprehensive research organisation, covering 
practically every field of agricultural research, which has been brought 
into existence during the past twelve years, and developed upon lines 
which ensure an attractive career to a large number of the most capable 
research workers coming out of our universities. In praising the 
Research Institute scheme I am not unmindful of the needs of the 
independent research worker and the spare-time research work of teach- 
ing staffs — the type of research work to which we owe so much in this 
country— and it is with some anxiety that I have watched the distribu- 
tion by the Ministry of Agriculture of the modest resources available 
for the support of this class of work. I trust that my fears are gi'ound- 
less, but I. am afraid of a tendency to deflect such resources towards 
the work of the Research Institutes, a tendency which in common 
fairness to the independent worker should be most strenuously resisted. 
With a sufficiently liberal conception of the class of work which can be 
effectively carried through by the independent worker there should 
be no difficulty in alloca.ting these moneys to the purposes for which 
they are intended. 

In suggesting, as I did a few moments ago, that in proportion to 
the means available agricultural research is perhaps more adequately 
provided for at the moment than other branches of agricultural educa- 
tional activity, nothing is further from my mind than to imply that 
greater resources could not be effectively absorbed in this direction, 
but I am guided by the feeling that a due measure of proportion should 
be maintained between research and the organisation behind it designed 
to translate the findings of research into economic practice, and to 
secure that each advance of knowledge shall be made known quickly 
and effectively throughout the industry. 

It is chiefly in the latter direction that agiicultural science can make 
an immediate and effective contribution to the alleviation of the present 
crisis, since agricultural research in the main does not lend itself to 
the ' speeding-up ' necessary for quick action. The same applies also 
to formal educational work, which must necessarily exert its influence 
on the industry but slowly. 

The one line of approach along which agricultural science can make 
its influence felt quickly is that of advisory work, which consists in the 
skilful application of existing knowledge to the solution of practical 
problems, or at most the carrying out of investigations of a simple 
type, with a view to securing guidance as to the solution of the problem 
in time for effective action to be taken. 

It is, therefore, to the possibilities of such advisory work that I 
propose to turn my attention in more detail. The root difficulty of 
agricultural educational propaganda in the past has been to secure a 
sufficiently intimate and widespread contact with the farmer, and for 
this purpose no agency at our command is so valuable as advisoi-y work, 
since it ensures a contact with the individual farmer which is both direct 
and sympathetic, originating, indeed, in most cases out of a direct 
request for help. The difficulties in the way of extending advisory work 


greatly I si: all turn to presently, but I wish first of all to outline some 
of the more immediately helpful forms of advisory work which have 
fallen within the scope of my own personal experience. 

When some four years ago I undertook to develop for the late 
Lord Manton a research and advisory organisation to fm-nish guidance 
in his extensive fai'ming enterprises, I was obliged in the first instance 
to take account of the fact that the resources at my disposal, though 
large, would not serve to cover the whole field of agricultm-al problems, 
and so far as specialist work was concerned it would be necessary to 
concentrate on two or three fields of activity, outside which only general 
guidance could be af orded by the departmental staff, and for specialist 
assistance it would be necessaiy to have recourse to the national advisory 
organisation set up by the Ministry of Agriculture. Eventually, after 
careful consideration, the fields of work selected for special attention 
were those of soils, plant nutrition, plant breeding, and animal nutrition, 
and it is to these that I propose to refer more particularly. No specific 
provision was made at the outset for dealing with diseases, either plant 
or animal, partly for reasons of economy, but mainly because it was 
felt that the outstanding disease problems could be more effectively 
dealt with by co-operative effort through the national organisation than 
by a small isolated advisory station. 

In making provision for soil work as one of our principal lines of 
activity I was actuated by the conviction that soil investigation is the 
most fundamental of all forms of agricultural research. Soil factors 
dominate the growth of crops from germination to maturity, and must 
influence the utilisation of the crops by the animal, wliich is their ultimate 
destiny. In stressing the importance of soil advisory work I am not 
unmindful of the fact that, despite the enormous volume of investiga- 
tion relating to soils which has been carried out, the task of the soil 
adviser still remains a very difficult one, and except in a. few directions, 
and over a comparatively small area of the country, the interpretation 
of soil analytical data is rarely clear. It is a sobering thought, indeed, 
tO' recall the abounding optimism with which soil analysis was entered 
upon some eighty years ago, and contrast the hopes then held with 
the realities of soil advisory work as we find them to-day. The initial 
mistake — so common throughout a large part of our agricultural in- 
vestigational work of the past — lay in a failure to visualise the com- 
plexity of the problem, even with due regard to then existing knowledge. 
The problem was approached as if the soil were to be regarded solely 
as a reservoir of plant food, whose capabilities for crop production 
should therefore admit of complete diagnosis by chemical analysis. 
The conception is fascinating in its simplicity, and has dominated the 
greater part of our soil work down to the present time, repeated en- 
deavours being made by variation in the methods and intensity of the 
analytical. attack to improve the persistently low degi-ee of correlation 
between analytical data and crop results. Parallel with this at a later 
date was developed the mechanical conception which found the major 
part of the explanation of the differentiation of fertility in the physical 
properties of the soil particles, whilst still later soil biology has asserted 
its claim to provide the ' simple solution.' The work of recent years. 


however, so brilliantly led in this country by Sir John Russell and his 
colleagues, leaves us with no excuse for such restricted conceptions 
of soil fertility, which must now be regarded as the index of the 
equilibrium established by the mutual interactions of a highly complex 
series of factors, the variation of any one of which may affect the 
interplay of the whole, with consequent effect upon the rate or character 
of plant growth. 

The problem of fertility being so complex, one might perhaps be 
inclined to despair of attaining to anythmg really effective in soil 
adviso'ry work, which must necessarily be dependent upon rapid and 
somewhat superficial examination, and such apparently is the view 
held by the Ministry of Agriculture if one may judge by the con- 
spicuous neglect of chemical and physical science in recent extensions 
of advisory facilities. 

My own conception, however, of the present possibilities of soil 
advisoiy work is more optimistic, and from experience covering the 
most diverse parts of the country I am confident that an extension of 
facilities for soil advisoiy work would be of immediate and progressively 
increasing benefit to the farmer. 

It is the common experience of all engaged in soil advisory work 
that, although what may be termed the ' average soil ' offers great 
difficulties, there are many soils in all parts of the country which are 
distinctly not ' average ' for the areas in which they are situate, and 
for which our conventional methods of chemical and mechanical 
analysis, crude though they be, and imperfect the premises upon which 
their interpretation is based, do yield guidance which on application in 
practice proves to have been substantially sound. The real difficulty 
at the moment is that for large tracts of the country we lack the neces- 
sary data, to enable: us to detemiine what is the ' average soil ' for each 
particular area, and until provision is made for specific soil work in 
these areas, which comprise the whole of the great agricultural areas 
of the Midlands, our advisory work relating to this raw material of 
crop production must of necessity remain superficial, and only too 
frequently ineffective. 

In no direction has the need for extended soil advisory work become 
more evident in recent years than in the revelation of the extent to 
which large areas of our soils have become depleted of lime. Oases 
come almost daily to our notice in which this lack of lime is clearly 
the chemical ' limiting factor, ' and the annual waste due to unremunera- 
tive expenditure on fertilisers on such land must indeed be very great. 
In many cases, fortunately, the depletion has been detected at a stage 
at which it is still economically remediable, but in others, unfortunately, 
this is no longer the case, and unless soil-survey facilities be greatly 
extended it is certain that large areas of our land must steadily fall into 
the latter category, with the inevitable development in the near future 
of a problem of such magnitude as will require national action for its 
solution. It is worthy of note also in passing that this problem will 
probably be accentuated rather than diminished as a greater proportion 
of our arable land reverts to grass. 

A further direction in which great scope remains for the work of 


the soil adviser is in the economic manuring of crops. More attention 
has probably been paid to the subject of manuring than to any other 
branch of agricultural science, and this branch has been perhaps more 
definitely systematised than any other; but inadequate and improper 
manuring is still widely prevalent, and the annual wastage of resources 
thereby incurred must represent a very large sum. A considerable part 
of this wastage is due to the widespread use of proprietary compound 
manures, more often than not compounded without any special reference 
to the soils upon which they are to be used, or even without intelligent 
adaptation to the special needs of the crops for which they are supplied. 
It is not uncommon, indeed, to find mixtures of identical composition 
offered for the most diverse crops. In far too many cases also the prices 
charged are extravagantly disproportionate to the intrinsic value of the 
ingredients of the mixture, and in all these various ways costs of pro- 
duction are made higher than they need be. In claiming that improved 
manuring achieved through extended advisory guidance might effect a 
sensible alleviation of the present difficulties of the arable farmer, I am 
not unmindful of the fact tfiat even the best practice may result in loss 
when the value of produce sinks to the low levels recently touched by 
many crops, and the best manuring will not make it possible, for 
example, to grow potatoes profitably under present conditions for sale 
at 30s. per ton. Where loss is inevitable, however, this will usually be 
lowest at a level of production involving the reasonable and intelligent 
use of manures. 

Passing on from soil and manuring, we come to the sphere of seed 
and sowing problems, presenting obviously abundant scope for advisory 
work. The need for good and pure seed is axiomatic and is recognised 
by the existence of the Seeds Act, which remains to us as a legacy, 
more beneficent in its operation than many others, of the war-time 
interest of the State in agriculture. 

Seed must not only be good, however, but it must be of the right 
kind, sown under proper conditions and at the most suitable time, and 
the value of advisory guidance on these points has always been recog- 
nised, especially with reference to the choice between different varieties 
of each particular crop. The variety tests carried out on the various 
college farms and elsewhere have always proved helpful in this respect 
in so far as they serve to demonstrate the general characteristics of 
the different varieties. Whether they have been equally successful in 
measuring the cropping capacities of the different varieties is more 
than doubtful, owing to their restriction to single, or at most double 
plots of a kind, and this has been recognised in the more elaborate 
schemes devised for the purpose by the National Institute of Agricul- 
tural Botany, which it is to be hoped may furnish a practical scheme 
for more accurate quantitative field tests in the future. 

Given good seed, the improvenient of crop possible through seed 
selection is perhaps not in general so striking as that frequently obtain- 
able by manuring, but it may nevertheless be substantial, especially 
with crops such as barley, where improvement of quality may have a 
special value. There is also a rapidly extending field for seed advisory 
work in connection with the laying down of land to grass for varying 


During the growth of the crop advisory worli is largely restricted to 
the domain of diseases and insect pests, whose ravages take incalculable 
toll of our crops. This section of advisory work i am not competent 
to discuss, but I am continually impi'essed by its importance as I note 
how largely such matters bulk in the inquiries for assistance which 
pass through my hands, and I believe science can make no more directly 
effective contribution towards the removal of at least the technical 
difficulties of the farmer than the elaboration of effective preventive 
measures against pests and diseases. 

In some directions, as in the circumvention of certain diseases of 
potatoes and cereals, very striking advances have already been made, 
to the great benefit of practice ; but in all too many cases the adviser at 
present can go little beyond the stage of diagnosis, although, with the 
greatly increased number of research workers now available, there are 
good grounds tO' hope that the lines of preventive action may before long 
be worked out. 

I must pass on, finally, to the utilisation of crop products as food for 
animals, the line of work with which my own personal interests and 
activities have always been most closely associated. Looking back over 
twenty years of advisory activity, I realise that the position of the 
adviser in animal nutrition is infinitely stronger to-day than when I 
first assumed the role. 

At the outset of this period the feeding of animals was regarded 
simply as a matter of supply of suitable proportions of digestible protein, 
oils, and carbohydrates, more or less regardless of the character of the 
materials in which they were supplied. Little further could be done in 
the way of differentiating the values of different food materials beyond 
a comparison upon the basis of gross digestible energy, although the 
conclusions to which this led were notoriously um-eliable and in many 
cases in flagrant conflict with practical experience. Material for a 
great advance was, however, rapidly accumulating in the work of 
Kellner, which was finally reduced by him to a practical system of food 
evaluation in his classic ' Ernabrung der landwu'tschaftlichen Nutztiere,' 
published in 1905, and universally acclaimed as representing a great 
advance in the application of nutritional science to the practical feeding 
of farm live-stock. The advance lay essentially in the disci-imination 
between the available energy and the net energy of foods, and the 
carrying out of a sufficiently large number of determinations of the latter 
to furnish a fairly adequate basis for generalisation. With these to 
supplement his classic determinations of the values of protein, fat, and 
carbohydrate for the production of fattening increase, he was able to 
devise a practical scheme of assessing the production-values or net 
energy-values of foods, which he preferred for reasons of practical con- 
venience to express in terms of starch. The significance of the great 
practical advance made by Kellner was not at first clearly grasped in 
this country, ciitical attention being directed, in accordance with true 
British conservatism, more to the admitted shortcomings of the starch- 
equivalent than to its merits ; but as time revealed its superiority over 
the older methods it came generally into use, and now serves as the 
basis of all our advisory woi'k in farm nutrition. 


Although primarily designed for the case of the fattening animal, 
it has proved practically useful for other classes of stock, and even, 
with slight modification, for the case of the milk-producing animal. 

The last twenty years has also witnessed the great developments of 
protein investigation which have thrown much light upon the problems 
of protein metabolism and the productive efficiency of the proteins of 
ditferent foods. Lastly, we may recall the remarkable developments in 
nutritional science of recent years, consequent upon Hopkins' discoveiy 
of the ' accessory growth factor,' and also the attention which is now 
being directed to the importance of the mineral ingredients of foods. 

With all this newer knowledge at his command, the adviser in 
nutrition can now approach his work with far greater confidence, and 
evidence of the increasing practical value of his work is rapidly accumu- 
lating. This is particularly the case with advisory work in milk pro- 
duction, a branch of feeding which lends itself more readily than most 
to carefully regulated rationing owing to the ease with which the 
amount of product can be determined. Pew branches of advisory work 
have proved more directly helpful to the farmer in recent years than 
this advisory control of the feeding of dairy cows, the extension of 
which has been greatly aided by the development of milk-recording 
societies, in whose activities such rationing advice is rapidly becoming 
regarded as an indispensable feature. Much success has also been 
met with in advisory work in pig-feeding, and to a less extent in the 
feeding of cattle, the lower degree of success in the latter case being due 
not so much to an inferior capability of the adviser to help as to the 
difficulty of dispelling the tradition that beef production represents the 
supreme accomplishment of the British farmer, as to which there is 
nothing left for him to learn. The work already accomplished repre- 
sents, however, but the very beginnings of economy in the feeding of 
live-stock, and wasteful feeding of both home-grown and purchased 
feeding-stuffs for lack of the necessary advisory guidance is still far too 
widely prevalent. 

Such are only a few of the aspects of advisory work, which, if 
extended more widely, might exercise a very profound effect upon the 
economy of the industry. Such extension implies, however, greatly 
increased resources in men and money and more efficient means of 
bringing the advisory facilities to the notice of the farmer. 

I am inclined, indeed, to think that a more efficient propaganda is 
perhaps the first need of the situation, as one finds in all parts of the 
country an astonishingly large number of farmers who are totally 
unaware of the existence of advisory facilities of any kind. A more 
extensive propaganda will be useless, however, unless accompanied by 
increased prov'ision for advice, since the present resources are already 
more than fully taxed by the relatively moderate volume of calls for 
assistance that now arise. It is the universal complaint of the County 
Agricultural Organisers that they cannot secure the personal contact, 
which it is the most important part of their functions to establish, 
with more than a very small fraction of the farmers within their area, 
and it is for a great extension of this type of advisory assistance that 
there is the most clamant need. Most of our counties have, at present, 


only one agricultural adviser — some, indeed, have none — and yet this 
slender organisation represents in large measure the base of contact with 
the industry upon which the whole pyramid of our advisory and educa- 
tional work rests. It is here where I see the most immediately profitable 
outlet for any further moneys that may be available for agricultural 
education in the near future. The facilities for organised instruction 
in agriculture are at present adequate for the numbers of students coming 
forward, or likely to come forward, in the near future, the present 
problem in this sphere being indeed rather that of finding suitable 
openings for the numbers of students passing througli our courses — a 
matter to which I shall return presently. 

I have already alluded to the chemical gaps in our specialised 
advisory organisation, and I might also have indicated the similar and 
even less comprehensible inadequacy in the provision for specialist advice 
in economics; but these are relatively small matters compared with the 
paucity of the less highly specialised but scientifically trained advisers of 
the County Organiser type, whose business it should be to secure the 
confidence of the individual farmer by personal contact, and the render- 
ing of assistance either directly in the simpler problems or with the help 
of the specialist staff standing behind them in more complex cases, 
whereby a more widespread and real appreciation of the practical value 
of agricultural education and research than now prevails might quickly 
be developed. 

A great extension of advisory wo-rk such as I suggest must neces- 
sarily involve heavy expenditure, and further, an exceptional measure 
of care in the selection of men, since in the direct approach to the farmer 
personal qualities may in the first instance count for more than technical 
proficiency. Furthermore, if the full measure of success is to be 
achieved, it is essential that a more closely organised and intimate 
contact should be established between the various units of the advisory 
organisation, from the research station through the scientific adviser, 
to the practical adviser. Our present organisation is too indefinite and 
toO' widely permissive in this respect and calls urgently for consideration 
by all concerned, both county authorities and advisory and research 
workers, with a view to more effective co-ordination and co-operative 

I have laid great stress upon the potentialities of advisory work as a 
contribution to the alleviation of the present crisis, but I cannot close 
without some reference to the far greater contribution to the future 
prosperity of British agriculture which we can make through our educa- 
tional system, if wisely pursued, in the ti-aining of the farmers of the 

future. _ _ . . . '' '^' 

I have already expressed the opinion that the existing facilities for 
organised agricultural education — at least so far as universities and col- 
leges are concerned — are adequate to deal with the numbers of students 
presenting themselves. There is indeed at the moment a considerable 
excess output of the class of student who is either unwiUing or unable 
to take up practical farming and must needs have a salaried post. This 
problem, which is becoming an increasingly serious one, especially for 
the non-university institution, such as my ov/n College, hardly falls, 
however, within the scope of my present theme, except in so far as the 



extension of advisory facilities I have advocated would tend to absorb 
this surplus and restore the balance of the whole organisation. 

Of more immediate concern is our comparative failure to secure for 
our educational courses more than a smaU fraction of the sons of farmers, 
upon whom the future of the industry will largely rest. I have testified 
to the greatly awakened interest in agricultural education which has 
been displayed amongst farmers in recent years, but it is yet far from 
having developed into a conviction that such education is to be regarded 
as a vitally essential part of the farmer's training. One must perhaps 
be content with gradual advance towards this goal by internal develop- 
ment, although the possibilities of more rapid advance by external 
pressure should not be overlooked. One such that might have a more 
potent influence than any other in filling our colleges with farmers' sons 
I would submit for the consideration of my distinguished predecessor 
of last year, in supplement of his able exposition of the part to be played 
by the enlightened landowner in the progress of agriculture. It is that 
in letting his farms — at any rate so far as young applicants are con- 
cerned-— the enlightened landowner should show his faith in agricultural 
education by giving first preference — other considerations being equal — 
to men who have received adequate instruction in the principles of agri- 
culture in addition to practical experience. So long as the private 
ownership of land continues — and I trust that it may be very long — the 
landowner will have it in his power to render the most powerful aid to 
the progress of agricultural education, and by action along the lines I 
have suggested might exert more good in one year than is attainable by 
many weary years of propaganda. Whatever the character of our land 
tenure system of the future, it is certain that sooner or later some 
guarantee of efiiciency for the productive occupation of land will be 
demanded from the would-be farmer. "We cannot continue indefinitely, 
on the one hand, to proclaim that the land is our greatest national asset, 
to be maintained with the help of, and in the interests of, the State in 
a highly efficient state of productivity, whilst, on the other hand, the use 
of the land is left open to all, regardless of fitness for its effective use. 
This vision of farming reduced to the status of medicine and law as a 
close profession regulated by an entrance examination, may perhaps be 
stigmatised as a horrible nightmare ; but some movement in that direc- 
tion I believe to be inevitable, and, with nationalisation of the land, 
might well come more speedily than one would venture to contemplate. 
None win question, at any rate, that, should such a day arrive, education 
in the principles underlying the calling will loom as largely as practical 
training in determining the standards of admission to the use of the 
land. I will conclude on this highly imaginative note with an expres- 
sion of my flnn conviction that the genius of the British race for the ■ 
management of its affairs on lines of voluntary action will not desert I 
us in this particular, and that with wise guidance and intelligent adapta- 1 
tion of educational curricula and methods to the changing needs of 
the times the penetration of our practice by science will proceed 
smoothly and with such rapidity as to render interference from outside 
not only unnecessary, but unwarrantable. 



Seismological Investigations.— Twenty-eighth Report of Com- 
mittee (Professor H. H. Turner, Chairman; Mr. J. J. Shaw, 
Secretary; Mr. C. Vernon Boys, Dr. J. E. Crombie, Sir Horace 
Darwin, Sir F. W. Dyson, Sir E. T. Glazebrook, Dr. Harold 
Jeffreys, Professor H. Lamb, Sir J. Larmor, Dr. A. Crichton 
Mitchell, Professors A. E. H. Love, H. M. Macdonald, and 
H. C. Plummer, Mr. W. E. Plummer, Professor E. A. Sampson, 
Sir A. Schuster, Sir Napier Shaw, and Dr. G. T. Walker). 
[Drawn up by the Chairmayi except where otherivise mentioned.] 


Once again the Committee has to deplore the loss of one of its eminent and 
active members in Professor C. G. Knott, who has been associated with the work 
from the time (1883) when he became a colleague of John Milne in Japan. He 
was the author of a standard work on earthquakes, ' The Physics of Earthquake 
Phenomena' (Oxford University Press, 1908), which represents a series of 
carefully thought-out lectures on the science; and more recently he undertook 
a laborious investigation of the paths of earthquake rays within the earth, 
including the times to different points [Proc. R.S.E., 1919, vol. xxxix., part II., 
No. 14). This important research was the starting point for the investigation 
of depth of focus of earthquakes, mentioned in the last Report, and in this. 

The clerical work at Oxford is still being carried on in the ' Students' 
Observatory,' since the tenant of the house purchased by Dr. Crombie's bene- 
faction continued to declare himself unable to find other quarters. But the 
situation may be modified by the recent death of this tenant. His widow is 
still living in the house, and it is yet too early to say how soon it will be 
available for Seismology. 


The relation of the Committee to the Seismological Section of the International 
Union for Geodesy and Geophysics was mentioned in the last Report, and the 
suggestion was made that at the end of 1917 the Bulletins of this Committee, 
which have aimed at giving a summary of observations of the important earth- 
quakes, should become the official publication of the Union. Accordingly, as 
mentioned below, the title was altered with the year 1918 to that of ' The 
International 'Seismological Summary.' But the subsidy received from the 
Union (10,000 francs annually) is only sufficient for a fraction of the cost of 
this publication, and at the next meeting of the Union in 1924 application 
will be made for an increased grant. Meanwhile the extra expense is being met 
partly by the annual grant of 100/. from the Caird Fund of the British Associa- 
tion, and partly by a further and special grant of 200/. from the Royal Society. 
These funds (and former grants of the same kind) have been applied to the 
routine expenses of calculation and printing, and to the maintenance of the 
modest instrumental equipment (first at Shide and recently at Oxford). Super- 
vision has been provided voluntarily by the Chairman and Secretary of the 
Committee ; but during the last year a very welcome addition to the resources 
available for supervision has been made by the further generosity of Dr. 
J. E. Crombie, who has provided a salary during the year for Mr. J. S. Hughes, 
B.A.. of New College, Oxford, in order that he may give his whole time to 
this work. 



The Milne-Shaw seismograph in the basement of the Clarendon Laboratory 
at Oxford has worked well throughout the year. It is one of the early machines 
of this pattern, and the scale is smaller than that on more recent machines. 
The question of replacing it by one with a more open scale has been con- 
sidered, but it is thought better at present to supply the improved pattern to 
distant stations, from which there has been a succession of demands sufficient 
to keep Mr. Shaw closely at work. 

During the year he has dispatched machines to Ottawa (2nd component). 
Hong Kong (2nd component), Strasbourg, Hyderabad, Perth (W.A.), and Stony- 
hurst. Of these only that for Perth is the property of the B.A. Committee, 
and represents a loan (again owing to the generosity of Dr. J. E. Croinbie) ; the 
others are all purchases. But they are mentioned here to show the distribution 
of machines of the type which is essentially the product of this Committee; 
for Mr. Shaw began his experiments at the request of John jMilne. 

It was mentioned in the last Report that a machine had been taken 
to Christmas Island by the eclipse observers from the Royal Observatory, 
Greenwich. An accident to the time-clock on the voyage led to considerable 
delay in setting up the instrument, which was only erected just before the 
observers left, after the eclipse, for home. It was expected that records would 
have been received before this, but nothing has yet come, and Mr. Jones is 
kindly making inquiries into the matter. 

Mr. Claxton has kindly sent to Oxford for examination most of the Hong Kong 
films which contain earthquake records, and they are naturally of great interest to 
us as showing the effects of disturbance at distances so much smaller than those to 
which we are accustomed. The record for March 24 last is specially noteworthy. 
The earthquake was very destructive in a region (32° N. 102° E.) not far from 
the destructive earthquake of December 16, 1920 (35°.5 N. 105°.5 E.). 

Bulletins and Tables. 

The Bulletins to the end of the year 1917 have been printed and distributed. 
The title of the publication was then changed, as above mentioned, to ' The 
International Seismological Summary,' the first number of which contains the 
results from January to March, 1918; the next number, April to June, 1918, is 
passed for press ; July to November, 1918, is ready in manuscript, though some 
checking of the later months is still required. The work steadily increases 
owing to the communication of results from new stations, and the receipt of 
arrears from older ones. 

The Tables for P and S have been expanded to give results for every tenth 
of a degree, and will be distributed with the next number of the Summary. 
This expansion has been delayed in the hope of first obtaining corrections of the 
tables, but it becomes clear that this may take some time owing to the compli- 
cation introduced by consideration of focal depth, and in any case the present 
tables will be applicable to a great deal of work already in print. 

Depth of Focus. 

It was mentioned in the last Report that the time of arrival of the earliest 
disturbance at the opposite side of the earth gives valuable indication of the 
depth of focus. The number of instances then available was small, but several 
more have been found during the past year, and successfully treated by the 
provisional formulae then given. As they are fully dealt with in the Bulletins 
and Summaries there is no need to reproduce them here, but new light has been 
thrown on the possibilities bv a paper by the late Prince Galitzin. dated 1919 
but only recently received from Petrograd. From a study of the angles of 
emergence he was led to infer three critical surfaces at depths 106, 232, and 492 
kilometres below the earth's surface : or 0.017, 0.036, 0.077 in terms of the 
earth's radius. This work is quite independent of the investigation of focal 


depth, but the results provisionally obtained for focal depth do collect them- 
selves roughly into three groups, which may possibly refer to foci at these 
critical surfaces ; at any rate the intervals between the groups correspond to 
the intervals between the surfaces. The information about focal depth was 
entirely relative, and wo had no means of judging the absolute focal depth. If, 
however, this identification is confirmed the missing constant is supplied. 

In a note to this effect (Genp. Step, to Mon. Not. R.A.S., Jan. 1923) the times 
of arrival of [P] at the anticentre from foci actually on these surfaces are 
found to differ from the adopted tables by 

Group ... I. II. III. 

Depth . . . —0-017 —0-0.36 —0077 

Diff. from normal . +0019 0000 -0-041 

Time for [P] . . +14s. —3s. —39s. 

To Group I. we may assign the following : — 







Oct. 3 


14-0 S 

74-5 W 

[P]= + 16 


Oct. 20 


18-0 S 

173 W 

= + 16 


June 1.3 


30-2 S 

177-7 W 

= + 1.5 


I\Tay 1 


29-2 S 

177-0 W 

= + 13 

In the last case the solution printed in the Bulletin is probably in error, 
as is seen by detailed comparison with Jime 13. 1917, probably from the same 
focus : and a corrected solution will be given, subtracting 25s. from the adopted 
Tq. To this group we may provisionally assign also 

1914 June 26 4 13-0 S 166-8 E [PI = + 8 

1916 Jan. 1 13 5-5 154-0 E [P]= + 7 

To Group II. we assign the great majority of earthquakes. Several cases 
where [P] can be well determined are collected in the paper in vol. i. No. 1, of 
the Geop. Sup. ; its values are as follows : — 

+3s., —Is., —4s., —4s., —5s.. —7s.. —9s.. —9s., —12s. (—17s.). 
but these cases have not been yet fully revised. 
To Group III. we assign the following : — 

d. h. ° ° s. 


Nov. 10 


18-0 S 

170-0 E 



Feb. 26 


160 S 

61-0 W 



Jan. 5 


165 S 

168-5 E 



June 21 



57 OW 



Sept. 3 


7-0 S 

155-0 E 



April 21 

37-2 N 

70-4 E 



Feb. 7 


65 N 

127-0 E 



April 10 


44-0 N 

131-0 E 



May 22 


170 S 

177-5 W 


1918 May 25 19 31-0 S 91-0 W —15? 

It is admitted that at the present stage there is too much scattering within 
the group and too much overlap between groups ; but a great deal of the 
material is still rough, and we may be content to await further developments. 
It will be seen that there is some appearance of local restriction in the groups. 
Thus the epicentres of Group I. are all south and west. But this may be an 
accident due to the distribution of observing stations. No case has been 
included at this stage unless there is a good determination of T„ from stations 
near the epicentre and also of [P} from stations near the anticentre, and on© or 
other of these may fail for want of observing stations (or of observations from 
them) in the appropriate neighbourhood. Thus the earthquake of 1918 January 
30d. 21h. at 47°. 5 N. 129°.0 E. has some large residuals which suggest an abnormal 
focal depth, but the South American stations give us no information about fP"), 
unless we accept a single observation at La Paz iP=+18m. 6s. as an observation 
of [P] with residual [ — 104s.], which is far too large to help us. It seems more 
likely that the obsei-vation refers to the P wave, with residual +31s. from 
adopted tables as printed. 



A periodicity near 21m. was mentioned in the last Report. It was detected 
in the Jamaica earthquakes tabulated by Maxwell Hall (Geo p. Sup. M. N., 
vol. i. No. 2), and the period assigned as 21.001451m. But this led to the 
examination of a long series of Italian earthquakes (kindly lent by Mr. R. D. 
Oldham for the purpose), which very foon mdicated a correction of one whole 
period in ten years. The discussion of the Italian series is not yet completed, 
but the Jamaica series was revised (Geop. Sup. M. N., vol. i. No. 3), for the 
new period 0.014584282d. or 21.001366m., which was found to suit them better. 
But there were fluctuations of six months' period and of four years' period in 
the position of maximum, the former with a range of 7.8m. (3.9m. on either 
side of the mean position), the latter with an even greater range of 14.0m. 
(7.0 on either side). A further fluctuation of fifteen months' period was 
detected after the paper had been sent to press, but is discussed in a supple- 
mentary note to the paper. This fifteen months' period had already been 
detected in ' Earthquake Phenomena ' (see the B.A. Beport for 1912), and its 
elimination from the Jamaica series had the satisfactory result of removing a 
double maximum which previously affected the mean curve. 

We thus have three new periodicities in addition to the main one of 21m. : 
.viz. 4 years. 15 months, and 6 months. The 15 month (or 104/7 months more 
accurately) has independent support as above stated, though as yet we have 
no hint of its origin. The 6-month period, if real, is doubtless connected with 
the year. There remains the 4-year period which stood unsupported. But it 
was noticed that it affected the general frequency of Jamaica earthquakes 
(apart from its effect on the 21m. period) ; and also that of the Italian earth- 
quakes. An examination was made of the Chinese and Japanese long series 
and of other shorter series, and they were all found to be affected. The results 
are given in a paper now in the press (Geop. Svp. M. N.. vol. i. No. 4). 
When the paper was read it had been inferred that the maximum travelled 
round the earth from east to west in 8 years (a double cycle, indicating a double 
polarity), but on checkinp; the proof a serious error was detected in the .Japanese 
reduction which rendered this view no longer tenable. It was found, however, 
that there was a travel in latitude from the Equator to the North Pole in the 
N. Hemisphere. What happens in the S. Hemisphere is doubtful, as we have 
only the single case of New Zealand to give information. But for what it is 
worth it indicates that the sweep is in the same direction (S'. Pole to N. Pole). 

But for the further elucidation of these matters more material, and more 
accurate material, is required : and it would appear that our best line of advance 
at present is to continue the identification of epicentres and times for as manv 
earthquakes as possible. Hence this work of identification has been continually 
expanded (in the 'Bulletins' for 1917 and their successors the 'Summaries' 
for 1918) in spite of the consequent delay in catching up arrears. 

The General Fiopagation of Earthquake Waves. 

The announcement of the "^Im. periodicitv in the last Report had the incidental 
consequence of leading; Dr. Jeans to undertake a new investigation of the whole 
ouestion of earthquake wave propagation, and in a paper contributed to the 
Roval Societv (Proc. B. S., A, vol. 102. 19'?3, p. .'^54) he points out that in 
addition to the Rayleigh waves denoted bv L. which travel with velocity 0.93 
a/(h/p\ there are two whole series of surface waves of wh'ch the terminal 
members travel with velocities of ^/Ifx/p) and \/f(X-(-'?[i.Vpl- Taking velocities 
sup'O'ested b^' the Oppan explosion, these waves would tra'^'el round the earth 
in 126m. and 222m.. and Dr. .Jeans suggests that returns of these waves to the 
epicentre (or perhaps the anticentre) may act as triggers for new earthquakes. 
■"Since this renort was sent to press a number of cnops favourable to this view 
have heen noticed. 1 Independently of this possibility (which chiefly concerns 
periodicities) the paper must be of great value for the interpretation of seismo- 
"rams, though no opportunity for testing it in this connection has yet been 


Calculation of Mathematical Tables. — Report of Committee 
(Professor J. W. Nicholson, Chairman; Dr. J. R. Airey, Secre- 
tary; Mr. T. W. Chaundy, Professor L. N. G. Filon, Colonel 
HipPiSLEY, Professor E. W Hobson, Mr. G. Kennedy, and 
Professors A. Lodge, A. E. H. Love, H. M. Macdonald, G. N. 
Watson, and A. G. Webster). 

In the Report for 1922 reference was made to mathematical tables calculated for the 
Association without the assistance of grant from the Committee. The publication of 
these tables was deferred ; the Report for the present year includes in Part I. the 
tables of sin and cos G for in circular measure from 1 to 100 radians, su])plementing computed by Dr. Doodson in the 191(3 Report, viz. sin and cos to fifteen 
places of decimals for = to 10 by intervals of 0-1 radian. 

Tables of Bessel and Neumann functions, where the order and argument are equal 
or differ by unity, have been calculated to six places of decimals and published in the 
Report for 1916, the order and argument having integer values only. In Part II. 
will be found tables of these and other functions, the integrals of Schlilfli and the 
Lommel-Weber functions, where the order and argument are not restricted in value, 
but contain both integral and fractional values, the order of the functions ranging 
from to 10 by intervals of 0-2o. The Avork of calculation, especially that of the 
preliminary tables required for Part II. of the Report, has been much relieved by the 
use of an arithmometer kindly lent to the Secretary. 

Recently, Prof. A. E. Kennelly has placed at the disposal of the Committee tables — 
to six places of decimals — of Bessel functions for a complex variable. These functions 
are equivalent to the classical ber, bei, ber' and bei' functions of Kelvin, but are more 
convenient to use in electrical engineering problems. On account of their practical 
importance, the Committee feel justified in imdertaking their publication in Part III. 
of this Report. 

The other functions referred to in last year's Report, Bessel-Clifford functions 
Cf,(x) and C,(a;) and Lommel-Weber functions Q.u{x) and Qi{x), and further tables of 
the sine and cosine functions are reserved for later publication. 

Part I. 
Sines and Cosines (0 in radians). 

The values of the sine and cosine of unit angle (radian) have been calculated* to 
105 places of decimals by Bretschneider. Using only 30 places, the sines and cosines 
of the following angles (radians) were found in succession, .5, 10, 50, 100, the last 
calculation being correct to 25 places of decimals. To obtain the values of these 
functions for intermediate angles, e.r/. 20, 30, 40, etc., it was found convenient to 
construct a table of the first hundred multiples of sin 10 and cos 10 to facilitate the 
calculation of the products when sin 10 or cos 10 is a factor. In a similar way, by 
employing a table of multiples of sin 1 and cos 1, the remaining values of sin and cos 
were obtained. Each result was checked by those already computed, sin 54 by sin 52, 
and so on. 

A further check was made bv a direct calculation of sin 71 and cos 71. 
Thus 71 (radians) = 22-67r+ 6, where 

= 0-00000 60288 70672 8107-1 42595. 
Hence sin = 0-00000 60288 70672 77422 20829 

and 1 — cos = 0-00000 00000 18173 64079 46837. 

Also sin 71 = sin 22-67C . cos + cos 22-6- . sin 

= cos 18° . cos — sin 18° . .sin 
= + 0-95105 46532 54374 63665 6570 
cos 71 = cos 22-67T . cos — sin 22-67T . sin 
= —sin 18° . cos —cos 18° . sin 
= —0-30902 27281 66070 70291 7494 
verifying the values in this example, and indirectly the whole table, to 24 places of 
decimals. Fifteen places only are given in continuation of Dr. Doodson's table. 

* C. A. Bretschneider, Archiv der Math. u. Phys., vol. 3, 1843, pp. 28-34. 
1923 X 



Sines and Cosines of Angles in Circular Measure. 
































































































































+ 0-66031 







+ 0-98870 




+ 0-91294 































+ 0-42417 







+ 0-99120 







+ 0-64691 
























































































+ 0-96379 







+ 0-74511 
























+ 0-55511 




+ 0-01770 


















































Sines and Cosines of Angles in Circular Measure. 














































+ 0-43616 














+ 0-63673 



































+ 0-92002 










































+ 0-77389 







+ 0-95105 







+ 0-25382 

















+ 0-17171 











+ 0-56610 







+ 0-99952 







+ 0-51397 
























+ 0-77668 




+ 0-31322 



+ 0-94967 







+ 0-24954 

























-0 82181 



+ 0-56975 




+ 003539 



+ 0-99937 




+ 0-86006 



+ 0-51017 











-t 0-10598 

















+ 0-31742 







+ 0-96945 




+ 0-68326 



+ 0-73017 




+ 0-98358 







+ 0-37960 

















+ 0-03982 












Part II. 
Bessel aud other related functions o£ equal order and argument. 

(A). Tables of the Bessel function J„(a;) and the Neumann functions G„{x) and Y„(a:), 
where the order and argument are equal or differ by unity, have been published in 
the 1916 RejJort, the value? of n and x increasing by unit intervals in the earlier part 
of the tables. There does not appear to be any record of the computation of these 
functions for fractional values of the order and argument. The values of the argmnent 
of the Bessel functions J,;(a:), Jv-i(-^') and the Neumann functions Nv(a,') and 'N^_,{x), 
tabulated below, range from to 10 by intervals of 0-25, the order of the functions 
being equal to the argument or less by unity. 

For small values of the argument, the functions J±i(a;) and J±3(.x) were calcu- 
lated from the ascending series, Ji(.r) and J-i{x) together, the terms of these series 
being simply related. 

Ji(»0 = 









— a;- 

, X* 

' 2-5 

- + ■ 




The use of the recurrence formula, Jv+jC-t) = -J\j{x) —J\j_i{x). gave the values 

entered in the following table. 

The Neumann functions were easily obtained from the relations 

J_v(^') = JvC-'^) ■ <^os V7T — N,|^(;c) . sin vtt 
N_^(a;) = J^{x) . sin viz + 'N^j(x) . cos vtc. 

For large values of the order and argument, the functions were directly calcidated 
from the asymptotic series, viz. : 

^'<'> - .„^.! [(!)'r(J j - ,4o i!fr(^) - ,kSf ■ r(^) + ■ ■ ] 

with similar series for Jv_i(v), N\,(v) and Nv_i(v). The results were checked by 





1 -Nvl,(v) 


] -000000 







1-252815 : 




0-990245 : 

0-990245 : 





0-861905 : 

: —0-232820 : 







0-410288 : 

0-699974 : 


—0-006067 : 





0-046083 ; 




0-644714 : 






0-107032 : 


0-339572 : 


0-593338 : 





0-572630 : 

0-140293 : 


0-318012 : 







0-538541 :