;^.:"L \ i.f ■,

L

dJ-

PROCEEDmGS

OF THK

AMERICAN ACADEMY

OF

ARTS AND SCIENCES.

Vol. XLII.

FROM MAY, 1906, TO MAY, 1907,

BOSTON:

PUBLISHED BY THE ACADEMY

1907.

2Enibtrsitg iOrrss:
John Wilson and Son, Cambridge, U. S. A.

X ^ Yl

CONTENTS.

Page
I. Studies in the Eupatorieae : (I.) Revision of the Genus Piqueria ;

(II.) Revision of the Genus Ophryosporus ; (III.) The Genus

Helofjyne and its Synonyms ; (IV.) Diagnoses and Synonymy of

Eupatorieae and of Certain Other Compositae which have been

Classed with them. By B. L. Robinson 1

II. Architectural Acoustics: (I.) Introduction; (II.) The Accuracy

of Musical Taste in regard to Architectural Acoustics ; (III).
Variation in Reverberation with Variation in Pitch. By W. C.
Sabine 49

III. On the Permeability and the Retentiveness of a Mass of Fine Iron

Particles. By B. O. Peiece 85

IV. On the Length of the Time of Contact in the Case of a Quick Tap

on a Telegraph Key. By B. O. Peikck 93

V. Sojne Stages in the Spermatogenesis of the Honey Bee. By E. L.

Mark and M. Copeland 101

VI. Friction and Force due to Transpiration as Dependent on Pressure

in Gases. By J. L. Hogg 113

VIT. On the Conditions to be Satisfed if the Sums of the Corresponding
Members of Two Pairx of Orthogonal Functions of Two Vari-
ables are to be Themselves Orthogonal. By B. O. Peirce . . 147

VIII. On the Correction for the Effect of the Counter Electromotive Force
induced in a Moving Coil Galvanometer when the Instrument is
used Ballistically. By B. O. Peirce 159

IX. A Simple Device for Measuring the Deflections of a Mirror Gal-
vanometer. By B. O. Peirce 171

X. On the Cytology of the Entomophthoraceae. By L. W. Riddle . 175

XI. A Revision of the Atomic Weight of Bromine. By G. P. Baxter 199

ir CONTENTS.

Page
XII. The Optic Chiasma of Teleosts; : A Study of Inheritance. By

A. P. Larrabee 215

XIII. Fluorescence and Magnetic Rotation Spectra of Sodium Vaj)or,

and their Analysis. By R. W. "Wood 233

XIV. Results of the Franco- American Expedition to Explore the Atmos-

phere in the Tropics. By A. L. Rotch 261

XV. An Approximate Law of Fatigue in the Speeds of Racing Ani-

7nals. By A. E. Kexnelly 273

XVI. A n Experimental Study of the Image-Forming Powers of Various

Types of Eyes. By L. J. Cole 338

XVII. Expansion and C ompressihility of Ether and of Alcohol in the

Neighborhood of their Boiling Points. By A. W. Smith . 419

XVIII. The Hydroids of Bermuda. By E. D. Congdon 461

XIX. The Spermatogenesis of the Myriapods. (V.) On the Sperma-
tocytes of Lithobius. By M. "\V. Blackman 487

XX. Revision of the Genus Spilanthes. By A. H. Moore . . . 519

XXI. Concerning the Adiabatic Determination of the Heats of Combus-
tion of Organic Substances, especiallij Sugar and Benzol By
T, VV. Richards and Messrs. Henderson and Frevert 571

XXII. On the Thomson Effect and the Temperature Coefficient of
Thermal Conductivity in Soft Iron between 115" and 204° C.
By E. H. Hall and Messrs. Campbell, Serviss, and
Churchill 595

XXIII. An Electric Wax-Cutter for Use in Reconstructions. By E. L.

Mark 627

XXIV. Concerning Position Isomerism and Heats of Combustion. By

L. J. Henderson 637

XXV. Temperature of Mars. A Determination of the Solar Heat

Received. By P. Lowell .... 649

XXVI. The Transmission of Rontgen Rays through Metallic Sheets. By

J. M. Adams 669

CONTENTS. V

Page
XXVII. The Process of Building up the Voltage and Current in a Long

Alternating-Current Circuit. By A. E. Kennelly . . 699

XXYIII. The Determination of Small Amounts of Antimony by the
Berzelius- Marsh Process. By C. R. Sanger and J. A.

Gibson 717

XXIX. Records of Meetings 737

Report of the Council 761

Biographical Xotice 761

Edward Atkinson 761

Officers and Committees for 1907-08 771

List of Fellows and Foreign Honorary Members ... . . 773

Statutes and Standing Votes 781

Rumford Premium 792

Index 793

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 1. — May, 1906.

CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD

UNIVERSITY.

New Series. — No. XXXII.

STUDIES IN THE EUPATORIEAE.

I. Revision of the Genus Piqueria.
II. Revision of the Genus Ophryosporus.

III. The Genus Helogyne and its Synonyms.

IV. Diagnoses and Synonymy of Eapatorieae and of certain other

Compositae which have been classed with them.

By B. L. Robinsox.

CONTRIBITTIOXS FROIM THE GRAY HERBARIUM OF HARVARD
UNIVERSITY, NEW SERIES, NO. XXXTT.

STUDIES IN THE EUPATORIEAE.
By B. L. RoBixsox.

Presented March 14, 1906. Received February 21, 1906.

Introductory.

During the summer of 1905 the writer spent some weeks in visit-
ing several of the larger herbaria of Europe in order to examine and
photograph plants not hitherto authoritatively represented in the
Gray Herbarium. In the course of this work considerable attention
was given to the tropical American species of the great genus Eupa-
torium and several allied genera. As must be expected in all such
large and difficult groups, which have not been subjected to recent
revision, the study of the type-specimens of several hundred species
has yielded much new information on the synonymy and proper classi-
fication of the group. The collections examined were : (1) the herba-
rium of the Museum of Natural History in Paris, where the herbaria
of Jussieu, Lamarck, and Michaux were consulted, and special atten-
tion given to an admirably preserved and well-nigh complete set of the
tropical American plants collected by Humboldt and Bonpland and
critically described by Kunth in the Nova Genera et Species ; (2) the
rich private herbarium of the DeCandolle family in Geneva, including
the invaluable Prodromus types ; (3) the herbarium of the Imperial
Museum of Natural History at Vienna, noteworthy among other ways
by containing the fullest series available of the species of Jacquin and
an excellent series of the plants of Pohl and species of Poeppig and
Endlicher; (4) the herbarium of the Royal Botanical Museum at
Berlin, remarkably rich in South American as well as in Old World
types and in the study of Eupatorieae specially noteworthy by ex-
hibiting to its fullest extent the recent critical work of Dr. Hieronymus ;
(5) Professor Urban's large and carefully selected West Indian her-
barium ; (6) the herbarium of the Botanical Museum of the University
of Copenhagen, containing, together with much other material of in-
terest, the extant types of Vahl ; (7) the herbarium of the Linnean

4 PROCEEDINGS OF THE AMERICAN ACADEMY.

Society of London, where special attention was given to the types
of Linnaens filius and of Sir James Edward Smith ; (8) the her-
barium of the Royal Botanical Gardens at Kew, noteworthy to the
student of the Eupatorime by exhibiting the very numerous Brazilian
types of Gardner, Hooker & Arnott, Bentham, and Baker, as well as
the Mexican work of Hemsley; (9) the herbarium of the British
Museum of Natural History, including, among many other specimens
of high interest, the plants of Clayton, Walter, and Philip Miller.

The writer would here express his sincere thanks to all those in
charge of these herbaria for their cordial hospitality, uniform courtesy,
and valuable aid during his researches. He is also indebted to Messrs.
Oakes Ames and A. A. Eaton for several excellent photographs of
type- specimens at Paris, to Mr. H. Hua for a critical comparison of a
Peruvian Piqueria in the herbarium of Jussieu, to Miss Mary A. Day,
Librarian of the Gray Herbarium, for bibliographical assistance, and
to Mr. F. V. Coville and Dr. J. N. Hose for the loan of the material of
Piqueria belonging to the United States National Museum.

About four hundred photographs of types were taken in the Euro-
pean herbaria, some important exchanges effected, and many notes and
sketches prepared, which it is hoped may form an accurate basis for
considerable work on the group concerned. 1\\ the present paper only
a small part of the results of the summer's investigation can be pre-
sented, but as any complete or monographic treatment of so large a
group must be delayed for a considerable time, it seems best to record
such identities and synonymy as can be at once stated with definite-
ness, in order that certain traditional errors may not become more fixed
by longer usage. The nomenclature adopted is that recommended by
the international congress at Vienna.

L Revision of the Genus Piqueria.

Piqueria is the typical genus of the Piqueriiiae, a small subtribe of
the Eapatorieae. The Piquertnae are chiefly marked by their blunt
anthers, which entirely lack the more or less expanded, oblong, or
lanceolate prolongation of the connective, which is present almost
without exception in other Compositae. In this subtribe the genus
Piqueria is characterized by a complete absence or very rudimentary
development of its pappus. Its natural affinities are obviously on
one hand with Op/iri/osporu.% which scarcely differs save in the pres-
ence of a well-developed setose pappus, and on the other hand with
Ahmia and Ageratum, which are habitally approached by the species
of Piqueria belonging to the subgenus Phalacraea. Geographically
Piqueria extends from the Sierras of northern Mexico through central

ROBINSON. — STUDIES IN THE EUPATORIEAE. 5

and southern Mexico, Central America, and Andean South America
to northern Chili. The only known exception to this range of the
genus is the occurrence of P. trhurvia Cav. in the mountains of
Haiti, a station called to my attention by Professor Urban. The
genus is capable of pretty clear division into four subgenera, of which
Erythradenia is Mexican, Eup'tqueria is of Mexico, Central America,
and Haiti, Phalacraea of the moister Andean region from Colombia to
Ecuador, and Artemisioides characteristic chiefly of the drier parts of
the Andes of Peru and Chili.

Since the treatment of some eight species in DeCandolle's Prodromus
in 1836 no effort has been made to revise the genus, although the
number of its species has been considerably increased since that time.
The following revision has been drawn up after personal examination
of nearly all the specific t}^es and of all the specimens of the genus
found in several of the leading herbaria of Europe.

PIQUERIA Cav. (in memoriam Andreae Piquerii — hispanice, An-
dres Piquer — medici hispanici et auctoris philosophici). — Capitula
parva homogama 3- » -flora, involucro ovoideo vel cylindrico vel
campanulato, squamis saepius paucis subaequalibus laxe imbricatis
vel subuniseriatis, receptaculo nudo piano vel leviter convexo. Co-
rollae tubulosae albae vel caerulescentes, tubo proprio saepissime brevi
piloso vel glanduloso-puberulo, faucibus saepe ampliatis, dentibus
limbi ovato-deltoideis suberectis vel saepius ovati-oblongis et paten-
tibus acutiusculis. Achaenia 5-angulata prismatica deorsum plus
minusve angustata basi saepe oblique callosa apice rotundata calva
vel disco annulari deciduo vel rarissime setis paucis brevibus coronata.
Styli rami filiformi-clavellati louge exserti saepe valde recurvati.
Antherae breviter oblongae, connectivo apice nee incrassato nee ap-
pendiculato. — Ic. iii. 18, t. 235 (1795); Usteri, N. Ann. xviii. 62
(1800) ; Pers. S)ti. ii. 397 (1807) ; Rees, Cycl. xxvii. (18U) ; Cass. Bull.
Soc. Philom. 1819, p. 127 (1819), et Diet. Sci. Nat. xli. 115 (1826) ; Less.
Syn. 154 (1832); DC. Prod. v. 104 (1836); Endl. Gen. 366 (1838);
Eeichenb. Nom. 97 (1841); Jameson, Syn. PI. Aequat. ii. 75 (1865);
Benth. et Hook. £ Gen. ii. 238 (1873) ; Hemsl. Biol. Cent. -Am. Bot.
ii. 77 (1881); Hoffm. in Engl, et Prantl, Nat. Pflanzeuf. iv. Ab. 5,
133 (1890) ; Hook, f et Jacks. Ind. Kew., ii. 544 (1894) ; Bailey et
Scott in Bailey, Cycl. Hort. iii. 1357 (1901). Phalacraea DC. Prod. v.
105 (1836); Endl. Gen. 366 (1838). Stevia Hort. — Herbae annuae
vel perennes vel frutices. Caulis erectus vel decumbens foliosus ramo-
sus. Folia opposita vel alterna petiolata vel subsessilia Integra vel
saepius serrata vel dentata vel rarius angulata.

b PROCEEDINGS OF THE AMERICAN ACADEMY.

Species 19 generaliter bene distinctae quarum 5 Mexicanae sunt, una
Mexicana et Centrali- American a etiam Haitensis, reliquiae Andium
montium Australi-Americae incolae.

Clavis subgenerum.

a. Corollae fauces tubulosi a tubo proprio non distinct!. Folia alterna, glan-
duloso-punctata Subg. I. Erythradenia.

a. Corollae fauces ampliati a tubo proprio bene distinct!. Eolia opposita vel
alterna. b.
b. Corollae fauces turbinati, brevissimi, dentibus linibi breviores ; tubus
proprius villosus vel rarissime glanduloso-puberulus.

Subg. II. ECPIQUERIA.

b. Corollae fauces campanulati vel cylindrici dentibus limbi longiores.
Corolla externe praesertiiu tubo glanduloso-puberula. c.

c. Capitula 4-5-flora Subg. III. Artemisioides.

c. Capitula IS-oo -flora Subg. IV. Phalacraea.

Subg. I. Erythradenia, subg. nov. Capitula circa 6-flora sessilia
in panicula ampla pyramidata disposita. Corolla subcylindrica glan-
duloso-puberula sine faucibus distinctis ; dentibus brevissimis. Folia
alterna. — Species unica habitu distinctissima.

1. P. pyramidalis Robinson, caule tereti maculato 2-2.6 m. alto
omnifariam puberulo-velutino ; foliis alternis magnis longe petiolatis
late ovatis vel suborbicularibus angulatis vel leviter lobatis crenato-
dentatis 3-nerviis, basi rotundatis vel cordatis supra viridibus subtus
griseis et glandulis parvis globosis numerosissimis brevissime stipitatis
rubris munitis in nerviis et venis reticulatis velutino-tomentellis ; pa-
nicula ampla folioso-bracteata, ramis ascendentibus ; capitulis in glo-
merulis sessilibus ca. 6-floris ; involucri squamis anguste oblongis dorso
pubescentibus ; coroUis anguste tubulosis externe glanduloso-punctatis,
dentibus brevissimis ; achaeniis 5-angulatis, basin versus leviter angu-
statis parum obliquis, costis sursum hispidulis. — Proc. Am. Acad.
xxxvi. 475 (1901). — Mexico: in rupibus umbrosis montium supra
Igualam, alt. 1250 m., Fringle, n. 8389 (hb. Gray, hb. U. S. Nat. Mus.).

Subg. II. Eupiqjjeria DC. Capitula parva 3-4-flora cymoso-corym-
bosa vel laxe paniculata, involucro anguste obovoideo vel subcylindrico,
squamis 3-4 subaequalibus obovatis vel oblongis concavis tenuibus,
apice obtusis vel rotundatis mucronatis eroso-subciliatis rarius dorso
pubescentibus. Corollae tubus proprius extus pubescens, dentibus
limbi oblongo-lanceolatis acutiusculis paten tibus. — Prod. v. 104 (1836) ;
Endl. Gen. 366 (1838); Hoffm. in Engl. & Prantl, Nat. Pllanzenf. iv,
Ab. 5, 133 (1890) pro parte; nee Gardn.; nee Walp. — Vel berbae
annuae vel perennes vel frutices. Folia opposita lanceolata vel ovata
breviter petiolata.

ROBINSON. — STUDIES IN THE EUPATORIEAE.

Clavis specierum.

a

Involucri squamae dorso pubescentes 2. P. trijlora.

a. Involucri squamae dorso glabrae, b.

b. Herba annua. Inflorescentia perlaxa, racemiformis. . . 3. P. laxiflora.
h. Herbae perennes. Inflorescentia plus minusve corymbosa. Achaenia basi
valde obliqua. c.

c. Caulis omnifariam pilosus vel puberulus 4. P. pilosa.

c. Caulis bifariam solum puberulus 5. P. trinervia,

b. Frutices. Achaenia basi subrecta 6. P. serrata.

2. P. TRiFLORA Hemsl., caule tereti vel supra subhexagono ubique
pilosiusculo folioso 4 dm. alto plus minusve ramoso; foliis oppositis
anguste lanceolatis basi perangustatis subsessilia caudato-attenuatis
sed in apice vero obtusiusculis 3-6 cm. longis 5-9 mm. latis utrinque
crispe puberulis remote serratis vel subintegris ; inflorescentia laxe
ramosa racemiformi ; bracteolis linearibus ; pedicellis filiformibus uni-
lateraliter pilosis 3-7 mm. longis ; capitulis numerosis obovoideis ;
involucri squamis 3 obovatis carinatis 3-nerviis scarioso-marginatis
eroso-ciliatis apice rotundatis mucronatis, dorso hirsuto-pubescenti-
bus ; flosculis 3 ; corolla alba ; tubo proprio extus lanato ; faucibus
quam dentes 5 oblongo-lanceolati brevioribus ; achaeniis atro-fuscescen-
tibus glabris 1.7 mm. longis. — Biol. Cent-Am. Bot. ii. 77 (1881). —
Mexico : Cerro de Pinal, Seemwin, n. 1478 (hb. Kew., hb. Gray).

3. P. LAXIFLORA Robinson & Seaton, herbacea tenuis laxe et copiose
ramosa ; radice annua ; caule tereti viridi 4-5 dm. alto piloso ; foliis
oppositis, ovatis vel ovato-lanceolatis serratis 3-5-nerviis sparse pilosis
basi cuneatis petiolatis apice obtusiusculis ; inflorescentia trichotomo-
furcata racemiformi ; bracteolis subfiliformibus 2-4 mm. longis ; pedi-
cellis fere capillaribus 1 cm. longis flexuosis ; capitulis obovoideis
parvis 4-floris ; involucri squamis viridibus obovatis mucronatis erosis
tenuibus persistentibus ; corollis albis ; tubo perbrevi externe pubes-
cent! ; achaeniis atro-fuscescentibus 5-angulatis glabris lucidis. — Proc.
Am. Acad, xxviii. 107 (1893). — Mexico: in rupibus frigidulis con-
vallium montanarum prope lacum Chapalam, Pringle, n. 4333 (hb.
Gray, etc.) ; montibus prope Durango, Pringle, n. 10,067 (hb. Gray).

4. P. PILOSA HBK., herbacea perennis ramosa 5-13 dm. alta; caule
subtereti omnifariam glanduloso-puberulo saepe purpurascenti folioso ;
foliis oppositis petiolatis ovatis serratis acuminatis 4-6 cm. longis
2-3 cm. latis utrinque puberulis ; petiolo 4-10 mm. longo glanduloso-
puberulo ; inflorescentia trichotoma cymoso-corymbosa ; capitulis par-
vis numerosis saepe congestis 4-floris ; involucri squamis 4 ellipticis
margine scariosis erosis apice rotundatis mucronatis dorso glabris;
corollis albis, tubo brevi piloso-lanato, faucibus brevibus, dentibus

8 PROCEEDINGS OF THE AMERICAN ACADEMY.

limbi 5 lanceolati-oblongis acutiusculis patentibus ; acbaeniis 5-angu-
latis glabris 2 mm. longis. — Nov. Gen. et Spec. iv. 158 (1820); Cass.
Diet. Sci. Nat. xli. 116 (1826); DC. Prod. v. 104 (1836); Hemsl. Biol.
Cent.-Am. Bot. ii. 77 (1881). P. trinervia, y&y. pilosa 0. Kuntze, Rev.
Gen. i. 355 (1891). F. Fringlei in sched. Pringlei pro parte, non
Robinson & Seaton. — LIexico (praecipue in montibus partis centralis
rei publicae) : Humboldt et Bonjiland, n. 4342 (bb. Par.) ; Alaman (bb.
DC.) ; Real del Monte, Ehrenherg, n. 481 (bb. Berol., bb. Gray) ; Bates
(bb. Kew.) ; silvis deserti Vieja, Bourgeau, n. 828 (bb. Berol.) ; Bour-
geau, n. 825 partim (bb. Par.); Uhde, nn. 414, 416 (bb. Berol.);
Tacubaya, Schaffner, n. 300 (bb. Berol.) ; Pringle, nn. 3624, 4119, 4285
partim, 7930 (bb. Gray, etc.) ; Sierra de Pacbucba, Hidalgo, Rose^
n. 8867 (bb. U. S. Nat. Mus.).

Var. Pringlei (Robinson & Seaton), n. comb., caule et inflorescentia
omnino eglandulosis pubescentibus ; pilis brevibus albidis crispis. —
P. Pringlei Robinson & Seaton, Proc. Am. Acad, xxviii 107 (1893). —
Mexico : saepe cum forma typica : pinetis convallis mexicanae, Bour-
geau, n. 825 partim (bb. Gray, bb. Kew.); Hchmitz, n. 398 (bb. Imp.
Mus. Vindob.) ; Pringle, n. 4285 partim (bb. Gray) ; Sierra de las
Cruces, alt. 3000 m., Pringle, n. 11,563 (bb. Gray).

5. P. TRINERVIA Cav., berbacea perennis erecta ramosa; radice fibrosa ;
caule tereti bifariam puberulo folioso 4-7 dm. alto ; foliis oppositis
lanceolatis vel anguste ovatis serratis subglabris 3 (-5)-nerviis crassi-
usculis basi cuneatis apice attenuatis ; capitulis parvis saepius 4-floris
laxe cymoso-corymbosis vel rarius in inflorescentia perlaxa racemiformi
dispositis ; involucri squamis ellipticis erosis margine tenuibus apice
rotundatis mucronatis ; corollis albis, tubo proprio brevi piloso, fauci-
bus brevissimis, dentibus limbi 5 ovato-oblongis patentibus ; acbaeniis
atrofuscis 5-angulatis basi oblique sigmoideo-callosis. — Ic. iii. 19,
t. 235 (1794); Willd. Spec. iii. 1748 (1804); Pers. Syn. ii. 397 (1807);
Jacq. f. Eel. i. 70, t. 48; Bot. Mag. t. 2650 (1826); Cass. Diet. Sci.
Nat. xli. 116 (1826); DC. Prod. v. 104 (1836); Hemsl. Biol. Cent.-
Am. Bot. ii. (1881) ; Rose, Contrib. U. S. Nat. Herb. v. 231 (1899);
Bailey, Cycl. Am. Hort. iii. 1357 (1901). P. trinervis J. E. Smitb in
Rees, Cycl. xxvii. n. 1 (1817). P. ovata G. Don in Loud. Hort. Brit.
337 (1830). Ageratum fehrifugum Sess. ex DC. Prod. v. 104 (1836).
Stevia febrifuga Moc. ex DC. 1. c. S. serrata et serratifolia Hort. —
Mexico : vulgaris et late distributa praecipue in arvis et collinis ad
2900 m. alt. Exsiccatis visis : Ai^chenborn, nn. 201, 580; Bates ; Ber-
landier, nn. 704, 1210, 1241; BiUmek; n. 578; Botteri, nn. 13, 391;
Bourgeau, nn. 144, 149, 288, 1402 ; Conzatti et Gonzalez, n. 1087 ;
Coidter, n. 721; Beam; Ehrenberg, n. 480; Galeotti, nn. 2108, 2414,

ROBINSON. — STUDIES IN THE EUPATORIEAE. y

2482; Graham, nn. 22, 23; Halsted, n. 27; Harris; Humboldt et
Bonpkind, nn. 4228, 4258, 4401 ; Karwinski, n. 104 ; Kerber, n. 328 ;
Lagasca, n. 128; Liebmann, n. 110; Nelson, nn. 1720, 1928, 3176,
3463 ; Palmer, nn. 85, 313, 496|-, 596 ; Parry et Palmer, nn. 85, 314 ;
Pringle, nn. 241, 1748, 5686, 9053, 9951; Purpus, n. 55; Hose,
n. 2767; Sartorius ; Schaffner, n. 235; Schiede, n. 303; Schmitz,
n. 73; Schumann, n. 62; Seaton, n. 276; C. e^ ^. Seler, n. 1153;
a X. Smith, n. 1664; X. (7. Smith, n. 291 ; 6Wg, nn. 349, 412, 413,
448. Guatemala : Heyde et Lux, n. 3399 pi. exsic. J. D. Smithii
(hb. Kew., hb. U. S. Nat. Mus.). Costa Rica : Cooper, n. 5811 pi.
exsic. J. D. Smithii (hb. Gray, hb. Kew.). Haiti : in montibus Furcy,
Picarda, n. 1521 (hb. Urb.), forma capitulis pauUo majoribiis ad var.
luxuriantem spectans.

NoTA. — Herba a horticultoribus sub nomine " Stevia " late culta et ob inflor-
escentia eleganter ramosa bene aniata, a Mexicanis pro febrifuga, etiam a
Cubensibus ut dicitur loco condiment! usa.

Xo.MiNA VERNACULA : Empueshta, Hierba de San Nicolas, Hicrba del tabar-
dillo, Xoxonitzal, Xoxonitztac, Yoloxiltic ; omnia fide cl. G. V. Alcocer.

Var. VARiEGATA Hort. ex Bailey, Cycl. Am. Hort. iii. 1358 (1901), est
forma calidariarum foliis albo-marginatis.

Var. NANA Hort. ex Bailey, 1. c, 1357, humilior 2-3.5 dm. alta folio-
sissima. — Forma ut videtur mexicana in calidariis saepe culta. Speci-
minia inculta sunt rara, e. g. Mexico : Mehedin, 1864-5 (hb. Par.),
Zacatecas, Beam, n. 141 (hb. Gray).

Var. LUXURiANS 0. Kuntze, foliis ovatis argute serratis 4-9 cm.
longis 2.3-4 cm. latis 5-nerviis.glabriusculis basi rotundatis, petiolo ca.
1 cm. longo ; capitulis quam ea formae typicae distincte majoribus ;
achaeniis 2.4 mm. longis. — Rev. Gen. i. 355 (1891). — Costa Rica :
silvis montanis in declivitatibus mentis ignivomi Irazu, C. Hoffmann,
n. 171 (hb. Gray); Kuntze; Pittier, n. 14,080 (hb. Gray).

6. P. SERRATA Gray, fruticosa ramosa primo aspectu glaberrima;
caule tereti pallide viridi obsolete bifariam puberulo folioso; foliis
oppositis ovati-oblongis acuminatis grosse arguteque serratis basi
abriipte angustatis breviter petiolatis 7-9 cm. longis 2.5-4 cm. latis
glaberrimis ; capitulis cymoso-cor}Tnbosis numerosis 3-floris ; involucri
squamis elliptico-ovatis 3-nerviis apice rotundatis mucronatis margine
ciliato-erosis dorso glabris ; corollis albis, faucibus brevissimis, dentibus
limbi oblongo-lanceolatis patentibus glabris, tubo proprio breviter sub-
glanduloso-puberulo ; achaeniis 5-angulatis glaberrimis annulo deciduo
coronatis basi callosis parum obliquis. — Proc. Am. Acad. xv. 25 (1880).
— Mexico : in montibus Alvarez prope San Luis Potosi, Parry et

10 PROCEEDINGS OF THE AMERICAN ACADEMY.

Palmer, n. 496 (hb. Gray, bb. U. S. Nat. Mus.), Palmer, n. 199 (bb.
Gray).

Var, (?) ANGUSTiFOLiA Robinson & Greenman, foliis angustioribus
lanceolatis obscure et remote serrato-crenatis basi cuneato-angustatis ;
capitulis eis formae typicae exacte siinilibus. — Am. Jour. Sci. 1. 151
(1895). — Mexico: in montibus Sierra de San Felipe, Oaxaca, alt.
2800-3300 m., Pringle, n. 4827 (bb. Gray, etc.). Nelson, n. 1049
(hb. Gray), C. L. Smith, n. 605 (hb. U. S. Nat. Mus.).

Subg. III. Artemisioides DC. Capitula 3-4-flora, involucro
subcylindrico, squamis saepius 4 subaequalibus. Corollae externe
glanduloso-punctatae, glandulis minutis rubescentibus brevissime
stipitatis ; faucibus cylindricis vel subcylindricis tubo proprio sub-
aequantibus, quam dentes limbi distincte longioribus. Achaenia
deorsum plus minusve angustata parum obliqua. — Prod. v. 105
(1836). — Frutices ramosi andini. Folia opposita vel alterna rhom-
boidea vel lanceolata vel linearia basi cuneata petiolata.

Clavis specierum.

a. Folia alterna fasciculata. h.

b. Capitula in panicula laxiuscula subrigida disposita. Involucri squamae

oljtusiusculae 1. P. yalioides.

b. Capitula congesta. Involucri squamae breviter acuminatae vel attenuatae.
Pappus e setis paucis brevissimis compositus vel nullus. c.
c. luflorescentia thyrsoidea. Involucri squamae lineari-lanceolatae.

8. P. pinifolia.
c. luflorescentia cymosa. Involucri squamae rhomboideo-oblongae acix-

tatae vel breviter acuminatae 9. P. Cuming iL

a, Folia opposita. d.

d. Involucri squamae 3.5-5 mm. longae. e.

e. luflorescentia fulvo-tomentosa. Folia flabelliformi-ovata sinuato-

dentata 10. P. pubescens.

e. luflorescentia obscure glanduloso-puberula. Folia ovata serrato-
dentata. f.

f. Involucri squamae apice eroso-ciliatae 11. P. Maihewsii.

f. Involucri squamae dorso granulatae nee erosae nee ciliatae.

12. P.ftoribunda.
d. Involucri squamae 2-2.7 mm. longae. g.

(J. Capitula prope apices ramorum late patentium paniculae congesta.

13. P. densiflora.
g. Capitula (numcrosissima) spicato-raccmosa in panicula subfastigiata

folioso-bracteata disposita. h.
h. Folia lanceolata dentata vel incisa. Capitula sessilia.

14. P. peruviana,
h. Folia caulina linearia subintegra. Capitula breviter pedicellata.

15. P. Hartwegi.

ROBINSON. — STUDIES IN THE EUPATORIEAE. 11

7. P. GALIOIDES DC, fruticosa ramosa glabriuscula ; foliis alternis
fasciculatis linearibus opacis utrinque attenuatis acutis sessilibus in-
tegris subenerviis 1.5-2 cm. longis 2 mm. latis ; panicula rigidiuscula
patente ramosa pyramidal! nudiuscula ; capitulis baud congestis
racemoso-spicatis subdivaricatis 3-floris ; involucri ca. 4 mm. longi
squamis subobtusis. — Prod. v. 105 (1836). — Peru: ia Cordilleriis,
Haenke, 1834 (bb. DC). Species ut videtur bene distincta sed vix
satis nota.

8. P. pinifolia (Pbil.) Hieron. in herb., fruticosa ramosa 6-12 dm.
alta, novellis plus minusve glutinosis ; ramis arcuato-ascendentibus
teretibus foliosissimis cortice griseo-flavido tectis; foliis in fasciculis
alternis vel irregulariter sparseque dispositis suberectis anguste lance-
olatis integerrimis vel utroque cum 2-3 dentibus brevibus patentibus
subremotis instructis apice modice acutis basi attenuatis 1.5-3 cm.
longis 2-6 mm. latis utrinque puberulis ; thyrsis ovoideo-cylindricis
6-12 cm. longis 3-5 cm. crassis, ramulis rigidiusculis patentibus;
capitulis in apice ramuli saepius 2-3 approximatis sessilibus 4-5-
floris ; involucri squamis 5 lineari-lanceolatis attenuatis subaequalibus
laxis stramineis dorso rotundatis l-nerviis 6 mm. longis glanduloso-
puberulis margine involutis; coroUis roseis tubulosis 3.5 mm. longis
glanduloso-puberulis in fauces plus minusve ampliatis, dentibus
limbi ovato-deltoideis patentibus ; achaeniis 5-angulatis basi attenu-
atis puberulis summo saepius calvis rarius obsolete setuliferis. —
Stevia pinifolia Phil. Ann. Mus. Nac. Chil. sec. 2 (botanica), 37
(1891); Reiche, Fl. de Chil. iii. 262 (1902). Piqueria innifolia
Hieron. in herb. Berol. — Chili : Atacama, Phili'ppi (hb. Berol.).
Peru : In montibus Andinis supra Palcam, d'Orbigny (hb. Par.) :
Pachia, alt. 1200-1900 m., Pearce, Sept. 1862 (hb. Kew.). Specimen
Pearcei est a cl. Benthamio (Gen. PI. ii. 238) ad hoc genus sed sine
nomine relatum.

9. P. Cumingii, n. sp., fruticosa ramosa, novellis vernicosis, ramis
teretibus flavidis foliosissimis valde patentibus juventate pulverulento-
puberulis ; foliis fasciculatis anguste oblanceolatis obtusis vel obtusius-
culis integerrimis vel cum dentibus unicis vel pluribus munitis 1-1.6
cm. longis 2-4 mm. latis basi attenuatis uninerviis glaberrimis plus
minusve viscosis ; inflorescentiis arete congestis corymbosis, ramulis
valde patentibus arcuato-ascendentibus; capitulis constipatis 5-floris;
involucri squamis oblongis vel subrhomboideis acutis saepe vernicosis
5 mm. longis ; corollis 3 mm. longis, tubo proprio quam fauces tubulosi
breviori glanduloso-pulverulento ; achaeniis pallidis substramineis pris-
maticis 5-angulatis 3 mm. longis basi attenuatis callosis in faciebus
puberulis. — Peru meridionali et Chili septentrionali : Cobija,

12 PROCEEDINGS OF THE AMERICAN ACADEMY.

IquiquI, et Arica, 1831, H. Cuming, n. 953 (hb. Kew.) ; Cobija, 1841,
Gaudichaud (hb. BeroL).

10. P. PUBESCENS J. E. Sm., fruticosa oppositiramea 1-2 m. alta;
caulibus teretibus a cortice griseo tectis ; ramulis foliosis glanduloso-
tomentellis ; foliis oppositis, late rhomboideis, grosse arguteque in-
aequaliter dentatis basi cuneatis vel abrupte angustatis graciliter
petiolatis 1.4-3.3 cm. longis 1-3.6 cm. latis sub lente utrinque
papilloso-granulosis, petiolo fulvo-tomentoso 8-18 mm. longo ; capi-
tulis numerosis congestis corymbosis 4-5-floris ; involucri squamis
anguste oblongis attenuatis dorso glanduloso-puberulis ; corollis albis
vel (?) flavidis.— J. E. Smith in Kees, Cycl. xxvii. n. 2 (1814); DC.
Prod. V. 105 (1836). P. qidnqmflora Cass. Bull. Soc. Philom. 1819,
p. 128 (1819), et Diet. Sci. Nat. xli. 116 (1826); DC. Prod. v. 105
(1836). — Peru: spec. typ. in hb. L. f. (hb. Linn. Soc); Domherj (hb.
Par.); Mathews, n. 946 (hb. Gray) ; Obrajillo, Wilkes (hb. Gray, hb.
U. S. Nat. Mus.) ; Lima, Cuming, n. 1045 (hb. Brit. Mus.) ; ad pedem
montis Amancaes prope urbem Lima, 21 Julio, 1876 (floribus albis),
Andre, n. 4117 (hb. Gray); in rupibus prope Lima, 30 Nov. 1901,
Weberhauer n. 9 (hb. BeroL).

11. P. Mathewsii, n. sp., suffruticosa oppositiramea; ramis tenuibus
rubescentibus glaberrimis; foliis oppositis membranaceis ovatis crenato-
serratis vel grosse-dentatis acuminatis graciliter petiolatis 3-5-nerviis
utrinque viridibus glabris 4-6 cm. longis 2-3 cm. latis, petiolo 7-10
mm. longo ; panicula laxe ramosa, ramis gracilibus teretibus puberulis
valde patentibus vel arcuato-ascendentibus prope apicem capitula
subcorymbosa ferentibus ; capitulis 4-5-floris ; involucri squamis
breviter acuminatis vel saepius obtusiusculis ca. 5 mm. longis apice
ciliolatis ; corollis valde exsertis, tubo proprio gracili glanduloso-
j)uberulo, faucibus cylindricis bene distinctis quam dentes limbi
longioribus. — Peru: Purruchuca, Mathsws, n. 1015 (hb. Kew.).

12. P. FLORIBUNDA DC, fruticosa oppositiramosa minutissime pu-
berula vel subglabra ; ramis patentibus griseo-fuscis foliosis ; foliis
oppositis ovatis serrato-dentatis acutis basi rotundatis vel abrupte
angustatis graciliter petiolatis subglabris 1-2 cm. longis ; panicula
patente ramosa pyramidal! 7-11 cm. lata; capitulis numerosis 4-6-
floris; involucri anguste cylindrici squamis oblanceolati-oblongis vel
-linearibus 3-costatis dorso convexis et glanduloso-puberulis acutis ;
corollis albis, tubo proprio gracili dense glanduloso-atomifero quam
fauces cylindrici subglabri breviori, limbi dentibus deltoideis brevibus ;
achaeniis gracillimis prismaticis 5-angulatis basi gradatim attenuatis
subrectis, angulis glanduloso-hispidulis. — Prod. v. 105 (1836) ; Phil.
Cat. PL Vase. ChiL 174 (1881). — Peru : in montibus Andinis, Haenke,

ROBINSON. — STUDIES IN THE EUPATORIEAE. 13

1834 (hb. DC); ObrajiUo, Wilkes (hb. Gray, hb. U. S. Nat. Mus.);
in rupibus inter Matucana et Tambo, alt. 2370-2650 m., Weberbauer,
n. 115 (hb. Berol.). Chili : Haenke sec. DC. sed dubitative.

NoTA. — Habitatio originalis a DC. data " montanis Oronocensibus " possit
forsan errore pro montanis Huanoccensibus.

13. P. DENSiFLORA Benth., fruticosa vel paene herbacea glabriuscula;
ramis plus minusve flexuosis gracilibus teretibus, internodiis quam
folia saepius longioribus ; foliis oppositis membranaceis ovatis vel
rhomboideis graciliter petiolatis acuminatis serratis 3-nerviis 5-6 cm.
longis, petiolo ca. 1 cm. longo ; foliis superioribus lanceolati-oblongis
integris ; panicula pyramidali oppositiramea, ramis patentissimis basi
nudis prope apicem capituliferis puberulis ; capitulis congestis 4-5-floris
cylindricis; involucri squamis oblongo-linearibus 2.5 mm. longis gla-
briusculis apice subobtusis eroso-ciliatis ; coroUis valde exsertis 2.5 mm.
longis, tubo gracili glanduloso-puberulo, faucibus campanulato-ampliatis
glabris vel obsolete granulatis, dentibus limbi 5 anguste oblongis revo-
lutis acutis ; achaeniis glaberrimis 1.6 mm. longis nigris lucidis summo
disco annulari coronatis. — Bot. Sulph. 110 (1845); Jameson, Syn. PI.
Aequat. ii. 75 (1865). — Ecuador: Insula Puna prope Guayaquil,
1841, Hinds, n. 401 (hb. Kew.); in terra pingui agrorum fruticiferorum
Insulae Punae 1-2 m. alta floribus albis, Sept. 1838, Barclay, nn. 412,
2426 (hb. Brit. Mus.) ; reg. trop., Sodiro, n. 3/4 (hb. Berol.). Specimen
dubium ex herb. Thibaudii verosimiliter a Neeo lectum sed sine ullo
indicio loci in hb. DC iuvenitur.

NoTA. — CI. Bentliamius asseveravit in descriptione principali hujus ispeciei
" antlierae apice appendiculatae," sed dissectio a cl. Brittenio in iierbario Musei
Britannicibenevolente permissa et ab auctore maxima cum cura facta flosculorum
e specimine Barclayano antheras sine ulla dubitatione inappendiculatas cxliibuit.

14. P. peruviana (Gmel.), n. comb., fruticosa 2-4 m. alta oppositi-
ramea subglabra; foliis oppositis tenuibus rhomboideo-lanceolatisattenu-
atis inferioribus grosse arguteque serratis basi cuneatis 3-nerviis supra
viridibus glaberrimis subtus vix pallidioribus in nerviis puberidis
6-10 cm. longis, petiolo 1.5 cm. longo, foliis superioribus multo minori-
bus vix serratis vel etiam integerrimis ; panicula ramosissima pyramidali,
ramis ascendentibus foliosis ; capitulis parvis sessilibus basi unibracteo-
latis ; bracteolis margine pubescentibus ; involucri squamis 4 aequalibus
anguste oblongis obtusis ciliatis basi calloso-incrassatis ; flosculis saepius
4. — Flaveria peruviana [Juss.] Gmel. Syst. ii. 1269 (1791). F. sp.
Peruviana a Dombeyo data Juss. Gen. 187 (1789). F. spicata J. E. Sm.
in Bees, Cycl. xiv. n. 2 (1810). Piqueria artemisioides HBK. Nov.

14 PROCEEDINGS OF THE AMERICAN ACADEMY.

Gen. et Spec. iv. 153 (1820); DC. Prod. v. 105 (1836); Loud. Hort.
Brit. 337 (1830) ubi errore dicitur originem mexicanam habere. —
Peru : Lima, Domheij (hb. Par., hb. Berol.) ; Lima et Peruvia septentri-
onali, Cuming, n. 1037 (hb. Kew.) ; Mathews, n. 413 (hb. Gray) ; Besser
(hb. Berol.); Wilkes (hb. Gray); Weberbauer, nn. 8, 8a, 39, et 200
(hb. Berol.). Ecuador : Alampi, Humboldt et Bonpland, n. 3229 (hb.
Par.) ; in montibus Andium prope Alausi, Huataxi, etc., in fruticetis
frequens, ^Spruce, n. 5965 (hb. Kew., hb. Par., hb. Vindob., hb. Gray),
"floribus albis suaveolentibus."

15. P. Hartwegi, n. sp. fruticosa 9-12 dm. alta; ramis flexuosis
teretibus juventate puberulis deinde glaberrimis a cortice griseo tectis ;
foliis oppositis saepius fasciculatis linearibus glabris obsolete crenulato-
serratis subtus pallidioribus 4-5.5 cm. longis 4 mm. latis uninerviis et
mediocriter reticulato-venulosis ; capitulis numerosissimis 4-fioris in
panicula elongata ramosissima racemose dispositis, lateralibus breviter
sed distincte pedicellatis, terminalibus plus minusve glomeratis sessi-
libus; coroUis 1.7 mm. longis albis, tubo proprio puberulo fauces
campanulato-ampliatos subaequanti, dentibus recurvis ; styli ramis
longe exsertis apice mediocriter incrassatis ; achaeniis immaturis. —
P. artemisioides Benth. PI. Hartw. 136 (1844), non HBK. — Peru:
El Catamayo, Hartweg, n. 762 (hb. Kew., hb. Par., hb. Vindob., hb.
Berol).

Subg. IV. Phalacraea Benth. et Hook. f. Capitula 15-xflora-
corymbosa, involucro campanulato, squamis 7-oo. Corolla externe
glanduloso-punctata, glandulis parvis rubescentibus brevissime stipi-
tatis, tubo proprio brevi, faucibus campanulatis vel cylindricis quam
dentes limbi longioribus. — Gen. ii. 238 (1873) ; Hofifm. in Engl, et
Prantl, Nat. Pflanzenf. iv. Ab. 5, 133 (1895). Phakirraea DC. Prod.
V. 105 (1838); Deless. Ic. iv. 3, t. 8 (1839); Hegel, Gartentl. iii. 388,
t. 107 (1854). — Species andinae herbaceae vel suffruticentes pubes-
centes. Folia opposita ovata petiolata. Habitus Agerati.

Clavis specierum,

a. Corollae fauces campanulati. h.

b. Achaenia glabra basi valcle obliqua sigmoidea 16. P. Sodiroi.

b, Achaenia in costis sursum hispidula basi parum obliqua.

17. P. calUtricha.
a. Corollae fauces cylindrici. c.

c. Capitula ca. 18-flora. Involucri squamae ovatae obtusiusculae.

18. P. latlfoUn.

c. Capitula ca. 100-flora. Involucri squamae lineari-lanccolatae, acuniinatis-

simae 10. P. coelestina.

ROBINSON. — STUDIES IN THE EUPATORIEAE. 1 5

16. P. SoDiROi Hieron., herbacea tenuis decumbens basi repens ; caule
flexuoso oppositirameo omnifariain hirsutulo, internodiis elongatis
quam folia multo longioribus ; foliis oppositis parvis 1-1.4 cm. longis
deltoideo-ovatis crenato-serratis ; capitulis paucis graciliter pedicellatis
subglobosis ca. 38-floris ; corollis externe glandulis rubris sparsissimis
munitis, tubo proprio brevissimo basi pilis multicellularibus valde
recurvatis vel reflexis hirsute, faucibus campanulatis ; achaeniis gla-
berrimis obovoideis basi valde obliquis. — Hieron. in Engl. Bot. Jahrb.
xxix. 3 (1900). — Ecuador : Sarsarango, Seemann n. 705 (hb. Kew., hb.
Gray) ; in umbrosis humidis juxta Quito, alt. 3000 m., floret Junio et
Julio, Jameson, n. 205 (hb. Kew.), n. 307 (hb. Kew., hb. Par.) n. 760
(hb. Brit. Mus.) ; fruticetis superioribus regionis silvestris in declivita-
tibus occidentalibus Andium circa Alihnir, prov. Cuenca, alt. 2800-
3300 m., floret in Oct., Lehmann, n. 5187 (hb. Berol.) ; inter virgulta
in regione interandina, Sodiro, n. B/1 (hb. Berol.) ; Chilliquin, Matheivs,
n. 1401 (hb. Kew., hb. Brit. Mus.). Peru : Prov. Chachapoyas (hb.
Kew.).

17. P. callitricha, n. sp., herbacea decumbens vel procumbens ra-
mosa ; caule elongato quadrangulari atropurpureo glabriusculo foliato ;
ramis ascendentibus ; foliis oppositis ovato-deltoideis 3(-5)-nerviis petio-
latis acutiusculis sedapice vero obtusis grosse crenato-dentatis 1-4 cm.
longis 0.7-3 cm. latis supra atroviridibus pilis albis basi incrassatis
scabriusculis subtus vix pallidioribus in nerviis venisque pubescen-
tibus margine pilis conspicue septatis eleganter ciliatis ; capitulis laxe
cymoso-paniculatis graciliter pedicellatis ca. 15-floris; involucri squamis
ca. 13 oblanceolatis acutiusculis carinatis in margine et carina ciliatis;
corollis externe glanduloso-puberulis, tubo proprio brevissimo, faucibus
campanulatis quam dentes limbi longioribus ; achaeniis 5-angulatis obo-
voideo-prismaticis disco annulari coronatis basi subrectis. — Colombia :
in summo monte Quendin, Maio 1846, Purdie (hb. Kew., hb. Gray) ;
inter Boquia et Volconcito, Holton (hb. Gray).

18. P. LATiFOLiA (DC.) Gardn., herbacea perennis ; caulibus decum-
bentibus subsimplicibus vel paucirameis foliatis omnifariam puberulis ;
foliis oppositis ovatis acutiusculis crenato-serratis trinerviis utrinque
viridibus subtus in nerviis pubescentibus ; inflorescentia cymoso-co-
rymbosa trichotoma paucicapitata ; capitulis ca. 18-floris ; involucri
campanulati squamis ca. 7 ovatis obtusiusculis 3-nerviis dorso glan-
duloso-puberulis ; corollis externe glanduliferis, faucibus cylindricis
tubo proprio multo longioribus, dentibus limbi brevibus patentibus ;
achaeniis obovoideis 5-angulatis basi attenuatis subrectis summo disco
annulari coronatis costis sursum hispidulis. — Gardn. in Hook. Lond.
Jour. Bot. vi. 430 (1847); Nicholson, Diet. Gard. iii. 148 (1886) pro

16 PROCEEDINGS OF THE AMERICAN ACADEMY.

parte. PJialacraea latlfoUa DC. Prod. v. 106 (1836) ; Deless. Ic. iv.
3, t. 8 (excl. syn. Ageratum latifolium Cav.) ; Regel, Garteutl. iii. 388.
— Peru : prope Lima, Nee (hb. DC), Haenke ; Cuzco, Gay (hb. Gray).

Var. glabra (DC), n. comb., caule glabro ; foliis paullo majoribus
ovatis cordatis ad 7 cm. longis ; pedicellis vix apice puberulis. —
Phalacraea latifoUa /3 glabra DC Prod. v. 106 (1836). — Peru ? Nee
(hb. DC).

19. P. coelestina (Regel) Hieron., snflFruticosa ramosissima 1 m.
alta pubescens ; foliis oppositis ovatis subcordatis crenato-dentatis ;
capitulis in cymis saepius 5-capitulatis longe pedunculatis dispositis
ca. 100-floris ; involucri squamis numerosis lineari-lanceolatis subtri-
seriatis acutissimis ; corollis externe in tubo proprio glanduloso-puber-
ulis, faucibus cylindricis quam dentes limbi longioribus. — Hieron. in
Engl. Bot. Jahrb. xxix. 3 (1900). PJialacraea coelestina Regel, Gar-
tenfl. iii. 388, t. 107 (1854). P. latifoUa Nicholson, Diet. Gard. iii.
148 (1886) pro parte. — Peru: casualiter in terra cum speciebus
orchidaceis et bromeliaceis a Warscewiczio lectis in horticulturam
europaeam introducta. Species inquirenda ut videtur ab herbariis
absens.

Species excludendae.

P. ageratoides (HBK.) Gardn. in Hook. Lond. Jour. Bot. vi. 430
(1847) est Alomia ageratoides HBK.

P. angustata Gardn. 1. c. 432 est Alomia angustata Benth.

P. attenuata Gardn. 1. c. 430 est Gymnocoronis sj)il'inthoides DC

P. cinerea Gardn. 1. c. 422 est Alomia cinerea Benth.

P. eupatorioides Gardn. 1. c. 431 est Trickogonia saloiaefolia Gardn.
var. /3 calca Baker.

P. Eupatorium Gardn. 1. c. 430 est Clihadium rotundifoUum DC

P.fastigiata Gardn. 1. c. 431 est Alomia fastigiata Benth.

P. foliosa Gardn. 1. c. 432 est Alomia foliosa Benth. et Hook. f.

P. latifoUa Gardn. 1. c. 430 est Ageratum conyzoides L.

P. longipetiolata Sch. Bip. ex. Bak. in Mart. Fl. Bras. vi. pt. 2, 183
(1876) est Gymnocoronis spilanthoides DC

P. myriadenia Sch. Bip. 1. c. 192 est Alomia myriadenia (Sch. Bip.)
Bak.

P. polypfiylla Sch. Bip. 1. c. 191 est Alomia polyphxjlla (Sch. Bip.)
Bak.

P. suhcordata Gardn. 1. c. 430 est Gymnocoronis spilanthoides DC

KOBINSON. — STUDIES IN THE EUPATORIEAE. 17

II. Revision of the Genus Ophryosporus.

Ophryosporus is a natural but not sharply delimitable group of
South American Eupatorleae Piqnerinae. It differs from Piqueria in
the presence of a well developed barbellate or shortly plumose pappus
of numerous capillary or rarely slightly thickened bristles. From
Eupatorium it differs in the entire absence of the apical appendage of
the anthers and usually may be distinguished furthermore by its sub-
simple involucre and rather conspicuously enlarged tips of the style
branches. The boundary between the two genera has been variously
drawn and must be regarded at best as a somewhat artificial line. To
the writer it appears that if the genus Ophryosporus is to be maintained
at all it must be restricted to those species in which the anthers are
really destitute of any terminal appendage or trace of such a structure
in any perceptible broadening or thickening of the connective at its
summit. Close examination shows such rudimentary appendages in
several species which recent authors have referred to Ophryosporus^
plants which furthermore exhibit at least in some instances the more
imbricated involucre and less enlarged style tips usual in Eupatorium.
If these species were kept in Ophryosporus there would appear to be
no single valid character and no combination of characters by which
the two genera could be clearly divided. For this reason it seems best
to refer these plants again to Eupatorium. Ophryosporus may be di-
vided into two sections (scarcely of subgeneric rank) on the nature of
the inflorescence and arrangement of the leaves. The t}^)ical section
is Chilian, while the other and larger section has a wider distribution,
occurring in Brazil, Argentina, Chili, Peru, Bolivia, and Ecuador.
Most of the species of Brazil and Argentina are, so far as yet known,
rather local. Those of the Andes, on the other hand, in some cases
have a considerable north and south range. The writer has been able
to examine the tyi^es or authentic specimens of all the species and
varieties of the genus as here treated.

OPHRYOSPORUS Meyen. (Nomen ab 6<f>pv^, supercilium, et o-Tropa',

seineu, derivatum, achaeniis in costis saepissime ciliatis.) — Capitula

homogama parva numerosa paniculata vel th}TSoidea 3-12-flora plus

minusve pedicellata ; involucri anguste campanulati vel cylindrici,

squamis subaequalibus 1-2-seriatim laxe vel vix imbricatis, disco nudo

parvo leviter convexo. Corollae albae tubulosae sursum gradatim ampli-

atae vel in fauces distinctos dilatatae externe praesertim in tubo proprio

et sub apicibus dentium glanduloso-puberulae vel atomiferae; limbi

dentibus 5 brevibus triangulares patentibus. Filamenta gracilia glabra.
VOL. xLn. — 2

18 PROCEEDINGS OF THE AMERICAN ACADEMY.

Antherae oblongae apice rotundatae vel truncatae vel retusae, connec-
tive angusto apice nuUo mode expanso nee appendiculato. Achaenia
5-angulata prismatica vel saepius leviter deorsum angustata 5-costata
saepius praesertim in costis hispidula vel glanduloso-ciliolata inter
costis saepe glanduloso-puberula vel atomifera. Pappi setae 15-35
albae vel roseae barbellatae vel breviter plumosae quam corolla vix
breviores. — Reise urn die Erde, i. 402 (1834) ; DC. Prod. vii. 260
(1838) ; Walp. in Meyen, Beitr. zur Botan. 256 (1843) ; Benth. et Hook,
f. Gen. ii. 239 (1873) ; Bak. in Mart. Fl. Bras. vi. pt. 2, 186 (1876)
excl. spec. n. 1 ; Griseb. Abhandl. Gesellsch. Wiss. Goett. xxiv. 173
(1879); Hoffm. in Engl, et Prantl, Nat. Pflanzenf. iv. Ab. 5, 133
(1890) ; Lofgren, Commissao Geograph. e Geolog. de Sao Paulo, Boletim,
xii. 139 (1897); Hieron. in Engl. Bot. Jahrb. xxii. 705 (1897); Reiche,
Fl. de Chil. iii. 258 (1902). Nothites DC. Prod. v. 186 (1836) solum
quoad spec. n. 5. Pachychaeta Sch. Bip. ex Bak. in Mart. Fl. Bras. vi.
pt. 2, 186 (1876). — Frutices ramosi, foliis oppositis vel alternis
saepius petiolatis rarius sessilibus triangulari-rhomboideis vel ovato-
lanceolatis vel rarius linearibus dentatis vel serratis vel crenatis vel
rarius integris.

Species 17 Americae australis incolae. Species aliae plurimae ab
auctoribus adhuc relatae videntur ob involucri squamis valdius imbri-
catis et ob antheris plus minusve distincte (quamquam brevissime)
apice appendiculatis melius ad Eupatorium referendae propterea quod
his speciebus in Ophryosporo inclusis distinctio inter generibus omnino
evanesceret.

Clavis sectionum.

Folia alterna parva, internodiis brevissimis. Panicula thyrsoidea.

Sect. I. EuopHRTOSPORrs.

Folia opposita majora, internodiis bene evolutis. Capitula in paniculis am-

plioribus vel in cymis axillaribus disposita. . . . Sect. II. Ophkyochaeta.

Sect. I. EuoPHRYOSPORUS, sect. nov. Capitula 5-12-flora in thyrso
angusto elongato folioso-bracteato disposita. Folia parva alterna
triangulari-rhomboidea vel lanceolato-linearia saepius fasciculata, in-
ternodiis brevissimis.

Clavis specierum.

Capitula ca. 5-flora. Folia lanceolatioblonga vel linearia subglabra.

1. 0. paradoxus.
Capitula 7-12-flora. Folia rhomboidea vel anguste deltoidea tomcntella.

2. 0. triaiigulai'ts.

1. 0. PARADOXUS (Hook, et Arn.) Benth. et Hook, f., fruticosus ra-
mosus glabriusculus ; ramis teretibus foliosissimis erectis ; foliis anguste
lanceolati-oblongis vel linearibus utroque acutis 1.5-2.5 cm. longis te-

EOBINSON. — STUDIES IN THE EUPATORIEAE. 19

nuibus subsessilibus subglabris viridibus margine hinc inde dentibus
argutis solitariis vel paucis instructis ; panicula thjTsoidea ad 3 dm.
longa, ramis ascendentibus foliosis subfastigiatis pluri- vel multi-capi-
tulatis ; capitulis numerosissimis 5-floris ; involucri squamis oblongis
apice rotundatis margine glanduloso-ciliolatis dorso sub-3-nerviis ob-
scure glanduloso-puberulis ; corollis 3.2 mm. longis, faucibus subcylin-
dricis glabris, tabo proprio glanduloso-puberulo aequantibus ; achaeniis
in costis et inter costis glanduloso-puberulis ; pappi setis ca. 20 sub-
plumosis. — Gen. PI. ii. 239 (1873) ex Hook. f. et Jacks. Ind. Kew. ii.
354 (1895). 0. triangularis Reiche, Fl. de Chil. iii. 259 (1902), not
Meyen. Eiqmtorium paradoxum Hook, et Am. in Hook. Comp. Bot.
Mag. i. 240 (1835). Nothites haccharidea DC. Prod. v. 187 (1836) ;
Gay, Fl. Chil. iii. 476 (1847). N. baccharoides Meigen in Engl. Bot.
Jahrb. xvii. 283 (1893). Stevia polyphylla DC. 1. c. 123. S. baccha-
roides Meigen, 1. c. — Chili : in planitiebus incultis et locis saxosis prope
marem vulgaris. Gay, n. 990 (hb. Gray) ; Valparaiso, Cuming, n. 337
(hb. Kew., hb. Brit. Mus., hb. Gray), Bridges, n. 52 (hb. Kew., hb.
Brit. Mus., hb. Gray), Gillies (hb. Gray), Bertero (hb. Gray), Philippi,
n. 406 (hb. Kew., hb. Brit. Mus.) ; Campana di Quillota, Edmonston
(hb. Kew., hb. Gray), Bertero, n. 837 (hb. Gray, hb. Brit. Mus.), Ger-
main (hb. Kew.).

2. 0. TRIANGULARIS Meyen, fruticosus ramosus ; ramis rectis vel
saepius leviter arcuatis rigidiusculis foliosissmis teretibus tomentellis ;
foliis parvis saepe fasciculatis rhomboideis ca. 1 cm. longis crenato-
dentatis vel lobulatis basi cuneatis utrinque tomentellis ; thyrsis sub-
cylindricis terminalibus 5-10 cm. longis 2-4 cm. crassis multicapitulatis ;
capitulis 7-12-floris ; involucri squamis 6-10 aequalibus oblongis dorso
enerviis tomentellis ; corollis externe glanduloso-puberulis ; faucibus
paullo ampliatis tubo proprio longioribus. — Reise um die Erde, i. 402
(1834) ; Gay, Fl. Chil. iii. 481 (1847) ; Benth. et Hook. f. Gen. ii. 239
(1873); Phil. Cat. PI. Vase. Chil. 174 (1881). Eupatorium decipiens
Hook, et Am. in Hook. Comp. Bot. Mag. i. 240 (1835). E. foliohsum
DC. Prod. V. 174 (1836). Kuhnia multiramea Turcz. Bull. Soc. Nat.
Mosc. xxiv. pt. 1, 168 (1851). E. Volckmanni Phil. Anal. Univ. Chil.
xviii. 51 (1861). Ophryosporus foliolosus Reiche, Fl. de Chil. iii. 259
(1902). — Chili : in planitiebus desiccatis, Coquimbo, Meyen, Gaudi-
chaud, Macrae (hb. Kew., hb. DC), Harvey (hb. Gray) ; Vallenar, Beed,
n. 47 (hb. Kew.) ; Concepcion, Bridges, n. 1412 (hb. Kew., hb. Brit.
Mus., hb. Gray) ; Copiapo, Gay (hb. Gray) ; Cobija, Gaudichaud (hb.
Gray); desertis Atacamae, Morong. n. 1149 (hb. Gray).

Nomen vulgatum : raho de zorra (fide Gayii).

20 PROCEEDINGS OF THE AMERICAN ACADEMY.

Sect. II. Ophryochaeta, sect. nov. Folia opposita, internodiis
bene evolutis. Capitula in paniculis amplis vel in cymis axillaribus
saepius laxe disposita.

Clavis specierum.

a. Squamae involucri saltim exteriores dorso puberulae vel pubescentes. b.

b. Achaenia glabra. Pubescentia involucri brevissima appressa. 3. 0. Cliarua.
b. Achaenia pubescentia vel glandulifera vel saltim in angulis hispiJula.
Pubescentia involucri squamarum laxior. c.
c. Inflorescentiae axillares quam folia multo breviores. 4. 0. axUUJlorus.
c. Inflorescentiae corymboso-paniculatae terminales. d.
d. Flosculi minimi. CoroUae ca. 2 mm. longae. c.
e. Folia ovata baud attenuata./!

f. Inflorescentia laxa, capitulis graciliter pedicellatis.

5. 0. laxiflorus.

f. Inflorescentia densa, capitulis subsessilibus. 6. 0. Rer/nellii,
e. Folia ovato-lanceolata vel lanceolata conspicue attenuata. g.

g. Stigmata nigrescentia. Acliaenia 1.8 mm. longa. Species

Brasiliae et Argentinae 1.0. Frei/rei/sii.

g. Stigmata brunnea. Achaenia 1.5 mm. longa. Species andinae

et Argentinae 8. 0. piquerioides.

d. Flosculi majores. CoroUae 3.3-5.5 mm. longae. h.

h. Capitula 6-11-flora. Folia 1.6-4 cm. longa. 9. 0. origanoides.
h. Capitula 4-5-flora. Folia ca. 7 cm. longa. 10. 0. venosissimus.
a. Squamae involucri praeter marginem saepe eroso-ciliatam glabrae. /.
i. Folia graciliter quamquam saepe breviter petiolata. j.

j. Capitula saepissime 8-10-flora ; involucri squamis ca. 5 mm. longis.

11. 0. macrodon.
j. Capitula 4-5-flora; involucri squamis 2-3.6 ram. longis. k.
k. Involucri squamae lanceolati-oblongae vel ellipticae. L
I. Achaenia gracillima 3 mm. longa. Species Argentinae.

12. 0. LorenUiu
I. Achaenia crassiora 2 mm. longa. Species bolivienses. m.

m. Cymae axillares compositae quam folia breviores.

13. 0. Cuming ii.
m. Cymae in corymbo convexo terminali aggregatae.

14. 0. Kuntzei.
k. Involucri squamae plus rainusve obovatae apice rotundatae. 7i.

n. Folia ovata subintegra. Species ecuadorensis. 15. 0. Sodiroi.
n. Folia lanceolata distincte serrata. Species argentinensis.

16. 0. clavulatus.
i. Folia sessilia 17. 0. Pachi/ckaeta.

3. 0. Charua (Griseb.) Hieron., fruticosus ramosus puberulus ; ramis
arcuato-ascendentibus ; foliis oppositis petiolatis ovato-lanceolatis
tenuibus acutis subgrosse serrato-dentatis margine uti-inque cum
dentibus 4-5 acutis instructis basi subcuneatis 2-3 cm. longis 1-1.5
cm. latis glabriusculis, petiolo ca. 8 mm. longo minutissime puberulo ;
cymis compositis ad axillas superiores glomeratis ca. 4-6 cm. diametro

ROBINSON. — STUDIES IN THE EUPATORIEAE. 21

rotundatis multicapitulatis ; pedicellis puberulis gracilibus 2-5 mm.
longis ; capitulis 4-fioris ; involucri squamis 4 appresse puberulis
anguste oblongis obtusis 3 mm. longis; corollis 3 mm. longis ex-
terne glanduloso-atomifero a tubo proprio brevi gracili in fauces
longiores gradatim ampliatis ; styli ramis brunneis longe exsertis
apice modice incrassatis ; achaeniis fuseo-nigris maturitate glaber-
rimis ; pappi setis ca. 30 barbellatis 2.5 mm. longis in specimine
exsiccato sordide albis. — Hieron. in Engl. Bot. Jahrb. xxii. 705
(1897). Mikania Charua, Griseb. Abhandl. Gesellsch. Wiss. Goett.
xxiv. 174 (1879). — Argentina: Prov. de Catamarca, Schickendantz,
n. 26 (hb. BeroL).

Noraen vulgatum : charrua.

4. 0. AXiLLiFLORUS (Griseb.) Hieron., suffruticosus ; caulibus flexu-
osis teretibus striatispilosiusculis; foliis oppositis membranaceis ovato-
lanceolatis 3-nerviis argute serratis basi cuneatis apice acuminatis
pilosiusculis ; cymis axillaribus quam folia multo brevioribus ; capi-
tulis 5-floris ; involucri squamis oblongis 3.5 mm. longis apice rotun-
datis dorso molliter pubescentibus margine ciliatis ; corollis (immaturis)
4 mm. longis externe in tubo proprio glanduloso-puberulis in fauces
leviter ampliatis, dentibus limbi 5 deltoideis ; acbaeniis 2 mm. longis
in costis 5 sursum hispidulis disco crassiusculo depresso-hemisphaerico
coronatis ; pappi setis ca. 20 sursum barbellatis. — Hieron. in Engl.
Bot. Jahrb. xxii. 70G (1897). Eupatorium axillijlorinn Griseb.
Abhandl. Gesellsch. Wiss. Goett. xix. 121 (1874). — Argentina :
Cordoba, prope Ascochinga, Lorentz.

5. 0. LAXiFLORus Bak., fruticosus ramosus erectus ad 1 m. altus ;
caule tereti glabrato a cortice brunneo tecto ; ramulis dense fulvescenti-
pubescentibus, pilis crispis ; foliis oppositis ovatis breviter petiolatis
grosse crenato-serratis a basi subintegra 3-nerviis obtusiusculis supra
viridibus scabriusculis subtus paullo pallidioribus modice pubescentibus
ca. 5 cm. longis ca. 2.7 cm. latis ; inflorescentia laxe paniculata ampla ;
bracteis ellipticis vel linearibus, ramulis pedicellisque filiformibus, his
ca. 4 mm. longis saepe arcuatis vel flexuosis ; capitulis ca. 5-floris, squa-
mis involucri 4-5 obovato-oblongis vel angustioribus 2.5 mm. longis
apice rotundatis eroso-ciliatis dorso pubescentibus ; corollis ca. 2.3 mm.
longis, tubo proprio gracile subglabro ; faucibus turbinato-campanulatis
externe gi-anulatis ; achaeniis obovoideis 5-costatis in costis sparse
hirsutis ; pappi setis ca. 16 achaenio distincte longioribus firmiusculis
barbellato-plumosis. — Brasilia : in campis, Prov. Minas Geraes prope
Caldas, Regnell, n. HI. 709 (herb. BeroL).

6. 0. E,EGNELLn (Sch. Bip.) Bak., fruticosus erectus ramosus tomen-

22 PROCEEDINGS OF THE AMERICAN ACADEMY.

toso-pubescens 1-1.3 m. altus; ramis oppositis ascendentibus rectis vel
leviter arcuatis foliatis, internodiis quam folia longioribus ; foliis oppositis
modice firmis ovatis obtusiusculis crenato-serratis 3-nerviis basi cuneatis
supra scabriusculis subtus pallidioribus praecipue in nerviis molliter
tomentosis 4-5 cm. longis 2-2.5 cm. latis, serraturis utrinque ca. 7 ;,
panicula ampla 3 dm. vel ultro longa folioso-bracteata, ramis cymiferis
oppositis divergentibus tomentosis, C5anis rotundatis ; capitulis bre-
vissime pedicellatis 5-floris ; involucri squamis 4-6 oblongis 2.5 mm.
longis erosociliatis nervoso-striatis dorso tomentosis apice rotundatis ;
corollis ca. 2.5 mm. longis, tubo proprio gracili puberulo, faucibus
gradatim ampliatis tubum longitudine vix aequantibus subgiabris, denti-
bus limbi 5 ovato-deltoideis patentibus ; achaeniis 5-angulatis prae-
cipue in costis valde birsutis ; pappi setis ca. 20 plumoso-barbatis. —
Bak. in Mart. Fl. Bras. vi. pt. 2, 188, t. 53 (1876). Eupatorium BegnelUi
Sch. Bip. Linnaea, xxii. 572 (1849), xxx. 182 (1859), nomen solum. —
Brasilia : in planitiebus Prov. Minas Geraes prope Caldas, Regnell, n. I.
237 (bb. Berol.) ; prope Villam Francam, Riedel, n. 1018 (hb. Gray).

7. 0. Freyreysii (Dallm.) Bak., fruticosus oppositirameus ; caulibus
teretibus juventate tomentosis maturitate glabriusculis ; ramis paten-
tibus foliatis ; foliis oppositis ovato-lanceolatis vel saepius lanceolatis
attenuatis basi breviter cuneatis 3-nerviis leviter sed distincte serratis
cum dentibus utrinque ca. 8 instructis supra scabriusculis vel glabrius-
culis subtus vix pallidioribus pubescentibus 5-8.5 cm. longis 1.5-3.5
cm. latis, petiolo supra sulcato tomentello 3-7 mm. longo ; capitulis
ca. 5 mm. longis saepissime 5-floris ; involucri squamis obovatis apice
rotundatis dorso tomentosis 3 mm. longis ; corollis 2.4 mm. longis
externe glanduloso-puberulis, faucibus gradatim ampliatis turbinato-
campanulatis tubum proprium gracilem fere aequantibus, dentibus limbi
5 brevibus patentibus ; styli ramis bene exsertis nigrescentibus apice
incrassatis rotundatis ; acbaeniis nigris 1.8 mm. longis sursum prae-
sertim in costis birsutulis. — Bak. in Mart. Fl. Bras. vi. pt. 2, 188
(1876), as Freyreissii. Eupatorium Freyreysii Dallm. in Thunb.
Decad. Nov. PI. Bras. n. 19, et Flora, 1821, i. 332; DC. Prod. v. 183
(1836). E. Freyresii DC. Prod. v. 169 (1836) in syn. E. Freyreissii
Bak. in Mart. Fl. Bras. vi. pt. 2, 188 (1876) in syn. E. Freyreysi
Hook. f. & Jacks. Ind. Kew. i. 917 (1893). E. RiedeUanum Gardn. in
Hook. Lond. Jour. Bot. v. 478 (1846). MiJcania clarellata DC. Prod.
V. 192 (1836). — Brasilia : Prov. Minas Geraes, Freyreiss (bb. Thunb.)
fide Bakeri ; in silvis Serro Frio, Gardner, n. 4851 (hb. Kew.); prope
Marianna, Vauthier, n. 287 (hb. Kew., hb. Gray), Gardner, n. 4852
(hb. Kew., hb. DC), sub hoc numero etiam Symphyopappiis polystachyus
(DC.) Bak. fide Bak. 1. c. 368; prope Bio Janeiro et Ouro Preto,

ROBINSON. — STUDIES IN THE EUPATORIEAE. 23

Glaziou, n. 15,158 (hb. Kew.); Riedel (hb. Kew.); Schuch, n. 138 (hb.
Vindob.).

8. 0. PiQUERioiDES (DC.) Benth., fruticosus erectus vel subscandens
oppositirameus foliis et floribus precedenti simillimus ; ramis juventate
fulvescenti-tomentellis maturitate glabratis striatulis ; foliis lanceolatis
3-Derviis serratis vel integerrimis breviter petiolatis 4-9 cm. longis,
1.2-3.3 cm. latis supra scabriusculis subtus in nerviis tomentosis vel
pubescentibus ; paniculis patente ramosissimis ; capitulis numerosissi-
mis 5-7-floris ; involucri squamis oblongis vel elliptici-obovatis apice
rotundatis erosis dorso laxe pubescentibus ; corollis lutescenti- vel
viridescenti-albis ; styli ramis apice brevissime et modice incrassatis
brunneis ; achaeniis nigris 5-angulatis ca. 1.5 mm. longis pubescentibus.
— Benth. ex Bak. in Mart. Fl. Bras. vi. pt. 2, 188 (1876). Eupatorhim
jnquerioides DC. Prod. v. 175 (1836). E. Tweedianum Griseb. Abhandl.
Gesellsch. Wiss. Goett. xxiv. 170 (1879), partim, non Hook, et Arn.
Mlkania Mandonil Sch. Bip. Linnaea, xxxiv. 536 (1865-6). M. Mandoni
Bak. 1. c. Ophryosporus saltensis Hieron. in Engl. Bot. Jahrb. xxii. 705
(1897). — Peruvia : in montibus Guanoccensibus, Haenke (hb. DC);
Panahuanca, Mathews, n. 1122 (hb. Kew.); inter Palcam et Huaca-
pistanam, Prov. Tarma, alt. 1700-2400 m., Weberhauer, n. 1776
(hb. Berol.). Bolivia : Yungas, d'Orb'igny, n. 421 (hb. Vindob.,
hb. Gray) ; prope Soratam, Prov. Larecaja, regione temperata, alt.
2550 m., ad rivum in nemoribus, Mandou, n. 268 (hb. Kow., hb. Brit.
Mus., hb. Gray); JIandon, n. 255 (hb. Kew., hb. Brit. Mus.); Calapampa,
Bang, n. 2342 (hb. Gray), distrib. sub nomine "Willoughbya sp. n."
Chili : Santa Cruz, Aug. 1865, Pearce, (hb. Kew., hb. Brit. Mus.).
Argentina : Salta prope Yacone, Lorentz et Hieronymus, n. 536
(hb. Berol.).

NoTA. — 0. saltensis Hieron. 1. c. est forma ut videtur vix distincta foliis
firmiusculis saepe conduplicatis verosimiliter e loco aridiori.

9. 0. ORiGANOiDES (Meyen et Walp.) Hieron., suffruticosus oppositi-
rameus ; caulibus teretibus striatulis ; foliis oppositis ovatis vel elliptico-
lanceolatis acutis vel acuminatis baud longe attenuatis 1.5-3 cm. longis
8-10 mm. latis 3-nerviis petiolo 4-6 mm. longo gracili et nerviis
tomentellis margine utrinque cum dentibus saepissime 4-7 instructis ;
involucri squamis uniseriatis 8-10 lanceolati-oblongis acutiusculis
saltim juventate dorso pubescentibus; capitulis in corymbo composite
dispositis 9-11-floris; corollis 5.5 mm. longis; achaeniis nigrescentibus
3.5 mm. longis. — Hieron. in Engl. Bot. Jahrb. xxii. 707 (1897), excl. pi.
Rusbyi et syn. Eupatorium eleutherantheruin. E. origanoides Meyen
€t Walp. Nov. Act. Acad. Caes. -Leopold, xix. Suppl. I. 257 (1843);

24 PROCEEDINGS OF THE AMERICAN ACADEMY.

Walp. Rep. vi. 113 (1846); non HBK. — Peruvia : in planitie circa
Tacoram, alt. 4300-5200 m., 3Ieijen (hb. Berol.).

NoTA. — Eupatorium eleutheranthernm Rusby, Mem. Torr. Bot. Club, iii. pt. 3,
5.3 (1893), hue a cl. Hieronyrao relatum exhibet antheras plus minusve ap-
pendiculatas saltiin connectivo apice expanse, etiam folia longiora magis apice
attenuata cum dentibus numerosioribus (7-11) utrinque instructa. Quapropter
planta Rusbyi videtur verosimiliter distincta et melius ad Eupatorium referenda.

Var. (?) MiCROCEPHALUS Hieron., habitu formae typicae simili.s ;
foliis magis attenuatis; capitulis minoribus 6-7-floris, squamis iiivolucri
obovalibus apice rotundatis ciliatis dorso laxe pubescentibus ; corollis
4 mm. longis ; achaeniis (immaturis) 2-2.5 mm. longis. — Hieron. in
Engl. Bot. Jahrb. xxii. 708 (1897). — Bolivia: prope Cochabambam,
ca. 4000 m. alt., Kuntze (hb. Berol.).

10. 0. VENOSissiMUS (Busby) Robinson, fruticosus oppositirameus ;
ramis subangulatis ascendentibus foliatis ; foliis oppositis lanceolatis
ca. 7 cm. longis ca. 2 cm. latis serratis 3-nerviis attenuatis basi cuneatis
utrinque viridibus sparse pubescentibus ; corymbis rotundatis folioso-
bracteatis ; capitulis numerosis brevissime pedicellatis vel subsessilibus ;
involucri pallide viridis subcylindrici squamis anguste oblongis acu-
tiusculis dorso rotundatis sparse laxeque pilosis ca. 3 mm. longis ;
flosculis 4-5 ; corollis albis vel ochroleucis 3-4 mm. longis, tube proprio
glanduloso-puberulo quam fauces glabri cylindrici breviori ; achaeniis
valde immaturis pubescentibus ; pappi setis ca. 28 barbellatis tenuibus
albis. — Proc. Am. Acad. xli. 271 (1905). Eupatorium venosissimum,
Rusby, Mem. Torr. Bot. Club, vi. 57 (1896). — Bolivia : prope Cocha-
bambam, Bang, n. 1113 (hb. Gray).

11. 0. macrodon Griseb., frutescens in parte superiori oppositi-
rameus; ramis subteretibus dense fulvo-puberulis ; foliis oppositis ovatis
magnis grosse et duplice dentato-serratis acutis basi subrotundatis vel
cuneatis membranaceis 3-5-nerviis ad 14 cm. longis ad 7 cm. latis supra
scabris subtus pallidioribus pubescentibus, petiolo ca. 1.3 cm. longo;
inflorescentiis terminalibus corymbosis convexis subcongestis ; capitulis
saepissime 8-10-floris pro genere maximis ; flosculis (styli ramis elon-
gatis exclusis) ca. 7 mm. longis ; corollis ca. 5 mm. longis, tubo proprio
puberulo quam fauces cylindrici glabri multo breviori. — Abhaudl.
Gesellsch. Wiss. Goett. xxiv. 173 (1879). — Argentina: Nevado del
Castillo, Prov. de Salta, Lorentz et Hieronymus, n. 156 (hb. Berol.).

12. 0. LoRENTZii Hieron., fruticosus oppositirameus 1.5-2 m. altus ;
ramis teretibus flexuosis ascendenti-patentibus striatulis ; foliis oppo-
sitis ovato-lanceolatis attenuati-acuminatis argute serratis ca. 5-10
cm. longis 2-4 cm. latis membranaceis 3-nerviis petiolatis juventate
utrinque sparse pubescentibus deinde glabratis ; corymbis numerosis

ROBINSON.

STUDIES IN THE EUPATORIEAE. 25

lateralibus in axillis superioribus et terminalibus rotundatis quam folia
brevioribus ; capitulis 4-flori3 ; involucri squamis 4 aequalibus liueari-
bus acutiusculis 4 mm. longis ; corolb's 3.3 mm. longis fere a basi grada-
tim ampliatis in parte inferiori glanduloso-puberulis, dentibus limbi
brevissimis erectis deltoideis ; achaeniis in parte inferiori glabris in
parte superiori sparse hispidulis ; pappi setis ca. 23 albidis subplu-
mosis 3 mm. longis. — Hieron. in Engl. Bot. Jabrb. xxii. 706 (1897).
Eupatorlum laeve Griseb. Abhandl. Gesellscb. Wiss. Goett. xxiv.
172 (1879), partim f. Hieron. 1. c. — Argentina : Cueste inter Yacone
et Los Potreros, Lorentz et Hieronymus, nn. 333, 340 (hb. Berol.).

13. 0. CuMiNGii (Scb. Bip.) Benth., fruticosus glabriusculus ; ramis
flexuosis ^ongatis subteretibus laevibus striatulis meduUosis, internodiis
5-12 cm. longis, ramulis gracillimis puberulis ; foliis oppositis tenui-
bus lanceolatis longissime attenuatis acutissimis 3-nerviis argute serra-
tis 3-10 cm. longis 7-20 mm. latis sparse in nerviis venulisque
puberulis vel supra glaberrimis, petiolo 4-12 mm. longo gracili ; C)^mis
axillaribus quam folia subtendentia multo brevioribus in parti superiori
caulium et ramorum aggregatis et paniculam foliosam formantibus,
pedicellis filiformibus 1-3 mm. longis ; capitulis 4-floris ca. 6 mm.
altis ; involucri squamis oblongis tenuibus stramiueo-viridibus ciliolatis
3-4 mm. longis apice rotundatis dorso 2-3-nerviis ; corollis albis 3.3
mm. longis, tubo proprio gracili externe glanduloso-puberulo fauces
cylindrico-campanulatos sparsissime glanduliferos subaequanti, denti-
bus limbi 5 ovato- deltoideis plus minusve patentibus ; acbaeniis
5-angulatis 1.6 mm. longis prismaticis modice deorsum angustatis
in costis sursum hispidis inter costis glaberrimis summa parte cupulo
brevissimo coronatis ; pappi setis capillaribus barbellatis. — Bentb. ex
Bak. in Mart. Fl. Bras. vi. pt. 2, 188 (1876) ; Hieron. in Engl. Bot. Jabrb.
xxii. 7(»") (1897). Mikania Cumingii Sch. Bip. Bull. Soc. Bot. Fr. xii.
82 (1865) et Linnaea, xxxiv. 535 (1865-6), nomen nudum. — Bolivia :
in nemoribus regionis temperatae 2700-2900 m. alt., inter Ladrilloni
et Condurpata, Prov. Larecaja, Mandon, n. 264 (hb. Kew., hb. Gray) ;
Bridges, 1847 (hb. Brit. Mus.) ; Cuming, n. 102 (f Sch. Bip.).

14. 0. Kuntzei Hieron., fruticosus oppositirameus ; ramis gracilibus
patenti-ascendentibus juventate puberulis deinde glabratis usque ad
inflorescentias terminales corymbosas foliatis ; foliis oppositis lanceo-
latis vel ovato-lanceolatis acuminato-attenuatis serratis 3-7 cm. longis
1-2 cm. latis 3-5-nerviis utrinque sparse pubescentibus ; corymbis
multicapitulatis valde convexis, pedicellis ca. 1 mm. longis ; capitulis
4-floris ; squamis involucri 4 subaequalibus 2.6-3.3 mm. longis fere a
basi gradatim expansis in parte inferiori glanduloso-puberulis ; achae-
niis nigris 5-angulatis cum vel absque angulis secondariis obscuris

26 PROCEEDINGS OF THE AMERICAN ACADEMY.

2 mm. longis deorsum valde angustatis apice ab annulo albido coro-
natis ; setis pappi ca. 25 sordido-albis. — Hieron. in Engl. Bot. Jabrb.
xxii. 707 (1897). — Bolivia : Tunari australi, ca. 3000 m. alt., Apr. -
Maio, 1892, Kuntze (bb. Berol).

15. 0. SoDiROi Hieron., fruticosus verosimiliter scandens ; ramis oppo-
sitis elongatis flexuosis puberulis, internodiis folia longitudine valde
superantibus ; foliis ovatis acutis petiolatis integris vel pauciserratis
3-4 cm. longis 1.7-2 cm. latis 3-nerviis tenuibus pellucide reticulato-
venosis ; capitulis sublaxe paniculatis 5-7-floris ; pedicellis patentibus
2-3 mm. longis ; involucri squamis 5-7 obovatis vel late spatulatis
brunneis ciliatis apice rotundatis erosis dorso glabris ca. 2.8 mm.
longis; corollis gradatim et modice apicem versus ampliatis ubique
glanduloso-puberulis vel atomiferis ; acbaeniis (valde immaturis) bre-
vissimis in angulis scabratis ; pappi setis ca. 28 albidis inaequalibus
barbellatis. — Hieron. in Engl. Bot. Jabrb. xxix. 3 (1900). — Ecuador:
in silvis subtropicis prope La Cbima, Hod'iro, n. 6/18 (bb. Berol.) ; Cam-
pamento Utauag in valle flu minis Cbambo, alt. 3045 m., Strubel, n. 275
(bb. Berol.).

16. 0. CLAVULATUS Griscb., fruticosus 2 m. altus superne puberulus
laxe ramosus ; ramis teretibus foliatis oppositis ; foliis anguste ovato-
lanceolatis longe acuminato-attenuatis 3-nerviis tenuibus serratis supra
obscure puberulis subtus in nerviis pubescentibus 4-6 cm. longis
1.. 3-2.5 cm. latis ; petiolis 6-11 mm. longis flexuosis planiusculis ; pani-
culis ovalibus multicapitulatis, capitulis 4-5-floris ; involucri squamis
obovati-oblongis 2 mm. longis ciliolatis dorso glabris brunneis ; corollis
2 mm. longis, tubo proprio gracili puberulo sursum in fauces subaequi-
longos gradatim expanso ; acbaeniis nigris 1.6 mm. longis 5-angulatis
in angulis sursum bispidulis ; pappi setis ca. 20 albidis subplumoso-
barbatis. — Abbandl. Gesellscb. Wiss. Goett. xxiv. 173 (1879) ; Hieron.
in Engl. Bot. Jabrb. xxii. 705 (1897). Ewpatorium clavulatum Griseb.
1.0. xix. 120 (1874). — Argentina: Cuesta de Periquilla, Lorentz, n.
409 ; Lorentz et Hieromjmus, n. 178 (bb. Berol.).

17. 0. Pachychaeta Bak, sufifruticosus erectus ramosus puberulus;
ramulis angulatis viridibus foliatis flexuosis ; foliis oppositis sessilibus
lanceolatis firmiusculis 3-nerviis utrinque viridibus punctatis subgla-
bris 2-3 cm. longis 4-7 mm. latis utrinque 1-3-angulato-dentatis
acutis ; corymbis terminalibus pyramidatis alternirameis 4-5 cm. dia-
metro, bracteis subulatis brevissimis, ramis puberulis apicem versus
3-7-capituliferis ; capitulis saepissime 4-floris ; involucri squamis 3-5
oblongis vel anguste obovatis vel ellipticis acutiusculis 2.5 mm. longis;
corollis glabriusculis 2.5 mm. longis, tubo proprio gracillimo fauces
campanulatos subaequanti ; acbaeniis 1.2 mm. longis basin versus

EOBINSON. — STUDIES IN THE EUPATORIEAE. 27

attenuatis 5-angulatis fere glabris ; pappi setis aequalibus crassiusculis
haud barbatis salmoneis vel roseis attenuatis subpatentibus. — Bale, in
Mart. Fl. Bras. vi. pt. 2, 187 (1876). Pachychaeta eupatorioides Sch.
Bip. mss. fide Bak. 1. c. — Brasilia : in planitiebus Pro v. Minas Geraes,
Lund ; Claussen (hb. Kew.) ; Riedel, n. 421 ; Rio Janeiro, Glaziou, n.
14,018 (hb. Kew., hb. Berol.), n. 14,019 (hb. Kew.).

Species reducendae vel exdudendae.

0. Burchellii Bak. in Mart. Fl. Bras. vi. pt. 2, 187 (1876) est forma
Eupatorii tetranthii Sch. Bip. quod videtur solum forma oppositifolia
JE. dentati Gardn.

0. Chilca (HBK.) Hieron. in Engl. Bot. Jahrb. xxii. 706 (1897) ob
antheris distincte appendiculatis certe ex Ophryosporo excludendus est
E. Chilca HBK.

0 Mandonii (Sch. Bip.) Benth. et Hook, f ex Hook. f. et Jacks. Ind.
Kew. ii. 354 (1895) est 0. piquerioides (DC.) Benth.

0. ovatifoUus (DC.) Benth. et Hook, f ex Hemsl. Biol. Cent. -Am.
Bot. ii. 79 (1881), ob antheris obscure appendiculatis et ob affinitate
indubia cum aliis speciebus Eupatorii melius nunc ad hoc genus re-
ferendus, est vere ab E. polybotryo DC. Prod. v. 174 (1836) nullo modo
distinctus.

0. soUdaginoides (HBK.) Hieron. in Engl. Bot. Jahrb. xxix. 4 (1900)
est eisdem rationibus E. soUdaginoides HBK.

0. solldagiiioides, var. Bonplandianus (Sch. Bip.) Hieron. 1. c. =
Eupatorlmn soUdaginoides, var. Bonplandianum (Sch. Bip.), n. comb.

HI. The Genus Helogyne and its Synonyms.

Since its publication by Nuttall in 1841 the genus Helogyne has
remained an obscure monotype known only from a single fragmentary
specimen, collected in Peru and now preserved in the herbarium of the
British Museum. The genus has been referred to the Piquerinae by
all recent authors who have had occasion to classify it, but Bentham
and Hooker, who first expressed this view as to its affinities, particu-
larly state that they did not examine the anthers, which alone furnish
the crucial character of the subtribe.

While at the herbarium of the British Museum, the author was
kindly permitted to remove one of the very few flowers from a head
and make a dissection. The anthers were found to be each supplied
with a well-developed terminal appendage, showing clearly that the
genus belongs not to the Piquerinae but to the Ageratinae. When
transferred to the latter tribe, Helogyne is found to occupy the same

28 PROCEEDINGS OF THE AMERICAN ACADEMY.

place as the later monotypic genus BracJujandra Phil., and there can
be no doubt that these two plants are congeneric. They are both
small-leaved glandular-pubescent xerophytic shrubs, with closely sim-
ilar achenes and pappus, and both possess the peculiar narrowly tubu-
lar corollas with exceedingly short teeth and no expanded throat. The
only difference between them which could possibly be regarded as of
generic importance is that the involucre in Helogijne is about 2-seriate
and of subequal bracts, while in Brachyandra it is about 3-seriate, the
outer bracts being decidedly shorter. In view of the close correspond-
ence in floral structure, achenes, leaf- arrangement, etc., this difference
in the involucre, which finds frequent parallels within the limits of
several other genera of the Compositae, seems by no means sufficient
to warrant keeping these two genera separate. The later name
proposed by Philippi must of course give way to the earlier one of
Nuttall.

Leto Phil, is a third obscure Chilian xerophytic monotype of this
affinity. Its generic relationship to Brachyandra was shrewdly sur-
mised by Dr. 0. Hoffmann (see Engl. & Prantl. Nat. Pflanzen. iv.
Ab. 5, 334), notwithstanding a misleading statement in the original
description to the effect that the corollas were irregular, which is not
the case. More recently Reiche, Fl. de Chil. iii. 263 (1902), has for-
mally transferred the single species to Brachyandra. While at Berlin,
the writer had an opportunity to examine an authentic specimen of
this plant {Leto tenuif alius Phil., Brachyandra teniu/oUa Reiche), and
failed to find even specific distinctions between it and the type of Htdo-
gyne ajxdoidea preserved at the British Museum. It is true that the
specimen of Leto at Berlin shows some leaves much more deeply lobed
than any on the specimen of Helogyne at the British Museum, but the
latter consists only of a tip of a flowering branch on which the leaves,
3-toothed at the apex, correspond well with the uppermost leaves in the
Berlin plant.

Still a fourth South American xerophytic monotype clearly belongs
to the same group, namely, Addisonia Rusby, Bull. Torr. Bot. Club,
XX. 432, t. 159 (1893). Like the three preceding, it is an erect viscid
much-branched shrub with small narrow alternate glandular leaves,
few-flowered heads, narrow subcylindric involucre, and disk fi-ee from
pales. In common with them it has 5 -angled achenes, slightly nar-
rowed toward the base, and crowned with numerous purple-tinged bar-
bellate setae. What is still more significant, it shares with them the
peculiar very narrowly tubular corollas destitute of any distinct throat
and provided with the same very short suberect teeth, of the same yel-
lowish white color and exhibiting the same tendency to external gran-

EOBIXSON, — STUDIES IN THE EUPATORIEAE. 29

ular puberulence. Like Brachyandra, Addisonia has an invclucre
with o-4-seriate scales which are strongly imbricated and very unequal
in length, but unlike any of the three other monotypes here discussed,
Addisonia has its involucral scales arranged in four upright rows.
This difference, if any, must be regarded as its claim to rank as a
separate genus. It is a conspicuous characteristic, and at first sight
might seem to be of considerable diagnostic importance. However, a
second species, closely related to Addisonia virgata Rusby, has been
collected in Peru by Weberbauer, and in it the scales are in five not
always equidistant erect series, showing that the number of the series
is not of generic significance. Furthermore, the tendency of closely im-
bricated, somewhat carinate involucral scales to assume more or less
regularity in upright series is observable elsewhere in the Compositae
in a way to cast much doubt upon the importance of the character as
a sole basis for a generic separation. Thus, in the species of Bigelovia,
of the B. graveolens group, an equally marked tendency of this sort is
observable, but shows such inconstancy even in very nearly related
forms, that it can scarcely be taken as a character of specific, not to
mention generic, significance. In view, then, of the close correspond-
ence of the four South American plants here discussed — a likeness
which embraces, as we have seen, not merely habit, leaf-arrangement,
etc., but all the more significant characters of flower and fruit — it
seems best to unite them under the oldest name, both in order to show
their obvio'js relationship and to avoid the adoption of a standard of
generic classification solely on the basis of involucral diff'erences, which
would cause great difficulty and artificiality if applied to neighbor-
ing genera of the Compositae.

Attention may be called to the fact that all four of these plants
maintain the chief distinction by which the genus Brachyandra has
long been separated from the allied genus Trichogonia, namely, the
very narrowly tubular corolla. The creation in botanical literature
of these four successive genera for plants, which now appear to be of one
generic type, is readily explained and to a great extent excused by the
rarity of the plants concerned and by the natural misapprehensions
which have arisen fi-om mistakes in the original descriptions. Thus,
the original Helogyne, founded on a small tip of a flowering branch, was
thought by Nuttall to be probably an annual, and his description was
likely to mislead the reader into supposing that the outer involucre
was more foliaceous and the style-branches more expanded than is
really the case. To this may be added the circumstance that Bentham
long ago referred the genus to the Piquerinae, with which it has no
close affinity. The original description of Leto states that the corolla

30 PROCEEDINGS OF THE AMERICAN ACADEMY.

is irregular, a trait which, if it really were true, would place the genus
in the Mutisieae. Finally Addisonia is described and figured as having
corollas with campanulate throats. Under these circumstances, it is
by no means remarkable that the real affinity of these plants has
not been noticed until authentic specimens of each of them could be
studied in relation to the others. The combined genus may be treated
as follows :

HELOGYNE Nutt. (Nomen ab 17X0?, ciavls, et yvvq, muUer, ob forma
styli ramorum incrassatorum.) — Capitula parvula homogama 6-12-
flora terminalia vel subcorymbosa vel spicato-racemosa ; involucro
subcylindrico vel anguste campanulato, squamis 2-4-seriatis imbrica-
tis, receptaculo parvo nudo planiusculo. CoroUae anguste tubulosae
vel etiam angustissime fusiformes nullo modo in fauces ullos distinc-
tos ampliatae externe glanduloso-puberulis vel pulverulis, limbi brevis-
sime 5-dentati dentibus suberectis vel leviter patentibus. Antherae
lineares inclusae apice obtuse appendiculatae basi integrae. Styli rami
valde exserti plus minusve patentes valde sed gradatim incrassati flavi
vel saepius nigrescentes. Achaenia 5-costata prismatica deorsum levi-
ter angustata. Pappi setae subaequales tenues achaeniis subaequilon-
gae vel superantes barbellatae vel subplumosae. — • Trans. Am. Phil.
Soc. n. s. vii. 449 (1841) ; Walp. Rep. vi. 107 (1846) ; Benth. et Hook,
f Gen. ii. 239 (1873) ; Hoffm. in Engl, et Prantl. Nat. Pflanzenf iv.
Ab. 5, 133 (1890). Bmchyandra Phil. Fl. Atac. 34, t. 4, f D (1860) ;
Benth. et Hook, f, 1. c. 244 (1873); Hoffm. 1. c. 138 (1890); Reiche,
Fl. de Chil. iii. 263 (1902). Leto Phil. Ann. Mus. Nac. Chil. sec. 2
(botanica), 33, t. 1, f. 3 (1891); Hoffm. 1. c. 334 (1893). Addisonia
Rusby, Bull. Torr. Bot. Club, xx. 432, t. 169 (1893). — Frutices ramo-
sissimi foliosi glanduloso-puberuli. Folia alterna parva Integra vel
dentata vel lobato-subpinnatifida sessilia.

Species 4 regionis desiccatae Peruviae et Boliviae australis et rei
publicae Chilensis borealis incolae.

Sect. I. EuHELOGYNE, scct. nov., involucri squamis subaequalibus ca.
2-seriatim imbricatis. — Helogyne Nutt. 1. c. Leto Phil. 1. c. — Species
unica.

1. H. APALOiDEA Nutt., ramis arcuato-ascendentibus foliosis, inter-
nodiis brevibus ; foliis parvis 8-15 mm. longis cuneato-oblanceolatis
integerrimis vel saepius irregulariter pinnatim 2-3-lobatis vel supremis
solum apice 2-3-dentatis glanduloso-puberulis amaris ; capitulis 8-12-
floris paucis erectis corymbosis, pedicellis gracilibus erectis vel arcuato-
ascendentibus ; involucri squamis subaequalibus anguste ellipticis vel

KOBINSON. — STUDIES IN THE EUPATORIEAE. 31

lanceolatis ca. 6-8 apice obtusiusculis vel rotundatis ca. 6 mm. longis
pubescentibus ; corollis verosimiliter flavescenti- vel viridiscenti-albis
4.5 mm. longis externe minute granulosis ; achaeniis 2.7 mm. longis ;
pappi setis ca. 20 barbellatis 2 mm. longis. — Trans. Am. Phil. Soc. n. s.
vii. 449 (1841). Leto tenuifoUus Phil, Ann. Mus. Nac. Chil. sec. 2
(botanica), 34, t. 1, f. 3 (1891). Brachjandm tenuifoUa Reiche, Fl. de
Chil. iii. 263 (1902). —Peru : Arequipa, Curson (hb. Brit. Mus.). —
Chili : inter Sibayam et Chiapam in provincia Tarapaca, F. FhiUppi
(specimen in hb. Berol. a cl. Reicheo missum).

Sect. II. Brachyandra (Phil.), sect, nov., involucri squamis valde
inaequalibus spiraliter 3-4-seriatim imbricatis. — Brachyamh-a Phil.
Fl. Atac. 34, t. 4, f. D (1860). — Species unica desertorum Atacamae
in cola.

2. H. macrogyne (Phil.), n. comb., fruticosa ramosissima viscoso-
tomentella 1 m. alta parte inferiori delapsu foliorum denudata cortice
griseo tecta; ramis ascendentibus foliosissimis furcatis prope apicem
capituliferis ; capitulis 6-7 mm. altis saepe 4-floris breviter pedicellatis;
involucri squamis subscariosis tenuibus pubescentibus appressis ex-
terioribus brevissimis ovatis acutis, intermediis gradatim longioribus
oblongo-ovatis acutis, intimis lineari-lanceolatis ; corollis albis vel ex
sicco purpurascentibus 5 mm. longis ubique externe resinoso-granulosis;
antheris linearibus 1.8-2 mm. longis ; achaeniis nigricantibus sursum
atomiferis 3 mm. longis ; pappi setis ca. 25 sordide albidis vel etiam
purpurascentibus breviter plumoso-barbatis 4.5 mm. longis subinaequa-
libus. — Brachyandra macrogyne Phil. Fl. Atac. 34, t. 4, f. D (1860);
Reiche, Fl. de Chil. iii. 263 (1902). — Chili : Pro v. Atacama versus
Tilopozo, alt. 2300 m., PMUppi ; in desertis Atacamae, Fhilippi,
n. 504 (hb. Berol.), Aug. 1864, Fearce (hb. Kew.).

Sect. III. Addisonia (Rusby), sect, nov., involucri squamis valde
inaequalibus in seriebus 4-5 erectis imbricatis. — Addisonia Rusby,
1. c. — Species 2 quarum una Boliviae australis altera Peruviae
australis.

3. H. virgata (Rusby), n. comb., fruticosa ramosissima glanduloso-
subviscosa ad 1 m, alta basi delapsu foliorum denudata, ramis sub-
fastigiatis foliosissimis saepius supra mediam pai'tem capituliferis;
foliis ascendentibus vel appressis ad 11 mm. longis ad 1.3 mm. latis
glaberrimis integris glanduloso-punctatis firmiusculis linearibus sessili-
bus subcarinatis 1-nerviis obtusis margine revolutis ; capitulis spicato-
racemosis breviter pedicellatis 4-5-fioris ; squamis involucri erecte
4-seriatim imbricatis subherbaceis acutissimis vel obtusiusculis et

32 PROCEEDINGS OF THE AMERICAN ACADEMY.

argute mucronatis ; corollis ocroleucis 5.5 mm. longis externe basi et
prope apicem granuliferis ; antheris 2 mm. longis linearibus ; achaeniis
obtuse 5-angulatis deorsum leviter angustatis ubic^ue sed praesertim
in angulis granulosis ; pappi setis purpureis ca. 25 paullulo rigidius-
culis barbellatis ca. 5 mm. longis. — Addisonia virgata Rusby, Bull.
Torr. Bot. Club, xx. 432, t. 169 (1893). — Bolivia : Songo, Nov.
1890, Bang, n. 868 (hb. Gray, hb. Acad. Philad.) sub nomine Chu-
quiragua distributa.

4. H. Weberbaueri, n. sp., fruticosa ad 1 m. alta ramosissima in
parte inferiori delapsu foliorum denudata cortice griseo tecta, ramis
subfastigiatis flexuosis erectis foliosissimis supra mediam partem capi-
tuliferis ; foliis linearibus crassiusculis 1 cm. longis 2 mm. latis prope
marginem hispidulis glanduloso-punctatis ; capitulis spicato-racemosis
breviter pedicellatis ca. 5-floris ; involucri squamis in seriebus 5
erectis imbricatis valde inaequalibus fere omnino brunnescenti-stra-
mineis nee herbaceis carinatis apice attenuatis ; corollis exacte tubu-
losis ocroleucis apice brevissime 5-dentatis externe solum versus basin
granuliferis ca. 7 mm. longis; antheris linearibus 2.5 mm. longis;
achaeniis prismatico-obpyramidatis ubique praesertim in angulis granu-
liferis 3 mm. longis ; pappi setis subinaequalibus purpurascentibus rigi-
diusculis barbellatis ca. 7.5 mm. longis. — Peru : in arenosis subdesertis,
Yura, alt. 2400 m., 31 Aug. 1902, Weberbauer, n. 1416 (hb. Berol.).
Species praecedenti valde affinis difFert foliis latioribus margine his-
pidulis, capitulis majoribus, involucre baud herbaceo, corollis longiori-
bus basi tantum granuliferis.

IV. Diagnoses and Synonymy of Eijpatorieae and of certain

OTHER CoMPOSITAE •WHICH HAVE BEEN CLASSED WITH THEM.

Apodocephala Balv. Jour. Linn. Soc. xxi. 417 (1885); S. Ell. ibid,
xxix. 28 (1891); Hoffm. in Engl. & Prantl Nat. Pflanzenf iv. Ab. 5,
134, 135 (1890), 388 (1894). Through the courtesy of Sir William
Thiselton Dyer and Dr. Stapf of the Royal Gardens at Kew the
writer was permitted to make dissections of the flowers of both species
of this problematic genus of Madagascar, which has been referred to
the Eupatorkae by Mr. Baker and to the Vernon ieae by Dr. Hoffmann.
The anthers are clearly sagittate, the leaves alternate, the style-
branches rather strongly recurved and acutish, and the involucre of a
form and texture far more frequent in the Vernonieae than in the
Eupatorkae. Indeed, all features observed seem to confirm fully the
view of Dr. Hoffmann that the genus should be referred to the former
tribe.

KOBINSON. — STUDIES IN THE EUPATORIEAE. 33

Alomia dubia, n. sp., herbacea erecta perennis sordide pubescens
4-7 dm. alta; radice lignescenti ramosa; caulibus 1 vel pluribus
teretibus striatulis foliosissimis ad inflorescentiam corymbosam simpli-
cissimis ; foliis alternis oblanceolatis obtusiusculis crenato-serratis 2-3
cm. longis 4-10 mm. latis basi attenuates subpetiolatis utrinque dense
et sordide pubescentibus supra rugulosis subtus reticulatis ; corymbis
laxe ramosis 7-15 cm. latis supra modice planis, ramis ascendentibus
saepius 3-5-capituliferis, bracteis linearibus 5-15 mm. longis; capitulis
ca. 6o-floris ca. 1 cm. diametro 8-10 mm. altis ; involucri campanulati
squamis subbiserialibus lanceolato- linearibus subaequalibus dorso pu-
berulis nervosis apice attenuatis tomentellis ; corollis roseis 4 mm.
longis, tubo proprio gracili externe glanduloso-hirsutulo basi plus
minusve expanso supra in fauces turbinato-campanulatos gradatim
ampliato, limbo purpurascenti-tomentello ; achaeniis nigris 5-angulatis
glaberrimis basi mediocriter angustatis apice rotundatis ab annulo
albido cartilagineo coronatis omnino calvis. — Brazil, presumably from
the Prov. Goyaz, Dr. A. Glaziou, n. 2 1579 (hb. Kew.).

Although there can be no doubt that this species is technically an
Alomia and must be referred to that genus, as the genera of this affinity
are now divided, it must be confessed that Alomia looks suspiciously
like an artificial aggregate of species which may well have had a very
different origin. Its species are varied in habit, and approach on the
one hand so close to Ageratum, and on the other to Trichogonia, that
it may well be doubted whether they are not, at least in some cases,
"formae epapposae " of these genera. The present species closely
resembles in habit and many of its features Trichogonia. It should
be noted that forms of at least two species of Trichogonia have been
found in which part or all the achenes were entirely destitute of
pappus. The species here described, however, is clearly distinct from
any hitherto characterized species of either genus. Trichogonia with
its plumose setiform pappus is certainly very distinct from Ageratum
with a pappus of few distinct or somewhat connate scales, yet the
Alomiae, which are entirely destitute of pappus or have only an
annular rudiment in its place, show such transitions of habit, involucre,
pubescence, etc., that they neither carry conviction as a distinct genus,
nor are they capable of satisfactory grouping as pappusless forms of
the pappus-bearing genera. The genus Alomia is as yet very poorly
represented in herbaria, and until further material has been collected,
it seems impracticable to revise the generic limits of the three genera
here concerned.

Hartwrightia floridana Gray, Proc. Am. Acad, xxiii. 265 (1888).
In characterizing this monotypic genus from Florida, Dr. Gray un-

VOL. XLII. 3

34 PEOCEEDINGS OF THE AMERICAN ACADEMY.

fortunately described the anthers as exappendiculate. This has led to
some misapprehension as to its affinities, and it has been placed in the
Piquerinae by Hoffmann in Engl. & Prantl, Nat. Pflanzenf. Nachtr.
zu iv. Ab. 5, 321 (1897), who seems to have overlooked Professor J. M.
Holzinger's notes on the subject. Bull. Torr. Bot. Club, xx. 287, t. 160
(1893), Careful dissection shows that the anthers are each provided
with an ovate deeply retuse membanaceous apical appendage. This
trait throws the genus into the Ageratinae, where it should probably
be placed nearest Alomia, a conclusion long ago reached by Professor
Holzinger.

Ageratum scorpioideum Bak. in Mart. Fl, Bras. vi. pt. 2, 197(1876).
Mr. Baker's description of this species was drawn from Schomburgk's
no. 353 in the herbarium of the Royal Gardens at Kew. He states
that the plant is an erect doubtfully perennial herb. While at the
Royal Botanical Museum of Berlin, the writer had an opportunity to
examine an authentic specimen of Caelestina repens Sch. Bip., mentioned
in Schomb. Fauna et Flora Guy. 1134 (1848), which proves identical
with Baker's species. Schultz's name, although earlier, cannot be taken
up, as it is accompanied by no description. It was founded on Schom-
burgk's no. 1188, collected on a moist savanna near the Canuku
Mountains, British Guiana. The specimen is more complete than the
one at Kew, and shows that the plant has a horizontal, evidently
perennial, and slightly lignescent rhizome, which roots at the nodes
and sends up erect subsimple stems.

Stevia simulans, n. sp., herbacea perennis fere a basi pauciramea
erecta ; caule et ramis simplicibus teretibus purpureis foliosissimis
3-3.5 dm. altis in summa parte glanduloso-puberulis ; foliis linearibus
crassiusculis firmiusculis 3-5-nerviis glabris 2.8-3.5 cm. longis 2-5 mm.
latis utrinque glanduloso-punctatis obtusiusculis ascendentibus ; capi-
tulis paucis corymbosis saepius longe rigidiuscule pedicellatis ca.
1.3 cm. altis 13-floris; involucri squamis lanceolati-oblongis 9 mm.
longis atropurpureis glanduloso-puberulis vix nervosis ; corollis laete
purpureis 7-9 mm. longis, tubo proprio externe glanduloso-puberulo
modice et gradatim in fauces longiusculos ampliato, dentibus limbi
anguste oblongis acutis patentibus vel recurvatis ; styli ramis planis ;
achaeniis 5 mm. longis 10-costatis subteretibus puberulis ; pappo
duplici e squamis 5 brevibus hyalinis apice rotundatis et aristis 5 atro-
purpureis 5 mm. longis erectis scabriusculis composito. — On the mesa
de la Sandia, Durango, Mexico, alt. 3050 m., 14 Oct., 1905, C. G.
Pringle, n. 10,144 (type, in hb. Gray). This species possesses a very
close habital similarity to S. Pringlei Wats., but may be readily
distinguished by its copious glandular indumentum and especially

ROBINSON. — STUDIES IN THE EUPATORIEAE. 35

by the presence of the aristate pappus, which is quite lacking in
K Pringlei

Fleischmannia arguta, n. comb. Eupatorium argutum HBK.
Nov. Gen. et Spec. iv. 121 (1820). E. quinquesetum Benth. ex Oerst.
Vidensk. Meddel. 1852, p. 79. Fleischmannia rhodostyla Sch. Bip.
Flora, xxxii. 417 (1850). The type of Eupatorium argutum HBK. is
still extant at the Museum of Natural History in Paris, It is clearly
just the plant which has long passed as Fleischmannia rhodostijla and
its much earlier specific name must accordingly be taken up.

Trichocoronis sessilifolia, n. comb. Argeratum sessili/olium
Schauer, Linnaea, xix. 715 (1847) ; Hemsl. Biol. Cent. -Am. Bot. ii. 83
(1881). Trichocoronis Greggii Gray, PI. Wright, i. 89 (1852). The
type of Schauer's Ageratum sessili/olium is Aschenborn's no. 4, of
which there is a well preserved specimen in the Royal Botanical
Museum in Berlin. The habitat is given as Mexico, but without more
particular locality, and the species has remained obscure. On exami-
nation it proves to be identical with the species later described as
Trichocoronis Greggii by Dr. Gray. Gregg's plant (no. 807 of his last
Mexican collection) is said to have come from the region between
Mazatlan and the City of Mexico. Fortunately Mr. Pringle has redis-
covered the species, and the fuller data of his label give definite infor-
mation of at least one station, namelj', marshes of Atequiza in the
state of Jalisco. Priority necessitates the transference of the original
specific name.

EuPATORiopsis HoFFMANNiANA Hicron. in Engl. Bot. Jahrb. xviii.
Beibl. 43, p. 4G (1893). This Brazilian monotype was placed by its
author in the subtribe Piqnerinae. Dissection, however, shows that
the anthers have distinct apical appendages quite as well developed as
in many of the Ageratinae. There can be no doubt that the true
affinity of the genus is with Trichocoronis Gray, PI. Fendl. 65 (1849),
with which it agrees closely in general habit, in its opposite sessile
leaves, its long pedicelled heads, campanulate involucre with subequal
subherbaceous bracts, its short purplish corollas with capanulate throat,
and in its abortive setiform pappus. In fact, almost its only claim to
generic separation is in its broad obovate quasi two-winged achenes,
those of Trichocoronis being narrow and prismatically 4-5-angled.

Dissothrix imbricata, n. comb. Stevia imbricata Gardn. in Hook.
Lond. Jour. Bot. v. 458 (1846). Dissothrix Gardneri Gray in Hook.
Jour. Bot. & Kew Misc. iii. 223 (1851); Bak. in Mart. Fl. Bras. vi. pt.
2, 272 (1876). Dr. Gray's specific name, coined at a time of greater
nomenclatorial laxity, must, according to priority, give place to the
original name given by Gardner.

36 PROCEEDINGS OF THE AMERICAN ACADEMY.

Trichogonia rhadinocarpa, n. sp., suffrutescens ramosa; ramis
subsimplicibus teretibus striatis viridibus puberulis foliosis ; foliis
alternis lanceolati-oblongis crenato-serratis ad apicem obtusiusculum
angustatis basi rotundatis vel breviter abrupteque euneatis petiolatis
utrinque pubescentibus et glanduloso-atomiferis viridibus subtus vix
pallidioribus merabranaceis 3-5.5 cm. longis 1.3-2.5 cm. latis, petiolo
8-15 mm. longo subtomentoso ; inflorescentia terminali corymbosa ca.
16-capitulata, bracteis filiformibus 3 mm. longis, pedicellis filiformibus
plus minusve flexuosis ca. 7 mm. longis ; capitulis ca. 18-floris 8-10 mm.
altis ; involucri turbinato-campanulati squamis linearibus vel anguste
oblanceolatis attenuatis ca. 7 mm. longis subuniseriatis dorso leviter
nervatis puberulis apice tomentosis purpurascentibus ; corollis angustis,
tubo proprio gracili glaberrimo, faucibus brevissimis, limbo purpureo-
tomentoso; achaeniis 4 mm. longis nigris 5-angulatis basi longe
attenuato-stipitatis angulis obsolete scabratis ; pappi setis phimosis
sordide albis 4 mm. longis basi brevissime connatis. — T. podocarim
Bak. in Mart. Fl. Bras. vi. pt. 2, 216 (1876) pro parte, non Sch. Bip. —
Near Tovar, Venezuela, Fendler, n. 651 (hb. Gray) ; Mariara, Venezuela,
800 m. alt., Aug. 1899, Preuss, n. 1508 (hb. BeroL); Ocana, Prov.
Ocaha, Colombia, SchUm, n. 178 (hb. Kew,). The Fendler specimen was
taken to Geneva and carefully compared with the type of T. podocarpa
Sch. Bip. {Kuknia podocarpa DC.) and it was found to be clearly a
distinct species, differing in various ways but most strikingly in its
densely tomentose corollas. In the type of T. j)odocarpa the corollas
are covered on the outside by large scattered waxy atoms but are other-
wise glabrous. From T. campestris Gardn., T. rhadinocarpa differs in
its much broader leaves, longer and more tapering achenes, etc.

EuPATORiUM ALTissiMUM L. Syst. cd. 12, 537 (1767). By the Index
Kewensis, i. 915, this is referred to B. ageratoides L. f., but this is
clearly a mistake. In the 12th edition of the Systema, p. 537, the
description of JE. altissimum is identical with the description of the
same species in the first edition of the Species Plantarum, and it can
be construed only as relating to the lanceolate-leaved plant which still
very properly bears the name B. althshnum.

Eupatorium auriculatum Vahl, Symb. Bot. iii. 95, t. 72 (1794);
DC. Prod. V. 174 (1836) ; Bak. in Mart. Fl. Bras. vi. pt. 2, 340 (1876) ;
not Lam. This species, said by Vahl to come from Brazil, was fully
described and clearly figured by him. It has, however, not been
rediscovered since its description a century ago and has remained
entirely obscure. Suspecting from Vahl's figure that the plant was
not really a Bupatorium but a Senecio, the writer, with the aid of
Dr. Greenman, who has a special knowledge of the latter genus, made

ROBINSON. — STUDIES IN THE EUPATORIEAE. 37

some efforts to identify the species among the Brazilian Seneciomae.
This search proved wholly unsuccessful, and accordingly a wish to
examine the type of this problematic plant added no small incentive
to a recent visit to Copenhagen, where many of Vahl's plants are
preserved. The specimen of the plant in question was easily found
and corresponded in all respects to Vahl's description and plate. It
proved as anticipated a tSenecio, but what was even more interesting, a
faint but still quite legible label on the back of the sheet disclosed the
fact that the specimen had not come from Brazil, but had been col-
lected by Commerson on the Isle of Bourbon in the Indian Ocean.
With this important clue, it has been easy to identify it positively
with Senecio penicillatus (Cass.) Sch. Bip. The synonymy of the
species is as follows : —

Eupatorium tomentosum Lam. Diet, ii. 410 (1786).

" auriculatum Vahl, Symb. iii. 95, t. 72 (1794).

Mikania tomentosa Willd. Spec. PL iii. 1744 (1804).

Cacalia penicillata Cass. Diet, xlviii. 460 (1827).

Senecio penicillatus Sch. Bip. Flora, xxviii. 499 (1845).

Senecio tomentosus Cordemoy, Fl. de llle de la Rdunion, 543 (1895),
not Michx.

Although the specific names tomentosus and auriculatus are both
earlier than penicillatus they have already been employed for other
valid species of Senecio and are accordingly not available for this
plant, which should continue to pass as S. penicillatus (Cass.)
Sch. Bip.

Vahl seems to have been quite aware of the identity between his
Eupatorium auriculatum and the earlier E. tomentosum of Lam., as he
has indicated this upon his label. Although Lamarck's species was
also founded on material collected by Commerson on the Isle of
Bourbon, he appends to his description the note "on la trouve aussi
dans le Brdsil," having probably confused with the plant of the Indian
Ocean some habitally similar species of South America. It was doubt-
less this circumstance which led Vahl to ascribe his E. auriculatum to
Brazil, notwithstanding the fact that his type-sheet bears a note ap-
parently in his own hand to the effect that the plant came from the
Isle of Bourbon,

Eupatorium confeHifolium Klatt, Abh. Naturf Ges. Halle, xv. 324
(1881). This species does not differ essentially from E. vaccinii-
FOLiuM Benth. PL Hartw. 200 (1845).

Eupatorium coperense Hieron. in Engl. Bot. Jahrb. xxi. 330 (1895).
This species, examined and photographed at the Royal Botanical
Museum at Berlin, appears identical with the earlier E. angustifolium

38 PROCEEDINGS OF THE AMERICAN ACADEMY.

(HBK.) Spreng. Syst. iii. 415 (1826), the type of which was exammed
and photographed at the Museum of Natural History in Paris.

Eupatorium cremastum, n. sp., fruticosum 3-4 m. altum ; ramis
teretibus glabris fusco-brunneis laevibus ; foHis magnis oppositis tenu-
ibus 16 cm. longis 4.5-6.5 cm. latis utrinque viridibus sublucidis ovato-
oblongis acuminatis serratis penninerviis supra glabris subtus in
nerviis lanulosis basi breviter acuminatis; petiolo 3-3.5 cm. longo;
internodiis ca. 3 cm. longis ; inflorescentiis laxis lateralibus pendulis
5-8 cm. longis pauci- vel multi-capitulatis; pedicellis 2-2.5 cm. longis
capillaribus flexuosis obscurissime puberulis ; capitulis 1.3 cm. latis
ca. 10-floris ; involucro perlaxo, squamis linearibus attenuatis ca. 10
pilosulis viridibus subaequalibus ca. 5 mm. longis 3.5 mm. latis
gracillimis nigris curvatis deorsum angustatis etiam apicem versus
paullulo decrescentibus ; corollis 4.5 mm. longis glabris albis, tubo
proprio gracili quam fauces anguste cylindrici breviori ; pappi setis ca.
18 laete albis corollam subaequantibus. — Crest of the Sierra Madre in
Michoacan or Guerrero, Mexico, alt. 2200 m., 17 Feb. 1899, Langlasse,
n. 893 (hb. Gray, hb. Berol.).

Eupatorium Cursonii, n. sp., ramis atropurpureis teretibus fusco-
tomentellis, internodiis brevibus 8 mm. longis ; foliis oppositis lineari-
oblongis attenuatis supra bullato-reticulatis sparse puberulis subtus
reticulato-venosis tomentosis 9 cm. longis 8 mm. latis crassiusculis
margine leviter crenulatis valde revolutis, petiolo ca. 1 mm. longo ;
capitulis 2-3 in summis ramorum axillaribus permagnis ca. 80-floris,
involucri squamis subaequalibus lanceolatis, exterioribus subcoriaceis
2 cm. longis 4 mm. latis striatulis dorso granulari-puberulis apice sub-
filiformi-attenuatis, interioribus angustioribus et tenuioribus ; recep-
taculo paleifero saltern ad marginem, paleis 2 cm. longis ad apicem fere
capillaceum attenuatis; corollis anguste tubulosis glaberrimis 1 cm.
longis, dentibus 5 brevissimis patentibus atropurpureis ; antheris line-
aribus apice valde appendiculatis basi integerrimis ; styli ramis clavatis
planiusculis 6 mm. longis atropurpureis ; achaeniis linearibus 7 mm.
longis 5-angulatis in costis minute scabratis ; pappi setis ca. 50 fere
1 cm. longis, plurimis exteriorum brevioribus. — Collected at Arequipa,
Peru, by Mr. Curson. The sole specimen of this clearly marked species
is in the herbarium of the British Museum of Natural History. It had
evidently been in the herbarium of Nuttall, who had recognized its
novelty and assigned it a specific name under the genus Campuh-
clinium. Unfortunately Nuttall's manuscript name has already been
used in Eupatorium and therefore cannot be now taken up. In habit
and probably in its affinities E. Cur.<onlt approaches E. BalUi Oliv.,
from which, however, it differs decidedly in its subequal involucral
bracts.

ROBINSON. — STUDIES IN THE EUPATORIEAE. 39

Eupatorium gracilicaule Scb. Bip. in herb., fruticosnm 3 m.
altum oppositirameuin ; ramis teretibus glaberrimis gracilibus, inter-
nodiis ca. 5 cm. longis ; foliis ovatis longe acuminatis basi rotundatis
vel brevissime acuminatis 3-nerviis leviter serrato-dentatis plus minusve
falcatis utrinque glabris subtus baud vel vix pallidioribus minute
glanduloso-punctatis ad 8 cm. longis 3-4 cm. latis, venulis subtranslucen-
tibus, petiolo gracili patenti 2-2.5 cm. longo; paniculis magnis 2-3 dm.
diametro rotundato-corymbosis oppositirameis folioso-bracteatis multi-
capitulatis obscurissime puberulis vel granulosis, ramis laxe patentibus,
pedicellis gracillimis saepe flexuosis minute bracteolatis ; capitulis
6-8 mm. altis ca. 13-floris ; involucri squamis laxissime imbricatis
linearibus acutissimis dorso sordide puberulis, intimis ca. 3 mm. longis
subaequalibus 6-9, exterioribus paucis (2-3) brevioribus angustissimis ;
achaeniis 5-angulatis gracilibus glabris fuscis deorsum levissime angus-
tatis ; corollis glabris 3 mm. longis verosimiliter albidis, tubo proprio
gracili in fauces modice ampliatos gradatim expanso, dentibus limbi
5 brevibus patentibus ; pappi setis ca. 20 tenuibus albidis aequalibus
simplicissimis corollam fere aequantibus. — Tlacolula, Mexico, Dec.
1839, Ehrenherg, n. 11,711 (hb. Berol., bb. Gray). This species in habit
somewhat suggests E. stilUngiaefoUum DC. and E. Mendezii DC, but
differs from each of them in being nearly glabrous and in its much less
imbricated involucre, etc.

Eupatorium hemipteropodum, n. sp., herbaceum robustum ad
3 m. altum ; caule meduloso subtereti valde striato-costato glabrato in
sicco stramineo-brunnescenti ; foliis oppositis magnis tenuibus ovatis
utrinque glabris et viridibus supra levissimis longe petiolatis, inferio-
ribus ovatis subacuminatis 1.8-2.5 dm. longis 12-15 cm. latis argute
grosseque dentatis basi acuminatis et breviter in petiolo decurrentibns,
petiolo 4-6 cm. longo, foliis supremis deltoideo-ovatis 8-10 cm. longis
5-7 cm. latis subduplice crenato-serratis basi acuminatis, petiolo fere a
media parte apicem versus alato ; panicula ovoidea thyi'soidea opposi-
tiramea ca. 7 cm. diametro aequialta multicapitulata ; capitulis ca.
10-floris ; involucri squamis stramineis in apice obtuso vel rotundato
brunneis pluriseriatim imbricatis, interioribus lineari-oblongis, exterio-
ribus gradatim brevioribus ovatis ciliolatis ; corollis anguste tubulosis
glabris dentibus limbi brevissimis ; pappi setis sordide albis corollam
subaequantibus ; achaeniis valde immaturis in et etiam inter costis
pubentibus. — E. quadmngidare Millsp. Field Columb. Mus. Bot. i.
324 (1896), not DC. E. jwpuUfoUum Millsp. 1. c, not HBK. E. aroma-
tisans Millsp. 1. c. iii. 92, with figs. (1904), not DC. — Yucatan : Izamal
(where, ace. to Millspaugh, 1. c, in general cultivation), Gaumer, -n. 552
(hb. Field Mus., bb. Gray) ; Merida, Valdez, n. 92 (hb. Field Mus., hb.

40 PROCEEDINGS OF THE AMERICAN ACADEMY.

Gray). This perplexing plant has several times been referred to the
present writer, who may well be responsible for some of the several
names under which it has passed. Renewed study of it shows that it
possesses distinctions which appear to separate it from any described
species. From E. quadrangulare it differs in its essentially terete
stem ; from E. liopulifoliiim (a species which should henceforth bear
the name^. morifoUum Mill.), it may be readily distinguished by its
essentially membranaceous leaves of different dentation, and by its
pubescent achenes, as well as by its half- winged petioles. Its nearest
affinity is doubtless, as pointed out by Dr. Millspaugh, with the West
Indian E. aromatlsans DC, yet it cannot be satisfactorily placed in
that species, as the leaves are much thinner, the upper ones crenate-
dentate, not serrate, and the petioles only partially winged instead of
being winged clear to the base, as is the case in E. aromatisans.

Eupatorium Holwayanum, n. sp., herbaceum gracile erectum vel
decumbens subgiabrum 3-5 dm. altum ; caulibus teretibus plus minusve
purpurascentibus striatulis obscurissime puberulis foliosis gracilibus
hand 2 mm. diametro ; foliis ternis vel oppositis vel praecipue in parte
superiore caulis alternis ovatis vel rhomboideis acutiusculis pauciserratis
1.5-2 cm. longis 7-10 mm. latis 3-nerviis utrinque glabris viridibus
basi cuneatis brevissime petiolatis; panicula laxe ramosa basi plus
minusve folioso-bracteata, ramis gracilibus purpureis ascendenti-
divergentibus saepius 1-5-capituliferis ; capitulis 9 mm. diametro ca.
60-floris ; involucri squamis valde inaequalibus lineari-lanceolatis
pluriseriatim imbricatis attenuatis acutissimis striatis viridibus vel
purpurascentibus ; corollis albis 3.3 mm. longis tubulosis, tubo proprio
brevissimo, faucibus anguste tubulosis multo longioribus glabris, denti-
bus limbi 5 externe puberulis ; achaeniis 5-angulatis fuscescentibus 1.7
mm. longis in angulis scabratis ; pappi setis ca. 20 albis tenuissimis
scabratis. — Dry banks. Sierra de San Fehpe, alt. 2150 m., 17 Nov.
1894, C. G. Prmgle, n. 5683 (hb. Gray), 14 Nov. 1903, E. D. W. Hol-
ivay, n. 5418 (hb. Gray). This plant was at first referred to E. triner-
vium Sch. Bip., to which it has considerable similarity. It may be
readily distinguished, however, by its much smaller leaves of an ovate
or rhombic form, and by the lack of pubescence regularly found in
E. trinervium.

Eupatorium leptophyllumDC. Prod. v. 176(1836). This species has
long been misunderstood and neglected. It was originally described
from material collected about Savannah, Georgia, by Herbemont, and
was regarded by Torrey and Gray (Fl. ii. 83) as merely a smoothish
variety (their var. glahrum, 1. c.) of E. foenimlaceum Willd. Dr. Chap-
man and Dr. Small in their floras of the Southern States do not

ROBINSOX. — STUDIES IN THE EUPATORIEAE. 41

mention the plant either as a species or variety. The material now
available shows that E. leptophyllum was well grounded and is read-
ily distinguishable from the related species. Among these, it most
nearly approaches E. capilUfoUum (Lam.) Small {E. foeniculaceum
Willd.), and has similar very fine filiform-linear entire, pinnate, or dis-
sected leaves, but it difters in the long simple recurved-spreading
secund -racemose branches of its inflorescence, the heads of E. capilU-
foUum being borne in compound somewhat fastigiate leafy panicles.
In E. capilUfoUuni, furthermore, the involucral scales are green and
oblong, rather abruptly pointed and but slightly scarious at the mar-
gins, while in E. leptophjUum they are inclined to be brown (in dried
specimens) and have strongly contrasting white margins. In form they
are linear-oblong or lance-linear and tend to be attenuate, often ending
in a very sharp point. The simple recurved racemose branches of the
inflorescence are 4-10 cm. long, and as DeCandolle remarks in the
original description, the inflorescence suggests strongly that of some of
the golden-rods. The following specimens of E. leptophyUum have
been examined : — Georgia : near Savannah, Herhemont (hb. DC).
South Carolina : damp pine land, San tee Canal, September, Ravenel
(hb. Gray). Florida : without locality, Leavenworth ; Braidentown,
Tract/, n. 7099 (hb. Gray), distributed as E. capUUfoUum. The species
shows some variation in its leaves. They are described as entire by
DeCandolle, and this is true in the upper parts of the specimens at
hand, but the lowermost leaves when shown are pinnately divided into
filiform or narrowly linear segments. In a second specimen collected
on the Santee Canal by Ravenel (October), the leaves are not only more
dissected than in the others, but the segments, although still very nar-
row, are distinctly flat rather than filiform. The close correspondence
of all these specimens, however, in the more essential characters of in-
florescence, involucres, flowers, achenes, and pappus, confirm the belief
that they are only individual or formal leaf- variations of E. leptophjl-
lum DC.

Eupatorium loxeme Klatt, Ann. k. k. Naturh. Hofmus. Wien, ix. 357
(1894). This species, founded on a plant collected by Jameson at Loxa,
Ecuador, has been examined both as to its tj^e preserved in the her-
barium of the Imperial Natural History Museum at Vienna and the
specimen in the herbarium of the late Dr. Klatt. It is clearly the
staminate plant of a Baccharis, and so far as may be judged from
the characters of B. berberifolia HBK. Nov. Gen. et Spec. iv. 57
(1820), may well belong to that species.

Eupatorium menthaefoUum Poepp. ex Spreng. Syst. iii. 412 (1826).
Although this Cuban species is kept up as a Eupatorium by Hooker

42 PROCEEDINGS OF THE AMERICAN ACADEMY.

and Jackson in the Index Kewensis i. 118 (1893), it was long ago
transferred to Vernonia by Lessing, Linnaea, iv. 268, a disposition
fully confirmed by a recent examination of the type preserved in the
herbarium of the Imperial Natural History Museum at Vienna. Un-
less some earlier specific name is found, the plant should certainly
stand as Vernonia. menthaefolia Less,

EuPATORiuM MORiFOLiUM Mill. Gard. Diet. ed. 8, no. 10 (1768).
The type-specimen of this hitherto obscure species was recently exam-
ined at the herbarium of the British Museum of Natural History. It
was collected at Vera Cruz, Mexico, by Dr. Houston, and proves to be
identical with the plant long familiar under the later name of E. popii-
lifollum HBK. Nov. Gen. et Spec. iv. Ill (1820). E. morifoUum Mill,
seems to have been overlooked by Mr. Hemsley, as it is omitted from
the Biologia Centrali-Americana, but it is as well characterized as most
species of its date and must be reinstated for the well-known plant to
which the name was clearly applied.

Eupatorium myosotifoUiim Jacq. Ic. PI. Rar. iii. 15, t. 582 (1786-
1793), & Coll. ii. 341 (1788). This species was described from culti-
vated specimens which had been raised from seeds supposed to come
from tropical America. The plant is well figured by Jacquin, and it is
clear, even from his illustration, that it does not belong to the genus
Eupatorium nor even to the Eupatorieae, for the style-branches are
short and decidedly recurved. An examination of an authentic speci-
men preserved in the herbarium of the Imperial Natural History
Museum at Vienna fully confirmed the correctness of the plate and
showed that the plant belongs to the baccharoid Astereae, probably
to the genus Conyza.

Eupatoriura nubigenoides, n. sp., inflorescentia excepta glaber-
rimum ; ramis lignescentibus teretibus medulosis ; foliis oppositis longe
petiolatis tenuissimis ovati-oblongis vel late lanceolatis penninerviis
serratis utrinque glaberrimis viridibus utroque acuminatis ca. 13 cm.
longis ca. 5 cm. latis, dentibus parvis incurvis tenuiter cuspidatis,
petiolo obcompresso nudo ca. 5 cm. longo ; panicula oppositiramea
ramosissima supra rotundata polycephala puberula vel tenuiter tomen-
tella folioso-bracteata ; capitulis pedicillatis ca. 10-floris 6 mm. altis ;
involucri campanulato-subcylindrici squamis albescentibus adpressis
valde imbricatis ca. 4-seriatis multi-striatulis, exterioribus brevissimis
ovatis acutiusculis ciliolatis intermediis ovato-oblongis apice rotundatis
glabris gradatim longioribus, intimis similibus sed anguste oblongis
obtusis ; corollis albis anguste tubulosis 3 mm. longis glabris sine
faucibus ullis distinctis, dentibus limbi deltoideis brevissimis patenti-
bus ; achaeniis 5-angulatis 1 mm. longis fuscis glabris ad basin leviter

KOBINSON. — STUDIES IN THE EUPATORIEAE. 43

attenuatis ; pappi subsparsi setis tenuissimis albis. — Pansamala, Depart.
Alta Verapaz, Guatemala, June, 1886, alt. 1150 m., //. von Tuerckheim,
n. 928 (distrib. by J. D. Smith). This specimen was first sent out as
E. aromatisans DC. Its identification was then changed at the mis-
taken suggestion of the writer to E. nubigenum Benth. Compared at
the Royal Gardens of Kew with Hartweg's n. 587, the type of Ben-
tham's E. nubigenum, this plant proved to be distinct. E. nubigenum
has larger flowers, longer achenes, closely sessile heads, and strongly
angled branches.

Eupatorium nutans HBK. Nov. Gen. et Spec. iv. 105 (1820). This
name has been regarded as a somewhat doubtful synonym of Brick-
ellia secunda Gray. The type, however, when examined at the her-
barium of the Museum of Natural History in Paris, proved to be B.
PENDULA Gray, PI. Wright, i. 85 (1852). Bulbostylis 2)endula DC.
Prod. v. 138 (1836). Eupatorium pendulum Schrad. Cat. Sem. Hort.
Goett. 1830, ace. to DC. 1. c. Although the specific name nutans is
earlier than pendulum, it is no longer applicable in Brickdlia owing to
the existence of the valid homonym B. nutans Robinson & Greenman,
Am. Jour. Sci. 1. 152 (1895).

Eupatorium ovaliflorum Hook. »& Am. Bot. Beech. 297 (1840).
This species was long known to the writer from the original description
only, and from the characters there given could not be positively dis-
tinguished from the plant, also of western Mexico, later described as
E. Bertholdii Sch. Bip. in Seem. Bot. Herald. 299 (1856). As others
may encounter difficulty in separating these nearly related and hab-
itally similar species, it may be well to record the differences, which
were found on a comparison of authentic specimens in the herbarium
of the Royal Gardens at Kew. In E. ovalijiorum the leaves are per-
manently tomentulose above as well as below and they are decidedly
pale beneath ; the involucres are ovoid and 3.8 mm. in thickness. In
E. Bertholdii, on the other hand, the leaves are somewhat scabrous
with scattered hairs above and green beneath ; while the involucres
are more narrowly ovoid, 2.3 mm. in thickness.

Eupatorium Palmeri Gray, Proc. Am. Acad. xxi. 383 (1886). From
the typical form of this species, which has its leaves grayish-tomentu-
lose beneath and its involucral scales finely pubescent, the following
smoothish caudate-attenuate leaved plant would appear quite distinct
were it not for the existence in western Mexico of some intermediate
forms, which appear to show that the differences, although conspicuous,
are by no means constant.

Var. tonsum, n. var., foliis ovato-lanceolatis longissime attenuatis
utrinque glabris remote serrulatis vel integris ad 14 cm. longis ad

44 PROCEEDINGS OF THE AMERICAN ACADEMY.

4.2 cm. latis ; capitulis pyramidato-paniculatis ca. 5-floris ; involucri
squamis viridibus striatis acutissimis vix pubescentibus ; antheris
apice brevissime appendiculatis. — El Ocote, Michoacan or Guerrero,
alt. 300 m., 10 November, 1898, Langhisse, n. 616 (hb. Gray, hb. BeroL).
Said to be a shrub 1.5 m. high with grayish flowers.

Eupatorium pelotrophum, n. sp., fruticosum 1.5 m. altum ; ramis
gracilibus teretibus fuscis puberulis ; internodiis ca. 5 cm. longis ; foliis
oppositis petiolatis ovatis longe acuminatis serratis basi rotundata et
apice caudato-attenuato integerrimis a basi 3(-5)-nerviis 7-10 cm.
longis 2-4 cm. latis firmiusculis utriuque viridibus scabriusculis, petiolo
fusco-puberulo ca. 1 cm. longo; cymis axillaribus glomeruliformibus
oppositis ca. 12-capitulatis 2-3 cm. diametro, pedicellis 1-5 mm. longis
teretibus sordido-tomentellis, bracteolis minimis fuscis ; involucris
subcylindrici-campanulatis saepissime 4-floris, squamis ca. 9 valde
iuaequalibus appresse imbricatis lanceolato-linearibus obtusis brunneis
dorso pilosiusculis, interioribus ca. 3 mm. longis ; corollis albis ex invo-
lucro longe exsertis ca. 4 mm. longis glabris, tubo proprio gracili in
fauces cylindricos subaequilongos leviter ampliato, dentibus limbi
brevissimis suberectis ; achaeniis (immaturis) fuscis obscure granulatis
quam corollae multo brevioribus ; pappi setis albis rectis ca. 20 sursum
scabriusculis corollam aequantibus. — In clayey soil on the crest of
the Sierra Madre in Michoacan or Guerrero, alt. 2300 m., 16 Februaiy,
1899, Langlasse, n. 880 (hb. Gray). This species is clearly related to
E. tubijlorum Benth. and B. areola?-e DC, but may be readily distin-
guished by its peculiar globular axillary inflorescences and by the fact
that the pappus is fully as long as the corolla.

Eupatorium purpureum L., var Bruneri (Gray), n. comb., foliis
oblongo-lanceolatis ternis vel quaternis vel quinis serratis firmiusculis
subtus plus minusve cinerascenti-puberulis vel tomentellis albescente
reticulato-venulosis ; corymbis planiusculis vel modice convexis. —
E. Bruneri Gray, Syn. Fl. i. pt. 2, 96 (1884) ; Coult. Man. Rocky Mt.
Reg. 142 (1885). E. atromontanum Nelson, Bot. Gaz. xxxi. 400 (June,
1901). E. Rydbergi Britton, Man. 921 (Oct. 1901). —Dr. Gray's
original characterization of E. Bruneri was drawn from a very poor
specimen and is so misleading that it is by no means surprising that
it has never been rightly understood. The leaves are not opposite, as
described, but are in whorls of three. In pubescence, venation, tooth-
ing, and texture, they correspond accurately with the widel}'' distrib-
uted western form of E. •pur'pureum, which as stated above has received
two subsequent specific names. The form, although fairly well marked
in its extreme, appears to pass by easy transitions into the typical form
of E. imrpureum and would therefore seem best treated as a variety.

ROBINSON. — STUDIES IN THE EUPATORIEAE. 45

In range it extends from Iowa to British Columbia and southward in
the Rocky Mountains to New Mexico.

Eupatorium rapunculoides, n. comb. Stevia rapunculoides DC.
Prod. V. 124 (1836). Eupatorium dasvcarpum Gray, Proc. Am. Acad,
xxii. 420 (1887); Robinson, ibid, xxxvi. 478 (1901).

Eupatorium remotifolium DC. Prod. v. 165 (18.36). This species
is reduced without comment by Baker in Mart. Fl. Bras. vi. pt. 2, 205
(1876) to E. Vitalbae DC, but the two species in question have not
the smallest resemblance. It can only be inferred that Mr. Baker was
misled through some transposition of labels or similar slip. The plants
are by no means similar in habit, leaf texture, inflorescence, or in-
volucre. The marked difference in the size of the heads is quite suffi-
cient to show them distinct species. In E. Vitalbae the florets,
including the mature achene, are 10-12 mm. long, while in E. remoti-
folium they are, when measured in the same manner, only 4-5 mm.
long.

Eupatorium resinosum Poepp. [& Endl.] Nov. Gen. et Spec. iii. 54
(1845), not Torr. From an examination of the type-specimen of this
obscure species, which is to be found in the herbarium of the Imperial
Natural History Museum at Vienna, it is clear that it is identical with
E. LAEVIGATUM Lam. Diet. ii. 408 (1786).

Eupatorium rubricaule HBK. Nov. Gen. et Spec. iv. 124 (1820).
Although excellently described by Kunth, this species appears never
to have been recognized. Hemsley (Biol. Cent. -Am. Bot. ii. 100) refers
no material to it beyond the original specimen collected by Humboldt
& Bonpland, and no more recent collection of it seems to be on record.
The type was found, however, to be exactly the plant for some years
known as E. amplifoUum Gray, Proc. Am. Acad. xv. 28 (1880), and
well shown by the following exsiccatae : Parry & Palmer's no. 334
from San Luis Potosi, Pringle's no. 4272 from cool canons near
Pazcuaro, Michoacan, Palmer's no. 165 (coll. of 1902) fi'om Alvarez,
San Luis Potosi, and L. C. Smith's no. 858 from the mountains of
Jayacatlan, alt. 2150 m., Oaxaca. Dr. Gray's later specific name
must, of course, drop into synonymy. Why E. rubricaule HBK.,
which is a large-leaved perennial, should have been referred to E.
guadalupense Spreng. by the Index Kewensis is not clear.

Eupatorium sagittatum Gray, PI. Wright, i. 88 (1852). This
species has in general ovate-oblong sagittate or hastate leaves con-
siderably longer than broad. In its wide deltoid leaves the following
plant is strikingly different, although maintaining the essential charac-
teristics of the species.

Var. deltophyilum, n. var., fruticosum oppositirameum habitu

46 PROCEEDINGS OF THE AMERICAN ACADEMY.

capitulis involucri scjuamis formae tj^icae simile ; foliis multo latiori-
bus deltoideis 3-4 cm. longis 2-4.4 ! cm. latis apice et angulis
inferioribus transverse divaricatis acutis. — Near Culiacan, Sinaloa,
Mexico, coll. Schajfner (type, in hb. Gray).

EuPATORiUxM THYRSOiDEUM Moc. ex DC. Prod. V. 150 (1836). Some
years ago the writer (Proc. Am. Acad, xxxvi. 484) stated the belief
that this plant was identical with E. quadrangulare DC. 1. c. How-
ever, subsequent study of more copious material and a re-examination
of the tj'pe specimens in the Prodromus Herbarium at Geneva have
shown conclusively that the two species are wholly distinct notwith-
standing considerable habital resemblance. To E. thiirsoideum, which
may be recognized by its roundish stem, more glomerate-thyrsoid
inflorescence, and softer less stramineous involucral scales, the follow-
ing specimens may be referred : Dr. Palmer's no. 1048 (coll. of 1890)
from Manzanillo, and his no. 1162 (coll. of 1891) from Colima, W. G.
Wright's no. 1355 from San Bias, Langlass^'s no. 650, collected on
granitic soil at Cajinicuilar, alt. 300 m., in Michoacan or Guerrero,
Baker's no. 2302, Volcan El Viejo, Dept. Chinandega, Nicaragua, and
Barclay's no. 2719 from Tiger Island, Gulf of Fonseca.

Eupatorhim tolimense Hieron. in Engl. Bot. Jahrb. xix. 45- (1894),
The writer, after examining the type of this species at the Boyal
Botanical Museum at Berlin and the type of E. pellucidum HBK.
Nov. Gen. et Spec. iv. 108 (1820), which is preserved in the herbarium
of the Museum of Natural History at Paris, is unable to find any
differences of importance between them.

EuPATORiuM urticaefolium Reichard, Syst. iii. 719 (1780). Agera-
tum altissimum L. Spec. PI. ii. 839 (1753). Eiipatorium altissimum
Murr. Syst. Veg. ed. 13, 614 (1774), not L., nor Murr. 1. c. 613. E.
ageratoides L. f Suppl. 355 (1781). Kyrstenia altissima Greene,
Leafl. i. 8 (1903). A consistent application of the rules of priority
necessitates the reviving of Reichard's name for our common and attrac-
tive N orth American Ewpatorium which has long passed as E. agera-
toides. Furthermore, in consequence of this revival of Reichard's
E. urticaefolium, it is necessary to suppress the later E. urticaefolium
L. f. Suppl. 354 (1781). This, however, is no great misfortune, for
the species of Linnaeus filius has been in recent times entirely mis-
interpreted, the name having been applied by English and German
botanists to a coarse annual, widely distributed in tropical America,
having rather long pedicels and ovate-lanceolate to lance-linear leaves.
This plant has borne many names, of which the earliest appears to be
the hitherto obscure E. pauci forum HBK. Nov. Gen. et Spec. iv. 120
(1820). Very di-fiferent from this is the type of ^. urticaefolium L. f,

KOBINSON. — STUDIES IN THE EUPATORIEAE. 47

which is still extant in the herbarium of the Linnean Society of
London. It is a Colombian plant, apparently perennial, with deltoid-
ovate, strongly cordate leaves and contracted inflorescence, the pedicels
being very short. It is not yet certain whether this plant has received
a later name, but it is pretty close to E. ballotaefolium HBK. and of
course has nothing whatever to do with the E. urticifolium of the
Flora Brasiliensis or of recent ^Titers on the flora of Argentina and
Paraguay.

MiKANiA Badieri DC. Prod. v. 194 (1896). This excellent species
is well marked by its coriaceous glabrous essentially entire leaves,
which are rather abruptly acuminate, ending in a caudate and often
falcate tip. The petioles are furthermore much flattened and rather
broad. The species, notwithstanding these distinctive characters, has
been reduced by Grisebach (Veg. Karaib. 85) to J/. lat'tfoUa J. E.
Smith (Rees, Cyclop, xxiii. n. 8). Grisebach also implies that it is
suspiciously close to M. amara Willd. However, the inflorescences in
M. Badieri are pyramidal panicles in which the heads are subspicately
arranged, while both in M. amara Willd. and in M. latlfiAla J. E.
Smith (ex char.) the heads are borne in corymbs. In the herbarium
of Lamarck there is a sheet of M. Badieri labelled in the hand of
Lamarck himself " Eupatorium vincaefolium Lam. diet. no. 39 de
Mr. Badier de la guadeloupe No 137." At first sight it would appear
that this was an authentic type of E. vincaefolium Lam. and that his
earlier specific name should take the place of DeCandolle's later
Badieri. However, Lamarck did not cite the plant of Badier in his
Dictionary, but on the other hand distinctly states that his E. vincae-
folium was founded on South American material. Indeed, most of
the characters are evidently drawn from Aublet's plate and description
of E. parvijiorum, which Lamarck reduces to a synon}'TQ of his own
species. Although Badier's plant of Guadeloupe possesses some hab-
ital similarity to the South American one, the latter lacks the broad
petioles and the peculiar acumination and is doubtless a distinct
species. Obviously, it is to the South American plant that Lamarck's
name E. vincaefolium was applied.

Mikania Houstoniana, n. comb. Eupatorium Houstonianum L.
Spec. ii. 836 (1753). E. Houstonis L. Syst. ed. 10, 1204 (1759).
Efruticosum Mill. Diet. ed. 8, no. 6 (1768). Mikania Houstonis Willd.
Spec. iii. 1742 (1804). The rule of priority of the specific name requires
the restoration of the earlier adjectival form.

Brickellia atractyloides Gray, Proc. Am. Acad. viii. 290 (1870).
Of this species, Coleosantkus venulosus A. Nelson, Bot. Gaz. xxxvii. 262
0904), is an exact synonym.

48 PROCEEDINGS OF THE AMERICAN ACADEMY.

Brickellia microphylla Gray, PI. Wright, i. 85 (1852) ; Bulbo-
stylis microphylla Nutt. Trans. Am. Phil. Soc. n. s. vii. 286 (1841). To
the synonymy of this species may be added B. ced/rosensis Greene, Bull.
Torr. Bot. Club, x. 86 (1883) ; Coleosanthiis cedrosensis Greene, Erythea,
i. 54 (1893).

Brickellia oblongifolia Nutt. Trans. Am. Phil. Soc. n. s. vii. 286
(1841). Of this species, Coleosanthus hum'dis Greene, Pittonia, iv. 124
(1900), appears to be a synonym.

Brickellia paniculata, n. comb. Eupatorium panlcidatum Mill.
Gard. Diet. ed. 8, no. 15 (1768). E. Verae-Crucis Steud. Nom. ed. 2,
i. 609 (1840). Ageratiim panlculatum Hort. and Eriopappus panlcu-
latus Hort. ex Steud. 1. c. Eupatorium rigidum Benth. PI. Hartw.
88 (1841), not Sw. Brickellia Hartwegi Gray, PI. Wright, i. 85 (1852).
Miller's Eupatorium paniculatum seems never to have been studied or
"accurately identified. It is evident that Steudel's renaming of the
species was purely a bibliographical change incident to his compilation,
and involving no personal examination of the plant. Miller's type,
collected at Vera Cruz, Mexico, by Dr. Houston, is still extant in the
herbarium of the British Museum of Natural History, and proves to
be the plant which has for some time been passing under the name of
Brickellia Hartwegi Gray. There seems no reason why Miller's name
should not be restored and transferred to the correct genus. Steudel's
purpose in renaming E. paniculatum Mill. (1768) was doubtless that he
might maintain the better known but much later homonym of Schrader
(1832), which, however, has since proved a synonym of ^. onicrostemon
Cass. Link, Enum. ii. 306 (1822), erroneously united under the name
E. paniculatum the very different plants of Miller and Schrader, be-
longing as we now see to two distinct genera. The unwarranted name
E. Verae-Crucis still persists in some botanical gardens.

Cacalia asclepiadea L. f. Suppl. 352 (1781). Senecio (?) asclepiadeus
DC. Prod. vi. 422 (1837). This doubtful species from Colombia seems
never to have been studied or accurately placed. Fortunately the
type-specimen is still extant in the herbarium of the Linnean Society
of London. It proves to be identical with Eupatorium angustifolium
Spreng. Syst. iii. 415 (1826); Mikania angustifoUa HBK. Nov. Gen.
et Spec. iv. 138 (1820). Although the Linnaean specific name is older,
it cannot be applied in Eupatorium because of the existing homon}Tn,
E. asclepiadeum DC. Prod. v. 148 (1836). Cacalia asclepiadea h. f.
should therefore drop into the synonymy of Eupatorium angusti-
folium (HBK.) Spreng. and the genus Cacalia (or Senecio) may thus be
freed from a dubious species.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. Xo. 2. — Jcke, 1906.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ARCHITECTURAL ACOUSTICS.

I. INTRODUCTION.
II. THE ACCURACY OF MUSICAL TASTE IN REGARD TO

ARCHITECTURAL ACOUSTICS.
III. VARIATION IN REVERBERATION WITH VARIATION IN
PITCH.

By Wallace C. Sabine.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ARCHITECTURAL ACOUSTICS.

Presented Dec. 13, 1905. Received March 22, 1906.

I. Introduction.

The problem of architectural acoustics requires for its complete
solution two distinct lines of investigation, one to determine quan-
titatively the physical conditions on which loudness, reverberation,
resonance, and the allied phenomena depend, the other to determine
the intensity which each of these should have, what conditions are
best for the distinct audition of speech, and what effects are best for
music in its various forms. One is a purely physical investigation,
and its conclusions should be based and should be disputed only on
scientific grounds ; the other is a matter of j udgment and taste, and
its conclusions are weighty in proportion to the weight and unanimity
of the authority in which they find their source. For this reason, these
papers are in two series. The articles which appeared six years ago
began the first, and the paper immediately following is the beginning
of the second.

Of the first series of papers, which have to do with the purely physi-
cal side of the problem, only one paper has as yet been published. This
contained a discussion of reverberation, complete as far as one note is
concerned. There is on hand considerable material for a paper ex-
tending this discussion to cover the whole range of the musical scale,
and therefore furnishing a basis for the discussion of what has sometimes
been called the musical quality of an auditorium. There has also been
collected a certain amount of data in regard to loudness, resonance,
interference, echos, irregularities of air currents and temperature, and
the transmission of sound through walls and partitions, — all of which
will appear as soon as a complete presentation is possible in each case.
Each problem has been taken up as it has been brought to the writer's
attention by an architect in consultation either over plans or in regard
to a completed building. This method is slow, but it has the advan-
tage of making the work practical, and may be relied on to prevent

52 PROCEEDINGS OF THE AMERICAN ACADEMY.

the magnification to undue importance of scientifically interesting but
practically subordinate points. On the other hand there is the danger
that it may lead to a fragmentary presentation. An effort has been
made to guard against this, and the effort for completeness is the reason
for delay in the appearance of some of the papers. Sufficient progress
has been made, however, to justify the assertion that the physical side
of the problem is solvable, and that it should be possible ultimately
to calculate in advance of construction all the acoustical qualities of
an auditorium.

Thus far it is a legitimate problem in physics, and as such a reason-
able one for the writer to undertake.

The second part of the problem, now being started, the question
as to what constitutes good and what constitutes poor acoustics, what
effects are desirable in an auditorium designed for speaking, and
even more especially in one designed for music, is not a question in
physics. It is therefore not one for which the writer is especially quali-
fied, and would not be undertaken here were it not in the first place
absolutely necessary in order to give effect to the rest of the work,
and in the second place were it not the plan rather to gather and give
expression to the judgment of others acknowledged as qualified to
speak, than to give expression to the taste and judgment of one. It
is thus the purpose to seek expert judgment in regard to acoustical
effects, and if possible to present the results in a form available to
architects. This will be slow and difficult work, and it is not at all
certain that it will be possible to arrive, even ultimately, at a finished
product. It is worth undertaking, however, if the job as a whole is
worth undertaking, for without it the physical side of the investigation
will lose much of its practical value. Thus it is of little value to be
able to calculate in advance of construction and express in numerical
measure the acoustical quality which any planned auditorium will have,
unless one knows also in numerical measure the acoustical quality which
is desired. On the other hand, if the owner and the architect can agree
on the desired result, and if this is within the limits of possibility con-
sidering all the demands on the auditorium, of utility, architecture,
and engineering, this result can be secured with certainty, — at least
there need be no uncertainty as to whether it will or will not be
attained in the completed building.

The papers following this introduction will be : " The Accuracy of
Musical Taste in regard to Architectural Acoustics," and " Variation
in Reverberation with Variation in Pitch."

sabine. — architectueal acoushcs. 53

11. The Accuracy of Musical Taste in regard to
Architectural Acoustics.

Piano Music.

The experiments described in this paper were underi;aken in order
to determine the reverberation best suited to piano music in a music
room of moderate size, but were so conducted as to give a measure of
the accuracy of cultivated musical taste. The latter point is obviously
fundamental to the whole investigation, for unless musical taste is
precise, the problem, at least as far as it concerns the design of the
auditorium for musical purposes, is indeterminate.

The first observations in regard to the precision of musical taste
were obtained during the planning of the Boston Symphony Hall,
Messrs. McKim, Mead, and White, Architects. Mr. Higginson, Mr,
Gericke, the conductor of the orchestra, and others connected with
the Building Committee expressed opinions in regard to a number of
auditoriums. These buildings included the old Boston Music Hall,
at that time the home of the orchestra, and the places visited by the
orchestra in its winter trips, Sanders Theatre in Cambridge, Carnegie
Hall in New York, the Academy of Music in Philadelphia, and the
Music Hall in Baltimore, and in addition to these the Leipsig Ge-
wandthaus. By invitation of Mr. Higginson, the writer accompanied
the orchestra on one of its trips, made measurements of all the halls,
and calculated their reverberation. The dimensions and the material
of the Gewandthaus had been published, and from these data its
reverberation also was calculated. The results of these measurements
and calculations showed that the opinions expressed in regard to the
several halls were entirely consistent with the physical facts. That
is to say, the reverberation in those halls in which it was declared too
great was in point of physical measurement greater than in halls in
which it was pronounced too small. This consistency gave encourage-
ment in the hope that the physical problem was real, and the end to
be attained definite.

Much more elaborate data on the accuracy of musical taste were
obtained four years later, 1902, in connection with the new building
of the New England Conservatory of Music, Messrs. Wheelwright and
Haven, Architects. The new building consists of a large auditorium
surrounded on three sides by smaller rooms, which on the second and
third floors are used for purposes of instruction. These smaller rooms,
when first occupied, and used in an unfurnished or partially fur-
nished condition, were found unsuitable acoustically, and the writer

54 PROCEEDINGS OF THE AMERICAN ACADEMY.

was consulted by Mr. Haven in regard to their final adjustment. In
order to learn the acoustical condition which would accurately meet
the requirements of those who were to use the rooms, an experiment was
undertaken in which a number of rooms, chosen as typical, were varied
rapidly in respect to reverberation by means of temporarily introduced
absorbing material. Approval or disapproval of the acoustical quality
of each room at each stage was expressed by a committee chosen by the
Director of the Conservatory. At the close of these tests, the reverbera-
tion in the rooms was measured by the \viiter in an entirely independ-
ent manner as described in the paper on Reverberation (1900). The
judges were Mr. George W. Chadwick, Director of the Conservatory,
and Sig. Oresti Bimboni, Mr, William H. Dunham, Mr. George W.
Proctor, and Mr. William L. Whitney, of the Faculty. The writer
suggested and arranged the experiment and subsequently reduced the
results to numerical measure, but expressed no opinion in regard to
the quality of the rooms.

The merits of each room in its varied conditions were judged solely
by listening to piano music by Mr. Proctor. The character of the
musical compositions on which the judgment was based is a matter of
interest in this connection, but this fact was not appreciated at the
time and no record of the selections was made. It is only possible to
say that several short fragments, varied in nature, were tried in each
room.

As will be evident from the descriptions given below, the rooms
were so differently furnished that no inference as to the reverberation
could be drawn from appearances, and it is certain that the opinions
were based solely on the quality of the room as heard in the piano
music.

The five rooms chosen as typical were on the second floor of the
building. The rooms were four meters high. Their volumes varied
from 74 to 210 cubic meters. The walls and ceilings were finished in
plaster on wire lath, and were neither papered nor painted. There was
a piano in each room ; in room 5 there were two. The amount of
other furniture in the rooms varied greatly :

In room 1 there was a bare floor, and no furniture except the piano
and piano stool.

Room 2 had rugs on the floor, chairs, a sofa with pillows, table,
music racks, and a lamp.

Room 3 had a carpet, chairs, bookcases, and a large number
of books, which, overflowing the bookcases, were stacked along the
walls.

Room 4 had no carpet, but there were chairs and a small table.

SABINE. — AKCHITECTURAL ACOUSTICS. 55

Room 5 had a carpet, chairs, and shelia curtains.

Thus the rooms varied from an almost unfurnished to a reasonably
furnished condition. In all cases the reverberation was too great.

The experiment was begun in room 1. There were, at the time,
besides the writer, five gentlemen in the room, the absorbing effect of
whose clothing, though small, nevertheless should be taken into account
in an accurate calculation of the reverberation. Thirteen cushions from
the seats in Sanders Theatre, whose absorbing power for sound had been
determined in an earlier investigation, were brought into the room.
Under these conditions the unanimous opinion was that the room, as
tested by the piano, was lifeless. Two cushions were then removed
from the room with a perceptible change for the better in the piano
music. Three more cushions were removed, and the effect was much
better. Two more were then taken out, leaving six cushions in the
room, and the result met unanimous approval. It was suggested that
two more be removed. This being done the reverberation was found
to be too great. The agreement was then reached that the condi-
tions produced by the presence of six cushions were the most nearly
satisfactory.

The experiment was then continued in Mr. Dunham's room, num-
ber 2. Six gentlemen were present. Seven cushions were brought into
the room. The music showed an insufficient reverberation. Two of the
cushions were then taken out. The change was regarded as a distinct
improvement, and the room was satisfactory.

In Mr. Whitney's room, number 3, twelve cushions, with which it
was thought to overload the room, were found insufficient even with
the presence in this case of seven gentleman. Three more cushions
were brought in and the result declared satisfactory.

In the fourth room, five, eight, and ten cushions were tried before the
conditions were regarded as satisfactory.

In Mr. Proctor's room, number 5, it was evident that the ten cush-
ions which had been brought into the room had overloaded it. Two
were removed, and afterwards three more, leaving only five, before a
satisfactory condition was reached.

This completed the direct experiment with the piano.

The bringing into a room of any absorbing material, such as these
cushions, affects its acoustical properties in several respects, but princi-
pally in respect to its reverberation. The prolongation of sound in a
room after the cessation of its source, may be regarded either as a case
of stored energy which is gradually suffering loss by transmission
through and absorption by the walls and contained material, or it may
be regarded as a process of rapid reflection from wall to wall with loss

56 PROCEEDINGS OF THE AMERICAN ACADEMY.

at each reflection. In either case it is called reverheration. It is some-
times called, mistakenly as has been explained, resonance. The rever-
beration may be expressed by the duration of audibility of the residual
sound after the cessation of a source so adjusted as to produce an aver-
age of sound of some standard intensity over the whole room. The
direct determination of this, under the varied conditions of this experi-
ment, was impracticable, but, by measuring the duration of audibility
of the residual sound after the cessation of a measured organ pipe in
each room without any cushions, and knowing the coefficient of absorp-
tion of the cushions, it was possible to calculate accurately the rever-
beration at each stage in the test. It was impossible to make these
measurements immediately after the above experiments, because, al-
though the day was an especially quiet one, the noises from the street
and railway traffic were seriously disturbing. Late the following night
the conditions were more favorable, and a series of fairly good obser-
vations was obtained in each room. The cushions had been removed,
so that the measurements were made on the rooms in their original
condition, furnished as above described. The apparatus and method
employed are described in full in a series of articles in the Engineering
Record and American Architect for 1900. The results are given in the
accompanying table.

The table is a record of the first of what, it is hoped, will be a series
of such experiments extending to rooms of much larger dimensions
and to other kinds of music. It may well be, in fact it is highly
probable, that very much larger rooms would necessitate a different
amount of reverberation, as also may other types of musical instru-
ments or the voice. As an example of such investigations, as well
as evidence of their need, it is here given in full. The following ad-
ditional explanations may be made. The variation in volume of the
rooms is only threefold, corresponding only to such music rooms as
may be found in private houses. Over this range a perceptible varia-
tion in the required reverberation should not be expected. The third
column in the table includes in the absorbing power of the room
(ceiling, walls, furniture, etc.) the absorbing powers of the clothes of
the writer, who was present not merely at all tests, but in the meas-
urement of the reverberation the following night. From the next
two columns, therefore, the writer and the effects of his clothing are
omitted. The remarks in the last column are reduced to the form
"reverberation too great," "too little," or "approved." The remarks
at the time were not in this form, however. The room was pronounced
"too resonant," "too much echo," "harsh," or "dull," "lifeless,"
" overloaded," expressions to which the forms adopted are equivalent.

SABINE.

ARCHITECTURAL ACOUSTICS.

u

4^

u

m

be

a

Ch

&

s

S !X

*a to

— ' 2

S 2

^

S,

(2 a

0^

<£•§

S.2

(2|

3

I"

a

3

o

= 83

J3 .^

a

a

35

o «

, 3

tf3

= 3

SO

O t-

^1

•§-2
= 5
1 o

Remarks.

a

a

3

s

to ^

3 o

go

•3^

>

o

O

JS

n

J2

.o

o

^

1

>

-=J

O

<

a

<!

H

JV»

74

5.0

0

0

0

0

5.0

2.43

Reverberation too great.

U

5

2.4

0

0

7.4

1.64

Reverberation too great.

It

t(

li

13

12.8

20.2

.60

Reverberation too little.

it

it

It

11

10.1

17.5

.70

Better.

it

it

il

8

7.3

14.7

.83

Better.

u

i<

it

6

5.5

12.9

.95

Condition approved.

u

((

n

4

3.6

11.0

1.22

Reverberation too great.

2

91

6.3

0

0

0

0

6.3

2.39

Reverberation too great.

li

6

2.9

0

0

9.2

1.95

Reverberation too great.

It

a

u

7

6.4

15.6

.95

Reverberation too little.

((

(«

If

5

4.6

13.8

1.10

Condition approved.

3

210

14.0

0

0

0

0

14.0

2.46

Reverberation too great.

((

7

3.4

0

0

17.4

2.00

Reverberation too great.

it

a

((

12

11.0

28.4

1.21

Better.

it

<(

((

15

13.7

31.1

1.10

Condition approved.

4

133

8.3

0

0

0

0

8.3

2.65

Reverberation too great.

((

7

3.4

0

0

11.7

1.87

Reverberation too great.

(t

U

tt

6

6.5

17.2

1.26

Better.

tt

(<

((

10

9.1

20.8

1.09

Condition approved.

5

96

7.0

0

0

0

0

7.0

2.24

Reverberation too great.

((

4

1.9

0

0

8.9

1.76

Reverberation too great.

((

((

It

10

9.1

18.0

.87

Reverberation too little.

((

t<

tt

8

7.3

16.2

.98

Better.

«

«

ti

5

4.6

13.5

1.16

Condition approved.

If from the larger table the reverberation in each room, in it.s most
approved condition, is separately tabulated, the following is obtained:

Rooms. Reverberation.

1 95

2 1.10

3 1.10

4 1.09

5 1.16

1.U8 mean.

The final result obtained, that the reverberation in a music room in
order to secure the best effect with a piano should be 1.08, or in
round numbers 1.1, is in itself of considerable practical value ; but the

58 PROCEEDINGS OF THE AMERICAN ACADEMY.

five determinations, by their mutual agreement, give a numerical
measure to the accuracy of musical taste which is of great interest.
Thus the maximum departure from the mean is .13 seconds, and the
average departure is .05 seconds. Five is rather a small number of
observations on which to apply the theory of probabilities, but, as-
suming that it justifies such reasoning, the probable error is .02
seconds — surprisingly small.

A close inspection of the large table will bring out an interesting
fact. The room in which the approved condition differed most from
the mean was the first. In this room, and in this room only, was it
suggested by the gentlemen present that the experiment should be
carried further. This was done by removing two more cushions. The
reverberation was then 1.22 seconds, and this was decided to be too
much. The point to be observed is that 1.22 is further above the
mean, 1.08, than .95 is below. Moreover, if one looks over the list in
each room it will be seen that in every case the reverberation corre-
sponding to the chosen condition came nearer to the mean than that
of any other condition tried.

It is conceivable that had the rooms been alike in all respects and
required the same amount of cushions to accomplish the same results,
the experiment in one room might have prejudiced the experiment in
the next. But the rooms being different in size and furnished so differ-
ently, an impression formed in one room as to the number of cushions
necessary could only be misleading if depended on in the next. Thus
the several rooms required 6, 5, 15, 10, and 5 cushions. It is further
to be observed that in three of the rooms the final condition was
reached in working from an overloaded condition, and in the other two
rooms from the opposite condition — in the one case by taking cushions
out, and in the other by bringing them in.

Before beginning the experiment no explanation was made of its
nature, and no discussion was held as to the advantages and disad-
vantages of reverberation. The gentlemen present were asked to ex-
press their approval or disapproval of the room at each stage of the
experiment, and the final decision seemed to be reached with perfectly
free unanimity.

This surprising accuracy of musical taste is perhaps the explanation
of the rarity with which it is entirely satisfied, particularly when the
architectural designs are left to chance in this respect.

SABINE. — ARCHITECTURAL ACOUSTICS. 59

III. Variation in Reverberation with Variation in Pitch.

Six years ago there was published in the Engineering Record and
the American Architect a series of papers on architectural acoustics
intended as a beginning in the general subject. The particular phase
of the subject under consideration was reverberation — the continua-
tion of sound in a room after the source has ceased. It was there
shown to depend on two things, — the volume of the room, and the
absorbing character of the walls and of the material with which the
room is filled. It was also mentioned that the reverberation depends
in special cases on the shape of the room, but these special cases were
not considered. The present paper also will not take up these special
cases, but postpone their consideration, although a good deal of mate-
rial along this line has now been collected. It is the object here to
continue the earlier work rather narrowly along the original lines.
The subject was then investigated solely with reference to sounds
of one pitch, C4 512 vibrations per second. It is the intention here
to extend this over nearly the whole range of the musical scale, from
Ci 64 to C7 4096.

It can be shown readily that the various materials* of which the
walls of a room are constructed and the materials with which it is filled
do not have the same absorbing power for all sounds regardless of
pitch. Under such circumstances the previously published work with
C4 512 must be regarded as an illustration, as a part of a much larger
problem — the most interesting part, it is true, because near the
middle of the scale, but after all only a part. Thus a room may have
great reverberation for sounds of low pitch and very little for sounds
of high pitch, or exactly the reverse ; or a room may have compara-
tively great reverberation for sounds both of high and of low pitch and
very little for sounds near the middle of the scale. In other words, it
is not putting it too strongly to say that a room may have very differ-
ent quality in different registers, as different as does a musical instru-
ment ; or, if the room is to be used for speaking purposes, it may have
different degrees of excellence or defect for a whisper and for the full
rounded tones of the voice, different for a woman's voice and for a
man's — facts more or less well recognized. Not to leave this as a
vague generalization the following cases may be cited. Recently, in
discussing the acoustics of the proposed cathedral of Southern Cali-
fornia in Los Angeles with Mr. Maginnis, its architect, and the writer,
Bishop Conaty touched on this point very clearly. After discussing
the general subject with more than the usual insight and experience,
possibly in part because Catholic churches and cathedrals have great

60 proceedi:ngs of the American academy.

reverberation, he added that he found it difficult to avoid pitching
his voice to that note which the auditorium most prolongs notwith-
standing the fact that he found this the worst pitch on which to speak.
This brings out, perhaps more impressively because from practical
experience instead of from theoretical considerations, the two truths
that auditoriums have very different reverberation for different pitches,
and that excessive reverberation is a great hindrance to clearness of
enunciation. Another incident may also serve, that of a church near
Boston in regard to which the writer has just been consulted. The
present pastor, in describing the nature of its acoustical defects, stated
that different speakers had different degrees of difficulty in making
themselves heard ; that he had no difficulty, having a rather high
pitched voice ; but that the candidate before him, with a louder but
much lower voice, failed of the appointment because unable to make
himself heard. Practical experience of the difference in reverberation
with variation of pitch is not unusual, but the above cases are rather
striking examples. Corresponding effects are not infrequently ob-
served in halls devoted to music. Its observation here, however, is
marked in the rather complicated general effect. The full discussion
of this belongs to another series of papers, in which will be taken up
the subject of the acoustical effects or conditions that are desirable
for music and for speech. While this phase of the subject will not
be discussed here at length, a little consideration of the data to be
presented will show how pronounced these effects may be and how
important in the general subject of architectural acoustics.

In order to show the full significance of this extension of the in-
vestigation in regard to reverberation, it is necessary to point out some
features which in earlier papers were not especially emphasized. Pri-
marily the investigation is concerned with the subject of reverbera-
tion, that is to say, with the subject of the continuation of a sound
in a room after the source has ceased. The immediate effect of
reverberation is that each note, if it be music, each syllable or part
of a syllable, if it be speech, continues its sound for some time, and by
its prolongation overlaps the succeeding notes or syllables, harmoniously
or inharmoniously in music, and in speech always towards confusion.
In the case of speech it is inconceivable that this prolongation of the
sound, this reverberation, should have any other effect than that of
confusion and injury to the clearness of the enunciation. In music,
on the other hand, reverberation, unless in excess, has a distinct and
positive advantage.

Perhaps this will be made more clear, or at least more easily realized
and appreciated, if we take a concrete example. Given a room com-

SABINE. — ARCHITECTURAL ACOUSTICS. 61

paratively empty, with hard wall surfaces, for example plaster or tile,
and having in it comparatively little furniture, the amount of rever-
beration for the sounds of about the middle register of the double-
bass viol and for the sounds of the middle register of the violin will be
very nearly though not exactly equal. If, however, we bring into the
room a quantity of elastic felt cushions, sufficient, let us say, to
accommodate a normal audience, the effect of these cushions, the
audience being supposed absent, will be to diminish very much the
reverberation both for the double-bass viol and for the violin, but will
diminish them in very unequal amounts. The reverberation will now
be twice as great for the double-bass as for the violin. If an audience
comes into the room, filling up the seats, the reverberation will be
reduced still further and in a still greater disproportion, so that with an
audience entirely filling the room the reverberation for the violin will
be less than one third that for the double-bass. When one considers
that a difference of five per cent in reverberation is a matter for ap-
proval or disapproval on the part of musicians of critical taste, the
importance of considering these facts is obvious.

This investigation, nominally in regard to reverberation, is in reality
laying the foundation for other phases of the problem. It has as one
of its necessary and immediate results a determination of the coeffi-
cient of absorption of sound of various materials. These coefficients
of absorption, when once known, enable one not merely to calculate
the prolongation of the sound, but also to calculate the average loud-
ness of sustained tones. Thus it was shown in one of the earlier
papers, though at that time no very great stress was laid on it, that
the average loudness of a sound in a room is proportional inversely
to the absorbing power of the material in the room. Therefore the data
which are being presented, covering the whole range of the musical
scale, enable one to calculate the loudness of different notes over that
range, and make it possible to show what effect the room has on the
piano or the orchestra in different parts of the register.

To illustrate this by the example above cited, if the double-bass
and the violin produce the same loudness in the open air, in the bare
room with hard walls both would be re-enforced about equally. The
elastic felt brought into the room would decidedly diminish this re-
enforcement for both instruments. It would, however, exert a much
more pronounced effect in the way of diminishing the re-enforcement
for the violin than for the double-bass. In fact, the balance wiU be so
affected that it will require two violins to produce the same volume
of sound as does one double-bass. The audience coming into the room
will make it necessary to use three violins to a double-bass to secure
the same balance as before.

62 PKOCEEDINGS OF THE AMERICAN ACADEMY.

Both cases cited above are only broadly illustrative. As a matter
of fact the effect of the room aud the effect of the audience in the
room is perceptibly different at the two ends of the register of the violin
and of the double-bass viol.

There is still a third effect, which must be considered to appreciate
fully the practical significance of the results that are being presented.
This is the effect on the quality of a sustained tone. Every musical
tone is composed of a great number of partial tones, the predominating
one being taken as the fundamental, and its pitch as the pitch of the
sound. The other partial tones are regarded as giving quality or color
to the fundamental. The musical quality of a tone depends on the
relative intensities of the overtones. It has been customary, at least
on the part of physicists, to regard the relative intensities of the
overtones, which define the quality of the sound, as depending simply
on the source from which the sound originates. Of course, primarily,
this is true. Nevertheless, while the source defines the relative in-
tensities of the issuing sounds, their actual intensities in the room
depend not merely on that, but also, and to a surprising degree, on
the room itself. Thus, for example, given an eight-foot organ pipe, if
blown in an empty room, such as that described above, the overtones
would be pronounced. If exactly the same pipe be blown with the
same wind pressure in a room in which the seats have been covered
with the elastic felt, the first upper partial will bear to the funda-
mental a ratio of intensity diminished over 40 per cent, the second
upper partial a ratio to the fundamental diminished in the same per
cent, the third upper partial a ratio diminished over 50 per cent,
while the fourth upper partial will bear a ratio of intensity to the
fundamental diminished about 60 per cent. Quality expressed numer-
ically in this way probably does not convey a very vivid impression
as to its real effect. It may signify more to say merely that the
change in quality is very pronounced and noticeable, even to com-
paratively untrained ears. On the other hand, if one were to try the
experiment with a six-inch instead of with an eight-foot organ pipe,
the effect of bringing the elastic felt cushions into the room would
be to increase the relative intensities of the overtones, and thus to
diminish the purity of the tone.

All tones below that of a six-inch organ pipe will be purified by
bringing into the room elastic felt. All tones above and including that
pitch will be rendered less pure. The effect of an audience coming
into a room is still different. Assuming that the audience has filled
the room and so covered all the elastic felt cushions, the effect of the
audience is to purify all tones up to violin C4 512, and to have very

SABINE. — AKCHITECTURAL ACOUSTICS. 63

little effect on all tones from that pitch upward. On very low tones
the effect of the audience in the room is more pronounced. For
example, again take Ci G4, the eft'ect of the audience will be to
diminish its first overtone about sixty per cent relative to the funda-
mental and its second overtone over seventy -five per cent.

The effect of the material used in the construction of a room, and
the contained furniture, in altering the relative intensities of the fun-
damental and the overtones, is to improve or injure its quality accord-
ing to circumstances. It may be, of course, that the tone desired is a
very pure one, or it may be that what is wanted is a tone with pro-
nounced upper partials. Take, for example, the "night horn " stop in
a pipe organ. This is intended to have a very pure tone. The room
in contributing to its purity would improve its quality. On the other
hand, the mixture stop in a pipe organ is intended to have very pro-
nounced overtones. In fact to this end not one but several pipes are
sounded at once. The effect of the above room to emphasize the fun-
damental and to wipe out the overtones would be in opposition to the
original design of the stop. To determine what balance is desirable
must lie of course with the musicians. The only object of the present
series of papers is to point out the fundamental facts, and that our
conditions may be varied in order to attain any desired end. One
great thing needed is that the judgment of the musical authorities
should be gathered in an available form ; but that is another problem,
and the above bare outline is intended only to indicate the importance,
of extending the work to the whole range of the musical scale, — the
work undertaken in the present paper.

The method pursued in these experiments is not very unlike that
followed in the previous experiments with C4512. It differs in minor
detail, but to explain these details would involve a great deal of
repetition which the modifications in the method are not of sufficient
importance to justify.

Broadly, the procedure consists first in the determination of the
rate of emission of the sound of an organ pipe for each note to be
investigated. This consists in determining the durations of audibility
after the cessation of two sounds, one having four or more, but a
known multiple, times the intensity of the other. From these results
it is possible to determine the rate of emission by the pipes, each in
terms of the minimum audibility for that particular tone. The appara-
tus used in this part of the experiment is shown in Figure 1. Four
small organs were fixed at a minimum distance of five meters apart. It
was necessary to place them at this great dista,nce apart because, as
already pointed out, if placed near each other the four sounded to-

64

PROCEEDINGS OF THE AMERICAN ACADEMY.

SABINE. — ARCHITECTURAL ACOUSTICS. 65

gether do not emit four times the sound emitted by one. This \vide
separation was particularly necessary for the large pipes and the low
tones ; a very much less separation would have served the purpose in
the case of the high tones.

From the point where the four tubes leading to the small organs
meet, a supply pipe ran, as shown on the drawing, to an air reservoir
in the room below. This was fed from an electrically driven blower
at the far end of the building. The chronograph was in another room.
The experiments with this apparatus, like the experiments heretofore
recorded, were carried out at night between twelve and five o'clock.

The rate of emission of sound by the several pipes having been
determined, the next work was the determination of the coefficients of
absorption. The methods employed having already been sufficiently
described, only results will be given.

In the very nature of the problem the most important data is the
absorption coefficient of an audience, and the determination of this
was the first task undertaken. By means of a lecture on one of the
recent developments of physics, an audience was enveigled into attend-
ing, and at the end of the lecture requested to remain for the experiment.
In this attempt the effort was made to determine the coefficients for the
five octaves from C2I28 to C6 2048, including notes E and G in each
octave. For several reasons the experiment was not a success. A
threatening thunder storm made the audience a small one, and the sul-
triness of the atmosphere made open windows necessary, while the
attempt to cover so many notes, thirteen in all, prolonged the experi-
ment beyond the endurance of the audience. While this experiment
failed, another the following summer was more successful. In the year
that had elapsed the necessity of carrying the investigation further
than the limits intended became evident, and now the experiment
was carried from Ci 64 to C, 4096, but including only the C notes,
seven notes in all. Moreover, bearing in mind the experiences of the
previous summer, it was recognized that even seven notes would come
dangerously near overtaxing the patience of the audience. Inasmuch
as the coefficient of absorption for C4 512 had already been deter-
mined six years before in the investigations mentioned, the coefficient
for this note was not redetermined. The experiment was therefore
carried out for the lower three and the upper three notes of the
seven. The audience, on the night of this experiment, was much
larger than that which came the previous summer, the night was a
more comfortable one, and it was possible to close the windows during
the experiment. The conditions were thus fairly satisfactory. In
order to get as much data as possible and in as short a time, there

VOL. XLII. 5

66

PROCEEDINGS OF THE AMERICAN ACADEMY,

were nine observers stationed at different points in the room. These
observers, whose kindness and skill it is a pleasure to acknowledge,

.9

^

/

r

.8
.7

/

/

.6
.5

/

/

-i

^^

.4

/

y

.3

/

.2

/

.1

....

Ci Ca

Cs C4

Figure 2.

C,

c.

c,

The absorbing power of .an audience for different notes. The lower curve
represents the absorbing power of an audience per person. Tlie upper curve rep-
resents the absorbing power of an audience per square meter as ordinarily seated.
Tlie vertical ordinates are expressed in terms of total absorption by a square
meter of surface. For the upper curve the ordinates are tlius the ordinary coeffi-
cients of absorption. The several notes are at octave intervals as follows, C^ 64,
C2 128, C3 (middle C) 256, C4 512, C5 1024, Cg 2048, C7 4096.

had prepared themselves by previous practice for this one experiment
As in the work of six years ago, the writer's key controlled the organ

SABINE. — ARCHITECTURAL ACOUSTICS. 67

pipes and started the chronograph, the writer and the other observers
each had a key which was connected with the chronograph to record
the cessation of audibility of the sound. The results of the experi-
ment are shown on the lower curve in Figure 2. This curve gives the
coefficient of absorption per person. It is to be observed that one of
the points falls clearly off the smooth curve drawn through the other
points. The observations on which this point is based were, however,
much disturbed by a street car passing not far from the building, and
the departure of this observation from the curve does not indicate a
real departure in the coefficient nor should it cast much doubt on the
rest of the work, in view of the circumstances under which it was
secured. Counteracting the perhaps bad impression which this point
may give, it is a considerable satisfaction to note how accurately the
point for C4 512, determined six years before by a different set of ob-
servers, falls on the smooth curve through the remaining points. In the
audience on which these observations were taken there were 77 women
and 105 men. The courtesy of the audience in remaining for the
experiment and the really remarkable silence which they maintained
is gratefully acknowledged.

The curve above discussed is that for the average person in an audi-
ence. An interesting form in which to throw the results is to regard
the audience as one side of a room. We may then look at it as an
extended absorbing surface, and determine the coefficient per square
meter. Worked out on this basis the absorption coefficient is in-
dicated in the higher curve. It is merely the lower curve multiplied
by a number which expresses the average number of people per
square meter. It is interesting to note that the coefficient of ab-
sorption is about the same from C4 512 up, indicating over that range
nearly complete absorption. Below that point there is a very great
falling off, down to Ci 64. The curve is such as to permit of an extra-
polation indicative of even less absorption and consequently greater
reverberation for the still lower notes. Without entering into an elab-
orate discussion of this curve, two points may be noted as particularly
interesting. The first is the nearly complete absorption for the higher
notes, a result which at first sight seems a little inconsistent with
the results which will be shown later on in connection with the absorp-
tion by felt. The inconsistency, however, is only apparent. The
greater absorption shown by an audience than that shown by thick
felt arises from the fact that the surface of the audience is irregular
and does not result in a single reflection, but probably, for a very large
portion of the sound, of multiple reflection before it finally emerges.
The physical conditions are such that they obviously do not admit of

68

PROCEEDINGS OF THE AMERICAN ACADEMY.

analytic expression, but the explanation of the great absorption by an
extended audience surface is not difficult to understand. In addition

Figure 3.

to the above there is another partial explanation which contributes to
the results. The felt forms a perfectly continuous medium, and there-
fore otfers a comparatively rigid reflecting surface. The comparatively
light, thin, and porous nature of the clothing of women, perhaps more
than of men, contributes to the great absorption of the high notes.

SABINE. — ARCHITECTURAL ACOUSTICS.

69

The next experiment, taking them up chronologically, and perhaps
next even from the standpoint of interest, was in regard to a brick

.10

.09

.08

.07

.06

.06

.04

.03

.02

.01

I ^-^-^ ^^

Cx

c.

c,

a

c.

Figure 4.

Tlie absorbin{r power of a 45 cm. tliick brick wall. The upper curve represents
the absorbing power of an unpainted brick surface. The bricks were hard but
not glazed, and were set in cement. The lower curve represents the absorbing
power of the same surface painted with two coats of oil paint. The difference
between the two curves represents the absorption due to the porosity of the bricks.
In small part, but probably only in small part, the difference is due to difference in
superficial smoothness. C3 (middle C) 256.

wall surface. This experiment was carried out in the constant tem-
perature room mentioned in the previous papers. The arrangement
of apparatus is shown in Figure 3, where the air reservoir in the room

70 PROCEEDINGS OF THE AMERICAN ACADEMY.

above is shown in dotted lines. In many respects the constant tem-
perature room offered admirable conditions for the experiment. Its
position in the centre of the building and its depth underground
made it comparatively free from outside disturbing noises, — so much
so that it was possible to experiment in this room in the earlier parts
of the evening, although not, of course, when any one else was at work
in the building. While it possesses these advantages, its arched ceil-
ing, by placing it in the category of special cases, makes extra pre-
caution necessary. Fortunately, at the beginning of the experiment
the walls were unpainted. Under these conditions its coefficient of
absorption for different notes was determined. It was then painted
with an oil paint, two coats, and its coefficient of absorption re-
determined. The two curves are shown in Figure 4. The upper
curve is for the unpainted brick ; the lower curve is that obtained
after the walls were painted. The difference between the two curves
would, if plotted alone, be the curve of absorption due to the poros-
ity of the brick. It may seem, perhaps, that the paint in covering
the bare brick wall made a smoother surface, and the difference be-
tween the two results might be due in part to less surface friction. Of
course this is a factor, but that it is an exceedingly small factor will be
shown later in the discussion of the results on the absorption of sound
by other bodies. The absorption of the sound after the walls are
painted is, of course, due to the yielding of the walls under the vibra-
tion, to the sound actually transmitted bodily by the walls, and to the
absorption in the process of transmission. It is necessary to call atten-
tion to the fact that the vertical ordinates are here magnified tenfold
over the ordinates shown in the last curve.

The next experiment was on the determination of the absorption of
sound by wood sheathing. It is not an easy matter to find conditions
suitable for this experiment. The room in which the absorption by
wood sheathing was determined in the earlier experiments was not
available for these. It was available then only because the building
was new and empty. When these more elaborate experiments were
under way the room had become occupied, and in a manner that did
not admit of its being cleared. Quite a little searching in the neigh-
borhood of Boston failed to discover an entirely suitable room. The best
one available adjoined a night lunch room. The night lunch was bought
out for a couple of nights, and the experiment was tried. The work of
both nights was much disturbed. The traffic past the building did not
stop until nearly two o'clock, and began again about four. The interest
of those passing by on foot throughout the night, and the necessity of
repeated explanations to the police, greatly interfered with the work.

SABINE. — ARCHITECTURAL ACOUSTICS.

71

FlGUKE 5.

72

PROCEEDINGS OF THE AMERICAN ACADEMY.

This detailed statement of the conditions under which the experiment
tried is made by way of explanation of the irregularity of the ob-

was

Figure 6.

servations recorded on the curve, and of the failure to carry this par-
ticular line of work further. The first niffht seven points were obtamecl
for the seven notes Ci 64 to C, 4096. This work was done by means

SABINE. — ARCHITECTURAL ACOUSTICS.

73

.13

.U

.10

.09

.08

.07

.06

.05

.04

.03

.02

.01

C,

Cj C4

FlGCRE 7.

The absorbing power of wood sheathing, two centimeters thick, North CaroHna
pine. The observations were made under very unsuitable conditions. The ab-
sorption is here due almost wholly to yielding of the sheathing as a whole, the
surface being shellacked, smooth, and non-porous. The curve shows one point of
resonance within the range tested, and the probability of another point of reson-
ance above. It is not possible now to learn as much in regard to the framing
and arrangement of the studding in the particular room tested as is desirable.
C3 (middle C) 256.

74 PROCEEDINGS OF THE AMERICAN ACADEMY.

of a portable apparatus shown in Figure 5. The reduction of these
results on the following day showed variations indicative of maxima
and minima, which to be accurately located would require the de-
termination of intermediate points. The experiment the following
night was by means of the organ shown in Figure 6, and points were
determined for the E and G notes in each octave between C2 128 and
Ce 2048. Other points would have been determined, but time did not
permit. It is obvious that the intermediate points in the lower and
in the higher octave were desirable, but no pipes were to be had on
such short notice for this part of the range, and in their absence the
data could not be obtained. In the diagram. Figure 7, the points
lying on the vertical lines were determined the first night. The
points lying between the vertical lines were determined the second
night. The accuracy with which these points fall on a smooth curve
is perhaps all that could be expected in view of the difficulty under
which the observations were conducted and the limited time available.
One point in particular falls far off from this curve, the point for C3 256,
by an amount which is, to say the least, serious, and which can be jus-
tified only by the conditions under which the work was done. The gen-
eral trend of the curve seems, however, established beyond reasonable
doubt. It is interesting to note that there is one point of maximum
absorption, which is due to resonance between the walls and the sound,
and that this point of maximum absorption lies in the lower part,
though not in the lowest part, of the range of pitch tested. It would
have been interesting to determine, had the time and facilities per-
mitted, the shape of the curve beyond C7 4096, and to see if it rises
indefinitely, or shows, as is far more likely, a succession of maxima.
The scale employed in this curve is the same as that employed in the
diagram of the unpainted and painted wall surfaces. It may perhaps
be noted in this connection that at the very least the absorption is four
times that of painted brick walls.

The experiment was then directed to the determination of the absorp-
tion of sound by cushions, and for this purpose return was made to the
constant temperature room. Working in the manner indicated in the
earlier papers for substances which could be carried in and out of a
room, the curves represented in Figure 8 were obtained. Curve 1
shows the absorption coefficient for the Sanders Theatre cushions, with
which the whole investigation was begun ten years ago. These cush-
ions were of a particularly open grade of packing, a sort of wiry grass
or vegetable fiber. They were covered with canvas ticking, and that
in turn with a very thin cloth covering. Curve 2 is for cushions bor-
rowed from the Phillips Brooks House. They were of a high grade, filled

SABINE. — ARCHITECTURAL ACOUSTICS.

75

with long curly hair, and covered with canvas ticking, which was in
turn covered by a long nap plush. Curve 3 is for the cushions of Ap-

.9
.8
.7

/4

\

r

^3

\

/

f

"SVv

^

\

.6
.5
.4
,3
.2
.1

^

//

\

N

n\

/ /

^

V

\

f\

7

\

/>

/

\

\

C:

C.

Ce

Cj C3 C4

Figure 8.

The absorbing power of cusliions. Curve 1 is for " Sanders Theatre" cushions
of wiry vegetable fibre covered with canvas ticking and a thin cloth. Curve 2 is for
"Brooks House" cushions of long hair covered with the same kind of ticking and
plush. Curve 3 is for " Appleton Chapel " cushions of hair covered with ticking
and a thin leatherette. Curve 4 is for the elastic felt cushions of commerce of
elastic cotton covered with ticking and short nap plush. The absorbing power
is per square meter of surface. C3 (middle C) 256.

pleton Chapel, hair covered Anth a leatherette, and showing a sharper
maximum and a more rapid diminution in absorption for the higher

76 PROCEEDINGS OF THE AMERICAN ACADEMY,

frequencies, as would be expected under such conditions. Curve 4 is
probably the most interesting, because for more standard commercial
conditions. It is the curve for elastic felt cushions as made by Sperry
and Beale. It is to be observed that all four curves fall off for the
higher frequencies, all show a maximum located within an octave, and
three of the curves show a curious hump in the second octave. This
break in the curve is a genuine phenomenon, as it was tested time after
time. It is perhaps due to a secondary resonance, and it is to be
observed that it is the more pronounced in those curves that have
the sharper resonance in their principal maxima.

Observations were then obtained on unupholstered chairs and set-
tees. The result for chairs is shown in Figure 10. This curve gives
the absorption coefficient per single chair. The effect was surprisingly
small ; in fact, when the floor of the constant temperature room was
entirely covered with the chairs spaced at usual seating distances, the
effect on the reverberation in the room was exceedingly slight. The
fact that it was so slight and the consequent difficulty in measuring
the coefficient is a partial explanation of the variation of the results as
indicated in the figure. Nevertheless it is probable that the variations
there indicated have some real basis, for a repetition of the work showed
the points again falling above and below the line as in the first experi-
ment. The amount that these fell above and below the line was diffi-
cult to determine, and the number of points along the curve were too
few to justify attempting to follow their values by the line. In fact the
line is drawn on the diagram merely to indicate in a general way the
fact that the coefficient of absorption is nearly the same over the whole
range. A varying resonance phenomenon was unquestionably present,
but so small as to be negligible ; and in fact the whole absorption by
the chairs is an exceedingly small factor. The chair was of ash, and its
type is shown in the accompanying sketch, Figure 9.

The results of the observations on settees is shown in Figure 1 1 .
Those plotted are the coefficients per single seat, there being four seats
to the settee. The settees were placed at the customary distance.
Here again the principal interest attaches to the fact that the coefficient
of absorption is so exceedingly small that the total effect on the rever-
beration is hardly noticeable. Here also the plotted results do not fall
on the line drawn, and the departure is due probably to some slight
resonance. The magnitude of the departure, however, could not be
determined with accuracy because of the small magnitude of the total
absorption coefficient. For these reasons and because the number of
points was insufficient, no attempt was made to draw the curve through
the plotted points, but merely to indicate a plotted tendency. The

SABINE. — ARCHITECTURAL ACOUSTICS.

77

Figure 9.

.03

.03

.01

C, C, C, C, C: C, C,

Figure 10.
The absorbing power of ash chairs shown in Figure 9.

=i==H — —I -

i . — •

— '1

.03

.02

.01

•

" i| ___■-■ — '

>

c, c, c, c, c.

Figure 11.

C,

The absorbing power of ash settees shown in Figure 9. Tlie absorption is per
single sent, the settee as shown seating five.

78 PROCEEDINGS OF THE AMERICAN ACADEMY,

settees were of ash, and their general style is shown in the accompany-
ing sketch.

An investigation was then begun in regard to the nature of the pro-
cess of absorption of sound. The material chosen for this work was a
very durable grade of felt, which, as the manufacturers claimed, was all
wool. Even a casual examination of its texture makes it difficult to
believe that it is all wool. It has, however, the advantage of being
porous, flexible, and very durable. Almost constant handling for sev-
eral years has apparently not greatly changed its consistency. It is to
be noted that this felt is not that mentioned in the papers of six years
ago. That felt was of lime-treated cow's hair, the kind used in pack-
ing steam pipes. It was very much cheaper in price, but stood little
handling before disintegrating. The felt employed in these experi-
ments comes in sheets of various thicknesses, the thickness here
employed being about 1.1 cm.

The coefficient of absorption of a single layer of felt was measured
for the notes from Ci 64 to C7 4096 at octave intervals. The experi-
ment was repeated for two layers, one on top of the other, then for three,
and so on up to six thicknesses of felt. Because the greater thicknesses
presented an area on the edge not inconsiderable in comparison with
the surface, the felt was surrounded by a narrow wood frame. Under
such circumstances it was safe to assume that the absorption was
entirely by the upper surface of the felt. The experiment was repeated
a great many times, first measuring the coefficient of absorption for one
thickness for all frequencies, and then checking the work by conducting
experiments in the other order ; that is, measuring the absorption by
one, two, three, etc., thicknesses, for each frequency. The mean of all
observations is shown in Figure 12 and Figure 13. In Figure 12 the
variations in pitch are plotted as abscissas, as in previous diagrams,
whereas in Figure 13 the thicknesses are taken as abscissas. The special
object of the second method will appear later, but a general object of
adopting this method of plotting is as follows :

If we consider Figure 12, for example, the drawing of the line through
any one set of points should be made not merely to best fit those
points, but should be drawn having in mind the fact that it, as a curve,
is one of a family of curves, and that it should be drawn not merely as
a best curve through its own points, but as best fits the whole set. For
example, in Figure 12 the curve for four thicknesses would not have
been drawn as there shown if drawn simply with reference to its own
points. It would have been drawn directly through the points for
Ci 64 and C2 128. Similarly the curve for five thicknesses would have
been drawn a little nearer the point for C2 128, and above instead of

SABINE. — ARCHITECTURAL ACOUSTICS.

79

below the point for Ci 64. Considering, however, the whole family of
curves and recognizing that each point is not without some error, the

C3 c, c.

Figure 12.

C,

The absorbing power of felt of different thicknesses. Each piece of felt was
1.1 cm. in tliickness. Curve 1 is for a single thickness, curve 2 for two thicknesses
placed one on top of the other, etc. As shown by these curves, the absorption
is in part by penetration into the pores of the felt, in part by a yielding of the
mass as a whole. Resonance in the latter process is clearly shown by a maximum
shifting to lower and lower pitch with increase in thickness of the felt. C3 (mid-
dle C) 256.

curves as drawn are more nearly correct. The best method of reconcil-
ing the several curves to each other is to plot two diagrams, one in
which the variations in pitch are taken as abscissa and one in which

80 PROCEEDINGS OF THE AMERICAN ACADEMY.

the variations in thickness of felt are taken as abscissas ; then draw
through the points the best fitting curves and average the correspond-
ing ordinates taken from the curves thus drawn ; and with these aver-
age ordinates redraw both families of curves. The points shown on
the diagram are of course the original results obtained experimentally.
In general they fall pretty close to the curves, although at times, as in
the points noted, they fall rather far to one side.

The following will serve to present the points of particular interest
revealed by the family of curves in Figure 12, where the absorption by
the several thicknesses is plotted against pitch for abscissas. It is to
be observed that a single thickness scarcely absorbs the sound from
the eight, four, and two foot organ pipes, Ci 6-4, C2 128, and C3 256,
and that its absorption increases rapidly for the next two octaves,
after which it remains a constant. Two thicknesses absorb more —
about twice as much — for the lower notes, the curve rising more
rapidly, passing through a maximum between C4 512 and C5 1024, and
then falling off for the higher notes. The same is true for greater
thicknesses. All curves show a maximum, each succeeding one cor-
responding to a little lower note. The maximum for six thicknesses
coincides pretty closely to C4 512. The absorption of the sound by
felt may be ascribed to three causes, — porosity of structure, compres-
sion of the felt as a whole, and friction on the surface. The presence
of the maximum must be ascribed to the second of these causes, the
compression of the felt as a whole. As to the third of these three causes,
it is best to consult the curves of the next figure.

The following facts are rendered particularly evident by the curves
of Figure 13. For the tones emitted by the eight-foot organ pipe,
Ci 64, the absorption of the sound is very nearly proportional to the
thickness of the felt over the range tested, six thicknesses, 6.6 cm.
The curves for notes of increasing pitch show increasing value for the
coefficients of absorption. They all show that were the thickness of the
felt sufficiently great, a limit would be approached, — a fact, of course,
self-evident, — but for C5 1024 this thickness was reached within the
range experimented on ; and of course the same is true for all higher
notes, Ce 2048 and C, 4096. The higher the note, the less the thick-
ness of felt necessary to produce a maximum effect. The curves of
Ci 64, C2 128, C3 256, and C4 512, if extended backward, would pass
nearly through the origin. This indicates that for at least notes of so
low a pitch the absorption of sound would be zero, or nearly zero, for
zero thickness. Since zero thickness would leave surface effects, the
argument leads to the conclusion that surface friction as an agent in
the absorption of sound is of small importance. The curves plotted

SABINE. — ARCHITECTURAL ACOUSTICS.

81

1.0

.9

.8

.6

-^

1

^

^

j^^

I

/

/

/:

1 ^

fcT

/ ^

/ ,

^

h

/

/c,

1

/

/

1

y

^^ i

1

/ \

//

Xc,

j

^

■^

1
4

^

1

2 3 4

Figure 13.

6

The absorbing power of felt of different tiiicknesses. The data, Figure 12, is here
plotted in a slightly different manner, — horizontally on plotted increasing thickness,
— and the curves are for notes of different frequency at octave intervals in pitch.
Tims plotted the curves show the necessary thickness of felt for practically maxi-
mum efficiency in absorbing sound of different pitch. Tliese curves also show
that for the lowest three notes surface friction is negligible, at least in comparison
with the other factors. For the high notes one thickness of felt was too great for
the curves to be conclusive in regard to this point. C3 (middle C) 256.

do not give any evidence in this respect in regard to the higher notes,
Cs 1024, Cs 2048, and C7 4096.

It is of course evident that the above data do not by any means

VOL. XLII.

82 PROCEEDINGS OF THE AMERICAN ACADEMY.

cover all the ground that should be covered. It is highly desirable
that data should be accessible for glass surfaces, for glazed tile surfaces,
for plastered and unplastered porous tile, for plaster on wood lath and
plaster on wire lath, for rugs and carpets ; but even with these data
collected the job would be by no means completed. What is wanted
is not merely the measurement of existing material and wall surfaces,
but an investigation of all the possibilities. A concrete case will
perhaps illustrate this. If the wall surface is to be of wood, there
enter the questions as to what would be the effect of varying the
material, — how ash differs from oak, and oak from walnut or pine or
whitewood ; what is the effect of variations in thickness ; what the
effect of panelling ; what is the effect of the spacing of the furring on
which the wood sheathing is fastened. If the wall is to be plaster on
lath, there arises the question as to the difference between wood lath
and wire lath, between the mortar that was formerly used and the
wall of to-day, which is made of hard and impervious plaster. What
is the effect of variations in thickness of the plaster 1 What is the
effect of painting the plaster in oil or in water colors ? What is
the effect of the depth of the air space behind the plaster ? The
recent efforts at fireproof construction have resulted in the use of
harder and harder wall surfaces, and great reverberation in the room,
and in many cases in poorer acoustics. Is it possible to devise a
material which shall satisfy the conditions as to fireproof qualities and
yet retain the excellence of some of the older but not fireproof rooms 1
Or, if one turns to the interior furnishings, what type of chair is best,
what form of cushions, or what form of upholstery 1 There are many
forms of auditorium chairs and settees, and all these should be in-
vestigated if one proposes to apply exact calculation to the problem.
These are some of the questions that have arisen. A little data have
been obtained looking toward the answer to some of them. The diffi-
culty in the way of the prosecution of such work is greater, however,
than appears at first sight, the particular difficulties being of opportunity
and of expense. It is difficult, for example, to find rooms whose walls
are in large measure of glass, especially when one bears in mind that
the room must be empty, that its other wall surfaces must be of a
substance fully investigated, and that it must be in a location admit-
ting of quiet work. Or, to investigate the effect of the different kinds
of plaster and of the different methods of plastering, it is necessary
to have a room, preferably an underground room, which can be lined
and relined. The constant temperature room which is now available
for the experiments is not a room suitable to that particular investiga-
tion, and for best results a special room should be constructed. More-

SABINE. — ARCHITECTURAL ACOUSTICS. 83

over, the expense of plastering and replastering a room — and this
process, to arrive at anything like a general solution of the problem,
would have to be done a great many times — would be very great, and
is at the present moment prohibitive. A little data along some of
these lines have been secured, but not at all in final form. The work
in the past has been largely of an analytical nature. Could the in-
vestigation take the form of constructive research, and lead to new
methods and greater possibilities, it would be taking its more interest-
ing form.

The above discussion has been solely with reference to the deter-
mination of the coefficient of absorption of sound. It is now proposed
to discuss the question of the application of these coefficients to the
calculation of reverberation. In the first series of papers, reverbera-
tion was defined with reference to C4 512 as the continuation of the
sound in a room after the source had ceased, the initial intensity of
the sound being one million times minimum audible intensity. It is
debatable whether or not this definition should be extended without
alteration to reverberation for other notes than C4 512. There is a
good deal to be said both for and against its retention. The whole,
however, hinges on the outcome of a physiological or psychological
inquiry not yet in such shape as to lead to a final decision. The
question is therefore held in abeyance, and for the time the definition
is retained.

Retaining the definition, the reverberation for any pitch can be
calculated by the formula

KV

T =

a

where V is the volume of the room, ^ is a constant depending on the
initial intensity, and a is the total absorbing power of the walls and
the contained material. K and V are the same for all pitch fi-equen-
cies. K is .164 for an initial intensity 10® timeis minimum audible
intensity. The only factor that varies with the pitch is a, which can
be determined from the data given above.

In illustration, the curves in the accompanying Figure 14 give the
reverberation in the large lecture room of the Jefferson Physical
Laboratory. The upper curve defines the reverberation in the room
when entirely empty ; the lower curve defines this reverberation in
the same room with an audience two thirds filling the room. The
upper curve represents a condition which would be entirely impractical
for speaking purposes ; the lower curve represents a fairly satisfactory
condition.

84

PROCEEDINGS OF THE AMERICAN ACADEMY.

10

9

8

7

6

5

4

3

2

k

1

c.

C3 C4

Figure 14.

C,

Curves expressing the reverberation in the large lecture room of the Jefferson
Piiysical Laboratory with (lower curve) and without (upper curve) an audience.
Tliese curves express in seconds the duration of tlie residual sound in the room
after the cessation of sources producing intensities 10"^ times minimum audible
intensity for each note. The upper curve describes acoustical conditions wliich
are very unsatisfactory, as the hall is to be used for speaking purposes. The lower
curve describes acoustically satisfactory conditions. C3 (middle C) 256.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 3. — June, 1906.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE PERMEABILITY AND THE RETENTIVENESS
OF A MASS OF FINE IRON PARTICLES.

By B. Osgood Peirce.

CONTRIBUTIONS FROxM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE PERMEABILITY AND THE RETENTIVENESS OF
A MASS OF FINE IRON PARTICLES.

By B. Osgood Peirce.

Presented February 14, 1906. Received March 13, 1906.

In a familiar lecture-room experiment, a mass of iron filings, filling
a straight glass tube to a length of thirty or forty times its diameter, is
forced to become a rather weak *' bar magnet " by subjecting it to a
strong exciting field in a solenoid ; and then, by rearranging the parti-
cles, it is made to lose its magnetic moment almost completely, although,
if, after the filings have been poured out of the tube, a few of them be
examined under a microscope of moderate power, it is usually easy to
see that most of the elongated particles retain some magnetism for a
good while. A number of persons ^ have studied the magnetic prop-
erties of masses of iron filings or of chemically deposited " iron dust,"
as well as of mixtures of iron particles in various proportions with non-
magnetic powders of various kinds. Concise statements of the results
of experiments on the subject are to be found in the papers of Maurain
and Trenkle.

I have lately had occasion to measure the permeability and the
retentiveness of each of several masses of very fine cast-iron particles,
or dust, made by a fine cutting end-mill in a milling-machine, and, as
testing the effect upon their magnetic properties of subjecting the
particles to a " hardening " process, the results seem to have some
slight interest.

The material to be examined was tamped solidly into a glass tube
almost exactly one centimeter in diameter, until a column was formed
fifty diameters long. After its ends had been closed by corks, the com-
paratively short tube was put into the middle of a long solenoid S, the

* Tijpler, Pogg. Ann. d. Phys., 1877; v. Waltenhofen, Wied. Ann. d. Phys.,
1870; Jamin, Comptes rendus, 1875; Bornstein, Pogg. Ann. d. Phys., 1875;
Auerbach, Wied. Ann. d. Pliys., 1880 ; Baur, Wied. Ann. d. Phys., 1880; Maurain,
;feclairage, ifelect., 1903; Trenkle, Eriangen. Sitzungsberichte, 1905; Wied. Ann.
d. Pliys., 1900.

88

PROCEEDINGS OF THE AMERICAN ACADEMY.

axis of which was horizontal and perpendicular to the meridian. The
connections of the apparatus are shown schematically in Figure 1.

After the tube (Q) had been
placed in >S', the double
switch T was closed to the
left, so as to connect >S' with
the secondary (Z) of a
transformer the primary of
which was attached to the
alternating street circuit.
The secondary coil was so
suspended with counterbal-
ancing weights in a tall
fi-ame that it could be
moved at will in the direc-
tion of its axis to a distance
of several feet away from
the primary, and thus a
great number of alterna-
tions of a current gradually
decreasing in intensity
could be sent through S to
demagnetize the specimen
in it.

31 represents a magnet-
ometer in the form of a
mirror galvanometer placed
in Gauss's B Position with
respect to Q ; the galvan-
ometer was so shunted by
an adjustable resistance JT
that the effect on the gal-
vanometer needle of the
partial current through the
coils of the instrument
almost exactly compensated
for the effect of the whole
current through the sole-
noid aS' when empty. B is
an adjustable rheostat of
200 ohms total resistance, designed to carry currents of some intensity,
K is a commutator, and IV a milliamperemeter furnished with a set of

PEIRCE. — PERMEABILITY OF A MASS OF FINE IRON PARTICLES. 89

four shunts. When the switch T was closed to the right, it was possi-
ble, by manipulating the rheostat arm and the commutator K, to put
Q through any desired hysteresis cycle in the usual manner. The
current came from a battery of storage cells, any number of which
could be used at pleasure. A current of 1 ampere in the solenoid
gave rise to a field of 54.8 gausses in the space within it. The field
about M'b needle had to be artificially strengthened to suit the circum-
stances, and a piece of soft Bessemer steel rod of almost exactly the
same dimensions as the column of filings was used to determine the
sensitiveness of the apparatus at any time. By means of a coil of 20
turns of extremely fine insulated copper wire wound directly on this
piece at its centre and connected with a carefully standardized ballistic
galvanometer, the induction flux through the centre of the rod could
be found and the corresponding deflection of the magnetometer needle
determined.

The work was undertaken in order to compare the magnetic prop-
erties of masses of iron particles, as they came from the milling-machine,
with those of masses of particles from the same lot which had under-
gone the treatment used in hardening iron castings for permanent
magnets. These " filings " were prepared by Mr. G. W. Thompson,
the mechanician of the Jefferson Laboratory, who has had much ex-
perience in the process. A completely closed iron crucible with thin
walls, containing a mass of the particles to be treated, was heated
white hot under a power blast in a gas furnace, and then suddenly
chilled in an acid bath. After this experience, during which the
particles had been carefully excluded from the air, they had a some-
what altered color and lustre, but under a microscope of low power
showed very little difference from the untreated particles ; at best all
such particles cut by machine tools from iron castings are most irreg-
ular in form, and are so much seamed by deep furrows and pits as to
look like clinkers from a furnace. All the particles were kept quite
free from oil or dirt, and the surfaces of the " hardened " ones were
only very slightly tarnished, but it was not possible to pack quite so
large a mass of the material into a given space after the treatment as
before. This might have arisen from changes of shape, but it is a
suspicious fact that the induction flux through the centre of a column
(of given dimensions) of the filings under a given excitation was almost
exactly the same whether the filings had been hardened or not. Two
uniform glass tubes from the same piece and practically of the same di-
mensions were filled respectively with 103 grams of untreated particles
and 96 grams of the others, and each was put several times through a
hysteresis cycle, using about 250 gausses as the intensity of the maxi-

90

PROCEEDINGS OF THE AMERICAN ACADEMY.

mum exciting field. After this 22 simultaneous determinations of H
and B were made in each half-cycle, and both cycles were carefully
plotted on such a scale that each was about 40 centimeters long. It ap-
peared that the maximum values of the induction were almost identical,
and that at no point were the plotted curves so much as 1 millimeter
apart. In filling the same glass tube a number of times in succession
from the same lot of filings, it was of course impossible to pack exactly
the same mass into the same space twice ; but the hysteresis diagrams.

E

\

D

£000

y

/

/

./

//

1500

//

//

/

//

/

' /

1000

/

'

/ /

/ /

/

/

/

/

500

/

/

/ 1

1 /

F-

'

/

1

g/

1

1

/c

K

]0

2

QO

31

DO

H

Figure 2.

many of which were obtained by Mr. J. Coulson and myself, were
always of the same shape, and the intensity of magnetization due to
a given exciting field seemed to be strictly proportional to the mass.
The density of the untreated filings was only about four tenths of that
of massive cast iron.

The demagnetizing effect of the ends in a rod of solid iron only fifty
diameters long would of course be very serious, but in the present
case, due to the relatively small value of / for a given value of //,
it is far less important. In order to determine from my observations
the permeability at the centre of an endless column of material like

PEIRCE. — PERMEABILITY OF A MASS OF FINE IRON PARTICLES. 91

mine, I have used the value of iV computed by Du Bois ^ from the
experimental results of Ewing, Tanakadat^, and himself.

Figure 2 shows half of a hysteresis diagram obtained by shearing
very slightly a diagram obtained by Mr. J. Coulson and me from a
column of untreated particles 50 centimeters long and 1 centimeter in
diameter, which weighed just over 100 grams. This diagram has all
the characteristics of the many others for which 1 have the materials.

As the figure shows, B was almost exactly 2100 for an exciting field
of 255 gausses, and this corresponds to a value for / of only about 147.
When the external field was removed, the remanent value of / was
about 20.8 ; the coercive force, however, was comparatively large,
being about 16. It is evident that the exciting field would need to
be very strong to magnetize the column of particles approximately to
saturation. The subject of the saturization of masses of iron filings
has been discussed at length by Maurain and by Trenkle.

The Jefferson Laboratory,
Harvard College.

2 Ewing, The Philosophical Transactions ; Tanakadate, The Philosophical
Magazine, 1888; Du Bois, Annalen tier Physik., 1892; "The Magnetic Circuit,"
chapter vi. For a criticism on this process, see Trenkle, 1. c.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 4. — June, 1906.

CONTRIBUTIONS FROM THE JEFFERSON PHYSiaVL LABORATORY,

HARVARD COLLEGE.

ON THE LENGTH OF THE TIME OF CONTACT IN

THE CASE OF A QUICK TAP ON A

TELEGRAPH KEY.

By B. Osgood Peirce.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE LENGTH OF THE TIME OF CONTACT IN THE
CASE OF A QUICK TAP ON A TELEGRAPH KEY.

By B. Osgood Peirce.

Presented February 14, 190G. Received March 13, 1906.

In the use of a sensitive mirror, needle, ballistic galvanometer, in
cases where a moving-coil galvanometer is objectionable, and the
familiar sliding-coil-on-a-long-magnet arresting apparatus unsuitable,
it is sometimes desirable to control the needle by currents of short
duration, sent through either a coil of the galvanometer or an auxiliary
coil, in one direction or the other, by aid of a pair of reversing keys.
The current through the controlling circuit during a comparatively
long depression of the key must be strong enough to check quickly a
large swing of the needle, and yet the operator must be able to bring
the needle practically to rest when its whole range, as measured by the
indication on its scale, is only a small fraction of a millimeter. To do
this quickly and surely requires some skill in making short key con-
tacts, as every person who has tried it knows, and different observers
find it well to use different strengths of current in the controlling cir-
cuit. In order to be able to plan wisely some apparatus, I have lately
found it desirable to learn about how short a contact the average
observer can make, either with a telegraph key or with a thimble on
the finger, and, through the kindness of a number of my colleagues
and fi-iends, I have been able to get the results given below.

The measurements were made according to a well-known principle,
by determining either the fi'actional part of the whole charge of a given
loaded condenser lost during the key contact by short circuit through
a given resistance, or the fractional part of a full charge gained by an
originally empty condenser, through a given resistance, when a fixed
electromotive force was applied during the time of closure of the key.
It is well known that with proper choice of the apparatus this proce-

96

PROCEEDINGS OP THE AMERICAN ACADEMY.

dure is susceptible of great accuracy, and that it furnishes satisfactory
means of determining the velocity of a rifle ball, or the rate of propa-
gation of an elastic wave in a bar of metal, or the time of contact of a
hammer and an anvil. Some time ago I had to measure with some care
an interval of time of about one five thousandth of a second, and to
test the apparatus, used a good number of different combinations of
condensers and resistances in the circuit, with the result that the
determinations agreed within the very small uncertainty caused by
the fact that it was difficult to be sure that the suspended system
of the ballistic galvanometer used was originally exactly at rest.

The arrangement of the apparatus for measuring the time of closure
of the key is shown schemetically in the subjoined diagram, ^repre-
sents a divided mica condenser of about 28.8 microfarads capacity;

G, a ballistic mirror galvanometer ; R, a large known resistance ; T is
the point of contact of the key with its base, or of the thimble with its
block ; P and Q are keys mounted on a large block of pai-rafine for
discharging the condenser and short-circuiting the galvanometer after
every throw. In order to make the potential difference across the open
key at all times small, the ends of the condenser circuit were attached
to two points {X, Z) in the closed high resistance current of one or
two cells, so chosen as to make the galvanometer throw, corresponding
to a complete loading of the condenser, a convenient number of centi-
meters ; the final adjustment of this throw to a predetermined value
was made by moving the scale (along a track made for the purpose)
away from or nearer to the galvanometer mirror.

It is evident that if k is the capacity in farads of the condenser,
r the whole resistance in ohms of the condenser branch circuit, and
(u -f v), of which V is the resistance of the plain conductor between
A" and Z, in the resistance of the battery circuit, then, when F and Q

PEIRCE. — TIME OF CONTACT ON A TELEGRAPH KEY.

97

are open, the charge in coulombs in the originally empty condenser,
t seconds after the key, 7", is closed, is

and Q.
so that t —

U + V

_ evk
" ~ u + v

k (uv + tir -{• V r)

u + v

'A<I^)

The values of the natural logarithms which enter into this equation
for several values of the ratio of Q^ to Q^ are as follows :

Qt/Q^-

loge[(Qoo-Qr)/<2oo]-

Qt/Qoo-

logc[(Qoo-Qr)/QooX

0.05

0.05130

0.40

0.51083

0.10

0.10537

0.45

0.59784

0.15

0.16252

0.50

0.69315

0.20

0.22315

0.55

0.79851

0.25

0.28769

0.60

0.91629

0.30

0.35668

0.65

1.04983

0.35

0.43079

0.70

1.20398

For the long scale distances actually used, the throw of the galva-
nometer caused by a discharge of electricity through its coil was, as
measured on the scale of the instrument, sensibly proportional, up to a
reading of say 25 centimeters, to the quantity of the discharge. The
galvanometer and the resistances ti and v were usually so adjusted
that a complete load (Q^) of the condenser, when sent through the
coil, caused a throw of exactly 20 centimeters. After k, u, v, and r
had been fixed, the coefficient of the logarithm remained constant ; if,
for example, its mean was 0.05, a throw of 50 millimeters would be
caused by closing the key for about 0.0144 seconds.

In order to make sure that the apparatus had been properly set up,
I made use of a body falling from rest through a measured space to
close the gap T for a short interval of calculable length. A heavy
weight sliding on a stout vertical brass rod carried with it an insulated
frame which held securely a printer's lead, which formed one terminal
of the gap T. Projecting about a millimeter from a hole in the vertical
rod, near the lower end, was a piece of sharpened drill rod which formed

VOL. XLU. 7

98

PROCEEDINGS OF THE AMERICAN ACADEMY.

the other terminal of T, and ploughed a clean furrow in the lead as the
weight, in falling, carried the lead by. In this way sure contact across
the gap could be made for a time interval, which could be varied be-
tween limits, the length of which could be computed with some accu-
racy. The agreement between the results obtained by this device and
those calculated from the electrical constants was always so close as to
lie within the uncertainty of the zero of the galvanometer.

Using the apparatus just described, a large number of trials were
made by about twenty different persons to determine how short a

TABLE I.

Observer.

B

C

D

E

F

G

11

I

J

K

Average time of
contact of key

as obtained from
all the trials.

0.0329
0.0278
0.0308
0.0223
0 0383
O.OGOO
0.0239
0.0871
0.0210
0.0239

Average time of
contact of key a.s
obtained from tlie

shorter half of
the observations.

Observer.

0.0223

L

0.0185

M

0.0202

N

0.0141

0

0.0305

P

0.0525

Q

0.0166

R

0.0788

S

0.0147

T

0.0178

Average time of

contact of key

as obtained from

all the trials.

0.0203
0.0303
O.OIGG
0.0175
0.0107
0.0277
0.0416
0.0318
0.0350

Average time of
contact of key a.s
obtained from tlie

shorter half of
the observations.

0.0130
0.0257
0.0095
0.0112
0.0050
0.0112
0.0362
0.0284
0.0280

contact each could surely make with a telegraph key or with a thim-
ble on a plate. If a telegraph key is furnished with a very stiff spring
it is possible for any one, after a little practice, to make short contacts,
not more than a thousandth of a second long, by striking the key with
the hand ; the observations recorded below were all made with a key
which had no spring, and which had to be lifted, after the contact, by
hand. It generally appeared that in the course of a long series of
trials a person made two or three contacts of abnormal length (some-
times five or ten times as long as the mean of the others), but it did
not seem well to leave them out of account ; I have, therefore, given

PEIRCE. — TIME OF CONTACT ON A TELEGRAPH KEY.

99

the average length of all the contacts, and also the average length of
the half of the whole number which were shortest. I am indebted to
Mr. John Coulson for help in making the observations.

The recorded averages are given in ten thousandths of a second, but
of course the average of two long sets of trials made by the same per-
son would not agree exactly. There is, however, in most cases, a
striking agreement between observations made at different times by

TABLE n.

u

>■

1
o

13

1

Average time of

contact of thimble

and plate as obtained

from all the trials.

Average time of

contact of thimble

and plate as obtained

from the shorter half

of the observations.

IS

>
<v

o

•6
§

Average time of

contact of thimble

and plate as obtained

from all the trials.

Average time of

contact of thimble

and plate as obtained

from the shorter half

of tlie observations.

A

Right

0.0077

0.0037

J

Right

0.0110

0.0045

B

Right

O.OOGO

0.0028

J

Left

0.013G

0.0086

C

Right

0.0083

0.0046

K

Right

0.0170

0.0062

C

Left

0.0061

0.0037

L

Right

0.0139

0.0078

D

Right

0.0126

0.0066

M

Right

0.0246

0.0035

E

Right

0.0077

0.0035

N

Right

0.0082

0.0036

E

Left

0.0062

0.0038

0

Right

0.0032

0.0022

F

Right

0.0034

0.0027

1*

Right

0.0037

0.0()32

G

Riglit

0.0217

0.0077

1'

Left

0.0110

0.0028

H

Right

0.0053

0.0032

T

Right

0.0064

0.0051

I

Riglit

0.0303

0.0083

one observer, and except in the cases of two persons whose records at
the beginning were not very good, practice did not shorten the time
appreciably. In my own case the shortest average that I have been
able to get differs from my longest by about one sixth part of the latter.
Tli£ records of thimble contacts made by two persons were 0.0036
and 0.0083 seconds in November, and 0.0037 and 0.0083 seconds in
January.

Table I shows results obtained with the telegraph key, and, though
the range is large, it appears that, when the key must be lifted away

100 PROCEEDINGS OF THE AMERICAN ACADEMY.

from its seat after the contact by the observer, tJm average person can
surely make a contact as short as a thirtieth of a second, and some can
always do better than this. Table II shows records of fair contacts
obtained with a thimble and block. While the lengths of the shorter
contacts of the average jjerson seem to be rather less — when made in
this manner — than one two hundredth of a second, three of the persons
(F, 0, P) who made trial of the apparatus could surely make contacts
the average lengths of which were only about one three hundredth
of a second.

The Jefferson Laboratort,
Cambridge, Mass.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 5. — June, 1906.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE.
E. L. MARK, DIRECTOR. — No. 179.

SOME STAGES IN THE SPERMATOGENESIS OF
THE HONEY BEE.

By E. L. Mark and Manton Copeland.

With a Plate.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE.
E. L. MARK, DIRECTOR. — No. 179.

SOME STAGES IN THE SPERMATOGENESIS OF THE

HONEY BEE.

By E. L. Mark axd Manton Copeland.

Presented May 9, 190G. Recaved May 1, 1906.

In 1903 F. Meves published a short account of spermatogenesis in
the honey bee in which it was held that the process was remarkably
unlike that of other animals, and simulated in an interesting way the
maturation of the female sexual products.

As is well known, an important parallelism between the formation of
polar cells in the maturing egg and the last two cell divisions lead-
ing to the formation of spermatozoa was established for Ascaris by
0. Hertwig, and has since been shown to be a general condition of matu-
ration throughout the animal kingdom. But while in the sexual cells
of the female maturation results in the formation of one functional and
three (or two) non-functional elements, in the male the usual outcome
is four elements, the spermatozoa, all of which are functional.

In the honey bee Meves showed that the maturation divisions of
the primary spermatocytes resulted, as in the case of the primary ovo-
cyte generally, in the production of a single functional cell, inasmuch
as there are produced from the primary spermatocyte in succession two
" Richtungskorper." However, this fundamental difference was noted :
whereas in the formation of polar cells during the maturation of the
primary ovocyte there are produced two nucleated " Richtungskor-
per," in the spermatogenesis of the honey bee only the second of the
corresponding bodies is nucleated, the first one being composed exclu-
sively of cytoplasm.

At the time I\Ieves published these observations we had already
begun the study of the germinal cells in the male honey bee, and hav-
ing now arrived at somewhat different conclusions from those set forth
by him, will give here a preliminary account of our results thus far,
the intention being to publish later a more detailed and comprehensive
paper on the subject.

104 PROCEEDINGS OF THE AMERICAN ACADEMY.

In the final generation of spermatogonia in the honey bee there is at
the apex of each conical cell a spheroidal, nearly homogeneous body,
which represents the remnants of the interzonal filaments of the pre-
ceding cell division. These bodies are stained black in iron haema-
toxylin, and on being washed out assume a characteristic yellowish
gray color. Since they are admittedly the metamorphosed remnants
of filamentous structures first named by Mark ('81, pp. 198, 539) inter-
zonal filaments, we shall henceforth speak of them as the Interzonal
bodies. The interzonal body is identical with the " Zellkoppel " of Paul-
mier ('99, p. 228), to which Prowazek (:01, p. 201) has given the name
" Spindelrestkorper." It is to be noted that the term " Zellkoppel "
was used by Zimmermann ('91, p. 189), who introduced the name
into cytology, with a somewhat diiferent meaning from that employed
by Paulmier. This is in itself a reason for applying another name —
interzonal body — to this structure.

At the end of the growth period, which follows the last spermato-
gonial division, the cells have increased greatly in size and have be-
come in general spherical, a form which is more or less modified by
the mutual pressure of the closely packed elements. At this stage
(Figure 1) the interzonal body {x) is clearly visible, and is in contact
with the cell membrane. Meves shows it in his Figure 1, but makes
mention of it neither in his explanation of the figure nor in the accom-
panying text.

The first evidence of spermatocyte division is seen when the centro-
some, which lies in contact with the cell membrane, divides and the two
daughter centrosomes move apart along the periphery of the cell. The
centrosomes during their migration appear to exert a marked influence
on the form of the cell, which exhibits two more or less conspicuous
elevations, the apex in each case being occupied by one of the centro-
somes. Figure 2 represents a fairly early stage in the migration of the
centrosomes and shows clearly the marked change in the form of the
cell due to their presence. The distance between the two centrosomes
increases until these ultimately arrive at opposite poles of the cell
(Figure 3). Up to this time each centrosome seems to have exer-
cised nearly the same amount of influence as the other in modifying
the form of the cell ; but from this time forward the influence of one is
seen to predominate over that of the other, until at length (Figure 4)
one end of the cell is drawn out into a long, slender, slightly tapering,
finger-like process, at the tip of which is located the centrosome.
This centrosome will be designated as the proximal one, the other as
the distal centrosome.

The choice of these designations rests on a later condition in the

MARK AND COPELAND. — SPERMATOGENESIS OF THE HONEY BEE. 105

arrangement of the spermatocytes. These become grouped in the cyst
in a radial manner with their interzonal bodies clustered at the centre,
very much as the spermatogonia are arranged in their follicles, l^his
constant orientation of the cells in relation to the cluster as a whole
makes it possible to use without ambiguity the terms proximal and
distal.

The nucleus, which hitherto has been near the centre of the sper-
matocyte, now changes its position, migrating to the distal end of the
cell ; it generally comes to lie close to the corresponding centrosome.
Coarse fibres, which stain deeply in iron haematoxylin, now make their
appearance, extending from the distal centrosome around the nucleus
to the region of the proximal centrosome. At this time the finger-like
process terminating in the proximal centrosome may be reduced to
a very narrow cytoplasmic stalk (Figure 4), so that it is difficult to
observe whether the fibres at this stage actually reach the centrosome
or not. It is, however, probable that they do, as they may be traced
for some distance into the base of the finger-like projection.

Changes, which we shall not attempt to describe here in detail, have
meantime taken place within the nucleus. The chromatin passes
through a spireme stage and gives rise — apparently by segmentation
and a concentration of the segments — to sixteen double, dumb-bell
shaped chromosomes (Figure 5), which lie in rather scattered positions.
The bivalent structure of the chromosomes becomes less conspicuous
when, a little later, the nucleus enters on the metaphase.

At about this stage the nucleus elongates, first in the direction of
the distal end of the cell (Figure 7), and later at the opposite end, until
finally it becomes spindle shaped, extending more or less completely
from pole to pole (Figure 8). At the time of nuclear elongation
a few thick, deeply staining intranuclear-spindle fibres are seen con-
necting the chromosomes with the distal centrosome, and later, as the
nucleus increases in length, similar fibres also run to the proximal
pole of the cell. These fibres are clearly separate from one another
in the region of the chromosomes, but as they approach the centro-
somes they seem to coalesce, until it is impossible to make out
separate elements. In the cell represented in Figure 8, a bundle of
fibres is traceable fi'om the chromosomes to the distal centrosome, and
on the opposite side of the chromosomes a bundle may be followed for
some distance into the base of the finger-like process which terminates
in the proximal centrosome. In other cases the nucleus, although
much attenuated at the poles, has been clearly seen to stretch from one
centrosome to the other, the chromosomes being midway between
the two centrosomes. I find nothing to corroborate the condition

106 PROCEEDINGS OF THE AMERICAN ACADEMY.

shown by Meves in bis Figure 2, wbere the elongated nucleus with its
contained spindle figure is entirely isolated from the two centrosomes
of the cell. Apparently he has overlooked the fibrous prolongations
which connect the ends of the spindle with the centrosomes. The
coarse, granular, extranuclear fibres already referred to are still to be
seen occupying the greater part of the cell, extending in somewhat
irregular sinuous courses outside the nucleus firom pole to pole.

The mitotic figure here described is evidently that of the first
spermatocyte division ; but now a peculiar phenomenon occurs.
Instead of a division of the chromosomes taking place, as would be
expected, the figure does not for the present progress beyond the
beginning of the metaphase. The spindle fibres either break down,
or, what is more likely, become closely pressed together into a single
bundle ; but the chromosomes maintain their form for some time. A
cross section through the middle of the spindle at this stage (Figure G)
shows the chromosomes still surrounded by a nuclear membrane, and
likewise the cut ends of the cytoplasmic fibres lying outside that
membrane.

The interzonal body persists throughout the period of the nuclear
changes last described without any apparent alteration in form or size,
but toward the end of this period it has a position at, or very close to,
the proximal end of the cell, and soon afterward it is found directly
beneath the proximal centrosome. Eventually it occupies the base of
the finger-like process of cytoplasm (Figure 9) previously described.
There is some variation in the sequence of phenomena during this
period. As early as the stage shown in Figure 7, the centrosome and
the interzonal body are sometimes seen closely applied to each other,
while in other cases at a much later stage in the nuclear metamorphosis
(Figure 9) a portion of the finger-like process may still be seen between
the two. At length the interzonal body occupies the place of the
finger-like process of cytoplasm and protrudes from the main body of
the cell (Figure 10), the centrosome continuing to occupy its former
position at the proximal end of the projection. At this stage the in-
terzonal body is a spherical object supported on a cylindrical process
of the cell, and resembles superficially the first polar cell formed
during the maturation of eggs ; but it differs from the polar cell in
obvious particulars. Not only is it destitute of visible chromatic
substance and the usual remnants of interzonal filaments, but it
exhibits from the beginning a fairly well-defined outline on the side
toward the body of the cell. Except for the persisting centrosome,
its substance is homogeneous and slightly more refi"active than the
neighboring cytoplasm.

MARK AND COPELAND. — SPERMATOGENESIS OF THE HONEY BEE. 107

During the migration of the interzonal body into the finger-like cell
process, other portions of the cell undergo conspicuous changes. The
extranu clear fibres which, in the earlier stages, extended from the
distal centrosome around the nucleus and the interzonal body to
the proximal centrosome, have now increased in number, and crowd
upon the nucleus. The latter continues to change in form and size ;
it becomes considerably flattened and much smaller. The chromosomes
are crowded together so that they often appear (Figure 10) as a single
deeply staining mass, generally much nearer the proximal than the
distal end of the cell, and sometimes actually in the projection of the
cell close to the interzonal body. Careful decolorizing at this stage
reveals the chromosomes in the form of dyads, with possibly an actual
separation of the dyads into their components. This perhaps repre-
sents what Meves describes as the breaking up of the chromosomes
into granules.

Soon after this the cylindrical process of cytoplasm connecting the
interzonal body with the main portion of the cell becomes elongated
and more attenuated. Eventually it assumes a slender neck-like fonn,
and then by rupturing, effects a complete detachment of the interzonal
body from the spermatocyte (Figure 11). The region of greatest at-
tenuation and final rupture is such that a small, though possibly
variable, amount of undifferentiated cytoplasm is cut off with the
interzonal body. The r61e of this body in spermatogenesis is now
finished ; apparently it gradually diminishes in size (Figure 15), and
ultimately disappears entirely.

The extranuclear fibres, which were well developed as far back as
the stage represented in Figure 4, are possibly concerned in some way
with the elimination of the interzonal body ; they are at no time con-
nected with any chromatin, and yet they are as large and stain as
deeply as the fibres within the nucleus. They persist and are to be
recognized in the cell throughout the succeeding division.

At about the time of the detachment of the interzonal body the
nuclear membrane disappears and the spindle presents a form resem-
bling that which usually characterizes such a structure. The chromo-
somes are now seen to be in the metaphase (Figure 11), having
returned to the condition which they exhibited immediately before
the elimination of the interzonal body.

The history of the nucleus during the elimination of the interzonal
body is hard to trace and difiicult to interpret. Meves states that,
after the formation of a spindle figure inside the persisting nuclear
membrane, with sixteen chromosomes irregularly arranged at the
equator, there is no further progress ; that, on the contrary, the chro-

108 PROCEEDINGS OF THE AMERICAN ACADEMY.

mosomes remain clustered together in one place, and finally break up
into granules ; and that the spindle fibres are converted into a net-
work. While we agree with the main point implied in this description,
— viz., that the chromosomes do not separate into two groups repre-
sentative of two daughter nuclei, — our observations lead us to think
that the nuclear matter does not pass through a true reticular stage.
For the chromosomes retain more or less distinctly their individuality,
and the spindle fibres do not seem to take on the reticulate condition,
but rather, to become confluent into a smaller number of strands.
Whatever may be the method of its formation, however, the spindle
and its chromosomes present almost exactly the same conditions
immediately after the elimination of the interzonal body that they did
just before that event. We have found, then, in our material no evi-
dence of a typical prophase leading up to the formation of the
spindle which is connected with the production of the second (the
nucleated) bud.

During the period intervening between the formation of the first and
second buds the centrosomes sometimes present a condition that may
have a bearing on the interpretation of the process we are dealing with.
Either the distal or the proximal centrosome, or rarely both, becomes
elongated in a plane perpendicular to the axis of the spindle (Figures
10, 11), and in some instances a constriction divides it more or less
completely into two bodies.

When the interzonal body has been detached, the spindle figure
again assumes the condition characteristic of a nucleus in the meta-
phase ; its cross section becomes greater, and the chromosomes, six-
teen in number, immediately undergo division. The small daughter
chromosomes, of the same size as each of the components of a dyad
previously described, migrate to the poles of the spindle, leaving
stretched between them interzonal filaments, which stain in iron
haematoxylin like the spindle fibres. Nearly up to the stage repre-
sented by Figure 12, nothing suggests an unequal division of the cell ;
but as soon as the chromosomes arrive at the poles of the spindle the
proximal end of the cell elongates and the chromosomes appear as a
deeply stained mass at the apex of a second finger-like process of
cytoplasm. The chromosomes at the opposite pole become surrounded
by a membrane, thus giving rise to a small typical nucleus. Between
these two nuclear bodies are seen the interzonal filaments together
with remnants of the more peripheral fibres already described in
connection with the account of the elimination of the interzonal body.
The finger-like process at the proximal end of the cell with the nuclear
mass at its tip continues to elongate (Figure 14), and eventually its

MARK AND COPELAND. — SPERMATOGENESIS OF THE HONEY BEE. 109

terminal part, containing the chromatin, is detached in the form of a
very small cell, — much smaller, indeed, than the interzonal body pre-
viously set free. We have called this a cell, though it is difficult to
determine how much, if any, undifferentiated cytoplasm is cut off with
the nuclear matter. This, however, is a difficulty which is often en-
countered in studying the polar cells formed during the maturation of
eggs, and does not in our opinion preclude the use of this designation.
When fully separated from its sister cell, this small cell assumes a
spherical form and increases in size. The nucleus of the larger cell,
the spermatid, likewise increases in size and becomes to all appear-
ances the counterpart of the detached polar cell. Figure 15 represents
the two cells at this stage, and it also shows the previously eliminated
interzonal body, now much diminished in size. The chromatin in
both nuclear bodies becomes variously aggregated, but assumes in
general a peripl 3ral position ; the metamorphosis of the larger cell
— the spermatid — now begins.

Meves in his description of the first "Richtungskorper" is evidently
dealing with what we have called the interzonal body, the peculiar
history of which has been briefly described. If this so-called bud
were in truth made up simply of undifferentiated cytoplasm, as Meves
leads us to believe, perhaps one would be justified in considering it a
rudimentary spermatocyte of the second order, even though it con-
tained no chromatin. But if it is composed of the remnants of the
interzonal filaments, which have become metamorphosed into a definite
body within the cell, and is surrounded by only the slightest amount
of undifferentiated cytoplasm, if any, it is difficult to find any sufficient
basis for homologizing it with the first spermatocyte division of typical
spermatogenesis. Moreover, such a casting forth of spermatogonial
spindle remnants has already been observed in cases where four
functional spermatids are formed in the normal way, and where, conse-
quently, this elimination of interzonal matter can have nothing to
do with the first spermatocyte division. Paulmier ('98, p. 228) has
described such conditions in Anasa tristis in the following terms : " At
the tip of the resting cell [spermatogonium] is a structureless mass
which is formed from the remains of the intermediate spindle fibres
[interzonal filaments] of the preceding division." Further on he adds,
" As a group of chromosomes approaches the end of its movement the
cell loses its conical shape and becomes more cylindrical, and the
Zell-Koppel [interzonal body] of the preceding generation is cast
off, remaining for a time as a small isolated mass, which ultimately
disappears." Blackman (■• 05, p. 37) likewise describes a somewhat

110 PROCEEDINGS OF THE AMERICAN ACADEMY.

similar phenomenon in the male germ cells of Scolopendra, where the
spindle remnants of both the first and the second spermatocyte
divisions are eliminated during a rotation of one daughter cell upon
the other.

It seems possible, therefore, that this globule, composed principally
of the substance of the interzonal filaments, is not comparable with the
spermatocyte of ordinary spermatogenesis, and therefore not with a
polar body in ovogenesis.

The smaller of the two bodies resulting from the real mitosis which
follows the elimination of the interzonal body bears a striking resem-
blance, it must be admitted, to the polar cell of eggs, and it is un-
questionably the result of a true, though modified, cell division.
This phenomtnon seems, however, never to have been seen in the
spermatogenesis of any other animal. There is here an equal division
of chromatin accompanied by a very unequal division of the cytoplasm,
precisely as in the formation of the polar cell in eggs. The small cell
apparently begins to undergo a metamorphosis parallel to that of its
larger sister cell, as Meves has maintained. Although Meves believes
that the small cell eventually degenerates, positive evidence of this
has not yet been produced. If it is to be interpreted as the homo-
logue of a polar cell, the question at once arises. Which of the two
polar cells usually produced does it represent 1 From the standpoint
of Meves, the first body might be looked upon as a partially abortive
attempt to produce the equivalent of the first polar cell, and the
second body might then be regarded as in some sense the equivalent
of the second polar cell ; but even were his view about the first (inter-
zonal) body correct, the division of nuclear substance accomplished by
the formation of the second bud would more strongly point to this,
rather than the first, as being the homologue of the first polar cell.
That view is, perhaps, strengthened by the facts here presented, which
tend to show that the body first produced has nothing whatever to do
with cell division, and that in the occasional doubling of the centro-
some (Figures 10, 11) some progress is made toward a second cell
division, which, if completed, would result in the formation of either
two spermatids or a second true polar cell. However, it must be
admitted that, on the assumption that the interzonal body has nothing
to do with an attempted cell division, the peculiar changes passed
through by the chromatin preceding and during the period of the
elimination of that body remain unexplained and without a parallel.

On the other hand, the beginning metamorphosis of the small
nucleated body (second bud) suggests that it is the equivalent of a
spermatid rather than a spermatocyte of the first order, and this view

MARK AND COPELAND. — SPERMATOGENESIS OF THE HONEY BEE. Ill

is strongly supported by the statement of Meves that in Vespa ger-
manica the cell division corresponding to this results in the production
of two spermatids of equal size.

Bibliography.

Blackman, M. W.

:05. The Spermatogenesis of Myriapoda. III. The Spermatogenesis of
Scolopendra heros. Bull. Mus. Comp. Zool. Harvard Coll., Vol. 48,
No. 1, pp. 1-138, 9 pi., 9 fig.

Mark, E. L.

'81. Maturation, Fecundation, and Segmentation of Limax carapestris,
Binney. Bull. Mus. Comp. Zool. Harvard Coll., Vol. 6, pp. 173-625,
5 pi.

Meves, F.

:03. Ueber " Richtungskorperbildung " ini Hoden von Hymenopteren.
Anat. Anz., Bd. 24, pp. 29-32, 8 Fig.

Paulmier, P. C.

'99. The Spermatogenesis of Anasa tristis. Jour. Morph., Vol. 15, Suppl.,
pp. 223-272, 2 pi., 6 fig.

Prowazek, S.

:01. Spermatologische Studien. Arb. Zool. Inst. Wien, Bd. 13, pp. 197-
236, Taf. 11 u. 12, 2 fig.

Zimmermann, K. W.

'91. liber den Kernteilungsmodus bei der Spermatogenese von Helix
pomatia. Verb. Anat. Gesell., Bd. 5, pp. 187-193.

EXPLANATION OF PLATE.

All figures were drawn with the aid of a camera lucida and are magnified
2073 diameters.

Figure 1. Primary spermatocyte, resting stage.

Figure 2. Primary spermatocyte ; tlie two centrosomes moving apart.

Figures. Primary speruiatocyte ; the centrosomes have arrived at opposite
poles of cell.

Figure 4. Proximal fiiiger-like process of the cell, terminating in the proximal
centrosome ; from the distal centrosome extend prominent extranuclear fibres.

Figure 5. Nucleus of primary spermatocyte, sliowing sixteen dyads.

Figure 6. Cross section of a primary spermatocyte in the same stage as that of
Figure 9.

Figure 7. Elongation of the nucleus toward the distal centrosome.

JiGURE 8. The nucleus exhibits a spindle-shaped elongation, and intranuclear
spindle fibres are established.

• Figure 9. The interzonal body has migrated to the base of the finger-like
process.

Figure 10. The interzonal body in the course of being constricted off from
the cell.

Figure 11. The interzonal body is detached, and there is a typical spindle in
the beginning of the metaphase.

Figure 12. Late anaphase.

Figure 13. Finger-like process surmounted by chromatin of polar cell.

Figure 14. Chromatin of finger-like process nearly detached from the process.

Figure 15. Spermatid, interzonal body reduced in size, and polar cell.

Mark AND Copeland— Spermatogenesis Honey Bee.

M. COPELAND DEL.

Proc. Amer. Acad. Arts and Sciences. Vol. XLII,

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 6. — July, 1906.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

FRICTION AND FORCE DUE TO TRANSPIRATION
AS DEPENDENT ON PRESSURE IN GASES.

By J. L. Hogg.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY

OF HARVARD COLLEGE.

FRICTION AND FORCE DUE TO TRANSPIRATION AS
DEPENDENT ON PRESSURE IN GASES.

By J. L. Hogg.

Presented by J. Trowbridge, November 8, 1905. Received April 6, 1906.

Problem in General and Results in General.

This is a preliminary paper on an investigation whose object is
threefold.

It is known that at pressures lower than about 1 cm. of mercury
the resistance which a solid body meets in passing through a gas is
noticeably smaller than it is when the pressure is that of an atmos-
phere. This is because the phenomenon of slip presents itself at the
low pressures. The first object of the investigation is to study fully
the relation between the friction of a gas on a solid body and the
pressure in the gas at those pressures where slip is appreciable.

Again, it is known that, if a given volume of gas is divided into two
portions by means of a partition one side of which is kept hotter than
the other, and if a small opening of any form be made in the partition,
the gas will flow from the cold side to the hot side of the partition until
there is an excess of pressure in the chamber contiguous to the latter.
This excess of pressure depends on the difference of temperature of the
two sides of the partition and on the mean pressure.

The second object is to examine in a particular simple case the
relation between the force on the partition (called the transpiration
force), resulting from this flow of gas towards the hot side of the parti-
tion, and the mean pressure in the gas.

The third object of the investigation is to examine the feasibility of
measuring the pressure in a gas when either of these relations is known
without having recourse to the McLeod gauge. That this third object
is by no means the least significant will appear when the evidence as to
whether the McLeod gauge is reliable for the measurement of small
pressures is adduced.

116 PKOCEEDINGS OF THE AMERICAN ACADEMY.

The progress made in the solution of these problems up to the
present may be summed up as follows :

(1) The great difficulty in devising and carrying out methods of con-
structing the pieces of apparatus required has been overcome. This,
which was by no means the least difficulty encountered, can be appre-
ciated only when one knows the form of the apparatus required, and
the treatment which the apparatus must receive in order that all traces
of moisture may be removed from all the solid surfaces exposed to the
interior of the containing vessel.

(2) The friction has been measured at pressures ranging from that
of an atmosphere to 0.00024 mm. of mercury, the small pressures being
measured by the McLeod gauge. Figure 6, in which ordinates are
proportional to friction and abscissas proportional to pressure, shows
how the friction diminishes as the pressure diminishes. The curve,
whose error is certainly less than one per cent (if the McLeod gauge
can be considered trustworthy over the range of pressures indicated),
is very regular; and a discussion of the numerical results in that
part of the curve which corresponds to pressures above 0.1 mm. of
mercury shows that the law

[tz:T-']^' = ''

first deduced by Kundt and Warburg for pressures down to 0.6 mm.,
holds very well down to about 0.1 mm. Beyond this point, however,
the theoretical curve, i. e., the curve obtained by calculating p from the
above relation after the constants have been determined from obser-
vations at comparatively large pressures, does not coincide with the
actual curve.

(o) The force due to transpiration has been measured over a range
of pressure varying from 1.42 mm. to 0.0093 mm.

(4) Figure 7 (the error in the curve may very well be five per cent),
in which the ordinates are proportional to the transpiration force and
abscissas to pressure, shows that, for pressures below that for which
the force is a maximum, the relation between the force and the
pressure rapidly approaches a relation of mere proportionality, or
at worst a proportionality disturbed by a constant term. In other
words, the curve becomes a straight line passing very nearly through
the origin.

hogg. — friction and force due to transpiration. 117

Problem in Detail.
Introduction.

Aside from the interest which attaches itself to an investigation of
the law relating viscosity to pressure at low pressures, the advantage
of being able to measure gas pressure by measuring the friction of the
gas on a pendulum is apparent. By this method the state of the gas
remains unchanged during the time the measurement is in progress,
while by the method of the McLeod gauge the gas must be compressed
in order that the pressure may be measured. It is, however, beyond
doubt very important that in establishing a method of gas pressure
measurement by friction, or otherwise, a second method should if
possible be obtained to serve as a check upon the one which we may
consider most convenient and therefore the most desirable. Though
the investigation of the law relating pressure in a gas to transpiration
force when the transpiration space is of special form is interesting and
important for its own sake, yet additional interest and importance is
imparted to it when the possibility of making its results serve as the
desired check upon the proposed friction method of measuring gas
pressure is considered.

Thus, in so far as the object of the present investigation is to test or
replace the McLeod gauge, the function of what has been called the
transpiration apparatus is to serve as a check upon the results of
pressure measurement obtained by the viscosity apparatus. As will
appear in the sequel, the problem to be solved with the transpiration
apparatus is that of investigating the law of gas action on a radiometer
vane of special form surrounded by a containing vessel whose parts are
symmetrically placed with respect to the vane.

That at least another attempt should be made to decide the question
as to how much reliance can be placed on the McLeod gauge for meas-
urement of pressures below 0. 1 cm. is very forcibly brought home to one
who examines the conflicting evidence of high authority.

The attempts to investigate the behavior of the gauge when the vacua
are high, have as a rule been made, not with the avowed intention of
testing the gauge, but with the object of testing the validity of Boyle's
law at various pressures, any departure from which for any gas would
at once limit the use of the gauge for that particular substance. The
method used was to enclose a certain quantity of gas, measure accu-
rately its volume and its pressure, calculate /? ?; ; change this volume,
and therefore pressure ; measure again, and so on. The various values
oi pv thus obtained should be the same, that Boyle's law may be
obeyed, and hence that the principle of the gauge may be sound.

118

PROCEEDINGS OF THE AMERICAN ACADEMY.

Siljestrom^ found departures from the law in the case of air and
oxygen. Amagat^ found the law obeyed, while Bohr^ found an
anomaly in the case of oxygen at 0.7 mm. pressure. In the curve
representing |> v plotted against p there is a sudden drop at this pres-
sure. Batelli's* experience corresponds well with that of Bohr. At
0.7 mm. with oxygen there is departure, while with air the departure
is at pressures between 2 mm. and 5 mm. Carbon dioxide departs from
the law, while hydrogen is found to obey it from one atmosphere to
0.002 mm. Baly and Ramsay ^ have pronounced the gauge worthless for
oxygen, while the results given for hydrogen are said to be reliable.

Lord Rayleigh,^ working with values of p ranging from 1.5 mm. of
mercury to 0.01 mm., found no evidence of any anomaly with oxy-
gen, nitrogen, or hydrogen ; while at pressures ranging from 75 mm. to
150 mm. he found the law fully obeyed.

There is, then, conflicting evidence, with much in favor of irregularity.

Although with the gauge which Rayleigh employed in his investiga-
tion one can measure, with an accuracy of about five per cent, pressures
of 0.01 mm. of mercury, yet for pressures which in many cases must be
measured, this method is not sensitive enough, and then one is forced
back upon the use of the McLeod gauge, and that in a region where we
know nothing of its action.

We are indebted to Sutherland 7 for the suggestion that the lowest
pressures may possibly be measured by measuring the friction of the
gas on a pendulum at pressures where the phenomenon of slip can be
detected experimentally. Having had some experience in determining
the absolute value of viscosity in gases, I have undertaken to investi-
gate the whole subject.

As has been stated at the beginning of this paper, the problem
involves the solution of two others, which will now be discussed in
detail.

The Friction Prohhm.

When a gas flows over a solid surface at a uniform rate, or a solid
surface is made to move through a gas with uniform velocity, there is
brought into play a resistance to the motion due to friction. If, for
example, we have two parallel planes placed in a mass of gas at, say,
unit distance apart, and, while keeping one fixed, we cause the other to
move in a certain direction in its own plane, a certain force must be

1 Pogg. Ann., 151, 1874.

3 Wied. Ann., 27, 1880.

6 Phil. Mag., 38, 18iH.

f Phil. Mag., [5], 43, 1897.

2 Ann. de Chim. et Phys., 28, 1883.
* Phys. Zeits., 3, 1901.
Phil. Trans., 196, 1901.

6

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 119

continually applied in the direction of motion in order that a uniform
velocity may be maintained. That is, during the motion there is a
certain tangential stress exerted by the gas on the solid which opposes
the motion of the solid. If the layer of gas which is in contact with the
moving plane moves with the same velocity with which the solid moves,
the tangential stress between the gas and the solid, that is, the resist-
ance experienced by the solid, must depend upon the force required to
cause one layer of the gas to move with a certain velocity relative to the
next layer. Experiment shows that the relative velocity of contigu-
ous layers is a measure of the tangential force. If, however, the solid
and the gas in contact with it do not move together, then, for the same
velocity of the moving solid, the velocity of a layer of gas relative to
its contiguous layer is less than before, and hence the friction between
them is less, and therefore the stress at the solid is less. In the case
considered, when the moving plane and the layer of gas next to it move
together the force per square centimeter of the plane necessary to keep
up a uniform velocity of one centimeter per second in the given direction
is the coefficient of viscosity or internal friction. If the moving plane and
the layer of gas next to it have not the same velocity, the gas is said
to slip on the solid. The force per unit area of the plane which must
be applied in a given direction in the plane to maintain a uniform rela-
tive velocity between the plane and the layer of gas is proportional to
this relative velocity. When the relative velocity is one centimeter
per second the force required is the coefficient of external friction.

Maxwell showed that the internal friction of a gas is constant for
pressures varying from atmospheric to one sixtieth of atmospheric
pressure. In his paper ^ he defines the coefficient of slip to be the
ratio /a/o", where /x is the coefficient of viscosity of the gas, and o- the
coefficient of external friction. The coefficient of slip is then a quan-
tity which decreases as o- increases and ft decreases, and which increases
as o- decreases and /x increases. In order that there should be no
sHpping, o- must be infinitely great compared with fx. As this is
probably never the case, there is some slip under all circumstances.
Maxwell also showed that when the conditions are such that slip must
be considered, the resistance to the moving solid in the foregoing dis-
cussion is the same as it would be were the fixed surface removed a
distance 2 /3 farther from the moving surface where /3 is the coefficient
of slip.

A consideration of Figure 1 will probably help to make the motion of
the gas between the planes better understood in the case where slip

* Sci. Papers, 2, 1.

120

PROCEEDINGS OF THE AMERICAN ACADEMY.

must be considered as well as in the case where it is negligible. Let
AB represent the section of the fixed plane just considered by the
plane of the paper. Likewise, let C D represent the similar section of
the moving plane. Let the moving plane have a velocity of one cen-
timeter per second in the direction C D, and let the distance between
the planes be one centimeter. If the layer of gas next to the solid
moves with the same velocity with which the solid moves, the line of
particles represented by X Y at the beginning of any second will, if
X 0 equals X Y, be represented by X 0 at the end of this second.
That the particles will at the end of the second lie in the line X 0 is
seen by considering the forces acting on any layer of the gas between
the planes and parallel to them. The layer above the one in question
exerts a tangential force on the latter which tends to move it in the direc-

/

V

c

X

x'/ /

0

A.

Y

y

/

D

B

Figure 1.

tion C D, but the layer below it holds it back with a force just equal
to this. Otherwise there would be a net constant force acting on the
layer parallel to C D, which would produce an acceleration. Clearly
there can be no acceleration of the layer while the moving plane
maintains its uniform velocity. Moreover, since action and reaction
are equal, the layer which is tjius holding back the layer above it is
being dragged forward with the same force. It in turn exerts the
same forward force on the next succeeding layer, and so on. It thus
appears that the force exerted by the layer of gas next to the fixed
solid, AB, in the direction AB, is just the same and in the same
direction as that exerted by any layer of gas upon that layer just be-
neath it ; and also that the force with which the fixed solid resists the
motion of the gas is the same as the force with which any layer resists
the motion of the layer above it. Clearly, a similar statement may be

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 121

made regarding the resistance which the gas in contact with the solid,
C D, offers to the motion of C D. Under these circumstances, in any
second, any one layer must move with respect to the next layer helow
it exactly the same distance which the one above it moves with respect
to the layer in question. It follows, then, that the line of particles,
X Y, at the beginning of a second will become the line X 0 at the end
of that second.

If, however, the solid and the gas in contact with it have different
velocities, that is, if the gas slips on the solid, the line X' Y' wiU rep-
resent the position of the line X Y at the end of the second. It is
clear from the figure that if we remove the planes farther from each
other by the distance 0 P plus Y P', that is, twice 0 P, and assume
that there is no slipping at the surface of the solids, then, since the
relative positions of the successive layers are unaltered, the friction be-
tween contiguous layers of gas, and therefore the tangential stress on
the solids will be the same as it is where there is slipping and where the
planes are at the original distance X Y from each other.

That the distance 0 P is, as Maxwell showed, equal to /u,/o-, is readily
seen. For, if we assume that the surfaces of the fixed and moving
solids are alike, o- will be the same for both. If, also, we call the dis-
tance Y Y', or X' 0, X, the tangential stress at either solid must be
(Tx, since x is the velocity of CD relative to the gas in contact with
it, and also the velocity of the gas in contact with A B, relative to
A B. But the stress between consecutive layers is, since the distance
between the planes is one centimeter, equal to yu, (1 — 2 .r), and we have
seen that this is the same as the stress at the solid. We have, then,

<TX = ^ (\ — 2x)

or, X =

(TX

2/A -f o-

(T fX.

2/-(. -j- o-

= the force at the solid.

But the form of this result shows that this is the force which must be
applied to the solid, C D, to maintain a velocity of one centimeter per
second if the distance from the fixed solid is (2 /u/cr-f 1) and there is

122 PROCEEDINGS OF THE AMERICAN ACADEMY.

no slipping. If there is no slipping, then, in order that the stress at
the solid should be the same as when there is slipping, namely a-x, the
distance between the planes must be increased by 2 ju/o-, that is, twice
the coefficient of slip as defined by Maxwell. In the figure, then, the
distance 0 P is equal to /a/o-.

The investigation of the law of friction on a body at pressures smaller
than those at which Maxwell worked was taken up by Kundt and
Warburg,^ but without adequate means of measuring pressure. They
verified Maxwell's law, and concluded, both on theoretical grounds and
from their experimental data, that over a certain range of pressure the
coefficient of slip varies inversely as the density of the gas, and there-
fore, so long as Boyle's law holds, it varies inversely as the pressure.
Sutherland ^^ reached the same conclusion by a different method. If this
is true and /x is constant, then o-, as defined above, must be proportional
to the pressure. When the density of the gas has been so far reduced
that the molecules seldom collide in passing from one solid surface to
the other, then the friction is largely superficial or external, and one
would expect that at less densities the resistance offered to the
movement of the solid body would be well-nigh proportional to the
pressure. ^^

Maxwell's viscosity apparatus consisted, essentially, of a disk of glass
suspended with its plane horizontal and between two other larger fixed
parallel disks of glass. The middle disk performed oscillations in its
own plane. When the distance D, between the fixed and moving sur-
faces is small, Maxwell's formula for this apparatus becomes

X-^=^ (I)

Where X is the total logarithmic decrement,

K is that due to the friction in the suspending fibre, and is a
constant.

/A is the coefficient of viscosity of the gas.

Z>, the distance between fixed and moving surfaces,

c, a proportionality factor.
This is the formula only when slipping is not taken into account.
When slipping must be considered, as has been said above, the fixed
and moving surfaces may be considered removed fi-om each other by a
distance 2 /?, where /? is the coefficient of slip.

9 Wicd. Ann, 158, 1876.
" Phil. Mag., [f,], 43, 1897.
" Kundt and Warburg, Wied. Ann., 158, 1876.

HOGG. — FRICTION AND FORCE DDE TO TRANSPIRATION. 123

In that case equation (I) becomes,

where

I is the total decrement at a lower gas pressure, and the other
quantities have the same significance as before.
Now, on dividing (I) by (II),

X-K _D + 2p
l-K~ D

P

since /? is inversely proportional to jy. This equation may be written
in the form

This equation is deduced by Sutherland ; and it is also of the form of
that used by Kundt and Warburg in their investigation to verify their
theoretical conclusion that the coefficient of slip varies inversely as the
pressure. As has been said, however, they were unable to measure
the lower pressures, and so the law was not submitted to a test at very
low pressures.

The relation between pressure and logarithmic decrement expressed
here is the one utilized by Sutherland ^^ to determine p after the con-
stants in the foregoing equation have been determined. The data for
this purpose he found in Crookes' paper on ' Viscosity of Gases at very
High Exhaustions.' There the logarithmic decrement of a vane of mica,
suspended with its plane vertical, and performing oscillations about a
vertical diameter, is given for pressures ranging from that of an atmos-
phere to 0.02 million ths of an atmosphere. The pressure was measured
by a McLeod gauge. Sutherland's formula applied to these results
gave very good agreement from about 0.2 mm. to about 0.01 mm. in
the pressure as measured by the gauge, and the pressure as calculated
from the formula. Below 0.01 mm. the agreement was not good.

Stokes 13 has shown that, in this apparatus, the coefficient of viscosity
is not proportional to the logarithmic decrement, and therefore, as

" Phil. Mag., [5], 43, 1897.

" Note added to Crookes* paper.

124

PROCEEDINGS OF THE AMERICAN ACADEMY.

FIG. 2

Sutherland has pointed out, a
fairer test of the correctness of
(III) might be made with a
viscosity apparatus like that
for which the formula was de-
duced.

This suggestion has been fol-
lowed in the construction of the
instrument whose description
follows.

Viscosity Apparatus — De-
scription. — The viscosity appa-
ratus used in these experiments
consists of two circular glass
plates 8.2 cm. in diameter and
0.3 cm. thick (A, Figure 2).
They are pierced by a hole in
the centre 0.3 cm. in diameter,
and by three holes near the
edge, equally spaced, and 0.15
cm. in diameter. Through the
latter are passed small threaded
platinum bolts, provided with
nuts, for the purpose of binding
the plates together. In order
that the latter may be fixed at
a certain distance apart, they
are separated by three short
glass tubes, through the bore
of each of which passes one
of the aforesaid bolts. These
glass tubes are ground to the
same length, 0.35 cm.

These are the two fixed plates
in Maxwell's apparatus, while
between them, concentric with
them, and parallel to them, is
suspended the vibrating disk,
which consists of a plate of glass
4.4 cm. in diameter and 0.09
cm. thick. It has a hole in

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 125

the centre about 0.075 cm. in diameter, through which passes the
closely fitting supporting wire, B, Figure 2. The latter is provided
with a hard-soldered shoulder, against which the plate is clamped
by means of the nut below. Platinum foil washers are placed between
the glass and the nut. On the supporting wire at C are fixed three
feet, long enough so that, if the swinging plate were lowered, they
would reach the upper surface of the upper plate just before the
suspended plate could touch the lower plate. This is a measure of
safety, as will be seen when the process of making and suspending
is described. At the proper height for the window, D, is fastened a
mirror of platinized glass. It is supported on the wire by thin platinum
foil, which is fused to the wire, and then folded around the edges of
the mirror. At the end of the wire is a clamp, consisting of two flat
pieces of platinum 1.25 mm. thick, 3 mm. wide, and 6 mm. long. One
is hard-soldered to the wire so that one surface is in the axis of the
wire. The other is fastened upon this by tw^o screws. The fibre is
fastened at the top in the similar clamp, F, at the end of the wire, I.
The nut, H, into which the wire, I, is screwed, carries a cross-bar, G,
the ends of which are engaged by the platinum wire hooks, E and E,
shown detached at E' and E'. There is also a check-nut, K, on the
wire, I, above H, which can be screwed down upon H to hold the clamp
and cross-bar in any desired relative position. The upper end of the
wire, I, screws into a nut of the same material as itself on the soft
iron armature, J, which is supported by the swivel-head, K. The
supporting cross-bar is itself fastened to the two vertical threaded
pieces passing through the supports, L L, and furnished with nuts for
support and adjustment.

As the telescope and scale were to be used in observing, and as the
whole apparatus was to be heated, a plane parallel window, D, which
would bear a temperature of 300° C, must be secured. It was decided
to close in the end of a glass tube, and grind the inside and outside
flat and parallel to each other, and then seal the short horizontal tube
at the proper place to the long vertical one. By using a large lump of
optical glass, and using the oxygen flame, it was found possible to close
the end with glass of fairly uniform density. In ordinary glass tubes,
the streaks in the glass cause difticulty, and besides, almost invariably
a small sort of pit is formed at the centre in the process of sealing.
At this point, the density of the glass is different from that of the
rounded part, thus giving an irregular lens effect. The method of
grinding is to use a ring tool with which to make a groove around the
inside just as large as the size of the tube will allow. The groove
allows clearance for the emery when the process of grinding flat is

126 PROCEEDINGS OF THE AMERICAN ACADEMY.

undertaken. A thoroughly satisfactory window is obtained in this
way.i*

After the glass vessel has been hermetically sealed, the soft iron
armature, J, can be turned by means of a magnet fixed suitably out-
side. The magnet is placed on a circular platform of brass surrounding
the tube so that the poles of the magnet control the armature within.
The platform is supported on the top of the box containing the glass
part of the apparatus. The platform has a circular groove in it which
a circular brass ring fastened to the lower side of the magnet exactly
fits, so that the magnet may be slid around without altering its position
with respect to the tube.

To put this apparatus together required some care in handling, and
no little skill in glass-blowing.^^ The large cylinder of glass was blown
about 40 cm. long, and when the three supporting wires, one of which
is shown at 0, had been sealed in, the lower end of the cylinder was
opened. To the upper end the narrower tube was joined, and the short
tube bearing the window, D, was then sealed on at the i)roper place.
The next step was to fasten the fibre so that it might be heated to a
temperature of, say, 300° C, without danger of slipping or breaking.
Various attempts were made. For example, the end of the fibre was
platinized, and electroplated with copper to the supporting wire, — a
very troublesome operation. It was found, moreover, that when heat
was applied a break occurred where the quartz came in contact with
the metal, so that this method was abandoned. Carbon cement was
also tried, but discarded owing to the uncertainty whether all of the
volatile substances which it contains were driven off. Clamping was
resorted to, and the simple form of clamp shown in the figure adopted.
With the clamp, the danger of snapping the fibre just at the edge of
the metal is considerable. To minimize this, platinum foil was wrapped
around the part of the fibre to be placed in the clamp. The upper
large plate was now pushed on to the wire, B, and the small disk
clamped to the wire in the manner already described. The lower
plate was then placed on a support, the glass separating pieces placed
temporarily upon it, and the disk suspended in position between
the plates. A short range horizontal telescope was then focussed on
the edge of the suspended disk, so that, when the latter was made to
revolve, one could tell very readily if the wire, B, had been fixed at
right angles to the disk. In order to remedy any want of perpendicu-

" This work was done by Mr. Lundin of the Alvan Clark Optical Company,
Cambridge.

^^ Mr. Gelling, the glass worker of the Jefferson Physical Laboratory, has
done the glass-blowing with great care and efficiency.

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 127

larity the upper plate and the disk were lifted together, and the wire
carefully bent at a point close to the disk. After some trials it was
found possible to adjust, so that the maximum difference in height of
the two ends of a diameter of the disk was less than 0.07 mm.^^ The
width of the disk was 44 mm. The large plates were then fastened
together as described above, and the three clamps, one of which is
shown at N, were placed so as to fit the supporting wires, one of which
is seen at 0.

Suspending cords were now placed temporarily around the glass
separating tubes and the plates raised by them, in an inverted position,
allowing the armature and its belongings to be suspended by the fibre.
The whole was then carefully lowered into the enclosing vessel, which
had been placed temporarily bottom upward. When the plates were
in position on the supporting wires, the various wires of the suspended
part were put in place by means of a tool made for the purpose, the
various nuts turned on, and the whole turned into its natural posi-
tion. The disk was raised by turning the armature, J, and the plates
then made parallel to it. This adjustment was made by turning the
supporting nuts on the wires 0, 0, 0. Finally, the check-nut, K,
being loose, the upper clamp was turned in the cylindrical nut, H,
until the mirror faced the window, D. The check-nut was then tight-
ened, and the suspended part lowered so as to rest on the tripod at C.
The instrument could now be handled with only moderate care. The
upper and lower ends were then sealed off, and it remained only to join
this to the other parts of the apparatus.

The Transpiration Problem.

The first experiments on Thermal Transpiration were made by Fed-
dersen,i7 but the full investigation of the phenomenon is due to Pro-
fessor 0. Reynolds. 1^ He showed that, if the two surfaces of a plate
of porous material which divides a mass of gas into two separate por-
tions are kept at different temperatures, the gas will force itself through
the channels in the material from the cold surface to the hot until a
certain difference of pressure is reached. In the case of air, he found
it possible to establish, in this way, as much as 6 mm. of mercury differ-

" Stokes has shown that a small inaccuracy in this adjustment involves a
rather large error in the measurement of the resistance encountered by the
moving disk. If the layer of air between the latter and the tixed disk is wedge-
shaped, considerable energy is used up in crowding the gas between the fixed and
moving disks. The adjustment attained here is sufficiently accurate to avoid this
difficulty.

" Pogg, 148, 302 (1873). " Phil. Trans., 170, 1880.

128 PROCEEDINGS OF THE AMERICAN ACADEMY.

ence of pressure between the two sides of the plate, where the mean
pressure in the gas was 760 mm. His experiments established the
fundamental law that the difference of pressure reached is increased by
increasing the difference of temperature between the surfaces of the
porous plate, and that, given a certain difference of temperature, the
amount of the gas transpiring, or the height to which the difference
of pressure will grow, is governed by the relation between the mean
free path of the molecules and the diameter of the conducting space.
When, at a given pressure, the diameter of this space is diminished,
the difference of pressure attainable is increased. Since this is true,
it is readily seen that, when the transpiration spaces are large, it is
only necessary to reduce the density of the gas to get the same re-
sults as those obtained at greater densities with spaces of capillary
dimensions.

Sutherland ^^ renews the theoretical discussion of this phenomenon,
and by a different method arrives at substantially the same result. His
result appears in an expression relating the difference of pressure to the
mean pressure, the coefficient of viscosity, the diameter of the transpira-
tion tube, and the mean velocity of the molecules. He then considers
the case of a circular vane of badly conducting material, placed in a
circular space, which it fits rather closely, and, assuming that in the
transpiration space thus formed the temperature of the gas is controlled
by that of the vane and the surrounding annulus, he deduces an expres-
sion for the force which will tend to push the vane out of the plane of
the annulus, when one side of the vane and the corresponding side of
the annulus are heated. His result is expressed thus:

^^ Ap + B+ljp ^^^^

where F is the force on the vane in arbitrary measure, and 2^ the
mean pressure expressed in, say, millimeters of mercury.

Sutherland has submitted his equation, with a considerable degree
of success, to the experimental test, using data accumulated by Crookes
in his work, on viscosity of gases at high exhaustions. Crookes meas-
ured not only the logarithmic decrement of the vane of mica men-
tioned above, but also the angle through which the vane was deflected
when the light from a candle was made to fall on the blackened half
of one of its surfaces. By measuring /'^and the pressure for three dif-
ferent pressures, the constants in (IV) can be determined, and then,

" Phil. Mag., 42, 1896.

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 129

by measuring F, 2^ can be calculated for any other degree of exhaustion
and the result compared with the value of p obtained by the McLeod
gauge. If (IV) is the proper relation between F and x>, the values of
the latter obtained from (IV) and from the gauge should be the same
over any range of pressures where the results obtained by the gauge
are reliable.

In Sutherland's hands, this formula has stood the test fairly well, but
it must be added that the experimental conditions from which the
data used by him were obtained did not well conform to the mathe-
matical conditions assumed in the deduction of the above formula.
Still, the results obtained by him indicate the direction in which to
look for the full solution of the problem.

Transpiration Apparatus — Description. — Figure 3 is a horizontal
section of the instrument through the centre of the suspended vane.
The essential parts of it are a cylindrical glass vessel, A, Figure 3,
about 7.5 cm. in diameter, in which is fixed an annulus of mica 1.25
cm. wide, the plane of the annulus being a cross section of the vessel.
The vane, suspended in a manner to be described later, will pass
through the opening of the annulus, leaving about 0.75 mm. clear-
ance. The vane is 4.7 cm. in diameter, and is less than 0.1 mm. in
thickness. The vane is clamped between a shoulder and nut at B,
Figure 3. The supporting wire, C, is in turn fastened to another,
D, by collar and check-nut, U and V. D bears a mirror, E, and F
and G are counterpoises. At K is a short metal tube- shown in
vertical section at H, Figure ^a. The wire, I, Figure 3a, is furnished
with shoulder and check-nut, seen at L and J, and just fits the tube,
H. The fastening of the fibre is the same here as in the viscosity
apparatus.

In Figure 4 is shown the arrangement \>y means of which the sus-
pended system can be raised or lowered without orienting, and
oriented without raising or lowering. A is a soft iron armature, D a
supporting swivel-head, the rod of which presses through guide-pieces,
E and F, and terminates in a second supporting swivel-head, G. To
the vertical rod is fixed a cross-bar, II, furnished with vertical guide-
pieces, I I, which pass through the wire loops, J J. To the armature,
A, the fibre clamp is fixed. The clamp is kept in the centre of the
tube by means of the wire, K, which has a loop through which the
clamp wire, L, just passes. M is another soft iron armature supported,
as sho^\Tl, on a screw passing through a nut, N, which, in order to
avoid complications from inequalities of expansion, is made of the same
material as the screw.

VOL. XLII. — 9

130

PROCEEDINGS OF THE AMERICAN ACADEMY.

nG.4

HOaa. — FRICTION AND FORCE DUE TO TRANSPIRATION. 131

By turning M alone, the whole suspended system is raised or lowered ;
while by turning A alone, a twist is given to the fibre while the height
of the system is unchanged. Magnets, similar to the one used for
turning the armature in the viscosity apparatus, and mounted so that
they are entirely free from the glass part of the apparatus, are used to
turn the armatures A and M.

Openings were left at 0, P, Q, R, S, and at a point directly beneath
the suspending fibre, until theannulus and vane with its support-
ing wire, C, were put in place, the wire D, bearing mirror and counter-
poise, screwed into the collar U, and the adjusting apparatus bearing
the fibre and the wire I placed in position. When J had been tight-
ened, the whole suspension was raised by turning M. This operation
was carried out in order to determine w'hether the wire D had been
screwed just far enough into the collar U so that, when the system
was raised, the plane of the vane might be parallel to that of the
annulus. To remedy any want of parallelism, the suspended system
was lowered again, and the collar U turned with respect to D. After
going through the process of adjusting many times, the vane was finally
placed in the proper adjustment, which was maintained by means of
the nut, V.

In order to avoid breaking the fibre, during the process of closing
the various openings in the apparatus, the suspension was lowered to
resting loops not shown in the figure. All of the openings mentioned
above were now closed save P, to which the connecting tubes shown in
Figure 5 were joined.

The McLeod Gauges. — Two McLeod gauges of the form shown at
A, Figure 5, were used. They have different factors, one of them being
suited for the measurement of comparatively high pressures, while the
other, the highest factor of which is about 69,(H)(), is suited for the high-
est vacua. At B B are air-traps to prevent small bubbles of air, which
may have adhered to the glass tube below, from slowly rising and de-
stroying the vacuum. As it was necessary to keep the mercury in the
gauge for some time and to keep it clean, the ordinary method of rais-
ing the mercury by raising a reservoir of it attached by rubber tubing
to the barometer tube of the gauge, was replaced by the method which
Figure 5 will explain^ Here are two reservoirs C and D, attached to
their respective gauges. The entrance to each is fitted with a stop-
cock, and the single leading tube has a three-way cock at E. F is an
air-tight reservoir, S a pipe leading to the water tap, and T a waste
tap. Water rises through S and forces air from the top of F against
the mercury surfaces in C and D.

132 PROCEEDINGS OF THE AMERICAN ACADEMY.

Arrangement of the Apparatus as a whole. — Figure 5 shows how
these three pieces of apparatus are connected. It will be seen that the
viscosity apparatus and the transpiration apparatus are joined by the
glass tube L, and that a common tube leads from them to the pump by
way of a tube, M, containing granular silver, and one, N, containing
sulphur which has been fused and then powdered. The sulphur is in-
tended to prevent mercury vapor from passing from the parts of the
apparatus in which there is mercury to the other parts. The silver is to
absorb the sulphur vapor. As a means of testing the purity of the air
used, a spectrum tube, not shown in Figure 5, is inserted between the
tube containing silver and the main part of the apparatus. The figure
shows how the McLeod gauges are connected to the other parts of the
apparatus. The tube, P, leads to the pump. The connection between
the viscosity apparatus and the transpiration instrument is a long
spiral tube, so that the former may be rotated through a considerable
angle without disturbing the latter.

The piece marked A' is for the purpose of admitting dry air or other
gases, and consists of about 2.5 m. of 2.5 cm. tubing containing phos-
phoric anhydride, and 1.25 m. containing chloride of calcium. The gas
is admitted through a tube, G, whose end passes under the flared out
end of the barometer tube, H. The bottle, I, contains mercury form-
ing a seal. The drying tubes may be connected to a bellows, if air
is to be experimented with, or to a gas generator. The gas rises in
bubbles through the mercury to the bulb, J. The small bent tube K
is to prevent the mercury from being driven through the apparatus
when a bubble of gas rises.

The mercury pump has no stop-cocks. It has one mercury-sealed
valve. The auxiliary is a mechanical pump which can reduce the
pressure to two or three millimeters.

The viscosity apparatus, the transpiration apparatus, and the gauges,
are placed on an iron support inside of an electric oven. The first and
second pieces are each placed in a double walled sheet iron box, whose
wall space is packed with asbestos. The fronts of these boxes are
removable, as is also the front of the oven. The purpose of the oven
is to provide means of heating the whole apparatus to a high tempera-
ture to insure drying and to free the inside of the glass from the
carbon dioxide which invariably adheres at ordinary temperatures and
pressures.

When the different parts of the apparatus were set in position and
sealed together, and before the suspensions had been raised, or any
pumping had been done, the front of the oven was closed and heat
applied so as to maintain the temperature at 200° C. during a whole

Figure 5.

HOGG. — FRK.'TION AND FORCE DUE TO TRANSPIRATION. 133

day. There was no cracking of the glass, so that one was assured
that the joints had all been well annealed.

Drying Process.

This process consisted in first pumping out the air until a pressure
of a few millimeters of mercury was reached, then forcing in through
the tube G a large quantity of dry air. This was pumped out again,
and more dry air then forced in. This process was repeated many
times. After this preliminary drying, and when the pressure was low,
the front of the oven was closed and a current turned on sufficient to
raise the temperature to 200° C. This temperature was maintained
for several hours, and during this time the pump was kept going, and
for about one hour the connecting tubes were kept hot by a Bunsen
flame.

Perhaps it may be well to state here, that in the effort to distinguish
between a real leak in the apparatus and what will produce a similar
eff'ect, viz., the slow "evaporation " of the gas from the inner surface of
the vessel, it was found expedient to remove the sulphur tube and silver
tube. Under these conditions the pumping can be done much more
quickly. When the heating and pumping process above described had
been resorted to, and after the oven had been allowed to cool down to
room temperature, it was found that a vacuum of about 0.0003 mm., as
indicated by the gauge, had been reached. When, however, the appara-
tus was simply allowed to stand the pressure greatly diminished, and a
condition was finally reached when a slight rise in the temperature of
the room would cause the pressure to increase greatly, much more than
could be accounted for by the temperature coefficient. Then again a
small decrease in temperature, say four or five degrees, would cause a
corresponding anomalous decrease in the pressure. In one case where
the temperature of the room reached 14° C. and remained there for
over a day, the pressure was less than one third of what it was when
the temperature had reached 18° C. for the first time after the oven
had been allowed to cool down. This is mentioned merely to show
how important a part the temperature of the glass plays in determining
what the vacuum in the apparatus at any time is.^o

After the complete drying process the spectrum showed that the
moisture had been removed, and the vessel was then filled with
dry air.

The suspensions were then raised to the proper height by turning

" After it had been proved that there was no leak in the apparatus the
sulpliur and silver tubes were replaced.

134 PROCEEDINGS OP THE AMERICAN ACADEMY.

the magnet which controls the armature, A, Figure 2, and M, Figure 4.
A cathetometer was used to determine when the swinging disk in the
viscosity apparatus was midway between the other two. As the mica
vane could not be well viewed with the cathetometer, its proper ad-
justment was judged by its symmetry of position with respect to the
surrounding ring of mica.

Method of Experiment.

Viscosity Apparatus. — This instrument is held in position at the
top by a snugly fitting collar fixed in the top of the enclosing box.
It is fixed at the bottom, as shown in Figure 5, so that by giving the
arm, L, a slight, slow angular movement, the disk can be set rotating
without giving it a serious pendulous motion. This is especially true
at the higher pressures, but more care in starting is necessary when
the gas becomes rarer. About three quarters of an hour's training is
always given to the fibre before observations begin. After allowing
everything to become steady, the position of rest for every swing is
observed, and when the damping is rapid about seven or eight swings
is all one can get for any one start given to the disk. Sufiicient ac-
curacy is obtained by using the results got from starting the disk four
times. This applies only to the work at the higher pressures ; as will
be seen, the plan is changed when the density diminishes, for then many
more arcs can be obtained before the amplitude of swing becomes too
small.

In getting the mean decrement, the logarithms of the fifth, sixth,
seventh, and eighth arcs are taken respectively from the first, second,
third, and fourth, and the result in each case divided by four. At the
lower pressures, where many more arcs can be obtained in a series, and
where as a consequence the error in observing any one is increased,
the eleventh is taken from the first, the twelfth fi-om the second, and
so on, and the results divided each by ten. The decrement used is
then got by taking the mean of some sixteen such decrements.

Transpiration Appat-atus. The source of light used for the purpose
of illuminating the blackened face of the mica vane and annulus was
a twenty-five candle power incandescent lamp, suited to a voltage of
forty. The current used was that from a storage battery.

The zero position of this instrument is that position of the armature,
M, Figure 4, which allows the vane to hang in the plane of the annulus,
when there is no irradiation of any part of the apparatus. To read
this position, there is a pointer attached to the magnet which controls
the armature. The pointer coincides with a radius of a graduated
circle placed on the upper magnet platform, concentric with the tube

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 135

in which the fibre is. Great care is taken in setting to turn the
magnet in one direction so that any movement which the magnet, and
therefore the pointer, may make, which is not made by the armature,
may be eliminated. It was found, however, that with an ordinary
permanent magnet this elimination was not satisfactory, so that a
strong electro-magnet was finally used. This proved quite satisfactory,
and certainly the error here is not so great as that arising from the
innate difficulty of setting the vane to the proper position. To deter-
mine when the vane is in the proper plane a telescope is focussed on
a scale reflected in the mirror, E, and the point on the scale which
corresponds to the proper position of the vane is noted. This, of
course, remains the same so long as the disposition of the apparatus
is unchanged.

From what has been said previously on the relation between the
force on the vane and the size of the transpiration space, it follows
that for any given pressure the force on the vane in this instrument
will be greatest when the vane and annulus are in the same plane, for
then the annular space is least. The object is to measure the force
when this disposition is secured. Since the blackened surface is
turned towards the heat source, when this surface is irradiated the
vane recedes, because pressure grows on the hot side. By turning the
magnet, enough torsion is given to the fibre to bring the vane forward
again into its zero position. If too much torsion is given, and the vane
is thrown in the least past the annulus, then it continues to swing
forward, because the force on it diminishes as its distance from the
annulus increases. A glance through the telescope shows when this
has happened, and in this case the magnet must be turned back and
another trial be made. Much practice is required that one may set the
vane, even with moderate success. The difference between the read-
ings on the circular scale when the vane is and when it is not irradiated
is the torsion necessary. As is allowable, the force on the vane is
assumed to be proportional to the angle of torsion when the latter
is not large.

In this maximum effect we have a method of finding the zero posi-
tion without actually looking to see that the vane and annulus are
co-planar. The method consists in illuminating the vane, setting to
the maximum point, and noting the mark indicated by the cross-hair
of the telescope. This mark indicates the zero position. It is really
best to determine the two balancing points for any angle of torsion,
one when the vane is behind the annulus and the other when it is in
front. As the torsion on the fibre is increased the places of balance,
indicated by the cross-hair of the telescope, approach each other,

136 PROCEEDINGS OF THE AMERICAN ACADEMY.

and the mean of these locates with sufficient accuracy the maximum
point.

So long as the shutter over the window of the containing box is
closed, the zero position should remain unchanged. With ordinary
jacketing, it was found that this was not the case. Indeed, in some
cases there was as much variation as 25°. This could be due to one
or all of three causes, viz. : convection currents, unequal heating of
the bulb or indeed any change of temperature of the apparatus, or to
small charges of electricity on the vane or containing vessel.

To guard against the first of these, as has been said, the apparatus
was enclosed in a double-walled box with an asbestos interspace. But
since the McLeod gauge, which, of course, must be left uncovered, and
is connected with this instrument through various obstructed tubes,
responds quickly to any change of temperature in the room, any
change in this temperature will cause a flow of gas either towards the
transpiration instrument or away from it. To overcome this difficulty,
a house whose walls are of asbestos and double, with an air interspace,
was built surrounding the apparatus. In it were placed four electric
heaters, the current through which can be made and broken by a relay
worked by a battery circuit, in which is a thermostatic strip. In this
way the temperature of the whole space — about 24 cubic meters —
enclosed can be maintained very nearly constant. The temperature
was kept near 22° C. day and night, so that one might begin work
at any time and know that the apparatus was not far from a uniform
temperature.

The second cause, that of temperature change in the instrument
itself, proved the most serious. Before the constant temperature room
was resorted to, invariably during the day with rising temperature
there was an advance in the zero position, i. e., the apparatus acted as
if the vane were illuminated, while during the night, as the tempera-
ture fell, the contrary was the case. The blackened surface would, of
course, absorb heat which was being conducted in through the walls
of the containing vessel faster than the clear surface, and a transpira-
tion would begin which would have the same direction as that arising
from the illumination of the vane. When the rise of temperature
ceased, then the two surfaces would gradually reach the same tempera-
ture, and in the absence of cause for transpiration the vane could be
put into its zero position without using force. Only by enclosing the
bulb of the apparatus in a pretty thick (1.5 mm.) brass shell (the object
of which is to distribute quickly the heat which enters from without)
and then packing the box full of cotton wool, leaving only a channel to
the mirror, E, closing the door of the box, and then packing it all around

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 137

with wool, was it possible, even with the help of the constant tempera-
ture room, to remove serious disturbances arising from this cause. It
was also necessary to prevent, as much as possible, light from shining
on any part of the apparatus, as this would produce unequal heating.
The light from the telescope lamp passed through a water window, and
was allowed to shine only when observations were being made.

The trouble arising from electrical charges can readily be distin-
guished from those just mentioned, for, with it, the vane tends to take
up a fixed position, and force is required to change that position in
either direction. The force on the vane arising from unequal heating
is unidirectional. Trouble from electrical charges showed itself most
distressingly after an attempt to wrap the bulb in tin foil for the pur-
pose of minimizing outside heat effects. The friction between the
metal and the glass produced a very pronounced charge. It was
noticed also that after filling the vessel with air in the manner already
described the suspension, or rather the whole apparatus, had become
so charged that its attraction for a pith-ball could easily be detected.
A rather weak radioactive substance was placed within the brass shield
as near as possible to the vane, and after several days the charge had
disappeared. During the time when the box was being packed with
the wool the brass shield was kept to earth, and it has remained so
connected.

By attending carefully to all of these points it was found possible to
control the vane so that after the current was turned on in the lamp and
before the shutter was opened there was no great change in the zero
reading.

Since the object is to establish a relation between pressure and the
difference of pressure maintained between the ends of a transpiration
space, and since any surface along which there is a variation of tempera-
ture must give rise to transpiration, it is clear that if the entire bulb
of the instrument is illuminated, there will be various causes contribut-
ing to the total transpiration pressure, because the different parts of the
surface of the bulb will not be ev[ually heated. Now Sutherland has
developed equation (IV) on the assumption that the only transpiration
space contributing to the effect is annular in form. This is the simplest
form of space to deal with analytically, and the attempt to establish
the desired relation is likely to prove more successful w4th such a space
than with an irregularly shaped surface unequally heated. In the form
of the apparatus finally adopted the bulb is of a somewhat different
form from that shown in Figure 3. The mica ring is placed against
the conical posterior part of the glass vessel, so that the whole of the
vane and ring, together with that narrow part of the glass in contact

138 PROCEEDINGS OF THE AMEllICAN ACADEMY.

with the ring, may be irradiated. Thus the gas will transpire past not
only the inner edge of the ring, but also the outer edge, and yet the
whole bulb is not heated. There are then really two concentric annuli,
and no space by which difference of pressure can be effaced except
through the transpiration spaces themselves.

Before packing the box with wool, the lamp was placed at its proper
distance, about 80 cm., and in such a position that the light from it fell
perpendicularly upon the vane. Then a bright metal diaphragm was
placed on the glass opening in the door of the box just large enough so
that the base of the cone of light from the lamp would cover the desired
area. The only part of the bulb illuminated, other than the mere ring
contiguous to the outer edge of the mica ring, was, then, that imme-
diately within the box and opposite the hole in the diaphragm, so that
the heated portion of the bulb was at least 16 cm. away from the vane.
The spot of glass irradiated was only about 4 cm. in diameter. To
minimize the heating of this by absorption, the light was made to pass
through about 2.5 cm. of glass and about 7 cm. of water. The water
was kept running from one bottle to another through a water window
placed between the lamp and the apparatus. The temperature of the
water suffered no perceptible change in the course of an experiment
which lasted some three hours.

Perhaps the greatest difficulty experienced in the mere handling of
this apparatus is that caused by the great inertia of the suspended
system. It is easily seen that the least jar given to the apparatus in
turning the control magnet may give to the system a momentum which
is easily many times greater than the force which it is desired to meas-
ure. To make conditions as favorable as possible, the platform on which
the magnet was placed was finally fastened so that it and the magnet
were entirely free from the glass vessel and from the containing box ;
but the more or less jerky motion of the armature as it moves under
the influence of the magnet still gives the same trouble, though in a
much less degree. This difficulty is greatly increased at low pressure ;
for when the density is small, the viscosity of the air is so small that
the vane, though large, is a very inefficient damper, and so when the
suspended system suffers a slight disturbance it moves freely until it
strikes one side of the containing vessel ; then it rebounds, strikes the
opposite side, and so on. It is true that the suspended system might
have been made lighter than it is, but, at best, it must be rather heavy,
for the form which it must assume in order that it may be put
together is such as to preclude its being made as light as it should be
for convenience.

It is clear also that the equilibrating torsion given to the fibre will

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 139

depend upon how long the Hght is allowed to shine on the vane, be-
cause the vane, after it is heated, becomes a radiator, and the surround-
ing vessel is heated by radiation from the vane. This increase in the
force goes on for some hours, and in that time there is a chance for very
inconvenient changes in the temperature of the vessel and vane due
to extraneous sources of heat, e. g. the different distribution of the
heat in the room when the lamp is lighted, and when the experimenter
is in the room. The source of light was enclosed in a double- walled
asbestos chimney, which communicated at the tc^ with a flue, but the
sides of this chimney became heated in time. It was found best to
set the illuminated vane as accurately as possible (a process taking
from a half to three quarters of an hour), and then close the shutter
and set again. The difference is taken as the torsion necessary. The
results given below were obtained in this way. It was found that
the zero position of the vane, i. e., the position of equilibrium after
the shutter had been closed, did not change as much as 5° in an hour.
At this point, however, an error is introduced which tends to make the
result too large. The maximum angle of torsion obtained was 250°,
so that the error here considered is not very serious for such an angle
of torsion ; but as the pressure is diminished the angle diminishes,
and at pressures where the angle of torsion has fallen to, say, 25°,
this error becomes serious.

McLeod Gauge.<i. — In reading the gauges, special attention was
paid to these points :

First, the mercury, when lowered, was never allowed to sink much
below the point of connection between the volume tube and the pres-
sure tube. The reason for taking this precaution is that the narrow
bore of the latter offers considerable resistance to the passage of gas
into it, and thus when the mercury is raised after having been allowed
to sink well down, more than the right quantity of gas is thrown up
into the bulb, and the pressure will read too high.21 Still further to
ensure accuracy on this point, the mercury is made to rise very slowly
indeed until it has passed the entrance to the pressure tube.

Second, during the ascent of the mercury the bulb and tubes are
tapped repeatedly ; and in setting on any mark, care is taken to tap
both tubes until one is certain that the mercury has really settled
down.

Third, in the measurement of each pressure the mercury is raised
twice, and, for each time, generally one measurement is taken at each

" Kamsay and Baly mention the necessity of taking tliis precaution. PliiL
Mag., [v], 38, 1804.

140 PROCEEDINGS OF THE AMERICAN ACADEMY.

of two marks on the volume tube of the gauge. The cathetometer is
used to learn when the setting is right, and to measure the mercury
column.

Of course, the nearer the top of the volume tube one works, the
more serious the error made in setting becomes. Indeed, it is better
not to use a mark which is less than, say, 2 cm. from the top.

Results.

The following table gives the results obtained so far. In the first
column is given the gas pressure as measured by the McLeod gauge.
The pressure is expressed in millimeters of mercury. The gas em-
ployed in this case was air. In the second column the values of
the logarithmic decrement in the viscosity apparatus corresponding
to these pressures are given, and in the third the amount of torsion
given to the fibre of the transpiration instrument at the various pres-
sures to balance the force due to gas action on the vane. The signifi-
cance of the fourth and fifth columns will appear later.

The table shows how slowly the logarithmic decrement decreases
at first as p is diminished. That there is an appreciable diminution
in I even when the pressure is great, e. g. 20 cm., is due to the fact
that the distance between the fixed and moving surfaces in the ap-
paratus is very small, and therefore the coefficient of slip, yS, is com-
parable with it. To put the matter in another way, I is large because
of the small distance between the plates, so that small relative changes
in it can be perceived. Yet the table shows that at a pressure of
5.8 cm. the resistance to the moving disk is only one half per cent
smaller than it is at atmospheric pressure.

With falling pressure the rate of decrease of / increases, and for
pressures less than 0.01 mm. I and j(> become approximately propor-
tional. At such pressures the mean free path of the molecules of air
is over half a centimeter in length, and is therefore several times the
distance between the fixed and moving disks, so that the friction is
largely superficial. Figure 6 shows the relation between I and 2^ over
the range from where j) = 0.530 mm. to where p = 0.00085 mm, A
unit on the axis of abscissas represents a pressure of 0.01 mm., and
a unit on the axis of ordinates represents I = 0.00333.

The resistance which the disk meets is due to at least two causes,
and we shall see that there is some evidence that there is a third.
There is first the friction of the air on the disk, and second, the fric-
tion in the suspending fibre. The former diminishes with decreas-
ing density of air, but the latter is a constant provided that the
temperature of the fibre is maintained constant, as was the case in

HOGG. — FRTCTION AND FORCE DUE TO TRANSPIRATION.

141

these experiments. Tlie change in the temperature of the apparatus
from day to day was rarely as much as 0°.5 C, and was generally much
less than this during the course of one experiment.

The proportionality already referred to would evidently be more
exact if the constant part of the resistance, i. e., that due to the im-
perfect elasticity of the fibre itself, could be determined and taken
from the total resistance. An effort has been made to determine what
is the resistance due to the air in the vessel alone. The method of

L

40

;i:

30

z:

g?

■f

?--

20

T-

1

10

O 10 20 30 40 50

Figure 6. The curve shows the relation between pressure and logarithmic
decrement over the ranjje of pressure, p — 0.5o0 mm. io p — 0.00085 mm. The
unit of pressure is 0.01 mm. The unit of logarithmic decrement is 0.00333.

procedure was to pump out the air to a certain low pressure, measure
the decrement, then pump to a still lower pressure, measure the dec-
rement again, and so on. If the exhaustion be carried far enough, a
limiting value for / should be approached. This did, indeed, happen,
but the limiting value seemed larger than one would have expected it
to be ; for it would seem that the friction in such a suspending fibre
should be exceedingly small. The following results show how the dec-
rement and the pressure diminished as the pumping proceeded. Pump
began at 10.30 a.m., when the pressure was about 0.001 mm.

142

PROCEEDINGS OF THE AMERICAN ACADEMY.

TABLE I.

p

I

R

C

p, cal. from I.

p, cal.

from R.

mm.
761.5

0.1655

514.1

0.1652

200.8

0.1650

58.4

0.1648

1.42

0.1533

62°

0.824

0.1461

122°

0.1112

0.498

0.1364

170°

0.1076

0..3.39

0.1258

190°

0.1085

0.226

0.1121

202°

0.1096

0.176

0.1032

0.1082

0.142

0.0938

0.1108

0.135

0.0931

248°

0.1072

0.0880

0.0765

240°

0.1050

0.0913

0.0590

0.0607

210°

0.1051

0.0611

0.0425

0.0491

170°

0.1048

0.0442

0.0284

0.0370

143°

0.1040

0.0297

0.033,

or 0.41

0.0232

0.0324

115°

0.1012

0.0249

0.025,

or 0.54

0.0211

0.0300

115°

0.1017

0.0226

0.025,

or 0.54

0.0148

0.0228

70°

0.1011

0.0159

0.015,

or 0.93

0.00928

0.01580

50°

0.1002

0.0101

0.010,

or 1.32

0.00595

0.01113

0.1000

0.00649

0.00410

0.00837

0.1002

0.00446

0.00261

0.00007

0.1007

0.00282

0.00177

0.00450

0.1113

0.00173

0.00186

000478

0.1053

0.00193

0.00085

0.00332

0.0999

0.00093

0.00024

0.00229

0.1119

0.00023

HOGG. — FRICTION AND FORCE DUE TO TRANSPIRATION. 143

Decrement at 11.30 a.m. was 0.00234
" " 12.30 P.M. " 0.00234

" " 4.45 P.M. " 0.00228

In this time there had been about four hours of continuous pumping.
According to the gauge the pressure at the final stage was 0.00019 mm.
It is possible, however, that the pressure was not completely equahzed
through the apparatus, although the time allowed to elapse between
successive strokes of the pump was sufficient to insure that the equal-
ization at this time must have been nearly complete. At 9.30 p.m.
the pressure had become 0.00024 mm. and the decrement at the same
time was 0.00229. No pumping had been done since the last meas-
urements were made at 4.45 p.m. At 12.10 p.m. on the next day the
pressure was 0.00027 mm., while the decrement was 0.00236. The
limiting value of the decrement seems to be not much less than
0.00230.

It is probable that this limiting value of / is due not only to the
friction in the fibre, but also to the friction of mercury vapor on the
disk. It was noticed that in the spectrum, after the current had been
allowed to run for some time, the mercury lines gradually appeared, as
if there were some slight deposit of mercury on the walls of the tube
which slowly evaporated under the heat due to the current. This
would indicate the possibility of a like deposit on the inner surface of
the other parts of the apparatus, for it will be remembered that the
spectrum tube is placed between the tube of silver and the main part
of the apparatus.

The fact that the limiting value of / obtained is larger than had
been anticipated would be explained by the presence of mercury vapor.
Its presence would add a third factor to the resistance experienced by
the disk, and one which would diminish certainly while pumping was in
progress, but which would increase again as evaporation of the mercury,
or the diffusion of its vapor to the viscosity apparatus from the other
parts of the apparatus, proceeded.

Proceeding for the moment on the assumption that the decrement
due to the air is proportional to the air pressure in the apparatus where
the pressure is small, we can deduce the value of that part of the decre-
ment due to friction in the fibre and the friction of the mercury vapor
combined. For if m represents this constant part of the decrement we
have,

Pi ■.(li-m)::p^: (l^ - m)

Also, for corresponding values for p and /, we find from Table I,

144 PROCEEDINGS OF THE AMERICAN ACADEMY.

;>j = 0.00177 mm. k = 0.00450
p^ = 0.00024 mm. 4 = 0.00229

Using these values, we find for m the value 0.00194. If now this
quantity m be inserted for K in the e(j[uation relating p and /, as given
above, viz. :

C can be determined for the different pressures, or C having been de-
termined for the higher pressures, for example for those between 1 mm.
and 0.1mm., the values oi jj corresponding to the lower values of /
can be solved for. The value of A used in this process was 0.1655, and
the value of C used was the mean of the first seven values given in the
fourth column of Table I. The fourth and fifth columns of Table I
give these results.

A comparison of the numbers given in the fifth column with those
in the first show that the values of p deduced irom the observed values
of / are in general greater than the observed values of p.

It must be admitted at once that the foregoing method of getting
the value of ^ is a very imperfect one, and it is inserted only tenta-
tively. It is now proposed to remove the sulphur and silver tubes
and place a vessel containing liquid air so as to surround a portion
of the tubes connecting the pump with the apparatus, so that not only
may all vapor be removed, but also that the very highest possible
vacuum may be reached. The decrement will then be measured. This
should give the value of the part of the decrement due to friction in
the fibre. The liquid air will then be replaced by liquid carbon diox-
ide, which will remove the vapor but not the gas to be experimented
with. It is hoped that this method of procedure will settle the only
point that seems to remain in doubt in this part of the investigation.
The full discussion of the law relating I and p is reserved until this
step has been taken.

With regard to the results given in Table I for the transpiration in-
strument it must be stated that the smaller numbers in the third col-
umn may quite easily have an error of ten per cent. Figure 7 shows
the results graphically. In this figure, a unit on the axis of abscis-
sas corresponds to 0.01 mm. of pressure, while on the other axis a unit
represents 10° of torsion. That portion of the curve which corresponds
to pressures below those for which the torsion is a maximum, ap-
proaches a straight line, and it is apparently a line which passes very
nearly through the origin. It is perhaps allowable to assume that it
does go through the origin ; for the force here, unlike the friction in the

HOGG. — FRICTION AND FORCE DUE To TRANSPIRATION.

145

other apparatus, depends entirely on the gaseous contents of the ves-
sel. There can be no force when these have all been removed. If there
is any vapor present, however, there will still remain some force when
the air has been pumped out. As we have seen, there are indications
that mercury vapor is present, but in small quantity, and at the lowest
pressure at which the transpiration apparatus was used the torsion
necessary to balance the force on the vane, were the contents of the
vessel the vapor alone, could not be more than 5°. This is readily

■p

1

XV

Qn -

OU

^"^ "®^-

Y "^^

J- """-^

OC\ I ^~^~--~.

tCKJ ^ o -

■^-"-^^

7

— — __ _

i

— -_

1^

■

t

L

1

I

>v

in -

L\J

7

t

^

O 10 20

30 40 SOP

FiGCRE 7. The curve shows the relation between pressure and force due
to gas action on a circidar vane over the range of pressure, p = 0.498 mm. to
p = 0.0093 mm. Tiie unit of pressure is 0.01 nun. The unit on the axis of ordi-
nates represents an angle of torsion of 10° given to the fibre supporting the vane.
This torsion is proportional to the force due to gas action on the vane.

seen by considering the torsion at these small pressures to be propor-
tional to the pressure.

If we confine our attention to the part of the curve from the origin
up to the maximum point, and use the larger values of the torsion
from which to determine the constants in Sutherland's equation, viz. :

F

Ap + B+ \Ip

(IV)

we get .1=0.00187, 7i = 0.0152, and 6'=25.G7. In the computa-
tions 0.005 mm. has been taken as the unit of pressure and 1° as the

VOL. XLII. — 10

146 PROCEEDINGS OF THE AMERICAN ACADEMY.

unit of torsion. If now we insert these numbers in the above equa-
tion and solve for the values of p, which correspond to the various
values of the torsion given in the third column of the table, the re-
sults given in the last column are obtained. The form of the equation
shows that there are two values of 2^ for any particular value of the
torsion. If we differentiate (IV) with respect to }) to get the value of
p, for which the torsion is a maximum, we get j»^= ^/ A, or/j = 23.1.
With the millimeter as the unit this is the same as j9 = 0.116 mm.
The value of the torsion for this value of jt? is 254°. The curve indi-
cates a maximum where p = 0.120 mm., and its value is 252°. The
further discussion of equation (IV) is reserved until more and more
accurate data have been collected.

With the object of rendering the instrument more easily handled,
and thus making it susceptible of greater accuracy, it is proposed now
to modify the form of the suspended system in order to reduce its mo-
ment of inertia. When this has been done the results from this
instrument should be quite as reliable as those from the other, and
with the experience which has been gained both in constructing and
handling the apparatus it seems quite certain that the desired object
will soon be accomplished.

Grateful acknowledgment is made to Professor Trowbridge for plac-
ing at my disposal all the resources of the laboratory, including the
services of a mechanician ^^ ^nd of a glass-blower. 23 Without the
assistance rendered by them the apparatus could not have been con-
structed. To Professor Hall, who first called my attention to the
problem, I am indebted for much advice and encouragement.

Jefferson Physical Labouatory,
Harvard University.

22 Mr. Thompson of the Physical Laboratory.

23 Mr. Oelling.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 7. — July, 1906.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE CONDITIONS TO BE SATISFIED IF THE
SUMS OF THE CORRESPONDING MEMBERS OF
TWO PAIRS OF ORTHOGONAL FUNCTIONS OF
TWO VARIABLES ARE TO BE THEMSELVES
ORTHOGONAL.

By B. Osgood Peikce.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL
LABORATORY, HARVARD COLLEGE.

ON THE CONDITIONS TO BE SATISFIED IF THE SUMS
OF THE CORRESPONDING MEMBERS OF TWO PAIRS
OF ORTHOGONAL FUNCTIONS OF TWO VARIABLES
ARE TO BE THEMSELVES ORTHOGONAL.

By B. Osgood Peirce.

Presented March 14, 1906. Received April 12, 190G.

If <^i (.r, I/), (p2 (•'', ]/) are the potential functions due to two colum-
nar distributions of matter the lines of which are perpendicular to
the a: y plane, and if ij/i (.r, y), xp^ {x,y) are conjugate to <^i and ^2,
respectively, the families of curves obtained by equating \pi and 1/^2 to
parameters, are lines of force of the two distributions. Moreover,
^1 + 02 is the potential function due to a combination of the two
distributions, and the function i/^i + ^2 equated to a parameter gives
the corresponding lines of force. The fact that if (<^i, i/^i) are any
pair of conjugate functions and (02, ^^ any other such pair, the
functions {a 4>i + h 02> ^^ "Ai + ^^ "As) are also conjugate — with similar
facts for other classes of functions — lies at the foundation of the
graphical methods so successfully used by Maxwell ^ and by others in
drawing equipotential lines, and lines of force or flow, due to combi-
nations of simple elements. If (0i, \pi) are merely a pair of orthogonal
functions and (02, ^i) another such pair, it is generally not true that
(01 + 02, "Ai + "As) are an orthogonal pair : thus {x, y), {x^ -f //-, yl x)
are pairs of orthogonal functions, but x -{■ x"^ ■\- y^, y -^ D /x are not
orthogonal.

In certain classes of physical problems one encounters potential
functions which are not themselves harmonic and the lines of which
are not possible lines of any harmonic function, and it is often de-

^ Maxwell, Treatise on Electricity and Magnetism, Vol. I, Ch. VII. Minchin,
Uniplanar Kinematics, § 112. See also P. W. Bridgman, The electrostatic field
surrounding two special columnar elements, These Proceedings, 41, 28.

150 PROCEEDINGS OF THE AMERICAN ACADEMY.

sirable in cases where the analytical processes become too complex,
to determine graphically the forms of lines of force or flow due to
a combination of two simple elements. This note discusses briefly
the conditions under which the ordinary method of procedure is
possible.

Let (a, yS) and (X, /x) be two pairs of orthogonal functions of the
two variables (.r, y), so that

dx dx dy dy '

ax a^ _^ ax . a^ ^ ^ _ (2)

dx dx dy dy '

then if (a + X, /? + i^) are to form an orthogonal pair, the equation

/aa ^ axwa^ ^ a^N fda ^ ^W^ _^ ^\ ^ (3^

\dx dx] \dx dx) \dy dy J \dy dy J

must be identically satisfied, Since (1) and (2) are true, (3) takes
the form

\dx dx dy dy J \dx dx dy dy)

If /^„, h^, h)^, h^ represent the values of the gradients of a, /8, X, /x,
and if the angle at any point between the directions in which X and /3
increase most rapidly be denoted by [X, /S], (4) becomes

hi,- h^- cos [X, P\ + h^ ■ h^ • cos [a, fj] = 0. (5)

Whatever the sequence of the directions of the gradient vectors
might be, the two angles which appear in (5) would be either equal
or supplementary, and their cosines would be ecjual in absolute value,
but the gradients themselves are intrinsically positive and the sequences
must therefore be such that

hjh^ = hjh^. (0)

Suppose that in the case of two given pairs of orthogonal functions
(s A) {\ H-)i the necessary condition (6) is satisfied, and that the

PEIRCE. — THE GRAPHICAL SUPEKPOSITION OF LINES OF FORCE. 151

value of the gradient ratio, hjh^, obtained from the given values of
a and /?, is the function li of ./■ and y ; then

and if, for {da)- j {dyY in this equation, we substitute the value

obtained from (1), it appears, since the gradient of a real function
cannot vanish, that

If for {dafl(dxy^ in (7), we substitute its equivalent

derived from (1), we shall learn that

Either the upper signs or the lower signs must be used in (9) and (11).
If now we treat the eciuation

V = «Vv (12)

in a similar way we shall obtain the e(|uations

d\ ^ fd,j.\

152 PROCEEDINGS OF THE AMERICAN ACADEMY.

and, so far as the relation (12) is concerned, we may use either the
upper signs or the lower signs, but if (4) is to be identically satisfied,
the same sign must be used in (9) and (13) and the sign opposite to
this in (11) and (14). Equation (6), then, together with the proper
choice of sequence of directions for the gradient vectors which corre-
sponds to the convention with regard to signs just made, will ensure
the orthogonality of a + X, ^ + /a. For practical purposes, however,
it is well to approach the problem from another side.

If (a, /3) and (A, /x) are given pairs of orthogonal functions, and if
we denote the given scalar point functions obtained by dividing dfi/dx
by da/dy, and by dividing dfx/dx by dX/dy, by t, and rj, the equations
(l) and (2) can be written in the forms

and

or

and

W%-Wi^=^

a^ ^ dy' dy ^ dx' ^ ^

dfi dX dfi dX

d:v = '' dy' ry = -'^ dTr- ^^^^

If the values of the derivatives of ft and /a given in (17) and (18)
be substituted in (4) this equation becomes

and if (a + X, /3 + /x) are to be orthogonal, a and X must be such as
to satisfy it. If A were expressible as a function of a, and /x as a
function of /8, the second factor would vanish, but this case is of no
practical interest and (10) demands in general that C and rj shall be
identical, so that

PEIRCE. — THE GRAPHICAL SUPERPOSITION OF LINES OF FORCE. 153

and

If in these equations the arbitrary function C is made equal to unity,
the conditions degenerate into the familiar definitions of any two
pairs of conjugate functions.

In order that a single function (/?) may exist the partial derivatives
of which with respect to x and y shall be equal, respectively, to

da , ^ da

it is necessary and it is sufficient that a and t, should satisfy the
condition

or

C [ ^ da\ d f ^ da\ ^ , ^

dt da dt da ^ ^, , . , ^

In order that /a may exist, t, and X must satisfy the et^uation

H.dJ^_^dJj_\_^^_^^^^^^

dx dx dy dij \ J • \. • J

If loge t, be represented by s7, the last two equations take the
forms

^ o "^ a

Cm ca . Cu Ca „„ , , „ . ,

S-a:; + ey-aJ+^W = "' (^4)

dm d\ dm dX _o/vN

s7-r.+ij-r, + ^^^^ = '>' , (2.^)

and, if each of these be differentiated with respect to x and with
respect to y, m may be eliminated from the resulting equations and a
necessary condition for a and A obtained, which may be stated in the
form of the determinantal equation —

154

PROCEEDINGS OF TUB AMERICAN ACADEMY.

da

dx

da

0

0

0

V'(a)

ax

dx

d\

dy

0

0

0

V (X)

d'^a.

dx-'

d'a
dx ■ dy

da

dx

da
dy

0

!.(-«)

dx'

d^K
dx ■ dy

dX
dx

dX

^y

0

I (-w)

d'a
dx ■ di/

d'a
dy'

0

da

dx

da

^y

^■(^^«)

d^k
dx • dy

d^X

dy'

0

dx

dx

dX

^y

i.M

0. (2G)

If a and A happen to be harmonic, the elements of the last column
vanish and the equation is satisfied, as it should be.

It is possible to factor the determinant, after it has been reduced,
and if

a-a . ax _ a^ . aa d'a , ax _ a=^x , da

dx' dx dx' dx dx ' dy dy dx ' dy dy'

d'a dX

dx ■ dy dx dx ' dy dx dy' dy dy' dy '

31 =

N^^[V^(a)

d'X

da d'a dx

a^X da

ax

dx

-^(-(^))-£-|(-«)|

ax

(27)

the condition of (2G) demands either that a and X satisfy the
equation

n rt /In

da

da

dx

dy

dX

ax

dx

dy

L

M

V\X)

N

= 0,

(28)

PEIRCE. — THE GRAPHICAL SUPERPOSITION OF LINES OF FORCE. 155

or else that a and A have the same level curves: this last case, as
being uninteresting, may be left out of account.

Sometimes (28) is more convenient than the unexpanded form of
the same condition which follows immediately if we solve (24) and
(25) for dm/dx and dzj jdy,

da

d\

duj d}j

V'V

^.'/

- \"-j

dx da

d\

da

dx

dx

^y

^^>J

dx

9uT dx

(a)-

da

dx

V^(X)

dij da

dx

da

dx

dx

%"

'^y

dx

(2!))

(30)

and equate the derivative with respect to i/ of the second member of
the first e(|uation to the derivative with raspect to x of the second
member of the other. This process yields the relation.

t-"^^^>-|-^^^"^'

da ^dX
dx dy

da dX
dy dx

d

ox

da

dx

-V-iX)

dx

da , dx
dx dy

da

dy

dx
dx

(31)

and it is possible to check the fact that (28) and (31) are equivalent
by a straightforward but somewhat laborious comparison of the two.

If a and A satisfy (31), a function I exists which satisfies (22) and
(23), functions (i and fx exist which satisfy (17) and (20), and (a, /8),
(A, fx), (a + A, /8 + i«) are orthogonal pairs of functions.

If, for instance, both a and A represent values in the xy plane of
harmonic space functions ( T, \V) the level surfaces of which are sur-
faces of revolution about the x axis, so that

1 d f dV\ a-F ^
y'yyV'^)-^-^ = ^

(32)

with a similar equation for W,

1 da

V^ (a) = -

y ^y

^''W=--.-^.

1 aA
y .%'

(33)

156 PROCEEDINGS OF THE AMERICAN ACADEMY.

equation (31) is satisfied and

da „ drjT 1 „ , V

eJ = «' a7 = ? ^ = '^- ^'*^

In this case, if we put c= 1, ^ and /j. are the Stokes functions corre-
sponding to a and A. If the level surfaces of the harmonic space
functions, V and W, are surfaces of revolution about two different
straight lines in the .ri/ plane, the functions a and A which represent
the values of Fand W in this plane do not in general satisfy (31).

Graphical superposition of the lines of force in the a-i/ plane due to
an infinitely long, homogeneous cylinder of revolution parallel to the
axis, and to a homogeneous sphere with centre in the plane, will not in
genera] yield the lines of force in the a:i/ plane due to a combination of
the two masses.

If a and X are harmonic, any linear function (but no other than
a linear function) of a is harmonic, and any two linear functions of
a and A satisfy (31). There generally exist, however, non-linear
functions of a and A which, although they are not harmonic, satisfy the
condition. The functions {w^ — y"^), {x^ + 3/^)", the second of which is
not harmonic, obey (31), as do the harmonic pair {x"^ — y"^), log (x^ + ?/^).

As a simple example of the fact that a harmonic function and a
function which is not even isothermal may satisfy the condition (31),
we may consider (2 y"^ — x'^) and (y^ — x"^).

The non-isothermal functions x"^ — ay"^, y"^ — ax"^, which are solu-
tions of the equation

d^_^d^_^V__^V_^^ (35)

dx^ dy"^ X ' dx y ' dy '

evidently satisfy the equation (31).

If a and A are any two solutions of the equation

where f{x) is any given function of x, the condition (31) is satisfied
and zj z=f(x).

PEIRCE. — THE GllAPIIICAL SUPERPOSITION OF LINES OF FORCE. 157

If a and A satisfy the equation

dn^ dW dV , dV

dx- Cif dx Cij ^ ^

ST is of the form <? .r + /* ^ + c.

In general a and A. must both be sohitions of an equation of the
form

d-^V d'^V „ dV ^, dV

where P and Q are any functions of x and y such that dP/dy = dQ/dx.

The question whether if (a, /8) and (X, /*) are orthogonal pairs and
(a + A, /? + yn) is not an orthogonal pair, it is possible to find a func-
tion {B) of ^8, and a function (J/) of /x such that (a + A., ^ + M)
shall form an orthogonal pair, has already been answered ; for a and \
must satisfy (31) in any case, and if they do this, nr may be determined
from (29) and (30) and B and xl/from (17) and (20).

The Jefferson Laboratory,

Harvard College, Cambridge, Mass.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 8. — July, 190G.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE CORRECTION FOR THE EFFECT OF THE
COUNTER ELECTROMOTIVE FORCE INDUCED IN
A MOVING COIL GALVANOMETER WHEN THE
INSTRUMENT IS USED BALLISTICALLY.

By B. Osgood Peirce.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE CORRECTION FOR THE EFFECT OF THE
COUNTER ELECTROMOTIVE FORCE INDUCED IN A
MOVING COIL GALVANOMETER WHEN THE INSTRU-
MENT IS USED BALLISTICALLY.

By B. Osgood Peikce.

Presented March 14, 1906. Received April 12, 1906.

At the present time, when on account of their many good qualities
ballistic galvanometers of the moving coil type are in such general
use, and when some of them fall into the hands of persons who are not
acquainted with their vagaries, it seems desirable to emphasize the
fact that the counter electromotive force induced in the coil as it swings
in the field of its own permanent magnet is often large, and that in
certain classes of absolute measurements the result might be in error
by many per cent if the effect of this electromotive force were not
allowed for. Of course, in comparing condenser charges, mirror, ballis-
tic d'Arsonval galvanometers are usually entirely satisfactory, and,
within wide limits, the "throws" of the coil, as measured on the
scale of the instrument, are nearly proportional to the quantities of
electricity sent impulsively through the coil. If, however, a moving
coil galvanometer, the resistance of which is known, be connected in
series with a resistance r, wound non-inductively, and an earth inductor,
permanently mounted at a given station, it will usually be found that
if /• be varied and if no account be taken of the electromotive force
induced in the galvanometer coil, throws ■will be obtained from a given
movement of the earth inductor, the relative values of which can only
be explained by assigning to the resistance of the galvanometer a value
much greater than the correct one. The amount of this difference
between the apparent resistance of the galvanometer and its real re-
sistance depends, it is clear, upon many things, such as the whole
effective area of the turns of the coil, the strength of the field about
the coil, the stiffness of the gimp by which the coil is suspended, the

VOL. XLII. 11

1G2 PROCEEDINGS OF THE AMERICAN ACADEMY.

relative resistances of the galvanometer and the rest of the circuit, the
moment of inertia of the coil, and the magnitude of the coefficients of
the air and electromagnetic damping. Two galvanometers which have
the same ballistic sensitiveness to a given discharge from a condenser,
and equal resistances, may, of course, act very differently so far as the
effect of the induced counter electromotive force is concerned when
placed in inductive circuits which outside of themselves are alike. It
is useless, therefore, to attempt to predict with any great accuracy the
magnitude of the disturbance due to the induced current in any par-
ticular instance, but it may be worth while to give briefly the general
results of observations in some actual cases, by way of illustration.

(A) A certain d'Arsonval ballistic galvanometer, such that a con-
denser discharge of one microcoulomb sent through it caused a throw
corresponding to a scale reading of about 11.0 cms., was connected in
series with a Du Bois and Rubens " Panzer Galvanometer " (P) and
with one of two coils of fine insulated wire which formed single layers,
the one on a wooden core 2.38 cms. in diameter, the other upon a rod of
soft iron 0.94 cms. in diameter. Either coil could be placed within a
solenoid of 22.3 turns per centimeter through which a small steady
current from a storage cell could be sent, and reversed at pleasure by
aid of a commutator in the circuit. By means of a clamp, operated
from without the case of the d'Arsonval galvanometer, its coil could be
held firmly fixed in such a position that the flux through it of the field
of its permanent magnet was practically zero, and it could be released
again at will. A heavy suspended system was used in P in order to
make the sensitiveness about the same as that of the other instrument
when the time of swing was a little shorter than that of the moving
coil. The whole resistance of the galvanometer circuit was about
2000 ohms. The slightest movement of the coil of the d'Arsonval galva-
nometer was sufficient to set the needle of the other instrument in
motion also, and the reversal of a given current in the solenoid always
caused a larger throw in P when the moving coil was clamped than
when it was free. In a typical case the throw of P's needle as meas-
ured on the scale of the instrument was 83.5 mm. when the suspended
coil was held still, but only 69.9 mm. when it was released. Each of
these numbers is the mean of a number of closely accordant readings.
Whether the strength of the current in the solenoid was made so small
that the throws caused by reversing it could just be read, or so large
that they could hardly be measured on the scale, the ratio of the indi-
cations when the suspended coil was fixed and when it was free was
almost exactly the same ; but it was easy to magnify the efi"ect of the
electromotive force of the swinging coil by increasing the current in

PEIRCE. — CORRECTION FOR COUNTER ELECTROMOTIVE FORCE. 163

the solenoid and decreasing the resistance of P so that the throws could
be determined. For the puri)ose of this experiment it was allowable to
shunt P, and when a one ninth shunt was used, the " throw " caused by
the reversal of a certain current in the solenoid was 73.9 mms. or
45.0 mms. according as the suspended coil was clamped or free.

(B) A certain d' Arson val ballistic galvanometer the total resistance
of which at the room temperature was almost exactly 123.7 B. A. units,
was connected in series with a rheostat and an earth inductor of 11.7
B. A. units resistance, the frame of which was fixed at a certain station.
The moving coil of the instrument was furnished with a horizontal wire
which projected about 23 mms. beyond the coil on each side and car-
ried on each end a brass weight. The object of this device was to
increase materially the moment of inertia of the suspended system and
thus to make the time of swing larger without increasing the already
inconveniently great sensitiveness of the galvanometer. When the
inductor ring, which lay in a vertical plane perpendicular to the merid-
ian, was reversed, the galvanometer throw, as measured on the scale
at a distance of 120 cms. from the mirror, was 9.41 cms., 5.51 cms., or
3.95 cms., according as the resistance of the rheostat in B. A. units
was 0, 100, or 200 : if no account were taken of the counter electro-
motive force induced in the suspended coil, these figures would point
to a circuit resistance of something more than 141 units instead of
135.4 units. In the condition just described the periodic time of the
suspended system was 34.5 seconds : when that time was reduced to
12.4 seconds by the removal of the weights attached to the horizontal
wire, the throw caused by reversing the inductor ring was 12.98, 7.72,
or 5.49 according as the rheostat resistance was 100, 300, or 500 ; these
figures point to an apparent resistance of 193 units in the circuit or
42 per cent more than the real resistance.

(C) A certain extremely sensitive d'Arsonval ballistic galvanometer,
the coil of which was about twice as long as is usual in such in-
struments, was connected in series with a rheostat and a "magneto-
inductor," i. e., a short coil of very fine msulated wire wound on a
spool which could be slipped between near, fixed stops on a long mag-
netized rod. The permanent magnet of the galvanometer was built
up of a large number of thin horseshoe plates hardened separately.
The resistance of the galvanometer current when the rheostat resist-
ance was zero was about 8691 at room temperature. When the ex-
ploring coil was slipped from one stop to the other, the throw of the
galvanometer, as measured on the scale, was 67.0, 58.1, 51.3, 48.3, or
40.05, according as the resistance of the rheostat was 0, 2000, 4000,
5000, or 8500. Of course it is not possible to compute the apparent

164 PROCEEDINGS OF THE AMERICAN ACADEMY.

resistance of the circuit with any great accuracy from these numbers,
any one of which might possibly be in error by 0.5% of its own value
and thus introduce a much greater fractional error into the result;
but it is interesting to find that if we compare the first number with
the others in succession, we get for the apparent resistance of the
circuit about 13060, 13070, 12915, 12990, and these numbers point
to a value 50% above the real value. The resistance of the "magneto-
inductor " alone was 40.3.

(D) When another similar ballistic galvanometer of the same gen-
eral type was substituted for the one mentioned in (C) so that the
resistance of the whole circuit was 4270, Mr. John Coulson obtained
throws of 116.0, 100.1, 88.6, 72.5, or 65.8, according as the rheostat
resistance was 0, 1000, 2000, 4000, or 5000. If we compare the first
of these numbers with each of the others in succession, we get as
values of the apparent resistances of the circuit, 6295, 6470, 6665,
6550, and these indicate a value about 50% above the true one.

(E) A d'Arsonval galvanometer such that the resistances of the coil,
suspending gimp, and connections amounted in all to only 4.8, was
connected in series with a rheostat and the " magneto-inductor "
already mentioned. The coefficient of air damping in this galvanom-
eter was considerable, and the field due to the permanent magnet ex-
tremely weak. The total resistance of the circuit was 45.1, plus the
rheostat resistance. By fastening the stops which limit the journeys
of the sliding coil on the inductor rod near together at the centre of
the rod or further apart near an end, the electromotive force induced
in the sliding coil as it was moved quickly fi-om one stop to the other
could be varied within wide limits. Three different positions of the
stop were used, and in each case a large number of observations were
taken and the mean used, as in all the results here given. For the
first position the throw of the galvanometer corresponded to a scale
reading of 77.8 mm. or 36.9 mm., according as the rheostat resistance
was 0 or 50 ; these numbers point to a circuit resistance of 45.2, which
is almost exactly the true value. The readings for the second position
were 129.3 and 61.4, and the calculated resistance was again 45.2.
The readings for the third position were 170.4 and 81.7, and the
calculated resistance was 46.0 units. The results obtained in this
extreme case illustrate what one may expect if the field is extremely
weak and the number of turns in the coil small.

(F) Another d'Arsonval galvanometer of very low coil resistance but
furnished with much finer gimp so that its total resistance was about
21, and with a strong permanent magnet, was treated in much the
same way as the galvanometer mentioned in (E). Two positions of its

PEIllCE. — CORRECTION FOR COUNTER ELECTROMOTIVE FORCE. 165

stops Oil the inductor rod were used, and in each of them throws were
observed when the rheostat resistance was 0, 50, and 70 ; the total
resistance of the galvanometer circuit outside the rheostat was 60.8.
For the first position the throws were comparatively large (196.3,
112.2, and 95.7), and the apparent resistance of the galvanometer
circuit was 66.6 besides the rheostat resistance. For the other setting
of the stops, the throws were much smaller (42.1, 24.6; 20.95), and the
apparent circuit resistance 70.2 ohms. In some galvanometers the ap-
parent resistance, when calculated from large throws as measured on
the calibrated scale, will be larger than when deduced from small
throws. In other galvanometers the opposite rule holds.

(G) A galvanometer of the same design as the one mentioned in (F),
but with many more turns in the coil and a resistance of 730 units,
was tested with the "magneto-inductor." This fine instrument, which
is furnished with a strong permanent magnet, has been used in making
a great number of measurements of permeability, and the very great
difference between the apparent and the real resistance (770.3) of the
circuit outside of the rheostat, illustrates strikingly the danger of
neglecting the correction for the counter electromotive force induced
in the coil during a swing. For one setting of the stops on the in-
ductor coil, the readings caused by the galvanometer throw were 66.2
or 39.7, according as the rheostat resistance was 0 or 1000; these
numbers point to a circuit resistance of 1498 units. For the second
setting of the stops, the readings were 88.2 and 52.9, and these cor-
respond to an apparent circuit resistance of 1499 units. The apparent
resistance is in this case nearly double the real resistance. For wide
ranges of throws the apparent resistance of any circuit in which this
galvanometer may be placed remains almost exactly constant, and the
instrument is wholly trustworthy when absolute measurements are to
be made, if the apparent resistance instead of the true resistance be
used. The apparent resistance of this galvanometer is naturally not
quite the same in all circuits ; when the electromotive force to be in-
duced in a coil attached to it is larger, it is of course necessary to
introduce a large extra resistance into the circuit, and this seems to
reduce very slightly the difference between the apparent and the real
resistance of the circuit; but so far as my experience goes, it has
always been about 700 units. A condenser discharge of one micro-
coulomb sent through this galvanometer gives a scale reading of
about 100 mm.

(H) A very useful instrument for hysteresis work on iron cores of
electro-magnets is the microamperemeter of Paul, which has the form of
an ordinary portable commercial amperemeter, and is of moderate cost.

1G6

PROCEEDINGS OF THE AMERICAN ACADEMY.

PEIRCE. — CORRECTION FOR COUNTER ELECTROMOTIVE FORCE. 167

The coil hangs from a single jewel, and the galvanometer is much more
sensitive than the " millivoltmeters " usually found in American labo-
ratories. The calibration curve for ballistic purposes is straight and
the scale practically one of equal parts; one of these instruments
which I have used has a resistance of about 60 ohms, and one micro-
coulomb sent impulsively through the coil causes a throw of 2 scale
divisions. This galvanometer was connected with a rheostat and the
low resistance secondary of a small induction coil, the primary of
which could be opened and shut by means of a commutator; a
rheostat in this primary circuit made it possible to change at pleasure
the amount of electricity set in motion in the secondary circuit. The
real resistance of the galvanometer circuit was about 74.9, and the
apparent resistance for all discharges up to 20 microcoulombs seemed
to be somewhere about 147. I took seventeen sets of observations with
different quantities, and got some results as low as 143.5 and others as
high as 151. The results all lay on a curious wavy line which seemed
to mark some idiosyncracy of this particular instrument.

(I) The galvanometers used in (A) to (G) were all of the compact
coil form without the inside soft iron core of the original d'Arsonval
instrument. Galvanometers of this latter type, however, have their
own advantages, as is well known, and are of course in very common
use in commercial amperemeters and voltmeters and in laboratory
mirror instruments of moderate sensitiveness for use in bridge work
and in measuring ballistically condenser charges. As an extremely
satisfactory representative of this class I chose one of the Leeds and
Northrup Company's " Type H Galvanometers," of which there are
several in the Jefferson Laboratory. The calibration curve of this
instrument for throws due to condenser discharges is nearly straight,
for quantities up to about 4 microcoulombs ; the throw due to 1 micro-
coulomb being about 3.2 cm., whatever the resistance, up to 240,000
ohms, in the discharge circuit. A battery the electromotive force of
which was about 8 volts was made to charge — through a resistance
large enough (2000 ohms) to prevent possible polarization — a set of
standard condensers, which were afterwards discharged through the
galvanometer, and the throws corresponding to capacities of 0.1, 0.2,
0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.00 microfarads, were about 2.75, 5.49,
8.21, 10.99, 13.82, 16.71, 19.70, 22.80, 26.02, 29.37. The "magneto-
inductor " and rheostat were attached to this galvanometer, and, with
the stops on the inductor rod in certain fixed positions, the throws of
the moving coil as measured on the scale were 15.81, 13.33, 9.76, 8.19,
or 7.05, according as the rheostat resistance was 0, 300, 1000, 1500, or
2000. The first of these numbers in connection with each of the

168 PEOCEEDINGS OF THE AMERICAN ACADEMY.

others gives the four values 1613, 1613, 1612, 1610 for the apparent
resistance of the galvanometer circuit. These results, which agree
wonderfully with each other considering the slight uncertainty in the
readings, differ widely from the true resistance of the circuit, which
was 531. If, when the rheostat resistance was zero, the galvanometer
coil had been held still, the whole quantity of electricity set in motion
in the circuit when the inductor coil was moved between its stops
would have been more than three times the actual flux (rather less
than 5 microcoulombs) when the coil was allowed to swing. This fact
illustrates the magnitude of the error which might be made in a per-
meability measurement if the true resistance of the circuit instead of
the apparent resistance were used. As is evident from the numbers
given above, the apparent resistance is nearly independent of the
actual resistance in the circuit when the impulse is constant and
comes from a given source, but when the character of the impulse is
changed the apparent resistance changes slightly also sometimes, and
in a manner to be determined for each instrument by experiment.
For a certain impulse which caused a throw of 8.52 cm., as indicated on
the scale of the galvanometer just mentioned, the apparent resistance
of the circuit was about 1704.

In such ballistic magnetic measurements as allow more than one
observation at each stage of the experiment, it is possible, by alter-
nately introducing and taking out of the circuit a known resistance
of suitable value wound non-inductively, to determine the apparent
resistance of the galvanometer circuit for each impulse. In other
cases it is feasible to put into the circuit once for all such a large
resistance, say 200,000 ohms, that changes in the apparent resistance
of the circuit and changes in the inductive impulses become relatively
unimportant. So far as my experience goes, a given instrument, as
was to be expected, holds its apparent resistance for a given impulse
unchanged for an indefinite time.

If a condenser discharge be sent through a d'Arsonval galvanometer
which has no electromagnetic damping other than that which accom-
panies currents in its own coil, the form of the curve which shows
the position of the swinging coil as a function of the time is hardly
affected at all by the introduction of a large inductance or a resistance
of several thousand ohms into the discharging circuit ; but if the con-
denser be displaced by a magneto-inductor of small resistance, the
damping is much increased and the shape of the curve is much altered.
Figure 1, in which the horizontal divisions represent seconds, shows
a careful copy (MOPQN) on a small scale of a large photographic
record of the excursion of the coil of a certain d'Arsonval galvanometer

PEIRCE. — COKRECTION FOR COUNTER ELECTROMOTIVE FORCE. 1G9

of short period, when a very sudden impulse from a magneto-inductor
was sent through it ; the curve starts very abruptly at 0. Figure 2 is
a photographic reduction, on the same scale as that of the other figure,
of the record, just as it was removed from the drum, of an excursion
of the same galvanometer when a condenser discharge was sent through
it. The straight line through K represents the zero position of the
coil ; the curve begins at X, but not so abruptly as before. When the
paper was on the drum, the points A, B and the points F, G fell to-
gether. It will be noticed that the time of the first swing of the coil
on one side of its zero is nearly the same, about 2.34 seconds, in both
diagrams.

Thb Jefferson Laboratory,
Harvard College, Cambridge, Mass.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 9. — July, 190G.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

A SIMPLE DEVICE FOR MEASURING THE

DEFLECTIONS OF A MIRROR

GALVANOMETER.

By B. Osgood Peirck.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

A SIMPLE DEVICE FOR MEASURING THE DEFLECTIONS
OF A MIRROR GALVANOMETER.

By B. Osgood Peikce.

Presented April 11, 1906. Received May 25, 1906.

For a good many years we have used in the Jefferson Laboratory,
to determine the deflections of mirror galvanometers and other similar
instruments, a simple form of tubeless telescope, which, at first in-
tended for students only, has proved in its way very convenient, and
has been adopted for some standard fixed instruments, because it is
not easily put out of adjustment after it has once been properly set up,
and because the scale image is so large and clear that a prolonged use
of the device does not involve the eye strain which most reading
telescopes would cause.

B

Tm

HL

M

Figure A.

In front of the plane mirror (M) of the galvanometer, instead of the
usual cover glass, is placed (Figure A) a convex lens (A) of focal
length equal to the desired scale distance. This lens need not be
achromatic ; a spectacle lens is quite good enough. At a distance in
front of A equal to its focal length is placed a horizontal scale (S)
mounted on a thin strip of wood at least twice as wide as the scale
itself Through the middle of this strip, above the scale, is bored
a round hole (H) rather more than 20 millimeters in diameter ; just
behind the scale is stretched a fine vertical wire or silk fibre (W) to
serve as a cross- hair. Behind H and at a distance suited to its focal

174 PROCEEDINGS OF THE AMERICAN ACADEMY.

length, and to the eye of the observer, is placed another spectacle lens
(B) to serve as an eyepiece. The centre of H should lie approximately
in the common axis of A and B. A peephole (P) on this same line
is placed at such a distance behind B, — which may conveniently have
a focal length of 12 or 15 centimeters — that B's aperture shall appear
wholly filled with a large, clear, uncolored image of the scale, with the
wire W running vertically across it. The proper distance between A
and S is determined by making the parallax of W across the lines of
the scale, when the eye is moved sidewise across the peephole, to
disappear : when this distance has once been found, the scale is firmly
clamped in position. The distances between S and B and between B
and P may be adjusted by every person to please himself, though it is
usually possible to fasten P securely in a suitable position and to move
B only to fit the eyes of different observers. It is important to notice
that if the distance between the eye-lens B and the peephole P is not
properly chosen, only a small round portion of the image of the scale
will be seen, not nearly large enough to fill the aperture of B, and this
will appear to move about in a distressing manner, when the eye at the
peephole is moved slightly. When the simple adjustments have been
properly made, however, the eye need not be pressed close to the peep-
hole, for the deflections of the galvanometer can be accurately and
easily read whether the eye is one inch or four or five inches behind
P. It is not necessary to close the unused eye, for the field should be
extremely bright and clear ; the observer is, of course, looking at a
life-size image of the scale at a distance PH from the peephole, and it
is easy to get any desirable magnification of this image by a proper
choice of the eye- lens. Ordinary astigmatism on the part of the
observer's eye can be partially corrected by a suitable spectacle lens
at B. One slight drawback to the use of this reading device, where
space is limited, is the fact that the eye will generally need to be 25 or
30 centimeters behind the scale. When it is desirable to do so, the
eye-lens, B, may be mounted in a tube which slips over the tube which
carries the peephole.

Figure 1 shows one form of the arrangement just described, mounted,
for students' use, with a mirror amperemeter on a wooden frame.
Several adjustments are here provided for, so that difterent instruments
may be used on this frame. Figure 2 shows the scale and eyepiece as
mounted on a brass rod, by Mr. J. Coulson, and Figure 8 represents a
convenient way of using the device with a wall galvanometer.

The Jkfferson Physical Larouatory,"
Hauvaku University.

Peirce — Deflections of Mirror Galvanometer.

Fig. 1.

Fig. 2.

^|!1 WP

Fig. 3.

Proc. Amer. Acad. Arts and Sciences. Vol. XLII.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 10. — August, 1000.

CONTRIBUTIONS FROM THE CKYPTOGAMIC LABORATORY OF
HARVARD UNIVERSITY. — LXIII.

Oy THE CYTOLOGY OF THE ENTOMOPHTHORACEAE.

By Lincoln Ware Riddle.

With Three Plates.

CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORY OF
HARVARD UNIVERSITY. — LXIII.

ON THE CYTOLOGY OF THE ENTOMOPHTHORACEAE.
By Lincoln Ware Riddle.

Presented by W. G. Farlow, May 9, 190G. Received May 14, 1906.

Introduction.

The Entomophthoraceae constitute a small, and, in some ways,
peculiar family of Phycomycetes, including, according to Schroeter's
arrangement in Engler & Prantl, seven genera. Of these seven genera,
we have more or less knowledge of the nuclear conditions in four. In
Conidiobolus (Brefeld, '84) we know only that the hyphae are non-
septate in the early stages, but in the older stages break up into
short sections (hyphal bodies) which are multi-nucleate. Basidiobolus
(Eidam, '87) is perhaps the best known of the genera from a cytological
point of view, chiefly on account of the work of Fairchild (97), although
the papers of Raciborski ('96), Lowenthal (:03), and Woycicki (:04)
are also to be mentioned. The hyphae are here septate, dividing the
fungus into cells, which are typically uni-nucleate ; the conidia also
possess single nuclei, derived directly without division from the parent-
cells. The zygospore is formed by the fusion of the nuclei of two
adjacent cells, this process being preceded, however, by the production
of two beaks on the fusing cells, with a simultaneous division of the
two gamete-nuclei so that a daughter-nucleus is cut off in each beak,
while the other two daughter-nuclei enter the young zygospore and
sooner or later fuse. Raciborski ('96") and Fairchild ('97) have both
described the division of the nucleus of Basidiobolus by a mitotic
method.

The two remaining genera, upon which a certain amount of cyto-
logical work has been done, are Empusa and Entomophthora, all
the species of which are parasitic on the larvae, pupae, or imagines of
various insects, and resemble one another in their general life-history.
For the general morphology of these genera reference may be made to
the account given by Thaxter (88) in his monograph of the North

VOL. XLII. — 12

178 PROCEEDINGS OF THE AMEllICAN ACADEMY.

American species. It was at Professor Thaxter's suggestion that the
present study of the cytology of certain species of these two genera
was taken up, in the hope of adding to our somewhat imperfect
knowledge of this, and especially, of ascertaining the relation of the
conditions involved in the formation of the resting-spores to the
conditions in other Phycomycetes.

The first mention of the nucleus of Empusa is found in a paper by
Maupas, published in 1879. By staining with picrocarmine, he was
able to differentiate the nuclei, which, if seen by earlier observers, had
been considered to be vacuoles, and to show that the hyphae of Empusa
contain a large number of " petits nuclei, d'un diam^tre d'environ
4 microns." The next paper was that of Vuillemin ('87), who worked
with material of Entomoj)hthora gleospora, which was stained in haema-
toxylin but was not sectioned ; he describes the relatively large nuclei
(10 microns in diameter) regularly spaced in the hyphae, one nucleus
migrating without division into each conidium. Vuillemin made out
the presence of chromatin contents in the nucleus, but found no nucle-
olus. In 1899 appeared a preliminary note, soon followed by the
complete paper, by Cavara, describing the conditions in the hyphae and
conidia of Empusa Muscae and Entomophthora Delpinlana, including
also an incomplete account of the azygospores of the latter, Cavara's
paper was marked by an important technical advance, inasmuch as he
used microtome-sections with the most favorable stains. The follow-
ing year Vuillemin (-.00) published another paper on Entomophthora
gleospora, describing the behavior of the nuclei in the formation of the
azygospores, and including a theoretical discussion of certain points
concerning the relationships of the genera of the Entomophthoraceae.
These last two papers will be discussed in some detail in connection
with the results here presented on the cytological processes in several
species of Empusa and Entomophthora.

Material and Methods

In his "Monograph of the Entomophthoreae of the U. S." Thaxter
('88) combined the species usually separated into Empusa and Ento-
mophthora in one genus under the name Empusa, considering that
the simple or divided character of the conidiophores, and the presence
or absence of rhizoids were features too inconstant to allow the separa-
tion of the species into two genera. Since, however, he has not been
followed in this procedure by other writers, and since, further, Cavara
(99'') has pointed out the importance of the fact that in the species
put in Empusa the conidia are typically multi- nucleate, while in those

RIDDLE. — UN THE CYTOLOGY OF THE ENTOMOPIITHORACEAi:. 171)

species put in Entomophthora, they are typically un' -nucleate, it seems
best to consider them as two distinct genera.

The results given in this paper are based upon a study of preparations
from the following species.

1. Emimsa Grylli, Nowakowski, on Hyphantria larvae (the "Fall
Web-worm "), and on the larvae of Spilosoma.

2. Entomophthora Americana, Thaxter, on the imagines of Musca sp.
and various other large flies.

3. i.'Uso an undescribed form closely related to E. Americana, found
by Professor Thaxter in various localities in New England, and called
in this paper Entomophthora "a'." The form "a-" resembles E. Amer-
icana in hosts and in conidia, but differs from it in the zygote, the
epispore of which is smooth in Americana, but is furnished with bullate
processes in Entomophthora "^." (See Figure 16.)

4. Entomophthora echinospora, Thaxter, on the imagines of Sapro-
myza (a small yellow-winged iiy).

5. Entomophthora Geometralis, Thaxter, on the imagines of a
geometrid-moth.

6. Entomophthora rhizospora, Thaxter, on caddis-flies.

7. Entomophthora Et'esenii, Nowakowski, on a species of Aphis.
Most of the material was fixed in 0.75 % chrom-acetic acid, which

gave satisfactory results, except for the more mature stages of the
resting-spores, when it became necessary to use hot sublimate-acetic.
Flemming's weaker solution was also tried, but seemed to be no
improvement over the chrom-acetic mixture. It is worthy of notice,
however, that material gave excellent preparations after being left in
Flemming's for some weeks (cf. Chamberlain, : 01, p. 27) ; the figures
in Plate I illustrating mitosis were drawn from such material. Small
pieces of the hosts infected with the fungus were imbedded in paraffin
by the usual procedure, and sections were cut either tliree or six
microns in thickness.

In staining, safranin-gentian-violet gave decidedly the best results.
The use of orange G in connection with these stains seemed to have
no added advantage. Heidenhain's iron-alum-haematoxylin was also
tried, but was a decided failure, as the stain showed too great affinity
for the general cell-contents. Unless otherwise stated the preparations
from which the plates were drawn were fixed in chrom-acetic and stained
in safranin-gentian-violet.

180 proceedings of the american academy.

Entomophtiiora.
Nucleus.

The nucleus of E. Americana may be taken as typical of the genus.
The resting-nucleus varies in diameter from five to ten microns, with
an average of six. A successful stain gives a beautiful differentiation of
the nucleus and shows its structure in considerable detail (Figure 1).
The nuclear membrane is sharply defined, taking a much darker stain
than the rather faint gray-blue of the cytoplasm. Within the nucleus
there is a relatively small nucleolus, which stains red with the safranin-
gentian-violet combination. As a rule, the nucleolus is single, but in
some cases two or three may occur, when they are correspondingly
smaller (Figure 13), while in other cases the nucleolus may be altogether
absent (Figure 16). Around the nucleolus and occupying a large part
of the nuclear cavity occurs the chromatin, in the form of densely
packed granules. These usually appear evenly granular, but at times
this even appearance is much less marked, and the chromatin may
occur in the form of a fine meshed network (Figure 12). The chromatin
in the resting-nucleus stains deeply with the gentian-violet.

The structure of this nucleus appears to be quite typical, and
certainly offers no support to the statement of Cavara (99) that " the
structure of these nuclei is quite singular, and perhaps has no counter-
part in those of any other plants, with the exception of the Saccharo-
mycetes . . . the nuclei of which recall very strongly those of the
Entomophthoreae." A comparison of the account of the nucleus of
the yeast given by Wager ('98), which is quoted by Cavara, with the
material of the present study fails to suggest the slightest similarity
in the two cases. Cavara further says, " It appears that the process
by which multiplication of the nuclei is effected must be ascribed to
division by fragmentation or to a modification of this which is tran-
sitional to mitotic division." The present study shows that the nu-
cleus of Entomophthora divides by a well-developed process of mitosis.

The first indication of the approach of nuclear-division is to be
seen in the gradual loss of the dense, evenly granular condition of
the nucleus. The chromatin becomes less densely distributed, while the
granules are seen to be fewer and larger. This is followed by the
gathering of more and more of these granules in the central region of
the nucleus, which then shows a dense central mass of large chromatin-
granules surrounded by a clear area where a few scattered granules
occur, and linin-fibres are plainly visible (Figures 23, 24). Meanwhile
a change in staining-reaction has taken place, the granules retaining

RIDDLE. —ON THE CYTOLOGY OF THE ENTOMOPHTHORACEAE. 181

more and more of the safranin, so that the larger granules show a
decided red. These granules then become aggregated into a definite
number of spherical chromosomes (Figures 2-6). The organization of
the chromosomes thus appears due to the direct aggregation of the
granules, no spireme stage having been observed.

During this process of aggregation the nucleolus has taken up a
position near the centre of the nucleus ; but with the formation of the
chromosomes the nucleolus is no longer distinguishable, since it is
identical in size, shape, and staining, with the chromosomes. There
is also no difference in behavior during the later stages of division.
It must therefore be concluded that the so-called nucleolus of Ento-
mophthora is in reality a chromatin-nucleolus, or karyosome. This
karyosome does not contain, however, all the chromatin-content of the
nucleus, as has been described by Wolfe (:04) for Nemalion, and by
Mitzkewitsch ('98) for Spirogyra ; on the contrary, it is equivalent to
a single chromosome. The total number of chromosomes in the
nucleus of E. Americaim (including this "nucleolar chromosome")
appears to be eight. This was seen clearly in many cases, and is
illustrated by Figure 6 and by the lower daughter-nucleus in Figure 8.
"VVe have apparently in this species a condition where one of the
chromosomes persists during the resting-stage of the nucleus as a
chromatin -nucleolus. The writer has been unable to find anything
comparable to this described for plants, but among animals Montgomery
('98) has described a similar condition in the spermatogenesis of
Pentatoma.

The organization of the spindle in Entomophthora shows interesting
conditions. It is always intranuclear and develops in the following
manner. As the chromatin-granules draw toward the central region of
the nucleus, they leave evident in the outer clear zone, numerous
linin-fibres radiating in all directions from the central aggregation of
chromatin (Figure 4) and running to the wall of the nucleus, which
persists through all stages up to the telophase. It is highly probable
that the chromatin-granules were, in the resting-period, distributed
along these linin-fibres, which become evident, however, only when the
granules draw toward the centre. The linin-fibres would thus be
attached to the chromosomes by their proximal ends. The fibres, at
first radiating in all directions, tend to separate into two groups, which
gradually migrate toward the respective poles of the now somewhat
drawn-out nucleus (Figure 5). These fibres form the spindle of the
mitotic figure, which is thus derived wholly from the linin, and is
therefore strictly intranuclear in origin and position (Figure 7). In-
tranuclear spindles have been described for a large number of plants

182 PROCEEDINGS OF THE AMERICAN ACADEMY.

(see Davis, : 04, Am. Naturalist, vol. xxxviii, p. 435, and literature
there cited). Stevens (:03) has described the origin of the spindle
from the linin in Synchytrium, but his material was apparently less
favorable for the exact determination of the process. In Phyllactinia,
Harper (: 05) has shown that the spindle-fibres of the mitotic figure are
identical with the linin -fibres of the resting-nucleus, but the method
of spindle-formation differs from the present case, since the process is
controlled by centrosomes in Phyllactinia. From the method of origin
in Entomophthora, it is clear that the spindle-fibres are identical with
the linin- fibres and are attached to the chromosomes permanently. In
this process of spindle-formation there is no place for centrosomes,
and no structures resembling centrosomes were seen in any case.

During this migration of the spindle-fibres the chromosomes are
grouped in a more or less definite equatorial plate (Figure 5). The typi-
cal metaphase with the e(iuatorial plate and the bipolar spindle, if it
occurs in Entomophthora, must be of very short duration, as it is the
only phase that has not been seen in examining a large number of
sections showing various stages of mitosis. The nearest approach to
the metaphase figure is the condition shown in Figure 5. The absence
of the typical metaphase may perhaps be explained if we assume that
the chromosomes split and begin to separate before the spindle becomes
definitely bipolar. The next older stage of mitosis seen in the prepa-
rations studied, is one where the chromosomes have divided and the
daughter-chromosomes are beginning to draw apart. The spindle,
occupying the entire nuclear-cavity, elongates at this time, and the
daughter-chromosomes are clearly half the size of those in the equa-
torial plate ; this stage (Figure 7) is unmistakable and was met with
repeatedly. As the daughter-chromosomes reach the poles the wall of
the nucleus becomes more rounded at these points. The chromosomes
remain very clear up to a late stage, and eight could often be counted.

Two methods occur in the reconstruction of the daughter-nuclei. In
the first method, a vacuole appears between the two daughter-nuclei,
and the spindle-fibres in this region break down, leaving only a few
granules (Figure 9). The old wall of the mother-nucleus persists up
to this time, connecting the two daughter-nuclei. This old wall forms
the walls of the daughter-nuclei, except on the side toward the vacuole,
where new walls are laid down, probably by the plasma-membrane,
bordering the vacuole (cf. Lawson, : 03). The portion of the old wall
connecting the daughter-nuclei now disapjieai's and the latter draw
apart freely. The second method is much less common than the first,
but was met with several times. The portion of the wall of the
mother-nucleus and the spindle-fibres connecting the daughter-nuclei

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITUORACEAE. 183

draw apart (Figure 10), giving a very characteristic dumbbell-shaped
appearance, similar to that figured by Stevens (: 01) in Albugo. The
entire wall of the daughter-nuclei in this case would be formed from
the wall of the mother-nucleus. Whichever method is followed, the
daughter-chromosomes remain more or less visible until after the wall
is completed, when they fragment and become redistributed in the form
of granules. Owing to the smaller size of the nuclei and to the den-
sity of their contents and to their strong affinity for stains at this
time, it was found impossible to follow the process in detaih But it
is not improbable that the process is the reverse of that followed in
the organization of the chromosomes, in which case the fragmentation
would be accompanied by a redistribution of the chromatin over the
persistent linin-fibres.

To sum up : the process of mitosis in Entomophthora shows a chro-
matin-nucleolus ; an organization of chromosomes by the aggregation
of granules, without the intervention of a spireme-stage ; the forma-
tion of a typical, intranuclear, bipolar spindle, without centrosomes,
directly from the linin-fibres, which retain their connection wath the
chrosomomes throughout mitosis ; and, in the daughter-nuclei, a redis-
tribution of the chromosomes in a granular form over these fibres.^

Conidia.

The conidia of the following species have been examined and found
to agree in the essential details : E. Americana, E. Geotnetralis, E.
echinoapora, E. rhizospora, E. Fresenii As an illustration of the devel-
opment and structure of the conidia in these species, the process may
be described as seen in E. Geometralis.

About the time of the death of the host the hyphae break up into
short multi-nucleate portions known as hyphal bodies (Thaxter, '88).
The young hyphal body is a thin-walled structure, the cytoplasm of

>■ Since tlie completion of this worii, two papers have appeared by E. W. Olive,
under the general title, " Cytological Studies on the Entomophthoreae " (Botani-
cal Gazette, 41, 192-205 and 229-258, with pis. 14-16). The first paper presents
a discussion of certain points in the life-history of various species of Empusa,
in particular a new species, E. Sciarae, with a general confirmation of the results
of previous workers in regard to the details of conidium formation. The second
paper discusses cell- and nuclear-division. Olive finds tliat cell-division takes place
through the entrance of a ring-shaped cleavage-furrow. The account of nuclear-
division is in striking contrast to the conditions seen in the course of the present
investigations, so mucli so that a close comparison is impossible. Olive describes
what he calls a " primitive mitosis " resembling that of the lower Protozoa, a pro-
cess controlled by " intranuclear centrosomes " and without definitely organized
chromosomes.

184 PROCEEDINGS OF THE AMERICAN ACADEMY,

which shows a more or less definite structure, which Cavara ('99) has
considered to be reticulate, but which, in the preparations studied, is
distinctly alveolar. This difference in appearance may be due to
different nutritive conditions, or more probably to difference in fixa-
tion. The nuclei are relatively few, and show, as a rule, regular spac-
ing. Each hyphal body sends up a long hypha to the surface of the
body of the host. Into this hypha pass a varying number of nuclei.
In the conidiophore, as this hypha may be called, the nuclei attain
their greatest size (Figure 19), owing, in all probability, to the active
metabolism necessary in connection with the formation of the conidia.
The nuclei in the conidiophore, as in the hyphal body, show a strik-
ingly regular spacing, and in the older portions a septate condition is
occasionally to be seen, these septa cutting off mostly bi-nucleate cells
(Figure 17). At the top of each branch of the conidiophore the cyto-
plasm becomes much denser, showing an upward pressure and conden-
sation at that point. Under this pressure a small protuberance soon
appears, forming the young conidium, into which passes the dense
cytoplasm (compare Empusa, Figure 24). A single nucleus enters the
young conidium, becoming smaller and denser during its passage. The
conidium is then cut off. There is never any nuclear-division during
this process, and the single nucleus of the conidium comes directly
from the conidiophore. The mature conidium (Figure 18) is a com-
paratively thin-walled structure, densely filled with very fine-meshed
cytoplasm and with a single much condensed nucleus.

Zygospores.

The formation of the zygospores has been studied by the writer in
E. Americana, and the results there obtained have been confirmed by
a further study of E. echinospora and E. Geometralis. There has been
hitherto no account of the cytological processes involved in the for-
mation of sexual resting-spores in any of the genera of the Entomoph-
thoraceae, with the exception of Basidiobolus, in which the conditions
have been generally recognized as peculiar and difficult to bring into
relation with the processes known in the other Phycomycetes.

Entomopkthora Americana shows two methods of zygospore forma-
tion. In the first case two hyphal bodies fuse at a point near their
tips (Figure 12); the young zygospore then buds out at this point of
fusion, in a manner similar to that seen in Piptocephalis, among the
Mucorales. In the second case, the fusion of the two hy])hal bodies is
distinctly lateral (Figure 11), forming what may be compared to an II
with a very short bar. The young zygospore in this case buds out
from one of the gametes, at a point usually far removed from the point

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITIIORACEAE. 185

of fusion. This condition is comparable to that seen in the case of
Spicephal/'s nodosa (compare description by Thaxter, '97).

In both of these methods, however, the essential cytological condi-
tions are the same. The two hyphal bodies fuse, the wall breaking
down between them, and the cytoplasm becoming completely con-
tinuous, so that no line of fusion is discernible. The wall near the
point of fusion, in the first case, or the wall of one of the hyphal bodies
at some other point, in the second case, then swells, and this swelling,
under the pressure of inflowing protoplasm, continues until a definite
ampulla is formed. The wall of this ampulla is only slightly thicker
than that of the hyphal body irom which it is derived, and forms, as
will presently be shown, the epispore of the zygote. Into this ampulla
pass all the nuclei of both the fusing hyphal bodies (see Figures 11-13).
It appears also that most, if not all, of the cytoplasm also passes into
the young zygospore. Figure 1 1 shows the much vacuolated cytoplasm
of the hyphal bodies ; and Figures 13 and 14 show young zygospores
attached to empty hyphal bodies.

The fusing hyphal bodies are accordingly multi-nucleate structures,
the entire nuclear and cytoplasmic contents of which pass into the
young zygospore. The hyphal bodies are therefore strictly gametes,
and since they are multi-nucleate, are certainly to be considered coeno-
gametes. Since the coenogamete is a type of sexual organ which has
been shown by Davis (=00), Stevens (=01), and others to be character-
istic of the Phycomycetes, the establishment of its occurrence in the
Entomophthoraceae is a matter of great importance.

After the entire contents of the two gametes have passed into the
young zygospore, the latter is cut off by a cross-wall. The exact
method of the formation of this wall has not been determined, but
stages, such as are shown in Figure 14, prove that the zygospore is not
abjuncted by a process of constriction, as is the case with the conidio-
spore. At this time the zygote is a spherical body surrounded by a
single thin wall. The cytoplasm is alveolar, and the relatively few
(probably not more than eighteen) large nuclei are irregularly placed,
with no apparent definiteness of arrangement. No fusion of these
nuclei has taken place up to this period of formation.

The next process of interest in the development of the zygote is the
formation of the thick endospore wall. As has been mentioned above,
the epispore is derived directly from the wall of the hyj)hal body. The
endospore, however, does not appear until after the zygote is cut off by
a cross -wall and the old walls of the hyphal bodies have disappeared.
The first sign of the formation of the endospore is the marked increase
of vacuolation in a zone just inside the epispore (Figure 15). On the

186 PROCEEDINGS OF THE AMERICAN ACADEMY.

inner side, this clearer zone is marked off by a densely granular region.
The conditions at this period suggest strongly the periplasm found in
so many Phycomycetes. This appearance, however, may be accidental
and without special significance. From a study of such stages as are
illustrated by Figure 15, it is evident that the granular cytoplasm is
being gradually transformed into the clear material of the mature endo-
spore (Figure 16). The endospore in Entomophthora thus appears to
be formed, not as a secretion of the outer plasma-membrane, but by
a direct transformation of the outer zone of cytoplasm, this transforma-
tion evidently involving more than the plasma-membrane itself, and
possibly representing a primitive type of periplasm.

After this formation of the endospore, the zygote enters into a rest-
ing period which lasts until the following summer. Sections cut from
material fixed three months after formation show that no fusion of the
nuclei has taken place up to that time (Figure 16). Whether or not
fusion of the nuclei in pairs takes place at the time of germination, as
we might expect, it has been impossible to determine, owing to the
difficulty of germinating the zygospores under artificial conditions.
That the process of zygospore formation thus given for E. Americana
is confirmed in full by E. echhiospora may be seen by comparing Fig-
ures 11 to 16 with Figures 20 to 22.

It will be seen from the foregoing description that the processes con-
nected with the formation of the sexual resting- spores in Entomoph-
thora are closely comparable with the corresponding processes in the
Mucorales, in so far as they have been made known by the work of
Gruber (:0l) on Sporodinia. Entomophthora has, in common with
Sporodinia, coenogametes (multi-nucleate sexual cells) which are of a
simple type, inasmuch as there is no differentiation of the contents
and all of the nuclei function as gamete-nuclei.

Empusa.

Material of E. Gryll'i on two different hosts furnished the preparations
upon which was based the study of this genus. Under E. Griilli, Now.,
Thaxter ('88) included as a synonym E. AuUcae, Reichhardt (in Bail,
'69) first described on Euprepia aulka, but also occurring on other
hosts, and especially in the United States, on the larvae of Spilosoma.
Several authors (Cohn, '75 ; Schroter, '86 ; Lindau, '97) have kept this
as a distinct species. The writer, in the course of the present study, has
seen no such differences as should be considered of specific rank, and
therefore prefers to follow Thaxter and consider both of the above forms
as true Empusa GrijlU, Nowakowski. The results here given are based

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITIIORACEAE. 187

on material on the Spilosoma larvae ; but these have been confirmed in
every particular by material from the larvae of Hyphantria,

Nucleus.

The nuclei of Empusa are smaller (average diameter 4 microns),
more numerous in each hyphal body than in Entomophthora, and
show no regularity of spacing (Figure 23). The smaller size of the
nucleus makes it a less favorable object for study ; so far as has been
observed, however, the structure of the nucleus of Empusa agrees
perfectly with that of Entomophthora. Although caterpillars killed
by E. GrylU were fixed at various hours of the day and night, in
various conditions of moisture, and at longer and shorter periods after
death, no nuclear-divisions were seen in any case. It is therefore
impossible to state whether or not the details of this process also agree
with those in Entomophthora, as we should expect from the close
relationship of the two genera.

Conidia.

The general process of the formation of the conidia in Empusa
(Figures 2-4 and 2o) is similar to that already described for Ento-
mophthora. There are a few differences, however, the most important
of which is the fact that the conidia of Empusa are multi-nucleate
structures, and the conidiophores are unbranched.

Some time before the death of the host the hyphae break up into
hyphal bodies in the usual manner ; and, at the time of death, each
hyphal body sends up a conidiophore. In this case, however, the
conidiophores and consequently the conidia are much larger than in
Entomophthora, conditions correlated with the absence of branching
in the conidiophore, and with the large amount of nuclear substance
in the multi-nucleate conidium. The nuclei in the conidiophore are
very numerous, and show no evidence of regular spacing (Figure 24).
There is the usual accumulation of dense cytoplasm in the tip of the
conidiophore as it swells to form the conidium. It will be recalled
that in Entomophthora a single nucleus passes into the young conid-
ium at this time. In the case of Empusa, a large number of nuclei
(about twelve to fifteen) pass in and the conidium is cut off. No nu-
clear-division takes place during this process of conidium-formation.

After the discharge of the conidium, the nuclei left in the conidio-
phore degenerate, certain stages of this degeneration presenting a
misleading resemblance to the prophase of nuclear-division. The
nuclei can, however, be followed through all the stages of the process,
ending as vacuoles containing a few oil-like globules.

188 PROCEEDINGS OF THE AMERICAN ACADEMY.

The centre of the mature conidium is pretty constantly occupied by
a single, large, well-defined vacuole around which the numerous, much
condensed nuclei are most often clustered (Figure 25).

The conidia of Empusa Grylli are, then, multi-nucleate structures
and corroborate the statement of Cavara ('99*), based on his examina-
tion of E. Muscae, that a multinucleate conidium is characteristic of
the genus Empusa, while, as the same author shows in Entomopkthora
Delpiniana^ and as has been shown above for a number of other species
of the genus, Entomophthora has constantly a uni-nucleate conidium.
The conidia of Empusa are also to be compared to those of Albugo and
other genera of the Peronosporales, where, in all forms which have been
examined (Ruhland, :03), the conidia are multi-nucleate. But the
absence of a nuclear-division preceding conidium-formation in Empusa
is in marked contrast to that of Albugo, a difference to be explained
by the fact that, while in Albugo a series of conidia are formed, in
Empusa but a single conidium is formed from each conidiophore.

, Azygospores.

Just as the hj^hal bodies and conidia of Empusa are multi-nucleate
structures, so also we find multi-nucleate conditions in the azygo-
spores. This multi-nucleate condition appears from the first formation
stages, and these nuclei undergo neither divisions nor fusions. As
these observations are not in accord with those of previous workers on
the azygospores of Entomophthora, namely Cavara ('99) on E. Del-
pmiana and of Vuillemin (:00) on E. gleospora, it will be well to
examine their results before describing the development of the azygo-
spores in Empusa.

In Entomophthora Delpiniaria, a species in which the hyphae do
not break up into hyphal bodies, Cavara observed two sorts of struc-
tures which he called azygospores. First, a thick-walled, intercalary
organ with granulated cytoplasm which shows clear reticulations, the
joints of the meshes being occupied by " chromophilous granules " ;
this organ contains no definite morphological nucleus, but Cavara
regards the " chromophilous granules " as a diffused nucleus. Such
an intercalary organ appears not to have been seen by any other
workers. Certainly in the present study no structures have been seen
resembling Cavara's description, so that an interpretation of these
curious conditions is here out of the question. Secondly, and more
commonly, Cavara finds an organ of acrogenous formation ; a hypha
swells at the end into an ampulla ; into this ampulla passes a single
nucleus ; a cross-wall is then formed cutting off the spore, which is,
therefore, at this time, uni-nucleate ; this single nucleus divides to

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPHTHORACEAE. 189

four, six, eight, and perhaps more, since Cavara was unable to follow
the process in its further development.

Vuillemin (: 00) states that the early development of the azygospores
of Entomopldhnra gkospora is the same as in the acrogenous azygo-
spores described for E. Delpiniana. There is an ampulla into which
passes a single nucleus, which after the formation of a cross-wall,
divides to four, six, eight, and then to sixteen. It appears, however,
that this number is by no means constant, as Vuillemin records finding
twelve, fourteen, fifteen, seventeen, or eighteen, which he supposes to
be due to the failure of some of the nuclei to divide, or to a greater
number of divisions than usual. After the nuclei have reached this
number, there occurs successive fusion in pairs till the number is
reduced to two ; the azygospore rests in this condition for some time,
but these two also ultimately fuse so that the mature azygospore is
once more uni-nucleate.

Vuillemin gives no figures for any of these numerous nuclear-divi-
sions and nuclear-fusions. His evidence seems to be based upon the
different numbers of nuclei in different cases and in their smaller size
when the number is greater. The number of the nuclei, however,
according to the results to be described presently, is closely dependent
upon the number in the hyphal body from which the azygospore is
formed. And the difference in size, apart from individual variations,
within restricted limits, which seem to be quite common (cf nuclei in
Figure 26), might easily be explained by the maintenance of the equi-
librium of nucleo-cj^oplasmic relations, the importance of which has
been shown by the recent work of Gerassimow (:01, -. 02, : 04), Hert-
wig (: 03), and others. As Vuillemin seems to cpnsider the conditions
described to be typical for the family, it will be well to compare the
account given above with results obtained from a study of the azygo-
spores of Empum Grylli

After the hyphae of the fungus have broken up into h}T3hal bodies,
the formation of azygospores takes place. At some point on the hyj)hal
body, not necessarily at one end, a small protuberance appears, into
which there is a flow of protoplasm from the hyphal body ; the proto-
plasm stains more densely in this region and shows pressure. On
account of this pressure the protuberance continues to expand into
a rounded ampulla, the wall of which is at first only slightly thicker
than that of the hyphal body (Figure 26). Into this ampulla gradu-
ally passes all of the cytoplasmic contents of the hyphal body, to-
gether with all the nuclei, which the hj^^hal body originally contained.
Figure 26 shows a stage where this process is under way ; and Figure
27, a stage where it is completed. It will be seen here that the young

190 PROCEEDINGS OF THE AMERICAN ACADEMY,

azygospore is a multi-nucleate structure ; and the attached empty
Lyphal body together with the absence of a cross-wall proves that this
multi-nucleate condition is brought about, not by the successive divi-
sions of a single primordial nucleus, but rather by the inclusion in the
azygospore of the entire number of nuclei which were present in the hy-
phal body. As this number is, within certain limits, somewhat variable,
the number of nuclei in the azygospore is correspondingly variable.

The next stage in the formation of the azygospore is marked by the
formation of a cross-wall, cutting off the recently formed resting-spore ;
this being immediately followed by the dissolution of the walls of the
empty hyphal body leaving the rounded azygospore, which at first
often shows the position of the cross-wall (Figure 28). The cytoplasm
is reticulated in structure, the meshes being comparatively small, and
clearly granular ; the wall is still only slightly thicker than that of the
hyphal body, but the thickening process begins immediately.

An additional piece of evidence against the occurrence of nuclear-
division within the azygospore is the fact that all of the stages de-
scribed above, from the first sign of a small protuberance up to the
fully formed spore, may be found on a single slide. Preparations of
material in which the spores had been formed from one to several days
were also studied. Yet in no case was there the slightest evidence of
nuclear- divisions. Further, the number shows no striking variation,
although it is often difficult to follow a spore through all the succes-
sive sections in which it should appear ; and, likewise, there is no
marked diminution in the size of the nuclei, such as would take place
during nuclear-division (as is shown by comparing the mother-nucleus
with the daughter-nuclei in Figures 1 to 10).

Finally, preparations were made firom azygospores, three months old
at the time of fixation. A median section of one of these is shown
in Figure 29. The thinness of the wall in this case is anomalous and
difficult to explain, since the normal procedure is for the wall to
thicken immediately after the formation of the cross-wall, the mature
azygospore having a thick wall with epispore and eudospore differen-
tiated similar to that described for Entomophthora. The appearance
of this spore, fixed three months after formation (Figure 29), will be
seen to be clearly similar to that of the newly-formed spore (Figure
28). The spore has increased in size somewhat, but with a corre-
sponding increase in the vacuolation of the cytoplasm, these vacuoles
being filled, in the living material, with oil-globules. The nuclear con-
ditions are essentially identical with those in the young azygospore,
and show clearly that no nuclear-divisions, and, likewise, no nuclear-
fusions, have taken place up to this time.

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITIIORACEAE. 191

When it is recalled that in Eatomophthora gleospora, which, as has
been mentioned, Vuiilemin considers typical, the young azygospore,
after the formation of the cross-wall, is uni-nucleate, and that the
nuclear-divisions and fusions described take place immediately, it will
be seen that here, in Empwsa Grylli, we have a very different type
of resting-spore formation — a resting-spore multi-nucleate from the
beginning and showing neither nuclear-divisions nor nuclear-fusions.

The evidence seems to indicate that the azygospore of Empusa is
more in the nature of a chlamydospore ; and the occasional substitu-
tion of an encysted hyphal body, such as is shown in Figure 30, as
a means of tiding over the winter period, is in favor of this view.

Conclusions.

In conclusion it will be well to consider what light the observations
here set forth may throw on the interrelationship of the genera of the
Entomophthoraceae, and the relationship of this family to other Phy-
comycetes. In comparing the nuclear conditions in the three genera,
which have been studied from the cytological point of view, namely
Basidiobolus, Entomophthora, and Empusa, two possible lines of de-
velopment are offered for consideration. First, it is possible that
Basidiobolus, with its uni-nucleate cells, may be a primitive type, from
which the development may have proceeded through the conditions
seen in the hyphal bodies of Entomophthora, with their several nuclei
regularly spaced, to the conditions in Empusa, where the hyphal
bodies have a large number of irregularly distributed nuclei. Or,
secondly, it is possible that Empusa is the primitive type of a series
showing progressive nuclear reduction, which reaches its highest
expression in Basidiobolus.

The first of these two views is supported by Vuiilemin in his paper
of 1900. He says: "Au point de vue cytologique, VE. glcospora
(ainsi que VE. Delphiland) forme un trait d'union entre les Basidiobo-
lus et les Empusa ; il nous montre par quelle gradation la structure
cellulaire s'est dans la sdrie des Entomophthordes pour passer ^ la
structure multi-nuclde. Cette derni^re apparait alors comme un
d(iriv(^ phylog(^ndtique de la premiere : c'est ce qui m'a depuis long-
temps sugg^rd I'id^e de la nommer une structure apocytique. Ceci
posd, nous interpreterons les vues de Raciborski en disant que la
famille des Entomophthordes chevauche sur les ArchimyctJtes et les
Phycomycfetes, qu'elle prend ses racines dans le premier groupe au
niveau des Basidiobolus, franchit la fronti^re au niveau des En-
tomophthora gleospora et Delpiniana pour s'epauouir en pleins Phyco-

192 PROCEEDINQS OF THE AMERICAN ACADEMY.

myc^tes au niveau des Empusa. Les details publies par Cavara sur la
structure de Y Empusa Muscae, details que j'ai pleinement v^rifi^s,
montrent clairement ce dernier stade de revolution apocytique des
appareils vdg^tatif et conidien des Entomophthordes." Vuillemin
thus makes Basidiobolus the primitive form for the family. But such
a primitive form should show some points of relationship to the forms
from which it has itself been derived. These points further should
be shown in connection with the sexual processes, the period of the
life-history, which is generally agreed to be of the greatest phylogenetic
importance. In connection with his views Vuillemin offers no special
form to which Basidiobolus might be directly related.

Such a line of evolution, as Vuillemin suggests, has been discussed
by Davis (: 30) in connection with his consideration of the origin and
evolution of the coenogamete. Davis says : "It is conceivable that
a uni-nucleate sexual element might become multi-nucleate perhaps
through such an increase in the protoplasmic content that more than
one nucleus would be required to control satisfactorily its activities.
This possibility has absolutely no evidence in its support. There is
no series of forms whose sexual cells pass from a uni-nucleate condition
to a multi-nucleate. There are no indications that such an evolutionary
process has ever taken place among plants."

So much for negative evidence against such a process as Vuillemin
supposes to have occurred. Let us now see what positive evidence
there is for the second of the two views stated above. The most
interesting piece of such evidence, because the most complete, is that
of the Albugo series established by Stevens ( :01) (and also quoted by
Davis (1. c.) ). Here the progressive increase in the development of
the physiologically important coenocentrum, and the corresponding
decrease in the now functionless receptive papilla indicate clearly the
line of evolutionary advance. While along with this, we have a pro-
gressive reduction in the nuclei, starting with Albugo Blltl with many
functional gamete-nuclei, through A. Tragopogonis with many poten-
tial but only a few functional, and ending with A. Candida, with its
single functional gamete-nucleus. This view may now be applied to
the conditions in the three genera of the Entomophthoraceae.

In Empusa, the originally non -septate hyphae early break up into
short segments, the hyjihal bodies, which contain large numbers of
small nuclei distributed irregularly through the plasm. The conidia
are multi-nucleate. A large number of nuclei enter the apogamous
resting-spore. In Entomophthora the hyphae usually break up into
hyphal bodies, but as has been shown above in the case of JJ. (u'onicfrcdls
and as Cavara has shown in E. IJi'lpiniana, the formation of hyphal

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITHORACEAE. 193

bodies may not take place, in which case the hyphae often become
septate. These septa cut off cells containing relatively few, regularly
spaced nuclei which from their larger size have evidently an increase
of elliciency. The tendency toward nuclear reduction has extended to
the conidium resulting in a uni-nucleate condition. The resting-
spores are formed by the fusion of coenogametes, with relatively few
nuclei, — these coenogametes being of a simple type, where all of the
nuclear material enters the zygote. In Basidiobolus the hyphae are
regularly septate and do not normally form hyphal bodies. It has been
shown, however, by Raciborski (96*) that under certain culture condi-
tions such a formation of h}T^)hal bodies may be induced. The tendency
to nuclear reduction has here reached its highest expression, resulting
in uni-nucleate cells. Accordingly the zygote is formed by the fusion
of two uni-nucleate cells, which must, however, from a phylogenetic
view-point, be considered coenogametes. The production of the peculiar
beak-cells is clearly a late specialization and makes these coenogametes
of the second of Davis's types, namely, where only a portion of the
nuclear material is functional.

If the evolutionary line thus indicated be the true one, it is reason-
able to expect that Empusa, as the primitive form, will show a possible
derivation from other Phycomycetes. The close agreement of the
methods of zygospore-formation, both as to general morphology and as
to cytological conditions, between Entomophthora and the Mucorales,
which has been pointed out above, indicates relationship in that
direction. If we consider such a form as Sporodinia, we find h}^hae
with very numerous small nuclei ; a sporangium forming a number of
uni-nucleate spores ; and zygospores formed by the fusion of primitive
coenogametes. Apogamy in this species is of frequent occurrence ;
and it is reasonable to assume that the azygospores thus formed are
multi-nucleate. Comparing with this the conditions in Empusa, we see
at once a possible line of derivation. The hyphal bodies, into which,
on account of the peculiar endophytic habit, the hyphae break, contain
many small nuclei, which are, however, less numerous and larger than
those of Sporodinia. Thaxter ('88) has already shown that the "co-
nidium " of Empusa might be regarded as a sporangium. It is clear
therefore that, just as the coenogamete is a gametangium into which
has been extended the coenocytic habit and which accordingly functions
as a unit, so the " conidium " of Empusa is a sporangium into which
has been extended the coenocytic habit and which likewise functions
as a unit. Apogamy has become constant in Empusa, resulting in the
formation of multi-nucleate azygospores. The close relationship of
Empusa and Sporodinia seems undeniable.

AOL. xr.ii. — 13

194 PROCEEDINGS OF THE AMERICAN ACADEMY.

We may now sum up the line of development indicated in this paper.

I. Sporodinia : Hyphae non-septate, with very numerous very small
nuclei. Non-sexual reproduction by a sporangium producing numerous
uni-nucleate spores. Resting-spore formed by the fusion of primitive
coenogametes with very numerous nuclei. Apogamy frequent.

II. Empusa : Hyphae breaking into hyphal bodies with numerous
small nuclei irregularly distributed. Non-sexual reproduction by a
multi-nucleate "conidium" which is morphologically a coenocytic
sporangium. Apogamy constant.

III. Entomophthora : Hyphae either breaking into hyphal bodies
after passing through a septate condition or else permanently septate,
with few large nuclei regularly spaced. Tendency toward nuclear
reduction extended to the non-sexual reproduction resulting in a uni-
nucleate coenosporangium. Resting-spores formed by the fusion of
primitive coenogametes with few nuclei. Apogamy occasional.

IV. Basidiobolus : Hyphae septate, breaking into hyphal bodies
only under abnormal conditions, with a single nucleus in each cell.
Non-sexual reproduction as in Entomophthora. Resting-spores formed
by the fusion of coenogametes of a specialized type, which through
the extension of the tendency to nuclear-reduction have become
uni-nucleate. Apogamy absent.

These three genera of Entomophthoraceae thus form a specialized
line, derived from a Mucor-like ancestry, and reaching a high stage in
the development of certain well-defined evolutionary tendencies.

Summary.

Material of the following species was studied during the present
investigation : Entomophthora Americana, E. " x," E. GeometraUs, E.
echinosjwra, E. rhizospora, E. Fresenii, and Empusa Grylli.

The nucleus of Entomophthora shows a well-developed structure.
There is a relatively small chromatin-nucleolus surrounded by a more
or less dense zone of chromatin granules. The division of the nucleus
is by a well-developed process of mitosis.

During mitosis, spherical chromosomes are organized by the direct
aggregation of the chromatin -granules, no spireme stage being present.
In E. Americana, eight chromosomes were counted with reasonable
certainty.

The linin-fibres freed by this process of aggregation separate into
two groups which migrate to the respective poles of the nucleus,
forming a typical, intranuclear, bipolar spindle, without centrosomes.

The conidia of Empusa are multi-nucleate, and of Entomophthora,
uni-nucleate. No nuclear-division is present in the process of
conidium-formation.

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITIIORACEAE. 195

The zygospores of Entomophthora are formed by the fusion of multi-
nucleate hyphal bodies, which are coenogametes of a primitive type,
since all of the nuclear material is retained in the zygote. No fusion
of the nuclei takes place during the first three months after formation.
Whether or not such fusion in pairs takes place at the time of germi-
nation it has been impossible to determine, owing to the difficulty of
germinating the zygospores under artificial conditions.

The epispore of the zygote is derived directly from the walls of the
hyphal bodies. The endospore is formed by the direct transformation
of an outer zone of the cytoplasm of the zygote.

In Empusa Grylli the azygospores are formed by the budding out
of a hyphal body. The entire nuclear and cytoplasmic contents of the
hjrphal body passes into the azygospore, which is therefore always
multi-nucleate. No division and no fusion of these takes place.

The cytological evidence suggests the derivation of the Ento-
mophthoraceae from a Mucor-like ancestry, with the extension of the
coenocytic habit to the non-sexual methods of reproduction, and with
the progressive reduction in the number of nuclei, with the increasing
efficiency of the survivors, a process beginning in Empusa, carried
further in Entomophthora, and reaching its highest expression in
Basidiobolus.

A preliminary notice of the results of the present study appeared
in Rhodora (Vol. 8, p. 67) on March 27, 1906.

The writer takes this opportunity to make a grateful acknowledg-
ment of his indebtedness to Professor Roland Thaxter, under whom
the work was begun, for invaluable assistance in the collection of
material, and for much advice ; and to Professor W. G. Farlow, under
whom the work was finished, for help in the preparation of this
paper.

Bibliography.

Bail, Th.

'69. Ueber Pilzepizootien der forstverheerenden Ranpen. Schriften d.
naturforsch. Gesel. Danzig, Vol. 2, pt. 2, pp. 1-25, pi. 1.
Brefeld, O.

'84. Conidiobolus utriciilosus und C. minor n, spp. Untersuchungen aus
dem Gesammtgebiete Mykologie, Pt. 6, p. 35.
Cavara, F.

'99*. I nuclei delle Entomophthoreae in ordine alia filogenesi di queste

piante. Bull. Soc. bot. italiana (1899), pp. 55-60.
'99''. Osservazioni citologiche sulle Entomophthoreae. Nuovo Gioniale
botauico italiano, Vol. 6, pp. 411-4GG, pi. 4, 5.

196 PROCEEDINGS OF THE AMERICAN ACADEMY,

Chamberlain, C. J.

:01. Methods in Plant Histology. Chicago, 111. 1901.
Cohn, F.

'75. Ueber eine neue Pilzkrankeit tier Erdraupen. Beitrage z. h'uA. d.
Pflanzen, Vol. 1, Pt. 1, pp. 58-84, pi. 45.

Davis, B. M.

:00. The Fertilization of Albugo Candida. Bot. Gazette, Vol. 29, pp. 297-

311, pi. 22.
-.03. Oogenesis in Saprolegnia. Bot. Gazette, Vol. 35, pp. 233 and 320,

pi. 9, 10.
-.04. Studies on the Plant Cell. Amer. Naturalist, Vols. 38, 39.

Eidam, E.

'87. Basidiobolus, eine neue Gattung der Entomophthoraceen. Beitrage z.

Biol. d. Pflanzen, Vol. 4, pp. 181-251, pi. 9-12.
Fairchild, D. G.

'97. Ueber Kerntheilung und Befruchtung bei Basidiobolus. Jahr. wiss.

Bot., Vol. 30, pp. 285-296, pi. 13, 14.
Gerassimow, J. J.

:01. Ueber den Einfluss des Kerns auf das Wachstum der Zelle. Bull.

Soc. Imp. Nat., Vol. 15, pp. 185-220, pi. A, B.
•.02. Die Abhangigkeit der Grosse der Zelle von der Menge der Kernmasse.

Zeitschr. fur allg. Physiol., Vol. 1, pp. 220-258.
:04. Ueber die Grdsse der Zellkerns. Beih. zum Bot. Centr., Vol. 18,

p. 43.
Gruber, E.

:01. Ueber das Verhalten der Zellke^-ne in den Zygospore von Sporodinia

grandis. Berichte d. Deutsch Bot. Gesell., Vol. 19, pp. 51-55, pi. 2.

Harper, R. A.

:05. Sexual Reproduction and the Organization of the Nucleus in certain
Mildews. Carnegie Inst., No. 37, pp. 1-87, pi. 1-7.
HertTwig, R.

:03. Ueber Korrelation von Zell und Kerngrosse, usw. Biol. Centr., Vol.
23, pp. 49 and 108.
Lawson, A. A.

:03. On the Relationship of the Nuclear Membrane to the Protoplast. Bot.
Gazette, Vol. 35, pp. 305-317, pi. 15.

Lindau, G.

'97. Zur Entwickelung von Empusa Aulicae,; Reich. Hedwigia, Vol. 36,
pp. 291-296.
LoTventhal, W.

:03. Beitrage zur Kenntniss.des Basidiobolus lacertae, Eidam. Archiv. f.
Protistenkunde, Vol. 2, pp. 369-420, pi. 10, 11.
Maupas, E.

'79. Sur quelques protorganismes animaux et vegetaux multinuclees.
Compte Rendus, Vol. 89, pp. 250-253.

RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITIlUllACEAE. 197

Mitzkewitsch, L.
'98. Ueber die Kerntheilung bei Spirogyra. Flora, Vol. '85, pp. 81-85,
pi. 5.
Montgomery, T. H.

'98. Spermatogenesis in Pentatoma up to the formation of the Spermatid.
Zool. Jiihrb. (Abth. Anat.), Vol. 12, pp. 1-82, pi. 1-5.

Raciborski, M.

'96*. Ueber den Einfluss ausserer Bedingungen auf die Wachstumsweise

der Basidiobolus rauaruui. Flora, Vol. 82, pp. 107-132.
'96''. Mykologische Studien : Karyokinese Lei Basidiobolus ; usw. An-
zeiger der Akad. Wissenchaften in Krakaw (18JJ6), i)p. 377-380, pi. 1.
Riddle, L. "W.

:06. Contributions to the Cj'tology of theEntomophthoraceae : Prelinunary
Communication. Rhodora, Vol. 8, pp. 67, 68.
Ruhland, "W.

:03. Studien ueber die Befruchtung der Albugo Lepigoni und einiger Pe-
ronosporeen. Jahr. wiss. Bot., Vol. 39, pp. 135-166, pi. 2, 3.
Schroeter, J.

'86. Eiitomophthorei. In Krytogamen-Flora von Schlesien, Vol. 3, p. 217.
Stevens, F. L.

:01. Gametogenesis and Fertilization in Albugo. Bot. Gazette, Vol. 32,
pp. 77, 157, and 286, pi. 1-4.
Stevens, F. L., and Stevens, A. C.

:03. Mitcsi-s in the Primal y Xucleu.s in Synchytrium decipiens. Bot.
Gazette, Vol. 35, pp. 405-415, pi. 16, 17.
Thaxter, R.

'88. The Entomophthoreae of the United States. Memoirs Boston Soc.
Nat. Hist., Vol. 4, pp. 133-199, pi. 14-21.

Vuillemin, P.

'87. litudes biologiques sur les Champignons. Bull. Soc. Sci. Nancy

(1887), pp. 1-126, pi. 1-6.
:00. Develojipement des Azygospores chez les Entomophthorees. Comptes

Rendus, Vol. 29, pp. 670^684, pi. 6.

"Wager, H.

'98. The Nucleus of the Yeast Plant. Annals of Bot., Vol. 12, pp. 499-
537, pi. 29, 30.
Wolfe, J. J.

:04. Cytological Studies on Nemalion. Annals of Bot., Vol. 18, pp. 607-
630"^ pi. 40, 41.

Woycicki, Z.

•.Oi. Einige neue Beitrage zur Entwicklungs-geschichte von Basidobolus
ranarum, Eidam. Flora, Vol. 93, pp. 87-97, pi. 4.

EXPLANATION OF PLATES.

All the figures were drawn at stage-level with the aid of an Abbe camera, and
with a Zeiss apochromatic 2 mm. objective and compensating ocular 4 (= X 600),
6(=X750), or8(=Xl000).

PLATE I.

Entomophlhora Americana.

Figures 1-10. Mitosis (X 1000).

Figure 1. Eesting-nucleus.

Figure 2. Prophase. Beginning of chromatin aggregation.

Figures. Prophase. Later stage of aggregation.

Figure 4. Prophase. Formation of the chromosomes, exposing the radiating
linin-fibres.

Figure 5. Metaphase. Linin-fibres migrating to the poles.

Figure 6. Late prophase, showing eight chromosomes.

Figure 7. Early anaphase, showing typical spindle, with the daughter-chromo-
somes being drawn toward the poles.

Figure 8. Late anaphase. The daughter-chromosomes have reached the poles ;
the lower pole shows eight chromosomes.

Figure 9. Telophase. Reconstruction of the daughter-nuclei, which are sepa-
rated by a vacuole.

Figure 10. Telophase. Separation of the daughter-nuclei by constriction.

Figures 11-14. Zygospore-formation (X750).

Figure 11. Lateral fusion of the gametes, with budding of the spore from one
of the gametes, the several nuclei of the hyphal bodies passing into the young
zygospore (form ".r").

Figure 12. Fusion of the gametes by their tips, with budding of the spore at
the point of union.

Figure 13. Young zygospore before the formation of the cross-wall, with an
attached empty hyphal body.

Figure 14. The same after the formation of the cross- wall. Figures 13 and 14
show the multi-nucleate condition.

Riddle. -Entomophthoraceae.

Plate I.

.>'V'XXi«.-.r

'.«:•
■&

iO-^'-f-ir::

8

v.V^.Vjf?V

Proc. Amer. Acad. Arts and Sciences. Vol. XLII.

PLATE II.

Figure 15. Entomophthora " x." Young zygospore, showing stage in the for-
mation of the endospore (X 750).

Figure 16. Entomophthora " x." Mature zygospore, three monthe after forma-
tion ; fixed in hot sublimate-acetic (X 750).

Figure 17. E. Geometralis. Septate conidiophore (X 600) ; fixed in Flemmings.

Figure 18. E. Geometralis. Mature conidium ( X 1000).

Figure 19. E. Geometralis. Large, elongated nucleus in the conidiophore
(X 1000).

Figures 20-22. E. echinospora. Zygospore-formation (X 760).

Figure 20. Young zygospore, showing method of formation.
Figure 21. Zygospore, after the formation of the cross-wall.
Figure 22. Mature zygospore, three months after formation.

Riddle. -Entomophthoraceae.

Plate 2.

Proc. Amer. Acad. Arts and Sciences. Vol. XLM.

PLATE III.

Empusa Grylli.

FiounE 23. Young hyphal body (X 750).

Figure '24. Upper portion of conidiophore, showing the formation of the con-
idiiim (X750).

Figure 25. Mature conidium (X 1000).

Figure 26. Young azygospore, showing a stage in tlie passage of the contents
of the liyphal body into the young spore (X 750).

Figure 27. Young azj'gospore, before the formation of the cross-wail, showing
the multi-nucleate condition and the attached empty hyphal body (X 750).

Figure 28. Mature azygospore, just after formation (X 750).

Figure 29. Mature azj'gospore, three months after formation, showing that no
changes in the nuclei have taken place (X 750).

Figure 30. Encysted hyphal body ; poor fixation due to the thick and resistant
wall (X 750).

Riddle.— Entomophthoraceae,

Plate 3.

Proc. Amer. Acad. Arts and Sciences. Vol. XLII.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 11. — August, 190G.

CONTRIBUTIONS FROM THE CHEMICAL LABORATORY
OF HARVARD COLLEGE.

A EE VISION OF THE ATOMIC WEIGHT OF

BROMINE.

By Gregory Paul Baxter.

CONTRIBUTIONS FllOM THE CHEMICAL LABORATORY OF
HARVARD COLLEGE.

A REVISION OF THE ATOMIC WEIGHT OF BROMINE.
By Gregory Paul Baxter.

Presented by T. W. Richards. Received May 28, 1906.

In numerous investigations in this laboratory upon the atomic
weights of certain metals, in which metallic bromides were first
titrated against the purest silver, and then the precipitated silver
bromide was collected and weighed, the relation between the silver
used in the titrations and the silver bromide obtained has yielded
data from which the atomic* weight of bromine may be calculated.
Furthermore, in all these investigations, as a check upon the purity
of the silver and bromine employed, silver bromide was synthesized
directly from weighed quantities of silver and an excess of ammonium
bromide or hydrobromic acid. Many of these results have already
been collected and discussed by Richards,^ nevertheless they are cited
in the following table together with a few more recent determinations.

From the first of these ratios the atomic weight of bromine, referred
to silver 107.930, is found to be 79.956, and from the second 79.955.

Very recently, in experiments in which silver iodide was heated
first in a current of air and bromine until the iodine was completely
displaced, and then in a current of chlorine to displace the bromine,
the ratio of silver bromide to silver chloride was determined in six
cases. From the results of these experiments the atomic weight of
bromine was calculated to be 79.953,2 if the atomic weight of chlorine
is assumed to be 35.473.*^

These values for bromine are in close agreement with those of Stas.*
In his experiments weighed quantities of pure silver and bromine were

1 Proc. Amer. Phil. Soc, 43, 119 (1904).

2 Baxter, These Proceedings, 41, 82 (1905).

3 Richards and Wells, Puhiications of the Carnegie Institution, No. 28 (1905).
* CEuvres Completes, 1, 003.

202

PROCEEDINGS OF THE AMERICAN ACADEMY.

Indirect Determinations.

1

Bromide
analyzed.

Number of
Experiments.

Analyst.

Reference.

Ratio f'i
AgBr

BaBrg

Last seven

Richards

Proc. Amer. Acad., 28, 28

57.444

2

SrBrg

Seven

«

Ibid, 30, 389

57.444

3

ZnBrg

One

((

Ibid , 31, 178

57.445

4

NiBr2

Seven

Cushman

Ibid, 33, 111

57.444

5

CoBrg

Last five

Baxter

Ibid., 33, 127

57.446

6

UBr4

Three

Merigold

Ibid, 37, 393

57.447

7

CsBr

Three

Archibald

Ibid., 38, 466

57.444

8

FeBrg

Two

Baxter

Ibid, 39, 252

57.443

9
10

CdBrg
MnBrg

Eight
Thirteen

Hines

Jour. Amer. Chem. Soc.
[28, 783
Not yet published

57.444
57.444

At

rerage, weig

jhted accordii

ig to the number of determinations .

. 57.4443

Di

RECT Determinations.

11

12

HBr
NH^Br

Two
One

Richards

Proc.Amer.Acad,28, 17,
[18
Ibid, 30, 380

57.445
57.446

13

HBr

Two

It

Ibid, 31, 105

57.444

14

NH^Br

One

Cushman

Ibid, 33, lOG

57.445

15

NHiBr

One

Baxter

Ibid, 33, 122

57.444

16

NIl4Br

Two

«

Ibid., 34, 353

57.447

17

NH4Br

Tliree

«

Ibid., 39, 250

57.444

18

NHiBr

One

nines

Not yet published

57.443

Ai

vevage, wei^

rhted accordii

ig to the number of determinations .

. 57.4447

BAXTER. — A REVISION OF THE ATOMIC WEIGHT OF BROMINE. 203

first titrated again&t each other, and then the precipitate of silver
bromide was collected and weighed. Of the four results by the first
method, one should be rejected according to his own statements, since
the bromine was not thoroughly dried. The remaining three, 79.959,
79.961, and 79.960, give as an average 79.960. From the weight of
silver bromide four values were obtained, 79.950, 79.952, 79,955, and
79.957, with an average of 79.954.

Marignac^ also determined the ratio of silver to silver bromide,
with somewhat lower results, — 79.959, 79.941, and 79.952; average,
79.950.

Scott,^ in his analyses of ammonium bromide, obtained six values
for the same ratio, varying between 79.936 and 79.948, with an
average of 79.943. One of his results is here rejected, since the silver
used in this experiment was known to be impure.

Dumas'' by heating silver bromide in chlorine found the values
80.06, 79.89, and 79.96.

In computing the atomic weight of bromine from these data, great
weight is always given to Stas's determinations, the value 79.955
being usually assumed as the most probable one for the constant in
question. Certainly, as pointed out by Richards,^ the true value
must lie between 79.95 and 79.96. Clarke calculates the value 79.949
as the weighted average of the dififerent investigations previous to
Scott's.9

Considerable uncertainty exists as to the purity of the materials
employed in much of the foregoing work. Richards and Wells ^^ have
already exhaustively investigated the various methods of preparing
pure silver, and have found that while it is a comparatively simple
matter to free this substance from metallic impurities, the absence of
gaseous impurities is by no means so easy to secure. Oxygen may be
eliminated best by fusion in an atmosphere of pure hydrogen gas,^^
or by prolonged fusion in a vacuum, while a lime boat was found to be
the most suitable support for the silver during fusion.

In most of the experiments cited on page 202, one of the final steps
in the purification of the silver was fusion of electrolytic crystals on
lime, in many cases in a vacuum, but without especial care to prolong

" CEuvres Completes, 1, 81.

« Jour. Chein. Soc. Trans., 79, 147 (1901).

f Ann. Chera. Pharm., 113, 20 (1860).

8 Proc. Amer. Phil. Soc., 43, 119 (1904).

9 A Recalculation of Atomic Weights, Smith. Misc. Coll., 1897.
1° Publications of the Carnegie Institution, No. 28, 16.

" 13a.\ter, These Proceedings, 39, 249 (1903).

204 PROCEEDINGS OF THE AMERICAN ACADEMY.

the fusion. Silver prepared in this way was found by Richards and
Wells to contain traces of oxygen, derived from silver nitrate occluded
by the electrolytic crystals. In cases 8, 9, 10, 17, and 18, however, the
silver was fused in hydrogen. Richards and Wells showed also that
Stas's silver contained at least one one hundredth of a per cent of
impurity, since it yielded one one hundredth of a per cent less silver
chloride than their purest silver. ^^ Scott's silver in three cases was
merely heated, not fused, in hydrogen, and in two of the others was
fused before a blowpipe on calcic phosphate. In one experiment only
the metal was fused on lime. No details are given as to the purifica-
tion of the silver used by Marignac.

Bromine also may be freed from impurities only with some difficulty.
Experience in this laboratory has shown that chlorine may be elimi-
nated most conveniently by distilling or precipitating the bromine
from solution in a bromide. One such distillation is sufficient to
remove chlorine completely only when the substance is initially com-
paratively pure. If, however, the process is repeated by converting a
portion of the partially purified product into a bromide, and dissolving
the remainder of the bromine in this comparatively pure bromide, the
chlorine is eliminated so completely that further repetitions of this
process have no apparent effect. ^"^ The removal of iodine may be
easily effected by converting the bromine into hydrobromic acid or a
soluble bromide, and boiling the solution with a small quantity of free
bromine. Here again it is well to repeat the process several times,
since the reaction between free bromine and the iodine ion, like
that between free chlorine and the bromine ion, is undoubtedly
incomplete.

The greater part of the experiments cited on page 202 were made
with bromine which had been purified with due observance of these
precautions. Of the other investigators, Stas seems to have been the
only one to use sufficient pains to secure purity of the bromine. Stas
removed iodine by shaking potassium bromide several times with free
bromine and carbon disulphide, and in the course of the prolonged
purification distilled the bromine twice from solution in a bromide.
Marignac's purification consisted solely in crystallization of barium
bromate and Scott's in distillation of hydrobromic acid.

Of the methods employed in these early determinations, that involv-
ing the analysis of metallic halides is least suited for the purpose, on

" Loc. cit., page 62.

13 Attention has already been called to these points by Richards and Wells,
These Proceedings, 41, 440 (1900).

BAXTER. — A REVISION OF THE ATOMIC WEIGHT OF BROMINE. 205

account of the danger of occlusion of metallic salts by the precipitated
silver bromide. That such an error actually exists to a slight extent
is shown by the fact that the average of the " indirect " determinations
is slightly larger than the average of the "direct" determinations.
Obviously, if silver bromide is precipitated by means of either am-
monium bromide or hydrobromic acid, occluded ammonium salts or
free acids could be easily expelled by fusion of the bromide. This
precaution was observed in most of the determinations recorded on
page 202, and is absolutely essential for the complete elimination of
water from the salt. Stas and Marignac both fused the silver bromide
in their syntheses, but this operation was omitted by Scott, who dried
the bromide at 180°. Scott's statement that the loss on fusion of
silver bromide which had been dried at 180° was due to the presence
of asbestos is contradicted by the experiments recorded later in this
paper, in which the loss on fusion amounted to about one one hundredth
of a per cent in the case of silver bromide which had been dried in a
similar fashion and which was almost entirely free from asbestos.

From this brief discussion of the more important errors which may
have influenced previous determinations of the atomic weight of bro-
mine, it is evident that some uncertainty still exists as to the true
value of this constant. In the hope of throwing new light upon the
subject, experiments were carried out by two of the methods outlined
above, with especial precautions to insure purity of materials and to
eliminate known possible errors in the experimental methods.

Both the methods chosen — synthesis of silver bromide from a
weighed amount of silver, and conversion of silver bromide into silver
chloride — have already been recently tested in this laboratory,^* and
have been found to be at least as satisfactory as any.

Purification of Materials.

Bromine. — In purifying bromine for this research, the principles set
forth on page 204 of this paper were applied ; but in some cases the
purifying processes were repeated after the product was apparently
pure, in order to make certain that further treatment had no effect.

Sample I was first completely dissolved in calcic bromide which
had been made from about one third of the original material by means
of lime and ammonia, and was then distilled from the solution. The
product was covered with several times its volume of water, and was
converted into hydrobromic acid by means of pure hydrogen sulphide

1* Baxter, Tlieso Proceedings, 40, 419; 41, 73. Itkhards and Wells, Publica-
tions of the Carnegie Listitution, No. 28.

206 PROCEEDINGS OF THE AMERICAN ACADEMY.

which had been generated from ferrous sulphide with dihite sulphuric
acid, and which had been thoroughly washed with water. After filtra-
tion from the precipitated sulphur and bromide of sulphur, the acid was
boiled for some time, with occasional addition of small quantities of
recrystallized potassium permanganate to eliminate the iodine. Finally
the residual hydrobromic acid was heated with an equivalent amount
of recrystallized permanganate, and the bromine was condensed in a
flask cooled with ice.

Sample II was first converted into hydrobromic acid by means of
red phosphorus and water, and the hydrobromic acid was then distilled,
after having been boiled with an excess of bromine. An equivalent
amount of permanganate was added, and the bromine liberated was
separated from the solution by distillation. About one fourth of the
product was next transformed into calcic bromide by means of am-
monia and lime which was free from chloride, and the remaining three
fourths of the bromine were dissolved in the calcic bromide and dis-
tilled. Still a third distillation from a bromide was carried out by
reducing the product of the second distillation with hydrogen sulphide
and subsequently oxidizing the hydrobromic acid with the purest re-
crystallized potassium permanganate, after boiling the acid with several
small portions of permanganate to eliminate last traces of iodine.

Sample III was obtained by preparing calcic bromide from a portion
of Sample II and distilling the remainder of Sample II from solution
in this bromide.

In the case of Sample IV the processes of reduction to hydrobromic
acid with hydrogen sulphide and oxidation of the hydrobromic acid
with pure permanganate were four times repeated. After each reduc-
tion the hydrobromic acid was boiled with free bromine to remove
iodine.

Sample V was three times reduced with hydrogen sulphide and oxi-
dized with permanganate. One fourth the product was converted into
calcic bromide and the remainder was dissolved in this calcic bromide
and distilled.

Thus Sample I was twice distilled from a bromide ; Sample II was
treated three times in the same way ; and Samples III, IV, and V four
times.

Shortly before use each sample was distilled and converted into
ammonium bromide by slow addition to an excess of redistilled am-
monium hydroxide. The solution was then boiled to expel the excess
of ammonia.

H'dirr. — Several different samples of silver were employed, many
of which have already been used in atomic weight researches in this

BAXTER. — A REVISION OF THE ATOMIC WEIGHT OF BROMINE. 207

laboratory, and have shown evidence of great purity. For details con-
cerning the puritication the papers referred to should be consulted.

Sample A was employed in a determination of the atomic weight of
iodine. ^^ This specimen had been twice precipitated as chloride and
once electrolyzed.

Sample B was used in experiments upon the atomic weight of iodine ^^
and of manganese. ■'^'^ It was precipitated once as chloride, electrolyzed
once, and finally precipitated as metal with ammonium formiate.

Sample C also was employed in a determination of the atomic weight
of manganese, and was purified by recrystallizing silver nitrate, seven
times from nitric acid and five times from aqueous solution. Finally
the silver nitrate was reduced by means of ammonium formiate.

Sample D was prepared for the determination of the atomic weights
of cadmium ^^ and manganese, by one precipitation as chloride, one
precipitation with ammonium formiate, and one electrolysis.

Sample E was first purified in part by precipitation as chloride, in
part by precipitation with ammonium formiate. The combined mate-
rial was then subjected to two electrolyses.

In all cases the electrolytic crystals were fused in a boat of the purest
lime, contained in a porcelain tube, in a current of electrolytic hydro-
gen. After the buttons had been cleansed with dilute nitric acid and
dried at 200°, they were cut into fragments of from four to eight grams
either by means of a clean chisel and anvil or with a fine jeweller's
saw. The latter method was employed in the case of Samples D and E,
because it proved easier completely to free the silver from surface con-
tamination with iron by etching the fragments with nitric acid, than
when a chisel was used. The cleansing process with nitric acid was
repeated until the solution thus obtained, after precipitation with
hydrochloric acid and evaporation, proved free from iron. That every
trace of iron could be removed by this treatment was proved by testing
for iron the evaporated filtrates from several of the analyses subse-
quently recorded in this paper. Negative results were obtained in all
cases.

After thorough washing with water and drying at 100°, the pieces of
metal were heated to about 400° in a vacuum, and were preserved over
solid potassium hydroxide in a desiccator.

" Baxter, These Proceedings, 40, 420 (1904).

16 Baxter, Ibid., 41, 79 (1905).

" Baxter and Ilines. Tliis paper will soon be publislied.

18 Baxter and Ilines, Jour. Amer. Chem. Soc, 28, 772 (1906).

208 proceedings of the american academy.

The Ratio of Silver to Silver Bromide.

The ratio of silver to silver bromide was determined as follows :
Weighed quantities of silver were dissolved in the purest redistilled
nitric acid diluted with an equal volume of water, in a flask provided
with a column of bulbs to catch possible spatterings. However, during
the solution of the silver the temperature was kept so low that almost
no gas was evolved, and hence there was very little danger from this
source. Next the acid solution of the silver was diluted with an equal
volume of water, and was heated until free from nitrous acid and oxides
of nitrogen. After still further dilution, the solution was added slowly
with constant agitation to a dilute solution of an excess of ammonium
bromide in a glass-stoppered precipitating flask, and the whole was
violently shaken for some time to promote coagulation. By adding the
silver solution to the bromide, occlusion of silver nitrate was almost
wholly precluded. In some experiments the solutions were as dilute
as twentieth normal, in others as concentrated as fourth normal. The
final results seemed to be independent of the concentration of the
solutions. At the end of about twenty-four hours the flask with its
contents was again shaken, and then it was allowed to stand until
the supernatant liquid was perfectly clear. The precipitate of silver
bromide was collected upon a weighed Gooch crucible, after thorough
washing by decantation with water, and was dried in an electric oven,
first for several hours at 130°, finally for about fourteen hours at 180°.
Then it was cooled and weighed.

The operations of precipitation and filtration were performed in a
large cupboard lighted with red light, and if the flask was taken out of
this cupboard it was enveloped in several thicknesses of black cloth.

Even after the prolonged drying, traces of moisture were retained
by the salt, and could be expelled only by fusion. This was done by
transferring the bulk of the silver bromide, freed as completely as pos-
sible from asbestos, to a small porcelain crucible which was weighed
with its cover. The silver bromide was then fused by heating the
small crucible, contained in a large crucible to prevent direct contact
with the flame of the burner. A temperature much above the fusing
point of silver bromide was avoided so that volatilization of the salt
could not take place. This treatment must have eliminated occluded
ammonium salts as well as water. Finally, in order to convert any
occluded silver nitrate, metallic silver, or silver sub-bromide into silver
bromide, the salt was again fused in a current of dry air containing
bromine vapor. This treatment seldom produced any measurable
effect either upon the weight or the appearance of the salt, which was

BAXTER. — A REVISION OF THE ATOMIC WEIGHT OF RROMINE. 209

perfectly transparent and of a light yellow color even after the first
fusion in air.

A few shreds of asbestos displaced from the crucible, together with
an occasional trace of silver bromide which escaped the crucible, were
collected upon a tiny filter paper which was then ignited in a porcelain
crucible. Before being weighed the ash was either treated with a drop
of nitric and hydrobromic acids and again heated, or else was heated
for some minutee in a current of air and bromine.

The filtrate and washings were evaporated to small bulk. The
precipitating fiask and all other glass vessels used in the analysis
were rinsed with ammonia and the rinsings were added to the evapo-
rated filtrate and wash waters. The whole was then tested in a nephel-
ometer for silver and the quantity found was estimated by comparison
with standard silver solutions. In most cases the correction thus
obtained was less than one tenth of a milligram.

The asbestos which formed the felt in the Gooch crucible, after
having been shredded, was digested for some hours with aqua regia
and was then thoroughly washed with water. Before the empty
crucible was weighed, the felt was ignited with a Bunsen burner.
Crucibles thus treated and then heated to 180° after being moistened
with water did not change in weight.

In the following table are cited all the analyses which were com-
pleted without accident. Vacuum corrections of — 0.000031 for every
apparent gram of silver and of -f 0.000041 for every apparent gram of
silver bromide are applied. ^^ The atomic weight of silver is assumed
to be 107.930.

The platinum plated brass weights were standardized from time to
time and were found to retain their original values within a very few
hundredths of a milligram in all cases.

The Ratio of Silver Bromide to Silver Chloride.

The ratio of silver bromide to silver chloride was determined much
as described in previous papers upon the atomic weight of iodine.^^
Pure silver bromide was prepared by precipitation of silver nitrate
with an excess of ammonium bromide. The silver employed was

" The specific gravity of llie weights was determined to be 8..3.

The specific gravity of silver has been found to be 10.49. Richards and "Wells,
Publications of the Carnegie Institution, No. 28, 11.

The specific gravity of fused silver bromide has been found to be G.473.
Baxter and Ilines, Amer. Chem. J., 31, 224.

20 Baxter, These Proceedings, 40, 4;]2 (1004) ; 41, 75 (1905).

VOL. XLII. — 14

210

PROCEEDINGS OF THE AMERICAN ACADEMY.

o o aj
o &ca

(a'»cc ^

o

TP O lO ".O

>o

Oi OiOiOi

Ci

Oi Oi C5 Gi

a

t:^ t~ t^ t^

I—

■^ Tj* o

lO

O lO o

o

Ci Ci o

en

oiosoi

35

t^ i^ t~

t^

t^ OJ » Ol C^ CO
■^ i.O O O O uO

c; c; Ci C5 CJ

Oi 05 05 ci oi

t^ t- t^ 1^ t^ i~

CO CO CO

Xl

■^ CO

rt<

1
CO

1.0 i-O o

lO

lO o

O

o

3i G5 03

wi

O C31

33

05 0JC5

35

Oi Oi

c;

33

t— t^ t^

t^

t- l~

t^

t—

CO CO

c-. 3;

31 ci

bo

be

O 'O CO Ci

t~ lO lO uO

CD

^^ ^y ^^ ^y
^^ ^^ "^ '^

■<*

■rJH

t^ t^- r^ t--

t^

O lO lO lO

o

Oi i-H lO

TO

■* lO ■*

rti

•*! -^ -*

'^

T)<^ TJI

Tt<

r- t^ t^

r—

lO lO lO

lO

o? -* 35 o :d CO

t^ O CO CO lO 'C
^j^ "T ^^ *7^ "p
^^1 ^^ ^7^ ^T^ ^'^ ^T"

t~^ t-^ t~^ t-^ t^ i-^

lO >C to O O iO

•O d TJf

■rft

0(M

fN

10*0 0

■o

lO lO

o

o

-r ~p ~1<

■^

•ti ^

■^

'^

-t -^ -^

■rf

TJI Tj*

■*

f

t^ t— t^

r—

t~ t-^

r-

r^

>0 lO lO

O

lOiO

•o

>o

CO CO
lO lO

■a s;

eo

CO

H
«3

.O

g2

■^ II

pq be
o

H

a

o
I— I

(— (

o
Hi;

^<

w ••

V<5

coo

1^4
0.5 a

.22 02 2

^

CO CO (M C5
to 35 CO CO
CO CO C5 O
— CO 00 O
(M C^ CO 00

CXJOOO 35

be ■* «~- t-

S^ CO 3; S<I
t; CO 33 30
O) CD (M CD
>. 1-H 00 CO
<; -^ CO 00

be CO C5 CO CO O <M

^ t- 33 CO CD CO -N

£; t^ -M t-- Tji 33 1~

Q CO o t^ lo o o

> Tjl 'M l^ ^- >— I 00

to <NCO(N

Jg 33 Ol O

£; CO 00 -^

O 35 Tf< lO
>. C5 35 OJ

bo t: f^

^ 35 -M

£ 2

> 00

*^ ' . : . . ^ s^. w* --* ^ w. w i*. *-,

OCOr-lrlO -.jj lOCOOO << -^LO <J< !— I
I—)*— ti-Hi— IT-H ^i— 1,-Hr- f ^r— II— I ^i— I

r-l t^ ^M t~

(M O rN i-H
O O — O

o oo o
o ooo

oddo

•«1< lO ■»*<
<M CO o

ooo
ooo
ooo

odd

t^ CO -^ ^ — I— I

o o o o oo
o o o o o o
o o o o o o
o o o o o o

<z> d o d> d> di

■^ t^ I-H

s§s

ooo
ooo

lO -o
oo
o o
oo
o o
dd

r^ C3 -i< C5

00 O — CO CO

a o o o o

§ oo oo

E o o o o

*" dddd

t~-co o
•* ^ o
ooo
ooo
ooo

C5 Tti O CD -M "*

o o — o -- o
o o o o o o
o o o o o o
o o o o o o
di d> d d> c^ <:i

35 35 t^
^OO

SO o
o o
ooo

CO t^

^ o

O' o

o o
oo

do

c c
o o

Ol (U

o o
'=c to

:5 «

> >

01

fl a.a
°.2 a
iss

tc2 a

= i 3

J3 CO *

2 » a

"s a

.2 §

a oj:
S 2

t^ O CO l^
04 <M ■M i-i

O o o o

O OOO

oooo
d>dic>c>

(M CO "O
O -- T-H
OOO

ooo
ooo

O t^ O O lO lO

tUX o

•^-n

T-H O -- O 'M O

l-H ^-N

l-HO

o o o o o o

oo

ooooo o

o o o

oo ooo o

ooo

O '— '

oooo oo

ooo

oo

d t-- 35 O

m CD X 35 O
g CO CO t^ O

S -H CO X o

2 IM t^ CO »

■^ oood d d

vO Ol X

CO CO CO
fN 35 X
CO Ol CO
I— 00 CO

■^ CO 00

T-l C5 lO — O) Ol
t^ C5 CO CD -^ Ol
I— Ol t^ 'S' 35 I^

CO o t^ "O o lo
•<i; oi t~; ■-; I-; 00
t--^ d 00 ■-<•-< d

CO X t~

X Ol CO

CO X ■*
C5 ^ lO
33 35 OJ
lO CO 00

O CO
03 —I
I- O
>0 OJ
OJ CD
■^ i-O

00 lO X OJ

kO Ol ^ C73
X t^ X 35
i-i ^ CO OJ
t-; O 33 CO
rli lO lO lO"

(M X r-H
I— < CO '— '
CO Ol t-
CO t^ o

T-H O X

00 lO 1^

05 «0 'O lO O CO
l~ ri OJ CO X 35
Ol 1— I -^ t^ I— I CO
t^ CO ^ O X CO
Ol 00 05 -^ CO Ol

T)i uO t-^ CO CO d

18778
01261
48638

0 1^

OO

01 CO

O05

05XO

wx

CO

CO

CO

I— <

^SSS >>> >»>»

c

<i5M<!o ^lopq o<JpqGQQ WWW WW

I-H Ol CO ^

»0 CO t^

00 S3 O rH Ol CO

t^ X

'S

c

-O

s

3

BAXTER. — A REVISION OF THE ATOMIC WEIGHT OF BROMINE. 211

purified either by precipitation as chloride and reduction with invert
sugar, or by electrolysis, or by precipitation with ammonium formiate.
The metal was then fused before a blowjiipe upon a crucible of the
purest lime, and the buttons were thoroughly cleansed with nitric acid.
No further purification was considered necessary since the weight of
the metal was of no consequence.

After the silver bromide had been washed by decantation with water,
in some cases it was collected in a Gooch crucible in which a disk of
filter paper was employed instead of asbestos, and after drying at 100°
it was carefully separated fi-om the filter paper. In other cases the
precipitate was transferred to a platinum dish, and was drained with
a platinum reverse filter ^i with a disk of filter paper. In still others
a platinum Gooch crucible with small holes was found to be sufficiently
effective as a filtering medium without the use of either asbestos or
filter paper. '

Before being weighed the silver bromide was fused in a current of
air saturated with bromine in a weighed quartz crucible. The air was
purified by passing successively over beads moistened with silver
nitrate solution, over sodium carbonate, and finally over concentrated
sulphuric acid which had been heated to its boiling-point with a small
quantity of recrystallized potassium dichromate to eliminate volatile
and oxidizable impurities. The air was then passed through dry bro-
mine in a small bulb. This apparatus was constructed entirely of glass
with ground joints. The tube which conducted the gases into the
crucible passed through a Rose crucible cover of glazed porcelain in
all experiments except Analyses 28 to 31, in which a quartz cover was
employed. The quartz crucibles were always contained in large porce-
lain crucibles while being heated. They remained almost absolutely
constant in weight during the experiments. The bromine was in each
case a portion of the sample from which the silver bromide had been
made.

Next the bromide was heated barely to fusion in a slow current of
chlorine, generated by the action of hydrochloric acid upon manganese
dioxide, and dried by means of concentrated sulphuric acid. The
apparatus for this purpose also was constructed wholly of glass. When
the bromine was apparently completely displaced, the silver chloride
was heated in the air for a few minutes to expel dissolved chlorine,
and then was cooled and weighed. A repetition of the heating in
chlorine seldom affected the weight of the salt more than a few hun-

" Cooke, These Proceedings, 12, 121.

212 PROCEEDINGS OF THE AMERICAN ACADEMY.

dredths of a milligram, although occasionally a third heating was
necessary to effect this result.

That no loss of silver chloride by volatilization took place is certain
for two reasons. In the first place the cover of the crucible and the
delivery tube for the bromine when rinsed with ammonia and the
solution treated with a slight excess of hydrochloric acid gave no
visible opalescence in the nephelometer. In the second place the
weight of the chloride became constant without difhculty. It has
already been shown that silver chloride which has been fused in
chlorine, if subsequently heated in air, retains no excess of chlorine. ^^

The following vacuum corrections were applied: silver bromide,
+ 0.000041; silver chloride +0.000071.23 ^he atomic weight of
chlorine referred to silver 107.930 is assumed to be 35.473.

Aside from the close agreement of all the results of Series I, the
fact is to be emphasized that of the last seven analyses, which were
consecutive, only two differ from the average of the series, 79.953, by
as much as one one thousandth of a unit. Furthermore, there is no
evidence of any dissimilarity in the different preparations of bromine.
Material which has received only two distillations from a bromide gives
values no lower than bromine which has been thus treated four times.
The various specimens of silver also show no difference in purity.

In the case of Series II, the extreme variation of the results is only
four thousandths of a unit, and only one of the thirteen experiments
yielded a value which differs from the average by more than one one
thousandth of a unit.

Finally, the difference between the averages of Series I and II is
only seven ten thousandths of a unit. It is extremely unhkely that
constant errors could have affected both series equally, so that this
striking agreement is strong proof that both series are free from such
errors.

It has already been pointed out that the average of Stas's syntheses,
79.954, probably represents with considerable accuracy the atomic
weight of bromine, and that certainly his determinations are more
accurate than those of later experimenters. His syntheses are few
in number, however, and differ among themselves by several thou-
sandths of a unit, so that they do not define within this amount the
constant in question. Their average, however, confirms the value

22 Baxter, These Proceedings, 40, 4:12 (1904) ; Richards and Wells, Publica-
tions of the Carnegie Institution, No. 28, page 59.

23 Kicliards and StuU have found tiie density of fused silver chloride to
be 5.5G.

BAXTER. — A REVISION OF THE ATOMIC WEIGHT OF BROMINE. 213

TABLE II. — THE ATOMIC WEIGHT OF BROMINE.

Series II.

AgBr : AgCl.
Ak - lOT.O.OO CI = 35.473

Number

of
Analysis.

Sample

of

Bromine.

Weight of

Silver Bromide

iu Vacuum.

Weiglit of

Silver Chloride

in Vacuum.

Ratio f«;.
AgCl

Atomic
Weight of
Bromine.

19

II

grams.

8.03979

grams.
6.13642

131.0176

79.953

20

II

8.57738

6.54677

131.0170

79.952

21
22

II

IV

13.15698
12.71403

10.04221
Average,

9.70413

131.0168

79.952

131.0171

79.952

131.0167

79.952

23
24

IV
V

13.96784
13.08168

10.66116
Average,

9.98469

131.0162

79.951

131.0164

79.952

131.0174

79.953

25

V

12.52604

9.56059

131.0175

79.953

26

V

11.11984

8.48733

131.0170

79.952

27
28

V

I

8.82272
11.93192

6.73402
Average,

9.10721

131.0172

79.953

131.0173

79.953

131.0162

79.951

2!)
30

I
III

12.53547
17.15021

9.56767
Average,

13.09009

131.0190

79.955

131.0176

79.953

131.0167

79.952

31

III

Total,

10.31852
153.94242

7.87572
Average,

117.49801

131.0168

79.952

131.0168

79.952

131.0170

79.952

Av

eragc of al

13 experimen

ts . , . .

1310171

79.952

Av

erage of Se

ries I and II

79.953

214 PROCEEDINGS OF THE AMERICAN ACADEMY.

obtained in this paper. From all the experiments here described the
number 79.953 seems to be the most probable value for the atomic
weight of bromine.

In conclusion, attention may be called to the fact that a diminution
in the atomic weight of bromine raises slightly all atomic weights
resulting from the analysis of metallic bromides by precipitation with
silver.

I am deeply indebted to the Carnegie Institution of Washington
and to the Cyrus M. Warren Fund for Research in Harvard University
for assistance in pursuing this investigation.

Chemical Laboratory of Harvard College,
Cambridge, Mass., May 18, 1906.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 12. — Octobek, 1906.

CONTRIBUTIONS FROM THE ZOIJLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HjVRVAKD COLLEGE,
E. L. MARK, DIRECTOR. — No. 184,

THE OPTIC CHI ASM A OF TELEOSTS: A STUDY

OF INHERITANCE,

By a. p. Lakkabee.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE.
E. L. MARK, DIRECTOR. — No. 184.

THE OPTIC CHIASMA OF TELEOSTS : A STUDY OF

INHERITANCE.

By a. p. Lakrabee.

Presented by W. E. Castle. Received June 28, 190G.

Introduction.

In the majority of teleosts, as has been pointed out by several inves-
tigators, the condition of the optic chiasma is markedly different from
that found in other vertebrates. In these teleosts the nerve fibres of
the two optic nerves do not interlace at the chiasma, but each nerve
remains distinct, so that the two can easily be dissected apart at that
point. Conflicting statements regarding the condition of the chiasma
are found, some writers stating that the nerve running to the right
eye is dorsal, others making the opposite statement. In recent years
Parker ( : 03 ) has shown that one condition is about as common as the
other. He made a dissection of one hundred specimens, each often dif-
ferent species of symmetrical teleosts. Of these, 514 had the right
nerve dorsal and -18() the left nerve dorsal. In each case the right or
left nerve signifies the nerve running to the right or left eye respec-
tively. He showed, too, that this dimorphism is not correlated with
sex. To quote from his paper giving his conclusions on this point :
"In Fundulus, of the 51 specimens with the left nerves dorsal, 29 were
females and 22 males ; and of the 49 with the right nerves dorsal, 29
were females and 20 males. Of the 43 specimens of Tautogolabrus
with the left nerves dorsal, 26 were females and 17 males ; and of the
57 with the right nerves dorsal, 26 were females and 31 were males.
These figures show clearly that there is no close correspondence be-
tween the crossing of the optic nerves and sex."

The question whether this dimorphism is due to racial differences
was left undecided. The writer will presently answer this question in
the negative, and at the same time discuss the relation of the dimor-

218 PROCEEDINGS OF THE AMERICAN ACADEMY.

phisni to heredity, and in the brook trout the effects of altered action
of gravity during development, together with the results obtained from
the study of monstrous specimens and from the development of the
optic nerves. The work on the inheritance of the optic chiasma was
begun by Dr. W. E. Castle and Mr. F. E. Pomeroy, and was carried
on and completed by the writer under the direction of Dr. Castle,
to whom the writer wishes to acknowledge his great indebtedness
for the material placed at his disposal and for aid and criticism dur-
ing the progress of his studies. He is also grateful to Mr. Pomeroy
for the use of results obtained by him at the beginning of this investi-
gation. Thanks are due also to the Massachusetts Commissioners of
Fisheries and Game, and in particular to Mr. Arthur Merrill, super-
intendent of the fish-hatchery at Wilkinsonville, Massachusetts, for
supplying and rearing the brook trout material ; also to the officers ot
the Bureau of Fisheries of the United States Department of Commerce
and Labor who supplied and reared at Wood's Hole, Massachusetts,
the young codfish used.

Object of the Investigation and the Method employed.

The writer has already hinted at the object for which this investiga-
tion was undertaken. The main object was to test the relation of
heredity to the dimorphism of the chiasma, and especially to determine
the applicability of Mendel's Law, should heredity prove to be a factor
in this dimorphic condition. In order to determine whether or not
heredity is a factor, matings of selected individuals were made, and
the effects determined by dissecting the young. For this purpose two
species offish were used, the common brook trout {Sal celt mis font inalis
Mitchill) and the codfish (Gadus morrhua L.). Since the spawning
season of these two is mainly during the months of November and
December, they were especially convenient forms with which to work.
In making these matings, the eggs of a female were commonly divided
into two or three lots, and each lot fertilized artificially with the milt
of a different male. The parents were then dissected to determine the
position of the nerves in the chiasmata ; the different lots of eggs were
carefully marked, and the necessary data recorded for future use.
This part of the work was done by Dr. Castle ; the study of the first
generation of brook trout and of the first lot of young codfish was
begun by Mr. Pomeroy and completed by the writer, who also carried
out the remaining studies described in this paper and prepared this
report for publication.

In preserving the two species of fish for study, different methods
of fixation were found necessary. The young trout were of suffi-

LARRABEE. — THE OPTIC CIIIASMA OF TELEOSTS. 219

cient size to allow dissection with needles under the dissecting micro-
scope. They were killed and fixed in Kleinenberg's picro-sulphuric
solution, washed out in 70 per cent alcohol, and finally preserved in 85
per cent alcohol. The young cod were too minute to be dissected
in the same way as the trout. It was necessary, therefore, to imbed
these in paraffine, and section, using the compound microscope to follow
the course of the optic nerves. Vom Rath's platinic-osmic-acetiy fluid
was found to be the best fixative for use with the cod.

Throughout this paper the writer will designate the optic nerves
according to the method employed by Dr. Parker, that nerve being
named right which runs to the right eye ; the one to the left eye, left.
For convenience, too, the specimens with the right nerve dorsal will be
termed rights, and similarly those with the left nerve dorsal, lefts.

Results of Selected Matings in the Brook Trout
(fkdveUnus fontinalis Mitchill).

First Generation.

The first generation of the trout includes the young regarding which
the condition of the chiasmata of one or both parents, but not of the
grandparents, was known. The results obtained from this generation
are shown in Tables I, II, and III. In all, there are eleven lots, four
of which were obtained in 1901, the remaining ones in 1902. In each
year where a male or female was used for more than one lot, the fact
can be recognized by the correspondence of the numbers following the
sex signs. The numbers of the two years, however, relate to different
individuals. The control lot includes a number of young taken at
random from the fiy at the hatchery without any knowledge of the
condition of the crossing of the nerves in the parents. This lot, com-
prising young of various parents, is assumed to represent the average
condition of the trout in their natural state.

The proportion of rights and lefts found in the eleven lots of the
first generation corresponds closely with that obtained from the control
lot. The percentage of rights in both cases is practically the same, —
56 per cent. With the exception of two lots, there is a slight excess
of rights in each case. In the nine lots where this excess is found, the
rights outnumber the lefts by from 0.4 per cent to 20 per cent. The
difference between the percentages of rights and of lefts in the series
as a whole is 11.8 per cent, which closely approximates the difference of
12.2 per cent found between the two kinds in the control lot. Nothing
in the net results indicates that in one case we are dealing with the

220

PROCEEDINGS OF THE AMERICAN ACADEMY.

young of selected parentage and in the other with young taken at
random.

Tables II and III show from another point of view the results obtained
from the first generation. In Table I the results are given as a whole,

TABLE I.

Eesults of Selected Matings in the Brook Trout

(Salvelinus fontinalis Mitchill).

First Generation.

Lot.

Nature of Mating.

Total

Number

of Young

dissected.

Right
Nerve 1
Dorsal.

Left
Nerve '
Dorsal.

Per cent
R.

Per cent
L.

A, 1901

$iR X cfjL

792

471

321

59.4

40.6

B, "

9iR X cf^R

346

188

158

54.3

45.7

C. "

?2 ^ X c^sL

677

380

297

56.1

43.9

D, "

$2 ^ X (fiR

798

479

319

60.0

40.0

1, 1902

?iR X cfiL

122

62

60

50.8

49.2

2, -•

?iR X cf.jR

105

59

46

56.0

44.0

3, "

$iR X cfjL

212

103

109

48.6

51.4

4 "

9.3R X cTiL

168

91

77

54.1

45.9

5, "

?2R X cfaR

420

212

208

50.2

49.8

6, "

?3R X diU

100

48

62

48.0

52.0

7, "

93R X cfflL

225

126

99

56.0

44.0

Total

3965
650

2219
365

1746

285

55.9
56.1

44.1
43.9

Control . .

Grand total

4615

2584

2031

56.0

44.0

1 Ne

rve to right eye.

2

Nerve to

left eye.

but in these two tables the results are grouped according to the condi-
tion of the chiasmata in the parents. Lots C and D, 1901, have to be
omitted from Tables II and III, as the crossing in the female is not known.
In comparing the results in these two tables, it is interesting to note

LARRABEE. — THE OPTIC CHIASMA OF TELEOSTS.

221

that, although the difference between the two groups is small, yet, in
the case of the young whose parents were both rights, the tendency
towards equality is slightly greater. In other words, among the young

TABLE II.

Lots from Table I ix which the Condition of the Chiasma was the
SAME (11 X K) IN Both Parents.

Lot.

Total No.
dissected.

Riglit Nerve
Dorsal.

Left Nerve
Dorsal.

P(^r cent
K.

I'er cent
L.

B, 1901
2, 1902

5, "

6, "

346
105
420
100

188
59

212
48

158
46

208
52

54.3
56.0
50.2
48.0

45.7
44.0
49.8
52.0

Total

971

507

464

52.2

47.8

TABLE in.

Lots from Table I i>f which the Condition of the Chiasma was
Unlike in the two Parents.

Lot.

Total No.
dissected.

Riglit Nerve
Dorsal.

Left Nerve
Dorsal.

Per cent
R.

Per cent
L.

A, 1901
1, 1902

3, "

4, "

7, "

792
122
212
168
225

471
62

10;]
91

126

321

60

109

77
99

59 4
50.8
48.6
54.1
56.0

40.6
49.2
514
45.9
44.0

Total

1519

853

666

56.2

43.8

whose parents were both rights, the proportion of rights is smaller than
among those which had but one parent with the right nerve dorsal.

It is evident from the close correspondence of the percentages shown
in Tables II and III with those of the control lot (Table I), that if the
IMendeliau principles of heredity can be applied at all to the case ol'

222 PROCEEDINGS OF THE AMERICAN ACADEMY.

the optic chiasma, it is an example of alternative dominance, for
neither condition is uniformly dominant over the other. The results
shown in Table III, where the crossing of the nerves was different in the
two parents, correspond closely with those to be expected if dominance
is alternative. If such is the case, it is necessary to assume either that
the parents were a "pure" right and a "pure" left, respectively, or
that both were heterozygotes. On the former assumption, the results
to be expected from the Mendelian formula would be equal numbers of
rights and lefts, all heterozygotes, thus :

R + R = gametes of first parent.
L + L == " " second " .

2 R (L) + 2 L (R) = offspring.

If both parents were heterozygotes, the apparent result would be the
same, but half each of the right and of the left offspring would be
" pure," the other half heterozygous, thus :

R + L = gametes of first parent.
R + L = " " second " .

R + R (L) + L (R) + L = offspring.

If one parent were a pure right and the other a heterozygote, the
proportion of rights to be expected would be 75 per cent, thus :

R + R = gametes of first parent.
R + L = " " second " .

R + R + R (L) + L (R) =: offspring.

The last assumption evidently is untenable, for in none of the lots
studied is this proportion approximated.

This principle of alternative dominance could be applied to the results
in Table II only by assuming that both parents were heteroz)^gous. On
this assumption alone could the observed almost equal proportions of
right and of left offspring be explained.

The first generation furnishes no direct evidence which would allow
a positive assumption that the facts are to be explained by Mendel's
Law.

Further, the results of the first generation show conclusively that
prepotency is not found in any individual. In Lots 1, 2, 4, and 5,
1902, the eggs of two trout were divided each into two lots, making
four in all. These were fertilized by two males so as to get as many

LAllllABEE. — TUE OPTIC CIIIASMA OF TELEOSTS.

223

combinations as possible. The following table (IV) gives the crosses
together with the percentage of rights resulting from each :

TABLE IV.

Lot.

Nature of Mating.

Per cent U.

1, 1002

?lR X d"iL

50.8

2, "

9iR X <f.,n

56.0

4, "

?.,R X cf,L

54.1

5, "

?.,R X d'-.R

50.2

An examination of this table makes it evident that no prepotency is
found in any individual or in either sex.

TABLE V.

Results of Selected Matings in the Brook Trout

{Salvelinus Jontincilis Mitcliill).

Second Generation.

Lot.

Nature of Mating.

Total
Number
of Young
dissected.

Right
Nerve
Dorsal.

Left
Nerve
Dorsal.

Per cent
K.

Per cent
L.

1, 1903
la, "

2, "
2 a, "

3, "

4, "
4 a, "

5, "
C, «

?iR X d"iR
? 1 R X d-., R
$.^L X d'sL
9.. L X d-i L
$;5L X d, L
?iR X d-oH
?., R X d-^R
95 R X c'gR
?«R X cf.R

39
8
15
28
41
19
20
69
96

21

4

8

7

21

10

10

33

51

18

4

7

21

20

9

10

30

45

53.8
50.0
53.3
25.0
51.2
52.6
50.0
47.8
53.1

46.2
50.0
46 7
75.0
48.8
47.4
50.0
52 2
46.9

Total

335

165

170

49.2

50.8

224

PROCEEDINGS OF THE AMERICAN ACADEMY.

Results of the Second Generation.

The second generation of trout (Table V) were descended from Lot
B, 1901. This lot included offspring from parents both of which had
the right nerve dorsal in the chiasma. The condition of the crossing
in the more remote ancestors is unknown, but from the results of the
first generation and of the control lot, it may safely be assumed that
they were about equally divided between rights and lefts.

The trout used for the second generation were small and immature.
Consequently the number of eggs produced was small, and the number
of young hatched proportionately smaller than in ordinary lots. Six
females and nine males were used. The eggs of three of the females
were divided into two lots each, making nine lots in all. The young
trout were taken soon after hatching and fixed, as before, in Kleinen-
berg's picro-sulphuric solution.

TABLE VI.

Group.

Total.

Number of
"Rights."

Number of
"Lefts."

Per cent
R.

Per cent
L.

A. (L X L)

B. (R X R)

84

251

36
129

48
122

43

51

57
49

In these nine lots there were 335 specimens, of which 1G5 were
rights and 170 were lefts. These 335 trout can be divided into two
groups according to their parentage. Group A includes those whose
parents were both lefts ; Group B, those whose parents were both rights.
The results are summarized in Table VI.

The excess of lefts in Group A at first thought seems significant, but
is doubtless due to the smallness of the lot (coinpare the result given
by Lot 2 a, 1903). This lot gave the same proportion (75 per cent
lefts to 25 per cent rights) which might be expected were this a case of
dominance under Mendel's Law, but the number of young is so small
as to make the chances of error very great. Not only the small number
included in Group A throws doubt on the significance of the result,
but also the results of the larger group (B). In this latter group there
are 251 individuals, of which 129 or 51 per cent are rights. We are
dealing here with individuals whose parents and grandparents were
rights, and yet the result is practical equality of rights and lefts.

When discussing the results of the first generation, the writer stated
that if Mendelism applied to this dimorphism, the case must be one of

LARRABEE. — THE OPTIC CIIIASMA OF TELEOSTS. 225

alternative dominance, and the suppositional grounds were stated on
which that claim might be based. In discussing the group which in-
cluded the young of trout both of which were rights, it was stated
that both parents must be heterozygotes. Assuming this to be the
case, it would follow that of the rights produced in the so-called first
generation, one half would be pure and the other half heterozygous,
i. e., rights having the left condition recessive. According to the laws
of chance, out of a considerable number of these rights, there would
be one chance out of three of obtaining a " pure " right. Among the
parents of Group B there were four females and six males. Applying
the law of chance stated above, it is improbable that out of ten speci-
mens not one should prove to be a "pure " right, — an animal which
would give at least 75 per cent of right offspring. These results lead
inevitably to the conclusion that the Mendelian principles of heredity
do not apply to the dimorphism of the chiasmata of the trout, thus
confirming the doubts caused by the results of the first generation.

The trout in Group B, whose parents and grandparents were
rights, afford a basis for comparison with the results to be expected
from another theory of heredity, namely, the one advanced by Galton
("89). According to this theory, the parents contribute one half the
hereditary influences, the grandparents one quarter, the great-grand-
parents one eighth, and so on.

In Group B there were 251 individuals, whose parents and grand-
parents were rights. According to the law of Galton, the influence of
these more immediate ancestors would be 75 per cent. The remoter
ancestors would probably be divided about equally between rights and
lefts. This would increase the influence of the rights to 87| per cent.
Of the 251 trout, then, about S~^ per cent, or 219 individuals, should
have the right nerve dorsal. Actually there were 51 per cent, or 129
rights. Such a discrepancy as this between the calculated and observed
results clearly indicates the inapplicability of Galton's Law,

The results of selective breeding in the trout clearly indicate that
neither dimorphic condition is a racial character. All the trout came
from the same locality, and although bred to the second generation, no
effect of selection on the dimorphism was evident, unless possibly a
tendency to make the two conditions more nearly equal.

The Results of Selected Matixgs in the Codfish
(Gad us morrhua L.).

The results obtained from the codfish have little significance in
themselves, but they serve to confirm the conclusions drawn from the
study of the brook trout.

VOL. XLII. — 15

226

PROCEEDINGS OF THE AMERICAN ACADEMY.

In the examination of the codfish, made by Dr. Parker, 60 out of 100
individuals had the right nerve dorsal. Table VII shows a similar result
for several selected matings of different sorts. Comparing this table
with Table I, where the results of the first generation of trout are tabu-
lated, a similarity is found with the conditions observed in that species.
The range of variation in the percentage of rights is greater in the case
of the cod than in the trout. Lot D, 1901, is specially notCAvorthy.
With both parents lefts, there is among the young an excess of rights
instead of lefts, as might be expected. From the similarity of results
in the two species, the conclusions which were drawn in the case of the
trout are made more certain. Selective breeding again fails to bring
out any evidence that either condition is hereditary.

TABLE VII.

Results of Selected Matings in the Codfish

(Gachis morrhua L.).

Lot.

Nature of Mating.

Total
Number
of Youug
dissected.

Right

N rve

Dorsal.

Left
Nerve
Dorsal.

Per cent
R.

Per cent
L.

A, 1901

B, "

C, "
1), "

9, 1902
10, "

?iR X cTiR
$iR X J'oL
$.^L X cfiR
9., L X c?, L
?4li X cT.R
?4H X cf,L

241

168
150
249
142
102

159

113

82

145

70

52

82
55
G8
104
72
50

06.0
67.3
54.7
58.3
49.3
50.9 .

34.0
32.7
45.3
41.7
50.7
49.1

Total

1052

580

552

55.2

44.8

Results oe Investigation of the Chiasmata in Monstrous
Specimens op Salvel'mus fontinalis.

Double monsters among trout fry are of common occurrence. These
vary greatly in the degree and kind of malformation. The specimens
used for this investigation varied from those having two heads and
one body to those with heads and bodies entirely distinct but with
a yolk sac in common. For couveiiieuce the individuals have been
placed in four groups.

LAURABEE. — THE OPTIC CIIIASMA OF TELEOSTS. 227

Group I includes the double-headed specimens which were divided
only anterior to the dorsal fin.

Group II includes double-headed specimens which were divided
posterior to the dorsal fin, but had a portion of the vertebral column
in common.

Group III includes specimens in which the two bodies were united
throughout a portion or the whole of the tail region, but were else-
where distinct.

Group IV includes specimens with two young entirely distinct and
on opposite sides of the yolk sac.

The bearing which these dicephalous specimens have upon the
subject under discussion can be shown by briefly considering some
of the theories advanced and some of the results obtained by those
who have made a study of this condition. Among other causes of
dicephaly, polyspermy has been advanced by several writers as a
probable cause. If this occurred, it is evident that the heredity of
these monstrosities would be more complicated than that of normal
individuals.

Schmitt (: 02), in a paper on the gastrulation of double trout em-
bryos, stated that the germinal area of the egg which produced a
double embryo was no larger, and contained no more material, than
the one which gave rise to a normal trout. In the formation of the
gastrula two invaginations occurred simultaneously in different parts
of the blastoderm. This observation indicates that polyspermy had not
occurred ; for if it had occurred, there would have been an increase in
the material contained in the germinal area. This change would also
occur if the egg were fertilized by a double-headed sperm, one of the
tentative causes for duplicity advanced by some writers.

Hans Spemann (:01, :01*), in experimenting with the eggs of the
salamander Triton, was able to produce dicephalous individuals, or even
two distinct individuals, by means of a ligature of hair tied across the
blastoderm. The extent of the duplicity depended on the tightness
of the ligature. A similar result has been obtained by Loeb and
others, although by different methods.

From these various observations it is evident that an increase in
the amount of sperm, either by polyspermy or otherwise, is not, at
least commonly, the cause of dicephaly. Accordingly in two-headed
trout, the hereditary characters of the divided parts should be the
same. It would follow, then, that if the dimorphic condition is
hereditary, the condition of the crossing should be the same in each
head. By referring to Table VIII, it will be seen that in more than
one half of the double-headed specimens dissected the crossings in the

228

PROCEEDINGS OF THE AMERICAN ACADEMY.

two heads were opposite. This is very significant, for it indicates that
the dimorphic condition of the chiasma is not hereditary. If heredity
is not a factor, what does determine the crossing of the nerves in the
chiasmata 1 In attempting to answer this question some other
possible factors were examined, but with negative results.

TABLE VIII.

Results obtained from Dissection of Monstrous Specimens
OF Salvelinus fontinalis.

Group.

Right Nerve

Dorsal in
Both Heada.

Left Nerve

Dorsal in

Both Heads.

Right Dorsal in

one Head, Left

in the other.

Per cent
R + R.

Per cent
L + L.

Per cent
R+L.

I.
II.
III.
IV.

24
10
10

11

8

6
4

7

21
25
2.3

22

45.0
24.4
27.0
27.5

16.0
14.7
11.0
17.5

39 0
60.9

62.0
55.0

Total

55

25

91

32.2

14.6

53.2

Results from Study of the Development of the
Optic Nerve.

Histological investigation was made of the optic nerves in different
stages of development. For this purpose eggs were brought from
the hatchery at Wilkinsonville, Massachusetts, and kept in a trough
of running water. Eggs were taken each day and fixed in Vom Rath's
fluid, which proved to be the best fixative for this purpose. As is
well known, the great majority of nerve fibres in the optic nerve de-
velop from the retinal cells and grow backward to the brain. The
object of this investigation was not, however, to study the mode of
development, but rather to find out whether both nerves developed
at the same time. In nearly all cases the nerve fibres had reached the
brain by the tenth day. Whenever the nerve fibres could be traced,
they developed at the same time, for the fibres fi"om both eyes were
equally developed. The dimorphism is not due to an earlier develop-
ment of one of the optic nerves.

larrabee. — the optic ciiiasma of teleosts. 229

The Effect of Gravity upon the Crossing of the
Optic Nerves.

0. Schultze ('95) in some experiments with frogs' eggs, found by
compressing the eggs between glass plates so as to force the blasto-
derm to remain at some point other than its normal one, that he
produced abnormal specimens. The degree of abnormality varied
according to the angle made by the axis of the normal egg with the
attraction of gravity. I have carried on similar experiments with
eggs of the brook trout, but with no results so far as abnormalities
were concerned. The compressed eggs died within a week or ten
days. But the experiments showed conclusively that gravity could
have no effect on the development of the nerves, and therefore could
not cause the dimorphism ; for in all cases the blastoderm finally came
to the top of the egg, in spite of the pressure. If the blastoderm
remained at the top under such conditions, it certainly would do the
same under normal conditions. In this position the effect of gravity
on the two sets of developing nerve fibres would be the same, and
consequently gravity could not be a factor in the question under
consideration.

The Laws of Chance applied to the Results.

The ■svriter has now shown that the dimorphism under consideration
is not hereditary, is not due to an earlier development of one of the
optic nerves, and is not caused by the action of gravity. It seems to
be begging the question to say that it is a matter of chance whether
one nerve is uppermost or not ; for this means that the real cause of
the dimorphic condition is unknown and, whatever it may be, it was
not affected by the conditions of the experiments performed. Admit-
ting that a " chance result " has this significance, the writer wishes to
show that the results obtained from the dissections are really chance
results. If so, the chances would be equal, in the normal trout, that
either the right or the left nerve should be uppermost. In other
words, the so-called rights and lefts should occur in equal numbers.
Referring to the results obtained from the first and second generations
of the trout, and to the control lot, also to the results obtained firom
the cod, it will be seen that the observed results closely approximate
such a relation. Of Salvelinus, 4950 specimens in all were dissected.
Of these, 2749 had the right nerve dorsal, and 2201 the left nerve dorsal.
Of Gadus, 1132 specimens were dissected; 580 of these had the right
nerve dorsal, and 552 the left nerve. In both cases, but especially in
the first, there is an excess of rights. In view of the results obtained

230 PROCEEDINGS OF THE AMERICAN ACADEMY.

from the selected matings, this excess cannot be regarded as very
significant. In the case of the trout, where it was greater than in the
cod, it amounts to six per cent only.^

In the case of the two-headed trout the conditions are more
complicated. In these, three combinations are possible. Either the
right or the left nerve may be dorsal in each head, or the right nerve
dorsal in one head, the left nerve dorsal in the other. According
to the laws of chance, in one half of the specimens the crossings
in the two heads should be unlike, while in the other half the
crossing should be similar in the two heads. Further, of those having
the crossings similar, one half should have the right nerve dorsal
in each head, the other half the left nerve dorsal. Of the 171 two-
headed trout dissected, 85 approximately should have crossings
opposite in the two heads, and 42 each should have the right or
the left nerve dorsal in both heads. Actually, 91 had the crossings
opposite, 55 had the right nerve dorsal in both heads, and 25 the left
nerve dorsal in both heads. Adding the last two groups together,
the numbers of those having the crossings similar and of those with
the crossings opposite are almost exactly equal, yet the right nerve,
as in other cs:;tegories of cases, is oftener uppermost than the left
one. This fairly close correspondence with the expected chance
result leads the writer to the conclusion that the position of the
optic nerves in the chiasmata of the symmetrical teleosts is a matter
of chance and not due to any of the possible causes which have been
discussed in this paper.

Summary.

1. The Mendelian principles of heredity do not apply to the dimor-
phic condition of the optic chiasma in symmetrical teleosts.

2. Galton's law likewise is inapplicable.

3. The dimorphic condition is not inherited.

4. The dimorphism is not due to an earlier development of one of
the optic nerves.

5. Gravity has no effect on the character of the crossing of the
optic nerves.

6. The condition of the crossing is a matter of chance.

^ Note bi/ W. E. Castle. It is, however, somewhat remarkahle that in both
species studied the rights should with such uniformity predominate, even though
the excess is not great. Selected matings evidently do not alTect the relation
one way or the other, but it persists nevertheless in nearly all matings and in
the control. The case may perhaps belong in the same category as the more
frequent occurrence of polydactylism in guinea-pigs upon the left side of the
body (Castle, :06).

LARRABEE. — THE OPTIC CHIASMA OF TELEOSTS. 231

Bibliography.

Castle, W. E.

:06. The Origin of a Polytlactylous Race of Guinea-pigs. Carnegie Institu-
tion of Washington, Publication No. 49, pp. 17-29.
Galton, F.

'89. 'J'lie Average Contribution of each Several Ancestor to the Total Heri-
tage of the Offspring. Proc. Roy. Soc, London, Vol. 61, pp. 401-413.

Parker, G. H.

:03. The 0[>tic Chiasnia in Teleosts and its Bearing on the Asymmetry of
the Ileterosoniata. Bull. Mus. Comp. Zool. Harvard (JoU., Vol. 40, No.
5, pp. 219-242, 1 pi.

Schmitt, F.

:02. Uber die Gastrulation der Forelle mit Beriicksichtigung der Coucres-
cenztheorie. Verhandl. d. deutsch. Zool. Gesellsch., 12te Jahresver-
sanunluug, Leipzig, pp. 64-83, 7 Fig.

Schultze, O.

'95. Die kiinstliche Erzeugung von Doppelbildungen bei Frosch Larven
niit Hilfe abnorraer Gravitations-wirkung. Arch. f. Entwickelungs-
mech., Bd. 1, pp. 269-305, Taf. 11 u. 12.
Spemann, H.

:01. Experimentelle Erzeugung zweikbpfige Erabryonen. Sitzungsb. d.
phys.-nied. Gesellsch. Wlirzburg, Jahrg. 1900, pp. 2-9.
Spemann, H.

:01*. Entwickelungsphysiologische Studien am Triton-Ei. Arch. f. Ent-
wickelungsraech., Bd. 12, pp. 224-264, Taf. 5, 24 Textfig.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. i;3. — November, 1906.

FL UOBESCENCE A ND BIA GNETIC EOT A TION SPECTRA
OF SODIUM VAFOIL AND THEIR ANALYSIS.

By R. W. Wood.

With Five Plates.

Investigations on Light and Heat made and published, whollt or m fabt, with Apphopeiation

FROM THE RUMFOBD FUND.

FLUORESCENCE AND MAGNETIC ROTATION SPECTRA OF
SODIUM VAPOR, AND THEIR ANALYSIS.

By R. W. Wood.

Presented by C. R. Cross. Received August 7, 1906.

Previous work, which has been recorded in the Philosophical Maga-
zine,^ convinced me that a careful study of the remarkable optical
properties of the vapor of metallic sodium would, in time, furnish the
key to the problem of molecular vibration and radiation. This opinion
has been strengthened by the work of the past year, and though much
remains to be done, it seems best to place the results already obtained
on record. In no other case that I know of is the molecular mechan-
ism so completely under the control of the operator. Its periodicities
can be studied in a variety of ways : by absorption, by cathode-ray
stimulation, by excitation with light, either white or monochromatic,
and lastly by its remarkable selective magnetic rotation of the plane
of polarization.

The vapor is, in every case, that obtained by heating metallic sodium
in steel or porcelain tubes, usually highly exhausted. From a study
of the dispersion of the vapor, it seems probable that we may be deal-
ing with clusters of molecules with which a certain amount of hydro-
gen may be associated.

As I have shown in a previous paper,^ if a pool of sodium is heated
in a highly exhausted horizontal tube, the top of which is cooler than
the bottom, the vapor has an enormous optical density close to the
surface of the pool, and a very small density along the roof, the non-
homogeneous layer acting as a prism. The only way in which I can
reconcile this state of things with the kinetic theory is to assume that
the vapor leaves the metal in the state of molecular clusters, which
gradually break up into smaller clusters and eventually into molecules.
This is of course only an hypothesis, and I mention it in the present
paper merely to indicate that our vibrating mechanism may be an

1 Magneto-optics of Sodium Vapor, Phil. Mag., Oct., 1905. The Fluorescence
of Sodium Vapor, Phil. Mag., Nov., 1905.

2 A Quantitative Determination of the Dispersion of Sodium Vapor, These
Proceedings, 40, 335.

236 PROCEEDINGS OF THE AMERICAN ACADEMY.

aggregate and not a single molecule. It is also possible that hy-
drogen atoms are associated with the sodium, for the work on the
dispersion indicated that there was present always a small trace of
some gas other than sodium, which no amount of pumping would
remove; that is, it appeared to be tangled up in the sodium vapor,
condensing with it in the cooler parts of the tube. All of this is,
however, irrelevant, for we are for the present merely engaged with
the study of a certain remarkable vibratory mechanism, and for the
present need not concern ourselves whether it is a molecule, a cluster
of molecules, or a compound molecule.

We will begin by a description of the various spectra which we shall
study and compare in the present paper. The spectrum region with
which we are concerned lies between wave-lengths 4600 and 5700, i. e.
the region of the green-blue channelled absorption spectrum.

The Absorption Spectrum.

Photographed with the twelve-foot concave grating, the absorption
spectrum is found to consist of a multitude of fine lines, to the num-
ber of about 1500 in the region specified. Its appearance has been
found to be profoundly affected by the presence of hydrogen or any
inert gas. It is shown on Plate 1, Figure 1, g, photographed in the
second order with a twelve-foot concave grating.' In hydrogen at
atmospheric pressure its appearance is shown by spectra /and h, the
fluted appearance being very marked. In a high vacuum its appearance
is shown by spectrum b, the flutings having entirely disappeared.
The chief change appears to lie in the increased absorbing power of
certain lines or groups of lines. Spectrum d is taken under nearly the
same conditions, the sodium vapor being less dense, however. A care-
ful study of the effect of the inert gas has not yet been made, and it is
mentioned here only on account of its relation with the subject of the
paper. Comparatively few of the absorption lines have any relation
with the fluorescent and magnetic rotation spectra, the ones concerned,
however, being those which are affected by the presence of the inert gas.

Moreover, both the fluorescence and magnetic rotation disappear,
i. e. cannot be excited, when the sodium vapor is formed in an atmos-
phere of hydrogen or other inert gas. Of this matter more will be said
later on.

The Magnetic Rotation Spectrum.

It was found last year that a number of vapors, showing fine and
sharp absorption lines, when placed in a powerful magnetic field, rotate

WOOD. — SPECTRA OF SODIUM VAPOR.

237

the plane of polarization for wave-lengths agreeing with that of the
absorption lines, not all of the absorption lines showing this rotatory-
power, however. The arrangement of the apparatus for showing the
bright-line magnetic spectrum of sodium is shown in Figure A,

A piece of thin seamless steel tubing of such a diameter as to slip
easily through the hollow cores of the electromagnet, from which the
conical pole-pieces have been removed, is procured. A short piece of
small brass tubing is brazed into one end, through which the tube is
exhausted.

A lump of sodium the size of a walnut is melted in an iron crucible,
and poured out into a V-shaped trough made of thin sheet iron. As
soon as the bar is solid it is placed in the iron tube, one end of which

•"••wsTiVvMr.^v

E

■^^-[\

cr

Figure A.

has been previously closed with a small piece of plate glass cemented
on with sealing-wax. The tube is introduced into the magnet, the
sodium bar pushed to a position midway between the helices, and the
other end closed with a piece of glass in a similar manner. The ends
of the tube should be coated while hot with sealing-wax before the
introduction of the sodium. One has then only to wave a Bunsen
flame over them and press on the piece of glass, previously heated ;
the sealing-wax should come into optical contact with the glass to
insure an air-tight joint. The tube is now connected with an air-
pump which will produce a vacuum of a millimeter or two. If the
air-pump leaks, it is a good plan to place a glass stopcock between
the pump and tube to prevent the entrance of traces of air after ex-
haustion. For purposes of demonstration it is sufficient to heat the
tube gradually with a Bunsen burner turned down low. In the present
work, however, where constancy of temperature was essential, electrical
heating was invariably used.

The light from an arc-lamp, made parallel by a lens, is passed
through a Nicol prism, the steel tube, and a second nicol, after
which it is brought to a focus by means of a second lens upon the

238 PROCEEDINGS OF THE AMERICAN ACADEMY.

slit of a spectroscope. With the steel tube cooled below the point at
which sodium vapor forms, the nicols are set for complete extinction,
and the field of the spectroscope becomes dark. The tube is now heated
and the magnet turned on, the air-pump being worked occasionally to
remove the hydrogen which is given off from the sodium. A bright
yellow spot will appear on the slit of the spectroscope, which is seen to
be made up of radiations chiefly in the immediate vicinity of the D
lines. The phenomena at the D lines have been fully described in the
paper already alluded to (Magneto- Optics).

When the vapor acquires a considerable density, a most magnificent
bright-line spectrum appears in the red and green-blue region. Each
bright line corresponds to a dark line in the absorption spectrum, but
only a small percentage of the dark lines appears to exercise a rotatory
power. Some of the strongest absorption lines are absolutely unrepre-
sented in the magnetic rotation spectrum, which indicates that there is
some radical difference in the absorbing mechanism.

It is with the bright-line spectrum in the green-blue region that we
are now concerned. This spectrum has been photographed with the
large, three-prism long focus spectrograph, and also with the twelve-foot
concave grating. Reproductions of the prism spectrograms are given
on Plate 2, / and m. The magnetic spectrum made with the large
grating and the absorption spectrum recorded on the same plate are
reproduced on Plate 1, c and d.

Only about sixty lines appear in this spectrum in contrast to the
1500 in the absorption spectrum. The intensities are very variable,
and apparently bear no relation to the intensities of the corresponding
absorption lines. The rotatory lines in many cases coincide with the
heads of the groups of absorption lines, though the centre of the line
appears to be slightly displaced beyond the head of the group of ab-
sorption lines. The displacement is, however, very slight, not more
than half the width of the line. A list of the wave-lengths of all the
lines visible on the negative is given on page 239. The approximate
intensities are represented by numerals, 10 indicating the maximum
intensity and 1 the minimum.

At first sight there appears to be no regularity whatever in the
distribution of the lines, except perhaps above wave-length 502,
where they appear to be about equally spaced in small groups of
three or four lines each. Without the aid of the fluorescence spectra
of the vapor excited by monochromatic light, it is doubtful whether
any regular series of lines could be found in the magnetic spectrum,
for, as has been subsequently found, more than half of the lines in the

WOOD. — SPECTRA OF SODIUM VAPOR. 239

series are absent, and there are six or more series present. The fluores-
cence spectrum with white-light excitation is shown on Plate 1, e, which
is from a negative made with the twelve-foot grating. As will be seen,
the bright lines coincide with the bright lines of the magnetic spectrum,
though much broader. It will be easier to explain how the series were
picked out after we have commenced the study of the fluorescence. I
have added to Plate l spectrum i, the magnetic spectrum with the series

Gkeen Rotation Spectrum.

5225.34

7

5040.65

2

4839.56

5218.49

2

5033.54

9

4837.49

5212.02

2

5025.66

2

4819.43

5186.70

3

5003.12 broad

1

4814.60

5179.71

10

5001.57

1

4812.68

5172.98

5

4979.34

3

4810.16

5171.98

2

4970.85

3

4802.62

5169.04

1

4967.10

5

4792.67

5165.85

1

4964.39

3

4782.89

5147.50

9

4962.85

1

4777.00

5140.71

1

4958.62

1

4766.94

3

5133.73

4

4933.93

6

4756.69

3

5126.54

5

4932.64

1

4752.04

2

5119.34

3

4924.32

2

4738.51

1

5095.70

4

4912.10

4

4727.52

2

5094.78

4904.67

1

4716.90

7

5087.31

4903.38

1

4715.63

7

5079.78

4896.65

1

4703.78

2

5071.58

4894.58

2

4692.54

1

5052.83

4892.77

2

4670.30

1

5049.56

2

4883.81

5

5048.49

3

4865.59

indicated. There appear to be five distinct series and a number of lines
which thus far have not been brought into any definite relation with
one another. These series we will number 1, 2, 3, 4, and 5. All the
lines belonging to the first series have one dot under them, those be-
longing to the second have two dots, etc. These series are shown
separated on the chart (Plate 5) at the top. Absent lines are indicated
thus : 0-

The fifth series is at the top, the fourth next, and so on down, the
extra lines being indicated in the lower row. This arrangement is

240 PROCEEDINGS OF THE AMERICAN ACADEMY.

considered provisional : it is the best that I can do at the present
time, and I believe that it is correct in the main. We shall see pres-
ently, however, that photographs of the fluorescence stimulated by
monochromatic radiation will have to be made with the large concave
grating before we can be absolutely sure of all of the lines. We will
drop the magnetic spectrum for the present and consider

The Fluorescence Spectrum.

In the previous paper I have described some of the remarkable
changes which take place in the distribution of energy in the fluo-
rescence spectrum of sodium vapor when the wave-length of the
exciting light is changed. With white-light stimulation the general
appearance of the spectrum is shown in Plate 4, Figure 6, A. There
is, in addition, a broad double band at the position of the D lines, and
a red-orange spectrum which, when the vapor is dense, is distinctly
banded. In the present paper we shall be concerned chiefly with
the portion figured above, for it is in this region that most of the
remarkable changes occur. As will be seen, it is comprised between
wave-lengths 460 and 570, and is devoid of any apparent regularity in
the distribution of its lines, except in the region above X = 505 where
we have lines spaced with considerable regularity, the spacing becoming
less as the wave-length increases. The distribution of intensity in this
portion of the spectrum is such as to give it a fluted appearance, the
flutings being most conspicuous in the region between A = 505 and
X = 535. With white-light stimulation the flutings cannot be made
out above 540, as can be seen from Plate 4, Figure G, B, in which the
upper limit of this part of the spectrum is shown. The fine lines are
present in this region, becoming, however, less and less distinct as the
upper limit of the spectrum is approached. If, now, instead of stim-
ulating the vapor with white light, we employ blue light in the region
460-465 obtained from a spectroscope for the excitation, the fluorescent
spectrum presents a totally diff'erent appearance (Figure 6, C). The
blue region, corresponding in its range to that of the exciting light
(indicated by a double arrow), appears as before, and the upper limit
of the spectrum between wave-lengths 540 and 565, the intermediate
jxjrt'ton being entirely absent, as shown in the lower spectrum of Fig-
ure 6, C. Furthermore, at the upper or yellow end, there now appear
the flutings, which were absent when the fluorescence was stimulated
with white light.

If, now, we gradually increase the mean wave-length of the exciting
light, the region of maximum intensity in the fluorescence spectrum

WOOD. — SPECTRA OF SODIUM VAPOR. 241

moves down from the yellow into the green, as is shown by the remain-
ing photographs in Figure 6, C. Moreover, as I pointed out in the
previous paper, the positions of the fluted bands change slightly, the
positions of the individual lines which make up the bands remaining
fixed however, the shift resulting from a change in the distribution of
intensity among the lines. The reason of this curious phenomenon
will appear when we come to the study of the fluorescence spectrum
excited by strictly monochromatic radiations.

The spectrum stimulated by white light I have named the "complex
fluorescent spectrum," for it has been found that it is a superposition of
a number of simpler spectra, any one of which can be independently
excited by suitably controlling the wave-length of the stimulating light.
Indications of something of this sort were found last year, and were
described in the preliminary paper. An insufficient number of photo-
graphs were obtained, however, at the close of the university year,
to make anything like a complete analysis of the complex spectrum
possible.

During the past winter and spring a careful study has been made of
the relations existing between the complex fluorescent spectrum, the
absorption spectrum, and the bright-line rotation spectrum described
in the earlier paper. The fluorescent spectrum has at last been photo-
graphed with the twelve-foot concave grating, enabling a study to be
made of its more minute structure.

Some very remarkable eff"ects have been observed with monochro-
matic stimulations obtained by the isolation of certain lines from
metallic arcs, which yield comparatively simple fluorescent spectra
made up of mdely separated sharp lines, placed in many instances
at nearly equal intervals along a normal spectrum. A given series
of lines can be brought out by stimulating with light of any wave-
length corresponding to that of some line in the series, but when the
stimulations occur at certain points, some of the lines may be absent,
gaps appearing in the series. The most conspicuous example is the
case of stimulation with the cadmium line 480, which will be considered
in detail presently. It will be remembered that certain lines are absent
in each series, in the magnetic spectrum.

The apparatus employed in the experiments was essentially the
same as that used in the earlier work. It consisted of a seamless tube
of thin steel three inches in diameter and thirty inches long, with a
steel retort at its centre in which a large amount of sodium could be
stored. The retort was made by fitting two circular disks of steel to a
short piece of tubing, just large enough to slip snugly into the larger
tube. The circular ends of the retort were provided with oval aper-

TOL. XLII. — 16

242 PROCEEDINGS OF THE AMERICAN ACADEMY.

tures, as shown in Plate 3, Figure 1. The retort was half filled with
sodium, the molten metal being poured in through one of the apertures.
It was then introduced into the tube and pushed down to the centre,
after which the plate-glass ends were cemented on, as shown in the
figure. This arrangement prevented the rapid diffusion of the vapor,
and enabled a large supply of metal to be kept at the centre of the
tube. The tubes used in the earlier work required re-charging after
two hours' continuous operation, while the retort tube could be
operated for several hundred hours on a single charge.

The tube was exhausted with a Fleuss pump and heated at the
centre with a large burner, the ends being kept cool by jackets
of absorbent cotton which dipped into pails of water.

The illuminating beam of either white or monochromatic light was
focussed just within one of the oval apertures of the retort, falling
upon the opposite wall a little to one side of the other aperture. By
covering the further end of the tube with a black cloth, the fluorescent
spot showed against the dead black background of the second oval
aperture, and its spectrum was therefore uncontaminated with the
exciting radiations.

A large three-prism spectrograph was constructed for photograph-
ing the spectra. The prisms were of clear dense flint four inches in
height, and the focal length of the lenses thirty-six inches.

Since only lenses such as are used for telescopes were available,
the spectrum lines are not so sharp as one would wish, except near the
axis of collimation. By adjusting things so that the centre of the
fluorescent spectrum fell at this point, the definition was pretty fair
throughout its extent, and wave-lengths could be determined with
an error not greater than one or two Angstrom units.

The photographs of the complex spectrum of the fluorescence ex-
cited by sunlight, obtained with this instrument (Plate 4, Figure 6),
showed peculiarities which made it appear of the utmost importance
to study the spectrum under higher dispersion. The green fluorescent
spot had, after repeated improvements in the apparatus, attained such
brilliancy that I felt sure that records could be obtained with the
twelve-foot concave grating. An all-day exposure was found to be
sufficient, the resulting spectrogram, with the iron comparison lines
and the wave-length scale, being reproduced on Plate 1, Figure 2.
The scale was printed separately, and slight errors occur, due to stretch-
ing and shrinking of the prints. They are not greater in any case
than 1.5 A. E. This plate shows the minute structure of the complex
spectrum, and enables us to measure the wave-lengths of the bright
lines with far greater accuracy than could be done with the plates

WOOD. — SPECTRA OF SODIUM VAPOR. 243

made with the prism spectrograph. As much of the detail is lost
during the process of reproduction, I have prepared a very careful
drawing of one of the groups of bands at wave-length 5200 (Plate 4,
Figure 5). The drawing was made from a print with the aid of a
hand magnifier, and the peculiarities shown are found throughout the
entire spectrum.

The bright lines are sharp, and quite as narrow as the iron lines of
the comparison spectrum. We must remember, however, that the
slit was not very narrow, 0.2 mm. perhaps, and it is quite possible
that a further contraction would not decrease the width of the
fluorescent lines. Each bright line is in general accompanied by
two lateral wings, which terminate quite sharply, the narrow spaces
between every two adjacent wings appearing as narrow dark lines.
These wings do not in general appear with strictly monochromatic
stimulation. In the work of last year, when studying the remarkable
changes which occur in the spectrum stimulated with the fairly
homogeneous light furnished by the monochromatic illuminator with
very narrow slits (see previous paper), I observed that as the wave-
length of the light was very gradually altered, the fluorescent lines
appeared with wings first on one side and then on the other, the
change in the appearance of the line reminding one of a flag flying
first on one side of the mast and then on the other. With the strictly
monochromatic illumination obtained with the isolated metallic arc
lines, the fluorescent lines are usually devoid of wings, though in
some instances the wings are found, and sometimes the wings appear
without the lines. These circumstances appear to indicate that the
wings are due to the stimulation of the electron by frequencies slightly
greater and slightly less than its own natural frequency.

I have not yet had time to repeat last year's experiments with
the monochromatic illuminator, and plan to make a further study
of the changes which accompany very gradual changes in the wave-
length of the exciting light. The observations are very difficult and
uncertain, as the light furnished by the monochromatic illuminator is
not very bright when its slits are made as narrow as possible and the
fluorescence spectrum can only be observed by carefully rested eyes.
Probably by using a large prism spectroscope as an illuminator better
results can be obtained. What is most desired is a light siren !

Analysis of the Complex Spectrum. Stimulation with
Monochromatic Light.

It was found impracticable to use the monochromatic illuminator
for the study of the simple spectra which made up the complex

244 PROCEEDINGS OP THE AMERICAN ACADEMY.

spectrum. Even with its slits very narrow, the wave-length range
of the emitted light was wide enough to cover several of the absorp-
tion lines of the vapor. The earlier work had shown that the light of
the cadmium spark was capable of exciting fluorescence, and ex-
periments were accordingly started with metallic arcs. Just at this
time came the very opportune invention of the fused quartz metallic
arc lamps by Stark, working in the Heraeus laboratory at Hanau.
Two of these lamps were immediately ordered, one filled with cad-
mium, the other with zinc. Their form is shown on Plate 3, Figure 1.
The lamp is kept in communication with a mercury pump during its
operation and stands in a disk of water. The cadmium lamp worked
well on a circuit of 110 volts direct, but the zinc lamp gave better
results on the 220. They are started by a small induction coil, one
terminal of which is connected to the negative pole of the lamp,
the other twisted around the quartz U tube. A blast lamp is directed
against the tube until the portion above the metal electrodes is
red hot, the coil is then started, and the arc usually forms at once.
As exposures of eight or ten hours were often necessary, and the lamps
have a trick of going out every half- hour or so, an automatic starter
was devised, which turned on the coil the moment the lamp went out.
As soon as the arc struck again, the coil was stopped. This arrange-
ment is figured on Plate 3, Figure 2, and consisted of a small electro-
magnet in circuit with the lamp, which pulled a steel spring away
from a brass screw as long as the lamp burnt. The spring and screw
were inserted in the primary circuit of the coil.

The cadmium lamp burns with a greenish-blue light of dazzling bril-
liancy, the zinc lamp with a curious purple light, which causes all the
woodwork in the room to appear blood-red, while most other objects
appear bluish white or purple. Both lamps excite a brilliant fluores-
cence of the sodium vapor when their images are thrown upon the oval
aperture of the retort. In this case the fluorescence is excited by
several different radiations. Various devices were used for picking out
one line at a time. The cadmium radiations which are capable of
exciting fluorescence have wave-lengths 5086, 4800, and 4678. Color
screens and the Fuess monochromatic illuminator, as well as the thin
crystals of chlorate of potash (described in the Phil. Mag. for June),
were tried ; also a block of quartz, cut perpendicular to the axis, placed
between two nicols. The arrangement which gave the best results, and
appeared to be accompanied with the least loss of light, is the one
figured on Plate 3, Figure 2. One vertical tube of the lamp is used as
the source, the light from which, after collimation, passes through a
large bisulphide of carbon prism, and is focussed upon the retort by an

WOOD. — SPECTRA OF SODIUM VAPOR. 245

achromatic telescope objective with an aperture of 12 cms. and a focal
length of 2 metres. The dispersion of the prism was sufficient to sep-
arate completely the monochromatic images of the lamp, any one of
which could be thrown into the aperture, the light passing by the edge
of the 90'' prism by means of which the fluorescent light was reflected
through a lens and thence upon the slit of the spectroscope.

The sources of light which have thus far been successfully employed
in stimulating the fluorescence of the vapor are the following : quartz arc
lamps containing cadmium, zinc, and thallium ; ordinary arcs between
lead, silver, bismuth, and copper electrodes ; lithium, sodium, and
barium arcs, and vacuum tubes containing helium and hydrogen.

Unfortunately the quartz lamps are very expensive, and become
almost useless after a run of about thirty hours, the surface becoming
granular and an opaque black deposit forming on the inner walls. As
exposures of eight hours are sometimes necessary, it will be seen that
lamps at S30 apiece, with an average life of thirty hours, make the
investigation an expensive one.

The photographs of the fluorescent spectra obtained with mono-
chromatic stimulation are reproduced on Plate 2.

After each exposure the D lines were recorded on the plate, so that
the difi'erent spectra could be brought into coincidence for purposes of
comparison : the D lines will be found at the extreme right in each
spectrum. The photographs have been reproduced as negatives, and
the point or points coinciding with the wave-lengths of the stimulating
light are indicated by arrows. A large scale drawing or chart of the
most interesting of these spectra, together with others too faint for
reproduction, has been made on cross-section paper, the points of
excitation being indicated by arrows, as in the photographs (Plate 5).

Drawings of the complex spectrum and the magnetic rotation
spectrum made from the photographs obtained "with the large concave
grating will be found at the bottom of the chart : the former is a posi-
tive. At the top I have given a composite drawing which represents a
superposition of all the simple fluorescent spectra thus far obtained.
Immediately below it will be found the spectra excited by the complete
radiation of the cadmium and zinc tubes. In each case there are three
difi'erent exciting radiations simultaneously applied, yet it is almost
impossible to find two fluorescent lines which coincide. The other
spectra are excited for the most part by a single monochromatic radia-
tion, the wave-length of which is indicated by the arrow. I have not
yet obtained photographs of the fluorescent spectra excited by the
separated radiations of the copper arc or by the separated zinc lines
468 and 472 ; consequently these have been drawn together. It is

246 PROCEEDINGS OF THE AMERICAN ACADEMY.

possible, however, by comparing the spectrum excited by copper with
the one excited by zinc 4811, to make a guess as to which lines belong
together.

We will begin by a study of the spectra excited by the cadmium
radiations.

Cadmium Stimulation.

Photographs of the fluorescent spectrum obtained with the cadmium-
arc excitation are shown on Plate 2, h, i, j, k.

Of these, i and k are excited by all three cadmium lines ; the former
taken with a much narrower slit than the latter. Spectrum h was taken
when the sodium vapor was excited by the line 480 ; observed visually,
it consists of twelve bright lines, in groups of two and four, as shown
on the chart immediately above the complex spectrum at the bottom.
Midway between the groups very faint lines can be perceived if the eye
is carefully rested. The strong lines are arranged thus: two, absent
line, four, absent line, two, absent line, four. The absent lines, or,
more correctly speaking, the faint lines, evidently belong to the same
series, and taken collectively the lines will be found to be very nearly
equidistant, measured along a normal spectrum.

The wave-lengths of the lines in this series, as determined from
measurements of the plates obtained with the prism spectrograph, are
as follows :

A.

\ differences.

A.

X differences.

4760

4800-

4838-

. . .34

. . .38

5095
5133-

-'^ 38
. . .38

• • •

^# 35

. . .

^^ 37

4908

. . .38
. . .37
. . .39

5207

. . .38
. . .38
. . .38

4946-
4983 •
5019'

5245'
5283-
5321-

These wave-lengths I consider to be accurate to within about 2 A. E.
or \ of the distance between the D lines.

It is, of course, of the utmost importance to determine the law which
governs the spacing of the lines in the simple spectra. A criterion
may perhaps be obtained by referring to the magnetic rotation
spectrum of the vapor, the lines of which correspond in general to the
lines of the fluorescence spectrum. This spectrum has been photo-
graphed with a large concave grating and the wave-lengths determined
certainly to within a tenth of an Angstrom unit. The strong lines at

WOOD. — SPECTRA OF SODIUM VAPOR. 247

the following points of the spectrum form a series analogous to the
series obtained with the cadmium 480 series.

A.

A differencea.

5119.34

5079.78*

. .39.56 A

5040.65 •

. .39.13

5001.57 •

. .39.08

4962.85 •

. .38.67

4924.32 •

. .38.52

This we have called the first series.

The wave-length differences are, in this case, much more nearly con-
stant, and decrease progressively.

The lines of this series are especially conspicuous in the magnetic
rotation spectrum (Plate l. Figure 1, c), hence I have mentioned it first ;
they appear in the fluorescence excited by the lead line 5001, as will
be seen by reference to the chart, Plate 5.

If now we try to fit one of the magnetic series to the cadmium 480
fluorescence series, we find that the third magnetic series coincides
with it between 5019 and 5134, while in the violet region it coincides
with the fourth magnetic set. I do not feel sure whether this peculiarity
is due to slight errors in the determination of wave-lengths or not.
I think not, however, for I have very carefully superposed the two
negatives (cadmium fluorescence and magnetic rotation spectra), both
taken with the same instrument, and find the same disagreement.
We cannot be sure of anything, however, until the cadmium series
has been photographed with the grating. During the coming year I
expect to photograph the fluorescence spectrum excited by cadmium
and zinc radiations with the large concave grating. It will then be
possible to determine the wave-lengths of the lines to within a tenth
of a unit.

One of the most remarkable facts connected with the appearance
of the lines of a series is that the distribution of energy among
the individual lines depends upon the point of excitation. Unfortu-
nately there are very few arc lights bright enough to excite fluor-
escence. It was found, however, that the silver line 5207, which
coincides with one of the fluorescent lines of the cadmium 480 series,
was bright enough for the purpose. The silver was carefully fi-eed from
copper, as the neighboring copper lines are powerful exciters ; in tlieir
absence, no prismatic separation was necessary, as the rest of the silver
lines were inoperative. A photograph of the fluorescence spectrum

248 PROCEEDINGS OF THE AMERICAN ACADEMY.

obtained with silver stimulation is shown on Plate 2, g. The series in
this case has no gaps in it, the line at 5170, which is absent with
cadmium excitation, coming out strong (see chart as well). The
monochromatic illuminator, with its slits reduced to the width
of a hair, was arranged to furnish light of wave-lengths cor-
responding to other lines in the series, and photographs obtained
which are recorded on the chart. It will be seen that faint or missing
lines occur in each case, but that their position varies with the point
of excitation. If we consider each line caused by a single electron or
vibrator, the phenomena suggest that the vibrators are united in some
way, perhaps in a closed ring, and that when the system is set in
vibration there are nodal points, the position of which depends upon
the point in the chain where the periodic force is applied. Moreover,
as has already been pointed out, if the force is applied at the " high
frequency" portion of the chain, the regions excited are those of
highest and lowest frequency, the intermediate portion appearing to
be at rest. This is especially noticeable in the case of the bismuth
excitation. (Plate 2, e, and chart.)

In addition to the Hues enumerated above, there are a number of
others at the upper end. These do not appear to be distributed with
the same regularity, though some of them may form an extension of
the series, or more probably may be the beginnings of other series. In
general it has been found that in the simple spectra the lines are reg-
ularly spaced between the extreme violet end and a point at about
X = 5350. Above this point the spacing is generally very irregular,
and it is difficult to unravel the spectrum. Of this more will be
said later.

"We will next take the fluorescent spectrum excited by the green
cadmium line 5086.

This spectrum is remarkable in that it is made up of eleven pairs of
lines regularly spaced (Plate 2, j and chart). The other two cadmium
lines appear on the plate, as the spectrograph was not shielded from the
diffused light from the lamp.

A series in the magnetic spectrum coincides with the series formed
by the shorter I member of each pair. The wave-lengths and differ-
ences are given in the following table :

A. A differences. K. A differences.

5165.85 ... -7J*6A 38.82

5126.54 •:;^-^.^ 4970.85

5087.31 • • • • ':^ti 4932.64 " " " " f^l^

5048.49- • • •^^•^'^ 4894.58- ' ' ' ^^"'^^

WOOD. — SPECTRA OF SODIUM VAPOR. 249

I am quite at a loss as to how the series formed by the other mem-
bers of the doublets is originated. It appears to coincide with the series
excited by helium 5014, as will be seen by reference to the chart. It
appeared at first as if the exciting line might lie between two adjacent
fluorescent lines, and in that way excite a double series, but cadmium
5086 is slightly on the short X side of the magnetic line 5087.3, while
the wave-length of the other line of this pair is 5092, i. e. on the long
X side.

This is the only case recorded where a spectrum of doublets is
excited by monochromatic stimulation, though I am of the opinion
that the copper line 5152 behaves in the same way.

What is still more remarkable is the fact that if the excitation is at
a different point we no longer get doublets. The lithium line at 4971
takes hold of one of the more refrangible components of one of the
doublets, but only a single series of lines appears in the fluorescence
spectrum (see chart). The other series, i. e. the less refrangible com-
ponents, can be separately excited by stimulation with the helium line
5014 (see chart). If we are dealing with anything in the nature
of electron doublets, we should expect both the lithium and helium
radiations to excite a fluorescence showing double lines.

If we try to explain the phenomena by assuming two chains of
electrons fastened together at the point 5086, we must account for
the fact that the 5086 vibrator excites the other chain when it is
acted upon by light of its own frequency, but not when it is vi-
brated by the lithium radiation acting at a different point on the
chain. I have adopted this hypothesis of electron chains merely to
aid in describing the physical phenomena, and not with much hope
that it will explain anything.

It seems much more likely that the different lines represent vibra-
tions of different frequencies of the same system. We must not try to
make the molecule too much like a piano. The vibrations may be
ripples running over its surface or they may be unlike anything with
which we are familiar. If we had never seen a bell, it would be diffi-
cult to work out the theory of its very complicated vibrations from a
study of a set of simple pendulums. Possibly stimulation at some
other points might give rise to the double lines.

I attempted to do this with the monochromatic illuminator, but
without success. The band of exciting light cannot well be made
much narrower than the distance between the components of the
doublets. Even with the instrument set at 5086, I could detect no
evidence of the doublets. I am planning to investigate this matter
further with a larger monochromatic illuminator designed to furnish
more nearly monochromatic light.

250 PROCEEDINGS OF THE AMERICAN ACADEMY.

In addition to the eleven pairs of lines in the fluorescence spectrum
excited by cadmium 5086 there are two strong lines at wave-lengths
5305 and 5341. These seem to belong to the same series, and the
former has a faint companion, the two forming a doublet. The line
5341 is also accompanied by a companion, which, however, is so faint
as to be barely distinguishable.

The spectrum excited by the more refrangible of the two blue cad-
mium lines 4678 is reproduced only on the chart. It consists of a
regular series of five lines in the blue region, and a large number of
irregularly spaced lines of widely different intensities in the yellow-
green region. None of these lines appear to be represented in the
magnetic spectrum.

This spectrum illustrates well the characteristic peculiarity of the
sodium fluorescence spectrum, that stimulation at the more refrangible
end excites powerful fluorescence at the opposite end. The lines which
form the regular series we may call directly excited, the others in the
yellow region indirectly excited. The latter in all cases seem to be
irregularly spaced. The great problem to solve is to determine the
nature of the mechanism and find out how the low-fi:equency vibrators
are set agoing by the stimulation of the high-frequency ones, while they
remain quiescent when the stimulation is at the middle of the spectrum.
Speculations on these points must be deferred for the present.

Zinc-arc Excitation.

The complete fluorescent spectrum excited by all three of the zinc
lines (i. e. the total radiation of the lamp) is shown near the top of the
folding chart, just below the cadmium fluorescence. It is scarcely
possible to find a coincidence of two lines. The two spectra placed
side by side make a striking picture of the variation produced by
different excitations of the same fluorescing medium. A photograph
of the spectrum is reproduced on Plate 2, c.

Exciting with the zinc line 4811 alone gives us the spectrum shown
on Plate 2, b. The other two zinc lines are of course present on account
of diff'used light. Referring now to the chart, we find that the violet
end of the spectrum agrees pretty well with the fifth magnetic series,
though other lines are present. The two strong lines at 5188 and 5225
also appear to belong to the same series. The lines on the whole are
much less regularly distributed than in the case of the cadmium 480
excitation. The three wide pairs between 523 and 535 are peculiar to
this excitation.

The fluorescence excited by the other two zinc lines, 4680 and 4722,
is also recorded on the chart. These lines are so close together that it

WOOD. — SPECTRA OF SODIUM VAPOR. 251

was found impossible to illuminate the vapor with light from but one
of them, and have at the same time sufficient illumination to excite
much fluorescence. I have not yet found much evidence of regularity
in the distribution of the lines in this case, though there is undoubted
evidence of two series in the immediate vicinity of the exciting lines.
I have indicated with the letters A and B the lines which appear to
belong together (compare with helium excitation). We have an
enormous number of lines in the yellow-green region, since we have a
double stimulation at the opposite end of the spectrum. There seems
to be some regularity here, but it is difficult to say which lines belong
together.

Bismuth Excitation.

The light of the bismuth arc makes a beautiful stimulus for the
fluorescence, since it contains but a single operative line, the strong
one at 4724. It gives rise to a very regular series in the blue-violet
region, the lines appearing to fall midway between the lines of the
third and fourth magnetic series (Plate 2, e, and chart). Though the

o

wave-length of the exciting line is only two Angstrom units longer than
that of the zinc line 4722, the spacing of the series in the two cases is
quite different. The same thing has been noticed in the case of the
shortest cadmium and zinc lines, which makes it seem possible that in-
teresting results may be obtained by altering the wave-length of the
exciting line, either by pressure or a powerful magnetic field. Exper-
iments in this direction will be made next winter.

In both of these cases, in each of which we have excitation by lines
of nearly the same wave-length, the wider-spaced series is produced
when the stimulation is by the longer wave-length. It remains to be
determined whether we take hold of different absorption bands and
excite entirely different series, or whether we stimulate the same vi-
brator in each case, the spacing of the resulting lines depending upon
how nearly we approach its natural period in our exciting vibrations.

In addition to the regularly spaced lines in the violet, we have a
complex assortment of lines in the yellow-green region, the intervening
portion being totally devoid of lines. One of these lines, A. = 5.300, has
a broad diff"used wing, and it is perhaps worthy of remark that in the
spectrum excited by the two zinc radiations we have a hazy doublet at
this point, in the spectrum excited by zinc 4811, a single line, and in
the spectrum excited by cadmium 480, two faint lines. Some of the
other lines have wings, as will be seen from the chart, and at wave-
length 546 we find a broad hazy band. All of these peculiarities com-

252 PROCEEDINGS OF THE AMERICAN ACADEMY.

plicate tilings, and I have drawn attention to them merely to show that
we must not expect to explain matters by too simple a mechanism.

A word or two about the bismuth arc may not be out of place.
Various plans were tried, such as immersion of the electrodes in water,
burning in the carbon arc, etc. The best arrangement was found to be
a shallow iron dish about 4 cms. in diameter (pounded from a piece
of thin sheet iron), filled nearly full of molten bismuth, and kept hot
over a small burner. The dish of metal formed the positive electrode,
the negative being a bar of iron which could be raised or lowered by
a rack and pinion. The arc required constant attention, fresh metal
being put into the dish every ten or fifteen minutes, and as exposures
of eight hours were necessary, it will be seen that an enormous amount
of very fatiguing work was necessary in all cases where open-air arcs
were used.

Copper Excitation.

I have been unable thus far to obtain photographs of the fluorescence
excited by the separated copper radiations. The lines are close together,
and the arc climbs about over the electrodes. I hope next year to im-
prove matters in this respect. On Plate 2, a, is seen the fluorescence
excited by the total copper radiation. Only the three green lines are
operative in stimulating the vapor. The lines in the fluorescence spec-
trum appear to bear no very definite relation to the lines of the magnetic
spectrum, as will be seen by the chart. There are many coincidences,
however, with lines in the spectrum excited by zinc 4811, and by zinc
468 and 472. By comparing the three spectra I have made a provi-
sional determination of the lines which belong together in the spectrum
excited by the copper radiation. These lines are indicated by crosses
and vertical dashes placed above them ; other lines, which do not appear
in the zinc spectra, have not been marked. I suspect that excitation
with copper 5152 will produce a doublet at this point, and probably at
other points, j ust as does cadmium 5086. An attempt will be made
to verify this surmise. I have on one or two occasions, when trying to
stimulate the vapor with this isolated line, been of the impression that
I saw doublets distinctly, but at the time I attributed it to incomplete
separation of the exciting lines.

Lead Excitation.

A lead arc, operated in a manner similar to the one described for
bismuth, was used for exciting the vapor. The only line operative was
the one at 5001, and it gave rise to a well-marked series of fluorescence
lines, which coincided exactly with the first series of the magnetic rota-

WOOD. — SPECTRA OF SODIUM VAPOR. 253

tion spectrum. It is worthy of remark that one of the extra lines of
the magnetic spectrum lies very close to the exciting line, yet none of
these lines appeared in the fluorescence spectrum. The fluorescence
excited by lead was very feeble, and even with an eight-hour exposure
the lines were very faint.

Helium Excitation.

A large "end on " helium tube with a 3 mm. bore was constructed
for the investigation. This tube could be run continuously with an
induction coil yielding a heavy ten-inch spark. An exposure of about
twelve hours was given. Two of the helium lines are operative : line
5015 gives a well-marked series, the lines of which fall exactly midway
between the lines of the second and third magnetic series; line 4713
gives a good series in the blue and at least six distinct lines in the
yellow-green, the wave-lengths of which can be seen from the chart.
The exciting line in this case coincides with one of the lines in the
spectrum excited by zinc 468, and there is perfect agreement in position
between the fluorescent lines in both cases, not only in the blue, but also
in the yellow-green region. The lines in the spectrum excited by line
468, or at least as many as could be identified, have been marked.
The identification was of course made by comparison with the spec-
trum excited by helium.

Lithium Excitation.

An arc was caused to play between a carbon rod and a large carbon
block on which the lithium salt was placed. The image of the red
flame was projected upon the window of the retort and excited a bright
fluorescence. Two of the lithium lines were operative, — one at 4601,
the shortest monochromatic stimulation thus far found, which gives
the series in the violet (see chart), and a large number of lines in the
yellow-green ; and another at 4971, which gives a beautiful series in the
green, coinciding exactly with the second magnetic series. The 4971
stimulation should be especially interesting, since there are several lines
in the magnetic spectrum very close to it. The line is unfortunately
not very bright, and the fluorescence lines were so feeble that they
could only be measured with difficulty.

The lines in the yellow-green region are also of considerable interest,
since they result from a single monochromatic stimulation applied prac-
tically at the extreme lower end of the fluorescence spectrum. In fact,
this line is considerably below the limit of the fluorescence spectrum
as usually seen with white-light stimulation : this limit is not far from

254 PROCEEDINGS OF THE AMERICAN ACADEMY,

wave-length 4670, which is the shortest thus far detected in the mag-
netic spectrum photographed with the grating, though faint lines are
visible even below 4600 on negatives made with the prism spectrograph.
There seems to be evidence of a number of series in the yellow- green
region, the spacing, however, decreasing with increasing wave-length,
just the opposite of the state of things which holds in the blue-green
region. It is more likely, however, that the apparent decreasing of
the spacing as the yellow end of the spectrum is approached is due to
other series similar to those which are found in the green and blue, the
nearness of the lines resulting from the large number of superposed
series. With white-light stimulation no trace of the lines can be seen
above wave-length 555, and they are so faint as to be almost indistin-
guishable for a considerable distance below this point. The broad
flutings seen in the spectrum stimulated with white light are doubt-
less to be referred in some way to the circumstance that the lines of
the different series get into and out of step periodically : they may
thus be considered analogous to the bands seen when two diffraction
gratings of slightly different spacing are superpoaed.

Barium Excitation.

The fluorescence excited by the barium arc appears to be due chiefly
to the line 4934, which coincides with one of the extra lines in the
magnetic spectrum. Line 4932 of the second magnetic spectrum is
also very near it, and we find that the fluorescence spectrum contains
lines which coincide with the magnetic lines of the second series, as
well as lines which coincide with some of the extra magnetic lines.
The barium arc contains a good many other fainter lines which may
give rise to some of the fluorescent lines. It will be necessary to re-
peat the experiment with the 4934 line isolated.

Sodium Excitation.

As I showed in the earlier paper referred to, if we stimulate the
vapor with intense sodium light, we obtain a yellow fluorescence
which the spectroscope shows to be made up of two lines in the position
of the D lines. We have here a re-emission of light of the same wave-
length as the exciting light, and nothing else. This I have called
resonance radiation, as we may find that it is different from fluores-
cence, though the two are doubtless intimately related. As there are
several pairs of lines in the ultra-violet which belong to the same
series as the D lines, it seemed of great importance to determine
whether these appeared in the spectrum of the fluorescence excited by

WOOD. — SPECTRA OF SODIUM VAPOR. 255

the sodium flame. The sodium tube was provided with a quartz
window, and the light of the oxyhydrogen flame, heavily charged with
sodium, focussed upon the aperture of the retort with a glass lens.
White light from the arc was also used, as this excites the D line vibra-
tions in the fluorescence. The spectrum was photographed with a
small quartz spectrograph, and though the D lines were greatly over-
exposed, no traces ofany of the ultra-violet doublets were found on the
plate. Conversely, illumination with ultra-violet light in the region of
the first ultra-violet pair of lines failed to produce any visible fluores-
cence. It was hoped that a faint yellow fluorescence might be produced
in this way, due to emission in the region of the D lines. I have not
yet tried stimulation with Di and D2, alone, to see whether both D lines
appear in the fluorescence. This will be a very difficult experiment,
and I am saving it for the last. It will settle the question as to
whether the principal series of sodium is a series of doublets or two
series of single lines.

Cathode-ray Excitation.

The cathode rays, I find, excite a fluorescence similar to white light.
The lines of the principal and subordinate series appear as well, some
of them of overpowering intensity. The apparatus for the electrical
excitation is shown on Plate 3, Figure 3.

It consisted of a steel tube 3 cms. in diameter and 35 cms. in length,
one end closed with a glass plate, the other cemented with sealing-wax
to a glass tube carrying the cathode. The mercury pump was kept
in continuous operation to remove the hydrogen liberated from the
sodium. On looking into the tube through the glass window a blazing
spot of yellow light 2 cms. in diameter was seen at the point where the
cathode rays entered the vapor. Its spectrum was photographed with
the prism spectrograph, and is reproduced on Plate 2, n. In addition
to the fluorescent spectrum, and the sodium lines of all three series,
the hydrogen lines come out strong. I have never been able to elimi-
nate them entirely. Very few experiments have been made on the
electrical excitation, but some very curious phenomena have been
observed. In some cases, by looking into the tube in an oblique direc-
tion, it was seen that at the point where the cathode rays entered the
mass of vapor there was a bright green spot of fluorescent, light, while
at the point of exit there was an orange-yellow spot, the intervening
space being non-luminous. Seen in a direction oblique to the direction
of the rays, the two spots were seen completely separated. This I con-
sider a very remarkable circumstance, and a spectroscopic study
of the two spots of light will undoubtedly yield very fruitful results.

256 PROCEEDINGS OF THE AMERICAN ACADEMY.

Unfortunately the condition is a difficult one to keep fixed, for the phe-
nomenon only appears when the density of the sodium vapor is just
right and the surrounding vacuum high. As I have shown in the
paper on the dispersion of sodium vapor, we can have a dense mass
of the metal vapor, bounded on each side by a very high vacuum, a
very anomalous condition from the p ant of view of the kinetic theory
of gases. My impression is that the green spot will show the fluores-
cent spectrum, and the yellow spot the lines of the principal and sub-
ordinate series, as found in the sodium arc, but as yet I have not found
time to make even a visual examination. Several attempts have been
made, but by the time the image of the spot was thrown upon the slit
in the proper direction to pass the light through the prisms, and the
eye brought to the instrument, the conditions in the tube changed.

It is difficult to account for the absence of luminosity of the
centre of the mass and the two bright spots. Perhaps the condition
under which the rays excite fluorescence exists only where the vapor
mass is in contact with the vacuum, i. e. in the region where the h}^o-
thetical clusters of molecules are breaking up and flying to the cooler
walls of the tube. Even assuming this to be the fact, the difference in
the color of the two spots is still to be accounted for. Possibly the
cathode rays excite the green spectrum, while the canal rays travelling
towards the cathode excite the orange-yellow luminescence. I have
made one experiment with a similar tube arranged so as to deliver
a stream of canal rays against the vapor. The luminescence was
bright yellow, but the tube cracked before a spectroscopic examination
was made.

On the other hand, it may be that whatever causes the green lumin-
escence is removed from the ray bundle by absorption, the residue
exciting the yellow luminescence at the point of exit. If this is the
case, we should expect the same amount of yellow light in each spot,
and I am of the opinion that the green light is much too pure for this
to be the case. Further experimenting will be necessary before it is
possible to draw any very definite conclusions.

In the spectrum excited by the cathode rays the D lines are of
immense brilliancy, running together into a single band of light. On
each side of this are seen three or four symmetrically placed bands,
decreasing in brilliancy as they recede from the D lines in each
direction. No trace of these bands appears in the magnetic spectrum,
which in this region shows only fine lines arranged in narrow groups,
which do not coincide with the bright bands of the cathode lumin-
escence.

A photograph of these bands is reproduced in Plate 4, Figure 4.

WOOD. — SPECTRA OF SODIUM VAPOR. 257

They have some connection with the D lines, I feel sure, for they are sym-
metrically arranged on each side of them. If the photograph had been
made with a grating, we should of course call them ghosts. It may be
that they are analogous to satellite lines, but if they are, we are cer-
tainly dealing with the phenomenon on a grand scale, for the fourth
one is not far from the sodium doublet at 5688 ! All of these points
will be more fully investigated during the coming year.

Other Possible Excitations.

It has occurred to me during the preparation of this paper that
very interesting results would be obtained by exciting the fluorescence
with the light selectively rotated by the vapor in a magnetic field, i. e.
by the magnetic bright-line spectrum. This light is fairly intense,
and it would be interesting to see whether the intensity distribution
among the excited fluorescence lines was the same as in the magnetic
spectrum.

What I most need, however, is a set of screens which will enable
me to separate lines such as those of copper without resorting to the
systems of prisms and lenses. A good collection of solutions of the
rare earths would probably be very useful in the work. Erbium,
praseodymium, and neodymium I have, but I should feel very
grateful for the loan of any others which might prove serviceable, or for
any suggestions regarding other possible sources of monochromatic
light. As I have said before, the instrument most needed is a light

siren !

Composite Excitation.

At the top of the chart just below the magnetic series will be found
a spectrum containing about two hundred lines. This is a composite
drawing made by superposing all of the drawings made of the simple
spectra excited by monochromatic stimulation. It contains many lines
not found in the complex spectrum excited by white light. In the
latter, between wave-lengths 5000 and 5100, we find but ten or a
dozen lines, while in the composite spectrum there are at least twenty.
This circumstance is of interest in connection with the periodic dark
regions of the complex spectrum, which give it a fluted appearance.
The formation of these flutings requires further study, as their position
shifts as we alter the wave-length of the exciting light, which in this
case is a rather broad, isolated band from the continuous spectrum
obtained with the monochromatic illuminator. The phenomenon was
more fully described in the earlier paper, but requires further study.

VOL. XLIl. — 17

258 PROCEEDINGS OF THE AMERICAN ACADEMY.

The Series in the Magnetic Spectrum.

As we have seen, the complex fluorescent spectrum is made up of six
or more series of lines, the individual lines of each series being about
38 Angstrom units apart, the spacing becoming less as we pass from
yellow towards violet. The fact that the lines in the magnetic
spectrum coincide with the lines of the complex spectrum makes
it seem certain that the same series will be found there. By com-
paring the various fluorescent spectra with the magnetic spectrum,
and by measuring carefully the distances between the lines of the
latter, I have made a provisional assignment of the magnetic lines thus
far observed into five series.

The wave-lengths and wave-length diff"erences are given in the
tables on page 259.

As will be seen by reference to the chart, the first series has the
largest average spacing, and the fifth the smallest, the " scale," if the
term is allowed, decreasing gradually from the first to the fifth, the two
coming into coincidence at about wave-length 4860.

Doubtless these series could be extended to wave-length 5500 or
thereabouts by making use of the grating photograph of the complex
fluorescence obtained by white-light stimulation. The lines are,
however, so diffuse in their nature, with overlapping wings and other
peculiarities, that I have not yet attempted any further extension.
I think that by employing a much denser vapor the magnetic
spectrum can be considerably extended, and as the lines are much
sharper in this case, an extension of the series will be an easy matter.
The other series necessary to give the close spacing found in the
yellow may be discovered in this manner.

A theoretical discussion of the results will have to be deferred
to a subsequent paper. In fact, I prefer to have this side of the
subject attacked by those who have given especial attention to the
theory of molecular radiation. The absence of many lines in each
series in the magnetic spectrum, and the absence of certain lines in
the fluorescent spectrum, are especially suggestive. We have similar
conditions in other series of lines, as is well known, but the present
case is, so far as I know, the only one in which we can, by varying the
exciting conditions, bring about a change in the position of the absent
lines. It appears to me that the data furnished us by sodium vapor
ought in the end to enable us to choose between the various theories
proposed to account for spectrum series.

The investigations recorded in this paper have been made possible

"WOOD. — SPECTRA OF SODIUM VAPOR.

259

First Series.

A. A differences.

5119.34

5079.78 • • •

504().Go • • •

5001.57 • • •

4962.85 • • •

4924.32 • • •

39.56
39.13
39.08
38.67
38.52

Second Series.

A. A differences.

5165.85

5126.54 • • •

5087.31 • • •

5048.49 • • •
.... J 7^<Lt = 38.83

4970.85
4932.64 • • •
4894.58 • • •

.... ^51^1- = 37.57
4819.43
? 4782.89 • • •

39.31
39.23

38.82

38.21
38.06

36.54

• • ■ • u_|.^ = 37.63

4670

5211
5172
5133
5094

4979,

4903,

Third Series.

A differences.

71

82 • • •

73 • • •

,78 • • •

38.89
39.09
38.95

4865

4752
4715

LL.|.j^= 38.45

34

. JJ^aiL^ 37.98

38

59 • • •

. u_|.^^ = 37.8'5
04
63 • • •

37.79

36.41

FoDKTii Series.
A. A differences.

5219.00
5179.71 • • •
5140.71 • • •

39.29
39.00

• • • • LL5.o^^ 3:3 38.35
5025.66

• • • • LL|.jj^ = 37,85

4912.10

.... J^«-L = 37.30
4837.49

• • • • UL|.jjj =36.68

4727.52

. . . 34.98

38.64
39.20

38.00

? 4692.54

Fifth Series.

A. A differences.

5225.34

5186.70 • ■
5147.50 • '

.... -V- = 38.00
5071.50
5033.54

.... ^^2-9-^ = 37.46
4958.62

.... jji^^U:^ 37.40

4883.81

.... ^-3.5^5-:= 36.82

4810.16

.... -X_U(L(L:zz 35.83

4738.5

Extra Lines.

5096.00
6052.83
5049.56
5003.12
4964.39
4967.10

260 PROCEEDINGS OF THE AMERICAN ACADEMY.

through very generous aid given from the Rumford Fund by the
American Academy of Arts and Sciences.

I am also under great obligation to my assistant, Mr. F. L. Cooper,
for the many hours of very fatiguing work which he devoted to the
research.

Wood.— Fluorescence of Sodium.

o

a

3
O

O
o

3

T3

01

O

04

Oi

•-^.

>

>

-n

>

>

CO

o

o

o

3

c
o

a-

U)

o

IT

O

o

■o

w

■o

It

•n

I

o

(^

o

O

o

3

3

3

3

O

O

>

a

<

01

<^

3

(U

o

o

n

o
w

3-

c
c
3

3

c
3

Proc. Amer. Acad. Arts and Sciences. Vol. XLII.

Wood.— Fluorescence of Sodium.

Plate 2.

Ill

z

blue

green

yellow

n ^TTl]

jiiiiliiltlij|«tokili

iiiiiililidi

n^fllfl

fm

Prog. Amer. Acad. Arts and Sciences. Vol. XLII.

HELIOTYPE CO., BOSTON.

o

o
o

5

X

J

o

5
<

r~^^=^

..J

i-iij

ft"":^

Wood.— Fluorescence of Sodium.

Plate 4.

o

I

o

00

I

OQ
00

Fig. 4.

i

Fig. 5.

■wo 47f 4«a +»f iJo 49Sr 500 S9S Sio ytr fi* Sl^ f JO jjy 540 s-45- sfc

1

I II- I J

I I I

llllib^kit'iilll

'J

Fig. 6.
Prog. Amer. Acad. Arts and Sciences. Vol. XLI

Woou.'i'LuwhiLCtUiiL or iOLi

' I " ( „ V i ' .V . I T.I ■' 0«r,ffi .>

n

I

yj^fnetic S/>ectrum.

liil

TgT;ii;''i!;iHli#^q""i^H|;

i. Jl lljlj

n

] — -1-,-i^j

■I ■ -[ir:i''=H^''|gT-----l^;it)-:Hfr1==|=^^=^^'^t-'rrl ' I,- I '--}

ill

lUIp

=pf

o i...j.JiL:i

"'!:"■ ^1

t I

t

im

J

^mtf--mm^mvim^:^^m$

0 /"Jei-ies

Sxira Lines

f'M^iTj I' ^ p 1 1 ii I" I i M!":i-'!.i: I . .li^iii'-iii. . ii-'T^'T'qffwyi" I >^ ■<t*'''f' ''i;*'™~-lT:a:

l!llllli:lli;ilTHIii!llil:llMl ttll II III iil 1! II ill

: i I -^i-

W

I

10

4

13:

7-j:

JTLl

I! II-
Uli

f

mTTji!!i!]l

jjtjr

! M

jiini

M

i_L

if. iHj;

ni^

nil

' ., "LEAD SOOl

" " r ""; -i -

_ :!:!'!!1!i,

I I iil IMS I ; tn ! i jj— -rTin^TTFTiTf

-ffflWHWrP^ftB

;K|B"l'"--,rpP7nPMl

: 'lli?

It m

lit

IP

li — 7

ft t ' , ' '

l» I t ♦ ' I ■ ; I

I t I

-u^_^\.

i^' ' ^ rs._LjL:: ^.__«? ; ..I II ih: :

1

, hi 4tM

I 4714 <^B
4713 JH

tc'N. J

» I

♦ , J H" ♦ 'TT

iiiiii

T^1^-n-' r

ill I F

lllll^,i,fJ,i.jiHJ::iijililiiiil!:.|ilii^li.^l!if;:liy

Pwoc. AMEfi Acad. Afiii AND Sciences vol XLII.

1

L

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 14. — December, 1906.

RESULTS OF THE FRANCO-AMERICAN EXPEDITION

TO EXPLORE THE ATMOSPHERE IN

THE TROPICS.

By a. Lawrence Rotch.

RESULTS OF THE FRANCO-AMETIICAN EXPEDITION TO
EXPLORE THE ATMOSPHERE IN THE TROPICS.

By a. Lawrence Rotch.

Presented February 14, 190G. Received September 13, 190G.

It has long been believed that the ascending currents above the ther-
mal ei^uator proceed immediately over the northeast and southeast
trade- winds as southwest and northwest anti-trades. It is possible that
part of the anti-trade sinks down over the high barometric pressure in
the North and South Atlantic oceans and returns with the trade-winds,
but the greater portion descends north and south of the origin of the
trades and continues to the poles as the prevailing southwest or north-
west winds of the North and South Temperate zones, respectively.
The facts upon which this theory is based, as regards the Atlantic
Ocean, are mainly observations upon the Peak of Teneriffe, where the
southwest wind can be observed the whole year; and although it
is lower in winter than in summer, there are no observations which
prove that this anti-trade ever reaches the surface of the ocean.

The author, after he had made the first meteorological observations
over the ocean, with kites flown from a transatlantic steamer in 1901,
concluded that a vessel, which could be navigated at will, would enable
meteorological data to be obtained with kites independently of the
natural wind.^ He suggested the application of this method to
the exploration of the atmosphere in the trade-wind region at the
Glasgow meeting of the British Association in 1901, ^ and at the
Berlin Congress for Scientific Aeronautics in 1902.^ In order to or-
ganize such an expedition, applications for aid were addressed in 1902
to the Prince of Monaco, and in 1903 to the Carnegie Institution, but
without receiving the desired assistance. However, Professor Herge-
sell, President of the International Commission for Scientific Aero-
nautics, succeeded in interesting the Prince of Monaco in the scheme,

1 Science, 14, 412 and 800.

* Report Brit. Ass. Adv. Sci., Glasgow, 1901, Transactions Section E.
' Protokoll dcr S. Versamnihing der Internationaleu Komuiission fUr wissen-
schaftliche Luftschiffahrt, Beilage 11.

264 PROCEEDINGS OF THE AMERICAN ACADEMY.

and upon his yacht, the " Princesse- Alice," during the summer of 1904,
kite-flights were made in the region bounded by Spain, the Azores, and
the Canaries. Although a height exceeding that of the Peak of Tene-
riffe was attained several times, the southwest current, which had been
reported on this mountain, was not found. Thereupon Professor Her-
gersell stated that he believed this current was due to the disturbing
influence of the island, and that in the region explored the inter-
change of air takes place through the northwest current, which he had
observed.*

These conclusions, which involved a fundamental principle of meteo-
rology, namely, the existence of the upper return-trades, seemed to
demand further investigation, and accordingly M. Teisserenc de Bort
and the writer undertook to execute this through their assistants,
Messrs. Maurice of Trappes Observatory and Clayton of Blue Hill
Observatory. Mr. Clayton made the voyage from Boston to Gibraltar,
via the Azores, in June, 1905, on the White Star steamer " Romanic,"
and flew kites six times to an average height of about 1000 meters.
The steam-yacht "Otaria," of 350 tons, purchased and equipped by
M. Teisserenc de Bort for exploring the atmosphere, and having on
board Messrs. Maurice and Clayton as the scientific staff, went during
the months of July and August, 1905, at the mutual expense of her
owner and the writer, from the Mediterranean, via Madeira, the
Canary and Cape Verde islands, to latitude 10° north, longitude 30°
west, returning via the Azores and Corunna (Spain) to Havre. Seven-
teen kite-flights were made over the ocean besides two in the harbor
of Santa Cruz (Teneriff'e) to study the sea-breeze, and another off
Corunna (Spain) during the total solar eclipse of August 30, 1905.
In this way continuous records of barometric pressure, air-temperature,
relative humidity, and wind-velocity were obtained from sea-level up to
the extreme height of 2200 meters, although wind-velocity was re-
corded to an altitude of 3100 meters. The direction of the wind
was obtained by measuring the azimuth of the kites. Direct observa-
tions were made by Mr. Clayton upon the Peak of Teyde (Teneriffe)
to a height of 3700 meters, and upon the Peak of Fogo (Cape Verdes)
to 2200 meters, and observations of clouds enabled the wind to be
ascertained about 500 meters higher. To attain a greater height in
the free air than w^as possible with kites, the " Otaria " was provided
with large paper balloons, eleven of which, filled with hydrogen gas,
were liberated from the islands of St. Michaels (Azores), Madeira,

* Conference de la Commission Internationale pour 1' Aerostation Scicntifique,
St. Tctersbour}?, 1901, Supplement 7.

ROTCII. — THE ATMOSPHERE IN THE TROPICS. 2G5

Teneriffe (Canaries), and St. Vincent (Cape Verdes). Since these bal-
loons were only intended to show the atmospheric drift, they did not
carry self-recording instruments, and their direction and velocity at
increasing heights were determined from angular measurements at the
ends of a base-line laid off on the lee shore of the islands mentioned.
One balloon, carrying a self-recording barometer and thermometer, was
launched from the yacht off' the island of Palma (Canaries), but,
though its drift was observed, the balloon could not be recovered. It
was found possible sometimes to follow the balloons in the telescope
until they reached a height of 11,000 or 12,000 meters.

The observations obtained with the kites at 500 and 1000 meters,
and the simultaneous observations at sea-level, are given in Table I,
which is divided into two parts, the first containing the observations
made in an east-southeast direction across the Atlantic, and the second
part those made in a southerly direction within the northeast trade
and on its borders. West of the Azores, on the westerly slope of the
permanent area of high barometric pressure, the observations between
longitudes 69° and 39° show a slow decrease of temperature with in-
crease of height, amounting to 4.5° per 1000 meters. In the lower
500 meters the decrease is only 0.24° per 100 meters, owing to inver-
sions of temperature within the first few hundred meters in half the
flights. In the next 500 meters there is the more rapid decrease of
0.66° per 100 meters. Upon the easterly and southeasterly slopes
of the high pressure, between longitudes 25° and 19°, latitudes 38° and
33° north, the temperature falls at the adiabatic rate of one degree
per 100 meters in the lower 500 meters, and then declines more slowly,
namely, 0.20° per 100 meters, up to 1000 meters. The adiabatic rate
appears to prevail over the ocean at night as well as in the day-
time, and the bases of the cumulus clouds generally are not higher
than 500 meters. The relative humidity decreases with height on
the west of the high pressure, and increases to above 500 meters on
the southeast side. In the former region southwest winds prevail,
and in the latter locality northeast winds, the southwest winds turn-
ing to the left when facing them up to 500 meters, with increasing ve-
locity up to 1000 meters, and the northeast winds turning to the
right and increasing slightly in velocity up to 500 meters, but diminish-
ing above that level. The mean directions and velocities in this table
are resultants derived geometrically. In the column for wind-direction,
a plus sign before the figures representing the diff'erences per hundred
meters indicates a turning towards the right hand, and a minus sign a
turning towards the left.

The observations on the northern edge of the northeast trade, that is,

266

PROCEEDINGS OF THE AMERICAN ACADEMY.

pq

o

eo

eo

ts

s

c

o

^

»*

^

c

K)

„

"«

u

3

8

<U

^

u

<^

(o

•<

^

H

fe

<;

n

'-I

H

-^

s:

H

c

^

o

PQ

to

•«!

toj

c

t^

o

O

1-;;

H

a

H^

Q

SJ

»

S

O

o

<2

h)

£

-«!

3

O

s

o

H

o

C3

l-l
o

:^

M

^

O

H

g

s

>c<

o

CQ

^

^

(C

-r

o

o 5

.

o

t~

o

CO

1^ lO o »— •

•

•

O'i

1— i

UO

OJ

+ •

•

d d 1-: i'

O HI

en

,

o

CO

uO

CO

2; CO

o

O CO CO 1-H

<D ;-■

O 4^

oi

CO

I>^

+ S

*

o 00 CO 4-

to

p

iq

lO

o

. o

o o 00 .

o »

,

sO

CO

lb

o

. d

,

00 t- t-^ .

<u

f— (

a

CO

t^

^

^

^

^

W ^ W

V

s

o

•

c-l

o

CO

<M *

'

O 00 CO rH

•

CO

CN

(N

+ •

•

o '^' +

a
o

o

1—1

cc

Oj

CO

^^^

•1^

^

^

^

^

K W W

S-

o

(N

CO

o

CD Tf

*

lO sq CO s^

a

lO

(N

o

(N

1 =^

•

■<*< <N +

r3

a

i

cc

CO

t»

CO

^

^^•^

03
ID

^

^

^

^

^

PJ K a

o

o

■<*l

Ci

(5

CO

CO 00 (M

CO

o

1—1

O) -N l-H •

o

•z

cc

</2

CO

^2;

I? ^ 12;

CO

p

O «

t^

.

(M

CO

T-H

l-H

o

O - o '^.

4^

CO

'

o

l~

t~

1 ■

o

S • « 1

'■3

a

1

3

£

o

CD

n

8^

CO

CO

00

•*

o

(M' CO

CO

00 • CO CO

>

t^

l^

GO

00

t^

1 *

t^

00 . 00 _j.

^

1

a;

o

V-O

50

o

C5

• t~

CO

l-H • 1.0 •

CO

CO

o;

Oi

00

. lO

o

t- . o .

a

o ^

iO

■<i<

"*.

■*

00

CO CO f-1 oq

^

s«

l--^

,

CO

CO

1-H

f .

ci

CO co' CO i"

O

a

I— 1

I-H

r-(

1

l-H rH rH 1

2

T»(

Ol

3

M

CO

CO

o

t-;

<M O

>o

t- o eo o

?

5^

lO

o

o

■^'

r '^'

■m'

CO d TP r-<

fr4

S

T— 1

r-(

1-H

t-l

I-H

1 r-l

T— <

l-H I-H l-H 1

a

00

H

P

»-H

00

00

Ci

. -^

lO

o 00 Tti

oS

r— <

t-^

>a

as

o

. CO

t^

CO d oJ

a

1—1

T— t

?— 1

»— t

r— 1

I-H

l-H

3<l IM I-H

Cl

■«»<

t—

Oi

(N

• lO

CI

CO CO Si •

o

lO

■^

CO

lO

. !M

I-H

ffl

iJ

o

tS

s

-4J .

<N

1— 1

r— 1

o

I— »

• 00

CO

CO CO lO •

■<*<

■*

'^

■»*<

■*

. CO

CO

CO CO CO .

i

CO

»o

«o

t~-

c

B^

o

CO ■<«< C "

^H

c3

f—t

a O

1

0)

c

O (1)

— H N. ^

o

3
1-5

< ^

^ ■ <•

ROTCII. — THE ATMOSPHERE IN THE TROPICS.

207

o

93

O

"-^

o

s
c
o

"^

s

e

^

•S
-5

©<

"~"

""

o

^^^

^^^

^^^

^^^

"""^

"^^^

^^^

o

,

lO

o

iO

t^

la

lO

o

,

*

o

,

lO

,

lO

lO

ci;

l>J

o

.

.

•

CO

o

<a>

o

o

+

U3

•

o

o

■

CJ

•

o

rH

•

Ci

I-H

lO

+

o

'

•

^

o

o

.—1

00

o

o

o

o

O

ox

o

cc

■

1-

•

o

"

t^

O

CO

o

*

"

•

I-

i~

CO

CO

o

t~

T— 1

Oi

I-H

00

CO

1—1

CO

■<11

o

o

o

o

o

o

o

o

o

o

o

o

o

o

5^

o

t-

00

[-

CO

00

t^

c?

1—*

T-H

I-H

CO

*

00

CO

*

00

t~

•<li

*

CO

■

'

■

W
o

00

o

1—4

S =

03 eS

o

rr,

H
•^

CO

!z;

•

>o

CO

CO

o

o

+

04

•

•

CO

•

lO

•

■*

+

CO

•

•

^;

a

12;

2; ^

^

^

;2;

^

CO

fA

H

w

K

a

H-4

^

H

w

m

^

o

CO

T»<

CO

uO

on

o

C5

■^

w

•

•

kO

•

t.

u

(N

o

•

>0

o

lO

vO

(N

■<*

^

00

>^

•

CO

•

■<ii

*

>

>

CO

CO

t?; 12; ^ ^

Z,

«

;zi

2;

;z;

^

iz;

CC

w

K

H

a

w

a

w

W

w

^

CO

CD

•^

r^

on

o

•

CO

t^

til

•

CO

■

o

•

W !=^

o

^

o

'

"

o

o

CO

CO

CO

lO

•

CO

Oi

•

Oi

•

o

•

' '

CO

•

CO

•

■

;z; !2; a z ;z; ^

^ ^

^

^

^

CC

■"ll

l^

•«*<

"

o

CO

fN

o

in

1

00

t-H

iC

r—

OJ

OI

00

•

CO

en

C<1

1

CO

o

CO

1

OS

Oi

OS

0-5

I-H

■^

00

o

U5

■<*'

I-H

CO

TT

o>

o

1-H

(Si

tK

(M

o

0?

(M

Tt<

■ti

•»t<

17^

o

O:

00

CO

r^

CO'

CO

t^

O

CO

o

r^

1

'O

^

IT)

S^l

Ci

S^w

C5

05

Ci

Ci

+

o

T— 1

(>4

o

CO

CO

c«

t-

00

a

00

o

t^

1

1— t

+

Tf

o

C5

■<1<

CO

?M

.

o

r^

C^l

OI

■*

CO

o

'^^

o

rr>

^

lYl

ro

r1

rr,

00

OO

t-

ou

00

00

•

ou

CO

t^

00

00

t^

00

CO

03

CO

CO

t^

•

00

Cl

00

•

OS

t^

U5

00

t^

CO

t^

o

r~*

CI

o

CO

C^

'N

>o

Ol

CD

t^

O

C?

CO

,

lO

->*

CO

lO

uo

1

CO

,

CO

1— H

00

05

OI

1-H

00

<r>

CO

+

m

no

Tl

1

1— t

1— t

1-H

1— 1

t— 1

Oi

(><

04

'N

■""

(M

•>4

04

CM

Ol

1-H

I-H

1—1

^_

I— 1

o

CO

CO

00

00

CO

00

t^

o

CO

Tt<

lO

1-H

!>■

00

T*1

00

t-

lO

00

00

Oa

Ci

00

00

00

1

CO

lO

Ci

<>)

o

00

OS

CI

00

,-H

'N

c->

1

1-H

<— 1

^

1

»— <

1— t

1— t

1— I

T— (

1— t

1— 1

s^

1—1

(N

(N

1— t

I-H

1-H

I-H

<N

04

04

(N

l>)

(N

1

<>1

00

CO

t~

<M

lO

t^

U3

<M

CO

CO

o

t^

CO

-*

t^

Ol

CO

O

o

O

rr\

CO

CO

CO

CO

CO

,

1-H

CO

CO

CO

o

c^

"N

-"f

•"n

i-O

lO

CO

CO

•^

lO

<M

!N

(N

Oi

(>i

"M

c^

Oi

s^

s^

c^

(M

1^4

!M

CN

C^

(M

0^

(M

!M

<N

•*

^

CI

t^

Ci

o

,

t^

Oi

t^

r^

(^

O

CO

CO

CO

f<

Ttt

"N

.

CO

<->

m

•M

>>\

t— 4

t— t

t— (

c^

*

1— t

1— 1

tH

r^

1— (

CN

Oi

!>J

<>(

(N

(M

<N

•

C^

CO

CN

•

f-«

J^

Cl

»i

CO

lO

o

■^

•^

vO

•

f— (

00

00

on

t^

rt<

CT>

o

CO

lO

lO

0^1

•

I-H

<— 1

r-i

.

CO

CO

CO

CO

CO

CO

■

CO

<>4

(N

iM

<M

Oi

I-H

I-H

I-H

l^H

I-H

<M

'

r—f

1-H

I-H

"

o

p.;

<5

a;

on

<:

c

g

■*

00

Oi

o

{?^

rji

lO

Ph'

o

<

r^

00

c

^H

■^

^1

c

a

>>*

rH

-

»— <

"

a

i->

I— 1

1-1

?-i

T— 1

(N

*•

GN

(N

o:

t~>

0^

'N

a

^

-

3

s

:

s

o

<

M

<

=

=

3
<

S

=

;

;

o

<

Zj

S

1—1

<

o
to

o

(I4

a
Pi

a

03

Ph

268 PROCEEDINGS OF THE AMERICAN ACADEMY.

between latitudes 36° and 34° north, show a rapid fall of temperature
with height (7.8° per 1000 meters) which is fastest (0.92° per 100
meters) within the first 500 meters. The relative humidity rises
nearly to saturation within the first 500 metres, but does not attain
this point, the flat cumulus clouds found in the region being probably
formed by the condensation of water-vapor rising from the ocean
through a slow motion of diffusion. The wind, which is generally
northeast, changes its direction but little with altitude, although it
increases in velocity above 500 meters. The same features are shown
by the only two observations south of the northeast trade, in about lat-
itude 10° north. "Within the trade-wind region, between latitudes 31°
and 15°, the vertical distribution of temperature and moisture is quite
different. Near its origin the trade has the character of a descending
current, that is, small vapor contents and little cloud, which is the flat
cumulus tjrpical in northern regions of high pressure and descending
air. In approaching the equator, that is, south of latitude 24° north,
the trade presents characteristics of an ascending current, the relative
humidity increases much with height, the sky is cloudy, and there are
frequent rains, often accompanied by thunder-storms. The decrease
of temperature within the trade region is less than 1°C. in 1000 meters,
there being a fall of 0.58° in the first 500 meters and a rise of 0.56°
in the next 500, on account of the inverted temperature-gradients
which occur near 1000 meters at the upper limit of the trade-wind.
Its depth varies from day to day between 300 and 1500 meters, and ap-
pears to be greatest in the afternoon and least at night. The upper por-
tion is damp, with cumulus and strato-cumulus cloud, above which the
wind falls light and the relative humidity sinks nearly to zero, coincid-
ing with the rise in temperature, which frequently carries it much
above that at sea-level. With increasing altitude there is a gradual
shifting of the wind, when facing it, to the right, accompanied by an
accelerated velocity, up to at least 1000 meters. The conditions at
greater heights were deduced by Mr. Clayton as follows : Above the
surface-trade is a current some 2000 meters in depth, varying in
direction between northeast and northwest, but coming always from
a direction to the left of the lower wind when facing it. This current
is extremely dry and potentially warm, and its velocity usually much
exceeds that of the lower wind. The third stratum, which begins at
a height of about 3000 meters, moves fi'om east, south or southwest,
being generally from the east in equatorial regions, and from the
south between latitudes 15° and 30° north (see Table II). As observed
on the Peak of Tenerifife this stratum was dry in its lower portion, but
with a larger vapor contents than the air immediately below. Alto-

ROTCII. — THE ATMOSPHERE IN THE TROPICS.

269

TABLE II.

Winds ahove the TR.vnE-wiNn Reciov of the Atlavtic, between Lat. 37°
AM) 10° N, Long. 15° and 20° W of Greenwich.

1905.
Aug. 22

July

(1

17
9

Teneriffe

(Canaries)

((

10

«

Aug.

10

It

<(

11

((

«

9-10

Peak of Teyde
(Teneriffe)

Aug. 13

July 17

" 18
" 29

" 27-28

" 25
" 24

St. Michaels

(Azores)

Madeira

At sea off Pal-
ma (Canaries)

St. Vincent
(Cape Verdes)

Peak of Fogo
(Cape Verdes)

Lat. 13° N,
Long. 24° W

Lat. 11° N,
Long. 20° W

XE to 800 meters; NW to at least 4200 meters.

WNW to 1800 m. ; NW and SW to 11,500 m. ; SW

at 11,600 m.
NE to 2900 m. ; NW and NE to 4200 m. ; WSW to

at least 12,500 m.

NE trade to 400 ni. ; NW to 3500 m. ; AVSW to at

least 7500 m.
NE trade (variable) to 2000 m. ; NNW to 4000 m. ;

SSE and SW to at least 5700 m.
NE trade to 3300 m. ; SW and NW to 5200 in. ;

S and SE to at least 11,000 m.
NE trade to 3200 meters; SE and S to 5300 m.;

SSW to at least 5900 m.
NE trade to 2300 ra. ; S and SSW to at least 3900 m.

E, 1 m. per sec, to 1000 m.; N, 4 m. per sec, at
2000 m. ; N, 7 m. per sec, at 2500 m. ; E, 3 m.
per sec, at 3000 m. ; S, 4 m. per sec, at 3500 m. ;
Sat 4000 m. (?)

NE trade to 2G00 m. ; NW to 3400 in.; WSW at
3400-1200 m.; SW to at least G500 m.

NE trade (variable) to 4100 ra.; variable to 5100
m. ; SE and SSE to at least 11,000 m.

NE trade to 1.300 m.; ESE to at least 2360 m.

NE trade to 050 m.; NW (variable) to 1900 m. ;
SW and SSW to 7500 m. ; ESE and NE to
11,700 m. ; S to at least 13,600 in.

E, 7-3 m. per sec, to 500 m. ; NE, 6 ra. per sec, at

1000 m.; N, 6 m. per sec, at 1500 ra. ; N, 5 m.

per sec, at 2000 m. ; ENE at 2500 m. ; E at

3500 ra. (■?)
NE, 4-3 in. per sec, to 1000 m. ; E, 16 ra. per sec,

to 2500 m.
N, 3-5 ra. per sec, to 1000 m. ; E at 3000 m. (?) by

ACu clouds ; ESE at 11,000 m. (? ) by CiS clouds.

270 PROCEEDINGS OF THE AMERICAN ACADEMY.

cumulus and alto-stratus clouds were seen floating in it at a height of
perhaps 4000 or 5000 meters, and from them light sprinkles of rain fell
occasionally. On the Peak of Teneriffe, in passing into this upper
current, a rise of temperature was noted, which was less than that
encountered above the surface-trade.

The winds at great heights in and near the trade-wind region are
given in Table II. They were obtained by pilot-balloons launched
from the islands, excepting the one from the yacht, and the last
figures for each ascension show the maximum height at which the bal-
loon was sighted. The means of direct observations of wind-direction
and velocity at definite heights, obtained during the ascents and de-
scents of the peaks on the tropical islands of Teneriffe and Fogo,
and the drift of clouds passing at estimated heights above these
mountains, are given. Observations of the direction and velocity of
the wind, obtained in two kite-flights south of the trade-wind region,
complete the table. In that portion of the Atlantic investigated by the
Franco- American Expedition, the atmospheric circulation was found
to be as follows: (1) North of Madeira, and near the Azores, the
upper winds, as was already known by observations of clouds, are chiefly
from west and northwest, this region being generally to the north of
the barometric maximum over the ocean and beyond the zone of the
trades. (2) The winds blowing towards the equator are from north-
east to east in the lower region, and generally from northwest to
northeast above 1000 meters. (3) The return currents from the
equator, or anti-trades, are formed by winds having a southerly com-
ponent, being generally southwest in the latitude of the Canaries, and
southeast near the Cape Verdes, thus showing the influence of the
earth's rotation. The law of the vertical succession of winds, as for-
mulated by Abercromby, ^ namely, a shifting in the northern hemi-
sphere of the upper winds to the left-hand, when one's back is
towards the wind, is found not to hold true always, the right or
left-handed rotation depending upon the origin of the wind, and,
presumably, upon the distribution of the pressure at high levels.

The vertical distribution of temperature and relative humidity re-
vealed by these observations up to a height of 4000 meters is nearly
the same as that found by Professor Hergesell during the cruises of
the " Princesse- Alice," in 1904 and 1905.^ Most of his observations

" Nature, 36, 85.

• Comptes Rendus de I'Academie dcs Sciences, 30 Janvier, 1005; INIeteoro-
logische Zeitschrift, November, 1905 ; Bulletin du Musee Oce'anograpiiique de
Monaco, 30 novembre, 1905.

ROTCn. — THE ATMOSPHERE IN THE TROPICS.

271

of direction of the upper currents differ radically, however, in show-
ing no southerly component, although one balloon, launched west of
the Canaries, gave the same direction as that obtained near these
islands, meeting interlaced currents from the southeast and south-
west, above the northeast trade. From the distribution of pressure
on the earth's surface it would be supposed that the upper anti-
trade ought to be especially regular in the region between Cape
Verde and the Canaries ; but this idea is contrary to the belief of
Professor Hergesell that the upper southeast and southwest winds
observed near these islands, and long considered to furnish a demon-
stration of the return-trade, are due to local disturbing causes. To
settle this question, Messrs. Teisserenc de Bort and the author again
sent the "Otaria," during the wnnter of 1906, to the south and west of
the region which had been explored by them the preceding summer.
Since this paper was presented to the Academy, Messrs. Maurice and
Nilsson, constituting the scientific staff of the " Otaria," have com-
municated the results of their atmospheric soundings, made from the
vessel to the westward of the Canaries, and these results appear in
Table III. The longitudes are from Greenwich.

TABLE III.

Winds observed in February, 1900, above the Atlantic, Southwest of

THE Canaries.

Feb. 13

" 14

" 15

16

Lat. 28° N, Long. 18° W. ENE to 2850 ni., NW to 3680 m., SW to
the culminating point of the balloon, 5300 m.

Lat. 27° N, Long. 18° W. ENE to 1800 m., SSE to 2100 m., N to
2250 m., SW to 2500 m., NW stratum 500 m. thick, then SW to
5100 m.

Lat. 26° N, Long. 19° W. NE changing to N up to 1350 m., NW
to 2600 m., WSW and SW to 5100 m.

Lat. 26° N, Long. 19° W. NE to 1300 m., NW and W to 3150 m.,

strong SW to 3300 m.
Cirrus clouds (4 observations) from S 50° W.

Lat. 25° N, Long. 20° W. NE to 2-300 m., NW to .3000 m., SW to
3250 m., WNW changing to W up to 3950 m., SW to 4150 m.

Alto-cumulus clouds from NE, cirrus (2 observations) from S
30° W.

Cirrus clouds from S 45° W.

272 PROCEEDINGS OF THE AMERICAN ACADEMY.

It is seen that the upper anti-trade is shown both by the bal-
loons and by the drift of the clouds, the stratified conditions giving
place to the southerly wind between 3000 and 4000 meters. There-
fore the classic observations of the return -trade, which were long
ago made on the Peak of Teneriffe, indicate a general phenomenon,
and agree with those obtained over the open ocean by the present
expedition.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 15. — December, 1906.

AN APPROXIMATE LAW OF FATIGUE IN THE
SPEEDS OF RACING ANIMALS.

By a. E. Kexxelly.

AN APPROXIMATE LAW OF FATIGUE IN THE SPEEDS

OF RACING ANIMALS.

By a. E. Kexnelly.

Received July G, 1906.

Races between swift men, or between swift horses, have been of the
greatest interest in all times. Olympia and Epsom Downs are known
to fame by the races they have witnessed. Olympian races, recently
revived, are of international interest.

It is strange that, judging from encyclopedias and text-books on
athletics, there is very little published information concerning the
speeds at which races are run. Apparently, all that is known by
our books on these matters is that short races are run at higher speeds
than long races. Every one knows that a contestant in a mile or kilo-
meter race runs at a lower speed than a sprinter in a lOU-yard or
100- meter dash.

There has, however, been accumulated during the last century, and
particularly during the last fifty years, a considerable fund of publicly
recorded information concerning the record times in which races of
stated length have been run. Athletes are, for example, generally
familiar with the records of the 100-yard and the mile runs ; namely,
9.6 and 252.75 seconds, respectively. A reduction of either of these
record times by even one per cent would be a matter of world-wide
importance and the hero of the new record would be famous among
the inhabitants of the temperate zones.

This paper presents the data which the writer has been able to
collect upon record speeds in various kinds of racing, as well as the
conclusions that seem to be warranted thereby. It will be seen that
the records align themselves closely to a simple mathematical relation.
It is not pretended that the records conform rigorously to this mathe-
matical relation. Such a condition could hardly be expected from the
performances of different animals at different times and in different
parts of the world. It is claimed, however, that any one who will
analyze the records presented will be able to satisfy himself that they
approximate to the said mathematical relation for practical purposes
within satisfactorily small limits of deviation.

We may commence with horse-racing records.

276 PROCEEDINGS OF THE AMERICAN ACADEMY.

Horses Trotting.

Table I, the data of which are taken from page 259 of " The World
Almanac and Encyclopedia" for 1906, gives in column I the date of
the record, in column II the distance run, or length of the course, and
in column III the best record time. For these data " The World
Almanac " is made responsible. These data have been checked, how-
ever, by those given in the same publication for preceding years. No
event has been rejected. The best records for 1, 2, 3, 4, 5, 10, 20,
30, 50, and 100 miles of trotting are taken. They are stated to be
World's records, and at least one, — the 4-mile event — is stated to
have been made in England.

Commencing with the above data, column IV shows the distances
expressed in meters. The meter and kilometer are so much simpler to
deal with numerically than the foot, yard, furlong, and mile, that it is
worth while to reduce all distances to meters. Column V gives the
average speed at which the record was made, expressed in meters per
second. Thus, taking the first event, the mile (1609.3 meters) was
trotted in 118.5 seconds. This represents an average speed of 1609.3
~- 118.5 = 13.58 meters per second (30.4 miles per hour; or 44.5 feet
per second).

Turning now to Figure 1, the abscissas are laid off both in miles and
in kilometers, as far as 20 miles (32.2 kilometers). The ordinates rep-
resent speeds both in meters per second and in miles per hour. An-
other scale of ordinates gives the record time of each run in seconds.
It is seen that the speeds, taken from column V, drop from 13.58
meters per second (30.4 miles per hour) at 1 mile (1609 meters) to 9.18
meters per second (20.6 miles per hour) at 20 miles. The average
speed of the trotting horse that made the 20-mile record was there-
fore 67.6 per cent, or about two-thirds of that of the trotting horse
which made the 1-mile record.

Taking next the time ordinates, the rising line in Figure 1 closely
follows the first six successively increasing times. It is evident that
both the speed-distance line and the time-distance line are curves,
when thus plotted. The curvature of these curves is greatest near the
start, or over the short courses, and diminishes as the course increases.

If, however, the speed and the time with respect to distance be
plotted on logarithm paper, as in Figure 2, instead of on ordinary
cross-section paper, as in Figure 1, the points fall approximately upon
straight lines.

The above fact is the gist of this paper. That is to say, if we con-
sider the three quantities L, T, and V, or length of course, record

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

277

<
Eh

SE

a.

25 "

O

c

H

o

H ^

c
.J

o
fe:

«^|

00

HH

g 1 'f>i

(- s^ ^

£ 1

^

o

p

p

K

00

■^

p

Ci

00

^]

00

d

-t>

^'

f-H

d

f-H

CO

CO

^

p

i^

f-H

-^

o

o

o

o

»o

o

.1^

f-H

CO

•^"

OJ

d

d

00

\6

r»i

d

-^ 1

1

(M

(N

f-H

(M

Oi

Ci

o

h^

a 1

1

1

1

1

<Ji

CO

Oi

X

1

1

1

1

1

d~

f-H

1

■d

i-O

t^

-tl

CD

00

p

o

p

o

o

S

aJ

d

^H

00

d

■^

t^

f*

co'

d

.

l> s.

o

f-H

o

CO

o;

r^

CO

-*

vO

X

1-H

!^^

■^

o

t--

o

Tfl

■>*

t^_

<M

a

f-H

CO

vO

oT

,-h'

o

!N

-3

•^

(M

CO

00

00

■^

Tt<

CO

00

1^

.

E^'-S

t^

O

Ttl

■Tfl

CO

o\

f-H

C5

GO

t^

►—1

o

I—

I— t

r-H

lO

CD

o

•rjl

CO

00

(M

o

■*

CD

1^

00

(M

o

t^

Ci

CO

oi

oi

(N

ir4

c^

CO

CO

CO

CO

Tji

Ol

00

(N

o

t-H

CO

o

CO

OJ

T»<

•

■*

cq

t^

u?

cq

o

o

CO

(M

o

OS

^^

CO

Ci

«D

CO

CO

o

o

I^

lO

Ci

>

1

f-H

p

P

p

p

p

C5

00

t~

CO

1— (

f-H

f-H

f-H

f-H

f-H

d

d

d

d

E-;

t^

o

o

t^

uO

CO

t~

o

-If

'>l

CO

o

00

CD

uO

t—

-*

o

t~-

^^

,

t^

o

t^

r~

05

•*

f-H

Iffl

o

>

o

o

f

s

r~

00

f-H

o

00

o

:^i

'jj

(M'

im'

c<i

CO

CO

co'

■*■

r)i

•^

o

t—

00

t~

CO

CD

t^

00

CD

o

o

t-

CO

00

o

CO

r~

CO

lO

CD

t-ii

o

o

o

00

o

o

o

o

00

o

o

>

c^

i-O

CD

CO

o

'^^

o

p

o

(M

CO

CO

CO

CO

CO

■*

'^

■*

T}i

id

-« 2'^

oo

■M

■M

r^

!M

T)

30

o

Ci

£.'2 a

o

lO

P

t^

1^

(M

Tjl

CO

o

>

CO

ci

f-H

d

d

d

d

I-^

id

id

f-H

f-H

f-H

f-H

•-H

1 00

CO

1^

o

rp

t--

p

p

o

o

o

ri

00

00

r-^

CD

f*

t-^

d

t-^

d

« fc-

o

f-H

(N

CO

Ttl

c:5

CO

00

CO

CO

>

l^'l

o_

c^

00

Tf

o

o

c^

•^

Ci

*^

M ©

^4

CO

Tji"

co"

oo"

rT

(M"

co"

d~

d'

(5 3

1— I

CO

■*

00

CD

f-H

e"3

U3

p

O

o

o
t^

p

o

o

o

o

CO

t-^

O

00

d

1-T

i-O

d

d

c?

hH

f-H

iC

f-H

OS

>o

t^

o

t—

"SH

o

f— i

l>J

•>*1

lO

t^

uO

o

rr

•-H_

^-1

co"

co"

T»<"

cf

CO

f-H

CO

oT

bS

l-H

»

CO

•^

iO

o

o

o

o

o

NM

s^

!N

CO

o

o

.2 a

f-H

q5

uO

(M

CO

o>

CO

CO

Iffl

t^

CO

CO

O

o

c^s

03

05

o

CO

>o

1^

lO

HH

a>

Ci

00

f-H

00

00

t-H

00

f-H

00

f-H

00

f"H

00

f-H

00

f-H

278

PROCEEDINGS OF THE AMERICAN ACADEMY.

Figure 1. World's Trotting Records.

Time, ,a j^.
Seconds § g

t_»

l_i

^_l

>— I

t J

to

en

to

A'

o

o

o

o

o

o

o

o

o

-Average speed over each course (meters per second).

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE. 279

time, and average speed of the run, in a series of events, any one, say
T, plotted against either of the others, say L, the observations are
found to fall approximately upon a straight line, with logarithm paper.
In other words, the curves i)lotted on plain rectangular paper from the
same records are approximately simple exponential curves, of the type

y = ^■"•

Instead of plotting the quantities in the ordinary way upon logarithm
paper to produce straight lines, we may perform the equivalent opera-
tion of plotting the logarithms of the quantities upon ordinary scaled
paper, and produce similar straight lines. That is, we may plot any
one of the quantities log L, log 7", and log V against either of the other
two. For some purposes the latter method is to be preferred, although
it takes more time. Its application is presented in Figure 3, where
log T and log V are both plotted as ordinates against log L as
abscissas for all of the data of Table I. Columns VI, VII, and VIII
in the table contain the common logarithms of the entries in columns
IV, III, and V respectively. It is seen in Figure 3 that the speeds fall
closely upon the descending straight line, as far as the 20-mile dis-
tance, as already seen in Figure 2. Beyond the 20-mile distance, the
speeds fall off markedly and are much too low to meet the line.
Table I indicates, however, that these long-distance records of 30,
50, and 100 miles respectively, were made about 50 years ago, whereas
the short-distance records are of recent date. At the dates indicated
(1846, 1853, 1857) the short-distance trotting records were by no
means so good as they are to-day. It is reasonable to assume that
if these deviating long distances were attempted to-day, their records
would be materially improved. ^

^ Since this paper was written, the writer has been indebted to Prof. E. L.
Mark for a photographic curve-sheet pertainino; to a paper presented by Prof.
Francis E. >«"ipher to tlie St. Louis meeting in 1903 of the American Association
for the Advancement of Science. The curve-sheet shows the steady reduction
in the record times of the trotting-horse mile and also of the running-Iiorse mile
at diiferent dates between 1840 and 1903. The curves indicate a final limit to the
trotting mile at 98 seconds and a final limit to the running mile at 91.5 seconds.
The equations to the curves do not appear on the sheet, but have been computed
by the writer, from the curves, as follows : —

At any epoch y years after 1840, the trotting-horse mile record appro.xi-
mates to

Ty = 98 (1 + 0.56 X 10-o"0526y) seconds (a)

and for the running-horse mile record:

T, = 91.5 (1 + 0.154 X 10-0009932) seconds (b)

where z is the epoch in years after a.d. 1863.

280 PROCEEDINGS OF THE AMERICAN ACADEMY.

The ascending line in Figure 3, connecting log T and log L, repre-
sents the sequence of record times with satisfactory precision, as far as
20 miles, with the exception, perhaps, of the 4-mile event, in which
the time is long and the speed low. As shown in Figure 1 or Table
I, the speed in the 4-mile trot is only half of one per cent greater
than the speed in the 5-mile trot. It should be relatively faster by
more than this amount, to judge by the speeds in the other events, and
this means that it should lie nearer the straight line of time-distance
in Figure 3.

Beyond 20 miles, the points deviate markedly from the rising
straight line of Figure 3 in the direction of excessive time, or low
speed, as already considered.

The rising straight line of Figure 3 represents the equation

log r=|logZ- 1.53 (1)

■while the falling straight line of speed-distance corresponds to

log F= 1.53- i log Z. (2>

That is, the rising line makes with the axis of abscissas an angle of
48° 22', whose tangent is % ; while the falling line makes with the same
axis an angle of —7° 7' 30", whose tangent is —I.

Equation (2) implies that at Z = 1, or upon a course one meter
long, the speed of trotting would be 33.9 meters per second, the loga-
rithm of this number being 1.53. It would be impossible for a horse to
reach any such speed on such a very short course, even with flying
start, if only owing to inertia and the large effort required for initial
acceleration. The initial velocity of equation (2) is therefore a ficti-
tious quantity of merely theoretical interest. The speed curve of
Figure 1 and the straight speed lines of Figures 2 and 3 mark a satis-
factory application of equation (2) between the limits of 1 mile and
20 miles. Columns IX and X of Table I give the computed time for
each event, as determined by equation (1) or the rising lines in Figures
1, 2, and 3. Column XI gives the deviation or discrepancy between the

From formula (a) or from tlie curve-slieet, tlie ratios of reduction in tiie
trotting-horse mile record time to 1905 are,

at 1846 0.82

" 1853 0.844

" 1857 0.858

Usint; these correcting ratios, the .30-milc trotting record is brought on to the
logaritlnnic straight line in Figure ;'> ; while the 50-niile and 100-inile records are
only brought about half-way towards tliat line, as indicateil on the figure.

KEN NELLY. — AN APPROXIMATE LAW OF FATIGUE. 281

computed record time T' seconds and the published record time T
seconds, while column XII expresses this discrepancy in percentage of
the record time T. Thus, the 4-mile event should have been trotted
in 568.6 seconds by the formula, as against the published record of 598
seconds, a discrepancy of 29.4 seconds or 4.9 per cent of the published
record. It is seen that between the limits of 1 mile and 20 miles (1.61
and 32.2 kilometers) the average discrepancy between the recorded
time and the time taken from the equation (1) or the ascending lines
in Figures 2 and 3 is 1.8 per cent. The discrepancy is much greater in
the three longest events and reaches 34 per cent in the lOO-mile trot.
Owing to the age of these three records, however, it is submitted that
they may properly be set aside. At all events, between the limits of
1 mile and 20 miles the straight logarithmic line of times agrees with
the published records to an average of 1.8 per cent. If the suspected
4-mile record were set aside, the average discrepancy without regard to
sign would come down to l.l per cent.

In Figure 4, drawn to uniform scale, the average speeds are continued
to 100 miles of course-length, or beyond the limits of Figure 1. The
curve of speeds corresponds to equation (2) or to

33.9
V = — Y meters per second. (3)

The figure shows the discontinuity which exists between the speeds
over the three longest courses and those over courses up to 20 miles, as
taken from column V, Table I.

Horses Running.

The records for running- horse races appear in columns I and II of
Table II. They are taken from page 258 of " The World Almanac " for
1905, which gives the records for 33 courses between \ mile (402.3
meters) and 4 miles (6437 meters) on American turf, revised to Decem-
ber 1, 1904. Column III gives the distances in meters and column IV
the average speed of each run. The times and the speeds are plotted
against distance to uniform scale in Figure 5 and to logarithmic scale
in Figure 6. In the latter case the entries in columns V, VI, and VII
are used. It is to be noticed that in Figure 5, with uniform ruling,
the observations follow curves, whereas in Figure 6, with logarithmic
ruhng (or logarithms of the quantities on uniform ruling), the obser-
vations fall substantially on straight lines. The two curves drawn
in Figure 5 respectively correspond mathematically to the two straight
lines drawn to meet the observations in Figure 6.

282

PROCEEDINGS OF THE AMERICAN ACADEMY.

X

X

K

X

6

s
o

is

Vi

^

^

o

5^

s

D

a

C5

g

^

■1^

K

Us

O

K

3

fi;

QJ Zi -i

s ^

Oi

CO

43 ^3

d a>
O to

^3

be a.

.2 a

f^ »

t-'«-

CO

•ys

tJ (D

a

0) +^

o

ap

Oi -

to

ocoooO'-joococqiooo

lO O t^ •^ CO

O o »— ' CO »— < CO

C5

--< CO oq o<i

r-ic<iiI^i(>ii-<OOr-<

I I I I I I

o o I- '— ' o

i-H i-H I-- CO CO

I I

00 c: cc

o o o

O"— '~oocoo-^o

O— ■t~CCO:0<No5>0'MQDO
C^COCOtPOOOCOI^OOXiOI

C005.— (-t<o-*'Oi-OI:^CO;oO
fNOCDi— iCiOl-OiOD-^OOO
OOr^'^CiiOOscoi^ — ^foo

CO

r^

rO

CD

1^

-ti

o

t^

lO

ID

o

TO

'^r

o

o

<r>

t^

00

Oi

en

(M

lO Ci t-- lO CD r- o

fN CO I— I <» 00 00 O

O -^ 00 I— 1 -rt> t^ O

O O O 1— < >— < rH CVJ

CO

T*< lO lO CD CD

t^ ^ r^ c<l (M

<» CO O CD 1— 1

CO lO O CD t^

O CI lO CO t^ t^ o

-f lO C^ •^ ■— ' -^ o

lO O CO Ci -M CO 00

t^ i~ 00 00 c: 05 05

CO to 00 C5 rt< 0<1
03 t^ CO ■^ O t--;

00 i-~ t-- t-- t-- t--

»0 CO CO 1^ lO

t-. CD 00 CO CO

t-^ CO w' CD CO

CO

o

r— t

t:^

(N

00

-*

o

CD

1— H

c;

CO

IM

CO

-*

■^

lO

»-tl

• ^

r^

r^

00

3D

o

O

o

O

O

o

o

o

o

o

o

o

■^

CD

l^

00

C5

o

I— <

i-H

CO

1— '

o

r-H

rl

lO >.o

(NO«OOcDI~iOO'*0(NO

a 8

_'

■^

o

CO

._;

CO

(M

00

00

CO

(N

lO

(N

CO

'*<

Tj<

lO

lO

CO

CD

1-

00

Oi

05

H S

lO

o

o

»o

lO

8

iii

o

t^

(M

lO

l-~

<>i

lO

r^

O

I^

CO

CO

(>)

or)

lO

f-H

r^

00

o

I's

<M

OO

Tt<

iC

lO

CO

CO

t—

CO

00

05

o

O

o

o

o

o

o

o

^

o

o

o

T— '

KENNELLY.

AN APPROXIMATE LAW OF FATIGUE.

283

OS

r— •

*—

— >

CJ

o

CD

CO

00

o

<— 1

o

t^

CO

!N

CO

o

Ci

o

00

04

(04

(04

uO

Tjt

CO

!N

3^

■M

T— 1

?<

o

o

(M

r-1

(M

o

o

CO

1—1

lO

o

1— (

lO

00

■^

Ol

i.O

lO

(N

O

<»

■*

O

M

CO

05

^

CD

CO

CO

cs

o

o

CO

o

CO

00

■*

1

(M

1

1

1

(M

1

1—1

o

CO

1

?

o

CO

(M

1

1—1

f— »

30

CO

1

1—1

1

o

1

Tf

CO
(04

(N

«D

00

t^

■ O

Ci

(N

O

CO

crj

t^

t~-

r-

30

CO

t^

-fl

o

00

00

o

T— 1

00

■*

CO

30

CT!

•M

C5

30

Ol

^

CO

o

00

a

00

00

CO

r^

r—

(04

00

00

•^

a

O

O

O
1-H

o

1— (

1— <

1— (

1-^

CO

1-^

CD
1—1

I—

1—1

(^

o

(04

d^

CO
(04

CD
104

30
04

(M

(Ol

CO

o

r^

r>

r^

fD

T— (

r~

CO

i.O

no

CO

(04

OO

CO

CO

<r>

-^

i-O

CO

1-

■^

— ;

CO

i.O

00

1^

CO

r^

-r.

Cf.)

cr>

1—1

-^

CO

t^

00

C:

o

r^^

r-

ci)

1—1

CO

r-

Ol

o

3!)

•^

Ol

'O

t-

o

as

O

c:>

o

P

p

p

1—1

'

1— '

Qi

04

(04

CO

CO

CO

'^

T)1

■^

VO

p

lO

rO

>.o

lO

uO

CO

-f

tn

•^

(TJ

LO

t^

r^

(Yl

CO

CO

(04

<3i

t^

CO

(04

1—1

CO

(M

•M

r— <

'^

o

CD

LO

C5

1—1

O

(04

I—

C/.)

^

O

o

0-J

•*

1—1

1— t

1—1

1—1

r— I

o

O

o

C-.

o

'00

(TS

■00

a

00

1.0)

1—

r^

t^

c^

<>i

°i

(M_

IN

Oi

i>J

(M_

(04

OA

r-H

CN

1—1

•

r~t

^^

1— '

\a

00

o

o

CO

CO

CD

00

o

t~~

lO

t^

CD

r^

o

00

CD

00

o

(X)

I—

1— <

00

o?

CO

l~

CO

■-f

".O

-M

1^

>-T5

ri

i~

-p

3U

~P

UO

o

CO

00

r— <

^i

CO

o

(T)

O

»>)

-p

3!)

1— «

-^

i~

<->

00

lO

o

-M

-r

'.•/)

o

C^_

5^

<>j

C^)

^.

•^

CO

CO

CO

"^.

'^

^.

o

o

iq

p

p

p

p

00

o

iM

1—1

i.O

CO

r^

^

Ci

o

00

o

o

OT

C5

•-1<

(M

•<*

Oi

CO

•o

o

o

o

1—1

o

o

cr.

Ci

oo

00

cn

00

nn

Of)

■^

o

O

Oi

■^

lO

o

Ml

o

1—1

-1<

30

(M

CO

t^

1— '

-r

Oi

f

CO

(01

t-

1—

r^*\

O'

o

O

o

o

o

o

1—1

1— t

1—1

(OJ

(M

(04

CO

CO

CO

-*

■*

■*

lO

CO

(M

00

>»

o

00

00

00

on

r~

CO

1— (

CO

n

l~>

<-5

r— 1

1.0)

(04

o

CO

(M

05

CO

OS

CO

>M

CO

00

o

O

00

C5

CO

Tp

00

04

r-H

00

(J5

(J3

O

U5
1—1

o

r-l

CO
1— <

CD
1—1

CO

T— 1

o

o

CD
1— t

1— t

1— t

o

1— 1

1—1

1-<

1—1

T— t

-*

1— t

o

o

CO

C5

uO

1—1

t—

CO

Ci

O

(M

CO

uO

CO

00

o

CO

UO

t^

o

o

t-

o

CO

05

o

r^

1—1

CI

fM

-*

o

CD

t^

00

(3i

^~,

CO

•^

o

lit)

r^

(M

lo

r—

o

1-^

1—1

1-H

1—1

1— H

1-^

1-^

1— t

f~M

1-^

(04

04

04

Ol

04

CO

O

o

O

I^

CH)

c;

o

1— «

Ol

-f

CO

00

o

04

■^

o

Ol

-tl

00

-^

T— '

1— t

1—1

r~*

^

(M

(04

(N

(04

■O)

CO

CO

OO

CO

-*

Til

•"Si

T!"

CO

UO

lO

c

-N

tD

tc

o

■^

00

o

o

04

Ol

o

o

lO

o

(N

lO

lO

t~

o

o

c

—

•M

"-^

^M

t^

OM

CO

r^

O

>o

r—

Ci

CO

(04

o

-*

00

00

Tt>

1—1

o

o

O
I— 1

o

1— t

1—1

C^l

CO

1—1

CO

T— (

i.O
1— t

CD

1—

1—1

1—1

o

04

CN
(M

OI
(04

CD
(M

S5
(04

35
(04

(04

CO

CO

•^

o

vO

lO

1—

00

o

'Ol

•o

fN

o

lO

LO

o

uO

>o

1—1

c^

•rti

CD

CM

Of)

o

t—

(M

o

i^

o

C4

lO

(04

in

o

o

p
1-i

o

o

O

s^

CO

CO

T— 1

o

CO

t^

00

o

(04

1—1
04

(04

i-O
(04

CO
(04

o

CO

o

284

PEOCEEDINGS OF THE AMERICAN ACADEMY.

Figure 2. World's Trotting Records Plotted on Lofjarhhm Paper.

Distance, or course length = L (miles).

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

285

Figure 3. World's Trotting Records to 100 Miles.

r 4.r,

4.4

4..'!

i:2

4.1

4.0

3.9

3.8

3.7

3.G

3.5

^•'5-4

3
a 3.3

2 3.2

I 3-1

3.0
2.9

2.8
2.7
2.6
2.5
2.4
2.3

2.1

2.0 t-

i__^i_.4--

lit:"

f—- h"

^--— -

]-^

[TfTti

ffr

-;7|;

m*

i

;

1

—

\\\i

|: i

:i

-

il ;

1

V

■tix

:

:± :

:i

M

5

tx':

|i

■

trr:

■tS

gb

V^

jffl.

iid

1^

tt

"^

::;-

::::

\=A a -;-•}— 6

'mMmm^mikm^

.•ri853

il846;„

■iS-gpS

3tei:

bo
o

l-l

1.3

1.0
.8

:>.7

J 353

S
6

- A
.3

.a

a

g'S^HHgSql

CO CO

CO CO

00 m

rf co'

C^ CO Tt<

LO -.;

00

C5

O

id ud

-Log. distance (meters).-

286

PROCEEDINGS OF THE AMERICAN ACADEMY.

Figure 4. World's Trotting Records to 100 Miles.
Average speed over covirse (meters per second).

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

287

Figure 5. Running Horses, Speeds and Record Times.

-Distance Run.

>H

288

PROCEEDINGS OF THE AMERICAN ACADEMY.

Figure 6. Speeds and Record Times of Running Horses (Logarithmic Co-ordinates).

hog. meters. -

-Miles.

KENNELLY. — AN APPROXIMATE LAW OV FATIGUE. 289

Referring to Figure 6, it is to be observed that the record speeds are
low, or the times high, with respect to the straight lines up to 1000
meters (0.G2 mile). It is possible that this discrepancy on the
short courses may be due to the inertia of the horses ; that is to
say, the horses may be supposed to lose time, or to miss attain-
ment of speed, over the short runs below a kilometer, owing to the
effort required to start their bodies into motion from rest. This
time lost in acceleration is ignored in the straight-line logarithmic law,
which assumes that the animal starts with full speed. For courses
of over 1 kilometer, the discrepancy disappears.

Moreover, horse-races are stated to be rarely run over distances less
than 5 furlongs (1006 meters) ; so that the question of the discrep-
ancy over short courses is of but little practical importance.

The ascending straight line in Figure 6, drawn to meet the points as
fairly as may be, is carried through the 1-mile record, and makes an
angle with the axis of distance of 48° 22', whose tangent is |. The
falling line is also carried through the 1-mile record and makes an
angle with the same axis of — 7° 7' 30", whose tangent is — i.

The straight lines of Figure 5 correspond to, or determine, the fol-
lowing equations :

log r= llogZ— 1.6274 (4)

and log r= 1.6274-^ log Z. (5)

These are also respectively equivalent to :

Z§
7'=--— seconds (6)

42.4
and V = -j-y meters per second. (7)

By comparing equations (7) and (3) it appears from them that the record
speeds of trotting horses is less than the record speeds of running
horses over a given distance in the ratio of 33.9 to 42.4, or by 20 per
cent of the latter.

On courses longer than 1 kilometer, the straight lines of Figure 6
fit the observations of Table II with satisfactory precision, some ob-
servations lying on one side and others on the other. The greatest
discrepancies are at 2\ miles and at 4 miles. Figure 5 shows in its
upper line that both of these performances were remarkable. The
speed over the 2^- mile course appears from the data to have been
greater than the speed in the 2-mile event. Again, the speed in the
4-mile race was actually higher than the speed in the 3-mile race.

VOL. XLII. 19

290 PROCEEDINGS OF THE AMERICAN ACADEMY.

Column IX of Table II gives the time that should correspond to
each event, according to formulas (4) or (6). Column X gives the de-
viation from the record time. Column XI expresses the deviations
in percentage of the record time. The mean percentage deviation
between observed and computed record times between the limits of
1 kilometer (5 furlongs) and 6.44 kilometers (4 miles) is shown in
column XII to be 1.9 per cent. Consequently, we may expect by follow-
ing the ascending straight line of Figure 6 to predict the record time
of any race between these limits to within 2 per cent on the average.

The mean percentage deviation between observed and computed
record times for the entire series of events, i. e. between I mile and
4 miles (0.4 to 6.44 kilometers), is 2.4 per cent.

Horses Pacing.

The record data for pacing horse-races in harness on American turf
appear in columns I, II, and III of Table III. They are taken from
page 260 of " The "World Almanac " for 1906. The entries in the suc-
ceeding columns, IV to VIII, are then found in the manner previously
described. In Figure 7 the logarithm of the time, or log T in column
VII, is plotted against the logarithm of the distance, or logZ in
column VI. The logarithm of the mean speed in each event, or log V
in column VIII, is also plotted. Taking the ascending time-distance
line, it is a straight line ruled through the 2-mile record point, so
as fairly to conform with the other record points. It makes an angle
with the distance axis of 48° 22' or tan~^ |. Referring to the de-
scending speed-distance line, it is a straight line drawn through the
2-mile record point, so as fairly to conform with the other record points.
It makes an angle with the distance axis of — 7° 7' 30" or tan~^ — |.
The two straight lines include between them an angle of approxi-
mately 55° 30' 30".

The straight lines of Figure 7 correspond respectively to the following
equations :

log r= flog Z- 1.5363 (8)

log V = 1.5363 - \ log L. (9)

These in turn correspond respectively to the following :

V = '\ meters per second. (11)

KE2IN1-1LLY.

AN APPROXIMATE LAAV OF FATIGUE.

291

<

«
t

g

!?;
O

t-H S5

o
Pi

P5
.O

W

c
g

Ph

o

X

X

X

p >
►J "

CO

1 CL a o

a
a

05
1— J

N

ru

lO

C<|

o

lO

1— t

1-H

CO

^

o

CD

1—1

oo'

CO

^ a"

u-O

lO

f^.2

O

o

o

CO

s^

1 rt

C^'

oi

d

t-^

ci

CO

^1

73

1

t

•rtl

CO

1

^

l-s

o

00

q

lO

-^

CO

•>*

t-^

i^

o

d

d

o

1— (

o

o

--C

(M

1— (

(M

■^

lO

t^

O «

«

•6

lO

1— t

05

^

lO

lO

En-S

(M

t-i

o

CO

00

t^

3

CO

t-

o

c

•^

iC

be 3<

o

t~;

o

■^

CO

t^

00

I— I

c<i

(>i

oi

<m'

c<i

o

■^

o

00

lO

I*

CO

t^

t—

lO

t^

r~

CO

1—1

lO

Ttl

C5

O)

(M

f.^

bo
o

1— t

I-H

q

q

q

q

1— (

r— t

I-H

1-i

1—1

1—1

(N

to

o

CO

CO

o

e^*

CO

T— t

02

CO

lO

■•#

^

■<*<

<o

o

o

00

Ci

t-^

o

Tf

q

t-

CO

1— 1

c^

c4

c<i

c4

oi

<£)

CD

t—

CO

t^

CD

>4

O

CO

r~

CO

00

lO

to
o

o

o

O

00

o

05

c^

U5

CO

CO

cs

o<i

CO

CO

CO

CO

CO

•« £

re

t—

t^

CO

lO

in

i^

CO

OS

o

CD

lO

(M

O

^

CO

(>i

d

d

d

cc a

0)
OQ

1—1

!— 1

1—1

I-H

1-H

"

t-;

CO

t-

c

"*.

t^

a ^

■^

Ci

00

00

t^

c6

o

o

IM

CO

■^

2 2

00

CO

c^

00

■^

o

5 a

I— (

CO

'Jl

CO

CO

00

»o

lO

® "2

as.'§

o

<M

q

(M

o

lO

CD

id

t-^

CO

d

CO

>o

r— 1

o

lO

1—1

00

*"*

(M

■*

CO

l^

(D

§•2

•H|«

rH

(M

CO

■«**

vO

.2 a

Q

2

CO

lO

CO

•*

o

o

o

o

o

t^

s

C5

o

CI

00

00

CO

a

1—1

»— t

1—1

1— t

292

PROCEEDINGS OF THE AMERICAN ACADEMY.

Figure 7. Pacing Records Plotted to Logarithmic Co-ordinates.

-Log. meters-

H °

1000

100

"2
o

(S
CO

S
H

10

1

1

'g

1

a

o

«

w

■>J<

la

M

o

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE. 293

An inspection of column X, Table III, containing the computed
record times according to formulas (8) and (10), shows that the i-mile
record was 2 seconds longer than the computed time, the mile 2^
seconds shorter, and the 3-mile, 4-mile, and 5-mile events considerably
longer. These deviations appear in column XI, and are given in
percentages of the respective actual records in column XII. The ^-mile
deviation of 3i percent maybe explained by inertia on short courses.
The deviations of 10^, 8, and 8 per cent on the long distances are not
explainable in such a manner. The 3-mile and 4-mile records date
from 1891, and the 5-mile record from 1874. Reference to the
records of 1892, as given on page 273 of "The World Almanac" for
1894, shows that at that time the pacing records were low by com-
parison with those at the present date. Thus the mile record
(1.6 kilometers) in pacing was 124 seconds, and the 2-mile record
(3.2 kilometers) was 287.75 seconds, which are in deviation from the
modern records of those events, according to Table III, by 7.6 and
11.9 per cent respectively. Consequently, it seems fair to say that
these records of 3, 4, and 5 miles, which are 8 to 10.5 per cent
off the straight lines in Figure 7, would have been close to similar
lines drawn for records in 1894. In other words, the 1-mile and
2-mile records have steadily improved since 1891, whereas the 3-mile,
4-mile, and 5-mile records remain as they were at that date.

If we eliminate the 3-mile, 4-mile, and 5-mile records from considera-
tion, the average discrepancy between the computed and observed record
times is seen in column XII to be 1.9 per cent. If, however, we have
to consider all of the events, the average discrepancy is 5.4 per cent.

Summing up the analysis of horse-racing as presented in Tables I, II,
and III with their accompanying curve-sheets, it is submitted that the
logarithmic straight lines meet the observations, within reasonable
limits of range, to 2 per cent of average discrepancy. Moreover, these
corresponding straight logarithmic lines are parallel to each other for
running, pacing, or trotting. This means that there is a similar law
of fatigue in each of these styles of progression.

Men Running.

The first two columns of Table IV give the world's records of running
races. The first four events, up to 45 yards inclusive, are taken from
the Amateur Athletic Union Records, as given on page 262 of " The
World Almanac " for 1906. The remaining events, up to 623 miles
inclusive, are taken from page 242 of " The World Almanac " for 1904.
For each event the best record has been selected, whether the holder

294

PROCEEDINGS OF THE AMERICAN ACADEMY.

TABLE IV. — Men Rcnning.

Analysis of Best Professional and Amateur Worlds Records.

I.

II.

III.

IV.

V.

VI.

VII.

VIII.

IX.

X.

Dis-
tance,
yards.

Time T,
seconds.

Distance
L, meters.

Speed

meters
seconds

log L.

logr.

logr.

T com-
puted.

deviation,
seconds.

J kll

1 '°'^

20

A 2.8

19.5

5.188

1.2622

0.4472

0.7150

1.55

-1.25

-44.5

35

A 4.0

32.0

8.000

.5052

.6021

.9031

2.90

-1.1

-27.5

40

A 4.4

36.6

8.312

.5632

.6435

.9197

3.37

-1.03

-23.5

45

A 5.2

41.2

7.914

.6144

.7160

.8984

3.85

-1.35

-26.0

50

5.25

45.7

8.700

.6600

.7202

.9398

4.33

-0.92

-17.5

60

A 6.4

54.9

8.572

.7393

.8062

.9331

5.32

-1.08

-16.9

70

A 7.2

64.0

8.890

.8002

.8573

.9489

6.33

-0.87

-12 1

75

7.25

68.6

9.458

.8362

.8604

.9758

6.84

-0.41

-5.7

80

A 8.0

73.2

9.145

.8643

.9031

.9612

7.36

-0.64

-8.0

100

9.6

91.4

9.524

.9611

.9823

.9788

9.5

-0.1

-1.0

110

11.0

100.6

9.144

2.0025

1.0414

.9611

10.5

-0.5

-4.5

120

A 11.4

109.7

9.625

.0403

.0569

.9834

11.6

0.2

1.8

125

A 12.4

114.3

9.207

.0580

.0934

.9646

12.2

-0.2

-1.6

130

12.125

118.9

9.804

.0751

.0837

.9914

12.7

0.6

4.8

131.5

12.4

120.2

9.096

.0800

.0934

.9866

12.9

0.5

4.0

135

13.2

123.4

9.352

.0915

.1206

.9709

13.3

0.1

0.8

140

13.5

128.0

9.482

.1072

.1303

.9769

13.8

0.3

2.2

150

14.5

1372

9.458

.1372

.1614

.9758

14.9

0.4

2.8

180

A 18.0

164.6

9.144

.2164

.2553

.9611

18.3

0.3

1.7

200

19.5

182.9

9.380

.2622

.2900

.9722

20.6

1.1

5.7

220

A 21.2

201.2

9.490

.3036

.3263

.9773

23.0

1.8

8.5

250

A 24.6

228.6

9.294

.3691

.3909

.9682

26.5

1.9

7.7

300

30.0

274.3

9.144

.4382

.4771

.9611

32.5

2.5

8.3

350

A 36.4

320.0

8.792

.5052

.5611

.9441

38.7

2.3

6.3

400

A 42.2

365.8

8.668

.5632

.6253

.9379

45.0

2.8

6.6

440

A 47.0

402.3

8.561

.6046

.6721

.9325

50.1

3.1

6.6

500

A 57.8

457.2

7.910

.6601

.7619

.8982

57.8

0

0

600

A 71.0

548.6

7.727

.7393

.8513

.8880

71.0

0

0

660

A 82.0

603.5

7.361

.7807

.9138

.8669

79.0

-3.0

-3.7

700

89.0

640.1

7.203

.8069

.9494

.8575

86.5

-2.5

-2.8

800

A 104.4

731.4

7.007

.8642

2.0187

.8455

98.0

-6.4

-6.1

880

113.5

804 7

7.089

.9056

.0550

.8506

109.2

-4.3

-3.8

1000

A 133.0

914.4

6.874

.9611

.1239

.8372

120.0

-7.0

-5.3

1320

A 182.8

1207.0

0.602

3.0817

.2620

.8197

172.2

-10.6

-5.8

miles

1

252.75

1609.3

6.367

.2066

.4027

.8039

238.1

-14.6

-5.8

1.25

330.0

2011.6

6.095

.3035

.5185

.7850

299.0

-31.0

-9.4

1.5

403.5

2414.0

5.997

.3837

.6058

.7779

376.7

-26.8

-6.6

1.76

A 488.2

2816.0

5.768

.4496

.6886

.7610

446.8

-41.4

-8.6

2

551.5

3218.7

5.837

.5077

.7415

.7662

519.4

-32.1

-5.8

2.5

A 726.0

4023.0

5.542

.6046

.8609

.7437

667.6

-58.4

-8.0

3

859.5

4828.0

5.618

.6838

.9342

.7496

819.6

-39.9

-4.6

3.5

1004.2

563:!0

5.607

.7507

3.0020

.7487

974.6

-29.6

-3.0

4

1165.6

6437.0

5.525

.8088

.0665

.7423

1133.0

-32.6

-2.8

4.5

A 1345.0

7242.0

5.385

.8599

.1287

.7312

1293.0

-52.0

-3.9

5

1480.0

8047.0

5.436

.9056

.1703

.7353

1456.0

-24.0

-1.6

5.5

A 1662.6

8851.0

6.150

.9470

.2208

.7262

1621.0

-41.6

-2.5

6

1790.0

9656.0

5.394

.9848

.2529

.7319

1787.0

-3.0

-0.2

6.5

A 1976.4

10,462.0

5.293

4.0196

.2959

.72.37

1956.0

-20.4

-1.0

'

2085.0

11,265.0

5.404

.0518

.3191

. .7327

2126.0

41.0

2.0

KENNELLY.

AN APPROXIMATE LAW OF FATIGUE.

295

I.

II.

III.

TABLE IV. — Continued.
IV. V. VI. VII.

VIII.

IX.

i

Dis-
tance,
miles.

Time T,
secouds.

Distance
L, meters.

Speed

meters
seconds'

\o%L.

logr.

log V.

T com-
puted.

T'—T

deviation,

seconds.

1 t,.2 a
g -^^

1— t

7.5

A 2298.0

12,070

5.252

4.0817

3.3614

0.7203

2297

-1

0

8

2420.0

12,875

5.320

.1097

.3838

.7259

2470

50

2.1

8.5

A 2613.0

13,680

5.236

.1361

.4171

.7190

2645

32

1.2

9

2721.0

14,484

5.322

.1608

.4347

.7201

2820

99

3.7

9.5

A 2931.0

15.289

5.217

.1844

.4670

.7174

2998

67

2.3

10

3060.6

1(),094

5.248

.2060

.4866

.7200

3175

108.4

3.5

10.5

3229.0

16,900

5.214

.2279

.5097

.7182

3355

126

3.9

11

8388.0

17,703

5.225

.2480

.5299

.7181

3534

146

4.3

11.5

3543.0

18,508

5.224

.2674

.5494

.7180

3710

173

4.9

12

3722.5

19,312

5.187

.2858

.5709

.7149

3898

175.5

4.7

13

4231.0

20,922

4.940

.3206

.0264

.6942

4206

35

0.8

14

4572.0

22,531

4.928

.3528

.6001

.6927

4037

05

1.4

15

A 4804.6

24,140

5.023

.3827

.6817

.7010

5010

205.4

4.3

16

5286.0

25,750

4.872

.4108

.7231

.6877

5389

103

1.9

17

5655.0

27,360

4.838

.4371

.7524

.6847

5768

113

2.0

18

A 6010.0

28,970

4.819

.4619

.7789

.6830

6147

137

2.3

19

A 6360.0

30,580

4.807

.4854

.8035

.6819

6537

177

2.8

20

A 6714.0

32,190

4.794

.5077

.8270

.0807

6926

212

3.1

21

A 7570.0

33,790

4.464

.5288

.8791

.0497

7315

-255

-3.4

22

A 7968.0

35,410

4.444

.5491

.9013

.6478

7709

-259

-3.2

23

A 8390 0

37,010

4.411

.5683

.9238

.0445

7918

-472

-5.6

24

A 8825.0

38,620

4.377

.5869

.9457

.0412

8504

-321

-3.6

25

A 9224.0

40,240

4.363

.6047

.9049

.6398

8904

-320

-3.5

30

11.709.0

48,280

4.124

.6838

4.0685

.6153

10,930

-779

-6.6

40

16,647.0

64,370

3.868

.8088

.2214

.5874

15,110

-1537

-8.6

50

21,304.5

80,470

3.777

.9056

.3285

.5771

19,410

-1895

-8.9

GO

27,033.0

96,560

3.572

.9848

.4319

.5529

23,830

-3203

-11.9

70

32,595.0

112,650

3.456

5.0518

.5132

.5380

28,350

4245

-13.0

80

38,030.0

128,750

3.386

.1098

.5801

.5297

32,950

-5080

-13.4

90

43,215.0

144,850

3.352

.1609

.6350

.5253

37,610

-5605

-13.0

100

48,390.0

160,933

3..325

.2066

.6848

.5218

43,320

-5070

-10 5

110

55,245.0

177,030

3.204

.2480

.7423

.5057

47,130

-8115

-14.7

120

60,490.0

193,120

3.192

.2858

.7817

.5041

51,980

-8510

-14.1

130

68,685.0

209,220

3.046

.3206

.8369

.4837

56,890

-11,795

-17.2

140

75,030.0

225,310

3.003

.3528

.8752

.4770

61,830

-13,200

-17.0

150

80,905.0

241,400

2.984

.3828

.9080

.4748

68,380

-12,525

-16.7

200

126,568.0

321,900

2.543

.5077

5.1024

.4053

92,370

-34,200

-27.0

300

209,826.0

482,800

2.302

.6838

.3218

.3620

145,700

-64,126

-25.8

383

288,625.0

616,400

2.135

.7899

.4606

.3293

192,300

-96,325

-33.4

450

343,578.0

724,210

2.108

.8599

.5361

.3238

230,000

-113,578

-33.0

500

393,509.0

804,700

2.005

.9056

.5949

.3107

258,900

-1.34,600

-34.1

560

451,485.0

901,200

1.996

.9548

.6547

.3001

294,100

-157,385

-.34.8

623

510,030.0

1,003,000

1.966

6.0013

.7078

.2935

331,700

-179,300

-34.5

, ,

7.0

00

8.57

1.7782

0.8451

.9331

10.8

100

9.25

2.0000

1.0334

.9006

, .

21.6

200

9.25

2..3010

1.3345

.9065

49.2

400

8.13

2.6021

1.6920

.9101

, .

116.0

800

.6.90

2.9031

2.0645

.8380

245.8

1500

6.10

3.1761

2.3900

.7855

5

1571.6

8047

5.12

3.9056

3.1962

.7094

■ •

10,288.0

40,000

3.90

4.6021

4.0123

.5898

296 PROCEEDINGS OF THE AMERICAN ACADEMY.

was amateur or professional. Amateur records are indicated in column
II by the letter A. The last eight events are taken from records of the
Olympian Games, as published in the Boston " Transcript " for May 12,
1906. These international contests have been held in 1896, 1900, 1904,
and 1906. The best of these four records has been taken for each
event.

In Figure 8, log T (see column VI, Table IV) is plotted as ordinates
against log L (column V) as abscissas. The circles mark the world's
records and the crosses the Olympian records. In order to keep the
chart within reasonably small dimensions, retaining a fairly extended
scale, the observations are made to cross the chart twice, by employing
dual scales of ordinates and abscissas. The straight line is drawn
through the 500-yard record to meet the remaining observations. It
runs off the sheet the first time at log T = 2.71 and log L = 3.5. It
then recommences at the left hand of the upper line and finally leaves
the sheet at log T= 4.9 and log L = 5.45. These parts of what would
be a single straight line on a larger sheet make an angle of 48° 22' or
tan" ■'I with the axis of abscissas. The record points conform closely
to this line, swinging slightly from one side of it to the other. They
lie above it as far as log L = 2.0. They lie beneath from log L = 2.0^
to log L = 2.66, and again from log L = 4.0 to 4.5. In the remaining
parts they lie above. In other words, the straight line hits the record
path at log L = 2.1, 2.7, 3.75, and 4.5.

Table IV gives in column VIII the values of the record times cor-
responding to the straight line in Figure 8. Column IX gives the
deviation from the world's record for each event and column X the per-
centage deviation. The percentage deviation commences at —44.5 for
the shortest run (19.5 meters). It dwindles to 0 at about 110 me-
ters. It reaches a maximum of 8.5 near 200 meters, returns to 0 at 500
meters, swings over to —8.5 at 2800 meters, returns to 0 near 10
kilometers, swings to 4.9 at 18 kilometers, crosses the zero point near 30
kilometers, and then steadily increases numerically and in the negative
direction until it is —34.8 at 900 kilometers.

The large discrepancies below 100 yards may be attributed to inertia.
This is indicated in Figure 9, where the speeds of the events are plotted
up to 201 meters. It is evident from the dotted line following the rec-
ords that runners attain their maximum apparent speed in the neigh-
borhood of 1 10 meters (120 yards). At shorter distances the retarding
effect of inertia prevents a higher average speed in the run from being
developed. At longer distances, the starting retardation is reduced in
effect, but fatigue acts in its place. The simple logarithmic law, repre-
sented by the heavy line, takes no account of inertia and assumes a

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE. 207

maximum speed on an indefinitely short course. It is probably not
worth while going to the complication of correcting the formula by a
term or terms introducing a retardation at the start, since races below
100 yards are rare, and the deviation between the actual and computed
speeds disappears beyond loo yards.

At the other end of the line in Figure 8 the deviations become large
after log L = a or beyond 100 kilometers. Beyond 150 miles the de-
viations exceed 20 per cent. It is possible that the discrepancy may
here be accounted for by reason of the fact that somewhere in this
neighborhood the runner stops at intervals to take food, or rest, and
there is no longer a continuous performance enacted. According to
the logarithmic straight line, the speeds on courses between 450 and
623 miles (724 and 1003 kilometers) are only two-thirds of what should
be expected.

Summing up the entries in column X, without regard to sign, it is
found that if all the events are included from 19.5 meters to 1003
kilometers, the average deviation is 8.9 per cent. If, however, the
summation be limited to the range from 100 meters to 100 kilometers,
the average deviation is 4.3 per cent. This appears to be a satisfac-
tory result, considering that the range of distance is 1000 to 1, and the
range of record times 2500 to 1.

From a practical standpoint it may be inferred from an inspection of
either Table IV or Figure 8, that it should be easier for trained ath-
letes to beat the world's records between 600 meters and 9 kilometers,
or between 30 and 1000 kilometers, than to beat the records between
100 meters and 600 meters, or between 10 kilometers and 30 kilo-
meters. Expressed in another way, we should expect the degree of
physical exhaustion in record runs over the short courses up to 600
meters to be more severe than on the courses from that distance up to
9 kilometers. The existing one-mile or three-mile record does not seem
to be so severe as the records from 100 yards to 500 yards. Whatever
mathematical conclusions may be drawn from the data, the belief seems
unavoidable that a study of Figure 8 will be useful to athletes training
for running with a view to breaking records.

The crosses in Figure 8, representing Olympian records, while useful
as a check, do not serve the results in establishing the straight lines,
because these Olympian records are inferior to the corresponding world's
records, excepting that for the 100-meter race.

The line of Figure 8 corresponds to the following formulas :

log r = g log /. - 1 . 2307 (1 2)

FiGtTRE 8. World's Running Records.

.1 e^ M

4 4
>» >,

i3 8

a

s

s

a

i
o

iKENNELLY. — AX APPROXIMATE LAW OF FATIGUE.

299

Figure 9. Mean Running Speeds over Short Courses.
Mean speed over course (meters per second).

10

20

30

40

50

60

70

80

; 90

100

■ 110

120

130

140

150

160

170

180

190

200

1

i

m; ■m

::«ft

|::- 1 t:-^*|:^yi^;-Miim;ii;=sl?8lffi

{[[III

:

:

II III M

^^^

:

:

1 1 1 iitti

:

: : : 1

i 1 l|l III

■: -FO,

1

.,,

:
■

IJilllH

■

:

■

niifn

■

fcferl

:

i

:i

:r

■

T ■

:.:: ::

: 1— : : : *:

a a-
::o o

::0 1
::1 Q

:das: a
:jat::: .

jm - ■ ■ ■

•

TTTTTl

I

* '

1

1 ■

-Mean speed over course (miles per hour).-

NoTE. — Figure 8, on the opposite page, expresses the relation between time
and distance to logarithmic co-ordinates. The scale of abscissas at the top of the
figure gives the logarithm of distance in meters for the upper line ; that at the
bottom, for the lower line.

300 PROCEEDINGS OF THE AMERICAN ACADEMY.

or T= seconds. (13)

17.01 ^

log V = 1.2307 - i log X (14)

or V = — '-J— meters per second. (15)

Men Walking.

The data for walking races are given in columns I and III of Table
V. They are taken from page 244 of " The World Almanac " for 1 904,
and are world's records, amateur and professional. The best records
in walking, unlike other athletic sports, seem to have been made entirely
by professional walkers.

Figure 10 indicates the points found by plotting log T from column
V against logL from column II. In order to economize space, the
series of points is carried twice across the sheet to two sets of scales.
The straight line, seen in two segments, is drawn through the 4 -mile
record point, and is drawn to meet the other points fairly. It makes
an angle of 48° 22' or tan~^ |, with the axis of distances. The entries
in column VIII correspond to points on the straight line. The com-
puted times T' of each event are thus obtained and set down in column
IX. The last column gives the percentages of deviation between the
actual and computed record. The observations commence above the
line, or the record times for the 1-mile and 2 -mile events are long, or
the speeds low, by comparison with the 4-mile and the 50-mile records.
This can hardly be accounted for by inertia, as in horse-racing; because
at the low speed of walking, the retardation, due to starting from
rest, must disappear in less than 100 meters.

The points fall below the line between 4 miles and 30 miles, repre-
senting faster speeds than the computed to the extent of nearly fi per
cent. Between 40 and 70 miles the agreement between the observed
and computed times is close. Beyond 70 miles the speed falls below
that computed by the logarithmic line. The deviations do not exceed
5 per cent until beyond 1 20 miles.

The mean percentage of deviation, without regard to sign, is 5.6 per
cent over the entire series of events, and 3.4 per cent between the
limits of 1 mile and 120 miles.

There seems to have been scarcely any improvement in walking
records during the ten years preceding the date at which these have
been selected (1904).

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

FiGnRE 10. World's Walking Records.
Tiuie-diatance to logaritlimic co-ordinates.

301

a

a

a

CO S

o 1-1 o\ n ri> ta
IP la lo o" o trf

Log. of distance (meters), upper line.

:^

~r

u~

■^

i^

cc

r:

—

.—

M

W

CO

a

n

CO

CO

a

CO

o

i

00

a

■o

t-

cc

o

o

■*

•*

Tj"

13

a

a

a

M

s

g

o
o

-Log. of distance (meters), lower line.

302

PROCEEDINGS OF THE AMERICAN ACADEMY.

S5

M

»

H
§

s

to

e
S

o
u

V

cq

'S^

C5

rH

l-^

o

T-H

^]

I-;

o

o

CO

VO

T-H

00
1

■*

1

o

T-H

T-i

T-H

CO

i^i

CO

■*

td

o t- s

o ».S

r-l P,^

q

CD

lO

o

q

o

o

q

q

q

o

q

t^l

■*

(M'

O

cq

■^

ci

oi

■^'

ci

cri

CO

ci

CO

CO

(M

c^

CO

lO

o

Oi

CD

(M

t^

1 Is

1

1

1

t-H

T-H

<M

<M

H

1

I

1

13

o

"*.

q

o

o

o

o

q

O

q

q

O

■6

ci

^

,_(

c"

^

o

CD

.-^

CO

T)<

r-H

CO

2

■Tti

o

o

o

CO

(M

T-H

(M

CO

la

00

T-H

o

CO

t^

!M

q_

t-H

CO

T-H

CO

T-^

CO

t—

.-T

?— 1

(m"

c^"

CO-

co"

TtT

■^''

lO

»o

u

CO

CD

t—

Cfl

OI

CO

CO

00

co

CO

•^

Ci

•

E^^

(N

I— 1

o

o

CO

CO

00

CO

t^

■^

CO

H-t

^tl

CO

t"-

IM

(M

T-H

Ci

UO

CO

r-H

o

»— •

^2-

o

CO

O

C^

CO

"^.

■^.

q

q

q

1-;

I-;

>

o a
^ o

tH

OO"

?>

CD

^

•^

CO

(M

CO

T-H

CD

o

O

CO

o

■*

.

fl

o

lO

lO

00

T-H

■^

1—

CD

CTJ

CO

r^

o

o

(M

p

C3

CO

CO

r~;

q

q

q

q

q

q

^

a)

^

CO

-*

o

o

T-H

CO

o

T*

lO

T-H

00

t~

t^

(.^

CO

t^

CO

C3

T-H

CO

lO

CO

UO

■*

(M

O

(M

C5

CO

CO

t^

CD

CO

O

o

UO

lO

°

o

s

uO

iq

Iffl

iq

q

q

q

q

q

q

(N

00

CI

CO

CO

00

CO

(M

t^

00

CO

T-H

^

CO

OS

CO

c»

■*

T-H

CO

O

lO

• •— 1

lO

o

,

00

o

CO

T-H

IM

T-H

CO

-P

o

i-O

Ci

CO

>

a

la

00

o

s^

CO

Tin

TfJ

q

q

q

q

t-;

(N

c4

CO

CD

r~

00

1^

CO

CO

t^

t^

00

CD

S

CO

►4

CO

r^

CO

00

lO

Ttl

1-H

Oi

^0

O

CO

lO

o

o

00

o

o

CO

lO

o

CO

o

•^

CO

>

U)

C^

LO

q

CO

q

q

q

T-H

T-H

OJ

IM.

O]

_o

CO

-^

q

q

iq

o

o

q

q

q

o

o

O

q

00

CO

•^

T-H

00

o

T-H

•*

t-^

■"*!

q

od

-ii

CO

05

(N

o

T-H

00

CO

T-H

oo

00

iS

CO

CO

i—

T— t

q,

T-H

c<r

o

q^
co"

co"

q.

■>i<~

"^

t--

O

■^.

t-;

T-H

o

o

q

q

o

o

^^ DO

oi

00

CO

t~^

CO'

CO'

lO

uO

■^

T*

CO

c^

O

T— 1

(M

CO

■^

o

CD

t~

00

Ci

o

T— T

1—)

CO

CO

CO

o
oo"

CO
C5

T-H
t-H

T-H

T-H

o

I-H

CO_

Ci

r-t

©"

y

rH

IM

CO

tH

uO

CO

l~

CO

Ci

O

^

T-H

11

__

KEXNELLY. — AN APPROXIMATE LAW OF FATIGUE. 303

o

t^

CD

00

CO

o

CO

Ci

•*

0)

o

CO

f-H

CO

o

00

CO

CO

00

>o

iO

O

lO

ox

1

CM

1

o

o

o

1

1

1

>D

1

1

7

00

1

Ol

7

o

7

1-H

1

1-H

1

1-H

1

lO

UO

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

CD

to

r^

CO

•»»<

o

-*

CO

o

CO

o

o

lO

00

o

■^

o

CO

lO

o

c^

CD

00

uO

00

t—

C5

CD

CO

CO

t^

c;

i-O

o

•^

o

CO ■

c^

l-H

CO

CO

CO

lO

CO

Tl

CO

CM

I*"

CM

CO

CM

CO

t^

c-.

CO

UO

CO

1

1

CM
1

CM

1

CO

1

CO

1

CM

1

1-H
1-H

1

CM

1

CM

1

CO

1

o
as

1

CO
Ci

i

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

CO

t—

CO

C5

o

o

o

o

o

o

o

f— \

o

o

o

o

o

o

^

^

lO

Ci

■Tfl

o

■>!J<

CO

Ttl

o

00

CM

CD

Oi

CO

o

f->

o

o

o

^

c^

t^

CO

1—^

1— 1

Ttl

02

■o

CM

1-H

o

Ci

"^

o

o

r-r'

o

1-H

«u

CO

c-

o

CD

=i

CO

■^

f— t

00

o

!M

CD

t^

i.O

1*

CO

o

o

o

T-H

(M

SM

CO

•*

•<*l

o

CD

t-

c;

CO

1-H

l-H

1-H

s

CO

■*

1-H

CO

Oi

CD

t~

(M

(M

CO

CD

00

CO

on

rs>

C5

CD

CD

I—

CM

CM

CD

CD

O)

uO

O

•^

O

Tf<

CO

00

CO

1-H

s

I— I

o

a

o

o

00

O

9?

CD

o

o

-v

O

■^

l-H

00

■<r

00

Ol

CO

■^

CM

r-

t--

o

r-;

00

00

O

!N

CO

■^

UO

CD

CO

t-

t^

00

c?

1-H

ID

CM

CO

■*.

iq

p

1-H

■^

o

Tt<

00

t^

00

1-H

h-

05

t^

CO

CD

1-H

CO

"*

t-

CO

Oi

o

CO

o

I-^

lO

(M

■*

(M

t^

00

■*

f-H

CD

CM

05

o

CM

■^

l-H

o

iq

lO

■*

CO

CI

(?4

00

00

r-;

CD

iq

iq

■*.

■^

1-H

p

p

CO

1-H

r^

r--

o

lO

CO

CD

>o

-*

■*

CD

CO

CO

00

o

C5

CO

<r>

CO

t^

CO

o

00

t^

'rp

o

O

CD

'j;

1-H

(M

C5

CD

o

1-H

■^

o

CD

1*1

CD

CO

o^

■^

-*l

■^

(M

o

'-0

o

•^

(M

O

o

05

no

1*

•^

o

o

CD

CO

CO

o

U3

o

O

■*

Tt<

■^

'j;

■*.

■^

■*

CO

CO

CO

eq

CO

CO

CM

CM

CM

t^

CO

tK

^H

CO

CO

(M

rj

Tt<

■<H

o

1-H

05

1-H

t~-

CO

f— t

.•*

f-H

t^

(M

00

CM

(>J

t~

Tt(

■>9<

(M

CM

CO

o

o

o

CM

CD

00

C5

CM

CM

00

r-

o

•^

00

^H

»c

lO

■<1*

C^

o

CD

o

•^

o

C5

t~

I*

1-

o

t-;

00

00

Ci

CO

T»<

o

CO

t-;

r-;

00

C3

o

1-H

CM

CO

iq

p

p

«3

00

t—

t—

00

t^

o

00

t^

r~

00

CD

on

r-

t^

CD

oo

r^

CD

o

-TJ

<N

t^

CO

00

uO

■^

1-H

o

o

CD

lO

CM

t^

■^

CO

on

>o

c^

lO

00

o

00

o

o

00

o

o

CD

o

00

00

o

o

oo

o

o

CO

CO

CO

CO

»o

CD

00

o

q

o

ID

1-H

1-H

CM

CM

CO

o

CD

p

00

p

p

lO

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

»-M

CD

t~

•^

o

CD

t~

i-O

CO

o

o

>a

00

o

'^l

^

CO

lO

o

2^

CO

UO

Ci

c»

1— <

o

-<»<

o

CO

Ot)

00

'*

Q

CI

Oi

rti

o

«o

■^

CD

■^

00

Ci

o

uO

CO

lO

1-H

t^

t^

■^

CD

o

>o

CD

CD

o

CD

O)

00

■^

f-H

o

t~

lO

o

o

CO

Of)

a

00

o

a

?-i

(.N

(^4

CO

'^

>o

lO

CD

t-

1-H

1-H

1-H

CO
CM

S5

1^

Ci

•^

o

O

o

o

o

^

o

o

o

o

o

o

o

o

o

o

o

o

o

o

<M

»-H

o

t^

o

■^

t^

,— ,

o

o

o

o

o

o

o

o

o

o

o

(»

CO

■<1<

00

00

t^

CD

f*!

lO

o

■^

-5'

OJ

o

r-

•^

-rf

1^

o

C5

o

I—"

f-H

(M

CO

•*

ID

CD

t^

OC

o

1-H

■^

00

CO

00

t^

o

o

o

!M

~t<

!M

CO

•>*

O

o

CM

00

-^

o

CO

1-H

f-H

CM

OJ

CO

•^

<N

!N

Q-i

CO

•*

CD

00

o

f-H

I— c

CM

1-H

TJI
f-H

o

1-H

f-H

CM

CO

o

00

CD

o

00

o

00

CO

-<*<

>.o

o

o

O

o

o

O

o

o

o

o

o

o

o

o

o

o

l-H

I-H

I— 1

1—)

<.N

CO

■^

o

CD

t~

00

a>

o

CM

T-H

o

CM

o
c^

o

CO

o

CO
lO

304 PROCEEDINGS OF THE AMERICAN ACADEMY.

The straight line of Figure K) corresponds to the following
equations :

log r = I log L - 1.064G (16)

and log r= 1.0646 - i log Z (17)

or T= : seconds (18)

11. b

and V = — T- meters per second. (19)

Table VI is compiled from the data contained in the article on
" Rowing " appearing on page 208, Vol. X, of the " Universal Encyclo-
pedia" published in 1900. The entries in columns I, II, III, and V of
table VI are taken directly from that article. The remaining columns
give the deductions therefrom, as in preceding cases. The logarithms
of the times are plotted against the logarithms of the distances in
Figure 11. The 8-oar line is drawn through the 4-mile record point.
The 1-mile record is the only point seriously off the line, in the direc-
tion of low speed. The 1-mile speed is seen in column VI to be
lower than the 4-mile speed. The 4-oar line is also drawn through the
4-mile record point. The 3-mile event is the only one seriously off
this line, in the direction of high speed. The speed over this course
was 5.15 meters per second, which is only about 7 per cent short of the
record speed for the 1-mile event. The single-pair-of-sculls line is
drawn through the 5-mile record point. The ^-mile and the 1-mile
events are the only ones seriously off this line. It is possible that the
quarter-mile is affected by starting inertia. The mean deviation for
the entire series is 6 per cent. If we discard the 1-mile 8-oar event
and the |-mile singles event, the mean deviation of the remaining
series is 4.3 per cent. This seems to be a good showing for the loga-
rithmic straight line considering the extent to which both wind and tide
are capable of influencing rowing speeds.

All three straight lines in Figure 1 1 are drawn to make an angle of
48° 22' with the axis of distances.

The formulas deducible from the three straight lines of Figure 11
are presented in Table VII.

KENNELLY. —

AX APPROXIMATE LAW OF FATIGUE.

305

>

o

>5

ft

^

'^

H

o

^

t-J

«

Si

-***

VOL. XLII

306

PROCEEDINGS OF THE AMERICAN ACADEMY.

Figure 11. American Rowing Records.
Time-distance to logarithmic co-ordinates.

^ ^ ^ S 3 Log. of distance (meters).

1000

o o o

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

307

TABLE VII.

QtTAXTITATIVE RESULTS OF ANALYSIS OF RoWING RECORDS.

8-oar8.

4-oars.

Singles.

logy^= ^ogZ- 1.202
log r= 1.202-1 log L

■r ^^^

J = -r^-TT^ seconds

10.92

^^ 15.92 meters
~ ]l second

log r^^ log/. -1.1145

log V= 1.1145- |IogZ

I'-
^ = 13.02 ^^^°"*^«

13.02 meters
~ l^ second

log r=|logL- 1.085
log F= 1.085 -J log L

^=12.16^^'^^"'^^

12.16 meters
[\ second

It i.s seen that for any given distance over 1 mile, the speeds of 85,
4s, and singles are in the ratio lo.92 : 13.02 : 12.16, or 100 : 81.8 :
76.4, to the degree of approximation supported by the analysis.

Men Swimming.

The data for swimming have been taken from the world's records
given on page 252 of "The World Almanac" for 1905, setting forth
38 events from 25 yards to 4000 yards by amateurs and by profes-
sional swimmers of all nations. These data appear in columns I and
II of Table VIII. The remaining columns work from these data as in
preceding tables.

In Figure 12, log V is plotted against log Z, and also log F against
log L. The ascending time-distance straight line is drawn through the
220-yard (201.2-meter) record point, and thence in a direction to con-
form fairly well with the other record points. It is drawn to make an
angle of 48°. 22' or tan~^ | with the axis of distances. The descending
straight line of speed- distance is likewise drawn through the 220-yard
record point, and to make an angle of —7° 1' 30"or tan^^ — | with
the same axis.

Referring to the latter line, it will be observed that there is no visi-
ble retardation of speed over the short courses even down to 25 yards
(22.9 meters). On the contrary, the speeds for the first four events,
up to 60 yards (55 meters), inclusive, are higher than correspond to the
logarithmic straight line. This may be accounted for by the fact that
swimming speeds are only 15.5 per cent of men's running speeds at any
given distance beyond 100 meters ; so that the retardation at starting
must be much less than in running. Moreover, it is possible that the

308

PROCEEDINGS OF THE AMERICAN ACADEMY.

o

~«

'A

s

B

^

W

M

ff

i£

.0

T

ec

Vi

>

«5

S

X

X

s a
a:;

J-
s

"^~~

^^^"^

'"*"■

^^■"

^^^

^^

^^

,-'— ^

E-i

■s s

1

\o

-*

0

CO

t^

CO

lO

t^

05

I— 1

0

lO

■>*l

T— (

ll

"■S

»o

00

Ttl

T-H

<£>

0

10

1—1

CO

0

•^

<_>

CO

■»t<

t-

t- *rr

I— 1

1

1—1

1

1

1

1

1

^-1

0

r-t

_

^l-s

t^

CO

lO

Tt<

>o

no

^H

(.^

^r>

0

C5

-*

Tfl

-*

t-

r—

oc

0

0

CO

Tjf

CO

Jus

0

1— t

w

0

CO

<N

CO

I-

CN

0

0

0

to

a

1-

^iS

1

1

1

1

1

*— )

» s

1

■o

t^

CO

lO

•^

lO

ro

1—1

1^

.

oc

C5

0

■*

CO

CO

1— '

0

lO

0

CO

v-O

(M

0

w

iM

•n"

CO

'^

r^

■^

1—t

CO

>o

CO

CO

m

r-<

'O

I*

HH

08

T— 1

(M

(N

CO

■*

lO

CO

0

I^

TO

TtH

0
CM

CO
CM

'6

■^

CO

0

»— I

CO

(M

CO

fM

1— <

t^

^

0

■^

0

,

^•s

C5

in

CO

I--

1^

0

0

CO

lO

■^

0

-M

■^

CM

rr

hH

0

TO

~v

CO

t^

CO

00

CO

r^

a)

(M

r^

CO

r~i

t^

1— 1

>

.2 g
0
0

1—1

00

"*

iC

0

t--

t-;

00

co_

TO.

T)

(N

CO

CO

t^

r-~

(M

on

0

00

r^

(N

CO

<M

1—)

CO

(N

CO

on

u'

<M

-M

C-.

r^

CO

fM

r^

r—

1—1

(M

CO

1— «

TO

t^

t^

LO

0

0

uO

0

TO

1—1

CCJ

0

CO

0

<^

c—

t— I
>

2

(M

(M

C^J

C^

(M

T— (

01

1—1

1— t

1—1

rH

rH

T-^

0

0

1—1

Tf<

CO

(N

-*

1—1

lO

CO

C^l

<M

CO

rH

CM

t^

^

0:

•^

0

TO

-^

iC

1—1

"M

0

r^

(M

r^•^

^i

00

TO

lO

CO

CO

0

1—4

CO

0

irf(

CO

CO

0

lO

CO

t^

M

bo

CO

«5

<n

t^

00

TO

TO

0

0

1—4

(N

CO

ot

■*

•cf

>

r— 1

(N

•*

r—

TO

y-O

c-

-+

CO

i-O

0

1— (

0

TO

„

TO

&;

0

1—*

0

r^

O)

CO

lO

00

UT)

CO

•M

TO

r^

T-^

CO

CO

05

CO

c

1—t

CO

00

lO

00

^

I^

■^

CO

0

t^

bo
0

p

c^

CT

UO

t-

I-;

t-^

!>•

CO

TO

1—1
0^

r-^

CM

CO

"^

-2

OQ

•^

CI

Ci

-^

•*

lO

r~-

TO

0

0

CO

-¥

0

00

CO

;>

tx «

a

t-

or)

UO

1—1

CO

TO

1—

■^

CJ

04

0

0

a)

1^

TO

0

CO

t^

nri

0

Ttl

0

lO

CO

lO

■^

CO

CO

CM

CM

a;

a

JO

T— 1

>4"

«5

»o

(M

0

lO

■^

s 2

CO

»— <

t—

00

I— *

CO

-<t

CO

t^

fN

TO

C4

CO

00

X

§1

C3 %

-M

1— >

iCl

-f

CO

'M

*— *

0

TO

r^

fN

r-l

CO

■^

,_H

HH

<M

■^

■*

lO

t-

00

TO

c

0

CO

00

0

(M

0

s °

I—"

1—1

1—1

1— (

CM

CM

CM

00

Q

iM

0

ro

0

0

CO

0

0

<M

CO

0

CO

00

CO

00

as

iM

CO

-H

-f

f— 1

1— (

00

1— <

<N

CO

0

CO

t^

-H

CM

,

T— )

T^

(N

CO

10

10

10

CO

r^

TO

■^

Ttl

t^

1-H

>o

1-H

rH

rH

CM

CM

H S

<

<

<^

<

Ph

<5

<1

<

<

<i

<!

<

Ph

<

0

oT

0

lO

0

0

0

0

0

0

p

0

0

0

0

0

(M

Tfl

>o

CO

00

<Ji

0

(N

10

0

Oi

'.0

0

CO

1— <

1—1

rH

T— <

■M

CN

CM

.2 >>

Q

KENNELLY. — AN APPROXIMATE LAW (»1' FATIGUE.

309

o

o

t~

lO

CD

sq

T— >

IN

lO

CO

1-H

CO

l~-

Tt<

C5

o

C5

>o

CO

o

I-H

lO

1

1

O
1

1

1

l-H
1

1

o

1

o

U5

1

l-H

CD

(M

o

l-H

1

o

1

1

o

1

CO

rt>

Ol

T-H

lO

O

<N

O

C5

l~

r~

I— <

o

__.

00

00

o

(M

o

lO

o

CO

CD

00

o

o

1

CD
1

5^

1

05
1

CO

1

1

1

7

CO

CO

1

CO

Ol

00

f-H

CO

l-H
1

05

1

CO

1

05

1

(01

CO

00
CO

lO

o

O

t— '

UO

CO

CO

CO

■>*<

1—^

CO

CO

CO

00

O^

o

o

o

o

o

o

o

o

o

,_■

■^

-^

CD

o

,--4

o

o

CO

-^

— '

^

o

CO

Ol

o

Ol

00

CO

■*

Ol

l-H

UO

05

fN

r—

f-H

•o

T— I

■^

C5

c

C*'

o

OJ

o

T-^

c-.

TO

CO

M<

CO

CO

Oi

(M

CO

CO

■^

-<*

lO

lO

>o

CD

CO

l-

1^

00

o

l-H

^H

l-H

Ol

1— (

1*

1— t

1-H

cn
cc

CO

OO

on

^ri

CD

O

CO

1—t

t^

rft

<-)

CO

o^

Ol

CO

Ol

l~-

CO

l-H

00

CO

r^

lO

05

00

CO

O

CO

Oi

•^^

00

1—

r-H

■^

OI

C5

o

00

r^

CO

CT5

CO

CT)

CO

00

o

o

I^

1-H

o

o

CO

r^

00

o

f

CO

l-H

o

o

-H

I—

o

i-O

«)

Ol

00

CO

"^

lO

iq

q

q

t^

t---

t-;

t>;

CC

00

00

q

q

o

CO

q

q

l-H

1—1

uq

U3

CO

CO

CO

1^

00

o

05

CO

^

o^

f-H

CD

-M

i-O

CO

-^

l-H

o

>o

05

CO

CO

o

•— '

o

•V

t— I

■^

r-

1^

o

CO

CO

CD

,—1

CO

o

-f

o

o

1^

C5

^)

m

Ol

o

1-

1-

t-

o

CO

CD

■^

CD

aj

CO

o

CO

r-r

Ol

CO

r-<

CO

CO

CO

00

q

q

•

q

q

q

q

q

q

q

q

q

q

q

(^

q

q

q

q

q

q

q

I-H

q

(M

CO

1— (

lO

CO

1^

■M

Ol

o

O^l

CO

-^

lO

CO

r^

CO

Ol

CO

CO

CD

T— (

IC

iro

-f

o

c;

o

CO

CO

t~

'^

o

o

*— 1

OJ

o

»-H

r^

1^

CO

o

1^

CO

o

^

o

o

o

CO

rx>

o

CO

-T

CO

.—1

CO

-^

0(;

O

CO

1-

o

O

CD

UO

iq

q

q

t-;

l^

tr~

<X)

ou

00

00

q

q

o

CO

q

q

1-H

Ol

iq

vq

o

GO

UO

CO

CO

lO

f—

f^^

o

uO

c^

»c

CO

o

CO

00

l-H

^^

l-H

l-H

r-

UO

»-H

-M

CO

c^

1^

CO

00

CO

I^

CO

-M

<x>

o

o

-ri

^

Ol

Ol

r->

*

Ol

1-H

r^

1— (

«)

01

f^

Ol

CO

CO

o

CI

Ol

•^

<r>

^^

1-

Ol

■»4S

CO

y-^

CO

■^

-^

iq

iq

q

CD

l-^

t^

t-;

00

!>■_

00

30

q

q

o

CO

q

q

•

l-H

>q

iq

O^

'ti

o

1— 1

CO

O)

CO

o

0^

o

t^

r^

i-O

^H

CO

o

r^

»o

,-H

Ol

Iffl

1.0

O

t~

CD

Tt<

CO

CO

05

a)

f/)

CO

CO

CO

Oi

CO

f—l

CO

Ol

rt.>

00

o

T)

CO

rx)

c:

o

o\

(N

c^

T— *

f— '

l-H

■

T— '

•

Ol

q

q

q

q

q

q

q

05

o

C5

o

o

1^

CO

(N

35

CD

o

f-H

00

1—1

iS

CO

o

■*

CO

Ol

o

Ol

CO

CO

I^

o

o

o

•M

I^

M

CO

^-«

o

lO

-H

,-H

•^

CO

•rr

"O

h-

i^

^

l-H

no

C5

on

t^

?N

o

O

O

rt<

o

Tf

Ot)

O

CO

o

Ol

l-H

o

*

<-;

Y)

t^

<-)

<r>

1^

CC

CO

■^

■^

O

O

CO

CD

CO

t^

t^

00

CO

o

o

o

T-H

0^

T-H

Ol

CO

l-H

o

1-H

l-H

Ol

CO

CO

CO

o

o

Kl

CO

'*

o

o

■*

•*

o

o

uO

o

CO

-**

o

lO

o

CO

-^

Ol

o

o

CO

r^

— ^

CO

to

lO

CO

1^

t^

Ol

Xj

•^

— ^

Ol

>.o

,_^

CO

r^

•<i<

r->

— ^

-r

-r

»c

(M

«)

■N

CO

CO

-V

cc

ti

Ol

CO

o

Ol

t— I

-t<

<r)

Ol

C-.

t~

,-15

Ol

O)

?4

CO

CO

■^

•*

o

o

lO

CO

CO

CO

t^

00

CI

r—l

l-H
l-H

1— <

CO

CO

1-H

1-H

g?

00
CO

Ph

<

<

'i:

<

<

o

<

<

O

<1

t—i

l-H

<

-<

<

<

<

<

<

<;

<

o

o

o

o

o

o

o

o

o

o

c

o

o

O

O

o

o

(-1

o

V.O

(■"■>

-r

o

uO

o

CO

o

1.-3

t^

(~-l

00

o

o

o

o

OI

o

(^^

lO

CO

'^i

o

ct

■*

-*

lO

uO

CO

CO

l^

t^

t^

00

c-i

o

l-H

T-H

l-H

CO
r-H

T-H

l-H

CO

1-H

T-H

CO

o

0)

Cl<

o

^

C.i

o

cj

•tH

s:

-a

c

a*

D

P-

o

3

c

bo

c

-H

w

o

-o

Zj

CJ

CO

cS

1— 1

^

«

f/i

J^

11

n

3

CO

ca

O

<u

<*H

o

bo

U

p

Ch

r^

eS

4^

.^

CS

c

X^

rO

0)

. -a

*- c

c c
iJ _,

B 01

.2 >■

to cd

Ph ^
01
C3
<»

o
o

0)

»H

=^ 5

c ^

a cs

CO CO

a p4

S *>

-^ j< ^•

*< H 2

310

PROCEEDINGS OF THE AMERICAN ACADEMY.

Figure 12. Swimming Records.

Time-distance and speed-distance to logarithmic co-ordinates.

3.0 T
3.5-
3.4

3-3 -

3.2 -;

3.1-

3.0 '^:
2.9 -::

2.8;

2.7.

2.6 i
■2.5I
1 2.41
V2.3[i

a

o
be
.3 2.1

2.0

1.9

1.8

1.7

l.(

I..''

1.4

1.?.

1.2

1.1

1.0

t' 00 Ci

Log. of distance (meters).

O !-< <N CO ^ »0 to t-;

ci c-i ^J c-i ->! ri '>V

! ■/'

r-OfC/V V?

li.aL.

8

■a

s

2>a
SS

0 5

r^K> 1-1

s >.

KENNELLY. — AN APPROXIMATE LATV OF FATIGUE. 311

starting plunge made by the swimmer may actually advance him,
relatively speaking, on the shortest courses.

With the exception of the four open- water events, on all of which
the speed is distinctly low, and the 8()-yard event, which has an unduly
low speed (about the same as in the laO-yard event), the observations
cling closely to the straight line. The speeds at both the half-mile and
the 1-mile events appear to be distinctly higher than the rest.

Table VIII indicates that the mean deviation, without regard to
sign, of all the events is 3.5 per cent.

The formulas pertaining to the straight lines in Figure 12 are

log r = I log L - 0.4196 (20)

log V = 0.4196 - i log L (21)

/f

^=^ seconds (22)

2 6'^8
V — 1 meters per second. (23)

Men Skating.

Table IX gives the analysis of 24 yard and mile events and also 5
metric events, between the limits of 50 yards and 100 miles. The
data appearing in columns I and II of this Table are taken from the
records of the Amateur Athletic Union revised in 1905 and published
on page 265 of "The World Almanac" for 1906. They represent,
therefore, amateur records.

In Figure 13, log T has been plotted against log L, crossing the
sheet twice for economy in space. The straight line drawn in two
sections is carried through the 1-mile record point. It also runs very
near to the 2-mile, 4-mile, 500-meter, and 5000-meter points. There
is a wide deviation of the points from the line between 50 yards (45.72
meters) and 440 yards (402.3 meters). This may be attributed to the
influence of inertia in acceleration at the start. Column IV of Table
IX shows in fact that the maximum speed over a course is not reached
until the 440-yard event (402.3 meters), when it attains 11.43 meters
per second (25.5 miles per hour). The entries in column IV also
reveal considerable relative variation, and do not descend with the
same degree of uniformity as is manifested by the corresponding speed
entries in Table VIII, or other tables. Perhaps this variability in the

312

PROCEEDINGS OF THE AMERICAN ACADEMY.

H

K

M

X

>5

H

ft^

CO

S5

>i;

U

'^

g

f~

hH

1

<u

t>

c

M

S

t— (

^

W

V-

1-;

cc

>

w

«

<1

-2~-

H

c

0^ .

1.1
£.1

^

1
1

1

^ a

ppcoQqo^aqco^_T-;

CN CO CO t-^ -rj^ 'm' O lO ■-< O

1 1 1 1 1 1 ' 1 1 1

t^COO-f'-HCOCOC<l'<*IQOO<>-^0

,-,oocoor-Hiocood»0'<*i.oco'o5

1 -Hr-.

(M_ CO CO '* (M

o CO Tii o —

T-H I— T-H 1

1 1 M

T'-T
deviation,
seconds.

0<M

^i-HrHC;0q'-l-^QqO5>-l

CO -^ 'XJ -N T»< o c<i CO CO o

MM -j^ 1 M ^

CO .-Hr- p 00 p p p p O O O O

(N-^^ocdrH^oo-^ioc^oi

O |CO(MCiOeDi-HCDOiOOCOCl

■"Hi-Tcq

— !^^ CO t-; X
o CO lO CO CO

1 1-H r^ 1

MM

T'

seconds,

computed.

■<# CO CO ^ -^ -N
CO-^l-iOOCOOOOuOCi

(?q TjH cj CO o .-! c<i O --H "H

T— * I— 1 (71 CO ^ l^ i— '

1-H

pcOr-i(MpopOOOOOpp

-X> O I-^ 5<i -3< O ^ r-^ CD o o O o O

LO •<-»< CO -f lO 00 -O en (M (M t^ CO -^ 35

i-HCOior^asorHCO i--__p_o >o «5 co
(M't-T di 0^ \a <x> '^ -^ c£

I-H I-H T-H ^ C<) C^

p l+l I* I-H p
T-H I— ( T-H -^ CO

■^ lO c: '^r i-o

I-H lO

2.

Ci t^ CO -^ ro c7 r-. o CO CO

^ ^ O t^ CO '-I 00 I^ O t~

CO o CO -* o ^ >-~ c; o to

CO Oi 05 p p CJ p Ci O 05
O ' ' >-< ■ O >-< O i-H o

i005'M^i-HiOC035(MC»'*<0'--CO
CO'M'Mr-Ci1<'-HOOCOCOIr^:OCO

T-Hi~coiO'Xico'-o-*coT-Hoa533Ci
oasasCiOiCicooococooot^c^i-^

T-J O

(N O CO 00 CO
t- CO O Ci -.o
r- O r- CO -^

p p p p p

I-H I-H CO c o

be

(MiOC:c0t^C;iOC0c0O5
CO-^O-^CDtDOlMi-OCO
t^COO'-iOJOS'S'^OC-^

o 'r-i oi

r-HQO^COLO^OCOTjHOSCOT-Ht^CO
CO-^T-Ht^CDC^tMt^OOCOS^I-^CO

c;cooiocoi:^co:ot-t~-^T-H^^^

i-HiOt^OOCiOIOOOp'-JfNCOCOTt
CO ■ ■ -^

CO 'N ■* CO -t"
1-H lO C2 CO (M
(M t^ 5<I O i-O
O r^ O <M t^

I-H ■ j<i ■ ■

'6
he A

.sa

o

CO-^— <t^C0t^O-*iS>O
cO.-iOOt--couOr---*:M
vOlO35C0t~'^^l— icDiOio

■^?Dp'-;rHCClOpCOp
O " ' i-H (M'

T-HOOiOiO^HOU^OtOCiT— •!:o»— '
CO— OOCiOOOuO-tiCOOO-rf-HCO
Ci CO CO I^ 1— ^H lO Ci O C5 XI CO Ci o
i-HiOt^COClCOOOCi'-HT-HSqcOCC'^
CO ■ ■■*

I-H (M t- 00 —
(M -H O X t-
(M — CD lO 1*

CO t^ 3i T-H t--

I-H ■ ■ -N ■

bo

O'XJr— "McoGOTtiasic-— 1

iyDCOCOCDOOOOCOOQO
O 3D rt (M CO T)< p t-. Oi p

^ ' c<i CO

Ot^OOt^OCDQOt^cOQOt^t^OOcD
CO r^ CO CO lO -^ CO CO '-0 -t< — J: o ^
OOCOOOOOOOOC»iOOCDO
(MiOOC005(>]-X)0005C50'-H — iM

TJH ■ ■ ■ ■ lO ■ ■ ■

O (M o — o

05X0 O 35
35 t~ O t^ 35
CD t-- O 1-H CO

(N 'co ■ ■

II

o

■* lO O O :D 05 lO
(Nt^C0iOCOCOC00<l-Ht^

opcD'— ''-;t--.T)iC2pp
t-^t-^cb— <o'ci6i-Hoioo5

I-H 1— t T-H 1—)

iCa0'f'#OO(M'Ml000u0-*iC0
(NOlOCO'-HOOCO-'JiT-HiOt^iOi-H
COCOiOpcOCOT-i3500iOcO(M01'M

oaioiodciodt-^oocdcDcccdco

CD X CO
lO t— Ttl IM -rf

p O CO CO 00

i-< O 35 05 CO
T-H rH

Distance
meters.

-M CO CO 00

t-; lo r-. 00 ca CO CO p p p
i.oodt-^oi^-^'No6-*t^

■^'OCOOOOi^O-^OO

r-l r-( (N -N •* O 00 0^_
T-H

C0t-.p'1<t-;ppp0pp0pp

cicoodt-^cocooTtii--^ — -^cdT-Hi-o

O -H 01 CO -f OS 00 I- -X> CO 'O Tf< -t< CO

p^'N cq^'J'^p^o tMCO-*liOOt^COp_

1-h' CO* -^jT co" OO' CO* CO* ■^* O" co" ri 00* ■^* o*

T-HTfiCOQOOl — (M-^CO

1-H f-H I-H I-H

ooo c; o

d o" o o d
o o o o o

lO CD O O p

I-H I-H lO

Time
seconds.

CO lO
pcO0C-+iCO-^0<l(M'^p

ocdiocdcii-HiC'OOco

r-lrH,-HCOCOU50OCO

p O O O O O^ O O Tt< p CO O CO o

cooicoOTii — cicccioi-oot-^cd
'ra-fOcN:Ot--OcOiO'M — — 0 3:
1-H 00 lO t^ 00 Q0__00_^(M_^l^_CO_l^__".O —^CO

I-H* CD* 05* I-H* ■>* t^ o CO* lO"
1-H I-H — (M •M 7<l

xccooo-*
— ciJ t-^ d o

1* UO O CO CO

I-H 1-H O

2 M

a frt

Q

0U500000000

lOt^OOfMO-^lOOOtM

--H^iMCO-<*'«O00CO__

?-H

SrH'MCO-'J'iCOOOOOOOOO

T: i-H CO -^ lO CO t~ CO C5 o

|8Sg§§

"£ lO CD O lO O

a T-r_H*o*

Figure 13. Amntenr Skating Records.

Time-distanoe to loKaritlimic co-ordinates.
— Lor. of distance (meters), upper line. —

a M

b M

S 8

4.5

4.4

4.:;

4 ■'
4.1
4.0
3.9

.1^

CO c e .-• Ti «

CO CO

'I iMii/i :" h- 1 " — r

i +- Ctrali'hl. .■,.;!> ■. Uh .'InJ i

' o W.ttrlo Hucorj!, , „ . ■_ „_|.

I |i"'i'

C4

id

en

t4<

^J-^

■■\"--r^T-"r

3.G

'-■

3.5

'-■

3.4

-'-

3.3

—

3.2

—

3.1

r-

3.0

-

2.9

1-^

2.8

r- ■

2.7

-

2.6

M

2.5

-^....

/

1 : 1

I

o

=l^;}^i^S;-i;-)^^:j::;:;lH;):;

;-]i:;i]^:S^]li\i:iii:i;i-~;;llif^:i:\\\~t:i::i::

60

O

2.5
2.4
2.3
2.2
2.1
2.0
1.0
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6

::}::::l::::r:r=|:^;::::|,u:j::z.tr=^:r;tr:r:p:qj ry :;

— . '" ^

M -i< 1--; -.^_ I-. 00 o O rt N CO -+ CO
:i ei c^ i> ?j ?< ti c^' co' co' rf co eo la

ta 3 a .5 2

-Log. of distance (meters), lower line.

314 PROCEEDINGS OF THE AMERICAN ACADEMY.

records is due in some measure to the influence of wind, which is
particularly active on skating speeds.

Column XII of Table IX indicates that the mean percentage devia-
tion of the series of computed times against record times is 7.6 per
cent between 500 meters and 100 miles (160.9 kilometers). If the
same test is applied to the entire series between 50 yards and 100
miles, the mean percentage of deviation, without regard to sign, is 13.3
per cent.

The following formulas pertain to the straight line of Figure 13 :

log r = I log L - 1.4143 (24)

log ]^= 1.4143 -i log i/ (25)

or T= —-— seconds (26)

25. yb

V= — '-r- meters per second. (27)

Men Bicycling.

The data for bicycling have been taken from pages 267 and 268 of
" The World Almanac " for 1906, and are embodied in columns I and
II of Table X. The first five events are professional paced records
against time. The next series of events, from 2 miles to 100 miles,
inclusive, are professional motor-paced records, in competition. The
remainder are stated to be American competition, professional, paced,
hour records. The average speeds over the distances are set down in
column V. It will be seen that the speed between 2 miles (3.22 kilo-
meters) and 30 miles (48.28 kilometers) was almost precisely uniform
at 23.5 meters per second. In fact, it appears from the table in " The
World Almanac " that all of these records were made by one and the
same individual, on one and the same day (May 31, 1904), at Charles
River Park, Mass.. Again, from 31 miles (49.89 kilometers) to 50
miles (59.59 kilometers), the speeds are nearly uniform at 22.8 meters
per second (51 miles per hour), and these appear to have been
likewise made at Charles River Park by the same rider on the same
day (September 1, 1903). There is very little fall of speed between
the 5()-mile event and the 2-mile event, or apparently but little
fatigue as far as 50 miles. Beyond 50 miles, however, the speeds
fall off and fatigue is indicated.

KENNELLY.

AN APPROXIMATE LAW OF FATIGUE.

315

TABLE X.
Men Bicycling.

Anali/sts of Professional Bicfjclinc/ Paced Records.

I.

II.

III.

IV.

V.

Distance,

Time,

Distance

Time
T

Speed r,
meters

miles.

h. m. s.

meters.

seconds.

seconds

0.25

20.0

402.3

20.0

20.12

0.33

27.8

536.4

27.8

19.3

0.5

41.0

804.7

41.0

16.92

0.66

58.6

1,072.8

58.6

18.30

1

1 06.2

1,609.3

66.2

24.30

2

2 19.0

3,218.7

139.0

23.16

3

3 31.6

4,828.0

211.6

22.82

4

4 43.0

6,437.4

283.0

22.75

5

5 51.0

8,046.7

351.0

22.93

6

7 00.2

9,656.1

420.2

22.98

7

8 07.6

11,265.4

487.6

23.10

8

9 14.2

12,874.8

554.2

23.23

9

10 22.0

14,484.1

622.0

23.28

10

11 29.2

16,093.0

689.2-

23.35

11

12 36.2

17,703.0

7562

22.88

12

13 43.0

19,312.0

823.0

23.46

13

14 50.4

20,921.0

890.4

23.50

14

15 57.2

22,531.0

957.2

23.54

15

17 03.4

24,140.0

1,005.4

24.00

16

18 10.6

25,749.0

1,090.6

23.61

17

19 17.4

27,359.0

1,157.4

23.64

18

20 24.2

28,968.0

1,224.2

23.66

19

21 30.8

30,577.0

1,290.8

23.68

20

22 37 6

32,187.0

1,357.6

23.71

21

23 44.6

33,796.0

1,424.6

23.72

22

24 51.8

35,406.0

1,491.8

23.73

23

25 59.0

37,015.0

1,559.0

23.75

24

27 07.6

38,624.0

1,627.6

23.73

25

28 14.2

40,234.0

1,694.2

23.75

26

29 22.6

41,843.0

1,762.6

23.73

27

30 30.2

43,452.0

1,830.2

23.74

28

31 37.4

45,002.0

1,897.4

23.75

29

32 48.0

46,671.0

1,968.0

23.72

30

33 52.6

48,280.0

2,032.6

23.77

81

36 26.0

49,890.0

2,180.0

22.82

32

37 37.2

51,499.0

2,257.2

22.81

33

38 48.8

53,109.0

2,328.8

22.81

34

39 57.0

54,718.0

2,397.6

22.82

35

41 07.6

56,327.0

2,467.6

22.82

36

42 18.2

57,937.0

2,538.2

22.83

37

43 28.2

59,546.0

2,608.2

22.83

38

44 39.2

61,155.0

2,679.2

22.82

39

45 49.4

62,765.0

2,749.4

22.83

40

47 00.0

64,374.0

2,820.0

22.83

316

PROCEEDINGS OF THE AMERICAN ACADEMY.

TABLE X.— Continued.

I.

II.

III.

IV.

V.

Distance,

Time,

Distance

Time
T,

Speed r,
meters

meters.

seconds.

seconds

41

48

10.8

65,983.0

2,890 8

22.82

42

49

21.2

67,593.0

2,961.2

22.82

43

50

31.2

69,202.0

3,031.2

22.83

44

51

41.2

70,811.0

3.101.2

22.83

45

52

20.8

72,421.0

3,170.8

22.84

46

54

23.8

74,030.0

3,263.8

22.68

47

55

49.6

75,639.0

3,349.6

22.58

48

57

21.2

77,249.0

3,441.2

22.45

49

58

43.2

78,858.0

3,523.2

22.38

50

59

59

80,407.0

3,.599.0

22.36

100

2

48

11.8

160,930.0

10,091.8

15.58

miles

yds.

50

3

1

80,470.0

3,600.0

22.35

( 1

440

2

124,322.0

7,200.0

17.27

106

900

3

171,409.0

10.800.0

15.87

137

275

4

220,728.0

14,400.0

15.33

168

910

5

271,198.0

18,000.0

15.07

197

220

6

317,241.0

21,600 0

14.69

199

220

7

320,456.0

25,200.0

12.71

218

440

8

351,230.0

28,800.0

12.20

246

440

9

396,300 0

32,400.0

12.23

268

10

426,480.0

36,000.0

11.84

289

11

465,1000

39,600.0

11.75

312

880

12

502,920.0

43,200.0

11.64

335

1540

13

-

540,535.0

46,800.0

11.55

355

14

571,314.0

50,400.0

11.33

372

15

598,670.0

54,000.0

11.09

397

220

16

639,100.0

57,600.0

11.09

403

440

17

649,000.0

61,200.0

10.60

410

18

669,500.0

64,800.0

10.33

432

19

695,200.0

68,400.0

10.16

450

1540

20

725,600.0

72,000.0

10.08

466

660

21

750,600.0

75,600.0

9.928

485

220

22

780,700.0

79,200.0

9.858

507

1320

28

817,100.0

82,800.0

9.870

528

925

24

850,600.0

86,400.0

9.846

Figure 14 shows log T plotted against log L, as in preceding cases.
The observations fall near to a straight line, A B, B C, as far as 50
miles. This line makes an angle of 45" with the axis of distances.
For the purposes of comparison a broken line ab, be is drawn through
the 2-mile record point at an angle of 48° 22' to correspond with
the lines in all of the other figures. The contrast is very noticeable.
Beyond 100 miles (1G0.9 kilometers) the points tend to follow the
direction of the broken line, but not with any degree of precision.

The inference to be drawn from Table X and Figure 14 is that

Fiot'RK 14. Bicyclinf/ Rerords.
Time-distance to logaritlimic co-ordinates.

a ^
S g

s

s

a -

<= ~ e-i CO •»"

(M

S 00 5

X c5 S ^"K- of distance

'- o ■-' (rriHtiT.si, iipiiiM liiii

■4 _o.^ro_lo3_aloniil- Motor-paced Keeordstln'Competltlon.^ . .;
-;.-4: XrqfB98lon«l«I'aced-Honr Pecord's. : : i"" '

I— • -'''•or(..-i3ional"A«aln8t»Tlmo. "paced Racord'a._

\rIT

rr

-.4'

2.0
Ml
l.S
1.7
1.0

1.0
1.4
1.3
1.2

i

•-* A -. a t-:

c^ ri CJ

-T"--r— -..

^Oi

X"Tr

00 o o -^

c^ C) «> M M ri

a I a

rV

Y

:;^B Bi I

"..()

1.;)
4.8
4.7
4.6
4..5
4.4

4.3

h

4.2
B
4.1

4.0

:; !l

3.8

3.7

3.C

3.5

3.4

3.3

3.2

3.1

3.0

O

a

,,i^,,:=.,::::p:.,p.:pnfn.:p.:|:::::::::|^::|,;:..:p:.::::n..3,p
^ t^ X C; o r-. c^ CO -J<

o

o

CO

o
A

CO CO CO CO

a

g

.s

o

a

CD

318 PROCEEDINGS OF THE AMERICAN ACADEMY,

we have no means of discovering from these records what the highest
speed of a bicycle rider may be. It is inconceivable that there should
be no fatigue for 50 or 30 miles. If the record speed over 30 miles
be 23.77 meters per second, the speed over 2 miles should be much
greater. If the same law of fatigue held for bicycle riders as for run-
ners, walkers, swimmers, and skaters, the speed at 2 miles should be
approximately Vl5 or 1.40 times greater ; viz., 33.3 meters per second,
or 74.4 miles per hour. There is no proof, however, that the same law
of fatigue applies, and the air resistance at such high speeds might in-
fluence the results. It is, however, evident that the speed at 2 miles,
or similar distances, is kept down abnormally to that at 30 miles. The
explanation suggests itself that the records are all made on a circular
track of considerable lateral inclination. The cyclist, on short runs,
perhaps attains the highest speed that he dares and not the highest
speed that his muscles could develop. When travelHng at 23.75 meters
per second (53 miles per hour), careful steering must be needed to keep
on the track, and perhaps the records indicate the limit of steering
nerve rather than the limits of speed and endurance below 30 or 50
miles. The case is somewhat similar to that of automobiles in this
respect. The track records of heavy-weight gasolene automobiles, as
given in " The World Almanac " for 1906, indicate speeds of 30 meters
per second (67 miles per hour) at 1 mile, and hardly any reduction
up to 10 miles, or no sensible fatigue within those limits. At 1000
miles (1609 kilometers) the speed is 20.35 meters per second (45.5
miles per hour). But on the straightaway courses, as distinguished
from track courses, the speed averaged 46.77 meters per second (104.5
miles per hour) at 1 mile, and fell off distinctly with distance at a
rate very similar to the fatigue rate of racing animals. Until, there-
fore, we have a wide straightaway course, say 5 kilometers long, pro-
vided for cyclists, of as good quality throughout as is presented in
circular tracks, the cyclist's maximum speed will remain a matter
of doubt.

Summary of Results.

A summary of the results of the various analyses in regard to
accuracy is presented in Table XL Column I refers to the table con-
sidered. Column II, the character of the race. The total number of
records in each table appears in column III. The range of distances
covered is given in column IV, both in miles and in kilometers. The
sum total of the percentage deviations, without regard to their sign,
as found for each table, including every record, is given in column V.
The quotient of the sum in column V, by the number of records in

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

319

i, tcid

■^"^

■~~"

^So

-*

a

o

lO

i.O

a?

(N

CO

K

CO

CO

l-H

CO

o

»o

Ci

^i|

r~^

l-H

I-H

■<*1

CO

■*

CO

t^

CO

cQ

St » a

a^o

o

^H

1-

CO

f^

o

00

t^

t^

HH

Total

cent

Deviat

l-H

CO

^

(M

CO

00

>-o

CO

CO

l-H

l-H

2

<s

s

23

■*

(M

CD

CO

t^

1^

f-H

01

cy

"V

CO

C.

l-H

05

CO

l-H

a

1— t

o

ti

ci

1^

^1

1

•s

<o

o

GO

o

o

o

o

lO

M

m

'"

l-H

o

o

—

l-H

o

o

QQ
9

o

■*

7

o

o

l-H

CO

CO

o

o

l-H

s

o
o

CO
CD

'^J

-^

§

o

1

1

r-ifr.

T-H

o

1-H

■-

^ >,s .

Numbe
of

properl
acceptab
Records

HH

HH

tr^

00

CO

as

o

uO

00

<M

(-«

85

<M

o

c^

r-H

CO

M

a

» _ <D

O

Averag
perceiita
Deviatio
over enti

series o
Records

CO

o
id

id

id

■5

o

CO'

CO

CO

p

>

l-H

w

r-l

o » m .', a

<

t-"

>

m total
ercentag
eviation
thout re
rd to Big

05

C5

CO

o

00

CO

l-H

o

00
00

o
o

00

co'

CO

CO

lO

l-H

H

PJ

00

l-H

I-H

T-H

CO

CO

m^»^§,

r-H

O

,

o

!»

s

»

o

■*

o

o
o

r-

t--

I-H

0)

T-H

^

00

r-i

00

C5

CO

■4.9

o

T-H

o

o

(N

c!>

c4>

1

(M

J)

o

i5

:;>

•<*<

00

O

CO

■*

o

>

tsi

T— 1

o

o

O

l-H

o

o

d

O

O

CO

I-H

o

a

DO

o

(>1

CO

o

C3

f— t

•^

vO

o

»o

o

(M

I-H

Oh

^

1— t

.1.

1

1

o

1

1

1

t. 00

Total
numbe

of
Record

HH

o

CO

O

(N

(M

t-

00

05

t^

?-H

CO

05

CO

rH

CO

<M

,

be

o

bO

'3

'S

he

c
3

tx

s

s

F

be

.5

d

a

w

CO

c

o

..-t

^

<U

O)

o

-'

^1

CO

no

™

(h

;-.

c

J3

c

c

c

o

o

O

0;

o

o

a»

o

HH

«-H

tn

S

s

s

s

s

3

HH

HH
HH

HH

HH

>

>

HH

hH
HH

Vi

h-t

H

HH

i—t

>

HH

HH

320 PROCEEDINGS OF THE AMERICAN ACADEMY.

column III, gives the mean percentage deviation for each table in
column VI, or the mean difference between the computed record time
and the actual record time in percentage of the latter. Reasons
have been given in connection with each table why certain records
should be left out of consideration. The remainder are discussed in
columns VII, VIII, IX, and X. These contain what may be called
the net results, while columns III, IV, V, and VI contain the gross
results.

In the net results, horses come out the best, and nearly equally weU
for trotting, running, or pacing, viz., 1.9 per cent mean deviation. The
horses come out much better than the men in this comparison. It
should be observed, however, that the ranges of distances covered by
the horse-races are relatively small, — 20, 6.4, and 4, — whereas with
men the ranges are successively 1320, 120, 6, 185, 300, — much greater.
Perhaps if the ranges covered in the horses' performances had been
similar to those covered in the men's performances, the disparity in
precision would disappear. In the men's performances the net average
deviation is about 4 per cent, except in skating, where it is 7.5 per
cent. The net average deviation of all the 207 records is 3.9
per cent.

Considering the gross results of columns III, IV, V, and VI, the
lowest deviation is found in trotting horses (2.43 per cent) followed by
men swimming (3.52 per cent). The greatest deviation is in skating
(13.26 per cent). The mean deviation of the whole series of 257
records, rejecting none, is 7.05 per cent.

It is submitted that the summary in Table XI demonstrates the
proposition that the records in races of men and of horses approxi-
mately follow straight lines when plotted on logarithm paper ; because
the average percentage deviation of all the records is only 7 per cent
from the line, and excluding 50 of the records as unreliable for reasons
assigned, this average deviation falls to 4 per cent. The record time
that should belong to any given distance within the usual limits, and
for any of the events considered, except bicycling, can thus be assigned
with these probable degrees of accuracy.

It is not so remarkable that the records of any one event, such as
men running, should approximately conform to a logarithmic straight
line ; but it is remarkable that the straight lines should be parallel, or
substantially parallel, in all of these eight classes of events, including
three gaits in quadrupeds and three gaits in bipeds, besides motion
in the water and over ice. Figure 1 5 collects all of the logarithmic
straight lines on one sheet to a reduced scale. The ascending parallel
straight lines are time-distance lines. The descending parallel straight

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

321

Figure 15. Speed-distance and Time-distance Lines.

Asceudiiig lines, time-distance ; descending lines, speed-distance.
Log. of distance (meters).

S5— _Miot-Ci'-Mir5r-05«Heo
— oi e4 ci oi ci m n m m n -^ 'f

Explanation.— At the riglit of the Figure the numerals 1.0 to 5.0 are loga-
rithms of time (seconds).

VOL. XLII. — 21

322

PROCEEDINGS OF THE AMERICAN ACADEMY.

lines are speed-distance lines. The mean speeds of the various events
in Table I to IX inclusive are plotted with relation to the descending
lines in such a manner as to reveal their deviations as clearly as

possible.

Deductions from the Results.

Starting with the approximate equation

T ^ seconds

(28)

as borne out in the preceding discussions of records in eight different
kinds of races, where c is a constant for each type of race, it follows
that as the length of the course, X, increases, the time occupied in the
race will increase according to the following table :

TABLE XII.
Effect of Increase of Distance upon Increase in Time.

Increase

in
Distance.

Increase

in

Time.

Increase

in
Distance.

Increase

in

Time.

2

2.181

70

119.1

3

3.442

80

138.4

4

4.757

90

158.0

5

6.114

100

177.8

6

7.506

200

387.8

■7

8.928

300

770.5

8

10.38

400

845.9

9

11.85

500

1087.0

10

13.83

600

1335.0

20

29.08

700

1588.0

30

45.90

800

1845.0

40

63.43

900

2106.0

50

81.64

1000

2371.0

00

100.1

Thus, if the equation (2>S) is correct, doubling the distance means
increasing the time by 118 per cent, and increasing the distance 60

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

323

times increases the time 100 times. Since the equation (28) is not set
up as a rigid law, but as a statistical approximation, or approximative
law, we cannot expect to find the relations of Table XII accurately
presented by all the events. For instance, if we limit ourselves to the
first statement that twice the distance should be covered in 2.1.S times
the time, we can examine all the cases of pairs of such events in the
records already considered and find what the ratios of time are when
the distances are as 2 : 1. The answer to this question is contained in
the following table :

TABLE XIII.

Analysis of Time

Katios over Pairs of Courses ix

Ratio

OF 2

:1.

Table.

Type

of

Racers.

No.

of

Pairs.

6

Range of
Distauces covered.

Sum

of

Ratios.

Mean
Ratio.

High-
est
Ratio.

Low-
est
Ratio.

Miles.

Kilometers.

I

Horses trotting

1-100

1.01-161

11.092

2.218

2.327

2.098

II

Horses running

19

0.25-4.0

0.4-6.4

40.523

2.133

2.244

2.000

III

Horses pacing

3

0.5-4

0.8-8.0

6.662

2.221

2.374

2.058

IV

Men running

57

0.03-300

0.02-483

123.754

2.171

2.593

1.818

V

Men walking

18

1-500

1.61-805

39.678

2.204

2.375

2.073

Vl Men rowing

8

0.25-6

0.4-9.6

17.950

2.244

2.518

1.981

VIII

Men swimming

23

0.014-2

0.023-3.2

50.337

2.189

2.436

2.016

IX

Men skating

13

0.03-100

0.05-161

27.198

2.092

2.556

1.760

General average

146

. . .

. . .

317.194

2.173

2.593

1.760

Taking, for example, the case of running men with reference to Tables
IV and XIII, there are 57 pairs of records in which one distance is just
double the other, commencing at 20-40 yards and ending with 150-300
miles. The sums of all the time ratios for these 57 pairs of events is
123.754, representing an average value of 2.171, as against 2.181 re-
quired by Table XII from equation (28). The highest ratio in any of
these pairs is 2.593, and the lowest 1.818.

It will be seen that men running and men swimming come nearest in
their averages to the ratio 2.181 ; while men skating deviate the most
(4 per cent). Taking all the 146 pairs of double distances presented
in the entire set of records, and without rejecting any, the average

324

PROCEEDINGS OF THE AMERICAN ACADEMY.

ratio of all is 2.173, which is within 0.4 per cent of the value 2.181
required in equation (28). This result constitutes an independent
demonstration of the approximate accuracy of that equation. If pairs
at short distances affected by starting retardation, or at very long
distances, had been rejected, the agreement would have been still
closer.

Equation (28) leads to the following :

T = -TT^ seconds
y "

(29)

or the time varies approximately inversely as the ninth power of the
speed in the race. If we assume that the racer reaches the winning
post virtually exhausted, so far as affects racing eff"ort, then the time
of exhaustion varies inversely as the ninth power of the speed. The
computed eff'ect of increasing speed is given in the following table :

TABLE XIV.
Computed Infltjence of Speed upon the Time of Exhaustion.

Speed.

Time.

Reciprocal.

Speed.

Time.

Reciprocal.

1.0

1.000

1.0

1.5

0.0260

38.4

1.01

0.915

1.09

1.6

0.0146

68.7

1.1

0.424

2.36

1.7

0.00843

119

1.2

0.194

5.16

1.8

0.00504

198

1.3

0.0943

10.6

1.9

0.00310

322

1.4

0.0484

20.7

2.0

0.00105

512

Table XIV shows that if a racer increases his speed 10 per cent, he
brings down his running time from 100 to 42.4, or 2.36 times ; and if
he doubles his speed, he becomes exhausted in 0.195 per cent of the
original time, or 512 times more quickly.

The records do not show that any one racer would be exhausted
512 times as soon if he doubled his speed, because there is no evi-
dence at hand as to the behavior of any single individual at doubled
speeds. If, howevei-, any one racer could be trained to take the record
speed at each event in the entire series, — that is to say, if a runner
could be trained to take every race from the 20-yard dash to the 50-
mile run at world's record speeds in each, — then this ideal athlete
would be exhausted in a time approximately as the inverse ninth
power of the speed. It is reasonable to assume that what would be

KEXNELLY.

AN APPROXIMATE LAW OF FATIGUE.

325

true of this ideal athlete also tends to be true of any normal athlete,
even though his range of speeds and distances be limited.

As an example of this rapid rate of exhaustion, take the 20-mile
(32.19 kilometers) running event in Table IV. The speed at which
this race was run averaged 4.794 meters per second as shown in
column IV. At twice this speed or 9.588 meters per second, there is
no exact distance in the table ; but the nearest is 131.5 yards (120.2
meters) at 9.696 meters per second. The time of the 20-mile event
was 6714 seconds in column II. The time of the 131.5 yard event was
12.4 seconds, or 541 times less, as against 512 times in Table XIV.

Again, consider the last event in Table VIII of swimming records.
The 4000-yard (3657-meter) event was finished in 3824 seconds at a
speed over the course of 0.9564 meters per second. If we take a speed
1.5 times greater than this, or 1.4346 meters per second, we find one
near to it in the table ; namely, 1.420 meters per second (column XI)
in the 150-yard (137 -meter) event. According to Table XIV, the time
of exhaustion at 1.5 times greater speed is 38.4 times less than the
original. The time should therefore be 3824 -^ 38.4 = 99.6 seconds.
The actual time of the event is given as 96.6 seconds.

Distance

Equation (28) leads to the following expression for L :

L^c^ T^ meters. (30)

That is, as more and more time is allowed for racers to occupy in an
event, the distances they will traverse will not be directly proportional
to the time, but will vary as the eighth power of the ninth root of the
time, approximately. A few numerical values are given in the accom-
panying table :

TABLE XV.

Distances traversed avitii Increasixg Racing Time.

Time.

Distance.

Time.

Distance.

1

1

20

14.3

2

1.85

50

32.4

3

2.66

100

60.0

4

3.4.3

200

111.0

5

4.18

500

251.0

10

7.74

1000

464.0

326

PROCEEDINGS OF THE AMERICAN ACADEMY.

It is thus indicated that with 500 times more time, the distance
covered will be only 251 times greater. As an example, we may take
the 4-mile (6.44 kilometers) walking event of table V. It occupied
1658 seconds. If we increase the time twenty times, or to 33,160
seconds, we should expect from Table XV that the distance covered
would be 57.2 miles (92 kilometers). The nearest event to this in
Table V is the 60-miles (96.6 kilometers), occupying 34,847 seconds or
21 times the original time, which is a satisfactory agreement.

Another consequence of equation (28) is expressed :

L '^^ ^ meters

(31)

or the distance covered in a race varies approximately as the inverse
eighth power of the speed adopted. That is, if an athlete could be
trained to take any distance from the shortest to the longest at the
record speed for the event ; then the distance which this athlete would
be able to run before being exhausted would be as the inverse eighth
power of his speed over the course. A few numerical values are given
in the accompanying table :

TABLE XVI.
Distances capable of being traversed as the Speed is increased.

Speed,
V.

Distance,

Reciprocal,

Speed,
V.

Distance,
F-8.

Reciprocal,
T'«.

1.0

1.

1.

1.5

0.0390

25.6

1.01

0.923

1.08

1.6

0.0233

43.0

1.1

0.467

2.14

1.7

0.0143

69.8

1.2

0.233

4.30

1.8

0.00907

110.0

1.3

0.123

8.16

1.9

0.00589

170.0

1.4

0.0678

14.8

2.0

0.00391

256.0

The table shows that if the speed is doubled, the distance that can
be run, before exhaustion, is reduced 256 times according to (31).

As an instance, the 20-mile (32.19 kilometers) running event of
Table IV, already referred to, may be selected. The speed over the
course was 4.794 meters per second. At 9.588 meters per second the
distance should be -^-^ = 0.0781 mile = 125.7 meters. Table IV shows
that at 9.696 meters per second, the nearest to the required speed,
the distance run was 131.5 yards, or 120.2 meters.

KENNELLY.

AN APPROXIMATE LAW OF FATIGUE.

327

Speed.
Equation (28) leads to the expression for speed;

V 'i:^ cL

-i

— T~ meters per second

(32)

already illustrated in formulas (3), (7), (11), (15), and (19). It means
that the speed of racing over courses of different lengths varies in-
versely as the eighth root of the length, approximately. Table XVII
gives a few numerical applications of this rule.

TABLE XVII.
Effect of increasing Distances upon the Speed over the Course.

Distance,
L.

Speed,

Reciprocal,
Li-

Di.stance,
L.

Speed,
Lh

Reciprocal,

1

1.

1.

100

0.562

1.78

2

0.917

1.09

200

0.516

1.94

3

0.872

1.15

300

0.490

2.04

4

0.840

1.19

400

0.473

2.12

5

0.815

1.22

500

0.460

2.17

0

0.799

1.25

600

0.449

2.23

7

0.784

1.28

700

0.441

2.27

8

0.771

1.80

800

0.433

2.31

9

0.760

1.32

900

0.427

2.34

10

0.750

1.33

1000

0.422

2.37

20

0.688

1.45

2000

0.387

2.59

30

0.654

1.53

3000

0,368

2.72

40

0.631

1.59

4000

0.355

2.82

50

0.613

1.63

5000

0.345

2.90

(JO

0.599

1.67

6000

0.337

2.97

70

0.588

1.70

7000

0.331

3.02

80

0.678

1.73

8000

0.325

3.08

90

0.570

1.75

9000

0.320

3.12

328 PROCEEDINGS OF THE AMERICAN ACADEMY.

According to these results the speed has to be reduced 1.33 times to
race 10 times the distance, and 1.78 times to race 100 times the dis-
tance. Thus, taking the 100. 6-meter event (110 yards) in Table IV,
the speed over the course is 9.144 meters per second. At 96.56 kilo-
meters (60 miles), nearly 1000 times greater distance, the speed has
fallen to 3.572 meters per second, or to 39.1 per cent of the former.
According to Table XVII, the speed should fall to 42.2 per cent on
increasing the distance 1000-fold.

Another consequence of formula (28) is expressed thus :

8

F^ c ' T~^ ^ — r meters per second (33)

or the speed over the course approximately varies inversely as the
ninth root of the racing time.

In Table XVIII the speeds of the various racers are set down as
computed for courses of 1 kilometer and of 1 mile. Thus over 1 -kilo-
meter courses the speed of the running horse is 17.88 meters per sec-
ond (column VI), and the time for the race 55.9 seconds. At the end
of the series come swimmers, with a speed of 1.108 meters per second
and an inferred kilometer-time of 902.4 seconds. Table VIII shows
that the time for 1.006 kilometers was 925.4 seconds. Turning to the
mile range, the speed of the running horse is 37.7 miles per hour over
the 1-mile range. His mile-time is 95.5 seconds, both computed and
recorded. The speed of the swimmer is 2.336 miles per hour, and the
mile-time 1544 seconds as computed, and 1476.2 seconds as observed.
The speed of a running man is almost precisely half that of the trotting
horse, for distances above 1 kilometer where starting retardation ceases
to affect the horse. The speed of a professional walker is very nearly
the speed of a professional rower (singles).

It is to be noted that all these speeds are average speeds over the
courses. There is no evidence among the records to show what the
speed was at different points in the course. So far as concerns anything
appearing in the data, the speed of a runner, for example, which
averages 7.17 meters per second over a 1-kilometer course, might be
10 meters per second in the first part and 5 in the last part, or vice
versa. Evidence is lacking to show what the facts are, and they are
of great importance to the science of athletics. The speed of a world's-
record type of trained runner might be determined at any or all
points of a course, either by securing a light recording chronograph
on the back of his belt, with a thread payed out as he ran, or by
pacing the runner with a light motor-car carrying an automatic speed

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE.

329

>

H

(C

S
iJ

a
o

s

O

lO

o

o

fr- '^ Ji TJ

»C

^1

lO

o

i^

l^

o

q

o

(N

►-.

i =i §

o

id

00

(6

M

•^

^

1-H

CO

d

J^

C-.

1-H

*— t

o

»o

o

c^

o

00

I'-

^-1

r— (

(M

CO

(M

CO

CO

■^

?-H

'S fc.

ti '*- J; 'O

o

00

US

o

l-H

CO

1-H

o

o

o

p.

— -;. ^ M

o

t^

OJ

o

00

-ai

r-i

CO

CJ

•^

gS-'S

Oi

I— t

r— <

o

CO

>-o

f-^

-V

•"*

1-H

i-H

^

(N

<M

CO

CO

CO

uO

o

'O

.^

00

iM

O

t^

1-H

-M

CO
CO

K

2 '£

1-;

lO

*-H

o

l-H

o

00

CO

CO

— 3

■s O

a 'J3

t-^

o

o

CO

o

Tti

^

d

d

(j4

CO

CO

CO

!N

T— f

I-H

'"'

1—1

1-H

6

«

a
o

Ot

t--

CO

CO

1-H

T»*

><

a

Iffl

o

o

^^

•o

!N

t^

CO

1-H

Ttl

1— <

i

CO

so

of

CO

CO

o

t^

o

CO

d

1-H

LO

00

CO

q

1-H

'd

I-^

r-^

.— t

t— 1

»

OS

,

»*./

lO

uO

Oi

<M

t^

(M

00

OO

HH

p*--

lO

C5

CO

C-.

l-H

CO

'^

CO

X

^

55

CO

^

-M

o

1-H

00

CD

1-H

>

<>i

?— '

^

q

00

00

t^

o

:o

o

^

I—"

f— (

I— 1

d

d

d

d

d

d

■

1u . . ^•

CO

>o

1— (

Time fo
1 Kilo-
meter,

aeconde

05

05
00

o
o

oo

C5
00

q

•"*

r*

lO

CO

I~-

o

CO

•"*

00

o

o

^

l-H

1-H

1-H

1-H

c^

"'

s^

M OO

CO

•^

C5

OS

CO

00

o

* ^
f^ ^

00

o

Ct

o

t^

CO

<M

OS

o

1— 1

03

0) ' ;:

00

o

-M

C5

t— t

t-

-Tl

00

I-H

>

1 °

I— 1

c

I-H

t-^

d

o

O

-^

*"*

^^

^

■>*

eo

CO

t^

lO

o

CO

(M

f-H

'^

o

uO

i^

wi

o

CI

•rti

TS

be

o

la

o

>a

lO

-N

7^

00

•^

>

2J

70

1— (

l-H

q

00

00

t^

t^

CD

O

cc

T-H

1-H

'"'

1— i

d

d

d

d

d

d

oo

o

1-H

*i

<M

CO

00

Ol

•

•*

c^

Ci

C35

q

05

O

1—1

q

CO

o

^

CO
CO

f-H

IS

1-H

CO'

1-H

1-H

1-H

oi

Tj<

CO

CO

tr-

\a

:o

CO

>

t~

o

-*

O

(M

Tjt

o

-s;

Ci

^

(M

c^

CO

.-H

CO

O

1-H

00

1-H

^

1

CD

uO

o

■^

(M

C-1

^-

q

q

•»*l

r-i

1— 1

r-t

1— (

I-H

1-H

1-H

r—t

1-H

d

tc

iC

S

ni.woj

br

bo

•^

'-w

b£

it

X

it

■S

?

c

'3'

4-d

O

_C

,^

to

m

O

.2

H

3

53

C
3

O

9

"M

-M

> '

o

o

o

QO

u

00

•<*<

'«

?

M

£

CO

c

PH

c

c

s

C

a

3

o

O

a>

O

o

Zt

a)

aj

ej

1— (

HH
H-C

K

S

S

s

§

S

S

%

h4

^^

^^

HiH

^

>

»— <

>

l-H
>

)-H

>

P-H
HH
l-H

>

330 PROCEEDINGS OF THE AMERICAN ACADEMY.

recorder, or by noting on a chronograph the times of the runner's
passage past a suitable number of fixed points along the track.

Although nothing can be stated directly from the data in this
paper as to the degree of uniformity or of variation in the speed of
a record-making trained racer, yet if it is proper to apply the inference
drawn from a long series of complete races to the speed conditions
during the operations of any one taken singly, then it should follow
that the speed of a record-maker is very nearly uniform throughout
the whole course. If, as appears from the whole series, the time of
exhaustion varies inversely as the ninth power of the velocity, and this
condition applies within the limits of any single race, then it is easily
seen that the quickest way to reach the winning post is to take at
the outset that speed which will just produce exhaustion at the goal,
and keep to that speed throughout the course. The penalty for
raising the speed at any part would be a degree of untimely exhaus-
tion far outweighing the benefit gained. Trainers commonly direct
practising athletes to spurt, or accelerate, near the end of the run.
This advice must be sound on any theory, because to slacken speed
at the end, if there is any balance of running energy left, would be
absurd. The runner naturally expends all the available energy balance
on the last lap ; but if he is able to accelerate to any appreciable extent,
it must mean that he has kept too much energy in reserve, and he
would have done better to adopt a higher general speed. If, on the
contrary, his pace falls to any appreciable extent at the end, he would
have economized time by maintaining a lower general speed. Ex-
perimental evidence to test this theory would be of great interest.
If the theory is correct, athletes, in training for a given event, ought to
be motor-paced, the speed of the pacing motor being set uniform.
In the earlier practice, this motor-speed should be, say, 15 per cent
less than the desired record-speed, and the athlete should train to keep
close to the motor. As the training progressed, the uniform speed of
the motor over the course should be raised, say, 1 per cent at a time.
Of course these suggestions advance beyond the warrant of evidence
at this time.

Conclusions.

An analysis of the various national and international appended
racing records, as above detailed, leads to the following conclusions, for
trotting, pacing, and running horses, as well as for running, walking,
rowing, skating, and swimming men :

(a) The time varies approximately as the ninth power of the

KENNELLY. — AN APPROXIMATE LAW OF FATIGUE. 331

eighth root of the distance. Doubling the distance means increasing
the time 118 per cent (Table XIII).

(b) The time occupied in a record-making race varies approxi-
mately inversely as the ninth power of the speed over the course.
Doubling the speed cuts down the racing time 512 times (Table XIV).

(c) The distance covered increases approximately as the eighth
power of the ninth root of the time. Doubling the time of the race
allows of increasing the course length by 85 per cent ( Table XV ).

(d) The distance covered increases approximately as the inverse
eighth power of the speed over the course. Doubling the speed cuts
down the distance that can be covered 256 times ( Table XVI ).

(e) The speed over the course varies approximately as the in-
verse eighth root of the distance. Doubling the distance brings down
the speed about 9.3 per cent ( Table XVII ).

(f) The speed over the course varies approximately as the inverse
ninth root of the racing time.

It may be noted that all of the statements (a) to (f) are different
aspects of one and the same fact.

(g) If any of the three quantities Z, T, and F = -=, be plotted on

logarithm paper as ordinates to either of the other quantities as ab-
scissas, the record points will fall on, or near to, a straight line
(Figures 2, 3, 6, 7, 8, 10, 11, 12, 13, and 15).

(h) Athletes aspiring to break racing records might succeed better
in attacking those whose points fall below the straight lines of speed
against distance, or above the straight lines of time against distance,
rather than those whose points fall on the opposite sides of those lines.

(i) The records presented on bicycling do not determine the
proper highest speed of cycling below 30 miles (48 kilometers), since
there is apparently no reduction in speed by fatigue up to that
distance.

(j) With the exception of bicycling, as above noted, the law of
fatigue in racing is the same, or very nearly the same, with horses as
with men, in air or in water, as indicated by the records analyzed
in this paper.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 16. — Jaxuary, 1907.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY (JF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE,
E. L. MARK, DIRECTOR. — No. 183.

AN EXPERIMEXTAL STUDY OF THE IMAGE-
FORMING POWERS OF VARIOUS
TYPES OF EYES.

By Leox J. Cole.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMl'ARATIVE ZOOLOGY AT HARVARD COLLEGE.
E. L. MARK, DIRECTOR. — No. 185.

AN EXPERIMENTAL STUDY OF THE IMAGE-FORMING
POWERS OF VARIOUS TYPES OF EYES.

By Leox J. Cole.

Presented by E. L. Mark. Received September 14, 1906.

Table of Contents. paoe

I. Introduction 335

II. Description of Apparatus 340

III. Experiments 347

1. Eartliworm (Allolohophora foetida [Sav.] ) 350

2. Land pianarian {Bipaliurn keivense Moseley) 361

3. Mealworm (larva of Tenebrio molitor Linn.) 367

4. Sow bug (Oniscus aselliis Linn.) 371

5. Cockroacli (Per ip/aneta amet-icana Jjinn.) 375

6. Mourning-cloak butterfly ( Vanessa autiopa Linn.) 380

7. Water scorpion {Ranatra fusca Pal. 13.) 382

8. Pomace fly {Droxophila ampelophila Loew) 388

9. Garden snail of Europe {Helix pomatia Linn.) 390

10. European garden slug (Z.('M«.r maxiHiHS Linn ) 391

11. Cricket frog (.Ic/v's //r////«s Le Conte) 392

12. Green frog (Rana damata Daudin) 400

IV. General considerations and discussion 402

V. Suinmarj'^ 412

VI. Bibliography 415

" Die wirkliche Xaturwissenschaf t begann damit, dass man, anstatfc iiber
das Wesen der Schwerkraft zu fabuliren, die niiherea Uiiistaude der Bewe-
gung de.s fallenden Steines, des Pendels u. s. f. genau be.stinunte und mbg-
lich.st genau und einfach beschrieb. In der Biologic, speziell in Bezug auf
die uns Jiier intere.ssireuden tneehaniscJie?! Lichtwirkungen kann die Aufgabe
des Forschers audi nur dariu bestehen, die durch das Licht ausgelosten
thierischen Bewegungen ihrer Abhiingigkeit nach niiher zu bestimmeu und
zu beschreiben." (Loeb, '90, p. 20.)

I. Introduction.

The structure of eyes has been long and carefully studied, both as
to gross anatomy and finest histological detail. This is esiiecially true

336 PEOCEEDINGS OF THE AMERICAN ACADEMY.

of the human eye, but the eyes of other vertebrates, and of the inver-
tebrates as well, have received a large share of attention. The abil-
ity of various eyes to form more or less accurate images of external
objects has been for the most part inferred from the application of
physical laws to the knowledge of their structure. In the case of man,
however, there is less need for inference, since his common experience
in seeing is a constant demonstration of the ability of his eyes to form
images. Nevertheless, even here certain factors which add to the
efficiency of the eye as a visual organ, but are in no way concerned with
the actual physical formation of the image on the retina, must be taken
into account. For example, judgments based upon experience involv-
ing other elements than mere image-formation, such as the mental
superposition of the images of the two eyes, giving a stereoscopic
effect, the action of the ciliary muscles and other mechanisms for
accommodation, and the influence of other senses, especially that of
touch. The filling out of the blind spot of the retina by the mind is a
good example of the influence of experience upon the interpretation of
the actual sense impression. It is not unlikely that the eye of a baby
is capable of forming practically as good an image as that of an adult ;
but the baby lacks the experience and training of the adult which
would enable it to form proper judgments, and consequently it appears
to have little if any conception of distances and space relations in
general.

The images formed by other eyes than the human can also in a
measure be studied from direct observation. Thus the image of distant
objects may be seen upon the retina of the freshly removed eye of an
albino rabbit, since the absence of pigment leaves the posterior por-
tion of the eyeball semi-transparent, and the relaxed eye is accom-
modated to distant vision. Or, the posterior portion of the eyeball of a
pigmented eye, such as that of a frog, may be cut away, and by aid of
a microscope the image may be projected so that it can be observed
directly, or thrown upon a screen. This has likewise been accomplished
with the eyes of some invertebrates ; thus Exner ('9i) succeeded in
taking a remarkable photograph through the eye of a fire-fly, while
Parker ('95) demonstrated empirically that the compound eyes of Astacus
form a single image rather than a number of separate images.^ Again,
in the eyes of many vertebrates the decolorizing effect of light upon the
visual purple, after protracted exposure, may be seen upon the retina,

1 The multiple photographs obtained through the corneal facets of insect eyes
do not represent the rethial image formed by these eyes, since in obtaining such
photographs only one portion of the dioptric apparatus is used.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 337

and the monochromatic image thus formed may even be permanently
fixed by a proper treatment with alum solution (Kiihne, '79, p. 299)
or platinum chloride (Stern, : 05).

By means of the ophthalmometer and other optical appliances, Beer
has made an extensive study of accommodation in the eyes of the lower
vertebrates and cephalopod.s. This faculty of accommodation may in a
general way be related to image formation, since it is probable that an
eye that is capable of accommodating differently to near and to distant
objects must be able to form fairly distinct images of those objects. The
converse, however, is not necessarily true, since there are eyes which
appear to have considerable image -forming power, but show no mechan-
ism for accommodation. The evidence that the compound eyes of
insects can accommodate seems insufficient, and there is no evidence
of this power in the eyes of any of the other invertebrates except the
cephalopods, unless perhaps the movements of the eyes of certain cope-
pods may be considered as such.

All the methods which have been enumerated for determining the
exact nature of the images formed by eyes have certain obvious defects.
Especially is this true in the more lowly organized types of eyes, where
comparisons with the human eye cannot be so closely drawn. A study
of structure alone cannot give an exact basis for this determination,
since it is not always easy to interpret the optical properties merely
from the structure. This is well illustrated in the variety of opinions
that have existed as to "mosaic" vision in insects and other animals
with so-called compound eyes. Empirical tests with fresh eyes lose
much of their value on account of the changes that take place in the
tissues immediately their blood supply is cut off and they are removed
from the animal. The most serious of these changes are loss of tonus
and coagulation of the fluids. The image on the retina, due to the
change in the visual purple, is not definite enough to be of much use for
settling this question ; and the inferences to be drawn from the action
of the eye in accommodation can be of only the most general nature.

It has not been the purpose of the work described in the following
pages to furnish a more exact method of determining the precise image-
forming powers of eyes. The aim has been, rather, to treat the forma-
tion of images ft"om the point of view of their relation to the animal as
a living organism, — to determine in what way the ability to form a
more or less perfect image affects the responses of the animal to light,
and what relation, if any, this result has to the normal habits of the
creature, and to its behavior under experimental conditions. This
investigation was suggested to me by Professor G. H. Parker, the sug-
gestion being an outcome of his study of the photo tropism of the mourn-

VOL. XLII. 22

338 PROCEEDINGS OF THE AMERICAN ACADEMY.

ing-cloak butterfly, in the course of which he found that this insect is
able to discriminate between light derived from a large luminous area
and that from a small one, even when the light from the two sources is of
equal intensity as it falls on the animal, and that it usually flies toward
the larger areas of light. He took the biological significance of this
reaction to be that " this species remains in flight near the ground be-
cause it reacts positively to large patches of bright sunlight rather than
to small ones, even though the latter, as in the case of the sun, may be
much more intense." (Parker, -.03, p. 467.) It is evident that such
a reaction as that described can be taken as "a rough measure of the
image-forming capacity of the eyes of the butterfly studied, but a com-
parison of diff'erent animals on this basis can be made only in a very
broad and general way.

Except for the work of Parker just mentioned, there appear to be
few if any direct references in the literature to experiments or observa-
tions calculated to determine the difference in the reactions of animals
to luminous (or illuminated) fields of different sizes ; at least, few if any
in which other factors, such as intensity and color of light, have been
eliminated. An experiment performed by Loeb ('90, p. 47, Versuch 2)
upon a species of crepuscular moth {Sphinx euphorbiae) perhaps comes
closest to the conditions of the present investigation. Specimens of
the moth were brought into a room illuminated at one side by a win-
dow, while upon the opposite wall was placed a kerosene lamp. Here,
then, were conditions with a large area of light at one side and a small
source of light at the other. No comparison was made of the relative
intensities of the lights, but as the experiment was performed at the
approach of twilight it is to be presumed that the light from the win-
dow was much less intense than it would have been in the middle of
the day, so that the light from the lamp was relatively more intense.
Animals liberated at a point midway between the window and the lamp
flew to the window ; and it was not until they were brought within
about a meter of the lamp that they flew in its direction. Loeb re-
gards this result as due entirely to the relative intensities of the light
received from the two sources ; but from the experiments to be de-
scribed later, it will be seen that the larger area of the window was
undoubtedly an important factor irrespective of, or at least in addition
to, the intensity of the light.

A number of observations have been made on the tendency of ani-
mals to go toward, and to collect in, shaded areas. Mitsukuri observed
that certain Japanese marine snails (species of Littorina) gathered in
largest numbers in the shadow of certain objects which he used in his
experiments (Mitsukuri, :01, p. 1, Experiment 2), and he furthermore

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 339

explained the movement of these snails landward at the time of flood
tide, when they are negatively phototropic, as due to the fact that, on
account of the bank, with bushes, grass, rocks, etc., less light came from
that side. Somewhat similar observations have recently been made
upon another species of Littorina {L. rudls) by Bohn (-OS), who found
that snails moving in an illuminated field took a course determined by
the relative amount of light coming from different directions, and that
if black or white vertical screens were placed in the field, the course of
the animals was correspondingly deflected; they were "attracted" or
"repulsed" by the screens, as the case might be. Bohn emphasizes
the importance of the size of the screen, but makes no attempt to de-
termine whether the greater influence of a large screen is due to the
formation of a correspondingly larger image upon the animal's retina
or merely to the fact that it reflects a greater amount of light if it is
white, and absorbs more if it is black. He apparently made no attempt
to determine exactly his light intensities, either absolute or relative,
and consequently his results are rather crude and only qualitative in
this respect.

Torelle ("03, pp. 470, 471) made a number of tests of frogs with
reference to shadows and to dark objects, and found that, although
ordinarily positively phototropic, they move out of the sunlight into
the shadow, even when by so doing the movement is away fi-om, or at
right angles to, the direction of the ray (p. 487). When once in the
shadow, however, the animals turned and faced the sun-illumined area.
This occurred when the shadow was that of a building or merely that
beneath a box raised a short distance from the ground. These results
in their bearings upon the present investigation will be discussed more
fully in considering the results of my own experiments.

The greater part of my experimental work consisted in testing the
reactions of various suitable animals to two sources of light, differing
in area, but of equal intensity at a point midway between them, where
the animals were exposed. It was planned so far as possible to select
animals with representative types of eyes, such as direction eyes (pla-
narians, etc.), compound or mosaic eyes (insects, crustaceans, etc.), and
camera eyes (vertebrates), and, in addition, to conduct parallel experi-
ments upon eyeless forms (such as the earthworm) which are known to
be sensitive to photic stimulation. For the purpose of the experiments
it was obviously necessary to use only animals which were decidedly
positive or negative in their reactions to light, since those which were
normally irresponsive or indifferent to light coming from one direction
only could not be expected to show evidence of discriminating between
luminous areas of different size. Furthermore, in so far as possible,

340 PROCEEDINGS OF THE AMERICAN ACADEMY.

animals which normally react positively to light, and also those which
are negative, were used in order to determine whether, as would be
expected a priori, the responses (evidences of discrimination between
the two lights) were reciprocal in the two cases. Forms which would
require to be experimented with under water were avoided on account
of the practical difficulties involved, — not only optical complications
due to the reflection and refraction of light by the water and the
containing vessel, but also on account of the difficulty of directly test-
ing the lights at the middle point in order to determine whether that
received from one source was exactly equal to that received from the
other.

Before passing on to a description of the apparatus most used, I wish
to express my indebtedness to Professor G. H. Parker, to whom, as has
already been mentioned, the study owed its inception, and under whose
direction, in connection with one of his courses, it was carried on for a
year. The later prosecution of the work was under the direction of
Professor E. L. Mark ; to him I owe my gratitude for much valuable
criticism and advice, since to his attention to accuracy of method both
in experimentation and in the deduction of conclusions therefrom must
depend in large part any merit which the present contribution may
possess.

II. Description of Apparatus.

In all the experiments on the reactions of animals to two lights of
different areas, as well as in certain of the other lines of investigation^
the same general apparatus was used. Special devices were found
necessary in working with each species of animal ; these can best be
explained in connection with the accounts of experiments with the
respective species. Although the apparatus was changed in some of
its details and added to from time to time, the changes and additions
were small and comparatively unimportant, the general plan and ar-
rangement of the apparatus remaining essentially the same throughout.
It will be described in its final form, reference being made to such addi-
tions or alterations as seem to be worthy of mention.

The apparatus was installed in a long, narrow room (7 meters by
about 2 meters) commonly used for photographic purposes. The single
window of this room could conveniently be made light tight, while an
antechamber at the entrance provided against the admission of stray
light at that end of the room. The side walls were of brick, the rough-
ness of which tended to give less definite reflections than smoother
surfaces would have done, and the whole interior of the room was
painted dead black. Furthermore, practically everything in the room.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EVES. 341

which did not from its nature need to be otherwise was painted black
to prevent the reflection of light.

The definite arrangement and relation of the parts of the apparatus
as viewed in vertical elevation may be seen in Figure 1, while Figure 2
shows the horizontal plan. Against the north wall of the room was
placed a large wood-top table (T) ; at the right of this a lamp (>Sw),
giving as nearly as practicable a point of light ; and at the left, at an
e(iual distance from its centre, the apparatus (Lg, Lg') designed to
furnish the larger illuminated area (g). A third lamp ( T) was placed
directly above the middle point of the line joining the other two
lights,^ a line which may be designated as the directive axis (a, Fig-
ure 2).

The lamp giving the small light (Sni) consisted of a wooden box
(22 X 22 X 35 cm.) painted black, and having a Nernst filament ar-
ranged before a small opening in the side facing the table. By this
arrangement a definite and clear-cut luminous area was secured. Since
there was no reflecting surface immediately back of the filament, the
light given off" in that direction traversed the blackened box and was
absorbed by the distant walls, two of which were set at an angle to
each other, as shown in Figure 1, to prevent, as far as possible, reflec-
tion of light.

The filament used on this lamp was the regular 110-volt "single
glower " Nernst filament, which is about 15 mm. long and has a diam-
eter of approximately 1 mm.

The illuminating apparatus (Lg and Lg') furnishing the large light
was more complicated. The lamp proper (Lg) was similar to Sm,
except that two 220-volt " six glower " filaments were used on a circuit
of the strength indicated.*^ The light of these two filaments was many
times stronger than that of the small lamp. In front of the lamp Lg'
was a long box (Lg,) lined throughout with white glazed paper, ex-
cept the end nearer the table, which was closed with a plate of ground
glass (g). The end farthest from the table made an angle of 45° with
the sides of the box (see Figure 2). An opening (o) in the side of the
box near the end farthest from the table admitted the light from the
lamp Lg', which fell at an angle of 45° upon the white paper covering

2 The word " lights " is liere used to designate the luminous areas which fur-
nished the light used in the experiments. In the case of the lamps Sm and I',
these were Xernst filaments used directly ; in the case of Z7 it was a large stjuare
of ground glass illuminated by light from behind. The lamp T'was not used in
the experiments described in the present paper.

3 The 220-volt current was secured by using a transformer on the same (llOr
volt) circuit tiiat supplied the smaller lamp.

342

PROCEEDINGS OF THE AMERICAN ACADEMY.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 343

^

I 1 1
■ I 1

10

^

^

^ o

• ■■ - , CO

= g

^ ..2

.§ ja

throu
small
ically.

; 3 =^

^ s «

"o -i^ ~

•= >

^- ic g

2 "5: i

^ =^ =?

o ^ o
•u ^r-a

=5 ^

S i :/

.£ ~ bp

O X

o s —

5 ^if

•« o

^ ■'■ u

cs S =;

ti; _ -

J- <— —

E o ■"

rt - 3

i<i

c--^ o

'= -B o

C3 a;

.— .^ •♦-»

a

-i 5-3

X

— o

o

o

i -^ '"

S" it 5)

'■^

e " =

— •- <U

2 H ti.

-c^"^

t; fc rt

^- O ft,

i^ O t,

■» c -

^ > a

neral
diap

us area ;
f L(j ; p,
le; F, la

Ge

axis
t/, d',

o o ^

^ ^ ..

C ., CS
— ^ +j

•r -xs 2

^" .^ f •*

CO?

3 50 ?^

rt o o

fc. o

,, Ji .~

rH •-• t-

ti"^ s

'O V

ai - to

^ r- .O

H S _,

a ^ O 60 ;:'- S

c 3 "S .E ■- 'S

P=H "Ev- ■? 5 3

344 PROCEEDINGS OF THE AMERICAN ACADEMY.

the oblique end of the box, and was thus reflected directly toward the
ground glass. The white-paper lining of the sides aided in securing
the desired diffusion of light. In this way a remarkably even illumi-
nation of the large sheet of ground glass was obtained. By means of
a square mat of opaque paper a clear field 41 cm. square was produced,
and this constituted the larger of the two areas of illumination used in
the experiments. The ground glass was first placed with the unground
surface toward the table, but later the ground side was turned in that
direction, in order to avoid the reflection of light from the small lamp
opposite.

The lamp ( P^, sending down vertical rays, was essentially like the
small lamp (Sm), being similarly provided with a single 110-volt fila-
ment. There was arranged in front of it, however, a sliding diaphragm
(not shown in the figure), by means of which the size of the orifice, and
therefore the amount of light coming from it, could be regulated at
will.

The filament of the small lamp (Sm) and the ground glass (g) of the
large lamp (L(j) were each exactly 2 meters from the central point (p)
of the table. For convenience this middle point may be spoken of as
the working point or wot'king posit/on. All light, except that coming
directly from the sources described, was excluded, as far as possible,
from the working position by means of diaphragms (d), screens of
heavy pasteboard or wood (s, s', s"), and black cloth (cs, cs', cs").
The intensity of illumination of the ground-glass surface could now be
easily regulated by varying the distance of the lamp Lg' from the
oblique reflecting surface in the box Lg. With the aid of a Lummer-
Brodhun photometer placed at the working position (;;) it was an easy
matter, by varying the distance from o of the light Lg\ to make the
intensities of the two lights exactly the same.

It is now necessar)'^ to compare the respective areas of the two sources
of illumination. The small filament was 1 mm. in diameter and 15 mm.
long, but at each end was a small knob where the platinum wires were
attached to the filament, and when the latter was at white heat these
glowed as well. Thus the total length of glowing surface was about
17 mm. Since the illuminated surface of the ground glass was 41 cm.
square, as has been stated, its area was 1()8,100 sq. mm. If in the
small lamp we regard the filament only, we shall have an area of
15 sq. mm., and therefore the ratio of the two areas will be that of
11,207 to 1. If, however, the length of the smaller light is considered
as 17 ram., the ratio becomes 9,888 to 1. Since the ratio cannot be
obtained with great accuracy, and the exact proportion is of only minor
importance, we may, for all practical purposes, regard the ratio as
10,000 to 1.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 345

The intensity of the light from either source was found at the end
of the investigations to be only about l.'i") candle meters. There were
two reasons why this intensity was not constant throughout the exper-
iments. In the first place, the voltage appeared at times to be very
inconstant, causing considerable liuctuation in the intensity of the
lights. These fluctuations were usually of sufficient amount to be
noticeable ; but since Iwth lights were on the same circuit, the relative
intensities were but little affected ; however, at such times the lights
were tested with the photometer, in order to make sure that they had
not changed relatively, and that they were still balanced at the work-
ing point. It was found by experience that with small fluctuations
their change in relative intensity was inappreciable, it being only in
cases of considerable fluctuations that it was necessary to make any
readjustment. The other change in intensity was due to a gradual
deterioration of the filaments, and therefore was more constant. The
light intensity employed at the beginning of the investigation was very
close to 5 candle meters, from which, as stated above, it gradually ran
down to as little as 1.25 candle meters in the later experiments. The
whole change from this cause was probably not so great, however,
as sometimes occurred in the temporary fluctuations due to varying
voltage. We seem justified in leaving these comparatively small in-
constancies out of consideration, since it is not probable that they were
of sufficient amount to influence materially the results on any of the
animals used. At most, these differences could probably have made
only a slight difference in the percentage of reactions and none in their
character, since Adams ( : 03) has shown that in the earthworm, for
example, it is only at very low intensities, near the point where the
animal changes from negative responses to positive, that small differ-
ences of intensity have a relatively great effect. At the higher intensi-
ties considerable range in the intensity produces relatively little change
in the percentage of responses. Furthermore, the animals employed in
these experiments were selected for their decided reactions to light of
about the intensity used, and it is probable that in no case where posi-
tive results were obtained was this near the point where these forms
change the character of their response.*

By means of a microspectral photometer the qualities of the two lights

* The common European garden snail {Helix pomatia) was found to be so in-
constant in its responses that it was not suitable for tlie purpose of these inves-
tigations. This may have been because the light used was near the critical
intensity for this species, though it is more probable that the changes in response
depended entirely upon certain physiological states of the animal independent
of the light (see p. 391).

346 PROCEEDINGS OF THE AMERICAN ACADEMY.

were also tested and compared. The differences in the spectral com-
ponents V7ere found to be so slight as to be negligible. A sheet of clear
glass, equal in thickness to the ground glass of the large light, was at
first placed in front of the small light, in order to make the conditions
of the two as similar as possible ; but it was found to be of little use,
and was of such obvious disadvantage, because of the considerable dis-
persal and reflection of the light which it caused, that it was later dis-
pensed with entirely, and consequently is not represented in the figures
. of the apparatus.

The vertical light (F), which has been described, was used only in
connection with the small light (Sm) in studying chiefly the reactions
of animals to lights of equal intensity, but coming from different direc-
tions, — in this case one light striking the animal from directly above,
the other coming to it horizontally. This combination of lights was
also employed in studying the reactions to shadows and to sudden
differences of intensity. These experiments will be described in another
paper.

Other appliances and conveniences will be mentioned in their proper
places. It should be stated here, however, that screens were provided
by means of which the light from any of the lamps could be immedi-
ately shut off from the working position at will.

At the point on the table exactly midway between the lights was
painted a white line, and this may be spoken of as the 7iormal axis of
the apparatus {a', Figure 2), since it is at right angles to the directive
axis already mentioned. At the beginning of each trial in an experi-
ment the subject was usually placed, headed in one direction or the
other, on this line, its long axis coinciding with the line. For the sake
of brevity in description, this is called the normal position. Any line
running parallel to the normal axis — nearer to one light or the other —
may be said to run in a normal direction. The centre of the ivorking
position was at the point where the normal and directive axes crossed,
and the working area included a small horizontal surface, the extent of
which was determined by the distance the animals were allowed to
move. Three concentric circles, the inner with a radius of 5 cm., the
second with a radius of 10 cm., and the outer with a radius of 15 cm.,
were described with their centres at this point. Each of the circles was
divided by short cross lines into arcs of 10°, and by means of this
device the angles at which the animals deviated from the normal axis
and crossed any of the circles could be read directly with ease and
accuracy.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 347

III. Experiments.

As stated in the Introduction, the experiments were undertaken
with the idea of ascertaining, as far as possible, to what extent com-
plexity in the organization of eyes is correlated with the reactions to
luminous areas of difterent size but of equal total luminosity. The
character and relative percentage of phototropic responses were used
as measures of the reactions. The method employed can perhaps
best be explained by an example. Let us suppose that an animal
which is decidedly positive in its ordinary reactions to directive light
is placed midway between two luminous areas of exactly equal shape,
size, and intensity, and in such a position that one light is at its right,
the other at its left. Let us assume, further, that each luminous area
is 1 cm. square, has an intensity of lUO c. p., and is situated at a dis-
tance of 2 meters from the animal. The measure of the light then
impinging upon either side of the subject would be 25 CM. (candle
meters). We should expect one of two results : (1) The animal being
equally stimulated upon both sides would go straight ahead without
turning ; or (2) owing to chance or random movement, it would be-
come turned slightly more towards one light, which would thus have a
more direct effect than the other, and the animal would then continue
crawling towards this light. But since the chance of random movements
in one direction is as great as in the other, the number of times that
the animal would go towards each of the lights should, in a large
number of trials, be equal, and we should have essentially a balanced
condition as before.

Now let us enlarge one of the areas to, say, 100 cm. square, but keep
the total amount of light given by it the same as before. Its area is
now 10,000 times as great as before, and consequently the intensity of
the light radiated from a single square centimeter is now only 0.01 c. p.
The whole amount of light received by the animal is, however, the
same as before, namely, 25 CM. upon each side. If the animal is with-
out image-forming organs, — in other words, without eyes, — it has no
obvious means of appreciating the increase in size of one of the areas,
and we should expect the reactions to be the same as when the lights
were of equal size, that is, the animal would be indifferent. In this
case, the skin (or certain scattered cells in the skin) is the sensitive
surface, and since there is no apparatus for concentrating the light
from the large area, the amount of light received by any point on the
skin on either side of the animal is equal to that received by any other.
This is evident from the fact that light from every one of the 10,000
areas (each a centimeter square) which make up the large area falls

348 PROCEEDINGS OF THE AMERICAN ACADEMY.

upon each point of the surface of the animal ; the intensity of the light
from any single square centimeter of the area is only 0.0025 CM., but
since there are 1(J,000 such radiating squares the total intensity is
25 CM.

In an animal possessing eyes capable of forming good images of ex-
ternal objects the conditions are very different. In this case light from
all parts of the large area cannot fall upon every point in the sensitive
surface (here the retina), but the light from each part of the field re-
tains its position relative to that from other parts, and falling upon the
retina in this order covers there an area similar in shape and relative
intensity of illumination to the external one. Such is the image. The
small light, which we are considering as only 1 cm. square, would
likewise form an image on the retina, and this, with the light at the
given distance, would cover a certain small area, which we may denote
by X. X, then, is the size of the retinal image of a luminous object
1 cm. square at a distance of 2 meters. The light received on this area
would have a certain intensity, which may be designated by y. Now,
since the large light has 10,000 times the area of the smaller one, its
image on the retina (making no allowance for aberration or other optical
defects) would be 10,000 times as large as the image of the small light,
or 10,000 X ; and the intensity on any single area x would be only
iwoo y- It is obvious, therefore, that under these circumstances we
have entirely different conditions of stimulation on the two sides —
that is, in the two eyes — of the animal. On the retina of one eye only
a very small area (.r) is stimulated, but the light has a considerable
intensity, which we have called y. The retina of the other eye is
stimulated over a much larger area (10,000 x), but each area (.r) re-
ceives in this case a light intensity of only towo y-

This is of course only an approximation to the relative influence of
the two sources of illumination. It is probable that even in the most
highly organized eyes, owing to aberration and other defects, the actual
conditions are far from those here assumed. It must be remembered,
furthermore, that fropa a physiological standpoint the retina cannot be
accurately divided into areas, such as we have assumed ,r to be, corre-
sponding to external areas, but that its physiological action, as well as
its finer structure, must be considered in terms of visual elements —
the ommatidia in the compound eye, the rods and cones in the verte-
brate eye. The matter is further complicated by the fact that these
visual elements may not have a uniform distribution over the whole ret-
ina, nor do we know that those of different parts of the organ are equally
sensitive to light stimulation.

In spite of these defects and deviations from the suppositional case,

COLE. — IMAGE- FORMING POWERS OF VARIOUS TYPES OF EYES. 349

we are safe in assuming (1) that the image of the larger light is spread
over a larger area on the retina, or better, that a larger number of vis-
ual elements receive light, and (2) that the intensity of the stinndus act-
ing on any one visual element is very much less than that which acts
on the one element, or very few elements, which are stimulated by the
small light. Analogy with the reception of stimuli by sense organs in
general makes the assumption reasonable that the difference between
even a very weak light and no light falling on a visual element may
have a much more stimulating effect upon the animal than the same,
or even a greater, difference in the amount of the light at higher inten-
sities. Such being the case, we should expect an animal to react more
strongly to that stimulus which fell upon the larger number of visual
elements — that an animal normally positive, for example, would be
more strongly positive to the large light than to the small, and similarly
that a negative animal would tend more often to move away fi-om the
larger than from the smaller luminous area. Parker's ( : 03) results give
evidence that in Vanessa such is really the case. In the following pages
are recorded the results of experiments made under more uniform and
more precisely determined conditions upon a variety of animals, some
negative and others positive, some with eyes and others without.

The kinds of animals experimented upon were not taken entirely at
random, but species whose reactions to a single light were definite and
well known were selected as far as possible. The number of animals
from which selection could be made was greatly limited owing to the
optical dilficulties with animals living in water. Only those were used,
consequently, which could be studied in the air. In addition to the
animals Avith Avhich a considerable series of experiments was finally
made, a large variety of animals were tested in a more or less complete
manner, to determine their suitability for the work. These included a
number of insects, such as the water strider (Hygrotrechus), an elater,
a small species of cockroach, and certain kinds of bees and flies, sev-
eral myriapods and spiders, the European slug {Limax maximus), the
horned toad (Phrynosoma), and two species of salamanders {Plrthodon
(jhitiwmm and P. er)ithronotii^). Some of these did not appear from
their movements to be responsive to light, others were inconstant in
their responses, and still others were too inactive for the purposes
of this work. Those from which more or less satisfactory data were
obtained are as follows : 1. The common dungworm or earthworm
{Alhihihophom foet'ida [Sav.]). 2. A large land planarian (yy/)w//«w
l-eireuse Moseley). 3. The mealworm (larva of Tenehrio molitor Linn.).
4. The sow bug (Oniscu.t a.<f^/lns Linn.). 5. The cockroach {Periphnn^ta
americana Linn.). 6. The mourning-cloak butterfly {Vanessa anti-

350 PROCEEDINGS OF THE AMERICAN ACADEMY.

opa Linn.). 7. The water scorpion {Banatra fusca Pal. B.). 8. The
pomace fly {Drosophila ampelophila Loew). 9. The common garden
snail of Europe {Helix pomatla Linn.). 10. The cricket frog {Acris
gryllus Le Conte), and the green frog [Tiana clamata Daudin).

Below are set forth the results of the experiments on these animals
in the order given above. The statement of results is followed by a
discussion of their significance.

1. Earthworm {Allolobophora foetida\^d,Y.'[).

In connection with observations upon the reactions of a series of
animals having eyes of different kinds and of varying degrees of com-
plexity, it seemed desirable, for the sake of comparison, to make similar
observations upon a form without eyes. Of all the forms available, the
earthworm appeared to be the best suited to this purpose. A number
of observers have worked with earthworms of various genera, so that
their behavior in relation to light is better known than that of many
other animals. Although there appear to be differences in the degree
of sensitiveness of different species, the behavior of the several kinds
that have been studied seems to be essentially the same.

That earthworms ordinarily respond negatively to light of moderate
intensities was early remarked by Hoffmeister ('45), and subsequently
by Darwin ('81), and has been abundantly confirmed by all later
workers. For the purpose of the present investigation it was sufficient
that the worms react in this manner in a large percentage of cases,
and that they lack eyes, — that is, any organs for focussing the light
upon special sense cells. The fact that they possess such special cells
as the so-called light cells, — demonstrated by Hesse (96) and shown
for Perichaeta by Harper (:05), — has no bearing in this connection,
since there is no contrivance for concentrating the light upon these
structures. Nor does it matter that the animal is sensitive upon all
parts of its body, though to a different degree in the different regions, as
shown by Parker and Arkin (:01). Indeed, it is unimportant to know
in what manner the reaction is brought about ; whether it is a direct
response, in the sense of the tropism theory, or a result of trial and
error, as maintained by Holmes (:05) and confirmed for moderate in-
tensities of Hght by Harper (:05), since the problem is merely to deter-
mine, as indicated by the direction in which the animal moves, whether
it is more strongly stimulated -upon one side than u})on the other.

Method of E.rper'niwntation. The luminous areas, as previously ex-
plained, were fixed, one at the left and one at the right of the experi-
mentation table. Earthworms in good condition, which had previously

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 351

been kept in the dark, were tested, each in its turn, first, with the lights
separately, and then with both acting at the same time. In each ex-
periment the worm was placed in the normal position, — that is, with
its long axis at right angles to the rays of light (see p. 346), — and al-
lowed to crawl a distance of 15 cm., i. e., until its anterior end crossed
the outer circle marked on the table (see p. 346, and Figure 2, p. 34.S).
The course and the angle at which the worm crossed the circle were
immediately recorded on blank diagrams differing from the table dia-
grams only in the absence of one of the three circles. These circles
were divided, as on the table diagram, into arcs of 10° each. When
the worm had been tested five times with the head started in one direc-
tion, it was then tested an equal number of times with the head started
in the opposite direction. Experiments of this kind and number were
made in succession with
five different worms, such
experiments — 50 in num-
ber — constituting a set.
Three such sets of experi-
ments were made, and they
may be designated as A , B,
and C respectively. Sets
B and G were performed
under precisely similar con-
ditions, and may be consid-
ered together ; in set A
the conditions differed from
those of sets B and C only
in the method of starting
the worm. This method

proved to be much less satisfactory than the one employed in sets
B and C.

In the experiments of set A, a ground-glass plate (Figure 3, P) was
placed on the diagram on the table, and the worm was allowed to crawl
on the roughened glass surface. The plate was kept moist by the
frequent use of a damp sponge, and when thus moistened was suflft-
ciently transparent to show the circles and radii on the table below.
Two strips of thick glass (.s, s') — made opaque by being painted, except
"where the worm was to come in contact with them — were placed par-
allel to the normal axis, with one of their ends at the directive axis,
and with a space between them only a little wider than the diameter
of the worm's body. This formed a trough, or runway, in which the
worm was placed and allowed to start crawling, whereupon a third

■M^;^-^}'^^^mS^W^^M

Figure 3. Apparatus used in earlier experi-
ments witli earthirorin : P, ground-glass plate;
s, s', small glass strips forming runway.

352 PROCEEDINGS OF THE AMERICAN ACADEMY.

piece of glass was used to cover the runway. Thus, when the worm
emerged from the end of the runway, its anterior end projecting out, it
was subjected to the lights in the desired mamner. To start the worm
headed in the opposite direction, the glass strips were moved on the
plate to a similar position on the other side of the directive axis.

The results of 50 trials made in this way under each condition of
illumination were as follows :

a. Response to small light alone. In 50 trials the animal turned
43 times away from the light (— reactions) and 7 times toward it
(+ reactions). This gives an excess of 36 responses away from the
light, or 72 per cent of the whole number. This may be taken as a,
measure of the negative phototropism of the worm under the given
conditions {cf. Parker and Arkin, :oi, p. 153).

b. Response to large light alone. Out of 50 responses 3 were
toward the light (+), 44 away from the light (— ), and 3 straight ahead,
or indifferent. The excess away from the light was 41, or 82 per cent.

c. Response to simultaneous influence of both lights. Out of 50
trials 31 resulted in a turning towards the large light, 15 towards the
small hght, and 4 were indifferent. Here there is an excess of 16 re-
actions, or 32 per cent, away from the small light and towards the
large.

This result is far from what would be expected in the case of an
eyeless animal. One would suppose, since, when both lights are used,
the amount of light striking the worm on each side is the same, that
the responses in each direction would be much more nearly equal in
number. Another noticeable fact is the high percentage of negative
reactions when only a single light was used. The highest average of
negative responses obtained by Adams (-.03) was 59 per cent. This
was observed with a light of 48 CM. intensity at the point where the
worms were placed.^

In this set of experiments no mention has hitherto been made of the
angle at which the worms turned. It was found upon an inspection of
the records that in fully a third of all the trials made the animals upon
leaving the runway had turned at an angle of 90°, confirming the sus-
picion awakened by watching them, that their natural thigmotactic
response caused them in a large number of cases to turn sharply and
follow the ends of the strips of glass. For the same reason they also

^ It should be borne in iniml tliat tlie present results are not strietly com-
parable with those of I'arker and Arkin or of Adams, sinee those invcstii^ators
recorded all definite head movements (i e., erawliim' ninveuK'nts), while in these
experiments the direction of the turning in an excursion of 13 cm. is used.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 353

appeared very reluctant to leave the runway, often drawing back com-
pletely after the anterior end had been extended a centimeter or two.
It was only by stimulating such individuals at the posterior end that
they could be induced to continue crawling.

As it seemed possible that the factor of thigmotaxis might have
vitiated in large measure the results, the second and third sets of
experiments {B, Cf) were made under somewhat different conditions.
The ground-glass plate, instead of being laid upon the table, was sus-
pended about 2 cm. above it by means of strings leading upward to a
common point, and thence to the ceiling in much the manner devised
by Parker and Arkin (:oi, p. 1 ol). In this way the horizontal position

Figure 4. Apparatus used in later experiments witli eart/nconn, and with
the land planarian, menhcorm, snail, and slug, d, d', diaphragms or screens of
heavy pasteboard ; P, ground-glass plate ; v, worm.

of the plate was maintained, but it could be moved in any direction in
a practically horizontal plane, and could be rotated freely about its
vertical axis. The worm could now be allowed to crawl freely on the
glass plate. By means of the opaque screens d and d' (Figure 4), it was
kept out of the iufl lence of the light until it had straightened out and
was moving well, whereupon, by revolving the plate if necessary, and
moving it horizontally in the right direction, the worm {u-) could be
brought into the normal position, with its anterior end projecting about
a centimeter beyond the directive axis, i. e., into the lighted area. In
this way it crawled out into the lighted area at right angles to the
direction of the rays of light, and without the disturbing thigmotactic
influence of the sides of the glass runway existing in the previous
experiments. "When once in position, the glass plate was held station-
voL. xm. — 23

354

PROCEEDINGS OF THE AMERICAN ACADEMY.

ary until the worm had crawled to the outer circle marked on the table,
a distance of 15 cm. When it was desired to test the worm headed in
the opposite direction, it was only necessary to shift the screens d and
(V to the other side of the directive axis. This arrangement proved
to be much more satisfactory than the one first employed, the results
being free from the disturbing factor of thigmotaxis.

Animal i?.. _

(4)

Time _

A^ ■"

Distance ._ ;^^/<<:>»t..:

2,

it

Tt"^

^^

/\\ ^

\\

/\ ^

/X\\\

w

/^3

^\^s>\

^-

</^y{

^c^^^\\>^

>^

/'^^^'

0

1/ ^

If y^

F^i3

■<s^

^:

' x/yV/

7r

\\ /^'2

rAV/ /

//

\\>^3

I4\,/ /

' /

^X4

15^^

/

^

MAY 11 1903 "^

-nK

8 "

A. foetida

Figure 5. Record of five successive trials with an earthworm exposed to the
influence of the large area of illumination and headed away from the observer.
For fuller explanation see text.

The difference in the results in these two cases emphasizes the im-
portance, in work of this nature, of bearing in mind and eliminating, as
far as possible, all extraneous influences.

Before describing these experiments and their results, it may be
well to describe in some detail the methods employed in keeping the
records, since the same description will apply in the case of most of
the animals studied. Figure 5 shows a record of five successive trials
with a single worm, — in this case exposed to the influence of only
one light (the one having the larger area), which was situated at the

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 855

left. The worm is in all five cases headed away from the observer.
It will be noticed that the circles on this printed blank are divided
into divisions of 10° each, corresponding to the divisions of the circles
on the table, so that it was an easy matter to plot the path of the
crawling worm with considerable accuracy. The successive trials were
numbered in the order in which they were made, from one to five.
When the animals were headed in the opposite direction (toward the
observer), similar blanks were used, but the zero point of the transverse,
or normal, axis of the circles was the near end, not the far end. By
this device the relation of the lights to the diagram is kept always the
same ; the large light being at the left, the small light at the right.

In giving numerical value to the angles at which the outer circle
was crossed, the readings were, for convenience, grouped into as many
classes as there were divisions of the circle. Each class was designated
by one of the numbers, 0 to IS, and embraced all the records falling
within 5° of the radius bearing the corresponding number. Its nature
was further indicated by Lg or Sm, according as the radius in question
lay on the side of the normal axis toward the large light or toward
the small one. The dividing lines (radii) shown on the diagram there-
fore fall in the middle of their respective classes ; thus, for example,
the radius numbered 2, which marks a point 20° from the normal axis,
is in the middle of class Lg 2, or Sm 2, as the case may be, and all cross-
ings between 15° and 25° fall in this class. Crossings which happen
to lie exactly midway between the lines numbered on the diagram are
always put into the class which lies next to the right of the point of
crossing ; in other words, in the direction toward which the hands of
a clock move. Thus a reading falling midway between 5 (50°) and
4 (40°) on the Lg side of the vertical would be put into class Lg 4f, if
it fell in a corresponding position on the Sm side of the vertical, it
would be included in class Sm 5. When to the readings for an animal
headed away from the observer are added those for the same animal
headed in the opposite direction, — the latter would lie in the lower
half of the circle, — the possible error resulting from this method of
recording is counterbalanced and the effect thus eliminated.

From what has been said it can be seen at a glance that the five
readings shown in the illustrative figure (Figure 5) fell into the follow-
ing classes : one in class 0 ; one in class Sm 1 ; one in class Sm 3 ;
and two in class Sm 5.

Something must be said with regard to the disposition to be made
of those cases in which the worm turned more than 90°, and so crossed
the circle at some point in the dark half of the field. There are three
possible ways in which these cases might be treated. Either (1) ig-

356 PKOCEEDINGS OF THE AMERICAN ACADEMY.

nore the response, (2) recognize as many classes in the dark field as in
the light one, or (3) regard the response as equivalent to that of an
animal crossing the circle in the light field at an equal distance from
the directive axis. To ignore the response would obviously give un-
satisfactory results, for such animals certainly exhibit strong responses
either toward or from a given light. To create of them separate
classes would also be undesirable, for the records should express the
degree to which the worm turned from the normal, or, putting it the
other way about, how closely it came into orientation in line with
the axis of the lights. Since 90° (class 9) represents the extreme possi-
bility of turning from the normal axis, the creation of further classes for
crossings in the dark field would be misleading. The third possibility
is obviously the one to be adopted. Thus, if an animal turned so far
as to pass over the line at the point 13 on the side toward the small
light, the trial was recorded in class Sm 5.

After the foregoing explanation the accompanying table (Table I)
will be easily understood. This gives the results of 100 trials made
with 10 individuals exposed to unilateral illumination, in this case to the
large light. The 19 vertical columns, numbered each way beginning
with 0 and going to 9, correspond to the classes described above. The
individual numbered 3 (marked with an asterisk) is the same one that
is represented in Figure 5. In the columns next beyond columns 9 are
recorded the total number of crossings made on the Lg side of the 0
class and on the Sm side of that class, while in the columns next be-
yond these are indicated the number by which one of these exceeds
the other. From this it can be seen at a glance that when the worms
were headed away fi'om the observer (left side to light), they
crawled only 4 times toward the light (+ responses), 38 times aAvay
from the light (—responses), and 8 times straight ahead' (indifferent
responses). Thus there is an excess of 34 trials on the side of Sm.
The records for the worms headed in the opposite direction (right side
to light) are not so striking. These are: toward Lg, 17 ; toward
Sm, 26 ; indifferent, 7, giving an excess of only 9 toward Sm. Add-
ing these two sets together, we have : Lg{+), 21 ; Sm. (— ), 04 ; 0 ( + ),
15 ; excess in favor of Sm, 43. Since 100 trials were made altogether,
43 per cent may be taken as an index of the negative response of
Allolohophora foetida to the large light alone under the conditions of
the experiments.

The results of 100 trials under each of the three conditions, large
light only, small light only, and both lights simultaneously, are sum-
marized in Table II. The general arrangement of the data is similar
to that in Table I, except that the details of individual reactions

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 357

S

f7

s

K

s

O

a:

Z
O

o

CO

Ci

CO

■tits 01

mox

iO'«*<Tj<coTtieooo>o>o

00
CO

-

CO CO lO lO lO rH CO

s

CO

Oi

.

. .

'

00

.

. .

'

.

t-

-

1— 1

1-H

CO

CO

o

1—4

I— I r— )

CO

i-H rl

(M

uO

lO

rH

<N

T-H

i-i(M

t-

1-^

• ■

rH

CO

T)<

* t— <

r— t r— <

r— t—H

lO

t-H 1 — 1

r- rH

I-H

o

o

r-1

M

■ ^ __ __ ^^ -

I— 1

CO

• rH

COrH

r-i

so

rH

!■>

■^ *— 1 * T— 1 CM T-H t— t

.

o

T-H

•rH(jq

rH

1—*

«o

CO

r-t

-

^^

• T— 1

t— 1

Tt*

.

1—*

CO

rH r^

o

O
rH

o

• 1-H 1— «

• ?^

••*

00

coco

■ •

• rH

r-

rH

.

.

' rH

' rH

<M

<M

IN

r-*

1— 1

rH 1 (M C^ rH

' rH

t-

CO

«

-

rH

IM

■

>

CO

-*

•^

-H

f-H

•

rH

.

f-i

(^^

O

05

r-H

CO

CO

o

•

t-

.

•

co

-

rH

I

rH

r-^

•^

o

• ■

•

•

'

•

■B'J 01

S<J rH

»— 1

'*

rH (MlO^^iyj

COC^

rH

rH

ssaoxa

• •

.

• ■

•

IBnpiAipni

r-i(MC0rt<OOl~XC;O

•

rH C<I CO -^ i-O U5 t^ CO C2 O 1 ■

.

Headed

away

from
observer

(left

side
to

ligiit).

13
o

Headed

toward

observer

(right

side

to

light).

3

o

Total, both
positions

358

PROCEEDINGS OF THE AMERICAN ACADEMY.

have been omitted. For the sake of brevity the worms are spoken of" as
"headed north" or "headed south," in place of "headed away from
observer," and " headed toward observer," respectively.

The first of these sets of records — that resulting from the use of

the large light alone — has
9 8 7 0 5 4 3 2 1 fi 1 2 3 4 5 r, 7 8 0 j ust been discusscd in com-

-r-r-r-T-n menting on Table I. The
per cent of negative reac-
tions to the S7na/l light
alone is even larger than
that to the large light alone.
It will be noted that the
worms turned 68 times to
Lg (— ) and only 12 times
to Sm (+), making an ex-
cess of 56 times, or 56 per
14 cent, away from the light.
In the case of both lights,
however, the records in the
two directions nearly bal-
ance. They read: to Lg,
40 ; to Sm 41 ; indifferent
19. This leaves an excess
of only one record, or 1 per
cent of the whole, in favor
of the side toward the
small light.

By regarding merely the
total number of crossings
at one side or the other
of the normal, no account
is taken of the degree of
divergence from that line.
This, however, is shown
within limits of 10° by the
segregation of the records
into classes, as shown in the
tables ; but it may be more quickly perceived by the use of a graphic
method — by plotting the records in the form of frequency polygons,
as seen in Figure 6. Along the abscissae are laid off 19 divisions, cor-
responding to the 19 classes, as in the tables. Here, too, the relative
positions of the lights are always the same — the large light at the

Figure 6. Frequency polygon showing the
distribution of reactions of the earthworm to {A)
the large light alone, (B) the small light alone,
and (C) both liglits used simultaneously (100
trials under each condition).

COLE. — IMAGE-FORMING POAVERS OF VARIOUS TYPES OF EYES. 359

P
O
H

-«!
Q

09

s
o

u
o

o

■<
W

o -r

►J -ts

c S

i-i t-3 O

1-3 2

a; -^

O -2

H

'C

S5 _

9 ?-

O

o
o

o

o

00

S5

O

■<

Excess
to Sm.

CO

CO

■

•

t^

I— <

-3 S
HO

CO o

CO (N

«o cc

?2

TH

tn

■<
.J

C3

: 1

00

•

.

I'

0?

CO

<o

M (N

\o

I-I 1—1

(M

lO

t- >-i

CO

(M .-1

CO

Tt<

O lO

o

1-H

•-H

I-I

(M Tl<

CO

M

o o

(M

1-H

I-I

CO CO

a>

C)

s «

CO

.-1 C^

•*

IM t^

Ci

tH

■«* «o

o

CO c^

o

t^ lO

I— t

o

CO t~

l-H

o c

o

(N

2 o

C.

I— "

'~'

'. ^

iM

CO >5

CO

t^ lO

S^

(N

r-c t^

CO

<© «

22

•<*( CO

t^

CO

,-1 CO

•^

C5 <£

S

■* -<J<

00

■*

r-1 i-H

(N

»o «

:2

■^ CO

t^

lO

! CO

CO

t- a

2

I-H 1-H

(M

o

: : 1 :

^ ,-

<N

t— t I-H

(M

t~

.

T—* r—

<M

(M ]

(N

00

r^ r-t

s^

<M

<M

.

•

C5 ■ ■

•

'

.

•

H2

I-H

CO C^

00

CO t^
(N I-I

o

0}

a: <

•

00 X

O

2"^

i i

•

.

^5 =

ii

ci
1-3

"5

n
s

(73

o

C-l

o

4-*

o

860 PROCEEDINGS OF THE AMERICAN ACADEMY.

left, the small at the right. The number of responses falling in each
class are recorded on the corresponding ordinates. In the first poly-
gon (Figure G, A) are represented the experiments with the large
light alone (as recorded in Table II), where, it will be noticed, the
polygon lies mainly on the side away from the light ; similarly the
second polygon (Figure 6, B) lies chiefly on the side away from
the small light, which was alone used in this case. The third figure
(Figure 6, C) represents the data when both lights were used, and is
remarkably symmetrical, with its mode at 0. This indicates a con-
dition as nearly balanced as could well be expected.

These results on the earthworm would appear to admit of only one
interpretation, namely, that the intensity of the light is the controlling
factor in its reactions and not the size of the field from which the
light is derived. The latter, in fact, appears to have no influence
whatever. This is in exact accordance with what would be expected
in the case of an eyeless animal. It possesses no organs so difieren-
tiated as to be able to discriminate space relations in objects beyond
its touch ; there is no mechanism for preserving these relations in
space, as the light from the difierent parts of the object falls upon the
sensitive portion of the animal, and consequently there is no sug-
gestion of image formation. The light stimulates according to its in-
tensity only, and since the intensity is the same on each side, the
animal responds by approximately an equal number of deviations in
each direction.^ It may be asked why, if the amount of stimulation
on the two sides is balanced, the worm does not always crawl in a
straight line, deviating neither one way nor the other, and always
cross the circle so as to fall in the 0 class. This is probably for
the same reasons that with unilateral illumination the worms do not
uniformly turn away from the light. Similarly Parker and Arkin
(:0l) pointed out that in their experiments only 30.2 per cent of the
"head movements " were away from the light, 65.6 per cent being
straight ahead and 4.2 per cent toward the light. These authors at-
tributed the movements toward the light to the uneven surface of
the paper on which the worms were allowed to crawl, and to other
disturbing influences. In view of Harper's recent work (:05), it
would seem that conditions of uneven or one-sided expansion or con-
traction of the animal might have some influence in producing these

^ Loeb (: 05, p. 2, footnote) maintains that "if two sources of light of equal
intensity and distance act simultaneously upon a heliotropic animal, tlie animal
puts its median plane at riyht anjiles to the line connecting the two sources of
light." This statement needs a number of qualifications.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 361

results, by exposing the deep-lying cells — which are supposed to be
the organs stimulated — unequally to the light. Undoubtedly, too,
these animals are not the simple mechanisms that we are often inclined
to consider them, but are subject to certain internal conditions —
physiological states, if we care to call them so — which are beyond
our observation and control, and by their changes produce corre-
sponding irregularities in the results. On this account it is important
to use animals for experimentation that have previously been sub-
jected for a considerable period to constant conditions.

2. Land Planarian {BipaVmm keicense Moseley).

The so-called eyes of planarians are remarkably uniform throughout
the group in general plan of construction. Each consists of one to
several sense elements, or cells, backed by a pigmented cup, which is
in turn composed of one or a few cells. These eyes have no appa-
ratus for the formation of an image, but are constructed in such a way
that generally light fi-om only one direction can affect a single eye at
a given time. For this reason they are often spoken of as directum
eyes. In the genera Planaria, Dendrocoelum, and related forms, only
two eyes are present; but in others, such as Polycelis and the laud
planarians, eyes may be present in great numbers.

Bipaliinn is a well-known genus, comprising a large number of spe-
cies, mostly indigenous to Japan, China, India, Ceylon, and the Malay
Archipelago. There is well established in certain greenhouses in Cam-
bridge a species, the original home of which is unknown. This species
was first described by Moseley (78) from a specimen obtained in the
Kew Gardens, England, and was named by him BipaUiim keivense.
Since that time it has been found in hothouses in widely separated
localities in nearly all parts of the globe, and it is generally believed
to have been unintentionally distributed with consignments of plants,
either from its original home or from other places where it had become
established. Woodworth ('96) reported it from Cambridge, Mass., in
1896. A form described from Landsdowne, Pa., by Sharp ('91) as
Bipalium manubriatum is probably the same species ; and Wood-
worth (^98) has since reported it from other localities in the United
States (Baltimore, Md., Pittsburg and Allegheny, Pa., and Spring-
field, Ohio).

Bipalium keivense is the largest of the land planarians, the speci-
mens ordinarily ranging from 12 cm. or 13 cm. to 25 cm. in length;
and Woodworth ('96) records one 30 cm. long. These measurements
are those of the worm in the extended condition, which is assumed in

362 PEOCEEDINGS OF THE AMERICAN ACADEMY.

crawling. The body is capable of great contraction, so that a worm
which is, when crawling, 25 cm. long, may contract to a length of only 5
or 6 cm. (see figures given by Bell, '86, pi. 18). The head when ex-
tended is semilunar, or shaped like a battle-axe (see Figure U, p. 364),
and is about twice as broad as the body immediately behind it. The
eyes have been described in other species of Bipalium by Moseley
('74, p 144) and in B. kewense by Bergendal ('87) and Janichen ('96,
p. 275; Taf 10, Figur 18; Taf 11, Figur 21). Bergendal ('87, p. 4it)
describes the position and arrangement of the eyes as follows : " Eyes
occur in this species in enormous numbers. They form a zone of three
or four rows near the margin of the head, and are also placed on the
sides (not on the back) of the whole body, even to the hindmost end."
The largest eyes are on the head and immediately behind it, and they
are closer together in those regions than on the body farther back.
According to Janichen ('96, p. 27G), each pigment cup has the form of
a hollow hemisphere, the convex side of which is turned inward, while
the flat side, which is open, is directed outward. The pigment spot,
which forms the background of the sensory cells, is composed of a sin-
gle cell. From three to six flattened sense cells lie in the pigment cup,
and, as in Polycelis, the eyes farther posteriorly are not only smaller,
but usually have a smaller number of sense cells.

Hesse ('97) has discussed from a theoretical standpoint the manner
in which the eyes of planarians probably function. He deals in this
case with those forms which possess only two eyes. The diagrams
which he gives ('97, p. 575) are reproduced in Figure 7, and require
only a brief explanation. When there is only a single sense cell in the
pigment cup, it may be stimulated by light coming from various
angles, covering a considerable range, that is, by any light which is
able to enter the cup. Thus the effect would be the same in the left
of the two eyes represented in the diagram for light coming in any of
the directions shown by the arrows in A, B, C, or D. If, however,
there were a number of sense cells in the cup, only a part of these
would be reached by the light coming from any one of the directions
shown, and the light would strike different cells according to the direc-
tion from which it came. In the first case, the structure of the eye
would not furnish any opportunity for determining the direction of the
light within the range of the arrows in A to D ; in the second case it
would, since under the conditions shown in A the cells on one side of
the cup (posterior) would receive the light, whereas in J) those of the
other side would receive it. This condition may be considered as the
beginning of a crude image-forming apparatus, the eye approximating
in a rough way the concave mosaic type. These are theoretical deduc-

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 3(33

tions from the anatomical conditions ; no test has been made to show
whether the physiological action supports the hypothesis. The eyes
of Bipalium are so small, and their axes so variously directed, that it
seems doubtful if the individual eyes can have more than a very gen-
eral directive function in the reception of light. Although in general
they open directly outward, — as mentioned by Jilnichen ('96), and as
may be seen in the photograph of a portion of the border of the head

A

I I

^

C

x>

/.

Figure 7. Various illuminations of the i>hmnriiin eye with light coming from
different directions. The optic cups are drawn too large in proportion to the
size of the liead. The arrows indicate the direction of the light ; the portions of
the interior of the cup not reached by the light are shaded. — From Hesse, '97.

reproduced in Figure 8, — they are nevertheless not all accurately
oriented in that way ; furthermore, the position and direction of each
eye naturally varies with the movements and contractions of the ani-
mal. In general, however, they do open outward, as is represented
diagrammatically in Figure 9. It will be noticed that the eyes of any
particular region are so arranged that they usually receive light exclu-
sively from a direction normal to that part of the surface of the head
beneath which they lie, as indicated by the arrows. The efficiency of

364 PROCEEDINGS OF THE AMERICAN ACADEMY.

this arrangement is greatly increased by the lateral extension of the

Figure 8. riiotoiuieroyrapli of a portion of the margin of tlie head of Bipa-
liuin, showing the position antl arrangement of the eyes. X 70.

head, which allows room for a greatly increased number of eyes in its
anterior border. Taken as a whole, this arrangement might be roughly

compared to a single convex mo-
saic eye, such as is found, for
example, in the Entomostraca.

Below are described the re-
sults of physiological tests with
lights of different sizes, in an
attempt to determine in how far
the eyes may act in this way.

It is a well-known fact that
most planarians avoid the light
(the exceptions being certain
chlorophyll-bearing forms), and
they have long been used for
work in phototropisra. Bipa-
lium appears never to have been
used for experimental purposes,
although the fact that the land
planarians share with the water
inha1)iting forms aversion to
light was remarked upon more
than sixty years ago by Darwin ( '44). That they are also nocturnal
in their habits has been commented upon by various authors since that

riGDRE 0. Diagram of tlie head of Bl-
paliitin, to sliow how light coming from
different directions (indicated by the ar-
rows) may alfect only certain of the eyes.

COLE. — IMAGE-FORxMOG POWERS OF VARIOUS TYPES OF EYES. 365

time. Bell ("86, p. lO.s) remarks that "There can be no doubt as to
the sensitiveness of Bipalium to light," but he referred only to what
he supposed was the eft'ect of strong light in causing the worm to break
up into a number of pieces, and not to the directive action of the light.
As a matter of fact, Bipalium hirense is exceedingly sensitive to light,
of even a very low intensity, falling upon it fr-om the side, and responds
immediately by turning away from the light. For this reason, and
because it is easy to keep and to handle, it is an excellent animal for
experimental purposes. Like most planarians, it creeps with an even,
gliding motion, the head being slightly raised and waved to right and
left, apparently in searching movements, as the worm crawls forward.
In the daytime this Bipalium is usually to be found coiled up under-
neath flower pots which sit on the ground in warm, moist rooms of
greenhouses ; and it is probable that it comes out and moves around
only at night. What it eats appears not to be known with certainty,
but the common opinion seems to be that, like other turbellarians, it is
carnivorous. Some of the related forms are known to eat earthworms,
and certain authors believe the same to be true of Bipalium Jceivense.

Description of Experiments. The experiments on Bipalium were
conducted in the same manner as those on the earthworm, except that
the ground glass on which the animals were placed was supported
about 1 cm. above the table by means of small wooden blocks, or feet,
glued to the under surface of the glass at its four corners, instead of
being swung free by strings from the ceiling. By lifting the plate very
slightly, it could be turned easily in any direction. This had the ad-
vantage that when the worm was once in the proper position, the wooden
feet could be brought in contact with the table again, the plate thus re-
maining perfectly steady and horizontal. When the worm was creeping
well in the shaded area, the plate was moved so that about 5 mm. of
the anterior end of the worm was brought out, in the normal posi-
tion, into the influence of the light, and the record was taken when the
animal's head reached the fin^t circle, instead of the third, as in the
case of the earthworm. It thus crawled a distance of only 4.5 cm. at
each trial ; but the reactions of Bipalium are usually so immediate and
definite that this distance seemed sufficient for the purpose of the
experiment.

The results of 10 trials each, with 10 worms (100 trials in all), when
both lights were operative, are shown in Table III. It will be noticed
that more than half of the 100 trials fall in the 0 class, and that only
a single record falls more than two classes to right or left of that posi-
tion. This means that in only one in.stance did a worm deviate more
than 25^ from the normal axis, thus showing a remakably well bal-

366

PROCEEDINGS OF THE AMERICAN ACADEMY.

lanced condition of all stimuli. The excess of responses towards Sm
over those towards Lg is, however, comparatively large, being 1 7 per
cent. The real nature of the results, with the conspicuous "mode"
at 0, may be more readily appreciated when the data are plotted ia
a frequency polygon, as has been done in Figure 10. These results
indicate that Bipalium has, to a slight extent, the ability to appreciate
differences in area, since it responds by turning away from the larger
luminous area more often than fi'om the smaller. It is possible that
a considerably larger area, even though the total amount of light were
no greater, might have a more decided effect. If the arrangement of
the eyes around the circumference of the head acts, as has been sug-
gested, in a manner similar to a single so-called mosaic eye, forming
roughly what Exner terms an apposition image, it can be seen that

9

8

7

G 5 4 3

o

1 0

1

O

4

5

G '

• 8

9

CO

r

T

III!

T

■| ■;-

T

T

T

T

-r

1

i ■■!

CO

55

-

i

55

50

-

A

50

45

-

M

45

40

-

\

\

"*

40

35

Lfl 30

:

3J

30 S^n

25

-

1 1

\

25

20

-

i

\

20

15

—

i

\

15

10

-

; i

\

10

5

-

y

/ \

V

5

0

L_

-l_

I 1 I 1^

4.

f '

_L

_L

:a=

=J.

_L

1

1 1

0

9 S

C 5 4

1 0 1

(J 7 8 9

Figure 10. Frequency polygon constructed from tlie results with Bipalium
shown in Table III (100 trials to both lights used simultaneously).

light must come from rather widely different directions in order to
enter an appreciably larger number of the cups than would be affected
by light from a single point. This is owing to the comparatively
large semicircle of the head and the irregularity in arrangement of
the pigmented cups, as well as to their shallowness and their great
distance apart, as compared with the ommatidia of, e. g., an insect's
eye. It is not suprising, then, that light from the different parts of
a field only 41 cm. across and 2 meters away (the most extreme rays
making with each other an angle of only about 12°) produces little
noticeable effect in the reactions of such a worm.

After the above set of experiments had been made it was found
that a disturbing factor had influenced some of the work with Bi-
palium. This factor was a light draught of air sweeping the table

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 3G7

1-3

pa

<

« -

oQ ;::

£:?

-* CO 1 t- 1

X ^

I-< 1 T-l 1

w2

1

.

H o

CC t

o

t" . ^

- :o

■*J

o

: 1 :

00

1-

!0

. 1

'■ i :

-(•

; ! :

n

CO

T-H

f-H

a

a

(N

T-l «

Tl<

t-J

I-l ■<»

\a

s

,

T-* —

■>\

c

H

to

CO

o

00 o:

Q

H

«

50 ■»»■

o

t

•^

M

CO

CO

s

,

•^

C<5

:2

■*

cq

b

<s

O
n

t-

S

1

o

H

00

o

^

m

14"

O •ti

CO

o .

H =

<E •

I tl

£^

.

,

X o

K-"

^

•

s-

OO •

^

4^

■£S

o

;3 "

K

o

*"

from left to right ; it came from a
ventilator in the south wall of the
room, which was sometimes open,
sometimes closed. No record was
made as to whether it was open or
closed when the above experiments
were made ; but in the light of
subsequent experiments made to
test the effects of the draught the
records themselves seem to show
that it must have been closed.
This appears from the fact that, in
the experiments made to test the
effect of this current of air, it was
found that the worms were very
sensitive to it, and that in all
cases when the ventilator was open
the " mode " for the reaction was
pushed over to the right of the
0 class, the light being in these
tests purposely non-directive, as it
came from a lamp directly above
the normal axis of the circle.

3.

Mealworm {Larva of Tenehrio
molitor Linn.).

The negative phototropism of
the mealworm has been commented
upon by Loeb (90, pp. 84, 85),
who found that these animals not
only moved away from the side
of a dish from which the light
came but that they remained in
the darkened half of the dish when
the plane between the dark and the
light portions coincided with the
direction of the rays. A few re-
sponses to a single light as used
in these experiments confirmed
Loeb's conclusions that the ani-
mals are markedly negative in

368 PEOCEEDINGS OF THE AMERICAN ACADEMY.

their reactions to light ; consequently a large series of experiments was
made to determine their reactions to the two lights of different area.

The larvae were placed, one at a time, upon the ground-glass plate
used in the previous experiments, which, as in the case of Bipalium,
was supported about 1 cm. above the table by means of small wooden
feet. As with Bipalium, too, the records were taken when the larva
reached the first, or inner, circle, so that it crawled a distance of only
about 5 cm. In the earlier experiments the glass plate was kept
moist in the belief that the moisture caused the larva to keep up its
crawling motion ; but later the plate was used dry without essential
difference in the results. The animals usually started promptly and
crawled rather rapidly and uniformly, as soon as placed on the plate,
but in some instances they showed considerable hesitancy and made
trials in various directions before going ahead.

They appear to have three characteristic modes of progression : (1)
The most usual manner is by means of the legs alone, the posterior
portion of the body being dragged along passively. This part may be
held straight, but sometimes it is slightly curved to one side, in which
case it is possible that its position influences to some extent the direc-
tion in which the animal turns. (2) The larva occasionally crawls by
alternate elongation and contraction of the body (made possible by the
telescoping movements of the segments), much as an earthworm crawls,
and at such times the anterior end is often raised into the air and
waved about more or less. (.3) The larva may also move backward
for a short distance at about the same rate that it normally crawls for-
ward. It seldom goes backward more than two or three centimeters,
and then starts forward again, apparently alivai/s turning in one direction
or the other, and not going forward in the same line in which it was
moving backward. This last reminds one somewhat of the motor reac-
tion described for Protozoa and some other animals by Jennings ; but
whether it is used for the same purpose in response to strong stimula-
tion or other conditions does not concern us here, since it is not the
usual method of orientation to light of moderate intensity.

In the experiments with light falling upon one side only, the larvae
were given five trials headed in one direction, and then five headed in
the opposite direction ; but in the trials with both lights at once they
were headed alternately in the two directions, — one trial in one direc-
tion and the next in the opposite. Since in both cases there are the
same number of trials in each direction, it is not probable that this
difference of method affects the results. Only 50 trials each were
made with the two lights separately, whereas 200 trials were made
with both operating at the same time. The same five individuals were

COLE. — IMAGE-FORMING POWERS C? VARIOUS TYPES OF EYES. 369

employed in the trials with the lights used separately and in 100 of
the 200 trials with both lights together ; in the remaining trials with
both lights five other larvae were employed. The results of the experi-
ments on the larvae of
Tciiebrio niolitor are class-
ified and summarized in
Table IV.

The preponderance of
reactions away from the
light is strikingly shown
in the first two sets of
experiments, where uni-
lateral illumination was
tested. With the large
light there was not a sin-
gle positive reaction, and
only 4 out of 50 fell in
the 0 class, so that 46, or
92 per cent, of the reac-
tions can be counted as
distinctly negative re-
sponses. The records with
the small light alone are
somewhat more scatter-
ing, but are nevertheless
preponderatingly nega-
tive. Only 8 records are
towards the light, while
in 41 out of the 50 trials
the animals turned to-
wards the dark, giving an
excess of 33, or G6 per
cent, in that direction.
The responses when the
two lights act simultane-
ously are almost equally
balanced as between the
two sides, by far the

larger number of records on each side falling near the 0 class, which
itself contains 43 of the 200 records, or nearly one fourth of the whole
number. This result may be much more quickly and completely
grasped from an inspection of Figure 11, C. On the side towards the

VOL. XLII. — 24

Figure 11. Frequency polygon constructed
from results with tlie mealworm shown in Table
IV. ^4, 50 trials to large light alone ; B, 50 trials
to small light alone ; C, 200 trials to both lights
used simultaneously.

370

PROCEEDINGS OF THE AMERICAN ACADEMY,

>

M

K

H

O

pq
o

H

0

-<
H

a
o

g
CO

O

H

B
C5

W
O

-»!

1-3

O

s

O

is
o

M

W

••!/t(,' o;
BS9axa JO

'XS cc
Ci oc

CM

•

•

CO

0

T—i

S883xa

CD

•

•

00 [

CO

■mso%

•* (M

«0

t- -

CO

•>* CO

g

H

CO

tn

•<
Hi

05

•<*< <M

«c

Ol \

01

00

t^

t>-

"* !

in

i-

lO U3

c

T-H

'. ^

CO

0

^ CC

b-

f— t

1— 1

r— 1

I-H

0

CO cc

CD

I— 1

T-H

•* ^

0

•*

CM r^

1 CO

•

•

0 T-H

t--

CO

rH (?q

CO

l-H

I-H

-# Ttl

00

C)

>-H (M

CO

iM 1—

CO

I-H ,-H

CO

tH

T-H

I-H

(M

CM

CO T-H
T-H T-H

•^

0

r-l CO

Tf

T-H

T-H

rt CM

CO

rH

'~

1-H

0 5^

T-H I-H

1--

c^

Ol !>^

^

S C

0

M

(M ^

CO

0 0

T-H
l-H

'I"

i-H v:

-*

•* CO

0

10

T-H r-

(M

CN (M

'^

to

CO C'

> 0

' Ol

CM

b-

CO l>

UO

.

'

00

!M IC

) t^

T-H

T-H

03

CO «:

c;

T-H T-H

(M

•57 0^

T-H C^

T-H

Oi 00

CO 00

•;6'/ O^

ssaoxa

0 c:

r-l O-

CO
CO

uO

•

•167" 01

ssaoxg jo

•

0 C^

1 0

■ lO

•

•p9pB9H

tioi^aajid

^2; a

>

. ^J '}

^ 0

•

Lights
used.

t-1

C

b

; s

< CO

3
0

0

13
•4-*

o

COLE. — IMAGE-FOKMING POWERS OF VARIOUS TVPES OF EYES. 371

large light are 77 records ; on that towards the small light 80, giving
-an excess of only 3 records in the direction of the small light, which is
only 1.0 per cent of the total number of trials.

Polygons ^1 and Ji are plotted from the data of the experiments
with one-sided illumination, when the large (^1) and small (//) lights
were used separately.

The conclusions to be drawn from the reactions of the larvae of
Tenebrio moUtor are, it would seem, as follows. These animals are
almost uniformly negative to unilateral illumination in light of mod-
erate intensity. The ability of the eyes to form distinctive images of
objects differing considerably in size is wholly lacking, or at least prac-
tically so, as is to be inferred from the reactions of the animals when
exposed to the simultaneous influence of the two light areas used in
these experiments. It is perhaps worth noting that the excess of 1.5
per cent is away from the large light, and that in no case did the larvae
turn towards the large light when that light was used alone, whereas
a few did turn towards the small light when that was the only one
used. Still, it would not be very surprising if in a repetition of this
series of experiments the balance should lie on the opposite side of the
zero class. The magnitude of this ditference is probably too small to
be of significance.

The above results are what would be expected in view of the rudi-
mentary condition of the eyes in the mealworm. The eyes apparently
consist of only two or three ocelli on each side of the head, arranged
in a vertical row immediately behind the base of the antennae. Exami-
nation of the cbitin immediately overlying them, even after it had
been boiled in caustic potash, has shown no thickenings or differen-
tiations that might serve as lenses. The eyes are so small that they
can scarcely be seen without the aid of a lens.

Loeb ('90) has remarked on the relation existing between the reac-
tions of these animals to light and moisture and their natural habits.

4. Soiv Bug (Oniscus asellus Linn.).

This widely distributed, active little isopod may be found in abun-
dance beneath stones, bark, pieces of wood, etc., in the woods in the
vicinity of Cambridge. Its retiring habits, indicating an avoidance
of light, and the ease with which it can be kept and handled in the
laboratory, suggested that it might be a suitable form for use in these
experiments. Handling often has at first an inhibitory effect as re-
gards locomotion, but this is usually overcome in a short time, and the
animals then normally start off as soon as released. The eyes are

372

PROCEEDINGS OF THE AMERICAN ACADEMY.

small, but still readily visible, each consisting of a group of about 20
ocelli situated on the side of the head at the base of the antero-lateral
lobe.

The animals were oriented in the proper position by placing them
within a small rectangular glass frame without top, the glass being

covered with black paper
to exclude the light un-
til the pen thus made
was lifted up. The frame
was oblong, and just large
enough to enclose the
Oniscus easily without al-
lowing it to turn around.
With a little care the
frame could be readily
moved on the table (the
glass plate was not used)
to the position desired,
and with the animal
headed in either direc-
tion. When it was lifted
off, the animal was left
exposed to the lateral
influence of one or the
other or both of the
lights, as the case might
be, but free to move in
any direction. The rec-
ords indicate the place
where it crossed the sec-
ond of the three circles
inscribed on the table, —
the one with a radius of
ten centimeters. As the
animals usually took a
straight, or only slightly
curved course, this was
practically the distance travelled by them in each of the trials.

The experiments with the lights used singly showed Oniscus to be
decidedly negative in the character of its reaction, but by no means so
strikingly so as the Tenebrio larva. In Oniscus, as may be seen from
an inspection of Table V, only 45 per cent to 51 per cent of the reac-

FiGDRE 12. Frequency polygon constructed
from results witli Oniscus shown in Table V. A,
reactions to large light alone; B, to small liglit
alone ; C, to both lights used simultaneously (100
trials under each condition).

COLE. — IMAGE-FORJUNG POWERS OF VARIOUS TYPES OF EYES. 373

o

a
■<

S

o

cc

>

H

K

i3^

^M

,.

c

-

-^

1— 1

^

a

o

5=

BS30\a JO

0 '■V

0 0:

10

•

•

CO

t^

BS33X3

00 t~
5M ^

•

•

0

1—*

i^

■'"V O}

:5 03

0 c

0

CM

CO

?-H

1 ^

-<

.J
o

0

IM !M

■"Jt

i-(

1— 1

(M \

(M

CO

.-> CO

T)1

I—*

l-H

t—t

(M

i ^

t-

5<1

C^

•

•

i : ^

?— t

■0

CO cc

;:^

-^

T-H

»o

lO

L*;

t^ CO

0

.

•

CO

■^

1 '^

•*

1 w t^

CO

.— CO

TJ(

uo

0

CO

l^ lO

C^l

(>»

C^

I— <

0

t^

Cl

<M -N

^

.■ 5^

(N

lr~

(M

Cjl

*-i

5<l uO

t-

t- (M

05

1 *^

'S'

1 ^

0

Tf t^

1 ,

0 Tf<

Ci

■<*'

CO

t^

-H

1 -" ^

(M

0 0^

t—

1—1

CO

■*

ff)

'-' (M

CO

00 0

CO

I-H

(N

CO

0

M

C^ <M

'^

■* ■>*

CO

»— t

(N

CO

-f

CO (N

lO

t^ 10

2 1

(M

CO

00

0

T— t ^^

<M

t^ 0

<N

(M

0

r~

-

! ■^

C<l

-M -*

CO

1 -

CO

■<*<

L-

t— t

l-H

^ (N

CC 1

00

-s<

t>-

CO

I-H

-

>-i CO

•^

<N

<N

■<»<

0

^^ T— t

(N

I— 1

l-H

t—t

r-H

•Bj 0%

Ci CO

■7J

•0 0

00 CO

1-

1

uO

00

CO

■Bjo%
ssaoxa

•

•

0

05

•£701
ssaoxa JO

•

<5 1^

0 uO

1—*

00

•papTjaq
tioi^Dajifj

i eg

0 3

^ CO

•

;^

d

1

00

s

3

0)

"3

0

15
E
cc

5
0

0

"3

374 PROCEEDINGS OF THE AMERICAN ACADEMY,

tions were away from the light in excess of those toward the light,
whereas in Tenebrio the excess in this direction ranged from 66 per
cent to 92 per cent of the total number of trials. The results of the
experiments on Oniscus are represented graphically in Figure 12.

In the trials with both lights the records on the two sides are nearly
balanced, there being an excess of only 7 per cent of the reactions away
from the larger light. This excess again lies in the direction we should
expect if the eyes enable the animal to discriminate between the two
luminous areas, but, as in the case of Tenebrio, it is too small to be of
great significance. It will be noticed by comparing the figures ob-
tained with the large and small lights used separately that the result
is the opposite of that obtained with the two lights acting simul-
taneously, and also opposite to the results in the case of Tenebrio, for
in Oniscus a larger percentage turned away from the small light than
from the large one. Since the experiments on Tenebrio and on Oniscus
were performed at different times, it is possible that a difference in the
(absolute, not relative) intensities of the lights at the two times may
be responsible for the want of harmony in the results. When both
lights were used at the same time, they were adjusted so that their
intensities were equal, and therefore no errors could have arisen from
this source.

It may be concluded from these experiments that, although Oniscus
has apparently much better developed eyes than the larva of Tenebrio,
its responses to light are of a considerably less definite character.
This means that with unilateral illumination Tenebrio turns toward the
light much oftener than Oniscus, and although in a frequency polygon
representing the reactions to light the modo for each of the animals
falls upon the side away from the light, in the case of Oniscus it
falls much nearer to the median (indifferent) line than it does in
Tenebrio. This may be seen by a comparison of Figures 11 and 12.
The greater delicacy of the adjustment to light conditions in Tenebrio
is also shown in the reactions to the two lights used simultaneously.
There the responses of this animal are concentrated about the indiffer-
ent or zero class (Figure 1 1, C), whereas in Oniscus under similar con-
ditions (Figure 12, C) they are scattered much more evenly through
the nineteen classes. This should not be taken to mean that Tenebrio
probably has better vision than Oniscus, but merely that in nature its
phototropism is more strongly negative, a state which may be inde-
pendent of the acuteness of vision, but is commonly related to the
conditions of existence. Whatever evidence is afforded by these
experiments as to the comparative ability of the eyes of Tenebrio
larvae and of Oniscus to form images lies in the fact of the apparently

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 375

greater efficiency of the eyes of the latter animal in distinguishing
between a large and a small area — an efficiency which is indicated in
one case by 7 per cent, in the other by 1.5 per cent. If Oniscus were
naturally as sensitive in its responses to light as Tenebrio, this
difference would probably be greater. In other words, the image-
forming power of the eye of Oniscus probably exceeds that of Tenebrio
more than appears in this method of experimentation, owing to the
fact that even to unilateral illumination the responses of the former
are so much less definite than those of the latter.

5. Cockroach {Periflaneta americana Linn.).

This cockroach, which abounds in slaughter-houses and other similar
situations where there is much waste matter that can serve as food,
possesses large compound eyes with a great number of ommatidia.
Latter ( : 04, p. 8.s), . in speaking of the related species, F. oi'ientalis,
says : "To what extent the compound eyes are capable of forming a
distinct image of surrounding objects we cannot say, but it is evident
that they are keenly sensitive to differences of light and shade from
the speed with which a cockroach makes for dark corners and crevices
when disturbed." This characteristic of cockroaches is very evident
to any one who has ever observed them. If a number of them are in a
glass jar, the cover may be removed with comparatively little danger
that any of them will escape so long as the mouth of the jar is turned
toward the light ; but if its position is reversed, they will usually
escape from it very quickly. These and similar observations led to the
selection of this animal also for experimentation with the lights of
different area.

Cockroaches are so active and comparatively difficult to handle that
it took considerable experimenting to devise a scheme for getting them
oriented in the proper position without the introduction of disturbing
factors. If one attempts to liberate them from the hand, their
struggles usually result in their being in an undesirable position when
released, instead of exactly in the normal position. Finally, after
employing several unsuccessful devices, the following was made use
of. A glass cylinder some 15 centimeters in diameter and 20 centi-
meters high was placed endwise on the table and so arranged that
from one side of the bottom a low, narrow glass runway led off for a
distance of about 5 centimeters. This runway was large enough to
allow a cockroach to pass through it easily, but not large enough to
permit the insect to turn about. It was covered with black opaque
paper, which cut off the light and made its interior dark. This

376 PROCEEDINGS OF THE AMERICAN ACADEMY.

apparatus could be placed -with the axis of the runway directly over
the normal axis of the diagram on the table and so oriented that its
anterior end was directed either north or south at will and coincided
with the directive axis. The animal to be tested was then dropped
into the cylinder and made to move about until at length it entered
the runway. When it came out at the other end of the runway, it was
properly oriented, with one light at its right, the other at its left.
Some of the most active individuals would run through this passage
and emerge without stopping ; but there was much individual variation
in their behavior in this respect. By far the larger number of them
stopped in the runway as soon as their antennae projected from the
farther end, and there they Avould remain, waving the antennae about
or cleaning them by drawing them through their jaws, but refusing to
go farther without being stimulated from the rear. Such individuals
were stimulated by pushing a small block of wood into the runway
behind them until it came against the cerci or the hind legs. The
block was made nearly as broad as the runway in order that it might
strike the animal evenly and not stimulate one side more than the
other. Usually the slightest touch was sufficient to start the insect
from the runway, but some individuals seemed very reluctant to leave,
and in a few instances, immediately they were outside, they turned
about and regained the shelter they had just left. Most of them, how-
ever, as soon as outside, ran ahead steadily and rapidly, either going
nearly straight or swerving to one side or the other ; others would
hesitate or even stop altogether, and then make sharp turns, often
going off finally in a direction entirely different from that which they
first took when they came out of the runway. The records indicate
the points at which they crossed the outer circle — the one having a
radius of 15 centimeters.

Table VI summarizes the results of 98 trials with the large light
alone and 200 each with the small hght alone and with the two lights
used simultaneously. As in the preceding experiments, Figure 13
shows the records in graphic form.

These records show that Periplaneta is decidedly negative to light
from one side, — 42.8 per cent of the reactions may be so regarded in the
case of the large light and 55 per cent in that of the small light.
Here the peculiarity will be noticed that, as in the case of Oniscus, there
was a larger per cent of reactions away from the small light than
away from the large one. Moreover, in the cockroach, as may be seen
from the lower third of Table VI and from Figure 18, C, there were
more turnings from the small light than from the large one, when both
were used. This excess is very small, it is true, — only 9 reactions in

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 377

<:

H

93
O

o

>5

-<

o

K

e

K

Eh

00

!5
O
H

ssaaxa JO

44.8
40.8

42.8

•

•

t—

•

•ms-o;
Bsajxg

iM O

•

•

i~

•

imox

CO CO

O
CD

CO
CO

o ^

00

N

o

CO

CO

(M ;

<N

•

•

00

i-H i-H

(M

•

•

;

•

t-

(N 1

(M

-N

(N

S<)

(M

o

■^ 1— 1

i-O

.

,

;

-

la

"* (M

O

O ]

CD

■

: 1

■*

1— 1 Tji

lO

IM CO

lO

1-1 CO

rH

CO

00 o

(N (N

-*

CO iM

00

IM

C5 05

oo

I— 1

!N tK 1 O

CO 00

CD

-H

cq lO

r-

O CO

00

CO i-l

(M i-i

S

O

CO lO

00

lO CI

r-H

(M

S ^ § 1

-^

lO ■M

t^

t— 1

o

1—1 i-(

05
(N

?1

1—1 I— 1

5^

CO o

T-l r-l

IM

CO

CO (M
1—1

00

1—1

CO

•

.

rH i-H

o

CO

(N CO

o

rt<

CO cq

o

r-l 1—1

CO
CO

■<*( 00

IM

f— 1

10

<-i l^

CO

Tjt t^

1—1

1—1 rH

<M

•.3 _■ CO

CO

•-I O

CO 1
1

r-H

1—4

t-

s<i cq

-*

1-1 (M CO

i-< (M

CO

00

*

r-( CO -Ttl

S<l

IM

C5

' *

■ ■*

•*

1—1

1—1

■i57- o:>
I«?ox-

I-H r-H

CO Ir-

CO t^

1— (

CO o

CO ^^

CO

■i57o;
ssaoxa

■

t- CO

^ CO

o

CO

Oi

ssaoxa JO

•

t^ CO

ij* to

CO
1— 1

•papuaq
nopoaaig

12; M

►2 o

•

!2i cc

•

Lights used.

1-1

O

CO

o

378

PROCEEDINGS OF THE AMERICAN ACADEMY.

200, or 4.5 per cent, —but it is difficult to explain why they are in
the direction of the larger light, instead of the reverse. In the first
set of 100 trials with both lights the records of particular individuals

were not kept separate,

9 R 7 G 5 4 3

10 1

3 4 5 6

8 9

is

10

14

12

^ 10

8

C

4

t>

0

30

32

28

24

B 20

10

12

8

4

0

&4

60

56

52

48

44

40

^ 30

32

28

24

20

16

12

8

4

0

I 1 i I 1 i t 1 : i I I I 1 i 1 I

I I I I

III'

and as it was thought
that possibly some ab-
normal animal had influ-
enced the total, the whole
series was repeated on
another set of five in-
dividuals, these matters
being kept in mind ; but
the results were entirely
comparable with those
obtained in the first set
of experiments. Such be-
ing the case, the two sets
of records were combined,
and are so represented
in the table and the
diagram.

The only plausible ex-
planation of this unex-
pected result which offers
itself at the present time
is, that at least a portion
of the animals were influ-
enced by other factors as
well as by the light from
the two primary sources.
Cockroaches, if undis-
turbed, are apt to make
themselves at home wher-
ever they are put, and
usually soon settle down
to cleaning their antennae
or to making an inspec-
tion of their surroundings,
apparently irrespective of
such influences as steady directive light. It has already been men-
tioned how the animals came to rest at the end of the runway,
waving the antennae about or cleaning them. Similarly, they

18

16

14

12

10

8

G

4

2

0

36

32

28

24

20

16

12

8

4

0

04

60

56

52

48

44

40

36

32

28

24

20

16

12

8

4

0

9 8 7 6 5 4 3

1 0 1

4 5 6

Figure 13. Frequency polygon constructed
from results with cockroach shown in Table \1.
A, 08 trials to large light alone; B, 200 trials to
small light alone ; C, 200 trials to both lights
used simultaneously.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 379

would sometimes stop outside the runway and go through the same
operations.

As a rule the animals which react most constantly and uniformly to
directive light are those that are under more or less unnatural condi-
tions, as was the case with the earthworm, Bipalium, Tenebrio, and, to
a less extent, Oniscus, when placed on the glass plate or on the table
top. These animals usually come to rest under normal surroundings
only when a considerable portion of the body, especially the dorsal
side, is in contact with something. Cockroaches, on the other hand, may
often be found at rest upon the walls of the dimly lighted cellars and
basements where they live. They do not by any means spend all
their time in cracks and crevices, though they usually retire to such
places when more strongly illuminated. In many animals the ordinary
reactions appear to have an inhibitory effect on the reaction to light,
so long as the animal is not disturbed in any unusual way. Or the
animal may simply come to rest, and yet respond immediately to such
constant stimuli as directive light or gravity if it be disturbed.
Carpenter (^05) has pointed out, for example, that pomace flies
(Drosophila) will come to rest in the darker portions of the dish
with their heads turned away from the light, but if they be disturbed
by turning the dish slightly, they respond at once with their ordinary
phototropic reaction. Mechanical agitation has a similar accelerating
effect upon their reaction to gravity. As will be described later, a frog
may sit for a considerable time with the axis of the body at right
angles to the direction of a light, which apparently has no effect upon
him ; but upon being stimulated in any non-directive way he will
usually turn at once and face the light, or may even hop toward it.
Similarly, reactions to food, to contact stimuli, etc., may inhibit
entirely the ordinary reactions to light. Certain pycnogonids cease
entirely their efforts to go toward the Hght when the feet can grasp
the stems of hydroids, among which these animals normally live ;
while if they are placed in a dish of water where they are unable to
grasp any such familiar objects, they are strongly phototropic (Cole,
: 01). In fact, Loeb ('90, p. 21, et seq.) made special mention of the
inhibitory effect of contact stimuli in his pioneer work on phototropism.

Instances need not be multiplied. The point is that the cockroaches,
not being under especially unusual conditions, may have been influenced
by other stimuli or by physiological conditions which in the case of
animals less " at home " would have been overcome by the phototropic
response. This may account for the fact that the slight excess of re-
actions was in a direction opposite to what one would expect. But the
surprising thing is that this excess should have been so small, for in an

380 PROCEEDINGS OF THE AMERICAN ACADEMY.

animal with eyes comparatively so well developed we might expect
more evidence of image-formation to be apparent in its reactions to the
lights of different areas. An inspection of Figure 13, however, shows
that the " mode " for the negative responses of the cockroach to unilat-
eral light lies only 20° to 4(J° from the indift'erent position, in which
respect it agrees more closely with Oniscus (compare Figure 12) and
differs markedly from the Tenebrio larva (Figure 11), although its eyes
are undoubtedly vastly better adapted to ordinary vision than those of
the mealworm. This means that the cockroach is less responsive to
directive light than the mealworm, or at any rate that its responses are
less definite and constant. Another factor which must be taken into
consideration is the greater rapidity with which the former animal
travels, so that in a given distance the light acts upon it during a much
shorter interval than is the case with an animal which moves more
slowly. Under these circumstances the records would tend to be less
divergent ; and undoubtedly this was an important factor in the reac-
tions to both lights, where, it will be observed, the number of records
in the 0 class was very large (Figure 13). The same factor would have
a tendency to mask any differences there might be in the reactions to
the two lights. This fault was partially corrected in the experiments
by taking the records for the cockroach when it crossed the outer circle
(15 cm. radius), whereas the records on Tenebrio were taken when it
reached the innermost circle (5 cm. from the starting point).

The conclusions to be drawn from the experiments on the cockroach
may, then, be stated briefly as follows : Periplaneta americana reacts
negatively to directive light as used in these experiments in an excess
of about 50 per cent (42 per cent to 55 per cent) of its responses. It
possesses relatively large eyes, which, one would suppose from their
structure, were capable of much better image-formation than those of any
of the other forms so far employed ; but the results of the experiments
fail to confirm this point. The explanation is probably to be looked for
in the fact that on account of the influence of other factors the reactions
to light are masked, and probably to a certain extent inhibited.

6. Moui'ning-cloak Butterfu ( Vanessa antiopa Linn.).

The work of Parker ( : 03) on Vanessa naturally suggested that animal
as a favorable subject for these experiments. The following conclu-
sions reached by Parker (: 03, p. 4G7) are of importance in the present
connection :

"3. V. antiopa creeps and flies toward a source of light, that is, it
is positively phototropic in its locomotor responses.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 381

"4. Its positive phototropism occurs with lights varying in inten-
sity from 2 candle-power at 2 meters distance (0.5 candle-meter), t)
250 candle-power at 2 meters distance (62.5 candle-meters). . . ,

" 10. V. antiopa does not discriminate between lights of greater oi
less intensity provided they are all of at least moderate intensity and
of approximately equal size.

"11. V. antiopa does discriminate between light derived from a
large luminous area and that from a small one, even when the light
from these two sources is of equal intensity as it falls on the animal.
These butterflies usually fly toward the larger areas of light."

It will be seen that Parker had already concluded what might be ex-
pected to result from experiments on these butterflies under the con-
ditions of the present investigation. His conclusions were based in
large part upon observations in the field, supplemented by a number
of experiments conducted in the laboratory. These, while they seemed
to establish the verity of his conclusions beyond a reasonable doubt,
were largely qualitative in their character, and it seemed of interest
to repeat them under conditions in which the intensities and compara-
tive areas of the lights were accurately known. Specimens of V. a?itiopa
were accordingly procured, and as it was desirable — considering the
comparatively small space where the insects could be exposed equally
to the two lights — to have them crawl instead of fly, the wings were
clipped off a short distance from the body, leaving only short stumps,
by means of which the animals could be easily handled. Two difficul-
ties presented themselves. Many of the butterflies either made at-
tempts to fly, which resulted in their flopping about helplessly on the
table, or they feigned death when released and refused to move at all.
It was found that by holding the animal by one wing-stump, it would
usually struggle with its legs and the other wing-stump. If in such
a state of activity it was placed on the table, it would seldom feign
death, but would start at once to crawl off. Attempts to start the
animals with exact orientation in the normal position were abandoned,
since it was found that holding them by one wing was apt to impart
a unilateral impetus to their first locomotor movements ; furthermore,
after starting to crawl they would often begin making attempts to
fly, and so struggle about on their backs with their legs in the air,
thus losing all orientation before they regained their feet and pro-
gressed again by creeping. For similar reasons no record was made
of the angles at which the animals diverged from the normal ; in fact,
when they once began crawhng well, they crawled, as a usual thing,
directly toward the light. In some cases they would first crawl a
short distance toward the small light and then turn and go toward

382 PROCEEDINGS OF THE AMERICAN ACADEMY.

the larger light. Since such results appeared to be due to chance
orientation at the beginning of the trial, or after the insect had lost
its orientation by fluttering, the records of the direction of its response
were not made until it had crossed a line, on either side, at a dis-
tance of about 25 cm. from the normal axis. In the later trials no
attempt was made to place the insects in normal orientations at the
beginning of the trials, but they were dropped at random as nearly
as possible at the central position on the table. About the same
proportion between negative and positive responses was obtained as
when the attempt had been made to orient the animals.

In all 1G4 trials were made in this way upon 7 different individuals
of Vanessa, with the following results :

Toward large light. Indifferent. Toward small light. Total.

143 1 20 = 164

Thus it will be seen that 87.2 per cent of the responses were toward
the large light; 12.2 per cent were toward the small light; while
only a single one, or O.G per cent could be called indifferent. The ex-
cess of responses toward the large light .over those toward the small
was 123, or just 75 per cent of the whole. This result therefore con-
firms Parker's conclusion that Vanessa antiopa discriminates between
lights of different area falling with equal intensity upon the animal.
That so many as 12 per cent of the responses were toward the smaller
light is probably to be accounted for largely upon the chance orienta-
tion and the condition of making the record as soon as the insect had
crossed a given line at a certain distance from the starting place. One
or two instances were observed in which the butterfly actually turned
and went back toward the large light after having passed this limit in
the direction of the smaller one.

7. Water Scorpion {Ranatra fusca Pal. B.).

The interesting work by Holmes (: 05*) on the reactions of the
water bug Ranatra to light suggested this form as a favorable one
for use in the study of image-formation. Except under certain con-
ditions, Ranatra is very strongly positive to light, apparently of any
intensity, and reacts to it with great uniformity and persistence.
Holmes says (p. 315): " Light seems to dominate entirely this creature's
behavior when the phototactic reactions are once started. It does not
manifest any fear or awareness of any object in its environment save
the light which it so strenuously seeks. Its excitement increases the
longer it is operated with, and after a time it may be picked up
without feigning death, or with only a momentary feint."

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 383

Diligent search in the streams and ponds in the vicinity of Cam-
bridge failing to disclose any of these animals, several dozen speci-
mens were procured from Ann Arbor, where Dr. Holmes obtained his,
and where they are often very abundant. They were shipped to
Cambridge in a small tin p;iil, with barely enough water to cover
them, but arrived in good cundition and were kept in aquaria in the
laboratory for a number of weeks. They were fed occasionally on
Asellus and whatever small water beetles or other a(iuatic insects
could be obtained, and when the freezing of the ponds made such
food difficult to obtain, it was found that mealworms (Tenebrio
larvae) could be substituted with apparently as good results. These
were offered to the Kanatras in a pair of tweezers, usually having
been crushed slightly in order to make it easier for the bugs to insert
their beaks through the hard outer covering of the larva ; otherwise
the Ranatras were often unable to penetrate the larvae anywhere
unless they chanced to find the soft integument at the bases of the
legs. Holmes gives, in addition to a description of their reactions to
light, a good account of their general habits, a knowledge of which is
alwaj's an invaluable preliminary to experimental work upon any
animal.

Comparatively few preliminary experiments were necessary to con-
firm the majority of Holmes's results, including the death-feigning,
the head movements and swaying movements in response to light,
and the subsequent positive phototropism, as well as the negative
response to light under certain conditions. This negative response
was found, in part, to occur at times when there appeared to be
no definite assignable cause ; but in general it seemed to be due to
an appreciably less active condition, brought about possibly in many
cases by exhaustion or by lack of food. As Holmes says (:05^ p. 317):
" The negative reaction is associated with a condition of lowered photo-
tonus. It is rarely shown except when the animal is in a condition of
comparative sluggishness. When in great excitement, when its move-
ments take place with quickness and vigor, Ranatra always shows a
positive reaction." He found that the negative reaction usually fol-
lowed prolonged exposure to darkness. At times, however, tempo-
rary periods of negative response appear in animals which are
otherwise uniformly responding positively to light, under apparently
similar conditions and with no obvious cause. It will readily be
seen how this might be a disturbing influence in the experiments
testing the responses to both lights ; for, whereas a positive ani-
mal might be expected to turn toward the large light, if it dis-
criminated between the two lights at all, conversely an animal in a

384 PROCEEDINGS OF THE AMERICAN ACADEMY.

condition of negative response would under similar circumstances
turn toward the smaller light. For this reason, although it would
not matter in testing the reactions of the animal to the two lights,
whether it were positive or negative, it is exceedingly important that
the insect should be in one or other of these states and remain so
without change throughout the experiment. It is so much easier to
keep Ranatra in the positive condition than in the negative one,
and the insect reacts so much more definitely and decidedly when
positive, that, so far as possible, only individuals in this conditioii
were used. A number of specimens were taken from the water and
placed on the table. Most of them immediately went into the death
feint, as described by Holmes ; but there were usually a few that re-
mained active. Some of these were occasionally positive, though more
often they were negative and began crawling away from the light.
After a time the others began gradually to come out of their death
feint, and these, in nearly all cases, were positive. They were al-
lowed to crawl toward the light until they became fully active and
could be picked up and handled without fear of changing their re-
actions. That individual was then selected for experimentation which
appeared most strongly and persistently positive. If, as often hap-
pened, they reached such a state of excitement that they attempted
to fly to the light, the method adopted by Holmes to prevent this
was resorted to, namely, fastening down their wings with asphalt
varnish.

No regular separate series of experiments were made to test the
reactions of Ranatra to the lights singly, but trials of this kind were
made from time to time in the course of the tests with both lights by
screening off one or the other, and exposing the animal to the remain-
ing light. Furthermore, the method used for bringing the animals into
normal orientation at the beginning of each trial aftbrded a means of
observing immediately any change in the character of the reactions.
The preliminary orientation was accomplished in the following manner:
Two runways were constructed by tacking strips of pasteboard, painted
black, to the sides of wooden blocks on each of which was mounted
a small incandescent lamp (Figure 14, /, /') registered as 2 c. p. By
means of a single switch, either of these lamps could be lighted at will
simply by throwing the switch handle one way or the other. When
the switch was midway, both lamps were thrown out of circuit. If it is
now desired to test an animal to the action of two lights, Lg and Sm,
having it first headed north, so that Lg is to its left and ^Sm to its
right, the animal is picked up by its breathing tube and dropped into
the runway So with its head pointing toward No. The switch has pre-

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 385

viously been thrown so that lamp / is lighted, and the animal, being pos-
itive to light and protected from lights Lg and Sm by the sides of the
runway, starts crawling straight ahead toward /. As soon as its head
emerges from the runway it comes under the influence of the lights at
the sides, and the lamp /, which was used only to bring it out in proper
orientation, is immediately switched off. If the animal now turns
toward either of the side lights,

1-4

Nc

So.

the record is taken, Lg or Sm,
according to the way it turns, the
record not being taken, however,
until it has crawled far enough
to cross the outer (15 cm.) circle.
Should it go straight ahead and
enter the opposite runway, the
record is indifferent, or 0. The
next trial is made from the
other runway. No, and so on
alternately, the specimen being
beaded first in one direction and
then in the other, in order to
avoid the possible establishment
of a habit of turning in the same
direction. The likelihood of this
occurring without proper precau-
tion is indicated by Holmes's
work (: 05*, p. 336). Still further
variation in operation was ob-
tained by occasionally running
two successive trials in the same
direction, thus shifting the order
of alternation.

A varying number of trials
were made with 12 different in-
dividuals, the results of which
are summarized in Table VII.

The results of the trials with the single lights, which were made from
time to time, are included for comparison with those to both lights,
since they can with considerable accuracy be taken as a measure of the
positive phototropism of the animal during the period it was being
experimented with. A test in each of the two orientations was usually
made with each of the lights separately at the beginning of the work
with any individual. The insect was then tested with both lights for

Figure 14. Apparatus employed for
orienting Ranatra ; I, I', 2 candle power
incandescent lamps ; No, runway on
nortli side of working position ; Sm, side
directed toward small light ; So, runway
on south side of working position.

VOL. XLII.

■25

386

PEOCEEDINGS OF THE AMERICAN ACADEMY.

TABLE VII.
Summary of Reactions of Ranatra to Large Light alone, to Small Light

ALONE, AND TO BOTH LiGHTS USED SIMULTANEOUSLY.

Lights used.

Large.

Small.

Both.

Total of
Trials with

Individual.

Direction of
Reaction.

Lg(+).

0

1

1
1

Sm{-).

Lg{-).

0

1
1

2
2.1

Svi(+).

Lg.

0

2

14

2

2

2

22
4.6

Sm.

Individual a
b
c
d
e
f

" g
h
i

J

k

1

4
10

8
25
18

4

7

4

2

4

7
1

3

7
3

4

4

8
7
21
20
4
6

4

2

4

6
23
23
23
77
59
23
12
35
3
6
46

2
11

5
19
17
13

5

13
3
2

28

16

54
44

102
152
80
48
12
58
12
8
84

Totals

Per cent of
total trials

Excess
(per cent)

86

87.8

76.5

11
11.2

14
14.6

80
83.3

68.7

336
70.6

45.8

118
24.8

670

Total of

trials under

each

condition

98

96

476

670

a considerable number of trials ; then tests were again made with the
lights singly. This was not altogether necessary, since a change in the
phototropic state of the animal could usually be told at once by its
behavior in the runway. As it became negative, instead of going out
toward the incandescent light in the other runway, it would attempt

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 387

to turn about and ^,^0 from it. Furthermore, whenever an animal was
subjected to both lights and turned for a number of times toward the
small one, it was immediately tested with the lights separately to find
whether it reacted negatively under these conditions. This was found
to be the case in enough instances to establish pretty thoroughly the
conclusion that a change in the character of the animal's reactions was
usually an explanation of a number of turnings to the small light. The
negative condition, however, often appears to be very temporary and
vacillating, and at such times the animals show much hesitancy in their
reactions, sometimes heading first toward one light and then toward
the other, as if undecided in which direction to go. When a specimen
appeared to have become at all permanently negative in its reactions,
the experiments with it were discontinued and another individual was
taken in its place. It will be observed in Table VII that the per cent
of plus reactions for the large light and for the small light were nearly
equal, — 87.8 per cent for the one and 83.3 per cent for the other, —
averaging about 85 per cent of the total number of reactions in the
two cases. The excess of positive over negative reactions was 76.5 per
cent and 68.7 per cent respectively. When both lights were used, the
per cent of responses to the large light was somewhat smaller, but still
comparatively large. This was 70.6 per cent of the total number of
reactions, or 45.8 per cent in excess of the reactions to the small light.
These figures are considerably smaller than the corresponding ones for
Vanessa, in which, it will be recalled, 87.2 per cent of the reactions
were toward the large light, while the excess in that direction was 75
per cent of the whole. This difference, however, is probably caused
not so much by an inferiority of the eyes of Ranatra, in respect to
image-formation, as by the variable character of its phototropic states.
Ranatra has periods of negative phototropism, whereas Vanessa appears
never to be negative in any of its locomotor responses to light.

From the experiments which have just been described, it is apparent
that Ranatra is able to discriminate between a very small source of light
and a luminous area 41 cm. square, even when the intensity of the
light striking the two eyes is the same ; and judging by the large per
cent of reactions toward the large light by animals which are positive
in response to unilateral illumination, it is reasonable to infer that the
eyes are capable of forming images of considerable definiteness. Differ-
ences in the normal phototropic responses of the two animals, as well
as the influence of different inhibitive reactions, and other factors, will
not allow the drawing of very close comparisons between the relative
capacity of image-formation in the eyes of Vanessa and Ranatra. Other
things being equal, the foregoing results would indicate a more precise

388 PROCEEDINGS OF THE AMERICAN ACADEMY.

condition in Vanessa, but the uncertain elements which have been
mentioned must be taken into account before conclusions can be drawn
with any degree of confidence.

Mention has been made of individuals which at times showed much
hesitancy in these reactions, and having turned toward one light
seemed disturbed by the other, which was now behind them. At such
times the head was usually held high, in the manner described by
Holmes (:05*, p. 312), when the light was moved to a position behind
the animal. It was found that by painting over the posterior half
of the eyes, so that the light was excluded on that face, the influence
of the light behind the insect could be prevented. After having their
eyes treated in this manner, even individuals which had previously
shown great hesitancy held their heads low, and once oriented toward
either light, crawled straight on in that direction without turning.
This was not resorted to, however, in any of the trials summarized in
Table VII. If the eyes were painted on their anterior halves, exactly
the opposite state of affairs was brought about. In this way individuals
which had previously shown no hesitation when once oriented toward
either light, were caused to turn first to one and then to the other, the
reason being that, as soon as the animal was facing one light, that one
could no longer be seen on account of the paint, while the other, shin-
ing on the unpainted posterior half of the eyes, caused the insect to
turn from the apparent darkness ahead to the light behind. In this
way it was kept turning about and about, and making no definite
progress in any direction.

8. Pomace Fly {Drosophila ampeloiyhUa Loew).

Upon this form and the succeeding one, only negative results were
obtained as regards the question of inferred image-formation. It was
expected from their general behavior toward light that these animals
would be eminently suitable for this investigation, and the failure to
obtain definite results with them was a disappointment. Long series
of experiments were tried both with these flies and with snails, in-
volving much time and labor ; a brief account of them is given here
merely to illustrate how certain unforeseen conditions may influence the
reactions of an animal in ways entirely unexpected.

In his investigations upon the reactions of Drosophila, Carpenter
(:05) found that this little fly is always positive in its reactions to
light, at least in its locomotor responses. ^ It, like Vanessa, often

' There are undeniably times when Drosophila may crawl away from the
source of light ; but this is probably in response to other stimuli, such as food,

COLE. —IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 389

comes to rest with the head directed away from the light, but Carpenter
does not consider this an indication of negative phototropism. His
explanation is that " The fatigued insects remain quiet in this position
because it is the one in which the least light enters the eyes, and iu
which, as a consequence, the kinetic stimulus is least" (p. 170). The
desirability in the present instance of having animals which were ac-
tively phototropic and in which the character of the response, whether
positive or negative, remained constant, has already been mentioned.
The pomace fly seemed to fulfil these conditions remarkably well,
since it is always, when in motion, positive to light, and can usually
be put into motion by slight mechanical agitation whenever it shows a
tendency to come to rest.

All this works out very well with a single light, but in using both
lights the difficulty arises of getting the flies properly oriented at the
beginning of the trial. If they chance at the beginning to be headed
toward either light, they appear to continue crawling in that direction,
heedless of the other light and indifferent as to whether the one toward
which they are headed is the larger or the smaller. The plan was first
tried of liberating a number of individuals in a box through a hole
in its bottom, the box being provided with glass sides, one directed
toward either of the lights. When once they alighted on either glass,
they crawled upward, in consequence of their natural negative geotro-
pism, and so passed into a trap device at the top, where they could
be counted at leisure. It was expected that when they were placed in
a small dark box beneath the hole in the bottom of the one with
the glass sides, they would at once fly upward from the dark into
the light of the upper box, and so would become suddenly exposed
(as they flew upward, and oriented at random) to the influence of the
large and small illuminated areas. It was found that on the contrary
few of the insects flew out ; the most of them crawled up over the edges
of the opening and proceeded to crawl on in the direction in which
they chanced to be oriented. Furthermore, a large proportion of them
evinced a decided tendency to settle down and remain quiet soon after
getting out into the light, coming to rest here and there all over the
bottom, top, ends, and the glass sides of the box, and it took more than
moderate jarring of the box to get them started to crawling again.

Next, the plan was tried of placing backwardly projecting strips of
paper around the opening, making it more difficult for the flies to crawl
out at the edge of the opening. At the same time there was placed

which for the time inliibit or overcome the natural phototropic reaction, and is
not to be considered an active negative reaction to lit^ht.

390 PROCEEDINGS OF THE AMERICAN ACADEMY.

in the middle of the opening a small wooden cone, up which the flies
could easily climb. Nevertheless many still persisted in crawling out
at the edge of the opening in spite of the obstructions, while those
that climbed the cone usually came to rest on its sides instead of
climbing up to its apex and flying thence as it was hoped they would
do. Obviously, too, those which climbed the sides of the cone were
often shaded from one or the other of the lights by the cone itself, and
this introduced another chance for error. Finally, an outer paper cone
was so arranged as to make it impossible for the flies to come out any-
where except through an opening at its apex, from which there led a
narrow Y-shaped paper, one arm extending toward the large light,
the other toward the small, with strings leading upward to the traps
on either side. But even with this apparatus the tendency of the
flies to continue crawling up the edge of the Y upon which they hap-
pened to emerge appeared to overcome in large part their reaction to
light. With a single light — the large one — only about twice as many
individuals went toward the light as in the opposite direction ; and
when both lights were used the readings were almost equal — 222
to 226.

From these results it will be seen that, although the eyes of Dro-
sophila would, from their structure, appear to be as well adapted to
image-formation as those of either of the other adult insects em-
ployed, the experiments with the two luminous areas of diff"erent size
furnish no data whatever to aid in the determination of this point.

9. Garden Snail of Europe {Helix pomatia Linn.).

These snails, during the winter months when they have withdrawn
into their shells for hibernation, are imported into this country by
certain French restaurants in the larger cities, and may in this way
be readily obtained in the living condition. Under the influence of
warmth and moisture they emerge and live well, so that they may
be kept in the laboratory for a considerable period. A few preliminary
experiments tried with them seemed to indicate that they were for the
most part decidedly positive in their reaction to light, often turniug
to it at once at a sharp angle. This led to the hope that they might
be suitable for experimentation in regard to the eff"ect of the two lights.
The snails were allowed to crawl on the ground-glass plate in the same
manner as described for the earthworm and laud planarian. They are
easily handled by the shell and can be placed in any position desired.
As in the case of the other forms, they were first oriented in the
" normal " position in the shaded area between the screens and then

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 391

allowed to crawl out into the light. Trials were made alternately with
the animals headed in one direction and then in the opposite.

It soon became apparent that these snails were by no means uni-
formly positive to light, so it was necessary each time to test them
first with a light at one side only in order to be certain of the state
of the animal. It was furthermore found that they appeared to become
fatigued very quickly, and apparently this was often" accompanied by
a change in the character of the phototropic response. Finally, the
method was adopted of making only a few trials with each individual
each day. The first trials were made with both lights, one trial in
each of the two orientations, and then trial was made with a single
light to ascertain whether the response was positive or negative to that.
The records for animals that were positive were kept separate from
those of animals that were negative. The responses were so irregular
and apparently so dependent upon the physiological state of the animal
that no very definite conclusions could be drawn. As far as they
showed anything, however, they seemed to indicate a fairly indifferent
reaction to the two lights in the case of animals that were negative as
well as in those that were positive. This leads to the inference that
the eyes of the snail do not aid greatly, if at all, in the discrimination
of two lights differing in area as the two used. If, as is maintained,
the general integument is sensitive to light-stimulation, a result simi-
lar to that obtained in the reactions of the earthworm to the influence
of light on the skin would be expected, since, without the eyes, the
condition would be comparable to that of the earthworm. These ex-
periments on the snail, as far as they go, point to the conclusion that
the ability to discriminate differences in the size of luminous areas is
aided but little, if at all, by the eyes.

10. European Garden Slug {Limax maximus Linn.).

A few experiments were also made with the slug Limax maximus,
as an example of a mollusk normally negative in its reaction to
light. As in the case of Helix, however, the animals were found to be
so inconstant in their responses that it was exceedingly difficult to
obtain consistent results fi:om them. Frandsen ( : Ol), in his work on
the reactions of Limax to direction stimuli, found much individual
difference in the reactions to light, as well as to gravity. Further-
more, he found that the reactions of the same individual vary in in-
tensity, and even in character, with variations in the intensity of the
light, and probably also in response to undeterminable physiological
states. These variable conditions introduce so many elements of un-

392 PROCEEDINGS OF THE AMERICAN ACADEMY.

certainty that Limax, like Helix, is unsuitable for use in experiments
where constancy in the character of the reactions is necessary.

11. Cricket Frog {Acr is gryllus Le Conte).

In the search for animals with the type of eye often known as the
" camera eye " which could be employed in these experiments, the
choice appeared to be rather limited. Of the vertebrates which could
be used out of water most appear to be either indifferent to the action
of directive light, or else their reactions are of such a complex nature
that the natural responses to light are inhibited by other external
stimuli or by fear. Certain of the amphibia appeared most promising,
especially the frog, this animal having been experimented upon by
.Graber ('84) more than twenty years ago, and by a number of observers
since that time. Two recent papers, one by Parker ( : 03^ ) and the
other by Torelle (:03), treat rather fully of the reactions of frogs to
light. Parker's observations relate exclusively to the leopard frog
{Plana pipiens Gmelin), while Torelle used this species and the green
frog {U. clamata Daudin) indiscriminately.

In previous years, at Ann Arbor, Mich., I had incidentally noted the
marked positive phototropism of the little cricket frog, which is
abundant about ponds and lakes and in the marshes of that region.
It is an active little animal, capable of making leaps to a distance of a
meter or more. Specimens placed on a large table top above which
swung an electric light at a height of a half-meter or so were observed
to make long leaps toward the light. They usually missed striking the
globe, seldom going so high, and landed on the other side of the table
headed away from the light. Ordinarily they would remain in this
position for a short time, then turn around so as to face the light again,
and then, after another interval, again leap toward it ; this proceeding
would be repeated until a chance jump carried them completely off
the table on to the floor. The decisiveness and persistence of the re-
action suggested that this animal might prove even better to work with
than the common species of Rana. In consequence, through the kind-
ness of friends in Ann Arbor, several dozen specimens of Acris were
obtained from that place for the purpose of these experiments. In the
meantime a number of other amphibians, including two species of
Plethodon and Diemyctylus viridescens, were tested as to their light
r3actions, but although these in general appeared to be negative to
light, as would be suspected from their habits, their reactions to the
intensity of light used did not appear sufficiently marked to make
them suitable for these experiments.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 393

In the experiments with Acris the animal was placed beneath a
small glass box (approximately 4 cm. X .J cm.), large enough to allow
the frog to turn freely in any direction but not permitting it to hop any
distance. Care was taken to keep the sides of this box normal to the
directive axis of the apparatus, and although the intervention of the
glass between the animal and the light on each side introduced reflec-
tions which could not be avoided, it appeared, from certain tests that
were made, that these were sufficiently insignificant to be disregarded.
The method of orienting the animals at the beginning of each trial, at
right angles to the line joining the two lights, was similar to that em-
ployed in working with Ranatra. When it was desired to start with the
frog headed north, for example, a small incandescent light was turned
on at that side, while screens were placed between the animal and the
experimental lights. Under these conditions the fi-ogs usually turned
within a short time and faced the incandescent lamp. This got them
into the desired position, so that the incandescent lamp was then turned
off and the screens removed as nearly simultaneously as possible, leav-
ing the frog exposed to the influence of the large and small lights, one
at either side. The next trial was made in precisely the same way
except that the incandescent lamp was placed to the south instead of
the north, and in consequence the frog was oriented in exactly the
opposite direction to what it was in the previous trial.

Four series of experiments, comprising in all 300 trials, were made
upon the reactions of Acris to the two lights. The first three of these,
(Table VIII, ^4, B, and C) were made with the lights at the same dis-
tance that had been used throughout all the experiments, namely, at 2
meters from the animal, or 4 meters apart. As has already been stated
(p. 345), this gave a light intensity of 1.25 to 5 CM. falling upon the
animal on each side. The combined results of these three series are
given in Table VIII. Before making series D, which is similarly sum-
marized in Table IX, the lights were moved nearer together until they
were but 2 meters apart, thus reducing the distance between them and
the animal by half and increasing their intensity at that, the median,
point four times. The intensity of light striking each side of the animal
was consequently then about 5 CM. to 20 CM. With the stronger
intensity the frogs reacted much more quickly and uniformly. They
sometimes acted almost immediately when the orienting light was
turned off and the screens removed exposing them to the experimental
lights ; but usually there was an interval varying from a few seconds
to half a minute, or even longer, before they turned toward one light
or the other. Parker (: 03*, p. 29) found similarly that Rana pipiens
responded much more quickly to the stronger light intensities. At the

394

PROCEEDINGS OF THE AMERICAN ACADEMY.

TABLE VIII.
Reactions of Acris gryllus to Both Lights.

Series.

Date.

Indi-
vidual.

Turu-

ings to

Lg.

Turn-
ings to

Sm.

Total
Trials.

Remarks.

A

May

14

1

10

0

10

(f

2

7

3

10

it

3

9

1

10

it
tt

4
5
6

7
3

7

3

10 .
10 <
10^

Inactive. Apparently not

it

3

strongly +phototropic.

ii

7

5

5

10

Turned in all cases to its left.

15

8

4

6

10

tl

9

4

6

10

tt

10

7

3

10

B

25

1

3

1

4

il

2

2

0

2

tt

3

1

5

6

it

4

2

2

4

tt

5

3

1

4

tt

6

3

1

4

a

7

4

0

tt

a

8

9

10

4

2
2

0
2

2

•!

Very inactive. Not strongly -\-.

tt

Turned always to its left.

C

26

1

4

0

4

t(

2

1

3

4

Seemed quite strongly -f .

tt

3

4

0

4

ti

4

2

2

4

Turned always to its left.

a

5

2

2

4

tt

6

2

2

4

Turned always to its left.

ti

7

3

1

4

Strongly -f .

it

8

3

1

4

it

9

3

1

4

it

10

4

2

6

it

11

4

0

4

Reactions prompt.

ti

12

3

1

4

it

13

3

1

4

a

14

2

2

4

<(

16

1

1

2

Totals

130

70

200

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 395

lower intensities used by him (in the neighborhood of 1 CM.) "the
animals often did not react for from five to ten minutes or even longer."
It was only an exceptional specimen of Acris that did not react within
less than about a minute, and as the intensity of light employed was
not far from the lower intensities used by Parker, it is obvious that,

TABLE IX.

Reactions of Acris gryllus to Botfi Lights at Half the Custojiary

Distance.

Series.

Date.

Indi-
vidual.

Turn-
ings to
Lg.

Turn-
ings to
Sm.

Total
Trials.

Remarks.

D

May 29

1

4

0

4

1( a
(( it

2
3

8

7

0

1

8
8

Turnefl toward Lq, even if fac-
ing at first more toward Sm.

i( 11

4

3

5

8

f( ((

5

8

0

8

(< a

6

7

1

8

tt ((

ti n

7
8

8
8

0
0

8
8

Strongly +; reactions very
definite.

it tt

9

8

0

8

n a

10

i

1

8

t( It

11

12

5
4

3
4

•i

8

Did not orient well to single
light. Apparently — part of
time.

At first + ; then became — .

ti it

13

6

2

8

Tc

)tals . .

83

17

100

as judged by the time required for response, Acris is much more
sensitive to this form of photic stimulation than the leopard frog.

An inspection of Table VIII will .show that out of 200 trials 130 (65 per
cent) were toward the larger light, an excess of 3< ) per cent in that di-
rection over those in the opposite direction. The proportion of turn-
ings to the large light is undoubtedly considerably lowered by the
inclusion of several individuals which appeared to be indifferent or

396 PROCEEDINGS OF THE AMERICAN ACADEMY.

defective in their reactions, such as No. 7 in Series A, and Nos. 4 and
6 in Series C, which turned in all cases to their left. This may have
been due to indifference to light, the animals turning to their left possi-
bly for some structural reasons, or there may have been some defect
of sight in the right eye, which would also result in a turning always to
the left. It should be mentioned that the same individuals, in part at
any rate, were used in the different series, but that the numbers by
which they are designated in the various sets do not correspond. For
this reason No. 4 or No. 6 of Series C may have been the same indi-
vidual as No. 7 of Series A, but it is impossible to say definitely. It
was found, too, that sluggish or inactive individuals, or those which
did not oi'ient readily to the light used for that purpose before making
the trial, gave in general a much smaller proportion of reactions toward
the large light than those frogs which reacted promptly and oriented
readily to the incandescent lamp. Individuals No. 5, Series ^4, and
No. 9, Series B, are examples of the inactive sort.

Series D comprised 100 trials, on 13 different individuals, with the
lights at half the usual distance. The results are shown in Table IX, and
are so decided as to admit of no doubt as to the character and meaning
of the reactions. Of the 100 trials, 83 were toward the large light and
only 17 toward the small one. This means an excess of 66 per cent of
the turnings in the direction of the large light. This is considerably
larger than the corresponding value found for Ranatra (45.8 per cent;
cf. p. 387), but smaller than that found in the reaction of Vanessa (75
per cent ; cf. p. 382). It will be noticed that with the exception of indi-
viduals 4, 11, and 12, all the animals turned toward the large light in at
least three-fourths of the trials with them, that is, in at least 6 out of 8
trials ; and if the records of these three had been omitted, it would have
brought the total number of reactions toward the large light up to 93
per cent, or an excess of 86 percent over those in the opposite direction.
No memorandum appears to have been made at the time with regard to
the behavior of individual 4 in other respects ; but No. 11" did not
orient well to single [incandescent] light " and was " apparently nega-
tive," at least part of the time ; while No. 12 was " first positive, then
became negative." In correspondence with this change of behavior
to a single light in this last individual, it first gave 4 turnings to the
large light and then 4 to the small.

It will thus be seen that the proportion of reactions to the large
light by Acris was considerably lowered by the inclusion of the
records of these three animals, which were either in a negative, or at
least an inconstant or indifferent, state as regarded the character of
their responses to one-sided illumination. As with Ranatra, this

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 897

inconstant and not accurately determinable factor precludes making
direct quantitative comparison with the results obtained upon Vanessa
or other forms. If such a comparison were to be attempted, it would
probably be justifiable to leave out of account entirely the results on
the three specimens of Acris which appeared to be negative, since
Vanessa appears to be always positive, and the comparison would then
be between animals which were in similar constant phototropic states.
If such were done, the proportion of turnings to the larger light would
be greater for Acris (as based on Series D) than for Vanessa, and in so
far might perhaps be interpreted as indicating the formation of more
distinct and better images of the lights on the retinae of the former
than the latter.

Parker (:03*) proved that li. ininens. is as a rule positively photo-
tropic to stimuli received by the skin, as well as to those received by the
eyes. The idea suggested itself of using Parker's methods and testing
in Acris the effect of the large and small lights when falling (a) upon
the eyes alone, the skin being protected from the light, and (b) upon the
skin after the optic nerves had been cut. If the persistent turning of
the normal frog toward the large area of light was to be attributed to
the ability of the eyes to form images of the lights, it would be expected
that frogs with the skin protected from the light would still react as
before, so long as vision with the eyes was unimpaired. On the other
hand, an eyeless frog — or what amounts to the same thing, one in
^v•hich the optic nerves had been severed — might be compared directly
with an earthworm, so far as its light-perceiving abilities are concerned.
It has only the general integument for the reception of photic stimuli,
and while, as in the earthworm, this is undoubtedly sensitive to
differences of intensity, there is no more reason to suppose that it
would enable the animal to discriminate between different areas of
like intensity but unequal size than in the case of the worm.

In making the test with the eyes exposed and the skin covered the
method employed by Parker was followed in detail. The skin was
removed in one piece from a large, dark-colored individual, turned
inside out, and drawn over a slightly smaller specimen which was
known to be active and strongly positive in its reaction to light. In
addition to the eyes, the snout and fore and hind feet were exposed to
the light. Only a single individual was used for this test, but the
nature of its responses was so decided that further experiments did not
seem necessary. When exposed as the normal frogs had been, to the
influence of the two lights, it turned toward the larger in 11 out of 14
trials, about as large a proportion as was obtained with normal animals.
The frog was much slower in its reactions than it had been previous to

398

PROCEEDINGS OF THE AMEllICAN ACADEMY.

having the skin of the other specimen slipped over it, not responding
within two minutes in more than half of the trials, so that it had to be
started by mechanical stimulation. As a check experiment, the
enveloping skin was now drawn forward so that it covered the eyes as
well as the rest of the body. The frog no longer turned toward the
large light, but, on the contrary, an unexpected result was obtained ;
for it now turned in nearly all cases toward the smaller light, when it

TABLE X.
Reactions of Acrts after the Optic Nerves had been cut.

Both Lights.

Small Light.

Individual.

Direction of Reaction.

Individual.

Direction of Reaction.

Lff.

0

Sm.

—

0

+

1
2
3
4

2

o
O

3

6
4

6

4

2
3

3

1
2
3
4

1
1
1
2

5
4
2

2

4

15
1
6

Totals

8

20

8

• •

5

13

26

would have been expected to be indifferent, since both skin and eyes
were protected from the light. A larger series of experiments might
have explained this apparent anomaly,^ but by this time the specimen
had become exceedingly sluggish and inactive, and it was believed that
the results obtained sufficiently demonstrated that Acris discriminated
between the two areas by means of the light from them that entered
the eyes.

It now remained to test animals by exposing their skin to the full

8 Two pos.sible explanations of what may have caused the results obtained
suggest themselves : (1) The portion of skin covering the eye toward the small
light may have been more pervious to light than that over the other eye, due to
its having been stretched more tiglitly, to a difference in pigmentation, or
possibly to injury, such as an abrasion or a small perforation; or (2) it maj"^ be
that the light from a small area such as was used may have a greater penetrating
power through a membrane of this character tlian the more diffuse liglit from a
larger area.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 399

influence of the lights, after their eyesight had been destroyed. This
was accomplished by cutting the optic nerves, a simple operation,
performed by inserting the points of a pair of fine scissors just back of
the eyeball, through the membrane lining the roof of the mouth, and
severing the nerve where it leaves the eye. The frogs did not seem
to be greatly inconvenienced by the operation, and three of the four
individuals so treated appeared to be as active as before, except that
they did not respond so quickly to light. The fourth animal (No. 3
in Table X) was more sluggish and behaved much as frogs do that
have had the cerebral hemispheres removed. All the specimens were
so slow in turning toward the incandescent light which had been used
in the previous experiments for orienting the animals into the normal
position, that they were placed in the desired orientation by moving
the glass plate upon which they were sitting. This could not be
rotated directly to bring the frogs into position on account of the
compensating circus reflex which resulted, but the plate was moved
backward and forward in line with the longitudinal axis of the frog's
body a distance of about 15 cm., and each time was turned slightly
until the animal was finally oriented. In this way the greater part of
the motion was lengthwise of the fi'og, and the rotating was so slight
in comparison with the backward and forward movement that there
seemed to be no tendency to give the compensating reflex.

Individuals 1 and 2 usually turned in one direction or the other, or
hopped or walked ahead — in other words, gave some locomotor
response — within 2 minutes of the time they were exposed to the
lights. If not, they were stimulated by touching them from behind.
As has been mentioned. No. 3 was inactive and slow to react, while
No. 4 was intermediate between No. 3 and the other two. In
cases where the animal hopped or walked ahead without turning at
least 45° in one direction or the other the record was taken as indiffer-
ent, and is included in the column headed 0 in the table.

The left half of Table X summarizes the reactions to both lights of
the four individuals with the optic nerves cut. The larger part of the
records (20 out of 36) were indifferent ; but it is a curious fact that
each individual turned exactly as many times toward one light as
toward the other. In all there were 8 turnings toward each lamp.
This shows a perfectly indifferent condition, and demonstrates that
Acris is unable to discriminate by means of the skin alone between
luminous fields of different size where the intensity of the light fi-om
each falling upon the animal is the same.

In order to make certain that the skins of these animals were sensi-
tive to light, the same individuals were finally tested with the small

400 PEOCEEDINGS OF THE AMERICAN ACADEMY.

light alone. The results of this test are recorded in the right half of
Table X. It will be seen that each individual gave a preponderance
of reactions toward the light, except No. 3, which turned once in each
direction, and twice went ahead without turning. Three of the frogs
were thus undoubtedly positively phototropic to light stimuli received
by the skin, and the inherent inactiveness of No. 3 has already been re-
marked. From the totals it is seen that out of 44 trials 26, or more
than half, were positive, or toward the light, 5 negative and 13
indifferent.

From the foregoing experiments it seems that the following con-
clusions may legitimately be drawn :

1. Acris gryllm is preponderatingly positively phototropic, though
there is some inconstancy in the reactions of the same and of
different individuals, depending upon unascertained factors.

2. Exposed to luminous areas of different size but equal intensity,
it turns in by far the greater number of trials toward the larger of the
two areas.

3. The result is substantially the same when the skin of the
animal is protected from the light, but the eyes are exposed.

4. Acris deprived of sight by severing the optic nerves, but having
the skin exposed to the light, is indifferent to the size of the luminous
field.

5. From this it follows that the discriminating power as to the dif-
ferent areas lies in the eyes, and is the result, it is safe to infer, of
the ability of these organs to form comparatively clear images of
external objects.

6. Acris with the optic nerve severed is still positively phototropic,
but in this case, where the light must be perceived by the skin, its
condition as regards image-formation and the consequent ability to
discriminate between luminous areas of different sizes is directly
comparable to that of an eyeless animal, such as the earthworm.

12. Green Frog {Rana clamata Daudin).

A number of experiments of a similar nature to those last described
were made with the green frog for the purpose of comparing its reac-
tions with those of Acris. The general method employed was the
same, but differed slightly in details. The frogs were placed beneath
a glass box 10 cm. X 12.5 cm. X 10 cm. high, and an attempt was made
to get them to orient in the normal position by means of the incandes-
cent lamp, as was done with Acris. They were so slow in respond-
ing, however, that it was found more expedient to raise the box and

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 401

orient them with the hand. Care had to be taken to avoid a one-
sided turning due to circus compensation or thigmotactic stimuli
received by this act, and in order to guard against such results the
animal was left sitting screened from the lights for a period of 15
seconds to 80 seconds after it had been placed in orientation ; if
it had not moved by the end of that time the screens were removed,
exposing it to the lights from the two fields.

Rana clamata was found to be much slower in its reactions than
Acris. It was usually given 5 minutes in which to react, and if at
the end of that period it had not moved, it was induced to do so by
means of an electrical stimulus applied to its lower side. This was
accomplished by having the board on which the fi"og was placed
crossed by fine parellel copper wires 1 cm. apart, alternate wires being
connected respectively to the opposite poles of a single " Columbia
Dry Cell No. 6." By means of a simple " key " placed in the circuit
the frog sitting on the wires was stimulated by the " make " and
" break " of the current whenever the key was pressed down and re-
leased. This method was used rather than simply touching the ani-
mal from behind, as it was believed that there was less chance of the
stimulus being one-sided, and because no movement of the operator
was necessary in the field of vision of the animal. On the whole it
was found to work very satisfactorily.

The results need not be given in detail, but may be stated briefly
as follows :

1. As stated by Torelle (: 03), Baiia clamata is positively photo-
tropic in nearly all cases at the ordinary temperature of the room
(about 20° C).

2. Such positive individuals, when exposed to the two light areas
of different size, turned in the great majority of cases toward the
larger light. This result agrees with that obtained with Acris, but as
would be expected from an animal which responds less quickly and
definitely to a single light, the proportion of the turnings to the large
light was not so large.

3. At low temperatures (6° C. to 10° C.) the frogs were usually
negative in their responses to a single light, or at least were indifferent
or inconstant in their reactions ; and in accordance with this

4. Such individuals turned toward the smaller of the two lights, or
were inconstant and gave inditferent results under these conditions as
with the single light. This last result was first obtained from a speci-
men which was brought into the experimenting room from a tank in
which the water registered 8° C. and was at once tested with the two
lights. Its first 8 reactions were all toward the small light, after which

VOL. XLIl. — 20

402 PROCEEDINGS OF THE AMERICAN ACADEMY.

it turned in most cases toward the larger area. Out of 32 trials fol-
lowing the first 8, 22 were in this direction. By the time the first 8
trials had been made the frog had been in the warm room for a half
hour or more, and it seemed reasonable to assume that the change
in its reactions was due to its having become warmed up to the room
temperature. Further observations tended to confirm this conclusion ;
and this agrees with the results obtained by Torelle (:03), who says,
(p. 487): "A rise in the temperature to 30° C. accelerates the rate of
the positive response. A lowering of the temperature to 10° C.
produces movements away fi'om the light."

IV. General Considerations and Discussion.

Conclusions as to the degree of the ability possessed by the vari-
ous animals studied to form images, as inferred fi-om the results of
the experiments, have been stated in connection with the description
of the experiments upon each animal employed. It still remains to
consider certain general phases of the subject : to examine the rela-
tionship existing between the natural habits of the animals and their
reactions to the two lights ; to determine, in so far as possible, what
part their phototropism — especially in its relation to luminous areas
of different sizes — plays in their ordinary activities ; and to attempt
to trace, as well as can be done with the limited data at hand, the
probable steps which have led to the development of highly specialized
organs capable of forming richly detailed images of external objects.

It is a noticeable fact that those forms which showed by their re-
actions the most evidence of discrimination between the two lights
(viz., Vanessa, Ranatra, and the two species of frogs) are all positive
in their ordinary phototropic responses. On the other hand, the
earthworm, the land planarian, the mealworm, the sow bug, and the
cockroach — all of which showed little or no ability to discriminate
between the different areas, but responded almost entirely according
to the relative intensities of the lights — are all ordinarily negative-
When one remembers that all the animals in the second group live
either in the ground, or beneath stones, logs, or similar objects, or in
other dark places, the nature of their responses is not surprising. For,
whatever view may be held as to the way in which adaptation may
have come about, it is undeniable that organisms are adapted to their
ordinary conditions of life ; consequently it would not be expected that
those which live in darkness, or in very dim light, would be so likely
to be provided with image-forming organs, since for these they would
have little or no use. The ability to distinguish light from darkness is^

COLE. — IMAGE- FORMING POWERS OF VARIOUS TYPES OF EYES. 403

however, important to them, since it aids them in remaining concealed,
and is thus of service in protecting them from enemies to which they
would be exposed if they came into the light, and in preventing them
from going into situations that would be unsuitable in other respects
(lack of moisture, etc.). The negative reaction to light is not, however,
the only form of response to change in environmental conditions which
operates to keep these animals in their accustomed habitats ; responses
to contact stimuli, to moisture, temperature, and other variable condi-
tions, are often undoubtedly of as much, if not, indeed, of greater impor-
tance. Such, for example, must be the case, as pointed out by Loeb
('90, p. 51), in the larva of the willow-borer, which lives in a dark
situation, but is, nevertheless, positive in its reaction to light when
exposed to its influence. It is not necessary to enlarge upon the
advantages which the ability to perceive distant objects (i. e., those
with which the oganism does not come in direct contact) in their
proper spacial relation gives to animals living in the light. An organ-
ism, by means of what we ordinarily speak of as " sight," is brought
into close relation with a part of its environment which organisms
wanting this faculty have no means of appreciating. This obviously
is of distinct advantage. As the converse of what has just been said
about dark-inhabiting forms, it may be expected that those normally
living in the light are as a rule positively phototropic, and this seems
in general to hold true. Where a change in the character of the pho-
totropic response takes place, — as is the case in many animals which
are under certain conditions positive and under others negative, — it
is probable that this change can in most cases be explained by the
natural habits of the animal. Different factors may operate to bring
about this change of reaction ; it may be mechanical stimulation, a
variation of temperature, or a change in the intensity of the light itself.
The result, in many cases at least, is to bring the organism into an
optimum condition, either as to light intensity or some other stimulus.
The frog (Rana), for example, becomes negative to light at tempera-
tures below 10° C, and this response is probably an important one
under natural conditions in inducing the animal to swim downward
to the bottom of the pond and bury itself on the approach of cold
weather.

We do not need to concern ourselves at this point with the theories
as to how this adaptation has come about. It is sufficient to show
that such adaptation exists. It may be asked whether certain animals
have become negatively phototropic because they live in dark places,
or whether they live in dark situations because they are negative in
their reactions to light. The two probably have developed together.

404 PROCEEDINGS OF THE AMERICAN ACADEMY.

An animal is dependent upon certain reactions to its environment to
keep it in the proper conditions for its best welfare, and in many cases
the response to light is without doubt of great importance in this re-
spect. It is questionable whether a Bipalium, for example, were it
positively phototropic, could long survive unless it had developed in
addition to its phototropism some other form of response that would
prevent its going, under the influence of the light, directly into the
most unfavorable conditions. Loeb ('90, p. 51) stated that, so far as he
had found, all larvae of Lepidoptera were positively phototropic, even
including the willow-borer, which, as previously mentioned, like most
negative animals, lives naturally in a situation with little or no light.
It would seem that we have here a case of secondary adaptation ; the
willow-borer, we may infer, has become adapted to living in a dark
situation in spite of its positive phototropism. It comes from a group
of animals uniformly positive in their reactions to light, and has prob-
ably inherited this character from its positively phototropic ancestors.
We have seen that as a rule animals like the earthworm and Bipalium,
which live in dark situations, lack image-forming eyes ; at least such
is the inference from the reponses of these forms to equal illumination
from areas of different size. It has been pointed out that the posses-
sion of such eyes could be of no use to them in the dark ; and it is
likewise obvious that the simpler organs are equally effective in pre-
venting the animals from straying out into the light. All that is
necessary for them is to avoid light altogether. This can be done,
however, with greater precision when the organism is able to appreciate
more exactly the direction from which the light comes. The earthworm
probably has little power of discrimination in this respect beyond recog-
nizing upon which side the source of light lies, — on its right or on its
left, — according to whether its right or its left side is illuminated.
Bipalium, on the other hand, by the arrangement of many of its eyes
around the anterior margin of the semicircular head, is able to deter-
mine the direction of the light more accurately, and consequently shows
a (quicker and more precise response by moving directly away from it.
Similarly, in the mealworm, the sow bug, and the cockroach, the eyes
are probably little more than "direction eyes."

The experiments on Helix failed to give any decisive evidence as
to the ability of these animals to discriminate between the two areas.
Nor do the observations of Mitsukuri (:0l) and Bohn (:05) help us
much in this respect, since neither of these authors discriminated
between the size of the areas and the relative intensity of the light
received from them. Bohn studied the reactions of Littorina when
vertical screens, both black and white, were placed in the illuminated

COLE. — IMAUE-FORMING POWERS OF VARIOUS TYPES OF EYES. 405

field, and speaks of these animals as being "attracted " by the one and
"repulsed" by the other. This terminology is rather misleading. It
should be remembered that every object upon which the light falls and
irom which it is retlected becomes thereby a secondary source of light
and must be so treated ; its size is therefore of importance as one of
the factors in determining the total amount of light which it reflects.
If the surface is what we ordinarily term black, it reflects very little
light, and its position may consequently represent the region of lowest
light intensity in the whole illuminated field. A white screen, on the
other hand, may reflect practically all the light that falls upon it ; and
if of large size, it is reasonable to predict that upon such animals as
Vanessa, Ranatra, and the frog it would exert a greater influence than
the source from which the light primarily came, provided the latter
were of relatively small area. Thus, if the light from a projection
lantern were thrown upon a large white screen and one of the above-
mentioned animals were placed midway between the screen and the
lantern, one would expect, fi-om the results of the experiments per-
formed on these species, to see the animal turn toward the large area
of light, viz., the screen.

Loeb appears not to have considered in his experiments light re-
flected from surrounding objects, but in speaking of light coming from
more than one source, he says (Loeb :05, pp. 61, 62): "When the dif-
fused daylight which struck the [fly] larvae came fi'ora two windows
the planes of which were at an angle of 90° with each other, the paths
taken by the larvae lay diagonally between the two planes ; " but in
other places (c/! :05, p. 2, footnote) he states specifically that "if
there are several sources of light of unequal intensity, the light with
the strongest intensity determines the orientation and direction of mo-
tion of the animal ; " in this case apparently the animal ignores the
influence of the other lights altogether.

Miss Towle (:00, p. 365), in her work on Cypridopsis, found that
these animals took a diagonal course due to light coming from other
directions beside the main source, and decided that "the resultant
direction [which the animal would take] could be found by compound-
ing all these forces if their direction and relative value were known."
The same question was later examined carefully, critically, and in an
able manner, by Holt and Lee (^01) ; but in both these papers only
the intensity of the various light components was considered, no ac-
count being taken, even in the theoretical discussion, of the possible
influence of the size of the areas of the various light-sources.

In his study of Littorina, Bohn (:05, pp. 28, 29) puts the matter the
other way about and uses the direction taken by the animals (their

406 PROCEEDINGS OF THE AMERICAN ACADEMY.

" trajectories ") as an indication of the resultant of the light forces ; ^
their paths he takes as indicating "veritable lines of luminous force."
This comes very close to reasoning in a circle, and is at best merely
qualitative, since he has not attempted to make a physical determi-
nation to verify his contention that the direction taken by the ani-
mals does really coincide with the resultant of light intensities. If
Littorina responds only to the intensity of the light, we should expect
that its course, in an illuminated field of this nature, would coincide
with the resultant of the light intensities, could such be determined
by physical measurements ; but if, like Vanessa, it reacts differently to
different areas, not in proportion to the intensity of the light received
from them, but according to their extent, the direction taken by the
snail would probably deviate accordingly from the resultant of intensi-
ties. It seems impossible to decide from the results either of Bohn or
of Mitsukuri (^Ol), whether Littorina reacts to differences of inten-
sity only, — the size of the screens or other objects in the field being
of importance merely in determining the amount of light reflected or
absorbed, and thus influencing the direction of the resultant "lines of
luminous force," — or whether, like Vanessa, it may react to the areas
according to their size, more or less irrespective of the intensity of light
received from them. Whichever may be the case, Bohn (:05, p. 30)
has pointed out that the shaded surfaces of rocks act in the same way
as black screens, and that when a Littorina is in the vicinity of two such
shaded areas it does not go directly toward either, but strikes a course
which is a mean and eventually leads it into the crevice between the
rocks. ^° This is apparently another case where the reactions of the
animal to light are well adapted to its needs, since the snails are un-
doubtedly much better protected in the crevices than they would be
upon the exposed surfaces of the rocks.

To animals commonly living in the light the possession of eyes
capable of forming images must be of distinct advantage. Neverthe-

9 " En un point donne d'un champ lumineaux la direction du champ n'est que
la direction de la resultante de toutes les forces attractives et repulsives excrceos
par les surfaces c'clairantes, surtout par les surfaces les plus e'tendues, les plus
liautes (fenetres, murs)."

" " Chaque surface d'ombre exerce une attraction proportionellement a son
ctendue, et I'animal suit une direction qui est celle de la re'sultante des forces
attractives. En particulier, quand une littorina se trouve dans le voisinage de
deux rochers prc'sentant des surfaces d'ombre d'e'tendue par trop ine'gale, elle
prend une direction qui est celle de la dingonale du paralli'logramme des forces
attractives, et ainsi il lui arrive de se mouvoir vers un espace compris entre les
deux rochers et de ne rencontrer ni I'un ni I'autre, bien qu'attiree par I'un et par
I'autre."

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 407

less, there are uumerous examples of positively phototropic forms whose
reactions to light tend to carry them always into regions of greater
illumination, but whose eyes are probably of little use beyond deter-
mining the direction and the relative intensities of lights. Here, again,
there appears to be a correlation between the habits of the animals and
the conditions under which they live, for an inspection will show that
these are usually creeping forms whose movements toward the light take
them in the direction of their food, or else that other conditions prevent
their phototropism from taking them into unfavorable surroundings.
The caterpillars of Porthesia (and probably of most other Lepidoptera)
may be taken as an example of the former. Although no tests have
been made on these forms to determine their ability to discriminate
between luminous areas of different size, the rudimentary condition of
their eyes, and the experiments with beetle larvae {cf. Tenebrio) make
reasonable the assumption that they respond only to the intensity
of the light reaching them, and not to the size of the area whence it
immediately comes. Under ordinary conditions, in the sunlight, the
largest patches of light are on the ground ; but the strongest intensity
is skyward, and responding to this, as soon as hatched, the young
caterpillars of Porthesia crawl upward and outward on the branches
until the reaction to food overcomes their phototropism, or they are pre-
vented from going farther by reaching the tips of the branches. In
these two ways their progress skyward is checked at the proper time.
In a similar manner positively phototropic snails or other crawling
forms are restrained by the natural conditions from continuing indefi-
nitely their migrations in the direction of the greatest illumination.
Parker (: 03, p. 462) has called attention to the fact that the surface of
the water forms a similar barrier to certain marine organisms (such
as the copepod Labidocera) which swim upward through the water
toward the light.

With forms which fly, and so, being independent of solid objects upon
which to crawl, are not limited in the distance which they might move
upward, the case is entirely different. A query which Romanes ( '83,
p. 279) found among Darwin's manuscript notes shows careful obser-
vation and puts the question very clearly. It is as follows : " Query.
Why do moths and certain gnats fly into candles, and why are they not
all on their way to the moon — at least when the moon is in the horizon %
I formerly observed that they fly very much less at candles on a moon-
light night. Let a cloud pass over and they are again attracted to the
candle." Romanes thinks the answer is that "the moon is a familiar
object, the insects regard it as a matter of course, and so have no
desire to examine it." As a result of Parker's work on Vanessa and

408 PKOCEEDINGS OF THE AMERICAN ACADEMY.

those of the present investigation, however, we are able to give another
and, it would seem, a more reasonable explanation. The moths and gnats
referred to react, like Vanessa, to large areas of light rather than to a
point of more intense light. As a consequence they remain near the
ground, on account of the bright patches of moonlight, instead of flying
toward the moon itself. If, however, they come close to a candle, its rel-
atively great intensity at so short a distance may overcome the reactions
to the moonlit areas, and the insects accordingly fly into the flame.
This is especially the case, as recorded in the note, when the moon
is obscured by a cloud and the patches of moonlight disappear.

Parker (:03, p. 461) has pointed out, furthermore, that the alighting
of Vanessa in sunny spots with the wings expanded is probably an
adaptation which serves to bring the sexes together ; for it is in this
position, headed as it always is away from the sun, that the colors
and markings of the upper surfaces of the wings are most conspicuous.
He adds, "I am sure from direct observations that females, as well as
males, will circle around an oriented and expanded individual of either
sex, till both fly off together." The recognition by one butterfly of
another as a definite object in its field of vision indicates a much finer
perception than that which distinguishes merely the diff"erence of size
in illuminated areas, and approaches to the highest type of vision.
Although no experiments were made which bear directly upon this
point, it is, nevertheless, worthy of brief consideration.

Nuel (: 04) speaks of "la perception simultanee des fins details des
objets visuels " as " iconoperception" (p. 82), and of the resulting re-
actions as " icono-rdactions." ^^ He says (p. 83): " Chez les animaux,
nous ne parlerons pas d'iconopsie, mais d'icono-rdactions, dans la cas
ou, comme chez I'homme, des mouvements sont suscitds ou guid(^s,
rdglds par les fins details visuels des objets." As the perception of
the details of the objects in the general image of the visual field be-
comes more refined, the reactions to these objects, or to certain partic-
ular ones of them, appear largely to inhibit the reactions to light in
o-eneral, including that to large areas as contrasted with small. Besides
the case of Vanessa, mentioned above, it seems certain that many
Lepidoptera and bees react to certain flowers, while many predacious
insects, such as the dragonflies, are remarkably quick in detecting their
prey. That color is not, in all cases at least, the determining factor in

" The words ironotropism and iconotaxls would oorresi)ond with tlie terms more
generally employed, such as phototropism and phototuxis, and miy,ht be employed
to designate specifically the reactions of animals to areas of light and to objects
in the field of vision, in contradistinction to reactions to the intensity of the
licht.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES, 409

these responses, is indicated by such observations as that of Latter ( : 04,
p. 88), who "once observed a brimstone butterfly visiting flowers of the
Dog Violet scattered along a bank, and picking out these flowers to the
exclusion of all others with gi-eat precision, not approaching even other
blue flowers that were present." The description of the feeding of
Ranatra by Holmes (-.05* p. 325) furnishes an excellent illustration
of the inhibition of the ordinary phototropic responses by attention
to particular objects in the visual field. Holmes's description is as
follows: "The phototactic response may also be inhibited by efforts
to obtain food. Ranatra which are swimming towards the light can
often be caused to discontinue their phototactic efforts if several
small insects are placed near them. If the phototactic activities are
very lively and vigorous, it is more difficult to divert the attention of
the insect to the capture of prey. When attention is once directed
to seizing the smaller insects, the light is disregarded. When the
prey has once been captured and tfie Ranatra is engaged in sucking
out its juices little attention is paid to the light. The repast being
finished the insect may resume its positive response."

Attention to moving objects would appear to be more general than,
and probably precedes, the response to stationary objects. This is well
illustrated in the feeding habits of frogs, toads, and many lizards,
which seldom or never notice an insect so long as it is quiet, but are
attracted by it at once if it moves. An object moving in the field of
vision may, however, affect the elements of the retina in ([uite another
way than does an object which is stationary ; for, unless its color
intensity is uniform with that of its background, its movement must
produce a change in the intensity of the light reaching certain of the
visual elements in the retina, and the response may be to this change in
intensity rather than to a definite and clear-cut perception of the object
as such. The question of how far animals are able to, and do, distinguish
stationary objects is rather a difficult one to solve. As has just been
said, it is well known that frogs react to small moving objects, such as
insects, which constitute their food. It is also a matter of common ob-
servation that if a ft'og sitting on the bank of a stream or pool is disturbed,
it ordinarily jumps at once in the direction of the water, even if it is
approached from a direction parallel to the shore line. The question
arises as to whether the frog recognizes the water by its appearance or
whether the response is merely a reaction to a larger area of illumina-
tion. For it seems (^uite certain that the open water and sky on the
one hand must in general form a larger area of illumination than the
bank, with usually tall grass, bushes, or similar dark objects, on the other.
We have seen (p. 39 o) that, although a frog may sit for a considerable

410 PROCEEDINGS OF THE AMERICAN ACADEMY.

time in a position without apparent orientation to the light, if it is
disturbed it usually turns at once and jumps toward the light; and if
there are two areas of illumination of different size, it turns toward
the larger. Is, then, its ordinary response of jumping toward a pool
or stream to be considered as a simple reaction of this kind ? It will
be seen that this is similar to what, in Mitsukuri's ( : 01) opinion, de-
termined the shoreward migration of Littorinas. A series of observa-
tions was started in connection with the present investigation in an
attempt to determine the question for the frog, but as yet a sufficient
number of experiments has not been made to settle the matter defi-
nitely. It need only be said that so far as they have gone, the results
appear to indicate that the reaction is not so simple as has been
suggested — that apparently the objects in the visual field exert an
influence beyond that merely of the amount of light received fi-om any
direction, or of the size of the area fi:om which the light is received.

In those higher animals whose actions correspond still less to simple
reflexes, as acute vision (the perception of details in the visual field)
becomes more perfectly developed, simple phototropic responses become
more and more a secondary matter, until they appear to be entirely
absent, or at least are not recognizable as such. Birds give evidence
of possessing especially acute vision, and under ordinary circumstances
certainly show no evidence of simple phototropic responses ; but the
way in which migrating birds often, on stormy nights, gather about
lighthouses and dash into the glass only to be killed, recalls strongly
the flying of moths into a flame, and it seems possible that this is an
expression of phototropism in birds which is ordinarily inhibited by
other responses.

Finally, in recapitulation, we may distinguish roughly the following
four stages or types of reactions of animals to stimuli received by the
photo-receptive organs.

Type A. Response of eyeless forms.

These are in general given by animals which live in dark situations
and are negatively phototropic to light of ordinary intensity, though
they may (e. g., earthworm) be positive to lower intensities. Some,
such as Hydra (Wilson, '91), are positive to light of ordinary intensity.
The reactions of a frog with optic nerves cut are essentially those of
a positive eyeless form. Animals in this group respond only to light
intensities.

Type B. Response of forms with " direction eyes."

Animals with eyes of tliis type also react to light intensity only, and
are more commonly negative ; but some of them, such as many Cope-

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 411

pods, larvae of Lepidoptera, etc., are positive ; these are commonly
limited, however, iu their movements toward the light by physical
conditions, which either bring them into favorable relations with their
surroundings (e. g., to their food supply), or at least prevent their com-
ing into unfavorable conditions.

Type C. Response to size of luminous field.

The animals which give this t}T^)e of reaction appear to be usually
positive to light of ordinary intensity, in which case, other things being
equal, they turn toward the larger of two areas of illumination. Some
of them (e. g., Ranatra and the frog) under certain conditions change
the character of their response, and probably turn oftener to the smaller
light than to the larger one, though not enough observations have been
made to settle this point conclusively. It is probably only when the
animals are positive that the reaction to the size of the illuminated
area is adaptive.

Type D. Response to definite objects in the visual field.

This form of response includes what we ordinarily mean by the
term "vision." As Nuel ( : 04, p. 10) says, " Le mot 'voir' supposant
generalement une distinction visuelle et une representation visuelle et
psychi(iue des objets." The responses to definite objects are not
often in the nature of simple reflexes, but are complicated by psychical
processes. In most cases they inhibit direct phototropic response,
which may be in evidence at certain times only (as in Ranatra and the
frog, and possibly in birds), or may apparently be absent altogether.

In the lower forms we speak of these responses as phototropic reac-
tions, photo-reactions, or simply reactions to light ; in the higher forms,
whose reactions give evidence of being governed, or at least influenced,
by definite objects in the visual field, they are usually termed vision.
These stages, at least in the examples adduced, must not be taken as
representing a genetic series. They shade insensibly into one another,
and we have seen how some forms, such as the fi-og, for example, may
give responses which fall into two of the classes. The ordinary re-
sponses of the frog to light which enters its eyes fall under what is
termed Tj'pe C, and to an undetermined extent under Type D. But
when the optic nerves are cut, so that the eyes no longer function,
the frog still reacts to light, its responses falling under Type A . Can
we say that the frog's " sight " has been destroyed then by cutting the
optic nerves ? It still is responsive to directive light much as it was
before. Certainly the commonly accepted usage of the terms " sight "

412 PROCEEDINGS OF THE AMERICAN ACADEMY.

and " vision " would not cover the responses to light perceived by the
integument, and it would perhaps be better to employ for the whole
series the terms "photo-reception" and "photo-reaction," which have
recently been proposed (see Beer, Bethe u. Uexkiill, '99, and Nuel, :04).

Although, as has been said, this classification cannot be taken as
representing a genetic series, nevertheless it does indicate in a rough
way the steps which have probably led up to the possession of the
highest type of vision. The classes as here established are far from
distinct, and especially is this true of the last two, which necessarily
must depend in part upon each other. However, the form of response
outlined under Type G is in general more primitive than that under
D. It depends upon a definite phototropic reaction, and as more
acute vision is gained phototropism becomes inhibited more and more
until it apparently disappears.

No experiments were made to test color perception and its relation
to image-formation. This is an extremely difficult field, since it is.
well-nigh impossible to get an objective criterion as to whether animals
perceive color as it is interpreted by the human eye, or whether colors
represent to them merely differences in light intensity.

V. Summary.

In the study of the reactions of certain animals to two lights of
different areas, the one 41 cm. square, the other only one ten thousandth
as much (for all practical purposes a point), the two lights were always
adjusted so that they gave an equal intensity of light at a plane mid-
way between them — the plane of experimentation. This intensity
varied from about 5 candle meters to 1.25 candle meters. A summary
of the principal results obtained is as follows :

1. The earthworm {Allolobopkora foetida) was negative in its re-
sponse to either of the two lights used separately ; to the two lights
used simultaneously it was indifferent, turning almost exactly as
many times in one direction as in the other. Allolobophora therefore
apparently responds only to the intenxttn of the light.

2. Bipallum keivense was similarly negative to either light used
singly. To the two lights operating at the same time it was nearly
indifferent, but showed a slightly larger number of turnings away from
the larger light ; this may indicate a slight ability to discriminate
between the lights, and if so, it is probably owing to the arrangement
of the eyes around the periphery of the semicircular head.

3. The mealworm (larva of Tenehrio molitor) was decidedly negative
in its reactions to the lights employed separately. As inferred from its
reactions to the two lights acting simultaneously, — the turnings to

COLE. — IMAGE-FOlimNG POWERS OF VARIOUS TYPES OF EYES. 413

■and from the large light being equal in number, — its eyes have no
ability to form distinguishable images of objects which differ from each
other in size no more than did the two lights used.

4. Onisciis asellus was found to be negative to light of the intensities
mentioned. Its responses to light are not so definite as those of
the larva of Tenebrio, but there is some evidence that it has a some-
what greater power of discriminating between the two lights acting
simultaneously.

5. The cockroach (J^eriplaneta americana) is decidedly negative to
light from one side, but the reactions to the two lights used simultane-
ously showed an almost indifferent condition. The excess of 4.5
per cent of the reactions was on the side of motion toward the larger
light, whereas one would have expected that if there were any differ-
ence there would have been a predominance of reactions away from the
larger light. This is possibly to be explained as due to other
disturbing factors.

6. The mourning-cloak butterfly {Vanessa antiopa^ is uniformly
positive in its -locomotor reactions to unilateral illumination. Exposed
to the simultaneous influence of both lights, it went in 87.2 per cent of
its responses toward the larger light, thus confirming Parker's con-
clusion that this insect responds to the size of the illuminated area
rather than to the intensity of the light received from it.

7. Ranatra fusca varied in the character of its response to unilateral
illumination ; but, as far as possible, only positive individuals were
employed in the experiments with the two lights used simultaneously.
It was found that Ranatra gave a somewhat smaller proportion of
turnings to the larger light (70.6 per cent) than did Vanessa ; but
it is believed that this may be due to the inconstancy of the phototropic
states of Ranatra, rather than to less efficiency of the eyes in forming
images of the two lights.

Individuals with the posterior half of the eyes blackened went
straight ahead, without hesitating, toward whichever light they chanced
to face ; when the anterior half of the eyes was blackened, they kept
turning from one light to the other, since the only one from which
light could enter the eyes was always the one behind the insect.

8. The pomace fly {Dj-osnphila ampelophiki) gave only negative
results, owing, apparently, to technical difficulties in the experiments.

9. Helix p>omatia did not prove to be a good form for the purpose
of these experiments, on account of the inconstancy of its phototropic
state. So far as the experiments went, they pointed to the conclusion
that the eyes are of little or no use in enabling this animal to discrimi-
nate between the sizes of the luminous areas employed.

414 PROCEEDINGS OF THE AMERICAN ACADEMY.

10. Llmax maximus, on account of the inconstancy of its photo-
tropic responses, was fourd to be unsuitable for these experiments.

11. The results of the experiments upon the cricket frog (Acris
gryllus) will be found concisely enumerated on p. 400.

12. The results of the experiments upon the green frog {Rana
clamata) are enumerated on p. 401.

13. The animals which showed by their reactions the most evidence
of discrimination between the two lights (viz., Vanessa, Ranatra, and
the two species of frogs) are all positive in their ordinary phototropic
responses.

14. The negative animals experimented upon (earthworm, land
planarian, mealworm, sow bug, cockroach) showed little or no ability
to discriminate between the two areas of illumination, but appeared to
respond almost entirely to the intensity of the lights.

15. These reactions are correlated with the natural habits of the
animals.

16. There are certain positive forms (especially larvae of Lepidop-
tera and certain marine Copepoda) which apparently respond to light
intensity only ; but these are prevented by the conditions under which
they live from being brought into unfavorable circumstances by their
movements toward the light.

17. The responses of animals to light may be divided roughly into
the following types:

Type A. Response of eyeless forms. Usually negative ; sometimes
positive, and then usually to very weak light. Respond to intensity of
light only (e. g., earthworm).

Type B. Response of forms with ^^ direction eyes." Usually negative
(e. g., Bipalium, Periplaneta, Tenebrio larva) ; sometimes positive
(e. g., larva of wood-borer), in which case special adaptation prevents
their following the light until it brings them into unfavorable
conditions. Response almost wholly to intensity of light.

Type C. Response to size of luminous field. Animals usually
positive, though they may be temporarily negative, as was seen to be
the case with the frog, for example. Probably the response to the size
of the field is adaptive only when they are positive.

Type D. Response to definite objects in the visual field. Not simple
reactions ; responses usually involve psychic phenomena. Respond
(1) to moving objects, (2) to stationary objects. This form of response
usually inhibits ordinary phototropic reactions.

Types C and I) are developed together.

The types outlined above do not necessarily represent a genetic
series.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 415

VI. Bibliography.

Adams, G. P.

:03. Uu the Negative and Positive Phototropism of the Earthworm Allo-
hibophora foetida (Sav.) as determined by Light of Different Intensities.
Amer. Jour. Physiol., Vol. 9, No. 1, pp. 26-34.

Beer, T., Bethe, A., und Uexkiill, J. v.

"99. Vorschlage zu eiut-r ol>jectivirenden Noraenclatiir in der Pliysiologie
<l.-5 Nervensystemt!. Centralbl. f. Physiol,, Bd. 13, No. 6, pp. 137-141.
Bell, F. J.

'86. Note on Bipalium kewense, and the Generic Characters of Land-
planarians. Proc. Zobl. Soc. London, 18SG, pp. 166-168, pL 18.
Bergendal, B.

'87. Contribution to the Knowledge of the Land-Planariae. Ann. Mag. Nat.
Hist., Ser. 5, Vol. 20, No. 115, pp. 44-50. (Translated from the Zoolo-
gi.*cher Anzeiger, Bd. 10, No. 249, April 18, 1887, pp. 218-224.)
Bohn, G.

:05. Attractions et oscillations des animaux marines sous I'influence de la
luminere. Mem. In.st. general physiologique, Paris, No. 1, 110 pp.
Carpenter. F. W.

:05. The Reactions of the Pomace Fly (Drosophila ampelophila Loew) to
Light, Gravity, and Mechanical Stimulation. Amer. Nat. , Vol. 39, No-.
456, pp. 157-171.
Cole. L. J.

:01. Notes on the Habits of Pycnogonids. Biol. Bull., Vol. 2, No. 5,
pp. 195-207.
Darwin, C.

"44. Brief Descriptions of Several Terrestrial Planariae, and of some Re-
markable Marine Species, with an Account of their Habits. Ann. Mag.
Nat. Hist., Ser. 1, Vol. 14, No. 91, pp. 241-251, pi. 5, figs. 1-4.
Darwin. C.

"81. The Formation of Vegetable Mould through the Action of Worms,
with Observations on their Habits. New York, 8vo, viii -{- 326 pp.
Exner, S.

"91. Die Pliysiologie der facettirten Augeu von Krebsen und Insecten.
Leii)zig und Wien, 8vo, viii + 207 pp., 1 Lichtdruck und 7 Tafeln.
Frandsen, P.

:01. Studies on the Reactions of Limax maximus to Directive Stimuli.
Proc. Amer. Acad. Arts and Sci., Vol. 37, No. 8, pp. 185-227.
Graber. V.

"84. Grundlinien zur Erforschung des Helligkeits- und Farbensinnes der
Tiere. Prag, Leipzig, Svo, viii -{- 322 pp.
Harper, E. H.

05. Reactions to Light and Mechanical Stimuli in the Earthworm Peri-
chaeta bermudensis (Beddard), Biol. Bull., Vol. 10, No. 1, pp. 17-34.

416 PROCEEDINGS OF THE AMERICAN ACADEMY.

Hesse, R.

'96. Uiilersuchungen iiber die Organ e tier Lichtempfindung bei niederen
Thieren. I. Die Organe der Lichtempfindung bei den Liiml:)riciden.
Zeitschr. f. wiss. Zool., Bd. 61, Heft 3, pp. 393-419, Taf. 20.
Hesse, R.

'97. Untersuchungen, u. s. w. II. Die Angen der Plathelraintben, inson-
derheit der tricladen Turbellarien. Zeitschr. f. wiss. Zool., Bd. 62,
Heft 4, pp. 527-582, Taf. 27, 28.
Hoffmeister, W.

'45. Die bis jetzt bekannten Arten aus der Familie der Regenwiirmer.
Braunschweig, 43 pp.
Holmes, S. J.

:05. The Selection of Random Movements as a Factor in Phototaxis. Jour.
Conip. Neurol, and Psychol., Vol. 15, No. 2, pp. 98-112.
Holmes, S. J.

:05*. The Reactions of Ranatra to Light. Jour. Comp. Neurol, and
Psychol., Vol. 15, No. 4, pp. 305-349.

Holt, E. B., and Lee, P. S.

:01. The Theory of Phototactic Response. Amer. Jour. Physiol., Vol. 4,
No. 9, pp. 460-481.
Janichen, E.

'96. Beitrage zur Kenntnis des Turbellarienauges. Zeitschr. f. wiss. Zool.,
Bd. 62, Heft 2, pp. 250-288, Taf. 10, 11.
KUhne, W.

'79. Chemische A^'organge in der Netzhaut. Hermann's Handbuch der
Physiologie, Bd. 3, Theil 1, pp. 235-342.
Latter, O. H.

:04. The Natural History of some Common Animals. Cambridge [Eng.],
8vo, X -1- 331 pp.
Loeb, J.

'90. Der Helioptropismus der Thiere und seine Uebereinstimmung mit dem
Heliotropismus der Pflanzen. Wiirzburg, 8vo, 118 pp.
Loeb, J.

:05. Studies in General Physiology. Univ. of Chicago Press, Decennial
Publications, Ser. 2, Vol. 15, Part I, pp. i-xvi -|- 1-424, Part II,
pp. i-xiv + 425-782.
Mitsukuri, K.

:01. Negative Phototaxis and other Properties of Littorina as Factors in
determining its Habitat. Annotationes Zoologicae Japonenses, Vol. 4,
Part 1, pp. 1-19.
Moseley, H. N.

'74. On the Anatomy and Histology of the Land-Planarians of Ceylon,
with some Account of their Habits, and a Description of two New Species,
and with Notes on the Anatomy of some European Acjuatic Species.
Phil. Trans. Roy. Soc. Lond. for 1874, Vol. 164, pp. 105-171, pis. 10-15.

COLE. — IMAGE-FORMING POWERS OF VARIOUS TYPES OF EYES. 417

Moseley, H. N.

'78. Description of a New Species of Land-Planarian from the Hothouses at
Kew Gardens. Ann. Mag. Nat. Hist., Ser. 5, Vol. I, No. 3, pp. 237-239.
Nuel, J. P.

:04. La vision. BiMiotiifeqiie inluriiationule de Psychologie experimentale
noniial et pathologii[ue. Paris, 376 pp.
Parker, G. H.

'95. The Retina and Optic G-auglia in Decapods, especially in Astacus.
Mittli. Zool. Sta. Neapel, Bd. 12, Heft 1, pp. 1-73, Taf. 1-3.
Parker, G. H.

:03. The Phototropisni of the Mourning-cloak Butterfly, Vanessa antiopa
Linn. Mark Anniversary Volume, No. 23, pp. 453-469, pi. 33.
Parker, G. H.

:03*. The Skin and the Eyes as Receptive Organs in the Reactions of Frogs
to Light. Amer. Jour. Physiol, Vol. 10, No. 1, pp. 28-36.
Parker, G H.. and Arkin, L.

:01. The Directive Influence of Light on the Earthworm Allolobophora
foetida (Sav.). Amer. Jour. Physiol., Vol. 5, pp. 151-157.
Romanes, G. J.

'83. Mental Evolution in Animals. With a Posthumous Essay on Instinct
by Charles Darwin. Luudon, 8vo, 411 pp.
Sharp, [B.]

'91. On a Probable New Species of Bipaliura. Proc. Acad. Nat. Sci. Phil.,
1891, pp. 120-122.
Stern, R.

:05. Ueber Sehpurpurfi.xation. Graefe's Arch. f. Opthal., Bd. 61, Heff 3,
pp. 561-563. Abstract in Zeutralbl. f. Physiol., Bd. 19, No. 20, p. 757.
Torelle. E.

:03. The Response of the Frog to Light. Amer. Jour. Physiol., Vol. 9, No.
6, pp. 466-488.
Towle, E W.

:00. A Study in the Heliotropism of Cypridopsis. Amer. Jour. Physiol.,
Vol. 3, No. 8, pp. 345-365.
Wilson, E. B.

'91. The Heliotropism of Hydra. Amer. Nat., Vol. 25, No. 293, pp. 413-
433.
"Woodworth, W. McM.

'96. Notes on Turbellaria. 1. On the Occurrence of Bipaliuni kewense
(Moseley) in the United States, Amer. Nat., Vol. 30, No. 360,
l^p. 1046, 1047.
Woodw^orth, W. McM.

"98. On the Occurrence of Placocephalus (Bipalium) kewense in the Sand-
wich Islands. Science, N. S., Vol. 8, No. 192, p. 302.

VOL. xi.ii. — 27

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 17. — Januaky, 1907.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

EXPANSION AND COMPRESSIBILITY OF ETHER AND

OF ALCOHOL IN THE NEIGHBORHOOD OF

THEIR BOILING POINTS.

By Alpheus W. Smith.

Investigations on Lioht and Heat made and published, wholly ou in pabt, with Appeopbiatiow

from the rnuford fund.

EXPANSION AND COMPRESSIBILITY OF ETHER AND

OF ALCOHOL IN THE NEIGHBORHOOD OF

THEIR BOILING POINTS.

By Alpheus W. Smith.

Presented by E. H. Hall, May 9, 1906. Received October 30, 1906.
[For a summary of the results reached in this paper, see p. 458.]

Introduction.

This subject was suggested to the writer by Professor Hall, to whom
it became of interest in his work on the van der Waals a in ethyl
ether and in ethyl alcohol. In obtaining values of the van der "Waals
a by one of the methods employed in that paper ^ Professor Hall
found it desirable to know both the coefficient of expansion and the
coefficient of compressibility of these liquids just before they change
into the vapor state.

The investigators who have concerned themselves with the coeffi-
cients of expansion and of compressibility of liquids have for the most
part used large differences of temperature and of pressure in produc-
ing the change of volume in the liquid, so that every coefficient is
the average coefficient over a considerable range of temperature and
of pressure. Such data do not give us with certainty the coefficient
of expansion and of compressibility at a particular temperature and at
a pressure differing but little from the vapor pressure of the liquid
at that temperature.

I, therefore, undertook to find by means of new measurements both
the coefficient of expansion and the coefficient of compressibility of the
two liquids in question at pressures which were only slightly greater
and at those which were somewhat less than the vapor pressure of the
liquid at the temperature used, — i.e., the coefficient of expansion
and the coefficient of compressibility of these liquids just before they
reach their boiling conditions, and these same coefficients when the
liquids are in the superheated state.

1 Boltzmann-Festschrift. 1904.

422

PROCEEDINGS OF THE AMERICAN ACADEMY.

If T is the absolute temperature, p the external pressure, v the
specific volume, k the coefficient of compressibility at constant temp-
erature, and e the coefficient of expansion at constant pressure, then
/■ and e have by definition the following meanings.

k =

e =

V \9j)

do

9T

If, according to the van
der Waals equation, we
plot on the 7^ r-plane,
as in Figure 1, the iso-
thermals of the liquid, /■
and e each have a geo-
metric interpretation ; /•
is the reciprocal of the
slope of the isothermal
divided by v; and e is
the distance between
twoisothermals measured
parallel to the r-axis,
divided by the difference
of temperature between

the isothermals and di-

^ vided also by v.

The purpose of this re-
search may now be made
somewhat clearer by an examination of Figure 1, where we will suppose
that we have plotted two of the isothermals of either ethyl ether or
ethyl alcohol. Suppose the temperatures for which these isothermals
are plotted differ from each other only by two or three degrees. To be
specific, consider the isothermal A F H J. On this isothermal the
point D represents the liquid when it is under a pressure equal to its
vapor-pressure. The part D F of this isothermal represents the liquid
in the superheated state. We are to determine the slope of such an
isothermal, (1) at B and C, where the external pressure exceeds the
vapor-pressure by about one atmosphere, (2) at D, where the external
pressure is equal to the vapor-pressure, (3) at E, where the external
pressure is less than the vapor-pressure. Furthermore, the distance
B L between any two neighboring isothermals, when p is equal to one

Figure 1.

SMITH. — EXPANSION OF ETHER AND ALCOHOL. 423

atmosphere, is to be compared, (1) with the distance CM between the
same isothermals when p is eiiual to the vapor-pressure of the Hquid
at the higher temperature, (2) with the distance EO between these
isothermals when /> is less than the vapor-pressure of the liquid at
either of the temperatures. B L, CM, and E 0 are parallel to each
other and to the r-axis.

Part I : Liquids under Pressures greater than their

Vapor-pressures.

Thermostat.

In order to study the compressibility of liquids at low pressures,
one must use small differences of pressure, not greater than 10 or 15
cm. of mercury, in getting the change of volume in the liquid. The
changes in volume which result from such slight changes of pressure
are very small and, since the coefficient of expansion of each of these
liquids is large in comparison with its coefficient of compressibility,
small changes in the temperature would introduce large errors in the
determination of the compressibility. So small a change of tempera-
ture as ().()()1° C, in either of these liquids, would introduce an error of
about 3.5 per cent in the compressibility, if the change of volume were
produced by increasing or by decreasing the pressure 20 cm. of mer-
cury. If, therefore, the data were to have an accuracy of one per cent,
the constancy of the temperature would become an important question.
Moreover, the apparatus to be introduced into the thermostat was of
such a form that the ordinary types of thermostats did not lend them-
selves to the purposes of this experiment. After some difficulty the
following type was devised, which has met very well the requirements
of this experiment.

The thermostat consisted in the main of a rectangular box, which
was 150 cm. long, 60 cm. high, and 46 cm. wide. This box for brevity
will be referred to as the air-hath. The top of the air-bath could be
removed at will to allow the introduction of apparatus. Extending
the whole length of the air-bath at mid-height of each side was an
opening 2 cm. in width. These openings were covered with plate
glass and served as windows through which observations could be
made in a manner to be described later. In the interior of the air-
bath, along its sides and bottom at a distance of about 5 cm. from the
adjacent walls, were strung spirals of No. 18 german-silver wire, which
in the aggregate had a resistance of about 20 ohms. These coils of
wire, when connected in series with the city alternating circuit of 110
volts, served as heating coils by means of which the temperature of

424

PROCEEDINGS OF THE AMERICAN ACADEMY.

Q

B

r

l«rom

I h

^J ^~

Relay

the air-bath could be raised to any desired value less than 60° C. In
order to keep the air in the air-bath homogeneous as to temperature,
a fan-motor which ran at fairly constant speed was placed at each of
its ends. These motors stood just outside of the air-bath, and their
shafts, each carrying a fan, projected into the interior.

For the regulation of the temperature of the air in the air-bath a
modified form of the usual device, depending upon the expansion of

alcohol, was used. A
brass tube, with thin
walls and an internal
diameter of about 0.7
cm., was wound in the
form of a spiral 50 cm.
long and 6 cm. in diam-
eter. One end being
closed, the other was
connected by means of
a short piece of stout
rubber tubing to the
larger end of the glass
tube, GADB (Figure 2).
It was found better to
make the spiral of brass
than of glass. The brass,
having a lower specific
heat and a higher ther-
mal conductivity than
the glass, allowed the
liquid which it con-
tained to assume more
rapidly the temperature
of the air which sur-
rounded it. The large
surface which the spiral presented, in comparison with the volume of
liquid which it contained, about 150 (cm.)^ increased the rapidity
with which the liquid assumed the temperature of the surrounding air.
The spiral stood in a vertical position in the air-bath, and the glass
tube BD (Figure 2) was also vertical. The thermo-regulator was
filled with well -boiled alcohol. From the line E F around to the plati-
num point at B, it contained mercury. By taking out, or by adding
mercury or alcohol, one fixed the temperature of the air-bath at any
desired value. The platinum wires A and B (Figure 2) were con-

Heating Coils

Dynamo

Figure 2.

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

425

nected in series with a relay of 1700 ohms and a battery of 8 volts.
The other terminals of the relay were connected in series with the
heating coils of the air-bath. These connections are shown diagram-
matically in Figure 2. The oscillations which occurred in the air-bath
were of the order of 0.2° C, and took place in about one minute.

I thought it well to isolate a portion of the space inside of the air-
bath from the remainder by means of non-conducting materials, hoping
thus to get an inner region in which these oscillations of temperature
would have little effect. Since the apparatus to be kept at constant
temperature was about 70 cm. long, and was to lie in a horizontal posi-

_J5^!?^^1_

.^^ 9,

tion, I chose as the region to be thus isolated the space inside of a
cylindrical shell, 120 cm. in length, 15 cm. in internal and 25 cm. in
external diameter. The walls of this cylindrical shell were made of
concentric sheets of asbestos, the space between these sheets being
packed with asbestos wool. The openings in the ends were filled with
cotton wool. For the purposes of observation, it was necessary to have
two narrow windows in the shell. These windows were diametrically
opposite each other, and the glass plates closing them were at the inner
surface of the shell. The temperature of the space thus enclosed was
found to remain very nearly constant.

An incandescent lamp was used as a source of illumination, and at
first the heat from it, passing into the thermostat, caused a slight drift

426

PROCEEDINGS OF THE AMERICAN ACADEMY.

of temperature. To prevent this drift, and to prevent, as far as possible,
tiie flow of heat from the thermostat into the room, water-windows
were placed just inside of the air-bath and opposite the small openings
in the cylindrical shell.

Figure S shows a cross section of the thermostat, made through the
water- windows, the telescope, and the source of illumination. L M N 0
is the air-bath ; E and F are the halves of the cylindrical asbestos
shell ; A and B, the two water- window s. The openings at K and J
and those at H and I, were closed by plate-glass windows.

FlGCRK 4.

Dilatometer and Piezometer.

The 'dilatometer (Figure 4) consisted of a C3dindrical glass bulb HG,
30 cm. long and 1.7 cm. in diameter. For purposes of filling, which
operation will be described later, one end of this bulb was closed by
means of the stopcock K. At right angles to the axis of the bulb and
midway between its ends was sealed another glass tube 5 cm. long, and
of the same internal diameter as the bulb. The lower end of this
short tube was closed, and to it was sealed the capillary tube ABCD,
which from A to B was parallel to the bulb, from B to C at right angles

Figure 6.

to it, and from C to D again parallel to it. Near the end D this tube
carried the rubber stopper M. The purpose of this stopper will be
explained later. Inside the bulb of the dilatometer there was a spiral
of fine platinum wire, to be used as a platinum thermometer. The de-
scription of the use of this platinum thermometer will be postponed.

The piezometer (Figure 5) consisted of the cylindrical bulb 0 N, to one
end of which was sealed the capillary tube 0 P. The piezometer also
contained a platinum thermometer, the lead wires of which passed out
through the rubber stopper L. The capacity of the piezometer was
determined by weighing it empty and then weighing it filled with

SMITH. — EXPANSION OF ETHER AND ALCOHOL. 427

distilled water at a known temperature. The capacity of the dilatom-
eter was determined in precisely the same way. The former had a
capacity of G4.04 (cm.)', the latter a capacity of 70.32 (cm./.

The capillary stem of the piezometer, and also that of the dilatom-
eter, was calibrated by use of a mercury column, so that the cross
section of each of them was accurately known at all points. The
capillary tube of the dilatometer, which had a mean cross section of
0.01918 (cm.)^ happened to have a very uniform bore, which showed
a variation of only about one half of one per cent over a distance of
20 cm. The capillary tube of the piezometer, with a mean cross sec-
tion of 0.01536 (cm.)*^, showed a variation of about 2 per cent over a
distance of 20 cm.

Brass Jacket.

In order to have the pressure on the inside of the piezometer the
same as that on its outside it was inserted in a rectangular brass vessel
which for the sake of brevity will be referred to as the brass jacket. In
the course of the whole work two slightly different types of brass
jackets were used. As their differences were of minor importance, only
one of them will be described. The brass jacket consisted essentially
of a rectangular brass box 7 1 cm. long, 1 1 cm. high, and 5 cm. wide, the
walls of which were made of strips of brass 0.6 cm. in thickness. In
one end of the brass jacket there was a rectangular opening 7 cm. long
and 3 cm. wide, through which the piezometer or dilatometer could be
introduced. This opening was then closed by the means of two cast-
ings, which were separated from each other and from the end of the
brass jacket by means of rubber gaskets. These castings, after being
firmly joined together and to the end of the brass jacket by means
of screws, afforded a conical shaped orifice into which M (Figure 4) or L
(Figure 5) fitted snugly. In order to prevent the stopper from coming
out under pressure greater than one atmosphere, it was pressed into
the conical orifice by means of a disc which, having at its centre an
aperture through which passed the capillary stem of the piezometer
or the dilatometer and the lead wires of the platinum thermometer,
was firmly fastened to the castings by means of four screws. In either
side of the brass jacket was a narrow window, closed by thick plate
glass used with a rubber gasket, through which observations could be
made. Into the top of the brass jacket and near each of its ends was
inserted a short cylindrical brass tube. One of these tubes was con-
nected to the pressure gauge so as to allow any desired pressure to be
applied to the liquid in the brass jacket. The other was for purposes
of filling, and was closed with a cylindrical brass cap after the filling.

428 PROCEEDINGS OF THE AMERICAN ACADEMY.

Although the brass jacket was designed especially for experiments on
compressibility, it was found convenient to insert the dilatometer in
it. Figure 6 shows the brass jacket with the dilatometer in position.
Part of one side is removed to show the dilatometer in the interior.

Pressure Gauge.

For the measurement of the pressure on the liquid an open manom-
eter of the form shown in Figure 7 was used. In this figure parts of the
vertical tubes are omitted. The manometer was made of heavy glass
tubing with an internal diameter of 1.2 cm. The U-shaped part of the
tube was filled with clean mercury to a height of 120 cm. Between the
branches A Band CD of the U-shaped part of the tube were placed

Figure 6.

meter rods, end to end, on which one read off the difference in height
of the mercury in the two parts of the tube. One had, of course, to
read the barometer each time in order to get the absolute pressure on
the liquid. From H and G the pressure gauge was connected by means
of pressure tubing to the capillary tube of the piezometer or the dila-
tometer and to the small tube in the top of the brass jacket. Hence
the internal and the external pressure on the walls of the piezometer or
of the dilatometer were the same. By means of the stopcock Ki the
pressure gauge could be made to communicate with the external atmos-
phere. The large tube I, which was 42 cm. long and 5.5 cm. in diam-
eter, served as an air-chamber into which air could be forced or from
which it could be exhausted. By turning the stopcock Kj the pres-
sure on the liquid could be increased or decreased by as small an amount
as one wished. The other end of I was closed with the stopcock K3.

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

429

K.

The stopcock K4 was for convenience in case the mercury had for any
reason to be removed from the pressure gauge.

Filling the Dilatometer and
the Piezometer.

The greater part of the capil-
lary stem and the short vertical
tube of the dilatometer up to the
line E F (Figure 4) were filled
with a known amount of clean,
dry mercury. The mercury was
poured into the dilatometer, care
being taken to avoid, as far as
possible, any air bubbles. One,
however, could never be perfectly
sure that slight traces of air were
not left either in the mercury or
along the sides of the tube which
contained the mercury. Since
the coefficient of expansion of air
is only about twice the coefficient
of expansion of either ethyl ether
or of ethyl alcohol, these very
slight traces of air would intro-
duce no appreciable error in the
data on the expansion of these
liquids. The end of the capillary
tube being closed, I (Figure 4)
was joined by means of a short
piece of rubber tubing to a glass
tube bent so as to dip into a
flask containing the liquid to be
investigated. This liquid had
been previously boiled to remove
traces of air. By alternately

heating the dilatometer above the boiling point of the liquid and then
cooling it, the bulb of the dilatometer was finally filled with liquid
which was free from air. When the liquid had assumed a temperature
nearly equal to the temperature at which observations were to be made,
the stopcock K was closed.

It was desirable to have the mercury in the dilatometer for two
reasons. At low pressures the otherwise free surface of the ether or

n

K.

H

FlGUSE 7.

430 PEOCEEDINGS OF THE AMERICAN ACADEMY.

the alcohol in the capillary tube afforded an opportunity for evapo-
ration, and as considerable time elapsed between observations on the
coefficient of expansion, the loss due to evaporation would introduce
some error in the measurement of the change of volume. Further-
more, the liquid retreating down the capillary tube with decreasing
temperature, leaves a film on the walls of the tube. This makes the
observed change of volume greater than the true change of volume.
This film will not disappear for a long time, and a similar cause of
error enters when the temperature is again increased. Both of these
sources of error were avoided by having mercury in the lower part
of the dilatometer.

It was hoped that a piezometer of the same form as the dilatometer
might be used in the work on compressibility ; for the error due to the
adhesion of the liquid on the walls of the capillary tube enters into
the data on compressibility as it did into the data on expansion. The
error due to the evaporation from the surface of the liquid was in
the work on compressibility not large enough to be of importance ; for
the observations on compressibility were made very rapidly. It was,
however, found that since it was impracticable to boil the mercury
into such a piezometer, the slight traces of air from which the bulb
and stem could not be entirely free, introduced serious error in
the compressibility at low pressures. It was therefore decided to
dispense with the mercury in the piezometer, and to use an instru-
ment of the kind shown in Figure 5. The liquid was boiled into this
piezometer in the same way in which it was boiled into the dila-
tometer. After the filling, the liquid in the bulb was heated 2° or 3° C.
above the temperature at which observations were to be made, ^yhen
che liquid again cooled down to the desired temperature, the exposed
surface was somewhere near the middle of the capillary tube 0 P.

It was possible to get a rough estimate of the error due to the
adhesion of the liquid on the walls of the tube. A glass tube of
about the same bore as the capillary tube of the piezometer was
filled with ether or alcohol and the liquid was then allowed to flow
out of it, leaving the inner walls of the tube wet. The weight of the
film of liquid adhering to the tube was determined at once. Knowing
the capacity of the tube, one found that about 2.5 per cent of the
liquid was left on the walls of the tube. In all the work on compres-
sibility the necessary correction was made for this source of error.

Measurement of Change of Volume.

Since the cross section of the capillary tube of the piezometer and
that of the dilatometer were accurately known, in order to measure

SMITH. — EXPANSION OF ETHER AND ALCOHOL. . 431

the change of volume corresponding to a definite change of pressure
or of temperature one need only observe the distance which the
liquid meniscus in the capillary tube moved. For this purpose a
telescope mounted with its axis horizontal on the screw of a dividing-
engine was used. The position of the telescope of the dividing-
engine is indicated in Figure 3. The screw of the dividing engine
had a pitch of 0.05 cm. and was graduated to read to 0.000125 cm.

Measurement of Teminrature.

It has been already pointed out that both the piezometer and the
dilatometer contained a platinum thermometer for the measurement
of the temperature of the liquids. Both of these thermometers were
taken from the same piece of fine platinum wire, which was about
0.015 cm. in diameter. This wire was in each case annealed by pass-
ing through it a current of 2 amperes for about 6 seconds. The wire
was then wound in the form of a helix, 30 cm. long and 1.3 cm. in
diameter. To each end of the helix was hard-soldered a short piece
of rather stout platinum wire. This was found necessary in order to
prevent the wire from breaking off where it was sealed into the ends
of the glass bulbs, G and H (Figure 4) and 0 and N (Figure 5).
Each of the platinum spirals, when inside the bulb, extended nearly
the whole length of the bulb, and the axis of the spiral coincided nearly
with the axis of the bulb. To the terminals of the spirals were
soldered copper lead wires, which, after being carried along parallel
to the capillary tubes of the dilatometer and the piezometer respec-
tively, passed out through the respective rubber stoppers M (Figure 4)
and L (Figure 5). It was found necessary to enclose these lead
wires in fine rubber tubing, in order to prevent battery-action between
them and the liquid in which they were subsequently immersed. The
total resistance of the lead wires on the dilatometer was 0.114 ohm,
while those on the piezometer had a resistance of 0.123 ohm.

Since both platinum thermometers were taken from the same piece
of wire and had been treated in precisely the same way, it seemed
sufficient to calibrate only one of them. I calibrated the platinum
thermometer which was in the piezometer and used the temperature
coefficient thus obtained in the work with the one which was in the
dilatometer. In the calibration of the platinum thermometer the
bulb of the piezometer was immersed in a mixture of ice and water
or in the vapor of one of the following liquids, boiling under atmos-
pheric pressure, — water, benzol, chloroform, and carbon disulphide.
The temperatures, except those of melting ice and boiling water, were
determined by means of a well-tested Baudin thermometer.

432

PROCEEDINGS OF THE AMERICAN ACADEMY.

Table I shows the resistance of this platinum thermometer at the
five temperatures previously referred to, and the change per degree of
its resistance over the four intervals of temperature.

TABLE I.

PC.

Resistance.

Range of Temp.

Change per Degree.

0°

25.581 ohms

0 - 45.9

.0838 ohms

450.9

29.482 "

45.9- 60.4

.0841 "

60°. 4

30.640 "

60.4- 80.3

.0844 "

80°.26

32.323 "

80.3-100.2

.0895 "

100°.2

34.111 "

It will be observed from this table that between 0° C. and 80° C.
the change per degree in the resistance of the platinum wire is very
nearly constant, and over this range of temperature shows a variation
of about 0.7 per cent. Between 80° C. and 100° C. it increases about
1.2 per cent. As all the temperatures at which the platinum ther-
mometer was used were below 80° C. the temperature of the liquid is
obtained with sufficient accuracy from a knowledge of the change in
the resistance of the platinum thermometer.

An attempt was made to fit the data into the formula of Callendar
and Griffiths. 2

T-pt = h

where

_Vioo

looj

T = absolute temperature,
8 = constant,

(B, - Bo) 100

pt

R

100

Ba

Bq = Resistance of thermometer at 0

B, =

c.

t° C.
100° C.

This attempt was, however, unsuccessful, and it appears that the
law given by Callendar and Griffiths does not hold for the specimen of
platinum wire here used.

« Phil. Trans., 182, A. (1892), p. 119.

SMITH. — EXPANSION OF ETHER AND ALCOHOL. 433

The resistance at 0° C. of the platinum thermometer which was in
the dilatometer was found to be 24.528 ohms.

For the measurement of the change in the resistance of the plati-
num thermometer during the experiments on compression and expan-
sion a Carey-Foster bridge was used. The bridge wire, which was of
manganin, was calibrated in the usual way and had a resistance of
0.01317 ohm per cm. The platinum thermometer was connected to
the bridge by means of manganin lead wires with a resistance of 2.359
ohms and a temperature coefficient of 0.000015 per degree C. The
coils on the other side of the bridge were also made of manganin wire,
which had the same temperature coefficient as the lead wires. The
resistance of each of these coils was accurately known. The change
in the resistance of these coils due to change in their temperature
was very small, but as it introduced in the coefficient of expansion an
error of about 0.2 per cent for a change of 1° C, the temperature of
the room in the neighborhood of the coils was always noted and the
necessary correction applied. The temperature of the room never
changed more than 2° C. or 3° C. between observations on expansion.

For a battery one Leclanch^ cell was used. A sensitive form of
Thomson galvanometer was found satisfactory for the resistance
measurements.

The heating of the platinum thermometer by the current used in
measuring its resistance had, of course, to be considered. By putting
a resistance of 1 ohm in the battery circuit and by using coils with a
resistance of 0.1 ohm for balancing coils in the Carey-Foster bridge, it
was practicable to reduce the current through the platinum ther-
mometer to about 0.005 ampere. This current flowed for not more
than one second. The amount of heat thus generated was small, and
would, it seems, for the most part be communicated to the liquid which
surrounded the platinum wire. Moreover, as this heating effect was
always about the same, it could not at worst introduce more than a
small constant error in the determination of the temperature, and
in getting the change of temperature this small error would be elimi-
nated. It may therefore be neglected here.

This method of measuring the change of temperature in the liquid
was found quite satisfactory. In the work on expansion the tempera-
ture of the liquid was changed only 2° C. or 3° C. The correspond-
ing change in the resistance of the platinum thermometer was never
greater than the resistance of the bridge wire, and care was taken to
measure the change of resistance in terms of the bridge wire alone.
The work was thus free from any error that might have been made in
determining the resistance of the standard coils. It was practicable to

VOL. XLII. — 28

434 PROCEEDINGS OF THE AjSIERICAN ACADEMY.

determine the change in the temperature of the liquid with certainty
to 0.01° C, but the absolute temperature of the liquid was not known
closer than 0.1° C.

Compressibility of Glass.

Since the liquid under examination was enclosed in a glass bulb
which changed its capacity with change of pressure on the liquid, the
change of volume in the liquid was partly hidden. As the piezometer
contained a platinum thermometer, the compressibility of the glass of
which it was made could not be determined directly in the usual way, by
use of mercury. Accordingly another piezometer was made which dif-
fered from the first only in this, — that it contained no platinum ther-
mometer. Its bulb was made from the same piece of glass tube from
which the bulb of the other piezometer was taken. Its capillary stem
had a mean cross section of 0.00541 (cm.)'' and had been calibrated in the
usual way. The capacity of this piezometer, determined by weighing
it empty and then weighing it filled with mercury, was found to be
63.21 (cm.)". The mercury being at 20° C, observations were made in
the usual way on the apparent change of volume of the mercury in
glass for a change of pressure, external and internal, of three atmos-
pheres. Before the measurement of the change of volume a wait of
ten minutes was allowed for the heat of compression to disappear.
Experiment showed, ki — k-i = l.ll X 10~®, where

ki — compressibility of mercury at 20° C.
^2 = " " glass " " "

This value is the mean of twenty observations, — ten made by in-
creasing and ten by decreasing the pressure. According to Amagat^
ki — 3.92 X 10-^ whence k^ = 2.15 X 10"^ This value is in good
agreement with the value given by Amagat * and with that given by
Richards and Stull.^

Expansion of Glass.

Not only does the capacity of the piezometer change when the pres-
sure on it is changed, but also the capacity of the dilatometer changes
when its temperature is increased or decreased. One must therefore
know the coefficient of expansion of glass in order to make the neces-
sary correction in the work on expansion of liquids. By the ordinary

8 Comp. Rend., 108, 228 (1880). * Loo. cit.

^ Publication No. 7 of Carnegie Institution of Washington.

SMITH. — EXPANSION OF ETHER AND ALCOHOL. 435

method with mercury, the coefficient of expansion of the glass in the
dilatometer was found to be 0.00023. One cannot be sure about the
last figure in this value, but an error of two or three units in that
place is not of importance in the present work.

Preparation of Liquids.

The ether used in these experiments was obtained from Kahlbaum
and had been distilled over sodium. Not all the observations were
made on the same specimen of ether, but they were all made on ether
which had been treated in precisely the same way. The alcohol was
purified in the usual way by distillation in the presence of lime. The
distillation took place behind suitable drying tubes to prevent the alco-
hol from taking up water from the air, and during all subsequent work
the flask containing the alcohol was not allowed to communicate with
the external atmosphere except through a drying tube. The purity
of the alcohol was determined by the ordinary methods of specific
gravity. The purity corresponding to a particular density was found
from the tables of Landolt and Bornstein.

Ea:pansion.

After the dilatometer had been filled with liquid in the manner
already described and had been placed in the thermostat and allowed
to assume a constant temperature, the pressure on the liquid was fixed
at the desired value and observations were made in the usual way on
the change of volume corresponding to a change of 2° C. or 3° C. in
the temperature of the liquid. Before the change of volume, or the
change of temperature, was finally observed, about seven hours was
allowed for the temperature to equalize. Sometimes the observations
were made by increasing, and sometimes by decreasing, the tempera-
ture. The change of volume due to a change of 2° C. in the tempera-
ture of the liquid was rather large, causing a movement of about
15 cm. along the capillary stem, and no difficulty was experienced in
measuring it. The observed change of volume due to a certain change
of temperature was, of course, due to the change of volume of the
liquid and of the mercury and of the glass bulb. Knowing the volume
of the mercury in the dilatometer and its coefficient of expansion, one
gets at once the change of volume due to this source. The error due
to the expansion of the glass bulb was corrected for in the way already
pointed out.

Tables II and III show the results of these observations. In these
tables p is external pressure on the liquid, ^i is the initial tempera-

436

PROCEEDINGS OF THE AMERICAN ACADEMY.

ture, and t^ is the final temperature ; P is the vapor-pressure of the
liquid at the corresponding temperature t^. The values of the vapor-
pressure at the different temperatures were obtained from vapor-pressure
curves plotted from the data of Ramsay and Young,^ and of Regnault.^
The mean of the two values thus obtained is given in the first column
of these tables. The values of the vapor-pressure given are certainly
correct to within a few millimeters of mercury, an accuracy which is
quite sufficient for our present purposes. Both the vapor-pressure and
the external pressure are expressed in centimeters of mercury.

TABLE II.

Expansion of Ethyl Ether.

P.

P-

h-

<»•

A/.

e X 106.

Mean
e X 10^

73.5

O

22.1

24°6

2°45

169

-

73.3

22.4

24.7

2.34

170

170

51.5

22.3

24.7

2.40

170

61.0

51.5

22.1

24.2

2.07

170

170

73.5

26.5

28.8

2.29

172

73.4

26.3

28.7

2.42

171

73.3

26.4

28.7

2.29

172

172

59.0

59.3

25.9

28.3

2.35

171

171

116.6

30.3

32.9

2.63

173

173

73.2

30.1

33.5

3.41

175

73.3

30.5

.33.5

2.99

176

73.5

30.2

32.8

2.62

174

73.4

30.5

33.0

2.51

173

73.5

.30.7

33.3

2.61

173

174

69.5

30.4

,33.0

2.61

174

G9.0

69.5

29.8

32.6

2.81

174

174

6 Phil. Trans., 177, I, 123 (1886).

7 Mem. do I'Acad., 26, 336 (1862).

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

437

TABLE III.
Expansion of Ethyl Alcohol — 99.5 Per Cknt.

P.

P-

'i-

h-

A/.

e X 105.

Mean

e X 105.

73.5

20.2

2.3.5

o

3.27

112

73.6

20.2

24.0

3.79

112

112

6.5

20.4

24 3

3.89

111

5.3

6.2

20.5

23.6

3.14

112

•112

74.2

39.0

42.4

3 39

115

74.1

39.4

42.9

3.52

116

116

16.9

39.1

42.9

3.84

114

16.0

17.0

39.6

43.5

3.92

116

115

123.0

74.6

84.8

10.2

144

123.0

73.5

84.8

11.3

142

99.0

123.0

73.5

84.4

10.9

142

143

Compressib ility.

In compression the liquid is heated. One must therefore proceed
in one of two ways. One must either wait for the heat of compression
to disappear, or read the change of volume at once and correct for the
error due to the heat of compression. The first method depends upon
the operation being as nearly as possible isothermal ; the latter, on the
condition that the compression be very nearly adiabatic. Since it was
practicable to read the change of volume in less than 30 seconds after
the change of pressure had been made, it seemed possible to get very
nearly adiabatic compression. This method had the further advan-
tage that, by reading the change of volume rapidly, any drift of tem-
perature, to which we have already referred as a source of error, would
be much less serious than if we were obliged to wait for the heat of
compression to equalize. To prevent as far as possible any loss of heat
during compression, the brass jacket was filled with the same kind of
liquid which was in the piezometer. The temperature of the liquid
which surrounded the piezometer was therefore raised the same amount

438 PROCEEDINGS OF THE AMERICAN ACADEMY.

by compression as was the temperature of the liquid in the piezometer.
There was, of course, some loss due to the heat capacity of the
piezometer.

To calculate the heat of compression, we made use of the well-
known formula,^

42350 Cj,

where e is the coefficient of expansion at constant pressure ; T is the
absolute temperature of the liquid ; A Hs the change in the tempera-
ture of the liquid due to an adiabatic compression of one atmosphere ;
and Cp is the specific heat of the liquid at constant pressure. The
values of Cp for different temperatures for both ether and alcohol were
calculated from the equations given by Regnault,^

q = 0.529^ + 0.000296^^ for ether,

q = 0.5475^ + 0.00112^== + 0.0000022U' for alcohol,

where t is temperature of the liquid on the ordinary centigrade scale,
and q is the amount of heat in calories required to raise the tempera-
ture of the liquid from 0°C. to t°C.

In order, however, to make sure that the method of adiabatic com-
pression would give trustworthy results, the compressibility of alcohol
was determined at 20°C. by the first method, — -i. e. by waiting for the
heat of compression to equalize before the change of volume was read.
The compressibility of the same specimen of alcohol was then deter-
mined by the second method, in which the change of volume is read
rapidly and corrected for the error due to the heat of compression.
Ether was examined in a similar way. The values obtained by the
first method differing from those obtained by the second method by
only one per cent, the method of adiabatic compression was regarded
as justified, and was used in all subsequent work on compressibility.

After the piezometer had been filled and had been in the thermostat
long enough to assume a constant temperature, observations were made
in the way just indicated, on the apparent change of volume of the
liquid in glass. The change of volume produced by a change of pres-
sure of 15 cm. of mercury was very small. In such a case, the total
movement of the liquid meniscus in the capillary tube amounted to
about 0.08 cm., and it was difficult to observe this change of volume

8 Sir William Thomson, Mathematical and Physical Papers, 3, 238.

9 Mem. de I'Acad., 26, 262 (1862).

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

439

accurately. Moreover, the liquid meniscus did not preserve a perfectly
symmetrical form, and this caused some error. By taking the mean of
twenty observations, — ten made by increasing and ten by decreasing
the pressure, — the probable error was reduced to one per cent or less.

Tables IV and V contain the results of these observations on ether and
on alcohol. In these tables, /• is the compressibility when the pressure
is expressed in atmospheres, and F is the vapor-pressure, in centimeters
of mercury, of the liquid at the corresponding temperature t.

TABLE IV.

COMPRKSSIBILITY OF EtHTL EtHER.

P.

Range of Pres-
sure in Cm. of
Mercury.

k X 10«.

46.6

2L6

152-76

184

76-47

185

76-61

184

61-47

185

56.0

26.0

152-77

195

152-77

103

77-56

194

77-56

193

67.6

31.5

152-77

204

77-68

206

Part II : Liquids under Pressures less than their
Vapor-pressures.

In order to have a liquid exist under a pressure less than that corre-
sponding to the vapor-pressure at the respective temperature, the
gaseous and liquid phases must, of course, not be in contact. In the
dilatometer used in the work on the coefficient of expansion described
in Part I of this paper, the liquid under investigation was in contact
with mercury in such a way that its gaseous phase was not allowed to
form. The boundary condition for superheating being thus fulfilled,

440

PKOCEEDINGS OF THE AMERICAN ACADEMY.

TABLE V.
Compressibility of Ethyl Alcohol.

P.

t.

Purity.

Range of Pres-
sure in Cm. of
Mercury.

k X 109.

4.4

2o!o

%
99.0

150-76
76-56
56-36
36-16
16-6
76-38
40-6

103
103
103
104
104
103
103

4.4

20.1

99.6

154-76
76-56
66-36
56-36
36-16
16-7

108
109
109
108
108
108

4.2

19.2

99.5

152-76
76-40
40-6

106
107
106

13.3

40.0

99.5

152-76
76-40
40-14

122
122
121

32.0

58.3

99.5

153-76
76-36

140
139

SMITH.

EXPANSION OF ETHER AND ALCOHOL,

441

it was at first expected to use this dilatometer for determining the
coefficient of expansion and a similar piezometer for determining the
coefficient of compressibility in the superheated condition. After some
effi)rts, in which this method was in part successful, it was abandoned
for another which has proved more satisfactory.

Ajyparatus.

The dilatometer used in this part of the work consisted of the cylin-
drical glass bulb A B, Figure 8, to one end of which was sealed the capil-
lary tube B C D E F, which was bent in the form indicated in that figure.
The bulb was about 30 cm. long and 1.7 cm. in diameter and had a
capacity of 60.73 (cm.)^. The capillary tube had an internal diameter

Figure 8.

of about 0.15 cm., except the part from E to F, which had a mean
cross section of 0.1506 (cm.)l In order to keep the temperature con-
stant, the dilatometer was placed in a water-bath, which was heated
by means of a Bunsen burner. Since the sides and top of the water-
bath were covered with asbestos and the space between the bottom of
the water-bath and the table on which it stood was enclosed by asbestos
walls, a small flame was sufficient to keep the water-bath at the required
temperature. After some attempts it was found possible, by means of
an ordinary pinch-cock, to regulate the supply of gas so that the tem-
perature of the water-bath remained sufficiently constant. The capil-
lary tube B C passed out through a rubber stopper in the end of the
water-bath, and the U -shaped part C D E F dipped into a large beaker
filled with ice and water. For this beaker there was later substituted

442 PROCEEDINGS OF THE AMERICAN ACADEMY.

a rectangular brass box with glass windows. In the experiments on
the expansion of ether between ()°C. and 16° C a freezing mixture
containing ice, water, and salt, at —2° C, was used instead of ice and
water. The liquid in the U-tube was therefore kept near 0° C, while
the remainder of the liquid was at a higher temperature. One has
here, then, the boundary condition for superheating all the liquid
except that contained in the U-shaped part of the capillary tube which
dipped into the beaker of ice and water, for it was in contact only with
glass or with some of the same sort of liquid at a lower temperature.

The piezometer used in determining the compressibilities in the
superheated state was of the same form as the dilatometer. For
the vertical tube E F was substituted a smaller tube of cross section
0.0184 (cm.)^. The bulb of the piezometer, which had a capacity of
61.11 (cm.)^, was inserted in a cylindrical brass tube, one end of which
was closed with a rubber stopper, through the centre of which passed
the capillary tube B C. The other end of this brass tube was closed by
means of a disk, in the centre of which was a small tube, through which
the interior of the brass tube could be made to communicate with the
pressure gauge, so that the pressure on the inside and that on the
outside of the bulb of the piezometer were the same. The pressure
on the inside of the capillary tube was not equal to that on its outside.
On account of this inequality of pressure the internal volume of the
capillary tube varied somewhat, and the magnitude of the error intro-
duced into the data on compressibility from this source had to be
considered. By means of the formula given on page 117 of Poynting
and Thomson's " Properties of Matter," the change in internal volume
for a typical case was calculated, and the error introduced from this
source was found not to exceed one fifth of one per cent, and may be
neglected.

Since in the work on expansion that part of the liquid which was
in the U-shaped tube remained at 0° C, it introduced no error into
the results. In the work on compressibility, however, the observed
change of volume, due to a certain change of pressure on the liquid,
was the sum of the change of volume of the liquid in the bulb,
which was superheated, and the change of volume of the liiiuid in the
U-shaped tube, which was not superheated, less, of course, the change
in the volume of the glass bulb. Knowing the compressibility and the
volume of the liquid in the U-shaped tube, one easily made the nec-
essary correction for the error arising from this source, which was
about one per cent. There was another correction which had to be
applied to the observed change of volume both in compressibility and
in expansion. In either of these cases the observed change of volume

SMITH. — EXPANSION OF ETHER AND ALCOHOL. 443

is supposed to be measured at the temperature of the liquid under
investigation. In the present method, however, the change of volume
due to a change of temperature or pressure was practically transl'erred
either from the bulb A B (Figure 8), where it had a temperature greater
than 0° C, to the tube E F (Figure 8), where its temperature was about
0° C, or from the tube E F back to the bulb A B. In either case it is
obvious that the observed change of volume is less than the true
change of volume. Taking an apj)roximate value of the coefficient of
expansion of the liquid, one at once finds what value the observed
change of volume would have if it had been measured at the tempera-
ture of the liquid in the bulb instead of at o° C. The magnitude of
this correction varied with the temperature of the liquid in the bulb,
but was never greater than seven per cent of the total change of
volume.

Expansion.

If observations were to be made on the coefficient of expansion, the
dilatometer was filled in the manner already described on page 429 and
then placed in position in the water-bath, the temperature of which
was raised to the desired value and allowed to become constant.
Enouiih of the liquid was removed from the tube E F (Figure 8) to
allow the free surface to stand about 2 cm. above the point E. The
end of the tube E F was connected to the pressure gauge described on
page 429 and the external pressure on the liquid was made slightly
less than the vapor-pressure corresponding to the temperature of the
li(|nid in the bulb of the dilatometer. This temperature was deter-
mined by means of a well-tested Baudin thermometer which passed
down through the cover of the water-bath and had its bulb near the
middle of the cylindrical bulb of the dilatometer. The pressure re-
maining constant, observations were then made on the change of
volume corresponding to a definite change of temperature. Before
observing the change of volume a wait of about one hour was allowed
for the temperature to attain equilibrium. After observations on the
change of volume and on the change of temperature had been made,
the external pressure on the liquid was increased, until the liquid was
no longer superheated. ^° The liquid was then allowed to cool dowji to

" This method of procedure was adopted after the first four attempts to
obtain values of the coefficient of expansion of ether in tlie superheated state.
In each of these attempts the following peculiarity was noticed.

I had the ether at a temperature of 35° C. and under a pressure of 75 cm. of
mercury. Leaving the pressure unchanged, I increased the temperature up to
45° C, and when the temperature had become constant, noted the change of
temperature and the corresponding change of volume. Without changing the

444

PROCEEDINGS OF THE AMERICAN ACADEMY.

TABLE VI.
Expansion of Ethyl Ether in the Superheated State.

P.

P-

/,.

h-

A/.

e X 106.

Mean
e X 10.

18.5

18.0

o

0

16':2

16°2

152

18.5

17.8

0

19.1

19.1

151

152

43.2

42.0

19.8

34.0

14.2

170

4.3.6

42.0

20.2

35.3

15.1

171

42.0

41.7

19.1

35.8

16.7

170

42.5

39.2

19.6

35.9

16.4

172

171

64.9

64.1

30.6

40.9

10.4

174

65.1

51.6

30.6

41.0

10.4

178

66.3

51.4

31.1

41.2

10.1

177

640

51.9

30.2

41.4

11.2

179

177

80.2

75.0

35.9

44.9

9.0

185

80 5

75.0

36.1

45.1

9.0

186

77.9

75.4

35.3

46.9

11.6

184

77.9

75.4

36.3

45.6

10.2

183

185

pressure, I removed the flame from beneath the water-bath in order to allow the
temperature of the ether to return to 35° C, expecting to observe the decrease
in volume corresponding to this decrease in temperature. But, instead of cool-
in"- quietly down to its former temperature, the ether suddenly changed into
vapor shortly after the flame had been removed. It occurred to me that the
reversing of the temperature was the cause of this sudden vaporization. I then
adopted the method described above, and no further difficulty was encountered
from these sudden vaporizations. It is seen that by this method I returned to
the unsuperheated state by an increase of pressure instead of by a decrease of
temperature.

I do not consider that the four observations which I made justify me in saying
that the reversal of the temperature was the true cause of these sudden vaporiza-
tions, but as we do not fully understand the conditions of equilibrium of the
superheated liquid, it seems best to record these unexplained observations.

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

445

its former temperature and a new series of observations commenced.
The cross section of the tube E F (Figure 8) being large, no correction
was made for the surface film which adhered to its sides.

Tables VI and VII show the results for ethyl ether and ethyl alcohol
respectively. In these tables P is the vapor-pressure, in centimeters of
mercury, of the liquid at the corresponding temperature t, and p is the
external pressure, in centimeters of mercury, on the liquid.

TABLE VII.
Expansion of Ethyl Alcohol in the Superheated State.

P.

P-

'i-

h-

XL

e X 105.

Mean
e X 105.

13.3

12.5

40°3

55^6

15?3

119

13.4

10.3

40.5

65.4

14.9

121

13.4

10.8

40.6

55.2

14.6

121

13.4

10.4

40.7

55.1

14.4

120

120

35.8

29.5

60.5

71.1

10.6

132

35.2

30.2

60.1

70.1

10.0

136

34.3

27.9

69.5

70.2

10.7

133

32.0

28.4

58.0

69.3

11.3

131

133

It will be observed from an examination of these tables that the
mean of the results obtained under the same conditions has in all cases
a probable error of less than one per cent.

Compressibility.

The piezometer, after having been filled, was inserted into the cylin-
drical brass tube which had been previously filled with water. Both
were then placed in position in the water-bath. The connections
were made with the pressure-gauge in the usual way. After the tem-
perature of the water-bath had been raised to the desired value and
allowed to become constant, it was determined by means of the same
Baudin thermometer used in the work on expansion. From an initial
value somewhat less than the vapor-pressure of the liquid in the bulb
of the piezometer, the pressure was decreased about 40 cm. of mercury
and the corresponding change of volume was read. The pressure was

446

PROCEEDINGS OF THE AMERICAN ACADEMY.

then increased to its original value and the change of volume noted.
These changes of volume were small and were measured with a cathe-
tometer. The observations were made rapidly, and the apparent
change of volume had, therefore, to be corrected for the error due to
the heat of compression. This correction was made in the same way
in which it was made in Part I of this paper. Here one has, however,
to assume that the specific heat of the liquid is about the same in the
superheated state as it is when the liquid is not superheated. As it
would require a change often per cent in the specific heat to prodace

TABLE VIII.

COMPEESSIBILITY OF EtHYL EtHER IN THE SdPERHEATED StATE.

p.

t.

Range of Pres-
sure in Cm. of
Mercury.

k X 106.

Mean
k X 106.

IIA

35:1

70-27

216

77.2

35.0

76-27

214

77.7

35.2

76-27

218

77.9

35.3

70-27

212

215

88.5

39.1

76-28

226

88.5

39.1

76-28

225

88.8

39.2

76-28

224

89.1

39.8

76-28

224

225

an error of about one per cent in the compressibility, this assumption
seems justified.

In Tables VIII and IX are given the results for ethyl ether and for
ethyl alcohol. Each of the values tabulated in the fourth column of
these tables is the mean of twenty observations, ten made by decreas-
ing and ten by increasing the pressure. The mean values in the fifth
column have a probable error of about one per cent. In these tables
F is the vapor-pressure in centimeters of mercury at the corresponding
temperature t. In finding the values of k, pressures are reckoned in
atmospheres.

SMITH.

EXPANSION OF ETHER AND ALCOHOL.

447

Application to the van der Waals a.

[A considerable part of the following discussion was written by
Professor Hall.]

It has already been pointed out that the determination of the coeffi-
cients e and k in the neighborhood of the boiling condition was under-
taken on account of the importance which is attached to them in the
study of the van der Waals a. Professor Hall, in the discussion re-
ferred to at the beginning of this paper, dealt with two assumptions
relating to the liquid and the vapor conditions :

TABLE IX.
Compressibility of Ethyl Alcohol in the Superheated State.

P.

t.

Range of Pres-
sure in Cm. of
Mercury.

k X 10".

Mean

k X 108.

75.6

78.0

76-36

158

75.9

78.2

76-36

156

75.8

78.1

76-36

156

760

78.3

76-36

157

157

" 1, That the pressure due to molecular attraction within a fluid is
-^, where v is the specific volume and a is some constant ;

" 2, That the energy per molecule, aside from the potential energy
due to the attraction just mentioned, is a function of temperature
only, so that it remains constant during any isothermal change of
state."

Using the data of Amagat for the expansibility and the compressi-
bility of ethyl ether and ethyl alcohol, he found that, if assumption 2
held good, ^^ assumption 1 could not be true for either of these sub-
stances in the liquid state, and that, on the contrary,

^^ I do not commit myself to the opinion that assumption 2 is necessarily
true. It is quite possible tliat we have in both liquid ether and liquid alcohol
some peculiar state of aggregation of the molecules in pairs or triplets or otlier
small groups such as Sutherland has shown the probability of in the case of liquid
water. If such groups do not exist in a given liquid, we should, according to the
van der Waals hypotheses, expect both assumption 1 and assumption 2 to hold.
If such groups do exist in a given liquid, and if their number is independent

448 PROCEEDINGS OF THE AMERICAN ACADEMY.

" I, a is not a constant but, in each of the liquids examined, a
function of both }-) and T.

" II, In each liquid at constant temperature a increases with in-
crease of volume," that is, with decrease of pressure.

Amagat's data do not, in the case of either liquid, serve for the
determination of a with certainty very near the boiling condition at
either high or low temperatures. On the other hand Professor Hall,
taking the data furnished by Regnault for the evaporation of ether
and of alcohol, and taking assumption 2 as holding through the process
of vaporization, found by means of a well-known formula the value
of a for this process at a number of temperatures in the case of each
liquid. The value of a obtained from any set of evaporation data
he called a\ and the following propositions were established with relation
to the values of a and a' :

" III, In alcohol a is much less than a' at low temperatures, but
with rise of temperature the difference diminishes, a growing larger
and a' smaller.

" IV, In ether «, at moderate pressures, is somewhat larger than a' ;
and both a and a' diminish slowly with rise of temperature, apparently
approaching equality."

The formula by means of which a is calculated is

a=gr-p),.^,

in which e = the coefficient of expansion,

^ = " " " compressibility,

jT = " absolute temperature,
jo = " pressure on the liquid,
V =■ " specific volume of the liquid.

The various quantities entering into this formula are expressed in
terms of the c. g. s. system.

of temperature and pressure, we should expect both assumptions to hold. Per-
haps the natural interpretation of the fact that both cannot hold for ether or for
alcohol is the hypothesis that such groups do exist in each liquid, but that
their number is a function of both temperature and pressure. From this point
of view the magnitude of the variations which we find in a, when assumption 2
is held, maybe taken as a measure of the discordance of the two assumptions
and therefore some indication of the rate of variation of the number of groups
with variations of temperature and pressure. It might be better to keep assump-
tion 1, taking a as really constant, and see what change would be necessary in
tlie proposition given as assumption 2.

It appears to be common opinion (see pp. 270 and 271 of the 1904 English
edition of Nernst's Theoretical Chemistr;/) that so-called polymerization exists in
liquid alcohol but not in liquid ether. E. H. H.

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

The equation used in finding the values of a' is

449

in which, p = the internal work of vaporization, in ergs,

v^ = " specific volume of the liquid state, in cu. cm.,
fi = " " " " " saturated vapor " "

The Value of a in Ether.

In Table X are given five values of a in ether, calculated by means
of my data on compressibility and expansibility. Of these values
the first three are for pressures slightly greater than the vapor-pressure,
and the last two are at pressures less than the vapor-pressure.

TABLE X.

Ether.

t°C.

a X 10-'.

22

543

27

541

32

536

36

533

39

537

We have, I believe, no definite information as to the method of
purification of the ether used by Amagat. The way in which the
ether used by me was purified has already been pointed out. In
comparing the values of a obtained from my data with those obtained
from the data of Amagat, we must neglect any differences due to
difference in purity of the ether used in the two cases. It is doubtful
if this would be a source of any considerable error.

For purposes of comparison the values found by Professor Hall for a
and a' in ether are given in the following table. The numbers in
brackets to the right of each a-column, are, as stated by Professor
Hall, " an attempt to establish a regular gradient of a with varying
pressure, corresponding in a general way to the indications of the a-
column."

VOL. XLII. 29

450

PROCEEDINGS OF THE AMERICAN ACADEMY.

TABLE XI.
Ether.

p

(atm.).

20^ C.
a' = 495 X 10'.

co^ c

a' - 491 X 107.

100^ c.
a' = 482 X 107.

V.

a X 10-7.

V.

a X 10-7.

V.

a X 10-7.

50
100
2.)0
300
400
500
600
700
800
900
1000

1.411

1.4!)0
1..380
1.302
\.Z\1
1.3.^,3
1.321
1309
1299
1.289
1.280

545 (.5.38)
532 (.335)
5.33 (528)
509 (.521)
514 (514)
507 (507)
504 (.500)
499 (493)
487 (486)
475 (4'.i7)
472 (473)

1.493
1.462
1.4.35
1.413
1.393
1.377
1.365
1..352
1.340
1.330

1603
1.552
1.514
1.486
1.462
1.4.39
1419
1.403
1..387
1.374

504 (511)
506 (508)
504 (504)
511 (501)
503 (498)
487 (494)
485 (491)

485 (488)

486 (485)
490 (482)

515 (527)
522 (522)
519 (517)
518 (512)
512 (507)
506 (506)
501 (497)
500 (492)
475 (487)
481 (483)

P

(atm).

138^ C.

198^ C.
a' -•!

V.

a X 10-7.

V.

a X 10-7.

50

100

. . .

z

. . .

200
300
400
■ 500
600
700
800
900
1000

16.56
I. GOO
I.. 560
1,528
1.500
1.476
1 4.55
1.435
1.419

)10 (509)
306 (.505)
)02 (501)
193 (497)
190 (492)
184 (488)
184 (484)
181 (480)
180 (476)

1.766
1.699
1.648
1.(507
1.574
1.545
1.521
1.500

191 (500)
i84 (496)
i97 (493)
506 (490)
511 (486)
193 (483)
165 (480)
157 (477)

Examination of Table.s X and XI shows that the vahies of a ob-
tained from my data are in very close accord with those calculated
by Professor ilall from the data of Amagat. Indeed, if the bracketed
estimates of a given in Table XI were continued by extrapolation to
the state of no external pressure, or an external pressure less than
one atmosphere, the "20° column would begin with the number 542,

SMITH. — EXPANSION OF ETHER AND ALCOHOL.

451

as against 543 for 22° in Table X, and the 60° column would begin
with the number 532. Interpolation between 542 for 20° and 532
for 60° would give 537 for 40°, whereas Table X gives 537 for 39°.
This closeness of agreement is highly satisfactory from one point of
view, though it fails to reveal any change of especial interest occurring
at or near the point of passage into the superheated condition.

In Professor Hall's paper the values of a' which were calculated
from Regnault's evaporation data are not given for temperatures above
100° C. In Table XII below are given a number of values of a' which
I have calculated from the probably more accurate evaporation data

TABLE XII.
Ether.

PC.

a' X 10-7.

re.

a' X 10-'.

40

468

o

150

409

60

457

160

898

80

450

170

385

100

434

180

372

110

433

185

362

120

428

190

378

130

422

192

392

140

418

193

395

found by Ramsay and Young. ^^ These values are considerably less
than the corresponding values obtained from the data of Regnault.
This discrepancy is accounted for by the fact that the latent heat of
vaporization of ether as given by Ramsay and Young is less than the
corresponding value given by Regnault. Now each value of a' given
in Table XI is smaller than the value which we have found for a
under like conditions of temperature and pressure. The reduction
now made in the values of a' by the adoption of Ramsay and Young's
data will make the difference between a and a' larger than before.
Moreover, a comparison of Table XII with the 198° part of Table XI
may seem to indicate that the two values do not approach the same

" Phil. Trans. (1886), p. 123.

452

PROCEEDINGS OF THE AMERICAN ACADEMY.

limit, as we should expect them to do, near the critical temperature,
which is about 194° C. But in explanation it is to be noted that the
difference between the bracketed and the unbracketed a-columns is much
greater in the 198° part of Table XI than it is elsewhere. Indeed, it now
seems quite possible that in the unbracketed a-column at 198° the
appearance of a maximum value for a in the neighborhood of 700 atmo-
spheres external pressure is really significant. If the Ama^at data
enabled us to calculate the value of « at 198° through descending stages
of pressure to 50 atmospheres, we might find a rapid fall to a value not
very different from that which the Ramsay and Young data give for a!
near the critical temperature. On the other hand, Table XII seems to
indicate a minimum value of a' near 185° C. with a rise from that point
on as the critical temperature is approached ; but it is doubtful if the
data from which the values of a' have been calculated have sufficient
accuracy in the neighborhood of the critical temperature and pressure
to allow any importance to be attached to the minimum here suggested.

The Value of & in Alcohol.

The values of a given in Table XIII were calculated in the usual
way from my data on the compressibility and the expansibility of
alcohol. Of these values the first two are for pressures slightly greater
than the vapor-pressure, and the last is obtained by using a value of
the coefficient of compressibility in the superheated state with a
value of the coefficient of expansion in the unsuperheated state. As
I have shown that neither of these coefficients is much changed in
passing from unsuperheated to superheated state, the above method
of getting the value of a at 78° C. causes no serious error.

TABLE XIII.

Alcohol.

/.°C.

a X 10 7.

o

20

40

78

481
505
570

The alcohol examined by me contained 0.5 per cent water. So far as
the writer is aware, Amagat does not state tlie purity of the alcohol
which he used, though it is fair to assume that it contained little water.

SMITH.

EXPANSION OF ETHER AND ALCOHOL.

453

This lack of information makes it difficult to compare my values of a
with those obtained from his data, and it becomes necessary to take up
the question of the effect of a small amount of water on the compressi-
bility and on the expansibility of alcohol. The latter part of the
problem has been examined by Dupre and Page,^*^ and moreover, the
necessary information is to be had from tables ^^ on the specific gravity
of mixtures of alcohol and water. Each of these sources of information
indicates that the difference between the coefficients of expansion of
absolute alcohol and that of alcohol which contains 0.5 per cent water

—

~^

—

.i-r*

---«

^

Tnrt

^

r--

V

•r'

^f"

^

y

^+

fiO

y

y

/

^

K

/

/

/

/

/

t

i

d.C\

;

'

/

/

/

20

[/

ao

40

CO

80

100

Curve I.

would not be so much as one per cent of either coefficient and may be
neglected here. These facts are brought out clearly by Curve I, in
which e X lOMs plotted as ordinate and per cent of alcohol as abscissa.
The points surrounded by circles are from the data of Dupri^ and
Page and the points marked with crosses are from the tables of den-
sities of mixtures of alcohol and water. It is seen that each set of
values gives essentially the same curve ; and for points between 99 per
cent and 100 per cent alcohol the tangent to the curve makes only a
small angle with the axis of abscissae.

The information heretofore available on the change in compressibility
with the presence of water is by no means satisfactory. Pagliani ^^ has

" Pliil. Trans. 159, 591.

« Jour, de Phys. (2) 10, 589 (1891).

" Landolt and Bornstein.

454

PROCEEDINGS OF THE AMERICAN ACADEMY.

examined the compressibility of mixtures of alcohol and water, but his
mixtures never contained more than 38 per cent of alcohol and his data
do not, therefore, throw sufficient light on the question which is here
being raised. Dupr^ and Page have also dealt with this question, but
the value for the compressibility of absolute alcohol given by them
seems to be in error, as is seen by comparing it with the value given
by Rontgen ^^ or with that given by Amagat, and this throws doubt on
their other data. Moreover, they pass by a single step from 100 per
cent to 90 per cent alcohol, and this leaves unexplored the precise

TABLE XIV.
Compressibility of Mixtures of Alcohol and Water.

Per cent of Alcohol
by Weight.

Temp. 0.'='

k X 10".

0.0

o
24.5

45.9

7.5

24.1

44.1

9.6

25.3

43.2

45.0

25.0

618

59.0

23.8

59.8

77.0

22.1

76.0

84.0

24.3

83.0

91.0

24.6

94.0

99.0

24.8

106.0

99.7

23.9

111.0

region which is of importance here. I have, therefore, examined the
compressibility of certain mixtures of alcohol and water with the
results given in Table XIV. The last two values, which are of chief
importance to this work, completely confirm values obtained earlier in
this paper. (See p. 440.) The relation between the compressibiHty
and the per cent of alcohol in these mixtures is brought out in Curve
II, in which k X 10^ is plotted for ordinate and per cent of alcohol for
abscissa.

The points on the curve marked with crosses are from the data of

« w. A., 44, 1 (1891).

SMITH.

EXPANSION OF ETHER AND ALCOHOL.

455

Pagliani, because my observations did not cover that region. This
curve, after passing its well-known minimum, is seen to become steeper
as the amount of alcohol in the mixture is increased ; and it is seen at
once that the compressibility of absolute alcohol decreases rapidly with
the introduction of a small amount of water. This decrease in the
compressibility would mean an increase in a. It is therefore probable
that the values of a given in Table XIII, which are for alcohol contain-
ing 0.5 per cent water, may be as much as 3 per cent greater than the
corresponding values for absolute alcohol. Allowing for this possible
discrepancy, we may still consider the values here found as being of
interest in connection with those obtained from the data of Amagat.

no

<

'

/

/

r

/

90

/

/

/

)

^

70

/

/

/

y

y

^

60

^

y

;y

X

*-«

<

■^

1

an

20

40 CO

Curve II.

80

100

We may perhaps see most clearly the contribution which these recent
values make to our knowledge of the van der Waals a in alcohol by
inserting them in their proper places in the table given by Professor
Hall. As given there, they have been corrected for the possible error
due to the impurity of the alcohol. That is, I have reduced by .3 per
cent the values of a given in Table XIII, after making an estimate of
the value at 80° from the value at 78^, assuming at the same time that
Amagat used absolute alcohol. The values of a calculated from my
data are enclosed in brackets in order to distinguish them from the val-
ues obtained from Amagat's data. The numbers enclosed in parenthe-

456

PROCEEDINGS OF THE AMERICAN ACADEMY.

ses have the same meaning which was attached to the corresponding
numbers in the analogous table for ether.

TABLE XV.
Alcohol.

p

(atm.).

20° C.
a' — 1197 X 10'.

40° C.
a' = 1197 X 10'.

60° C.
a' = 1164 X 10'.

V.

a X 10-'.

V.

a X 10'.

V.

a X 10-'.

50
100
200
300
400
500
600
700
800
900
1000

1.259
1.253
1.242
1.231
].222
1.214
1.205
1.197
1.189
1.181
1.175

[467]
453 (465)
458 (463)
460 (458)
457 (453)
449 (448)
448 (443)
439 (438)
422 (433)
422 (429)
426 (424)
434 (420)

1.285

1.276

1.262

1250

1.239

1.230

1.222 ■

1.213

1.205

1.197

1.189

[490]
478 (479)
471 (477)
476 (472)
470 (407)
465 (463) .
459 (459)
455 (454)
450 (450)

444 (446)

445 (442)
438 (438)

1.315
1.306
1.291
1.276
1.265
1253
1.245
1.236
1.227
1.219
1.211

483 (496)
486 (494)

491 (491)
494 (487)

492 (484)
486 (481)
479 (477)
476 (474)
472 (471)
464 (468)
466 (465)

P

(atm.).

80° C.
a' = 1112 X 10'.

100° C.
a' = 1072 X 10'.

V.

a X 10-'.

V.

a X 10-'.

50
100
200
300
400
500
600
700
800
900
1000

1.340
1.321
1.306
1.291
1.276
1.265
1.256
1.247
1.239
1.230

[556]

531 (533)
524 (527)
519 (522)
521 (517)
518 (512)
513 (507)
506 (502)
490 (497)
486 (493)
494 (488)

1.371
1.350
1.330
1.315
1.300
1.288
1.276
1.268
1.259
1.250

• • • •

567 (570)
660 (564)
556 (559)
563 (553)
551 (548)
538 (542)
526 (537)
533 (532)
621 (527)
641 (522)

It will be seen that in the case of alcohol, as in the case of ether, the
values of a calculated from the data of this paper are about what one

SMITH.

EXPANSION OF ETHER AND ALCOHOL.

457

would get by extrapolating from the values previously obtained from
the data of Amagat. It is true that the [490] now placed at the head
of the 40° column is slightly larger than the numbers beneath it would
lead one to expect, and a still greater divergence in the same direction
is to be observed at the head of the 80° column. Moreover, these dis-
crepancies would have been considerably greater if a possibly too great
allowance (3 per cent) had not been made for the greater impurity of
the alcohol used in the research of this paper as compared with the
alcohol used by Amagat. But at the most they are hardly great
enough to give certain evidence of any noteworthy change in the con-

TABLE XVI.
Alcohol.

Temp. C=>.

a' X 10--.

Temp. 0°.

a X 10 I.

o
110

1083

o
180

937

120

1069

190

904

130

1050

200

875

140

1035

210

843

150

1019

220

812

IGO

994

230

769

170.

964

240

718

dition of the alcohol in approaching and passing into the superheated
condition.

It appears in Table XV that a' decreases and that a increases with
rising temperature. Here, as in the case of ether, we find it interest-
ing to follow the change of each of these quantities as far as we can, in
order to see how nearly they approach each other in the neighborhood of
the critical temperature, which for alcohol is about 243° C. We should
of course expect them to approach the same limit in approaching the
critical temperature and pressure. The values of a' given in Table
XVI were calculated from the evaporation data of alcohol as given by
Ramsay and Young. It appears from this table that a' continues to
decrease until the critical temperature is approximately reached.

I have made an attempt to obtain values of a at temperatures not
very far from the critical temperature. Ramsay and Young have with

458

PROCEEDINGS OF THE AMERICAN ACADEMY.

considerable care plotted some of the high isothermals of alcohol. In
obtaining from these curves values of the coefficient of compressibility
and of the coefficient of expansion considerable uncertainty was intro-
duced, but at the three temperatures given in the following table it
seemed possible to find a value of each of these coefficients having
sufficient accuracy to be useful in this paper. The three values of a
calculated from the coefficients thus obtained are given in Table XVII.

TABLE XVII.
Alcohol.

Pressure
(atm.).

Temp. C^.

a X lO-'.

67
67
67

200°

210

220

737
787
832

It would appear from Tables XVI and XVII, as they here stand,
that the two quantities a and a' meet and cross in magnitude in the
neighborhood of 215° C. This is unlikely. It is more probable that
the data for the calculation of a and a' in the neighborhood of the
critical temperature and pressure are somewhat unreliable.

Summary.

1. The coefficient of compressibility, k, and the coefficient of expan-
sion, e, of ether and of alcohol have been measured at various tempera-
tures at pressures near the saturation pressures of the respective vapors.
In some cases the liquids have been examined in the superheated con-
dition. Within the error of my observations these coefficients have
been found to be constant over the range of pressure employed in this
paper. By reference to Figure 1 the meaning of this result may be more
clearly brought out. It states that the slope of any one of the isother-
mals examined in this paper, — e. g. the isothermal A F H J (Figure 1)
— has the same value at C, where the external pressure is somewhat
greater than the vapor-pressure, that it has at E, where the external
pressure is less than the vapor-pressure ; i. e., the direction of the
isothermal does not change when the saturation curve is crossed. It
has been recently stated by Amagat ^'^ that nothing is known of the

" Comp. Eend., May 21, 190G.

SMITH. — EXPANSION OF ETHER AND ALCOHOL. 459

exact course of the Thomsou isothermal where it cuts the saturation
curve. It is seen that the present investigation has been able to
supply some information on this point.

2. From the data given in Tables II, III, IV, V, VI, and VII, values
of the van der Waals a have been calculated, for the two liquids in
the various states examined, by the method used by Professor Hall in
his paper in the Boltzmann Festschrift, that is, by use of the formula

a=fy7^ — 7^1 c\ which assumes, tentatively, that the energy per mole-
cule, aside from the potential energy due to the attraction ~^, is a func-
tion of the temperature only, so that it remains constant during any
isothermal change of state. (But see footnote to p. 447.)

3. The values of a thus found prove in the case of ether to be
almost exactly those which would be obtained by extrapolation from
the values calculated by Professor Hall from the data of Amagat.
There is, therefore, no indication of any significant change of the in-
ternal state of ether as it approaches and enters the superheated
condition.

A like conclusion is probably to be drawn in the case of alcohol,
though the evidence against such a change of internal state upon
entering the superheated condition is less satisfactory in the case of
alcohol than in the case of ether.

4. From the data of Ramsay and Young on the vaporization of
ether the value which Professor Hall calls a' has been calculated for
this substance at various temperatures, ranging from 40° C. to 193° C,

by means of the formula a' =p-^ { ), in which

p = the internal latent heat of vaporization,

t'o = the specific volume of the liquid state,

Vi = the specific volume of the saturated vapor state.

These values are smaller than those which Professor Hall found for a'
from the Regnault vaporization data for ether, and these latter were
smaller than the values found for a at corresponding temperatures. We
should expect a and a' to approach the same limit at the critical tem-
perature and pressure. The lack of satisfactory data for determining
a in the immediate neighborhood of this condition makes it impossible
at present to put this expectation to the proof The last stage of
approach reached in the calculations leaves

460 PKOCEEDINGS OF THE AMERICAN ACADEMY.

a = 491 XIO^ at 198° C. and 300 atmospheres
a' = 395 X 10' at 193° C. and 34.5 atmospheres.

The critical condition is about 194.4° C. and 35.6 atmospheres. There
is some indication of a maximum value of a for the temperature 198' C,
in the neighborhood of 700 atmospheres.

From the data of Ramsay and Young values of a and of a' have
been found for alcohol, supplementary to those calculated by Professor
Hall from the data of Amagat and of Regnault. At low temperatures
the value of a' in alcohol is more than twice as great as the value of a.
At the last stage, at highest temperatures reached in the calculations,
the following values were found :

a = 832 X 10"' at 220° and 67 atmospheres,
a' = 718 X 10' at 240° and 60 atmospheres.

The critical condition is about 243° and 63 atmospheres. It would
appear, according to the data now available, that the values of a and a'
meet and cross in magnitude in the neighborhood of 215° C. ; but this
seems improbable. Data for the neighborhood of the temperatures
here considered are rather dubious.

5. Partly from the data of Pagliani and partly from new data a
table (XIV) of the compressibility of mixtures of alcohol and water has
been made, ranging from 0 per cent to 99.7 per cent of alcohol. It is .
found that the effect of a small amount of water is very marked. Thus
the compressibiHty of 99.7 per cent alcohol is about 4 per cent greater
than that of 99 per cent alcohol.

6. In four successive attempts to return ether from the superheated
state to the unsuperheated state by cooling at constant pressure sud-
den vaporization occurred, after which this method of procedure was
abandoned. No difficulty was experienced in effecting the return by
increasing pressure at constant temperature. The reason for the
apparent upsetting effect of the cooling process is not evident.

Grateful acknowledgment is made by the writer to Professor Hall
for constant advice and personal aid in the course of this work.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 18. — January, 1907.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY, SYRACUSE

UNIVERSITY; ALSO CONTRIBUTI0^'S FROM THE BERMUDA

BIOLOGICAL STATION FOR RESEARCH. —No. 9.

THE HYDROIDS OF BERMUDA.

By Edgajb Davidson Congdon.

THE HYDROIDS OF BERMUDA.i
Edgar Davidson Congdon.

Presented by E. L. Mark, November 14, 1906. Received November 2, 1906.

This paper has for its purpose the description of certain hydroids
which I collected in the summer of 1903, while an attendant at the
Bermuda Biological Station. They were investigated under the guid-
ance of Dr. C. W. Hargitt in the Zoological Laboratory of Syracuse
University. I wish to express my great indebtedness to Dr. Hargitt
for his suggestions and criticisms, and to thank the Bermuda Biological
Station for courtesies extended to me during the season.

Verrill ('99, p. 571) has stated in the Proceedings of the Connecticut
Academy of Science that eleven hydroids occur at Bermuda, but he
does not name or describe them. I know of no other zoologist who
has occupied himself with the subject.

Of the eighteen species that were found, eight were previously un-
described. Each species which had been previously described varied
in some small degree from the type individuals. The various common
hydroid families are quite equally represented. Eudendrlum hargitti, a
new species, is especially interesting because of phenomena of oogenesis
which have been elsewhere described (Congdon, : 06). Two new species
of Halecium present female gonophores whose structures are significant
when compared with the gonophores of other species of the genus.

Few hydroids are found on the exposed southern shore of the Ber-
mudas. The coves, inlets, and reefs of the opposite shore are well
supplied with individuals and species. The Sargassum, which floats in
after a prolonged south wind, often is the home of an abundance of
Aglaophenia minuta, Halecium, and Clytia simphx.

Pennarla tiarella, Eudendrlum ramomm, Sertularia humilis, and
Sertularella hrevicyatkus are the most common species. E. hargitti^
Sertularella speciosa, and TJip-oscyphus intermedius are each confined
to some single very restricted locality. In the few places especially
favorable to hydroid life the strife for foothold is so marked that seven
of the small species may be found growing on the larger ones.

^ Contributions from The Zoological Laboratory, Syracuse University ; also
Contributions from the Bermuda Biological Station for Research, No. 9.

464

PROCEEDINGS OF THE AMERICAN ACADEiMY.

The Bermuda hydroids show a close relationship to those of the
West Indies and the Gulf of Mexico, All the genera of the new species
and all but one of the species previously described are there represented.
The remaining species, Bimeria humilis, has not to my knowledge
been found south of New England.

Genus PENNARIA McCrady.
Pennaria tiarella McCrady.

The Pennaria tiarella of Bermuda
has on the average three more filiform
tentacles than that of Wood's Hole,
Mass. Clarke ('79) described a member
of this genus from Cuba, under the name
of P. symmetrica, in which the gonosome
was lacking. The characters which he
considers specifically distinctive are : the
exact form of the hydranth, the origin
of the tentacles from a little above the
base, and the presence of eighteen fili-
form tentacles. The first two characters
vary greatly with age and the amount of
food in the hydranth. The number of
tentacles does not seem to me of specific
importance, because it varies considerably,
owing only in part, I think, to the degree
of maturity. It seems probable that P.
symmetrica, like the Bermuda form, is a
geographical variety of P. tiarella.

Genus EUDENDRIUM Ehrenberg (in

part), 18:52.

Budendrium ramosum Linnaeus.

E. ramosum differs in three respects
from the individuals of Wood's Hole,
Mass. There is a slightly larger aver-
FiGURE 1. Colony of Eudendrium age number of tentacles ; there may be
hargitti (xiO). one more lobe to the male gonophore ;

the hydranth to which the clusters are
attached is often entirely aborted.

CONQDON.

THE HYDRUIUS OF BERMUDA.

465

Eudendrium hargitti (new species). Figures 1-5.

This hydroid was found at only one place, a shallow inlet on the
south shore of Bermuda (lat. 32° IG'oO", long. 64° 4;'/ 5"). It is a
handsome little form with bright reddish brown hydranths and horny
brown perisarc, which contrasts with the usual substratum of white
coral sand (Figure 1).

Trophoso)}te. Stem unfascicled ; colony twenty to fifty millimeters
long, becoming nearly transparent toward the extremities. Branches
straight, few, nearly par-
allel to the main stem,
distributed irregularly,
joining stem by an abrupt
bend. Annulations at ba-
ses of colony and branches,
occasionally elsewhere.
Hydranth most deeply
colored at base of hypo-
stome; tentacles from
thirty-five to forty-five, in
contraction forming two
closely appressed rows ;
hypostome very mobile,
contracting into a shallow
cup or extending to a
length greater than that
of the hydranth body.
Some hydranths provided
with a groove near the
base containing gland cells
and thread cells.

Female Gonosome. Colonies dioecius. Two types of orange -colored
gonophores (Figures 2, 4). One begins its development before the other,
has an undivided spadix, consisting of a tube passing from the attach-
ment upward and around the eg^, and forms in conjunction with not
more than four others a circle around the base of the hydranth body.
The gonosomes of the second type are associated in clusters of two to
seven closely and rather irregularly around a thick finely annulated
pedicel, which may or may not have a terminal hydranth. They are
partly confluent with the stem, ovoid, completely invested on the exposed
side by a spadix, often indistinctly separated into a proximal and a
distal group. A dozen clusters may occur close together on a basal

VOL. XI.II. — 30

FiGi'RE 2. Eudendrium hargitti. Orthospadi-
ceous and streptospadiceous gonophores (X 11).

466

PROCEEDINGS OF THE AMERICAN ACADEMY.

branch. Found toward the base of the colony always below the first
type, whether occupying the same stem or not. A pedicel bearing this
type may support a hydranth upon which the other type occurs.

Male Gonosome. Gonophores on an aborted hydranth and much
annulated pedicel (Figures 3, 5). Three- chambered in a moniliform
arrangement (Figure 3, left side) with but slight constriction between
the lobes and their relative diameter variable. Four lobes may be

Figures 3-5. Eudendrium hargitti.

Figure .3. Hydranth witli common type of male gonophore to the left and a
less common form to the right (X 26).

Figure 4. Distal streptospadiceous and proximal orthospadieeous gonophores
(X 12).

Figure 5. An unusual form of male gonophore (X 22).

arranged so as to form a diamond- shaped cluster, or another may be
added proximally upon one side (Figure 3, right side).

The variability and simplicity of these gonophores in comparison
with other Eudendria is suggestive of degeneration. This hydroid
has the distinction of being the only member of the genus whose egg
is known to grow by the absorption of other cells.

It is a pleasure to name this species after Professor Charles W.
Hargitt. To those who, as students of the Hydromedusae, are ac-
quainted with his various contributions relating to problems of the
group, the reason for so doing is apparent.

CONGDON. — THE IIYDROIDS OF BEKMUDA.

467

Gencs BIMERIA S. Wright, 1859.
Bimeria humilis Allman. Figure 6.

Dense growths of the colonies of this small animal are to be found
on Eudendrium, Pennaria, sponges, and the like. The stem of Pen-
naria often forms the centre of a
cylindrical mass a centimeter in di-
ameter. No gonosome is present.

The genus Bimeria was estab-
lished in 1859 by Strethill Wright
for a hydroid of the Firth of Forth,
characterized by a covering of peri-
sarc on the hydranth body and
around the bases of the tentacles
(Allman, '71, p. 297). Allman ('77,
p. <S)'added to the genus the species
B. hv. mills from the Tortugas, which
differs but slightly from the Ber-
muda Bimeria.

Gonosome is lacking. In two
respects the hydroids differ. The
Tortugas form has a very opaque
perisarc as described by Allman ;
in the Bermuda form it is trans-
parent; but descriptions of other
species added to the genus later by

different authors suggest by their dissimilarity that in regard to this
character individuals may vary in appearance. Secondly, Allman states
that he was not able to detect the ends of the tentacle tubes and his
figures do not show them. By focussing on the end of an expanded
hydranth, I had no difficulty in finding them. There is thus no
warrant for constituting a new species unless the gonosomes reveal
differences.

Figure 6.

Colony of Bimeria humilis
(X 18).

Gencs LAFOEA Lamouroux, 1812.

Lafoea calcarata A. Agassiz.

A small number of colonies were found growing around the base of
a hydroid. Unfortunately the collection was lost before it could be
examined at length.

468

PROCEEDINGS OF THE AMERICAN ACADEMY.

Genus OBELIA Peron and Leseur, 1809.
Obelia hyalina S. F. Clarke. Figures 7-9.

Obelia

Figures 7-9. Ohelia h)/nlina.

hi/alma grows on
sponges, algae, and large hy-
droids which inhabit the shallow
waters of Bermuda (Figures 7, 8).
Stems and branches may develop
short stolons. The branches are
described by Clarke as arising
from the axils of hydrothecae.
I found them more commonly
resulting from the extension of
pedicels. The gonothecae which
Clarke found were evidently
immature, since they are fig-
ured with a truncate end. Later
these develop a small aperture
surrounded by a flaring rim
(Figure 9).

Figure 7.
Figure 8.
Figure 9.

Colony (X 3).
Colony (X :50).
Gonotheca (X CO).

Genus CAMPANULARIA
Lamouroux (in part) 1816.

Campanularia insignis
AUman. Figures 10-12.

The animal lives in all the
localities along the shores of Ber-
muda where hydroids are plen-
tiful. The trophosome (Figure
10) was described by Allman
from a dredging of the Challenger
expedition in thirty fathoms of
water off the coast of Bermuda.
I have to add a de^ription of
the gonosome.

An interesting character not
to my knowledge elsewhere found
in the genus Campanularia, is the
vegetative reproduction through
the agency of stolons, much as
takes place in plants by creepers

CONGDON. — THE HYDROIDS OF BERMUDA.

469

(Figure 11). The outgrowths arise from the ends of the stems and
branches or may replace the latter. They are present in colonies of
all sizes and are most abundant at the distal end. By their elongation,
sometimes aided by a bending of the colony, their tips come in contact
with the substratum. A clump of rhizoids forms and a new colony
rises from them. Only a small proportion of the stolons were engaged
in this process. Hincks ('68, p. 170) figures similar stolons on C,
aiKjuUdn, but they were not seen to give rise to colonies.

Nutting (:00, p. 44) has seen a species of Aglaophenia in the act of
conjugating by means of stolons. A hooked stolon of one colony
catches a similar structure of another. Fusion occurs, and after a
resting period of three months a colony arises at the point of contact.

Figure 10. Campanularia insignls. Branch and part of main stem, showing
two t\'pcs of gonophores (X 4).

Though I found no case of fusion in many hundred colonies, the possi-
bility of its occurrence is suggested by the hooked ends of the young
stolons. Sometimes a small hooked stolon arises perpendicularly from
near the end of another. As the branches grow larger, the hook
gradually straightens, until there is but a slight curve, as found in
C. angulata, S. piimila, and other species.

Gonosome. I found two types of gonothecae. The one was cylin-
drical and divided into about five lobes by regular and broad furrows
(Figures 10, 12). It was not apparent from their structure whether they
were female or immature male gonothecae, and I was not able to inves-
tigate their histology. The other form Avas ovoid with a constricted
opening and a single male gonophore (Figure 10).

The spermatozoa develop in gonothecae instead of in medusae. A thick
layer of sperm mother-cells lies next the mesogloea in the entoderm.

470

PROCEEDINGS OF THE AMERICAN ACADEMY.

Mature gonothecae within this layer have a zone of degenerating, ill
defined, columnar cells, whose fate I have not followed. The ectoderm

was also found undergoing ret-
rogressive change while the
sperms were nearing maturity.
It would seem probable that
the entoderm furnishes nour-
ishment for the spermatic layer
from its own substance at this
stage, while at an earlier period
of growth it passes food onward
from the central cavity to it.

There are minor points of
structure which require to be
reconciled with Allman's de-
scription of Campanularta
insignis. He gives the height
of large colonies as nine inches.
Although I found none having
more than half that height,
this is so variable a feature
that it should have little
weight. The rim of the hy-
droid is described by Allman
as narrow and more transpa-
rent than the rest. In his plate
it is represented by a line
parallel to and just below the
edge. My collections show the
extreme border of the hydranth
set slightly inward from the
general surface. Two or three grooves may appear encircling the
hydrotheca, but the top one may occasionally be lacking.

Allman places his species only provisionally in the genus Campan-
ularia because of lack of gonosome. The character of the gonosome
as described above settles the question of genus, placing the hydroid
among the Campanularia.

Figures 11,12. Campanularia in^ignts.

Figure 11. Young colony growing from
a stolon (X 4).

Figure 12. One of the types of gono-
theca, sex undetermined (X 40).

Genus CLYTIA Lamouroux (in part), 1812.
Clytia fragilis (new species). Figure 13.

The hyaline colonies of Cltjtia fragilis occur in company with
Halecium bermudense on Pennaria tiarella.

CONGDON. — THE HYDROIDS OF BERMUDA.

471

Trophosome. Colonies twelve to eighteen millimeters long, the small
diameter of the stem and the hyalinity of the perisarc giving the ap-
pearance of fragility. Short, strongly marked nodes, ending below
with an abrupt curve and attached to the side of the next lower node ;
ending above, apparently in the pedicel of a hydranth. Stem genicu-
late, somewhat curved in each node. Hy-
dranths alternate. The branches, which
arise from the growth of a pedicel, given
off irregularly, duplicating the structure
of the stem. Annulation at lower end of
node, sometimes extending well up or oc-
curring midway in its length (Figure 18).

Ilydrothecae campanulate, elongated,
with nearly straight sides, tapering most ab-
ruptly close to pedicels. Rim with twelve
to fourteen pointed teeth separated by
rounded edges. In old individuals the
walls often folding and cracking longitudi-
nally, causing the hydrothecae to collapse ;
the teeth in part breaking off, producing
an irregular edge. Diaphragm with a small
opening sometimes quite far from base of
hydranth. Pedicels often as long as a
node. If entirely annulated there are
from ten to twenty rings.

Gonosome. Gonothecae attached closely
to base of a hydranth pedicel, or carried
away from the stem by its elongation,
nearly twice as long as hydrothecae, flat-
tened, ovoid, truncate above, with a flaring
ring and tapering to the short annulated
pedicel. There may be some suggestion
of annulation on the wavy surface. About
six medusa buds can be found on the
blastostyle. Their bells are deep and their
manubria large. The presence of four
tentacles indicates the genus Clytia.

Figure 13. Clytia fragilis.
Half of a colony bearing a
gonotheca (X 18).

Clytia simplex (new species). Figures 14, 15.

This hydroid is only a little less abundant on Sargassum than
Aglaophenla minuta. It grows on some of the larger Bermuda
hydroids.

472

PROCEEDINGS OF THE AMERICAN ACADEMY.

Trophosome. Minute white colonies, seldom ten millimeters long,
arising rather sparsely from a creeping stolon, bearing a deeply cam-
panulate hydrotheca, pedicel annulated most commonly at both ends,
(Figure 14), hydrothecae only one and one-third to twice as long as
wide, the proportion depending on the age and condition of expansion
of hydranth. Ten to twelve triangular teeth, more or less rounded and

of varying proportions. Wall
of hydrotheca thickened below
hydranth to form a spheroidal
cavity. Hydranth of usual
type with twenty to twenty-
four tentacles.

Gonosome. Gonothecae aris-
ing from stolons, sessile, twice
as long as hydrothecae, ovoid
and flattened, distal end trun-
cate and flaring, and of one
half to two thirds the diame-
ter of the gonothecae (Figure
15). About eight medusa buds
are attached along the blasto-
style, of which the most mature
are campanulate in form with
four tentacles and four other
rudimentary organs interra-
dial in position. The manu-
brium may occupy half the
space within the bell, is nearly
spherical, and apparently not
provided with any terminal
lobes.
This Clytia combines the unbranched habit of C. hicophora and
C. grayi with the non-annulated or weakly annulated gonosome of C.
cyUndrica. The teeth of the hydrothecae are less pointed than those
of C. bicophora, and, though as rounded as those of C. grayi, are much
more deeply cut. The specific name " simplex " is suggested by the
marked simplicity in the form of trophosome and gonosome.

Genus HALECIUM Oken, 1815.

Halecium bermudense (new species). Figures 16-20.

The hydroid occurs in those places along the shores of Bermuda
which are most frequented by related species.

Figures 14, 15. Clytia simplex.

Figure 14. An individual (X 18).
Figure 15. Gonotheca (X 60).

CONGDON. — THE IIYDROIDS OF BERMUDA.

473

Trophosome. Colonies delicate and graceful, with hyaline or brown-
ish perisarc, usually twenty to thirty-five millimeters long, main stem
and large branches fascicled in part, elsewhere slightly geniculate
(Figures 16, 17). Branches irregularly placed, arising from below hy-

FiGDRES 16-20. Halecium bermudense.

Figure 16. Colony (X 4).

Figure 17. Tart of a colony (X 24).

Figure 18. Female gronotheca (X 27).

Figure 19. Compound hydropliore (X 30).

Figure 20. Male gonotheca (X 27).

drophores, when young, by an abrupt curve, which later is less appar-
ent ; occasionally, toward the end of larger branches, arising midway
between hydrophores. Branches may twice subdivide. They tend to
form a cluster at the tip of the colony.

Hydrophores alternate, very shallow, with usual ring of refractile

474

PROCEEDINGS OF THE AMERICAN ACADEMY.

bodies ; in the older part of the colony quite largely double, occasion-
ally seen with seven divisions (Figure 19). Annulations above each
hydrophore divide the stem into nodes, others at base of branches and
occasionally elsewhere. Hydranths large with rounded hypostome and
twenty to thirty tentacles.

Gonosome. Colonies dioecius. Gonothecae sessile at the axils of
hydrophores, sometimes found arising from hydrophores.

Female gonotheca ovoid, flattened, with a short pedicel-like base,
one side open for two thirds its length, the edges of the opening form-
ing similar compound curves (Figure 18). The blastostyle extends up
around the opposite side, curving toward the opening. The develop-
ment of the eggs is accompanied by the breaking down of the tissue
between them and the opening.

Male gonotheca (Figure 20) cylindrical and unusually slender, trun-
cate, and tapering to-
ward base, often marked
by an irregular encir-
cling groove somewhat
wavy in outline, one
third the way from the
base.

Halecium marki (new
species). Figures 21-23.

The creeping stolons
of this species form a
network over the Sar-
gassum and to a less
extent cover the bases
of some of the large
Bermuda hydroids.

Trophosome. Colonies
are commonly one and a
half to three millimeters
high (Figures 21, 23).
A thick layer of spher-
ical, unicellular algae
extending through the
coenosarc of the entire
colony colors it green. A colony begins its growth as a single hydro-
phore arising from a stolon. Its structure, like other hydrophores, is
typically that of a cylinder ; it is three times as long as broad, with a

Figures 21, 22. HaJecium marki.

Figure 21. Colony (X GO).
Figure 22. Female gonotheca and hydranths
(X76).

CONGDON.

THE HYDROIDS OF BERMUDA.

475

flaring end and one or more deep annulations at the base. Growth in
a straight line may result from the addition of successive hydrophores.
Their rims are outside the walls of the next in the series and so may
be lost off. Pairs of branches arise as hydrophores, attached by short
abrupt curves to the
opposite sides of a
hydrophore, or, less
frequently, but one
occurs. There is no
especial order in the
arrangement of hydro-
phores. Small colonies
result, whose units are
partly branching and
partly linear. Seldom
are there more than
four hydrophores in a
series ; stolons in a few
instances were found
terminating branches.

Large and slightly
retractile hydranths
terminate each branch.
There are sixteen to
twenty-five tentacles
and the hypostome is
short and rounded.

Gonosome. Ovoid Figdre 23. llalecium marki. Large colony (X CO).

gonothecae take the place

of branches (Figures 21, 22). Most colonies examined had from one
to three of them. Male and female gonothecae occur on colonies at-
tached near to each other on the stolon. The constricted opening and
the short deeply annulated pedicel make a straight line down one side.
Midway upon it two delicately annulated tubes arise, which are closely
confluent with each other and with the gonotheca. At the curiously
annulated mouth of the latter they end as hydrophores which bear
hydranths.

The blastostyle in either sex is joined with the coenosarcal column,
which branches into the two tubes. The single female gonophore
contains two large eggs, one above the other. The male gonophore is
also single and ovoid.

llalecium heanii is the only species of the genus which has a gono-

476 PROCEEDINGS OF THE AMERICAN ACADEMY.

phore in any way similar to this. It falls in a natural group with the
other species here described, H. beanii, H. dichotomum, H. sessile, and
H. hermudense, because all have large hydranths, shallow hydrophores,
and slipper-shaped female gonothecae. It is of interest for purposes of
comparison to arrange the salient characters of the female gonophores
of these forms in an order suggested by their structure.

H. mark}. Female gonotheca has two tubes, each bearing a hy-
dranth, which reach from the centre of the gonophore to its summit.
The opening is at the summit.

H. beanii. Tubes much shortened and mouth at top on a level with
the tubes.

H. dichotomum. Only one tube springing from the side half-way
down.

H. sessile. Like H. bermudense, but the opening at top and the
remains of tube gone.

Though recognizing that caution should be used in formulating theo-
ries as to the development of animal structures from such comparisons
as are suggested above, it seems to me that the facts point forcibly to
the origin of the slipper- shaped gonotheca in the following way. The
gonotheca structure in the present species suggests that a hydrophore
bearing a gonotheca also gave rise to a branch on either side, the latter
a common condition in the species. The two branches with their ter-
minal hydranths then became fused with the gonotheca. In this
species the fusion is complete half-way up the gonotheca. Next the
tubes shortened further by a contraction of their upper part until they
became mere openings and the aperture of the gonotheca remained
near to them, as in H. macrocephalum. In H. bermudense the opening
is elongated toward the top. H. sessile and others have the opening
at the top, but retain the slipper-like form.

Genos SERTULARELLA Gray (modified), 1847.

Sertularella speciosa (new species). Figures 24-28.

This form was found only at the opening of an underground passage
connecting Harrington Sound and Castle Harbor (lat. 32° 20' 30",
long. 64°42' lO").

Trophosome. Colonies fascicled, truncate, usually five to eight inches
high (Figures 24, 28). Occasionally a large branch occurs resembling
the main colony. Pinnae alternate, making an angle of eighty degrees
with the stem, divided into nodes at intervals of some five hydrothecae
by grooves slanting alternately in opposite directions. Stolons occur
at ends of stems and branches.

CONGDON.

THE HYDROIDS OF BERMUDA.

477

Hydrothecae alternate, embedded in stem or pinna nearly to the
opening, separated by a considerable space from each other, cylindrical
and flattened laterally, the lower end tapering slightly, with no line
marking its union below and no diaphragm, the upper end bending out
at an angle of sixty degrees. The hydrothecae of the branches grow
from a pair of tubes on opposite sides of the stem. There are usually
three between successive pinnae
on one side, one of which is just
above the origin.

The opercula of young hydro-
thecae have four, or occasionally
five, ridges, terminating in corre-
sponding projections of the edge ;
one abcauline, and the others
symmetrically placed. Opercu-
lum usually first ruptured at
centre. Four ragged lobes or a
rim may remain until maturity,
but they are more commonly lost.
Projections usually persist, be-
coming less distinct. Two or
three rings usually found below
the edge of old hydrothecae.

Expanded hydranths trumpet
shaped, hypostome conical, ten-
tacles twenty to thirty. A blind
sack is attached to abcauline
wall of hydrotheca, from which
projects a transverse edge.

Gonosome. Colonies dioecious.
Male and female gonothecae, aris-
ing from pinnae, externally simi-
lar, equal to five hydrothecae in
length (Figure 26). Theca hya-
line, cylindrical, distally truncate,
proximally constricted for one
fourth its length into a pedicel-
like base. Axis slightly curving,
markings of surface often very
faint, consisting of eleven longitu-
dinal ridges terminating in lobes along the distal margin, separated
by more faint parallel ridges and six or eight broad shallow circular

Figure 24. Sertularella speciosa.
Colony with gonothecae (X li).

478

PROCEEDINGS OF THE AMERICAN ACADEMY.

grooves. Top has radial ridges terminating in the lobes. Gonothecae
attached below hydrothecae, one or two near base of branches, or
a series decreasing in size distally or otherwise arranged. Female gono-
thecae with gonophores filling the cavity containing about forty eggs
arranged around a lumen (Figure 27). The male gonothecae similar
(Figure 25).

I examined the structure of the stem by macerating it in caustic
potash. Twenty tubes occur near the base of a small colony and four

26
Figures 25-28. Sertularella speciosa.

Figure 25. Male gonotheca (X 30).
Figure 26.
Figure 27.
Figure 28.

Female gonotheca ( X 30).
Female gonotheca ( X 30).
Part of branch (X 22).

near the top. They extend for various distances upward to terminate
by joining others. The rhizoids consist of tubes which themselves
unite near the base of the colony much as do the former. In each
colony there is one large hydrothecae -bearing tube which gives rise to
the pinnae of one side near the base and further up for both sides. It
arises from a union of other tubes near the base of the colony and
traverses the entire stem. Pinnae on the side opposite the large tube
arise from tubes which become hydrothecae-bearing for a short distance,
give off two or three other branches, and then terminate in a tapering

CONGDON.

THE HYDKOLDS OF BEllMUUA.

479

process which joins another tube of similar structure. The large tube
and all hydrothecae-bearing tubes are segmented, as well as the others,
just before uniting with them.

The present species is an illustration of the difficulty which is found
in delimiting the genus Sertularia and some other genera of the same
family. The genus is confined by Nutting (: 04, p. 37) to those species
in which the operculum is well defined or stretched tightly over the
top of the hydrotheca. Though neither condition occurs here, the
characters of hypostome and gonosome place the species unmistakably
in this genus. Thidaria pinnata, described by Allman from the Double-
headed Shot Key, is similar in trophosome, but the hydrothecae are
less confluent (Allman, '77, p. 28). The gonosome is not known. Ser.
tularellx didans is also much like this species (Nutting, : 04, p. 88).
The stem is, however, unfascicled and the hydrothecae provided with
a constant border.

Figures 29-31. Sertularella kvmilia.

Figure 20. Female gonotlieca, one egg remaining (X 25).
Figure 80. Female gonotlieca, eggs not discharged (X 25).
Figure 31. Male gonotlieca (X 25).

Genus SERTULARIA Linnaeus (in part), 1767.

Sertularia humilis (new species). Figures 29-32.

This is one of the hydroids most common at Bermuda. It grows so
abundantly between tide marks as to make thick brown mats, which

480

PllOCEEDINGS OF THE AMERICAN ACADEMY.

frequently contain coral mud and diatoms. Doubtless it is protected
at low tide by its denseness, which mitigates desiccation. The name
refers to its humble appearance.

Trophosome. Colonies are a deep horn color, pinnate, unfascicled,
thirty to forty millimeters long. The sometimes geniculate stem is
constricted below each of the ten or more alternate pinnae (Figure 32).

Three sessile hydrothecae usually found on each joint of stem, most
frequently two on the same side as the pinna, the other sub-opposite
the more distal. Variations in arrangement are found, such as two pairs

Figure 32. Sertularella humilis. Part of main stem and branch (X 25).

of opposite hydrothecae on a joint. The flattened pinnae with two or
three pairs of opposite, or slightly sub-opposite, hydrothecae to a seg-
ment. Base of stem and pinnae devoid of hydrothecae.

Hydrothecae of stem and pinnae tubular and two or three times as
long as wide for the lower two thirds of their length, and at the base
confluent with the stem. Above, bending outward at an angle of
thirty-five to forty-five degrees, and also slightly toward each other.
On this side the intervening space usually not so wide as a hydrotheca,
though width increases with age. Outer border of hydrotheca con-
tinuous with border of stem or pinna, which extends proxiraally for a
short distance to the next hydrotheca or constriction. The confluent

CONGDON. — THE IIYDROIDS OF BERMUDA. 481

portion of the hydrotheca diverges from the axis to a small degree,
distally. There is a proximal diaphragm.

Edge of hydrotheca provided with a single adcauline and abcauline
scallop, each of which is marked by a slight projection at its centre.
In older hydrothecae several parallel ridges near the edge and oper-
culum may be largely torn away ; in younger consisting of three parts,
meeting in ridges extending from the centre to the three projections.
A lateral view of the colony presents the edge of many opercula, but
shows the upper valve of some.

Gonosome. Colonies dioecious. Form of gonotheca the same in both
sexes (Figures 29-31), more than twice as long as hydrothecae, ovoid,
with a flaring mouth. They are most abundant in proximal part of
colony, attached to hydrothecae just below diaphragm. A gonotheca
was once observed rising from the interior of a hydrotheca. Charac-
teristic markings may have been lost as the gonothecae were not well
preserved. About sixteen eggs in the single large gonophore (Figure
30). Male gonothecae of similar appearance.

Sertularia brevicyathus Versluys.

So prolific is this little animal in some places that one can hardly
pick up a piece of sponge, seaweed, or large hydroid without finding a
dense growth attached.

Versluys ('99, p. 40) first described it from the Cape Verde Islands,
and later Nutting (:04, p. 60) from the Bahamas. Neither author came
upon the rather infrequent branches, which are attached at an acute
angle just below the hydrothecae and differ in no respect from colonies.

Stolons are not uncommon. They may be given off like branches or
from the tip of the colony. In the latter case they are often as long as
a colony. If a number occur in one colony, they are arranged in pairs
or are irregularly distributed.

The gonosome has not been previously described. Gonothecae are
usually solitary on a colony, and attached just below a basal hydro-
theca. Both male and female gonothecae are sessile, with a constricted
opening, a low flaring lip, and wavy surface. They are closely similar
to the gonothecae of S. pumila. These have been so completely de-
scribed by Weismann as to render further account unnecessary.

Sertularia versluysi Nutting.

Sertularia versluysi was first described by Allman from dredgings oflF

the coast of Bermuda in thirty fathoms. I have only a few colonies,

which I found on floating Sargassum.
vol.. XI, II. — 31

482

PROCEEDINGS OF THE AMERICAN ACADEMY.

Versluys believed the animal had an operculum with a single abcaul-
ine flap. Nutting (: 04, p. 53) was inclined to think there were two
flaps on his badly ruptured specimen. Material in good condition
shows that there are two large lateral projections from the edge of the
hydrotheca and a smaller adcauline one. The three parts of the oper-
culum meet in ridges along lines passing from the centre of the opening
to the projecting points.

Genus THYROSCYPHUS Allman, 1877.
Thyrocyphus intermedius (new species). Figures 33-36.

My only collection of this new form is from the eel grass of a shallow,
muddy cove of Mangrove Bay (lat. 32° 18' 10", long. 64° 51' 30").

Hydrothecae usually sin-

^oJ^

34

35 3G

Figures S-S-^JO. Thi/roscyphus intermedius.

Figure 33. Colony (X If),

Figure 34. Hytlranths, sliowing operculum (X 7^)

Figure 35. Colony (X 10).

Figure 36. Hydrantli (X 60).

gle, with pedicels one
and a half millimeters
long (Figure 36). A
small proportion have
two or three hydrothe-
cae, whose annulated,
geniculate, erect stems
resemble elongated sto-
lons (Figure 3a). A
terminal hydrotheca is
found at one end of the
axis and one or two
others are attached at
geniculations. The an-
nulated pedicels are
shorter than hydrothe-
cae ; when single, not
more than a third as
long.

Hydrothecae (Figure
r)6) are more than twice
as long as wide, nearly
cylindrical, marked by
eight or more annula-
tions, and tapering
slightly toward the top.
An operculum is formed
by the bending of the

CONGDON. — THE IIYDROIDS OF BERMUDA. 483

hydrotheca wall to form four deep symmetrical scallops. The edges
meet in two deep intersecting ridges, which terminate at the four
points between the scallops (Figure 34). The narrow diaphragm con-
sists of a fold which encloses a considerable space.

Colonies arise from creeping stolons, which are as large as a pedicel
and not annulated (Figure 33). They grow parallel to each other along
the blades of eel grass, sending frequent connecting branches across to
neighboring stolons.

The few well-preserved hydranths are contracted into the lower half
of the hydrotheca. They are attached to the diaphragm only, possibly
because of unsatisfactory killing. There are about twenty tentacles
and the hypostome is rounded.

The characters of the trophosome are allied to both Campanular-
idae and Sertularidae. The occurrence of diaphragm, pedicel, and an
ovato-cylindrical annulated hydrotheca suggest the former. Yet we
do not find a four-part operculum in that family except in the genus
Thyroscyphus, erected by Allman in 1877 for the single species T.
ramosm, which is of doubtful affinity (Nutting, :04, p. 10). The
jointed stem, shortness of pedicel, and four-part operculum suggest its
close relation with the genus Sertularella. If the gonosome is of the
Sertularelia type, the existence of a pedicel would be the only character
separating it from that genus.

The genus Sertularella as revised by Hartlaub contains species with
a hydrotheca and operculum closely similar to the Bermuda hydroid.
The one character in which it differs from the genus is the presence of
a pedicel. This difference Allman judged so important in the case
of T. ramosus as to demand a new genus. I have accepted his view of
the matter.

The chief differences between the two species, as far as we now
know, are these : T. ramosus is larger, has a bordered hydrotheca, and
a jointed stem bearing many hydrothecae instead of a short, annulated,
unjointed one bearing at most three hydrothecae.

Genus AGLAOPHENIA Lamouroux, 1816.
Aglaophenia minuta Fewkes. Figure 37.

This form is rather widely distributed. It occurs on the Sargassum,
which drifts to Bermuda from the south. Though I did not find the
gonosome, the complex trophosome was sufficient for identification.
A small nematophore is always present on each side of the axil of a
branch. The fact is not mentioned by Fewkes nor in the fuller de-
scription by Nutting.

484

PKOCEEDINGS OF THE AMERICAN ACADEMY.

Genos LYTOCARPUS Kirchenpauer, 1872. Figure 37.
Lytocarpus philippinus Kirchenpauer.

Lytocarpus philippinus is found at the places where hydroids most
abound along the shores of Bermuda. It was also dredged from the

Challenger banks, south of Bermuda.
It was first described by Kirchenpauer
from the Philippine Islands, and since
has been noted from many stations in
the Pacific and from Jamaica.

The following slight variations from
the description and plate of Nutting are
to be found : the mesial nematophore
is longer ; the intrathecal ridge nearer
the base, and the colony shorter.

^.

1

Genus PLUMULARIA Lamarck, 1815,

modified by Nutting, 1900.

Plumularia alternata Nutting.

Figure 37.

Lytocarpus philippinus. Base of
pinna (X 105).

Nutting has described this form from
a collection made by Agassiz at Barra-
cuda Rocks during the cruise of the
I found it to be one of the less common
hydroids growing upon the floating Sargassum in the vicinity of
Bermuda. The gonosome is not known.

"Wild Duck" in 1893.

Zoological Laboratort, Syracuse Univehsitt,
July, 1906.

Bibliography.

Allman, G. J.

'71. A Monograph of the Gymnoblastic or Tubularian Hydroids. Ray
Soc. piibl. for 1869 and 1870. 450 pp., 83 text figs., and 23 pis.

'77. Report on the Hydroida collected during the Exploration of the Gulf

Stream by L. F. de Pourtalfes, Assistant United States Coast Survey.

Mem. Mus. Comp. Zool. Harvard Coll., Vol. 5, No. 2, 66 pp., 34 pis.
Clarke, S. F.

'79. Report on the Hydroida collected during the Exploration of the Gulf

Stream and of the Gulf of Mexico by Alexander Agassiz, 1877-1878.

Bull. Mus. Comp. Zool. Harvard Coll., Vol. 5, No. 10, pp. 241-252,

pis. 1-5.

CONGDON. — THE IIYDIIOIDS OF BERMUDA. 485

Congdon, E. D.

: 06. Notes on the Morphology ami Development of Two Species of
Eiulendrium. Biol. Bull., Vol. 11, No. 1, pp. 27-46, 11 text figs.

Hiucks, T.

'68. A History of the British Hydroid Zoophytes. London, John Van
Voorst. 338 pp., 42 text figs., and G7 pis.

Nutting, C. C.

: 00. American Hydroids. Part I, The Plumularidae. Bull. Smithsonian
Inst., Washington, 285 pp., 124 text figs., and 34 pis.

: 04. American Hydroid.'!. Part 11, The Sertularidae. Bull. Smithsonian
Inst., Washington, 325 pp., 139 text figs., and 41 pis.

Verrill, A. E.

'99. Additions to the Anthozoa and Hydrozoa of the Bermudas. Trans.
Conn. Acad. Arts and Sci., Vol. 10, Art. 14, pp. 551-572, 1 text fig., and
pis. 47-49.
Versluys, J., Jr.

'99. Hydraires calyptoblastes recueillis dans la mer des Antilles pendant
Tune des croisi^res accomplies par le comte R. de Dalmas sur son Yacht
" Chazalie." Mem. soc. zool. France, Tom. 12, Pt. 1, pp. 29-58, 24 figs.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 19. — Feukuaky, 1907.

CONTRIBUTIONS FROM THE BERMUDA BIOLOGICAL STATION

FOR RESEARCH, No. 10; AND FROM THE LABORATORY

OF HISTOLOGY AND EMBRYOLOGY, WESTERN

EESERVE UNIVERSITY.

THE SPERMATOGENESIS OF THE MYRIAPODS

Y. — ON THE SPERMATOCYTES OF LITIIODIUS.

By Maulsby W. Blackman.

WiTu Two Plates.

THE SPERMATOGENESIS OF THE MYRIAPODS.

v. — ON THE SPERMATOCYTES OF LITHOBIUS.^
By Mauls by W. Blackman.

Presented by E. L. Mark, December 12, 1906. Received November 22, 1906.

For a number of years the author has been collecting material for a
comparative study of the spermatogenesis of the principal groups of the
Chilopoda. Five papers based upon this material have already been
published; a series of four papers (Blackman, :0l, :03, :05, :05*) upon
two species of Scolopendra (S. heros and S. subspinipes) and one paper
upon Scutigera forceps by Medes (:05). In the present article it is my
purpose to carry this comparative study further.

The present paper is based upon a study of the spermatocytes in
three species of the genus Lithobius and is from material collected
in three widely separated localities. The principal observations were
made on the testes of Lithobius mordax, collected in the vicinity of
La\vrence, Kansas, during the spring and summer of 1902 and 1903.
Using as a basis the knowledge gained from the study of this species,
additional observations have been made upon Lithobius sp. 1 and
Lithobius multidentatus, with a view to comparison. The material
of Lithobius sp. 1 was collected by the author near Flatts, Bermuda,
during July, 1903, while working at the Bermuda Biological Station for
Research ; that of Lithobius multidentatus was collected near Cambridge,
Mass., during October, 1904.

At the time this comparative study of myriapod spermatogenesis was
begun, no detailed work upon the germ cells of chilopods had been at-
tempted under modern conditions of technique. The only observations
upon this material then published were those of Carnoy ('85) in his
classical Cytodierfese chez les arthropodes, and those of Frenant ('87, '92).
Since then, however, a number of papers based upon the sperm cells of
myriapods have appeared. Of those dealing with problems touched
upon in this article the chief are those by Meves and von Korff (Litho-

^ Contributions from the Bermuda Biolot;ical Station for Research, Xo. 10; and
from the Laboratory of Histology and Embryology, Western Reserve University.

490 PROCEEDINGS OF THE AMERICAN ACADEMY.

bins forficatus), :01 ; P. Bouin, :00, :01, :03, :03^ :04 ; P. et M. Bouin,
:02, Lithobius forficatus and Scolopendra morsitans ; P. Bouin et R.
Collin, :01, Geophilus linearis.

The results obtained by these authors differ so markedly in several
important particulars from those obtained by myself (Blackman, :01,
:03, :05, :05^) on Scolopendra and by Medes (:05) on Scutigera that
it seemed advisable to extend the comparative study to the genera
upon which they had worked. What I consider the important dis-
crepancies between the observations upon American and those upon
European forms have to do with the condition of the chromatin during
the growth period and its later behavior in the prophase. According
to my observations upon the two species of Scolopendra, the chromatin
during the growth period is not arranged in the form of a spireme, or
reticulum, throughout the nucleus, but the threads are aggregated into
a very dense mass, the karyosphere, and at the beginning of the pro-
phase the chromosomes arise from this mass directly. The observa-
tions of Medes (:05) show that an essentially similar condition exists
in Scutigera. All the observations upon the European forms, however,
except the early ones of Carnoy ('85) upon Lithobius and Scutigera,
seem to lead to the conclusion that the large intra-nuclear bodies seen
in all chilopod spermatocytes are true nucleoli and have no genetic
relation to the prophase chromosomes. As will be seen later in this
paper, my present observations on Lithobius confirm my earlier ones
on Scolopendra.

Technique.

In the preparation of the material much difficulty was at first ex-
perienced in obtaining a good fixation of all the cell structures, owing
to the peculiar character of the cytoplasm. Thus, in the early study,
a large number of fixing reagents were used, including the following :
Flemming's strong solution, Flemming's weak solution, Gilson's fluid,
Perenyi's fluid, Merkel's fluid, and various picro-acetic and sublimate-
acetic mixtures. Of tliese, much the best results were obtained with
Gilson's nitric-acetic-sublimate mixture. While the results of this fixa-
tion were not always entirely satisfactory, the majority of preparations
thus obtained apparently left nothing to be desired. In later studies
Benin's pi eric -acetic- form ol mixture was tried, but the results were
much inferior to those obtained with Gilson's fluid.

The sections were cut with the Minot rotary microtome, the thick-
ness varying from 2 to 6 micra, and were affixed to the slide by means
of very dilute albumen water. The sections were then stained by one
or another of a number of methods, the best cytological results being

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 491

obtained with Heiclenhain's haemotoxylin used either alone or with
Conijo red as a counterstain. Sections thus stained were used for
all detailed studies of the cell structures. For micro-chemical tests,
Flemming's three-color stain and the Ehrlich-Biondi mixture were
used, the results obtained with the latter being especially satisfactory.

Observations.

The testis of Lithobius consists of a single unpaired sac tapering at
the anterior end, where it ends blindly, and also tapering shghtly at the
posterior end, where it is directly continuous with the vas deferens. In
adults, which were used exclusively in this study, the spermatogonia
are found only at the periphery of the testes. They are small spindle-
shaped cells containing oval nuclei (Plate 1, Figure 1), and are similar
in all respects to the spermatogonia of Scolopendra, with the exception
that each nucleus contains two karyospheres instead of one. These
karyospheres consist largely of chromatin, as is shown by their reaction
to stains. They are stained black in iron-haemotoxylin, and after treat-
ment with the Ehrlich-Biondi mixture they are colored green, while all
other cell structures assume a red tint. The remaining portion of the
nucleus is occupied by a network of linin fibres, which stains as lightly
as does the cytoplasm outside of the nucleus.

The constancy with which two karyospheres, and never more than
two, occur in the spermatogonia of Lithobius mordax has led me to ask
what significance this may have. When we consider that there are
always two karyospheres in the spermatogonia, and never more than
one in the spermatocytes of this species, the explanation suggests itself
that one of the spermatogonia! karyospheres may represent the chromo-
some group derived from the mother, while the other one is made up of
paternal chromosomes. However, it would seem impossible to obtain
proof of this, and the suggestion is made merely as an interesting possi-
bility. Furthermore, this condition is constant only for Lithobius
mordax, while in Lithobius sp. 1 the number of karyospheres in the
spermatocytes is often as great as four. At the beginning of the active
prophase of the spermatogonia! mitoses in Lithobius, the chromatin
leaves the karyospheres and becomes arranged throughout the nucleus
in the form of a large number of fine granular threads (Figure 2), each
one of which represents a chromosome. The number of these segments
at this stage is so great, and the nucleus is so small, that it has been
found impossible to count them ; but from counts of the chromosomes
during the spermatocyte stages, it may be inferred that the number of
these granular threads found in the spermatogonia is forty-eight, so

492 PROCEEDINGS OF THE AMERICAN ACADEMY.

that with the accessory chromosome the total spermatogonia! number
is forty-nine.

After the origin of the chromatin segments from the karyospheres
the residue consists of two sorts of material : a small, deeply staining
body, the accessory chromosome, and two lightly staining plasmosomes
(Figure 2). The plasmosomes remain in the nucleus during the pro-
phase, and are dissolved at the time of the breaking down of the nuclear
membrane. The accessory chromosome is usually closely applied to one
of these nucleoli, although it may be entirely free from both.

Thus the conditions at this time are quite similar to those found in
Scolopendra subspinipes (Blackman, :05*), where a portion of the residue
of the karyosphere is nucleolar material, while the other portion is a
modified chromosome. In Scolopendra heros, on the contrary, all the
products of the karyosphere are chromatic. One point of difference,
however, between the spermatogonia! prophases in Lithobius on the
one hand, and in the two species of Scolopendra (Blackman, :03, :05'')
and in Scutigera forceps (Medes, :05) on the other, is the shape and
appearance of the chromosomes. In Lithobius these elements are
slender granular segments, similar to the corresponding structures in
insect spermatogonia, while in the other three species mentioned the
chromosomes are in the form of small rounded granular masses, which
■ never lengthen out to form threads. The later stages of the sperma-
togonia! mitosis offer no points of especial interest, and will not be
described in this paper.

The telophase stages of the last spermatogonia! division are similar
in all essentia! respects to those in Scolopendra and Scutigera. The
daughter chromosomes, as they move toward opposite poles of the
spindle, are aggregated into dense masses. At this stage the chromo-
somes are rounded bodies possessing clear-cut outlines. Soon, however,
just as in Scolopendra, they begin to lengthen out and become granular,
and thus in place of a mass of closely aggregated homogeneous bodies
there soon arises a more loosely arranged group of granular segments.
At first this is enclosed in no membrane, but lies within a vacuole of
hyaloplasm. Eventually, however, a definite nuclear membrane appears
and the chromatin segments become distributed throughout the space
enclosed by it (Figures 3, 4). It may now be readily seen that the
number of these chromatin segments is much smaller than the number
of chromosomes seen during the spermatogonia! prophase. Carefid
counts give the number of segments at this stage as 24, which, to-
gether with the accessory chromosome, produces a total of 25, the
number of chromosomes characteristic of the following mitosis. Thus
here, just as in Scolopendra, pseudo-reduction has already occurred as

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 493

the result of the union in pairs of the spermatogonia! chromosomes
during the telophase of the last mitosis of the division period.

Evidences of the nature of this union are to be seen in many nuclei,
although, owing to the close grouping of the chromosomes in the telo-
phase, actual stages in the union are very difficult to find. In the two
species of Scolopendra (Blackman, :03, :05, :05'') it has been shown
that this union of the chromosomes is accomplished by an end to end
fusion of the elements, similar to that described by Montgomery (:00,
:0l) for Peripatus, and by Sutton (:02) for Brachystola. In the three
species of Lithobius studied, evidences of the origin of the spermatocyte
chromosomes by a similar union are seen in Figures 3 and 4. The
chromatin segments are often bent at a sharp angle at about their
middle point, the two equal limbs representing spermatogonia! chromo-
somes which have conjugated during the preceding telophase. Thus
in Lithobius, just as in Scolopendra and in Scutigera, there is no stage
in which all of the chromatin is arranged in a continuous spireme, and
at no time is the number of chromatin segments less than the number
of chromosomes characteristic of the succeeding metaphase.

In the meantime, even before the reconstruction of the daughter
nuclei in the last spermatogonia! telophase, the cells have entered
upon that period of remarkable growth characteristic of the spermato-
cytes of chilopods. This growth is so marked that at the time of the
appearance of the nuclear membrane (Figures 3, 4) each of the daughter
cells has attained a size about equal to that of the parent cell. In
succeeding stages this increase in size continues (Figures 3-8), until
finally in the vesicle stage (Figure 10) the diameter of the spermato-
cytes is more than ten times that of cells in the spermatogonia! telo-
phase. Thus the ultimate size of the spermatocyte in the vesicle stage
is even greater than in Scolopendra.

At the time of the reconstruction of the nuclear membrane, as has
already been mentioned, chromatin segments of the reduced number
become scattered throughout the entire nuclear cavity (Figure 3). As
the cell continues to grow these chromatin threads become more diffuse
and the granules composing them become finer, and are now in a con-
dition apparently similar in all respects to the segmented spireme stage
of the spermatocytes of other animals. Now, however, a rearrange-
ment of the chromatin begins to take place, which seems to be charac-
teristic of chilopod spermatocytes and is seldom met with in the male
cells of other animals. These changes have been studied in detail in
Scolopendra (Blackman, :03, :05, :05^) and in Scutigera (Medes, :05),
and while they are essentially similar in these two genera, they still
present several interesting minor differences.

494 PROCEEDINGS OF THE AMERICAN ACADEMY.

In Scolopendra heros (Blackmail, :03, :05) their changes are as fol-
lows : " The chromatin segments begin slowly to break down, and their
substance becomes aggregated about the accessory chromosome, thus
apparently increasing the size of this body enormously. This process
continues until finally all of the chromatin of the cell is aggregated in
one large intensely staining body." (Blackmail, :05, p. 14.) This body
I have called the karyosphere. It is not a simple homogeneous body of
chromatin, but a very complex mass of chromatin fibres closely en-
veloping a solid chromatin body, the accessory chromosome. It is
made up of chromatin, linin, and karyolymph, but contains no nucleolar
material.

In Scolopendra subspinipes (Blackman, :05^) the conditions are
slightly different, owing to the presence of a true nucleolus. Here the
karyosphere is formed by the massing together of all of the chromatin
of the cell, but it also contains a nucleolus in addition to the material
derived from the chromosomes. The chromosomic material is deposited
in a dense granular mass over the outside of the nucleolus, forming a
mantle around it.

In Scutigera forceps (Modes, :05) the origin of the karyosphere is
quite similar to that in Scolopendra heros. The material composing
it in these early stages is derived entirely from the chromosomes.
Later, however, during the growth period, the karyosphere acquires in
addition a large quantity of nucleolar material, as is shown both by
its staining reaction in the vesicle stage and by the nucleolar residue
remaining after the origin of the chromosomes in the prophase fol-
lowing. Thus, while the component materials of the karyosphere in
Scutigera are identical with those of the same body in Scolopendra
subspinipes, there is in the former no such definite localization of
chromatic and nucleolar material as is found in the latter.

In the three species of Lithobius which I have now studied, two con-
ditions exist as to the origin of the karyosphere. In Lithobius mordax
the origin of the karyosphere is more like that in Scolopendra heros
and Scutigera forceps, while in Lithobius multidentatus and Lithobius
sp. the stages observed resemble more closely those found in Scolopendra
subspinipes.

Stages in the formation of the karyosphere in Lithobius mordax are
shown in Figures 3, 5, 6, 7, and 8. In Figure 3 the outlines of the
accessory chromosome can still be distinguished. Closely apposed to
one side of this element are several masses, which are more granular.
These represent chromatin segments which have become shortened and
thickened by a rearrangement of their granules, and have taken up a
position upon one side of the accessory chromosome. Other chromo-

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 495

somes, still in the form of granular segments, are in contact with the
forming karyosphere and very plainly are about to undergo a similar
process. This disposition of the chromosomes around the accessory
chromosome continues (Figure 5) until all of them are aggregated in
one irregular densely staining mass, the karyosphere (Figures 6, 7).

In Scolopendra heros it was never possible to establish conclusively
that the chromatin enters the karyosphere as definite individual chromo-
somes. That this is the case was, however, ahvays believed by the
author, and indeed there was considerable evidence supporting this
view. In Scolopendra subspinipes more convincing evidence was found,
as the nucleolar material there present serves as a background against
which the chromosomes can be seen in favorable cases. However, some
doubt might still remain.

The stages in the formation of the karyosphere in Lithobius mordax
furnish better evidence of the individuality of the chromosomes during
the early spermatocytic stages than those of any other myriapod yet
studied. It can be very plainly seen that the chromosomes enter into
the formation of the karyosphere as distinct ekments tvithoitt losing their
individuality. Evidences of this fact are found at all stages in the
formation of the karyosphere in the irregular lobulated structure of
this body (Figures 5-8). Each one of these lobules undoubtedly repre-
sents a chromatin segment which has become shortened and thickened
into an irregularly rounded body. In Figure 5 several of these chromo-
somes still remain detached from the rest and their identity is easily
recognized. In Figure 6 the individuality of many of the elements
may still be readily seen, while in Figure 7 the grouping of the
chromosomes is but little closer.

Shortly after the stage shown in Figure 7, the karyosphere begins
to undergo a change by which the dense mass of chromosomes is con-
verted into the completely formed karyosphere of the vesicle stage.
This change consists in the acquisition of a large amount of nucleolar
material. This results in three changes in the appearance of the
karyosphere. The first two of these are changes in size and shape, by
which the irregular lobulated karyosphere of the young spermatocytes
is converted into the larger spherical body characteristic of the vesicle
stage. The presence of nucleolar material in the karyosphere also
brings about a change in its staining reactions.

In Figure 8 is seen an early stage in this metamorphosis. By com-
paring the karyosphere in this cell with that shown in Figure 7, the
changes mentioned above are immediately apparent. The karyosphere
has undergone a considerable increase in size and a portion of the
surface has assumed a regular rounded outline. The portion of the

496 PROCEEDINGS OF THE AMERICAN ACADEMY.

karyosphere possessing the regular outline has also changed in its
reaction to the stains, showing that it is in this part that the nucleo-
lar substance lies. Here certain rounded areas, which represent the
chromosomes, still retain the haematoxylin strongly, while surrounding
these chromosomes are irregular areas which show little or no affinity
for the chromatin stains. Thus the rounding off of the karyosphere is
due to the filling of the interstices between the chromosomes with
nucleolar material, which thus acts as the matrix in which the chro-
matin is embedded. The acquisition of achromatic material continues
during succeeding stages until, in the vesicle stage, the fully formed
karyosphere is considerably larger, possesses a clearly cut outline, and
is spherical in shape.

The origin of the karyosphere in Lithobius multidentatus and
Lithobius sp. 1 differs from that in Lithobius mordax in several re-
spects, and at this stage the cells resemble those of Scolopendra sub-
spinipes more than they do those of Scolopendra heros. This is due
to the facts that the young spermatocytes of these two species of
Lithobius contain one or more true nucleoli and that this nucleolar
material also enters into the formation of the karyosphere. In Figure 4
is represented a young spermatocyte of Lithobius sp. 1 showing an early
stage in the formation of the karyosphere. The spermatocytes of this
species are characterized by the presence of two or more nucleoli dur-
ing the growth period. Figure 4 shows a cell possessing two nucleoli.
Chromatin in the form of diffuse segments is already being deposited
upon the surface of one of these, and the accessory chromosome may
be seen embedded in one side of it. The other nucleolus (Figure 4) is
still free of chromatin, but would later be involved in these changes
also. Each nucleolus usually forms the basis for a separate karyo-
sphere, as may be seen by referring to Figures 14, 16, 17. In Figure
15 one of the nucleoli contains no chromatin deposits whatever. This,
however, is exceptional.

In Lithobius multidentatus the origin of the karyosphere is similar
to that just described for Lithobius sp 1, except that here only one nu-
cleolus occurs, and only one karyosphere is formed (Figures 11-13).

After all of the chromosomes of the cell have become massed to-
gether to form the karyosphere, the remaining portion of the nucleus
no longer stains deeply with chromatin stains (Figures 5, 6) and is no
more dense in its structure than the cytoplasm. Soon irregular amor-
phous deposits appear in the nucleus, and these form a mantle sur-
rounding the karyosphere. This mantle, however, does not envelope
the karyosphere closely, but is separated from it by an area of trans-
parent substance so that this body seems to lie in a vacuole of hyalo-

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 497

plasm (Figures 5, G, and 7). The remaining portion of the nucleus is
occupied by an irregular reticulum of linin fibres.

As the cell continues to grow this amorphous deposit increases in
amount (Figures 8, 9, 10), until finally, in the vesicle stage, it forms
quite a conspicuous portion of the nucleus (Figures 9, 10). Just
what the significance of this material may be I am at a loss to say.
From its straining reactions, however, it is seen that it is chemically
similar to the nucleolar substance. In Lithobias mordax it is much
more abundant than in either of the other species studied, while in
Lithobius sp. 1 (Figures 14, 17) very little if any occurs. Thus it varies
inversely with the amount of nucleolar material contained in definite
nucleoli. In Lithobius multidentatus less is present than in L. mor-
dax, but in the former species (Figures 11, 13) it occurs in much
more definite bodies, and these often approach nucleoli in form and
structure. So the conclusion would seem justified that these deposits
represent nucleolar material which has never become arranged in the
form of distinct nucleoli.

We will now return to the early spermatocyte and consider the evo-
lution of the extra-nuclear structures. First, as regards the centro-
some. In Scolopendra heros (Blackman, :05) I was so fortunate as to
be able to find the centrosome during all the stages from the spermato-
gonium to the mature spermatozoon. Here it was readily found and
recognized, owing to the fact that during the growth period it is en-
closed in a specialized portion of the archoplasm. In Lithobius, how-
ever, such aggregations of archoplasm do not occur, and the centrosome
has not been observed during the growth period. In Figure 7 two
small, densely stained bodies enclosed in a denser portion of the
cytoplasm are shown. It is, however, impossible to state with any
certainty that these are centrosomes, owing to the fact that such
structures have not been observed at other stages of the growth
period. However, it does not necessarily follow that no centrosome
exists during the growth period, as no determined effort has been
made to find it and study it, as was done in Scolopendra.

The structure of the cytoplasm in Lithobius has been studied by P.
et M. Bouin (99), and by Meves und von Korff (:0l). The brothers
Bouin report the presence within the cytoplasm of Lithobius forfica-
tus of certain irregularly formed bodies, which they have designated
"formations ergastoplasmiques." These are believed to arise by the
disintegration of the astral rays. Just before the prophase these de-
posits undergo what is described as a gelatinous metamoi'phosis and
are not seen later than the early proj^hase. Meves und von Korff
(:0l), working on the same species, find these bodies in all phases of the

VOL. XLII. — 32

498 PROCEEDINGS OF THE AMERICAN ACADEMY.

first spermatocyte mitosis, although in later stages they are reduced
to smaller granules. In Scutigera (Modes, :05) structures which are
probably homologous are formed both in the nucleus and in the cyto-
plasm. These bodies, which are classed as metaplasm, stain densely
and vary widely in number in different cells. As the prophase ap-
proaches, they begin to disintegrate, and soon disappear entirely.

In Scolopendra (Blackman, :05) there are two sorts of formations
occurring in the cytoplasm. The first of these is the archoplasm,
which is similar in structure to the cytoplasm and appears as a thick-
ened and condensed part of it. The second consists of rather small,
dark staining granules, which in appearance and behavior are similar
to those in Scutigera. These undoubtedly represent metaplasm —
either ingested food particles, or by-products of the cell activity.

In well-preserved cells of the three species of Lithobius studied
I have been able to find no structures corresponding to the " forma-
tions ergastroplasmiques " of P. et M. Bouin, although in sections of
poorly fixed material such deposits are often seen. The cytoplasm in
Lithobius is very fine meshed and seems to be very difficult to fix
properly. When wrongly treated, the fine reticulum becomes dis-
torted and irregularly massed together in such a manner as to give
the appearance of definite structures, and these I believe have been
incorrectly regarded as normal structures. However, a few small, dis-
tinct granules do seem to be present at all stages of the first sper-
matocyte, and these I consider to be metaplasm, i. e., food material or
by-products of metabolism.

In Lithobius no such aggregations of archoplasm exist as are char-
acteristic of the growth period and vesicle stage of Scolopendra. On
the contrary, all of the cytoplasm of the cell seems to be of about the
same consistency. Indeed, both in structure and staining reactions
the cytoplasm in the vesicle stage is quite similar to that in the pro-
phase of the first spermatocyte of Scolopendra, after the archoplasm
has been dissolved in the hyaloplasm and dispersed throughout the
entire cell. This similarity and the fact that there are no special
aggregations of archoplasm have led me to conclude that during the
vesicle stage in Lithobius the archoplasm is dispersed throughout the
cell. This causes the cytoplasm at this stage and during the early
phases of mitosis to stain more strongly than at other times.

At the completion of the growth period the spermatocyte of Litho-
bius mordax in the vesicle stage presents the appearance shown in
Figure 10. The size of the cells is remarkable, as they often reach an
average diameter of more than 100 micra, thus being even larger than
the spermatocytes of Scolopendra and Scutigera. In the various

BLACKMAN. — SPERMATOGENESIS OF THE MYllIAPODS. 499

species of Scolopendra (Blackman, :01, :05, :05*; Bouin, "•03, :03*) the
spermatocytes in the vesicle stage are of two distinct tj^ies as to size.
In Lithobius, however, while there is considerable variation in the
sizes of the cells during the vesicle stage, no such great differences
exist, and the cells cannot be divided into two types on this basis.

The cells in the vesicle stage of the three species of Lithobius are
quite similar to one another as regards the extra-nuclear portion, but
differ considerably in the structure of the nucleus, so much so that
the species may be readily identified by this alone. The differences
existing between Lithobius mordax and L. multidentatus are less ap-
parent than those between either of these and the Bermuda species, yet
very little study is necessary for identification. The greatest of these
specific differences are seen in the structure of the karyosphere, but the
condition of the achromatic structures also varies in the three species.

What may be taken as the typical appearance of the nucleus in
Lithobius mordax is shown in Figure 10. The karyosphere is stained
an intense black with haematoxylin and green with the Ehrlich-
Biondi mixture, showing that it is rich in chromatin. However, in
many sections in which the decolorizing has been carried further, the
entire karyosphere does not take the chromatin stain, thus showing
that this body is not made up entirely of chromatin, as is that of
Scolopendra heros, but contains nucleolar material also, as do the
similar structures in Scolopendra subspinipes and Scutigera forceps.
A karyosphere of this sort is shown in Figure 9. Here the chromatin
is arranged in the form of a network of anastomosing strands which are
embedded in the nucleolar substances. No portion of the nucleus
except the karyosphere contains any chromatic material. The con-
spicuous deposits which form an irregular mantle around the karyo-
sphere are very evidently achromatic material, as is shown by their
staining reactions.

In Lithobius multidentatus the karyosphere is much like that just
described. The chief difference lies in the fact that here the amount
of chromatin to each cell is considerably less. Thus the karyosphere
is not usually stained so black and the nucleolar portion is more evi-
dent (Figures 11, 12, 13). " It is also true that the chromatin is usually
found only on the periphery of the karyosphere outside the nucleolus,
resembling in this respect Scolopendra subspinipes. The deposits of
achromatic substance in the nucleus are much less abundant and are
in more definite bodies, thus allowing more of the linin network to be
seen.

The nucleus in Lithobius sp. 1 differs from that of either of the two
species described in several particulars. There are no indefinite

500 PROCEEDINGS OF THE AMERICAN ACADEMY.

masses of achromatic material, this all being incorporated in the nu-
cleoli, of which there are several, the amount of nucleolar material
being greater. Usually each nucleolus contains one or more chromo-
somes and thus constitutes a karyosphere (Figures 14-17). The num-
ber of karyospheres in a nucleus varies from one (Figure 15) to four
(Figure 18) or even six, the most common number being two (Figure
16), while three are often seen (Figures 14, 17). When the number
of karyospheres is greater, the relative amount of chromatin in each is
smaller and the chromatin occurs in more definite masses. Often it
is arranged in the form of a single thread embedded in the nucleolar
material (Figure 14), while in other cases it occurs in several irregular
masses (Figures 14, 1.5, 17). It is usually enveloped in the nucleolus
and not deposited upon the periphery, as in Lithobius multidentatus.

The origin and behavior of the chromosomes during the prophase
of the first spermatocyte of myriapods has been described differently
by different workers. The first account is that by Carnoy (85),
which deals with the spermatocyte mitoses of Lithobius forficatus,
Scutigera arachnoides, Geophilus, and Scolopendra dalmatica. In
Lithobius, Scutigera, and Geophilus the nucleole-noyau (karyosphere)
gives rise to the chromatin thread, from which the chromosomes are
derived. The process of tetrad formation was not studied at all. In
Scolopendra dalmatica the nucleolus is said to take no part whatever
in the origin of the chromosomes.

Later investigators upon European myriapods have arrived at re-
sults quite different from those of Carnoy. Meves und von Korfif
(:0l) confined their observations almost entirely to the peculiar modi-
fication in the achromatic division figure of the first spermatocyte of
Lithobius forficatus. The chromosomes were but little studied, and
those figured are already in the form of distinct elements. The de-
scription, however, gives the impression that they arise from the net-
work of the nucleus.

In several short papers from the University of Nancy, P. Bouin, M.
Bouin, and R. Collin have dealt briefly with the chromosomes, al-
though most of their work has been upon achromatic structures. In
Geophilus linearis P. Bouin et B. Collin (:0l, page 101) find no con-
nection between the large " nucleolus " and the origin of the chromo-
somes, but on the contrary state that these elements arise from a
chromatic reticulum: "Le reticulum chromatique est constitud par
de tres fins microsomes distribuds sur les mailles du rdseau de liuine ;
au niveau des points d'entrecroisement de ce r^seau, ils sont rassembl^s
en amas plus ou moins volumineux. Ces microsomes chromatiques
se r^unissent bientot en petites masses qui se condensent rapidement

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 601

en sphtTules homogc!ne.s ; celles ci paraissent subir tout de suite une
segmentation transversale. Peu de temps aprtis le d^but de ces pro-
cessus on peut voir, dissdmin(^s dans I'aire nucldaire, et aussi bien
contre la face interne de la membrane du no3'au que sur les trav(5es
du r^seau lininien, des chromosomes segmentes transversalement et qui
figurent, comme Tun de nous I'a duja signaled h, propos du Lithobius
forficatus, des sortes de diplosomes chromatiques minuscules. Ces
diplosomes, chez Geophilus linearis, sont au nombre de huit. lis nous
a 6t6 impossible, h cause sans doute de I'extreme petitesse de ces
formations, de nous rendre compte si les indices de la deuxi^me divi-
sion de maturation apparaissaient sur ces chromosomes d^s ce stade de
la car3'ociu6se." The authors conclude that each of the succeeding
mitoses results in a transverse division of the chromosomes.

The criticism by Grdgoire (:05) of these results of Bouin et Collin
seem to me to be just. He says (p. 284) : "Cette interpretation ap-
pelle plusieurs remarques. D'abord, si la description des auteurs est
exacte, il faut reconnaitre que cet objet est detestable pour I'dtude du
subjet actuel et qu'on n'en peut tirer de conclusion d'aucune sorte. En
effet, il semble bien impossible de savoir si la division en deux d'une
' spherule ' constitue une division transversale h mettre sur le pied de
ce qu'on appelle ailleurs de ce meme nom ; de plus, h la seconde cint;se,
comment fixer la valeur de la bipartition d'une 'granulation minu-
scule ' 1 L'objet, tel qu'il est d^crit, serait done h condamner au point
de vue actuel."

In a later paper P. Bouin et M. Bouin (:02) have published the
results of their studies on the chromatin reduction in Lithobius forfi-
catus. Here the chromosomes are larger than in Geophilus, although
still somewhat smaller than those described in this paper. The
authors believe that in Lithobius also the chromatic elements have no
connection with the large "nucleolus." But in the figures accompany-
ing this and other papers on the same species, it is seen that at the
beginning of the prophase the nucleolus is large and stains like chro-
matin, while later, after the chromosomes are formed, it is much
smaller and more lightly stained. However, the authors state that
the chromosomes arise from the nuclear reticulum. The chromatin
granules, while still a part of this network, undergo cleavage, so that
each thread of the reticulum becomes double. Later the chromatin
granules collect and fuse to form bipartite chromosomes or " diplo-
somes." No true tetrads were observed, but the authors conclude
that reduction is accomplished by a longitudinal division followed by
a transverse division.

In the American myriapods the origin and behavior of the chromo-

502 PROCEEDINGS OF THE AMERICAN ACADEMY.

somes of the first spermatocytes have heen studied in three species :
in Scolopendra heros (Blackman, :01, :03, :05), in Scolopendra sub-
spinipes (Blackman, :05*), and in Scutigera forceps (Medes, :05). In
these species the essential phenomena are similar, although the details
of the processes vary considerably. In all three forms the chromosomes
arise from chromatin stored in the karyosphere. The chromosomes
appear first as segments equal in number to the elements later taking
part in mitosis. These granular segments undergo first a longitudinal
and later a transverse cleavage, and soon take on the well-known cruci-
form shape characteristic of the heterotypical chromosomes of inverte-
brates. During the late prophase the chromatin granules fuse and the
tetrad becomes a homogeneous four-lobed chromosome.

The formation of the tetrads in Scutigera varies in one interesting
particular from the typical process as observed in Scolopendra, as has
been shown by Medes (:05, p. 163): "Immediately after leaving the
karyosphere the chromosomes shorten into dense granular cords. These
now undergo a longitudinal cleavage and the double thread of chroma-
tin breaks up into a number of short portions of irregular size." These
portions are spherical in shape and of homogeneous consistency ; they
appear to be lobules of chromatin in a liquid condition.

In describing the origin and behavior of the chromosomes of the first
spermatocyte in the forms used in the present paper, the observations
upon Lithobius sp. 1 will be given first, as here the phenomena are more
like those observed in other animals. Indeed, as regards the changes
in the chromosomes themselves, the nuclear processes are nearly identi-
cal with those in Scolopendra. The first change in the nucleus during
the prophase has to do with the appearance of the chromosomes, which,
as we have already seen, unite with the nucleoli during the early part
of the growth period to form several karyospheres. During the growth
period and vesicle stage this chromatin may be seen in the karyospheres
as dense masses or threads embedded in the nucleolar material. The
first change in the nucleus is in this chromatin. The dense masses
become more granular and more diffuse and move to the surface, thus
coming to lie outside the nucleolar portion. Strands of the chromatin
leave the karyosphere and lie free in the nucleus. This process con-
tinues until all of the chromatin has left the karyospheres. When this
is accomplished, the number of chromatic segments in the nucleus is
the same as the number of chromosomes participating in the succeed-
ing division. Figure 18 (Plate l) represents an advanced stage in
the disintegration of the karyospheres. Many of the chromosomes are
already free, while those which still remain in the karyosphere are
spread out as diffuse flocculent deposits upon the surface of the
nucleolar portions.

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 503

In later stages (Figures 19-21), when all of the chromosomes are free
in the nucleus, the nucleoli, much reduced' in size, may still be seen.
These nucleoli, although at first spherical (Figure 21), soon become
irregular in outline and rapidly disintegrate (Figures 19*^, 20). At
least a portion thus set free in the nucleus is used in the evolution of
the chromosomes.

The chromatin segments of the reduced number as they arise from
the karyosphere are diffuse granular threads (Figure Ls). These soon
elongate, and the granules composing them become coarser. The seg-
ments assume a variety of shapes, but most often they are roughly
U-shaped or V-shaped, just as they were in the early spermatocytes
before they entered the karyosphere. At about their middle point, —
i. e., at the angle of the V, or at the loop of the U, — there is very
often a small gap in the chromatin thread (Figure 18), as has been
observed by several investigators on other material (Montgomery, :00,
:05 ; Sutton, :02 ; Blackman, :03, :05, 05*; Foot and Strobell, :05).
This undoubtedly represents the point at which the conjugating
chromosomes united during synapsis.

Soon each segment undergoes a longitudinal splitting, resulting in
two more slender segments (Figures 19''-21). The halves thus result-
ing typically lie parallel to each other, but very often they are twisted
about each other, as is shown by several chromosomes in Figures 19^
and 20. Less often the ends of the halves may be separated and drawn
in opposite directions, as is the case with several chromosomes in Figures
19" and 19". Tyjiically, however, the two threads lie near each other
and are approximately parallel.

The next change in this double segment consists in the cleavage of
each of the halves at about their middle point, resulting in a four-
parted chromosome or tetrad. This is a transverse division of the
chromosome and occurs at the point where in preceding stages an
interruption in the chromatin was observed. Thus, when this division
is completed, it results in the separation of entire spermatogonia!
chromosomes.

As soon as the transverse cleavage is established the chromatids
revolve upon each other in one of several ways, producing tetrads vary-
ing in shape, but all referable to one type. The more common method
is as follows : At the point of transverse cleavage the threads show a
tendency to bend at a more or less acute angle, and in each half-segment
the adjacent ends produced by the cross division become drawn out in
the same direction, but perpendicular to the axis of the original thread,
while the corresponding portion of the other half is drawn out in the
same plane, but in an opposite direction. This results in the typical

504 PROCEEDINGS OF THE AMERICAN ACADEMY.

cross-shaped figures shown by several tetrads in Figures 19^ and 20.
The four arms of the cross are aj^proximately equal in length, and
each arm is split longitudinally. Thus the chromosome is formed of
four chromatids, each of which consists of a continuous chromatin
thread extending the length of the two adjacent arms and forming one
half of each (Figures 19^', 20). Another common shape assumed by the
tetrad is illustrated by the double- V figures (Figure 2()), similar to
those observed in other animals by Paulmier ('98), McClung (:00, :02),
Sutton (:02), Blackman (:01, :03, :05, :05''), Foot and Strobell (:05),
and others. These are obtained by a longitudinal and transverse
division of the V-shaped segments, no rotation of the chromatids occur-
ring. A third form of the tetrad is shown by chromosomes in Figure
22. Here the straight segment undergoes the two cleavages, as in the
more common type. It is not converted into the typical cross-shaped
figure, however, but remains as a straight band of chromatin consisting
of four parts — the chromatids.

In later stages of the prophase the changes in the tetrads consist
principally in a contraction of the arms and a condensation of the
chromatin. Thus, in a fairly late prophase (Figure 22) the more common
form of the chromosomes is still that of a cross, but the arms of the
cross are much shorter and thicker, and in the more advanced tetrads
the condensation of the chromatin granules has proceeded so far as to
mask the planes of cleavage, these being seen only in the most favor-
able cases. In still later stages the chromatin becomes more condensed,
and the tetrad goes to the equatorial plate as an apparently homo-
geneous body typically of a four-lobed shape.

Some of the chromosomes in the process of condensation pass through
stages similar to those described by Medes (:05) in Scutigera. The
chromatin, instead of massing together into one body, becomes con-
densed into a number of homogeneous globules, which lie embedded in
a more lightly staining substance (Figure 22). These globules later
fuse in such a manner as to form a metaphase chromosome of typical
appearance. This process will be followed more in detail in the other
species of Litliobius, where it is the common method.

The nuclear changes during the prophase in Litliobius mordax and
Lithobius multidentatus will be treated at one time, as they are essen-
tially similar in the two forms. In both of these forms all of the
chromatin of the nucleus is massed in a single karyosphere, which also
contains a considerable portion c f nucleolar material. In addition to
this there are plentiful deposits of achromatic material in the nucleus,
it being more abundant in Lithobius mordax than in the eastern species.
This material, although purely achromatic in nature, plays a part in
the evolution of the chromosomes.

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 505

Just as ill Lithobius sp. ?, the first nuclear change in the prophase of
the first spermatocyte concerns the chromatin in the karyosphere.
This leaves the dense masses and collects near the periphery either in
the form of coarse granular flakes or loose aggregations of small
globules. At the same time the achromatic deposits in the nucleus
break up into a number of diffuse, lightly staining masses (Figure 13),
which come into relation with the chromosomes as they arise fi'om the
karyosphere and become a part of them.

The chromatin arises from the karyosphere (Figure 23) in the form of
small globules, which, as they leave the karyosphere, become embedded
in the diffuse masses of the achromatic substance. These masses of
achromatin lengthen out into short segments, and in each of these the
chromatin becomes arranged in the form of distinct darkly stained glob-
ules (Figure 23). Thus each of these composite masses at this time con-
sists of a diffuse, lightly stained baud of achromatic material, in which is
embedded a single row of intensely black globules of chromatin. These
globules at this stage are always of about the same size, and are always
spherical, presenting the appearance of droplets of liquid chromatin. It
is not always easy to observe the typical arrangement of the chromatin
globules, as the chromosome is often so bent, or in such a manner
distorted, as to obscure their linear arrangement.

The changes immediately following the origin of the chromosomes
are similar in results to those in other animals. Each globule is divided
into two equal parts, so that the chromosome, instead of being com-
posed of a single row of chromatin particles, now consists of two such
rows (Figure 23), each of which contains the same number of globules.
This undoubtedly represents a longitudinal division of the chromosome,
as the linear arrangement of the globules doubtless has the same sig-
nificance as the similar arrangement of the granules in the ordinary
chromatin segment of the prophase. Following the longitudinal split-
ting, the transverse cleavage is accomplished in the same manner as in
Lithobius sp. 1 by a division of each row of globules at its middle. The
four chromatids thus produced may rotate upon each other in such a way
as to result in the typical cruciform tetrad (Figure 23), or may remain
a double row of granules with a gap between the two pairs nearest the
middle wider than that between any other two pairs. In Figure 23
two tetrads showing the typical cross-shaped form are shown ; these
are redrawn at the side of the figure with the achromatic portions
omitted and the globules comprising each chromatid connected by
lines, in order to show diagrammatically the author's interpretation of
their structure.

Owing to the distortions of the arms of the tetrad, it is often difficult

506 PROCEEDINGS OF THE AMERICAN ACADEMY.

to correlate the chromosomes at this stage with the type forms described.
In later stages this difficulty is rendered still greater by the changes
which next take place. These have to do with the condensation of the
chromatin by which the tetrads of this stage are converted into the
homogeneous chromosomes of the metaphase. The condensation is
accomplished by the fusing together of the chromatin globules com-
posing each chromatid of the tetrad. It eventually results in the pro-
duction of a tetrad made up of four large, deeply stained chromatin
globules, each one of which represents a chromatid (Figure 25).

Tetrads when they have reached this stage are very readily under-
stood and correlated with those of an earlier period. The intervening
stages (Figures 24, 25), however, proved rather puzzling. These are
much more numerous, and were observed before either the foregoing
or succeeding ones were found. After all stages were studied, how-
ever, the interpretation was simple. All of the chromatin globules
belonging to a chromatid do not fuse at once, but this is a process
involving considerable time. Thus the chromosomes may contain a
variable number of globules, and these often are of v^ery different sizes
(Plate 1, Figures 24, 25 ; Plate 2, Figure 26). In other cases chromo-
somes were found containing from six to ten spherules of approximately
equal size (Figures 24, 25, 27). The latter fact at first inclined me
to the belief that the chromosomes here were multiple chromosomes
similar to those found by Sindty (:0l) and McClung (:05) in insects,
where some chromosomes possess as many as ten chromatids. However,
a study of the chromosomes in the late prophase and in the metaphase
(Plate 2, Figures 28, 29, 30) rendered this plausible view untenable.
The fusing of the chromatic globules continues until all belonging to
one chromatid have united to form one large spherule of apparently
pure chromatin.

The structure of the chromosome when it has reached this stage is
shown by several examples in Figures 25 and 26. The four chromatids,
of about equal size and arranged symmetrically, are enclosed in an
irregular homogeneous or granular mass of achromatic material. In
the later prophase (Figures 26, 27) this achromatic mantle contracts and
becomes more dense, serving to bind the four parts of the chromosome
together. Thus the chromosomes at the time of the breaking down of
the nuclear membrane are four-lobed structures, which in Lithobius
mordax are apparently homogeneous in consistency.

In Lithobius multidentatus the formation of the tetrad is similar to
that in the western species. Apparently the only difference in the
chromosomes of the two species is in the smaller size of those in L.
multidentatus (compare Figures 26 and 27 with Figure 28) and in the

BLACKMAN. — SPERMATOGENESIS OF THE MYllIAPODS. 507

relatively larger amount of achromatic material contained in the fully
formed chromosomes. In Figures 26 and 27 are seen various late
stages in the evolution of the tetrads. The younger stages here shown
are practically identical with those of the other species. The later
stages, however, are here much clearer. The larger quantity of achro-
matic material causes the component parts to be more loosely bound
together, and the individual chromatids may be readily distinguished.
It is possible even to recognize the planes of the cleavage, although
it cannot be said with certainty which is longitudinal and which is
transverse.

When all of the chromosomes have left the karyosphere, the body
remaining is purely nucleolar in nature and stains lightly (Plate 1,
Figures 24, 25). It is considerably smaller than the karyosphere, and
in succeeding stages of the prophase gradually disintegrates. Usually
it breaks up into a number of irregular granular bodies, which may
persist even to the stage of the metaphase or anaphase (Figures 30, 32).
In such cells these particles are usually grouped irregularly in the
cytoplasm near the poles of the nuclear spindle, as has been observed
in both Lithobius by P. Bouin (:0l), by Meves und von Korff (:0l),
and in Scutigera by Medes (:05). In other cells, however, the nucle-
olus seems to disappear entirely, there being no residue at the time of
the formation of the spindle (Figure 29).

Often the nucleus, instead of breaking up into several granular
masses, becomes dissolved in the nuclear sap while retaining its
spherical shape. In such cases its circumference often remains
about the same, and sometimes even increases. An example of
this is shown in Plate l. Figure 23, the increase in circumference
being due to the presence of a large vacuole, which represents nucle-
olar material converted into a liquid. The contents of the vacuole
remain entirely unstained. In later stages more and more of the
nucleolus undergoes this change, until eventually none remains.

The changes in the achromatic structures in chilopods, and the
peculiarly modified spindle occurring in these forms, have been the sub-
ject of several papers. Meves und von KorfF (:0l) confined their ob-
servations to the first spermatocyte division. The centrosomes during
the early prophase are not upon the nuclear membrane, but lie at a
considerable distance Irom it. In later stages of the prophase they
diverge and pass through the cytoplasm to the cell membrane, where
they take up a position at opposite sides of the nucleus. Later, the
nuclear spindle arises, but the mantle fibres have no connection with the
centrosomes, each fibre ending free in the ctyoplasm. The astral fibres
radiating from the centrosomes have no connection with the spindle.

508 PROCEEDINGS OF THE AMERICAN ACADEMY.

The observations of P. Bouin (:00, :0l) upon the same species are
practically identical with the foregoing, and those of Bouin et Collin
(:0l) extend these observations to Geophilus linearis. These authors
(p. 106) reach the following conclusions regarding the modified spin-
dle: "De cette ^tude sur le fuseau chez le Geophilus linearis nous
nous croyons autorisds h conclure qu'il existe (^galement chez ce Myria-
poda une independence complete entre le fuseau d'une part, les spheres
et les corpuscles polaires, d'autre part, independence evidente au stade
de la m^tacin^se, plus difficilement observable, mais tr^s vraisemblable
cependant d6s prophases de la mitose."

In Scutigera forceps (Medes, :05) much the same condition exists in
the fully formed spindle, although earlier stages in its formation pre-
sent some important differences, and at this time more closely resem-
ble corresponding stages in the small spermatoc3i:e of Scolopendra
(Blackman, :01, :05). The centrosomes at first lie at the poles of the
spindle. Later, however, they leave this position and migrate to the
cell membrane, retaining no apparent connection with the nuclear
spindle. During the metaphase the author (Medes, p. 168) states:
" The mutual independence of the spindle-fibres and the astral rays in
Scutigera is the more clearly shown by the great dissimilarity in their
structure and general appearance ; for while the latter are very fine
and delicate, . . . the former are heavy, stain an intense black, and
present the appearance of wires, the ends of which may be distinctly
seen lying free in the cytoplasm."

In the present study of the achromatic structures the cells of Litho-
bius mordax have been used almost entirely, although observations
showing that the changes are common to the genus have been made
on the other two species. It will be seen that in general my obser-
vations on the achromatic structures are largely confirmatory of those
on the European species of Lithobius made by Bouin (:00, :Oi)and by
Meves und von Korff (:0l).

In the prophase of Lithobius mordax the centrosomes were first
seen in cells in which the nucleus is about in the stage represented in
Plate 1, Figure 23. At this stage there are two, one lying at each
side of the nucleus and about midway between this structure and the
cell membrane. Each centrosome has already begun to divide to pro-
duce the centrosomes of the second spermatocyte mitosis, and is now
a small, darkly stained, dumb-bell shaped body. It lies in a small,
clear area of the cytoplasm, and is surrounded by astral radiations
which, though very fine and delicate, are still distinct from the cyto-
plasmic reticulum.

In later stages the centrosomes move through the cytoplasm toward

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS, 509

the cell membrane, and finally take up their position on the inner face
of this structure. In this migration they do not move in opposite
directions, but proceed toward the side of the cell nearest to a line
connecting the two centrosomes. Thus when they reach the cell
membrane they usually both lie upon one side of the cell, which as yet
still preserves its rectangular outline (Figures 24, 25). During this
migration the nucleus also undergoes a movement in a similar direc-
tion, seemingly striving to retain its position in a line between the two
centrosomes. Thus at a time when the centrosomes have reached the
cell membrane, the nucleus lies very near to the same side of the cell,
as is shown in Figure 25. When the centrosomes come in contact
with the membrane, they immediately begin to move apart along its
inner face until they have reached opposite poles of the cell, the nu-
cleus meantime changing its position so as to lie between the two
(Figure 24).

Meanwhile the centrosomes have changed considerably in appear-
ance. By the time they have reached the cell membrane each is en-
closed in quite a distinct centrosphere. This is homogeneous or finely
granular, and stains slightly darker than the cytoplasm (Figures 24,
25). The astral rays have increased both in size and number, and
now penetrate to nearly all regions of the cytoplasm. Those from the
two poles may be distinctly seen to cross one another near the centre of
the cell (Figures 24, 25), although this crossing is not so apparent as it
is later (Figure 28). These fibres are entirely distinct from the cellu-
lar network, as the cytoplasmic reticulum is still evident except in the
regions immediately surrounding the poles. In these regions, how-
ever, the network seems to have entirely broken down, leaving only
the hyaloplasm and the penetrating astral rays. Thus each centro-
sphere is surrounded by a transparent area of considerable width
(Figures 24, 25), which serves as an excellent background for the cen-
trosome and centrosphere. Appearances similar to this have been
observed in other m)a'iapods by Meves und von Korff (:0l), P. Bouin
(:00, :01), and Medes (:05).

During the time of the divergence of the centrosomes upon the cell
membrane the cell has altered considerably in shape. In the vesicle
stage and early prophase the cells are typically rectangular in outline.
Now, however, they undergo a change by which their form becomes
approximately spherical. This I believe to be directly due to the ap-
pearance and development of the archoplasm (Blackman, :05), for the
rounding off of the cell is only perfected when the astral systems have
reached the height of their development (Plate 2, Figures 28-30).

The achromatic changes thus far described have been entirely inde-

510 PROCEEDINGS OF THE AMERICAN ACADEMY.

pendent of the nucleus, but during this same period the nucleus is
also active. Aside from the evolution of the chromosomes and the
disintegration of the nucleolus, which have already been described, the
linin reticulum has also changed. Before the origin of the tetrads, a
considerable portion of the nuclear area is occupied by the diffuse
masses of achromatic material, which is so abundant as to obscure the
greater part of the nuclear framework (Figures, 9, 10). After the
chromosomes have arisen from the karyosphere, however, this diffuse
material is collected into smaller and denser masses, which closely sur-
round the chromosomes. Thus the linin network is rendered visible
and is seen to consist of a coarse, irregular reticulum (Figures 23-25).
At first this is granular and stains very diffusely. As the tetrads
condense to form the homogeneous chromosomes of the metaphase, the
network becomes coarser and more irregular. At the same time the
linin fibres begin to lose their granular appearance and to take on
the form of more definite threads, which retain the stains much more
strongly. Thus the nucleus in the late prophase presents the appear-
ance shown in Figures 26 and 27 (Plate 2). The^linin network is
much more irregular than in preceding stages, and at many places is
made up of distinct threads which have lost their granular structure.
In later stages they become more and more numerous and definite,
and the network becomes more and more broken up, although as yet
the fibres have no definite arrangement with reference to the poles of
the cells.

The breaking down of the nuclear membrane and the formation of
the central spindle is a process involving considerable time, as is
shown by the numerous cells found in these stages. The nuclear
membrane disappears rather early, often before all of the chromosomes
have attained their homogeneous structure. The distinction between
nuclear and cytoplasmic material is not so early lost, however, and
may indeed be seen until the following anaphase. In the late pro-
phase the line of demarcation between nuclear material and cytoplasm
becomes very irregular, and shortly before the completion of the spin-
dle presents the appearance shown in Figure 28. The distinction
between nuclear sap and cell sap is shown by the much more trans-
parent appearance of the former. The linin at this time (Figure 28)
is all in the form of definite threads, and these are being oriented so
as to point toward the poles.

In the later prophase this orientation of the linin fibres continues
until it eventually results in the formation of such a spindle as is repre-
sented in Figures 29, 30. The central spindle is derived from the
nucleus, as is shown by numerous stages in its formation. The chromo-

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPOKS. 511

somes lie near the centre and are arranged in nearly one plane, forming
an equatorial plate. Extending from the chromosomes toward the
poles are the linin fibres, which have now become mantle fibres. These
at first (Figure 2i») are comparatively short, but later they lengthen
(Figure 30) and extend about one half of the distance from chromo-
some to centrosome. They are much thicker than the astral rays and
stain much darker. The central spindle, or nuclear spindle, is entirely
distinct from the astral systems and lies in a clear area devoid of retic-
ulum, which represents the nuclear sap that has not yet become mixed
with the cytoplasm. The entire spindle is barrel- shaped, the fibres
converging slightly, but not coming to a point. At this time, and at
all later stages of mitosis, the fibres if continued through the cyto-
plasm would converge at the centrosomes, thus showing that these
small bodies, while not directly connected with the nuclear spindle,
still are the directing forces which determine its orientation and toward
which its fibres converge.

During the late prophase and metaphase the astral systems continue
to develop, the rays becoming longer and more numerous. In the
equatorial region they may often be seen to cross, although this cross-
ing of the rays is not so pronounced as it is later during the anaphase
(Figure 32), at which time the archoplasmic structures reach their
highest development. In the metaphase (Figure 30) the centrosome
has often already divided to form the centres of the second division,
and this is always completed by the anaphase. The two centrosomes
are surrounded by the centrosphere just as in the prophase. The
lighter area of cytoplasm surrounding the centrosomes, however, is
usually much reduced by the time the spindle is completed (Figure 29),
and usually disappears entirely in the early anaphase. The cell mem-
brane in the region of the centrosomes is always depressed during meta-
kinesis and cytoplasmic cleavage (Figures 29-34). This depression first
becomes apparent in the late prophase at the time the outline of the ceU
is becoming rounded. This phenomenon probably has the same signifi-
cance as that ascribed to it in Scolopendra (Blackman, :05, p. 55).

With the formation of the nuclear spindle the chromosomes, which
heretofore have been scattered throughout the nuclei, become lined up
near the middle of the spindle to form a fairly definite equatorial plate
(Figures 29, 30). While they do not all lie in exactly the same plane,
they are still arranged much more regularly than in Scolopendra. We
have seen that the characteristic form of the chromosomes in the late
prophase is that of a four-lobed structure, each lobe representing a
chromatid. The chromosomes in the equatorial plate are likewise
typically of this form, yet there are individual variations both in the

512 PllOCEEDINGS OF THE AMERICAN ACADEMY.

form of the tetrads and in the attachment of the mantle fibres which
are interesting and instructive. A peculiarity seen in these chromo-
somes which I have not seen reported by any other observer is shown
in Figures 29-31. The chromosomes here represented were studied in
preparations in which the extraction of the haematoxylin had been
carried farther than usual. This caused the greater part of the
chromosome to stain not a dense black, but a dark gray. At the ends
of each tetrad, at the point where the mantle fibres attach, there is a
small, distinct body which stains much darker than the rest of the
chromosome, and is of about the size of the centrosome (Figure 31).
This spherule is embedded in the chromosome and is continuous with
the mantle fibre and appears to be an enlargement or knob upon the
end of this thread. Whether this body has any other significance than
that of serving as an attachment to the chromosome I am unable to say,
but it is a very distinct structure and is always found in the metaphase
chromosome. The position of this body is very useful in determining
the exact point of attachment of the mantle fibres and as an aid in
determining whether the division of the chromosome is transverse or
longitudinal. Usually the mantle fibres are attached at opposite ends
of the four-lobed chromosome, and in such cases the fact that the
division is longitudinal can be determined only by the shape assumed
by the chromosome during the gliding apart of the two component
dyads (McClung, :00 ; Blackman, :03, :05). Quite often, however, the
mantle fibres attach to two of the adjacent lobules or chromatids of
the tetrad (Figure 31). In such cases the chromosome lies with its
longer axis parallel to the equatorial plate and division occurs by the
separation of the chromosome along its longer axis. Such chromo-
somes are seen in all equatorial plates studied and are represented in
Figures 29-31.

Thus the shape of the chromosomes at this time strongly indicates
that the division of the first spermatoc)rte is a longitudinal one, but
the best evidence of this is seen in the early prophase and during the
anaphase of the first spermatocyte division. We have seen that in
the prophase the first change in the chromatin segment consisted in the
longitudinal cleavage. It is but natural, then, to believe that this
longitudinal division is the one first completed in the two mitoses
following. In the anaphase of the first spermatoc)'te, strong evidence
as to the character of the chromosomic division j ust completed is fur-
nished by the shape of the daughter chromosomes during their passage
toward the poles. In Figure 32 is shown a mid-anaphase of the first
spermatocyte. The chromosomes are already approaching their final
position, but as yet are not massed together as they are at a slightly

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 513

later stage (Figure 33). The chromosomes are of a distinctly dumb-
bell shape, the constriction at the middle of each one representing the
line of transverse cleavage at which point the chromatids separate
during the following metaphase. During the succeeding stages (Figures
33, 34) and in the prophase of the following mitosis (Figure 35) the
chromosomes retain this shape. In the metaphase of the second
spermatocyte (Figure 36) the dumb-bell shaped elements are arranged
with the constriction parallel to the equatorial plate and the separa-
tion of the component chromatids occurs at this place. This is the
reduction division of the chromosomes, and by it the parts of the
bivalent element are separated, doubtless at the same point at which
they united during the telophase of the last spermatogonium.

In the meantime the nuclear spindle of the first spermatocyte remains
entirely independent of the centrosomes and their system of astral rays.
During the division and separation of the chromosomes the mantle
fibres elongate considerably and their polar ends approach the centro-
somes (Figure 32), but at no time do they abut upon it. Thus the
chromosomes are evidently not separated by the contraction of the
mantle fibres, but these seem merely to act as runways along which
the daughter chromosomes move as they approach the poles. This,
however, does not necessarily mean that the centrosomes do not have
an important function in the separation of the chromosomes, for the
influence of the chromosomes over the nuclear spindle is at all times
apparent. The nuclear spindle is oriented parallel to a line connecting
the two poles of the cell, and at all stages the mantle fibres converge
toward the centrosomes. It seems probable that the separation of the
daughter chromosomes is accomplished by an attractive force exerted
upon them by the centrosomes rather than that they move apart by a
force inherent in themselves. At any rate it cannot be disputed that
the centrosomes determine the direction of this migration.

In a former paper (Blackman, -.05) I have given at some length
reasons for believing that the centrosomes and astral rays play an im-
portant part in the cytoplasmic cleavage. This work upon Lithobius
strengthens the belief there expressed by showing that similar phenom-
ena occur here also. The astral rays are not so conspicuous as in
Scolopendra, but in all other respects they are essentially the same,
and in Lithobius, just as in Scolopendra, I believe that the constriction
of the cell is brought about by a force which is inherent in the centro-
some and is exerted upon the cell membrane through the astral rays.

The further changes in the maturation divisions offer but few points
of special interest, and will be treated very briefly here. After the
separation of the chromosomes in the first spermatocyte division, the

VOL. XLII. — 33

514 PROCEEDINGS OF THE AMERICAN ACADEMY.

mantle fibres extend between the two masses of daughter chromosomes,
presenting the peculiar appearance shown in Figure 33. The nuclear
substance may still be distinguished from that of the ordinary cyto-
plasm by its more transparent appearance. With the constriction of
the cell, however, the distinction between nuclear-sap and cell-sap is
finally lost, although a disc of more transparent material still remains
in the plane of constriction until cell division is nearly complete
(Figure 34).

By the constriction of the cell, the interzonal filaments are grouped
together in a sheaf-like bundle. This is much shorter and broader
than in Scolopendra, and persists but a short time. At the plane of
constriction each fibre is interrupted by a small enlargement. These
bodies at first occur only in the superficial fibres, where, by their fusion,
they form a darkly stained ring about the sheaf of spindle remnants
(Figure 35). Later, however, as constriction proceeds still farther, the
interzonal filaments entirely disappear, while the ring surrounding them
at a former stage has been converted into a darkly stained plate.
This is continuous with the constricted cell membrane, and closes the
opening between the two daughter cells. In sections it appears as a
black band, and extends through a considerable depth of focus.

The second spermatocyte mitosis follows the first very closely, there
being no distinction between the telophase of the first and the prophase
of the second division (Figure 35). The centrosomes do not leave their
position upon the cell membrane, but in separating move along this
structure until they arrive at opposite sides of the cell. The nuclear
membrane then breaks down, and the spindle is formed. This spindle,
just as in the first spermatocyte division, is truncate at the poles and
remains entirely distinct from the astral systems.

The succeeding changes in the second mitosis are so similar to those
in the first spermatocyte as to render separate description unnecessary.
The dividing cells in the second spermatocyte may, however, always be
readily distinguished from those of the first by several characteristics.
The cells are much smaller, the spindle is more attenuated, and the
chromosomes are of quite a different shape. The changes in the sper-
matid during its development into the spermatozoon will be the subject
of a later paper.

Summary.

Pseudo-reduction is accomplished by an end-to-end union in pairs
of the chromosomes during the telophase of the last spermatogonia!
division. All of the chromosomes take part in this except the ac-
cessory chromosomes.

BLACKMAN. — SPERMATOGENESIS OF THE MYRIAPODS. 515

During the early part of the growth period all of the chromosomes
become massed together to form the karijosphere. The chromosomes enter
this body as distinct elements, and the indlcridual elements can be recog-
nized for a considerable time. The karyosphere also contains nucleolar
material.

The karyosphere varies in structure with the species. In Lithobius
mordax the amount of nucleolar material is less than in the other
species studied. In Lithobius multidentatus the chromatin is periph-
eral in position, and surrounds the nucleolar material. In Lithobius
sp. 1 the amount of nucleolar substance is greater, and there are always
two or more karyospheres. The chromatin in this species is usually
central in position, and is surrounded on all sides by nucleolar
material.

During the growth period no special aggregations of archoplasm are
presejit, but this substance is dispersed throughout the cytoplasm of the
cell.

In the three species of Lithobius studied the chromosomes arise from
the karyosphere and develop into tetrads, but the manner of development
of the tetrads varies with the species.

In Lithobius sp. ? the stages in the formation of the prophase
chromosome are similar in all essential respects to those of the
typical arthropod tetrad.

In Lithobius mordax and Lithobius multidentatus the chromatin
arises from the karyosphere in the form of globules ivhich, as they arise,
become arranged iii a single row for each chromosome, and each chromo-
some is embedded in a separate mass of achromatic material. In the
formation of the tetrad each globule divides into two equal halves, giving
rise to two parallel rows of globules. This represents the longitudinal
or equational division of the chromosomes. The transverse or reduction
division is accomplished by a separation of the roivs of globules at their
middle point, the globules themselves remaining intact. Ln later stages
the globules forming each chromatid fuse into one, thus giving rise to
a tetrad composed of four sj)herules of chromati7i.

After the origin of the chromosomes, the nucleolar portion of the
karyosphere remaining gradually breaks down. Portions of it may
often be seen at the poles of the nucleolar spindle during the meta-
phase and anaphase of the following division.

In the early prophase the centrosomes separate and move through the
cytoplasm to the cell membrane. Along the inner face of the membrane
they migrate apart until they are upon opposite sides of the cell.
During the migration the cell outline becomes rounded off, and by the
time of the metaphase the cell is spherical in shape.

516 PROCEEDINGS OF THE AMERICAN ACADEMY.

"When the centrosomes are at opposite sides of the cell the nuclear
membrane breaks down, and its component parts become rearranged
to form a spindle. The linin netwoi'k is transformed directly into the
mantle fibres.

The nuclear spindle remains entirely disti7ict from the centrosomes
and astral systems. Its fibres do not converge at a special point at
each pole, but end free in the cytoplasm, the poles of the spindle
thus being truncate. Each mantle fibre, however, points directly
toward the centrosome.

The distinction between nuclear substance and cytoplasm may he
readily seen up to the late anaphase of the first division.

The second division follows very closely on the first. The centro-
somes separate and move apart upon the cell membrane, forming a
spindle similar to that of the first spermatocyte.

The first maturation mitosis results in a longitudinal or equation
division of the chromosomes, while the second is the reduction division.
Evidences of this are seen in the sequence of cleavages in the pro-
phase, in the attachment of the mantle fibres during the metaphase
of the first mitosis, in the shape of the daughter chromosomes during
the anaphase and telophase of the first division, and in the shape of the
dyads and their position in the equatorial plate of the last division.

Laboratory of Histology and Embryology,
Western Reserve University,
Cleveland, Ohio, May 21, 1906.

Bibliography.

Blackman, M. W.

: 01. The S[)eniiatogenesis of the Myrinpods. I. Notes on the Spermato-
cytes and Spermatids of Scolopendra. Kansas Univ. Quart., Ser. A.,
Vol. 10, No. 2, pp. 61-76, pi. 5-7.
Blackman, M. "W.

:03. The Spermatof^enesis of the Myriapods. 11. On the Chromatin in
the Spermatocytes of Scolopendra heros. Biol. Bull., Vol. 5, pp. 187-
217, 22 fi<,'.
Blackman, M. W.

:05. The Spermatogenesis of the Myriapods. III. The Spermatogenesis
of Scolopendra heros. Bull. Mus. Comp. Zool. Harvard Col., Vol. 48,
No. 1, pp. 1-138, 9 pi. and 9 fig.
Blackman, M. "W.

: 05^ The Spermatogenesis of the Myriapods. IV. On the Karyosphere
and Nucleolus in the Spermatocytes of Scolopendra suhspini]ies. Proc.
Amer. Acad. Arts and Sci., Vol. 41, No. 13, pp. 331-344, 1 pi.

BLACKMAN. — SPEIIMATOGENESIS OF THE MYIUAPOUS. 517

Bouin, P.

:00. Mitoses spermatogenctiques chez Lithobius forficatus, L. Etude sur
les variations du processus initosique. XIII*. Coiigres luteruat. de
Med., Paris, Section d'Histol. et d'Embryol., pp. 4G-5I.

Bouin, P.

: 01. Sur le fuseau, le rosidu fusorial et le corpnscule intermediaire dans les
cellules seniinales de Lithubius forticatus. C. 11. Assoc. Anat., Sess. 3,
pp. 225-233, G tig.
Bouin, P.

: 03. Centrosome et Centriole. C. R. Soc. Biol., Paris, Tom. 55, No. 17,
pp. 647-649.
Bouin, P.

: 03*. Sur I'existence d'une double spermatogenfese et de deux sortes de
spermatozoids chez Scolopendra morsitans. Arch. zool. exper., Ser. 4,
Tom. 1, pp. 3-6.
Bouin, P.

: 04. Recberches sur la figure achromatique de la cytodierese et sur le cen-
trosome. Arch. zool. exper., Ser. 4, Tom. 2, Notes et Revue, pp. Ixxiii-
Ixxxviii, 6 fig.

Bouin, P., et Bouin, M.

'99. Sur la presence et revolution des formations ergastoplasmiques dans
les cellules seminales de Lithobius forficatus. Bibliogr. Anat., Naucy,
Tom. 7, pp. 141-150.
Bouin, P., et Bouin, M.

:02. Reduction cbromatique chez les Myriapodes. C. R. Assoc. Anat.,
Sess. 4, pp. 74-78.

Bouin, P., et Collin, R.

: 01. Contribution a I'etude de la division cellulaires chez les Myriapodes.
Mitoses spermatogenctiques chez le Geophilus linearis (Koch). Anat.
Anz., Bd. 20, pp. 97-115, 11 fig.

Carnoy, J. B.

'85. La Cytodierese chez les arthropodes. La Cellule, Tom. 1, pp. 189-

440, 8 pi.

Foot, K., and Strobell, E. C.

: 05. Prophases and Metaphase of the First Maturation Spindle of Allolo-
bophora foetida. Amer. Jour. Anat., Vol. 4, No. 2, pp. 199-243,
9 pi.

Gr6goire, V.

: 05. Les resultats acquis sur les cinfeses de maturation dans les deux
rogues. Mem. I, Revue critique de la litterature. La Cellule, Tom. 22,
pp. 221-376, 147 fig.
McClung, C. E.

: 00. The Spermatocyte Divisions of the Acrididae. Kansas Univ. Quart.,
Ser. A, Vol. 9, No. 1, pp. 73-100, pi. 15-17.

518 PROCEEDINGS OF THE AMERICAN ACADEMY.

Mc Clung, C. E.

:02. Tlie Spermatocyte Divisions of the Locustidae. Kansas Univ. Sci.
Bull., Vol. 1, ijp." 185-231, pi. 7-10.
McClung, C. E.

: 05. The Chromosome Complex of Orthopteran Spermatocytes. Biol.
Bull., Vol. 9, No. 5, pp. 304-340, 21 fig.
Medes, Grace.

: 05. The Spermatogenesis of Scutigera forceps. Biol. Bull., Vol. 9, No. 3,
pp. 156-187, pi. 2-6.
Meves, P., und von Korfif, K.

:01. Zur Kenntnis der Zelltheilung bei Myriapoden. Arch. f. mikr.
Anat., Bd. 57, pp. 481-486, Taf. 21, 6 fig.
Montgomery, T. H., Jr.

: 00. The Spermatogenesis of Peripatus balfouri up to the Formation of
the Spermatid. Zool. Jahrb., Abth. f. Morph., Bd. 14, pp. 277-368,
Taf. 19-25.
Montgomery, T. H. , Jr.

:01. A Study of the Germ Cells of Metazoa. Trans. Amer. Phil. Soc,
Phila., Vol. 20, jtp. 154-23G, pi. 4-8.
Montgomery, T. H., Jr.

: 05. The Spermatogenesis of Syrbula and Lycosa, with General Considera-
tions upon Chromosome Reduction and the Heterochromosomes. Proc.
Acad. Nat. Sci. Phila., Vol. 57, pp. 162-205, pis. 9, 10.
Paulmier, P. C.

'99. The Spermatogenesis of Anasa tristis. Jour. Morph., Vol. 15, Suppl.,
pp. 223-272, pi. 13, 14.
Prenant, A.

'87. Observations cytologiques sur les elements seminaux de la Scolo-
pendre et de la Lithobie. La Cellule, Tom. 3, pp. 415-436, 2 pi.
Prenant, A.

'92. L'origine du fuseau achromatique nucleaire dans les cellules semin-
ales de la Scolopendre. C. R. Soc. Biol., Paris, Tom. 44 (Ser. 9,
Tom. 4), pp. 249-253.
Sutton, W. S.

: 02. Oil the Morphology of the Chromosome Group in Brachystola magna.
Biol. Bull., Vol. 4, pp. 24-39, 11 fig.

Explanation of Plates.

All drawings were made witii the aid of a camera lucida. A Lcitz -j^.T-inch homo-
geneous immersion objective and No. 4 ocular were used, producing, at the pro-
jection distance employed, a magnification of 1230 diameters. All figures were
reduced ^ in reproduction, making a final magnification of 820 diameters.

PLATE 1.

Figure 1. Spermatogonium of Lithobius mordax in the " resting stage." Each
nucleus possesses two karyospheres, which contain all of the chromatin of the cell.

Figure 2. Prophase of spermatogonium of L. mordax. The chromosomes
have arisen from the karyosphere, and are distributed throughout the nucleus in
the form of fine granular threads. The nucleoli and the accessory chromosome
are all that remain of the karyosphere.

Figure 3. Early spermatocyte of L, mordax. The chromosomes have under-
gone pseudo-reduction. The massing of the chromosomes about the accessory
chromosome to form the karyosphere has already begun.

Figure 4. Lithobius sp. ? at about the same stage as is shown in Figure 3.
Here the nucleoli serve as the basis of the karyosphere. Two nucleoli are seen,
one of which is already acquiring chromatin.

Figures 5, 6, 7. First spermatocytes of L, mordax in the early growth period,
showing massing of the chromosomes to form the karyosphere. The outlines of
many of the chromosomes can still be seen.

Figure 8. Later stage of growing Jirst spermatocyte of L. mordax. The
karyosphere has increased in size, is becoming more regular in outline, and
stains less deeply, owing to the acquisition of nucleolar material. The nucleus
also contains diffuse deposits of achromatic material. The outlines of some of
the chromosomes are still to be seen.

Figure 9. Nucleus of Jirst spermatocyte of L. mordax in the vesicle stage,
showing the presence of both chromatin and nucleolar substance.

Figure 10. The vesicle stage in L. mordax, showing characteristic shape of
cell, dense structures of the cytoplasm, and characteristic appearance of the
nucleus. The karyosphere appears entirely black, and is surrounded by a mantle
of non-chromatic material.

Figures 11, 12. Nuclei ot Jirst spermatocytes of L. multidentatus in the vesicle
stage. Tlie amount of chroTnatin is here less than in L. mordax. It is spread
out over the surface of the nucleolus, forming a karyosphere similar to that of
Scolopendra subspinipes. The achromatic deposits are confined to several dense
masses.

Figure 13. Very early prophase of first spermatocyte of L. multidentatus. The
chromatin in the karyosphere is becoming more loosely arranged. The deposits
of achromatic material have broken up into a number of smaller masses.

Figures 14-17. Nuclei of spermatocytes of Lithobius sp. ? in the vesicle stage.
Two or more karyospheres are usually present, each containing considerable
nucleolar material.

Figure 18. Nucleus oi first spermatocyte of Lithohius sp. ? in early prophase.
Most of the chromosomes have left the karyosphere, and are in the form of
granular segments.

TiGUKES 19a, 19b, 19", 20, 21. Later prophase of first spermatocyte in Lithohius
sp.l, showing various stages in formation of the tetrads and in disintegration of
the nucleoli. Figures 19*, 19'', and 19= represent successive sections of the
nucleus of one cell.

Figure 22. Mid-prophase of first spermatocyte in Lithohius sp. ? The tetrads
have contracted to form denser bodies of chromatin.

Figure 23. Nucleus of first spermatocyte, showing early stages in the forma-
tion of the tetrads in L. mordax. Some of the chromosomes have undergone
longitudinal splitting, resulting in double rows of globules. Others are already
taking on the form of characteristic tetrads. One chromosome is just arising
from the karyosphere. Tlie nucleolar material is already becoming vacuolated.

Figures 24, 25. Mid-propliases of the first spermatocyte of L. mordax. The
centrosomes are moving apart along the inner face of the cell membrane. The fu-
sion of the globules forming each chromatid of the tetrad has begun. In two
chromosomes in Figure 25 this fusion is complete, there being only four parts to
the tetrad. The nucleolus is much reduced in size.

PLATE 2.

Figures 26, 27. Late prophase of first spermatocyte of L. midtidentatus.
Many of the tetrads have already become homogeneous. However, the dividing
planes are still very evident. The linin fibres are being converted into definite
threads.

Figure 28. Late propliase of L. mordax. The nuclear membrane has dis-
appeared, and tlie linin fibres are becoming oriented to form the mantle fibres
of the spindle.

Figures 29, 30. Division figures of the first spermatocyte of L. mordax, showing
the complete independence of nuclear spindle and astral systems. The fibres of
the spindle, however, converge toward the centrosomes. The distinction between
nuclear sap and cytoplasm is very distinct. The chromosomes are arranged in
an equatorial plate. At the point of attachment of the mantle fibres to the chromo-
some, a small, darkly stained body is seen.

Figure 31. Cliromosomes seen in a single equatorial plate of L. mordax
sliowing the variety of shapes and sizes and the manner of attachment of the
mantle fibres.

Figure 32. Mid-anapliase of fiirst spermatocyte of L. mordax. The daughter
chromosomes are of a distinct dumb-bell shape, the constriction representing the
plane of the second division.

Figures 33, 34. Later stages in division of first spermatocyte of L. 7nordax.
Where chromosomes can still be distinguished, their form is unchanged.

Figure 35. Late telophase of first, or early prophase of second, spermatocyte
of L. mordax. Cliromosomes still dumb-bell shaped. Centrosomes are moving
apart along inner surface of cell membranes.

Figure 36. Metaphase of second spermatocyte of L. mordax. Achromatic
structures similar to corresponding stage of first division. The dumb-bell
shaped chromosomes are arranged with the constriction in the plane of the
equatorial plate.

Figure 37. Telophase of second spermatocyte of L. multidentatus.

Blackman ,- Spermatocytes of Lithobius

Plate i.

Proc Amer Acad Arts and Sciences Vol XLll.

Blackman- Spermatocytes OF Lithobius

PlATE 2

Proc Amer Acad, Arts and Sciences. Vol. XLII.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 20. — Makch, 1907.

CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD

UNIVERSITY.

New Series. — No. XXXIII.

REVISION OF THE GENUS SPILANTHES.

By Albekt Hanford Moore.

COXTRTBUTIONS FROM THE GRAY HERBARIUM OF HARVARD

UNIVERSITY.

New Series. - No. XXXIII.

REVISION OF THE GENUS SPILANTHES.
By Albebt Haxford Moobe.

Presented by B. L. Robinson, October 10, 190G. Received November 10, 1906.

Introduction.

When this revision was undertaken, the genus Spilanthes was found
to be in a very confused condition, and the work was greatly hampered
by lack of abundant and authentic material ; a lack, however, which it
was in a large measure possible to overcome through the great generosity
of numerous botanists in different parts of the world. But for the pur-
pose of further study and for the more intelligent determination of
ranges a great deal of material of the genus should be collected. The
genus has been so little understood that it seemed more than usually
desirable to base information regarding the ranges merely on actual
specimens or reproductions examined rather than on published ac-
counts. For habitat the labels give almost no data, and except in a
few cases there were not specimens enough to form satisfactory con-
clusions as to the dates of flowering and fruiting, so that no mention
of these subjects has been made. It is hoped, however, that such
attention in the field will be accorded this interesting genus that the
knowledge of all these matters may be supplied.

The species have proved to be almost entirely lacking in constant
technical characters, so that it has seemed artificial to maintain many
of the earlier ones in an independent rank. The genus thus con-
tains several complex groups of interrelated types, the study of a con-
siderable amount of material of which shows them to intergrade very
strongly with each other. It is certainly very undesirable to attempt
to distinguish species upon the basis of mere leaf and habital varia-
tions. Therefore in treating the genus it has been the plan to make
the species stand for something definite, at least, so that they may
represent an aggregation of variations more like each other than like

622 PKOCEEDINGS OF THE AMERICAN ACADEMY.

any other variations, and to relegate to the rank of varieties and
forms, under species into which they converge, plants of less numerous
or significant characters.

The nomenclature of the revision is strictly in accordance with the
Vienna Rules.

To Dr. R. Chodat, of Geneva, Drs. C. F. Millspaugh and J. M. Green-
man, of the Field Museum of Natural History, Dr. J. N. Rose, of the
United States National Museum, Capt. J. D. Smith, of Baltimore, and
Prof William Trelease, of the Missouri Botanical Garden and Henry
Shaw School of Botany, I desire to express my gratitude for their kind
loan of valuable specimens. To Dr. N. L. Britton, of the New York
Botanical Garden, and his associates, I owe special thanks for the
courteous reception afforded me, and for permission to consult the fine
herbaria of the Garden and of Columbia University. For photographs
of type specimens important to the work, I am indebted to B. Daydon
Jackson, Esq., Secretary of the Linnean Society, and Prof. F. 0.
Bower, of the University of Glasgow. Dr. Casimir de Candolle, of
Geneva, Prof. A. Engler, of the Royal Botanical Garden in Berlin,
Lieut. -Col. David Prain, F.L.S., F.R.S.E., of the Royal Gardens at
Kew, and Dr. A. Zahlbruckner, of the Imperial Museum of Natural
History in Vienna, were so kind as to contribute excellent tracings,
drawings, and photographs. Dr. Otto Kuntze, of San Remo, Italy,
and Alfred J. Swart, Esq., of the Victorian Department of Agri-
culture, Victoria, Australia, kindly contributed valuable authentic
specimens. I wish to thank Dr. H. Pittier, of the Bureau of Plant
Industry, Department of Agriculture, and Dr. H. H. Rusby, of the
New York College of Pharmacy, for useful information in regard to
geographical matters. I wish to express my special thanks also to
the librarian of the Gray Herbarium, Miss Mary A. Day, for her
untiring efforts in connection with the bibliographical work and for
much other valuable assistance and advice. To Miss I. W. Anderson,
of the Gray Herbarium, I am greatly indebted for assistance in pre-
paring the material for study. Prof. M. L. Fernald and Mr. H. H.
Bartlett, of the Gray Herbarium, have also given many useful sug-
gestions, for which I wish to thank them very much. But above all
I am indebted to the Curator, Dr. B. L. Robinson, for his constant
advice and assistance throughout the work.

Revisio Generis Spilantiiis.

Spilanthes Jacq. Plantae inter erectas et prostratas variantes her-
baceae 6-15 dm. altae. Folia opposita inter sessilia et valde petiolata
variantia. Capitula discoidea vel radiata (sed radiis saepius parvis)

MOORE. — REVISION OF THE GENUS SPILANTHES. 523

inter subglobosa et oblonga variantia (regulariter conica) plerumque
parva peduiiculata. Involucri squamae G-mult. obtusae vel acutae
ovatae vel lanceolatae. Radii lutei aut albi vel nulli. Aebaenia valde
compres.sa raro vix triangulata nunquam columnaria inaequaliter biar-
istata aut inaristata (aristis rigidis aut saepius ciliis persimilibus)
margine ciliata vel glabra raro superficiebus ciliata nonnunquam mar-
gine crassa sed plerumque (praeterquam in no. 1) inconstanter. —
(Derivatio: o-ttiAo?, macula + -di/^r/s, florens). — Enum. Syst. PI. Carib. 8
(1762).

Genera praecedenti magis affinia (secundum Engl, et Prantl Natiir-
lichen Pfl. iv, 5, 229, in clave) sunt Lipochaeta Z>C., Flourensia
DC, Salmea DC, Salmeopsis Benth. Lipochaeta distinguitur
achaeniis non valde compressis, plerumque multis capitulis mini-
mis subglobosis et saepe foliis non simplicibus ; Flourensia capitu-
lis valde aromaticis et achaeniis longis pilis tectis, foliis alternis ;
Salmea Salmeopsisque inflorescentia cymose disposita distinguun-
tur ; praeter Lipochaetam, omnes habitu suffruticoso.
Aspectus Isocarphae R. Br. generi nostro simillima est at illius
achaenia columnaria et 4-6-angulata sunt.

Generis nostri locus systematicus. — Tribus Heliantheae {DC)
Cass, ixicl. Spikoitheae Csiss. Diet. Sc. Nat. v, 419 (1825). Sub-
tribus Verbesininae 0. Hoffm. Verbesineae (Cass.) Lindl.
Synonymia. — Praelinnaeana :

Ceratocephalus Burm. Thes. Zeyl. 58 (1737); Ktze. Rev. Gen.

PI. i, 326 (1891).
ABC Darin Rumpf. Amb. Kruidb. (Herb. Amb. Burm. tr. la-

tina) vi, 145, t. 65 (1750).
Postlinnaeana :

^Spilrmtkas L. Syst. Nat. ed. XII, ii, 533 (1767).
Ftjrethrum Med. Act. Acad, vel Hist, et Comment. . . . Theod.

-Palat. (Phys.) iii, 237 (1775), in parte.
Spilantus R. W. Darw. Fam. PI. ed. II, ii, 544 (1787).
Athronia Neck. Elem. Bot. i, 32 (1790).
Ceruckis Gaertn. ex L. - Schreb. Gen. PI. ed. VIII, ii, 543

(1791).
Acmella Rich, in Pers. Syn. PI. ii, 472 (1807).
Synonymum exclusum. — Mendezia DC. Prod, v, 532 (1836) =

Zinnia L.
Distributio. — Per regiones tropicas hemisphaeriorum amborum
et in Hemisphaerio Occidentali in regionibus Zonae Tem-
pera tae calidioribus a Missouri ad Louisianam, Texas, Floridam
in Civitatibus Foederatis Americae.

524 PROCEEDINGS OF THE AMERICAN ACADEMY.

Generis Clavis.

A. Capitula discoidea (praeterquam in no. 12). B Sectio I. Salivaria,

B. Folia sessilia (nonnunquam in no. 7 minute subpetiolata) inter linearia et
lanceolata variantia integra. C.
C. Achaenia margine crassa (margine ca. 1 mm. lata) uniaristata.

1. S. chamaecaula.
C. Achaenia margine non crassa inaequaliter biaristata. D.
D. Antherae apice nigrae ; folia non spatulata ; plantae Mundi Xovi. E.
E. Eolia conspicue venata ; radices fasciculatae. . . . 2. S. nervosa.
E. Folia tribus nervis plus minusve prominentibus ; radices non fascicu-
latae. F.
F. Plantae inter glabras et leviter pubescentes variantes. 3. S, urens.

F. Plantae laneae 4. -S. urens f. Janea.

F. Plantae hispidulae 5. <S. urens var. hispidiila.

D. Antherae apice nigrae ; folia non spatulata ; plantae australienses.

6. S. anactina,
D. Antherae apice non nigrae ; folia linearispatulata ; plantae Mundi

Novi 7. <S. pusilla.

B. Folia petiolata obovata valde et saepe obtuse sinuatodentata.

8. S. insipida.
B. Folia petiolata ovata subintegra vel crenata serrata vel incisa. G.

G. Discus ovoideocoluranaris tempore maturitatis 1-1.7 cm. latus ; capitula

saepe apice fusco 9. 5. oleracea.

G. Discus multo gracilior ; capitula colore uniformi. H.
H Plantae Mundi Novi. I.

I. Achaenia inaristata glabra ; involucri bracteae numerosae.

10. S. leucantha.
I. Achaenia aristata vel ciliata ; involucri bracteae 4-8. K.

K. Folia saepius integra vel subintegra sed nonnunquam serrata (raro
conspicue) ; non multis capitibus brevipedunculatis.

Capitula sine radiis 11. S. ocymifolia.

Capitula cum radiis 12. 6". ocymifoUa f. radii/era.

K. Folia serrata (plerumque conspicue) ; regularitcr multis capitibus

brevipedunculatis 18. ^. oci/mijblia var. acutiserrata.

H. Plantae Mundi Antiqui. L.
L. Pedunculi 3-10 cm. longi (plerique ca. G cm.). M.

M. Achaenia glabra calvaque 14. /S. calva.

M. Achaenia aristata vel ciliata. N.

N. Folia nervis longitudinalibus non conspicuis.

Folia inter subintegra et serrata variantia non incisa.
Folia plerumque 3-6 cm. longa non albescentia.

15. S. Acmella.
Folia plerumque maiora fere semper infra albescentia.

IG. 5. Acmella var. albescent if oUa.

Folia incisa 17. 5. Acmtlla var. lanceolata.

N. Folia nervis longitudinalibus prominentibus. 18. 5. costata.

L. Pedunculi 14-17.2 cm. longi (plerique ca. 15 cm.). 19. 5. callimorpha.

MOORE. — REVISION OF THE GENUS SPILANTIIES. 525

A. Capitula radiata. 0 Sectio IT. Acmella.

0. Kadii capituli maturi involucrum vix superantes pleruiiique perminuti et

paulo ovati. P Subsoctio I. Parvoradiatae.

P. Involucri squamae inter late ovatas et suborbiculares variantes obtusae
vel acutae nunquani acuininatae.
Folia 1.1-2.5 cm. longa subintcgra vel Integra.

Palcae apice violaceae 20.-5. iodiscaea.

Paleae apice non violaceae 21. .S. iodiscaea f. leucaena.

Folia 2.8-5 cm. longa plerumque serrata (raro subintcgra).

22. 1?. tdirjitwfsa.
P. Involucri squamae inter ovatas et ovatolanceolatas variantes acumin-
atae. Q.
Q. Plantae Mundi Novi. R.
K. Capitula acute obtuseve conica. S.
S. Folia nee integra nee subintcgra. T.
T. Folia non mucronuloide attenuata. U.
U. Plantae non conspicue tomentulosae aut hispidulosae. V.
V. Folia lanceolata ; capitula pleraque G mm. longa 4 mm.

lata 23. 5. Lwidii.

V. Folia inter anguste ovata et ovatolanceolata variantia ;
capitula pleraque 8 mm. longa 6 mm. lata vel minora.
Plantae erectae vel ascendentes ; folia inter late ovata et
ovatolanceolata variantia.
Folia plerumque integra aut crenata ; achaenia fere sem-
per margine valde ciliata. (Vide supra sub no. 12.)

12. S. ocijmifolia f. radii/era.

Folia saepius dentata (nonnunquara irregulariter incisa) ;

achaenia plerumque omnino non vel leviter margine

ciliata 2i. S. ciliata.

Plantae prostratae ; folia ovata vel subrotunda quam ia
praecedentibus minora (ca. 2-3 cm. longa).

25. S. ciliata var. diffusa.
U. Plantae dense tomentulosae vel hispidulosae, maxime surculi

recentiores 26. 6'. subhirsuta.

T. Folia abrupte mucronuloide attenuata. ... 27. S. caespitosa.
S. Folia integra aut vix undulata.

Plantae et maxime involucri squamae canescentes.

28. S. poliolepidica.
Plantae non conspicue canescentes.

Folia linearilauceolata, nervo medio prominente, non ciliolata.

29. S. disciformis.
Folia ovatolanceolata, nervis aequaliter prominentibus tribus,

margine ciliolata 30. <S'. limonica.

R. Capitula truncata fere planoconvexa 31. *?. alpestris.

Q. Plantae Mundi Antiqui.

Capitula subglobosa vel conica 5-8 mm. longa 5-9 mm. lata.

32. aS. mauritiana.
Capitula oblonga 1.5 cm. longa 5-6 mm. lata.

33. S. mauritiana f. madagascariensis.
0. Radii capituli involucrum conspicue superantes plerumque magni atque

liguliformes. X Subsectio II. Matjnoradiatae.

X. Folia angustissima 2-2.5 cm. longa 1.5-2 mm. lata. . 34. 6^. stenophylla.

526 PROCEEDINGS OF THE AMERICAN ACADEMY,

X. Folia non angustissima vel si angiistissima multo breviora. Y.

Y. Cajntula 3.5-5.5 mm. longa (pleraque 4.7 mm.). . . . 35. S.Jilipes.
Y. Capitula non minus quamO mm. longa ac plerumque multo magis. Z.
Z. Radii longitudine conspicue minus quam dimidia jiars disci.

3(5. S. iabadicensis.
Z. Radii longitudine non minus quani dimidia pars disci, a.

a. Caules colore rubro tincti crassiores 37. S.phaneractis.

a. Caules non colore rubro tincti tenuiores. b.

b. Plantae non radicibus rigidis aut crassissimis et nunquam radi-
cum fasciculis reptantes; radii saepius non latissimi. c.
c. Folia Integra undulata vel distanter sinuatodentata ovatolan-
ceolata.

Folia longiacuminata 38. .S". macrophi/lla.

Folia non longiacuminata 39. 5'. papposa.

c. Folia inter integra et valde serrata variantia ; si Integra turn
late linearia vel lanceolata. d.
d. Plantae Insularum Malayensium.

Folia inter ovata et lanceolata variantia 3-7 cm. longa .7-2.5

cm. lata 40. .S. (jru)idljiora.

Folia linearia 2.5-5.5 cm. longa .5-.8 cm. lata.
Ligulae involucrum multo superantes.

41. S. grand ijlora var. brnchijglossa,
Ligulae involucrum vix aut omuino non superantes.

42. ;S. grandiflora var. calva.
d. Plantae Abyssiniae vel Mundi Novi. e.

e. Folia minutissima 7-15 mm. longa (pleraque 8 mm.).

43. S. pammicroph i/Ua.
e. Folia non minus quam 2 cm. longa et plerumque multo
magis (nri. 40, 47, 48, 49 nonnunquam minus quam 2 cm.
longa sunt sed dentata non subintegra ut in no. 43). f.
f . Radii colore albo puro ; plantae abyssinicae.

44. S. abijssinica.
f. Radii luteo saltem tincti ; plantae ]Mundi Novi. g.

g. Folia inter elliptica et ovatolanceolata variantia. h.
h. Folia saepius crenata quam serrata ; plantae Mexico,
et Americae Centralis Australisque. i.
i. Plantae erectae aut deorsum repentcs sursum as-
cendentes; folia maiora (0-18 cm. longa).

45. 6\ americana.
i. Plantae magis prostratac plerumque omnino ; folia

minora (1.5-4.5 era. longa). k.
k. Discus parvus gracilisquc (saepius .5 cm. longus
1 mm. crassus). 40. iS. umericuita \Ar. ramosa.
k. Discus maior. 1.

1. Plantae glabrae aut vix pubescentes.

47. »S. americana var. parvula.
1. Plantae pubescentes.

48. S. americana var. parvula f. parvifolia.
1. Plantae dense lanuginosae.

49. S. americana var. parvula f. lanitecta,
h. Folia saepius serrata quam crenata ; plantar Ameri-
cae Borealis. ... 60. »S. americana var. repens.

MOORE. — REA^ISION OF THE GENUS SPILANTIIES. 527

g. Folia linearia. m.

m. Folia non margine ciliata. n.
n. I'lantae non longissimis internodiis; folia Integra
vel distantcT subscrrata.

51. S. amcrirann var. stolonifera.
n. riantae longissimis internodiis ; folia distanter
serrata.
52. .S'. americana var. stolonifera f. lonijiinternodiata.
m. Folia margine ciliata. o.

o. Folia obtusa ; cilia minima non distantia.

53. <S'. aiiKrirund var. stolonifera t. ciliatifolia.
0. Folia acuta ; cilia conspicua distantia.

54. S. hlepharicarpa.
b. Plantae radicibus rigidis aut crassissimis, saepius radicum fasci-
culis reptantes ; radii saepius latissimi. p.
p. Capitula non latissima ; receptftcula non crassissima. q.
q. Folia caullna inconspicue vel omnino non serrata.

Folia caulina 5-9 cm. longa lanceolata; folia basalia saepe
foliis caulinis valde dissimilia semperque in rosulae forma

disposita 55. S. deciimhens.

Folia caulina 2.5-6 cm. longa foliis basalibus non valde dis-
similia.
Folia duarum formarum fieri inclinata (aliqua late lan-
ceolata aliqua anguste lanceolata vel linearia) vel
omnia late lanceolata.

56. S. decumbens var. macropoda.
Folia unius formae (linearia).

57. S. decumbens var. Jeptophylla.
q. Foli!^ caulina conspicue sed non omnia valde serrata. r.

r. Folia dense hispidulosa sed margines non valde ciliatae ;

folia basalia caulinis non similia 58. S. grisea.

r. Folia sparse vel omnino non hispidulosa sed margines
valde ciliatae ; folia basalia caulinis similia. s.
s. Folia lanceolata ; pedunculi longissimi (1-2.8 dm.), t.
t. Folia 3-7 cm. longa 1.7-2 cm. lata.

59. S. grisea var. intermedia,
t. Folia 7-10 cm. longa 1-2.2 cm. lata.

00. S. grisea var. setosa.
t. Folia 4.8-8 cm. longa, .5-8 cm. lata ; serrationes quam
in praecedentibus prominentiores.

61. S. grisea var. Chodatana.
s. Folia ovata ; pedunculi 5.5-7 cm. longi.

62. S. grisea var. micrn.

p. Capitula latissima (1.1-2 cm.); receptacula crassissima (ple-

rumque 3.5 mm.) 63. 6'. eurycarena.

Sectio I. Salivaria DC. capitulis discoideis. — Prod, v, 624 (1836).
Distributio. — In India, Indiis Orientalibus Nederlandicis, Insulis
Philippinis, Australia, Mexico, America Centrali Australique, Indiis
Occidentalibus.

528 PROCEEDINGS OF THE AMERICAN ACADEMY.

1. S. chamaecaula A. H. Moore spec, nov. glabra vel subglabra ;
longissimis caulibus diffusis prostratis ; foliis late linearibus supra
infraque paulum scabris plerumque ca. 3 cm. longis .4-6 cm. latis
margine non revolutis, nervo medio ; capitulis globosis vel subglobosis ;
receptaculis ca. 4-5 mm. latis ca. 7 mm. longis ; achaeniis crassis
uniaristatis. Haec species a ceteris achaeniis uniaristatis margine con-
stanter crassissimis longe abest.

Distributio. — In Borneo boreali.

Specimen typicum. — Borneo: F. W. Burbidge, ann. 1877-1878 (in

Herb. Gray.).

2. S. NERVOSA Chod. 1.8-3 dm. alta sparse ciliata ; caulibus erectis
vel ascendentibus ; foliis lanceolatis vel ovatolanceolatis obtusis sine
squamulis valde pinninervatis, petiolis valde pilosis vel subtomentosis ;
capitulis semiglobosis, involucri squamis oblongis ;. radicibus fasciculatis.
— In Bull. Herb. Boiss. ser. 2, iii, 724 (1903).

Distributio. — In regione cursus superioris fluminis Apa in Paraguay.
Specimen examinatum. — Paraguay: E. Hassler, 8274, in regione
cursus superioris fluminis Apa.

3. S. UREXS Jacq. 2-5 dm. alta glabra aut plus minusve ciliata ;
caulibus decumbentibus ; foliis anguste vel late lanceolatis raro lineari-
bus acutis acuminatisve 3 5-5.5 cm. longis, supra squamulis albis
scabris infra glabris, margine saepe perminute revolutis saepius tri-
nerviis ; pedunculis plerumque 1.4-2 dm. longis ; capitulis globosis
vel subglobosis, involucri squamis ovatis ; receptaculis ca. 2 mm. crassis
et 5 mm. longis ; achaeniis tenuissimis plerumque aristis duabus ciliis
persimilibus et inaequalibus. — Enum. Syst. PI. Carib. 28 (1762), et
Select. Stirp. Am. Hist. 214, t. 126, f 1 (1763); DC. Prod, v, 625
(1836) : SantoUna pyrethri sapore humi fusa, Plum. Cat. PL Am. 10
(1703).

Synonymia. —

Cotula SpilantJms L. Mant. PI. 116 (1767).

Bidens angustifoUa Lam. Encycl. Meth. (Bot.) i, 416 (1783).

Bidens angustifoUa Lam. var. minor Poir. Lam.-Poir. Illustr.
Genres iii, 244, t. 668, f. 2 (1823).

SpUanthes repens Spreng. ex DC. Prod, v, 625 (1836).

Ceratocephalus urens (Jacq.) Ktze. Bcv. Gen. PI. i, 326 (1801).
Distributio. — In Jamaica, Martinica, litoribus colombianis borealibus,
Brasilia, et adventive (f) Altatae in Mexico.

Specimina examinata. — Mexico : Sinaloa : T. S. Brandegee, Al-
tatae, Sept. 2, 1904. Jamaica: A. S. Hitchcock, Luceae, Ian. 3,
1891, Port Antonio, Dec. 26, 1890, Port Morant, Dec. 22, 1890; /.
Moulton- Barrett, Jackson Tower, lun. 15, 1902 ; C. F. Jli/lspaugfi,

MOORE. — REVISION OF THE GENUS SPILANTHES. 529

2028, Bowden. Martinica: L. TIahn, 126, Fort de France, et 726, in
valle St. Pierre; P. Dms, 1733 et 4077, Fort de France. Brasilia:
G. Gardner, 4252. Colombia : Magdalena : H. II. Smith, 553,
Santa Marta.

4. S. URENS Jacq. f. lanea A. H. Moore f. nov. praecedenti omnino
similis sed caules lanei et nonnunqnam folia.

DIstributio. — Lagoa Santa in Brasilia.

Specimen typicum. — Brasilia : Minas Geraes : B. Warming, Lagoa

Santa, Oct. 27, 1863 (in Herb. Hort. Bot. Novebor.).

5. S. URENS Jacq. var. hispidula DC. S. urenti persimilis sed con-
spicue hispidula ; foliis plerumque 2.5 cm. longis ; pedunculis 1.5-2.5
cm, longis. — S. urens Jacq. /?. hispidula DC. Prod, v, 625 (1836).
Synonymia. —

Spilanthes leiocarpaDC. Prod, v, 626 (1836).

Spilanthes Macraei H. et A. in Hook. Jour. Bot. iii, 317 (1841).

Spilanthes Macrali Ktze. Rev. Gen. PL i, 326 (1891).

Ceratocephalus leiocarpus (DC.) Ktze. 1. c.
Distributio. — Per oram peruvianam et chilensem borealem.
Specimina examinata. — Perua : Callao : U. S. So. Pac. Explor.
Exped., Callao. Chile: Tacna : W. Lechler, 1532, prope Aricam.
Concepcion : /. D. Hooker, Concepci6n (photographa).

6. S. anactina F. Muell. glabra erecta vel raro decumbens ; foliis
linearibus aut linearilanceolatis non revolutis ; nervo medio promineute ;
pedunculis 1.1-2 dm. longis; achaeniis inaequaliter biaristatis. —
Fragm. Phyt. Austr. v, 63 (1865-1866).

Synonymia. —

Ceratocephalus anactinus (F. Muell.) Ktze. Rev. Gen. PL i, 326
(1891).
Distributio. — In Australia.

Specimina examinata. — Australia: Queensland: In insula Sweer in
sinu Carpentariae (sine collectoris nomine). Wallia Nova Australis :
S. Mossman, 509, ad flumen Brisbane (planta per chartam delineata).

7. S. PUSILLA H. et A. 1.5-12 cm. alta ; caulibus decumbentibus ;
foliis angustissime lanceolatis ad linearispatulata vergentibus ca. 2 cm.
longis 3-5 mm. latis aliquando leviter petiolatis ; capitulis globosis vel
subglobosis ca. 5-7 mm. diametro ; receptaculis ca. 5 mm. longis 1 mm.
crassis; alioqui S. urenti Jacq. similis. — In Hook. Jour, Bot, iii, 317
(1841).

Synonymia, —

Spilanthes stolonifera DC. var. pusilla (H. et A.) Bak. in Mart. Fl.
Bras, vi, 3, 235 (Maio 1, 1884).
Distributio. — Buenos Aires in Argentina.

VOL. XLII. — 34

530 PROCEEDINGS OF THE AMERICAN ACADEMY.

Specimen examinatum. — Argentina : Buenos Aires : J. Tweedie,
223, Buenos Aires.

8. S. INSIPIDA Jacq. ad 3 dm. alta ; foliis supra infraque hispiduKs
vel subtomentosis valde aut saepe obtuse sinuatodentatis petiola (quae
ca. 1 cm. longa) decurrentibus ; pedunculis ca. 10-15 cm. longis, textura
crassa vel raro tenui ; capitulis vel globosis subglobosis aut raro conicis
in pedunculo singulo singulis vel plurimis ; achaeniis fere vel omnino
glabris calvisque. — Enum. Syst. PL Carib. 28 (1762), et Select. Stirp.
Am. Hist. 215, t. 126, f. 2 (1763) ; DC. Prod, v, 626 (1836).
Synonymia. —

Bidens insipida (Jacq.) Lam. Encycl. Meth. (Bot.) i, 416 (1783).

Ceratocephalus insipidus (Jacq.) Ktze. Rev. Gen. PI. i, 326 (1891).
Distributio. — In Cuba.

Specimina examinata. — Cuba: C. Wright, 3610; 'IE. Otto, 9-4.
Matanzas : J. W. Bobbins, prope Matanzas, Apr. 1864 ; F. Bugel, 6,
Matanzas ; N. L. Britton, E. G. Britton, J. A. Shafer, 206, in fauci-
bus Sumuri prope Matanzas.

9. S. oleracea L. ad 4 vel 5 dm. alta; foliis deltoideis, basi 1.5-
5.5 cm. lata inter cuneatam et subtruncatam variante, 2.4-7.5 cm.
longis conspicue crenatis vel dentatis, petiolis quam in praecedentibus
plerumque multo longioribus (1-4 cm. longis) ; capitulis plerumque
ovoideocolumnaribus vel oblongis raro subglobosis 1-3 cm. longis 1-1.7
cm. latis, saepe apice fusco ; receptaculis crassissimis ovoideocolumnari-
bus .8-2.3 cm. longis .5-1 cm. latis ; achaeniis plerumque inaequaliter
biaristatis conspicue ciliatis (ciliis saepe basi tuberculoidea) et margine
crassa. — Spilanthus oleracea L. Syst. Nat. ed. XII, ii, 534 (1767);
Kegel Gartenfl. ii, t. 42 (1853), Spilanthes oleracea Jacq. secundum
DC, et /3. i.fusca (Hort. Par.) DC. Prod, v, 624, nris. 30 et 30/3, cf.
Jacq. Hort. Bot. Vind. ii, 63, t. 135 (1772).

Synonymia. —

Bidens acmelloides Berg in Kongl. Vetensk. Acad. Handl. xxix, 2,

245 (Iul.-Sept. 1768).
Pyrethrum Spilanthus Med. in Act. Acad, vel Hist, et Comment.

. . . Theod.-Palat. (Phys.) iii, 242, t. 18 (1775).
Bidens fervida Lam. Encycl. Meth. (Bot.) i, 415 (1783); Lam.-

Poir. Illustr. Genres iii, 244, t. 668, f. 1 (1823).
Bidens fusca Lam. 1. c.
Spilanthus fusca Hort. Par. ex Lam. 1. c.
Buphthalmum strigosum Spreng. N. Entd. ii, 140 (1821).
Spila?ithes brasiliensis Spreng. L. -Spreng. Syst. Veg. iii, 444 (1826).
Acmella brasiliensis Spreng. 1. c.
Buphthalmum heterophjllum Willd. ex L.-Spreng. 1. c. 592.

MOORE, — REVISION OF THE GENUS SPILANTHES. 531

Spilanthes oleraceus ya,T. Bl. Bijdr. Fl. Nederl. Ind. xiv, 912 (1826).

Spilanthes oleracea L. yS. l.fusca (Hort. Par.) DC. Prod, v, 624
(1836).

Bidens oleracea (L.) Cav. ex Steud. Norn. Bot. ed. II, i, 203 (1840).

Spilanthes Acmella (L.) Murr. var. oleracea (L.) Zoll. Syst. Verz.
Ind. Arch. 123 (1854).

Bidens fixa Hook. f. Fl. Brit. Ind. iii, 307 (1882). Forsan etiam
Spilanthes oleracea L. /?. rufa Ott. ex Ind. Sem, Hort. Berol.,
an. 1858, collect. 10 (1858), nom. nud.
Distributio. — In India, Antillibus Minoribus, Brasilia orientali.
Specimina examinata. — Ex Mus. Bot. Berol. ; J. E. Teijsmann, " ex
horto bogoriensi Javae misit, 1869." Guadeloupe: P. Buss, 2498.
Martinica: F. Duss, 1449, Trois Fonts in St. Pierre. Brasilia: W.
J. Burcludl, 4734. MiNAS Geraes : S. E. Henschen, ser. I, 269, Caldas.
Bio BE Janeiro: C. Gaudichaud-Beaupre, 681, Rio de Janeiro. India:
Behar in Bengalia : H. v. Schlagintweit-Sakimlilnski, sub catal. no.
12959, in alveo sicco fluminis Gandak prope Patnam. Konkan in
Bombay : J. D. Hooker, ex " Herb. Ind. Or. Hook. fil. & Thomson "
Bombay. Specimina culta: Ex Hort. Bot. Univ. Harv., an. 1874;
ex Herb. I. A. Lapham, e seminibus e Cuba missis cult. ; J. Gay,
Parisiis, Sept. 1835. C. J. Maximowicz, in itinere secundo, Yoko-
hamae, in Japonia, an. 1862 ; G. Engelmann, Berkeley in California in
Civitatibus Foederatis Americae, Sept. 6, 1880.

10. S. LEUCANTHA HBK. foliis ovatolanceolatis acute vel obtuse
dentatis 4.5-7.5 cm. longis 1.8-3 cm. latis, apice subacuminato, basi
inter subcuneatam et subcordatam variante, petiolis iuferiorum brevi-
oribus superior urn saepius nullis; pedunculis 1.7-9 cm. longis; capitulis
inter globosa et ovatoconica variantibus .7-1.5 cm. diametro, bracteis
numerosis ; achaeniis glabris calvisque ; sequenti valde affinis. — Nov.
Gen. et Sp. PI. iv, 210, t. 370 (1820); DC. Prod, v, 625 (1836).
Syuonymia. —

Isocarpha Kimtkii Cass, in Diet. Sc. Nat. xxiv, 19 (1822).

Ceratocephalus leucantkus (HBK.) Ktze. Rev. Gen. PI. i, 326
(1891).
Distributio. — In Andibus ecuadorensibus.

Specimen examinatum. — Ecuador: BolIvar : ^. ^//(/r^'J Guarandae,
lul. 8, 1876.

11. S. ocymifolia (Lam.) A. H. Moore comb. nov. magnopere
variabilis erecta vel prostrata fere semper pubescens ; foliis regulariter
ovatis inter subintegra et dentata vel crenata variantibus 1.5-9 cm.
longis 5 mm. -5 cm. latis (saepius 5.5-6 cm. longis ca. 3.4 cm. latis)
plerumque nou valde acuminatis, textura tenui vel crassa (plerumque

532 PROCEEDINGS OF THE AMERICAN ACADEMY.

crassiore), colore viridi aut alboviridi ; pedunculis 1.5-10 cm. longis ;
capitulis 2-20 ovoideis (plerisque albis vel albidovirescentibus); achaeniis
plerumque insigniter ciliatis.
Synonymia. —

Bidens ocymifoUa Lam. Encycl. Meth. (Bot.) i, 416 (1783) ;

Lam.-Poir. Illustr. Genres iii, 244, t. 668, f. 3 (1823).
Spilanthus albus L'Hdr. Stirp. Nov. i, 7, t. 4 (1784), Spilanthea
alba Willd. secundum DC. Prod, v, 625 (1836), cf. Willd. iii,
3, 1714 (1804).
Spilanthus SaUvaria Domb. ex L'H^r. 1. c.
Spilanthus radicans Jacq. Collect. Bot. Chem. Hist. Nat. iii, 229

(1789).
Spilanthus eorasperata Jacq. Ic. PI. Bar. iii, 15, t, 584 (1781-
1793) ("Spilanthus radicans mihi dicta fuit in Collectaneis
vol. 3"); DC. Prod, v, 626 (1836).
Spilanthes radicans Schrad. ex DC. 1. c. 624.
Spilanthes exasperata Jacq. /?. cayennensis DC. 1. c. 626.
Spilanthes leucophaea Hort. Berol. % ex Klatt Leopold, xxiii, 5

(1887).
Spilanthes Botterii Wats, in Proc. Am. Acad, xxvi, 141 (1891).
Ceratocephalus Salivaria (Domb.) Ktze. Rev. Gen. PI. i, 326

(1891).
Ceratoceplialus exasparatus (Jacq.) Ktze. 1. c.
Sp)ilanthes Sodiroi Hieron. ex Sod. in Engl. Bot. Jahrb. xxix, 842
(Maio 22, 1900).
Distributio. — Per Mexico et Americam Centralem, in Venezuela, Co-
lombia, Ecuadore, Perua. In Mexico haec species perabundans et con-
stantior est.

Specimina examinata. — Mexico : Friedr. Mueller, 267 et 274.
SiNALOA : T. S. Brandegee, Cafradiae prope Culiacan, Oct. 20, 1904;
E. Palmer, 1565, Lodiego. Jalisco : C. G. Fringle, 2946 et 4341,
l^rope Guadalajaram. Colima : K Palmer, 1192, Colimae. Michoa-
CAN : C. G. Pringle, 4340, Monte Le6n. Morelos : C. G. Pringle,
11572 et C. C. Beam, Ian. 3, 1899, Cuernavacae. Oaxaca : C. Conzatti
et V. Gonzalez, 647, Oaxacae. Vera Cruz : E. Bourgeau, 3098, M.
Botteri, 825, Friedr. Mueller, 4072, Orizabae. Guatemala: Zacapa :
G. C. Beam, 239, Gualan. Amatitlan : H. v. T'urcMeim, 8705, Ama-
titL4n. Santa Bosa : H. T. Heyde et E. Lux, 3812, prope Bio de Las
Cafias. Salvador: San Salvador : L. V. Fg/<7.>?w, 8851, San Salvador.
Costa Rica : Guanacaste : A. Tonduz, 13628, Nicoyae. Alajuela :
A. Al/aro, 5807 B, Alajuelae. Venezuela : Miorida : A. Fendler, 691
et 69lB, prope Tovar. Caracas : /. li. Johnston, 102, ad flumen

MOORE. — REVISION OF THE GENUS SPILANTHES. 533

Asuncidn in insula Margarita ; . . . Birschel, Caracas. Panama :

B. Seemann. Colombia : Magdalena : H. H. Smith, 591, prope
Mamatocam prope Santa Marta. BoLfvAR : J. B. Boussingault,
Cartagenae, an. 1833 (planta per chartam delineata). Brasilia : Rio
DE Janeiro: R. Spruce, Rio de Janeiro, an. 1864. Ecuador: A.
Sodiro, 39/1 (specimen per cliartam delineatum). Guayas : T. Hartweg,
867, Guayaquil. Perua : Herb. Hook. ; Plantae Schottianae. Lima :
U. S. So. Pac. Explor. Exped., infra Obrajillo. Cuzco : ? J. Gay, Oct.
1839-Feb. 1840. Specimen cultum : M. S. Behb, Fountaindale in
Illinois in Civitatibus Foederatis Americae.

12. S. OCYMIFOLIA (Lam.) A. H. Moore f. radiifera A. H. Moore f.
nov. praecedenti omnino similis sed radiifera.

Distributio. — In Panama, Colombia, ora Americae Australis occidentali
ab Ecuadore ad Chile, et in ora Brasiliae orientali.
Specimen typicum. — Colombia: Magdalen a : H. H. Smith, 513,
Santa ]\Iarta (in Herb. Hort. Bot. Novebor.) (specimina cum eodem
lecta in Herbb. Gray., Mus. Hort. Bot. Mo., Mus. Hist. Nat. Field).
Specimina alia examinata. — Panama: B. Seemann ; A. Fendler,
166, Chagres. Surinam: W. H. De Vriese. Colombia: BoLfvAii :
E. Andre, Armadae, Maio 22, 1876. Brasilia: Rio de Janeiro:

C. Gaudichaud-Beaupre, 682, et E. Warming, Maio 16, 1863, Rio de
Janeiro. Ecuador : Manabi : //. F. A. v. Eggers, 15646, Hacienda
del Recreo. Bolivia : 31. Bang, 2024. Chile : J. Gay. Specimen
cultum : Hort. Bot. Univ. Harv., an. 1874.

13. S. OCYMIFOLIA (Lam.) A. H. Moore var. acutiserrata K. H. Moore
var. nov. foliis valde acuminatis et subinaequaliter serratis ; capitulis
ovoideis aut saepius subglobosis fere semper numerosissimis (25-100).
Distributio. — In Mexico et per Costa Rica.

Specimen typicum. — Costa Rica : Cartago : J. J. Cooper, 5807,
Cartago (in Herb. J. D. Sm.) (specimen cum eodem lectum in Herb.
A. H. Moore).

Specimina alia examinata. — Mexico : Tepic : E. Palmer, Ian. 5-
Feb. 6, 1892. Costa Rica: San Jos^ : A. Tonduz, 1429, circum San
Jos^, 8493, San Francisco de Guadalupe.

14. S. CALVA DC. decumbens vel repens, nodis saepius radicans,
pubescens vel subtomentosa ; foliis 1.5-3.5 cm. longis plerumque 1 cm.
latis inter subintegra et dentata vel crenata variantibus brevipetiolatis ;
pedunculis 2.5-9 cm. longis ; capitulis ovoideis vel subglobosis .5-1.3 cm.
diametro ; achaeniis glabris calvisque. — DC. ex Wight Contr. Bot. Ind.
19 (1834) ; DC. Prod, v, 625 (1836).

Synonymia. —

Spilanthes Acmella Bl. Bijdr. Fl. Nederl. Ind. (1826), non (L.) Mutt.

534 PROCEEDINGS OF THE AMERICAN ACADEMY.

Spilanthes rugosa Bl. ex DC. Prod, v, 625 (1836).
Spilanthes Acmella Wall, ex Steud. Nom. Bot. ed. II, ii, 622
(1841), non (L.) Murr. ; nomen ex Wall. Cat. 3185/295 (Dec.
1, 1828).
Spilanthes rugosa Bl. var. truncata Miq. Fl. Ind. Bat. ii, 81

(1856-1859).
Spilanthes Acmella (L.) Murr. var. calva (DC.) Clarke ex Hook. f.

Fl. Brit. Ind. iii, 307 (1882).
Spilanthes Pseudo- Acmella Wall, ex Hook. f. 1. c. ; nomen ex Wall.

Cat. 3185/295 (Dec. 1, 1828),
Cotula conica Wall, ex Hook. f. 1. c. ; nomen ex Wall. 1. c.
Distributio. — In India australi, Ceylonia, et 1 Java.
Specimina examinata. — India: 11. Wight, 1456. Orissa in Ben-
GALiA : Edidit R. F. Hohenacker, 1017, et (r. S. Perrottet, 27, in collibus
Nilgiri. Madras: "Herb. Ind. Or. Hook. fil. & Thomson," Madras.
Ceylonia: G. H. K. Thwaites, 684. Java?: F. W. Jimghukn,
307.

15. S. Acmella (L.) Murr. erecta ascendens decumbensve plerum-
que non nodis radicans subpubescens vel pubescens vel subhispida
nonnunquam glabra; foliis 1.5-5 cm. longis .7-3 cm. latis obtusis acu-
tis acuminatisve subintegris aut acute vel obtuse plerumque non valde
serratis brevipetiolatis ; pedunculis 3-10 cm. longis ; achaeniis in-
aequaliter biaristatis plerumque margine ciliatis. — Spilanthus Acmella
(L.) Murr. L. - Murr. Syst. Veg. ed. XIII, 610 (1774).
Synonymia. —

Verbesina Acmella L. Sp. PI. ed. I, ii, 901 (1753), et Mat. Med. 142
(1749); DC. Prod, v, 623 (1836); Wight Ic. PI. Ind. Or. iii,
1109 (1843-1850); Trim. Hand Bk. Fl. Ceyl. iii, 40 (1895):
Chrysanthemum bidens zeylanicum Acmella dictum, Bre3Ti. f.
Dissert. Bot.-Med. (1700); Senecio ind. orient, ocymi majoris
folio profunde crenato,V\'Qk. A\m. Bot. Mant. 343(1700) t. 315,
f. 2 (1696).
Pyrethrum Acmella (L.) Med. in Act. Acad, vel Hist, et Comment.

. . . Theod. - Palat. (Phys.) iii, 243, t. 19 (1775).
Bidens Acmella (L.) Lam. Encycl. Meth. (Bot.) i, 415 (1783).
Spilantus Aemella R. W. Darw. Fam. PI. ed. II, ii, 544 (1787).
Spilanthus melissaefoUus Salisb. Prod. Stirp. Hort. Chap. Allert.

186 (17.96).
Acmella Linnaei Cass, in Diet. Sc. Nat. xxiv, 330 (1822), A.

Linnaea Cass, secundum Hook. f. Fl. Brit. Ind. iii, 307 (1882).
Spilanthus Amelia Roxb. Fl. Ind. iii, 410 (1832).
Verbisina Amelia Roxb. 1. c.

MOORE. — REVISION OF THE GENUS SPILANTIIES. 535

Sjnlanthes panicuktta Wall, ex DC. Prod, v, 624 (183G); Hook. f.
FI. Brit. Ind. iii, 307 (1882); nomen ex Wall. Cat. 3186/296
(Dec. 1, 1828).
SpUanthus peregrina Blanc. Fl. Filip. ed. I, 622 (1837).
SpibditkiLs lobata Blanc. 1. c.
Spikinthes Acmelh (L.) Murr. var. jycmiculata (Wall.) Clarke ex

Hook. f. Fl. Brit. Ind. iii, 307 (1882).
Ceratoc£2}halus Acmella (L.) Ktze. Rev. Gen. PI. i, 326 (1891).
Distributio. — In India orientali, China, Formosa, Insulis Philippinis,
Australia.

Specimina examinata. — J. E. Teijsmann, " ex borto bogoriensi misit,
1869"; India: R. Wight, 449 et 1607. Bengalia : J. D. Hooker,
Sikkim. Madras : " Herb. Ind. Or. Hook. fil. & Thomson," sine col-
lectoris nomine, Madras. Tenasserim in Burma aut Insulae Anda-
man : /. W. Heifer, 3186. Formosa: li. Oldham, an. 1864; A.
Henry, 812, sine localitate, et 219, in Garampi (qui locus etiam Prom-
unturium Australe appellatus est). Insulae Philippinae : //. Cuming,
2361; Herb. U. S. So. Pac. Explor. Exped., Mauilae. China: Yun-
nan : A. Henry, 12706, Sze-mao.

16. S. Acmella (L.) Murr. var. albescentifolia A. H. Moore var.
nov. foliis quam in praecedente plerumque maioribus (4.5-9.5 cm.
longis 2-3.5 cm. latis) fere semper infra albescentibus.
Distributio. — Incognita sed sine dubio in Mundo Antiquo.
Specimen typicum. — " The Bernhardi Herbarium " nullis notis adiec-
tis (in Herb. Hort. Bot. Mo.).

Specimina alia examinata. — Tria specimina alia " The Bernhardi Her-
barium " nullis notis adiectis.

17. S. Acmella (L.) Murr. var. lanceolata (Lk.) A. H. Moore comb,
nov. erecta vel basi decumbente ; foliis ovatolanceolatis longiacumina-
tis incisis 3-7 cm. longis 1-4.5 cm. latis, petiolis 6.5-10.5 cm. longis
numerosis; capitulis .8-1.3 cm. longis .7-1 cm. latis.

Synonymia. —

Spilanthes Pseudacmella Spreng. L. - Spreng. Syst. Veg. iii, 444
(1826), non (L.) Murr.

Verhesina Pseudacmella Spreng. 1. c, non L.

Acmella lanceolata Lk. var. ex Spreng. 1. c.
Distributio. — Incognita sed sine dubio in Mundo Antiquo.
Specimina examinata. — Ex Mus. Bot. Berol. ; ex Hort. Bot. Petropol.

18. S. costata Benth. ascendens nodis radicans; foliis 4-6.2 cm.
longis 2-3 cm. latis saepius obtusis brevipetiolatis subintegris fere in-
tegris ; pedunculis ca. 9 cm. longis. — Ex Hook, et Benth. Fl. Nigr.
436 (1849).

536 PROCEEDINGS OF THE AMERICAN ACADEMY.

Distributio. — In promunturio Palmas in Africa.

Specimen examinatum. — Liberia : J. B . T. Vogel, in promunturio

Palmas.

19. S. callimorpha A. H. Moore spec. nov. laxa longe decumbens
vel prostrata, longis internodiis, nodis distantibus radicans, subpubes-
cens vel glabra; foliis plerumque 4.7 cm. longis 1 cm. latis longe
acuminatis, apice obtuse mucronuloideo, acute serratis aut saepius
subincisis, petiolis plerisque 1 cm. longis ; pedunculis 14-17 cm. lon-
gis; capitulis ovoid eoconicis .9-1.1 cm. longis 6-8 mm. latis, involucri
squamis 4-8 subacutis subciliatis ; achaeniis inaequaliter biaristatis
subciliatis vel glabris calvisque. Nostra species a ceteris sectionis longe
distat foliis valde serratis, pedunculis internodiisque longissimis.
Distributio. — Sze-mao, China.

Specimen typicum. — China: Yun-nan : A. Henry, 12260 A, Sze-
mao (in Herb. Hort. Bot. Novebor.) (specimen cum eodem lectum in
Herb. Gray.).

Sectio H. AcMELLA (Rich.) DC. capitulis radiatis. — Prod, v, 620
(1836).
Synonymia. —

Genus Acmella Rich, in Pers. Syn. PL ii, 473 (1807).

Genus Athronia Neck. Elem. Bot. i, 32 (1790).

Subgenus Acmellae Bkk. Erpota Ptaf New Fl. N. Am. i, 51
(1836).

Sectio Spilanthis Jacq. Megaglottis F. Muell. Fragm. Phyt. Austr.
V, 63 (1865-1866).
Distributio. — Per Indiam, Indias Orientales Nederlandicas, in In-
sulis Philippinis, in Abyssinia aliisque Africae regionibus, in Civitati-
bus Foederatis Americae a Carolina Boreali ad Floridam, in Texas et
adventive in Nova Caesarea, per Mexico et Americam Centralem, in
Indiis Occidentalibus, et in variis locis per totam oram Americae
Australis.

Subsectio I. Parvoradiatae A. H. Moore subsect. nov. Radii in-
volucrum vix superantes plerumque perminuti et paulo ovati.
Distributio. — In Indiis Occidentalibus, in Mexico, Costa Rica, et per
oram Americae Australis occidentalem a Colombia ad Chile et Argcn-
tinam, et in Africa orientali occidentalique.

20. S- iodiscaea A. H. Moore spec. nov. decumbens vel prostrata
sparse pubeseens ; caulibus tenuioribus. Folia 2.4-3.6 cm, longa
.9-1.2 cm. lata, textura tenui, minute et sparse dentata, petiolis brevis-
simis vel nonnunquam nullis. Pedunculi 1.5-5 cm. longi (plerique ca.

MOORE. — REVISION OF THE GENUS SPILANTHES. 537

2.5 cm.). Capitula ovoidea saepius acuta parva (5.7 mm. longa 4-5

mm. lata), paleis sursum violaceis deorsum luteis ad virides vergenti-

biis, nihil praeter partem violaceam manifestum ; radii minutissimi

albi vel paulo luteotincti, apices ovate expaiisi ; involucri squamae

ovatae, margine ciliata. Receptacula tenuissima acutissimaque ca.

4-5 mm. louga 1 mm. minusve lata breve inaequaliterque biaristata.

Radices tenues fasciculatique.

ITaec species a ceteris longe distat palearum apicibus valde violaceis.

Distributio. — In insula Porto Rico.

Specimen typicum. — Porto Rico : Mayaguez : P. E. E. Sintenis,

718, Cabo Rojo, locis cultis (in Herb. Gray.) (specimen cum eodem

lectum in Herb. Mus. Hist. Nat. Field).

Specimina alia examinata. — Porto Rico : Bayamon : P. E. E. Sln-

tenis, 114'J, "ad vias locis cultis" Palo-seco, Bayam6n. Ponce aut

GuAYAMA : A. A. Heller et uxor, 548, inter Aibonito et Cayey.

21. S. iodiscaea a. H. Moore f. leucaena A. H. Moore f. nov. prae-
cedenti omnino similis sed paleis albidovirescentibus.

Specimen typicum. — Porto Rico : Ponce aut Guayama : A. A.
Heller et u.ror, 550a, inter Aibonito et Cayey. Annotatio in titulo
dicit " unique" (in Herb. Hort. Bot. Novebor.).

22. S. ULiGiNOSA Sw. pervariabilis ascendens laxa vel prostrata;
foliis lauceolatis distanter irregulariterque serratis crenatisve 1.5-4.5
cm. longis .3-1.6 cm. latis, textura inter tenuem et crassam variante;
pedunculis 1.1-5.2 cm. longis, discorum radiorumque colore inter
luteum fere album et aureum variante ; receptaculis tenuibus acu-
tisque. — Spila/ithus uUglnosa Sw. Nov. Gen. PI. seu Prod. Descr.
Veg. Ind. Occ. 110 (1788); DC. Prod, v, 624 (1836).
Synon}Tnia. —

Acmella uUginosa (Sw.) Cass, in Diet. Sc. Nat. xxiv, 331 (1822).
Jaegeria uUginosa (Sw.) Spreng. L. - Spreng. Syst. Veg. iii, 590

(1826).
Spilanthes Acmella (L.) Murr. var. uUginosa (Sw.) Bak. in Mart.

Fl. Bras, vi, 3, 233 (Maio 1, 1884).
Ceratocephalus Acmella (L.) Ktze. var. uUginosa (Sw.) Ktze. Rev.

Gen. PI. i, 326 (1891), var. uliginosus 1. c. iii, 140 (1898).
Ceratocepkalus Acmella (L.) Ktze. var. depauperata Ktze. Rev.
Gen. PI. i, 326 (1891).
Distributio. — In Jamaica, per Antilles Minores a St. Christopher ad
Grenadam, Tobago, Trinidad, et in Panama, et in Sierra Leone in
Africa occidentals

Specimina examinata. — Jamaica: ./. R. Churchill, St. Ann's Bay,
Mart. 19, 1897 ; A. 8. Hitchcock, Luceae, Ian. 3, 1891, et Port Morant,

638 PROCEEDINGS OF THE AMERICAN ACADEMY.

Dec. 20, 1890; N. L. Britton, 830, inter Constant Spring et Annotta
Bay; A. Fredholm, 3059, prope Port Antonio; A. E. Wight, 35,
Port Antonio; W. Faivcett, 8005, Castleton ; C. F. Millspaugh, 1888,
in paeninsula Tichfield. St. Christopher . iV. L. Britton et /. F.
Cowell, 678, in fando Molyneaux. Guadeloupe: P. Duss, 2521,
Basse-terre, 2822, apud castra Jacob, et 893 et 4447, Adonis prope
castra Balata. Dominica: //. F. A. v. Eggers, 74, Goodville : F. E.
Lloyd, 473, Petite Soufriere. Martinica: Herb. Rich, in arvis cam-
pestribus; C. P. Belanger, 179, prope St. Pierre; P. Duss, 930, St.
Pierre; L. Hahn, 1107, in palude du Lamantin. St. Vincent: //. H.
et G. W. Smith, 96. Grenada: W. E. Broadway, in fossa ad montem
Parnassum, St. George's, Ian. 16, 1905; H. F. A. v. Eggers, 6063,
Belvidere. Tobago: H. F. A. v. Eggers, 5760, ad flumen Great Dog.
Trinidad: 0. Kuntze, Apr. 1874. Panama: J. F. Cowell, 392, inter
Ahorca Lagarto et Culebram. Sierra Leone: W. H. et A. H. Brown,
32a, Freetown.

23. S. LuNDii DC. erecta ; foliis lanceolatis obtuse vel plerumque
acute et saepius aequaliter serratis acuminatis brevipetiolatis, petiolis
non ciliatis ; capitulis saepius in planta multis (8 vel pluribus) plerisque
6 mm. longis 4 mm. latis, ligulis minimis. Plantae precedenti aspectu
non dissimiles sed involucri squamis lanceolatis non late ovatis. —
Prod. V, 622 (1836).

Synonymia. —

Spilanthes Sahmanni DC. Prod, v, 623 (1836).
Distributio. — In Brasilia.

Specimina examinata. — Brasilia: L. Riedel ; W.J.Burchell, 7956-2.
Bahia : K. F. P. V. Martins, 438, Bahiae ; /. Blanchet, circa Bahiam, an.
1831. Bio DE Janeiro : G. Gardner, ser. I, 70, prope Rio de Janeiro.

24. S. ciLiATA HBK. pervariabilis erecta vel ascendens ; foliis lan-
ceolatis vel plerumque ovatolanceolatis crenatis vel serratis (saepe in-
aequaliter) acutis vel breviacuminatis, petiolis plus minusve brevibus
nonnunquam fimbriatis vel ciliatis; capitulis .7-1.9 cm. longis 6-
9 mm. latis, ligulis quam in praecedente plerumque paulo maioribus.
Plantae aspectu S. uliginosae Sw. dissimiles. — Nov. Gen. et Sp. PI. iv,
208 (1820); DC. Prod, v, 621 (1836).

Synonymia. —

Spilanthes fimhriata HBK. Nov. Gen. et Sp. PI. iv, 208 (1820) ;

DC. Prod. V, 621 (1836).
Sinlanthes debilis HBK. 1. c ; DC. 1. c. 624.
Spilanthes tenella HBK. 1. c. ; DC. 1. c.

Acmella ciliata (HBK.) Cass, in Diet. Sc. Nat. xxiv, 331 (1822).
Acmella fimhriata (HBK.) Cass. 1. c.

MOORE. — REVISION OF THE GENUS SPILANTIIES. 639

Acmella debilis (HBK.) Cass. 1. c.

Acmella tenella (HBK.) Cass. 1. c.

Acmella brachi/glossa Cass. 1. c. 1, 258 (1827).

Spilanthes grandls DC. Prod, v, G22 (1836).

Spilanthes Foejypigii DC. 1. c.

Spilanthes Mariannae DC. 1. c. 623.

Spil<inthes arrayana Gardu. in Hook. Lond. Jour. Bot. vii, 408
(1848).

Spilanthes Mandonii Sch. Bip. in Liunaea xxxiv, 529 (1866).

Ceratocephalus ciliatus (HBK.) Ktze. Rev. Gen. PI. i, 326 (1891),

Ceratocephalus fimbriatus (HBK.) Ktze. 1. c.

Ceratocephalus debilis (HBK.) Ktze. 1. c.

Ceratocephalus tenellus (HBK.) Ktze. 1. c.

Ceratocephalus Foeppigii (DC.) Ktze. 1. c.

Spilanthes Eggersii Hieron. in Engl. Bot. Jahrb. xxviii^ 608 (Ian.
11, 1901).
Distributio. — In Brasilia et Mexico, et per oram Americae Australis
occidentalem a Colombia ad Boliviam.

Specimina examinata. — " The Bernhardi Herbarium," 229. Mexico :
Herb. Humboldt, apud montem Jurullo (planta per chartam delineata).
Brasilia: W. J. Burchell, 1025 et 9236; F. Sellow, 848 et 1078;
Herb. U. S. So. Pac. Explor. Exped., ad basim montium Organ. Goyaz :
G. Gardner, ser. VIII, 3866, Arrayas. Colombia aut Ecuador : F. C.
Lehmann, 7987. Colombia: Cundinamarca : % I. F. Ilolton, Fusa-
gasugae, Dec. 21, 1852. Ecuador: Manabi : H. F. A. v. Eggers,
14931, Hacienda el Recreo (specimen per chartam delineatum).
Perua : Lima : U. S. So. Pac. Explor. Exped., Limae et Obrajillo.
Bolivia : La Paz : G. Mandon, 63, prope Soratam. Yungas : H. H.
llusby, 919.

25. S. CILLA.TA HBK. var. diffusa (Poepp.) A. H. Moore comb. nov.
praecedenti persimilis sed prostrata ; foliis ovatis, basi subcuneata,
margine regulariter acute dentata, ca. 2.3 cm. longis 1.7 cm. latis ;
pedunculis singulis.

Synonymia. —

Spilanthes diffusa Poepp. Nov. Gen. et Sp. PI. iii, 50 (1845).

Ce?'atocephalus diffusus (Poepp.) Ktze. Rev. Gen. PI. i, 326 (1891).
Distributio. — In Andibus ecuadorensibus peruvianisque.
Specimina examinata. — Ecuador : J. P. Couthouy, in Andibus qui-
tensibus, an. 1855. Perua: W. E. Staffm'd, ad flumen Rimac, Aug.
29, 1887.

26. S. SUBHIRSUTA DC. decumbens ; surculis maxime recentioribus
subhirsutis vel dense tomeutulosis aut saltern valde pubescentibus ;

540 PROCEEDINGS OF THE AMERICAN ACADEMY,

foliis ovatis irregulariter sed saepius acute serratis acutis non mucronu-
loide attemiatis brevipetiolatis, petiolis subhirsutis ; capitulis radiis
minimis. — Prod, v, 622 (1836).
Synonymia. —

Ceratocephalus suhhirsutus (DC.) Ktze. Rev. Gen. PI. i, 326 (1891).

Spilanthes popayanensis Hieron. in Engl. Bot. Jahrb. xxviii, 608

(1901).
Distributio. — In Mexico et Colombia.

Specimina examinata. — Mexico : Tamaulipas : J. D. Berland'ier,
Tampico (pars speciminis typici et eiusdem habitus per chartam de-
lineatus). Colombia: Cauca : F. C. Lehmann, 8010, Popayan.

27. S. caespitosa DC. laxa prostrata vel subglabra ; foliis auguste
ovatis parvis, apice conspicue mucronuloide atteuuato ; capitulis radiis
minimis. — Prod, v, 622 (1836).

Synonymia. —

Ceratoceplialus caespitosus (DC.) Ktze. Rev. Gen. PI. i, 326 (1891).
Distributio. — In Minas Geraes in Brasilia.

Specimen examinatum. — Brasilia: Minas Geraes : . . , Vauthler,
308 (pars speciminis typici et habitus photographa).

28. S- poliolepidica A. H. Moore spec, no v. erecta canescens pilo-
sula. Folia lanceolata 3-5 cm. longa .7-1.4 cm. lata brevipetiolata vel
subsessilia, supra obscuriora infra pallidiora canescentia saltern colore,
margine Integra nisi vero minutissime undulata subrevoluta. Capitula
ovoidea 6-8 mm. longa ; radii subaurei ; involucri squamae valde pilo-
sulae ; paleae membranaceae deorsum albae sursum luteae vel sub-
aureae. Achaenia ciliata fere aequaliter biaristata.

Distributio. — Chilamate prope flumen Sarapiqui in Costa Rica.
Specimen typicum. — Costa Rica: Heredia: F.BloUeij, 7420, Chila-
mate prope flumen Sarapiqui (in Herb. Gray.) (specimen cum eodem
lectum in Herb. J. D. Sm.).

29. S. DisciFORMis Rob. procumbens cum ramis ascendentibus (parte
erecta 1.8-2.5 dm. alta), caulibus maxime prostratis lignosis maxime
erectis rubrotiuctis, nodis radicantibus ; radicibus crassis in fasciculis
dispositis ; foliis integris subacutis subsessilibus aut brevipetiolatis,
nervo medio prominente albicante, internodiis non longissimis et foliis
quam internodiis plerumque longioribus. Pedunculi 5-7 cm. longi
(plerumque 5.5 cm.). Capitula elongatoconica ; radii quam capitula
multo breviores minimi. Achaenia parum ciliata iuaristata. — In Proc.
Am. Acad, xxvii, 176 (Nov. 2, 1892).

Distributio. — Prope Guadalajaram in jNIexico.

Specimen examinatum. — Mexico : Jalisco : C. G. Prlngle, 3489,

prope Guadalajaram (specimen typicum).

MOORE. — REVISION OF THE GENUS SPILANTHES. 541

30. S. limonica A. H. Moore spec. nov. laxa sed erecta 3-5 dm.
alta, caulibiis nuiK^uam rubrotiiictis sparse pubescentibus ; foliis ova-
tolanceolatis integris vel subintegris (vix undulatis vel dentatis) obtusis
aut vix acutis tenuibus, margine ciliolata ; pedunculis 8-16 cm. longis
(plerumque 10 cm.) ; capitulis elongatoconicis, radiis quam capitulis
multo brevioribus minimis.

Distributio. — Limones in Santa Clara, Cuba.

Specimen typicum. — Cuba: Santa Clara: C. G. Pringlc, 75,

Limones (in Herb. Gray.) (specimina cum eodem lecta in Herbb. Hort.

Bot. Mo., Hort. Bot. Novebor., Mus. Hist. Nat. Field).

Appellatio. — Ex nomine localitatis in qua specimen typicum lectum est.

31. S. ALPESTRis Griseb. erecta ad 7.3 dm. alta; foliis late lanceo-
latis 1.5-6.6 cm. longis 1.5-2.6 cm. latis acute distanterque serratis,
petiolis nuUis ; pedunculis ca. 11cm. longis; capitulis subhemisphae-
ricis supra planioribus fere planoconvexis. — In Gcitt. Gel. Abb. xix,
185 (1874).

Distributio. — In Argentina.

Specimen examinatum. — Argentina: Tl'CUMAN : P. G. Lorentz et

G. IHeronijmus, 903, Siambon (regione typica) (specimen per cbartam

delineatum).

32. S. mauritiana (Ricb.) DC. erecta aut saepius decumbens pro-
cumbensque nodis saepe radicans puberula ; foliis deltoideis vel ovatis
serratis 2.3-3.2 cm. longis 1.5-2.8 cm. latis; pedunculis 1-1.5 cm.
longis, bracteis late ovatis ; capitulis subglobosis vel conicis 5 mm.
-1.5 cm. longis 5-9 mm. latis, radiis latitudine saepe eis subsectionis
sequentis aequantibus ; involucri squamis angustioribus discos super-
antibus vel aequantibus. — Prod, v, 625 (1836).

Synonymia. —

Acmdla mauritiana Rich, in Pers. Syn. PI. ii, 472 (1807).

Acmella caulirhiza Del. Cent. PI. d'Afr. du Voy. h. Mero^, 45, t. 3,
f. 7 (1826).

Spilanthes caulirhiza (Del.) DC. Prod, v, 623 (1836).

Sjjilantkes africaim DC. 1. c.

Spilanthes caulorrhiza Bentb. Fl. Austr. iii, 541 (1866).

Acmella caulorrhiza (Bentb.) Hook. f. et Jack. Ind. Kew. i, 29
(1895).

Acmella mauritanica Hook. f. et Jack. 1. c.
Distributio. — In Pondoland in Africa, in Madagascare, et in Mauritio.
Specimina examinata. — Africa ? : " The Bernhardi Herbarium," 303.
Pondoland: IF. Tyson, 1057, in cultis, Enshlewzi. Madagascar:
. . . Blackbu)-n, "comm. Admiral W. Bowles," lul. 17, 1863. Mau-
ritius : Sine collectoris nomine (planta per chartam delineata).

542 PROCEEDINGS OF THE AMERICAN ACADEMY.

33. S. MAURiTiANA (Rich.) DC. f. madagascariensis (DC.) A. H.
Moore comb. nov. capitulis maturis oblongis quam in praecedente
magis elongatis 1.5 cm. longis 5-6 mm. latis.

Synonymia. —

Spilantlies caulirldza (Del.) DC. /S. madagascariensis DC. Prod, v,
623 (1836).
Distributio. — In Madagascare.
Specimen examinatum. — Madagascar: M. A. Shufiidt, 105.

Subsectio II. Magnoradiatae A. H. Moore subsect. nov. Ptadii
capituli maturi involucrum conspicue superantes plerumque magni
atque liguliformes.
Synonymia. —

Sectio Spilanthis Jacq. Megaglottis F. Muell. Fragm. Phyt. Austr.
V, 63 (1865-1866).
Distributio. — In Civitatibus Foederatis Americae a Missouri ad Flori-
dam et Texas, per Mexico et Americam Centralem, et in America
Australi a Colombia ad Patagoniam borealem in Argentina, etiam in
Mundo Antique in Java, Insulis Philippinis, Australia, et in Abyssinia
in Africa.

34. S. STENOPHTLLA H. et A. procumbens ; foliis angustissimis 2-2.5
cm. longis 1.5-2 mm. latis densissimis; pedunculis ca. 5.5 cm. longis;
radiis discum aequantibus vel paulo superantibus. — In Hook. Jour,
Bot. iii, 317 (1841).

Distributio. — Apud Buenos Aires in Argentina.

Specimen examinatum. — Argentina : Buenos Aires : J. Tweedie,

861, Buenos Aires.

35. S. filipes Greenm. erecta ; foliis ovatis, basi in petiolum cuneato-
attenuato, conspicue et valde aequaliter crenatoserratis, apice vix acuto
aut vix mucronuloideo, petiolis plerisque ca. 2.5 cm. longis ; pedunculis
gracillimis ; capitulis minimis (3.5-5.5 mm. longis plerisque 4.7 mm.
latis), regulariter multis, radiis conspicuis quam capitulis longioribus ;
achaeniis ciliatis inaequaliter biaristatis. — In Proc. Am. Acad, xxxv,
314 (Mart. 16, 1900).

Distributio. — In civitate Yucatan in Mexico.

Specimina examinata. — Mexico: Yucatan: "Allison V. Armour

Expedition," 43; G. F. Gaumer, 2502, Izamal, 1122, Buena Vista

(specimen t}i)icum), 1257, 1465, 2185, Chichankanab, 3835, in

insula Cozumel ; C. F. Millspaugh, 1494, San Miguel in insula

dicta.

36. S. iabadicensis A. H. Moore spec. nov. erecta saltem 2.8 dm.
alta; foliis lanceolatis distanter sed acute et saepius inaequaliter

MOORE. — REVISION OF THE GENUS SPILANTIIES. 543

serratis, basi acuta, apice valde acute nunquam mucronuloideo,
petiolis brevissimis ; pedunculis non gracillimis ; capitulis .8-1.4 mm.
longis, radiis (^uam capitulis brevioribus ac (|uam in praecedente multo
minus abundantibus ; achaeniis ciliatis inaequaliter biaristatis.
Distributio. — In Java.

Specimen typicum. — Java: J. E.Teijsmann, "ex horto bogoriensi
Javae niisit, 1869." (in Herb. Gray.).

37. S. phaneractis (Greenm.) A. H. Moore comb. nov. prostrata
decumbensve nodis radicantibus, radicibus tenuioribus ; caulibus crassis
rubrotinctis sed nunquam lignosis ; foliis late linearibus aut lineari-
lanceolatis, nervo medio prominente plerumque non albicante, inter-
nodiis plerumque longis quam foliis multo longioribus ; pedunculis
8.2-14 cm. longis (plerumque ca. 11 cm.); capitulis radiis magnis (cf.
no. 29).

Synonymia. —

^pilanthes d'lsciformis Rob. var. plianeractls Greenm. in Proc. Am.
Acad, xxxix, 108 (Sept. 25, 1903).
Distributio. — In civitatibus Jalisco et Michoac^n in Mexico.
Specimina examinata. — Mexico: Jalisco: C G. Pringle, 11312,
apud aquae deiectum Juanacatlan prope Guadalajaram. Michoacan :
C. G. Pringle, 8G37 et 9539, Zamorae.

38. S. MACROPHYLLA Greenm. foliis ovatolanceolatis inter integra
et distanter inaequaliterque dentata vel undulata variantibus, basi
cuneata, apice acuminato, margine ciliolata ; involucri sqnamis valde
pubescentibus ; radiis capitula aequantibus vel superantibus. — In
Proc. Am. Acad, xxxix, 109 (Sept. 25, 1903).

Distributio. — In Honduras et Costa Rica.

Specimina examinata. — Honduras : Santa Barbara : C. Thieme^
5309, San Pedro. Costa Rica : San Jos^ : H. Pittier, 3717, in ripis
fluminis Volcan, 1054G, Alto del Zacatal (specimen typicum) (planta per
chartam delineata). San Marcos : A. Tonduz, 7831, San Marcos.

39. S. PAPPOSA Hemsl. foliis ovatolanceolatis inter integra et paulum
undulata variantibus, basi subcuneata, apice longe acuto sed non acumi-
nato, margine non ciliolata ; involucri squamis pilosulis ; radiis capitula
fere vel omnino aequantibus. — Biol. Centr.-Am. Bot. ii, 193 (Oct.
188r

Distributio. — In Nicaragua.

Specimen examinatum: Nicaragua: Chontales : R.Tate, 1867-1868.

Synonymia. —

Ceratocephalus papposiis (Hemsl.) Ktze. Rev. Gen. PI. i, 326
(1891).

40. S. GRANDiFLORA Turcz. foliis inter ovata et ovatolanceolata

644 PROCEEDINGS OF THE AMERICAN ACADEMY.

variantibus plerumque irregulariter serratis ; radiis involiicrum vix
superantibus. — In Bull. See. Nat. Mosc. xxiv, 1, 185 (1851).
Synonymia. —

CeratocepJialus grandiflora (Turcz.) Ktze. Rev. Gen. PI. i, 326
(1891).
Distributio. — In insula Luzon in Insulis Philippinis et in Queensland
in Australia.

Specimina examinata. — Insulae Philippinae : //. Cuming, 115-1, in
insula Luzon (cum specimine typico lectum). Australia : Queensland:
E. 31. Bowman, Rockhampton.

41. S. grandiflora Turcz. var. brachyglossa Benth. praecedenti
similis sed ligulis involucrum vix superantibus et foliis 2.5-5.5 cm.
longis .5-8 cm. latis. — Fl. Austr. iii, 541 (1866).

Synonymia. —

Spilantlles Acmella F. Muell. Fragm. Phyt. Austr. v, 63 (1865-
1866), non L.
Distributio. — Ad rivum Sturt in Australia Occidentali.
Specimen examinatum. — Australia : Australia Occidentalis :
Ferd. Mueller, ad rivum Sturt (planta per chartam delineata).

42. S. GRANDIFLORA Turcz. var. calva Benth. praecedenti similis sed
ligulis involucrum multo superantibus. — Fl. Austr. iii, 541 (1866).
Synonymia. —

Spilmitkes macroglossa F. Muell. Fragm. Phyt. Austr. v, 63 (1865-
1866).
Distributio. — Apud sinum Moreton in Queensland in Australia.
Specimen examinatum. — Australia: Queensland: Sine collectoris
nomine, apud sinum Moreton.

43. S. pammicrophylla A. H. Moore spec. nov. erecta 15.5-18.5
cm. alta ; caulibus glabris, surculis foliosis brevibus, radicibus fascicu-
latis; foliis minutissimis 7-15 mm. longis integris aut vix et sparse
serratis sparse pubescentibus densis, internodiis inferioribus plerumque
1.5 cm. longis superioribus plerumque .4-1.3 cm. longis (regulariter
ca. 8 cm.), petiolis 2-5 mm. longis; capitulis ovoideis .7-1 cm. longis,
pedunculis 2.5-4.5 cm. longis tenuioribus; achaeniis margine ciliolatis
inaequaliter biaristatis.

Distributio. — In Nicaragua.

Specimen typicum. — Nicaragua : C. Wright, Herb. U. S. No. Pac.
Explor. Exped. (in Herb. Gray.) (specimen cum eodem lectum in
Herb. Mus. Nat. Civ. Foeder. Am.).

44. S. ABYSSiNiCA Sch. Bip. prostrata vel ascendens dense sed minute
pubescens vel subglabra, radicibus fasciculatis ; foliis ovatis 1.5-4.5 cm.
longis .8-3 cm. latis subsessilibus vel petiolatis usque ad 1.5 cm. longis;

MOORE. — REVISION OF THE GENUS SPILANTIIES. 5i5

radifs fere colore albo puro, pedunculis 2-8 cm. longis ; achaeniis mar-

gine pleriimque crassa. — In Thdoph. Leftbvre Voy. en Abyss, iv (Rich.

Tent. Fl. Abyss, i), 415 (1847); nomen ex Hochst. in Flora xxiv, 1, " In-

tcllbl."2r, (IS41).

Distributio. — Prope Adowa in Abyssinia.

Specimen examinatum. — Abyssinia : Tigre : W. S'chimper, 134,

prope Adowa (cum specimine typico lectum).

45. S. AMERICANA (Mut.) Hieron. pervariabilis erecta, radicibus
non fasciculatis ; foliis inter ovata et ovatolanceolata variantibus
saepius crenatis quam serratis nonnunquam subintegris vel paulo
serratis, apice inter obtusum et acutum variante (saepius obtuso), nun-
quam tarn longis quam in no. 50 sed quam in nris. 46, 47, 48, 49
maioribus, petiolis brevibus vel longis. — Ex Sod. in Engl. Bot. Jahrb.
xxix, 42 (Maio 22, 1900).
Synonymia. —

Anthemis americana Mut. ex L. f. Suppl. Syst. Veg. 378 (1781).

Antkemis oppositifolia Lam. Encycl. Meth. (Bot.) i, 576 (1783).

Anthemis occidentaUs Willd. L. - Wilkl. Sp. PL iii, 2185 (1804).

Acmella occidentaUs (Willd.) Pticb. in Pers. Syn. PI. ii, 473(1807).

Spilanthes Miitisii HBK. Nov. Gen. et Sp. PL iv, 209 (1820);
DC. Prod. V, 622 (1836).

Acmella ? Mutisii (HBK.) Cass, in Diet. Sc. Nat. xxiv, 331 (1822).

Spilanthes Beccahunga DC. Prod, v, 622 (1836).

Spilanthes Lehmanniana Klatt in Engl. Bot. Jahrb. viii, 43 (1886).

Spiilanthes oi-izabaensis Sch. Bip. ex Klatt Leopold, xxiii, 5 (1887).

Spilanthes uliginosa var. Sch. Bip. ex Klatt 1. c.

Spilanthes Sartorii Sch. Bip. ex Klatt 1. c.

CeratocepJialus americanus (Mut.) Ktze. Bev. Gen. PL i, 326 (1891).

Ceratocephalus Bec&ihunga (DC.) Ktze. 1. c.
Distributio. — In Cuba, INIexico, America Centrali, Colombia.
Specimina examinata. — Mexico : T. Coulter, 324 ; C. J. W. Schiede,
229 ; comm. C. Schaffner, det. Sch. Bip. San Luis PoTOsf : J. G.
Schafner, 338, "ex convalli San Luis Potosi," et 763, "San Luis
Potosi " ; C. C Pai'rij et E. Palmer, 464, maxime in regione San Luis
Potosi. Jalisco: C. &'. Pr//?^/*^, 1821, Guadalajarae. Regio Foeder-
ALis : C. G. Fringle, 9964, prope Tlalpam ; E. Bourgeau, 154, Chapul-
tepes. MoRELOS : C. G. Fringle, 9546, prope Cuautlam. Vera Cruz :
31. B. Halsted, 32, et C. R. Barnes, C. J. Chamberlain, W. J. G.
Land, 9, prope Jalapam ; J. 31. Greenman, 25, La Laguna prope
Vera Cruz, et 134, prope Cordobam ; E. Bourgeau, 603 et 603 bis,
prope Santa F(^, et 1630, in valle Cordobae ; ^4. Gray, "Journey to
Mexico and California, Feb., May, 1885," Cordobae; C. Sartor ius, Mi-

VOL. XLII. 35

546 PROCEEDINGS OF THE AMERICAN ACADEMY.

rador prope Huatucam ; H. E. Beaton, 73, Orizabae. 0 ax AC A : E. W.
Nelson, 1032, prope La Parada ; L. C. Smith, 131, Ranchade Calderas ;
J. N. Rose, J. H. Fainter, J. S. Rose, 10U55, prope Tomellin ; C, Con-
zatti et V. Gonzalez, 1241, Oaxacae. Chiapas : A. Ghieshreght, 557.
Guatemala: Alta Vera Paz : //. v. Tdrckheim, 758, Coban, et 124
et J. D. Smith, 1604, prope Coban. Quiche : H. T. HeydeQt E. Lux,
4501, Nebaj. Quezeltenango : F. C. Lehmann, 1596, Quezeltenango.
Costa Rica: San Jose : A. Tonduz, 3030, SanJosd Cuba: Habana:
A. H. Curtiss, 684, et /. W. Robbins, Mart. 1864, prope Habanam ;
J. A. Shafer, 420, Habanae. Colombia: J. Triana, 1391. Cauca : F.
C. Lehmann, 3487, circum Puracd, et 3599, Chapae. Colombia aut
Ecuador: F. C. Lehmann, 6446.

46. S. AMERICANA (Mut.) Hieroii. var. ramosa (Hemsl.) A. H.
Moore comb, no v. prostrata laxa vel procumbens ; foliis 1.5-2.2 cm.
longis ca. 7 mm. latis denticulatis ; capitulis subglobosis (ca. 5 mm.
diametro), discis gracillimis.

Synonymia. —

Spilanthes ramosa Hemsl. Biol. Centr.-Am. ii, 193 (Oct. 1881).

Ceratocephalus ramosus (Hemsl.) Ktze. Rev. Gen. PL i, 326 (1891).
Distributio. — In valle Cordobae in Mexico.

Specimina examinata. — Mexico : Vera Cruz : E. Bourgeau, 2284,
in valle Cordobae ; //. E. Seaton, 445, Cordobae.

47. S. AMERICANA (Mut.) HieroD. var. parvula (Eob.) A. H. Moore
comb. nov. prostrata vel laxa vel procumbens glabra aut vix pubescens ;
foliis ovatis raro ellipticis crenatulis vel serratulis plerumque 1.8 cm.
longis 1 cm. latis minoribus ; capitulis plerumque 7-14 mm. longis.
Synonymia. —

Spilanthes Beccahunga DC. var. parvula Rob. in Proc. Am. Acad,
xxvii, 176 (Nov. 2, 1892).
Distributio. — In Mexico, Guatemala, Costa Rica.
Specimina examinata. — Mexico : Mexico : C. G. Pringle, 3643,
Flor de Maria. Guatemala: Zacatepequez: J. D. Smith, 2125,
Duefias. Santa Rosa : H. T. Heyde et E. Lux, 4209, Naranjo.
Costa Rica: San Jose : A. Tonduz, 449, San Josd.

48. S. AMERICANA (Mut.) Hicron. var. parvula (Rob.) A. H. Moore
f. parvifolia (Bentb.) A. H. Moore comb. nov. praecedenti omuino
similis sed plus minusve conspicue pubescens.

Synonymia. —

Spilanthes parvifolia Benth. ex Oerst. in Videusk. Meddel. Nat.

For. Kjoeb. 100 (1852).
Spilanthes lateraliflora Klatt in Engl. Bot. Jabrb. viii, 43 (1886).
Ceratocephalus jyarvi/olius (Benth.) Ktze. Rev. Gen. PI. i, 326

(1891).

MOORE. — REVISION OF THE GENUS SPILANTHES. 547

Distributio. — In Guatemala et Costa Rica.

Specimina examinata. - — Guatemala : Alta Vera Paz : F. C. Leh-
mann, 1319, circum Coban ; //. v. T'urckheim, 8418, Cobjln. Costa
Rica: San Josk : ^1. Tonditz, 12241, in pascuis Sa^nta Ro.sadu Copey.
r.i. S. AMERICANA (Mut.) Hieron. var. parvula (Hob.) A. H. Moore
f. lanitecta A. H. Moore f. nov. S. americanae {Mat.) Hieron. var.
parvulae {Rob.) A. H. Moore omnino similis sed dense lanuginosa,
maxime caiiles.

Distributio. — San Siguan in Guatemala.

Specimen typicum. — Guatemala : Quiche : H. T. Heyde et E. Lux,
3o81, San Siguan, alt. ca. 1770 m. (in Herb. Gray.) (specimen cum
eodem lectum in Herb. J. D. Sm.).

50. S. AMERICANA (Mut.) Hieron. var. repens (Walt.) A. H. Moore
comb. nov. magnopere variabilis pubescens vel glabra erecta vel laxa
ascendens decumbeus raro prostrata ; foliis plerumque inter elliptica
et lanceolata variantibus saepius serratis quam crenatis (inter subintegra
et valde sed aequaliter serrata variantibus), apice inter obtusum et acu-
minatum variante saepius acuto vel acuminato, 2-12 cm. longis .7-4.5
cm. latis subsessilibus vel petiolis usque ad 4 cm. longis ; pedunculis
3-12 cm. longis ; capitulis plerumque 9-16 mm. longis. Haec varietas
S. americanae {Mut.) Hieron. valde affiuis est.
Synonymia. —

Anthemis repens Walt. Fl. Car. 211 (1788).

Sinlanthes repens (Walt.) Michx. Fl. Bor.-Am, ed. I, ii, 131
(1803) ; DC. Prod, v, 623 (1836).

Acmella repens (Walt.) Rich, in Pers. Syn. PI. ii, 473 (1807).

Acmella occidentalisi Nutt. Gen. N. Am. PI. ii, 171 (1818).

Acmella NuttalUana Raf. New Fl. N. Am. i, 52 (1836).

Spihmthes Nuttallii T. et G. Fl. N. Am. ii, 356 (Apr. 1842).

Ceratocephalus rej^ens (Walt.) Ktze. Rev. Gen. PI. i, 326 (1891).
Distributio. — In civitatibus australibus Civitatum Foederatorum Amer-
icae, ]\Iissouri, Arkansas, Louisiana, Mississippi, Texas, Carolina Aus-
trali, Florida.

Specimina examinata. — Civitates Poederatae Americae : A. Gray,
in Civitatibus Australibus, 1846 ; Mexican Boundary Survey, 587 (Civ.
Foeder. Am. ?). Missouri : G. W. Letterman, Aug. 15, 1875, et C.
Russell, Sept. 1897, Poplarblufif; F. W. Dewart, Poplarbluif, Aug. 14,
1892, et Neeleysville, Oct. 2, 1892 ; H. Eggert, prope Neeleysville,
Aug. 8, 1893, et prope Asheville, Aug. 19, 1892 ; B. F. Bush, 176,
Maiden, et Campbell, Sept. 18, 1893, 178, Keunett, et lunct. Paw Paw,
Sept. 15, 1893, et 82, in comitatu New Madrid ; W. Trelease, 544, Bertig.
Arkansas : F. V. Coville, 99 ; B. F. Bush, 248, Marked Tree ; W. Tre-

548 PROCEEDINGS OF THE AMERICAN ACADEMY.

lease, iu insula Rattlesnake in flumine St. Francis, Aug. 29, 1897 ; G.
W. Letterman, Little Rock, Aug. 29, 1879. Louisiana : M. C. Leaven-
u-orth ; J. Gregg, prope Shreveport, Sept. 14, 1847 ; -C. Z. Moseley, in
parochia West Carroll, lul. 17, 1903 ; /. D. Hmltk, in parochia Concordia,
Sept. 9, 1885; C. B. Ball, 639, prope Alexandrian! ; Baton Rouge,
Sept. 14, 1867, comm. W. R. Dodson, an. 1896 ; K. K. Blackenzie,^!!,
prope lacum Charles; >S'. M. Tracy, 2485, 8586, et "ex Herb. J. F.
Joor," Nov. 1870, New Orleans. Mississippi : J. D. Smith; T. Nut-
tall, comm. E. Durand, an. 1866. Texas: /. Beverchon, 161, " W.
Texas " ; S. 31. Tracy, 7329, Pierce; B. F. Bash, 118, 295, 712, 941,
1287, Columbiae; E. Hall, 348, B. F. Bush, 252, L. F. Ward,
Sept. 12, 1877, F. Lhidheimer, Aug., et Sept. 1842, Houston; J.
Beverchon, Sept. 6, 1903, et 1535, in comitatu Ellis ; J. M. Bigelow, Las
Moros. Carolina Australis : W. Bavenel, ad flumen Santee (regio-
nem typicam), Sept. 1846. Florida : M. C. Leavenivorth, " Florida," et
"E. Florida"; A. S. Hitchcock, in comitatu Columbia, lun.-Iul. 1898;
F. Bugel, prope St. Marks ; 31. C. Beynolcls, St. Augustine, Sept.-Oct.
1875 ; A. H. Curtiss, 6000, prope Chattahoochee, et prope Da}i:onam,
Feb. 1881 ; A. P. Garber, in comitatu Levy, Nov. 1877, et Tampae,
Maio 1876 et Oct. 1877 ; S. 31. Tracy, 7148, Braidentowu (forma ex-
trema) ; J. H. Simpson, Manatee, an. 1889 ; A. W. Chapman, ad
flumen Caloosahatchee.

51. S. AMERICANA (Mut.) Hieron. var. stolonifera (DC.) A. H. Moore
comb. nov. S. americanae {3Iut.) Hieron. var. repenti {Walt.) A. H.
3Ioore valde persimilis sed foliis linearibus integris aut vix denticulatis
(saepius integris) 1.7-5.5 cm. longis .2-1 cm. latis subsessilibus vel
sessilibus (petiolis quam in varietate dicta plerumque brevioribus) ;
pedunculis 4.5-17.5 cm. longis. Per varietatem dictam S. americanae
(3Iut.) Hieron. affinis.
Synonym ia. —

Spilanthes stolonifera DC. Prod, v, 621 (1836).
Distributio. — Li Paraguay et in Civitatibus Foederatis Americae ad-
ventive in Nova Caesarea et probabiliter adventive in Carolina Boreali
Australique et Florida.

Specimina examinata. — Civitates Foederatae Americae : Nova
Caesarea : G. A. Gross, adventive Camden, Jul. 3, 1891. Carolina
BoREALis : G. 3IcCarthy 5, et F. V. Coville, 166, Wilmington. Caro-
lina Australis : G. Mc^larthy, xxxi, "in oriente Carolina Australis."
Florida : A. H. Curtiss, 5882, in parte, Carrabelle. Paraguay : E.
Hassler, 1639, et 3370, San Bernardino ; T. Morong, 89, Asuncit^n ;
K. Fiebrig, 345, in Cordillera de Altos. Specimen cultum: /.
Gay, Parisiis, Sept. 1839.

MOORE. — REVISION OF THE GENUS SPILANTHES. 549

52. S. AMERICANA (Mut.) Hieroii. var. stolonifera (DC.) A. H. Moore
f. longiinternodiata A. H. Moore f. nov. glabra ; internodiis longis
(plerumque 3.5 cm.) ; foHis conspicue acute et distanter dentata (spatia
interdentalia .5-1 cm. longa).

Distributio. — Apud Carrabelle in Florida in Civitatibus Foederatis

Americae.

Specimen typicum. — Civitates Foederatae Americae : Florida :

A. H. Curtiss, 5882, in parte, Carrabelle (in Herb. Uray.) (specimina

cum eodem lecta in Herbb. Hort. Bot. Mo., Mus. Nat. Civ. Feeder Am.,

Hort. Bot. Novebor., Mus. Hist. Nat. Field).

53. S. AMERICANA (Mut.) Hicrou. var. stolonifera (DC.) A. H.
Moore f. ciliatifolia A. H. Moore f. nov. pubescens ; foliis margine
plus minusve cilia ta.

Distributio. — In Argentina.

Specimen t3T)icum. — Argentina: P. G. Lorentz, 76 (in Herb. Gray.).

54. S. blepiiaricarpa DC. foliis linearilanceolatis angustioribus
distanter margine ciliatis, apice acuto ; achaeniis valde ciliatis. — DC.
Prod. V, 621 (1836).

Distributio. — In provincia Rio Grande in Brasilia.

Specimen examinatum. — Brasilia : Rio Grande : Herb. Mus. Imp.

Bras., 1030 (planta per chartam delineata).

55. S. decumbens (Sm.) A. H. Moore comb. nov. sparse pubescens,
maxime in foliis, radicum fasciculis reptans; foliis basalibus saepe quam
caulinis maioribus ovatis crenatis, caulinis ovatis vel lanceolatis vel
linearispatulatis angustioribus et subintegris vel integris, basi saepe
attenuata; capitulis radiis latis, pedunculis 14.5-23 cm. longis.
Synonym ia. —

BudbecJcia decumbens Sm. in Rees Cycl. vel Univ. Diet. Art. Sc.
Litt. ed. anglica, xxx, sect, ii, parte 60, no. 11 (1815).

Budbeckia bellioides Sm. I c. no. 12.

Verbesina bwphthalmo'ides Lk. et Ott. Ic. PI. Select. Hort. Reg.
Bot. Berol. 105, t. 49 (1828).

Spikmtkes arnkoldes DC. Prod, v, 620 (1836).

Spilanthes doronicoides DC. 1. c.

Spilanthes helenioides H. et A. in Hook. Journ. Bot. iii, 317 (1841).

Ceratocephalus decumbens (Sm.) Ktze. Rev. Gen. PI. i, 326 (1891).

Ceratocephalus arnicoides (DC.) Ktze. 1. c.

Ceratocephalus decumbens (Sm.) Ktze. var. doi'onlcoides (DC.) Ktze.
1. c. iii, 140 (1898).
Distributio. — In Brasilia et Uruguay.

Specimina examinata. — Brasilia: F. Selloiv, 1969. Uruguay:
Montevideo : A. hahelle, Montevideo, an. 1838.

650 PROCEEDINGS OF THE AMERICAN ACADEMY.

56. S. DECUMBENS (Sm.) A. H. Moore var. macropoda (DC.) A. H.
Moore comb. nov. foliis quam in praecedente plerumque paulo angusti-
oribus cluarum formarum fieri inclinatis, linearibus (4-8 cm. latis),
lanceolatis (plerumque 1.5 cm. latis), ambabus 4.5-6 cm. longis ; sine
foliis basalibus formae peculiaris ; pedunculis 1 1-17 cm. longis. Plautae
nonnunquam folia latiora solum liabent.

^ J.

Synonyniia. —

Spilantkes macropoda DC. Prod, v, 621 (1836).

Spilanthes arnicoides DC. var. macropoda (DC.) Bak. in Mart. Fl.

Bras, vi, 3, 234 (Maio 1, 1884).
Ceratocephalus decumhens (DC.) Ktze. /3. macropodus (DC.) Ktze.
Rev. Gan. PI. iii, 140 (1898).
Distributio. — In Brasilia.

Specimina examinata. — Brasilia: F. Sellow, 1764 et 3522; A. F.
Begnell, ser. II, 168.

57. S. DECUMBENS (Sm.) A. H. Moore var. leptophylla (DC.) A. H.
Moore comb. nov. repens ; foliis densis anguste linearibus (2-4 mm. latis
1.5-2.5 cm. longis) sessilibus subsessilibusve ; pedunculis 5.4-8.5 cm.
longis. *

Synonymia. —

Spilanthes leptoplnjlla DC. Prod, v, 621 (1836).

Sjnlanthes arnicoides DC. var. Uptophylla (DC.) Bak. in Mart. Fl.
Bras, vi, 3, 234 (Maio 1, 1884).
Distributio. — In Brasilia.
Specimen examinatum. — Brasilia : F. Selloiv, 2796.

58. S. grisea (Chod.) A. H. Moore comb. nov. erecta vel ascendens
valde subpubescens, maxime folia et involucri squamae. Folia inter
lanceolata et ovata variantia obtusa vel snbacuta dentata dense his-
pidulosa. Capitula maxima ; radii maximi (of no. 62).
Synonymia. —

Spilantkes arnicoides DC. f. grisea Chod. in Bull. Herb. Boiss.
ser. 2, i, 417 (1901).

Spilanthes arnicoides DC. var. gj-isea Chod. 1. c. iii, 725 (1903).
Distributio. — In Paraguay.

Specimina examinata. — Paraguay : E. TIassler, 1211, prope Tacuaral,
et 4659, prope flumen Jejui Guazu.

59. S. GRISEA (Chod.) A. H. Moore var. intermedia (Chod.) A. H.
Moore comb. nov. sparse ciliata ; foliis quam in praecedente angusti-
oribus 3-7 cm. longis .7-2 cm. latis.

Synonymia. —

>S'. arnicoides DC. var. intermedia Chod. in Bull. Herb. Boiss. ser.
2, iii, 725 (1903).

MOORE. — REVISION OF THE GENUS SPILANTHES. 551

Distributio. — In regione cursiis superioris fluminis Apa in Paraguay.
Specimen examinatum. — Paraguay: E. Hassle?; 8273, in regione
cursus superioris fluminis Apa.

60. S. GRiSEA (Cbod.) A. H. Moore var. setosa (Cbod.) A. H. Moore
comb. nov. maxime foliis margine conspicue ciliatis ; foliis quam in no.
58 longioribus 7-10 cm. longis 1-2.2 cm. latis.

Synonymia. —

S. arnicoides DC. var. setosa Cbod. in Bull Herb. Boiss. ser. 2, iii,
725 (1903).
Distributio. — Prope flumen Capibary in Paraguay.
Specimen examinatum. — Paraguay : B. Ilassler, 4475, prope flumen
Capibary.

61. S. GRISEA (Cbod.) A. H. Moore var. Chodatana A. H. Moore var.
nov. foliis minute ciliatis distanter serratis quam in no. 59 angustioribus
4.8-8 cm. longis .5-8 cm. latis, serrationibus quam in duabus prae-
cedentibus prominentioribus.

Distributio. — In regione cursus superioris fluminis Apa in Paraguay.
Specimen typicum. — Paraguay: E. Ilassler, 7651, in regione cursus
superioris fluminis Apa (in Herb. Cbod.).

Appellatio. — Ex nomine doctoris R. Cbodat, qui banc novam esse
varietatem iudicavit, derivata. Nota in titulo dicit "var. acced. ad
var. macropoda."

62. S. GRISEA (Cbod.) A. H. Moore var. micra A. H. Moore var.
nov. Caules pendunculique pubescentes. Folia margine ciliata et prae-
terquam nervum medium glabriuscula ad basin subconserta. Pedunculi
5.5-7 cm. longi. Capitula maiora ; radii maiores (cf. no. 58).
Distributio. — Prope Tacuaral in Paraguay.

Specimen tj'picum. — Paraguay : E. Hassler, 925, prope Tacuaral (in
Herb. Hort. Bot. Novebor.).

63. S. eurycarena A. H. Moore spec. nov. erecta vel ascendens,
basi procumbente ; foliis anguste linearibus (2-5 mm. latis 2-3.8 cm.
longis) sessilibus vol brevipedunculatis densioribus ; capitulis latissimis
(1.5-2.5 cm.) 1-1.8 cm. longis, discis crassissimis (plerumque 4 mm.
latis 1 cm. longis), radiis brevibus latisque ca. 7 mm. longis 4-5 mm.
latis ; pedunculis 12-19.5 cm. longis ; acbaeniis margine ciliatis iuae-
qualiter biaristatis.

Distributio. — Rio Negro in Patagonia boreali in Argentina et circum

Buenos Aires.

Specimen typicum. — Argentina : Del Rio Negro : U. S. So. Pac.

Kxplor. Exped., Rio Negro (in Herb. Gray.) (specimen cum eodem lec-

tum in Herb. Hort. Bot. Novebor.).

Specimen alium examinatum. — Argentina : Buenos Aires : " Miss

Parker" Buenos Aires.

652 proceedings of the american academy.

Annotationes.

Spilanthes Jacq. Nomen in forma Spilanthes primo a Jacquin usur-
patum est, sed a Linnaeo in editione duodecima Systemae Naturae sub
forma Spilanthus datum est et postea hac forma Jacquin ipse usus est.
Descriptio autem originalis, quamquam brevis, formam Spilanthes cer-
tam facit. S. urens et S. insipida primo a Jacquin descriptae sunt,
quamobrem S. urens generis species typica est. DeCandoUe duas
sectiones recognovit, viz. Salivariam et Acmellam, quarum posterior
imprimis a Richard pro genere descripta erat.

Sectio I. Salivaria DC.

1. S. chamaecaula a. H. Moore. Haec species inter insignissimas
generis nostri est, non solum habitu prostrato, quem paucae species
aliae saltem in parte habent, sed etiam quod achaenia aristam singu-
1am ferunt. Species generis ceterae aut biaristatae aut inaristatae
sunt. Specimen typicum sub nomine S. anactinae F. Muell. distribu-
tum est, a qua tamen characteribus technicis habituque valde differt.

2. S. nervosa Chod. Haec species foliis magis ovatis et nervis anas-
tomosantibus prominentibus a sequente differt.

3. S. urens Jacq. Huius speciei tabula optima, Jacq. Select. Stirj).
Am. Hist. 1. 126, f. 1, banc plantam esse quam Jacquin indicaverit sine
dubio ostendit. Variationes duae notatae sunt : —

4. S. URENS Jacq. f. lanea A. H. Moore forma lanea et

5. S. URENS Jacq. var. hispidula DC. imprimis natura plus his-
pidulosa sed etiam habitus differentiis paucis, foliorum formis, etc.,
discriminatur.

6. S. ANACTiNA F. Muell. Haec species S. urenti Jacq. antheris apice
nigris foliisque integris similis est, sed foliis plus acuminatis plerum-
que angustioribus nunquam revolutis differt. ludicare licet banc spe-
ciem, cuius natura specimine a F. Mueller autbenticato certa fiat, S.
urenti Jacq., speciei maxime Indiarum Occidentalium, respondere.

7. S. PUSILLA H. et A. Haec species parva gracilisque a praecedenti-
bus omnibus caulibus tenuibus parvisque et foliis angustis linearispa-
tulatis differt. Figura speciminis originalis per cbartam delineatrj
huius speciei characteres noti sunt.

8. S. insipida Jacq. Haec species foliis valde et maxime obtuse sinu-
atodentatis in sectione unica est. E tabula, Jacq. Select. Stirp. Am.
Hist. t. 126, f. 2, quamquam imperfectissima, cum descriptione bona,
/. c. 215, S. insipidae natura certa est.

9. S. oleracea L., saepe sed errore cum auctoritate Jacq. citata,
species a ceteris discis magnis oblongis (vero in genere maximis) foliis-

MOORE. — REVISION OF THE GENUS SPILANTHES. 553

que deltoideis longe abest. Figura prima bona, quod sciam, est Jacq.
Hort. Bot. Vind. ii, 1. 135. Recenter nomen S. oleracea pro synonymo
iS. Acmellae (Z.) Murr. habitum est, potius, crediderim, quia haec
ignoscebatur quam ilia.

10. S. LEUCANTiiA HBK. scquenti valde affinis est et cliaractere
solum technico differt, eo nempe quod multas bracteas habet.

11. S. OCYMIFOLIA (Lam.) A. H. Aloore. Haec species communiter
S. alba Willd. (errore incertae origiiiis pro L'H^r.) appellata est.
^pilanthus Salivaria Domb., re vera a L'Heritier una cum Spilanthe
alba anno 1874 editus, falso dicitur iam antea publicatus esse. Anno
1873 Lamarck in encyclopaedia sua Bidentem ocymifoliam pro sj'no-
nymo S. albae edidit. Apud Lam.-Foir. Illustr. Genres Hi, t. 668
tabula invenitur quae sine dubio >S. albam typicam repraesentat. Inde
Bidens ocymifoUa combinatio prima speciei nostri est. S. ocymifolia
habitu pervariabilis praecedentibus multo latius distributa est.

12. S. OCYMIFOLIA (Lam.) A. H. Moore f. radiifera A. H. Moore
inter sectiones Salivariam et Acmellam radiis intermedia est. Haec
forma, cum specie coextensa, multas eiusdem variationes participat.

13. S. OCYMIFOLIA (Lam.) A. H. Moore var, acutiserrata A. H.
Moore. Haec varietas a specie plerumque capitibus abundantioribus
et foliorum serrationibus prominentioribus magis acutis differt, sensim
in eandem transgreditur.

14. S. CALVA DC. a sequente achaeniis inaristatis habitu tenuiori et
foliis minoribus differt. Nulla species alia inaristata descripta esse
videtur. S. calvae natura e figura per chartam delineata ex Herbario
DeCandolle mihi transmissa certa fit. (Vide etiam infra sub no. 15.)

15. S. AcMELLA (L.) Murr. Huius speciei naturam excogitare diffi-
cillimum erat. Figurae a Linnaeo citatae rudes sunt ac speciei status
ab auctoribus disputatur. Nonnunquam etiam in sectione specierum
radiatarum inclusa est. Specimina multa e regione typica examinata
nullas species radiatas ibi inveniri ostendunt. Quod Hooker in J^lora
of British India de natura S. Acmellae radiorum scripsit contrarium
non probat, nam infra sub titulo "var. Acmella proper,"' Wight Ic.
PI. Ltd. Or. Hi, 1109, tabulam citat quae sine dubio ligulas nullas
exhibet. Quod ad discrimen inter S. Acmellam et S. calvam attinet,
figurae a Linnaeo citatae plantam habitu crasso repraesentare videntur.
(Vide etiam sub no. 14.)

16. S. Acmella (L.) Murr. var. albescentifolia A. H. ^Moore a
praecedente foliis plerumque maioribus infra pallescentibus vel albe-
scentibus differt.

17. S. Acmella (L.) Murr. var. lanceolata (Lk.) A. H. Moore.
Haec varietas a specie foliis magnis valde et irregulariter incisis

654 PROCEEDINGS OF THE AMERICAN ACADEMY.

differt. Descriptio S. Pseudacmellae Spreng., non (L.) Murr., huic
varietati S. Acmellae simillima est. Nomen S. Pseudo-Acmella aut
Pseudacmella ad tarn multas species diversas pertinet ut usurpari non
opporteat. Nomen Acmella lanceolata Lk. var. a Sprengel pro syno-
nymo superioris editum est et nomen primum est quae usurpari
potest.

18. S. cosTATA Benth. a S. Acmella foliis integris vix margine un-
dulatis facile distinguitur.

19. S. CALLiMORPiiA A. H. Mooie species nova pulcherrima chinensis
est. Internodiis longis laxis sed gracilibus et foliis serratis vel subin-
cisis (quam in S. Acmella {L.) Murr. var. lanceolata (ZA.) A. H.
Moore multo angustioribus) a speciebus sectionis ceteris longe abest.

Sectio II. Acmella (Rich.) DC.
Subsectio I. Parvoradiatae A. H. Moore.

20. S. iodiscaea a. H. Moore. Haec species lepidissima capitulis
minimis, radiis minimis et foliis parvis tenuibus minute et sparse den-
ticulatis necnon (praeter formam leucaenam) paleis sursum violaceis,
disco toto visum violaceum praebentibus, a speciebus generis ceteris
valde differt.

21. S. iodiscaea a. H. Moore f. leucaena A. H. Moore. Haec
forma variationem probabiliter raram et certe insignilicantem exhibet.

22. S. ULIGINOSA Sw. habitu pervariabilis est, sed folia et plerumque
capitula crassiora quam in duabus praecedentibus habet. Una cum
eisdem characterem habet qui turmam totam distinguit, viz. quod in-
volucri squamae inter late ovatas et suborbiculares variant. Sicut
paucae species aliae Indiarum Occidentalium et Americae Centralis,
S. uliginosa distributionem miram habet, viz. in Indiis Occideutalibus,
America Centrali, Africa occidentali.

23. S. LuNDii DC. praecedenti simillima est, sed involucri squamae
magis lanceolatae sunt.

24. S. ciLiATA HBK. Haec species inter totum genus maxima varia-
bilis et forsan dificillima est, et in futuro studium diligentissimum
exiget.

25. S. CILIATA HBK. var. diffusa (Poepp.) A. H. Moore a praece-
dente forma prostrata et foliis ovatis, basi paulum subcuneata, differt.

26. S. SUBIIIRSUTA DC. Haec species a praecedente charactere sub-
tomentoso praesertim differt.

27. S. CAESPiTOSA DC. a S. subhirsuta natura leviori, et a S. ciliata
foliis parvis, apice mucronuloideo, differt.

MOORE. — REVISION OF THE GENUS SPILANTIIES. 555

28. S. POLiOLEPiDiCA A. H. Moore a praecedeutibus involucro canes-
cente ligulisque subaureis facile distinguitur.

29. S. DisciFORMis Rob. species procumbens ; caulibus ascendenti-
bus, maxiine caulibus erectis rubrotinctis caulibus prostratis nodis
radicantibus ; foliis iiervo medio prominente albicante.

30. S. LiMONiCA A. H. Moore a praecedente habitu laxo sed erecto
ct foliis latioribus margine ciliolatis diifert.

31. S. ALPESTRis Griseb. Haec species capitula fere planoconvexa
et folia sine ciliolis in margine habet. Eiusdem speciei natura tantum-
modo a specimine, cum descriptione originali congruente, a P. G. Lorentz
et G. Hieronymo in regione typica lecto determinabilis erat.

32. S. MAURiTiANA (Rich.) DC. a praecedente facile distinguitur
foliis non integris vel fere integris. Nee illi speciei nee uUi coniuncte
affinis est.

33. S. MAURITIANA (Rich.) DC. f. madagascariensis (DC.) A. H.
Moore a specie solum capitulis oblongis nee globosis truncatis nee
conicis differt.

Subsectio 11. Magnoradiatae A. H. Moore.

34. S. STENOPHYLLA H. et A. foliis linearibus angustissimis facile
dinoscitur.

35. S. filipes Greenm. capitula parva pedunculos tenuissimos et
foliorum bases cuneatoattenuatas habet, sed radii ad magnitudinem
disci relati longissimi sunt. Species pulcherrima est.

36. S. iabadicensis A. H. Moore. In hac specie capitula bis tantum
longiora quam in praecedente sed radii ad magnitudinem disci relati
breviores quam in generis speciebus ceteris sunt.

37. S. phaneractis (Greenm.) A. H. Moore S. disciformi Roh. habitu
simillima est, sed praesertim radiis multo maioribus Magnoradiatis
magis affinis esse videtur.

38. S. macrophylla Greenm. foliorum basibus longicuneatis apici-
busque acuminatis facile distinguitur,

39. S. PAPPOSA Hemsl. radios maximos habet, sed a sequente
involucri natura pilosulata longe abest.

40. S. grandiflora Turcz. Haec species radios maximos habet, sed
a turmis S. decumbentis {Sm.) A. H. Moore et S. griseae (Chod.)
A. H. Moore radicibus tenuioribus non fasciculatis distinguitur. A
varietatibus sequentibus foliis non linearibus differt. (Vide etiam
sub no. 39.)

41. S. grandiflora Turcz. var, braciiy^glossa Benth. a specie et

556 PROCEEDINGS OF THE AMERICAN ACADEMY.

varietate sequente radiis involucrum vix superantibus differt. (Vide
etiam sub no. 40.)

42. S. GRANDiFLORA Turcz. var. calva Benth. a praecedente radiis
involucrum multo superantibus differt. Character calvus probabiliter
inconstans est, sed e figura singula per chartam delineata hoc factum
indeterminabile erat.

43. S. pammicrophylla A. H. Moore. Haec species unica plantas
tenuissimas et folia in genere toto minima habet.

44. S. ABYSSINICA Sch. Bip. habitu S. americanae (Mut.) Hieron.
var. parvulae {Bob.) A. II. 3Ioore similis est, sed radii albissimi non
lutei sunt.

45. S. AMERICANA (Mut.) Hicrou. sub nomine Ant kemid is americanae
Mut. ex L. f. Supplemento primo descripta et recentius a Humboldt,
Bonpland, et Kunth in honore Mutis S. Mutisii appellata plerumque
sub nomine >S'. Beccabungae DC. nota est. In hac tiirma Anthemis
americana nomen vetustissimum et inde primarium est. Inter specimina
plurima, quae a me examinata sunt, gradationes perspicuae inventae
sunt, quae distinctiones inter species varietatesque huius turmae olim
habitas, quamquam in formis extremis diversissimas, iunaturales et
eapropter reiiciendas esse ostendunt.

46. S. AMERICANA (Mut.) Hierou. var. ramosa (Hemsl.) A. H. Moore
a praecedente receptaculis tenuibus habituque prostrato differt.

47. S. AMERICANA (Mut.) Hieron. var. parvula (Rob.) A. H. Moore.
Haec varietas a specie habitu prostrato et foliis parvis differt. De-
scriptio prima sub nomine S. Beccabungae DC. var. parvulae Rob. edita
est. Nomen mutavi nomenclaturae rationibus solum adductus.

48. S. AMERICANA (Mut.) Hicron. var. parvula (Rob.) A. H. Moore
f. PARViFOLiA (Benth.) A. H. Moore a praecedente modo natura paulum
hispidulosa differt. Hanc esse formam primo a Bentham sub nomine
S. parvifoliae descriptam a specimine originali per chartam delineate
manifestum est. Combinatio autem infelix est, nam folia non minora
sunt quam in varietate, sed nomenclaturae rationibus flicta est.

49. S. AMERICANA (Mut.) Hicrou. var. parvula (Rob.) A. H. Moore
f. LANiTECTA A. H. Moorc. Haec forma lanuginosa est.

50. S. AMERICANA (Mut.) Hieron. var. repens (Walt.) A. H. Moore
a specie fere foliis magis acuminatis, serrationibus magis acutis, differt.
Distributio etiam maxima in parte distincta est. Varietates autem
formaeque praecedentes saltem in parte eadem in regione inventae sunt.
Formae extremae facile dinotae sunt, sed formae aliquae intermediae
sine notitia distributionis difficile distinguuntur.

51. S. AMERICANA (Mut.) Hieron. var. stolonifera (DC.) A. H.
Moore. Inter hanc varietatem et praecedeutem, per quam tantummodo

MOORE. — REVISION OF THE GENUS SPILANTIIES. 557

speciei affinis est, gradationes aequales intersunt, quamquam formae
extremae duarum varietatum atque distributio earuudem omnino dis-
similes sunt. Forma tyjiica folia linearia integra habet.

52. S. AMERICANA (Mut.) Hieron. var. stolonifera (DC.) A. II.
Moore f. longiinternodiata A. H. Moore a varietate internodiis
longis et foliorum serrationibus distantibus prominentibusque differt.

53. S. AMERICANA (Mut.) Hieroii. var. stolonifera (DC.) A. H.
Moore f. ciLiATiFOLiA A. H. Moore a no. 51 foliis ciliatis differt.

54. S. blepiiaricarpa DC. quoque folia linearia aut linearilanceolata
ciliis margine distantibus sed habitum erectum habet. (Vide etiam sub
nris. 51 et 53.)

55. S. DECUMBENS (Sm.) A. H. Moore. Huius speciei et varietatum
sequentinm nomina solum rationibus nomenclaturae mutata sunt. No-
men Rudbeckia decumbens Sm. plerumque pro synonymo >S'. arn'icoidis
DC. ductum est. Haec opinio sine dubio vera est, nam, quamquam
specimen originale inspici non potuit, descriptio originalis lucidissima
est. Haec turma radiis magnis et radicibus fasciculatis distinguitur.
Folia basalia, dummodo extant, in forma rosulae disposita a caulinis
valde differunt.

56. S. DECUMBENS (Sm.) A. H. Moore var. macropoda (DC.) A. H.
Moore. Haec varietas plerumque foliis diversis et basi subterranea
magna distinguitur, sed ambo characteres variabiles inconstantesque
sunt.

57. S. DECUMBENS (Sm.) A. H. Moore var. leptophylla (DC.) A. H.
Moore foliis linearibus a praecedentibus dinoscitur.

58. S. grisea (Chod.) A. H. Moore. Haec species primo a Chodat
pro varietati >S'. arnicoidis DC. habita est ; Chodat etiam iuste existimat
varietates sequentes griseae valde affines esse. Mihi autem haec species
propius accedere ad varietates sequentes quam ad ^. decumbentem (Sm.)
A. H. Moore (*S'. arnicoidem DC.) varietatesque eiusdem videtur. Inde
optimum puto eam speciem typicam facere turmae, affinis sane S. de-
cumbently paulo tamen discrepantis. S. grisea a praecedentibus natura
pubescente facile distinguitur.

59. S. grisea (Chod.) A. H. Moore var. intermedia (Chod.) A. H.
Moore. In hac varietate folia angustiora quam in praecedente et sparse
ciliata sunt.

60. S. grisea (Chod.) A. H. Moore var. setosa (Chod.) A. H. Moore.
Folia longiora quam in specie sed latiora quam in varietate praecedente
margine valde ciliata, sunt.

61. S. grisea (Chod.) A. H. Moore var. Chodatana A. H. Moore.
Haec varietas folia quam in ceteris varietatibus angustiora cum serra-
tionibus distantibus habet.

558 PROCEEDINGS OF THE AMERICAN ACADEMY.

62. S. GRiSEA (Chod.) A. H. Moore var. micra A. H. Moore. In
hac varietate folia foliis specie! similia sunt, sed minora et maxime in
marginibus et nervo medio ciliolata.

63. S. EURYCARENA A. H. Moore capitulis latissimis longipeduncu-
latis a ceteris generis speciebus facile distinguitur.

Nomina Nuda quorum Synonymia Igxota Est.

Spilanthes Arrabidae Hort. ex Teijsm. et Binnend. Cat. PI. Hort. Bot.

Bogor. 105 (1866).
S. deltoidea Wall. Cat. 3185/295 (Deo. 1, 1828).
S. leucocephala Ott. Ind. Sem. Hort. Bot. BeroL, an, 1845, collect. 6

(1845).
S. multiflora Ott. ex Sweet Hort. Brit. ed. H, 306 (1830).
S. mysurensis Wall. Cat. 3185/295 (Dec. 1, 1828).
S. pallida Sweet Hort. Brit. ed. H, 306 (1830).
S. Pseudo-Acmella H. et A. Bot. Capt. Beech. Voy. 150 (1841), non

(L.) Murr. secundum Hook. f. et Jack. Ind. Kew. iv, 963

(1895).
S. rhombifolia Zipp. ex Span. Prod. Fl. Timor, in Linnaea xv, 323

(1841).

Species Formaeque non satis Cognitae Spilanthis vel ad
Spilanthem Attributae.

Sectio I. Salivaria DC.

Spilanthes diffusa Hook./, in Trans. Linn. Soc. xx, 214 (1847).

S. diffusa Hook. f. f minor Hook. f. 1. c.

S. grandifolia Miq. Fl. Ind. Bat. ii, 80 (1856).

S. intermedia {Rick.) DC. Prod, v, 624 (1836).

Acmella intej-media Rich, in Pers. Syn. PI. ii, 472 (1807).

S. javanica Sck. B'ip. ex Miq. Fl. Ind. Bat. (1856-1859) ; nomen Sch.
Bip. in Zoll. Syst. Verz. Ind. Arch. 123 (1854-1855) ; descriptio
"Spilanthes sp. n." Zoll. in Nat. en Geneesk. Arch, ii, 255 (1845)
secundum Miq. 1. c.
Geratocephalus javanicus (Sch. Bip.) Ktze. Rev. Gen. PI. i, 326
(1891).

S. macropoda Turcz. in Bull. Soc. Nat. Mosc. xxiv, 2, 71 (1851).

Ceratocephalus macropodus (Turcz.) Ktze. Rev. Gen. PI. i, 326
(1891).

S. portoricensis /S)?;-?/?//. L. - Spreng. Syst. Veg. iii, 444 (1826); S.
2Mrtoricce7isis^yYeng. secundum DC. Prod, v, 625 (1836), secun-
dum DC. autem probabiliter = S. urens Jacq.

MOORE. — REVISION OF THE GENUS SPILANTIIES. 559

Sectio II. AcMELLA (Rich.) DC.

S. sp. Lor. et Niederl. in Inf. Off. Exped. Rio Negr. (Patag.) Entr. ii,

Bot. 238 (1881).
S. affinis //. et .-1. in Hook. Jour. Bot. iii, 317 (1841).
S. arnicoides DC. f. minor Chod. in Bull. Herb. Boiss. ser. 2, iii, 725

(1903).
S. arnicoides DC. f. nervosa Chod. 1. c.
S. commutata Koch ex Ind. Sem. Hort. Berol. App. 14 (1855).

S. repens Hort. Par. et Berol. ex Koch 1. c.

Ce7-afoce2)halus commitfatus (Koch) Ktze. Rev. Gen. PI. i,326 (1891).
Eclipta filicaulis Schumach. Beskr. Guin. PL ii, 164 (1827).
Feaea linearis A.S^rewg'. L.-Spreng. Syst. Veg. iii, 581 (1826).

Selloa ? linearis (Spreng.) DC. Prod. v. 612 (1836).
Spilanthes longifolia DC. Prod, v, 621 (1836).

S. melampodioides Gardn. in Hook. Lond. Jour. Bot. vii, 407 (1848).
S. sphaerocephala DC. Prod, v, 621 (1836).

Subgenus Exclusum.

Helepta Raf., subgenus Acmellae Rich., New Fl. N. Am. i, 52 (1836) =
Heliopsis Pers. Genus Helepta Raf. Neogen. 3 (1825).

Species Exclusae.

Spilanthes arhorea (Forst. et Forst. f.) Forst. f. in Comm. Soc. Goett.

(Phys.) ix, 67 (1787); DC. Prod, v, 626 (1836), sub. spp.

exclus. = Laxmannia arborea Forst. et Forst. f. Char. Gen. 94,

t. 47 (1776).
Spilanthes atriplicifolia L. Syst. Nat. ed. XII, iii, 236 (1768).

Spilantus atriplifolius R. W. Darw. Fam. PI. ed. II, ii, 544

(1787) = Isocarpha atriplicifolia (Z.) R. Br. Bidens atriplici-
folia L. Amoen. Acad, iv, cent. pi. 2, 329 (lun. 11, 1756).
Spilanthes atriplicifolia Houtt. ex Miq. Fl. Ind. Bat. ii, 37 (1856) =

Dichrocephala latifolia {Pers.) DC.
Spilanthes hicolor (DC.) Benth. et Hook. f. ex Hemsl. Biol. Centr.-

Am. Bot. ii, 192 (lun. 1881), non Gen. PI.
Ceratocephalus hicolor (DC.) Ktze. Rev. Gen. PI. i, 326 (1891) =

Zinnia bicolor {DC.) Hemsl. Mendezia hicolor DC. Prod, v, 533

(1836).
Pyrethrum Bidens Med. in Act. Acad, vel Hist, et Comment. . . .

Theod.-Palat. (Phys.) iii, 241, t. 18 (1775) = Cotula Pyre-

thraria L.

660 PROCEEDINGS OF THE AMERICAN ACADEMY.

Acmella hlfiora (L.) Spreng. L. -Spreng. Syst. Veg. iii, 591 (1826) =

Wedelia biflora (X.) DC. Verhesina bijlora L. Sp. PI. ed. II, ii,

1272 (1763).
Acmella huphthalmoides (Jacq.) Rich, in Pers. Syn. PI. ii, 473 (1807) =

Heliopsis buphthalmoides {Jacq.) Dun. Anthemis huphthal-

moides Jacq. PI. Rar. Hort. Caes. Schoenbr. ii, 13, t. 151

(1797).
Spilantkus cascata Steud. Nom. Bot. ed. I, 108 (1821) = Verbesina

crocata (Cav.) Less.
Spilantkes cernua (L.) Koehn. in Just Bot. Jahresber. xxii, 2, 595

(1897) = Spirantbes cernua (Z.) Rich. Ophrys cernua L. Sp.

PI. 946 (1753).
Spilantkes crocata (Cav.) Sims in Curt. Bot. Mag. xl, 1627, 1. 1627(1814);

DC. Prod. V, 626 (1836), sub spp. exclus. Verbesina crocata

{Cav.) Less. Bidens crocata Cav. Ic. Descr. PI. i, 66, t. 99

(1791).
Spilantkes ecliptoides Gardn. in Hook. Lond. Jour. Bot. vii, 407

(1848).
Ceratocepkalus ecliptodes (Gardn.) Ktze, Rev. Gen. PI. i, 326

(1891) = Jaegeria birta {Lag.) Less.
Acmella flavicauUs Raf. New Fl. N. Am. i, 52 (1836) = Heliopsis

heliantboides {L.) Sweet.
Acmella Garcini (Burm. f.) Spreng. L. -Spreng. Syst. Veg. iii, 591

(1826) = AnvilleaGarcini {Burm. f^ DC. Bupkthalmiim Garcini

Burm. f. Fl. Ind. t. 60, f. 1 (1768), descr. sub nomine Anthemidis

Garcini Burm. f. 1. c. 183.
Acmella globosa (Ort.) Spreng. L. -Spreng. Syst. Veg. iii, 592 (1826) =

Zaluzania globosa {Ort.) Sck. Bip. Antkemis globosa Ort. Nov.

Rar. PI. Hort. Bot. Matrit. Descr. Dec. iv, 47 (1797).
Spilantkes gracilis (Big.) Koehn. in Just Bot. Jahresber. xxii, 2, 595

(1897) = Spiranthes gracilis {Big.) Beck. Neottia gracilis Big.

Fl. Bost. ed. II, 322 (1824).
Spilantkes guatemalensis Ysitk. ex J. D. Sm. Enura. PI. Guat., etc., i, 23

(1889), nom. nud. == Melampodium paludosum IIBK.
Spilantkus kirta (Lag.) Steud. Nom. Bot. ed. II, ii, 622 (1841).

Acmella kirta Lag. Gen. et Sp. Nov. 31 (1816) = Jaegeria hirta

{Lag.) Less.
Spilantkes KarvinsMana DC. Prod, v, 623 (1836).

Ceratocepkalus Karwinskianus (DC.) Ktze. Rev. Gen. PI. i, 326

(1891) = Jaegeria hirta {Lag.) Less.
Acmella lanceolata Raf. New Fl. N. Am. i, 52 (1836) = Heliopsis

scabra Dun.

MOORE. — REVISION OF THE GENUS SPILANTHES. 661

Spilanthes nitidus Llav. in Llav. et Lex. Nov. Veg. Descr. i, 28 (1824) ;

sp. dub. DC. Prod, v, 626 (1836).
Ceratocephalus nitidus (Llav.) Ktze. Rev. Gen. PI. i, 326 (1891)

= Salmea scandens {L.) DC.
Acmella iiudicaulis Raf. New Fl. N. Am. i, 52 (1836) = Heliopsis

helianthoides (//.) Sweet.
Acmella parvifolia Raf. New Fl. N. Am. i, 52 (1836) = Heliopsis

helianthoides (Z.) Sweet.
Spilanthus Pseudo-AcnieUa (L.) Murr. L. -Murr. Syst. Veg. ed. XIII,

610 (1774) ; DC. Prod, v, 625 (1836).
Verbesina Fseudo- Acmella L. Sp. PI. ed. I, ii, 901 (1753); Trim.

Hand Bk. Fl. Ceyl. iii, 40 (1895). Chrysanthemum Maderas-

patanum, latifolium, Scabiosae capituUs pat-vis, Pluk. Aim. Bot.

99, t. 159, f. 4 (1720).
Ceratocephalus Acmella (L.) Ktze. var. Pseudacmella (L.) Ktze.

Rev. Gen. PL i, 326 (1891). (Species mixta e generibus

alienis.)
Sjnlatithes pseudo-gummifera Forst. ex DC. Prod, v, 626 (1836) =

Laxmamiia arborea Forst. et Forst. f.
Spilanthes Romanzoffiana (C. et S.) Koehn. in Just Bot. Jahresber. xxii,

2, 595 (1897) = Spirauthes Romanzoffiana C. et S. in Linnaea.

iii, 32 (1828).
Spilanthes sessilifolia Hemsl. Biol. Centr. -Am Bot. ii, 193 (Oct.

1881).
Ceratocephalus sessili/olius (Hemsl.) Ktze. Rev. Gen. PI. i, 326

(1891) = Jaegeria hirta (Lag.) Less.
Spilanthes sessilis Poepp. Nov. Gen. et Sp. PI. iii, 50 (1844).

Ceratocephalus sessilis(Foei^^.) Ktze. Rev. Gen. PL i, 326 (1891) =

Jaegeria hirta (Lag.) Less.
Acmella spilanthoides Cass, in Diet. Sc. Nat. xxiv, 330 (1882) =

Wedelia camosa Pers.
Spilanthes tetrandra Roxb. in Beats. Tracts Relat. St. Helena, App. i,

325 (1816) ; DC. Prod, v, 626 (1836), sub. spp. exclus. = Lax-

mannia arborea Forst. et Forst. f.
Spilanthes tinctm-ia Lour. Fl. Cochinch. ii, 484 (1790) ; DC. Prod, v,

626 (1836), sub spp. exclus. = Adenostemma tinctorium {Lour.)

Cass.
Acmella trilobata Spreng. L.-Spreng. Syst. Veg. 591 (1826) = Zalu-

zania triloba (Ort.) Pers.
Spilanthes wedelioides H. et A. in Hook Jour. Bot. iii, 318 (1841).

Ceratocephalus wedeliodes ( H. et A. ) Ktze. Rev. Gen. PL i, 326

(1891) =Eclipta elliptica i)(7.

VOL. XLII. — 36

662 PEOCEEDINGS OF THE AMERICAN ACADEMY.

Index Collectorum cum Determinatione Specimincm
numeratorum eorundem.

A. Alfaro (Costa Rica) 5807B, Spilanthes ocymifolia.
"Allison V. Armour Expedition " (Mexico) 43, S. filipes.
C. R. Ball (Louisiana) 639, S. americana var. repens.

M. Bang (Bolivia) 2024, S. ocymfolia f. radiifera.

C. R. Barnes, C. J. Chamberlain, W. J. G. Land (Mexico), 9, S.

americana.
C. P. Bel anger (Martinica) 179, S. uliginosa.
"The Bernhardi Herbarium" (Terra ignota) 229, S. ciliata.

(Africa 1) 303, S. mauritiana.
P. BiOLLEY (Costa Rica) 7420, S. poliolepidica (specimen typicum).
M. BoTTERi (Mexico) 825, S. ocymifolia.

E. BouRGEAU (Mexico) 154, 603, 603 bis, 1630, S. americana — 2284,

S. americana var. ramosa — 3098, S. ocymifolia.
Herbarium Musei Imperialis Brasiliae (Brasilia) 1030, S. blephari-

carpa.
N. L. Britton (Jamaica) 830, S. uliginosa.
N. L. Britton, E. G. Britton, J. A. Shafer (Cuba) 206, S. in-

sipida.
N. L. Britton et J. F. Cowell (St. Christopher) 678, S. uliginosa.
W. H. et A. H. Brown (Sierra Leone) 32a, S. uliginosa.
W. J. BuRGHELL (Brasilia) 1025 et 9236, S. ciliata — 4734, S. oleracea

— 7956-2, S. Lundii.

B. F. Bush (Texas) 118, 252, 295, 712, 941, 1287 (Missouri) 82, 176,

178, (Arkansas) 248, S. americana var. repens.

C. Conzatti et V. Gonzalez (Mexico) 647, S. ocymifolia — 1241, S.

americana.

J. J. Cooper (Costa Rica) 5807, S. ocymifolia var. acutiserrata (speci-
men typicum).

T. Coulter (Mexico) 324, S. americana.

F. V. Coville (Arkansas) 99, S. americana var. repens. (Carolina

Borealis) 166, S. americana var. stolonifera.
J. F. Cowell (Panama) 392, S. uliginosa.
n. Cuming (Insulae Philippinae) 1154, S. grandiflora — 2361, S.

Acmella.
A. H. CuRTiss (Cuba) 684, S. americana. (Florida) 5882, in parte, S.

americana var. stolonifera — 5882, in parte, S. americana var.

stolonifera i longiinternodiata (specimen typicum) — 6000, S.

americana var. repens.

MOORE. — REVISION OF THE GENUS SPILANTHES. 563

C. C. Deam (Guatemala) 239, S. ocymifolia.

P. Duss (Guadeloupe) 893, 2o-21, 2822, 4447, S. uliginosa — 2498,

S. oleracea. (Martinica) 93U, S. uliginosa — 1449, S. oleracea —

1733 et 4077, S. urens.
H. F. A. V. Eggers (Dominica) 74 (Tobago) 5760 (Grenada) 6063,

S. uliginosa. (Ecuador) 14931, S. ciliata — 15646, S. ocymifolia

f. radiifera.
\y. Fawcett (Jamaica) 8005, S. uliginosa.
A. Fendler (Panama) 166, S. ocymifolia f. radiifera. (Venezuela) 691

et 69 iB, S. ocymifolia.
K. FiEBRiG (Paraguay) 345, S. americana var. stolonifera.
A. Fredholm (Jamaica) 3059, S. uliginosa.
G. Gardner (Brasilia) 4252, S. urens — ser. I, 70, S. Lundii — ser.

VIII, 3866, S. ciliata.
C. Gaudichacd-Beaupre (Brasilia) 681, S. oleracea — 682, S. ocymi-
folia f. radiifera.
G. F. Gaumer (Mexico) 1122, 1257, 1465, 2185, 2502, 3835, S.

filipes.
A. Ghiesbreght (Mexico) 557, S. americana.
J. M. Greenman (Mexico) 25 et 134, S. americana.
L. Hahn (Martinica) 126 et 726, S. urens — 1107, S. uliginosa.
E. Hall (Texas) 348, S. americana var. repens.
M. B. Halsted (Mexico) 32, S. americana.
T. Hartweg (Ecuador) 867, S. ocymifolia.

E. Hassler (Paraguay) 925, S. grisea var. micra (specimen typicum)

— 1211 et 4659, S. grisea — 1639 et 3370, S. americana var. sto-
lonifera — 4475, S. grisea var. setosa — 7651, S. grisea var. Cho-
datana (specimen typicum) — 8273, S. grisea var. intermedia —
8274, S. nervosa.

J. W. Helper (Burma ant Insulae Andaman) 3186, S. Acmella.

A. A. Heller et uxor (Porto Rico) 548, S. iodiscaea — 550a, S.
iodiscaea f. leucaena (specimen typicum).

A. Henry (Formosa) 219 et 812, S. Acmella. (China) 12706, S. Ac-
mella— 12260A, S. callimorpha (specimen typicum).

S. E. Henschen (Brasilia) ser. I, 269, S. oleracea.

H. T. Heyde et E. Lux (Guatemala) 3812, S. ocymifolia — 3381, S.
americana var. parvula f. lanitecta (specimen typicum) — 4209,
S. americana var. parvula — 4501, S. americana.

Edidit R. F. Hohen acker (India) 1017, S. calva.

J. R. Johnston (Venezuela) 102, S. ocymifolia.

F. W. Junghuhn (Java ?) 307, S. calva.

W. Lechler (Chile) 1532, S. urens var. hispidula.

564 PROCEEDINGS OF THE AMERICAN ACADEMY.

F. C. Lehmann (Guatemala) 1319, S. americana var. parvula f. parvi-
folia — 1596, S. americana. (Colombia) 3487 et 3599, S. ameri-
cana— 8010, S. subhirsuta. (Colombia aut Ecuador) 6446, S.
americana — 7987, S. ciliata.

F. E. Lloyd (Dominica) 473, S. uliginosa.

P. 6. Lorentz (Argentina) 76, S. americana var. stolonifera f. ciliati-

folia (specimen typicum).
P. G. Lorentz et G. Hieronymus (Argentina) 903, S. alpestris.
K. K, Mackenzie (Louisiana) 477, S. americana var. repens.

G. Mandon (Bolivia) 63, S. ciliata.

K. F. P. V. Martius (Brasilia) 438, S. Lundii.

G. McCarthy (Carolina Borealis) 5 (Carolina Australia) xxxi, S.
americana var. stolonifera.

Mexican Boundary Survey (Civitates Foederatae Americae?) 587, S.
americana var. repens.

C. F. MiLLSPAUGH (Mexico) 1494, S. filipes. (Jamaica) 1888, S. uligi-
nosa — 2028, S. urens.

C. MoRiTZ (Venezuela) 1387, S. ciliata.

T. MoRONG (Paraguay) 89, S. americana var. stolonifera.

S. MossMAN (Australia) 509, S. anactina.

Friedr. Mueller (Mexico) 267, 274, 4072, S. ocymifolia.

Herbarium Musei Imperialis Brasiliae (Brasilia) 1030, S. blepliari-
carpa.

E. W. Nelson (Mexico) 1032, S. americana.

E. Otto (Cuba) 94, S. insipida ?

E. Palmer (Mexico) 1565 et 1192, S. ocymifolia.

C. C. Parry et E. Palmer (Mexico) 464, S. americana.

G. S. Perrottet (India) 27, S. calva.

H. Pittier (Costa Rica) 3717 et 10546, S. macrophylla.

C. G. Pringle (Cuba) 75, S. limouica (specimen typicum). (Mexico)
1821, 9546, 9964, S. americana — 2946, 4340, 4341, 11572 S.
ocymifolia — 3489, S. disciformis — 3643, S. americana var. par-
vula—8637, 9539, 11312, S. pbaneractis.

A. F. Regnell (Brasilia) ser. II, 168, S. decumbens var. macropoda.

J. Reverciion (Texas) 161 et 1535, S. americana var. repens.

J. N. Rose, J. H. Painter, J. S. Rose (Mexico) 10055, S. americana.

F. RuGEL (Cuba) 6, S. insipida.

H. H. RusBY (Bolivia) 919, S. ciliata.
J. G. Sciiaffner (Mexico) 338 et 763, S. americana.
C. J. W. Schiede (Mexico) 229, S. americana.
W. ScHiMPER (Abyssinia) 134, S. abyssinica.

H. V. Schlagintweit-Sakuenluenski (India) sub catal. no. 12959, S.
oleracea.

MOORE. — REVISION OF THE GENUS SPILANTHES. 565

II. E. Seaton (Mexico) 73, S. araericana — 445, S. americana var.
ramosa.

F. Sellow (Brasilia) 848 et 1078, S. ciliata— 1764 et 3522, S. deciim-

bens var. macropoda — 1969, S. decumbens — 2796, S. decumbens
var. leptophylla.

J. A. Shafer (Cuba) 420, S. americana.

M. A. Shufeldt (Madagascar) 105, S. mauritiana f. madagascari-
ensis.

P. E. E. SiNTENis (Porto Rico) 718 (specimen typicum) et 1149, S.
iodiscaea.

H. H. Smith (Colombia) 513, S. ocymifolia f. radiifera (specimen typi-
cum) — 553, S. urens — 591, S. ocymifolia.

H. H. et G. W. Smith (St. Vincent) 96, S. uliginosa.

J. D. Smith (Guatemala) 1604, S. americana — 2125, S. americana
var. parvula.

L. C. Smith (Mexico) 131, S. americana.

A. SoDiRO (Ecuador) 39/1, S. ocymifolia.

C. Thieme (Honduras) 5309, S. macrophylla.

G. H. K. Thwaites (Ceylonia) 684, S. calva.

A. ToNDUZ (Costa Rica) 449, S. americana var. parvula — 1429 et
8493 — S, ocymifolia var. acutiserrata — 3030, S. americana —
7831, S. macrophylla — 12241, S. americana var. parvula f. par-
vifolia — 13628, S. oc}Tnifolia.

S. M. Tracy (Louisiana) 2485 et 8586 (Florida) 7148 (Texas) 7329,
S. americana var. repens.

"W. Trelease (Missouri) 544, S. americana var. repens.

J. Triana (Colombia) 1391, S. americana.

H. V. Tuerckheim (Guatemala) 124 et 758, S. americana — 8418, S.
americana var. parvula f. parvifolia — 8705, S. ocymifolia.

J. Tweedie (Argentina) 223, S. pusilla — 861, S. stenophylla.

W. Tyson (Pondoland) 1057, S. mauritiana.

. . . Vauthier (Brasilia) 308, S. caespitosa.

L. V. Velasco (Salvador) 8851, S. ocymifolia.

A. E. Wight (Jamaica) 35, S. uliginosa.

R. Wight (India) 449 et 1607, S. Acmella — 1456, S. calva.

C. Wright (Cuba) 3610, S. insipida.

566

PEOCEEDINGS OF THE AMERICAN ACADEMY.

INDEX NOMINUM BOTANICORUM.

In hac indice inclusa sunt primo nomina cum e genere Spilanthe tuni o
peneribus synonymis, deinde e generibus alienis nomina quae pro speciebus aut
varietatibus generis Spilanthis habita sunt. Exclusa autem sunt nomina planta-
rum revera generibus alienis pertinentiura quae ad genus Spilanthem immerito
attributae sunt ; quarum specierum exclusarum indicem supra p. 557 consultare
licet.

ABCDaria Rumpf., 523.
Acmella Rich., 523, 536.

biflora (L.) Spreng., 560.

brachyglossa Cass., 539.

brasiliensis Spreng., 530.

buphthalmoides (Jacq.) Rich., 560.

caulirhiza Del., 541.

caulorrhiza (Bentli.) Hook. f. et Jack.
541.

ciliata (HBK.) Cass., 538.

debilis (HBK.) Cass., 539.

fimbriata (HBK.) Cass., 538.

flavicaulis Raf., 500.

Garcini (Burm. f.) Spreng., 560.

globosa (Ort.) Spreng., 560.

hirta Lag., 560.

intermedia Rich., 558.

lanceolata Lk. var., 535, 554.

lanceolata Raf., 560.

Linnaea Cass., 534.

Linnaei Cass., 534.

mauritanica Hook. f. et Jack., 541.

mauritiana Rich., 541.

nudicaulis Raf., 501.

Nuttalliana Raf., 547.

occidentalis 1 Nutt., 547.

occidentalis (Willd.) Rich., 545.

parvifolia Raf., 5G1.

repens (Walt.) Rich., 547.

spilanthoides Cass., 501.

tenella (HBK.) Cass., 539.

trilobata Spreng., 501 .

uliginosa (Sw.) Cass , 537.
Acmella? Mutisii (HBK.) Cass., 545.
Acmella (Rich.) DC, 525, *536, 554.
Anthemis americana Mut., 545, 566.

occidentalis Willd., 645.

oppositifolia Lam., 645.

repens Walt., 547.
Athronia Neck., 623, 536.

Bidens Acmella (L.) Lam., 534.

acmelloides Berg., 530.

angustifolia Lam., 528.
var. minor Poir., 528.

fervida Lam., 530.

fi.xa Hook, f., 531.

fusca Lam., 530.

insipida (Jacq.) Lam., 5.30.

ocymifolia Lam., 532, 553.

oleracea (L.) Cav., 531.
Buphthalmum heterophyllum Willd.,
530.

strigosum Spreng., 530.

Ceratocephalus Burm., 523.
Acmella (L.) Ktze., 535.

var. depauperata Ktze., 537.

var. Pseudacmella (L.) Ktze., 561.

var. uliginosa (Sw.) Ktze., 537.

var. uliginosus (Sw.) Ktze., 537.
americanus (Mut.) Ktze., 545
anactinus (F. Muell.) Ktze., 529.
arnicoides (DC.) Ktze., 549.
Beccabunga (DC.) Ktze., 545.
ecliptodes (Gardn.) Ktze., 560.
exasparatus, (Jacq.) Ktze., 532.
fimbriatus (HBK.) Ktze., 530.
granditlora (Turez.) Ktze., 544.
insipidus (Jacq.) Ktze., 530.
javanicus (Scii. Bip.) Ktze., 558.
Karwinskianus (DC.) Ktze., 560.
leiocarpus (DC.) Ktze., 529.
leucanthus (HBK.) Ktze., 631.
bicolor (DC.) Ktze., 559.
caespitosus (DC.) Ktze., 540.
ciliatus (HBK.) Ktze., 539.
comnnitatus (Koch) Ktze., 569.
debilis (HBK.) Ktze., 539.
decumbens (Sm.) Ktze., 549.

y3. macropodus (DC.) Ktze , 550.

MOORE. — REVISION OF THE GENUS SPILANTHES.

667

Ceratoccphalus dccunibens (Sm.) Ktze.
var. doronicoidcs (DC.) Ktze., 549.

diffusus (roepp.) Ktze., 5o9.

inacropodus (Turcz.) Ktze., 558.

nitidus (Llav.) Ktze., 6G1.

papposus (Henisl.) Ktze., 543.

parvifolius (Heiitli.) Ktze., 546.

Poeppigii (DC.) Ktze., 539.

ramosus (Heinsl.) Ktze., 546.

repens (Walt.) Ktze., 547.

Salivaria (Domb.) Ktze., 632.

sessilifolius (Ilemsl.) Ktze., 5G1.

sessilis (Poepp.) Ktze., 501.

subliirsutus (DC.) Ktze., 540.

tenellus (HBK.) Ktze., 539.

urens (Jacq.) Ktze., 528.

wedeliodes (H. et A.) Ktze., 661.
Cenichis Gaertn., 523.
Cotula conica Wall., 534.

Spilanthus L., 528.
Erpota Raf., 536.
Ilelepta Raf. (subgenus) 559.
Heliantheae (DC.) Cass., 523.
Isocarpha Kunthii Cass., 531.
Jaegeria uliginosa (Sw.) Spreng., 537.
Magnoradiatae A. H. Moore, 525,

*.j42, 555.
Megaglottis F. Muell, 536, 542.
Mendezia DC, 523.

bicolor DC, 559.
Parvoradiatae A. H. Moore, 625, *530,

554.
Pyretiirum Med., 523.

Aomella (L.) Med., 534.

Bidens Med., 559.

Spilanthus Med., 580.
Rudbeckia bellioides Sm., 549.

decumbens Sm., 549, 557.
Salivaria DC, 524, *o27, 552.
Spilantheae Cass., 523.
Spilanthes Jacq., *522, 652 ; " Introduc-
tion " *521 (vide etiam s.vv. Spil-
anthus et Spilantus).

abyssinica Sch. Bip., 526, *544, 556.

Acmella Bl., 533.

Acmella F. Muell., 544.

Acmella (L.) Murr., 524, *534, 553.
var. albescentifolia A. H. Moore,

524, *535, 553.
var. calva (DC.) Clarke, 534.
var. lanceolata (Lk.) A. II. Moore,
524, *535, 553.

Spilanthes Acmella (L.) Murr.
var. olcracea (L.) ZolL, 531.
var. paniculata (Wall.) Clarke,

535.
var. uliginosa (Sw.) Bak., 537.
Acmella Wall., 534.
affinis II. et A., 559.
africana DC, 541.
alba Willd., 553.
alpestris Griseb., 525, *541, 555.
americana (Mut.) Hieron., 526, *5J5,
556.
var. parvula (Rob.) A. II. Moore,
526, *546, 556.
f. lauitecta A. H. Moore, 526,

*547, 556.
f. parvifolia (Benth.) A. H.
IMoore, 526, *546, 556.
var. ramosa (Hemsl.) A. H.Moore,

526, *546, 556.
var. repens (Walt.) A. II. Moore,

626, *547, 556.
var. stolonifera (DC.) A. H.
IMoorc, 527, *548, 556.
f. ciliatifolia A. II. Moore, 627,

*549, 557.
f. longiinternodiata A. H.
Moore, 527, *549, 557.
anactina F. Muell., 524, *529, 552.
arborea (Forst. et Forst. f.) Forst. f.,

559.
arnicoides DC., 549, 557.
f. grisea Chod., 550.
f. minor Chod., 559.
f. nervosa Chod., 5-59.
var. grisea Chod., 550.
var. intermedia Chod., 550.
var. leptophylla (DC) Bak., 550.
var. macropoda (DC) Bak., 550.
var. setosa Chod., 551.
Arrabidae Ilort., 558.
arrayana Gardn., 539.
atriplicifolia Iloutt., 559.
atriplicifolia L., 559.
Beccabunga DC, 545, 556.

var. parvula Rob., 546, 556.
bicolor (DC.) Benth. et Hook, f.,

559.
blepharicarpa DC, 527, *549, 557.
Botterii Wats., 532.
brasiliensis Spreng., 530.
caespitosa DC, 525, *540, 554.

568

PROCEEDINGS OF THE AMERICAN ACADEMY.

Spilantlies callimorpha A. H. Moore,

524, *536, 554.
calva DC, 524, *533, 553.
caulirhiza (Del.) DC, 541.

/3. madagascariensis DC., 542.
caulorrhiza Benth., 541.
cernua (L.) Koehn., 560.
chamaecaula A. H. Moore, 524, *528,

552.
ciliata HBK., 525, *538, 554.

var. diffusa (Poepp.) A. H. Moore,

525, *539, 554.
commutata Koch, 559.
costata Benth., 524, *535, 554.
crocata (Cav.) Sims, 560.
debilis HBK., 538.

decumbens (Sm.) A. H. Moore, 527,
*549, 557.
var. leptophylla (DC) A. H.

Moore, 527, *550, 557.
Tar. macropoda (DC.) A, H.
Moore, 527, *550, 557.
deltoidea Wall., 558.
diffusa Hook, f., 558.

f. minor Hook, f., 558.
diffusa Poepp., 539.
disciformis Rob., 525, *540, 555.
var. phaneractis Greeiim., 543.
doronicoides DC, 549.
ecliptoides Gardn. 560.
Eggersii Hieron. 539.
eurycarena A. H. Moore, 527, *551,

558.
exasperata Jacq. j8. cayennensis DC,

532.
filipes Grecnm., 526, *542, 555.
fimbriata HBK., 538.
gracilis (Big.) Koehn., 560.
grandiflora Turcz., 526, *543, 555.
var. brachyglossa Benth., 526, *544,

555.
var. calva Benth., 526, *544, 556.
grandifolia Miq., 558.
grandis DC, 539.

grisea (Chod.) A. H. Moore, 527,
*550, 557.
var. Chodatana, A. H. Moore, 527,

*551, 557.
var. intermedia (Chod.) A. II.

Moore, 527, «550, 557.
var. micra A. II. Moore, 527, *551,
558.

Spilanthes grisea (Chod.) A. H. Moore,

var. setosa (Chod.) A. H. Mo'ore,
527, *551, 557.
guatemalcnsis Vatk., 560.
helcnioides II. et A., 549.
iabadiceusis A. H. Moore, 526, *542,

555.
insipida Jacq., 524, *530, 552.
intermedia (Rich.) DC, 558.
iodiscaea A. H. Moore, 525, *536, 554

f. leucaeua A. II. Moore, 525, *537,
554.
javanica Sch. Bip., 558.
Karvinskiana DC, 560.
lateraliflora Klatt, 546.
Lehmanniana Klatt, 545.
leiocarpa DC, 529.
leptophylla DC, 550.
leucantha HBK., 524, *531, 553.
leucocephala Ott., 558.
leucophaea Hort. Berol. ? 532.
limonica A. H. Moore, 525, *541, 555.
longifolia DC, 559.
Lundii DC, 525, *538, 554.
Macraei II. et A., 529.
Macrali Ktze., 529.
macroglossa F. Muell., 544.
macrophylla Greenm., 526, *543, 555.
macropoda DC, 550.
macropoda Turcz., 558.
Mandonii Sch. Bip., 539.
Mariannae DC, 539.
mauritiana (Rich.) DC, 525,*541,555.

f. madagascariensis (DC) A. H.
Moore, 525, *512, 555.
melampodioides Gardn., 559.
multiflora Ott., 558.
Mutisii HBK., 545, 556.
mysurensis Wall., 558.
nervosa Chod., 524, *528, 552.
nitidus Llav., 561.
Nnttallii T. et G , 547.
ocymifolia (Lam.) A. H. Moore, 524,
*531, 553.

f . radiifera A. II. Moore, 524, 525,
*533, 553.

var. acutiserrata A. H. Moore,
524, *533, 553.
oleracca Jacq., 530.

/3.? fusca (Hort. Par.) DC, 530,531.
oleracca L., 524, *530, 552.

i8. rufa Ott., 531.

MOORE. — REVISION OP THE GENUS SPILANTIIES.

669

Spilanthcs oleraceus var. 151., 501.
orizabuL'nsis Soli. Bip., 545.
pallida Sweet, 558.
pammicrophylla A. H. Moore, 52G,

*5J4, 55G.
paniculata Wall., 535.
papposa Ileinsl., 520, *543, 555.
parvifolia Benth., 646, 566.
phaneracti3 (Greenm.) A. II. Moore,

52(J, *'AS, 555.
Poeppigii DC, 539.
poliolepidica A. II. Moore, 525,

*54U, 555.
popayanensis Hleron., 540.
portoricensis Spreng., 558.
portoriccensis Spreng., 558.
Pseudacmella Spreng., 535, 554.
Pseudo-Acmella H. et A., 558.
Pseudo-Acraella Wall., 534.
pseudo-gummifera Forst., 561.
pusilla H. et A., 524, *529, 552.
radicans Schrad., 532.
ramosa Hemsl., 546.
repens Hort. Par. et Berol., 559.
repens Spreng., 528.
repens (Walt.) Michx., 547.
rhombifolia Zipp., 558.
Komanzoffiana (C. et S.) Koehn., 561.
rugosa Bl., 534.

var. truncata Miq., 534.
Salzmanni DC, 538.
Sartorii Sell. Bip., 545.
sessilifolia llemsl., 561,
sessilis Poepp., 561.
Sodiroi Hieron., 532.
sp. Lor. et Niederl., 559.
sphaerocephala DC, 559.
sp. n. Zoll., 558.

stenophylla H. et A., 526, *542, 555.
stolonifera DC, 548.
var. pusilla (H. et A.) Bak., 529.

Spilanthcs subliirsuta DC, 525, *539,
554.
tenella IIBK., 538.
tetrandra Hoxb., 561.
tinctoria Lour., 561.
uliginosa Svv., 525, *537, 554.

var. Sell. Bip., 545.
urcns Jaeq., 524, *528, 552, 558.
0. liispidula DC, 520.
f. lanea A. II. Moore, 524, *529,

552.
var. hispidula DC, 524, *529, 552.
wedelioides II. et A., 561.
Spilanthus L., 623; (vide etiam s.vv.
Spilanthes et Spilantus).
Acmella (L.) Murr., 534.
albus L'Her., 532.
Amelia Koxb., 534.
caseata Steud., 560.
exasperata Jacq., 532.
fusca Hort. Par., 530.
liirta (Lag.) Steud., 560.
lobata Blanc., 535.
nielissaefolius Salisb., 534.
oleracea L., 530.
peregrina Blanc., 535.
Pseudo-Acmella (L.) Murr., 561.
radicans Jacq., 532.
Salivaria Donib., 532, 553.
uliginosa Sw., 537.
Spilantus R. W. Darw., 523 (vide
etiam s.vv. Spilanthes et Spilan-
thus).
Aemella R. W. Darw., 534.
atriplifolius R. W. Darw., 559.
Verbesina Acmella L., 534.
buplithalmoides Lk. et Ott., 549.
Pseudacmella Spreng., 535.
Verbesineae (Cass.) Lindl., 523.
Verbesininae O. Hoffm., -523.
Verbisina Amelia Roxb., 634.

Proceedings of the American Academy of Arts and Sciences.
, Vol. XLII. ISTo. 21. — March, 1907.

CONTRIBUTIONS FROM THE CHEMICAL LABORATORY
OF HARVARD COLLEGE.

CONCERNING THE ADIABATIC DETERMINATION OF
THE HEATS OF COMBUSTION OF ORGANIC SUB-
STANCES, ESPECIALLY SUGAR AND BENZOL.

By Theodore W. Kichards, Lawrence J. Henderson, and

Harry L. Frevert.

iNVESnOATIONS ON LlOHT AND HRAT MADE AND PtirXlSHED, WHOLLY OB IN PABT, WITH APPBOPEIATION

FBOM THB RUMPOBD FCND.

CONTRIBUTIONS FllOM THE CHEMICAL LABORATORY OF

HARVARD COLLEGE.

CONCERNING THE ADIABATIC DETERMINATION OF THE

HEATS OF COMBUSTION OF ORGANIC SUBSTANCES,

ESPECIALLY SUGAR AND BENZOL.

Bv Theodore W. Richards, ^Lawrence J. Henderson, and Harry

L. Frevert.

Presented January 9, 1907. Received December 4, 1906.

Introduction.

As a preliminary step to the determination of the heats of combus-
tion of an extended series of organic substances, desired for certain
theoretical considerations, measurements were made on two common
substances, cane-sugar and benzol. These substances were chosen in
order that one might represent solids and the other volatile liquids,
and because they may be easily obtained in a high state of purity, as
well as because their heats of combustion have been carefully studied
by other investigators.

This investigation offered the opportunity for further testing and
improving the adiabatic calorimetric method recently proposed and
tested by Richards, Henderson, and Forbes,^ by means of which cor-
rections for accidental loss of heat and for the lag of the thermometer
are experimentally eliminated. The method was devised in the hope
that its use might increase the accuracy of thermochemical work ; and
this hope is j ustitied by the present experience. The principle of the
method is to cause the temperature of the surroundings of the calo-
rimeter to change in the same direction and at the same rate as the
calorimeter itself This is accomplished by surrounding the calorim-
eter with vessels in which a suitable warming reaction can take place
in a manner fulfilling the above conditions. A reaction easily regu-
lated and well suited to this purpose, namely, the neutralization of an
alkali with an acid, was chosen for this purpose.

1 These Proceedings, 41, 3 (1905) ; Zeit. phys. Chem., 52, 551 (1905).

514: PROCEEDINGS OF THE AMERICAN ACADEMY.

The Apparatus.

A vertical section of the apparatus is shown in the accompanying
diagram. The large outer vessel (A) and the covering vessel (B),
designed for holding the alkaline solution, were made of sheet copper.
On account of the corrosive action of the caustic solution to which the
vessels are continually exposed, the joints must be very thoroughly
soldered, otherwise the corrosion may give rise to annoying leaks.
These are of serious consequence if they occur in the cover, because
then they may allow the solution to pass into the calorimeter or into
the narrow air-space surrounding the calorimeter.

The inner vessel (C) protecting the calorimeter itself from the alka-
line surrounding liquid was a heavy nickel-plated copper can well
burnished in the interior and firmly adjusted in the outer vessel
several inches above the bottom, so as to allow a free circulation of the
liquid beneath it.

The calorimeter proper (D) was placed inside of this inner vessel,
resting on several bits of cork and separated by an air-space of about
two millimeters from its burnished nickel inner surface. This calo-
rimeter was made of pure silver; it weighed 1357 grams and had a
capacity of about 4432 milliliters ; in operation it was filled with
water, completely submerging the combustion bomb which rested upon
points bearing on its base. The German-silver stirrer (E) which agi-
tated the water in the silver calorimeter consisted of two perforated
rings on upright supporting wires, and was moved up and down at a
perfectly regular rate by means of an electric motor with a worm-gear
attachment. This stirring arrangement was found to be very satis-
factory, as it produced a complete and rapid adjustment of the
temperature of the calorimetric system during a combustion, and the
comparatively slow motion gave rise to no warming correction during
the seven or eight minutes necessary for the actual combustion.

The copper pan (B) used as a cover to both calorimeter and outside
jacket, was provided with copper tubes for the stirrers and thermome-
ters projecting below it ; its temperature also was changed in the same
manner as that of the outer jacket by adding acid to its alkaline con-
tents, so as to follow the effect of the heat of the combustion. The
liquid in the cover was stirred by a large oscillating perforated copper
ring (F) actuated by the same motor which raised and lowered the
stirrer of the calorimeter. It was found unnecessary to follow the
change in temperature of the calorimeter as closely in the cover as
in the jacket, although had this been necessary it might as easily have
been done.

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 575

Figure 1.
Vertical Section.

A. Outer vessel.

B. Covering vessel.

C. Nickel-plated cop-

per can.

D. Silver calorimeter.

E. Stirrer for calorime-

ter.

r. Stirrer for covering
vessel.

H. Stirrer for outer
vessel.

I.

J.

Copper cover.
Burettes.

K. Crucible containing
substance to be
burned.

L. Thermometer.

576

PROCEEDINGS OF THE AMERICAN ACADEMY.

On the other hand, it is imperative that the heat generated by the
reaction of the acid and the alkali in the outside can should be evenly
and very quickly distributed, so that the change in temperature of the
outer jacket may follow as closely as possible the change in tempera-
ture of the calorimeter. This was accomplished by running the acid
into the alkaline solution in the immediate vicinity of a very powerful
rotary stirrer (H), which drove the solution downward and at the same
time around the vessel. This stirrer was propelled by an electric motor,
and kept the liquid very thoroughly agitated. In order to prevent
splashing into the calorimeter or into the air-space around the calorim-
eter, a covering sheet of copper (I) was bent down so as to fit snugly
around the inner nickelled copper can (C) ; this sheet extended to the
edge of the outer jacket. This cover effectually prevented injurious
splashing, no matter how violent was the agitation of the liquid.

The acid was run both into the outer vessel and into the cover from
burettes (J), which were calibrated, not in cubic centimeters, but in
tenth degrees of temperature. In other words, the amount of acid
necessary to raise each of the outer systems xV° ^^^ determined by
trial, and the burettes were marked accordingly.

The bomb used in this work was made after the model of those
used by Atwater by the firm of Dinsmore and Singleton, Middletown,
Connecticut. The interior and top of the bomb were lined heavily

with platinum. Every part of
the apparatus exposed to the
oxygen under pressure during a
combustion was of platinum,
except a lead gasket which made
the joint gas tight when the top
of the bomb was screwed down.
The presence of a rim of lead
caused at first serious difiiculty
on account of its rapid oxida-
tion by the oxygen under pres-
sure during a combustion. This
might introduce a small error of
unknown and probably varying
magnitude ; in some cases the
quantity of lead converted to oxide was considerable. Lead gaskets both
gold-plated and covered with gold foil were tried without success.
The difiiculty was finally solved by the use of gold in the following
manner. A lead gasket was fitted in position and the top screwed
down upon it several times in order to form a depression in the centre

Figure 2. Detailed section of edge
of bomb, a, showintj tlie platinum lining,
d, and the method of protecting the lead
gasket, b, with gold foil, e. The gasket
is partially cut away at c.

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 577

of the gasket and force out the sides. Some of the lead at the inner edge
was then cut away as shown in the diagram. Small strips | | of

sheet gold, previously annealed, were inserted around this edge so that
they might overlap, after which the top was again screwed down several
times in order to wedge in the strips of sheet gold. The gold was
then bent back over the lead and the top screwed down in order to
smooth out the gold lining. A lining of this sort proved entirely
satisfactory, though in time a very slight oxidation of the lead occurred,
due to the loosening of several of the gold strips. This oxidization was,
however, too slight to affect the results, for when a new lining replaced
the old, no variation in the results could be detected.

Instead of the shallow dish ordinarily used for holding the sub-
stance to be burned, a platinum crucible (K) weighing about 15 grams
was substituted. The platinum crucible has probably several advan-
tages over a shallow dish, especially in the combustion of liquids.
The high sides of the crucible tend to prevent loss by projection of
the material, and the heat at the moment of ignition is probably con-
centrated, thus securing a more comjjlete combustion.

The thermometer (L) was made by Fuess after the ordinary Beck-
mann model, with a large bulb containing about 75 grams of mer-
cury and possessing a wide and very freely moving thread of mercury.
It had been standardized by the Prussian Physikalisch-Technische
Reichsanstalt and was subsequently compared here with a most care-
fully constructed Baudin thermometer, and with another similarly
standardized Beckmann thermometer. All measurements were made
over about the same part of the scale, in order to make the results with
benzol as closely comparable as possible to the results with sugar.

The oxygen used was similar to that used by Atwater, and was
obtained already compressed in steel cylinders from the White Dental
Company of Boston. In order to insure a certain standard of purity
in the oxygen, samples of each cylinder were analyzed volumetrically
for oxygen, and check combustions were frequently performed with
sugar. As a rule, this oxygen contained between 2.7 and 3.2 per cent
of nitrogen and no chlorine. In work at present in prospect, it is pro-
posed to prepare purer samples of the gas. The effect of the impu-
rity of nitrogen is discussed in detail below.

Purification of Material.

Cane-Sugar, C10H22O11. Three samples of sugar, designated A, B,
and C, were used in this investigation. The source of each sample
was the crystallized sugar or "rock-candy" of commerce. For the
first, called Sample A, powdered " rock-candy " was dissolved in boil-

VOL. XLII. 37

678 PROCEEDINGS OF THE AMERICAN ACADEMY.

ing distilled water until the solution was almost saturated. The hot
solution was filtered through asbestos in a platinum Gooch crucible
and allowed to cool in low crystallizing dishes. After inoculating the
solution with several minute sugar crystals, the substance began to
crystallize slowly in fine granular crystals. Several days afterwards
the sugar was separated from the syrup by filtration through a Gooch
crucible with suction, being washed with distilled water several times
during the process. "When the greater part of the solution had been
drawn off, the sugar was put into short funnels fitted with platinum
cones and subjected to centrifugal action. During the whirling it was
several times washed and stirred with distilled water. The sample
was desiccated, powdered in an agate mortar, and preserved in a
desiccator.

Because this sample, A, might be not completely free from included
water, another sample of sugar was crystallized from its solution in a
mixture of water and ethyl alcohol which had per gram the same heat
of combustion as sugar. In this case, if the sugar included some of the
liquid from which it was crystallized, the weighed mother-liquor would
give the same heat of combustion as an equal weight of sugar. This
preparation was conducted in the following way. A concentrated solu-
tion was made fi'om powdered " rock-candy " and a known quantity of
hot distilled water ; and while the solution was still hot, it was filtered
through asbestos in a platinum Gooch crucible. To this solution was
added such a weight of absolute alcohol that the mixture of water and
alcohol should have the same heat of combustion as sugar. After
standing a short time, the sugar began to separate out as fine granular
crystals. The dishes with the sugar solution were covered, and at the
end of several days the sugar was filtered off and treated in the same
manner as sample A, except that it was washed with a mixture of
water and alcohol having the same heat of combustion as sugar.

The third sample, C, was prepared at a different time and with differ-
ent material, but in a manner similar to the latter method.

Benzol, CgHg. Two samples of benzol were prepared as follows.
For the first, sample A, 500 grams of Merck's benzol, freed from
thiophene, were agitated in a flask submerged in a bath of ice and water
until about two thirds had crystallized. The crystals were allowed to
drain slowly, so that any adhering benzol might be washed off by the
liquid formed from the melting crystals. The crystals were then
allowed to melt and the above process repeated three more times.

For the second, sample B, the same quantity of Kahlbaum's similar
preparation was agitated in a flask submerged in a bath of ice and
water until about one third of the benzol had crystallized. These crys-

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 579

tals were drained, melted, and then recrystallized, about the first fifth
of the crystals being discarded. From the remaining benzol about one
third was allowed to crystallize. These crystals were drained, melted,
and recrystallized as before, the first crystals being discarded. About
one half of the remaining benzol was allowed to crystallize and was
retained as the final sample. The freezing-point of this sample was
determined in a regular Beckmann fi-eezing-point apparatus, using all
of the precautions to prevent supercooling. The freezing-point was
found to remain constant until practically all of the sample tested was
frozen, thus indicating its purity. Especial care was taken to keep
these preparations free fi-om dust and other impurities, both during
and after the purification.

The thermochemical results showed that these two samples were
essentially the same, as far as the present purpose was concerned.

The Combustion of Sugar,

The details of conducting a combustion of sugar in the calorimetric
bomb in the adiabatic calorimeter are easily told.

About 1.5 grams of sugar were accurately weighed in the platinum
crucible in which the substance to be burned was placed. The sugar
was not compressed into tablets, as has been the custom of previous
investigators, but was burned as a powder. This method is the less
troublesome and also the safer one, in that it involves less manipulation
of the substance ; moreover, in a preliminary series of experiments it
was found that powdered sugar and sugar tablets gave perfectly con-
cordant results.

The platinum crucible was placed m its support, a platinum ring
secured to one of two stout platinum wires projecting downward from
the cover of the bomb. These wires formed the terminals of an electric
circuit. A spiral of very fine iron wire to serve as the igniter was sus-
pended between them, dipping into the crucible and buried in the
sugar. A small amount of water, never more than a milliliter, was
sprayed into the bomb, so that the space might be saturated with
water- vapor, in order to avoid a correction for the evaporation of part
of the water formed by the combustion. The cover was then placed
on the bomb, and a gas-tight joint was made by means of the screw-
cap fitting over it. Oxygen was run into the bomb until it was under
a pressure of 35 atmospheres. This high pressure was always used, in
order to be more certain of obtaining complete combustion, unless
otherwise indicated.

Meanwhile the rest of the apparatus was being prepared. The dilute
alkaline solution in the jacket and cover was brought to a temperature

680 PROCEEDINaS OF THE AMERICAN ACADEMY.

a little below that of the room, and the bomb was placed in the silver
calorimeter. Connections were prepared for the later use of an electric
current by joining a copper wire to the bomb itself, and another, care-
fully insulated, to the tip of that one of the two stout platinum wires
which was insulated from the bomb. The water for the calorimeter, 3302
grams at 20° C, was now measured in a marked flask, and poured into
the silver vessel, submerging the bomb, at nearly the temperature desired.
The cover containing dilute alkali was put in position, and its tempera-
ture roughly adjusted to that of the calorimeter. The stirrers were set
in motion, and the thermometers and burettes clamped in position. The
temperatures of the two systems were taken with a 0.01° thermometer ;
if, after all was ready, a slight difference existed between the tempera-
tures of the calorimeter and the other jackets, the latter were easily
adjusted by a little ice, or a little hot water or acid, until the whole ap-
paratus was very nearly the same temperature throughout, that is to
say, within a few hundredths of a degree. All measurements were made
between 20° and 25° C. Readings every one or two minutes were now
taken on the accurate Fuess thermometer, which was always jarred by an
electric vibrator before reading, in order to prevent errors due to friction
of the mercury thread. As soon as the readings assured constancy of
the temperature of the calorimeter, the switch, completing the electric
circuit through iron wire in the bomb, was lowered, and the sugar
ignited by the combustion of the wire.^ In a few seconds the tempera-
ture of the calorimeter began to rise, and the change in temperature
was equalled in the outer system by adding concentrated sulphuric
acid from the burettes. For about the first minute the temperature
of the outer system, as indicated by the quantity of sulphuric acid
used from the burettes, was kept about 0.1° to 0.05° above that in-
dicated by the thermometer in the calorimeter, so as to allow for
thermometric lag and give time for the equal distribution of the heat
in the jacket. In from four to five minutes the calorimeter reached its
maximum temperature, and the thermometer gave constant readings.

The great advantage of this adiabatic method of calorimetry is
shown at this point by the constancy of the thermometer at the com-
pletion of the combustion. The thermometer usually gave constant
readings for a long time after it had reached its maximum, showing
indubitably that there was no appreciable heat exchange between the
calorimeter and its surroundings. Moreover, there was plenty of time
in which to read the thermometer accurately, while the mercury thread
was stationary, and no thermometric lag was possible.

^ The electrical heat thus intrmluccd is very small in amount, and is wholly
eliminated by the coraparative method finally used for calculating the results.

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 581

After the combustion, the pressure of the gas in the bomb was
relieved and the bomb opened. The interior of the bomb and the
crucible were always inspected for any caramel or unburned sugar, but
in only two cases among the preliminary and rejected experiments was
any trace of caramel noted. The remaining gas was repeatedly ana-
lyzed after combustions of sugar for carbon monoxide, with negative
results. Any unburned iron wire was measured, and a correction sub-
tracted from the knoAvn heat of combustion for the original amount
used. The interior of the bomb and the crucible were rinsed with dis-
tilled water, and these washings, containing the nitric acid formed in
the combustion, were titrated with a solution of sodium hydroxide,
which was standardized so that one milliliter was equivalent to a
known rise in temperature of the calorimetric system. Corrections for
the burning of the iron wire and the formation of nitric acid were of
course subtracted from the observed rise in temperature.

The data of a typical combustion of cane-sugar follow.

Combustion No. 2.

The weight of sugar (Sample A) taken was 1.5270 grams. The
calorimeter was adjusted at 2.55 o'clock.

Temperature of jacket = 1.50*^
Temperature of cover = 1.50

The sugar was ignited at 3.08.10 o'clock, and the rapidly rising
temperature of the interior was equalled in the jackets and cover.

Time.

Reading of thermometer
iu calorimeter.

3.03

1.495°

.05

1.496

.06

1.496

.07

1.496

.08

■ 1.496

Time.

Beading of thermometer
in calorimeter.

3.10

3.050°

.11

3.108'

.12

3.116

.13

3.117

T/^w

.14

3.117

leu

.15

3.117

len

.17

3.117

.18

3.II7J

Temperature of jacket = 3.11"
Temperature of cover = 3.19

The observed rise of temperature was therefore

3.117° - 1.496°= 1.621°.

582

PROCEEDINGS OF THE AMERICAN ACADEMY.

-0.015°

-0.003°
+0.001°

-0.017'

15 cm. iron wire were burned, causing a correction of

4.1 milliliters of sodium hydrate solution were used, indicating

nitric acid corresponding to a correction of
The correction for graduation of the thermometer was

Total,

Therefore the corrected rise of temperature is

1.621° - 0.017° = 1.604°.

This would correspond to 1.050° per 1 gram cane-sugar.

Below is given a table containing all the results with sugar, except
the few rejected preliminary determinations.

Data concerning the Combustion of Sugar.

Number.

Sample.

Rise in Temperature
per gm. Cane-sugar.

Average.

1

2
8

A
A
A

1.050 1 *
1.050*
1.052 *

o

1.0506

4

6
6

7

8

9

10

B
B
B
B
B
B
B

1.050
1.050
1.051
1.050
1.050
1.052
1.050

1.0504

11
12
13
14

C
C
C
C

1.049 t
1.052 t

1.050 t
1.050 t

1.0503

Average of 14 determinations, 1.0504°.

* Under .a pressure of 25-27 atmospheres of oxygen.

t Combustiona made by L. J. Henderson. All others were made by 11. L.
Frevert.

RICHARDS. — U-RXTS OF COMBUSTION OF ORGANIC SUBSTANCES. 583

The purity of the sugar is indicated by the essential identity of the
results obtained from three difterent samples.

In Determinations Nos. 7 and 8 the bomb was exhausted before run-
ning in the oxygen, and in Determinations Nos. 9 and 10 the amount
of nitrogen was increased to about 13 per cent by volume in the
compressed atmosphere of the bomb, by pumping in air in the first
place, and then supplying the oxygen to 35 atmospheres pressure.
The essential identity of these results with the others shows that the
presence of even this large amount of inert gas does not aflfect the
heat of combustion of a substance so easily burned as sugar.

In these experiments it appears probable that the greatest experi-
mental error in a combustion lay in the reading of the thermometer.
Probably with a scale divided to jl-g°, even with a good lens, one may
make an error of 0.001°. Should this error be made in the same direc-
tion in the two extreme readings, the errors would cancel each other.
However, should the errors be made in opposite directions, then in a
rise of two degrees this error in reading the thermometer would amount
to a percentage error of 0. 1 per cent. The average result should be
much more accurate than this, however. The agreement of the re-
sults of cane-sugar is in accord with this consideration of error. In
the future, measurements of the more important substances, when
other conditions justify a greater refinement, will be made with a
platinum resistance thermometer.

The Combustion of Benzol.

The first problem to be solved in the combustion of a volatile liquid
was to devise a method by which an accurately weighed quantity of it
might be burned. Berthelot ^ determined the heat of combustion of
benzol by saturating cellulose with the liquid, which was then ignited
in the bomb. This method of procedure is evidently open to the
error of a varying loss in weight of benzol by evaporation. Besides,
since in this case some of the benzol must burn as vapor, which of
course gives a greater heat of combustion than liquid benzol, a cor-
rection should be subtracted accounting for the heat of evaporization
of that portion of the benzol burned as vapor. These objections ac-
count, in part at least, for the irregularity of his results.

Julius Thomsen * burned benzol both as vapor mixed with air and
as a liquid in his Universal Burner. By these methods he obtained at
various times four series of results, one of which was not at all in

3 Ann. Chim. et Phys. (5) 23, 193 (1881).
* Thermo. Untersuch., 4, 59.

584 PROCEEDINGS OF THE AMERICAN ACADEMY.

agreement with the others. Probably, as Stohmann pointed out, the
results with the Universal Burner were too high.

Stohmann ^ obtained most of his values for benzol by combustion in
a different kind of lamp. Subsequentlj'',^ however, he sealed benzol in
very thin glass bulbs which were placed in the bomb and broken by
shaking just before the bomb was placed in the calorimeter. This
method involved a necessary correction for the benzol burned as vapor.
Stohmann thus secured two results concordant with those previously
obtained, but he had much difficulty on account of the incomplete
combustion of the benzol. Of a series of determinations, he obtained
only these two which were not vitiated by the deposition of soot on
the interior of the bomb.

In order to burn completely a weighed quantity of liquid benzol
without applying a correction for vaporization, the follo'wing procedure
was followed in the present investigation. Thin glass bulbs of about
0.7-0.8 milliliters with bent capillary stems were weighed, and filled
with benzol by immersing the stems under benzol, alternately cooling
and warming the bulbs in cold and hot water. The thin walled capil-
lary stems, filled with benzol, were sealed off near the bulbs in a fine
blowpipe flame. In this way bulbs could be obtained either com-
pletely filled or with a negligible amount of vapor in the short capil-
lary stem.7 The bulbs and the detached capillary stems were weighed
together under the same conditions as the empty bulbs, and the
weights of benzol thus determined.

For combustion one of these bulbs was placed upon the top of about
0.25 gram of carefully weighed pure sugar in the combustion crucible,
and the rest of the procedure was exactly the same as in the case of
cane-sugar. The great heat of the burning sugar caused the bulb of
benzol to burst with the consequent immediate combustion of the
benzol. In the preliminary trials small patches of soot due to incom-
plete combustion of the benzol were noticed on the crucible and on the
lining of the bomb. This inadmissible complication was traced to the
fact that the stems of the bulbs were from one to two centimeters in
length. After sealing new bulbs in such a way that the stems were
only three to five millimeters long, no trace of soot ever appeared.
Some idea of the temperature in the crucible at the moment of com-
bustion may be gained from the fact that after a combustion the glass

0 Jour. f. prak. Cliom., 33, 241 (1886).

6 Ibid., 40, 77 (1889).

' This method of enclosing liquids in thin bulbs in such a way as to be capa-
ble of subjection to high pressure was first used by Richards and Stull in their
work on Compressibility (Carnegie lust. Pub., 7, 1903).

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 585

of the bulbs was always found at the bottom of the crucible fused into
small globules.

A peculiar nitrous odor was in some cases observed in the gas in the
bomb after a combustion. In order to discover whether this odor
might be due to the formation of small amounts of some of the oxides
of nitrogen which were not completely absorbed by the water, the fol-
lowing test was made on the gas in the bomb after combustions No. 12
and No. 25. The gas from the bomb was allowed to bubble slowly
through gas-washers made of test tubes containing cold distilled water.
This water was then boiled for some minutes to expel carbon dioxide,
and was then titrated with a very dilute sodium hydroxide solution
and phenolphthalein. The first drop of alkali turned the solution red,
so there must have been very little of the acid-forming oxides of nitro-
gen, nitric or nitrous acids in the gas. Any nitric oxide formed in the
bomb would have been immediately converted to nitrogen peroxide in
presence of the excess of oxygen, and would have dissolved in the
water. The washings of the bomb also were tested for nitrous acid
with a-naphthylamine and sulphanilic acid ; but negative results only
were obtained. In a number of other determinations under varying
conditions (Nos. 21, 22, 23, 24, 27), no odor whatever was noticeable
in the escaping gas, although the quantitative results were not essen-
tially different from similar ones in which an odor was noticed. Hence
it appears that whatever may have caused this odor, it has no appreci-
able effect on the heat of combustion of benzol ; no connection could
be found between the presence of the odor and the effect of increasing
the per cent of nitrogen present. Nevertheless the matter will receive
further attention in the future.

The first trials of this method were from one cause or another unsuc-
cessful, as is usual in such cases ; but after eleven such partial failures
satisfactory results were regularly obtained. After a series of five
consistent values (Nos. 12-16) for benzol had been found, two com-
bustions (No, 17 and No. 18) were made in which the air in the bomb
was almost entirely removed before the oxygen was run in. It was
hoped that two advantages might be gained by conducting the com-
bustion in the absence of the nitrogen of the air originally contained
in the bomb : first, that the cause of the nitrous odor might be removed ;
second, that the correction for the formation of nitric acid would be
decreased. These new experiments gave for the heat of combustion
of benzol a value higher than the average previously obtained by over
0.3 per cent, — a greater deviation than could be ascribed to the errors of
the method. This interesting observation being new, so far as we could
discover, the matter was pursued further. Three more combustions

586 PROCEEDINGS OF THE AMERICAN ACADEMY.

(Nos. 19, 20, and 21) were made in the usual way with the bomb origi-
nally filled with air, and the average value for the heat of combustion
of benzol in this series was the same as that obtained in the first series.
Again three combustions (Nos. 22, 23, and 28) were made with the air
removed from the bomb before the oxygen was run in, and again results
were obtained more than 0.3 per cent greater than the results of the
combustions in which the bomb was filled with air at the beginning.
At the same time, in those cases in which the bomb was exhausted
the amount of nitric acid formed during a combustion did not appreci-
ably diminish, hence it was evident that the oxygen in use must
contain nitrogen.

After due consideration of these results the logical conclusion seemed
to be that the presence of an inert gas such as nitrogen in some way
or other interfered with the complete burning of the benzol, and there-
fore lowered the heat of combustion. In order to test this hypothesis
further, more combustions were made in the presence of still greater
concentrations of nitrogen, under which conditions the heat of com-
bustion should be still more diminished. To accomplish this, air was
forced into the bomb by means of an ordinary bicycle-pump, and the
pressure of the air forced in was measured on the pressure-gauge.
Oxygen was then run in until the pressure inside the bomb was 35
atmospheres. Since the amount of nitrogen in the oxygen had been
determined, it was a simple matter to calculate the approximate
amount of nitrogen in the bomb. The results of the combustions
made under these conditions agreed with the hypothesis, and while
the relation was not a simple ratio, yet the results showed clearly
beyond a doubt that the greater the concentration of nitrogen the
lower the heat of combustion. This effect of nitrogen in combustion
suggests the retarding influence of oxygen on the rate of formation
of hydrochloric acid when hydrogen and chlorine are exposed to the
light,^ and numerous similar phenomena, sometimes classified under
the general head of negative catalysis.

In presenting these results, a typical determination is given in detail,
in order to illustrate further the method of calorimetry ; afterwards a
table giving all the later results with benzol is recorded.

Determination No. 23,

Weight of benzol (A), 0.5840 gram.

Weight of sugar (B), 0.2073 gram.

Air was exhausted from the bomb before admitting oxygen.

The bomb was immersed in the calorimeter at 11.25 o'clock, and
the temperature of jacket and cover were adjusted at 11.30 o'clock.

8 Bunsen and Roscoe, Pogg. Ann., 96 (1855) ; Phil. Trans., 147, 389 (1857)

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 587

Time.

Reading of thennometer.

11.33

2.326°

.35

2.327

.37

2.328

.39

2.330

.41

2.330

.43

2.3.30

.45

2.330

nition occurred at 11.45.

Time.

Reading of thermometer.

11.47

4.07°

.48

4.110

.49

4.116

.50

4.117 +

.51

4.118

.52

4.118

.53

4.118

.54

4.118

Temperature of jacket = 2.31°
Temperature of cover =2.32"

'I'

Temperature of jacket = 4.10°
Temperature of cover =4.20°

Observed rise of temperature = 4.118° — 2.330° = 1.788°
There was little if any odor in gas remaining in the bomb after com-
bustion. 11.0 centimeters of iron wire were burned, and 4.0 milliliters
of the solution of sodium hydrate were used.

From the observed rise of temperature, 1.788°, the following correc-
tions must be subtracted :

For error in graduation of thermometer =
For the combustion of 0.2073 gram sugar =

" 11 cm. iron wire =
" nitrogen to nitric acid =

Total,

—0.001°
—0.218°
—0.011°
—0.003°

-0.233°

of 0.5840 gram of benzol raises the
= 1.555°, and 1 gram of benzol would

Therefore the combustion
temperature 1.788° - 0.233°
raise the temperature 2.662°.

In this result, 2.662°, mistakes of 0.001° in reading the initial and
final thermometric height would cause an error of almost 0.004°, if the
mistakes happened to be in opposite directions. On comparing a num-
ber of determinations, one would therefore expect to find an occasional
deviation from the mean as large as this ; but the mean should be much
more accurate, because in many determinations such accidents tend to

588

PROCEEDINGS OF THE AMERICAN ACADEMY.

balance one another. The study of the results given below confirms
these inferences. The following table is arranged according to the
amount of nitrogen present in the oxygen at the time of burning ;
it contains the results of all the combustions except the rejected
preliminary ones.

Determina-
tion No.

Sample

of
Benzol.

Per cent
Nitrogen.

Rise in Temperature
of System for
1 gm. Benzol.

Average and
Probable Error.

23
28
17
18
22

A
A
B
B
B

2.7
3.2

2.7
2.7
2.7

2.662
2.661
2.661
2.663
2.663

o

2.662
±0.0006

12
13
14
15
16
19
20
21

A
A
A
A
B
B
B
B

4.9
4.9
4.9
4.9
4.9
4.9
4.9
4.9

2.655
2.658
2.653
2.656
2.651
2.657
2.657
2.650

2.655
±0.0007

26
25
24

27

A
B
A
B

9.7

9.6

10.1

11.9

2.660
2.649
2.643
2.650

2.650
±0.0023

It is seen at once, from the averages in the right-hand column, that
an increasing amount of nitrogen decreases the heat of combustion
to an extent far beyond the limit of accidental error. In this respect
the results with benzol are very different from those with sugar, which
has previously been shown to be unaffected by the presence of much
nitrogen. The nature of the gaseous or liquid uuburut residue in the

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 589

case of benzol has not been determined ; solid carbon, at least, was
wholly absent.

Those determinations in which the least nitrogen was present un-
doubtedly represent the closest approach to the true value for the
heat of combustion of benzol. The first average of five determinations
in the presence of about 3 per cent of nitrogen gives 2.662° as the
rise in the calorimetric system for 1 gram of benzol. This, in our
opinion, represents a minimum value ; the true one may be yet higher.
It is planned to determine soon the heat of combustion of benzol in the
presence of pure oxygen.

Obviously, data on only two substances will not permit the drawing
of certain general conclusions. Nevertheless, it seems reasonably prob-
able that the effect in general of the presence of an inert gas during
the combustion of easily burned substances is very slight. On the other
hand, other substances like benzol which need much oxygen for their
combustion are probably, like it, affected by the presence of an inert
gas.

Since the water-equivalent of our bomb and calorimeter has not
been determined either by the method of finding the sum of the
water-equivalents of the component parts, or by the admirable electri-
cal method of Jaeger and von Steinwehr,^ absolute values for the
heats of combustion of sugar and benzol cannot be computed from
these data. Until an accurate value for the absolute heat of combus-
tion of some standard pure substance has been obtained, the present
results may be expressed as ratios, taking the rise in temperature of
the calorimetric system caused by the combustion of one gram of cane-
sugar as the standard of reference. Such ratios can be easily con-
verted to absolute values when a standard has been established, and
moreover, the relative values can be used to the same purpose as ab-
solute values in the application of heats of combustion to the primary
idea which instigated the present work. The outcome of the present

work is thus that a gram of benzol yields at least , ' . , . = 2.5342

l.OoOi

times as much heat on combustion as a gram of sugar.

It is interesting to compare this result with the results of other

experimenters. On account of the relation which exists between the

weight of water and the weight of metal in the bomb-calorimetric

system, and the fact that at temperatures between 0°-30° the specific

heat of water decreases, while the specific heats of the metallic parts of

» Verhandl. d. d. pliysik. Ges., 5, 50 (1903) ; Ibid., 5, 353 (1903); Zeit. phys.
Chem., 53, 153 (1905).

690

PROCEEDINGS OF THE AMERICAN ACADEMY.

the calonmetnc system increase with rise in temperature, the water-
equivalent of the calorimetric system varies but slightly with change
in temperature. In fact, the roughly calculated water-equivalent of
our calorimetric system at 20° varied from its water-equivalent at 25°
by less than 0.03 per cent. The estimated water-equivalents used in
this comparison were, of course, not accurate, but the ratio between
them must be very close to the truth. On the assumption that the
relation between the weights of the water and the metallic parts in the
calorimetric system of other investigators did not differ much from
ours, it is evident that but little error will arise in comparing our re-
sults obtained at an average temperature of 21.4° with the results of
Stohmann and of Fischer at average temperatures of 17° and 15°
respectively.

The results of previous investigators, expressed both in gram-calories
and kilojoules, are tabulated below.

Results of Other Experimenters.

Cane-Sugar.

Benzol.

Calories per
Gram at Con-
stant Volume
and Pressure.

Kilojoules per
Gram at Con-
stant Volume
and Pressure
at 21°.

Calories per
Gram at Con-
stant Volume.

Kilojoules per
Gram at Con-
stant Volume
at 21'^.

Stohmann lo , .
Fischer and "Wrede "
Berthelot 12 . .

S955.2
3977.8
3961.7

16.533
16.627
16.560

9977
9949

41.704

• • •

41.587

Thus our ratio for the heats of combustion of benzol and sugar,
2.534, is about 0.3 per cent higher than 2.527, Stohmann's correspond-
ing ratio. It is interesting to note that had we used the value for
benzol obtained when the bomb was filled with air at the beginning,

our ratio would have been
same as Stohmann's.

2.655
1.0504

= 2.528, which is practically the

" Stohmann and Langbein, Jour. prak. Chem., 45, 313 (1892) ; 40, 77, 81
(1889) ; Stohmann, Rodatz, and Ilerzherp, ibid., 33, 103 (1886).

" Sitzb. Berl. Akad. d. Wisson, 19, 20, 21, 087 (1904). Value corrected for
error in calibration of bomb, vide, Zeit. phys. Chem., 53, 164 (1905).

" Berthelot and Vielle, Ann. Oliim. T'hys. (6), 10, 442 and 458 (1887).
Berthelot, Ann. Chim. Rhys. (5), 23 ,193 (1881).

mCHAIlDS. — HEATS OF COMBUSTION OF ORQANIC SUBSTANCES. 591

The very wide diflerence between the absolute heats of combustion
of sugar as given by Stohmann and Fischer makes a calculation of
the absolute value for benzol from the combination of our results with
either of theirs a somewhat uncertain matter. If Stohmann's value
for sugar be accepted, 41.89 kilojoules is computed as the heat of
combustion of a gram of benzol ; but if Fischer's be accepted, 42.13 kilo-
joules must be taken as the true value. No attempt will be made in
the present paper to decide this discrepancy, which is probably due
either to different standards of temperature or to different standards
of heat capacity in the two cases.

In conclusion, it is a pleasure to express our indebtedness to the
Rumford Fund of the American Academy of Arts and Sciences for
pecuniary support at the commencement of these experiments, and to
the Carnegie Institution of Washington for further assistance during
their continuation.

Summary.

1. The adiabatic method of calorimetry devised by Richards, Hen-
derson, and Forbes, as applied to the determination of heats of com-
bustion with the calorimetric bomb, was improved and thoroughly
tested.

2. The efficiency of this method in eliminating all corrections for
heat exchange with the surroundings, and for thermometric lag, was
established.

3. A new method was devised for burning an accurately weighed
quantity of a liquid in the calorimetric bomb, by sealing it in a thin
completely filled bulb, and exploding this by the combustion of a small
amount of sugar.

4. The effect of an inert gas, nitrogen, on the heat of combustion of
substances was noted for the first time.

5. In the calorimetric combustion of substances needing much
oxygen it was shown that the presence of nitrogen may involve a very
considerable error.

6. Benzol was found to evolve at least 2.534 times as much heat as
an equal weight of sugar on burning.

592

PROCEEDINGS OF THE AMERICAN ACADEMY.

<
H

I

<

1 ^

^^~

^^~

"■""

^^^"

^^^"

^^^"

^^^"

^

C3 t^ E?

C*"

^

a S <u bo

•^ m p^ S

o

o

(M

O

o

I-H

o

o

C<I

o

OJ

(M

o

o

o

* 9 ? -

c^o

>o

lO

lO

lO

»o

lO

to

IC

to

'^

to

lO

to

•-H 9 *" 9

(5 s 9 g

p

p

T-H

P

p

I-i

p

I-i

p

I-H

p

I-i

p

I— I

p

I-H

p

I-H

p

I-H

p

I-H

p

r-i

p

r~t

o

.5 CO
a. -r;

r^ ^

■£.a ^ .

CO

-rt<

o

00

r-

to

lO

I-H

o

CO

t^

o

t^

00

o

t-. 05 n 9

„t-

o

CO

CO

a>

o

CO

t~

CO

I-H

T-H

CO

CD

t~

OuO

p

p

p

p

I--

"#.

p

p

p

CO

p

r^

00

-*^ o

fci"3 9 ^

r-i

T— *

T-H

I-H

I-i

T-i

I-i

I-i

I-H

r-i

I-H

I-H

rH

I-H

>,=?

O H

» o

Qi li

Jci

•20"^

CO

CO

CO

CO

CO

-t<

(M

CO

to

•^

CO

CO

03

CO

*^ II

"5 2

gw a
>: fc, s

o

o

o

o

o

O

O

o

o

o

o

O

o

<+H ^^

O*^

o

o

o

o

o

o

o

o

o

o

o

o

o

o
1

o

1

d

d
1

9

d
1

c?

d

d
1

d
t

d
1

d
1

9

d

1

O O tH

1

1

1

1

i

1

1

1

1

1

1

1

1

1

Ch cj

rt 0

fl w

" ^

2 fl^:

iO

\0

CO

lO

iO

■*

to

■*

!N

-*

to

CO

■*

to

Si a

0 W

■5 g'S

tH

I-H

T-H

I-H

I-H

I-H

T— *

T— 1

I-H

I-H

T— 1

I-H

rH

§M §

oP

o

o

o

o

O

o

o

o

O

o

O

o

o

fc ^ §

O
1

o

1

d
1

1

d
1

d
1

d
1

d

1

d
1

d
1

d
1

d
1

d
1

d

1

-^

.. M

rmome-
Correc-
tion.

f-H

I-H

I-H

I-H

Q

00

I-H

rH

I-H

rH

i~^

I-H

o

I-H

.22 5:

o

o

O

o

o

o

o

O

o

o

o

O

o

o

oP

o

o

o

o

o

o

O

o

o

o

o

o

o

0 B

o

d

d

d

d

d

d

d

d

d

d

d

d

d

OS .

S t<

+

+

+

+

1

+

+

+

1

1

+

1

0 a

H-S

0 Sb
d <M

II <^

Observed
Rise in
Tempera-
ture.

o

I-H

to

lO

to

t^

I-I

t^

CO

lO

CD

•rH

'^

t—

Cl

.05

<M

05

o

I-H

t^

o

CO

■-1'

CO

CO

to

CO

o

II ^

lit

DO

I-H

p
r-i

p
I-H

p

I-H

p
I-i

I-i

p

r-i

p

r-l

p

rH

p

r-i

CO
T-H

p

T— 1

r-i

CO
r-i

'-' a

a o

^— V

a> 0

c>'-

«1

h5

o

t^

I-H

o

I-H

CO

rH

t-H

o

CO

CI

t^

CO

O

^n

.CO

I-H

CO

(M

'^

Oi

T-H

>o

CD

CO

to

c^

(M

t^

HH

I-H

CO

CO

o

CO

CO

p

«o

03

p

CO

p

o4

CO
(M

CO

(M

CO

00

03

CO
03

I-H 0

0

f^

P^

&«'

It

o

CO

o

I-H

<£>

o

O

^

CO

00

C3

CO

(M

CO

05

•^

o

CO

(M

(M

I-H

I-H

CO

tN

•f

IM

c—

'ti

t—

rH

°c^

Tfi

o

"^

CO

C5

o

■^

03

C<I

p

^

O

t-;

0

.2 t->

T-H

I-i

I-H

I-i

T-i

c^

c4

r-i

r^

I-H

r-i

I-H

l?i

r-^

0

*3 ^

d

t-H

OT

bp

O ,

lO

o

Ci

Iffl

I-H

lO

l-

t-

CO

(M

t—

CD

00

<M

:S S

mOO

t-

I-H

CM

T— 1

o

03

lO

00

o

i-H

CO

<M

CO

"S- bb

9®
1^

(N

o

I-H

OJ

l~

I-H

05

■^

-n

03

to

CO

00

.£f9

0)00

p

p

p

p

p

'^

p

p

I>;

p

p

t^

.—4

^

a

0

L. 1 ■

u

Kumbe
of Com
bustiou

..H

r-(

(M

t'3

■<*<

to

CO

t—

CO

a>

o

I-H

<M

oo

•^

tH

r-t

r-l

rH

rH

I-H

01

■♦H

■«-^ •

c 0

05

oi 0

p.

a

<1

<

<

M

M

w

n

M

M

M

O

o

O

o

0

RICHARDS. — HEATS OF COMBUSTION OF ORGANIC SUBSTANCES. 503

Rise in

Temp, per

grain

Benzol.

u-O

X>

CO

....^

i-H

^

CO

t-

1^

o

CO

CI

c^

a>

o

o

T-H

o

lO

'.Ti

l.O

i.O

o

CO

lO

lO

o

CO

CO

-^

-p

CO

«.o

CO

CO

c4

o

so

ci

CO

c4

o4

CO

CO
CJ

CO

CO

ci

CD

ci

CD

ci

CD

ci

CD

CD
CI

CD

c4

CO

ci

Per

Cent
N, in
Bomb.

^5

05

05

05

C5

c?

I-H

O
I-H

CD

CJs

OS

T-H
I-H

CO

I.S * .

1-H

XI

<N

Oi

to

o

i.O

r~

-t<

CO

t^

uo

O

m

r^i

1-H

CO

orrec

Rise

empe

ture

-^ =°

I^

-ti

o

■••o

00

CO

00

o

o

o

o

00

o

•^

T-H

t~

I— 1

p

c:

CO
r-t

I-H

T-H

o

T-H

T-H

T-H

CD

T-H

I-H

to

I— t

1-H

i—i

CO

r-H

I-H

O H

Tt<

CO

-+<

o

-t<

CO

li^

iC

•^

-H

CO

CO

CO

o

lO

r^

CO

o

o

o

o

o

o

o

o

O

o

o

o

o

o

o

^ =s^ a

oO

o

o

o

o

o

o

o

C_J

O

o

o

o

o

o

o

o

O
1

o

1

o

1

o
1

o

1

o

1

o

1

o

1.

o

1

o

1

o
t

o

1

o

1

o

1

o

1

o

1

o

1

« ° fl aj

O

i-O

CO

lO

00

'^

CO

o

-t

lO

CO

o

■^

T-H

LO

IC

kO

1— (

1-H

1-1

»— «

f-H

1-H

T-H

I-H

1-H

1—t

1-H

T-H

1-H

1-H

ti- - o 3
w = t^ u

oO

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

O Ot^ 3

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o-^ «

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

O O 1- "

o

lO

<M

<N

(M

(M

ro

-*

CO

M

t-

00

■*

eyt

»o

t^

uO

r>i

o

1-H

r-M

I-H

1-H

1-H

T— *

T— 1

1-H

1-H

,9.2m 3

o'N

(M

C^

CJ

CI

CI

CI

CI

CI

CI

CI

CI

CI

CI

CI

c^

O

o

O

o

o

o

o

o

o

o

o

o

o

o

o

o

o

os"^«

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

ermom-
eter
orrec-
tiou.

r-l

-+<

r-1

1-H

1-H

1-H

1-H

T-H

CO

CO

»— I

CI

1-H

1-H

•-H

I-H

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

!5

oO

o

o

o

o

o

o

o

(^

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

©

o

o

o

o

o

o

g "

+

1

1

1

1

1

1

+

1

1

1

1

1

1

+

1

m
a

1 = 2 .

uO

UO

CO

c^

CD

o

a

o

00

t~-

1-H

on

00

r~

CD

1-H

CD

^— g a,

Oi

I— f

c;

CI

Ot)

1-H

o

CI

CO

co

Ci

0!)

r~4

CO

r~

1-1

o

fe $e-5

0-*

CO

»-H

o

t-

00

CO

CXJ

t^

r~

CO

CD

CD

o

t^

1-H

I— 1

<M

<N

I-H

1-H

(M

I-H

1-H

I-H

I-H

I-H

I-H

T-H

1-H

CI

I-H

^h .

VO

CO

O

(M

CD

o

00

00

00

r^

o

CO

o

o

CD

nn

1-H

-ri

o

c:i

Oi

C5

CO

F— 1

o

CO

o

on

1-H

CD

I^

on

<~>

CD

.S S-5

0"*

(M

00

T-H

l^

00

00

o

CO

(Si

00

1-H

00

l^

UO

t~

CD

CO

Tt(

CO

■*

(N

CO

CO

CO

•^

-*

CO

■*

s^

cq

CO

CO

CO

Initial
Temper-
ature.

O

CO

r^

o

O

o

c;

00

o

o

C3

o

CI

C5

<->

r--

lO

lO

Ci

Ol

o

1-H

o

■1*1

OO

o

«^

00

CO

-fl

00

r-^

lO

lO

oci

ou

OJ

o

1-H

1-H

CO

CI

t^

o

o

CO

o

T-H

O

CO

CT>

'"'

(M

ri

(M

I-H

<N

I-H

I-H

CI

CO

cq

d

T-H

T-H

I-H

1-H

I-H

O

CO

o

05

Oi

o

I—

CO

(N

Hi

lO

(N

CO

'^

V-O

I-H

lO

d

*> C

.'-O

■^

t-H

r^

1-H

T— 1

-^

CI

1-H

r^

r^

CO

T— i

lO

CO

o

&,s

o

f— f

00

o

o

o

o

o

o

o

o

<r->

<~l

<->

<-)

o

CI

(>4

-M

CI

CI

CI

CI

CI

CI

CJ

CI

c<>

CI

CI

CI

CI

^'^

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

«)H

o .

o

•*

Ci

o

CO

^

>-0

(N

-rt<

00

CO

o

o

>o

(->

CO

CD

■s'^

^"^

o

f— <

CO

o

o

o

t^

00

irti

■^

-tl

f->

T-H

f^i

CO

CO

Sr-

o

03

o

-rft

o

C4

a

CI

o

Ot)

m

<-5

CO

-tl

(T)

o

bD-:t<

■^

t^

t^

o

uO

t-

lO

lO

CD

lO

lO

O

lO

CO

o

^«

O

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

°S2g

IM

CO

Tf<

lO

<o

t^

CO

C5

o

1-H

CJ

CO

-^

lO

CO

r~

00

^6^-B

i-l

t-(

»-H

I-H

rH

I-H

r-*

I-H

C4

CI

c^

(.N

CI

c«

C^

cq

CJ

1

Si

<

<i

<i

<!

n

P3

P5

M

M

«

M

<

<

t-H

<

K

<

Proceeding's of the American Academy of Arts and Sciences.
Vol. XLII. No. 22. — Makch, 1907.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL
LABORATORY, HARVARD COLLEGE.

OX TEE THOMSON EFFECT AND THE TEMPERA TUBE
COEFFICIENT OF THERMAL CONDUCTIVITY IN
SOFT IRON BETWEEN 115° AND 204° C

By Edavix H. Hall, L. L. Campbell, S. B. Serviss,
AND E. P. Chukchill.

IsvEsnoATioss ON Light and Heat made akd pcblished, ■wtiollt ob in paet, with Appbopbiatios

FEOM THE RUMFORD FOND.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD COLLEGE.

ON THE THOMSON EFFECT AND THE TEMPERATURE
COEFFICIENT OF THERMAL CONDUCTIVITY IN SOFT
IRON BETWEEN 115° AND 204° C.

By Edwin H. Hall, L. L. Campbell, S. B. Sebviss, and

E. P. Chckchill.1

Presented May 9, 1906. Received December 7, 1906.

Introduction and Summary of Results.

A PAPER printed in these Proceedings for May, 1905, by the authors
of the present paper gave the following results as obtained from the
study of a certain specimen ^ of soft iron :

Composition : iron, 99.93% ; carbon, 0.059%.

Density : about 7.785 at 0° C.

Thermal conductivity, k : 0.1528 at 28.2° C,

with a temperature coefficient 0.0003 (1) from 28° to 58°,
" " " " 0.0007 0) " 13° " 87°,

the latter value being the more reliable.
Electric resistance, absolute : 11365 at 0° C,

with a mean temperature coefficient 0.00519 from 0° to 100°.
" Thermo-electric height " with copper :

1028 X 10-8 volt at 26.6° C,
980 " " " 41.3° C,
936 " " " 54.5° C,

. 870 " " " 71.1° C,

'^ Mr. Churchill was not engaged in the earlier part of the work described in
this paper, but he worked with me during the greater part of July, 190(3, in a
supplementary investigation. — E. H. H.

^ It is proverbial that the various properties of any given metal, as set down
in plij'sical tables, are usually obtained from different specimens. It has seemed
to us worth while to study one particular kind of iron in as many of its different
aspects as practicable. The study is still in progress.

approximately

598 PKOCEEDINGS OF THE AMERICAN ACADEMY.

Thomson effect coefficient, v :

r — 757 X 10-^° mean, from IS*" to 90°,

approximately \ - 715 " " " " " 51°,

[ - 793 " " " 51° " 90°,

[a mean rise of — 2 X 10~^° per degree].

We have now to add for the same specimen of iron :
Temperature coefficient of thermal conductivity between 115° and
204° C, referred to the value of the conductivity at 115° = — 0.00068,
approximately. Electric resistance, absolute : 17260 at 100° and
26140 at 218.2°, with a mean temperature coefficient 0.00661 (on the
basis of the 0° value of the resistance) between 100° and 218°.

Thomson effect coefficient, v (— a- -^r T, where o- is the fraction of a
calorie absorbed per second in the Thomson effect by a current of 10
amperes flowing from a cross-section at temperature (T— ^) absolute
to a cross-section at temperature (T + h) absolute), from a combina-
tion of our new observations with our old ones, approximately (see
pp. 614, 615).

- (717 + 2 (T- 305)) X 10-^

from 32° C. to 182° C. (The rate of change of v here indicated would
make the tangent of the angle of inclination of the iron line on the
ordinary thermo-electric diagram about 40 per cent greater at 182° C.
than at 32° C.)

Battelli, who worked about twenty years ago with a specimen of iron
which he does not describe, except as to its shape and size, got values
from which we can deduce the approximate law

,-10

V = - (283 + 0.34 (T- 326)) X 10

from 53° C. to 308° C.

Lecher, who also in his recent paper fails to describe the quality
of the iron with which he worked, gets o- as — 278 X 10~', that is,
V — — 855 X 10~^°, at 52° C, and gives a formula which, when allow-
ance is made according to the data of B^de, for the change of specific
heat of iron with change of temperature, indicates a considerable
increase, about 12 per cent, in the numerical value of r between 50° and
130°, a nearly constant value from 130° to 160°, a slight numerical fall
between 160° and 180°, and an increasing rate of fall with further rise
of temperature.

It appears, then, that there is general agreement among those who
have worked directly on the Thomson effect in iron that the line for
this metal on the thermo-electric diagram should be one of increasing

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 599

steepness from 50° C. to tlie neighborhood of 130° C. ; though Lecher
is in disagreement with others as to the general change of inclination
of the line above this temperature.

It is noted that lead, in which the Thomson effect is undoubtedly very
small at certain temperatures, has apparently been carefully examined
only in the neighborhood of 50° C. (by Le Roux, by Haga, and by Bat-
telli) and 110° C. (by Battelli), and the question is raised whether it is
not desirable to examine copper, which is mechanically a much better
material to work with than lead, very carefully through the widest
practicable range of temperature, with a view to establishing a reference
line for the thermo-electric diagram.

Incidentally, it is observed that the thermal conductivity of calcined
oxide of magnesium, packed to a density of about 0.17 gram per cu. cm.,
is considerably less, perhaps 30 percent less, at 218° C. than at 100° C.

General Arrangement of Apparatus.

The general method followed in our recent work was the same as
that which was described in the paper already referred to ; but, as many
changes in detail were necessitated by working at a higher tempera-
ture, it seems desirable to show by means of diagrams the later form of
the apparatus.

Figure 1 shows a horizontal section through the middle at the level
of the two main iron bars, a and y8, each 1 cm. in diameter, which were
the subjects of the research. The pots are of cast iron, about 16.5 cm.
long, in the direction of the bars, 27 cm. wide, and 25 cm. deep.

Around the main bars are two " guard-rings " (see Figure 2, a verti-
cal cross-section of the apparatus), each consisting of twenty iron bars
about 0.6 cm. in diameter, the primary object of which is to lessen
lateral outflow of heat from the main bars. The outer guard-ring is a
new feature of the apparatus.

Behind the brass nuts n on the main bars are, first, washers of brass ;
next, washers of leather prepared for plumbers' use, to bear a rather
high temperature.3 Mica and a plumber's cement, consisting of silicate

' A trial which we now know to have been too short had persuaded us tliat
this prepared leather would withstand the action of hot naphthalin. When, after
a long course of experiments, the main apparatus here described was closely
examined, it appeared that the leather washers had been reduced to dust. But
the cement had apparently held, so that, so far as we know, there was no leakage
at the flanges of the main bars during the experiments on the Thomson effect,
though there was such leakage in experiments made later, in July, 1906. See
p. 619.

PROCEEDINGS OF THE AMERICAN ACADEMY.

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON, 601

of soda, graphite, and asbestos, with perhaps other ingredients, were
used for packing and insulation under the flanges of the main bars
and within the cylindrical apertures adjacent.

To prevent leakage at the ends of the numerous guard-ring bars we
depended solely on lead washers squeezed hard between the brass cap
nuts c and the walls of the pots ; and to lessen the danger of strain-
ing the apparatus and producing rupture of the joints around the main

Figure 2.

bars at the tightening of these nuts, we used on or in each guard-ring
bar just outside the walls of pots, nuts or iron pins, as Figure 1 shows.
Although in most cases the lead washers thus used were entirely satis-
factory, we shall see later that through one or two joints leakage finally
occurred.

K and K' are the junctions, 1 cm. apart, of a copper-German-silver
thermo-electric couple wound spirally in a groove made in the asphaltum
coating of the bar a, as shown in Figure 5 of our former paper, which rep-
resents a part of the surface of the bar laid out in a plane. L L', M ]\I',
N N', 0 0', and P P' are similar spirally placed couples. Each such

602 PROCEEDINGS OF THE AMERICAN ACADEMY.

couple is to indicate the gradient of temperature in its part of the bar
on which it lies. Cemented by asphaltum to the bar a, midway between
K and K' is a^, one junction of a copper-German-silver couple,, the other
junction of which is kept at a known temperature in a Crafts'* boiler
containing water or naphthalin, which apparatus is not shown in the
figure. The object of this couple is to indicate the mean temperature
of that part of a which lies between K and K'. The junctions a^, a^, a^,
tte, /3a, /3b, /3c, /3d, and (3^, have each a function similar to that of a^ ; for
each of them there is a corresponding junction in one or another of four
Crafts boilers. The bar Ge carries five copper- German-silver junctions,
6a, 6b, etc., and the bar Gie a like equipment, 16a, 16b, etc., correspond-
ing in position and function to the junctions a^, (3^, etc., already noted,
on the main bars. In every case the junction indicated in the figure is
connected with a mate, which can be kept at a definite temperature in
one of the Crafts boilers. Each junction attached to a guard-ring bar
is really lodged in a small hole drilled in the bar, insulation being
secured by means of thin-walled glass tubing, and fixity of position by
means of asphaltum varnish. Bars Gi and Gu, shown in Figure 2, are
similarly provided. We have, accordingly, on the main bars and the
guard-ring taken together, six a junctions, six b junctions, etc., each
set of six lying approximately, though by no means accurately, in one
cross-sectional plane. The effect of displacements from such a plane,
though for the most part eliminated in the end by the practice of
reversing the gradient of temperature in the apparatus, will require
notice in some cases.

In every case the distance from a to b, from b to c, etc., was intended
to be 4 cm. The distance from pot to pot was very nearly 21 cm.

The copper and German-silver wires, all about 0.02 cm. in diameter,
leading up from the various thermo-electric junctions which have been
described, were insulated, where insulation seemed necessary, by passing
them through short, thin-walled glass tubes. The wires from the main
bars ran almost straight up, as Figure 2 indicates, while those from the
guard-ring bars were made to follow the contour of the inner guard-ring
for a greater or less distance before leaving the packing with which the
guard-rings are surrounded. The wires from bar Gi, at the top, were
carried down to the bottom of the inner ring, as Figure 2 shows, and
then brought up on its outside. The object of these precautions was to
make sure that the gradient of temperature in the wires leading from

* See a paper On Thermo-electric Heterogeneitij in Certain AIloi/s, especial};/
German-Silver, by the autliors of the present paper, tliese Proceodiiiffs, March,
1900, for an account of tlie calibration of tiierrao-electric couples by use of the
Crafts apparatus.

HALL. — TIIEEMAL AND ELECTRICAL EFFECTS IN SOFT IRON. G03

any junction should be very small in the neighborhood of that junction.
All the wires, after leaving the packing surrounding the bars, ran nearly
straight upward to a wooden platform about 30 cm. above the outer
guard-ring. Here all the copper wires were connected with larger
copper wires leading off toward the du Bois and Rubens Panzer-
galvanometer with which all the thermo-electric currents were meas-
ured, while all the German-silver wires were continued to the Crafts
boilers, about 1 meter distant.

To obstruct the lateral flow of heat from the main bars outward, the
outer guard-ring was covered, except at the top, where the wires came
through, by a wrapping of magnesia and asbestos about 2.5 cm. thick,
and the space within was stuffed rather loosely with wisps or wads of
asbestos fibre. Concerning this packing something will be said later.

The space between the square pots was closed on both sides by thick
asbestos board, between which and the packing outside the outer guard-
ring there was at mid-level an interval about 2 cm. wide.

The space beneath the packed bars was walled in on all four sides by
similar asbestos board, which was intended to prevent, to a great degree,
circulation of air, and especially of hot gases from the large Bunsen-
burner flames used beneath the pots, from passing up past the bars.
The space above the bars, up to the wooden platform already mentioned,
was boxed in in the same way, though there were, before April 13,
two gaps near the top of this enclosure, through which escape of air
from the interior was facilitated, it being at first considered unsafe to
close in completely the space under the wooden platform.

Study of the Lateral Flow.

The first observations of this kind were made January 26-27, 1906.
Both pots contained water boiling at atmospheric pressure, and the
outer junctions of all the thermo-electric couples a, h, c, d, and e
connected with the main bars and the guard-ring bars were placed
in two of the Crafts boilers containing water boiling at atmospheric
pressure.

The time at which boiling began is not recorded in this case.
Observations to test the approach of the bars to a constant condition
of temperature began about G p. m., January 26, and were continued
about two hours, the indications being that a fairly stable condition
had been attained by 8 p. m. The boiling was continued, however,
till past midnight before any of the thermo-electric observations finally
used were made.

The final operations were substantially as follows, though not made
in the precise order here given : —

60i

PROCEEDINGS OF THE AMERICAN ACADEMY.

1. The couples 1„ 6„ 11,, and 16a, all the guard-ring couples belonging
to the cross-section a, were joined in series, and the current sent by
this combination through a known resistance was measured. This
made it possible to find the difference between the boiling-point of
water in the Crafts boilers and the mean temperature of the points a
on the guard-rings, and so to find this mean temperature itself

Similar observations were made with respect to the sections h, c, d,
and e of the guard-rings.

2. The couples a,, a^, (3^, /?„ on the main bars, joined in series, were
placed in opposition to the couples 1^, 6a, 11», and 16„ joined in series,
and the current sent by this combination through a known resistance
was measured. This gave the means of finding the excess of the mean
temperature of the points a and e on the main bars above the mean tem-
perature of the points a on the inner guard-ring.

Similar observations gave the means of finding the excess of the
mean temperature of the same points a and e on the main bars above
the mean temperature of the points e on the inner guard-ring.

Further observations of a like character gave the excess of the mean
temperature of the points b and d on the main bars above the mean tem-
perature of the points b and the points d, respectively, on the inner
guard-ring.

The excess of the mean temperature of the points c on the main
bars above the mean temperature of the points c on the inner guard-
ring was found in like manner.

3. The spiral couples K K', M M', N N', P P', on the main bars,
were joined in series, and the current sent by this combination through
a known resistance was measured. This made it possible to find the
mean gradient of temperature at the points a and e on the main bars.

From (1) and (2) above we get the following summary of temperatures
and temperature differences : —

Main bars.
Guard -ring,

Differences,

Mean a and e
Temperature.

100.28° 5
99.56°

0.72'

Mean b and d
Temperature.

Mean c
Temperature

100.07°

100.06°

98.55°

98.06°

1.52'

2.00'

Proceeding with these data, we find by a graphical method that the
difference between the mean temperature of the main bars between

•* The barometer read about 77 cm. corrected, makinj,' the temperature of
boiling water about 100.4° at the top of the pot, and perhaps 100.7° at the
level of the main bars.

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. COS

the cross- sections a and e, a distance of 16 cm., exceeds the mean
temperature of the inner guard-ring bars between the same two planes
approximately 1.48°.

The mean temperature gradient, leading toward the middle, at the
points a and e of the main bars was found, according to the evidence
of (3) above, to be approximately ().()(5G° per cm. The diameter
of each bar being 1 cm., and its thermal conductivity at 100° ap-
proximately 0.145, according to our observations of last year, we find
as the amount of heat led into each bar per second, by conduction past
a and e,

2 X T X 0.066 X 0.145 = 0.0150 calorie.
4

This is also, when a stable condition is reached, the amount of heat
lost from each bar per second by lateral flow from the parts between
a and e.

As the lateral outflow per second from each bar per 1 degree excess of
mean temperature of the bar above the mean temperature of the inner
guard -ring, all relating to the region between the cross-sections a and
e, we have, then,

0.0150 ^ 1.48 = 0.0101 calorie.

On February 8 and 9 the lateral flow was measured again, all the
pots in use now containing naphthalin boiling under atmospheric
pressure, which was about 77.3 cm. The boiling temperature of high-
grade naphthalin, such as was used in the Crafts boilers, is 218.8° at
this pressure. That of the very cheap variety, which was used in the
square pots at the ends of the bars, is not so well determined ; but
there was no need of an accurate knowledge of the temperature in
these pots.

Naphthalin was boiling in all of the pots about 7 P. M. on February 8,
and continued in that condition until after 6 a. m. of February 9, opera-
tions being continued through the night. The first thermo-electric ob-
servations recorded were made about 3 a. m., and the last about 6.20 a. m.
The following statement will give some indication of the degree of con-
stancy of temperature which was maintained during these observations.
Under Sensitiveness are given the galvanometer deflections produced by
a current of a certain constant strength used in determining the sensi-
tiveness of the instrument ; under Spirals, the deflections given by the
couples K K', M M', N N', P P', joined in series ; under M against G,
the deflections given by the main bar a's and e's joined in series, in
opposition to the guard-ring a's in series.

606

PROCEEDTNOS OF TTIE AJIERfCAN ACADEMY.

Time.

SenBitivenesa.

Spirals.

M against G.

2 : 55 A.M

13.18

. . •

3:15

. . .

19.85

. . .

3:45

. . .

. . .

12.98

5:53

. . .

. . .

13.44

6:10

. . .

20.35

. . .

6:25

13.08

. • •

It appears that both the mean gradient at the spirals and the mean
difterence of temperature between the main bars and the guard-ring
bars increased a few per cent during the course of the observations,
keeping pace with each other pretty closely in this change. This is a
sufficient approach to equilibrium for our purposes.

A summary of the results from the observations of February 9,
which were in a general way similar to those of January 26 and 27,
is given below. The c temperature of the main bars was found by
direct thermo-electric observation ; the other main bar temperatures
were estimated from this one by the use of data furnished by the
gradient measurements and the M against G measurements. The
guard-ring temperatures were found by means of the subtraction here
shown :

Mean a and e
Temperature.

Me.in b and d
Temperature.

Mean c
Temperature

Main bars .

. 216.0°

214.7°

214.2°

M-G. .

3.6°

6.5°

8.1°

Guard-ring

. 212.4°

208.2°

206.1°

Plotting an M-G curve, we get, as the excess of the mean tempera-
ture of the main bars, between the cross-sections a and e, over the
mean temperature of the corresponding part of the inner guard-ring,
6.32°.

Taking the thermal conductivity of iron to be 0.134 at 216°, an
estimate which is in accord with our measui-ements of the temperature
coefficient of thermal conductivity, we get, as the total How of heat
per second in each bar at the junctions a and e,

TT

2 X - X 0.403 X 0.134 = 0.848 calorie.
4

Accordingly we get, as the lateral outflow from each bar per second, in
the stable condition, per degree excess of mean temperature of the bar

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 607

above the mean temperature of the inner guard-ring, all relating to the
region between the cross-sections a and e,

0.0848 -r- S.32 = 0.0134 calorie.

The difference between this estimated outflow, per degree difference
of temperature in the neighborhood of 218° C, and the corresponding
outflow in the neighborhood of 100° C, 0.0184 and O.Olol, respect-
ively, is too large, apparently, to be readily attributed to mere errors
of measurement. On the other hand, one may well doubt whether the
coefficient of thermal conductivity of a packing of asbestos fibre really
increases by 33 per cent in the rise of temperature from 100° to 218°,
though we are unacquainted with any experiments upon this point
except our own. We have already stated that the fibre was loosely
packed, 1 gram, in, let us say, 15 cu. cm. It is easy to make the
density of such packing several times as great as this, and the ques-
tion has arisen whether there may not have been considerable currents
of air through our loosely placed fibre and whether the increase in
facility of lateral heat transmission with rise of temperature may not
have been due to the part played by such air currents. In this state
of doubt one naturally asks whether the coefficient of lateral outflow of
heat at either temperature is consistent with the results obtained by
previous experimenters on the thermal conductivity of fibrous materials.

Assuming that our lateral outflow is due to conduction proper, we
can make from our data a tolerable estimate of the coefficient of thermal
conductivity of the packing. Thus, examining Figure 2, we see that
no heat should flow across the vertical between Gi and Gn. Accord-
ingly, a gives heat to the half-ring Gi Gi6 Gn only. The length of
this arc, along the centres of the guard-ring bars, is approximately
7 TT cm., 22 cm. It is evident that a, with a given difference of tem-
perature between it and the guard-ring, sends less heat to this arc
than it would send to the same length of arc bent to a radius equal to
the distance, about 4 cm., from the centre of a to the centre of the
nearest guard-ring bar, Gie. On the other hand, it is evident that a
gives out more heat to the half-ring in the actual case than it would
give to the same half-ring, with the same difference of temperature, if
it were placed at the centre of curvature of the ring, the radius of which
is 7 cm. We can, therefore, make no very large mistake in assuming
that, for a given difference of temperature, the lateral outflow of heat
from a is equal to that which would occur between a and a guard-ring
arc 22 cm. long, having a radius of curvature equal to i (4-f- 7) cm.,
a being at the centre of curvature. A point of some doubt just here
is, how large a part of the circumference of a we should consider as

608 PROCEEDINGS OF THE AMERICAN ACADEMY.

giving off heat to the guard-ring in the imagined arrangement. This
part should evidently be more than half. A considerable variation in
this particular would make no great difference in the estimate of the
total outflow from a to the guard -ring. We shall make no serious
error if we assume that the outgiving arc of a is the same part of a
circumference as the receiving arc, 22 cm. bent to a radius of 5.5 cm.
As the radius of a is 0.5 cm., we take 2 cm. as the length of the
effective arc on a in the case imagined. In circular measure the
length of each arc is 1.27 tt.

In the case of steady flow, if q represents the number of calories
transmitted per second from 1 cm. length of a to the corresponding
1 cm. length of guard-ring, and if k stands for the thermal conductivity
of the packing, while T stands for temperature, we have for any ring
of radius r and width dr,

— k X 1.21 IT r -^ = q, or dT = — , ^ .. — .
dr ^ /; X 4 r

Integrating between limits we get

4 a; ri

At 100° for #1 — ^2 = 1 we have q = 0.0101 -M6 = 0.00063, whence
^100 = 0.00038.

At 218° for i^i — ^2 = 1 we have q = 0.0134 -M6 = 0.00084,
whence ^-ois = 0.00050.

Of course no great accuracy can be claimed for a result obtained by
so many rude approximations ; but it seems unlikely that these ap-
proximations have introduced an error so great as 25 per cent into the
estimated values of k.

If now we seek to compare these values of k for loosely packed asbes-
tos fibre with the values obtained by other investigators, we fail to iind
any information given in the 1905 edition of Landolt and BlirnKtein
concerning the thermal conductivity of this material. If we look at
the values of k given for other fibrous materials, we see figuring prom-
inently in tables of physical constants the values obtained many years
ago by Professor George Forbes for haircloth, cotton-wool (divided),
cotton-wool (pressed), flannel, and coarse linen. These values range
from 0.0000402 for haircloth to 0.0000298 for coarse linen. They at
first seem to make the values obtained above for asbestos packing
rather improbable and tend to strengthen the suspicion of consider-
able air currents through this packing. But the values found by
Forbes are, in all probability, decidedly too small, for they are consider-

HALL. — THERMAL AND ELECTRICAL EFFECTS EN SOFT IRON. G09

ably less than the fairly well-established value, about 0.00005, of the
thermal conductivity of " stagnant " air at ordinary temperatures.
Rubner^ found /; = 0.000098 for cotton-wool packed closely, about
1 gm. to 8 cu. cm., though he found smaller values for wool and silk.
Lees and Chorlton ^ found k = 0.00043 for asbestos-paper. They
give no description of this paper beyond its name and the thickness,
about 0.3 cm., of the layer composed of it. The mean temperature of
this layer was about 87°. The value 0.00043 lies between the two,
0.00038 and 0.00050, derived above for the effective k of our layer of
asbestos fibre ; but, as it is altogether likely that the asbestos-paper
of Lees and Chorlton made a much more dense layer than the one
which we used, and would therefore have a greater conductivity proper,
it seems probable that there was more or less convective movement of
air through the layer of fibre as we used it.

The coefficient of outflow through this layer at 100° was about L7
times as great as that found in our previous work with closely packed
cotton-wool at 100°.

In making allowances for the lateral outflow at temperatures inter-
mediate between 100° and 218° we assumed that the coefficient of
lateral flow, which may be defined as the fraction of a calm'ie lost per
second from unit length of a main bar per degree difference of tempera-
ture between main bar and guard-ring, increases at a uniform rate
with rise of temperature from 100° to 218°.

It is assumed, furthermore, that this coefficient is practically inde-
pendent of the gradient of temperature which exists in the bars and
iu the packing parallel to the length of the bars. This is equivalent
to the assumption that the various currents of heat through the pack-
ing, whether maintained by conduction proper or by convection, are
practically independent of each other. As the currents of air through
the packing must be comparatively slow, this assumption is not, per-
haps, a violent one, though the doubt attaching to it is sufficient, in
view of the large corrections Avhich must be made for lateral flow, to
make these corrections the least satisfactory part of our work. But
see p. 616.

Temperature Coefficient of Thermal Conductivity.

On February 7, and again during the night of March 2-3, 1906,
observations were made on the temperature coefficient of thermal con-

6 Archiv fur Hygiene, 24, 320 (1895).
T riiil. Mag., 5th Series, 41, 502 (189G).

VOL. XLH. 39

610 PROCEEDINGS OF THE AMERICAN ACADEMY.

ductivity in the main bars. During these observations there was no
electric current in these bars and the two were treated as one, in this
sense, that no attempt was made to determine the temperatures or
the gradients of temperature on the main bars singly, mean values
only being looked for. Accordingly, in what follows ta will indicate
the mean temperature of the two main bars in the cross-section a,
Qa will indicate the mean gradient of temperature of the two bars
at the same cross-section, etc. Similarly t'^ will indicate the mean
temperature of the guard-ring bars, 1, 6, 11, and 16, in the cross-
section a, etc.

The general method followed in this phase of the investigation was
to establish practically fixed conditions of temperature, by keeping
the boilers in action several hours before the beginning of observations
for record, and then proceed substantially as follows :

1. Data were taken from which the gradients of temperature g^ and
g, could be found.

2. Data were taken from which the difference between the tempera-
ture of the main bars and the temperature of the guard-ring bars
could be found for each of the five cross- sections, a, b, c, d, e. These
data were obtained, in ways already sufficiently indicated, by means of
the thermo-electric couples, a^, fi,„ Gu, G^^, Giu, Gi6,„ etc.

As the various junctions lying nominally in any given cross-section
do not strictly so lie, there is opportunity for very considerable errors
in the estimation of the temperature differences mentioned in (2) above.
It is possible to eliminate such errors almost wholly from the final re-
sult by making two complete sets of observations of the kinds indi-
cated in (1) and (2) above, one set with the a end of the apparatus,
the east end, the hotter and the other set with the e end, the west end,
the hotter. The first condition existed on February 7, and the second
condition on March 2 and 3.

The following table exhibits the main data obtained from the two
sets of observations. The temperatures, t, given for points on the
main bars, were in some cases estimated from data obtained at other
times ; but the possible inaccuracy of these values cannot be a source
of important error. The columns headed (f-f) give the excess of tem-
perature of points on the main bars over nominally corresponding
points on the guard-ring bars.

At the foot of each gradient column is given the difference of
gradient ; at the foot of each t column, the range of temperature ; at
the foot of each t-t' column, the mean value of the column.

The values in the last three columns, which are mean values taken
from the preceding columns, are used in finding the temperature co-

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 611

efficient of thermal conductivity. In what immediately follows the
subscript h will refer to the high temperature cross-section, which was
at one time a and another time e, while the subscript / will refer to the
low temperature section, which was at first e and later a.

We must now take account of the fact that a part of the excess of
gh over gi is due to the lateral escape of heat from the main bars be-
tween the h and the / cross-sections. From the data, given in the last
column of the table above a curve is plotted from which may be found
the difference of temperature of the main bars at any section between

February 7.

March 2 and 3.

Means.

a

Gra-
dient, g.

t.

t-t'.

Gra-
dient, g.

t.

t-f.

ae

Gra-
dient, g.

t.

I -I'.

5.°92

203.2

o

2.44

e

5.89

2(M.l

5°02

6.90-1-

20°3.7

o

3.73

h

. . .

179.4

3.44

d

. . .

179.8

5.10

bd

. . .

179.6

4.27

c

. . .

156.7

3.71

c

.

158.2

4.46

c

. . .

157.4

4.09

d

135.3

1.72

b

. . .

135.5

2.16

db

. . .

135.4

1.94

e

5.30

114.4

-0.32

a

5.22

114.8

-0.39

ea

5.26

114.4

-0.35

0.62

88.8

2.20

0.67

89.8

o

3.27

0.64+-

89.3

2.73-f-

h and /. Then, with the use of the data already given concerning
lateral flows, the amount of heat escaping laterally from each one of
the 16 linear centimeters of each bar between the k and / cross-sec-
tions is found. The total lateral outflow as thus found, from each bar,
is 0.0369, let us say 0.037, calorie per second. Taking first a tenta-
tive value of the thermal conductivity at f^, 203.7°, and replacing this
value later by one obtained by use of the data we are now dealing
with, proceeding, in other words, by a method of approximation, we
find that the gradient of temperature at t^ needed to carry through the
k cross-section this amount of heat is 0.346, or 0.35. This we must
subtract from gu in order to find just how much of the latter gradient
is necessary to transmit the amount of heat that passes through the
/ cross- section. But before this subtraction is made we raise the value
of gt, from 5.90-f-, to 5.91, in order to make due allowance for the
fact of expansion in the main bars. We thus get 5.91—0.35 = 5.56
as the value of g^, which is to be compared with 5.26, the value
of gi. Accordingly, if k stands for thermal conductivity, and if /

612 PROCEEDINGS OF THE AMERICAN ACADEMY.

stands for the temperature coefficient of this property between ti and
tn, we have

^•ft ^ (Jh = h X gi

and / = ^A^' ^^t^-t,)=(^f^-l^-r- {t, - O

= [^ -\\^{t„-t^= -0.00060+.
\9h J

As the value of this temperature coefficient is a matter of consider-
able interest, and as such coefficients are notoriously difficult to de-
termine, it seems worth while to inquire how much the two values
differ which are obtainable from the data of February 7 and the
data of March 2 and 3, taken separately and corrected, as well as pos-
sible, for the small displacements of the various junctions from their
nominal planes of cross-section.

Measurements, which were capable of no great accuracy, have indicated
that the junctions on the guard-ring bars are placed, on the average,
about 0.15 cm. farther toward the east end of the apparatus than the
con*esponding junctions on the main bars. This displacement, with
the gradient of temperature ordinarily prevailing in the bars, about 5.5,
would make a difference of about 0.15 X 5.5, or 0.83, degree. The values
of ^ — t', corrected accordingly, would be 2.20 + 0.83 = 3.03 for Feb-
ruary 7, and 3.27 — 0.83 = 2.44 for March 2 a,nd 3. The values of/
worked out from the two sets of data, as thus amended would be very
nearly —0.00047 and —0.00073 respectively.

The value of / found in our observations of last year on the same
bars of iron, between 13° and 87°, was —0.0007, the value of k at 13°
being the basis. The values of/ found in this paper are for the interval
from 115° to 204°, approximately, and the value of k at 115° is here
taken as the basis. If we use the value oik at 13° as our basis now,
we get approximately —0.00056, instead of —0.00060, as the value of/
between 115° and 204°. The work on thermal conductivity described
in the present paper is probably entitled to more confidence than that
described in our paper of last year, though the correction for lateral
flow was very much greater this year than last year.

On the whole, in view of the acknowledged difficulty of making any-
thing like an accurate determination of/ the general accord of all our
results in this phase of our work is reassuring.^

' See the Appendix to this paper for an account of further experiments on the
temperature coefficient of thermal conductivity in bars a and /3.

Jaeger and Disselliorst found (see Beib. zu den Ann. der Tliys. for 1901, p. 20)

hall. — thermal and electrical effects in soft iron. 613

Measurement of the Thomson Effect.

Our general method of procedure in getting data on the Thomson
effect itself, and our method of handling these data, were so fully set
forth in the paper ^ already mentioned that, inasmuch as we have made
no fundamental changes in these methods, we shall not describe them
in detail here ; but certain modifications may well be mentioned. In
the previous paper occurs the following sentence : " It will be ob-
served that such a day's work includes six complete cycles, or runs,
through all the pairs of corresponding couples from M P to K N and
back, three runs with the main current in condition F [cold to hot in
the front bar, ^], and three with this current in condition B [cold to
hot in the hack bar, a]." In the work described in the present paper
we have usually, though not always, made more cycles during a single
heating, as the following practically complete table shows :

Date. Cycles. Date. Cycles,

B F B F

January 31 (2 2} 4 March 2-3 U ^ 1 10

February 5-6 -^ 3 6 V 12 ^ (5

16-17

April 13-14 jo ^ |- li

18

17-18 \1 8 M7

The main data obtained from the experiments just indicated,
and from supplementary observations made at other times on the
temperature differences of the main bars, are exhibited in the
table on p. 608, in which

Aj =1 the difference of temp, gradient at low temp, spirals.
A,„ = " " " " " " middle "

A^ = " " " " " high

The + sign indicates that the steeper gradient is in the warmer bar,
and vice versa.

ti = the mean of the temperatures at the low temp, spirals.

" middle "
" '' «« " high " "

diff. " " " low

" middle "
" " high "

as the value of this coefficient —0.00065 in one bar of iron and —0.00014 in an-
other bar of iron, between 18° C. and 100° C.
• These Proceedings, May, 1905.

tm

- ■-

h

=

Tl

=

T.n

Tft

z=

614

PROCEEDINGS OF THE AMERICAN ACADEMY.

o

a

a

J; cc

05

0I

■*

a

r-t

CO
CO

« ti

a a

OQ "^

.—1

•^

<M

t-t

.

<M

CO

CO

CO

^

lO

lO

0

0

(M

?a

c^

(M

o»

iy>

•M

iM

H*

o(M

c*

C«

C<J

■=

0

0

0

Tt«

■*

■^

^

S

0 ""^

Tft

Tf»

■qi

t-

0

0

0

0

«o

?o

CO

CO

s

0 ^

rX

^

^

0

0

0

0

.

ff>

CD

C5

Ci

3

qI^O

CO

CO

CO

t-

^

0

0

0

0

0

0

0

h*

0^

-ra

:M

<N

0

0

0

0

(M

t~

<M

-*

0 CO

CO

CO

CO

0

0

0

0

(?<

(>*

0<J

04

0

t—

^

-*

<

0 rs

0

0

d

s

i^

CO

00

OO

r-t

r-t

T— t

r-H

0

t^

r-

CO

2

0 CO

00

00

CO

>o

lO

to

to

I-l

f— »

F-<

I—I

00

•*

I— 1

(M

'is

0 Iffl

CD

CD

0

^

CO

CO

CO

00

1—1

i-<

t— t

I— 1

■*

0

t^

CO

i^

0^

to

■^

-#■

1— 1

1— i

T-H

1— 1

r-l

rH

I— (

t-H

r-l

t^

0

■M

0

0

■*

to

1^

t^

I^

t--

<\

0

0

0

0

0
t

0
1

0

1

0

1

CO

vO

CO

05

00

CO

t^

t^

s

0

0

0

<j

0

0

0

0

0

0

d

0

+

+

+

+

0

•^

(M

5^

0

0

CD

CO

<

1^

t^

CO

CO

-1

0

0

0

0

0

0

0

0

+

+

+

+

t^

CO
1— t

0

t^

" s

0)

^

r-H

5r c3

rt

CO

vO

s s

0

rd

U

ss

O)

Pu

0

•-5

Ph

<

o

0

^ QC

OS

o'S

CO

0

OO

-r

..S:

I— 1

»-H

r-H

Tf

« 5

W. X

00

CO

o>

CO

•

<M

IM

<M

IM

^

to

to

tC

lO

(M

(N

(M

?^

r-H

1-H

-*

(M

«

o'M

^

(M

CI

0

0

0

0

t^

t--

CO

0

0^

■*

'T

T

t-

0

0

0

0

0

0

00

C5

s

otq

to

•*

-a*

0

0

0

0

.

i-H

1— 1

0

r-t

-2

0 ■^

■^

-*

Tfl

t-

0

0

0

0

CO

0

0

0

0

h"

o!M

IM

1-H

1-H

0

0

0

^

(M

0

(M

0

•_»

0 tO

'tf

^

-*

•K>

0

0

0

0

M

(N

C-J

(M

CO

00

0

0

-<

0 r-H

0

0

^^

s

CO

CO

00

00

1-H

1-H

r-t

r-t

■*

cs

C^

CO

2

00

0

0

C5

■^

0

to

0

0

T-H

1-H

T-H

1-H

t^

00

1*

to

s

0 CO

0

CO

CO

-vT^

CO

CO

00

CO

1-H

r-H

:-H

1— t

1-H

t^

-*

t-

I4

0 0

Tt*

Tl<

^

'^

1-H

1-H

1-H

r^

I-H

1-H

0

1-H

1-H

00

0

CO

(N

0

'-i

t~

0

t^

f-

0

0

0

0

0

0
1

0

1

0
1

?

Ci

00

CO

1-H

"*

-M

■^

•<*<

g

0

0

0

<

0

0

0

0

0

0

0

0

+

+

+

+

to

Ci

0

t^

to

0

CO

■rt<

.

CO

y3

CD

CD

<1

0

0

0

0

0

0

0

0

+

+

+

+

t—

CO

»-H

^

_^

^

^

00

" c

QJ

0

1-H

^ -5

0

T-H

13

d

h-H

<5

ft

<

2 3

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 615

ti,n = mean of temp's midway between the / and the m spirals.

± U (( (( (( (( K .„ U I ((

((

((

((

((

m

u

((

((

((

((

I

((

((

u

((

«

((

T,„, = diff. " " " " " I " m "

T„^ = " " " " " " m " h

A — strength of the main electric current in amperes.

In finding the "general mean" for each column except the last
each quantity in the column is taken with a weight proportional to
the number placed on its level in the last column.

The various ^'s and t's in this table were not all independently ob-
served. All those in the first part, East End Hot, are derived from
observations made February 5 to 7, with allowance for the change
which differences of barometric pressure would probably make in the
temperature of the main bars, the ends of which are in boiling water
or boiling naphthalin.

The ^'s and t's for February 16-17 and March 2-3 are derived from
observations made February 23-24. The ^'s and t's for April 13-14
are derived from observations made April 14, during the same heating
that gave the A's for these days.

In the derivation of the thermal conductivity values of iron which
are needed for use with the data given above, the temperature co-
efficient of this conductivity is taken as — 0.00U7 below 115°, and
as —0.0006 from this temperature up to 205°. We thus get approxi-
mately, hi being the conductivity at ti, etc. :

0.1436 0.1396 0.1355

The specific electric resistance of the iron, which also is needed in
the evaluation of the Thomson effect, was measured by Mr. Campbell
with the aid of the Crafts boilers, in the summer of 1905, and was
found to be 17,260 at 100° and 26,140 at 218.2°, with a mean temper-
ature coefficient 0.00661 (on the basis of the 0° value of the resist-
ance) between 100° and 218°.

In the following table q^ indicates the first approximation to the
" Thomson effect heat " ; that is, the difference between the amount
of heat generated per second by the electric current between the / and
the h cross-sections of either bar and the amount accounted for by
Joule's law between the same cross-sections, </' being calculated by the
formula (4), p. 25, of our previous paper.^^ The value ^", the second
approximation to the quantity desired, obtained from q^ by taking
account of the difference of thermal conductivity due to the slight excess

" These Proceedings, May, 1905.

616

PROCEEDINGS OF THE AMERICAN ACADEMY.

of temperature of one main bar over that of the other, differs so little
from q^ that it is not given in the table. Under q is given the final
value of the Thomson effect heat, obtained from ^" by taking account
of the amount of heat which, between the / and the h cross-sections,
escapes by lateral flow from the warmer bar in excess of that which
escapes in the same way from the cooler bar. This correction, which
is large, usually about 23 per cent of the value of q, will be discussed

A

at some length later. Under o- is given q^ —{th — t^ ; that is, the

mean Thomson effect heat per electromagnetic unit of current per
degree of the range of temperature considered. Under v is given
cr -7- (273 -{■ \{ti\ h)), which may be called the mean Thomson effect
coefficient between ti and t;, :

Date.

th-tf

q'XW^

9X10'.

o-xlO'.

vXlO'".

wt.
4

General Mean
I'XIO'".

Jan. 31

88.8

799

1028

-459

-1064

East

end

Feb 5-7

88.7

801

1029

-459

-1061

12

I -1045

hot

Ap. 17-18

88.5

706

996

444

-1029

17

1-1019

Feb. 16-17

90.1

745

985

-433

-999

16

^

West

end

Mar. 2-3

89.9

704

945

-417

-964

10

I -993^

hot

Apr. 13-14

89.8

755

986

-434

-1004

18

The difference, about 5 per cent, between i'e, the value of v obtained
with the east end the hotter, and v^, the value obtained with the west
end the hotter, as shown in the table just given, has been the subject
of a great deal of cogitation, and a thoroughly satisfactory explanation
of it has not been found. It is unlikely that the whole difference was
purely accidental in the sense that it would have disappeared in a pi-o-
longed continuation of the experiments ; for the smallest I'p. is larger
than the largest v^. It is true that fi and 4 were determined only
once with the east end the hotter, which will now be called the state E ;
and, moreover, the conditions during this determination were not of the
best, so that it may well be doubted whether the true value of h — ti
was any greater with state E ^^ than with state W. If we assume that
the two values were the same, the difference between the mean v^ and

1^ A redetermination of tliis quantity for condition E after tlic observations
of April 17-18 was prevented by a partial breaking down of the apparatus, which
mishap will be described later.

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 617

the mean Vw will be reduced to about 3.7 per cent ; but even then the
smallest Vp will be somewhat larger than the largest Vw

There is one other important datum, namely, the mean difference
of temperature between the main bars, which was measured at only one
heating in condition E, namely during February 5-7. This mean value,
found from the observed values at the five cross-sections a, b, c, d, e,
by plotting a curve, was 0.389°, or 0.39°. An error of about 20
per cent in this rather small quantity would account for the whole
difference between the Vg and the iv as found. That an error approach-
ing this magnitude was made here is shown to be improbable by the
fact that the two determinations of the main bar mean differences of
temperature made with condition W gave 0.408°, or 0.41°, and 0.391°,
or 0.39°, respectively.

Other possibilities which have been considered in the endeavor to
account for the difference in question are the following :

1. A partial short circuit of the main electric current in the west
pot when this contained naphthalin. There is no good reason for sus-
pecting such an action. A test made on April 18, with boiling water
in the west pot and boiling naphthalin in the east pot, showed that
there was no serious leakage of electricity through either liquid.

2. Difference in the sensitiveness of the thermo-electric spirals on
the main bars.

A difference of two or three per cent, perhaps more, in the sensitive-
ness of these spirals is possible. But the observations with these
spirals are taken and are combined in such ways that the result ob-
tained from a complete set of data for condition E or condition W is
dependent on the mean sensitiveness rather than on the differences
of sensitiveness of these spirals. We could account for the difference
between I'p. and v^ by means of variation in these spirals, if we should
assume that the two a spirals, at the east end of the bars, are about
seven per cent more sensitive at 204° and seven per cent less sensitive
at 115° than the corresponding two e spirals at the west end of the bars.
This is very improbable.

3. Dissymmetry in the shape of the bars or in the placing of the
spirals upon them.

There is none that can account for the difference which we are con-
sidering. The bars were ground to 1 cm. diameter by Brown and
Sharpe. The spirals are probably not all of exactly the same length,
and there may be slight inaccuracies in their emplacement ; but these
imperfections, though they might affect slightly the value of v, would
have little or no tendency to make a difference between iv. and iv.

4. Difference in the movements of air within the loose asbestos fibre

618 PROCEEDINGS OF THE AMERICAN ACADEMY.

surrounding the bars, consequent upon a reversal of the gradient of
temperature in the apparatus.

Already, in connection with the discussion of loss of heat by lateral
outflow, the question has been raised whether this loss is merely, or
practically, a function of lateral differences of temperature. If we had
to do here with a true conduction only, there would be little risk in
answering this question in the affirmative ; but when convection, accom-
panying rather general movements of the air within the packing, comes
into play, as it probably does to some extent, the problem becomes more
difficult. But it is not easy to find any plausible reason why this
longitudinal temperature gradient should be less eff"ective in carrying
off" heat from the warmer bar in condition E than in condition W. It
is true, that a leakage of naphthalin vapor into the packing space while
condition E prevailed might reduce the effectiveness of the convection
movements by replacing air by a more sluggish medium ; but in the
one case in which such leakage was known to occur, the value obtained
for ve was smaller than usual, indicating, if anything concerning lateral
loss, that such loss was greater on this occasion than usual. The gen-
eral matter of lateral loss will be discussed once more later in this paper.
It is the most troublesome part of our experimental problem, and it
may be that some inequality of packing of the asbestos fibre is at the
bottom of the discrepancy which we are now discussing.

5. Change of quality from one end to the other of the main bars.

Both bars were made fi-om pieces taken from the interior of a very
soft bar some 10 cm. in diameter, and any diff"erence of composition or
physical state sufficient to make such a diff"erence in the Thomson
eff"ect with reversal of temperature gradient is very improbable. It is,
perhaps, worth noting that in our work of the year 1905 with these
same bars, and with the same spirals upon them, what corresponds to
our Vg of 1906 was, apparently, about two per cent greater than what
corresponds to our v^ of 1906; that is, in both 1905 and 1906 the
data obtained with the marked ends (bar a is stamped with a 1 and
bar ^ with a ^ on one end) of the bars the hotter have indicated a
slightly greater value of the Thomson eff"ect. This is probably an acci-
dental coincidence.

This long search for an explanation of the discrepancy in question,
though it has not been decisive, has served the useful purpose of
passing in review a number of possible sources of error. A difference
of five per cent in the values of i'k and iv is of no great consequence,
if we can feel reasonably sure that the mean of the two is not more
than two or three per cent different from the true value of v.

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 619

It must be confessed that this assurance is a little difficult to hold.
The close scrutiny which we have given to the matter of lateral flow
has left a rather troublesome doubt as to the soundness of our working
assumption that this flow is not to any important extent a function of
the longitudinal gradient of temperature. Upon this point we must
bring to bear whatever further evidence is available.

A satisfactory mode of investigation, if it were not so extremely
laborious, would be to repeat the determination of v wnth other kinds
or states of packing than those here used. Something like this varia-
tion of conditions we find in a comparison of our 1905 work with
that of 1906, or in the former cotton- wool, closely packed in, was
used instead of the rather loosely packed asbestos of 1906, and it has
already been stated that the coefficient of lateral outflow, at 100",
per degree difference of temperature between the main bars and the
guard-ring bars, was about 1.7 times as great with the asbestos as
with the cotton. If we have made any large error in using the as-
sumption now on trial, we should expect a marked discordance be-
tween the results obtained from the older and the more recent work.
But as the two do not cover the same temperature, one lying between
13° and 90°, while the other lies between 115° and 204°, how can we,
without begging the main question which this research deals with, tell
what is accordance and what is discordance 1

In this difficulty we get some help from the fact that in each case
we have taken note of the diff"erence of gradient at the middle cross-
section, c, of the main bars, so that it is possible to make from the
data of each year's research an estimate of the rate of change of v with
change of temperature, which estimate should not be greatly affected
by error in regard to the absolute magnitude of the loss by lateral
flow. These estimates are :

From Data of Range of Temperature. '^"ilUe'of Temp^^^ ^®'''°*

1905 32° to 71° -2.0 X 10"^° i_i q x 10-1°

1906 137° to 182° -1.6 X 10"" J

If now, taking —1.8 X 10"^° as the rate of change of v from the mean
temperature, about 53°, of the 1905 work to the mean temperature,
about 159°, of the 1906 work, we reckon from the value of v at 53°
what its value at 159° should be, we get

-757 X 10-^^ -(159-53) 1.8 X 10"^° = -948 X 10-^°.

The value found from the data of 1906 is, as we have seen at page 610,
— 1019 X 10"^", about 7 per cent larger than the value as estimated

620 PROCEEDINGS OF THE AMERICAN ACADEMY.

above. As an overestimate of the loss of heat by lateral flow would
tend to an increase of the numerical value of v, the test here applied,
if it can be called a test, would seem to indicate that too great rather
than too small a correction had been applied for lateral flow in getting
the value —1019 X 10"^° for v. Reducing the applied correction by
one third of itself would reduce v at 159° from— 1019 X 10~^° to
something very near —948 X lO"^''.

Further, and perhaps stronger, evidence tending to the same eff"ect,
that too large an allowance has been made for lateral flow in the work
of 1906 thus far described, is now at hand. During July, 1906, a re-
measurement of the temperature coefficient of thermal conductivity of
bars a and /3 was made^^ with calcined oxide of magnesium as a pack-
ing, through which very little, if any, convection of heat could occur.
The resulting value of this coefficient was— 0.00076, whereas the
value found when the asbestos fibre was used as a packing was

— 0.00060. An overestimate of the allowance for lateral flow tends to
give too small a numerical value for this coefficient. Reducing the
applied correction, in the case of asbestos fibre, by one fifth of itself
would raise the value found for the coefficient from — 0.00060 to

— 0.00074, which is very close to the value found with use of oxide of
magnesium as a packing.

Circumstantial evidence, then, favors the opinion that the allowance
which we have made for loss by lateral flow through asbestos fibre
packing should be reduced about one fourth part of itself. Perhaps
the best we can do under the circumstances is to combine the various
estimates of the rate of change of v with rise of temperature as follows :

Increase of v
per 1"^ Rise.

From values of v at 32*' and 71° . . . -2.00 X lO"^"^

(1905)
From values of v at 137° and 182° . . -1.55 X 10""^ -2.0 X 10""

(1906)
From values of v at 52° and 159° . . -2.45 X lO-i*^]

(1905 and 1906)

Applying this rate of change to — 757 X 10"^", the value of v at
52°, as found in 1905, we get, as the value of v at 157°, — 971 X lO'^^.
This value is about 5 per cent less than — 1019 X 10~^*^, the value
at 159° as found from the measurements of 1906 taken alone. This
discrepancy is somewhat disappointing, and it must be admitted that
our values of v may be several per cent in error at any temperature.

" By Mr. E. P. Churchill and myself. See the Appendix to this paper. —
E. II. H.

Mean.

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 621

On the other hand, it seems to be well established that the numerical
value of V increases at a rate not very different from that indicated
above, 2.0 X l()~^°per degree, in the region between 32° and 182°. As
V is proportional to the tangent of the angle of inclination of the iron
line from the horizontal line on the thermo-electric diagram, the state-
ment just made means that in the temperature region considered the
iron line should be one of increasing steepness with rise of tempera-
ture. Taking the value of v

at 32° as - (757 — 20 X 2) X lO"^" = — 71 7 X lO'^^
and at 182° as —(757 + 130 X 2) X 10"" = — 1017 X 10-'^

we find that the tangent of the angle of inclination of the iron line
should be about 40 per cent greater at 182° than at 32°.

In our previous paper ^^ it was pointed out that Battelli's observa-
tions on iron gave data which yield the following values for v :

-283 X 10-1*' at 53° C. -331 X lO"^" at 243° C.

-319 " " 108° -369 " " 308°

The mean rate of increase of r here indicated would make the value at
182° about 18 per cent greater numerically than the value at 32°.

Battelli's general method was to surround a certain length of each of
two similar bars of one metal by a narrow trough containing mercury,
separated fi-om the bar by a layer of varnish or other insulating
material, establish a gradient of temperature in the bars by means of
ice and boiling liquids, pass a strong electric current up the gradient
in one bar and down in the other, then estimate the Thomson effect
from the difference in the rate of heating of the two baths of mercury.
He does not give sufficient details to assure us that he took adequate
account of the tendency of the mercury, which was continually stirred,
to reduce the gradient of temperature, and so the Thomson effect, in
the part of the bar which it surrounded. Whether the low numerical
value which Battelli found for the Thomson effect in iron, as com-
pared with that found by us or very recently by Lecher, 1* is due
to this peculiarity of his method or to his having used a very different
kind of iron from that which we have used, is uncertain, but it is quite
possible that his relative values of v at different temperatures were
approximately correct ; and the per cent rate of change which his data
give for v \vith rise of temperature, though less than that which we
find, is large enough to establish a strong presumption in favor of
representing iron on the thermo-electric diagram by a line of con-
is These Proceedings, 41, 36 (1905).
" Annalen der Pliysik, 4, 19, 859 (1906).

622 PROCEEDINGS OF THE AMERICAN ACADEMY.

stautly increasing steepness from the region of 50° to the region
of 300°.

On the other hand, the work of Lecher, to which reference has
already been made, gives at 52° the value —855 X 10"^** for v in iron,
a quantity about 13 per cent greater than our value of v at the same
temperature. As to the change of v with rise of temperature, Lecher's
data seem to indicate, when account is taken of the change of specific
heat of iron with change of temperature, a considerable increase, about
12 per cent, in the numerical value of v from 50° to 130° ; a nearly con-
stant value from 130° to 160°, a slight numerical fall between 160° and
180°, and an increasing rate of fall with further rise of temperature.
Indeed, according to the curve by means of which Lecher gives his
results for iron, even the quantity o-, that is, vT, begins to diminish
numerically with increase of T in the neighborhood of 210° C, and
goes on diminishing more and more rapidly to the upper temperature
limit of the observations, 441° C, where the value of v is scarcely more
than one sixth as large as the v at 210° C.

The method of Lecher, though very different from that of Battelli,
resembled it in this particular, that both were calorimetric ; that is,
neither method depended on the establishment of constant conditions,
but each made use of a rate of change of temperature of a quantity of
metal. Battelli noted the heating effect in mercury, and he ob-
served the change of temperature during a 30-miuute run of the
electric current. Lecher noted the rise of temperature in the iron it-
self during a 30-second run of the current. In getting the curve for
iron, to which reference is made above, he seems to have ignored the
change of specific heat of iron with change of temperature, though he
observes that a correction might be made on account of this change, and
apparently refrains from making it on the ground that " the data con-
cerning the specific heat of iron are very uncertain." The common be-
lief appears to be that this quantity increases rather rapidly with rise
of temperature, and if account were taken of this change, the course of
Lecher's curve for iron and the inferences drawn from it would be
seriously affected. Lecher himself recognizes other sources of possible
error in his work, and it may well be doubted whether the evidence
which he presents entirely offsets the force of Battelli 's data, which, as
we have already seen, tend to the conclusion that not only vT but
V continues to increase with rise of temperature up to at least the
neighborhood of 300° C. It must be admitted that the true course
of the iron line, above 200° C, on the thermo-electric diagram is
uncertain.

In the case of copper and in the case of silver Lecher does make an

HALL. — THERMAL AND ELECTRICAL EFFECT IN SOFT IRON. 623

allowance for the change of specific heat with change of temperature.
He gets with the unit current (10 amperes), in copper, —

o- = +(3.01 + 0.00662 t) 10-',
and in silver, —

o- = +(7.363 + 0.00887 t) 10"^

t being the temperature on the ordinary Centigrade scale. From
these equations we get for copper, —

. = .H-2-=+(l^ + C6.2)lO-»,
and for silver, —

_+(^i5«0 + 88.,),o-...

Each of these equations indicates a falling value of v with rise of tem-
perature. Each indicates for the ordinary thermo-electric diagram a
line rising from left to right, with constantly though slowly diminishing
steepness. Lecher himself would probably not claim that his observa-
tions are sufficiently accurate to establish as a fact the change of cur-
vature of these representative lines. They do, however, make it appear
probable that the lines for copper and silver should be drawn nearly
straight through a great range of temperature on the thermo-electric
diagram, and they suggest these metals as good subjects for further
and more careful study. For the very difficulty which every one of
experience in the matter finds in the measurement of the Thomson
effect in any metal impresses upon us the desirability of establishing
some one line on the thermo-electric diagram so accurately that others
can be satisfactorily determined from it by "thermo-electric height"
measurements, without further recourse to direct observations of the
Thomson effect.

To be sure, the lead line, taken as horizontal, has been used in this
way, and it may be asked whether it is not still sufficient for the purpose
indicated. All observers, so far as we know, agree in declaring the
Thomson effect in lead to be very small. Le Roux,^^ who rated this
effect in iron as 31 and in copper as 2, found it sensiblement mil in
lead. At or near 50° C, Haga^^ found the effect in "pure" lead to

" Ann. de Cliimie et de Ph\-sique, 4"'"' serie, t. X, 18G7, p. 201. Le Roux does
not, we believe, describe the quality of the lead which he used.

^8 Ann. de TEcole Poly technique de Delft, t. Ill, 1887, p. 51. Analysis showed
the lead useil by Ilaga to contain, "beside a trace of silver, 0.09.3 per cent of anti-
mony, 0.004 per cent of iron, and 0.013 per cent of zinc." It is easy to get much
purer lead now.

624 PROCEEDINGS OF THE AMERICAN ACADEMY.

be negative, as in iron, but tresfaihle compared with that in platinum.
Battelli,^'' stimulated by the fact that Haga had found a Thomson
effect in lead, undertook to measure this effect. He found it 2Msitive,
and gives data from which we get, —

V at 53.0° C. = 4.37 X lO"'",

V " 108.4° C. = 4.29 X " .

Below 50° C. and above 110° C. we have, apparently, no direct
experimental evidence concerning the magnitude of the Thomson
effect in lead, and between these two temperatures we are, finding
Haga on one side and Battelli on the other, in doubt as to the sign
of this effect in the purest lead. It seems probable that the lead line
on the thermo-electric diagram should be very nearly horizontal below
50° and above 110° ; but it can hardly be said that we have a satis-
factory assurance in regard to this fundamental matter. Accordingly
it seems desirable to study very carefully through a rather wide range
of temperature the Thomson effect in some metal which is easily
obtained in a state of great purity. Lead is such a metal, but it is
mechanically difficult to work with, especially at moderately high
temperatures. Copper seems to be, on the whole, a better material for
the most careful direct examination, with a view to the establishment
of a reference line on the thermo-electric diagram.

Appendix.

The doubt concerning the amount and character of the lateral escape
of heat through the loose asbestos fibre packing was so great that two
of us^^ undertook in July, 1906, further experiments bearing on this
question. By means of a rough test with a small apparatus we satis-
fied ourselves that closely packed asbestos would not make a satisfactory
wrapping, as the flow of heat through it appeared to be even greater
than through the loosely packed asbestos which we had used. Ac-
cordingly we looked for other materials capable of bearing a tempera-
ture of 218° without injury, which might serve better. Magnesium
carbonate, which is used commercially as a bad conductor of heat, was
found to lose much weight, doubtless from the giving up of water of
composition, at 218° and to regain weight when exposed to the air
at ordinary temperature. This, therefore, was rejected. The oxide of

" Atti della Reale Accadeniia dei Lincei, serie 4, t. 3, 1887, p. 61. Battelli
does not give tlie analysis of the lead, but states that its density at 0° C. was
11.344.

18 Mr. Churcliill and myself. — E. H. 11.

HALL. — THERMAL AND ELECTRICAL EFFECTS IN SOFT IRON. 625

magnesium, " light calcined magnesia," on the other hand, was found
to bear the heating test well, losing at first a small amount of weight, in
drying, probably, but remaining constant in weight at high temperature
therealter.

Accordingly we undertook to repack our Thomson effect apparatus,
using now the dried magnesium oxide, and to repeat the experiments
on lateral flow through the packing as well as those on the temperature
coeflicient of the thermal conductivity of iron.

As we had a strong apprehension that our boilers would now leak vapor
of water or of naphthalin into the packing space, though we had done
what we could to stop such leaks as we had discovered, and as we feared
that any condensation of vapor in the powdery oxide would be highly
objectionable, we put a sort of buffer of asbestos fibre about 0.5 cm.
thick against the boiler at each end of the space to be packed, trust-
ing that the upward movement of air through this layer would carry
off vapor coming into it. Then, after putting in place the wrapping of
magnesia and asbestos which lies outside the outer guard-ring (see
Figure 8), we poured the magnesium oxide down into the space between
the many bars, striving, by tapping the outer covering and by pressing
down the oxide with strips of metal, to get the light powder so well
packed that it would not by subsequent settling leave empty spaces
under the bars. The density of the powder as thus placed was about
0.17 gram per cubic centimeter.

After this we made, in spite of a considerable amount of leakage of
naphthalin, especially toward the last, observations which resulted as
follows :

Lateral outflow from each main bar per 1° difference of temperatu)-e
between the main bars and the inner guard-7-ing,

0.00791 cal. with both pots at 100°, July 17-18
0.00894 " " " " " " " 27

0.00843 "

0.00579 "

((

((

((

" 218°,

((

21-22

o.oor.r,5 "

«

u

((

(( «

((

28

U.00G22 "

Temperature coefficient of thermal conductivity in iron between 115°
anc? 204°, with reference to the value at 115°,

f = - 0.00076, July 19 and 24.

It is to be noted that in this packing the thermal conductivity
appears to be about 30 per cent greater at 218° than at lOO"".

VOL. XLII. 40

626 PROCEEDINGS OF THE AMERICAN ACADEMY.

No great confidence should be placed in the numerical accuracy
of this indication, but the direction of the change seems to be well
established.

The cause of the apparent increase in conductivity of the packing,
both at 100° and at 218°, with lapse of time is not known.

The value here found for f, combined with that found for the same
coefiicient when asbestos packing was used, gives as a mean
f = - ^ (0.00076 + 0.00060) = - 0.00068.

Proceedings of the American Academy of Arts and Sciences.

Vol. XLII. No. 23. — Makcu, 1907.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE.
E. L. MARK, DIRECTOR. — No. 187.

AN ELECTRIC WAX-CUTTER FOR U/SE IN
RECONSTR UCTIONS.

By E. L. Mark.

CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE.
E. L. MARK, DIRECTOR. — No. 187.

AN ELECTRIC WAX-CUTTER FOR USE IN
RECONSTRUCTIONS.

By E. L. Makk.

Presented December 12, 1906. Received December 17, 1906.

Any one ■who has had much experience in making models of micro-
scopic objects by means of wax reconstruction-plates must have felt
the disadvantages of the ordinary method of cutting out the plates with
a scalpel.

Some years ago the advantages of heating the scalpel in a flame
suggested to me the desirability of employing a knife heated to a
constant temperature, and observation of the methods employed in
making corrections to " line process " plates prepared by the so-called
wax method led me to think it might be possible to use for this pur-
pose a small gas jet attached to the knife and connected with the gas
supply by a small flexible rubber tube. I did not succeed, however, in
producing a device that would work satisfactorily. A little later it
occurred to me that a wire heated by an electric current might be kept
at a sufficiently constant temperature to answer the purpose. Accord-
ingly in an ordinary bow-saw with large bow the saw blade was re-
placed by a fine wire, the ends of which were insulated from the frame
and connected by means of flexible insulating wire with a 110-volt
alternating electric circuit. By introducing into the circuit the proper
resistance — in the form of electric lamps arranged in multiple — it
was possible to heat to the proper degree the wire selected. By means
of this apparatus one could melt a wax plate readily along any pre-
determined course, provided the wire were slowly moved back and
forth as in sawing. But this apparatus was defective, owing to the
lengthening of the wire and its consequent laxness when heated. It
became obvious at once that for accurate work some sort of spring
would have to be introduced into the mechanism to take up the slack of

G30 PROCEEDINGS OF THE AMERICAN ACADEMY.

the wire. But a still more serious and unexpected drawback presented
itself. Unless the cutting was done very slowly, the melted wax cooled
in the saw-carf behind the wire, leaving the edges of the cut almost as
firmly joined as before the wire had passed through. This, together
with the difficulty of holding conveniently the wax plate during the
process of cutting, led to the adoption of a fundamental modification.
Instead of holding the wax plate in such a position that the wire-saw
could be moved freely, it seemed that a better plan would be to move
the wax plate on a horizontal platform against a wire fixed in a verti-
cal position. Some preliminary trials were made with such a device,
but it soon became evident that the wire would have to be made white
hot if the track through the wax plate were to be made with satis-
factory rapidity. The disadvantages of this were obvious ; among
others, the wire became dangerously lax, and the desired rigidity could
not be maintained. The remedy which at once suggested itself, and
proved in the end to be practicable, was to give the wire, while keeping
it taut by means of a spring, a vertical play of an inch or two, as in
a jig-saw. By this means the w^ire surface brought in contact with the
wax was multiplied many times, and a sheet of wax that quickly
cooled down a stationary wire at the level of contact was easily melted
by the moving wire.

A domestic experience in the exchange of sewing machines had
acquainted me with the fact that an abandoned — but not worn out —
sewing machine was worth about what it would fetch for old iron. I
selected one of fairly large proportions, and proceeded to replace the
needle with the electrically heated wire. It was at this juncture that
the mechanical skill and experience of one of my students — Mr. J. A.
Long — proved to be of great value. We together planned the details
of the alterations to be made, and he executed the most of them, no
professional mechanic being required at any time. The obstacle
which it took us longest to overcome was the freezing of the wax in
the track of the wire. I at first thought it would be necessary to
use a jet of hot air to blow the melted wax away, but found on trial
that a cold blast was even better, so far as getting the wax out of
the saw-carf was concerned, for it left a sharper cut. After removing
the presser-foot, in its place a blowpipe with a fine opening was
clamped to the presser-foot bar, and so adjusted that a blast, con-
ducted to it through rubber tubing, was directed downward on the wax
plate immediately behind the electric wire. The melted wax was
easily removed from the sheet, but there were two serious drawbacks
to the arrangement. First, the lower end of the wire where it was
attached to the lower end of the needle-bar became loaded with con-

MARK.

AN P^LECTKIC WAX-CUTTER.

633

scribed will evidently be moved up and down with the oscillating
vertical motion of the lever V, and is represented in Figure y> at
about the michlle point of its excnirsion, which in this machine amounts

a b

FiGTRE 2. The top of the nuichiiie aoen obliquely from above. The slate
platform, showiiiti a eentral hole for the nozzle of the copper tube and a slot
runiiiuii' from it to the front margin of the platform, has been pushed baek so
as to uncover the " well," in which are seen the round screw cap of the hot-
water tank, and immediately beyond it a portion of the lower horizontal arm of
the '■ needle-bar." In addition are seen the two levers (a, b) which are nsed in
raisiui; tiie far edge of the platform. At the left of the "well" is tiie removable
felt screen, and in the background the Wagner und Muntz ])ump. Tiu' ]datiniim
wire (whicii has been imrjiosely made more conspicuous than it really is) is
sliown with tile su])portiiig brass wire and spring, and likewise tlie manner in winch
thi' latter are sui)ported by passing through the bars of indurated fibre. Tlie
portable lamp is seen at the right.

to H") mm. Supporting the upper wire and spring by two sets of
horizontal bars bored to receive the cylindrical rods has the advantage
of allowing one to adjust the upper hook vertically over the lower hook
with great ease and accuracy. Once clamped in the proper ])osition,

these bars need no resetting.

The use of indurated fibre, which is a

634 PROCEEDINGS OF THE AMERICAN ACADEMY.

poor conductor, for the shorter horizontal bars, serves to insulate, as
well as to support and guide, the upper wire and spring. To prevent
lateral vibration of the long, or second, vertical arm of the " needle-
bar," a bearing is provided at the level of the table top of the machine,
as shown in Figure 2.

The electric circuit used to heat the wire W is established by
clamping the wire of one pole to the head (Figure ?>, H) by a liinding-
screw (seen directly below the axle of the lever), and connecting the
other with the upper end of the insulated brass wire and spring. Thus,
head, lever, and bent "needle-bar" form a part of the circuit. In this
circuit is introduced a rheostat (R, Figure 3) consisting of some eight
or nine electric lamps of candle-power varying from 4 to 50, arranged
in multiple, each with separate key. These are seen in Figure 1, be-
neath the drawers at the right of the figure. A portable lamp on
the table (shown in Figures 1 and 2) is constantly in the circuit,
and serves to illuminate the wax plate while cutting. With an alter-
nating current of 110 volts the candle-power required properly to
heat the wire (W) — a platinum wire of 26 standard gauge (about
0.4 mm. in diameter) — is between 50 and loo. The rheostat de-
scribed allows one to adjust the resistance to any voltage ordinarily
used in electric lighting.

The removal of the melted wax is effected by suction produced by
using a Bunsen pump. Figure 1 shows the machine set up with a pump
of the Richards pattern ; Figure 2, with a more efficient special pump,
made by Wagner und Muntz, Munich. With a pressure of 30 or 35
pounds either pump will effectually withdraw the melted wax. To
succeed with this suction apparatus, which is an essential part of the
outfit, requires careful attention to certain conditions. The sucking
tube must be hot enough to keep the melted wax from immediately
hardening, and it must be very close to the under surface of the wax
plate at the point where the plate is being cut. The manner in which
this has been accomplished is shown in Figure 3. A quarter-inch
(6 mm.) copper tube passes through a water reservoir heated with an
alcohol lamp, shown indistinctly in Figure 1. The lower end of the
copper tube ends in a glass bottle with an air-tight rubber stopper
pierced by a bent glass tube (D, Figure 3), to which the suction tube
from the pump (Figure 1) is attached. The tube 0 is for the escape of
steam from the water tank. The upper end of the co})per tube is drawn
out into a bent nozzle (N, Figure 3, seen in vertical and in horizontal
section), with a narrow (about 2 mm.) orifice. In the convex side of
the terminal bend is cut a longitudinal slot (T), which is slightly wider
than the diameter of the platinum wire. The wire, without being de-
tached from its hooks, is slipped into the slot so as to occupy the centre

MARK.

AN ELECTRIC WAX-CUTTER.

631

gealed wax, which in time interfered with the working of the ma-
chine. Secondly, it wa.s necessary to change continually the position
of the wax plate, so that while being melted it should always press

FiGUKi-. 1 (coiiijiiire Fiuure 3). Com])k'tc' inarliine, slio\vin<; tlirce of the
arms (tlie two vertical and tlie upjier horizontal) of tlie " needle-bar," the
two horizontal l)r;iss bars bound to one of the vertical arms by binding-serews,
the short steel rod and (foreshortened) tlie two bars of indurated fibre support-
in.ij the sprinji" and ])latinum wire. The lower horizontal arm of the needle bar
occupies a " well " which is covered by the horizontal slate platform, raised
slif^htly above the table top. In the background are seen the Richards pump
attached to a faucet ami the rubber suction tubini;- leading- to tiie bottle btdow
the water tank. The electric lamps composing the rheostat are seen below the
right-hand drawers of the machine.

against the near face of the wire, leaving all the melted wax on the
far side of the wire. Changing the position of the blowpipe so
that the blast was from below instead of from above, proved to be
little, if any, improvement on the first method, for thereby the melted

VOL. XI.II. — 40

632 PKOCEEDINGS OF THE AMERICAN ACADEMY.

wax, blown upward, fell in drops and spatters on the upper surface of
the wax plate, rendering it unfit for accurate reconstruction work,
and there was the same disadvantage as before, that the cutting had
to be so done as to leave the saw-carf with its melted wax always
on the side of the wire away from the operator. These difficulties
were finally overcome by substituting suction for blast, and by caus-
ing the wire to emerge from the centre of the blowpipe hole, as
will be explained directly.

As at present arranged, the apparatus consists of a sewing machine
(Wheeler ^K: Wilson), in which only a few changes have been required.

These changes consist in the removal of certain superfluous parts,
such as the presser-foot, the bobbin and bobbin-holder, etc., and the
substitution for the needle and needle-bar of an arrangement for
holding the heated wire.

The needle-bar is replaced by a cylindrical steel bar of precisely the
same diameter as the original needle-bar. This new bar may for con-
venience be called "needle-bar" (B, B, Figure n). It is thrice bent
at right angles, thus giving four regions, or arms, — two vertical and
two horizontal. The first of the two vertical arms is inserted, in place
of the original needle-bar, into the bearings of the head (H), and fastened
by a binding-screw to a block which in turn is connected to the lever (V)
by means of the link (L). The upper horizontal arm of the bar is
made about as long (20 cm.) as half the diameter of the largest wax
plate which it is designed to cut. The bending is such that this arm
and the two vertical arms are in one plane ; the fourth (lower horizontal)
arm is bent out of that plane, its free end being nearer the operator
than the corresponding end of the upper horizontal arm. A vertical
slit in the free end of the lower arm receives a copper wire, which is held
firmly by a binding-screw and terminates in a hook, as seen in Figure 3.
The lower end of the electrically heated wire (W), which is platinum,
is made into a loop that can be slipped on to this hook. The loop at
the upper end of the platinum wire is likewise made to slip on to a hook
at the lower end of a brass wire, which is supported indirectly by the
first vertical arm of the bent steel rod, or "needle-bar." Apart of
the brass wire is bent into a spiral spring (S), which serves to keep taut
the heated wire (W), the lower end of the brass wire being free to move
up and down through a hole in the lower of the two short horizontal
S({uare bars of indurated fibre which support it. These two bars are
clamped by binding-screws to a short vertical steel rod, which is in turn
attached to the first vertical arm of the " needle-bar " by means of two
scpiare rods of brass, bored at each end to receive the steel rods, and
furnished with set-screws. The whole of the apparatus thus far de-

MARK. — AN ELECTRIC WAX-CUTTER.

635

rmMi.

Figure 3. Diagrammatic representation of the essential parts of the appa-
ratus. These are all shown in vertical section, except the rheostat, which is
shown in horizontal projection. Near the middle of the rectangular area,
bounded by the arms of the "needle-bar" (B, B) are shown in vertical section
the nozzle (N) with its slot (T) and the platinum wire (W) ; and immediately
above this a horizontal section of the same at the level of the letter N of the
vertical section.

B, B. The two vertical arms of the " needle-bar " ; D, glass tube terminating in
the bottle, which also receives the copper tube ; the rubber suction tube is at-
tached to the glass tube at D; H, portion of the "liead" of the sewing macliine,
which receives the "needle-bar" ; L, link by which the " needle-bar " is attaclied
to the lever; N, nozzle of the copper tube ; 0, orifice of tube for the escape of
steam from the hot-water tank ; P, metal ])lug to fill the slot in N ; R, rheostat ;
S, brass sj)ring to keep the platinum wire taut wlien hot ; T, slot in one side of
copper nozzle ; V, lever connected with crank wheel ; W, platinum wire.

636 PROCEEDINGS OF THE AMERICAN ACADEMY.

of the terminal orifice of the nozzle and to emerge below from the
bottom of the slot. The slot is then carefully stopped with a thin
metal plug P (slight projections from its surface prevent its being
forced inward too far), so that air can enter the tube through the ter-
minal orifice only. If this orifice is kept close to the under surface of
the wax plate, the melted wax will be completely withdrawn and will
run down into the glass bottle ; but if the orifice drops only a few milli-
metres below the under surface of the wax plate, the melted wax will
not be withdrawn and will soon congeal, leaving the cut edges firmly
reunited. This fact has been taken advantage of to produce at will
either a temporary or a permanent cut. As it would be inconvenient
to raise and lower the nozzle with its attached water reservoir, the slate
platform which supports the wax plate during cutting is made mova-
ble in a nearly vertical direction. The front edge (that next the
operator) is supported on two round-headed screws, — one seen dis-
tinctly near the dotted line a, Figure 2, the other faintly, close to the
detached " front plate-slide," further to the right. The height of the
front edge of the platform can thus be regulated by turning these
screws in or out, and accurate adjustment to the height of the fixed
nozzle thus secured. The middle of the far edge of the platform rests
on a square block (a, Figure 2) screwed to a long horizontal arm turn-
ing on a horizontal pivot at the left. Another horizontal arm (b) turn-
ing on a vertical pivot engages the slanting under side of the block, and
when moved in a certain direction raises the block some 6 or 8 mm.
This second horizontal arm is actuated by levers, not shown in the
figures, which are moved by the operator's knee. Thus the far edge
of the platform may be quickly raised or lowered at will, so that the
middle of the platform, where the heated wire is melting the wax, will
also be raised or lowered about half as much as the distant edge.

To prevent the slate platform from becoming heated by the hot-
water tank below it, a felt lining is attached to its under surface and
a removable screen of the same material is placed over the tank.
This is seen at the left in Figure 2 — a square sheet with a square
notch cut out of one corner to accommodate the platform-block.

As thus arranged, the wire may be readily heated to the desired tem-
perature, and, by operating the pedal as in sewing, it may be made to
make rapid vertical excursions. Since the wire is central to the orifice
in the copper tube, the wax plate may be moved in any direction, the
melted wax being withdrawn with equal facility, whatever the direction
of the cutting. The fine sharp cut, exactly perpendicular to the plane
of the wax, which is produced by this machine, seems to meet all the
requii'ements for cutting wax plates rapidly and accurately.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 24. — March, 1907.

CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF

HARVARD COLLEGE.

CONCERNING POSITION ISOMERISM AND HEATS

OF COMBUSTION.

By Lawrence J. Henderson.

Investigations on Liuht and Heat madb and published, vthoixt or in past, with Appeopbiation

fbom the ruuvobo fund.

CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF
HARVARD COLLEGE.

CONCERNING POSITION ISOMERISM AND HEATS

OF COMBUSTION.

By Lawrence J. Henderson.

Presented by T. W. Richards, January 9, 1907. Received December 20, 1906.

Current ideas of valence consist of two distinct conceptions, quan-
tivalence and valence energy, which rest upon two bodies of fact of
different sorts. Of these conceptions quantivalence has played by far
the greater role in the development of organic chemistry and of stereo-
chemistry, though the consideration of valence energy is present or im-
plied in Le Bel's discussion of the asymmetric carbon atom, in von
Baeyer's "Spannungstheorie," in Thiele's theory of partial valence,
and in Werner's stereochemical theories and recent publications. In
Richards's recent discussions of the compressible atom the conception
of valence energy has shown itself more pertinent than the conception
of quantivalence, and in the theoretical discussion of thermochemical
data it has been, and of course is, of the greatest moment.

Conclusions regarding valence energy which are based upon heats of
combustion are open to the criticism that from measures of the magni-
tude of the total-energy change it is sought to determine the magnitude
of a quantity which depends perhaps entirely upon the free-energy
change. Yet even to-day the determination of heats of combustion
remains the one way possible of gaining quantitative data regard-
ing the magnitude of valence energy in organic compounds, and it is
probable that such information, properly interpreted, leads to not
inaccurate conclusions. On the contrary, these conclusions may be
very accurate when differences between the heats of combustion
of similar substances are considered, and when such differences in
very similar cases are compared, as in this paper, there is good rea-
son to believe that changes in bound energy have been almost wholly
eliminated.

Of these two ideas concerning valence, that of valence energy is the
less clearly defined. J. Thomsen, it is true, has sought to show that

640 PROCEEDINGS OF THE AMERICAN ACADEMY.

the energy involved in producing a union between any two atoms is
the same for all cases of that particular union, excluding double and
treble ties, but without regard to the constitution of the rest of the
molecule, and with the aid of this theory he has woven the fabric of
his complicated thermochemical hypotheses. But, as I have shown in
another place,^ unless together with valence energy other considerable
energy relationships exist within the molecule, a possibility as yet un-
supported by fact, the energy of the tie between two atoms is variable,
and dependent upon the nature of every other atom of the molecule
and its position. This logical deduction was established by the con-
sideration of such processes as the substitution of hydrogen by hy-
droxyl to form primary alcohols or acids as the case may be. The
average values of the change in heat of formation of the molecules
in these two cases are

R CH3 - R CH2 OH = 40 Cal.
R CHO - R COOH = 72 Cal.

If we assume that the valence energy of a tie between two atoms is
constant for all cases of the union, and exclude the possibility of other
considerable energy relationships within the molecule, it is clear that
these two values, 40 Cal. and 72 Cal., should be identical. Therefore
the assumption is incorrect.

This conception of varying valence energy is, indeed, old. It was
originally stated without experimental basis by Claus,^ and, again as a
theory, was developed by Werner ^ in his original discussion of his
stereochemical ideas. More recently ^ the significance of comparative
reactions has been carefully considered in this connection, and from
that point of view much evidence has been adduced in support of the
idea of variable valence energy.

The influence of the nature of those atoms of a molecule which are
not directly concerned in a reaction of the molecule upon the heat of a
reaction, an influence which must manifest itself in part through va-
riations in the dependent valence energies of the reacting atoms, I
have already briefly discussed ; ^ with existing data little more can be

1 Journal of Physical Chemistry, 9, 40-56 (1905).

2 Berichte 14, 432 (1881).

' Vicrtcljahrsschrift d. Ziiriehor Naturforschcr Gesollschaft (1801).
4 Werner, Bericlite, 39, lL'78 (1900). Fliirscheiin, Jour. f. prakt. Chcm., 66,
321 (1902) ; 71, 497 (1905) ; Berichte, 39, 497 (1905).
" 1. c.

HENDERSON.

CONCERNINQ POSITION ISOMERISM.

641

said, and I postpone the discussion of this aspect of the question till the
necessary experimental data are at hand, investigations to this end
heing now in progress in this laboratory.

On the other hand, the influence of the relative positions of its
atoms upon the heat of reaction of a molecule, and consequently
upon the valence energies of the reacting atom, is an interesting
subject which in some of its aspects may be discussed with the aid of
existing data.

The following tables contain the available data which show that the
introduction of a foreign group into a molecule influences the heat of
a reaction of an atom group of that molecule in a varying degree
according to the relative positions of the two groups.

I.

CH -> C-CHs

y8

COOH present.6
CHs • COOH - H • COOH 207 - 59

C2H5 • COOH - CH3 • COOH 364.0 - 206.7

higher C2H5 • C„H2,. • COOH - CHs • C„H2„ • COOH

Cal.

148

157..3

156.5

a

B

CONH2 present.7
CH3 • CONH2 - H • CONH2

/3 C2H5 • CONH2 - CH3 • CONH2

283 - 135
439.8 — 282.7

higher C2H6 • C„H2„ • CONH2- CH3 • C„H2„ • CONH2

148

157.1

156.1

C

CONHCsHs present.7
a CH3 • CONH CeHs - H • CONH CeHs
P C2H5 • CONH CeHs - CHs • CONH Q,YL,
higher C2H6 • C„H2„ ' CONH CeH^ -

CH3-C„H2„-C0NHC6H6

1011 -
1168-

861 :
1011

150
157

= 156.2

XLII. — 41

6 Stohmann, .Jour. f. prakt. Chem., 49, 107 (1894).

7 Id., 52, 59 (1895).

642

PROCEEDINGS OF THE AMERICAN ACADEMY.

a
a

y
y

a

/3

a
a
a

/3
/8

/8

D

CH(C00H)2 present.8
CH3 • CH(C00H)2 - H • CH (C00H)2 3G2 - 207
(CH3)2 C (C00H)2 - CH3 • CH (C00H)2 515 - 362

cJhb)^ (C00H)2 - ^^'^G (C00H)2 676 - 515

CsH-)^ (C00H)2 - c'h')^' (C00H)2 990 - 833

C3H;)^ (C00H)2 - c'h /^ (C00H)2 1146 - 990

CO present.^

CO • CH3 - CH3 • CHO 437 - 282

• CO • CH3 - C3H7 • CHO 754 - 600

CH2 • CHO - CH3 • CHO 441 - 282

CH • CHO - CH3 • CH2 • CHO 600 - 441

F
COH present.io
CHs-CH^OH-CHgOH
CH3 • CHOH • CH3I1 - CH3 ■ CH2OH

(CH3)3 COH - (CHa)^ CHOH
C0H5 • CH2OH - CH3 • CH2OH
(CHg)^ CH • CH2OH - CH3 • CHo • CH2OH
(CH8)2 C2H6 • COH - (CH3)3 COH

CH3'

C3H7

CH3-

(CH3)2

155
153

461
157
156

155
154
159
159

326

478
633
480
637
788 - 633 =

171
322

478
322
480

155
156
155
158
157
155

Averages.
C„H2„+iCH3 - C„H2„+iH = 156.2 Cal.

In the Presence of

a

^

Y

higher.

COOH

148

157.3

156-157

156.5

CONH2

148

157.1

156-157

156.1

CONH CfiHs

150

157.0

156-157

156.2

CH (C00H)2

154

161

166-157

CO

154.5

159

. . .

• ■ •

COH

155.3

156

• • •

• • *

* Id., pp. 114, 116. ^ Thomsen, Therinochemische Untersuchuniien.

" See Stolimann's tables, Zeits. f. physikal. Chem., 6, 334 (1890) ; 10, 410 (1892).
" Louguinine's values are here cliauged; see Henderson, Jour, of Physical
Chemistry, 19, 43 (1905).

HENDERSON. — CONCERNING POSITION ISOMERISM.

G43

Differences from 156.2 Cal, the ^^normaV Value.

Ill the Presence of

a

|3

y

liigher.

COOH

-8

+ 1

0

0

CONH2

-8

+ 1

0

0

CONH Colls

-G

+1

0

0

CII • (COOIl),,

-2

+5

0

. . .

CO

-2

+3

. . .

. . .

COH

-1

0

. . .

. . .

11.

CH3 -> COOH

a CHs

/3 CHs

y CH3

8 CHs

e CHs

4 CHs

V CHs

e CHs

I CHs

/3 CHs

P CHs

P CHs

P CH3

fi CHs

ft CHs

ft CHs

ft CHs

ft CHs

/? CHs

ft CHs

COOH present. 12

COOH - COOH • COOH

CH2 • COOH - COOH • CH2 • COOH
(CH2)2 • COOH - COOH • (CH2)2 • COOH
(CH2)3 • COOH - COOH • (CH2)3 ' COOH
(CH2)4 • COOH - COOH • (CH2)4 ' COOH
(CH2)5 • COOH - COOH • (CH2)5 • COOH
(CH2)6 • COOH - COOH • (CH2)6 • COOH
(CH2)7-COOH-COOH-(CH2)rCOOH
(CH2)8-C00H-C00H-(CH2)8-C00H

CH. • COOH - COOH • CH2 • COOH

(CH^)^
(CH2)s
(CH2)3

(CH2).

(CH^)^
(CH2)5

(CHOe

(CH2),
(CHo)8
(CH2)9

COOH -XVI ^.C(C00H)2

COOH- CHs •CH(C00H)2

COOH-CaHs-CHCCOOH)^

C00H-(CHs)2-C(C00H)2

CHs\.

C2H5/'

C00H-CsHrCH(C00H)2
C00H-(C2H6)2-C(C00H)2

C00H-^^^'^)C(C00H)2

COOH- (C3H7)2 • C (C00H)2
COOH- CtHis • CH (C00H)2
COOH - CsHn • CH (C00H)2

207 - 60 = 147

364 - 207 = 157

520 — 357 = 163

677-515 = 162

832 - 669 = 163

989 - 829 = 160

1145-984 = 161

1302- 1141 = 161

1458-1297 = 161

364 - 207 = 157
520 — 362 = 158
677 - 518 = 159
677 -515= 162

832 - 676 = 156

832 - 675
989 — 833

157
156

1145 — 990 = 155

1302 - 1146 = 156
1458 — 1303 = 155
1616 - 1458 = 158

" Stohmann, Jour. f. prakt. Cliem., 49, 107, 114, 116 (1894).

644 PROCEEDINGS OF THE AMERICAN ACADEMY.

Averages.
C„H2„+iCH3 - C„H2„+iC00H = 160 Cal.

/3

y. «f «

higher.

In the presence of COOH 147 157

163

161

Differences from 160 Cal, the *^ normal"

Value.

^

v,«. «

higher.

In the presence of COOH -13 -3

+3

+ 1

III.

CHs -^ CONH^is

A

CONH2 present.

a CHs-CONHa-CONH^-CONHa

283-

■ 203 = 80

P CHs-CH^CONH^-CONHaCHo-CONHa

440-

•359 = 81

y CHs-CHa-CHa'CONHa-

CONH2CH2CH2CONH2 596-

•510 = 86

Summary.
C„H2„+iCH3 - C„H2„+i • CONH2 = 83 Cal.

a P V

In the presence of CONH2 80 81 86

Differences from 83 Cal., the ^^ normal" Value.

a p y

In the presence of CONH2 -3 -2 +3

IV.

CH3-CONHC6H5I4

A

COOH present.
a CH3 • COOH -CeHe-NH- CO COOH 207 - 863 = - 656

P CH3 • CH2 • COOH - CeHs • NH • CO • CH^ • COOH

364 — 1013 = - 649
y CH, • (CHa)^ • COOH - CeHs • NH • CO • (GE,), • COOH

520- 1166 = - 646

Summary.
C„H2„+iCH3 - CJI^^+iCONHCeHs = - 645 Cal.

" Id., 52, 59 (1895) ; 55, 203 (1897). " Id.

HENDERSON. — CONCERNING POSITION ISOMERISM.

64)

-649

In the presence of COOII — G56

D'iffereyices from —645 Cal, the "normal" Value

y
-646

In the presence of COOH

-11

-4

V

-1

It is apparent from a consideration of the above tables that the
effect upon the heat of reaction of a molecule exerted by a group which
is itself not directly concerned in the reaction varies in a regular way
with variation in the position of the group with respect to the react-
ing portion of the molecule. This is most clearly apparent in the
reaction CH3 — COOH in the presence of the group COOH, probably

Cal

170

ICO

150

140

t(

lorm;

,1"

^

1

..^

(

/

/

/

/

a

^

8
Curve I.

because here the effect is great and the data abundant and accurate.
In this case, when the carboxyl group is a to the reacting group
the heat of reaction is diminished by 13 Cal., compared with its
"normal " value in the absence of the carboxyl group ; when the car-
boxyl group is in the /? position the heat of reaction is diminished by
about 3 Cal. ; when the carboxyl group is in the y, 8 or e position it is
increased by about 2..5 Cal., returning finally to the "normal" value
when the distance between the two groups is gi'eater. The effect
may be represented by the accompanying curve. -^^

^' The nature of this curve is apparently inconsistent witli the idea developed
by Fliirscheiin (I.e.) and by Biach (Zeits. f. physikalische Chemie, 50, 4;>, ICOJ) tliat
valence enerfry alternately increases and decreases from one carbon atom to the
next, in a chain or ring ; the period of alternation beintr, in the present matter, some-
times one carbon atom, sometimes more, according to the nature of the case.

646

PROCEEDINGS OF THE AMERICAN ACADEMY.

It is clear in all the above cases that the effect of a group upon the
heat of reaction is greatest when it occupies the a position, and that
when it is sufficiently distant from the reacting group, this necessary
distance varying with the nature of the case, it has no appreciable
effect. Evidently, too, in most cases, before the effect disappears it is
reversed, as in the y, 8, and e positions on the above curve and in the
/3 position in those cases where the effects of the groups COOK,
CONH2, etc., upon the reaction CH — C CH 3 are considered.

In most cases an atom or atom group does not appreciably influence
the heat of a reaction when the reacting group is further away from
it than the /3 or y position, and it may be noticeable only when it oc-
cupies the a position, as in the case represented by the accompanying
curve.

Cal.r

160

150

I >

Curve II.

In the case represented by the first curve, however, an effect is still
notable when the two groups are in the e position to each other, pro-
vided the data are nearly correct, and it is important to consider that
the data for this series of compounds are perhaps the best of all
Stohmann's admirable determinations. Accordingly it is not impos-
sible that curve I represents at least one general case of variation in
heat of reaction with variation in position of an inactive group ; at
any rate the data here represented is not inconsistent with such a
conclusion, and for the most part the curves would be of similar shape.
These regularities in the variation of heats of reaction which
have been here considered, as well as those previously pointed
out, lead naturally to the conclusion that the valence energy
of a tie between two atoms must be capable of continuous varia-
tion^^ within certain limits, not yet to be defined ; otherwise we must
assume the existence of large forces of unknown nature Avithin the
molecule. AcanxUng to this conclusion and the above con^tiderations the
valence energies of two ties between like atoms will under like conditions
be equal, under tmlike conditions different. Thus in the compound CR4

^^ Or, what is less probable, through muuerous distinct niagnitiules discoa-
tinuously.

HENDERSON. — CONCERNING POSITION ISOMERISM. C47

the four valence energies of the central carbon atom will be equal, in
the compound CIl'lV's three will be e(iual and one different from these
three, and in the compound CR'R"R"'R"" all four will be different, even
when the central carbon atom is tied to like atoms by all four of its
valences as in methylethylacetacetic ester

CH3\ /CO — CH3

C,Ur/ \CO-O-C2H6

because every one of the four carbon atoms which are tied to the cen-
tral carbon atom is different in position from every other and conse-
quently subjected to different influences from at least some of the
atoms of the molecule.

It cannot be too strongly emphasized that this conclusion is a logi-
cal deduction from established experimental data with the aid of but
two postulates, the current theory of chemical constitution and the
current theory that the interatomic forces within the molecule are
exclusively (or almost exclusively) valence energies.

It remains to be pointed out that through the consideration of
many cases similar to those here studied, one may hope to obtain
accurate quantitative information regarding the phenomena of orien-
tation of substituting groups ^"^ and the countless other cases familiar to
every organic chemist of the influencing of reaction by substituted
groups, and thus to replace the existing empirical rules for such cases
by accurately formulated principles.

Summary.

In development of the conception of varying valence energy it is
shown that the effect of an inactive atom group upon a reaction of
another atom group of the same molecule, measured by the heat of
reaction, varies in a regular way according to the relative positions
of the two groups.

Curves are presented representing the nature of this variation in
one case of special importance because of the magnitude of the effect
and the accuracy of the data, and in a case where the effect is slight.

It is shown that, in accordance with this conclusion and the previous
considerations, the valence energies of two ties between like atoms are
under like conditions equal, under unlike conditions different.

The importance of these considerations for the understanding of the
influencing of reactions by substituted groups is pointed out.

" Sec for instance Flurscheim, 1. c.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 25 — March, 1907.

TEMPERATURE OF MARS.

A DETERMINATION OF THE SOLAR HEAT RECEIVED.

By Percival Lowell.

Investigations oh Light and Heat madb or published, wholly or in part, with Appbofblatiohs

FROM TUB KdmFURD FUND.

TEMPERATURE OF MARS.

A DETERMINATION OF THE SOLAR HEAT RECEIVED.
By Pebcival Lowell.

Presented December 12, 1900. Received January 15, 1907.

Heat hitherto deduced from Distance only.

Up to the present time the chief obstacle to crediting Mars with the
possibility of life has lain in accounting for sufficient heat on the surface
of the planet. So far the determination of this heat has been limited to
a consideration of distance from the sun. Thus Professor Young, who
feels the difficulty acutely, says in his " General Astronomy " : ^ " We
know that on account of the planet's distance from the Sun the intensity
of solar radiation upon its surface must be less than here in the ratio of
1^ to 1524'^." For the resulting temperature he seems to have assumed
either with Newton, that a body radiates heat in direct proportion to
its temperature, which would give for the mean temperature of Mars
223.6° Abs. (— 236°F.), or Dulong and Petit'slaw, which would make it
363° Abs., or —96° F. ; for he entertains the possibility that the polar
caps may be composed of solid carbonic acid, which freezes only at
—109° F.

A better determination has recently been made by Moulton by taking
Stefan's law of radiation, that of the fourth power of the temperature.
Stefan's formula is not only the best experimentally to-day, but has
since its enunciation been deduced from theoretic considerations by
both Boltzmann and Galitzine. On this basis the mean temperature
comes out —33° F., the reasoning being this ; If a body remains at the
same temperature, it must radiate as much heat as it receives. Con-
sequently the temperature is as the fourth root of the amount received.
Absolute zero is minus 459° F. The mean temperature of the earth is
usually taken at 60° F. Therefore, to determine the mean temperature
of Mars we have, calling x its temperature on the absolute scale, the
following equation :

X : 518 Abs. : : ^4 : >^9,

which gives —33° F. for the mean temperature of the planet.

1 Ed. 1898, p. 3G3.

g52 proceedings of the american academy.

Distance but One of Several Factors.

In these and similar determinations, the only thing considered is
the distance from the sun, as if the surfaces of the planets were im-
material points in space, and the whole heat arriving there went to
warm the bodies. But such is far from being the fact. Not only are
the surfaces material, but any air the bodies possess as a covering is
material too. Now, postponing for the moment consideration of the
blanketing effect of air, the actual amount of heat received at the sur-
faces in consequence of their constitution or of their air-envelope, is not
at all what mere distance would lead one to infer.

Division of Radiant Energy.

So soon as a radiant ray strikes matter it suffers division of its energy.
Part of it is reflected, part absorbed, and part transmitted. What is re-
flected is sentoff again intospace, performing noworkintheway of heating
the body. Now the amount reflected is not the same in all cases, depend-
ing for its proportion upon the character of the matter the ray strikes.

If the surface of a planet be itself exposed unblanketed by air, the
absorbed and transmitted portions go to heat the planet, directly or
indirectly.

If the planet be surrounded by air, the portion transmitted by this
air, plus what is radiated or reflected from it to the solid surface, must
first be considered. Then, upon this quota as a basis, must secondly
be determined how much the surface in its turn reflects. The balance
alone goes to warm the ground or ocean.

Light and Heat.

Radiant energy is light, heat, or actinism, merely according to the
effect we take note of. If our eyes were sensitive equally to all wave-
lengths, we could gauge the amount of heat received by a body by the
amount of light it reflected, — that is, by its intrinsic brightness, or
albedo. For this percentage deducted from unity would leave the
percentage of heat received. This procedure may still be applied,
provided account be also taken of the heat depletion suffered by
the invisible rays. Two problems, then, confront us.

We must find the albedoes of the several planets in order to compare
one with another in its reception of heat, and we must find the relation
borne by the visible and invisible rays to the subject. The latter
problem may best be attacked first.

Actinometers and pyrheliometers are instruments for measuring in
toto the heat received from the sun ; and they have been used by

LOWELL. — TEMPERATURE OF MARS. 653

Violle, Crova, Hansky, and others to the determination of this quan-
tity at given places, and so to a conclusion as to the amount of heat
outside our air, or the Solar Constant. Langley's great contribution
to the subject was the pointing out that the several wave-lengths of
the different rays were not of homogeneous action or modification, and
that to an exact determination of the Solar Constant it is necessary to
consider the action of each separately, and then to sum them together.
To this end he invented his spectro-bolometer.

By means of this instrument Langley mapped the solar radiation to
an extension of the heat spectrum unsuspected before. He then car-
ried it up Mt. Whitney in California, and discovered two important
facts: one, that the loss in the visible part of the spectrum was much
greater, not only actually, but relatively to the rest, than had been
supposed ; and the other, that the gi'eater the altitude at which the
observations were made, the larger the value obtained for the Solar
Constant. Both of these are pertinent to our present inquiry.

With a rock-salt prism, instead of a glass one, he next extended
still farther the limits of the heat spectrum toward the red, the effect
of the solar radiation proving not negligible as far as A = 15 fx.

In 1901 Professor Very, who had been his assistant earlier, published
an important memoir on the Solar Constant, based upon these bolometric
observations, but with a value for it got from spectral curves derived
from simultaneous actinometric and bolometric determinations at Camp
Whitney and Lone Pine, and extended from them outside the atmosphere
by taking both air and dust effects into account in selectively reflecting
and diffracting the energy waves. The air effect is proportionate to the
air mass, but the dust effect increases in greater ratio as one nears
the surface of the ground. The formula he used were adaptations of
those by Rayleigh for accounting for the selective reflection and dif-
fraction of small particles. 2

Energy of Visible and Invisible Spectrum.

Planimetrical measurement of the area enclosed by the curve deduced
for outside our atmosphere gives the following results :

Distribution of Heat in the Spectruji.

Wave-lengths. Percentage.

Invisible, X = 0.2 /ia-0.393 /*...«. 2.5

Visible, A = 0..393 fx-OJG fx. 32.

Invisible, X = 0.76 /a-15 /x 65.5

100.

2 U. S. Department of Agriculture, Weather Bureau, No. 254.

654 PROCEEDINGS OF THE AMERICAN ACADEMr.

giving for the

Visible portion, 32 per cent,

Tnincil-ilo " fiS "

of the whole.

Invisible " 68

Loss OF Heat in Tra"\^rse of the Air.

Turning, now, from the question of the initial heat for different parts
of the spectrum at the time the solar radiation enters the air, we come
next to consider the loss the several rays sustain in their traverse
of it.

From Very's curves for the radiation at the confines of the atmosphere
at Camp Whitney and at Lone Pine, 18 A = 1.2 /a, we get the amount
transmitted at these two stations, employing planimetric measurement
as before, and introducing with him the absorption in the red and
inira-red Irom the Alleghany measures, which he considers the same
at Lone Pine.

From Very's measures we have, calling the whole heat at the
confines of the atmosphere unity, —

Transmission.

\ = 0.2 ^-1.2 IX. A = 1.2 ;u.-15 M.

Outside 50. 50.

Camp Whitney . . . 31.3

Lone Pine 24.3 25.1

To get that for sea-level we shall take Crova's actinometric measures
at Montpellier (height 40 m.), made on August 13, 1888, at 12'' 30",
under a barometer of 761 mm. Simultaneously with these, other self-
registering ones were taken by him on Mt. Ventoux (height 2000 m.).
The respective calories he obtained were, —

Montpellier. Mt. Ventoiuc.

Aug. 13, 12'' 30™, 1888. 0.975 calories, 1.360 calories,

bar. 761.1 mm. bar. 613.5 mm.

We shall reduce these to the same scale as the Lone Pine results,
made with the pyrheliometer and used by Very, to wit :

Lone Pine.

Aug. 11, 12, 14, 12^-1 2" 30™, 1881. 1.533 calories, bar. 663 mm.

giving for

Montpellier. Mt. Ventoux.

1.180 calories. 1.643 calories.

LOWELL. — TEMPERATURE OF MARS, 655

This value of 1.180 i.s one which is probably about the average of
clear days in our latitude, the day in question being registered by
Crova as "very clear."

From these several data we find the following values for the solar
radiation received at the respective posts, in calories in one column, in
percentage of that entering the atmosphere in another.

Solar Radiation.

Bar. Calories. Percentage.

Outside the atmosphere . 0. 3.127 1.000

Camp Whitney .... 500 mm. 1.89G .606

Lone Pine 663 " 1.533 .490

Montpellier 761 " 1.180 .377

The loss in the visible spectrum is almost wholly from selective or
general reflection and from diffraction, that in the invisible one from
selective absorption. The absorptive loss by bands in the former is only
about 1 per cent of the whole, and the loss by reflection in the latter
probably not over 7 per cent of its depletion.

In view of the fact that the absorption is known to take place high
up in the air. Very adopted the Alleghany amount for Lone Pine,
the diff"erence being insensible; but when it comes to Camp Whitney
it is clear from the above that 9 per cent of it is got rid of, between
X= 1.2 fj. and = 10 jU by rising the 11,700 ft. from sea-level.

Depletion in Visible Rays.

We may now find the depletion in the visible part of the spectrum
which is not in general the same as that for the invisible part, decreasing
relatively with the altitude and reversely increasing as the air envelope
becomes thicker. It does this at a greater rate than the increase of
the air mass, because the particles suspended in the air, dust, water
globules, and ice augment more rapidly than the air mass as one
approaches the ground.

Drawing the curve for transmission at the sea-level on the same
principles as those for outside the atmosphere at Camp Whitney and
at Lone Pine, and then measuring the amounts of transmission of each
within the limits of the visual rays, from A = 0.393 ju the K line to
X = 0.76 /i the A band, we get the foUomng table :

65G PROCEEDINGS OF THE AMERICAN ACADEMY.

Transmission of Solak Eadiation in the Visible Spectrum.

Calories received from Visible Portion

tlie Whole Spectrum. trausmitted.

Outside the atmosphere . . . . 3.127 1.000

Camp Whitney 1.896 . .664

Lone Pine 1.533 .482

Sea-Level 1.180 .210

The relative loss in the regions I, X = 0.393 |U to A = 0.76 /u, and II,
X = 0.76 |U. to X = 1.2 /u, between the several stations is as foUows:

L n.

Outside to Camp Whitney . . 0.105 0.029

Camp Whitney to Lone Pine . . 0.055 0.010

Lone Pine to Sea-Level . . . 0.086 0.027

Light received from the Day Sky.

To these transmissions must be added that part of the solar radia-
tion which is lost by reflection and diifraction in the atmosphere before
reaching the ground, but is reflected again upon it, causing the bright-
ness of the day sky. This amount is sufficient to obliterate the stars.
Compared with direct sunlight, its ratio as determined by Langley ^ is

Sun. Sky.

Illumination .... 80 19

or 24 per cent of the sun's light.

We must therefore increase the energy transmitted by 24 per cent
of itself. This gives finally :

Transmission. Portions reflected into Space.

Outside 1.000 1000 0

Sea-Level 21 26 74

Albedo of the Earth.

Now the fraction of the incident energy in the visible spectrum is that
by which we see the body and is called its albedo. The albedo of our
air, then, comes out .74. To get the whole albedo of the earth we
must add to it the albedo of the surface.

3 Professional Papers of tlie Signal Service, Vol. 15.

Dark slate .

.09

Ocean . .

.075

.07

.50 — .78

LOWELL, — TEiMPERATUllE OF MARS. C57

The albedo of various rocks and of the ocean is as follows :

White quartzite . . .25
Clay shale 16

For forest we may perhaps take

and snow according to purity

The percentages of distribution of surfaces being about

Ocean • 72 per cent Steppes & Desert . 10 per cent

Forest . 10 per cent Polar Caps ... 6 per cent,

we deduce 1 1 for the albedo of the surface. But this being illumi-
nated by only 25 per cent of the light outside the air gives about 3 for
its quota to the planet's illumination. When finally the earth's whole
albedo to one viewing it from space becomes .74 + .3 = .77 albedo of
the earth for a clear sky.

As the earth's is about 50 per cent cloud-covered (see the researches
of Teisserinc de Bord on Nebulosity) and the albedo of cloud is .72, we
get .75 for the mean albedo of the earth.

Value of Loss of Light a Minimal One.

That the value above found for the percentage transmission of solar
radiation to the earth's surface is a maximal rather than a minimal
amount, and the albedo a minimal rather than a maximal one, is hinted
by the fact that the higher the observer ascends above the surface the
greater his estimate of the solar constant becomes. Thus Langley in
his memoir on the Mt. Whitney expedition says :

" In accordance with the results of previous observers, then, and of
our own with other instruments, we find a larger value for the Solar
Constant as we deduce it from observations through a smaller air
mass." The italics are his.'*

Depletion by Water-vapor on Mars.

We are now in position to estimate the heat actually received respec-
tively at the surfaces of Mars and the earth. The visual part of the
spectrum containing 32 per cent of the incident solar radiation gives
us its quota directly from the albedo, since the heat received = 1
albedo. The infra-red portion containing 65 per cent of the whole de-
pends upon the character of the air and of what it holds in suspension.

* Researches on Solar Ileat, p. 68.

VOL. XLII. — 42

658 PROCEEDINGS OF THE AMERICAN ACADEMY.

The greater bulk of the depletion in this part of the spectrum comes
from the absorption by water-vapor, water itself, or ice and carbon
dioxide. At the earth's surface the transmission in consequence is
about 50 per cent ; at Camp Whitney it was about 59 per cent. We
might, therefore, suppose it still greater through the air of Mars,
which is very thin, and if we did so we should find a still larger frac-
tion of solar heat to be received by the planet's surface ; so that
such a supposition would actually increase the cogency of the present
argument. But the very thinness of the air joined to the lesser grav-
ity at the surface of the planet would lower the boiling point of water,
as investigation shows (see later in the paper) to something like 110° F.
The sublimation at lower temperatures would be correspondingly in-
creased. Consequently the amount of water-vapor in the Martian
air must on that score be relatively greater than in our own.

Depletion by Carbon Dioxide.

Carbon dioxide, because of its greater specific gravity, would also be
in relatively greater amount, so far as this cause is considered. For
the planet would part, caeteris paribus, with its lighter gases the
quickest. Whence, as regards both water- vapor and carbon dioxide we
have reason to think them in relatively greater quantity than in our
own air at corresponding barometric pressure. We may therefore as-
sume provisionally that the absorption due this cause is what it is
with us at Camp Whitney, or about 40 per cent of the whole, leaving
60 per cent of the heat transmitted.

It is distinctly to be noted not only that this estimate lowers the
determination of the heat received at the surface of Mars, but that
what is thus lost in reception goes to make the retention of the heat
received all the greater.

Albedoes of the Planets.

The albedoes of the several planets, according to the determinations
latest obtained, those by Miiller at Potsdam, together with that found
above for the earth and for the moon by ZoUner, stand thus :

Mercury

. .17

Jupiter .

. .75 (

■ (using Struve's

Venus .

. .92

Saturn .

. .88^

latest diametral

Earth .

.75

Uranus .

. .73 (

. measures, .78)

Moon .

.17 (ZOllner)

Neptune .

. .63

Mars . .

.27

lowell. — temperature of mars. 659

Heat received by Earth and Mars.
We will now apply the argument from the albedo.

Heat received at the Surfaces of Mars and the Earth.

Per cent of Per cent of Heat received

Whole Energy. to Whole Energy.

Mars. Earth.

Visual spectrum ... 32 73 23

Infra-red G5 60 50

Total 64 41.5

The ultra-violet rays slightly increase the depletion by selective dis-
persion for both planets, and probably the more for Mars.

Insolation.

But this is not all. The above deduction applies only to such sky as
is clear. Now the earth is cloud-covered to the extent of 50 per cent of
its surface on the average ; Mars, except for about six Martian weeks,
at the time of the melting of the polar cap and over an area extending
some fifteen degrees from the pole, stands perpetually unveiled. The
surface thus fog-enveloped is 0.034 of its hemisphere, and the time 0.23
per cent of the half year, whence the total ratio of cloud to clear the
whole year through over the whole surface is less than 1 per cent.

The albedo of cloud being .72, its transmission, including absorption
re-given out, cannot exceed .28, and may be taken as 20.^ Conse-
quently the effective heat received on this score by the earth is about
as 20 X 50 = 60 per cent, and for Mars 99 per cent, giving the ratio
that of .60 to .99.

Taking now Stefan's law that the radiation of a body is as the fourth
power of its temperature, and remembering that, since the two planets
maintain their respective mean annual temperatures, they must ra-
diate as much heat as they receive, we have the following equation
from which to find the mean annual temperature of Mars, a:, in which
459.4° + 60° or 519.4°F. on the absolute scale denotes the mean an-
nual temperature of the earth :

a; : 519.4°: : a/i' X .64 X .99 : V^l.524' X .415 X .60
or a:= 519.4° |?f

giving X = 531.4° Abs. = 72° F. or 22° C.

' This agrees with Arrhenius' estimate of the heat transmissibility of cloud.

660 proceedings of the american academy.

Heat received and Heat retained.

Such, then, would be the mean annual temperature of the planet,
were the heat retained as well there as here. I am far from saying
that such is the temperature. For the retention is not the same on
the two planets, being, on account of its denser air, much better on the
earth. But that such is the amount received is enough to suggest
very different ideas as to the climatic warmth from those hitherto
entertained.

Temperature deduced from Heat retained.

To obtain some idea of the heat retained and of the temperature in
consequence we may proceed in this way :

Let y = the radiant energy received at the surface of the earth.
i/i = that similarly received on Mars.

e = the relative emissivity or the coefficient of radiation from the
surface of the earth, giving the ratio of the loss in twenty-
four hours to the amount received in the same time, due to
factors other than the transmissibility of the air, which is
separately considered.
ei = the same coefficient for Mars.

Clouds transmit approximately 20 per cent of the heat reaching
them ; a clear sky at sea-level, 50 per cent. Consequently as the sky
is half the time cloudy the mean transmission of its air-envelope for
the earth is

.35 e
For Mars it is

.60^1

To get, then, the mean temperature of the planet in degrees, .r, from
the heat retained, which is the daily mean receipt less the mean loss,
we have the following equation, the mean temperature of the earth
being [519.4°F. Abs.] 288°C. above absolute zero :

^ _ Vy, (1 -.60gi)
288.5 ~ \X^ (l-.35g)

Determination of e.

To find e we have the data that the fall in temperature toward
morning on the earth under a clear night sky is about 18° F. or 10° C. ;

LOWELL. — TEMPERATURE OF MARS. G61

under a cloudy one, about 1° F. or 4° C. Taking the average day
temperature from these data at 292°iVbs. on the centigrade scale or
19°C., and considering an average day sky and a clear night, we have
the transmission or loss

i (.35 + .50)eoT A25e;
while for an average day and a cloudy night it is

i (.35 + .20) e or .275 0
We form the following equation to determine e :

292° - 10° _ A^y(l -.425e)
292°- 4°~^J/^(i_.275e)

whence e = .47

Since the radiation by day is greater by about 1.15 than by night

292*
being as ^^„

we have more approximately

^(.40 + .50)eoTA5e
for a clear night and average day and

i(.40 4- .20) e or .30 e
for a cloudy night under the same conditions.
This gives, e = .4634,

or substantially what it was before. It changes the final result for the
mean temperature of Mars by less than two tenths of a degree.

Determination of ci.

Since in the mean the planet radiates as much heat as it receives
and

^ = 1.10
2/

662 PROCEEDINGS OF THE AMERICAN ACADEMY.

the radiation must be in the same ratio. Whence, the loss by radia-
tion in twenty-four hours on Mars so far as it depends on the heat
received is

ex = 1.1 e
= .51,

or by the more approximate calculation in the paragraph above, it
still

= .51

Substituting these values in our equation (page 660), we find
a;, the mean temperature of Mars,

= 8°. 7 a

or ==47°. 7 F.,

taking into account the heat radiated away as well as the heat received
and gauging the temperature by the heat retained ; by the net, instead
of the gross, amount of the radiant energy received.

If we assume clouds to transmit less heat than 20 per cent, we di-
minish i/ and increase (1 — .35 e), so that the ultimate result is not
greatly altered.

If we take Arrhenius' formula for the temperature T of the earth's
surface as affected by the air-envelope, we have as determined in his
paper on the effect of carbon dioxide in the air :

T' =

a^-f J/-f(l-a)^(l + i') + iV^M + - j

y {I + f — ZSv)

where a = atmospheric absorption for solar heat,

ft — atmospheric absorption for earth-surface heat,
A = Solar Constant, less loss by selective reflection by the air,
31 = heat conveyed to the air from other points,
N = heat conveyed to the surface from other points,
V = 1 — albedo of the surface,
y = radiation constant.

The values for these quantities found bolometrically for a clear sky
are a = .50,

^ = 1 — .79 X .32 = .747 = whole spectrum — albedo of the air X

visible portion,
(3 = a approximately,
v= 1 -.11 = .89

LOWELL. — TEMPERATURE OF MARS. 663

For the earth in its entirety M = o and N = o, since what is lost hy
convection in one place is gained in another.
Applying this same formula to the case of Mars we have similarly —

ai = .40 approximately,

A 1 = , ,^ „ (1 —.17 X .32) = whole spectrum — albedo of its air X
1.524''

visible portion

.946

1.524'
fii = ai approximately,
vi = 1 — .13 = .87

Whence for the earth under a clear sky

^^^A(l +v — va)
yd + v-^O'

and similarly for Mars, substituting its values for A, a, and /?.

Since in both a = ^ and yi = y approximately, we have Ti for Mars,
which gives

r* A'

But the earth is .50 cloud-covered, and the transmission of cloud
being not more than .20 (the value he takes), we have finally

Ti* ^ Ai .99

T ~A .60'
whence

T, =^ .974 T,

and 7" being 519.4° Abs. on the Fahrenheit,

Ti = 505.7°, that is, 46.3° F. or 8° C.

a result substantially the same as we have deduced.

Had we assumed (3 to be .70 and to be in like proportion to a for
Mars, we should have had

T*= 1.140-

y

and 7\*= 1.101—,

71

GG4 PROCEEDINGS OF THE AMERICAN ACADEMY.

which gives not far from what we had before, since it lowers the re-
sulting temperature for Mars by only about 4° F. or 2° C.

Albedo and Air,

Some interesting conclusions follow on the investigation of plane-
tary albedo.

If we classify the various planets according to their atmospheric
envelopes, we shall discover a significance in their several albedoes.
Three classes stand forth distinct : 1. those possessing no air ;
2. those with air but wholly or in part cloudless ; 3. those with a
cloud covering. Into these classes the planets fall in the manner
below, while the albedoes they respectively present are placed along-
side of them.

I. Airless Bodies. Albedo.

Mercury 17

Moon 17

II. Air-enveloped Bodies.

Venus, Cloudless "I ht t • 92

Earth, 50 % Cloudless r^^^™ ^^^ 77

Mars, Cloudless, thin air 27

III. Cloud-canopied Bodies. Albedo,

Jupiter 75

latest measures.

c, , ^^ f or.78 by Struve's

Saturn 88 j ^

Uranus 73

Neptune 63

The albedo of cloud is .72. Whence it is clear that cloud cannot
account for the albedo of Venus, but that it accords with the albedo
of the four major planets. That an air-envelope increases the albedo
of a planet is witnessed first by the greater brilliancy per unit of
disk of the earth, Venus, and Mars as compared with the airless bodies,
Mercury and the Moon, and secondly, by the relative specific bright-
ness of Venus and Mars, together with what has above been found as
to that of the earth. It appears that the denser the air surrounding
the planet the more dazzling the aspect the planet presents. This is
undoubtedly due not to the gases themselves, but to the solid or liquid
particles the gases support in the shape of dust, ice-particles, or drops
of water.

This testimony of the albedo that Venus is not cloud-covered but
atmosphere-hid is corroborative of the observations made by me at

LOWELL. — TEMPERATURE OF MARS. 665

Flagstaff, 1896, and at Mexico in 1897, from which it appeared that
the planet's markings were not obscured by cloud, but seen, as it were,
through a veil, and which also showed the correctness of Schiaparelli's
deduction that Venus in all probability turned in perpetuity the same
face to the sun. That she did so was evident from the long-continued
observations at Flagstaff and Mexico. Now such a facing always of
one hemisphere sunward would cause convection currents upward in
the centre of the disk, and an indraught along its edge, together with
an absence of moisture on the sunlit half of the planet. Dry winds
of the sort blowing over a perpetual Sahara must be laden with dust,
which Very's investigation finds to be the chief cause of reflection in
our own air. The high albedo of Venus thus stands accounted for.

Light around Venus.

A sidelight bearing on the albedo of air comes from the prolongation
of the crescent of Venus when the planet passes in inferior conjunction
before the sun.

It used to be thought that the fine circlet of light that then crowns
the disk was due to refraction in the Venusian air. But in 1898
Russell, at Princeton, showed that it is rather reflection from that air
than refraction through it which reaches our eyes. Now that such
should be the case follows from the planet's albedo, if that albedo be
of atmospheric and not of nubial origin. This supports the conclusion
reached by the visual observations of Venus at Flagstaff. For refrac-
tion means transmission, and if the air of Venus reflects 90 per cent
of the incident light, it can refract but 10 per cent at most. The light
from it, therefore, must be reflected, not refracted, light in the propor-
tion of nine to one. The albedo, Russell's observations, and the
Flagstaff results, thus all concur to the conclusion that Venus is not
enveloped in cloud.

Deduction as to Amount of Martian Air.

Another outcome of the consideration of albedoes is a means it
gives of approximating to the density of the Martian air. Mars is
chiefly Saharan, and dust, therefore, must be largely present in its air.
Now from the albedo of various rocks, of forests, and of other super-
ficies, we may calculate the relative quotas in the whole albedo of Mars,
of its surface and its air. Five eighths of its surface is desert, and
therefore of an albedo of about .16, as its hue shows three eighths of a
blue-green, the color of vegetation, with an albedo of about .7, while
one sixth is more or less permanently of a glistening white in the

666 PEOCEEDINGS OF THE AMERICAN ACADEMY.

polar caps. These would combine to give it an albedo of .13. This,
however, is illuminated by so much of the light as penetrates the
atmosphere only, about three quarters of the whole. Whence the ap-
parent albedo of the surface must be about .10. As the total albedo
of the planet is .27, the remaining .17 is the albedo of its air.

Taking the density of the air as proportionate to its brilliancy, which
would seem to be something like the fact, since the denser the air the
more dust it would buoy up, we have for the Martian air a density
about two ninths our own over each square unit of surface.

Now, if the original mass of air on each planet was as its own mass,
we should have for the ratio between the Earth and Mars, 9.3 of atmos-
phere on the former to 1 on the latter. This being distributed as their
surfaces, which are in the proportion of 7919^ to 4220^, must be di-
vided by 3.5, giving 2.7 times as much air for the earth per unit of
surface. The difference between 2.7 and 4.5 found above may perhaps
be attributed to the loss of air Mars has since suffered on the supposi-
tion of proportionate masses to start with.

Air Density at Surface of Mars.

To get the relative density of the air at the surfaces of the two
planets these amounts must be divided by the ratio of gravity at the
surfaces of the two, that is, by .38.

For the density being proportional to its own increase, if D denote
the density at any point, we have

dD = — Dgdx,

where g denotes the force of gravity at the surface of the earth, and
X is reckoned from that surface outward into space, whence

D = Ae-<",

A being the density at the surface of the planet.
For Mars we have correspondingly

For the whole mass of air over a space dydz we have, for the Earth,

X'

A A

iJ 9

LOWELL. — TEMPERATURE OF MARS. 667

Similarly for Mars it is

and as the whole mass of the earth's atmosphere over any space di/dz =
4.5 that of Mars at a similar point, and r/i = .38^, we have

1 = ^-^ Ts'

whence as J. = 30 inches of barometic pressure, Ai = 2.5 inches.

Boiling Point on Mars.

Owing to the less amount of the Martian air and the smaller gravity
at the surface of the planet the boiling point of water is greatly re-
duced, being probably in the neighborhood of one hundred and eleven

degrees Fahrenheit. If the whole mass of air be -^ of the earth's,

4.0

while gravity is .38 of ours, the pressure is

dlir/i = .09 of the earth's,
whence the boiling point is 44° C. or

79 + 32 = 111° F.

For the same reason sublimation takes place more freely at identical
temperatures there. Proportionally, therefore, there would be more
water- vapor in the air.

We may summarize the results for Mars :

Mean Temperature . . . . 48° F. or 9° C.

Boiling point of water . . . . 1 11 ° F. or 44° C.

Amount of air per unit surface . 7 in. or 177 mm. ; § of the earth's.

Density of air at surface . . . 2.5 in. or 63 mm. ; yVof " "

The look of the surface entirely corroborates the temperature result
of this investigation.

'to--

Januart 14, 1907.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 20.— Ait.ii,, 1007.

CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY,

HARVARD UNIVERSITY.

THE TRANSMISSION OF RONTGEN RAYS THROUGH

METALLIC SHEETS

By John Mead Adams.

I^'VESTIOATI0NS ON LiQHT AND HEAT MADE AND PUBLISHED, WHOLLY OB IN PAKT, WITH APPEOPRIATION

FEOM THE RuUfOBD FUND.

THE TRANSMISSION OF llONTGEN RAYS THROUGH

METALLIC SHEETS.

Bv John Mkad Adams.

Presented by John Trowbridge, November 14, 190G. Received January 8, 1907.

I. Introduction.

Tins experimental investigation into the phenomena of the trans-
mission of Rontgen rays through metallic sheets has grown out of a
research which was undertaken three years ago for the purpose of con-
firming the measurements of the energy of Rontgen rays then recently
made by Dorn,^ Rutherford and McClung,^ Schops,*^ and others. These
measurements had been rendered somewhat doubtful by Leininger's *
unsuccessful attempt to repeat the work of Rutherford and McClung
and of Schops, and it seemed desirable to obtain new evidence on the
question by a method diiferent from those already used.

In general plan the methods of the above-mentioned investigators
were similar. Each of them allowed the rays to fall upon thin sheets
of metal, and from the heat developed in the metal estimated the
energy of the absorbed rays ; then, after making a correction for the
fact that not all of the rays incident on the metal are absorbed in it,
they were able to calculate the rate at which the tube was radiating
energy in the form of Rontgen rays, by assuming from the work of
Rontgen ^ and of Guillaume ^ that the emission of energy is nearly
uniform in all directions from the target. To reduce the results to
absolute measure, it was only necessary to send through the absorbing
metal a known electric current of such strength that the heating effect
thereby produced was equal to that produced by the absorption of the
rays ; the Joulean heat of the current in the metal was then taken to
be equal to the energy of the absorbed rays. The methods differed in

E. Dorn, Ann. d. Phys., 63, 100 (1897).

E. Uutlierford and K. K. McClunsr, Proc. Roy. Soc, 67, 245 (1900).

3 Scliups, Zcitsch. fiir Xaturwis.s., 72, 145 (1899).

4

F. Leininger, Phys. Zeitsch., 2, m2 (1901).
6 W. C. Kontgen, Ann. d. Phys., 64. 22 (1898).
6 Ch.-Ed. Guillaume, Comptes Kendus, 123, 450 (189G).

672 PROCEEDINGS OF THE AMERICAN ACADEMY.

the means used to detect the heat developed in the metal. Dorn im-
mersed the metal in a body of gas ; the rise of temperature of the gas,
due chiefly to the heat produced in the metal, caused a corresponding
rise of pressure, which was made evident upon a delicate pressure-
balance. Rutherford and McClung and Schups, and Leininger following
them, made the metal the sensitive arm of a bolometer. The methods
differed also in the correction for the incomplete absorption of the rays.
Dorn arranged his apparatus, so that the rays had to pass through sev-
eral layers of the metal, and thus were almost completely absorbed.
The others observed the diminution of heating effect which occurred
when a piece of metal, of the same kind and thickness as the absorbing
sheet, was interposed between the latter and the tube, and hence esti-
mated what fraction of the rays was effective in producing heat.

The method followed throughout the present research was a modifica-
tion of this general plan. A Boys' radiomicrometer 7 was the instrument
used, the thin piece of metal which partially absorbed the rays being
placed at one of the junctions of the thermal couple. With this in-
strument, which is described in detail below, a heating effect was readily
perceived ; and some measurements were made of the whole energy of
the Riintgen rays emitted per second by a tube, which measurements
are included in this paper as a confirmation of the results obtained by
the earlier investigators.

In the course of this work it became plain that there is at least one
possible source of error which may affect, more or less, all measurements
of the energy of Rontgen rays based upon observations of the heat de-
veloped by the absorption of the rays in thin metallic sheets. The
well-known fact that the character of Rontgen radiation is changed by
passage through solid substances shows that the methods thus far used
to correct for the imperfect absorption of such sheets may yield only a
first approximation to the truth. This uncertainty as to the exact effect
produced upon a beam of Rontgen rays by passage through metallic
sheets suggested the subjects experimentally investigated in this paper.
These subjects are :

(1) The effect of varying the thickness of a metallic sheet upon
transmission through it.

(2) The effect of varying the intensity of the incident radiation
upon transmission through a metallic sheet.

(3) The effect of the surfaces of the sheet upon transmission through
it, as distinguished from the eff'ect occurring within its substance.

(4) The effect of transmission through a sheet of one metal upon the
penetrating power of the rays for a sheet of another metal.

' C. V. Boys, riiil. Trans., 180, 159 (1888-1889).

ADAMS. — TRANSMISSION OF RONTGEN RAYS. G73

(5) The nature of the effect which occurs within the substance of the
sheet.

Most of these subjects had ah-eady been investigated by various
observers at more or less length, by means of the photographic plate,
the Huoroscope, and ionization plieuomena ; but in view of the semi-
qualitative nature of photographic and fluoroscopic work, and con-
sidering the difficulty of an exact interpretation of the phenomena of
ionization, it seemed desirable to reinvestigate the subjects with a
strictly quantitative instrument.

The results obtained confirm the work of earlier investigators in most
cases, but in one or two important particulars they are at variance with
generally accepted views. It is believed that such measurements as
those here published are valuable not only in themselves, but as an in-
dication of the way to a more accurate quantitative examination of the
nature of the Kontgen radiation than has yet been made,

11. Apparatus.

Figure 1 illustrates the suspended system of the instrument. It
consisted of a loop, L, of copper wire 0.026 cm. in diameter, completed
at the lower end by a bit of constantan wire, C, and a thin circular
piece of platinum, D. The junctions were made with a soft solder, no
acid being used, and all superfluous solder being removed. The wires
at the upper end of the loop were twisted together, and carried a light
mirror, M. A vertical section through the wooden case of the instrument
is shown in Figure 2. The loop of copper was hung by a fine quartz
fibre in a magnetic field due to the permanent magnets, N, S. The
block of soft iron, I, was drilled horizontally and vertically as repre-
sented, and was designed to prevent the magnetic field from exerting
a directive force on the suspended system. A copper sheathing, not
shown in the section, lined the central cavity of the wooden case
throughout its length. The Runtgen rays entered the instrument
through a thin aluminium window at A and were partially absorbed
in the platinum. The heat thus developed at the lower junction of
the copper-constantan couple produced an electric current around the
loop, which caused the suspended system to rotate in the magnetic
field until brought to rest by the opposing toreion of the fibre. The
dimensions of the instrument may be estimated from Figure 2, which
is about one third actual size. The thickness of the absorbing platinum
was 0.0014 cm., and its diameter 0..S8 cm. The thickness of the
aluminium window was 0.015 cm. A telescope and scale, the latter
151 cm. from the mirror, were used to read the deflections.

Disturbances of many sorts were encountered and, so far as possible,

VOL. XLII. 43

674

PEOCEEDINGS OF THE AMERICAN ACADEMY.

avoided in setting up and using this instrument. It was placed on a
heavy iron pillar rising from the cement floor of a basement room.
The outside of the wooden case was covered with tinfoil, and a par-
tition of roofing tin, 2 m. high by 1.3 m. wide, was placed between the
instrument and the tube and was put to earth. A hole 1 cm. in
diameter was bored in the partition to give passage to the rays. As

0»t

0 rg^v^^^?;!i!^j:j^^jjg^^

ElGUKE 1.

Figure 2.

an indication of the efficacy of these precautions against electrostatic
disturbance, it may be stated that when powerful sparks were allowed
to pass to the partition from the coil used to drive the tube, the zero
reading of the instrument was not in the least affected. It seemed
that the magnetic field about the suspended system exerted a con-
siderable directive force upon the latter, notwithstanding the soft-iron
block, and direct experiments confirmed this belief In order, therefore,
that not only the sensitiveness of the instrument but its zero reading

ADAMS. — TRANSMISSION OF llONTGEN HAYS. 675

might be independent of transient changes in the external magnetic
field, a hollow cylinder of soft iron, with wall 0.6 cm. thick and with
the necessary apertures, was slipped over the case. The effects
believed to be due to external magnetic disturbances were thereby
much diminished. Changes in the room temperature promptly
produced a drift of the zero reading. To avoid this drift as much
as possible, the instrument was jacketed with cotton wool and hair
felt, the aluminium window for the rays being covered only by a
thin layer of the latter, which appeared by the use of the fluoro-
scope to be perfectly transparent. In addition to this, a double-
walled house of asbestos, large enough for a man to enter, w^as built
around the instrument, the partition, and the tube. The aperture
for observing the mirror was protected by a water-window about 8 cm.
thick, and the telescope and scale were placed outside the asbestos
house. These precautions were found sufficient for seasons w^hen there
was no artificial heat in the building, but during the winter the interior
of the house had to be kept at an approximately constant temperature
by means of an electric stove and an automatic regulator. Because of
the small mass of the suspended system — one or two tenths of a
gram — mechanical vibrations, such as those produced by machinery
in neighboring buildings or by a high wind, greatly limited the hours
available for work w'ith the instrument.

The tube ^ employed as a source of Rontgen rays was one especially
designed for use with a Tesla coil. It is illustrated in section in
Figure 3. The Tesla coil was operated with power obtained indirectly
from the incandescent lighting mains. From those mains the alter-
nating current (110 volts, 60 cycles per second) was led to the pri-
mary of a step-up transformer and an adjustable resistance in series
with it. The current from the secondary of this transformer charged a
condenser of 0.005 mfd. capacity to a difference of potential of from
5,000 to 10,000 volts. The condenser was connected in series with the
primary of the Tesla coil and a Cooper-Hewitt interrupter, and dis-
charged itself through that circuit with a frequency of about 7 X 10^
oscillations per second. Under these circumstances a spark from the
Tesla secondary 33 cm. long between points was obtained ; but for ordi-
nary purposes a spark of half that length proved sufficient. By keeping
the interrupter at a constant temperature of from 75° to 90° C, it was
found possible to maintain a remarkably uniform activity of the tube
for considerable periods, especially in the case of new tubes.

8 Manufactured by the Macalaster Wiggin Company, Boston.

676

PROCEEDINGS OF THE AMERICAN ACADEMY.

The distance from the platinum of the instrument to the centre of
the target of the tube was 22 cm. in all the experiments described in
this paper, with a few exceptions which are noted where they occur.
The metallic sheets were interposed in the beam of rays at about 11 cm.
from the platinum of the instrument in all cases. Throughout the
remainder of this paper these metallic sheets will be referred to as

" screens."

PlGCEE 3.

The two electrodes at opposite ends of the bulb were of aluminium, and be-
tween them passed the rajiidly oscillating discharge from tlie secondary of tlie
Tesla coil. At the centre of the bulb was fixed the platinum target, upon which
the cathode stream from tlie larger aluminium electrode came to a focus. In
the ordinary use of the tube, the target had no metallic connection with the
rest of the system. The effect of the constriction in the walls of the tube in front
of the smaller aluminium electrode was to choke off more or less the cathode
stream emanating from that electrode. The tube was provided with a device for
reducing the vacuum.

III. Approximate Measurement of the Energy.

Soon after the instrument was set up, a test was made to ascertain
whether its deflections were proportional to the amount of radiant
energy which it absorbed per second at its sensitive surface. For the
purpose of this test, and of the calibration described below, the platinum
of the instrument had been coated on one side with a thin paste of lamp-
black in kerosene. A small battery-lamp using about 5 watts served
as a radiating source, and was placed about 3 meters from the in-
strument, the aluminium window of the latter being raised so as to
expose the platinum to the radiation. After noting the zero, the
current was sent through the lamp and the maximum deflection read.
Then the lamp was moved nearer and another deflection taken, and so

ADAMS.

TRANSMISSION OF RONTGEN RAYS.

677

on. The distances used were such that the lamp could be considered
as a point source, and hence the constancy of the product

deflection X square of distance

is proof of the proportionality in question. The maximum deflection
was used rather than the steady deflection, in this work and in all the

TABLE I.
Relation of Dkflkction to Energy absorbed.

d.

Zero
Reading.

Miiximum
Reading.

Throw,
cms.

d^ X Throw.

2.90

20.00

21.53

.63

5.30

2.80

20.06

21.64

.68

5.33

2.70

21.01

21.77

.76

5.54

2.60

21.17 '

21.96

.79

5.34

2.50

21.24

22.11

.87

5.44

2.40

21. .36

22.29

.93

5..36

2.30

21.41

22.44

1.03

5.45

2.20

21.50

22.62

1.12

5.42

2.10

21.G0

22.83

1.23

5.42

2.00

21.71

23.04

1.33

6.32

1.90

21.80

23.30

1.50

5.42

1.80

21.89

23.57

1.68

5.44

1.70

21.98

23.86

1.88

6.43

1.60

22.03

24.12

2.09

5.35

1.50

22.12

24.-52

2.40

6.40

1.40

22.18

24.93

2.75

5.39

work of this paper, because of the drift and other disturbances which
rendered inaccurate the determination of the steady deflection. A
specimen set of readings is given in Table I. By d is indicated the
distance from the lamp to the platinum of the instrument, in meters,
A calibration of the instrument in absolute measure was next made.

678 PROCEEDINGS OF THE AMERICAN ACADEMY,

As a standard of radiation was chosen the " black body " ^ formed by
the small opening of a cavity kept at 100° C. by a steam jacket. At
50 cm. distance this standard radiator, 3.14 sq. cm. in area, produced
a deflection of 111 mm., the platinum of the instrument being in the
normal to the radiating surface ; and by using Kurlbaum's ^^ measure-
ment of the total net radiation from such a body to its surroundings at
the room temperature (0.0156 gm. cal. per sq. cm. per sec, distributed
through the half sphere according to the cosine law), it was computed
that a small source 1 meter away, radiating energy according to the
cosine law, must emit altogether 0.00177 gm. cal. per sec. to produce
a deflection of 1 mm. In other words, a deflection of 1 mm. was
produced -when the platinum was receiving energy at the rate of
5.63 X 10~* gm. cal. per sec, per sq. cm. of its surface.

With this result, an approximate measurement of the total energy
of the Rontgen rays was readily obtained. The tube was placed so that
the centre of the target was 20 cm. from the platinum of the instrument.
A screen of platinum 0.0026 cm. thick was arranged so that it could
be interposed in the path of the rays or withdrawn at pleasure. (A
screen 0.0014 cm. thick, like the platinum used in the instrument,
would have simplified the calculation, but none was available.) Then
readings of the throws produced by the rays with the screen out were
taken, alternating with readings with the screen in. These readings
are given in Table II. In each case the rays were kept on until the
maximum deflection occurred, a period of about 10 seconds. From the
mean deflection obtained when the screen was not interposed, 0.890,
the total energy of that portion of the rays which was absorbed was
found to be

2 TT X 20- X 8.90 X 5.63 X 10"^ gm. cal. per sec,

or 0.00126 gm. cal. per sec. To find what fraction of the whole radia-
tion this represented, it was assumed ^^ that the fraction of rays trans-
mitted by a piece of platinum is given in terms of its thickness, t, by
g-tt_ Then k was found from

^•^''* __ -0.0026 i

0.890

to be equal to 453. Hence the fraction of the incident rays which the
instrument absorbed was

1 g— *53 X 0.0014

9 Wicn and Lumrner, Ann. d. Tlivs., 56, 4')! (1895).
" F. Kurlbaum, Ann. d. Phys., 65, 74«i (1808).

^^ Tliis assumption of an exponential absorption law is without justification,
and probably in the present case is far from tiie truth.

ADAMS. — TIIANSMISSION OF RuNTGEN RAYS.

679

or 0.470, and the whole energy of the rays was then ^ ' — , or

0,00268 gm. cal. per sec. A correction for the absorption in the
aluminium window of the instrument, obtained by assuming expo-

TABLE II.

ApPROXIMATIO MKASUnEMENT OF ExEKGY.

Screen out.

Screen in.

Zero
Reading.

Maximum
Reading.

Throw,
cms.

Maximum
Reading.

Throw,
cms.

•

28.47

29.34

0.87

28.50

28.7G

0.2G

28.52

29.39

0.87

28.49

28.7G

0.27

28.52

29.39

0.87

28.51

28.80

0.29

28.52

29.42

0.90

28.53

28.78

0.25

28.52

29.40

0.88

28.53

28 81

0.28

28.51

29.41

0.90

N

28.53

28.82

0.29

28.55

29.45

0.90

28.58

•

28.80

0 28

28.G0

29.53

0.93

Means 0 890

0274

nential absorption in aluminium, increased this result to 0.00325 gm.
cal. per sec.

As a quantitative determination of the energy of R-ontgen rays,
not too much importance should be attached to this measurement, be-
cause the method is subject to obvious inaccuracies, and also because

680 PROCEEDINGS OF THE AMERICAN ACADEMY.

any measurement of this quantity is of little significance unless accom-
panied by complete specification of the conditions under which the rays
are produced. But as a confirmation of the qualitative result of the
earlier investigations, it serves the purpose for which it was under-
taken ; and, together with the recently published work of Wien,^^ of
Bumstead,^"^ of Angerer,!"* and of Carter ^^ establishes beyond reason-
able doubt the fact that the absorption of Rontgen rays in metals is
accompanied by the appearance of a measurable amount of heat. It
may be of interest, however, to remark that the result reached above
is of the same order of magnitude as those found by the other in-
vestigators : Dorn's tube yielded an output of 0.00151 to 0.00168 gm.
cal. per sec, Rutherford and McClung found 0.011 gm. cal. per sec,
"VVien has obtained 0.0015 gm. cal. per sec, Angerer gives a maximum
value of 0.013 gm. cal. per sec, and Carter finds 0.00514 gm. cal. per
sec. In this connection it may be added that in the latter part of the
present research rays were used the energy of which was undoubtedly
of the order of 0.01 gm. cal. per sec.

IV. Experiments on Transmission.

1. Change in Transmission accompany itig Change in Thickness

of Screen.

The change in transmission which accompanies a change in the
thickness of a metallic screen has been examined by many observers,
and has been found in every case to follow the same qualitative law,
namely, that each succeeding equal increment of thickness is less ef-
fective as an absorbing medium than the one preceding it. Experiments
made in the course of the present research confirm this law for all the
metals examined, and it seems necessary here only to indicate the mode
of procedure followed in these experiments, and to give a specimen of
the curves obtained.

A series of screens, of the metal to be examined was prepared. Each
screen was built up to the desired thickness from thin sheets of
the metal, — a method which is justified by experiments described
below. The screens were then interposed, one by one, in the patli of
the rays, and the corresponding deflections of the instrument observed.
Just before and just after taking each deflection the screens were with-

12 W. Wien, Ann. d. Tliys., 18. OiU {\Wb).

13 II. A. lUinistoad, AnitM". Jour. Sci., 171. 1 (lOOG).
" E. An.uaTor, Ann. d. Phys.. 21, 87 (lUOt;).

" E. Carter, Ann. d. I'liys., 21, 955 (190(5).

ADAMS. — TRANSMISSION OF IloNTGEN RAYS.

681

drawn, and the deflection produced by tlie unimpeded rays was observed,
for the purpose of making allowance for any small variation in the ac-
tivity of the tube. The ratio of each deflection obtained with a screen
interposed to the mean of these two standardizing deflections was com-
puted, and the relative deflection thus obtained was plotted as ordinate

2
O

(-

o

LU
_1
Li.
UJ
D

Hi

>

Ul

a:

to

.9
.8
.7
.6
.5
.4
.3
.2
J

\

\

\

\

\

Sn

\

S^

V

X

"

—

.001 .002 .003 .004 .006 -006 .007 .008 .008 .010

THICKNESS
Figure 4.

CM^ ■

This curve shows the relation between the deflections of the instrument and
the tliickness of the tinfoil screens interposed in the path of the rays. The
thickness, in centimeters is plotted as abscissa, and tlie correspondhifr " relative
deflection" (that is, the deflection observed when the screen is interposed divided
by the deflection observed when the screen is withdrawn) is plotted as ordinate.
It is to be noticed that each successive equal increment of thickness of the
screen is less effective in reducing the deflection than the one preceding it.

against the thickness of the corresponding screen as abscissa. An ex-
periment of this kind on screens of tin is illustrated by Figure 4. The
tinfoil used was not much alloyed by lead, judging from its appearance
and from a measurement of its specific gravity. The curve is from
data taken January 9 with the tube at 20 cm. from the instrument.
A curve taken January 10, with the tube at 25 cm. distance, and
another curve taken on the latter day with the tube at 20 cm. distance,
coincide with this one so closely as to be indistinguishable from it.
Such exact reproduction of results on successive days was possible only
when the tube was comparatively new.

682

PROCEEDINGS OF THE AMERICAN ACADEMY.

2, Change in Transmlssioji accompanying Change in Intensity of

Incident Radiation.

The metals used in the following experiments were platinum, 0.0014
cm. thick ; copper, 0.0044 cm.; silver, 0.0019 cm.; tin, 0.0012 cm.;
aluminium, 0.027 cm. The method was the same in all cases except
for differences in detail. The experiment with silver will serve as an
example.

TABLE III.

Effect of Variation of Intensity upon Transmission bt Silver.

Distance, 42 cms.

Distance, 22 cms.

Screen out.
Throw, cms.

Screen in.
Throw, cms.

Ratio.

Screen out.
Tlirow, cms.

Screen in.
Throw, cms.

R.atio.

1.62
1.G4

1.62
l.GO

1.6.5
1.G6

1.77
1.74

1.11
1.11
1.11

1.20

0.68
0.68
0.67
0.08

5.82
5.61

5.78
5.84

5.92
6.12

3.98
3.91
4.10

0.70

0.67
0.68

0.683

1

The tube was placed as far as convenient from the instrument (42 cm.
from the platinum of the latter to the centre of the target), and a " ratio
of transmission " was obtained by dividing the deflection taken when the
screen was in by the mean of two standardizing dctiections taken when
the screen was out. Then the tube was moved toward the instrument
a distance of 20 cm. along a track wiiich had befen carefully aligned
with the instrument before the latter was jacketed, and a determination

ADAMS. — TRANSMISSION OF RONTGEN RAYS.

683

was made of the ratio of transmission of the silver screen under these
circumstances. The screen was interposed at the same place, relatively
to the instrument, as before ; hence the motion of the tube involved a
considerable variation of the intensity of the radiation incident on the
screen. The extremes of intensity were in the ratio of 1 to 8 in this
experiment, if the law of inverse squares is applicable. The tube
was then returned to its original position, and the first ratio of tran3-

TABLE IV.
Effect of Variation of Intensity upon Transmission by Platinum.

Screen out.

Screen in.

Throw, cms.

Throw, cms.

Ratio.

Mean.

2.80

1.25

0.43

>

Distance,
22 cms.

3.05
3.10
3.20

1.10
1.20

0.36
0.38

I 0.39

J

0.00

0..30

0..33

\

Distance,
42 cms.

0.00
1.00
0.80

0.40
0.37

0.42
0.41

- 0.30

J

3.00

1.12

0.41

'\

Distance,
22 cms.

2.40
2.15
1.60

0.85
0.73

0.37
0.39

■ 0.39

•

mission redetermined as a safeguard. By repeating this process several
times, the set of readings in Table III was obtained.

The experiment with platinum is of especial interest because of the
use made of that metal as the absorbing material of the instrument.
Table IV shows the procedure and the result of this experiment.

From the experiments on copper, tin, and aluminium it appeared
that for those metals, as for silver and platinum, the ratio of trans-
mission is independent of the intensity of the incident radiation for
a considerable range of intensity.

684

PROCEEDINGS OF THE AMERICAN ACADEMY.

3. Experiments to show a Possible Effect of the Surfaces of a Screen

on Transmission.

Experiments "with two metals, aluminium and copper, were made in
order to find evidence of any effect which the surfaces of the screen
might exert on transmission. The results in both cases were negative.
These experiments were conducted in the following way :

A set of screens of different thicknesses was prepared, each screen
consisting of a single solid piece of the metal in question. A second

1.0

.e

.8

7

O

.7

1-

o

Ul

.6

u.

UJ

Q

.5

III

>

(-

.4

-^

LJ

.3

.8

.1

^

Al

^

^.

^

S^

"->

+

\

■

-

\

+

yCu

1

'+

.01 .02 .03 .04 .06 06 .07 .08 09 .10 .U 02 .13 .04 .16 .16

THICKNESS CM.

Figure 5.

This figure shows the small effect of the surfaces of screens upon transmission,
in the case of aluminium and of copper. Tlie curves are obtained by plotting
as abscissa the thickness of each of a set of one-piece screens of the metal under
examination against tlie corresponding "relative deflection" (that is, the deflec-
tion observed wlien the screen is interposed divided by the deflection observed
when the screen is withdrawn) as ordinate. The crosses are points on a curve
obtained when laminated screens were substituted for one-piece screens.

set of screens was made, similar to the first except that the screens
were laminated. The pieces of metal used were brightly polished on
both sides. From the first set of screens a curve was obtained by the
method described on page 6S1. A similar curve was taken for the
laminated screens, and lastly, to check the constancy of the tube, a
second curve for the solid screens. Readings were taken at intervals
of one minute, and in these experiments the rays were not allowed to
run until the greatest attainable deflection occurred, but were cut off

ADAMS. — TRANSMISSION OF RONTGEN RAYS.

685

TABLE V.
Effect of Surfaces of Aluminium Screen.

No. of

Throw, cms.,

Tlirow, cms.,

Rutio.

Screeu.

without Screen.

with Screen.

1.15

1

1.43

1.06

0.82

2

1.62

1.10

0.72

3

1.09

0.68

Data for First Transmission

1.59

4

0.73

0.48

Curve for Solid Screens.

1.46

3

1.55

1.01

0.67

2

1.40

1.13

0.76

1

1.24

1.14

0.86

1.24

1

1.23

1.02

0.82

2

1.16

0.88

0.73

3

0.72

0.63

Data for Transmission Curve

4

1.12

0.51

0.47

for T^Aminated Screens.

1.05

3

1.13

0.74

0.68

2

1.05

0.77

0.71

1

0.95

0.89

0.89

0.96

1

0.90

0.80

0.86

2

0.95

0.69

0.74

3

0.64

0.67

Data for Second Transmis-

4

0.97

0.49

0.51

sion Curve for Solid Screens.

0.96

3

0.92

0.59

0.63

2

0.91

0.70

0.76

1

0.92

0.77

0.84

686

PROCEEDINGS OF THE AMERICAN ACADEMY.

by an automatic device after running three seconds. Though this
reduced the size of the deflections, it rendered less rapid the change
in condition of the tube. The deflections of the instrument under
these conditions appear, from considerations of the motion of the
suspended system under the forces involved, to be proportional to
the energy received during the exposure, just as in the case where
the greatest attainable deflection is used.

A comparison of the mean curve for the solid screens with the curve
for the laminated screens should show the effect upon transmission, if
any, due to the surfaces of the screen. In Figure 5 the dots and the
curves drawn through them are from the data obtained with the solid
screens ; the crosses are points on the curve for the laminated screens.
The screens used in the experiment with aluminium were as follows :

Solid screens : No. 1, 0.027 cm.
No. 2, 0.050 cm.

Laminated screens : No. 1, 0.027 cm.

No. 2, 0.054 cm.
No. 3, 0.081 cm.,

No. 3, 0.072 cm.
No. 4, 0.160 cm.

1 layer.

2 layers.

3 layers.

No. 4, 0.162 cm., 6 layers.
Those used in the experiment with copper were :

No. 3, 0.021 cm.

Solid screens : No. 1, 0.0044 cm.
No. 2, 0.014 cm.

Laminated screens : No. 1, 0.0044 cm., 1 layer.

No. 2, 0.013 cm., 3 layers.
No. 3, 0.023 cm., 5 layers.

TABLE VI.
Summary of Table V.

Solid Screens.

Laminated Screens.

Screen No.

Ratio.

Screen No.

Ratio.

1

2
3

4

0.85

0.75
0.66
0.50

1

2
3
4

0.86
0.72
0.G6
0.47

ADAMS. — TRANSMISSION OF RONTGEN RAYS.

687

Table V contains the data of the experiment with ahnninium in full,
and in Table VI the mean ratios of transmission for that experiment
are collected. Table Vll gives the mean ratios of transmission for the
experiment with copper. The accuracy of the readings with aluminium
was greater than that of the readings with copper, the deflections being
larger. It is to be noted, however, in both Table VI and Table VII, that
the ratios for solid screens are not strictly comparable with the corre-
sponding ratios for laminated screens, for corresponding screens of the
two sets are not quite of the same thickness in most cases. In plotting
the curves in Figure 5, this fact is taken into account.

TABLE VII.
Summary of Experiment ox Effect of Strfaces of Copper Screex.

Solid Screens.

Laminated Screens.

Screen No.

Ratio.

Screen No.

Ratio.

1

2
3

0.55
0.28
0.10

1
2
3

0.53
0.27
0.17

From the.se results we may conclude that in the case of aluminium
and of copper, the effect of the surfaces as such on the tran.smission of
the rays is too small to be detected in measurements of this degree
of precision, if it exists at all.

4. Effect of Transmission through a Screen of One Metal on
Penetrating Power for a Screen of Another Metal.

It has been generally supposed that the transmission of a beam of
rays through a screen of any substance renders the beam more pene-
trating toward another screen of the same or of any other substance
than it was originally. In view of the importance of this matter a re-
examination of the experimental facts seemed desirable. Accordingly
experiments were performed for the purpose of comparing the penetrating
power for a given metallic screen of rays direct from the tube with the
penetrating power for the same screen of rays which have passed through
a screen of some other metal. The ratios of transmission were used as
a basis of comparison. With most metals it was found to be true that
the ratio of transmission for a given screen was greater when the rays

G88

PROCEEDINGS OF THE AMERICAN ACADEMY.

had passed through a screen of another metal than when they came
direct from the tube ; in the language of the subject, the rays were
" hardened " by passage through the first screen. The following ratios
of transmission show this :

Copper alone, 0.587
Aluminium alone, 0.875
Aluminium alone, 0.85
Copper alone, 0. 53

Copper behind silver, 0.608

Aluminium behind tin, 0.928
Aluminium behind copper, 0.91
Copper behind tin, 0.65

TABLE VIII.

Effect of Transmission through Silver on Penetrating Power for

Aluminicm.

Throw, cms.,

Throw, cms.,

Ratio.

Throw, cms.,

Throw, cms.,

Ratio.

no Screen.

Al. Screen.

Ag. Screen.

Ag -Al. Screen.

2.02

1.00

0.84

2.02

1.25
1.21

1.05

0.85

1.79

1.54

0.81

1.74

1.15
1.15

0.96

0.83

1.83

1.59

0.85

1.90

1.24
1.23

1.07

0.86

1.91

1.71

0.89

1.95

1.29
1.28

1.13

0.88

2.06

1.76

0.87

1.98

Means . . .

. 0.852

0 855

In these experiments the thicknesses of the various screens were :
copper, 0.0044 cm. ; silver, 0.0019 cm. ; aluminium, 0.027 cm. ; tin.

ADAMS. — TRANSMISSION OF RUNTGEN RAYS.

689

0.0012 cm. When the first screen was of silver, however, and the
screen for which the penetrating power was being investigated was
of aluminium, the data in Table VlII were obtained. According to

TABLE IX.

Effect of Transmission tiirocgii Aluminium on Penetrating

Power for Silver.

Throw, cms.,

Tlirow, cms.,

Ratio.

Throw, cms..

Throw, cms..

Ratio.

no Screen.

Ag. Screen.

Al. Screen.

Al.-Ag Screen.

2.22

1.43

0.65

2.18

1.67
1.65

1.04

0.63

2.08

1.28

0 65

1.86

1.30
1.33

0.78

0.59

1.57

1.00

0.G3

l.GO

1.18
1.14

0.73

0.63

1.48

0.96

0.65

1.4G

1.12
1.13

0.70

0.62

1.42

0.92

0.65

1.41

- 106
1.07

0.68

0.64

1.35

0.87

0 05

1.30

Means . .

. 0.647

0.622

these measurements, the effect of transmission through silver on ab-
sorption by aluminium is very small. A slight modification of this
experiment, performed some days later, gave a more striking result,
as shown in Table IX. " Ag.-Al. Screen " indicates that the rays trav-

VOL. XLII. 44

G90 PROCEEDINGS OP THE AMERICAN ACADEMY.

ersed first the silver screen, then the aluminium, and vice versa. From
the latter measurements it would appear that the effect of transmission
through aluminium is actually to "soften" the rays for silver. With no
other pair of metals was this anomalous effect observed, and even with
this pair it was not always obtained, but depended much on the state of
the tube. An experiment performed only a few minutes before the one
showing the " softening " effect gave a quite different result, but the
change in the condition of the tube between the two experiments was
evident to the eye. Direct experiments showed that the secondary radi-
ation diffused from the screens cannot account for the observed effect.

5. Effect of the Order of the Piece? in a Tivo-Piece Screen upon
Transmission through the Screen.

In order to throw some light on the nature of the phenomena which
are involved in transmission, the following set of experiments was
devised :

A screen was made by placing face to face two pieces of different
metals, and the deflection obtained from the rays transmitted by this
screen was compared with that obtained when the order of the two
pieces of metal in the screen was reversed. In practice it was found
convenient to prepare two screens, one composed of two metals in one
order and the other composed of the same metals in the other order,
and to compare the deflections accompanying the interposition of the
two screens in succession. In using this method it had to be shown
by an auxiliary experiment that there was no difference in the thick-
ness of the two pieces of either metal, which might produce a spurious
effect or mask a real one. This test was usually applied by reversing,
in each screen, the order of the pieces of metal composing it. In all
of the experiments the deflections were standardized in the manner
before described, by comparison with deflections obtained when no
screen was interposed. In some of the experiments the three-seconds
exposure was used, and in others the rays were allowed to run until
the greatest attainable deflection was reached. The quality of the
rays used in the different experiments varied over a wide range, and
sometimes it was allowed to vary considerably during a single ex-
periment, as was the case in the example given in Table X. Copper
and silver were the two metals used in this experiment. The cop-
per was 0.()()44 cm. thick, and the silver 0.0019 cm. After reversing
the order of the plates in each screen, the data summarized in Table XI
were obtained.

From these measurements it appears that the order of the pieces

ADAMS. — TRANSMISSION OF RONTGEN RAYS.

691

in a two-piece screen of silver and copper does not affect the trans-
mission appreciably. This conclusion evidently holds for a considerable
range of quality of the incident radiation, as the parallel variations of
values in the two columns of ratios in Table X indicate.

TABLE X.
Effect op reversixg the Order of the Metals ix a Two-piece Screen.

Throw, cms.,
no Screen.

Throw, cms..

Throw, cms..

Silver-Copper

Ratio.

Copper-Silver

Ratio.

Screen.

Screen.

4.32

1.55

0.36

4.19

1.62

0.38

4.43

l.GO

0.38

4.28

1.79

0.41

■i.')t]

1.85

0.40

4.67

1.8G

0.39

4.7G

1.90

0.39

4.89

2.02

0.41

4.89

2.05

0.42

4.88

2.04

0.41

4.9.5

2.02

0.41

4.92

2.20

0.44

4.97

2.20

0.45

4.84

2.20

0.46

4.76

2.21

0.46

4.S9

2.28

0.46

4.92

2.17

0.45

4.73

Similar conclusions were deduced from experiments on other pairs of
metals. The four metals, copper, silver, aluminium, and tin, were taken
two by two in each of the six possible ways, and in every case it was
found that the ratio of transmission for the two-piece screen was in-
dependent of the order of the pieces, within the experimental error.

692

PROCEEDINGS OF THE AMERICAN ACADEMY.

The means of the ratios of transmission for each pair of metals
follow :

Copper-aluminium, 0.424
Tin-aluminium, 0.567
Aluminium-silver, 0.489
Copper-tin, 0.336
Tin-silver, 0.368

Aluminium -copper, 0.430
Aluminium-tin, 0.560
Silver-aluminium, 0.489
Tin-copper, 0.331
Silver-tin, 0.365

The thicknesses used were : Copper, 0.0044 cm.

Tin, 0.0012 cm.
Silver, 0.0019 cm.
Aluminium, 0.050 cm.

TABLE XI.
Check on Correctness of Procedure in Experiment of Table X.

Ratio of Trans-
mission Copper-
Silver Screen.

Ratio of Trans-
mission Silver-
Copper Screen.

0.47
0.47
0.48
0.47

0.47
0.47
0.48
0.47
0.48

V. Discussion of Experimental Results.

The qualitative law which connects the thickness of a screen with the
transmission through it, as stated and illustrated on pages 680, 681,
was first enunciated by Rontgen.^^ He explained the phenomenon by
assuming that the beam emitted by the tube consists of a mixture of
different kinds of rays, some of which have more penetrating power
than others. If such a beam were passed through a plate of any sub-
stance, the less penetrating rays would suffer absorption to a greater
extent than the more penetrating ones, and the penetrating power
of the emergent beam would be on the whole greater than that of

the

original beam.

This explanation is a satisfactory one so far as

« W. C. ROntgen, Ann. d. Phys., 64, IS (1898).

ADAMS. — TRANSMISSION OF IlUNTGEN RAYS. G03

the plienomena observed with dilFerent thicknesses of one metal are
concerned.

Another explanation of the phenomena of transmission has recently
been proposed by Walter. ^^ His theory assumes that the effect of
transmission through any substance upon a beam of rays, which may be
supposed homogeneous, is essentially a transformation of the character
of the beam, — a transformation which in some way renders the rays
more penetrating toward all substances. In particular, transmission
through a piece of silver, cadmium, or tin is assumed to render the rays
especially penetrating toward another piece of either of those metals,
and the more so as the atomic weights of the two metals concerned
are more nearly equal. These assumptions are a necessary consequence
of his experimental results, which are briefly as follows : The pene-
trating power of the rays direct from the tube was compared with the
penetrating power of the rays after transmission through a sheet of silver.
The comparison was made by the use of the Benoist- Walter scale of
hardness ^^ and a photographic plate. It appeared that the rays were
rendered less penetrating by transmission through the silver. Trans-
mission through cadmium and through tin showed the same effect to
a less extent. The effect of transmission through each of the three
metals was also examined by means of scales of hardness in which the
central disk of silver was replaced by one of cadmium or by one of
tin ; in every case it was found that the greatest reduction of pene-
trating power occurred when the central disk of the scale was of the
same metal as the interposed sheet, and that this reduction of
penetrating power diminished as the atomic weight of the metal of
the disk departed from that of the metal of the interposed sheet.
Transmission through sheets of metals other than silver, cadmium, or
tin appeared in all cases to increase the penetrating power of the
rays as measured by either of the three scales of hardness. A dif-
ferent series of experiments with the fluoroscope indicated that the
anomalous reduction of penetrating power by transmission through
silver, cadmium, or tin was apparent rather than real, and that in
every case the effect of transmission through one metal was to in-
crease the penetrating power of the rays for every metal. This result,
if correct, makes untenable an hypothesis of relative selectivity in the
absorption of the rays by different metals, which otherwise might
explain the experiments with the scales of hardness, and renders
necessary some such theory as the one which Walter proposes.

" B. Walter. Ann. d. Pliys., 17, 5G1 (1905).
" B. Wiiltor, loc. cit.

694 PROCEEDINGS OF THE AMERICAN ACADEMY.

The experiments of the present research upon the effect of trans-
mission through one metal on penetrating power for another were
undertaken for the purpose of confirming or disproving the necessity
of such a theory of transformation. The results which are summarized
on page 688 are in agreement with the general statement which Walter
has deduced from his fluoroscopic work, so far as they go ; but the re-
sult of the experiments with silver and aluminium, given on page G90,
is contradictory to that statement, and indicates that relatively selec-
tive absorption among metals may exist.

In view of the doubt thus cast upon the necessity of a theory of trans-
formation, direct experimental evidence of transformation was sought
by means of measurements of transmission through a screen composed
of two pieces of different metals. These measurements are described
on pages 691, 692. It is to be expected that if transformation occurs
in the metals, the effect of the second metal upon rays transformed
by the first will not be quantitatively the same as the effect of the first
metal upon rays transformed by the second. In other words, the trans-
formation theory leads ua to expect that the ratio of transmission of a
two-piece screen will depend upon the order of the pieces ; and the ab-
sence of this dependence, experimentally shown, is evidence of the
absence of transformation.

With the possibility of transformation in transmission thus removed,
and with experimental evidence ^^ showing that any effect of the sur-
faces of the metal upon transmission is small, the only conceivable
action produced upon a beam of rays by transmission through a
metallic screen is an absorbing action. To explain the phenomenon
observed by Rontgen with different thicknesses of the same metal,
we must suppose, with him, that the rays from a tube are hetero-
geneous, and that different kinds of rays are differently absorbed in
any one metal. To explain Walter's apparent reduction of penetrating
power by transmission in certain cases, we must suppose that rays
which are more penetrating for some metals are less penetrating for
others, — ■ that is, that metals show relatively selective absorption, and
that the apparent reduction of penetrating power by transmission
through silver, etc., is a real reduction of penetrating power with
respect to aluminium. In judging of the significance of Walter's
fluoroscopic work, as in fact of all work on R(>ntgen rays, it must be
borne in mind that the selectivity of the absorbing media of the
instruments themselves must greatly affect the magnitude of their
indications, and that an exact interpretation of those indications is

" See Tables V-VII and Figure 5.

ADAMS. — TRANSMISSION OF lluNTGEN RAYS. 695

beyond our knowledge at present. This consideration will cx])lain
many disagreements in the results obtained by observers using dillerent
instruments.

It is simplest to suppose that the effect of transmission through
a metallic screen upon any one component of a heterogeneous beam
is independent of the presence or alDsence of the other components.
In other words, the effect of a given screen upon the transmission
of a particular sort of ray is measured by an absorption coefficient
which may change with the conditions of the experiment only in so
far as those conditions affect the ray in question. An attempt has
been made to test the constancy of these coefficients under changing
intensity of the rays, by the experiments where the dependence of
the ratio of transmi^-sion upon the distance between the tube and the
screen was investigated. These experiments are given in detail on
pages 6S2, 683.

It seems very probable that in experiments so conducted the varia-
tion in the intensity of the rays incident on the screen, involved in
moving the tube, very nearly fulfils the condition that the changes
in the intensities of all the components of the beam shall be in one
ratio. Except for the absorption by the air, this ratio is doubtless
fixed for all the different sorts of rays by some function of the dis-
tances involved ; and from numerous experiments with various in-
struments 20 it appears that the absorption by air of Runtgen rays
in general is negligible for such short distances as these. Of course
a real disturbing factor is the changing behavior of the tube, for
which correction is made, as well as possible, by alternating and
checking readings. Granting that these sources of error have had
no appreciable effect, we learn from the observations that the ratios
of transmission of the metallic screens examined are independent of
the total intensity of the incident radiation, when that intensity
changes in such a way that the intensities of all the components
change in the same ratio.

If we examine this result in the light of the conclusions already
reached in this paper, its practical importance will appear. It is plain
that if we knew in advance that all of the absorption coefficients for
the metallic screen and the beam in question are constant so far as
the intensity is concerned, the constancy of the ratio of transmission
would necessarily follow, provided we conclude from the data of Table IV
that all of the absorption coefficients of platinum are independent of the
■ - — _

20 J. Trowbridge ami J. E. Biirbank, Amor. Jour. Sci., 157, ."96 (1800) ;
A. SL Jlayer, Amer. Jour. Sci., 151, 467 (1896) ; C. G. Barkla, riiil. Mag., 7,
655 (1904).

G96 PROCEEDINGS OF THE AMEllICAN ACADEMY.

intensity. But to draw conclusions as to the constancy of any or all of
the separate coefficients from the constancy of the ratio of transmission
is not in strictness possible. It might be that two or more of the coeffi-
cients changed together in such a way as to keep the ratio of transmission
constant. But the repetition of this coincidence in experiments with
different metals and with rays from tubes in very different conditions
is exceedingly unlikely, and the constancy of the ratio of transmission
with varying intensity is at least very good presumptive evidence
that the coefficients characteristic of the absorption of Ilontgen rays
in metallic sheets are all constant with varying intensity of the
rays. It may be of interest to examine the consequences of sup-
posing that the constancy of the ratio of transmission is not a result
of the constancy of each of the coefficients. To simplify the argument,
let us suppose that the metallic screen is very near the instrument.
Let .^1 and s^ represent respectively the fraction of a certain sort of
ray which the metallic screen transmits at the large intensity and
at the small intensity. Let jj be the fraction of the same sort of ray
which the platinum of the instrument transmits at all intensities. Let
/j and /o represent the two intensities of this sort of ray at the instru-
ment. Then the ratio of transmission for this ray alone at the large
intensity would be

7i si (1 —p)

or Si; and at the small intensity,

I^s^ jl-p)

or ^2. If the ratios of transmission for the whole beam are found to
be the same at the two intensities, the explanation must be either
that each .sj is e(iual to its corresponding ,%, or that some of the si's
are larger than their corresponding s^s while others are smaller. The
latter explanation is equivalent to saying that the absorption coefficients
for some sorts of rays are increasing functions of the intensity, while
others are decreasing functions ; and this seems highly improbable.

The argument of this section may be summarized in another form,
as follows :

The possible effects of transmission through a metallic screen upon
a beam of Rihitgen rays are three :

(1) An eifect produced upon the beam by transmission across the
surfaces of the screen.

(2) An effect of trdnsformatlon suffered by the several components
of the beam in passing through the substance of the screen.

ADAMS. — TRANSMISSION OF RONTGEN RAYS. G97

(3) An efl'ect o^ absorption sufTered by the several components of the
beam in passing through th^ substance of the screen.

Experimental results rule out, more or less certainly, the first two
effects. Granting these results, a theory of relatively selective ab-
sorption is necessary to explain the reduction of penetrating power for
one metal by transmission through another. By somewhat indirect
experimental evidence, this absorption is shown to be governed by
coefficients which are probably constant with varying intensity of
the rays.

VI. Conclusions.

The following conclusions are reached in this paper :

(1) The approximate measurement of the energy of Rihitgen rays is
of the same order of magnitude as the earlier measurements of that
energy, and to that extent confirms them.

(2) In the transmission of Runtgen rays through metallic sheets, the
effect of the surfaces of the metal is small.

(H) In the transmission of Rontgen rays through metallic sheets, the
probability that one sort of ray is transformed into another sort of ray,
to an appreciable extent, is small.

(4) The absorption of any particular sort of ray by a metallic sheet is
measured by a coefficient which is probably independent of the intensity
of that ray.

(5) In one special case, at least, the general effect on absorption by
one metal of passing the rays through another metal is not, so far as
we can judge, a decrease of absorption, but an increase ; and this fact
tends to support the theory that the radiation irom an ordinary tube
is heterogeneous in character, and that the absorption in metallic
sheets is more or less selective.

It is hoped to continue this research in the direction suggested by
the conclusions of this paper : to test the hypothesis of relatively se-
lective absorption by direct experiment ; ^^ to obtain, if possible, beams
of Rontgen rays which will yield transmission curves of a simpler form
than those heretofore found ; to study the properties of those beams ;
and to study the indications of the instrument used in this research in
comparison with those of other instruments heretofore used, especially
the ionization -electroscope and the photographic plate.

21 For a preliminary note on this experiment, see Amer. Jour. Sci., 173, 91
(1907).

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 27 — May, 1907.

THE PROCESS OF BUILDING UP THE VOLTAGE
AND CURRENT IN A LONG ALTERNATING-
CURRENT CIRCUIT.

By a. E. Kennelly.

THE PROCESS OF BUILDING UP THE VOLTAGE AND CUR-
RENT IN A LONG ALTERNATING-CURRENT CIRCUIT.

By a. E. Kennelly.
Presented March 13, 1907. Received March 5, 1907.

Let us consider the simple alternating-current circuit indicated in
Figure 1 ; namely, a long single uniform wire AB, with a ground return
circuit. A single-phase sinusoidal alternator of negligible internal
impedance and generating an e. m. f.

E=E^ sin lot ab volts (1)

is connected to the end A at the instant ^ = 0, when E is starting
positively from zero at the uniform frequency w cycles per second, or
with angular velocity w = 2 tt w radians per second. At B, the distant
end of the line, there is connected an impedance Z to ground. If we
make Z = oo , we virtually free or disconnect the line at B. If we
make Z = 0, we virtually ground the line at B. If we make Z = Zr,
we virtually insert a receiving impedance at B. Any two-wire or
multiple-wire metallic circuit is capable of being reduced to an equiva-
lent simple single-wire circuit with ground return, such as is represented
in Figure 1.

A B

r

Figure 1. — Simple alternating-current circuit.

The current and voltage which exist at any point of the line in Fig-
ure 1 can be readily computed, whatever the given terminal impedance
at B, after the system has been allowed to operate for a sufficient length
of time, usually about one second, during which the initial unsteady
state may be regarded from a practical standpoint as developing into
the final steady state. It is proposed to discuss in this paper certain
formulas, that appear to be new in this application, by which the ac-

702 PROCEEDINGS OF THE AMERICAN ACADEMY.

tions occurring during the initial unsteady state can be easily grasped
and followed to the final steady state. ^ It will be readily seen by the
aid of these formulas that the final steady state is approached by suc-
cessive sudden jumps, and not by a uniform continuous advance. The
unsteady state is a state of leaps and bounds ; but these, although not
necessarily or generally of successively diminishing magnitude, dimin-
ish in a definitely irregular way, and finally disappear. From a phys-
ical point of view, the process is very beautiful, and from a practical
engineering standpoint, it is not without importance.

We may first derive the formulas for voltage and current in the
circuit of Figure 1 in the usual way, starting with the differential
equations of the circuit, and then lead to these already known for-
mulas in the new way.

At any instant t, and at any distance a; centimeters from A along

the Hue in Figure 1 , we have ^

— e' = zi abvolts per cm. (2)

and — i' = ye absamperes per cm. (3)

where e = the instantaneous e. m. f , -abvolts

de ,, T ^ /. abvolts

e' = -r- the space gradient oi e

ax t- o gjjj

i = the instantaneous current, absamperes

di ,, V .^ r . absamperes
z' = -J- the space gradient ot ^

absohms

r = conductor linear resistance,
I = conductor linear inductance,
g = dielectric linear conductance,
c = dielectric linear capacity

cm.
abhenrys

cm.
abmhos

cm.
abfarads

cm.

, d absohms ,..

dt cm.

d abmhos ,^.

^=time.rate of change -^

dt second

1 Compare, however, " Alternating Currents," by Bedell and Crehorc, 1893,
pp. 201-207.

2 "Electromagnetic Theory," by Oliver Heaviside, 1, 450 (180o).

KENNELLY. — BUILDING UP VOLTAGE AND CURRENT. 703

Equation (2) states that the descending gradient of voltage in
abvolts per linear centimeter at any point of the line is always
equal to the current strength at that point multiplied by the con-
ductor resistance per centimeter plus the time-rate of change of the
current into the conductor inductance per centimeter. In other words,
the voltage per linear centimeter is equal to the momentary linear Ir
drop, plus the linear back e. m. f of self-induction.

Ei^uation (3) states that the descending gradient of current along
the line is always equal to the local voltage multiplied by the linear
dielectric conductance, plus the linear capacity into the local time-rate
of change of the voltage, i. e. the linear leakage current plus the linear
charging current.

Differentiating (2) and (3) with respect to x the length of line,

,, ., abvolts per cm. , ,

we get e" = — zi' = ^jz-e (6)

cm. ^ ^

... , . absamperes per cm.

i" = -ye'=yz-i ^^T^ <^')

By (6) the curvature (or gradient of gradient) of the voltage at any
point along the line is always yz times the voltage at that point. By
(7) the curvature of the current along the line is also yz times the local
current. The complete solutions of the second-order differential equa-
tions (6) and (7), for any point distant x from A, are known to be :

e = Eao^xVyz — IK/" ?,\ri}a ws/yz abvolts (8)

i = I cosh x\^z — E^ - sinh x's/yz absamperes (9)

where E and / are the instantaneous impressed voltage, and current,
at the sending end A (Figure 1), respectively.

For an impressed e. m. f. which is sinusoidal, or simply harmonic, in

accordance with (1), we have, '\ij =

V=

■1,

—T- = E^w cos <i>t = ju)E

abvolts per second

(10)

and —J- = /^to cos wt = ju)I

absamperes per second

(11)

so that c = r -f jlw

absohras per cm.

(12)

y = g + jcio

abmhos per cm.

(13)

y and z are thus plane- vector constants.

We have hitherto kept the equations within the absolute C. G. S.
magnetic system of units. We may, however, transfer them to the

704 PllOCEEDINGS OF THE AMERICAN ACADEMY.

" practical " system and use the kilometer (or the mile) as the unit of
length : 3

e = ^^coshXia — /cosinhZi a volts (U)

i = /cosh Zi a — — sinh Zi a amperes (15)

where L^ is the distance w measured from A in kilometers,

a = wTMwrm ^^^ (16)

and Zo = J'^-^tJbL ohms (17)

the vector, or complex quantity, a is commonly called the attenuation-
constant of the circuit. It comprises a "real " part ai called the real
attenuation-constant, and an " imaginary " part Jag called the wave-
length constant, by the relation

The vector impedance z^ is called the " initial sending-end impedance "
of the line, and sometimes the " surge-impedance."

r = the linear resistance ohms per kilometer.

/ = the linear inductance henrys per kilometer.

g = the linear leakage conductance . . mhos per kilometer.

c = the linear capacity farads per kilometer.

Since equations (14) and (15) hold for any moment of time, they
must apply to the final steady state. We may easily derive from them
the following steady-state formulas :

1. When the distant end of the line at B is free,

2. When the distant end of the line at B is grounded,

Ib = — • , J Ia = — : — r-r- amperes (21)
Co smh La Zq tanh La

E^= E Eb= a volts (22)

2 " The Distribution of Pressure and Current over Alteriiatiug-Current Cir-
cuits," by A. E. Kennelly. Harvard Engineering Journal, 11)05-11)00.

KENNELLY. — BUILDING UP VOLTAGE AND CUHRENT. 705

3. When the distant end of the line at B is grounded through a
receiving impedance Zr uhuis,

1b = ^—r-, — ; vT^— amperes (23)

Co Sinn La + Zr cosn La x v /

Eb= laZr volts (24)

All of the values of voltage and current in the steady-state formulas
(14) to (24) inclusive, may be regarded either as instantaneous vol-
tages and currents, in terms of instantaneous impressed voltage E and
current /; or they may be regarded as effective, or S(iuare-root-of-mean-
square values, in terms of etfective impressed voltage E and current
/, such as would be indicated by properly calibrated voltmeters and
ammeters.

We may now proceed to show how formulas (19) to (24) inclusive
may be derived by taking into account the initial outgoing waves of
voltage and current, together with superposed reflected waves. The
only postulate needed is that when the line is first connected to the
alternator at A, the first outgoing current wave has the strength

T E

U — — amperes (2,))

~0

and this current strength continues to be delivered to the line at A
until such time as current-waves reflected from the distant end modify
the current. This proposition is well known.*

The outgoing voltage and current waves run along the wire hand in
hand, with the velocity :

V — ~~ kilometers per second (2(5)

a velocity which is soracAvhat less than the speed of long-wave light in
the dielectric. When the linear conductor resistance and leakage con-
ductance are very small, this velocity approximates to :

v = —= kilometers per second (27)

In the case of overhead aerial copper wires, v approaches 300,000
kilometers per second at high frequencies. At low frequencies the
effect of conductor resistance requires the use of formula (26), and
may bring down the velocity to 100,000 kilometers per second or less.
In paper-insulated, and especially in rubber-insulated cables, the veloc-

* " On the Mechanism of Electric Power Transmission," by A. E. Kennelly.
Electrical World, 42, 673 (Oct. 24, 190-3).

706

PROCEEDINGS OF THE AMERICAN ACADEMY.

DD'

r. ^1

^ KJ

\

1

I

\

\

~1

1

r

n ^ r>

B ^^

^ r

H ^t

X-7V

V X

t 4

% 4

^^ J

i-

:iz 4 Jl

i ^ X

A^^ A

^

-K t

4 ^^ t

t ^\

r N

4 2C

t ^^" \

^^^ t

i^ 4

-f ~~'~'^-~ \r

/ ^-^^

2 ' ^-~—'"~^ \

-/ "-' — """ ^

?-^ \

'^l. .9 .b .7 .9 .4

Amplitude.

Figure 2. -
tlie lirst t)-J kil
tion-constant o

.3 .1 0

r,2

60

68

56

64

62

50

48

46

44

42

40

38

36

34

32

28

26

24

22

20

18

16

14

12

10

.3 .1 .6 .6 .7 .U .» 1.

2 a

o

A a

ity by (26) may be re-
duced, with low frequen-
cies, to 10,000 kilometers
per second, or less.

As the electromagnetic
wave starting from A at
time ^ = 0 runs over the
circuit, containing within
it both a voltage wave, or
electrostatic-flux wave, and
a current wave, or magnetic-
flux wave, it dwindles or
attenuates at the rate of
c~" per kilometer ; so that
after running Li miles, both
the voltage and the current •
will have become weakened
by the attenuation-coefii-
cient £"■^1" ; or

e^E^-^'" volts (28)

and
i = /(, f-^'"^ amperes (29)

where a is the attenuation-
constant of formula (16).
This logarithmic attenua-
tion is represented for a
particular circuit and fre-
quency in Figure 2, but
the same curve, A B C D,
may be used to represent
any circuit and frequency,
by suitably changing the
scales of co-ordinates. The
length of the horizontal axis
is determined byai, the real
part of the attenuation-
constant a in (18), and the
wave-length is determined
by Oj, the imaginary part.
The greater a^, the shorter
the length of circuit that
will fit the curve AB CD.

Piirvo of Wiivo attenuation for

oinctcrs of a circuit of attcuua-

0.07675 -HiO.7854 per kilometer.

KENNELLY. — BUILDING UP VOLTAGE AND CURRENT. 707

The greater a,, the shorter the wave-length, or the more waves that can
be filled into the diagram.

In the case represented by Figure 2, a = a^ -\- jno = 0.07675 +
j 0.7854 per kilometer. After running, say thirty kilometers, the wave
will have dwindled by the atteiiuation-coefhcient e-soo.orers+jojsM) _

^-(2..XK6 + i 2^^.562) ^ ^-2.3026 ^ ^-JZrm_ r|,J^g ^^^^ f^^^^j, -^ g^^^J ^^ nUmcric

0.1. The second is equal to a negative angle of 23.562 radians, or 3|
complete rotations or cycles. The waves of current and voltage on
arriving at B have thus each dwindled to 10 per cent of their original
amplitude, and have also fallen 3f cycles behind the phase existing
at A. The phase of the wave remains the same as it advances, a
crest remaining a crest, but the phase at A is constantly advancing at
the angular velocity w radians per second, so that with respect to the
phase at A, that of the advancing wave is constantly falling behind.

After advancing another thirty kilometers, or to C, Figure 2, sixty
kilometers from A, the voltage and current waves will again shrink to
10 per cent of their amplitudes at B, or to 1 per cent of their original
amplitudes, and will have fallen 7^ cycles in phase behind the voltage
and current phases at A, respectively, the attenuation-coefficient hav-
ing become e-'-'®'^2 + -''^^'-'" = 0.01 \270O°. The original phase differ-
ence between the voltage and current waves at A is equal to the angle
of the vector z^, the initial sending-end impedance (17). With negli-
gible resistance and leakage conductance, formula (17) shows that the
angle of Zq would approach zero ; so that on such a circuit the voltage
and current would be in phase at the start, and also at any point along
the line. Whatever the original phase difference might be, according
to (17), it would be maintained throughout the first run along the
line.

If we represent at 0 E, Figure 3, a unit vector rotating in a vertical
plane about a horizontal axis 0, with the angular velocity oj radians per
second, its projection on the horizontal plane 6 0 2 will at any instant
represent the actual voltage applied to the end A of the line. At
a distance of one kilometer from A, the phase of the outgoing wave
stream will be 0 1, or 45° behind 0 E. The amplitude will have shrunk
to 0 1' or 0.923, an attenuation of 7.7 per cent. The projection of
0 1' on the horizontal plane 6 0 2 will give the amplitude of the wave
at the same instant. At a distance of another kilometer beyond, or
two kilometers from the origin, the phase of the wave stream will be
90° behind 0 E, and the amplitude will have again lost 7.7 per cent, or
will have fallen to 0.853, 85.3 per cent of the original. By continuing
the examination, we should find that at the instant considered, all
points along the line would have a wave amplitude determined by the

708

PROCEEDINGS OF THE AMERICAN ACADEMY.

orthogonal projection of a certain radius corresponding thereto in a
logarithmic spiral E 1' 2' o', etc. At successive distances of eight kil-
ometers, the phases at any instant would be the same. Moreover, by
rotating the entire spiral system of Figure 3 counter-clockwise about
0, with angular velocity w, the amplitude and phase of the wave stream
at any point on the line could be determined, for any moment, by the
orthogonal instantaneous projection of the proper radius in the spiral.

/ '\

\9y \ \

/ / \

y \ \

/ / \

/ ' \

/ '» \ \

/ ' \

/ » 1 \

/ ' \

/ . ',

' \

/ \

X 1 1

R" \

/ .to' :2'

R /

1 /

^"^v '

\ ' y'

N. /

\ * X

\^ / /

\ * y^

>y / /

\ * ^

X / /

\ * j^

\. ' /

\ * X

^^ / /

\ * y^

\ / /

\ ^rf^

\ / /

\ /^'x

\. X ^

\ X •»*

^ ** X. /

\/ "^"^

— ^ \/

^ \.

4^—' ?^

Figure 3. — Diagram of relative matjnitudes and phases of outgoing wave
over the line of Figure 2, for the tirst ten kilometers.

By combining Figures 2 and 3, a mechanical model might be pre-
pared to illustrate the first run of an electromagnetic wave over a cir-
cuit. Into a cylindrical wooden shaft, of the length 0 0', Figure 2,
metal pins or wire nails are driven at intervals, corresponding, say, to
each quarter kilometer. The radial length of the pin from the axis of
the cyHnder must conform to the logarithmic curve A B C D, Figure 2,
and its angular position about the axis must conform to Figure 3, for
the particular line considered, or thirty-two pins to 360°. A shutter
S S, Figure 4, movable in a plane parallel to the shaft, like the sliding
lid of a box, should start from A and admit vertically-falling light rays
L L, on to the spiral, at a moment when the shaft is rotated by the
handle H at uniform angular velocity w, and when the first pin at A

KENNELLY. — BUILDING UP VOLTAGE AND CURRENT.

709

stands vertical. The shutter must be geared with the shaft 0 0', so as
to move uniformly and uncover one complete turn of the spiral in the
interval of one complete rotation of the shaft. The shadow of any pin
P on a horizontal plane at /> beneath would then indicate the wave
motion at that point from the moment of the wave's first reaching it

^UilliiitUJj>'

Figure 4. — Diagram of model for exhibiting the propagation of the first
outgoing wave-train along a uniform line.

until reflected waves disturbed the distribution. The spiral of pins
thus constructed would just fit into the arrangement of Figure 2, con-
sidered as a hollow cylinder or logarithmic trumpet of revolution.

In the case of an indefinitely long circuit, as above outlined, the
initial current strength at the sending end A would remain the final
steady current strength. In other words, there would be nothing to
disturb the original simple harmonic voltage and current. At the
origin A we should always have :

or

also

or

E = Ea sin (Jit

V2

instantaneous volts (30)
effective volts (31)

E,

*o

/„ = /o^ sin wt =■ — sin mt instantaneous amperes (32)
Jo

A

a/2

effective amperes (33)

710 PROCEEDINGS OF THE AMERICAN ACADEMY.

At any distance Li kilometers from A we should have

e =^ E c-"-^i"i \u2

= Ee-^^'^

instantaneous volts

(34)

or

e — £— •'-i«i \a2

V2

effective volts

(35)

also

i — To €~-^i"i \a2
1 ^ e-^.«.\a2

instantaneous amperes
effective amperes

(36)
(37)

If, however, the circuit be comparatively short, and be free, or opened,
at the distant end {Z — <^ in Figure 1), the wave stream on arriving
at B will be reflected back towards A. Let the length of the line be
L kilometers, then the voltage when it reaches B will have the value
Ei.-^"- and the current likewise /o (-^°-. The effects of reflection are
different on voltage and on current, i. e., on moving electrostatic flux
and moving magnetic flux, so that each must be considered separately.

Considering first the voltage wave arriving at the distant open end
of the line, it rebounds therefrom at light-speed, or is reflected there.
The voltage in the reflected wave at B starts back at the same ampli-
tude and phase as when it strikes the free end. It is simply started
backwards along the circuit without undergoing any other change.
It returns towards A, attenuating as it goes, just as though nothing
had happened. At B, however, after the reflection, the voltage is
double that which occurred just before reflection ; for as soon as the
reflected wave starts back, there are the ^c--^" volts arriving at the
head of the incoming train, and also E^~^'^ volts starting at the head
of the returning train. The voltage at B was thus 0 until the wave
arrived at B, then it was E^r-^"-, whereupon reflection immediately
occurred and made the voltage jump to 2 Ef~^"-; where a is a com-
plex number, the real part of 2 E^—^'^, being the maximum cyclic
value of the voltage at B, and 2 Ee-^'^^ sin {wt-a^) being the voltage
at any instant after arrival.

By the time that the wave train gets back to A, the total distance
it will have travelled is 2 Z- kilometers, and the attenuation-coefficient
will be f.-^^'"-. The arriving voltage will therefore be Ef-"-^'"-. As
soon as the end A of the line is reached, the wave will go direct to
ground through the alternator. The e. m. f of the alternator does not
stop the wave, which goes straight through the machine (assumed as
impedanceless) without modification. A voltage wave passing through
a ground or short-circuit virtually swings round the goal and returns
on its path reversed. That is the same, however, as being reflected
with change of sign, or with a change of 180 degrees, or -k radians, in

KENNELLY. — BUILDING UP VOLTAGE AND CURRENT. 711

phase. The wave after reaching A and going to ground returns back
on the circuit towards B, but reversed in sign. The voltage at A is
thus not affected by the return of the wave, because although it tends
to be increased by A'c-^ia volts on the first return it is immediately
increased by —Ef.-"^^"- volts on the recoil from A, these two impulses
being e(|ual and opposite.

The wave reflected with inversion at A now runs back towards B for
the second time. When it reaches B it will have run a total distance of
3 L kilometers from the start, and its magnitude will be —Ei~^^"^ volts.
At the open end B, it is reflected without reversal, thus adding a sud-
den jump of —2 Efr'^^'^ to the voltage previously existing at B. Back
it comes to A in the condition — 7i'e~*-^*. It is again reflected from
A and ground with reversal, making no change in the voltage im-
pressed on A, but starting out for B with the value E<r-^^'^. It
reaches B in the condition E^~^^°-, adding a sudden jump of 2 Ef.—^^"^
to the voltage existing at that moment, and again sets out for A.

The time of one passage along the line is — seconds, where L is the

length of the line and v is approximately -—:= kilometers per second.

vie

In overhead aerial wires v is nearly 3()(),0()0 kilometers per second or the

light speed in air; so that over a circuit 300 kilometers long, the time

of flight of a wave would be about toVo second, and the time of one

return trip jAo second. In one second of time after applying the

alternator to A there would have been completed nearly 500 return

trips over the circuit.

From time ^ = 0 to ^ = 0.001 second, the voltage at B = 0

From time t = 0.001 to 0.003 second, the voltage at B = 2 E e-^^'^ volts

From time t = 0.003 to 0.005 second, the voltage at B =

From time t = 0.005 to 0.007 second, the voltage at B =

2 Ee-L'^ — 2 E^-^^o- + 2 ii'e-5-^^«

and so on indefinitely, until the succeeding jumps of voltage at B
become infinitely small, or the wave has been attenuated away to
nothing. The total final voltage at B after the steady state is finally
reached is :

^^ = 2 E{c-i^^ — e-3^« -f e-si-^ — €-'^i« -t- volts (38)

= 2 E^^''{\ — €-'-^^" -f- c--*^''^ — €-G^" -f " (39)

-La

2 E E

~ ^ ^ 1 -f €-2^- '~ £^« + £-^- ~ cosh La " *^^^^

712 PROCEEDINGS OF THE AMERICAN ACADEMY.

The final result (40) is the same as was found in formula (20). All
the terms in equations (38) to (40) are vector quantities, and are sup-
posed to be added vectorially. It is evident that the e. m. f. impressed
at A is unaffected by reflected waves ; while the e. m. f. at the distant
free end increases by jumps that are numerically smaller and smaller ;
but the phase relation may be such that the eftect on the resultant of
any one jump may exceed that of the preceding jump.

In particular cases when the length L of the line is suitably chosen
with respect to the frequency and to the line constants, the final volt-
age at the distant end may greatly exceed the voltage at the sending
end, either on the basis of maximum cyclic values, or of effective, i. e.
voltmeter, values.

Turning now to the current wave, or magnetic flux wave, when this
reaches B for the first time its value is I^ e-^'^, a vector quantity, hav-
ing a certain phase lag La^ with respect to the current entering simul-
taneously at A, and also undergoing simple harmonic variation. When
a current wave strikes a free end or discontinuity, it is reflected with
inversion ; i. e., with reversal of sign, or 180° (jr radians), change of
phase. It starts back, therefore, towards A as — /q e~^" amperes, and
the total current increment at B is nil. On arriving at A its con-
dition is — /q i.—-^'^ amperes. It then passes through the impressed
e. m. f. without change and is reflected from the groujid. A current
reflected from a ground or short circuit undergoes no change of phase.
It adds, therefore, a jump of —2 I^ f—'^La. amperes at A vectorially to the
current I^ impressed there. Whether this will involve an increase or
decrease in the magnitude of the current at A will depend upon the
relative phases of /o and of — 2/o e~2ia^ which in turn will depend on
the length of the line L for any given frequency. The current wave
then returns to B for the second time, reaching it in the condition
— /o e— ^-^* . It is again reflected with inversion or starts back to A as
/o €—2-^* amperes, adding nothing to the current at B. It keeps up
this battledore and shuttlecock action theoretically forever ; but prac-
tically until it becomes attenuated to insignificant dimensions. The
final resulting current at B is zero, which, of course, must be true at
an open end. This is due to the occurrence there of pairs of incident
and reflected current waves having equal magnitudes but respectively
opposite signs.

The total current strength at A is

/o from ^ = 0 to ^ = 0.002

/o - 2 h e--^^" " t = 0.002 to t = 0.004

/o - 2 /o €-2^" + 2 /o €-^» " t = 0.004 to t = 0.006
and so on.

KBNNELLY. — BUILDING UP VOLTAGE AND CURRENT. 713

After an indefinitely great lapse of time, the current at A is

I^ = I„-2lo e---^" + 2/0 c-*^-^ — 2/0 e-*^^'' + amperes (41)

= /o{l — 2 e--^'' + 2 6-4^« — 2 e-*^^-^ + " (42)

= /o{l — 2 €-2/><^ (1 - e--'^-"' + ^-^^'"- — e-^^" + " (43)

= ^^ = ^

COth Za Co COth Xa ^ V \ "^J

The final result (45) thus agrees with the result of (19).

If now the line be grounded directly at B, the final voltage at B is
nil, because each voltage wave is now reflected from that end with
inversion. The voltage at A also remains steady at E because the
voltage waves are reflected from the ground at A with inversion.

The current arriving at B the first time is Iq e-^'^. It is reflected
directly from the ground there, thus producing at B a total increment
of 2 /o (.~^'^ amperes. On arriving back at A its value is I^ e— 2i".
Being reflected from the ground at A without inversion, it adds a total
increment of 2 Iq c— 2^'^ to I^ the vector current at A. When it reaches
B the second time, its value is /q €~^-^^ and it adds there an incre-
ment of 2 /(, e— 3i/a_ Reversal does not recur at either end of the line.
The final current strength at B after a sufficient lapse of time is

/b =: 2 /o €-^« + 2 /o €-3^-^ + 2 /t-5^^« + amperes (40)

= 2 /o e--^" (1 -f £-2^- + e-4^» + e-<^^" + " (47)

_ I 1(^ € _ Iq I _ J() _ J^ ,, . .

1 — e-^La. ^Lo. _ g-ia gi^Jj 2/a Co sinh La. ^ '

The result (48) thus agrees with Is in (21) or the final receiving-end-
impedance of the grounded circuit is c^ sinh La. ohms.

Similarly, the final current strength at A will be the vector sum
of the initial outgoing current plus all the subsequently added reflected
currents, or

/^ = /o -1- 2 /o £-2/- + 2 /o ^^"^ -f 2 /o e-6^<^ + . . . . amperes (49)
= /o{l -f 2 €-2^-(l -h €-2^« + e-^^« -F . . . . " (50)

( 2 £— 2^°^ ) /I -f- £— 2i<i\

= ^0 1 1 + -{z:^^:. \ = ^"(rfTi^r.) = ^o coth La « (51)
= ,\ T " (52)

Co tanh La

The result in (52) thus agrees with the value for /^ in (21).

If now the line be grounded through an impedance c^ ohms at B,

714 PROCEEDINGS OF THE AMERICAN ACADEMY.

the current Iq e— -^" arriving at B after the first passage, is partly re-
flected with inversion as from a discontinuity, and the rest of it passes
through the impedance c^ to ground without' further reflection. Let
m be the fraction of the current that goes through Zr- This coefficient
m may be called the transmission-coefficient of the impedance Zr. We
have

m = -^ (53)

a vector. Consequently the remaining portion of current 1 — m is
reflected with inversion, as from a discontinuity, and may be called
the reflection-coefficient of the impedance z,..

l-m = ^^-^ (54)

Zo + Zr ^ ^

This portion of current retreats with its sign reversed.

The current which flows through the receiving impedance Zr on first
passage is ?n /o e—^'^ amperes, and a current — (1 — m) I^ e—^"^ =
(m — 1 ) /(, e—^'^ returns to the sending end. It reaches that end in
the condition (m — 1) /oe~~^-^" and is reflected from the ground back
to B without inversion. On reaching B the second time, it will have
dwindled to (m — 1) /(, e—^J^'' amperes and subdivides. The portion
m, {m — 1) /„ €—'^La. passes directly to ground through c,., and the re-
mainder is reflected homewards as (w — 1)^ /q e^^^". The final current
strength built up in the receiving impedance Zr will be :

/^ = m /„ c--'^" + m {m — 1) /„ e"^-^" + m (m — l)'^ Iq i~^^'^ + • • • (55)
= ??//oe-^«{l -f (m — l)e-2i'^ + {m — l)-e— '^-" + {m—iy^-^^'' -f • • •

ml^^ f-^"^ mlf^ _

/n

1 — {in — 1) e-2i« ■" ^La _ (^in _ 1) g-Za - jia /

'"^-iV--

in \

in J

( ) cosh La -f sinh La — cosh La -f sinh La

\ m J zo

E

amperes

■^0 sinh La + Zr cosh La

The final result of (56) is thus identical with the value of /» in (23).
The receiving-end-impedance with the impedance Zr at B is

Zi — Co sinh La -+- Zr cosh La ohms (57)

Following the above line of reasoning, we can readily understand
that every discontinuity in a circuit, such as a leak or a lump of im-

KENNELLY. — BUILDING UP VOLTAGE AND CURRENT. 715

pedance at a point, sets up a pair of secondary waves ; namely, those
that go on through the impedance, and those that go back reflected.
The final steady state is the harmonic variation of a vector sum at
each point, due to all the primary, secondary, tertiary, etc., ^Yaves,
summed to infinity. In many cases this vector sum may be very
simply expressed in hyperbolic functions ; but if these functions are
not made use of, there is a fearful and wonderful summation.

I

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 28. — May, 1907.

CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF

HARVARD COLLEGE.

THE DETERMINATION OF SMALL A3I0UNTS OF
ANTIMONY BY THE BERZELIUS-MAltSH

PROCESS.

By Chari-es Robert Sanger and James Andrew Gibson.

With a Plate,

CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF

HARVARD COLLEGE.

THE DETERMINATION OF SMALL AMOUNTS OP ANTI-
MONY BY THE BERZELIUS-MARSH PROCESS.

Br Chakles Robert Sanger and James Andrew Gibson.

Presented January 9, 1907. Received March II, 1907.

The Berzelius-Mar.sh method has been successfully applied to the
quantitative determination of arsenic. On the one hand, the process
which depends upon the weighing of the " mirror," first suggested by
Berzelius himself,^ has been carefully worked out by Gautier,^ Chitten-
den and Donaldson,^ and several others, and is applicable to cases in
which the amount of arsenic is too small for precipitation as sulphide
or in which the separation of the latter would be inconvenient. On
the other hand, for cases in which the mirror of arsenic is too small for
weighing, or in the rapid estimation of very small amounts, methods
similar to that which was first described by one of us ^ have found
wide application.

The extension of the gravimetric Berzelius-Marsh method to the de-
termination of antimony is impossible for the reason that, under ordi-
nary circumstances, a large part of the antimony is deposited on the zinc
in the reduction flask and does not leave the solution as the hydride.
In attempting to apply the method of Sanger * to the determination of
small amounts of antimony, we were met not only by this difficulty,
but also by the well-known irregularity in the deposition of the anti-
mony in the heated tube, the temperature at which the antimony
hydride is decomposed being so low that much of the deposit is formed

^ Berzelius, Jahresbericlit, 17, 191 (1837). The decomposition of the arsenic
hydride by heating the tube was also suggested by Liebig, Ann., 23, 217 (1837),
but the idea of weighing tlie arsenic seems to have originated witli Berzelius.

2 Bull. Soc. Chim. (2) 24, 2")0 (1876).

3 Am. Chem. Journ., 2, 2:^>5 (1881) ; Chem. News., 43, 21 (1881).

* Tlicse Proceedings, 26, 24 (1891); Amer. Chem. Journ., 13, 431 (1891).
Abstracted in Jour. Chem. Soc, 62, 882 (1892) ; Jour. Soc. Chem. Ind., 11, 370
(1892) ; Chem. Centralbl., 63, 335 (1892) ; Ber., 25, 47, r, (1892) ; Zeitschr. Anal.
Chem., 38, 137 and 377 (1899).

720 PROCEEDINGS OF THE AMERICAN ACADEMY.

in the wide part of the tube ; hence a series of standard mirrors under
these conditions is impossible. We have found, however, that both of
these obstacles are surmountable, and that small amounts of antimony
in solution can be reduced with practical completeness to the hydride,
which, when suitably heated, deposits the antimony in such a form as
to admit of estimation with reasonable accuracy by comparison with
standard mirrors.

In arriving at this result two studies were made: first, as to the influ-
ence of the concentration of the antimony ions on the deposition of the
antimony upon the zinc ; second, as to the influence of the temperature
and cross section of the heated tube on the formation of the mirror.

I. The Evolution of Antimony Hydride in the
Reduction Flask.

A solution of pure recrystallized tartar emetic was prepared of such
a strength that 10 grams contained 0.0996 gram of metallic antimony
(average of five determinations of the antimony as the pentasulphide,
also confirmed by the volumetric method given below). A definite
amount of this solution was introduced in small portions into the re-
duction flask (see Figure 2), which contained 0.5 gram of zinc and 20
cubic centimeters of dilute sulphuric acid (1 to 12). The evolved
hydride was carried through a hot tube by a current of hydrogen
according to the method described below, except that the tube was
heated, as in the determination of arsenic, at its wide portion. After
the deposition of the antimony in the heated tube had evidently reached
its maximum, we determined the amount of the deposit, as well as the
amount precipitated on the zinc and the residue still in solution. The
volume of liquid in the reduction flask was approximately the same in
all cases.

To find the amount of antimony deposited in the heated tube, the
portion of the tube containing the deposit was weighed, the mirror
dissolved in hydrochloric acid and potassic chlorate, and the tube,
after washing with alcohol and ether, reweighed.

The metallic antimony and zinc .left in the reduction flask were
filtered, washed, and dissolved in hydrochloric acid with the aid of a
small amount of potassic chlorate. The antimony in this solution was
determined by the iodometric method of Gooch and Gruener.s The
solution, free from chlorine, was reduced by boiling with potassic iodide
in excess of sulphuric and tartaric acids. Any residual iodine was
bleached by careful addition of approximately hundredth-normal sul-

» Amer. Journ. Sci., 42, 213 (1891).

SANGER AND GIBSON. — DETERMINATION OF ANTIMONY. 721

phurous acid, and the solution, neutralized with sodic hydroxide, was
titrated with iodine after addition of acid sodic carbonate.

In the filtrate from the metallic antimony and zinc, the unreduced
antimony in solution was determined also by titration with iodine.

Four series of determinations were made, using weighed amounts of
the tartar emetic solution equivalent respectively to about 150, 100,
50, and 10 milligrams of antimony. The results are given in the fol-
lowing table. The analyses under columns c and d were made, in
Series A and B, with an approximately decinormal solution of iodine,
standardized, through sodic thiosulphate and potassic bichromate,
against pure iron. In Series C and D an appi'oximately centinormal
solution of iodine was used, standardized against a determinate solution
of thiosulphate made from the decinormal.

TABLE I.

No.

a

mc;. Sb.
taken.

b c

mg. Sb. (lep. mg. Sb. ppted

iu tube. on zinc.

SERIES A.

d

mg. Sb. not
reduced.'

e

Ratio

c/b.

1.

147.8

9.6

106.8

14.3

11.1

2.

156.1

13.8

117.7

7.6

8.5

3.

149.2

19.2

105.0

9.6

5.5

4.

152.0

19.6

90.0

26.9

4.6

5.

151.0

12.9

136.7

12.3

10.6

6.

152.9

16.9

100.1

19.7

5.9

Average of Series A . .

7.7

K

SERIES B.

1.

101.5

17.3

71.9

7.i

4.2

2.

100.9

21.6

lost

lost

3.

100.9

20.0

65.3

5.5

3.3

4.

100.7

12.8

73.5

11.2

5.7

5.

100.3

13.5

lost

4.7

6.

100.5

15.7

64.4

7.4

4.1

Average of Series B . .

. 4.3

SERIES C.

1.

49.7

13.3

28.3

3.6

2.1

2.

<<

14.9

22.7

3.6

1.5

3.

cc '

11.7

27.4

6.3

2.3

4.

((

lost

24.9

2.9

5.

cc

16.9

21.8

3.9

1.3

rOL.

XLii 40

Average of Series C . .

1.8

722

PROCEEDINGS OF THE AMERICAN ACADEMY.

SERIES

D.

1.

9.4

7.8

1.8

1.4

0.2

2.

10.4

8.7

1.0

1.9

0.1

3.

9.5

4.9

2.2

4.7

0.4

4.

9.5

5.7

2.0

2.7

0.3

5.

9.6

8.7

1.4

3.2

0.2

6.

9.6

7.8

A VP1

2.0

cfl.crp. nf Sfil

3.3

ries D . .

0.3
. 0.3

0.3

1.8

i.3

Figure 1.

A study of the above table
will show that there is appar-
ently a considerable amount
of unreduced antimony in
solution, and that all the
antimony taken is not ac-
counted for, except in Series
D, in which it is less than the
amount apparently found.
Though the impurities in the
zinc were probably too slight
to influence the reaction in
any way, yet the amount of
zinc, which was purposely
small in order to avoid the
introduction of large quan-
tities into the solutions to
be titrated, was perhaps in-
sufficient for reduction. It
is not unfair to suppose that
a more complete reduction
would have given the same
ratios between the precipi-
tated antimony and that
evolved as hydride. As to
the inequality between the
amounts of antimony taken
and found, we think that
this may be explained by the
errors in the titration of such
small amounts.
In spite of these criticisms of the above results, it seems to us that
the study points to the conclusion that practically all of a small amount

"

*=-

150-

^

/.

/

/

/

/

/

lUO

/

f

/

/

/

/

7

/

bO

/

/

/

11

-*

SANGER AND GIBSON. — DETERMINATION OF ANTIMONY. 723

of antimony, when introduced into the Marsh apparatus, can be con-
verted to the hydride and collected as a metallic mirror. This conclu-
sion is reached by a consideration of the averages, for each series, of
the ratios of antimony precipitated on the zinc to that deposited in the
heated tube. These ratios vary from 7.7 in Series A to 0.8 in'Series J),
and the rate of progression is not the result of chance. Plotting these
results, we have the following curve (Figure 1), in which the ordinates
are the amount of antimony taken and the abscissae the ratios of anti-
mony precipitated on the zinc to that deposited in the heated tube.

From inspection of this curve, it seems to us reasonable to suppose
that amounts of antimony under a milligram when introduced into the
reduction Hask would be practically converted to hydride, and we have
proceeded on this assumption in the development of the method which
follows, since in that method the amount of antimony usually taken
for a determination in no case exceeds one tenth of a milligram and is
usually considerably under that amount.

With the exception of an abstract of a paper by Rieckher,^ we have
found no previous study of the ratio of antimony deposited on the
zinc to that evolved as hydride. In this abstract the ratio is said to
be between 92 to 8 and 96 to 4, i. e., from 11.5 to 24, but the data for
this conclusion are not given. As the original paper of Rieckher is
not accessible to us, we can only assume that the concentration of the
antimony ions must have been much greater than in our experiments.

II. The Temperature and Cross-Section of the
Deposition Tube.

The preparation of pure, gaseous antimony hydride has been accom-
plished in recent years by Stock and Doht 7 and by Stock and Gutt-
mann.^ The pure gas has been shown by these authors to have in
many respects (|uite different properties from those of the various
mixtures of hydrogen and hydride of antimony which have been in
the hands of so many investigators. As to the property which con-
cerns us in this investigation, the decomposition of the hydride by heat,
Stock and Guttmann have shown that the pure gas decomposes slowly
at ordinary temperature, but very readily in the presence of catalytic
agents, notably antimony itself In the case, however, of the mixture
of hydrogen and antimony hydride which comes from a j\Iarsh appa-
ratus containing minimal amounts of antimony, the concentration of

6 Neucs Jalirbuch. d. Pliarin., 28, 10 (1867 ?) ; ref., Jahresbcr. 1867, 255.

7 Ber., 34, 2339 (1901) ; 35, 2270 (1902).

8 Ibid., 37, 885 and 901 (1904).

724 PROCEEDINGS OF THE AMERICAN ACADEMY.

the hydrogen is very great compared with that of the hydride, and
the decomposition would not take place except at a relatively high
temperature.

We have, therefore, no data as to the decomposition point of anti-
mony hydride in such dilution, since investigators of this point, for
example Brunn,^ have dealt with mixtures containing much greater
amounts of antimony. Brunn gives the decomposition point of anti-
mony hydride as 150°; of arsenic hydride as 230°; but the amount
of each in the mixture is not stated. Furthermore, in our work the
differences in the amounts of antimony are relatively so slight in com-
parison with the large amount of diluting hydrogen that the tempera-
tures required for decomposition should not vary within wide limits.
As the amount of antimony to be estimated in mirror form should not
exceed 0.1 mg, of antimonious oxide, the question to be considered is
the lowest temperature at which the hydride from this amount, mixed
with a relatively very large volume of hydrogen, would be decomposed
when passed through the heated tube. At the same time, with a view
to the possibility of separating small amounts of arsenic and antimony
by the difference in decomposition points of the diluted hydrides, we
included in our investigation the decomposition point of diluted arsenic
hydride. While it is well known that antimony hydride, in any dilu-
tion, decomposes at a lower temperature than arsenic hydride at equal
dilution, there were no exact data to guide us.

At the beginning of the study, the tube was heated just behind the
drawn-out portion, or, as we shall call it, the capillary. It was very
soon found that even with small portions of antimony there was a tend-
ency to deposition in the wide part of the tube back of the heated
portion, since the larger surface offers greater chance for deposition of
the rapidly condensing antimony. It was then found necessary to heat
the capillary itself, which had the effect of concentrating the deposit
at the desired place just in front of the heated space.

For determining the decomposition temperature, we used the thermo-
electric method of Le Chatelier, employing for the purpose a couple of
which the wires were platinum and an alloy of platinum with ten per
cent of rhodium. The couple was standardized by determining the
electromotive force (in micro- volts) produced by heating the junction
in the vapor of boiling naphthaline (218°), diphenylamine (302°), and
sulphur (445°). With these three boiling points as ordinates and the
corresponding electromotive forces as abscissae, a perfectly straight
line was obtained. As the temperature to be measured did not exceed
700° or fall below 200°, it w.s justifiable to extend this line and use

8 Ibid., 22, 3202 (1889).

SANGER AND GIBSON. — DETERMINATION OF ANTIMONY. 725

it as a means of determining the temperatures by observation of the
electromotive forces produced.

The study, as far as it concerned the separation of arsenic and anti-
mony, is not completed, hence the results are reserved for another
publication. Sufficient data were obtained to show that there was a
possibility of separating arsenic and antimony by the difTovence in
decomposition points of their diluted hydrides, and the investigation
will be continued in this laboratory. Concerning the arsenic hydride,
it will be sufficient to say that an amount of diluted hydride corre-
sponding to 0.04 mg. of arsenious oxide is completely decomposed at
340° if the length of capillary heated is 3.5 cm. ; at 410° if the length
is 2 cm. ; and at about 450° if the length is 1 cm. Conversely, no
arsenic is deposited from this amount at 330° with a heating length of

I cm. ; none at about 300° if the length is 2 cm. ; and none at about
250° if the length is 3.5 cm.

We were unable to get as definite results on the decomposition of
antimony hydride, since the difficulty in deposition of the antimony
mirror on the glass tubing used, which was afterwards solved as ex-
plained later, prevented the results from being uniform. We think,
however, that we are safe in saying that amounts of hydride from 0.1
mg. antimonious oxide and under are entirely decomposed at a tem-
perature of 300° and a heating length of 2 cm.

Having shown that practically all the antimony may be evolved as
hydride from the small amounts to be used in our work, and that the
hydride, diluted with hydrogen, can be entirely decomposed by heat-
ing the capillary through which the gases pass at a temperature which
is easily controlled, we then proceeded to develop a method for estimat-
ing minimal amounts of antimony.

The Apparatus.

The apparatus ^^ is essentially the same as that proposed by Sanger
for the estimation of small amounts of arsenic. Slight modifications
of this have been introduced by subsequent workers, many of whom
have overlooked the original article. As shown in the figure, the parts
comprise a constant hydrogen generator, two reduction flasks, and two
heating tubes, so that duplicate determinations may be carried out at

^'^ This apparatus, wliic^li is shown in Figure 2, is essentially the same as that
described, but not illustrated, in the paper of Sanger (1891) above referred to.
An apparatus of practically the same principle is shown on page 220 of Volume

II of tlie Final Eeport of the Koyal Commission on Arsenical Poisoning (Appen-
dix 22, Report to the Commission 1)3' McGowan and Finlow on the methods em-
ployi'd in testing for arsenic) ; London, Eyre and Spottiswoode, 1903.

726

PROCEEDINGS OF THE AMERICAN ACADEMY.

5-

2!
O

H

o
<

>-)

;^

o

3
«

O
b

CD

H

«

SANGER AND GIBSON. — DETERMINATION OF ANTliMONY. 727

the same time. The generator which we have found most convenient
is one proposed by Richards, and is similar to the forms described by
him some years ago.^^ Any form of constant generator will answer
which provides for withdrawal of the spent acid without disconnection.
The zinc in the generator is conveniently sensitized, according to the
suggestion of Gooch,!^ by brief treatment with a solution of cupric
sulphate and subsequent washing. The acid is sulphuric, at a dilution
of one to eight. The hydrogen from our generator shows no arsenic
or antimony when run for hours at a time.

As the hydrogen wnth which the antimony hydride is heated must
contain no hydrogen sulphide, as hereafter shown, the hydrogen from
the generator is passed through a ten per cent solution of cupric sul-
phate contained in an Allihn or other suitable washing bottle. From
this, the hydrogen, which needs no further purification, passes to a
Y-tube with two glass stopcocks. To these stopcocks are attached
the reduction flasks, which are wide-mouth bottles of 60 to 75 c.c.
capacity. These are fitted with a pure rubber stopper with three holes.
Through one hole passes, to the bottom of the bottle, a right-angle
tube connected with the stopcock ; through the second a tube pass-
ing nearly to the bottom of the bottle and extending 3 to 5 cm.
above the stopper. The upper end of this tube is open, the loAver
somewhat constricted. In the tube is placed a small funnel, blown
from narrow tubing, through which the solution to be reduced is added.
The third hole in the stopper carries the right-angle deliver)^ tube for
the hydrogen which passes just below the stopper. On its upper end is
a rubber stopper over which is placed a 15 cm. (total length) tube filled
with calcic chloride in fused sticks. We have found it convenient to
half fill the tube with calcic chloride, and then to introduce a second,
smaller tube filled with the chloride. By this arrangement the rear
portion of the chloride, which soon becomes moist, may be frequently
and conveniently renewed without disturbing the rest.

To the calcic chloride tube is connected the hard glass reduction
tube drawn out to a straight capillary and ending in a capillary point.
This tube is supported throughout its length by three adjustable brass
hooks (No. 6 gauge, 4.1 mm.).' The middle hook, which has a shank
10 cm. long, is fastened to a stand by the ordinary double clamp. On
the top of the shank and about two thirds the distance from the
clamped end are soldered two ordinary screw connectors at right angles
to the shank. The other hooks, which are somewhat longer than the
first, are bent at right angles in the plane of the table and their shanks

." Amer. Clicm. Jour., 20. 180 (1808).
" Amer. Jour. Sc-i., (3) 48, 202 (1894).

728 PROCEEDINGS OF THE AMERICAN ACADEMY.

pass in opposite directions through the connectors, in which they can
be clamped by the screws. The end hooks are thus capable of being
raised or lowered or of being moved laterally, so that the combination
of the three hooks will support any tube and capillary.

We found it best to protect the capillary from direct contact with
the flame, and at the same time to secure a more uniform heating by
enclosing it in a brass tube or collar which is slipped over the capillary
and rests on the two anterior hooks of the support. This collar is
5 cm. long, with an outer diameter of 6 mm. and an inner of 4 mm.
It is heated towards the anterior end by the tip of a flame 5 to 6 mm.
high from a burner with a good air supply and protected by a conical
chimney. We assume that under these conditions the capillary is
heated, through a space of 3 cm., at about 500°.

The Preparation of Standard 3Iirrors.

A standard solution of antimony was made by dissolving 2.3068 gr.
of recrystallized tartar emetic in water and making up to one liter.
This solution (I) contains 1 mg. of antimonious oxide in each cubic
centimeter. Of solution I, 10 c.c. were diluted to a liter, giving a
solution (II) containing 0.01 mg. per c.c. The tartrate offers the
most convenient and accurate solution, and we satisfied ourselves
that the presence of the tartrate ions had no effect whatever on the
deposition of the mirror. The strength of solution I was also checked
by analysis.

The zinc used in the reduction flask was the same as that used in
the generator, but in smaller pieces, averaging perhaps 1 cm. in their
longest dimension. The weight used was from three to five grams.
This zinc, which is obtained of the New Jersey Zinc Company of New
York, contains not over 0.019 per cent of lead and not more than
0.013 per cent of iron ; hence the evolution of hydrogen by its contact
with dilute sulphuric acid is slow. Platinum or other sensitizing agents,
either in form of foil or as a deposit on the zinc, cannot be used, as we
have proved by trial, since they show a tendency to hold back anti-
mony even greater than in the case of arsenic. ^-^ We had recourse,
therefore, to hydrochloric acid, in a dilution of one to ten, of which we
use exactly 20 c.c. for each run. The hydrochloric acid, which is ob-
tained of Messrs. Baker and Adamson, of Easton, Pa., contains no
antimony, and only about 0 02 mg. of arsenious oxide per liter, an

^^ The discussion as to tlie effect of otlier Jiietais on the evolution of arsenic
hych'ide has heen revived in recent years through the endeavors to increase tiie
delicacy of the Marsh test for arsenic. This question, as ai)i)lied to arsenic and
antimony, will he taken up hy one of us in a fulure jiaper.

SANGER AND GIBSON. — DETERMINATION OF ANTIMONY. 729

amount which is inappreciable in our work on antimony.^'* By u.se of
hydrochloric acid and purification of the hydrogen from the generator,
there is no necessity for purification of the hydrogen from the reduc-
tion flask, provided sulphur compounds reducible to hydrogen sulphide
are absent. Whenever the hydrogen contains hydrogen sulphide, the
deposit in the heated tube is more or less reddish-yellow in color, due
presumably to the presence of antimonious sulphide.

The fused sticks of calcic chloride used for drying (Merck) dissolved
clear in water, and the solution showed an alkalinity of not over 0.8
per cent. We have seen no reason to believe that hydride of anti-
mony is held back by this preparation, nor has there been any loss of
antimony observed from an unduly moist condition of the chloride.
AVe have, however, kept the chloride as active as possible by refilling
the rear half of the tube with fresh chloride after every half dozen runs,
as explained, or when the accumulation of moisture becomes noticeable.
When not in use, the tubes are kept stoppered.

The selection of hard glass tubing is a matter of the highest im-
portance for the success of the method. We used at first a German
glass, source not known to us, which had been used in arsenic work
without apparent disadvantage. This glass had a slight brown color
after long ignition. Antimony mirrors deposited on this, under the
conditions about to be described, were often white and not clearly
defined. We next tried a sample of American glass, but this gave the
brown color on ignition still more, and the deposits of antimony were
entirely white. Next a Jena glass, which on ignition gave the well-
known opaque appearance, and on which the mirrors were also entirely
white. Finally we resorted to a glass of Kavalier, which did not give
any color or opacity on long heating. The deposits of antimony on
the capillaries drawn from this glass were satisfactory, and it was used
in the prepai'ation of the standard mirrors. ^^

^* Tliis would mean not over 0.00004 mg. of arsenic in the amount of hydro-
chloric acid used, which is beyond the limit of the delicacy of the process as
applied to arsenic.

^5 A cursory qualitative examination of the different samples of tubing showed
no marked points of difference except tliat the fourth tubing contained no barium,
while the others did. The amount of barium in the others was proportional to the
degree of change in appearance of the mirror produced on the samples. Lack
of time prevents an investigation on this point, and an opinion as to the influence
of the barium, if any, would be mere conjecture ; as, for example, whether the
barium oxide could act catalytically in causing an oxidation of the antimony,
since it seems probable that the white deposit is due to an oxide of antimony. In
the absence of any definite knowledge on the matter one can only determine the
availability of a sample of glass by actual trial.

730 PROCEEDINGS OF THE AMERICAN ACADEMY.

The glass tubing varies from 5 or G mm., inside diameter, to 7 or
8 mm. outside. The inside of the tube should be thoroughly cleaned
before use. For this purpose a bundle of tubes is entirely immersed
for some time in concentrated sulphuric acid to which sodic chromate
has been added. The tubes are then washed, dried, and stored away
from dust. In drawing out the capillary, care should be taken to draw
to the same outside diameter and as nearly as possible to the same
length. If one starts with tubes of as nearly equal size as possible,
and observes these conditions, a capillary of nearly constant bore is
obtained. It is on this uniformity of bore that the gradation of the
standards depends. One should therefore at least draw the tubes to
the same diameter, since this condition is easily governed and is the
chief factor in determining the bore. We have used for this purpose a
Brown and Sharpe wire gauge, and have drawn the tubing to gauge
No. 13, which corresponds to 1.8 mm., or 0.072 inch.

In beginning the run, three to five grams of zinc are placed in the
reduction flask, which is then attached at one end to the stopcock of
the constant generator, at the other to the drying tube. To the latter
is then attached the ignition tube, with the collar over the capillary.
20 c.c. dilute hydrochloric acid are added through the funnel tube,
and the apparatus may be tested for tightness by closing the end of
the capillary with the finger while adding the acid. The hydrogen
is then turned on from the generator, and, when the air is expelled, is
lighted at the end of the capillary and turned down to a height of
about one millimeter. It is important that this height be maintained
as nearly as possible throughout the run and that the flame should
burn steadily, since an irregular flow of hydrogen results in an uneven
deposit of antimony. After the apparatus has been in action for five
or ten minutes, the measured amount of antimony is added to the
reduction flask through the funnel, which is then rinsed into the, flask
with a little water. No air is introduced into the apparatus if the
funnel is sufficiently small compared to the tube in which it is set, and
if the lower end of the tube is constricted.

The deposit of antimony makes its appearance in five to ten min-
utes, and is completely deposited in thirty, though we have usually
waited forty to fifty minutes, to avoid the possibility of loss. We have
satisfied ourselves that all the antimony is deposited from the hydride
at this point, since a further heating along the tube gives no mirror.

The tubes containing the mirrors are sealed at each end and
mounted in a frame, as shown in the plate. This firame is 185 mm.
by 70 mm. outside, 135 by 35 mm. inside, and made of blackened
wood G mm. in thickness. The tubes are fastened in holes passing

SANGER AND GIBSON. — DETERMINATION OF ANTIMONY. 731

through the upper and lower sides of the frame. As the antimony
mirrors are aflected by moist air, and in the course of time by lii^ht,
we take the precaution to seal the tubes and to keep the set of stand-
ards in the dark. The deterioration of the standards with time is not
a serious objection to the method, since a fresh set can readily be made
when desired. ^^

The amounts of antimony used by us in the set of standards shown
in the plate are, in milligrams of antimonious oxide (SbjOs) as follows :
().(>(>5; 0.01; 0.015; 0.02; 0.025; 0.03; 0.035; 0.04; 0.045; 0.05;
O.OG ; 0.07. Above 0.07 mgr. it is of no advantage to make a mirror,
as the recognition of the dilferences in the higher mirrors is difficult.
These mirrors may be used as standards when viewed by reflected
light, as shown in the upper set of the plate, but it is much better to
use transmitted light. This is best arranged by mounting the frame
in a box, similar in form to the fluoroscope, which may be of wood or
metal. This box, about 25 cm. long and open at each end, is larger at
the bottom than at the top, and carries a rabbet at the bottom through
which the frame can be slipped. It is provided at the top with means
of shading the eyes against all light except that which comes through
the set of mirrors. If the box is held against a white surface, the mir-
rors gain greatly in sharpness, and smaller differences may be in this
way detected when comparing mirrors obtained in an analysis. The
lower part of the plate shows the set of standards when viewed by this
device.

Analysis of Solutions containing Antimony.

To test the availability of the standard mirrors, a series of seven
analyses was made of solutions in which the amounts of antimony
were unknown to the analyst. The solutions were weighed to the
second decimal place in a side-neck test tube of about 30 c.c. capacity.
After the apparatus had been running for about ten minutes, a few
drops of the solution were added to the reduction flask. If no mirror
appeared within ten minutes, a larger portion of the solution was added,
and if this again gave no mirror, the addition was continued. After
the appearance of the mirror, the run was continued for thirty or forty
minutes, until there was no probability of further deposit. By re-
weighing the test tube after the addition of the portion or portions
which produced the mirror, the amount of solution taken was deter-
mined. The mirror obtained from this amount was then compared

" The suggestion of Panzer (Clieni. Centralbl., 74 (1),821 (1903), to seal stand-
ard arsenic mirrors with pliosphorus pentoxide could probably be applied with
advantage to the set of antimony mirrors.

732

PROCEEDINGS OF THE AMERICAN ACADEMY.

with the standards and the amount of antimony read off. From the
amount in the aliquot portion, the amount in solution was calculated.

Very often the mirror obtained from a given portion of the solution
will be found too small or two large for estimation. In this case one
can readily determine the proper amount of solution to be used.

The following table shows the results of these analyses :

TABLE II.

No. of
Analysis.

Standard

Solution

used.

•

C.c. of

Solution

taken .

SboOj
taken.

Total

Weight

Diluted

Solution.

Weight

Diluted

Solution

taken

for

Analysis.

Mirror
Reading.

Sb„03

found.

Sb„0.,
found,
Mean.

Per

ceut
SbjOs
found.

mg.

gm.

gm.

mg.

mg.

mg.

2

II

5

0.05

24.49

a) 5.56

b) 13.93

0.014
0.027

0.06
0.05

0.055

110

1

II

10

0.10

25.36

«) 11.64
b) 13.72

0.038
0.042

0.08
0.08

0.080

80

6

II

30

0.30

29.95

a) 3.14

b) 2.40

0.035
0.025

0.33
0.31

0.320

107

7

I

0.5

0.50

24.48

(/) 1.91
b) 1.G2

0 043
0038

0.55
0.57

0.560

112

3

I

1.0

1.00

23.94

a) 0.83

b) 1.58

0.038
0.048

1.10
0.73

0.915

92

4

. I

1.5

1.50

20.22

<i) 0.72
b) 0.79

0.040
0.045

1.46
1.49

1.475

98

5

I

2.0

2.00

23.21

a) 0.45
/') 0.C8

0.038
0.048

1.96
1.64

1.800

90

A

verage pe

rcentage

98

The results are as good as can be expected, considering the small
amounts of antimony under estimation and the difficulty of reading the
mirrors more accurately than within 0.002 or 0.003 mgr. The demand
on the method made by these analyses is much more severe than would
occur in actual practice. It is safe to say that the method will give a
close approximation to the amount of antimony present in a given
product, within the limits for which it is intended. It will serve also
as a means of quickly, though roughly, estimating amounts which would
require the ordinary analytical methods for an exact determination.

SANGER AND GIBSON. — DETERMINATION OF ANTIMONY. 733

As to the delicacy of the process in the detection of minimal amounts
of antimony, a mirror corresponding to 0.005 mg. can be detected and
identified with certainty. With 0.001 mg. a faint deposit is seen. Yet
the differentiation of amounts under 0.01 mg. presents some difficulty.
Possibly the solution of the problem of how to sensitize the zinc prop-
erly in the Marsh process as applied to arsenic will enable one to
detect smaller amounts of antimony with certainty. The question of
the delicacy of the process has not so much concerned us, however,
as its practicability. Its application to the determination of small
amounts must of course be worked out for each particular problem.
This does not come, however, within the scope of the present investi-
gation, but certain applications of the method are under consideration
in this laboratory.

Harvard University, Cambridge, Mass.,
January 1, 1907.

Sanger and Gibson — Determination of Antimony.

STANDARD ANTIMONY MIRRORS IN MILLIGRAMS OF SB^Os.

Proc. Amer. Acad. Arts and Sciences. Vol. XLII.

Proceedings of the American Academy of Arts and Sciences.
Vol. XLII. No. 29. — August, 1907.

RECORDS OF MEETINGS, 1906-1907.

REPORT OF THE COUNCIL: BIOGRAPHICAL NOTICE.
Edward Atkixsoj^. By Thomas Wentwokth Higginson.

OFFICERS AND COMMITTEES FOR 1907-1908.

LIST OF THE FELLOWS AND FOREIGN HONORARY
MEMBERS.

STATUTES AND STANDING VOTES.

RUMFORD PREMIUM.

INDEX.

(Title Page and Table of Contents).

RECORDS OF MEETINGS.

Nine hundred and sixty-seventh Meeting.

October 10, 1906. — Stated Meeting.

The Academy met at its House.

The President in the chair.

There were present twenty-three Fellows.

The Corresponding Secretary read the following communi-
cations : From the University of Pennsylvania, inviting the
Academy to send a representative to the dedication of the new
building of its engineering department; from the Curator of
the Reale Universita Napoli, offering for sale collections of speci-
mens of the materials ejected in the recent eruption of Vesuvius;
from the American Philosophical Society, presenting the medal
struck by order of the Congress of the United States in honor
of the two hundredth anniversary of the birth of Benjamin
Franklin ; one from the same Society acknowledging the ad-
dress presented by the Academy on the occasion of the above
celebration ; from the Director of the Observatorio Astronomico
de la Plata, announcing the annexation of the Observatorio to
the Universidad Nacional ; from the family of Ludwig Boltz-
mann, announcing his death, and also the same announcement
from the University of Vienna ; from the Museo Nacional,
Mexico, announcing the death of Manuel Urbina, chief of the
department of natural history.

The following deaths were announced by the Chair : —

Edward J. Young, Resident Fellow in Class III, Section 2;
Bennett H. Nash, Resident Fellow in Class III, Section 2;
Ludwig Boltzmann, Foreign Honorary Member in Class I,
VOL. xm. — 47

738 PROCEEDINGS OF THE AMERICAN ACADEMY.

Section 2 ; J. W. A. Kirchlioff, Foreign Honorary Member in
Class III, Section 2.

Professor G. F. Swain was appointed by the President to
represent the Academy at the dedication of the building of
the engineering department of the University of Pennsylvania.

At the request of the President, Professor "Ware gave some
information in regard to the ventilation of the Meeting-room,
with its estimated cost. After some discussion, on motion of
the Recording Secretary, the whole subject was referred to the
President, with full power.

The following communications were given : —
" An Ascent of Orizaba, Mexico," by Professor John E.
Wolff ; " On Some Elements of Conservatism in Ancient
Greece," by Professor Herbert Weir Smyth.
The following paper was presented by title : —
Contributions from the Gray Herbarium of Harvard Univer-
sity. New Series. — No. XXXIII. "Revision of the Genus
Spilanthes," By Albert Hanford Moore. Presented by B. L.
Robinson.

Nine hundred and sixty-eightli Meeting.

November 14, 1906.

The Academy met at its House.

The President in the chair.

There were present twenty-two Fellows.

The Corresponding Secretary read the following letters :
From the Delegation pour 1' Adoption d'une Langue Auxiliaire
Internationale, offering to members of the Academy the re-
sources of the Delegation for the propaganda in the United
States ; from the Board of Managers for Massachusetts, of the
Jamestown Exposition, asking for the loan of objects of his-
torical interest for display at the Exposition.

The following communications were given : —

" The Ancient Coniferous Flora of New England," by Pro-
fessor E. C. Jeffrey ; " The Ancient Water-levels of the Cham-
plain and Hudson Valleys," by Professor J. B. Wood worth.

The following papers were read by title : —

RECORDS OF MEETINGS. 739

"Description of Bermuda Hydroids." By Edgar Davidson
Congdon. Presented l)y E. L. Mark.

"The Transmission of RiJntgen Rays through ^Metallic Sheets."
By John Mead Adams. Presented by John Trowbridge.

Nine hundred and sixty-ninth Meeting.

December 12, 1906.

The Academy met at its House.

The PiiESiDENT in the chair.

There were present twenty-two Fellows.

The Corresponding Secretary read a letter from Mr. Henry
H. Edes, presenting to the Academy a photographic copy of
the certificate of Membership in the Academy, which was given
in 1781, to Benjamin Franklin.

On motion of the Corresponding Secretary, it was

Voted, That the thanks of the Academy be tendered to Mr.
Edes for his gift.

The Chair announced the following deaths : —

Samuel Cabot, Resident Fellow in Class I, Section 3 ; F.
Brunetiere, Foreign Honoiary Member in Class III, Sec-
tion 4.

A proposition from the Council for the establishment of an
emeritus list of Resident Fellows was read ; this proposition,
requiring a change in the statutes, was referred to a committee
consisting of Charles P. Bowditch, A. Lawrence Rotch, William
Watson.

The followinor recommendation from the Council was read
by the Corresponding Secretary: —

That an appropriation of five hundred dollars (8500) be made
from the income of the Publication Fund, for the use of the
Publishing Committee for the remainder of the year.

The following communication was given : —

" The Surface Temperature of Mars (from a New Determina-
tion of the Solar Heat received by it)." By Professor Percival
Lowell.

The following papers were read by title : —

740 PROCEEDINGS OF THE AMERICAN ACADEMY.

" An Electric Wax-Cutter for Use in Reconstruction." By
E. L. Mark.

" On the Magnetic Behavior of the Finely Divided Core of
an Electro-magnet or of a Transformer while a Steady Current
is being established in the Exciting Coil." By B. O. Peirce.

" The Sensation of Loudness." By W. C. Sabine.

Nine hundred and seventieth Meeting.

January 9, 1907. — Stated Meeting.

The Academy met at its House.

The President in the chair.

There were present twenty-five Fellows.

On the recommendation of the Council, at the request of the
Chairman of the Publication Committee, and with the approval
of the Treasurer, it was

Voted, To appropriate the sum of five hundred dollars (S500)
from the income of the Publication Fund for the use of the
Publication Committee for the remainder of the year.

On motion of the Chairman of the Rumford Committee,
it was

Voted, To appropriate the sum of three hundred and seventy-
five dollars ($375) from the income of the Rumford Fund for
the use of the Rumford Committee in the furtherance of
research.

The report of the Committee on Amendments to the Statutes
was read and accepted, and, in accordance therewith, it was

Voted, To amend the vStatutes as follows : —

Chapter I, Section 2, line 1. After the word "Fellows"
add " residing in the Commonwealth of Massachusetts."

This amendment was passed by a vote of three-fourths of
the members present, there being eighteen (18) affirmative
votes.

The following communications were given : —

" The Meteorology of the North and South Polar Zones." By
R. DeC. Ward.

"The Corpuscular Theory as applied to Electric Conduction
in Gases." By Theodore Lyman.

RECORDS OF MEETINGS. 741

The following papers were read by title : —

" On Linear Differential Equations of the Parabolic Type."
By M. M. Smith. Presented by Maxirae IlOcher.

" The Spermatogenesis of the Myriapods. V. On the Sper-
matocytes of Lithobius." By Maulsby W. Blackman. Pre-
sented by E. L. Mark.

" Concerning the Adiabatic Determination of the Heats of
Combustion of Organic Compounds, especially Sugar and Ben-
zol." By T. W. Richards, L. J. Henderson, and H. L. Frevert.

" Concerning Position Isomerism and Heats of Combustion."
By L. J. Henderson. Presented by T. W. Richards.

" The Determination of Small Amounts of Antimony by the
Berzelius-Marsh Process." By C. R. Sanger and James A.
Gibson.

"The Determination of Arsenic in the Urine." By C. R.
Sanger and Otis F. Black.

" The Determination of Arsenic by the Guthzeit Method."
By C. R. Sanger and Otis F. Black.

Nine hundred and seventy-first Meeting.

February 13, 1907.

The Academy met at the Walker Building of the Massachu-
setts Institute of Technology.

The President in the chair.

There were present twenty-five Fellows and eighteen guests.

The following letters were read ; From the Soci^t^ Imperiale
russe de Geographic, on the occasion of the eightieth anni-
versary of M. Pierre de Semenov ; from E. van Everdingen,
announcing his appointment as Director of the Netherlands
^leteorological Institute ; from the Academic de Macon, enclos-
ing the medal of its centennial ; from the Seventh International
Zoological Congress, inviting the Academy to be represented by
delegates at its meeting in Boston, August 19 to 23, 1907.

The President announced that the Rumford Medal had been
awarded to Professor Ernest Fox Nichols for his researches on
radiation, particularly on the pressure due to radiation, the
heat of the stars, and the infra-red spectrum. He then called

742 PROCEEDINGS OF THE AMERICAN ACADEMY.

upon Professor Charles R. Cross, Chairman of the Rumford
Committee, to state the grounds on which the award was
made.

Professor Cross gave a brief account of Professor Nichols'
researches, after which the President, in the name of the Acad-
emy, presented the medal to Professor Nichols, who made an
appropriate reply expressing his appreciation of the high honor
which had been conferred upon him.

Professor Nichols then showed experiments demonstrating
the pressure of rays of light.

Remarks were made on this subject by Professor Webster,
who concluded with the motion that a vote of thanks be given
to Professor Nichols for his admirable experimental demonstra-
tions.

The following papers were presented by title : —

" The Kathode-luminescence of Fluorite." By Harry W.
Morse. Presented by John Trowbridge.

" On the Self and Mutual Inductance of Cylindrical Sole-
noids." By A. G. Webster.

Contributions from the Gray Herbarium of Harvard Univer-
sity. New Series, — No. XXXIV. I. "New Species of Sene-
cis and Schoenocaulon from Mexico." By J. M. Greenman.
II. " New or otherwise noteworthy Spermatophytes, chiefly from
Mexico." By B. L. Robinson. III. "New Plants from Guata-
mala collected by C. C. Deam." By B. L. Robinson and H. H.
Bartlett. IV. " Diagnoses of New Spermatophytes from Mex-
ico." By M. L. Fernald. Presented by B. L. Robinson.

Nine hundred and seventy-second Meeting.

March 13, 1907. — Stated Meeting,

The Academy met at its House.

The President in the chair.

There were present twenty-one Fellows.

Letters were read from Henry S. Pritchett, Henry G. Denny,
David W. Cheever, and Jeremiah Smith, resigning Fellowsliip ;
from the Michigan Agricultural College, inviting the Academy
to be represented by delegates at its fiftieth anniversary, May

RECORDS OF MEETINGS. 743

28-31, 1907 ; from the Smithsonian Institution, informing the
Academy of the election of Charles Doolittle Walcott as its
Secretary ; from G. Capellini, inviting the Academy to partici-
pate in the celebration of the three hundredth anniversary of
the death of Ulisse Aldrovandi, June 12, 1907, at Bologna ;
also, printed communications regarding the adoption of an inter-
national language.

On motion of the Recording Secretary, it was unanimously

Voted, To invite Dr. William Everett, Professor Amos E.
Dolbear, and Mr. Henry G. Denny to attend the meetings of
the Academ}'-, and to make use of the library.

The Chair announced the following death : —

Dimitri Mendeleeff, Foreign Honorary Member in Class I,
Section 3.

The following gentlemen were elected Members of the
Academy : —

William Zebina Ripley, of Newton, as Resident Fellow in
Class HI, Section 3 (Political Economy and History).

Edward Henry Hall, of Cambridge, as Resident Fellow in
Class HI, Section 4 (Literature and the Fine Arts).

William Coolidge Lane, of Cambridge, as Resident Fellow in
Class III, Section 4 (Literature and the Fine Arts).

Magnus Gustav Retzius, of Stockholm, as Foreign Honorary
Member in Class II, Section 3 (Zoology and Physiology), in
place of the late Albert von KoUiker,

Hermann Diels, of Berlin, as Foreign Honorary Member in
Class HI, Section 2 (Philology and Archaeology), in place of
the late J. W. A, Kirchhoff.

The President appointed the following Councillors to act as
Nominating Committee : —

William T. Sedgwick, of Class II.
Elihu Thomson, of Class I.
Andrew McF. Davis, of Class III.

The following Communications were given : —

Professor S. P. Sharpies, " Cobalt and Silver Deposits of
Cobalt, Canada."

Professor D. W. Johnson, " The Volcanic Necks of the Mt.
Taylor Region, New Mexico" (by invitation).

744 PROCEEDINGS OF THE AJIERICAN ACADEMY.

The following papers were read by title : —

" The Process of building up the Voltage and Current in a
Long Alternating-Current Circuit." By A. E. Kennelly.

" High Electromotive Force with its Application to Spectrum
Analysis." By John Trowbridge.

Nine htrndrecl and seventy-third Meeting.

April 10, 1907.

The President in the chair.
There were present sixteen Fellows.

The Corresponding Secretary read the following letters : From
Edward H. Hall, William C. Lane, and William Z. Riple}',
acknowlecisfing election as Resident Fellows ; from Hermann
Diels, acknowledging election as Foreign Honorary Member ;
from Amos E. Dolbear and Henry G. Denny, thanking the
Academy for its invitation to attend the meetings and to use
the library ; from the Geological Society of London inviting the
Academy to appoint a delegate to attend its centennial cele-
bration, September 26, 27, and 28, 1907 ; from the Comite
Geologique de la Russie, announcing the death of M. Nicholas
Sokolow ; from Columbia University in the City of New York,
announcing the Loubat prizes to be awarded in 1908.
The Chair announced the following death : —
Marcellin Berthelot, Foreign Honorary Member in Class I,
Section 3.

The following delegates were appointed by the chair : —
Professor Ephraim Emerton (Professor Angelo Celli of Rome,
alternate), to attend the celebration at Bologna of the three
hundredth anniversary of the death of Ulisse Aldrovandi,
June 12, 1907 ; President James Burrill Angell, to attend the
celebration at Lansing, Michigan, of the fiftieth anniversary of
the Michigan Agricultural College, May 28 to 31,1907; Pro-
fessor Edward Laurens Mark, to attend the Seventh Liter-
national Zoological Congress at Boston, August 19 to 23, 1907.
The following communications were given : —
" On the Physiological Basis of Illumination." By Dr. Louis
Bell.

RECORDS OF jrEETINGS. 745

" Meteorological Observations in 1906 above the Tropical and
Equatorial Atlantic." By Professor A. Lawrence Rotcb.
The following paper was presented by title : —
" The Demagnetizing Factors for Cylindrical Magnets of Dif-
ferent Dimensions." By C. L. B. Shuddemagen. Presented by
B. O. Peirce.

Nine hundred and seventy-fourth Meeting.

May 8, 1907. — Annual Meeting.

The President in the chair.

There were present twenty-two Fellows.

Letters were read from E. F. Sawyer and J. S. Kingsley,
resigning Fellowship ; from Gustav Retzius, acknowledging
election as Foreign Honorary iNIember ; from the New York
Academy of Sciences, inviting the Academy to be represented
at the celebration of the two hundredth anniversary of the birth
of Carl von Linne, and also to contribute an official document
appreciative of the work of Linn^.

On motion of the Recording Secretary it was

Voted, That the appointment of Delegates to the celebrations
of the Geological Society of London and the New York Acad-
emy of Sciences be intrusted to the President.

The Chair announced the death of Sir Michael Foster,
Foreign Honorary Member in Class II, Section 3.

The annual report of the Council was read.i

The annual report of the Treasurer was read, of which the
following is an abstract : —

General Fund.

Receipts.

Investments $1,683.01

Assessments 1,880.00

Admission fees 40.00

Rent of offices 1,200.00 81,803.01

Expenditures.

General expenses $3,603.47

Library 1,199.54 84,803.01

1 See p. 761.

746 PROCEEDINGS OF THE AMERICAN ACADEMY.

RuMFORD Fund.

Receipts.
Balance, April 30, 1906 $ 451.23

Investments, etc 2,614.75 $3,065.98

Expenditures.

Research . . , $1,490.00

Publication 788.54

Library 149.35

Charged to reduce book value of stocks . . . 451.23 $2,879.12

Balance, April 30, 1907 . . 186.86

$3,605.98

C. M. Warren Fund.
Receipts.

Balance, April 30, 1906 $ 940.06

Investments 347.74 $1,287.80

Expenditures.

Research $ 450.00

Vault rent 4.00

Premium on bonds charged off 50.00

Accrued interest on bonds bought .... 20.83 $ 524.83

Balance, April 30, 1907 762.97

$1,287.80

Publication Fund.

Receipts.

Balance, April 30, 1906 $ 961.68

Investments 2,854.50

Sale of publications • . 130.35

Authors 179.23 $4,125.76

Expenditures.

Publication $3,275.42

Charged to reduce book value of investments . 625.00

Vault rent 12.50 $3,912.92

Balance, April 30, 1907 212.84

$4,125.76

I

RECORDS OF MEETINGS. 747

The following reports were also presented : —

Report of the Librarian.

During the past year the Assistant Librarian and Miss Wyman, as
cataloguer, have been employed in verifying and continuing the type-
written catalogue, begun by Dr. Holden, and also in classifying the
books according to the classification adapted by him to this library.
The subjects, mathematics, astronomy, physics, light, heat, electricity,
chemistry, the useful arts (including engineering), natural history,
geology, mineralogy, and about one-half of meteorology, are entirely
catalogued and classified. This includes all serial publications relating
to the subjects mentioned. There remains to be done, paleontology,
botany, zoology, agriculture, medicine, the moral and pohtical sciences,
and the books and serial publications on general science. As Miss
Wyman can only give two or three hours a day during the coming
year, the catalogue will probably not be completed for some months,
but the thoroughness with which the work has been done compensates
for the length of time taken.

It is very much to be desired that each member of the Academy
should present to the library a copy of any scientific work of which he
is the author. The books on the various subjects were, as a rule, well
chosen in the past, and form what might be called the nucleus to a
valuable library, but some years ago, through lack of funds, it was de-
cided to purchase no more books from the General Fund; therefore
donations are much needed.

The accessions during the year have been as follows : —

By gift and exchange . . .
By purchase — General Fund
By purchase — llumford Fund

Total 148 3422 85 8~ 3663

61 books have been borrowed from the library by 18 persons, includ-
ing 10 Fellows. The library has been consulted many times when no
books were taken.

All the books borrowed during the year have been returned for the
annual examination. Of the books reported as still out a year ago, all
have been returned except 5 (taken out by one person).

The expenses charged to the library are as follows : Miscellaneous,
S40() (which includes S20G.2.") for cataloguing) ; Binding, ;>4I7.65,
General, and S44.70, Rumford, Funds ; Subscriptions, $381.89, General,

Vols.

Parts of Vols.

Pams.

Maps.

Total.

144

2396

85

8

2633

3

690

693

1

336

337

748 PROCEEDINGS OF THE AMERICAN ACADEMY.

and $104.65, Rumford, Funds ; making a total of $799.54 for the Gen-
eral, and $149.35 for the Rumford, Funds as the cost of binding and
subscrii^tions.

A. Lawrence Rotch, Librarian.
May 8, 1907.

Report op the Rumford Committee.

During the past year the Committee has made the followiag grants
in aid of research, from the amount placed at its disposal by the
Academy for that purpose.

Oct. 10, 1906. Professor Arthur A. Noyes, of the Massachusetts
Institute of Technology, for the construction of a calorimeter for the
determination of heats of reaction at high temperatures . . . $300

Professor R. W. "Wood, of the Johns Hopkins University,
for the purchase of quartz lamps (additional appropriation) . 200

Nov. 14, 1906. Professor Norton A. Kent, of Boston Uni-
versity, for the continuation of work on spectral lines (addi-
tional appropriation) 75

Professor L. R. IngersoU, of the University of Wisconsin, for
an investigation of the Kerr Effect in the infra red rays . . . 200

Professor Frederick E. Kester, of the Ohio State University,
for a research on the thermal properties of gases flowing
through porous plugs (additional appropriation) 315

March 13, 1907. Dr. Harry W. Morse, of Harvard Univer-
sity, for his research on fluorescence (additional appropriation) . 400

'Since the last Annual Meeting papers as follows have been published
at the expense of the Rumford Fund. Two additional papers are now
in press.

" Dispersion in Electric Double Refraction." H. L. Blackwell, i\Iay,
1906.

"The Thermal Conductivity of Lead." F. L. Bishop, May, 1906.

" Fluorescence and Magnetic Rotation Spectra of Sodium Vapor, and
their Analysis." R. W. Wood, November, 1906.

" Expansion and Compressibility of Ether and of Alcohol in the
Neighborhood of their Boiling Points." A. W. Smith, January, 1907.

" Concerning the Adiabatic Determination of the Heats of Combustion
of Organic Substances, especially Sugar and Benzol." T. W. Richards
and Messrs. Henderson and Frevert. March, 1907.

" On the Thomson Effect and the Temperature Coefficient of Thermal
Conductivity in Soft Iron between 115° and 204° C." E. H. Hall and
Messrs. Campbell, Serviss, and Churchill. March, 1907.

RECORDS OF MEETINGS. 749

"Concerning Position Isomerism and Heats of Combustion." L. J.
Henderson. March, 1907.

"Temperature of Mars. A Determination of the Solar Heat Re-
ceived." P. Lowell. March, 1907.

" The Transmission of Rontgen Rays through Metallic Sheets." J.
M. Adams. April, 1907.

Reports of progress in their respective researches have been received
from Messrs. A. L. Clark, J. A. Dunne, E. B. Frost, G. E. Hale, W. I.
Humphreys, L. R. IngersoU, N. A. Kent, F. E. Kester, A. B. Lamb,
C. E. Mendenhall, R. S. j\Iinor, H. W. Morse, A. A. Noyes, J. A.
Parkhurst, T. W. Richards, F. A. Saunders, C. B. Thwing, J. Trow-
bridge, R. W. Wood.

At its meeting of January 9, 1907, the Committee voted for the first
time, and at its meeting of February 13, 1907, for the second time, to
recommend to the Academy that the Rumford Premium be awarded to
Edward Goodrich Acheson for the Application of Heat in the Electric
Furnace to the Industrial Production of Carborundum, Graphite, and
other New and Useful Substances.

Charles R. Cross, Chairman.

Mays, 1907.

Professor Cross continued as follows : — .

Mr. President and Gentlemen of the Academy, — In presenting the
claims of i\Ir. Acheson for the Rumford Premium, in view of the char-
acter of the work upon which the recommendation of the Committee is
based, instead of making an independent statement of my own, I will
read a report upon that work which was presented to the Committee
by one of its members, than whom there is none more competent to pro-
nounce an opinion upon any subject concerning applied electricity. I
hardly need to say that I refer to Professor Elihu Thomson.

The report is as follows :

" The early experimenters with the carbon arc fi'om voltaic batteries
found that the temperature developed transcended that of all other
sources of artificial heat, and numerous substances subjected thereto
were found to undergo profound changes. It may sufl&ce to quote from
Silliman's Physics, a text-book in common use some forty years ago,
page .589, paragraph 886 of the edition of 1870, 'Heat of the Voltaic
Arch Deflagration ' : ' Where the positive electrode is fashioned into
a small crucible of carbon, gold, silver, platinum, mercury, and other
substances are speedily fused, deflagrated, or volatilized, with various
colored lights. The fusion of platinum (like wax in a candle) before
the voltaic arch is significant of its intense heat, and still more, the

760 PROCEEDINGS OF THE AMERICAN ACADEMY.

volatilization and fusion of carbon, a result first announced by Professor
Silliman in 1822 and since confirmed by Despretz, who by the union of
the heat of six hundred carbon couples arranged in numerous parallel
series, and conjoined with the jet of an oxyhydrogen blowpipe, and the
heat of the midday sun, focahzed by a powerful burning glass, succeeded
in volatihzing the diamond, fusing magnesia and silica, and softening
anthracite. The diamond is also softened, and converted into a black
spongy mass resembling coke, or, more nearly, the black diamond found
in the Brazilian mines.'

" The fusion of carbon referred to is evidently a mistake, but
the softening of anthracite probably resulted in its conversion into
graphite.

" Upon the advent of the dynamo during the decade of 1870 to 1880,
the ability to obtain and maintain electric arcs with comparative ease
made it possible to apply electric heat to larger crucibles and to note
again the facile conversion of impure varieties of carbon into graphite.
The first attempts to apply electric heating on a fairly large scale in
obtaining new products was probably made by Cowles in 1886, using a
mixture of carbon, aluminum oxide, and copper, whereby there was
formed aluminum bronze. The operation involved the direct reduction
of alumina by carbon, but if this were attempted without the presence
of the alloying metal copper, a carbide of aluminum was formed and no
metal. The operation was rather irregular and uncertain, but stands as
a worthy effort to apply electricity to smelting. The heat generated
in the mass of materials undergoing the operation was due to resistance
of innumerable contacts throughout the granular mass, to the resist-
ance of the materials themselves, and possibly to incipient arcing
between particles.

" Mr. Edward G. Acheson, who had assisted in the Edison Menlo Park
laboratory in 1880 and 1881, and who up to 1889 and later was con-
nected with electric work as engineer, superintendent, or electrician,
began to work with an electric furnace in 1891. In attempting to
'impregnate clay with carbon under the influence of the high heat
obtainable with the electric current ' he noted the formation of a few
bright specks. After having separated out one of these specks, he
drew it across a pane of glass, which it scratched and cut. This led to
further experiments, and a small vial of the new product was taken to
New York under the name 'carborundum,' as Mr. Acheson was labor-
ing under the mistake that it contained carbon and corundum. It was
tried in cutting diamond, with the result that the diamond cutter
bought the material at thirty cents per carat. This was the first sale
of the new abrasive. On finding that it was the silica in the clay

RECOEDS OF MEETINGS. 751

which had reacted with the carbon, sand was substituted for the clay
befoj-e used. Mr. Acheson then planned a furnace substantially the
same as that now used in the manufacture at Niagara, — a central core
of carbon pieces resting on the floor of the furnace and connecting
heavy carbon terminals or electrodes, around which core was packed
the mixed materials to be heated, which in the case of the production
of carborundum are sand, coke-powder, and a little common salt.

"Meeting with troubles and trials, the usual lot of pioneers, and
having his efforts at last crowned with success, the carborundum
manufacture has become a large industry. In 1S94 a steam generat-
ing plant of less than loO horse power was used, and the cost of produc-
tion greatly restricted the applications of the product. Only one half
the product found a market. It was then that, in spite of the opposition
of the directors of his company, Mr. Acheson insisted on removing to
Niagara, so as to manufacture more cheaply with large amounts of
relatively cheap electric energy. The wisdom of this insistence soon
became manifest. One thousand horse power was consumed in a single
carborundum furnace. In 1904 the Carborundum Company had a plant
of five thousand electrical horse power, and produced over seven mil-
lions of pounds of carborundum or silicon carbide.

"Later on Mr. Acheson found that when carborundum was very highly
heated in the furnace in which it was formed the silicon was evapo-
rated from the crystals and graphite left as a pseudomorph. This
observation led the way to experiments and methods which formed the
basis of another large industry carried on by the National Acheson
Graphite Company at Niagara. Its product is plumbago, a graphite
made by heating to a high temperature impure carbon, such as anthra-
cite coal. The silica and clay in the ash apparently provide material
for the chemical changes which result in the conversion, and the im-
purities are themselves finally vaporized out of the mass to a large
extent. That impure carbon was convertible into graphite at high
temperatures was known. Eods of carbon were so converted by the
writer in 1882. The carbon electrodes of arc lights, especially large
arcs, were noted to have been after burning so converted for a small
distance from the ends at the arc, and this was particularly noticeable
at the positive craters of large arcs, which, of course, during burning
attained a temperature limited only by the sublimation of the carbon
itself It is, however, due to Mr. Acheson that the production of arti-
ficial graphite has become a great commercial success. Rods, bars, plates
of carbon converted into Acheson graphite, are now extensively used
in electro-chemical and electro-metallurgical industries, almost to the
complete exclusion of the ordinary moulded carbon formerly used.

752 PKOCEEDINGS OF THE AMERICAN ACADEMY.

The graphite is used as a filler for dry batteries, and is being applied
in place of natural graphite in stove polish, lubrication, foundry facings,
and as a pigment for paints. It is easily reducible to a very fine pow-
der. The graphite is nearly pure, containing about one-half per cent
of impurities when used for electro-chemical electrodes, and about three
per cent when used for paint. A good quality of natural graphite may
be eighty-five per cent pure, and much of it on the market is as low as
forty-five per cent. The solid bars of artificial graphite have a rela-
tively high electric conductivity, estimated at about four times that of
ordinary amorphous carbon rods. They disintegrate in electro-chemical
work at a much lower rate than the former electrodes, for which they
have become the substitute. In some cases the life of the electrode is
increased twelve times. During 1905 the Acheson Graphite Company
produced about two and a half millions of pounds of graphite electrodes
and nearly two miUions of pounds of bulk graphite, made principally
from anthracite coal.

" Two other electric furnace products have been added more recently
as the outcome of Mr. Acheson's experiments. In attempting to reduce
the element silicon by electrically heating an intimatQ mixture of fine
graphite and pure silica, the amount of carbon being only that suffi-
cient to remove the oxygen, Mr. Acheson noted not only the reduction
of the silicon in part, but the production of a quantity of a greenish
gray fluffy substance which, from the circumstances of its production,
he recognized as highly refractory. The manufacture of silicon itself
was turned over to the carborundum company in 1901, since which
time this manufacture has been extended and perfected so that the
element silicon, once a rare curiosity of the chemical laboratory, seen
only in small crystals and in samples of small amount, has become a
commercial product of low price.

" The greenish gray fluffy mass referred to when analyzed gave the
formula SigCoO, and was named siloxicon. It is amorphous and said
to be inert to acid and basic slag, insoluble in fused iron, and packs or
binds itself when pressed and then heated to about 2500 degrees F.
Briquettes can thus be made, resisting the highest furnace tempera-
tures. Attention is now being given to this substance as a material
for crucibles, muffles, fire bricks, fire-resisting linings, etc.

" Mr. Acheson has contributed several papers to technical journals
and societies, an incomplete list being as follows : —

" 'The Influence of the Condenser on Disruptive Discharges.' Elec-
trical World, July 7, 1888.

" ' Disruptive Discharges and their Relations to Underground Cables.'
Before the National Electric Light Association, August 29, 1888.

RECORDS OF MEETINGS. 753

" ' Lightning Arresters and the Photographic Study of Self- Induc-
tion.' Before the American Institute of Electrical Engineers, January
8, 1889.

"'Carborundum: its History, Manufacture, and Uses.' Before the
Franklin Institute, June 21, 1893.

" ' Graphite : its Foundation and Manufacture.' Before the Franklin
Institute, :\Iarch 15, 1899.

" ' Egyptianized Clay.' Before the American Ceramic Society, in
1903.

" ' Discovery and Invention.' Before the Society of ^Mining En-
gineers, Massachusetts Institute of Technology, March 9, 1906.

" He has received some forty United States patents, chiefly relating
to carborundum, graphite, and other products of the electric furnace.

" In conclusion, it may be said that the labors of Mr. Acheson have,
through the agency of electric heat, in furnaces especially designed for
its utilization, and by methods devised by him, provided a new abra-
sive only inferior to the diamond in hardness and toughness, much
harder than emery or carborundum, of which it largely takes the place,
whether used in the form of graded sizes of grains or in slabs, or in
the construction of grinding wheels. His work has also developed a
source of nearly pure graphite aside from the usual mining of this
substance, and which promises to become the principal supply of such
material. It has supplied compact graphite in any form desired, and
of high endurance and purity, for electrodes in electro-chemical in-
dustry. There has resulted from the work of Mr. Acheson a commer-
cial production of the element silicon, before known in small amounts
as a curiosity of the chemical cabinet. This element promises to fill a
need for electric-resistance materials, and for chemical ware unattack-
able by strong acids even when hot, hydrofluoric among the number.
It can be cast in any form in ordinary moulds, and stands rapid changes
of temperature when in the form of crucibles or dishes not too thick.
It oxidizes but slightly in the air even at high temperatures. Lastly,
the work of Mr. Acheson provides a new material, — siloxicon, — the
properties of which promise to render it a very valuable addition to
our resources in high temperature furnace processes. He is to be com-
mended for his persistency, ingenuity, and sagacity in applying the
heating effect of electrical energy to technical problems of the highest
importance."

I can add to this only that the committee is heartily unanimous in
the opinion that the labors of Mr. Acheson fully entitle him to the
honor of the award.

VOL. XLII. — 48

754 PROCEEDINGS OF THE AMERICAN ACADEMY.

It was then

Voted, That the Rumford Premium be awarded to Mr.
Edward Goodrich Acheson for the " Application of Heat in the
Electric Furnace to the Industrial Production of Carborundum,
Graphite, and other new and useful Substances."

Report of the C. M. Warren Committee.

The C. M. Warren Committee beg leave to report that during the
last year they have made the following grants from the C. M. Warren
Fund : —

Professor Walter L. Jennings, of the Worcester Polytechnic
Institute for a research on the acetyl derivatives of rosaniline
and pararosaniline Si 00

Dr. J. Bishop Tingle, of Johns Hopkins University, for re-
search on the hj^drazine derivatives of the camphor oxalic acids 50

Mr. Richard C. Tolman, Research Laboratory of Physical
Chemistry, Massachusetts Institute of Technology, for the con-
struction of apparatus to be used in the measurement of the
difference in electrical potential between the inner and outer
ends of rotating tubes containing salt solutions, this apparatus
to be the property of the American Academy of Arts and Sci-
ences, and to be returned to the C. M. Warren Committee on
the completion of Mr. Tolman's investigations 300

Acknowledgments of these grants and satisfactory reports of progress
have been received.

Leonard P. Kinnicutt, Chairman.

May 8, 1907.

Report of the Publication Committee. '

During the last year there were published of the Proceedings three
numbers of Volume XLI (33-35), and twenty-six numbers of Volume
XLH ; also one biographical notice ; in all, 854 + v pages and eleven
plates. Seven numbers of Volume XLH (13, 17, 21, 22, 24, 25, and
26) were paid for from the income of the Rumford Fund.

Of the Memoirs, one number (Volume XHI, No. 4, pp. 149-179,
plates IX-XXIV) has been published.

Under the ruling that balances of appropriations unexpended at the
end of the year revert to the general funds of the Academy, and that
the proceeds from sales of publications are not available for the pur-
poses of publication except by special vote of the Academy to that
effect, the funds available for publication during the year just closed

RECORDS OF MEETINGS. 755

have been limited to the appropriation of S2600 voted at the annual
meeting', May 9, 19()0, and an additional appropriation of SyOO voted
January 9, 1907; in all, S3 100. However, several authors bore a
portion of the expense of their papers. Sometimes it was convenient
to have the author pay a lump sum to the Academy rather than send
him a separate bill. The money so received aggregated .$179.23, and
was turned over to the Treasurer for credit to the General Publication
Fund. Against this total sum of $3279.23 bills aggregating .$3279.22
have been approved, thus leaving an unexpended balance of one cent.

There are now three papers in press for the Proceedings, the esti-
mated unpaid expense of which is $282, and unpaid bills amounting
to S-27.25.

Bills for publications on account of the Rumford Fund amounting
to $887.01 have been forwarded to the chairman of the Rumford Com-
mittee for approval.

One number of the iMemoirs, estimated to cost for the text $145,
and one number of the Proceedings, estimated to cost $86, are in press
as Rumford papers.

Edward L. Mark, Chairman.

May 8, 1907.

Financial Report of the Council.

The income of the Academy for the year 1907-8, as estimated by
the Treasurer, is as follows :

( Investments $1608

General Fund < Assessments 1800

( Rent of offices 1200 $4608

p ^ Appleton Fund investments . $ 5.56

publication l-UND ) Centennial Fund investments 2178 $2734

Rumford Fund Investments $2547

"Warren Fund Investments $584

The following appropriations are recommended :

General Fund.

House expenses $1200

Library expenses 1600

Books, periodicals, and binding 900

Expenses of meetings ... 250

Treasurer's office - 150 $4100

756 PROCEEDINGS OF THE AMERICAN ACADEMY

RuMFORD Fund.

Research $1000

Periodicals and binding 150

Books and binding 50

Publication 700

To be used at discretion of Committee 264

Unexpended balance of 1906-7 appropriation . . . 186 $2350

C. M. Warren Fund.

Research ' $500

Publication Fund.

Publication $2400

In accordance with the recommendations in the foregoing
report it was

Voted, To appropriate for the purposes named the following
sums : —

From the income of the General Fund . . . 84100

From the income of the Rumford Fund . . . 2350

From the income of the C. ^I. Warren Fund . 500

From the income of the Publication Fund . . 240-0

On the motion of the Treasurer, it was

Voted, That the annual assessment for the ensuing year be
ten dollars (810).

The annual election resulted in the choice of the following
officers and committees : —

William W. Goodwin, President.
John Trowbridge, Vice-President for Class I.
Henry P. Walcott, Vice-President for Class II.
John C. Gray, Vice-President for Class III.
Edwin H. Hall, Corresponding Secretary.
William Watson, Recording Secretary.
Charles P. Bowditch, Treasurer.
A. Lawrence Rotch, Librarian.

RECORDS OF MEETINGS. 757

Councillors for Three Years,

Henry P. Talbot, of Class I.
John E. Wolff, of Class II.
George L. Kittredge, of Class III.

Finance Committee.

William W. Goodwin,
Eliot C. Clarke,
Francis Bartlett.

Rumford Committee.
Charles R. Cross, Arthur G. Webster,

Edward C. Pickering, Elihu Thomson,
Theodore W. Richards, Erasmus D. Leavitt,

Louis Bell.

C. M. Warren Committee.
Leonard P. Kinnicutt, Charles R. Sanger,
Robert H. Richards, Arthur A. Noyes,
Theodore W. Richards, Henry P. Talbot,
George D. Moore,

The following standing committees were appointed by the
Chair : —

Piiblication Committee.

Wallace C. Sabine, of Class I, Edward L. Mark, of Class II,
Crawford H. Toy, of Class HI.

Library Committee.

Harry M. Goodwin, of Class I, Samuel Hensha w, of Class II,
Henry W. Haynes, of Class III.

Auditing Committee.
A. Lawrence Lowell, Frederick J. Stimson.

House Committee.

William R. Ware, A. Lawrence Rotch,

Morris H. Morgan.

758 PROCEEDINGS OF THE AMERICAN ACADEMY.

The following gentlemen were elected members of the
Academy : —

Charles Ladd Norton, of Boston, to be a Resident Fellow in
Class I, Section 2 (Physics).

George Washington Pierce, of Cambridge, to be a Resident
Fellow in Class I, Section 2 (Physics).

Gregory Paul Baxter, of Cambridge, to be a Resident Fellow
in Class I, Section 3 (Chemistry).

The following communications were given :

" Variable Stars in the Globular Clusters." By Professor S.
I. Bailey.

" The Eastern Escarpment of the Mexican Plateau." By
Professor W. M. Davis.

The following paper was presented by title :

Contribution from the Research Laboratory of Physical
Chemistry. — No. 15. "On the Density, Conductivity, and
Viscosity of Fused Electrolytes." By H. M. Goodwin and R.
D. Mailey.

AMERICAN ACADEMY OF ARTS AND SCIENCES,

Report of the Council. — Presented May 8, 1907.

BIOGRAPHICAL NOTICE.
Edward Atkinson Thomas Wentworth Higginson.

REPORT OF THE COUNCIL.

The Academy has lost nine members by death since the re-
port of the Council at the Annual 'meeting, May 9, 1906 : three
Resident Fellows, Edward J. Young, Bennett H. Nash, Samuel
Cabot ; six Foreign Honorary Members, J. W. A. Kirchhoff,
Lndwig Boltzmann, F. Bruuetiere, D. Mendeleeff, M. Berthelot,
Sir Michael Foster.

Six Resident Fellows have resigned ; one has abandoned
Fellowship.

New members have been elected as follows: Resident Fellows,
three ; Foreign Honorary Members, two.

The roll of the Academy now includes 189 Resident Fellows,
98 Associate Fellows, and 68 Foreign Honorary Members.

EDWARD ATKINSON

Edward Atkinson, a member of the American Academy of Arts and
Sciences since March 12, 1879, was born in Brookline, Mass., on February
10. 1827, and died in Boston on December 11, 1905. He was descended
on his father's side from the patriot minuteman. Lieutenant Amos At-
kinson, and on the maternal side from Stephen Greenleaf, a well known
fighter of Indians in the colonial period ; thus honestly inheriting on
both sides that combative spirit which marked his life in good causes.
Owing to the business reverses of his father he was prevented from
receiving, as his elder brother William Parsons Atkinson had received,
a Harvard College education, a training which was also extended to all
of Edward Atkinson's sons at a later day. At fifteen he entered the
employment of Read and Chadwick, Commission Merchants, Boston, in
the capacity of office boy ; but he rapidly rose to the position of book-
keeper, and subsequently became connected "«ath several cotton manu-
facturing companies in Lewiston, Maine, and elsewhere. He was for
many years the treasurer of a number of such corporations, and in 1878
became President of the Boston Manufacturers Mutual Insurance Com-
pany. This business was in a somewhat chaotic state when he took
hold of it, but he remained in this position until his death, having dur-

762 EDWARD ATKINSON.

ing this time organized, enlarged, and perfected the mutual insurance
of industrial concerns. In 1855 he married Miss Mary Caroline Heath
of Brookline, who survives him with seven children, — Mrs. Ernest
Winsor, E. W. Atkinson, Charles H. Atkinson, Wm. Atkinson, Robert
W. Atkinson, Miss C. P. Atkinson, and Mrs. R. G. Wadsworth.

This gives the mere outline of a life of extraordinary activity and
usefulness which well merits a further delineation in detail. Mr.
Atkinson's interest in public life began with a vote for Horace Mann in
1848. Twenty years after, speaking at Salem, he described himself as
never having been anything else than a Republican ; but he was one
of those who supported Cleveland for President in 1884 and whose
general affinities were with the Democratic party. He opposed with
especial vigor what is often called " the imperial policy," which followed
the Cuban war, and he conducted a periodical of his own from time to
time, making the most elaborate single battery which the war-party had
to encounter.

He was from an early period of life a profuse and vigorous pamphlet-
eer, his first pamphlet being published during the Civil War and
entitled " Cheap Cotton by Free Labor," this publication leading to his
acquaintance with David R. Wells and Charles Nordhoff, thenceforth
his life-long friends. His early pamphlets were on the cotton question
in different forms (1863-76) ; he wrote on blockade running (1865);
on the Pacific railway (1871); and on mutual fire insurance (1885),
this last being based on personal experience as the head of a mutual
company. He was also, during his whole life, in print and otherwise,
a strong and effective fighter for sound currency.

A large part of his attention from 1889 onward was occupied by
experiments in cooking and diet, culminating in an invention of his
own called " The Aladdin Oven. " This led him into investigations as
to the cost of nutrition in different countries, on which subject he also
wrote pamphlets. He soon was led on into experiments so daring
that he claimed to have proved it possible to cook personally, in open
air, a five-course dinner for ten persons, and gave illustrations of this
at outdoor entertainments. He claimed that good nutrition could be
had for $1 per week, and that a family of five, by moderate management,
could be comfortably supported for $180 per year ("Boston Herald,
Oct. 8, 1891). These surprising figures unfortunately created among
the laboring class a good deal of sharp criticism, culminating in the
mistaken inquiry, why he did not feed his own family at 8180 a year,
if it was so easy 1 I can only say for one, that if the meals at that price
were like a dinner of which I partook at his own house with an invited
party, and at which I went through the promised five courses after

EDWARD ATKINSON. 763

seeing them all prepared in the garden, I think that his standard of
poverty came very near to luxury.

Mingled with these things in later years was introduced another
valuable department of instruction. He was mors and more called upon
to give addresses, especially on manufactures, before Southern audiences,
and there was no disposition to criticize him for his anti-slavery record.
There could hardly be found another man whose knowledge of manu-
facturing and of insurance combined made him so fit a man to give
counsel in the new business impulse showing itself at the South. He
wrote much (1877) on cotton goods, called for an international cotton
expedition, giving an address at Atlanta, Ga., which was printed in
Boston in 1881.

Looking now at Atkinson's career with the eyes of a literary man, it
seems clear to me that no college training could possibly have added to
his power of accumulating knowledge or his wealth in the expression of
it. But the academic tradition might have added to these general state-
ments in each case some simple address or essay which would bring out
clearly to the minds of an untrained audience the essential points of each
single theme. Almost everything he left is the talk of a specially trained
man to a limited audience, also well trained, — at least in the particular
department to which he addresses himself. The men to whom he talks
may not know how to read or write, but they are all practically versed in
the subjects of which he treats. He talks as a miner to miners, a farmer
to farmers, a cook to cooks ; but among all of his papers which I have
examined that in which he appears to the greatest advantage to the
general reader is his " Address before the Alumni of Andover Theo-
logical Seminary " on June 9, 1886. Here he speaks as one represent-
ing a wholly different pursuit from that of his auditors ; a layman to
clergymen, or those aiming to become so. He says to them frankly at
the outset, " I have often thought [at church] that if a member of the
congregation could sometimes occupy the pulpit while the minister
took his place in the pew, it might be a benefit to both. The duty has
been assigned to me to-day to trace out the connection between morality
and a true system of political or industrial economy."

He goes on to remind them that the book which is said to rank next to
the Bible toward the benefit of the human race is Adam Smith's
" Wealth of Nations," and that the same Adam Smith vsrote a book on
moral philosophy which is now but little read. He therefore takes the
former of Smith's books, not the latter, as his theme, and thus proceeds:

" I wonder how many among your number ever recall the fact that it
has been the richest manufacturers who have clothed the naked at the
least cost to them ; that it is the great bonanza farmer who now feeds the

764 EDWARD ATKINSON.

hungry at the lowest price ; that Vanderbilt achieved his great fortune
by reducing the cost of moving a barrel of flour a thousand miles, — from
three dollars and fifty cents to less than seventy cents. This was the
great work assigned to him, whether he knew it or not. His fortune
was but an incident, — the main object, doubtless, to himself, but a
trifling incident compared to what he saved others." ^

He then goes on to show that whatever may be the tricks or wrongs
of commerce, they he on the surface, and that every great success is
based upon very simple facts. "The great manufacturer," he says,
" who guides the operations of a factory of a hundred thousand spindles,
in which fifteen hundred men, women, and children earn their daily
bread, himself works on a narrow margin of one fourth of a cent on
each yard of cloth. If he shall not have applied truth to every branch
of construction and of the operation of that factory, it will fail and
become worthless ; and then with toilsome labor a hundred and fifty
thousand women might try to clothe themselves and you, who are now
clothed by the service of fifteen hundred only.

" Such is the disparity in the use of time, brought into beneficent
action by modern manufacturing processes.

"The banker who deals in credit by millions upon millions must
possess truth of insight, truth of judgment, truth of character. Pro-
bity and integrity constitute his capital, for the very reason that the
little margin which he seeks to gain for his own service is but the
smallest fraction of a per cent upon each transaction. I supervise
directly or indirectly the insurance upon four hundred million dollars'
worth of factory property. The products of these factories, machine-
shops, and other works must be worth six hundred million dollars a
year. It is n't worth fifty cents on each hundred dollars to guarantee
their notes or obligations, while ninety-nine and one half per cent of
all the sales they make will be promptly paid when due." ^

He elsewhere turns from viewing the factory system with business
eyes alone to the consideration of it from the point of view of the
laborer. There is no want of sympathy, we soon find, in this man of
inventions and statistics. He thus goes on :

" The very manner in which this great seething, toiling, crowded
mass of laboring men and women bear the hardships of life leads one
to faith in humanity and itself gives confidence in the future. If it
were not that there is a Divine order even in the hardships which seem
so severe, and that even the least religious, in the technical sense,

*• Address to Alumni of Andover, p. 1.
a Ibid., p. 10.

EDWARD ATKINSON, 765

have faith in each other, the anarchist and nihilist might be a cause
of dread.

"As I walk through the great factories which are insured in the
company of which I am president, trying to find out what more can
be done to save them from destruction by fire, I wonder if I myself
should not strike, just for the sake of variety, if I were a mule-spinner,
obliged to bend over the machine, mending the ends of the thread,
while I walked ten or fifteen miles a day without raising my eyes to
the great light above. I wonder how men and women bear the mo-
notony of the workshop and of the factory, in which the division of
labor is carried to its utmost, and in which they must work year in
and year out, only on some small part of a fabric or an implement,
never becoming capable of making the whole fabric or of constructing
the whole machine.""*

We thus find him quite ready to turn his varied knowledge and his
executive power towards schemes for the relief of the operative, schemes
of which he left many.

Mr. Atkinson, a year or two later (1890), wrote a similarly popular-
ized statement of social science for an address on " Religion and Life "
before the American Unitarian Association, In his usual matter-of-
fact way he had prepared himself by inquiring at the headquarters of
different religious denominations for a printed creed of each. He first
bought an Episcopal creed at the Old Corner Bookstore for two cents,
an Orthodox creed at the Congregational Building for the same amount,
then a Methodist two-cent creed also, a Baptist creed for five cents,
and a Presbyterian one for ten, Unitarian and Universalist creeds
being furnished him for nothing ; and then he proceeds to give some
extracts whose bigotry makes one shudder, and not wonder much that
he expressed sympathy mainly with the Catholics and the Jews, rather
than with the severer schools among Protestants. And it is already
to be noticed how much the tendency of liberal thought, during the
last twenty years, has been in the direction, whither his sympathies
went.

As time went on he underwent the test which awaits all Northern
public men visiting the Southern States, but not met by all in so simple
and straightforward a way as he. Those who doubt the capacity of
the mass of men in our former slave States to listen to plainness of
speech should turn with interest to Atkinson's plain talk to the lead-
ing men of Atlanta, Ga., in October, 1880. He says, almost at the
beginning: " Now, gentlemen of the South, I am going to use free

^ Address to Workingmen in Providence, April 11, 1886, p. 19.

766 EDWARD ATKINSON.

speech for a purpose and to speak some plain words of truth and sober-
ness to you. ... I speak then to you here and now as a Repubhcan
of Repubhcans, as an Abolitionist of early time, a Free Soiler of later
date, and a Republican of to-day." And the record is that he was
received with applause. He goes on to say as frankly: " When slavery
ended, not only were blacks made free from the bondage imposed by
others, but whites as well were redeemed by the bondage they had
imposed upon themselves. . . . When you study the past system of
slave labor with the present system of free labor, irrespective of all
personal considerations, you will be mad down to the soles of your
boots to think that you ever tolerated it ; and when you have come to
this wholesome condition of mind you will wonder how the devil you
could have been so slow in seeing it." [Laughter.]

Then he suddenly drops down to the solid fact and says : "Are you
not asking Northern men to come here, and do you not seek Northern
capital ? If you suppose either will come here unless every man can
say what he pleases, as I do now, you are mistaken." Then he goes on
with his speech, rather long as he was apt to make them, but addressing
a community much more leisurely than that which he had left at home ;
filling their minds with statistics, directions, and methods, till at last
recurring to the question of caste and color he closes fearlessly : "As
you convert the darkness and oppression and slavery to liberty and
justice, so shall you be judged by men, and by Him who created all
the nations of the South."

After tracing the course and training of an eminent American at
home, it is often interesting to follow him into the new experiences of
the foreign traveller. In that very amusing book, " Notes from a
Diary," by Grant Duff (now Sir Mountstuart Elphinstone Grant Duff),
the author writes that he came unexpectedly upon a breakfast (June,
1887), the guests being "Atkinson, the New England Free Trader,
Colonel Hay, and Frederic Harrison, all of whom were well brought
out by our host and talked admirably." I quote some extracts from
the talk:

" Mr. Atkinson said that quite the best after-dinner speech he had
ever heard was from Mr. Samuel Longfellow, brother of the poet.
An excellent speech had been made by Mr. Longworth, and the pro-
ceedings should have closed, when Mr. Longfellow was very tactlessly
asked to address the meeting, which he did in the words: 'It is, I
think, well known that worth makes the man, but want of it the fel-
low,' and sat down." After this mild beginning we have records of
good talk.

"Other subjects," Grant Duff says, "were the hostility of the So-

EDWARD ATKINSON. 767

cialists in London to the Positivists and to the Trades' Unions ; the
great American fortunes and their causes, the rapid melting away of
some of them, the hindrance which they are to poHtical success ; and
servants in the United States, of whom Atkinson spoke relatively,
Colonel Hay absolutely, well, saying that he usually kept his from
six to eight years. ...

" Atkinson said that all the young thought and ability in America
is in favor of free trade, but that free trade has not begun to make
any way politically. Harrison remarked that he was unwillingly, but
ever more and more, being driven to believe that the residuum was
almost entirely composed of people who would not work. Atkinson
took the same view, observing that during the war much was said
about the misery, of the working women of Boston. He offered ad-
mirable terms if they would only go a little way into the country to
work in his factory. Forty were at last got together to have the con-
ditions explained — ten agreed to go next morning, of whom one
arrived at the station, and she would not go alone ! "

On another occasion we read in the "Diary ": —

" We talked of Father Taylor, and he [Atkinson] told us that the
great orator once began a sermon by leaning over the pulpit, with his
arms folded, and saying, ' You people ought to be very good, if you 're
not, for you live in Paradise already.'

" The conversation, in which Sir Louis ]Mallet took part, turned to
Mill's economical heresies, especially that which relates to the fostering
of infant industries. Atkinson drew a striking picture of the highly
primitive economic condition of the South before the war, and said
that now factories of all kinds are springing up throughout the coun-
try in spite of the keen competition of the North. He cited a piece
of advice given to his brother by Theodore Parker, ' Never try to lec-
ture down to your audience.' This maxim is in strict accordance with
an opinion expressed by Hugh Miller, whom, having to address 'on the
other side of the Firth just the same sort of people as those amongst
whom he lived at Cromarty, I took as my guide in this matter during
the long period in which I was connected with the Elgin Burghs."

" Atkinson went on to i-elate that at the time of Mr. Hayes's elec-
tion to the presidency there was great danger of an outbreak, and he
sat in council with General Taylor and Abraham Hewitt, doing his
best to prevent it. At length he exclaimed: ' Now I think we may
fairly say that the war is over. Here are we three acting together for
a common object, and who are we ? You, Mr. Hewitt, are the leader
of the Democratic party in New York ; I am an old Abolitionist who
subscribed to furnish John Brown and his companions with rifles ; you.

768 EDWARD ATKINSON.

General Taylor, are the last Confederate officer who surrendered an
army, and you surrendered it not because you were willing to do so,
but, as you yourself admit, because you couldn't help it.' "

The publication which will perhaps be much consulted in coming
years as the best periodical organ of that party in the nation which
was most opposed to* the Philippine war will doubtless be the work issued
by Mr. Atkinson on his own responsibility and by his own editing,
from June 3, 1899, to September, 1900, under the name of " The Anti-
Imperialist." It makes a solid volume of about 400 octavo pages, and
was conducted wholly on Atkinson's own responsibility, financially and
otherwise, though a large part of the expense was paid him by volun-
teers to the extent of $5,657.87 or more, covering an outlay of
$5,870.62, this amount being largely received in sums of one dollar,
obtained under what is known as the chain method. For this amount
were printed more than 100,000 copies of a series of pamphlets, of
which the first two were withdrawn from the mail as seditious under
President McKinley's administration. A more complete triumph of
personal independence was perhaps never seen in our literature, and it
is easy to recognize the triumph it achieved for a high-minded and
courageous as well as constitutionally self-willed man. The periodical
exerted an influence which lasts to this day, although the rapidity of
political change has now thrown it into the background for all except
the systematic student of history. It seemed to Mr. Atkinson, at any
rate, his crowning work.

The books published by Edward Atkinson were the following: " The
Distribution of Profits," 1885; "The Industrial Progress of the Na-
tion," 1889; "The Margin of Profit," 1890; "Taxation and Work,"
1892; "Facts and Figures the Basis of Economic Science," 1894.
This last was printed at the Riverside Press, the others being issued
by Putnam & Co., New York. He wrote also the following papers in
leading periodicals: "Is Cotton our King?" (Continental Monthly,
March, 1862); "Revenue Reform" (Atlantic, October, 1S71) ; "An
American View of American Competition " (Fortnightly, London,
March, 1879); "The Unlearned Professions " (Atlantic, June, 1880);
" What makes the Rate of Interest " (Forum, 1880) ; " Elementary In-
struction in the Mechanics Arts " (Century, May, 1881) ; "Leguminous
Plants suggested for Ensilage" (Agricultural, 1882); "Economy in
Domestic Cookery" (American Architect, May, 1887); "Must Hu-
manity Starve at Last?" "How can Wages be Increased?" "The
Struggle for Subsistence," "The Price of Life "(all in Forum for 1888);
" How Society Reforms Itself," and " The Problem of Poverty " (both in

EDWARD ATKINSON. 769

Forum for 1889) ; " A Single Tax on Land " (Century, 1890) ; and
many others. When the amount of useful labor performed by the
men of this generation comes to be reviewed a century hence, it is
doubtful whether a more substantial and varied list will be found
credited to the memory of any one in America than that which
attaches to the memory of Edward Atkinson.

Thomas Wentworth Higginson.

VOL. XLII. 19

American Academy of Arts and Sciences

OFFICERS AND COMMITTEES FOR 1907-08.

president.
William W. Goodwin.

Class I.
John Trowbridge,

Class I.

Wallace C. Sabine,
Ira N. Hollis,
Henry P. Talbot,

vice-president.

Class II.

Henry P. Walcott,

CORRESPONDING SECRETARY.

Edwin II. Hall.

RECORDING SECRETARY.

William Watson.

treasurer.

Charles P. liowDixcH.

librarian.
A. Lawrence Rotch.

COUNCILLORS.

Class II.

William G. Farlow,

Terms expire 1908.

James C. White,

Terms expire 1909.

John E. Wolff,

Terms expire 19 10.

Class III.
John C. Gray.

William W. Goodwin,

committee of finance.
Eliot C. Clarke,

Class III.
Edward Robinson.

William R. Ware.

George L. Kittredge.

Francis Bartlett.

RUMFORD COMMITTEE.
Ch.\rles R. Cross, Chairman,
Erasmus D. Leavitt, Edward C. Pickering,

Arthur G. Webster, Theodore W. Richards,

C. M. WARREN COMMITTEE.

Leonard P. Kinnicutt, Ckairman,
Robert H. Richards, Charles R. Sanger,

Elihu Thomson.
Louis Bell.

Arthur A. Noyes.

Henry P. Talbot,

Theodore W. Richards, George D. Moore.

COMMITTEE OF PUBLICATION.

Edward L. Mark, of Class II, Chairman,

Wallace C. Sabine, of Class I, Crawford H. Toy, of Class III.

COMMITTEE ON THE LIBRARY.

A. Lawrence Rotch, Chairman,

Harry M. Goodwin, of Class I, Samuel Henshaw, of Class II,

Henry W. Haynes, of Class III.

AUDITING COMMITTEE.

A. Lawrence Lowell,

Frederick J. Stimson.

HOUSE COMMITTEE.
WiLLiA.M R. Wake, Chairman.

A. Lawrence Rotch,

Morris H. Morgan.

LIST

OF THE

FELLOWS AXD FOREIGN HONORARY MEMBERS.

(Corrected to June 1, 1907.)

RESIDENT FELLOWS. — 192.

(Number limited to two Lundred.)

Class I. — Mathematical and Physical Sciences. — 78
Section I. — 15.

Mathematics and A

Solon I. Bailey,
Maxime Bocher,
AVilliam E. Byerly,
Seth C. Chandler, V\
Gustavus Hay,
Percival Lowell,
Edward C. Pickering,
William H. Pickering,
John Ritchie, Jr.,
Arthur Searle,
William E. Story,
Ilenry Taber,
Harry A\'. Tyler,
O. C. Wendell,
P. S. Yendell.

stronomy.

Cambridge.
Cambridge.
Cambridge,
ellesley Hills.
Boston.
Boston.
Cambridge.
Cambridge.
Roxbury.
Cambridge.
Worcester.
Worcester.
Boston.
Cambridge.
Dorchester.

Section H. — 26.

Physios.
A. Graham Bell, Washington, D.C.

Louis Bell,
Clarence J. Blake,
Francis Blake,
George A. Campbell,
Harry E. Clifford,
Charles R. Cross,

Boston.

Boston.

Weston.

Boston.

Newton.

Brookline.

A. W. Duff,
H. M. Goodwin,
Edwin II. Hall,
Hammond V. Hayes,
William L. Hooper,
William W. Jacques,
Frank A. Laws,
Heniy Lefavour,
Theodore Lyman,
Charles L. Norton,
Benjamin O. Peirce,
George W. Pierce,
A. Lawrence Rotch,
Wallace C. Sabine,
John S. Stone,
Elihu Thomson,
John Trowbridge,
A. G. Webster,
Robert W. Willson,

Worcester.

Roxbury.

Cambridge.

Cambridge.

Somerville.

Newton.

Boston.

Boston.

Brookline.

Boston.

Cambridge.

Cambridge.

Boston.

Boston.

Boston.

Swampscott.

Cambridge.

Worcester.

Cambridge.

Section IU. — 19.
Chemistry.

Gregory Paul Baxter, Cambridge.

Arthur M. Comey, Cambridge.

James M. Crafts, Boston.

Charles W. Eliot, Cambridge.

Charles L. Jackson, Cambridge.

Walter L. Jennings, Worcester.

KESIDENT FELLOWS.

Worcester.
Cleveland, O.
Boston.
Worcester.
Chicago, 111.
Boston.
Jamaica Plain.

Leonard P. Kinnicutt

Charles F. Mabery,

Arthur Michael,

George D. Moore,

John U. Nef,

Arthur A. Noyes,

Robert H. Richards,

Theodore W. Richards, Cambridge.

Charles R. Sanger, Cambridge.

Stephen P. Sharpies, -Cambridge.

Francis H. Storer, Boston.

Henry P. Talbot, Newton.

Charles H. Wjng, Ledger, N. C

Section IV. — 18.
Technology and Engineering.
Cambridge.

Comfort A. Adams,

Alfred E. Burton,
EUot C. Clarke,
Heinrich O. Ilofman,
Ira N. Hollis,
L. J. Johnson,
Arthur E. Kennelly,
Gaetano Lanza,
E. D. Leavitt,
William R. Livermore,
Hiram F. IMills,
Cecil H. Peabody,
Andrew H. Russell,
Albert Sauveur,
Peter Schwamb,
H. L. Smyth,
George F. Swain,
WilUam Watson,

Boston.

Boston.

Jamaica Plain.

Cambridge.

Cambridge.

Cambridge.

Boston.

Cambridge.

New York.

Lowell.

Brookline.

Manila.

Cambridge.

Arlington.

Cambridge.

Boston.

Boston.

Class IL — Natural and Physiological Sciences. — 62.

Section I. — 14.

Geology, Mineralogy , and Physics of
the Globe.

H. H. Clayton,
Algernon Coolidge,
William O. Crosby,
William M. Davis,
Benj. K. Emerson,
O. W. Huntington,
Robert T. Jackson,
T. A. Jaggar, Jr.,
William II. Nilcs,
Charles Palache,
John E. Pillsbury,
Rol)ert DeC. Ward,
John E. Wolff,
J. B. Wood worth,

Milton.

Boston.

Jamaica Plain.

Cambridge.

Amherst.

Newport, R. I.

Cambridge.

Cambridge.

Cambridge.

Cambridge.

Boston.

Cambridge.

Cambridge.

Cambridge.

Section II. — 12.

Botany.

F. S. Collins,
Geo. E. Davenport,
William G. Far low,
Charles E. Faxon,
Merritt L. Fernald,
George L. Goodale,
John G. Jack,
Edward C. Jeffrey,
B. L. Robinson,
Charles S. Sargent,
Arthur B. Seymour,
Roland Thaxter,

Maiden.

Medford.

Cambridge.

Jamaica Plain.

Cambridge.

Cambridge.

Jamaica Plain.

Cambridge.

Cambridge.

Brookline.

Cambridge.

Cambridge.

Section IIL — 23.

Zoology and Physiology.

Alexander Agassiz, Cambridge.
Robert Araory, Boston.

RESIDENT FELLOWS.

775

Henry P. Bowditch,
William Brewster,
Louis Cabot,
Walter B. Cannon,
William E. Castle,
Sanmel F. Clarke,
VV. T. Councilman,
Harold C. Ernst,
Edward G. Gardiner,
Samuel Henshaw,
Theodore Hough,
Edward L. ]\Iark,
Charles S. Miuot,
Edwai'd S. Morse,
George H. Parker,
William T. Porter,
James J. Putnam,
Samuel H. Scudder,
William T. Sedgwick,

Jamaica Plain.

Cambridge.

Brookline.

Cambridge.

Cambridge.

Williamstown.

Boston.

Jamaica Plain.

Boston.

Cambridge.

Boston.

Cambridge.

Milton.

Salem.

Cambridge.

Boston.

Boston.

Cambridge.

Boston.

James C. White, Boston.

William M. Woodworth, Cambridge.

Section IV. — 13.

J\Tedtcine and

Edward H. Bradford,
Arthur T. Cabot,
Thomas Dwight,
Reginald H. Fitz,
Charles F. Folsom,
Frederick I. Knight,
Samuel J. INIixter,
W. L. Richardson,
Theobald Smith,
O. F. Wads worth,
Henry P. Walcott,
John C. Warren,
Francis H. Williams,

Surgery.

Boston.

Boston.

Xahant.

Boston.

Boston.

Boston.

Boston.

Boston.

Jamaica Plain.

Boston.

Cambridge.

Boston.

Boston.

Class III, — Moral and Political Sciences. — 52.

Section I. — 9.

Philosophy and Jur

James B. Ames,
Joseph H. Beal, Jr.,
John C. Gray,
Francis C. Lowell,
Hugo Miinsterberg,
Josiah Royce,
Frederic J. Stimson,
Edward H. Strobel,
Samuel Williston,

Hsprudence.

Cambridge.

Cambridge.

Boston..

Boston.

Cambridge.

Cambridge.

Dedham.

Cambridge.

Belmont.

Section IT. — 19.

Philology and Archceology.

Charles P. Bowditch, Jamaica Plain.
Lucien Carr, Cambridge.

Franklin Carter,
J. W. Fewkes,
William W. Goodwin,
Henry W. Haynes,
Albert A. Howard,
Charles R. Lanman,
David G. Lyon,
George F. jNIoore,
Morris II. I\I organ,
Frederick W. Putnam,
Edward Robinson,
Edward S. Sheldon,
Herbert Weir Smyth,
F. B. Stephenson,
Crawford H. Toy,
John W. White,
John H. Wright,

Williamstown.

Washington.

Cambridge.

Boston.

Cambridge.

Cambridge.

Cambridge.

Cambridge.

Cambridge.

Cambridge.

New York.

Cambridge.

Cambridge.

Boston.

Cambridge.

Cambridge.

Cambridge.

776

RESIDENT FELLOWS.

Section III. — 12.

Political Economy

Charles F. Adams,
Thomas N. Carver,
Andrew McF. Davis,
Ephraim Emerton,
A. C. Goodell,
Charles Gross,
Hem-y C. Lodge,
A. Lawrence Lowell,
James F. Rhodes,
William Z. Ripley,
Charles C. Smith,
F. W. Taussig,

and History.

Lincoln.

Cambridge.

Cambridge.

Cambridge.

Salem.

Cambridge.

Nahant.

Boston.

Boston.

Newton.

Boston.

Cambridge.

Section IV. — 12.

Literature and the Fine Arts.

Francis Bai'tlett,
Arlo Bates,
Kuno Francke,
Edward IL Hall,
T. W. Higginson,
George L. Kittredge,
William C. Lane,
Charles Eliot Norton,
Deuman W. Ross,
William R. Ware,
Herbert L. AVarren,
Barrett Wendell,

Boston.

Boston.

Cambridge.

Cambridge.

Cambridge.

Cambridge.

Cambridge,

Cambridge.

Cambridge.

Milton.

Cambridge.

Boston.

ASSOCIATE FELLOWS.

777

ASSOCIATE FELLOWS. — 97.

(Number limited to one hundred. Elected as vacancies occur.)
Class I. — 3Iathematical and Physical Sciences. — 37.

Section I. — 14.

Mathematics and Astronomy.

Edward E. Barnard, AVilliaras Bay,

Wis.
S. W. Burnliani, Williams Bay, Wis.
George Davidson, San Francisco.

Fabian Franklin,
Asaph Hall,
George \Y. Hill,
E. S. Holdeii,
Emory McClintock,
E. H. Moore,
Simon Newcomb,
Charles L. Poor,
George M. Searle,
J. N. Stock well,
Chas. A. Young,

Baltimore.
S. Norfolk, Conn.
W. Nyack, N.Y.
New York.
Morristown,N.J.
Cliicago.
Washington.
New York.
Washington.
Cleveland, O.
Hanover, N. H.

G.

Section H.

Physics.

Carl Barus, Providence, R.I.

G. E. Hale, Williams Bay, Wis.

T. C. Mendenhall, Worcester.
A. A. Michelson, Chicago.

E. L. Nichols,
M. I. Pupin,

Ithaca, N. Y.
New York.

Section IH. — 9.
Chemistry.

Wolcott Gibbs, Newport, R.I.
Frank A. Gooch, New Haven.
Eugene W. Hilgard, Berkeley, Cal.
S. W. Johnson, New Haven.
J. W. Mallet, Charlottesville, Ya.

E. W. ]\Iorley, Cleveland, O.

Charles E. Munroe, Washington.
J. M. Ordway, New Orleans.
Ira Remsen, Baltimore.

Section IV. — 8.

Technology and Engineering.

Henry L. Abbot, Cambridge.
Cyrus B. Comstock, New York. [Ya.
W. P. Craighill, Charlestown, W.

John Fritz,
James D. Hague,
F. R. Hutton,
William Sellers,

Bethlehem, Pa.
New York.
New York.
Edge Moor, Del.

Robt. S. Woodward, Washington.

Class II. — Natural and Physiological Sciences. — 32.
Section I. — 10.

Geology, Mineralogy , and Physics of
the Globe.

Cleveland Abbe,
George J. Brush,
T. C. Chamberlin,

Washington.
New Haven.
Chicago.

Edward S. Dana, New Haven.

Walter G. Davis, Cordova, Arg.

Samuel F. Emmons, AVashington.

G. K. Gilbert, Washington.

R. Pumpelly, Newport, R.I.

Israel C. Russell, Ann Arbor.

Charles D. Walcott. Washington.

778

ASSOCIATE FELLOWS,

Section II. — 6.
Botany.

L. H. Bailey,
D. II. Campbell,
J. M. Coulter,
C. G. Pringle,
John D. Smith,
AV. Trelease,

Ithaca, N. Y.
Palo Alto, Cal.
Chicago.
Charlotte, Vt.
Baltimore.
St. Louis.

Section III. — 9.

Zoology and Physiology.

Joel A. Allen, Xew York.

W. K. Brooks, Lake Roland, Md,

C. B. Davenport,

Cold Spring Harbor, N. Y.

F. P. Mall,

Baltimore.

S. Weir Mitchell, Philadelphia.

H. F. Osborn, Xew York.

A. E. Verrill, New Haven.

C. O. Whitman, Chicago.

E. B. Wilson, New York.

Section IV. — 8.

Medicine and Surgery.

John S. Billings, New York.

W. S. Ilalsted, Baltimore.

Abraham Jacobi, New York.

W. V( . Keen, Philadelphia.

William Osier, Baltimore.
T. ]\litchell Prudden, New York.

Wm. H. Welch, Baltimore.

H. C. Wood, Philadelphia.

Class III. — 3Ioral and Political Sciences. — 27.

Section I. — 6.

Philosophy and

Joseph H. Choate,
Melville W. Fuller,
William W. Howe,
Charles S. Peirce,
G. W. Pepper,
T. R. Pynchon,

Jurisprudence.

New York.
Washington.
New Orleans.
Milford, Pa.
Philadelphia.
Hartford, Conn.

Section II. — 7.

Philology and Archceology.

Timothy Dwight, New Haven.
B. L. Gildcrsleeve, Baltimore.
D. C. Gilman, Baltimore.

T. R. Lounsbury, New Haven.
Rufiis B. Richardson, New York.
Thomas D. Seymoui', New Haven.
A. D. White, Ithaca, N.Y.

Section HI. — 7.

Political Economy and History.

Henry Adams, Washington.

G. P. Fisher, New Haven.

Arthur T. Hadley, New Haven.

Henry C. Lea, Philadelphia.

Alfred T. Mahan, New York.

H. Morse Stephens, Ithaca.

W. G. Sumner, New Haven.

Section IV. — 7.

Literature and the Fine Ai'ts.

James B. Angell, Ann Arbor. ^lich.

H. H. Furness, Wallingford, Pa.

R. S. Greenough, Florence.

Herbert Putnam, Washington.
Augustus St. Gaudens, Windsor, Vt.

John S. Sargent, London.

E. C. Stedman, Bronxville, N. Y.

FOREIGN HONORARY MEMBERS.

779

FOREIGN HONORARY MEMB E RS. — 68.

(Number limited to seventy-five. Elected as vacancies occur.)

Class I. — Mathematical and Physical Sciences. — 22.

Skction I. — 7.

Mathematics and Astronomy.

Arthur Auwers, Berlin.

George II. Darwin, Cambridge.
Sir William Huggins, London.

Felix Klein, Giittingen.

Emile Picard, Paris.

H. Poincare, Paris.

H. C. Vogel, Potsdam.

Section U. — 5.
Physics.

Oliver Heaviside,
F. Kohlrauscli,
Joseph Larraor,
Lord Kayleigh,
Joseph J. Tliomson,

Newton Abbot.

Marburg.

Cambridge.

Witham.

Cambridge.

Sectiox hi. — 5.

Chemistry.
Adolf Ritter von Baeyer, INIunich.

J. H. van't Iloff,
Wilhelm Ostwald,
Sir H. E. Roscoe,
Julius Thomseu,

Berlin,
Leipsic.
London.
Copenhagen.

Section IV. — 5.
Technology and Engineering.

Sir Benjamin Baker,
Lord Kelvin,
jNIaurice Levy,
H. Miiller-Breslau,

London.
Largs.
Paris.
Berlin.

"W. Cawthorne Unwin, London.

Class IL — Natural and Physiological Sciences. — 23.

Section I. — 5.

Geology, Mineralogy, and Physics of
the Globe.

Sir Archibald Geikie, London.
Julius Ilanu,
Albert Heim,
Sir John Murray,
Henry C. Sorby,

Vienna.
Zurich.
Edinburgh.
Sheffield.

Section II. — 6.
Botany.
E. Bornet, Paris.

A. Engler,

Berlin.

Sir Joseph D. Hooker, Sunningdale.
W. Pfeffer, Leipsic.

II. Graf zu Solms-

Laubach, Strassburg.

Eduard Strasburger, Bonn.

780

FOREIGN HONORARY MEMBERS.

Section III. — 5.

Zoology and Physiology.

Ludimar Hermann,
H. Kronecker,
E. Ray Lankester,
Elias Metschnikoff,
M. Gustav Retzius,

Konigsberg.

Bern.

London.

Paris.

Stockholm.

Section IV. — 7.

Medicine and Surgery,

Emil von Beliring, Marburg.

Sir T. L. Brunton, London.

A. Celli, Rome.

Sir V. A. H. Horsley, London.

R. Koch, Berlin.

Lord Lister, London.
F. V. Recklinghausen, Strassburg.

Class III. — Moral and Political Sciences. — 23.

Section I. — 5.

Section IH

. — 5.

Philosophy and Jurisprudence.

Political Economy <

%nd History,

A. J. Balfour, Prestonkirk.

James Bryce,

London.

Heinrich Brunner, Berlin.

Adolf Harnack,

Berlin.

A. V. Dicey, Oxford.

Sir G. 0. Trevelyan,

F. W. Maitland, Cambridge.

Bart.,

London.

Sir Frederick Pollock,

John Morley,

London.

Bart. , London.

Pasquale Villari,

Florence.

Section II. — 7.

Section IV

. — 6.

Philology and Archceology.
Ingram Bywater, Oxford.

Literature and the Fine Arts.

F. Delitzsch, Berlin.

E. de Amicis,

Florence.

Hermann Diels, Berlin.

Gaston Boissier,

Paris.

W. Dorpfeld, Athens.

Georg Brandes,

Copenhagen

Sir John Evans, Berkhampsted.

S. H. Butcher,

London.

H. Jackson, Cambridge.

Jean Leon Gerome,

Paris.

G. C. C. Maspero, Paris.

Rudyard Kipling,

Bur wash.

STATUTES AXD STANDING VOTES.

STATUTES.

Adopted May 30, 1854 : amended September 8, 1857, November 12, 1862,
May 24, 1864, November 9, 1870, 31ay 27, 1873, January 26, 1876,
June 16, 1886, October 8, 1890, January 11, one? J% 10, 1893, May
9, a??rf Octo(5>er 10, 1894, March 13, JpriV 10, ayid May 8, 1895, May
8, 190], January 8, 1902, J% 10, 1905, February 14 a?j(/ J/arcA 14,
1906.

CHAPTER I.
Of Fellows and Foreign Honorary Members.

1. The Academy consists of Resident Fellows, Associate Fellows, and
Foreign Honorary Members. They are arranged in three Classes, ac-
cording to the Arts and Sciences in which they are severally proficient,
viz.: Class I. The Mathematical and Physical Sciences; — Class II.
The Natural and Physiological Sciences; — Class III. The Moral and
Political Sciences. Each Class is divided into four Sections, viz. :
Class I., Section 1. Mathematics and Astronomy; — Section 2. Physics;
— Section 3. Chemistry ; — Section 4. Technology and Engineering.
Class II., Section 1. Geology, Mineralogy, and Physios of the Globe; —
Section 2. Botany ; Section 3. Zoology and Physiology ; — Section 4.
Medicine and Surgery. Class III., Section 1. Theology, Philosophy,
and Jurisprudence; — Section 2. Philology and Archaeology; — Sec-
tion 3. Political Economy and History ; — Section 4. Literature and
the Fine Arts.

2. The number of Resident Fellows residing in the Commonwealth
of Massachusetts shall not exceed two hundred, of whom there shall not
be more than eighty in any one of the three classes. Only residents in
the Commonwealth of Massachusetts shall be eligible to election as Resi-
dent Fellows, but resident fellowship may be retained after removal from

782 STATUTES OP THE AMERICAN ACADEMY

the Commonwealth. Each Resident Fellow shall pay an admission fee
of ten dollars and such annual assessment, not exceeding ten dollars,
as shall be voted by the Academy at each annual meeting. Resident
Fellows only may vote at the meetings of the Academy.

3. The number of Associate Fellows shall not exceed one hundred,
of whom there shall not be more than forty in either of the three classes
of the Academy. Associate Fellows shall be chosen from persons resid-
ing outside of the Commonwealth of Massachusetts. They shall not be
liable to the payment of any fees or annual dues, but on removing within
the Commonwealth they may be transferred by the Council to resident
fellowship as vacancies there occur.

4. The number of Foreign Honorary Members shall not exceed
seventy-five; and they shall be chosen from among persons most eminent
in foreign countries for their discoveries and attainments in either of the
three departments of knowledge above enumerated. There shall not be
more than thirty Foreign Members in either of these departments.

CHAPTER 11.
Op Officers.

1. There shall be a President, three Vice-Presidents, one for each
Class, a Corresponding Secretary, a Recording Secretary, a Treasurer,
and a Librarian, which officers shall be annually elected, by ballot, at
the annual meeting, on the second Wednesday in May.

2. There shall be nine Councillors, chosen from the Resident Fellows.
At each annual meeting, three Councillors shall be chosen, by ballot,
one from each Class, to serve for three years ; but the same Fellow shall
not be eligible for two successive terms. The nine Councillors, with the
President, the three Vice-Presidents, the two Secretaries, the Treasurer,
and the Librarian, shall constitute the Council. Five members shall
constitute a quorum. It shall be the duty of this Council to exercise a
discreet supervision over all nominations and elections. With the con-
sent of the Fellow interested, they shall have power to make transfers
between the several sections of the same Class, reporting their action to
the Academy.

3. The Council shall at its March Meeting receive reports from the
Rumford Committee, the C. M. Warren Committee, the Committee on
Publication, the Committee on the Library, the President and Record-

OF ARTS AND SCIENCES. 783

ing Secretary, and the Treasurer, proposing the appropriations for their
work during the year beginning the following May. The Treasurer at
the same meeting shall report un the income which will probably be
received on account of the various Funds during the same year.

At the Annual Meeting, the Council shall submit to the Academy,
for its action, a report recommending the appropriations which in the
opinion of the Council should be made for the various purposes of the
Academy.

4. If any office shall become vacant during the year, the vacancy shall
be filled by a new election, at the next stated meeting, or at a meeting
called for this purpose:

CHAPTER III.
Of Nominations of Officers..

1. At the stated meeting in March, the President shall appoint a
Nominating Committee of three Resident Fellows, one for each Class.

2. It shall be the duty of this Nominating Committee to prepare a list
of candidates for the offices of President, Vice-Presidents, Corresponding
Secretary, Recording Secretary, Treasurer, Librarian, Councillors, and
the Standing Committees which are chosen by ballot; and to cause this
list to be sent by mail to all the Resident Fellows of the Academy not
later than four weeks before the Annual Meeting.

3. Independent nominations for any office, signed by at least five
Resident Fellows, and received by the Recording Secretary not le^<s than
ten days before the Annual Meeting, shall be inserted in the call for the
Annual Meeting, which shall then be issued not later than one week
before that meeting.

4. The Recording Secretary shall prepare for use, in voting at the
Annual Meeting, a ballot containing the names of all persons nominated
for office under the conditions given above.

5. When an office is to be filled at any other time than at the Annual
IMeeting, the President shall appoint a Nominating Committee in accord-
ance with the provisions of Section 1, which shall announce its nomina-
tion in the manner prescribed in Section 2 at least two weeks before
the time of election. Independent nominations, signed by at least five
Resident Fellows and received by the Recording Secretary not later
than one week before the meeting for election, shall be inserted in the
call for that meeting.

784 STATUTES OF THE AMERICAN ACADEMY

CHAPTER IV.

Of THE President.

1. It shall be the duty of the President, and, in his absence, of the
senior Vice-President present, or next officer in order as above enumer-
ated, to preside at the meetings of the Academy ; to direct the Recording
Secretary to call special meetings ; and to execute or to see to the execu-
tion of the Statutes of the Academy. Length of continuous membership
in the Academy shall determine the seniority of the Vice-Presidents.

2. The President, or, in his absence, the next officer as above enumer-
ated, shall nominate members to serve on the different committees of the
Academy which are not chosen by ballot.

3. Any deed or writing to which the common seal is to be affixed
shall be signed and -sealed by the President, when thereto authorized
by the Academy.

CHAPTER V.
Of Standing Committees.

1. At the Annual Meeting there shall be chosen the following Stand-
ing Coramitlees, to serve for the year ensuing, viz. : —

2. The Committee on Finance to consist of three Fellows to be
chosen by ballot, who shall have, through the Treasurer, full control and
management of the funds and trusts of the Academy, with the power of
investing and of changing the investment of the same at their discretion.

3. The Rumford Committee, to consist of seven Fellows to be chosen
by ballot, who shall consider and report to the Academy on all applica-
tions and claims for the Rumford premium. They shall also report to
the Council in March of each year on all appropriations of the income of
the Rumford Fund needed for the coming year, and shall generally see
to the due and proper execution of the trust. All bills incurred on ac-
count of the Rumford Fund, within the limits of the appropriation made
by the Academy, shall be approved by the Chairman of the Rumford
Committee.

4. The C. M. Warren Committee, to consist of seven Fellows to be
chosen by ballot, who shall consider and report to the Council in INIarch
of each year on all applications for appropriations from the income of the
C. M. Warren Fund for the coming year, and shall generally see to the due

OF ARTS AND SCIENCES. 785

and proper execution of the trust. All bills incurred on account of the
C. M. Warren Fund, within the limits of the appropriations made by the
Academy, shall be approved by the Chairman of the C. M. Warren
Committee.

5. The Committee on Publication, to consist' of three Fellows, one
from each class, to whom all communications submitted to the Acad-
emy for publication shall be referred, and to whom the printing of the
Proceedings and Memoirs shall be entrusted. This Committee shall re-
port to the Council in March of each year on the appropriations needed
for the coming year. All bills incurred on account of publications, within
the limits of the appropriations made by the Academy, shall be approved
by the Chairman of the Committee on Publication.

6. The Committee on the Library, to consist of the Librarian ex
officio, and three other Fellows, one from each class, who shall examine
tlie Library and make an annual report on its condition and management.
This Committee, through the Librarian, shall report to the Council in
March of each year, on the appropriations needed for the Library for the
coming year. All bills incurred on account of the Library, within the
limits of the appropriations made by the Academy, shall be approved by
the Librarian.

7. The President and Recording Secretary shall be a Committee on
the general expenditures of the Academy. This Committee shall report
to the Council in March of each year on the appropriations needed for
the general expenditures for the coming year, and either member of the
Committee may approve bills incurred on this account within the limits
of the appropriations made by the Academy.

8. An auditing Committee, to consist of two Fellows, for auditing the
accounts of the Treasurer, with power to employ an expert and to ap-
prove his bill.

9. In the absence of the Chairman of any Committee, bills may be
approved by a member of the Committee designated by the Chairman
for the purpose.

CHAPTER VI.

Of the Secretaries.

1. The Corresponding Secretary shall conduct the correspondence of
the Academy, recording or making an entry of all letters written in its
name, and preserving on file all letters which are received ; and at each

VOL. XLII. — 50

786 STATUTES OP THE AMERICAN ACADEMY

meeting he shall present the letters which have been acMresserl to the
Academy since the last meeting. Under the direction of tlie Council,
he shall keep a list of the Resident Fellows, Associate Fellows, and
Foreign Honorary Members, arranged in their Classes and in Sections
in respect to the special sciences in which they are severally proficient ;
and he shall act as secretary to the Council.

2. The Recording Secretary shall have charge of the Charter and
Statute-book, journals, and all literary papers belonging to the Academy.
He shall record the proceedings of the Academy at its meetings; and
after each meeting is duly opened, he shall read the record of the jire-
ceding meeting. He shall notify the meetings of the Academy, apprise
officers and committees of their election or appointment, and inform the
Treasurer of appropriations of money voted by the Academy. He shall
post up in the Hall a list of the persons nominated for election into the
Academy ; and when any individual is chosen, he shall insert in the
record the names of the Fellows by whom he was nominated.

3. The two Secretaries, with the Chairman of the Committee of
Publication, shall have authority to publish such of the records of the
meetings of the Academy as may seem to them calculated to promote
its interests.

4. Every person taking any books, papers, or documents belonging to
the Academy and in the custody of the Recording Secretary, shall give a
receipt for the same to the Recording Secretary.

CHAPTER YII.

Of THE Treasurer.

1. The Treasurer shall give such security for the trust reposed in
him as the Academy shall require.

2. He shall receive all moneys due or payable to the Academy and
all bequests and donations made to the Academy. He shall pay all bills
due by the Academy, when approved by the proper officers (except those
of the Treasurer's office, which may be paid without such approval).
He shall sign all leases of real estate in the name of the Academy. All
transfers of stocks, bonds, and other securities belonging to the Academy
shall be made by the Treasurer with the written consent of one member
of the Committee of Finance. He shall keep an account of all receipts
and expenditures, shall submit his accounts annually lo the Auditing

OP ARTS AND SCIENCES, 787

Committee, and shall report the same at the expiration of his term of
office or vvlienever called on so to do by the Academy or Council.

3. Tlie Treasurer shall keep separate accounts of the income and
appropriation of the Rumford Fund and of -other special funds, and
report the same annually.

4. The Treasurer may appoint an Assistant Treasurer to perform his
duties, for whose acts, as such assistant, the Treasurer shall be responsi-
ble ; or the Treasurer may employ any Trust Company, doing business
in Boston, as agent to perform his duties, the compensation of such As-
sistaut Treasurer or agent to be paid from the funds of the Academy.

CHAPTER VIII.

Of the Librarian and Library.

1. It shall be the duty of the Librarian to take charge of the books,
to keep a correct catalogue of them, to provide for the delivery of books
from the Library, and to appoint such agents for these purposes as he
may think necessary. He shall make an annual report on the condition
of the Library.

2. The Librarian, in conjunction with the Committee on the Library,
shall have authority to expend such sums as may be appropriated, either
from the General, Rumford, or other special Funds of the Academy, for
the purchase of books, periodicals, etc., and for defraying other necessary
expenses connected with the Library.

3. To all books in the Library procured from the income of the
Rumfoid Fund, or other special funds, the Librarian shall cause a stamp
or label to be affixed, expressing the fact that they were so procured.

4. Every person who takes a book from the Library shall give a
receipt for the same to the Librarian or his assistant.

5. Every book shall be returned in good order, regard being had to
the necessary wear of the book with good usage. If any book shall
be lost or injured, the person to whom it stands charged shall replace
it by a new volume or set, if it belongs to a set, or pay the current
price of the volume or set to the Librarian ; and thereupon the remain-
der of the set, if the volume belonged to a set, shall be delivered to the
person so paying for the same.

6. All books shall be returned to the Library for examination at
least one week before the Annual Meeting.

788 STATUTES OF THE AMERICAN ACADEMY

7. The Librarian shall have custody of the Publications of the
Academy. With the advice and consent of the President, he may effect
exchanges with other associations.

CHAPTER IX.

Of Meetings.

1. There shall be annually four stated meetings of the Academy ;
namely, on the second AVednesday in May (the Annual Meeting), on
the second Wednesday in October, on the second Wednesday in January,
and on the second Wednesday in March. At these meetings, only, or at
meetings adjourned from these and regularly notified, or at special meet-
ings called for the purpose, shall appropriations of money be made, or al-
terations of the statutes or standing votes of the Academy be effected.

Special meetings shall be called by the Recording Secretary at the re-
quest of the President or of a Vice-President or of five Fellows. Notifi-
cations of the special meetings shall contain a statement of the purpose
for which the meeting is called.

2. Fifteen Resident Fellows shall constitute a quorum for the trans-
action of business at a stated or special meeting. Seven Fellows shall
be suflticient to constitute a meeting for scientific communications and
discussions.

3. The Recording Secretary shall notify the meetings of the Academy
to each Resident Fellow ; and he may cause the meetings to be adver-
tised, whenever he deems such further notice to be needful.

CHAPTER X.

Of the Election of Fellows and Honorary Members.

1. Elections shall be made by ballot, and only at stated meetings.

2. Candidates for election as Resident Fellows must be proposed by
two Resident Fellows of the section to which the proposal is made, in
a recommendation signed by them ; and this recommendation shall be
transmitted to the Corresponding Secretary, and by him referi-ed to the
Council. No person recommended shall be reported by the Council as a

OF ARTS AND SCIENCES. 789

candidate for election, unless he shall have received the approval of at
least five members of the Council present at a meeting. All nominations
thus approved shall be read to the Academy at any meeting, and shall
then stand on the nomination list until the next stated meeting, and until
the balloting. No person shall be elected a Resident Fellow, unless he
shall have been resident in this Commonwealth one year next preceding
his election. If any person elected a Resident Fellow shall neglect for
one year to pay his admission fee, his election shall be void; and if any
Resident Fellow shall neglect to pay his annual assessments for two
years, provided that his attention shall have been called to this article,
he shall be deemed to have abandoned his Fellowship ; but it shall be in
the power of the Treasurer, with the consent of the Council, to dispense
(siib silentio) with the payment both of the admission fee and of the
assessments, whenever in any special instance he shall think it advisable
so to do.

3. The nomination and election of Associate Fellows shall take place
in the manner prescribed in reference to Resident Fellows.

4. The nomination and election of Foreign Honorary Members shall
take place in the manner prescribed for Resident Fellows, except that
the nomination papers shall be signed by at least seven members of the
Council before being presented to the Academy.

5. Three-fourths of the ballots cast must be affirmative, and the
number of affirmative ballots must amount to eleven to effect an elec-
tion of Fellows or Foreign Honorary Members.

6. If, in the opinion of a majority of the entire Council, any Fellow —
Resident or Associate — shall have rendered himself unworthy of a
place in the Academy, the Council shall recommend to the Academy
the termination of his Fellowship ; and provided that a majority of two-
thirds of the Fellows at a stated meetinc;;, consisting of not less than
fifty Fellows, shall adopt this recommendation, his name shall be stricken
off the roll of Fellows.

CHAPTER XI.

Of Amendments of the Statutes.

1. All proposed alterations of the Statutes, or additions to them, shall
be referred to a committee, and, on their report at a subsequent stated
meeting or a special meeting called for the purpose, shall require for

790 STATUTES OF THE AMERICAN ACADEMY

enactment a majority of two-thirds of the members present, and at least
eighteen affirmative votes.

2. Standing votes may be passed, amended, or rescinded at a stated
meeting, or a special meeting called for the purpose by a majority of two-
thirds of the members present. They may be suspended by a unanimous
vote.

CHAPTER XII.

Of Literary Performances.

1. The Academy will not exjiress its judgment on literary or
scientific memoirs or performances submitted to it, or included in its
publications.

OP ARTS AND SCIENCES. 791

STANDING VOTES.

1. Communications of which notice has been given to the Secretary
shall take precedence of those not so notified.

2. Associate Fellows, Foreign Honorary jNIembers, and Resident
Fellows, who have jjaid all fees and dues chargeable to them, are en-
titled to receive one copy of each volume or article printed by the
Academy on application to the Librarian personally or by written oider
within two years of the date of publication. Exceptions to this rule
may be made in special cases by vote of the Academy.

3. The Committee of Publication shall fix from time to time the price
at which the publications of the Academy may be sold. But members
may be supplied at half this price with volumes which they are not
entitled to receive free, and which are needed to complete their sets.

4. Two hundred extra copies of each paper accepted for publication
in the Memoirs or Proceedings of the Academy shall be placed at the
disposal of the author, free of charge.

5. Resident Fellows may borrow and have out from the Library six
volumes at any one time, and may retain the same for three mouths, and.
no longer.

6. L'^pon special application, and for adequate reasons assigned, the
Librarian may permit a larger number of volumes, not exceeding twelve,
to be drawn from the Library for a limited period.

7. Works published in numbers, when unbound, shall not be
taken from the Hall of the Academy, except by special leave of the
Librarian,

8. Books, publications, or apparatus shall be procured from the
income of the Rumford Fund only on the certificate of the Rumford
Committee that they, in their opinion, will best facilitate and encourage
the making of discoveries and improvements which may merit the Rum-
ford Premium ; and the approval of a bill incurred for such purposes
by the Chairman shall be accepted by the Treasurer as proof that such
certificate has been given.

9. A meeting for receiving and discussing scientific communications
may be held on the second Wednesday of each month not appointed. for
stated meetings, excepting July, August, and September.

792 STATUTES OF THE AMERICAN ACADEMY.

RUMFORD PREMIUM.

In conformity with the terms of the gift of Benjamin, Count Rumford,
granting a certain fund to the American Academy of Arts and Sciences,
and with a decree of the Supreme Judicial Court for carrying into effect
the general charitable intent and purpose of Count Rumford, as ex-
pressed in his letter of gift, the Academy is empowered to make from
the income of said fund, as it now exists, at any Annual Meeting, an
award of a gold and a silver medal, being together of the intrinsic value
of three hundred dollars, as a premium to the author of any important
discovery or useful improvement in light or in heat, which shall have
been made and published by printing, or in any way made known to
the public, in any part of the continent of America, or any of the
American islands ; preference being always given to such discoveries
as shall, in the opinion of the Academy, tend most to promote the good
of mankind ; and to add to such medals, as a further premium for such
discovery and improvement, if the Academy see fit so to dO; a sum of
money not exceeding three hundred dollars.

IKDEX.

Academie de Macon, Medal of,
741.

Achesoii, Edward Goodrich, awarded
lluiiiford Preiiiiuiu, 74!), 754.

Acoustics, Architectural, 49-84.

Adams, J. M., Tlie Transiuission of
Kontgen Rays through Metallic
Sheets, 669-G97, 739.

Adiabatic Detenninatiou of the Heats
of Combustion of Organic Sub-
stances, especially Sugar and Ben-
zol, 571, 741.

Alcohol, Expansion and Compressi-
bility of, and of Ether, in tlie
Neighborhood of their Boiling
Points, 419.

Aldrovandi, Ulisse, Three hundredth
anniversary of death of, 743.

American Philosophical Society, Letter
from, 737.

Angell, J. B., Delegate, Lansing,
Mich., 744.

Animals, Racing, An approximate
Law of FatigTie in the Speeds
of, 273.

Antimony, The Determination of
Small Amounts of, by the
Berzelius-Marsli Process, 741.

Arsenic, The DeteiMnination of, by
tlie (iatlizeit Method, 741.

Arsenic in the Urine, The Determi-
nation of, 741.

Assessment, Annual, Amount of,
756.

Atkinson, Edward, Biographical no-
tice of, 701.

Atmos]ihere in the Tropics, Results
of the Franco-American Expedi-
tion to explore the, 2G1.

Atomic Weight of Bromine, A Revi-
sion of the, 199.

Bailey, S. I., Variable Stars in the
Globular Clusters, 758.

Bartlelt, II. II. See Robinson, B. L.,
and Bartlett, II. II.

Baxter, G. P., elected Resident Fel-
low, 758 ; A Revision of the
Atomic Weight of Bromine,
199-214.

Bell, Louis, On the Physiological Basis
of Illumination, 741.

Benzol, Adiabatic Determination of
the Heats of Combustion of, 571,
741.

Bermuda Biological Station for Re-
search, Contributions from, 461-
487.

Bermuda, The Hydroids of, 461, 739.

Berthelot, M., Death of, 744.

Berze]ius-]\Iarsh Process, The Deter-
mination of Small Amounts of
Antimony by the, 741.

Black, O. F. See Sanger, C. R., and
Black, O. F.

Blackman, M. W., The Spermatogen-
esis of the Myriapods : (V.) On
the Spermatocytes of Lithobius,
487-518, 741. _

Boltzmann, Ludwig, Death of, 737.

Bowditch, C. P., Report of Treasurer,
745.

Bromine, A Revision of the Atomic
Weight of, 199.

Brunetiere, F., Death of, 739.

Cabot, Samuel, Death of, 739.

Campbell, L. L. See Hall, E. H.,
Campbell, L. L., Serviss, S. B.,
and Churchill, E. P.

Capellini, G., Letter from, 743.

Carborundum, 749.

Celli, A., Delegate, Bologna, 744.

Cheever, D. W., resigns Fellowship,
742.

Chemical Laboratory of Harvard Col-
lege, Contributions from, 199, 571,
637, 717.

794

INDEX.

Churchill, E. P. See Hall, E. H.,
Campbell, L. L., Serviss, S. B.,
and Churchill, E. P.

Circuit, Long' Alternating-Current,
The Process of building up the
Voltage and Current in a, Gi)9,
744.

Cobalt, Canada, Cobalt and Silver
Deposits of, 743.

Cobalt and Silver Deposits of Cobalt,
Canada, 743.

Cole, L. J., An Experimental Study
of the Image-ForrainLT Powers of
Various Types of Eyes, 333-417.

Columbia University of the City of
New York, announcement of
Loubat prizes, 744.

Combustion, Concerning Position
Isomerism and Heats of, 637,
741.

Combustion of Organic Substances,
especially Sugar and Benzol, Con-
cerning the Adiabatic Determin-
ation of the Heats of, 571, 741.

Committees, Standing, appointed ,757 ;
List of, 771.

Compressibility and Expansion of
Ether and of Alcohol in the
Neighborhood of their Boiling
Points, 419.

Conductivity of Fused Electrolytes,
758.

Conductivity, Tliermal, in Soft Iron
between 115° and 204° C, On the
Thomson Effect and the Temper-
ature Coefficient of, 595.

Congdou, E. D., The Hydroids of
Bermuda, 461-485, 739.

Copelaud, M. See Mark, E. L., and
Copeland, M.

Corpuscular Theory, The, as applied
to Electric Conduction in Gases,
740.

Council, Report of, 761 ; Financial
Report of, 755.

Cross, C. R., Report of the Rumford
Committee, 748.

Cryptogamic Laboratory of Harvard
University, Contributions from,
175.

Current in a Long Alternating-Cur-
rent Circuit, The Process of
Building up the Voltage and,
699, 744.

Cylindrical Magnets of Different
Dimensions, Demagnetizing Fac-
tors for, 745.

Cytology of the Entomophthoraceae,
On the, 175.

Davis, W. M., The Eastern Escarp-
ment of the Mexican Plateau,

758.

Deam, C. C, New Plants from Guate-
mala, collected by, 742.

Delegation pour I'Adoption dune
Langue Auxiliaire Internation-
ale, Letter from, 738, 743.

Demagnetizing Factors for Cylindri-
cal Magnets of Different Dimen-
sions, 745.

Denny, Letter from, 744; resigns Fel-
lowship, 742.

Density, Conductivity, and Viscosity
of Fused Electrolytes, 758.

Diels, H., elected Foreign Honorary
^Member, 743 ; accepts Member-
ship, 744.

Dolbear, A. E., Letter from, 744.

Edes, H. H., letter from, 739.

Electrolytes, Fused, On the Density,
Conductivity, and Viscosity of,
758.

Electromagnet, On the Magnetic Be-
havior of the Finely Divided Core
of an, while a Steady Current is
being established in the Exciting
Coil, 740.

Electromotive Force, Counter, induced
in a ]\Ioving Coil Galvanometer
when the Instrument is used Bal-
listicallv, On the Correction for
the Effect of the, 159.

Electromotive Force, High, with its
Application to Spectrum Analy-
sis, 744.

Emerton, E., Delegate, Bologna, 744.

Entomophthoraceae, On the Cytology
of the, 175.

Equations, On Linear Differential, of
the Parabolic Type, 71 1 .

Ether, Expansion and Compressi-
bility of, and of Alcohol in the
Neigliborhood of their Boiling
Points, 419.

Eupatorieae. Diagnosesand Synonymy
of, and of Certain Other Compos-

INDEX.

795

itae which have been classed with
them, 32.

Eupatorieae, Studies in the, 1-48.

Everdingen, E. van, Director of the
Netherlands INIeteorological In-
stitute, 741.

Expansion and Compressibility of
Ether and of Alcohol in the
Neishborhood of their Boiling
Points, 419.

Eyes, An P^xpcri mental Study of the
Image-Forming Powers of Vari-
ous Types of, 333.

Fatigne, An Approximate Law of, in

the Speeds of Racing Animals,

273.
Fellows, Associate, List of, 777.
Fellows, Resident, deceased, —

Cabot, Samuel, 739.

Nash, B. H., 737.

Young, E. J., 737.
Fellows, Resident, elected, —

Baxter, G. P., 758.

Hall, Edward II., 743.

Lane, AV. C, 743.

Norton, C. L., 758.

Pierce, G. W., 758.

Riplev, W. Z., 743.
Fellows, Resident. List of, 773.
Fernald, M. L., Diagnoses of New

Spermatophytes from Mexico,

742.
Flora, Coniferous, of New England,

738.
Fluorescence and Magnetic Rotation

Spectra of Sodium Vapor, and

their Analyses, 233.
Fluorite, The Kathode-Luminescence

of, 742.
Foreign Honorary Members, de-
ceased, —

Berthelot, M., 744.

Boltzmann, L., 737.

Brunetiere, F., 739.

Foster, Sir M., 745.

Kirchhoft", A., 738.

Mendeleeff, D., 743.
Foreign Honorary Members,

elected, —

Diels, H., 743.

Retzius, M. G., 743.
Foreign Honorary Members, List of,

779.

Foster, Sir Michael, Death of, 745.

Franco- American Expedition to Ex-
plore the Atmosphere in the
Tropics, Results of the, 261.

Franklin, Benjamin, Certificate of
Membership in the Academy,
739; Medal of Anniversary of, 73/ .

Frevert, H. L. See Richards, T. W.,
Heuder.son,L.J.,aDdFrevert,lI L.

Galvanometer, Mirror, A Simple De-
vice for Measuring the Deflections
of a, 171.

Galvanometer, a JMoving Coil, On the
Correction for the Effect of the
Counter Electromotive Force in-
duced in, when the Instrument *
is used Ballistically, 159.

Gases, Friction and Force due to
Transpiration as Dependent on
Pressure in, 113.

General Fund, 745, 755 ; Appropria-
tions from the Income of, 756.

Geological Society of London, Letter
from, 744.

Gibson, J. A. See Sanger, C. R., and
Gibson, J. A.

Globular Clusters, Variable Stars in
the, 758.

Goodwin, H. ]M., and INIailey, R. D.,
On the Density, Conductivity,
and Viscosity of Fused Electro-
lytes, 758.

Graphite, 740.

Gray Herbarium of Harvard Univer-
sitv. Contributions from, 1, 519,
738, 742.

Greece, Ancient, On Some Elements
of Conservatism in, 738.

Greenman, J. M., New Species of
Senecio and Schoenocaulon from
Mexico, 742.

Guatemala, New Plants from, col-
lected by C. C. Deam, 742.

Guthzeit ^Method. The Determination
of Arsenic by the, 741.

Hall, Edward H., elected Resident
Fellow, 743; accepts Fellowship,
744.

Hall, Edwin II., Report of the Coun-
cil, 761.

Hall, Edwin II., Campbell, L. L.,
Serviss, S. B., and Churchill, E.

796

INDEX.

P., On the Thomson Effect and
the Temperature Coefficient of
Thermal Conductivity in Soft
Iron between 115° and 201° C,
595-6-_»().

Harvard College. See Harvard Uni-
versity.

Harvard University. See Chemical
Laboratory, Cryptogamic Labo-
ratory, Gray Herbarium, Jeffer-
son Physical Laboratory, and
Zoological Laboratory.

Heats of Combustion, Concerning Po-
sition Isomerism and, 711.

Heats of Combustion of Organic Sub-
stances, Concerning the Adia-
batic Determination of the, espe-
cially Sugar and Benzol, 571, 711.

Helogyne, The Genus, and its Syno-
nyms, 27.

Henderson, L. J. See Richards, T.
\V., Henderson, L. J., and Fre-
vert, H. L.

Henderson, L. J., Concerning Posi-
tion Isomerism and Heats of
Combustion, 637-647, 741.

Higginson, T. W., Biographical notice
of E. Atkinson, 761.

Hogg, J. L., Friction and Force due
to Transpiration as Dependent
on Pressure in Gases, 113-146.

Honey Bee, Some Stages in the Sper-
matogenesis of the, 101.

Hydroids, The, of Bermuda, 461, 739.

Illumination, On the Physiological
Basis of, 714.

Image-Forming Powers of Various
Types of Eyes, An Experimental
Study of the, 333.

Inheritance, A Study of, — The Optic
Chiasma of Teleosts, 215.

International Language, 738, 743.

Iron Particles, Fine, On the Permea-
bility and the lletentiveness of
a Mass of, 85.

Iron, Soft, between 115° and 204° C,.
On the Thomson Effect and the
Temperature Coefficient of Ther-
mal Conductivity in, 595.

Jamestown Exposition, Board of
Managers for Massachusetts, Let-
ter from, 738.

Jefferson Physical Laboratory, Con-
tributions from, 49, 85, 03, 113,
147, 159, 171,419, .595,669.

Jeffrey, E. E., The Ancient Conifer-
ous Flora of New England, 738.

Johnson, D. W., The Volcanic Necks
of the Mt. Taylor Region, New
Mexico, 743.

Kathode-Luminescence of Fluorite,
742.

Kennelly, A. E., An Approximate
Law of Fatigue in the Speeds of
Racing Animals, 273-331 ; The
I^rocess of Building up the Vol-
tage and Current in a Long Al-
ternating-Current Circuit, 699-
715,744.

Kingsley, J. S., resigns Fellowship,
745.

Kinnicut, L. P., Report of C. M.
Warren Committee, 754.

Kirchhoff, J. W. A., Death of, 788.

Laboratory of Histology and Embry-
ology, Western Reserve Univer-
sity, Contributions from, 487.

Lane, W. C, elected Resident Fel-
low, 743; accepts Fellowship,
744.

Larrabee, A. P., The Optic Chiasma
of Teleosts : A Study of Inherit-
ance, 215-231.

Law of Fatigue, An Approximate, in
the Speeds of Racing Animals,
273.

Librarian, Report of, 747.

Library, Aj^propriations for, 755.

Linne, Carl von, Anniversary of
birth of, 745.

Lithobius, Spermatocytes of, 487,
741.

Loudness, The Sensation of, 740.

Lowell, Percival, Temperature of
Mars. A Determination of the
Solar • Heat received, 649-667,
739.

Lyman, Theodore, The Corpuscular
Theory as a[)plied to Electric
Conduction in Gases, 740.

Mailey, R. D. See Goodwin, II. I\I.,

and Mailey, R. D.
Mark, E. L., Delegate to attend 7th

INDEX.

797

International Zoological Con-
gress. An Electric Wax-Cutter
for Use in Reconstructions. 627-
036, 740; Report of the Publi-
cation Committee, 751. See
Zoological Laboratory of the
Museum of Comparative Zool-
ogy at Harvard College, Contri-
butions from.

Mark, E. L., and Copeland, ]\r.,
Some Stages in the Spermatogen-
esis of the Honey Bee, 101-111.

Mars, Temperature of. A Determi-
nation of the Solar Heat re-
ceived, 649, 739.

]\Iendeleeff, I)., Death of, 743.

^Meteorological Observations in 190G
above the Tropical and Equato-
rial Atlantic, 74.5.

jNIeteorology, The, of the North and
Soutli Polar Zones, 740.

Mexican Plateau, The Eastern Es-
carpment of the, 758.

;Me.\ico, New or otherwise Note-
worthy Spermatophytes from,
742.

Mexico, New Species of Senecio and
Schoenocaulon from, 742.

^Michigan Agricultural College, Let-
ter from, ~A2.

]\Ioore, A. H., Revision of the Genus
Spilanthes, 519-569, 738.

Morse, IL W., The Kathode-Lumi-
nescence of Fluorite, 742.

Mt. Taylor Region, New Mexico, The
Volcanic Necks of the, 743.

Museo Xacional, Mexico, Letter from,
737.

Museum of Comparative Zoology at
Harvard College. See Zoologi-
cal Laboratory.

Musical Taste, The Accuracy of, in
regard to Architectural Acous-
tics, 49.

^lyriapods. Spermatogenesis of the,
487, 74L

Xash, Bennett IL, Death of, 737.

New York Academy of Sciences, Let-
ter from, 745.

Nichols, Ernest Fox, presented with
Rumford Medal, 741.

Norton, C. L., elected Resident Fel-
low, 758.

Observatorio Astronomico de la Plata,
Letter from, 737.

Oflicers, elected, 756; List of, 771.

Ophryosporus, Revision of the Genus,
17.

Optic Chiasma of Teleosts : A Study
of Inheritance, 215.

Orizaba, Mexico, An ascent of, 738.

(Orthogonal Functi(jns of Two Vari-
ables, On the Conditions to be
satisfied if tlie Sums of the
Corresponding Members of Two
Pairs of, are to be Themselves
Orthogonal, 147.

Peirce, B. O., On the Conditions to
be satisfied if the Sums of the
Corresponding Members of Two
Pairs of Orthogonal Functions
of Two Variables are to be
Themselves Orthogonal, 147-
157; On the Correction for the
Effect of the Counter Electromo-
tive Force induced in a Moving
Coil Galvanometer when the In-
strument is used Ballistically,
159-169; On the Length of the
Time of Contact in the Case of
a Quick Tap on a Telegraph Kev,
93-100; On the Magnetic Be-
havior of the Finely Divided
Core of an Electromagnet or of
a Transformer while a Steady
Current is being established in
the Exciting Coil, 740; On the
Permeability and the Retentive-
ness of a Mass of Fine Iron Parti-
cles, 85-91; A Simple Device
for JNIeasuring the Deflections
of a Mirror Galvanometer, 171-
174.

Permeability and the Retentiveness of
a Mass of Fine Iron Particles, On
the, 85.

Physiological Basis of Illumination,
On the, 744.

Pierce, George W., elected Resident
Fellow, 758.

Piqueria, Revision of the Genus, 1.

Pitch, Variation in Reverberation
with Variation in, 49.

Polar Zones, North and South, The
Meteorology of, 740.

Position Isomerism and Heats of

798

INDEX.

Combustion, Concerning, 637,

741.
Pressure in Gases, Friction and

Force due to Transpiration as

Dependent on, 113.
Pritchett, H. S., resigns Fellowship,

742.
Publication, Appropriation for, 740,

756.
Publication Committee, 771"; Re-
port of, 754.
Publication Fund, 746.

Racing Animals, An Approximate
Law of Fatigue in the Speeds
of, 273.

Reale Universita Napoli, Letter from,
737.

Reconstructions, An Electric Wax-
Cutter for Use in, 627, 740.

Records of Meetings, 737.

Research Laboratory of Physical
Chemistry, Contribution from,
758.

Retentiveness of a Mass of Fine Iron
Particles, On the Permeability
and the, 85.

Retzius, M. G., elected Foreign Hon-
orary Member, 743 ; accepts
Membership, 745.

Reverberation, Variation in, with
Variation in Pitch, 19.

Richards, T. W., Henderson, L. J.,
and Frevert, H. L., Concerning
the Adiabatic Determination of
the Heats of Combustion of
Organic Substances, especially
Sugar and Benzol, 571-593,
741.

Riddle. L. W., On the Cytology of the
Entomophthoraceae, 175-197.

Ripley, W. Z., elected Resident Fel-
low, 743 ; accepts Fellowship,
744.

Robinson, B. L., New or Otherwise
Noteworthy Spermatophytes,

chiefly from Mexico, 742 ; Stud-
ies in the Eupatorieae : (I.) Re-
vision of the (ienus Piqxieria ;
(II.) Revision of the Genus
Oph n/os!porus ; (H L ) The Genus
Helof/i/ne and its Synonyms ;
(IV.) Diagnoses and Synonymy
of Eupatorieae and of certain

other Compositae which have been
classed with them, 1-48.

Robinson, B. L., and Bartlett, 11. II.,
New Plants from Guatemala,
collected by C. C. Deam, 742.

Rontgen Rays through jNIetallic
Sheets, The Transmission of,
669, 739.

Rotch, A. L., Meteorological Obser-
vations in 1906 above the Tropi-
cal and Equatorial Atlantic, 745 ;
Report of Librarian, 747 : Re-
sults of the Franco-American
Expedition to Explore the At-
mosphere in the Tropics, 261-272.

Rumford Committee, Report of, 748 ;
Reports of Progress to, 749.

Rumford Fund, 746; Appropriations
from the Income of, 756 ; Papers
published by Aid of, 233, 419,
571, 595, 637, 649, 669.

Rumford Premium, 792 ; award of,
741, 754.

Sabine, W. C, Architectural Acous- ,
tics, 49-84; The Sensation of
Loudness, 740.

Sanger, C. R., and Black, O. F., The
Determination of Arsenic by the
Guthzeit Method, 741 ; The De-
termination of Arsenic in the
Urine, 741.

Sanger, C. R., and Gibson, J. A.,
The Determination of Small
Amounts of Antimony by the
Berzelius-Marsh Process, 717-
733, 741.

Sawyer, E. F., resigns Fellowship,
745.

Schoenocaulon, New Species of,
from Mexico, 742.

Semenov, Pierre de, 80th anniversary
of, 741.

Senecis, New Species of, from Mex-
ico, 742.

Seventh International Zoological Con-
gress, Invitation from, 741.

Serviss, S. B. See Hall, E. H., Camf^
bell, L. L., Serviss, S. B., and
Churchill, E. P.

Shuddemagen, C. L. B., The Demag-
netizing Factors for Cylindrical
Magnets of Different Dimen-
sions, 745.

I

INDEX.

799

Sliarples, S. P., Cobalt and Silver
Deposits of Cobalt, Canada,
743.

Silver Deposits of Cobalt, Canada,
743.

Smith, A. W., Expansion and Com-
pressibility of Ether and of Al-
cohol in the Neighborliood of
their Boiling Points, 41!i-4(i0.

Smith, Jeremiah, resigns Fellowship,
742.

Smith, M. M., On Linear Differential
Equations of the Parabolic Type,
741.

Smyth, H. W., On Some Elements of
Conservatism in Ancient (Jreece,
738.

Societe Imperiale russe de Geographie,
Letter from, 741.

Sodium Vapor, Fluorescence and
Magnetic Rotation Spectra of,
and their Analysis, 233.

Sokolow, N., Death of, 744.

Solar Heat received, A Determination
of the Temperature of Mars, 64!),
739.

Solenoids, Cylindrical, On the Self
and Mutual Inductance of,
742.

Spectra, Magnetic Rotation, Fluores-
cence and, of Sodium Vapor, and
their Analysis, 233.

Spectrum Analysis, High Electromo-
tive Force with its Application to,
744.

Spermatocytes of Lithobius, 4S7,
74L

Spermatogenesis of the Honey Bee,
Some Stages in the, lOL

Spermatogenesis of the Myriapods,
487, 741.

Spermatophytes from Mexico, Diag-
noses of New, 742.

Spermatophytes, Xew or otherwise
Noteworthy, chiefly from Mexico,
742.

Spilanthes, Revision of the Genus,
519, 738.

Standing Committees, appointed, 757;
List of, 771.

Standing Votes, 753.

Stars, Variable, in the Globular Clus-
ters, 758.

Statutes, 781 ; amendment of, 740.

Sugar, Adiabatic Determination of
the Heats of Combustion of,
571.

Swain, G. F., appointed to represent
Academy at University of Penn-
sylvania, 738.

Syracuse University. See Zoological
Laboratory, Syracuse University.

Telegraph Key, On the Length of
Time of Contact in the Case of a
Quick Tap on a, 93.

Teleosts, The Optic Chiasma of, 215.

Temperature Coetiicient of Thermal
Conductivity in Soft L'on be-
tween 11.5° and 204° C, 595.

Temperature of Mars, A Determina-
tion of the Solar Heat received,
649, 739.

Thermal Conductivity in Soft Iron
between 115° and 201° C, On
the Thomson Effect and the
Temperature Coefficient of, 595.

Thomson Effect and the Temperature
Coefficient of Thermal Conduc-
tivity in Soft Iron between 115°
and 204° C, 595.

Time of Contact, On the Length of,
in the Case of a Quick Tap on a
Telegraph Key, 93.

Transformer, On the Magnetic Be-
havior of the Finely Divided
Core of an Electromagnet or of
a, while a Steady Current is
being established in the Exciting
Coil, 740.

Transpiration, Friction and Force due
to, as Dependent on Pressure in
Gases, 113.

Treasurer, Report of, 745.

Tropics, Results of the Franco-Amer-
ican Expedition to explore the
Atmosphere in the, 261.

Trowbridge, J., High Electromotive
Force with its Application to
Spectrum Analysis, 744.

University of Pennsylvania, Letter

from, 737.
University of Vienna, Letter from,

737.
Urbina, Manuel, Death of, 737.
Urine, The Determination of Arsenic

in the, 741.

800

INDEX.

Viscosity of Fused Electrolytes, 758.

Voltage and Current in a Long Al-
ternating-Current Circuit, Tlie
Process of Building up the, 699,
744.

Walcott, C. D., elected Secretary of
Smithsonian Institution, 743.

Ward, R. DeC, The Meteorology
of the North and South Polar
Zones, 740.

Warren (C. M.) Committee, Report
of, 754.

Warren (C. M.) Fund, 746; Appro-
priation from the Income of,
756.

Water-levels, The Ancient, of the
Champlain and Hudson Valleys,
738.

Wax-Cutter for Use in Reconstruc-
tions, An Electric, 627, 740.

Webster, A. G., On the Self and
Mutual Inductance of Cylindri-
cal Solenoids, 742.

Western Reserve University. See
Laboratory of Histology and
Embryology, Western Reserve
University.

Wolff, J. E., An Ascent of Orizaba,
Mexico, 738.

Wood, R. W., Fluorescence and Mag-
netic Rotation Spectra of Sodium
Vapor, and their Analysis, 233-
260.

Woodworth, J. B., The Ancient
Water-levels of the Champlain
and Hudson Valleys, 738.

Young, Edward J., Death of, 737.

Zoological Laboratory of the Museum
of Comparative Zoology at Har-
vard College, E. L. Mark, Direc-
tor, Contributions from, 101, 215,
333, 627.

Zoological Laboratory, Syracuse Uni-
versity, Contributions from,
461.

U.

MBI. WHOI LIBRARY

H iiK&a fi

^rr/