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■- "^HOS-.S^I.i
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ilorbarb CoUege lArarp
FROM
The bequest of
Frederic H. Lewie
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BIOLOGY
AND ITS MAKERS
IVitb portraits and Other Illustrations
WILLIAM A. LOCY, Ph.D., Sc.D.
Prt/tsur /■ Ntrilmaart U'niraty
SECOND EDITION. REVISED
NEW YORK
HENRY HOLT AND COMPANY
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nou
The bequest of
Frederic H. Lewis
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BIOLOGY
AND ITS MAKERS
JVitb Portraits and Other Illustrations
WILLIAM A. LOCY. Ph.D., ScD.
Pn/iiar in Neriimittrn Univiraly
SECOND EDITION. REVISED
NEW YORK
HENRY HOLT AND COMPANY
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2 "Z'^cs". ^i, I
A///3ao7:cA-
IuniversityI
LIBRARY
VmmmJ
COFVRIOMT, 1908,
HENRV HOLT AND COMPANY
Published June 1908
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To
MY GRADUATE STUDENTS
Who have worked by my lide in the Laburacory
Inipired by the belief that those who seek shall linii
This account of the findings of some of
The great men of biological science
Is dedicated by
Thb Author
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PREFACE
The writer is annually in receipt of letters from students,
teachers, ministers, medical men, and others, asking for in-
formation on topics in general biology, and for references to
the best reading on that subject. The increasing frequency
of such inquiries, and the wide range of topics covered, have
created the impression that an untechnical account of the
rise and progress of biology would be of interest to a con-
siderable audience. As might be surmised, the references
most commonly asked for are those relating to different
phases of the Evolution Theory; but ihe fact is usually over-
looked by the inquirers that some knowledge of other features
of biological research is essential even to an intelligent com-
prehension of that theory.
In this sketch I have attempted to bring under one view
the broad features of biological progress, and to increase the
human interest by writing the story around the lives of the
great I.eaders. The practical execution of the task resolvcfl
ilsclf largely into the question of what to omit. The number
of detailed researches ujTOn which progress in biologj' rests
made rigid selection necessar\', and the difficulties of separat-
ing the essential from the less important, and of distinguish-
ing between men of temporarj- notoriety and those of endur-
ing fame, have given rise to no small perplexities.
The aim has been kept in mind to give a ])icture suffi-
ciently diagrammatic not to confuse the general reader, and
it is hoped that the omissions which have seemed nccessar)-
will, in a measure, be compensated for by the clearness of
the picture. References to selected books and articles have
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been given at the close of the volume, that will enable readers
who wish fuller information to go to the best sources.
The book is divided into two sections. In the first are
considered the sources of the ideas — except those of organic
evolution^that dominate biologj, and ihe steps by which
they have been molded into a unified science. The Doc-
trine of Organic Evolution, on accouni of its importance,
is reserved for special consideration in the second section.
This is, of course, mercl\' a division of convenience, since
after its acceptance the doctrine of evolution has entered
inio all phases of biological j)rogress.
The portraits wiih which the text is illustrated embrace
those of nearly all Ihe founders of biologv'. Some of the
rarer ones are unfamiliar even to biologists, and have been
discovered only after long search in the libraries of Europe
and .\mcrica.
An orderly account of the rise of biolog}' can hardly fail
to be of scr\'ice to the class of inquirers mentioned in the
opening paragraph. It is hoped that this sketch will also
meet some of the needs of (he increasing body of students
who are doing practical work in biological laboratories. It is
important that such students, in addition to the usual class-
room inslruclion, should get a perspective view of the way
in which biological science has come inio its present form.
The chief purjwse of the book will have been met if I
have succeeded in indicating the sources of biological ideas
and the main currents along which ihey have advanced, and
if I have succeedal, furthermore, in making readers ac-
quainted with those men of noble purpose whose work has
created (he epochs of biological history, and in showing that
there has been continuity of development in biological
thought.
Of biologists who may examine this work with a critical
purpose, I beg that they will think of it merely as an outline
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sketch which docs not pretend to give a complete history of
biological thought. The story has been developed almost
entirely from the side of aninial life; not that the botanical
side has been underestimated, but that the story can be told
from cither side, and my first-hand acquaintance with botan-
ical investigation is not sufllcicnt to justify an attempt to es-
timate its jjarticular achievements.
The writer is keenly aware of the many imperfections in
the book. It is inevitable that biologists with interests in
special fields will miss familiar names and the mention of
special pieces of notable work, but I am drawn to think that
such omissions will be viewed leniently, by the consideration
that those best able to judge the shortcomings of this sketch
will also best understand the difficulties involved.
The author wishes to acknowledge his indebtedness to
several publishing houses and to individuals for permission
to copy cuts and for assistance in obtaining portraits. He
takes this opportunity to express his best thanks for these
courtesies. The [jarties referred to are the director of the
■ American Museum of Natural History; D. Appleton & Co.;
P. Blakiston's Sons & Co.; The Macmillan Company;
The Open Court Publishing Company; the editor of the
Popular Science Monthly; Charles Scribncr's Sons; Pro-
fessors Bateson, of Cambridge, England; Conklin, of Phila-
delphia; Joubin, of Rcnncs, France; Nierstrasz, of Utrecht,
Holland ; Newcombe, of Ann Arbor, Michigan; Wheeler and
E. B. Wilson, of New York City. The editor of the Popu-
lar Science Afontkly has also given permission to reprint the
substance of Chapters IV and X, which originally ap-
peared in that publication.
W. A. L.
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CONTENTS
The Sources of Biological Ideas Except Those of
Organic Evolution
CHAPTER I
An Outline of the Rise o
Notable advances in natural science during the nineteenth century, 3.
Biology the central subject in the history of opinion regarding
hfc, 4. It is of commanding importance in the world of science,
5. DifTicullies in malting its progress clear, 5. Notwithstanding
its numerous details, there has been a relatively simple and
orderly progress in biology, 6. Many books almut the facts of
biology, many encellent laboratory manuals, but scarcely any
attempt to trace the growth of biological ideas, 6. The growth
of knowledge regarding organic nature a long slor}' full of human
interest. 7. The men of science, 7. The stor)' of their aspira-
tions and struggles an inspiring history, S. The conditions under
which science developed, 8. The ancient Greeks studied nature
by observation and experiment, but Ibis method underwent
eclipse, 9. Aristotle the founder of natural history, g. Science
before his day, 9, 10. Aristotle's (losition in the dovelo[)ment of
science, it. His extensive knowledge of animals, ii- Hisscien-
lific writings, 13. Personal appearance, 13. His influence. 15.
Pliny: his writings mark a decline in scientific method, 16. The
arrest of inquiry and its effects, 17. A complete change in the
mental interests of mankind. 17. Men cease to observe and in-
dulge in metaphysical speculation, 18. Authority declared the
source of knowledge, 18. The revolt of the intellect against these
conditions, 19, The renewal of observation, ig. The beneficent
results of this movement, jo. Enumeration of the chief epochs
in biological history: renewal of observation, ao; the overthrow
of authority in science, lo. Harvey and e:(perimental ini-estiga-
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tion, zo; introduction of microscopes, zo; Linnsus, lo; Cuvier,
lo; Bichat, 3i; Von Baer, 31; the rise of physiology, zi; the
beginnings of evolutionary thought, at; the cell-theory, zr; the
discoveiy of protoplasm, 31.
Vesalius and the Overthkow of Authority m SaENCE, .
Vesalius, in a broad sense, one of the founders of biology, zz. A pic-
ture of the condition of anatomy before he look it up, 23. Galen:
his great influence as a scientific writer, 24. Anatomy in the
Middle Ages, 14. Predecessors of Vesalius: Mundinus, Beran-
garius, Sylvius, z6. Vesalius gifted and forceful, 37. His im-
petuous nature, 37. His reform in the teaching of anatomy, 38.
His physiognomy, 30. His great book (1543), 30. A descrip-
tion of its illustrations, 30, 31. Curious conceits of the artist, 33.
Opposition to Vesalius: curved ihigh bones due to wearing tight
trousers, the resurrection bone, 34, 35. The court physician, 3-;.
Close of his life, 36. Some of his successors: Euslachius and
Fallopius, 36. The especial service of Vesalius; he overthrew
dependence on authority and reestablished the scientific method
of ascertaining truth, 37, 38.
CHAPTER m
William Habvev and Expefibental Observation, . . . ,
Harvey's work complemental to that of \'esalius, 30. Their com-
bined tabors laid the foundations of the modem method of in-
vestigating nature, 39. Har\'ey introduces experiments on living
organisms, 40. Harvey's education, 40. At Padua, comes
under the influence of Fabricius, 41. Return 10 England, 43.
His personal qualities, 43-45. Harvey's writings. 45. His great
classic on movement of the heart and blood (i6z8). 46. His
demonstration of circulation of the blood based on cogent rea-
soning; he did not have ocular proof of its passage through
capillaries, 47. Views of his predecessors on the movement of
the blood, 48. Servetus, ;o. Rcaldus Columbus, 50. Caisal-
pinus, ji. The originality of Harvey's views, 51. Har^■ey's
argument, 51. Harvey's influence, 53. A versatile student;
work in other directions, 52. His discovery of the circulation
created modem physiology, 5a. His method of inquiry became
a permanent part of biological science, 53,
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CHAPTER IV
D THE PnOCHESS OP INDB-
The Inthoddctton or the Microscope ai
PENDENT Observation
The pioneer micioscopists: Hooke and Grew in England; Malpighi
in Italy and Swammerdara and Lceuwenhock in Holland, 54.
Robert Hooke, 55. His microscope and the micrographia (1665),
56. Grew one of the founders of vegetable histology, 56. Mal-
pighi, i638-~i6-)4, 58. Penonal qualities, 58. Education, 60.
University positions, 60, 61. Honors at home and abroad, 61.
Activity in research, 62. His principal mitings: Monograph
on Ihe silkworm, 63; anatomy of plants, 66^ work in embry-
ology, 66. Jan Swammerdam, 1637-1680, 67. His lemperamenl,
67. Early interest in natural history, 68. Studies medicine, 63.
Important observations, 68. I>evotes himself 10 minute anat-
omy, 70. Method of working, 71, Great intensity, 70. High
quality of his work, 71. The Bibtia Nalura, 73. Its publica-
tion delayed until fifty-seven years after his death, 73. Illustra-
tions of his anatomical work, 74-76. Antony van Lecuwenhock,
1631-1713, 77, A composed anil better-balanced man, 77, Self-
taught in science, the effect of this showing in the desultory char-
acter of his observations. 77, 87. Physiognomy, 78. New bio-
graphical facts, 78. His love of inicrascopic observation, 80,
His microscopes, 81. His scientific letters, 83. Observes the
capillary circulation in 1686, 84. His other discoveries, 86.
Comparison of the three men: the two university -trained men
left coherent pieces of work, that of Leeuwcnhock was discursive,
87. The combined force of their labors marks an epoch, 88.
The new intellectual movement now well under way, 88.
CHAPTER V
F MlNtJTE AnAI
Progress in minute anatomy a feature of the eighteenth century.
Altracliveness of insect anatomy. Enthusiasm awakened by the
delicacy and perfection of minute structure, Sq. Lyonet, 1707-
1789, go. Description of hia remarkable monograph on the
anatomy of the willow caterpillar, 91. Selected illustrations,
gi-Q4. Grcatdeuil — 4,041 muscles, <)l- Extraordinary character
of his drawing, 90. A model of detailed dissection, but lacking
in comparison and insight, 91. The work of Reaumur, Roesel,
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and DeGcer on a higher plane as regards knowledge of insecl life,
95. StTaus-Diln:kheim'smonographoninse<:lana.lomy,96, Rivals
that of Lyonet in detail and in the execution of the plates, 99.
His general considerations now antiquated, qg. He attempted
to make insect anatomy comparative, 100. Dtifour endeavors to
found a broad science of insect anatomy, 100. Newport, a very
skilful dissector, with philosophical cast of mind, who recognizes
the value of embryology in anatomical work, 100. Leydig starts
a new kind of insect anatomy embracing microscopic structure
(hislolog)') I 103- This the beginning of modem work, 103.
Structural studies on other small animals, 103. The discovery
of the simplest animals, 104. Observations on the micnMcopic
animalcula, 105. The protozoa discovered in 1675 by Leeuwen
hoek, 105. Work of O. F. Muller, 1786, 106. Of Ehrenbeig
1838, 107. Recent observations on protozoa, loy.
CHAPTFR VI
LiNN«DS AND Scientific Natural Histobv. 1
Natural histor)- had a parallel development with comparative anatomy,
1 10. The Physiologus, or sacred natural history of the Middle
Ages, 110, HI. The lowest level reached by zoiilogy, 11 1. The
return lo the science of Aristotle a real advance over the Physiol-
ogus, 111. The advance due to Wnllon in 1553, iii. Gesner,
1516-1565. High quality of his Jlistoria Animaliiiin, 111-114.
The scientific writings of Jonson and Aldrovandi, 114. John
Ray the forerunner of Linnsus, iij. His writings, 117. Ray's
idea of species, 117. Linnams or Linne, iiS. A unique ser-
vice 10 natural history. Brings the binomial nomenclature into
general use, 118. Personal history, 119. Quality of his mind,
120. His early struggles with poverty, uo. Gets his degrc-e in
Holland, iii. Publication of the Systrma Xatura in 1735, 121.
Return lo Sweden, 123. Success as a university pn)feS50tin l'|i-
Sala, 133. Personal appearance, 125. His influence on natural
history, 125. His especial service, ii6. His idea of s[«icies,
j*8. Summary, 129. Reform of the I.innjian system, 130-
138. The necessity of reform, 130. The scale of being, 131.
Lamarck the first to use a genealogical tree, 132. CuiHer's
tour btanchi'S, 131. .^Iterations by Von Sielmld and Leuckarl,
134-1.1;. Tabularriewof flassificalions, 13S. General liioli.gi-
cal projcess from I-innitusi lo Darwin, .Mlhiiugh delails wi-rc
niulliplicd, pnign-s-s was by a scries of steps, ij8. Analysis
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of animals proceeded from the organism to organs, from organs
lo tissues, from tissues to cells, the elementary parts, and finally
to protoplasm, 139-140, The physiological ade had a par-
allel development, 140.
CHAPTER VII
CuVIER AND TBE RiSE OT COMPARATIVE ANATOMV, . . . . I4I
The study of internal structure of living beings, at first merely de-
scriptive, becomes comparative, 141. Belon, 141. Severinus
writes the first book devoted to comparative anatomy in 1645,
143. The anatomical studies of Camper, 143. John Hunter,
144. Personal characteristics, 145. His contribution to prog-
ress, 146. Vicq d'Azyr the greatest comparative anatomist
before Cuvier, 146-148. Cuvier makes a comprehensive study
of ihe structure of animals, 14S. His birth and early education,
149. Life at the sea shore, 150, Six years of quiet study and
contemplation lays the foundation of his scientific career, 150.
Goes to Paris, 151. His physiognomy, 152. Comprehensiveness
of his mind, 154. Founder of comparative anatomy, 155. His
domestic life, 155. Some shortcomings, 156. His break with
early friends, 156. Estimate of George Bancroft, 156. Cuvier's
successors: Milne-Edwards, 157; Lacaze-Duthicrs, 157; Rich-
ard Owen, 158; Oken, 160; J. Fr. Meckel, i6a; Ralhbe, 163;
J. MOller, 163; Kari Gegenbaur, 164; E. D. Cope, 165. Com-
parative anatomy a rich subject, 165. It is now becoming exper-
imental, 165.
CHAPTF,R VIII
BtCHAT AND THE BlRTH OF HISTOLOGY, l66
Bichat one of the foremost men in biological history. He carried the
analysisof animal organization lo a deeper level than Cuvier, 166.
Buckle's estimate, 166. Bichat goes to Paris, 167. Attracts at-
tention in Desault's classes, 167. Goes to live with Desault, 168.
His fidelity and phenomenal industry, 168. Personal appear-
ance, 168. Begins to publish researches on tissues at the age of
thirty, 170. His untimely death at thirty-one, 170. InBuencc
of his writings, 170. His more notable successors; Schwann,
171; Koelliker, a striking figure in the development of biology,
171; Max Schultze, 172; Rudolph Virchow, 174; Leydig, 175;
Ramon y Cajal, 176. Modem text-books on histology, 177.
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CHAPTER IX
The Rise of Physiology — Habvev. Haller. Johannes MOlleh, 179
Physiology had a parallel development wilh anatom)', 179. Physiol-
ogy "f '*"" ancients, 179. Galen, 180. Period of Harvey, 180.
His demonstration of circulation of the blood, iSo. His method
ot experimental investigation, 181. Period of Haller, 181. Phys-
iology developed as an independent science, iSj. Haller's per-
sonal characleristics, 181. His idea of vital force, 1S2. His book
on ihc Elements of PhyEtiology a valuable work, 183, Discovery
of oxygen by Pricsltey in 1774, 183. Charles Bell's great discov-
ery on the nervous system, 183. Period of Johannes Mii Her, 184.
A man of unusual gifts and [lersonal altracliveness, 185. His
personal appearance iSi; His great influence over students, 185.
His esjiecial service was to make physiologj' broadly comparative,
186. His monumental Handbook of Physiology, 186. Unex-
ampleii accuracy m olscrialion 186. Introduces the principles
ot [sychology into phisiilogj 186 Physiology after MUUer,
188-195. Ludwig 188 Du Bois-Reymond, 189. Claude
Bernard, iijo. Two directions of growth in physiology — the
chemical an<l the physical jiji Influence upon biology, 19J.
Other great names in phvsiologi 194.
CHAPTKR X
IlAKH AS-D THE RlSE OF EsiBKVOLOGV r
imantic nature ot cmbrj-ologj-, 195. Its importance, 195. Rudi-
nientiiry organs and their meaning, 195. The domain of em-
brj'ology, 196. Five historical periods, 196. The period ot
Harvey and Mnlpighi, 197-205. The embtyological woA of
these l«*o men insufficiently reingnized. 197. Harvey's pioneer
allem[)t crilitally to analyze the process of development, 198. His
leaching regarding the nature ot development, 199. His treatise
on Gcnerafion, 199. The frontispiece of ihe edition of 165:, Joi,
302. Malpighi's papers on the formation of the chick within ihe
egg, SOI. Quality of his pictures, 103. His belief in preformation,
807. Mal[righi's rank as embrj'ologist, 105. The period of
WollI, 105-114. Rise ot Ihc theory of prcdclineation, io6.
Sources of the idea thai the embryo is preformed mihio the egg,
307. Maljiighi's observations quoted, 307. Swammerdam's
view, 108. l.ieuwcnhoek and the discovery of the sperm, 208.
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CONTENTS ;
Bonnet's views on embollemfnl. 20S. WollT opposes the doclrini-
of pretormation, 210. His famous Theory of Generation (1759),
a 10. Sketches from this treatise, log. His views on the directing
force in development, 211. His highest ^adc of work, zii.
Opposition of Haller and Bonnet, in. Restoration of Wolff's
views by Mecltet, 212. Personal characteristics of Wolff, iij.
The period of Von Baer, 2i4-32». The greatest personality in
embryology, 215. His monumental work on the Development of
Animals a choice combination of obsc-valion and reflection, 215.
\'on Baer's especial service, 117. Establishes the germ-layer
theory, ai8. Consequences, 2i<). His influence on embryology,
120. The period from Von Baer to Balfour, 222-226. The proc-
ess of development brought into a new light by the cell-theory,
222. Rathke, Remak, Koelliker, Huxley, Kowatcvsky, 223, 224.
Beginnings of the idea of germinal continuity, 125, Influence of
the doctrine of organic evolution, 226. The period of Balfour,
»-ith an indication of present tendencies, 226-236. The great
influence of Balfour's Comparative Embryology, 226. Person-
aim of Balfour, 228. His tragic fate, 218. Interpretation of the
embnolcigical record, 22g. The recapitulation theory, 230.
Oiikar Hen«ng 232. U'ilhtlm His. 232. Recent tendencies;
Pipinmintal embr>'olog>', 232; Cell-lincagc, 234; Theoretical
CH.^PTKR XI
The <'f,ll-Theor\— Schleiden. Schwass. Schultze, . . 2
Unifying power of the cell-theori', 237. Vague foreshadowings, 237.
The first pictures of cells from Robert Hookc's Micrographia, 238.
Cells as depicted by Malpighi, Grew, and Leeuwenhoek, I3g, 240.
Wolff on cellular structure, 340, 241. Oken, 241. The an-
nouncement of the cell-lheorj' in 1838-3Q, 242. Schleiden and
Schwann co-founders, 243. Schleidcn's work, 343. His ac-
quaintance with Schwann, »43. Schwann's personal appearance,
244. Influenced by Johannes MQlIer, 245. The cell-theory his
must Important work, 246. Schleiden, his lemjicramcnt and dis-
position, 247. Schleiden's contribution to the ccll-theorj-, 247.
Errors in his observations and conclusions, 248. Schwann's
trcatis", 248. Purpose of his researches, 24q. Quotations from
his mirrosciipical researches, 24<). Schwann's part in eatabli.sh-
ing the cell-theori' more important than that of Schleiden, 250.
Modification of the cell-theory, 250. Necessity of modifications,
2JO. The liiscovtrj- of pmloplasm, and its effect on the cell-
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XVI CONTENTS
theory, ajo. The cell-lheory becomes harmonized with the pro-
toplasm doctrine of Max Schulize, 251. Further modifications of
the cell-theory, 251. Origin of ceUs in tissues, 251. Structure of
the nucleus, 153. Chromosomes, 254. Cenirosome, 256. The
principles of heredity as telated to cellular studies, 257. V'cr-
wotn's definition, 258. Vast importance of the ccll-lhcory in
advancing biology, zjS.
CHAPTER XII
Protoplasm the Physical Basis op Life 159
Great influence of the protoplasm doctrine on biological progress, 259.
Protoplasm, 259. Its properties as discovered by examination of
the amceba, 260, Microscopic examination of a transparent leaf,
z6i. Unceasing activity of its protoplasm, 161. The wonderful
energies of protoplasm, 361. Quoialion from Htutley, »62. The
discovery of protoplasm and the essential steps in recognizing
the part it plays in living beings, 162-275. Dujardin, 262. His
pccEonality, 263. Education, 263. His contributions to science,
264. His discovery of "sarcode" in the simplest aiumab, in 183S,
266. Purkinje, in 1840, uses the teim protoplasma, 267. Von
Mohl, in 1846, brings the designation protoplasm into general
use, 26S. Cohn, in 1850, maintains the idenlity of sarcodc and
protoplasm, 270. Work of De Bary and Virchow, 172. Max
SchulUe, in 1861, shows that there is a broad likeness between
the protoplasm of animals and plants, and establishes the proto-
plasm doctrine. The university life of Schullze. His love of
music and science. Founds a famous biological periodical, 272-
274. The period from 1840 to i860 an important one for biol-
ogy, 274.
chapter xiii
The Work of Pasteur, Koch, and Others, 876
The bacteria discovered by Leeuwenhoek in 1687, 276. The develop-
ment of the science of bacteriology of great importance 10 the
human race, 176. Some general topics connected with the study
of bacteria, 177. The spontaneous origin of life, 377-?g3. Bio-
genesis or abiogenesis, 377. Historical development of the ques-
tion, 377. I. From Aristotle, 325 B.C., to Rcdi, 1668. 278. The
spontaneous origin of living forms universally believed in, 378.
Illustrations. 378. II. From Rcdi 10 Schwann, 378-184. Redi,
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in i66S, puts the question to experimental test and overthrows
the belief in the spontaneous origin of fonns visible to the un-
aided eye, 179. The problem narrowed to the origin of micro-
scopic animalcula, i8r. Needham and Bufion test the ques-
tion by the use »f tightly corked vials containing boiled or-
ganic sotulions, 381. Microscopic life appears in their infusions,
282. Spallanzani, in 1775, uses hermetically sealed glass flasks
and gels opposite results, 282. The discovery of oiygen raises
another question; Does prolonged heat change its vitalizing prop-
erties? 284. Experiments of Schwann and Schulze, 1836-37,
284. The question of the spontaneous origin of microscopic life
regarded as disproved, 386. III. Pouchet reopens the question
in 1858, maintaining that he finds microscopic life produced in
sterilized and hermetically seated solutions. 2S6. The question
put (o rest by (he brilliant researches of Pasteur and of Tyndall,
288, 381). Description of Tyndall's apparatus and his use of op-
tically pure air, itjo. Weismann's theorclica! speculations re-
garding the origin of biophors, 2172. The germ-theory of disease,
*<>3~304- The idea of conlagium vivum revived in 1840, 153.
Work of Bassi, 194. Demonstration, in 1877, of the actual con-
nection between anthrax and splenic fever, 21)4. Veneration of
Pasleur, 294. His personal qualities, 496. Filial devotion, 397.
Steps in his intellectual development, iq8. His investigation of
diseases of wine (1868), 295. Of the silk-worm plague {1865-68),
399. His studies on the cause and prevention of disease con-
stitute his chief service lo humanity, 399. Establishment of the
Pasleur Institute in Paris, age). Hecent developments, 300.
Robert Koch; his senices in diKovering many bacteria of dis-
ease, 300. Sir Joseph Lister and antiseptic surgery, 30a. Bac-
teria in their relation to agriculiurc, soil inoculation, etc., 303.
Knowledge of bacteria as relalc<l to (he growth of general biol-
ogy, 304.
CHAPTER XIV
Heheditv and Ceruis-al Continuity —Mendel. Gai.ton. Weis-
MANN, 3
The hereditary substance and the ly-arcrs of heredity, 305. The
nature of inheritance, 305. Darwin's theory of pangenesis, 306.
The theory of pangens replaced by that of germinal continuity,
307, Exposition of the theory of germinal continuity, 30S. The
law of cell -succession, 309. Otiiiis ceUula c cdluta, 309. The
continuity of hereditary substance, 309. Early writers, 310.
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Webmaiui, 310. Gcnii'Cells and body cells, 310. The hered-
itnry substance is thv germ -plasm, 311. Il embodies all the past
history of protoplasm, 311. The more precise invesdgalion oi
the material basis of inheritance, 311. The nucleus of cells, 311
The chromosomes, 31s. The fertilized ovum, the staning-poini
of new organisms, 313. BehiLviuruf the nucleus during diiision,
3 1 J. The miitureot parental qualities in the chromosomes, 313.
Prclocalized areas in the proto[>lasni iif the egg. 314. The i
heritance of acquired characteristics, 314. The application
statistical methods and exptrimtnts 10 the study of heredity, 31
Mendel's important discovery of alternative inheritance, 316.
Francis Gallon, 317. Carl Pearson, 318. Experiments 1
heritance, 318.
CHAPTKR XV
The SctF.NCE or Fossil Life, 32c
Extinct fonna of life, 320. Strange views regarding fossils, 330.
Freaks of nature, 31X. Mystical explanations, 321. Large bones
supposed Co be those of giants, 322. Determination of the nature
of fossils by Steno, 322. Fossil de[>osits ascribed to the P'lood, 323.
Mosaic deluge regarded as of universal extent, 324. The com-
parison of fossil and living animals nf great importance, 315.
Cuvier the founder of vertebrate palromtologj', 33;. Lamartic
(bunds invertebrate paleeontology, 326. Lamarck's conception of
the meaning cf fossils more scientific than Cuvier's, 327. The
arrangement of fossils jn strata, 328. William Smith, 328. Sum-
mary of the growth of the science of fossil life, 33g, Fossil re-
mains as an index to the past history of the earth, 330. Epoch-
making work ot Charles I.yell, 330. ElTeet of the doctrine of
organic evolution on [wilffiiintology, 3.1?. Richard Owen's
studies on fossil animals, 331. Agassi/ and the parallelism be-
tween fossil forms of life and stages in the de^'elupment of
animals, 334, Huxley's geological work. 335. Leidy, 337. Cope,
337. Marsh, 338. Carl Zittel's writings and influence, 338.
Henry F. Osborn, 339. Method of collecting fossils, 340. Fossil
remains of man, 340. Discoveries in the FayOm district of
Africa, 341.
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The DocTRi.vi; of Orc.anic Faoi.ution
CHAPTER X\l
What Kvoumos Is: The Evidence upon which it Rests, etc., . 3
Great v.-igueness regarding the meaning of evolution, 346. Causes fur
this, 346. The confusion of Darttinism with organic evolulion,
347. The idea that the doctrine is losing ground, 347. Scientific
controversies on evolution relate to ihc factors, not to the fact, of
evolution, 347. Nature of the question: not metaphysical, not
theological, but historical, 348. The historical method applied
tothestudyof animal life, 349. The diversity of living forms, 349.
Arc species filed in nature? 350. Wide variation among an-
imals, 3io. Evolutionarj- series: The shells of Slavonia and
Steinheim, 351-353- Evolution of the horse, 3^4. The collec-
tion of fossil horses at the American Museum of Natural Hislorj',
New York, 355. The genealogy of the horse tracetl for more
than two million years, 354. Connecting fcimis: the arthasip-
leryx and pterodactyls, 358. The entliryokigical rect)rd and its
connection with evolution, 358. Cluca 10 the past hisiorj- of
animals, 358. Rudimentary organs, 361-363, Hereditary sur-
vivals in the human body, 363. Remains of the scaffolding for
its building, 364. Anliquity of man, 364, Pre-human ty]>es, 365.
Virtually three links: the Java man; the Neanderthal skull; the
early neolithic man of Engis, 364-366. Evidences of man's I'vo-
lution based on paliontolog)', embr^'ology, and archlEology, 366.
Mental evolution, 366. Sweep of the doctrine of organic evolu-
tion, 366-367.
CHAPTER XVII
Theories OF EvoLnTiON— Lamarck. D/bwin 31
le atlcmpt to indicate the active factors of evolution is ihc Murce of
(he diflcrenl theiiries, 368. The theories of Lamarck, Darn'in,
and Weismann have altracled ihe widest attention, 360. La-
marck, the man, 368-374. His education, 370. Leaves priestly
studies for the army, 370. Great braverj', 371. Physical injury
Kim to glTO up military life, 371, Por-
mpnnanl work in botany, 371. Pathetic [mvcrty
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CONTENTS
and neglect, 371. Changes from botany to zoology at the age of
fifty years, 373. Profound influence of this change in shaping
his ideas, 374. His theory of evolution, 374-380. First public
announcement in iSoo, 375. His FhilosophU Zoviogi^ue pub-
lished in 1809, 375, His two laws of evolution, 376. The first
lawcmbodies the principleof use and disuse of organs, the Second
that of heredity, 376. A simple exposition of his theory, 377.
His employment of the word besoin, 377. Lamarck's view of
heredity, 377. His belief in the inheritance of acquired char-
acters, 377. His attempt to account for variation, 377. Time
and favorable conditions the two principal means employed by
nature, 378. Salient points in Lamarck's theory, 378. His
definition of species, 379. Neo-Lamaickism, 3S0. Damin. His
Iheory rests on three sets of fads. The central feature of his
theory is natural selection. Variation, 380. Inheritance, 38a.
Those variations will be inherited that are of advantage to the
race, 383. Illustrations of the meaning of natural selection, 383-
389. The struggle for existence and its consequences, 384. Vari-
ous aspects of natural selection, 384. It does not always operate
toward increasing ihe efficiency of an organ — short-winged
beetles, 385. Color of animals, 386. Mimicry, 387. Sexual
selection, 388. Inadequacy of natural selection, 389. Darwin the
first to call attention to the inadequacy of this principle, 389.
Confusion between the theories of Lamarck and Darwin, 390.
Illustrations, 391. The Origin of Species published ia 1859, 391.
Other writings of Darwin, 391.
CHAPTER XVIII
Theories Continued — Weisman.v. De Veies 3
Weismann's views have passed through various stages of remodeling,
391. The Evolution Theorj' published in 1904 is the best es-
position of his views, 391. His theory the field for much contro-
versy. Primarily a theory of heredity, 393. Wcismann's iheory
summarized, 393. Continuity of the germ-plasm the central idea
in Weismann's theory, 394. Complexity of the gerTn-jiIasm. Il-
lustrations, 393, The origin of variations, 396. The union of
two complex germ-plasms gives rise lo variations, 396. His ex-
tendon of the principle of natural selection — germinal selection,
397. The inheritance of acquired characters, 398. Wcismann's
analysis of the subject Ihe !iesl, 398. Illustrations, 399. The
question still open to e^ipcrimcntal observation, 399. Weis-
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CONTENTS XM
mann's personality, 400. Quotation from his autobiography, 401.
The mutation theory of De Vrics, 401. An important contribu-
tion. His application of experimcnls commendable, 403. The
mutation theory not a substitute for that of natural si^lection, 404.
Tendency toward a reconciliation of apparently conflicting views,
404. Summary of the salient features of the theories of Lamarck,
of Darwin, of Weismann, and De Vrics, 405. Causes for bewil-
derment in the popular mind regarding the different forms of the
evolution theory, 406.
CHAPTER XIX
The Rise of Evolutiovaby Thought, 40J
Opinion before Lamarck, 407. \'iews of certain Fathers of the
Church, 408. St. Augustine, 409. St. Thomas Aquinas, 409.
The rise of the doctrine of special creation, 410. Suarcz, 410.
ERect of John Milton's writings, 411. Forerunners of Lamarck:
Buflon, Erasmus Darwin, Ccielhe, 4ir. Statement of Buffon's
views on evolution, 412. Erasmus Darwin the greatest of La-
marck's predecessors, 413. His writings, 414. Palsy's Natural
Theology directed against them, 414. Goethe's connection with
evolutionary thought, 414. Causes tor the neglect of Lamarck's
theoretical writings, 411;. The temporary disappearance of the
doctrine of organic evolution, 415. Cuvicr's op]X)sition, 415.
The debate between Cuvier and St. Hilaire, 415- Its effect, 417.
Influence of Lyell's Principles of Geology, 418. Herbert Spen-
cer's analysis in 1851, 419. Darwin and Wallace, 430. Circum-
alances under which their work was laid before the Linnaian
Society of I-ondon, 420. The Idler ot transmission signed by
Lyell and Hooker, 410-411. The jjcrsonalitv of Darwin, 413.
Appearance, 423. His charm of manner, 423. Affectionate
consideration at home, 424. Unexampled induslr;' and con-
scientiousness in the face of ill health, 424, 426. His early
life and education, 415. \'oy.igc of the BeagU, 435. The re-
sults of his five years' voyage, 426. Life at Downs, 416,
Parallelism in the thought of Danrin and Wallace, 427.
Darwin's accotmt of how he arrived at the conception of natural
selection, 417. Wallace's narrative, 42S. The Da ruin -Wallace
theory launched in 1858, 427. Darwin's hexik on The Origin of
Species regarded by him as merely an outline. 419. The spread
of the doctrine of organic evolulirm, 420. Husltyone of its great
popular exponents, 430. Haeckel, 43 c. After Darwin, the prob-
lem was to explain phenomena, 433.
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CHAPTER XX
5 Prospect. Present Tendencies in Biolocv, . j
Hirilogical though! ^ihows conlinuity of dci-clopmenl. 4J4. Character
of the [imgn-ss — a crusade against superstition, 434. The first
triumph of the scientific method was the overthrow of authority,
435. The three stages of progress — descriptive, mmparative, eit-
pcrimenta], 435. The notable books of hiologj' and their authors,
435-437. Kecent tendencies in biologj" higher standards, 43;;
improvement in the tools of science, 438; ad\-ancc in mcthoils,
43q; cxjierimcnlal work, 431; the gnwing interest in the study
of processes, 440; ex]>crimtnls applied lo heredity and ev-olulion,
lo fertilization of the egg. and to animal 1>ehavior, 440, 441. Some
tendencies in anatomical .studies, 443. Cell-lincagc, 441. New
work on the nervous s\*sleni, 443. The application of biological
facts to the benefit of mankind, 443. Technical biology*, 44J.
Soil inoculation, 444. Kdaiiun of insects to the transmission of
diseases, 444. The frxni i)f fishes, 444, The establishment and
mainlenanie of biological LilBiratories, 444. The station at
N'apli-s, 444. Other stations, 446. The eslablishmenland main-
tenance of technical [leriodicals, 446. Explorations c)f frssil
records, 447. The n-conslnictive influence of bi-ilogical ])rog-
ress, 448-
READIXr, LIST, 4
I. General References, 449-4Sr. 11. Special Kefcnnces, 451-460.
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ILLUSTRATIONS
I. Aristotle, 384-51? b.c
J. PL1.VY. J3-79 A.D.,
3. Galeji, 131-200
4. Vesalius, 1514-1565
5. Anatomical Sketch from Vpsaliuh' Fabrica (1543),
6. The Skeleton fhom \'esalius' Fabricis, .
7. IS'iTiAL Letters tkou the Fabrka, ....
8. Fallopius. 1523-1563,
<). Fabhicius, Harvev's Teacheh, i537-i6i<(,
10. WiLLi.vu Harvey, i578-i6j;7,
(■543)
12. Hooke's Microscope (1665)
13. Malpighi, 1618-1654,
14. Fkou MalPiqhi's Anatomy nj Ibe Silh.-orm (1669), .
15. SWAMMKBDAM. 1637-1680,
16. Fkom Sivahmerdau's Bihih N.ilur',
17. -A.vatomv or AN Insect Dissf.ctedanuDraw.v bySwax
i8. Leevwenhoek, 1631-1713,
I'). Leeuhenhoeks Microscope,
joii. Leeuh'exhoek's Mechanisupor Examining ti
OF THE Blood, 83
2ab. The Capillary Circvlation, after Leeuwenmokk, . . 84
31. Plant Cells from Leeuwenhoek's Arcami Xalura, . . 86
22. Lyonet, i707-i78g, 90
23. Larva of the Willow Moth, prom Lionet's Monograph
(-750), 9'
14. Muscles of the Larva op the Willow Moth, from Lyonbt's
monoosaph 93
25. Central Nervoos System and .serves of the Same Animal, 93
36. Dissection of the Head of ihe Lar\a of the Willow Moth, 94
17. The Bhain AND Head Nerves of the Same Animal, , . . 95
28. ROESEL VON ROSENHOF, 1705-1759, ... . . 97
29. RfAL'MUR, 16S3-I757, .... 98
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XXIV ILLUSTRATIONS
30. Nervous System op the Cockchafer, from Stsaus-DOrck-
HEiu's Monograph (1838) loi
ji. Ehkenberg. 1795-1876, 108
3a. Gesner, 1516-1565, 114
33. John Ray, 1618-1705, :i6
34. LiNN^.us AT Sixty (1707-1778) 114
35. Karl Th. von Siebold 135
36. Rudolph Leuckart 136
37. Severinus. 1580-1656, 14)
38. Camper, 1732-1789, 144
35. John Hunter, 1718-1793 145
40. VicQ d'Azvr, 1748-1794 147
41. CuviEH AS A Young Man, 1769-1819, 151
41. CUVIEH AT THE ZeNITH OF HiS PoWEB I53
43. H. Milne-Edwards, 1800-1885, '57
44. Lacaze-Duthiers, 1831-1901, 159
45. Lorenzo Oken, 1779-1851, 160
46. Richard Owen, 1S04-1893, r6i
47. J. Fr. Meckel, 1781-1833, - 163
48. Karl Gegenbaub, 1836-1903 164
49. Bichat, 1771-1801 169
50. Von Koellikeb, 1817-1905 173
51. Rudolph Vihchow, 1831-1903, 174
53. Franz Levdig, 1821-1908 (April), '75
53. S. Ramon v Cajal, 176
54. Ai.brecht Haller, 1708-1777 183
55. Charles Bell, 1774-1843, 184
56. Johannes MCller, 1801-1858, 187
57. LuDwic, 1816-1N95 188
58. Du Bois-Revmond, 1818-1896 189
59. Claude Bernard, 1813-1878, 191
60. P'kONTlSPiECE OF Harvev's Generalion€ Animalium (1651), . 301
61. Selected Sketches frou Malpighi's Works, . . .103
63. Marceli.o Malpiciii, 162N-1694. 304
6.1- Plate from H'olff"s Tbeoria Ctneralhnis (1759). . - 309
64. Charles Bonnet, 1710-1793 113
65. Karl Rrnst von Baer, 1793-1876, ii6
66. VriN Baer at about Seventy Years of Age .■17
67. Sketches from Von Baer's Kmdrvolocical Treatise (iSiS), 331
68. A. KowAi.EvsKY, 1840-190 335
ti). Francis M. B.vlpouh, iS|;i-i883. . ... .-37
70. <Kkar Hehth-ic; in iS->o, .,,.... '^t
7.. Uir.irEJ.M His, 18,51-1904 --.y
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ILLUSTRATIONS
7a. The Earliest Known Picture of Cells, from Hooke's Micro-
graphia (1665) 1
73. Sketch from Malpigui's Treatise on the Anatomy of Plants
(■670) 2
74. Theodob Schwann, i8io-i88j, i
75. M. ScHLEiDEN, 1804-1S81, I
76. The Ecc and Earlv Stages in Its Developvent (after Ce.
77. An Early Stage in the Development of the Egg of a Rock
LiupET (after Conklli), a
78. Highly MAGNinED Tissije-Cells from the Skin of a Sala-
mander (after Wilson), i
79. DlAGRAIIOFTHECi^IEFSTZPSlNCELL-DH^SI0s(A^^EHPAltKER), 2
So. Diagram of a Cell (modified after Wilson), . . .2
Si. (A) Rotation OF Protoplasm IN Cells OF NiTELLA. (B) High-
ly Magnified Cells of a Tradescantia Plant, Showing
Circulation of Protoplasm (after Sedgwick and Wilson), 2
82. FiLIX DUJARDIN, 180I-1860, 1
83. PURKISJE, 1787-1869, 1
84. Carl Nag ELI, 1S17-1891 i
85. Hugo von Mohl, 1805-1872 2
86. Ferdinand Cohn, 1828-1898, 1
87. Heinrich Anton De Barv, 1831-1888 1
S8. Max Schwltze, 1825-1874, 2
8q, Francesco Redi, 1626-1697 2
90. Laz^aro Spallaniam, 1719-1799, 2
91. Apparatus of Tyndall for Experimenting on Spontaneoiw
92. Xavis Pasteur (1822-1895) *-'"* His Granddaughter, , . i
93. Robert Koch, born 1843, 3
94. Sir Joseph Lister, born 1817 3
95. Gregor Mendel, 1821-1884 3
96. Francis Gaiton, born i8zi, 3
97. Charles Lvell, 1797-1S75 3
98. Professor Owen and the Extlnct Fossil Bird of New Zea-
i«*i> 3
99. Louis Agassiz, 1807-1873 3
100. E. D. Cope, 1840-1897, 3
101. O. C. Marsh, 1831-1899, . 1
103. Karl von Ztttei, 1839-1904, j
103. Transmutations of Paludina (after ^JEusIAVERl, . . 1
104. Planorbis Shells from Steinheim (after Hvatt), . ,3
105. Bones of the Foreleg of a Horse, i
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XXVI ILLUSTRATIONS
io6. Bones of Fossii, Ancestors of the Hosse. .... 357
107. REPHESF.JiTATION OF THE ANCESTOR OF TUE HORSE DrAWN BY
Chahles K. Knight usdek the Dibectios of Professor
OSBORS. PERUISSIOS or THE AUEHICA^ MvSEUU OF NATURAL
IIlSTORV 359
. Fossil Reuains of a PurMiTivE Bird (Ahcii^opteryx), . . 360
[Oq. GlLL-CLEPTS OF A SHARK COUPARED WITH THOSE OF THE Ell-
BRVONic Chick anti Rabbit, 361
. JAWSOF AN ?;MBRVOMC\VHALE,SHOW*IN(; RimiUESTARvTEETH, 36*
. Profile Reconstructions of the Skulls of Living and of
KossiL Men, 365
. Lauahck, t744-i8n), 373
[13. Charlfls Darwis, 1R0Q-1882 381
. i707-r;8«, .
s Darwis, 1731-1802.
riv Saint Hilairk, 1771
. Frnst IIaeckkj., b
113. The BioLotJicAL S
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PART 1
THE SOURCES OF BIOLOGICAL
IDEAS EXCEPT THOSE OF
ORGANIC EVOLUTION
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PART I
THE SOURCES OF BIOLOGICAL
IDEAS EXCEPT THOSE OF
ORGANIC EVOLUTION
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CHAPTER I
A.V OUTLINE OF THE RISE OF BIOLOGY AND OF
THE EPOCHS IN ITS HISTORY
•■Truth il the Daughter of Time."
The ninelcenlh century will be for all time memorable
for the great extension of the knowledge of organic nature.
It was then that the results of the earlier efTorts of mankind
lo interpret the mysteries of nature began to be fruitful;
observers of organic nature began to see more deeply into
the province of life, and, above all, began to sec how lo direct
their future studies. It was in that century' that the use of
the microscope made known the similarity in cellular con-
struction of all organized beings; that the substance, proto-
plasm, began to be recognized as the physical basis of life
and the seat of all vital activities; then, most contagious
diseases were traced to microscopic oi^nisms, and as a con-
sequence, medicine and surger\' were reformed; then the
belief in the spontaneous origin of life under present condi-
tions was given up; and it was in that century that the
doctrine of oi^nic evolution gained general acceptance.
These and other advances less generally known created an
atmosphere in which biology — the great life-science — grew
rapidly.
In the same period also the remains of ancient life, long
since extinct, and for countless ages embedded in the rocks,
were brought to light, and their investigation assisted mate-
rially in understanding the living forms and in tracing their
genealogy.
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" nvj::raL" '.< ■ in-' mcir-.' diictTnint outuniUs^
.■■■■■iTi--T L'viuJ "< iniiuoir; im rrend of
,1:: ■.:■:■- :.;-j: vniz: a^ii, i)tt.T. s( alien jirt-
>,'^-:-, .. ^'.r.ici roTiviciior.. lim: all tht
..-. ■.i:~rv:. rrczi: aimijicr one? hy l piadual
.-nc— .■?- i: !-:oioir- 111', nineiecnth rtiirurv'
■■ •:r..'^:- ...v.-jnrv- u imyiic? aric; chcrc-
:: ■.— , -.:: '-.ri- : "r!H>r Tftim: viih incrsir.ic
:. -,■: ■■!i»UHr- ii. ai. imim;.u ivl\.
:.;.■: :..: ■. :'i.i.'. ii al anir.-jiL- ;;ii:' ;>tii:-
., :- : :■■■-:,■. -Jiv.T'.i:!!. ;.tk'.. :ir l rorj*-
1', :. :■,:: :"-s;'-„!ii r;i'-'mi:::'y ii: ordtT
r. 'V: -, -"■.■-■■ .1 .i-r.-ni; chtinLstr} ir. la'.e
:: .-.'..-. :■-.■■>. -z- li:t: onM n^vt Ifvini;
■ . : .. -.T.-. >■ '.:v.T--. ii;.--. uri^adi been
• ■• ,- ^ ■ , ■-— :■ iTT.-.'!-. ?. ('-!::.r.ic com-
- ■ r .i:..- i.r :hi risdi of
■'. ..;■ ..T!-. -.::\ :o->n.>Ii:iie5
- _". ■.■.-. L'Jwrlng. It
-.- • ..-i.._r :":iii? have
'.*. b.'.'.'j^-' . ". ' ■ -■ " : :'rt :rjn>forma-
• J -_-.-" -~> ;> an inter-
-■...■.■.... ■ . vii'TiEtni. Thi.
■_".. Thb i> one
' -■ -. -■- ,■ ■ ■:■,■ -..ci- all quesiions
■ :.' - .-,■ ■■;-■- ..- ', manifestations,
,..,.,,•-, -Tx- :r-.. ■■■.■ iLVilopment, and
•:;' •,!■.'■■ -.'.-rr.'. a- ■vvll ;:- '.n :ht'ir physiol-
r,'.!'.;-'., (i i- n'j--v of ccmman'iing impor-
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OUTLINE OF BIOLOGICAL PROGRESS 5
lance in the world of science, and it is coming more and more
to be recognized ihat it occupies a field of compelling in-
terest not only for medical men and scholars, but for all
intelligent people. The discoveries and conquests of biology
have wrought such a revolution in thought that Ihey should
be known to all persons of liberal culture. In addition to
making acquaintance with the discoveries, one ought to Icam
something about the history of biology; for it is essential
to know how it took its rise, in order to understand its
present position and the nature of its influence upon expand-
ing ideas regarding the world in which we live.
In its modem sense, biology did not arise until about
i860, when the nature of protoplasm was first clearly pointed
out by Max Schultze, but the currents that united to form it
had long been flowing, and we can never understand the
subject without going back to its iatric condition, when what
is now biology was in the germ and united with mi'dicine.
lis separation from medicine, and its rise as an independent
subject, was owing to the steady growth of that zest for ex-
ploration into unknown fields which began with the new
birth of science in the sixteenth centun% and has continued
in fuller measure to the present. It was the outcome of
applying observation and experiment to the winning of new
truths.
Difficulties. — But biology is so comprehensive a field,
and involves so many details, that it is fair to inquire: can
its progress be made clear to the reader who is unacquainted
with it as a laboratorj' study ? The matter will be simplified.,
by two general observations — first, that the growth of biolog\-
is owing to concurrent progress in three fields of research,
concemi'd, respectively, with the structure or architecture of
living beings, their development, and their physiologj-. We
recognize also a parallel advance in the systematic classifica-
tion of animals and plants, and we note, furthermore, that
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& BIOLOGY AND ITS MAKERS
the idea of evolution permeates the whole. Il will be neces-
sary to consider the advances in these fields separately, and
to indicate the union of the resuhs into the main channel of
progress. Secondly, in attempting to trace the growih of ideas
in this department of learning one sees that there has been
a continuity of development. The growth of these notions
has not been that of a chaotic assemblage of ideas, but a
well-connected storj' in which the new is built upon the old
in orderly succession. The old ideas have not been com-
pletely superseded by the new, but they have been molded
into new forms to keep pace with the advance of investigation.
In its early phases, the growth of biology was slow and dis-
cursive, but from the time of Linna;us to Darwin, although
the details were greatly multiplied, there has been a relatively
simple and orderly progress.
Facts and Ideas. — There are many books about biology,
with direclions for Iaboralor\* obscr\*ation and experiment,
and also many of the leading facts of the science have been
given to the public, but an account of the growth of the ideas,
which are interpretations of the facts, has been rarely at-
tempted. From the books refcrrc-d to, it is almost impossible
to get an idra of biolog)' as a unit; this even the students in
our universities acc|uire only through a coherent presentation
of the subject in the classroom, on the basis of Iheir work in
the laborator}'. The critical training in the laboratory is
most im[)ortant, but, after all, it is only a part, although an
essential part, of a knowledge of biology. In general, too
little attention is paid to interpretations ami the drill is con-
finctl to a few facts. Xow, the facts are related to the ideas
of the science as statistics to hislorj- — meaningless without
interpretation. In the rise of biolog)- the facts have accu-
mulated constantly, through obsenalion and experiment, but
the genera! truths have emerged slowly and periodically,
whenever there has been grante<l to some mind an insight
;dbyGOOglC
OUTLINE OF BIOLOGICAL PROGRESS 7
into the meaning of the facts. The detached facts are some-
times tedious, the interpretations always interesting.
The growth of the knowledge of organic nature is a long
story, full of human interest. Nature has been always the
same, but the capacity of man as its interpreter has varied.
He has had to pass through other forms of intellectual activ-
ity, and gradually to conquer other phases of natural phe-
nomena, before entering upon that most difficult task of
investigating the manifestations of life. It will be readily
understood, therefore, that biology was delayed in its devel-
opment until after considerable progress had been made in
other sciences.
It is an old saying that "Truth isthedaughterof Time,"
and no better illustration of it can be given than the long
upward stru^Ie to establish even the elemental truths of
nature. It took centuries to arrive at the conception of the
uniformity of nature, and to reach any of those generaliza-
tions which are vaguely spoken of as the laws of nature.
The Hen of Science. — In the progress of science there is
an army of obseners and experimenters each contributing
his share, but the rank and file supply mainly isolated facts,
while the ideas take birth in the minds of a few gifted leaders,
either endowed with unusual insight, or so favored by cir-
cumstances that they reach general conclusions of importance.
These advance-guards of intellectual conquest we designate
as founders. What were they hke in appearance? Under
what conditions did they work, and what was their chief aim ?
These are interesting questions which will receive attention
as our narrative proceeds.
A study of the lives of the founders shows that the scien-
tific mood is pre-eminently one of sincerity. The men who
have added to the growth of science were animated by an
unselfish devotion to truth, and their lasting influence has
been in lat^e measure a reflection of their individual char-
ed byGoOglc
8 BIOLOGY AND ITS MAKERS
acters. Only those have produced permanent results who
have interrogated nature in tJie spirit of devotion to truth
and waited imtienlly for her replies. The work founded on
sitirish motives and lanil)' has sooner or later fallen by the
wayside, \Vc can recognize now that the work of scientific
investigation, subjected to so much hostile criticism as it
appeared from lime to time, was undertaken in a reverent
spirit, and was not iconoclastic, but remodelling in its in-
fluence. Some of the glories of our race are exhibited in
ihe lives of the pioneers in scientific progress, in their struggles
to establish some great truth and to maintain intt-Uectual
inlcgrity.
The nam.es of some of the men of biolog)', such as Harvey,
Linna'us, Cuvier, Danvin, Huxley, and Pasteur, arc widely
known because Ihcir work came before Ihe people, but others
equally deserv^inR of fame on account of Iheir contributions
to scientific progress will require an introduction to most of
our readers.
In recounting Ihe stor)- of the rise of biology, we shall
have occasion to make tlie ac(|uaintance of this goodly com-
[Kiny. Itefore beginning the narrative in detail, however,
we shall lcx)k summarily at some general features of scientific
progress and at the e]:ncli> <it biology.
The Conditions i\iit-R which Sciexct, Developed
In a brief sketch of biology there is relatively little in the
ancieni world that ^e<juire^ notice e.\ce]il the work of Aris-
loile and (ialen: but with the advent of \'e.-ia!ius, in 154,1,
our interest begins 10 freshen, and. iherrafier, llirough lean
times and fat times there is always something 10 command
our attention.
The early aindition^ mils! be de:i(t with in order to appre-
ciate what followiti. We are to reiolUri that in the ancient
;dbyGOOglC
OUTLINE OF BIOLOGICAL PROGRESS 9
world there was no science of biology as such; nevertheless,
ihc germ of it was contained in the medicine and the natural
history- of those times.
There is one matter upon which we should be clear: in
the time of Aristotle nature was studied by obsenation and
experiment, Thb is the foundation of all scientific ad-
vancement. Had conditions remained unchanged, there is
reason to believe that science would have de\'elopcd steadily
on the basis of the Greek foundation, but circumstances, to
be spoken of later, arose which led not only to the complete
arrest of inquiry, but also, the mind of man being turned
away from nature, to the decay of science.
Aristotle the Founder of Hatural History. — The Greeks
represented the fullest measure of culture in the ancient
world, and, naturally, we find among them the best -developed
science. All the knowledge of natural phenomena centered
in Aristotle (384-322 b.c.), and for twenty cenluries he
represented the highest level which that kind of knowledge
had allained.
It is uncertain how long it took the ancient observers to
lift science to the level which it had at the beginning of
Aristotle's period, but it is obvious thai he must have had
a long line of predecessors, who had accumulated facts of
obscr\-ation and had molded them into a system before he
perfected and developed that system. We arc reminded
that all things are relative when we lind .Aristotle referring
to the ancients; and well he might, for we have indubitable
evidence that much of the scientific work of antiquity has
been lost. One of the most striking discoveries pointing
in that direction is the now famous papyrus which was found
by fleorg Ebers in Egj-pt about i860. The recent trans-
lation of this ancient document shows that it was a treatise
on medicine, dating from the I'lflccnth century b.c. At this
time the science of medicine hud attaine<l an astonishingly
;dbyGOOglC
lo BIOLOGY AND ITS MAKERS
high grade of development among that people. And since
it is safe to assume that the formulation of a system of med-
icine in the early days of mankind required centuries of
obser\'ation and practice, it becomes apparent that the
manuscript in queslion was no vague, first attempt at rediK-
ing medicine to a system. It is built upon much scientific
knowledge, and must have been preceded by writings both
on medicine and on its allied sciences.
It is not necessary that we should attempt to picture the
crude beginnings of the observation of animated nature and
the dawning of ideas relalive to animals and plants; it is
suitable to our purpose to commence with Aristotle, and to
designate him, in a relative sense, as the founder of natural
history.
That he was altogether dissatisfied with the state c^
knowledge in his time and that he had high ideals of the
dignity of science is evidenced in his writings. Although he
refers to the views of the ancients, he regarded himself in
a sense as a pioneer. " I found no basis prepared," he says,
" no models to copy. , . . Mine is the first step, and there-
fore a small one, though worked out with much thought
and hard labor. It must be looked at as a first step and
judged with indulgence." (From Osbom's From ihe Greeks
to Darwin.)
There is general agreement that Aristotle was a man of
\'asl intellect and that he was one of the greatest philosophers
of the ancient world. He has had his detractors as well as
his partisan adherents. Perhaps the just estimate of his
attainments and his position in the history of science is
between the enthusiastic appreciation of Cuvier and the
critical estimate of Lewes.
This great man was bom in Stagira in the year 384 B.C.,
and lived until 322 B.C. He is to be remembered as the
most distinguished pupil of Plato, and as the instructor of
;dbyGOOglC
OUTLINE OF BIOLOGICAL PROGRESS "
Alexander the Great. Like other scholars of his time, he
covered a wide range of subjects; we have mentioD, indeed,
of about three hundred works of his composition, many of
which are lost. He wrote on philosophy, metaphysics, psy-
chology, politics, rhetoric, etc., but it was in the domain of
natural history that he attained absolute pre-eminence.
His Positioa in the Development of Science. — It is mani-
festly unjust to measure Aristotle by present standards; wc
must keep always in mind that he was a pioneer, and that
he lived in an early day of science, when errors andcrudities
were to be expected. His greatest claim to eminence in the
historj- of science is that he conceived the things of importance
and that he adopted the right method in tr>'ing to advance
the knowledge of the natural universe. In his program
of studies he says : " First we must understand the phenomena
of animals; then assign their causes; and, finally, speak of
their generation." His position in natural historj' is fre-
quently misunderstood. One of the most recent writers on
the history of science, Henry Smith Williams, pictures him
entirely as a great classifier, and as the founder of systematic
zoology. While it is true that he was (he founder of sys-
tematic zoology, as such he did not do his greatest scnice
to natural history, nor docs the disposition to classify repre-
sent his dominant activity. In all his work classification is
made incidental and subsenient to more important considera-
tions. His obser\'ations ujion structure and development,
and his anticipation of the idea of organic evolution, are the
ones upon which his great fame rests. He is not to be remem-
bered as a man of the type of Linnieus; rather is he the fore-
runner of those men who looked deeper than Linnaeus into
the structure and development of animal lift — the mor-
phologists.
Particular mention of his classification of animals will
be foimd in the chapter on Linnaus, while in what follows
;dbyGOOglC
12 BIOLOGY AND ITS MAKERS
in this chapter attention will be confined to his observation
of their structure and development and to the general in-
fluence of his work.
His great strength was in a philosophical treatment of
the structure and development of animals. Professor Osbom
in his interesting book. From llie Greeks to Dam-in, shows
that Aristotle had thought out the essential features of
evolution as a process in nature. He believed in a complete
gradation from the lowest organisms to the highest, and that
man is (he highest point of one long and continuous ascent.
His Extensive Knowledge of Animals. — He made exten-
sive studies of life histories. He knew that dnme bees
develop without previous fertilization of the eggs (by par-
thenogenesis); thai in (he squid the yolk sac of the embr)-o
is carried in front of the mouth; that some sharks develop
within the egg-lube of the mother, and in some species have
a rudimentary blood -connection resembling the placenta of
mammals. He had followed day by day the changes in the
chick within the hen's egg, and obser\'ed the development of
many other animals. In cmbr)'ologv' also, be antici|}ated
Harvey in appreciating the true nature of development as
a process of giadual building, and not as the mere expansion
of a prc\'iously formed germ. This doctrine, v.-hich is known
under the name of cpigenesis, was, as we shall see later,
hotly contested in the eighteenth centurj-, and has a modified
application al IJie present lime.
In reference to the structure of animals he had described
the tissues, and in a rude way analyzed the organs into their
comjxjneni jiarls. It is known, furthermore, that he prepared
plates of anatomical l'it;ures, but, unfortunately, these have
been lost.
In estimating the contributions of ancient writers to
science, it must be remembered ihat we have hut fragments
of their works to examine. It is, moreover, doubtful whether
;dbyGOOglC
OUTLINE UF BIOLOGICAL PROGRESS "3
the sciemific writings ascribed lo Aristotle were all from his
hand. The work is so uneven that Huxley has si-ggcsted
that, since the ancient philosophers taught vivn voce, what
wc have of his zoological writings may possibly be the notes
of some of his students. While this is not known to be the
case, that hypothesis enables us lo understand the inlimaic
mixture of profound obser\ation with trivial matter and
obvious errors thai occur in the writings ascribed to him.
Hertwig says: "It is a mailer for great regret that there
have been preserved only parts of his three most important
zo&logical works, ' Hisloriti atiiiiwiium,' ' Dc parlihus,' and
' De generolione,' works in which zoology is founded as a
universal science, since anatomy and embryology, physiolog}-
and classification, find equal consideration,"
Some Errors. — Dissections were liiile practised in his
day, and it must be admitted that his observations embrace
many errors. He supposed the brain to be bloodless, the
arteries lo carry air, etc., but he has been cleared by Huxley
of the mistake so often altributed lo him of supposing the
heart of mammals to have only ihree chambers. It is alto-
gether probable that he is crwlited with a larger number of
errors than is justified by ihe facts.
He must have had unusual gifis in the exposition of these
technical subjects; indeed, he made his researches appear
so important lo his royal palron, Alexander, ihat he was
aided in the prejiaration of his great Natural History by a
grant of 800 talents (equivalent lo ?2oo,ooo) and by nu-
merous assistants and collectors. Thus in ancient times was
anticipatcfi the question thai is being agitated to-day— that
of the support and the endowment of rc-scarch.
Personal Appearance. — Some idea of his looks may be
gained from Fig. i. This is a copy of a bas-relief found in
the collection of P'ulvius Ursinus (d. 1600), and was originally
published by J, Fabcr. Its authenticity as a [xjrtrait is
;dbyGOOglC
14 BIOLOGY AND ITS MAKERS
attested (iSii) by Visconti, who says that it has a perfect
resemblance to the head of a small bust upon the base of
which the name of Aristotle is engraved. Portrait busts and
statues of Aristotle were common in ancient times. The
picture of him most familiar to general readers is the copy
of the head and shoulders of an ancient statue representing
him with a draping over the left shoulder. This is an
384-3"
attractive portrait, showing a face of strong intellectuality.
Its aulhenticily, however, is not as well established as that
of the picture shown here. Other pictures, believed to be
those of Aristoile, represent him later in life with receding
hair, anil one exists in which his baldness is very extensive.
He was described as short in stature, with s])indling legs and
smalt, penetrating eye-s, and to have been, in his younger
<luys, vain and showv in his dress.
;dbyGOOglC
OUTLINE OF BIOLOGICAL PROGRESS ^5
He was early left an orphan with a considerable fortune;
and there are stories of early excesses after coming into his
property. Thc-se charges, however, lack trustworthy support,
and are usually regarded as due mainly to that under-
mining gossip which follows one holding prominent place
and enviable recognition. His habits seem to have been
those of a diligent student v.'ith a zest in his work; he was an
omnivorous reader, and Plato called him ihe mind of his
school. His large private librarj' and his manner of liv-
ing bespeak the consenting of his property, rather than its
waste in selfish indulgences.
His Influence.— The influence of Aristotle was in the
right direction. He made a direct appeal to nature for his
facts, and founded his Natural Histor>- only on obser\ation
of the structure, physiolog)', and development of animals.
Unfortunately, the same cannot be said of his successors.
Galen, who is mentioned above in connection with Aris-
totle, was a medical writer and the greatest anatomist of
antiquity. On account of the relation of his work to the
growth of anatomy, however, the consideration of it is re-
served for the chapter on Vesalius.
Soon after the period of Arislotle the center of scientiTic
investigation was (ransferred to Alexandria, where Ptolemy
had erected a great museum and founded a large public
libran,'. Here mathematics and geography flourished, but
natural histor\- was little cultivated.
In order to find the next famous naturalist of antiquity,
it is necessary to look to Rome. Rome, although great in
political power, never became a true culture center, char-
acterized by originality. .All that remains of their thought
shows us that the Roman people were not creative. In the
capital of the empire, the center of its life, there arose no
great scientific investigator.
Pliny. — The situation is represented by Pliny the Elder
;dbyGOOglC
i6 BIOLOGY AND ITS MAKERS
(23-79 A.D.), the Roman general ami litterateur (Fig, 2).
His v.orks on natural history, filling tliirty-scvcn volumes,
have been prcscn-ed with greater completeness than those trf
other ancient writers. Their overwhelming bulk seems to
have ]jrotlucei) an impression upon those who, in ihe nine-
teenth centur)-, heralded him as the greatest naturalist of
-Pl-INV,
i,l-79 I
anli(|uily. Rut an examination of his writings shows that
lie did nothing to deipen or broaden the knowledge of nature,
and hisNaturalHistorymarksii distinct retrograde movement.
He was, at best, merely a compiler — "a collector of anec-
(lotLs" — who, forsaking observation, indiscriminately mixed
fable, farl, and fancy taken from the writings of others.
He emphasized tlie feature of classiticalion which Aristotle
had held in proper subordinalion, and he replaced Ihe clas-
;dbyGOOglC
OUTLINE OF BIOLOGICAL PROGRESS i?
sification of Aristotle, founded on plan of organization, by a
highly artificial one, founded on the incidental circumstance
of the abodes of aninials — cither in air, water, or on ihr earth.
The Arrest of Inquiry and its Effects. — Thus, natural
history, transferred from a Greek to a Roman center, was
already on the decline in the time of Pliny; but it was dc-s-
tined to sink still lower. It is an old, oft-repeated slorj' how,
with the overthrow of ancient civilization, the torch of learn-
ing was nearly extinguished. Not only was there a complete
political revolution; there was also a complete change in the
menial interests of mankind. The situation is so complex
that it is diflicult to state it with clearness. So far as science
is concerned, its extinction was due to a turning away from
the external world, and a complete arrest of inquiry into the
phenomena of nature. This was an important part of that
somber change which came over all mental life.
One of the causes that played a considerable part in the
cessation of scientific investigation was the rise of the Chris-
tian church and thedominanceof the priesthood in all intellec-
tual as well as in spiritual life. The world-shunning spirit,
so scrupulously cultivated by the early Christians, prompted
a spirit which was hostile to observation. The behest to
shun the world was acted upon too literally. The eyes were
closed to nature and the mind was directed toward spiritual
matters, which truly seemed of higher importance. Pres-
ently, the obser\-ation of nature came to be looked upon as
proceeding from a prying and impious curiosity.
Books were now scarcer than during the classical period ;
the schools of philosophy were reduced, and the dissemina-
tion of learning ceaswl. The priests who had access lo the
books assumed direction of iniellcctual life. But they were
largely employed with the analysis of the supernatural,
without the wholesome check of observation and expcrimenl ;
mystical explanations were invented for natural phenomena.
;dbyGOOglC
iS BIOLOGY AND ITS MAKERS
wh3e metaph)-sical speculatiofl became the dominant fonn
of mental aniriiy.
Aiittiority Oedaied the Sonice erf Knowledge. — In this
atmosphere controversies over trivial points were engendered,
and the ancient writings were quoted as sustaining one side
or the other. AH this led to the referring of questions as to
their truth or error to authority as the source of knowledge,
and resulted in a complete eclipse of reason. Amusing illus-
trations of the situation are abundant; as when, in the
Middle .Ages, the question of the number of teeth in the horse
vns debatal with great heat in many contentious nTitings.
.'\pparently none of the contestants thought of the simfde
expedient of counting them, but tried only to sustain their
position by reference to authority. Again, one who noticed
spots on the sun became convinced of the error of his eyes
because Aristotle had somewhere written "The faceof the
sun is immaculate."
This was a barren period not only for science, but also
for ecclesiastical advance. Notwithstanding the fact that
for more than a thousand years the only new works were
written by professional theologians, there was no substantial
advance in their field, and we cannot escape the reflection
thai ihe reciprocal action of free inquiry is essential to the
growth of theologj- as of other departments of learning.
In [he period from the downfall of Rome to the revival
of learning, one eminent theologian, St. Augustine, stands
in rdicf for the openness of his mind to new truth and for
his expressions upon ihc relation of revelation in the Scrip-
tures to the obseiration of nature. His position will be more
clearly indicated in the chapter dialing with the rise of
evolutionary thought.
Perhaps it has been the disposition of historians lo paint
the Middle Ages in too dark colors in order to provide a
backgroun<l on which fitly to portray the subsequent awak-
ed byGoOglc
OUTLINE OF BIOLOGICAL PROGRESS 1?
ening. It was a remolding period through which it was
necessan' to pass after ihe overthrow of ancient civilization
and the mixture of the less advanced people of the North with
those of the South. The opportunities for advance were
greatly circumscribed ; the scarcity of books and the lack of
facilities for travel prevented any general dissemination of
learning, while the irresponsible method of the time, of
appealing to authority on all questions, threw a barrier across
the stream of progress. Intellectuality was not, however,
entirely crushed during the prevalence of these conditions.
The medie^-al philosophers were masters of the metaphysical
method of argument, and their mentality was by no means
dull. While some branches of learning might make a little
advance, the study of nature suffered the most, for the knowl-
edge of natural phenomena necessitates a mind turned
outward in direct observation of the phenomena of the
natural and physical universe.
Renewal of Observation. — It was an epoch of great im-
portance, therefore, when men began again to observe, and
to attempt, even in an unskilful way, hampered by intellec-
tual inheritance and habit, to unravel the mysteries of nature
and to trace the relation between causes and effects in the
imiverse. This new movement was a revolt of the intellect
against existing conditions. In it were locked up all the
benefits that have accrued from the development of modem
science. Just as the decline had been due to many causes,
so also the general revival was complex. The invention of
printing, the voyages of mariners, the rise of universities,
and the circulation of ideas consequent upon the Crusades,
all helped to disseminate the intellectual ferment. These
generic influences aided in molding the environment, but,
just as the pause in science had been due to the turning away
from nature and to new mental interests, so the revival was
a return to nature and to the method of science. The pio-
;dbyGOOglC
ao BIOLOGY AND ITS MAKERS
necrs had to be men of determined independence ; they labored
against self-interest as well as opposition from the church
and the prieslhood, and they withstood the terrors of the
Inquisition and the loss of recognition and support.
In this uncongenial atmosphere men like Galileo, Des-
cartc-s, and Vesaliiis established the new movement and over-
threw [lie reign of authority. With the coming of Vesalius
the new era of biological progress was opened, but its growth
was a slow one; a growth of which we are now to be con-
cerned in tracing the main features.
The Epochs in Biological History
It will be helpful to outline the great epochs of biological
progress before taking them up for fuller consideration.
The foundation of progress was the renewal of obscr\'ation
in which, as already slated, all modem science was locked up.
It was an epoch in biological historj' when Vesalius over-
threw the authority of Galen, and studied at first hand the
organization of the human body.
It was an epoch when William Han'cy, by adding experi-
ment to observation, demonstrated the circulation of the
blood and created a new physiology. The two coordinate
branches of biology were thus early outlined.
The introduction of the microscope, mainly through the
labors of Grew, Hooke, Malpighi, and Leeuwenhoek, opened
a new world to the investigator, and the work of these men
marks an e|K)ch in ihe progress of independent inquiry.
Linna-us, by intralucing short descriptions and uniform
names for animals and ]>lants, greatly advanced the subject
of natural history,
Cuvier, by founding the school of comjiarative anatomy,
so furthcrcfi the knowledge of the organization of animals
tliat he create*! an ('[)och.
;dbyGOOglC
OUTLINE OF BIOLOGICAL PROGRESS 21
Bichat, his great conicmporarj', created another by laying
the foundation of our knowledge of the structure of animal
tissues.
\on Bacr, by his studies of the development of animal
life, supplied what was lacking in the work of Cuvier and
Bichal and originated modem embryology,
Hallcr, in the eighteenth, and Johannes Muller in the
nineteenth century, so added to the ground work of Harvey
thai i)liysiolog>' was made an independent subject and was
established on modem lines.
With BuRon, Erasmus Darwin, and Lamarck began an
epoch in evolutionary thought which had its culminating
point in the work of Charles Danvin.
.\fter Cuvier and Bichat came the establishing of the
cell-theorj-, which created an epoch and influenced all
further progress.
Finally, through the discovery of protoplasm and the
recognition that il is the scat of all vital activity, arrivcxi the
epoch which brought us to the threshold of the biology of
the present day.
Step by step naturalists have been led from the obvious
and superficial facts about living oi^anisms to the deep-
lying basis of all vital manifestations.
;dbyGOOglC
CHAPTER II
VESALIUS AND THE OVERTHROW OF AUTHORITY
IN SCIENCE
Vesalil'S, although an anatomist, is to be recognized in a
broad sense as one of the founders of biology. When one
is attempting to investigate animal and plant life, not only
must he become acquainted with the external appearance of
living organisms, but also must acquire early a knowledge
of their structure, without which other fads relating to their
lives can not be disclosed. Anatomy, which is the science
of the structure of organized beings, is therefore so funda-
mental that we find ourselves involved in tracing the history
of its rise as one part of the story of biology. But it is not
enough (o know how animals and plants arc constructed;
we must also know something about the purpose of the
structures and of the life that courses through them, and,
accordingly, after considering the rise of analomy, we must
lake a similar view of its counterpart, physiology.
The great importance of Vcsalius in the history of science
lies in the fact that he overthrew adherence to authority as
the mciliod of ascertaining trulh, and substituted therefor
obscn'ation and reason. Several of his forerunners had
tried to accomplish the same end, but they had failed. He
was indebted to them as every man is indebted to his fore-
bears, but at thesameiimewecannot fail to see that Vesalius
was worthy of the victory. He was more resolute and force-
ful than any of his predecessors. He was one of those rare
;dbyGOOglC
OVERTHROW OF AUTHORITY IN SCIENCE ^3
spirits who see new truth with clearness, and have the bravery
to force their thoughts on an unsympathetic public.
The Begiimmg of Anatomy.^ — In order lo appreciate his
ser\ice it is necessary to give a brief account of his predeces-
sors, and of the condilion of anatomy in his time. Remem-
bering ihat anatomy embraces a knowledge of the architec-
ture of all animals and plants, wc can, nevertheless, see why
in early times it should have had more narrow boundaries.
The medical men were the first lo take an interest in the
structure of the human body, because a knowledge of it is
necessary for medicine and sui^erj'. It thus happens that
the earliest observations in anatomy were directed toward
making known the structure of the human body and Ihat of
animals somewhat closely related to man in point of struc-
ture. Anatomical studies, therefore, began with the more
complex animals instead of the simpler ones, and, later,
when comparative anatomy began to be studied, this led to
many misunderstandings; since the struclure of man became
the type to which all others were referred, while, on account
of his derivation, his structure presents the greatest modifi-
cation of the vertebrate type.
It was so difficult in the early days to get an opportunity
to study the human body that the pioneer anatomists were
obliged to gain their knowledge by dissections of animals, as
the di^, and occasionally the monkey. In this way Aristotle
and his forerunners learned much about anatomy. About
300 B.C., the dissection of the human body was legalized in
the Alexandrian school, the bodies of condemned criminals
being devoted to that purpose. But this did not become
general even for medical practitioners, and anatomy contin-
ued to be studied mainly from brute animals. .
Galen. — The anatomist of antiquity who outshines aj]
others was Galen (Claudius Galcnus, 130-200 a.d.), who lived
some time in Pergamos, and for five years in Rome, during
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«4 BIOLOGY AND ITS MAKERS
the second century of the Christian era. He was a man of
much talent, both as an observer and as a writer. His de-
scriptions were clear and forceful, and for twelve centuries
his works exerted the greatest influence of those of all scien-
tific writers. In his writings was gathered all the anatomical
knowledge of his predecessors, to which he had added ob-
servations of his own. He was a man of originality, but not
having the human body for dissection, he erred in expounding
its structure "on the faith of obsen-ations made on lower
animals." He used the right method in arriving at his facts.
Huxley says: "No one can rrad Galen's works without bein^
impressed with the marvelous extent and diversity of his
knowledge, and by his clear grasp of those experimental
methods by which alone physiology can be advanced."
Anatomy in the Middle Ages. — But now we shall see how
the arrest of inquiry already spoken of oi>erated in the field
of anatomy. The condition of anatomy in the Middle Ages
was the condition of all science in the same period. From
its practical iniiX)rtance anatomy had to be taught to medical
men, while physics and chemistry, biology and comparative
anatomy remained in an undeveloped state. The Way ill
which this science was taught is a feaUire which charSclcrizes
the intellectual life of the Middle Ages. Instead of having
anatomy taught by observations, the writings of Galen were
expounded from the desk, frequently without demonstrations
of any kind. Thus his work came to be set up as the one'
unfailing authority on anatomical knowledge. This was in
accord with the dominant ecclesiastical influence of the time.
Reference to authority was the method of ihc thcologftins,
and by analopy it became the method of all learning. As
the Scriptures were accepted as the unfailing guide to spir-
itnal truth, so Galen and other ancient writers were made
the guides to scientific truth an<l thought. T^e baneful
effects of this in stifling inquir)' and in reducing knowledge
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26 BIOLOGY AND ITS MAKERS
to parrot-like repetition of ancient formulas are so obvious
that they need not be especially dwelt upoiu
Predecessors of Vesalius. — Italy gave birth to the first
anatomists who led a revolt against this slav'eiy to authority
in scientific matters. Of the eminent anatomists who pre-
ceded Vesalius it will be necessaiy to mention only three.
Mundinus, or Mondino, professor at the University of
Bologna, who, in the early part of the fourteenth century,
dissected three bodies, published in 1315 a work founded
upon human dissection. He was a man of originality whose
work created a sensation in the medical world, but did not
supersede Galen's, His influence, although exerted in the
right direction, was not successful in establishing observation
as the method of teaching anatomy. His book, however,
was sometimes used as an introduction to Galen's writings
or in conjunction with them.
The next man who requires notice is Berengarius of Carpi,
who was a professor in the University of Bologna in the eariy
part of the sixteenth century. He is said to have dissected
not less than one hundred human bodies; and although his
opportunities for practical study were greater than those of
Mondino, his attempts to place the science of anatomy upon
a higher level were also unsuccessful.
We pass now from Italy to France, where Sylvius (1478-
1555), one of the teachers of Vesalius, made his mark. His
name is preserved to-day in the fssure oj Sylvius in the brain,
but he was not an original investigator, and he succeeded
only in " making a reputation to which his researches do not
entitle him," He was a selfish, avaricious man whose adop-
tion of anatomy was not due to scientific interest, but to a
love of gain. At the age of fifty he forsook the teaching of
the classics for the money lo be made by teaching anatomy.
He was a blind admirer of Galen, and read his works to
medical students without dissections, except that from time
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OVERTHROW OF AUTHORITY IN SCIENCE 27
to time dogs were brought into the amphitheater and their
structure exposed by unskilled barbers.
Vesalius. — Vesalius now came upon the scene; and
through his efforts, before he was thirty years of age, the idol
of authority had been shattered, and, mainly through his
persistence, the method of so great moment to future ages
had been established. He was well fitted to do battle against
tradition — strong in body, in mind, and in purpose, gifted
and forceful; and, furthermore, his work was marked by
concentration and by the high moral quality of fidelity to
truth.
Vesalius was bom in Brussels on the last day of the year
1514, of an ancestry of physicians and learned men, from
whom he inherited his leaning toward scientific pursuits.
Early in life he exhibited a passion for anatomy ; he dissected
birds, rabbits, dogs, and other animals. Although having
a strong bent in this direction, he was not a man of single
talent. He was schooled in all the learning of his time,
and his earliest publication was a translation from the Greek
of the ninth book of Rhazes. .A.ftcr his early training at
Brussels and at the University of Louvain, in 1533, at the
age of 18, he went to Paris to study medicine, where, in
anatomy, he came under Sylvius and Gunthcr.
His Force and Independence. — His impetuous nature was
shown in the amphitheatre of Sylvius, where, at the third
lecture, he pushed aside the clumsy surgeon barbers, and
himself exposed the parts as they should be. He could not
be satisfied with the exposition of the printed page; he must
see with his own eyes, must grasp through his own expe-
rience the facts of anatomical structure. This demand of
his nature shows not only how im|>atient he was with
sham, but also how much more he was in touch with reality
than were the men of his time.
After three years at the French capital, owing lo wars
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26 BIOLOGY AND ITS MAKERS
in Belgium, he went back to Louvain without obtaining his
medical degree. After a short experience as surgeon on the
field of battle, he went to Padua, whither he was attracted
by reports of the opportunities for practical dissection that
he so much desired to undertake. There his talents were
recognized, and just after receiving his degree of Doctor of
Medicine in 1537, he was given a post in surgery, with the
care of anatomy, in the university.
His Reform of the Teaching of Anatomy. — The sympa-
thetic and graphic description of this period of his career by
Sir Michael Foster is so good that I can not refrain from
quoting it: "He at once began to teach anatomy in his own
new way. Not to unskilled, ignorant barbers would he en-
trust the task of laying bare before the students the secrets of
the human frame; his own hand, and his own hand alone,
was cunning enough to track out the pattern of the structures
which day by day were becoming more clear to him. Fol-
lowing venerated customs, he began his academic labors by
'reading' Galen, as others had done before him, using his
dissections to illustrate what Galen had said. But, time after
lime, the body on the table said something different from
that which Galen had written.
"He tried to do what others had done before him — he
tried to believe Galen rather than his own eyes, but his eyes
were too strong for him; and in the end he cast Galen and
his writings to the winds, and taught only what he himself
had seen and what he could make his students sec, too.
Thus he brought into anatomy the new spirit of the time,
and the men of the time, the young men of the lime, answered
the new voice. Students llocked to his lectures; his hearers
amounted, ii is said, to some five hundred, and an enlightened
senate rccogni.-^wl his worth by repeatedly raising his emol-
uments.
"Five years he thus spent in untiring labors at Padua.
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Fio. 4.— Vesalius, 1514-1564.
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3° BIOLOGY AND ITS MAKERS
Five years he wrought, not weaving a web of fancied thought,
but patiently disentangling the pattern of the texture of
the human body, trusting to the words of no master, ad-
mitting nothing but that which he himself had seen ; and at
the end of the five years, in 1542, while he was as ycl not
twenty-eight years of age, he was able to write the dedi-
cation to Charles V of a folio work enlillcd the 'Structure of
the Human Body,' adorned with many plates and woodcuts
which appeared at Basel in the following year, 1543."
His Physiognomy. — This classic with the Latin title,
De Humani Corporis Fabrica, requires some special notice;
but first let us have a portrait of Vesalius, the master. Fig. 4
shows a reproduction of the portrait with which his work
is provided. He is represented in academic costume, prob-
ably that which he wore at lectures, in the act of demonstrat-
ing the muscles of the arm. The picture is reduced, and in
the reduction loses something of the force of the original.
U'c sec a strong, independent, self-willed countenance; what
his features lack in refinement they make up in force; not
an artistic or poclic face, but the face of the man of action
with scholarly training.
His Great Book. — The book of Vesalius Iai<l the founda-
tion of modem biological science. It is more than a land-
mark in the progress of science — it created an epoch. It is
not only interesting historically, but on account of the highly
artistic [>latcs with which it is illustrated it is interesting to
examine by one not an anatomist. For executing the plates
Vesidius securefl tlie sen'ice of a fellow-countrj'man, John
Stephen deCalcar, who was one of the most gifted pupils of
Titian. The drawings are of such hi^h artistic quality that
for a long time they were ascribed to Titian. The artist has
attemplixl to soften tlic necessarily prosaic nature of anatom-
ical ill I! si rat ions liy introducing an artistic Iwickground of
hndscape of varied features, with bridgi-s, roads, streams,
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3* BIOLOGY AND ITS MAKERS
buildings, etc. The employment of a background even in
port rail -painting was not uncommon in the same century,
as in Leonardo da Vinci's well-known Mona Lisa, with its
suggestive perspective of water, rocks, etc.
Fig. 5 will give an idea on a small scale of one of the plales
illustrating the work of Vesalius. The plates in tht original
are of folio size, and represent a colossal figure in the fore-
ground, with a background showing between ihi'limbs and
at the sides of the' figure. There is considerable variety as
rej/ards the background, no two plates being alike.
Also, in delineating the skeleton, the artist has given to
it an artistic pos^, as is shoixTi in Fig, 6, but nevertheless the
bones are well ilrawn. No plates of equal merit had ap-
peared before these; in fad, they arc the earliest generally
known drawings in an^lomy, although woodcuts represent-
ing anatorifical figures were published as early as 1401 by
John Kttham. Ketham's figures showed only externals
and preparations for opening the body, but rude woodcuts
representing internal anatomy and the human skeleton had
been published notably by Magnus Hundt, 1501; Phryscn,
1518; and Berengarius, 1521 and 1533. Leonardo da \'inci
and olher artists had also executed anatomical drawings
before the time of Vesalius.
Previous lo the publication of the complete work, Vesalius,
in 1538, had published six tables of anatomy, and, in 1555,
he brought out a new edition of the Fabrka, with slight
additions, especially in reference to physiologj', which will be
adverlcd lo in the chapter on Harvey.
In ihe original edition of 1543 the illustrations are not
colleclcd in ihc form of plates, bul are distributed through
the text, the larger ones making full-fiage (folio) illustrations.
In this edition also the chapters are introduced with an initial
letter showing curious anatomical figures in miniature, some
of which are shown in Fig. 7.
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34
BIOLOGY AND ITS MAKERS
The Fabrica of V'esalius was a piece of careful, honest
work, the moral influence of which must nol be overlooked.
At any momtni in the world's history, work marked by
sincerity exercises a wholesome
influence, but at this particular
stage of intellectual develop-
ment such work was an inno-
vation, and its significance for
progress was wider and deeper
than it might have been under
different circumstances.
Opposition to Vesalius. —
The beneficent results of his
efforts were to unfold after-
ward, since, at the time, his
utterances were vigorously op-
posed from all sides. Not only
did the ecclesiastics contend
that he was disseminating false
and harmful docirine, but the
medical men from whom he
might have expected sympathy
and support violently opposed
his teachings.
Many amusing arguments
were brought forward to dis-
credit Vesalius, and lo up-
hold the authority of Galen.
Vesalius showed that in the
human body the lower jaw is
a sins;lc bone — that it is not
dividnl as it is in the dog and
other UnvLT m;immals, and, as
iiijris4j. fialen had taught, also in the
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OVERTHROW OF AUTHORITY IN SCIENCE 35
human subjects. He showed that the sternum, or breast
bone, has three parts instead of eight; he showed that the
thigh bones are straight and not curved, as they are in the dog.
Sylvius, his old teacher, was one of his bitterest opponents;
he declared that the human body had undergone changes in
structure since the time of Galen, and, with the object of de-
fending the ancient anatomist, " he asserted that the straight
thigh bones, which, as every one saw, were not curved in
accordance with the leaching of Galen, were the result of
the narrow trousers of his contemporaries, and that they
must have been curved in their natural condition, when un-
interfcred with by art ! "
The theologians also found other points for contention.
It was a widely accepted dogma that man should have one
less rib on one side, because from the Scriptural account
Eve was formed from one of Adam's ribs. This, of course,
\'esalius did not find to be the case. It was also generally
believed at this time that there was in the body an indestruc-
tible resurrection -bone which formed the nucleus of the
resurrect ion -body. Vesalius said that he would leave the
question of the existence of such a bone to be decided by the
theologians, as it did not appear to him to be an anatomical
question.
The Court Phyucian. — The hand of the church was heavy
upon him, and the hatred shown in attacks from various
quarters threw Vesalius into a state of despondency and
anger. In this frame of mind he destroyed manuscripts upon
which he had expended much labor. His disappointment
in the reception of his work probably had much to do in
deciding him to relinquish his professorship and accept the
post of court physician to Charles V of the United Kingdoms
of Spain and Belgium. After the death of Charles, he
remained with Philip II, who succeeded to the throne. Here
he waxed rich and famous, but he was always under sus-
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3^ BIOLOGY AND ITS MAKERS
picion by the clerical powers, who from time to time found
means of discrediting him. The circumstances of his leaving
Spain are not definitely known. One account has it that he
made a posl-mortem examination of a body which showed
signs of life during the operation, and that he was required
to undertake a pilgrimage to the Holy Land to clear his soul
of sacrilege. Whether or not this was the reason is uncertain,
but after nineteen years at the Spanish Court he left, in 1563,
and journeyed to Jerusalem. On his return from Palestine
he suffered shipwreck and diet! from the effects of exposure
on Zanti, one of the Ionian Islands. It is also said that
while on this pilgrimage he had been offered the position of
professor of anatomy as successor to Fallopius, who had
died in 1563, and that, had he lived, he would have come
back honorably to his old post.
Eustachius and Fallopius. — The work of two of his con-
temporaries, Eustachius and Fallopius, requires notice.
Cuvier says in his Hisloire des Sciences Naturelles that those
three men were the founders of modem anatomy. Vcsalius
was a greater man than either of the other two, and his
influence was more far-reaching. He reformed the entire
field of anatomy, while the names of Eustachius and Fallopius
are connected especially with a smaller part of the field.
Eustachius described Ihe Eustachian tube of the ear and gave
especial attention to sense organs; Fallopius made special
investigations upon the viscera, and described the Fallopian
tube.
Fallopius was a suave, polite man, who became professor
of anatomy at Padua; he opposed Vcsalius, but his attacks
were couched in respectful lerms.
Eustachius, the professor of anatomy at Rome, was <rf a'
different type, a harsh, violent man, who assailed Vesalius
with virulence. He corrcclwl some mistakes of Vesalius,
and prepared new plates on anatomy, which, however, were
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OVERTHROW OF AUTHORITY IS SCIENCE
37
nol published until 1754, and iherefore did not exert the in-
fluence upon anatomical studies that those of Vcsaliusdid.
The Especial Service of Vesalius. — Ti should be remem-
bered that both these men had the advantage of the sketches
made under the direction of Vesalius. Pioneers and path-
breakers are under special limitations of being in a new
Icrritory, and make more errors than ihey would in following
|--r,. s -Fali.opjl's, .i23-'S63.
another's survey of ihc same territory; it lakes much less
creative force to correct the enx)rs of a first sun^cy than
lo make the original discoveries. Ever}'lhing considered,
Vesalius is deserving of the position assigned to him. He
was great in a larger sense, and it was his researches in
particular which re-established scientific method and made
further progress possible. His errors were corrected, not by
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3** BIOLOGY AND ITS MAKERS
an appeal to aulhority, but by the method which he founded.
His great claim to renown is, not that his work outshone all
other work (that of Galen in particular) in accuracy and
brilliancy, but that he overthrew dependence on authority
and re-estabhshed the scientific method of ascertaining truth.
It was the method of Aristotle and Galen given anew to the
world.
The spirit of progress was now released from bondage,
but we have-still a long way to go under its guidance to reach
the gateway of modem biol<^.
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CHAPTER III
WILLIAM HARVEY AND EXPERLMENTAL OBSERVA-
TION
After the splendid observations of Vesalius, revealing in
a new light the construction of the human body Har\ey took
the next general step by introducing experiment to determine
the use or purpose of the structures that Vesalius had so
clearly exposed. Thus the work of Harvey was complemcntal
to that of Vesalius, and we may safely say (hat, taken together,
the work of these two men laid the foundations of the modem
method of investigating nature. The results they obtained,
and the influence of their method, arc of especial interest to us
in the present connection, inasmuch as lliey stand at the
beginning of biological science after the Renaissance. Al-
though the obsen-alions of both were applied mainly to the
human body, they ser\-ed to open the entire field of structural
studies and of experimental obsen^ations on living organisms.
Many of the experiments of Ha n'ey, notably those relating
to the movements of the heart, were, of course, conducted
upon the lower animals, as the frog, the dog, etc. His ex-
periments on the living human body consisted mainly in
applying ligatures lo the arms and the legs. Xevertheless,
the results of all his cxpcrimenls related to the phenomena of
the circulation in the human body, and were primarily for
the use of medical men.
In whal sense the observaiions of the two men were com-
plemcntal will be better understood when wc remember that
there arc two aspects in which living organisms should
always be considered in biological studies; first, the struc-
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40 BIOLOGY AND ITS MAKERS
ture, and, then, the use that the structures subserve. One
view is essential to the other, and no investigation of animals
and plants is complete in which the two ideas are not in-
volved. Just as a knowledge of the construction of a ma-
chine is necessary to understand its action, so the anatomical
analysis of an organ must precede a knowledge of its office.
The term " physiological anatomy of an organ," so commonly
used in text-books on physiology, illustrates the point. \Vc
can not appreciate the work of such an organ as the liver
without a knowledge of the arrangement of its working units.
The work of the anatomist concerns the statics of the body,
that of the physiologist the dynamics; properly combined,
they give a complete picture of the living organism.
It is to be remembered that the obser\ations of Vesalius
were not confined exclusively to structure; lie made some
experiments and some comments on the use of parts of the
body, but his work was mainly structural, while that which
distinguishes Han'ey's research is inductions founded on
experimental observation of the action of living tissues.
The service of Vesalius and Har\-ey in opening the j>ath
to biological advance is very conspicuous, but they were not
the only pioneers; their work was a part of the general revival
of science in which Galileo, Descartes, and others had their
part. While the birth of the experimental method was not
due to the exertions of Harvey alone, nevertheless it shouhl
stand 10 his credit thai he established that method in bio-
logical lines, .-^risiolle and Galen both had cmjiloyed ex-
perimenls in their researchL-s, and Han-ey's step was in the
nature (if a revival of ihe method of the old Greeks,
Harvey's Education.— Ha r\ey was filti'd both by native
talent and by his training for the part which he played in the
intelk'clual awakeni.ig. He was bom at Folkestone, on the
south coast of England, in 1578, the son of a prosperous
yeoman. The Har\ey family was well esteemed, and the
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HARVEY AND EXPERIMENTAL OBSERVATION 4i
father of William was at one time the mayor of Folkestone.
Young Ifaney, after five years in the King's school at Canter-
bury, went to Cambridge, ami in 1593, at the age of sixteen,
entered Caius College, He had already shown a fondness
for obser\-ations upon tlie organization of animals, but it is
unlikely that he was able to cultivate (his at ihe university.
There his studies consisted mainly of Latin and Greek, with
some training in debate and elementary instruction in the
science of physics.
At Padua. — In 1 597, at the age of nineteen, he was grad-
uated with the Arts degree, and the following year he turned
his steps toward Italy in search of the best medical instruc-
tion that could be found at that time in all the world. He
selected Ihe grcal university of Padua as his place of sojourn,
being attracted thither by the fame of some of its medical
teachers. He was particularly fortunate in receiving his
instruction in anatomy and physiology from Fabricius, one
of the most learned and highly honored leachers in Italy,
The fame of ihis master of medicine, who, from his birth-
place, is usually given the full name of Fabricius ab Aqua-
pendente, had spread to the intellectual centers of the world,
where his work as anatomist and- surgeon was especially
recognized. A fast friendship sprang up between the young
medical student and this ripe anatomist, Ihe influence of which
must havebeenvcrv' great in shaping thef uture work of Han'ey,
Fabricius was already sixly-one years of age, and when
Han-ey came to Padua was perfecting his knowledge upon
the valves of the veins. The young student was taken fully
into his confidence, and here was laid that first familiarity
with the circulatorv' system, the knowledge of which Han*cy
was destined so much lo advance and amplify. But it was
the stimulus of his master's friendship, rather than what he
taught about the circulation, that was of assistance to Harvey.
For the views of F"ahricius in reference lo the circulation were
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42 BIOLOGY AND ITS MAKERS
those of Galen; and his conception of the use of the valves
of the ^'eins was entirely wrong, A portrait of this great
teacher of Harvey is shown in Fig, 9.
At Padua young Harvey altractcd notice as a student of
originality and force, and seems to have been a favorite with
the student body as well as with his teachers. His f)osition
in the university may be inferred from the fact that he be-
longed to one of the aristocratic-student organizations, and,
further, that he was designated a " councilor " for England.
The practice of having student councilors was then in vogue
in Padua; the students comprising the council met for
deliberations, and very largely managed the university by
their votes upon instructors and university measures,
It is a favorable comment upon the professional education
of his time that, after graduating at the University of Cam-
bridge, he studied four or more years (Willis says five years)
in scientific and medical lines to reach the degree of Doctor
of Physic.
On leaving Padua, in 1602, he returned to England and
took ihe e.xaminations for the degree of M.D. from Cam-
bridge, inasmuch as the medical degree from an English
university advanced his ]»rospects of receiving a position at
home. He opened practice, was married in 1604, and the
same year began to give public lectures on anatomy.
His Personal Qualities. — Harvey had marker! individual-
ity, and seems to have produce*! a [wwerful impression upon
those with whom he came in contact as one jxjssessing
unusual intellectual ]X)wers and independence of character.
He inspiriil conrnk'nce in people, and it is significant that,
in reference lo the circulation nf ihc blood, he won to his way
of thinl:ing hin associates in the medical profession. This is
imj)ortant testimony as to his ]>ersnnal force, since his ideas
were o|)]>osed to the bc'li<*{ of the time, ;ind since also away
from home they were vigorously assaiki!.
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Fic, 9.— Fabricius, 1537-L619. Uarvkv's Teacher,
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44 BIOLOGY AXD ITS MAKERS
Although described as choleric and hasly, he had also
winning qualities, so that he retained warm friendships
throughout his life, and was at all times held in high rcsjiect.
S7N'i6(.7-
It miisl be said also thai in his rt'i>Iit.'s to his critics, he showed
great moderalion.
The conlcmplative face of Han-ey is shown in Fig. lo.
This is taken from his [)ic1urc in the National Porlrait
Gallery in I.omlon, and is usually regarded as the second-
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HARVEY AND EXPERIMENTAL OBSERVATION 45
best portrait of Harvey, since the one painted by Jansen,
now in possession of the Royal College of Physicians, is
believed to be the best one extant. The picture reproduced
here shows a countenance of composed intellectual strength,
with a suggestion, in the forehead and outline of (he face, of
some of the portraits of Shakespeare.
An idea of his personal appearance may be had from the
description of Aubrey, who sa j-s : " Harvey was not tall, but of
the lowest stature; round faced, with a complexion lilic the
wainscot; his eyes small, round, very black, and full of spirit;
his hair black as a raven, but quite white twenty yc-ars before
he died; rapid in his utterance, choleric, given to gesture,"
etc.
He was less impetuous than V'csalius, who had published
his work at twenty-eight; Hairey had demonstrated his ideas
of the circulation in public anatomies and lectures for twelve
years before publishing them, and when his great classic on
the Movement of the Heart and Blood first appeared in 1628,
he was already fifty years of age. This is a good example for
young investigators of to-day who, in order to secure priority
of announcement, so frequently rush into print with imperfect
observations as prcliminarj' communications.
Harvey's Writings. — Hanej's publications were all -ircM ;
in embryology, as in physiologj^, he produced a memorable
treatise. But his publications do not fully represent his
activity as an investigator; it is known that through the
fortunes of war, while connected with the sovereign Charles I
as court physician, he lost manuscripts and drawings u]X)n
the comparative anatomy and development of insects and
other animals. His position in embryolog}' will be deah
with in the chapter on the Development of .Animals, and he
will come up for consideration again in the chapter on the
Rise of Physiology. Here we are concerned chiefly with his
general influence on the development of biology.
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46 BIOLOGY AND ITS MAKERS
His Great Classic on Hovement of the Heart and Blood,
— Since his book on the circulation of the blood is regarded
as one of the greatest monuments along the highroad of biol-
ogy, it is time to make mention of it in particular. Although
relatively small, it has a long title out of proportion to its
size: Exercilalio Analomka de Molii Cordis el Sanguinis in
Animalibtis, which maybe freely translated, " An Anatomical
Disquisition on the Movement of Ihc Heart and Blood in
Animals." The book is usually spoken of under ihe shorter
title, De Molu Cordis el Sanguinis. The full title seems some-
what repellent, but the contents of the book will prove lo be
interesting to general readers. Il is a clear, logical demon-
stration of the subject, proceeding with directness from one
point lo another until the culminating force of the argument
grows complete and con\'incing.
The book in its first edition was a quarto volume of
seventy-eight pages, published in Frankfort in 1628, An
interesting facsimile reprint of this work, translated into
English, was privately reproduced in 1894 by Dr. Morcton
and published in Cantcrburj-. .\s slated above, it is known
ihat Harvey had presented and demonstrated his views in
his lectures since 1616. In his book he showed for the first
time ever in print, that all the blood in the body moves in a
circuit, and that the beating of the heart supplies the propel-
ling force. Both ideas were new, and in order lo appreciate
in what sense they were original with Har\'ey, we must
inquire into the views of his forerunners.
Question as to Harvey's Originality. — The question of
how near some of his predecessors came to antici]>ating his
demonslmiion of the circulation has been much debated.
It has been often mainlaini-d that Scrvctus and Realdus
Columbus held the conception of the circulation for which
Harvey has become so celebrated. Of the various accounts
of the \iewi; of Harvey's predc'cessors, those of Willis, Huxley,
;dbyGOOglC
HARVEY AND EXPERIMENTAL OBSERVATION 47
and Michael Foster are amoag the most judicial; that of
Foster, indeed, inasmuch as it contains ample quotations
from the original sources, is the most nearly complete and
satisfactory. The discussion is too long to enter into fully
here, but a brief outline is necessary to understand what
he accomplished, and to put his discovery in the proper
light.
To say that he first discovered — or, more properly,
demonstrated — the circulation of the blood carries the im-
pression that he knew of the existence of capillaries connect-
ing the arteries and the veins, and had ocular proof of the
circulation through these connecting vessels. But he did not
actually see the blood moving from veins to arteries, and he
knew not of the capillaries. He understood clearly from his
observations and experiments that all the blood passes from
veins to arteries and moves in "a kind of circle"'; still, he
thought that it filters through the tissues in getting from one
kind of vessel to the other. It was reserved for Malpighi,
in 1661, and Leeuwenhoek, in 1669, to see, with the aid of
lenses, the movement of the blood through the capillaries
in the transparent parts of animal tissues- (See under
Leeuwenhoek, p. 84.)
The demonstration by Har\-ey of the movement of the
blood in a circuit was a matter of cogent reasoning, based on
experiments with ligatures, on the exposure of the heart in
animals and the analysis of its movements. It has been com-
monly maintained (as by AVhcwolI) that he deduced the cir-
culation from obser^■at!ons of the valves in the veins, but this
is not at all the case. The central jKiinl of Han'ey's reason-
ing is that the quantity of blood which leaves the left cavity
of the heart in a given space of lime makes necessary its
return to the heart, since in a half-hour (or less) the heart,
by successive pulsations, throws into the great artcn' more
than the total quantity of blood in the body. Huxley points
;dbyGOOglC
48 BIOLOGY AND ITS MAKERS
out that this is the first time that quantitative determinations
were introduced into physiologj'.
Views of His Predecessors on the Movement of the Blood.
— Galen's view of the movement of the blood was not com-
pletely replaced until the establishment of Haney's view.
The Greek anatomist thought that there was an ebb and flow
of blood within both veins and arteries throughout the
system. The left side of the heart was supposed to contain
blood vitalized by a mixture of animal spirits within the lungs.
The veins were thought to contain crude blood. He sup-
posed, further, that Uiere was a communication between the
right and the left side of the heart through ver.- minute pores
in the septum, and that some blood from the right side [tassed
through the pores into the left side and there became charged
with animal spirits. It should also he pointed out that Galen
believed in the transference of some bloo<l through the lungs
from the right to the left side of the heart, and in this fore-
shadowed the views which were later developed by Scn'ctus
and licaldus Columbus.
\'esaliu5, in the first edition of his work (1543) expressed
doubts u(>on the existence of iK>rcs in the partition -wall of
the heart through which blood could pass; and in the second
edition (1555) of the Fabrica he became more skeptical.
In taking this position he attacked a fundamental part of
the belief of Galen. The careful structural studies of \'esalius
must have le<l him ver\' near to an understanding of the con-
nection between arteries and veins. Fig. 11 shows one of
his sketches of the arrangement of aneries and veins. He
saw that the minute terminals of arteries and veins came ver\'
close together in the tissues of the body, but he did not grasj)
llic meaning of the obsenation, bi^cause his physiology was
slill that of (Jalen; \'csalius continui-d to believe that the
arteries contained blood mixed with spirits, and the veins
crude blood, and his idta of the movement was that of an
;dbyGOOglC
HARVEY AND EXPERIMENTAL OBSERVATIOX 49
ebb and flow. In reference to the anatomy of ihc blood-
vessels, he goes so far as to say of the [jortal vein and the
vena cava in the liver that " the extreme ramifications of these
veins inosculate with each other, and in many placc-s appear
I Accordinj;
to unite and be continuous." All who follmvt-d him haii ihc
advantage of his drawings showing the parallel arrangement
of arterii-s and veins, and tlieir close approach to each other
in their minute lemiinal twigs, but no one before Harve>'
;dbyGOOglC
5° BIOLOGY AND ITS MAKERS
fully grasped the idea of the movement of the blood in a
complete circuit.
Sen-etus, in his work on the Restoration of Christianily
(Reslitutio Chrisluinismi, 1553), the work for which Calvin
accomplished his burning at the slake, expressed more
clearly than Oalen had done (he idea of a circuit of blood
through the lungs. According to his view, some of the blood
took this course, while he still admits that a part may exude
through the wall of the ventricle from the right to the left
side. This, however, was embodied in a theological treatise,
and had little direct influence in bringini; about an aliered
view of the circulation. Xevertheless, there is some reason
to think that it may have been the original source of the ideas
of the anatomist Columbus, as the studies into the character
of that obser\-cr by Michael Foster seem to indicate.
Realdus Columbus, professor of anatomy at Rome, ex-
pressed a conception almost identical with that of Scr\-clus,
and as this was in an important work on anatomy, published
in 1559, and well known to the medical men of the period,
it lay in the direct line of anatomical thought and had greater
influence. Foster suggests that the devious methods of
Columbus, and his unblushing theft of intellectual property
from other sources, give ground for the suspicion that he had
appropriatcfl this idea from Sen'etus without acknowlcdg-
mcni. Although Calvin supposed that the complete edition
of a thousand copies of the work of Sen'etus had been burned
with its author in 1553, a few copies escaped, and possibly
one of these had been examined by Columbus. This as-
sumption is strengthened by llie circumstance thai Columbus
gives no record of obsen-ations, bul almost exactly repeals
the words of Seiretus.
Ca-salpinus, thi' botanist and medical man, expressed in
1571 and 1593 similar ideas of the movement of the blocxl
(jjrobably as a matter of argument, since there is no record
;dbyGOOglC
HAR\'EY AXD EXPEaTXENT.C : S?Z5LVAT: >." =1
of either ob^errstiocs or eiz<rirsf^i^ "17 "' r. . H . lis-. iij£
hold o( a still oiore iicporti:!: orcct^ci-rc rr^. ■.>^t ?.:— t :t
the blood posse from the ief: ^-fe :c ■^- z^-. :JL-:-_ri ■;?
arteries of thebody^arKi rtr.:r^i :o :J:i r>r; ?;■:■; :c :''- zzs.-.
bv the veins. But a ia;rciDCi>dtri:>:c :c trr :li:zir ;: :h:^o
men as forerunners of H2r%cv rt-jfrt^ \■j:•'J.^.'y.'r.^ :'-: ~ :heir
worksandacriticalesasiiri'.iocc: :r.e:r-o"";r::r :b,jii'i jre*i.
TTiis has been excellecJy dor.v by >Lcrj-:i F;-r::r i^ -L? i>i:-
/urf5 on /Af History o; Pk\/:-.\-:;\. F-rr.-.r >::--: i.ritiocs
of this aspect of the questior. ^oul'^ ^^v t'.y - ^ :'r- lurroies
of this book.
At most, before Har.ey. :hc c;r: .;": :"-r-: m jr. :'.-, I.:r -- rj-. i
been vaguely defxt^l by Ga'-r-. >-.— -.■.;-. C :"_—"'_-. .;- i
Ciesalpinus, and the la::irr h;ii >j; :■>.-". ^ ::■■- ■ ■: ' : :.\-i
from the heart by thearvH<-j ar. ! :.■ t::i~. : ■ i: '-.y :''.. ■.■.■ir.-:
but no one had arrivc-d at Lin :■:;-_ '■: ^ c - - '.-.-■. i;i-;.:'.,.;;or.
of all the blood through :hi- iy--.vr-.. ar. : : ".-. :■.; : _~\>:x\:
the consequences involve! in ~:.i:r. a c""C-- ■ .t.. H,;r\i-v'i
idea of the movement ol '.hi '.'.i-^r, />■ .'/ ::: C -.::• ; ;i-row;
his notion of the- circuh:;i.':; ■; S:':::r'::- ■ ,-,■- mv/: ;ir.d
his method of dcmonMr-irins; ",ht--.- v.i- n--.
Harvey's Argument. — The izi-t o; IKirvi \ V L\r;^'un'.oni- is
indicated in the follow:n-j :iro|>o>i:io:!> ^jiuiU'l v.\:h -liu'lil
modifications from Hall's Pliysioloj^y: Ii 'I'tu' hv.in |kis-
sively dilates and actively com rLirt<: dl ■ theauricK'-coiiinirt
before the vemriclcs do: (111 > ilie contraction of tlioauritlvs
forces the blood inio ihe Miitricle-;; {i\ ■ tin- iirtoriis have
no "pulsific jjowcr,'' i.e.. duy dilate p;i>sivi'ly, since ilu' piil-
salion of the arteries i; nothin.s^ vKcihan ilir ini|iiilsi- of ilu-
blood within ihcm; (V) ilu- heart is the origan of pnipuMon
of the blood; (\'l) in passiiitj from the rijjhi.veniriclc to the
left auricle the blood transudes llin)ut;li the ]);irei)ehynia of
the lungs; (\'II) the quanlity anil niteiif jiassaf-'euf ihehlooi]
peripherally from the heart makes it a j)hysiral luTessily ilijil
;dbyGOOglC
52 BIOLOGY AND ITS MAKERS
most of the hlood return to the heart; O'U^I) 'he blood does
return to the heart by way of Ihe veins. It will be noticed
that the proposition VII is the important one; in it is
in\olved the idea of applying measurement to a physiological
process,
Harvey's Influence.— Har\'ey was a \-ersatilc student.
He was a comparative anatomist as well as a physiologist
and embryologisi ; he had investigated the anatomy of about
sixty animals and the embryolog}' of insects as well as of
vertebrates, and his general influence in promoting biological
work was extensive.
His work on the movement of the blood was more than
a record of a series of careful investigations; it was a land-
mark in progress. \\'hen we reflect on the part played in
the body by Ihe blood, we readily see that a corrcci idea of
how it carries nourishment to the tissues, and how it brings
away from them the products of disintegrated protoplasm is
of prime importance in physiology. It is the jxiint from
which spring allolheridcasof the action of tissues, and until
this was known the fine analysis of vital processes could not
be made. The Iruc idea of respiration, of Ihe secretion by
glands, the chemical changes in the tissues, in fact, of all the
general activities of the body, hinge ujwn this conception.
It wa> these consequences of his demonstration, rather than
the fact thai the blood moves in a circuit, which made it so
important. This discover)' created modem physiology, and
as that branch of inquirv isoncof the |«rts of general biology,
Ihe bearing of Hanxy's discovery upon biological thought
can be reafiily surmised.
Those wlio wi^h lo examine Hancy's views at first liand,
without ilu- burden of translating them from the Latin, will
find an edition of his comjilele works translated into Kngiish
by Willis, and jiubJi-^hcfi by the Ray Society, of London.
.\s is always the case with new truths, there was hostility
;dbyGOOglC
HARVEY AND EXPERiMENTAL OBSERVATION 53
to accepting his views. In England this hostility was slight
on account of his great personal influence, but on the Conti-
nent there was man)- a sharp criticism passed upon his work.
His views were so illuminating that they were certain of
triumph, and even in his lifetime were generally accepted.
Thus the new conception of vital activities, together with his
method of inquiry-, became permanent parts of biologicat
science.
;dbyGOOglC
CHAPTfc-R IV
THE. INTRODUCTION OF THE MICROSCOPE AND
THE PROGRESS OF INDEPENDENT OBSERVATION
The introduction of the microscope greatly increasw! the
ocular powers of obser\'ers, and, in the seventeenth ccntun,*,
led to many new departures. By its use the obsenations
were carried from the plane of gross anatomy to that of
minute siruclure; the anatomy of small forms of life, like in-
sects, began lo be studied, and also the smaller microscopic
animalcula were for the first time made known.
Putting aside the disputed questions as to the time of the
invention and the identity of the inventor of the microscope —
whether to Fontana, Galileo, or the Jensscns belongs the
credit — we know that it was improved by the Hollander
Drebbel in ihe early years of the sevcntcenih century, but
was not seriously applied lo anatomical studies till after the
middle of that century.
The Pioneer Microscopists
The names especially associated with early microscopic
observations arc those of Hooke and Grew in England,
Malpighi in Italy, and Swammcrdam and Leeuwenhoek,
boih in Holland. Their microscopes were imperfect, and
were of two kinds: simjile lenses, and lenses in combination,
forming what we now know as llie compound microscope.
Some forms of these early microscopes will be described and
illusirated later. Although thus early introduced, micro-
id byGoOglc
INTRODUCTION OF THE MICROSCOPE
55
scopic obscn-alion did not produce its great results until the
nineteenth century, just after magnifying-lenses had been
greatly improved,
Robert Hookc Cift^s-i;©.^), of London, piiblishefl in 1665
a book of observations with the microscope entitled Micro-
grj^A/fl, which was embellished with eighty-three plates of
figures. Hooke was a man of fine mental endowment, who
had received a good scientific
training at the University of
Cambridge, but who lacked
fixedness of purpose in the
employment of his talents.
He (lid good work in math-
ematics, made many models
for experimenting with flying
machines, and claimed to have
di5Covered gra vital ion before
;dbyGOOglC
SG BIOLOGY AND ITS MAKERS
Newton, and also the use of a spring for regulating watches
before Huygens, etc. He gave his attention lo microscopic
study for a time and then dropped il ; yet, allhough we can not
accord (o him a prominent place in the history of biology,
he must receive mention as a pioneer worker with the micro-
scope. His book gave a powerful slimulus to microscopy in
England, and, jjartly Ihrough its influence, labor in this field
was carried on more systematically by his fellow-countryman
Nehemiah Grew.
The form of the microscope used b)- Hooke is known
through a picture and a description which he gives of it
in his MicTographia. Fig. 12 is a copy of the illustration.
His was a compound microscope consisting of a combination
of lenses altachwl to a lube, one set near the eye of the ob-
sener and the olher near the object to be examined. When
we come to describe the microscopes of I.,eeuwcnhoek, with
which so much good work was accomplish e<l, we shall see
that they stand in marked contrast, on account of their :sim-
plicity, to the somewhat elaborate instrument of Hookc.
Grew (1628- 171 1) devoted long and continuous labor to
microscopic obsen'ation, and, allhough he was less versatile
and brilliant than Hooke, his ]>atient investigations give him
just claim to a higher place in the historj' of natural science.
Grew ap]iiic-d the microscope especially lo the structure of
plants, and his books entitled Idea 0} a Philosophkal His-
tory oj PIuuls (1673) and Anatomy oj Vegetables (1682)
helpwl lo lay the foundations of vegetable histology. When
wc comi- lo consider the work of Malpighi, we shall see that
he also pro<luci-d a work upon the microscopic structure of
plants which, allhough not more f.sacl and ])ainstaking than
Crew's, showed deeper comprehension. He is the co-
founder with Grew of the science of the microscopic anatomy
of plants.
li (s not necessary to dwell long \i\mn ihe work of either
;dbyGOOglC
INTRODUCTION OF THE MICROSCOPE 57
Hooke or Grew, since that of Malpighi, Swammcrdam, and
Lceuwcnhock was more far-reaching in its influence. The
publications of these three men were so important, both in
reference to microscopic study and to the progress of inde-
pendent investigation, that it will be ncccssan- lo deal with
them in more detail. In the work of these men we come
upon the first fruits of the application of the methods intro-
duced bv Vesalius and Han'ey. (H this triumvirate, one —
Malpighi — was an Tiatian, and the other two were Holland-
ers. Their great service to intellectual progress consisted
chiefly in this — that, following upon the foundations of
Vesalius and Harvey, "they broke away from the thraldom
of mere book-learning, and relying alone upon their own
eyes and their own judgment, won for man that which had
been quite lost— the blessings of independent and unbiased
obscnation."
It is natural that, working when they did, and independ-
ently as they did, their work overlapped in many ways.
Mal]»ighi is noteworthy for many discoveries in anatomical
science, for his monograph on the analomy of the silkworm,
for observations of ihe minute structure of (•■lants, and of the
development of the chick in the hen's egg. Swammerdam
did excellent and accurate work upon the anatomy and
metamorphosis of insects, and the internal structure of mol-
Kisks, frogs, and other animals, Leeuwcnhoek is distin-
guished for much general microscopic work; he discovered
various microscopic animalcula; he established, by direct
observation, the fact of a couneciion between arteries and
veins, and examined microsco] ileal ly minerals, plants, and
animals. To him, more than to ihe others, the general title
of " microrcopist " might be applied.
Since these men are so important in Ihe growth of biol-
ogj", let us, by taking them individually, look a little more
closely into their lives and labors.
;dbyGOOglC
S8 BIOLOGY AND ITS MAKKRS
Marcello Malpighi, 162S-1694
Personal Qualities. — There are sfvcral portraits of Mal-
pighi cxliinl. These, together with the account of his
jXTsonal appearance given by Atti, one of his biographers,
enable us to tell what manner of man he was. The jvortrait
shown in Fig, 13 is a copy of (he one painted bj' Tabor and
presented by Malpighi lo the Royal Society of London, in
whose rooms it may still be seen. This shows him in the
full allracliveness of his early manhood, with the earnest,
intellectual look of a man of high ideals and scholarly tastes,
sweet-tempered, and endowed with the insight that belongs
to a sympathetic nature. Some of his [JOrtraits taken later
are less attractive, and the lines and wrinkles that show
in his face give evidence of imperfect heahh. Acconling to
Atti, he was of medium stature, with a brown skin, a delicate
complexion, a serious countenance, and a melancholy look.
Accounts of his life show that he was modest, quiet, and
of a pacific disposition, notwithstanding the fact that he lived
in an atmosphere of acrimonious criticism, of jealousy and
conlrovers)'. A family dispute in reference to the boundan,'-
hnes between his father's property and the adjoining land of
the Sbaraglia family gave rise toa feud, in which representa-
tives of the latter family followed him all his life with efforts
to injure both his scientific reputation and his good name.
Under all this he suffered acutely, and his removal from
Bologna lo Messina was partly to escape the harshness of
his critics. Some of his bc-st qualities sho\ve<l under these
persecutions; he was dignifie<! under abuse anrl considerate
in his reply. In referfnce to the attacks ujxjn his scientific
standing, there were ]>ublished afier his death replies to his
critics that were written while he was smarting under their
injustice and severity, but these replies are free from liiliemess
and are w ritlc-n in a s])iril of great moderation. The follow-
ed byGoOglc
6o BIOLOGY AND ITS MAKERS
ing picture, taken from Ray's correspondence, shows the fine
control of his spirit. Under ihe dale of April, 1684, Dr.
Tancred Robinson writes : " Just as I left Bononia I had a
lamentable- spectacle of Malpighi's house all in flamfs,
occasioned by the negligence of his old wife. All his pic-
tures, furniture, books, and manuscripts were burnt. I saw
him in the very heat of the calamity, and mclhought I never
beheld so much Christian patience and philosophy in any
man before; for he comforted his wife and condolal nothing
but the loss of his papers."
Education. — Malpighi was bom at Crevalcuorc, near
Bologna, in 1628. His parents were landed pcasanis, or
farmers, enjoying an independence in financial malters. As
their resources permiltcd it, they designed lo give Marcellus,
their eldest child, the advantage of masters and schools.
He began a life of study; and, before long, he showwl a lasle
for belles-lettres and for philosophy, which he studied under
Nalali.
Through the death of both parents, in 16^9, Malpighi
found himself orphaned at the age of twenty-one, and as he
was the eldest of eight children, the management of domestic
affairs devolved upon him. He had as yet made no choice
of a profession; but, through the advice of Xatali, he resolve*!,
in 1651, to study medicine. This advice followe<l, in 1651,
at the age of twenty-five, he received from the Universiiy of
Bologna ihe degree of Doctor of Medicine,
University Positions. — In ihc course of a few years he
married the sister of Massari, one of his teachers in anatomy,
and became a candidate for a chair in the UnivLTsity of
Bologna. This he did not immediately receive, but, about
1656, he was appoinle<i lo a post in the university, and bef;;in
his career as a leacher and investigator. He must have
shown aptitude for this work, for he was soon called to ihe
University of I'isa, where, fortunately for his development,
;dbyGOOglC
INTRODUCTION OF THE MICROSCOPE 6:
he became associated with Borelli, who, as an older man,
assisted him in many ways. They united in some work, and
together ihey discovered the spiral character of the heart
muscles. But the climate of Pisa did not agree with him,
and after three years he returned, in 1659, to teach in the
University of Bologna, and applied himself assiduously to
anatomy.
Here his fame was in the ascendant, notwithstanding the
machinations of his enemies and detractors, led by Sbaraglia.
He was soon (1662) called to Messina to follow the famous
Castelli. .After a residence there of four years he again
relumed to Bologna, and as he was now thirty-eight years
of age, he thought il lime to retire to his villa near the city
in order lo dt;vote himself more fully to anatomical studies,
but he continued his lectures in the university, and also his
practice of medicine.
Honors at Home and Abroad. — Malpighi's talents were
appreciated even at home. The University of Bologna hon-
ored him in 1686 with a Latin eulogium; the city erected a
monument to his memory; and after his death, in the city of
Rome, his body was brought (o Bologna and interred with
great pomp and ceremony. At the three hundredth anniver-
sary of his <lcath, in 1894, a festival was held in Bologna,
his monument was unveiled, and a book of addresses by
eminent anatomists was published in his honor.
During his lifetime he received recognition also from
abroad, hut that is less remarkable. In 1668 he was elected
an honorary member of the Royal Society of London. He
was very sensible of this honor; he kept in communication
with the society; he presented them with his fx)rlrail, and
deposited in their archives the original drawings illustrating
the anatomy of the silkworm and the development of the chick.
In 1691 he was taken to Rome by the newly elected pope,
Innocent XII, as his personal physician, but under these new
;dbyGOOglC
62 BIOLOGY AND ITS MAKERS
conditions he was not destined to live many years. He died
there, in 1694, of aix)plcxy. His wife, of whom it appears
that he was very fond, had died a short time previiuidy.
Among his posthumous works is a sort of personal ])syclio!og>-
written down to the year 1691, in which he shows the growth
of his mind, and the way in which he came to takei'p the
difTcrent subjects of investigation.
In reference to his discoveries and the position he occupies
in the history of natural science, it sliould be observed that
he was an "original as well as a verj- profound obser\-er."
While the ideas of anatomy were still vague, " he applied him-
self with ardor and sagacity to the study of the fine structure
of the different parts of the body," and he extended his inves-
ilgations to (he siruclure of plants and of different animals,
and also to their deveiopmenl. Entering, as he did, a new
and unexplored lerritor)-, naturally he nuide many discover-
ies, but no man of mean talents could have done his work.
Activity in Research,— During forty years of his life he
was always busy with research. Many of his discoveries had
practical bearing on the advance of anatomy and physiology
as related to medicine. In 1661 he demonstralcd the struc-
ture of the lungs. Previously these organs had been regarded
as a sort of homogeneous jiarcnchyma. He showtxl ihe pres-
ence of air-cells, and had a tolerably correct idea of how the
air and the blood arc brought together in the lungs, the two
never actually in contact, but always se[Kiralcd by a mem-
brane. These discoveries were first made on the frog, and
apj)lied by analog)- to Ihc interpretation of the lungs of the
human body. He was a comparative anatomist, and the
first to insist on analogies of structure between organs
throughout the animal kingdom, and to make extensive
practical use of the idea that discoveries on simpler animals
can be iitili/:ed in interpreting the similar structurc-s in ilu-
higher ones.
;dbyGOOglC
INTRODUCTION OF THE MICROSCOPE <>3
It is very interesting to note thai in connection with this
work he actually observed the passage of blood through llic
capillaries of the transparent lungs of the frog, and also in
the mesenter)'. Although this antedates the similar obser-
vations of Leeuwcnhoclt (1669), nevertheless the work of
I^eeuwenhoek was much more comjjletc, and he is usually
recognized in physiologj- as the discoverer of the capillary-
connection between arteries and veins. At this same period
XIalpighi also obscn-cd the bloof! corpuscles.
Soon after he demonstrated the mucous layer, or pigment-
ary layer of the skin, intermediate between Ihc true and the
scarf skin. He had separated this layer by boiling ami
maceration, and described it as a reticulated membrane.
Even its existence was for a long time controverted, but it
remains in modem anatomy under the title of the Malpighian
layer.
His obsen-ation of glands was c\tensive,and while it must
be confessed that many of his conclusions in reference to
glandular structure were erroneous, he left his name connectc-d
with the Malpighian corjjuscles of the kidney and of the
spleen. He was also the first 10 indicate the nature of the
papilla- on the tongue. The foregoing is a res|)L-ciable list of
discoveries, but much more stands to his crc(iit. Those which
follow have a bearing on com|jaralive anatomy, zoology, and
botany.
Monograph on the Structure and Metamorphosis of the
Silkworm. — ^^al])ighi's work on the structure of the silkworm
lakes rank among the most famous monographs on the
anatomy of a single animal, ^^uch skill was required to
give to the world this picture of minute structure. The mar-
vels of organic architecture were being made known in the
human body and the higher animals, but "no inscTl — hanlly,
indeed, any animal^hafi then been carefully describt-d, and
all the methods of the work had to be discovered."' He
;dbyGOOglC
64 BIOLOGY AND ITS MAKERS
labored with such enthusiasm in this new terriiorj as to throw
himself into a fever and lo set up an inflammation in the eyes.
"Nevertheless," says Malpighi, "in performing these re-
searches so many marvels of nature were spread before my
eyes that 1 experienced an internal pleasure that my pen
could not describe."
He showed that the method of breathing was neither by
lungs nor by gills, but through a system of air-tubes, com-
municating with ihc e.xlerior through biitlonholeshaped
openings, and, internally, by an infinitude of branches reach-
ing to the minutest i»arts of (he body. Malpighi showed an
instinct for comparison; instead of confining his researches
to the species in hand, he exiended his obsenations to other
insects, and has given sketches of the brealhing-tubes, held
open by iheir spiral thread, taken from several species.
The nenous system he found to be a central white cord
with swellings in each ring of the body, from which ner\'cs
are given off to all organs and tissues. The cord, which is,of
course, the central nervous system, he found located mainly
on the ventral surface of the body, but extending by a sort
of collar of nenous matter around the ccsophagus, and on
the dorsal surface appearing as a more complex mass, or
brain, from which neri-es arc given off lo the eyes and other
sense organs of the head. As illustrations from this mono-
graph we have, in Fig. 14, reducwl sketches of the drawings
of the ncr\'0us system and the food canal in the adult silk-
worm. The sketch at the right hand illustrates the central
ner\*c cord with ils ganglionic enlargement in each segment,
the segments being indicated by ihc rows of spiracles at the
sides. The original drawing is on a much larger scale,
and reducing it lakes away some of its coarseness. .\11
of his drawings lack the finish and detail of Swammerdam's
work.
He showed also the food canal and the luhules connected
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INTRODUCTION OF THE MICROSCOPE 65
with the intestine, which retain^is name in the insect analomy
of to-day, under (he designation of Malpighian tubes. The
silk -forming apparatus was also figured and described. These
Malpighi's Analomy of Ike Silkworm,
slruclures arc rqiresentcd, as Malpighi drew iheni, on the
left of Fig. 14.
This monofjnipli, which was originally publishcii in 16(19
by ihc Roval Society of London, bears the Latin liile, Dhsi-r-
laiio Efiistolka de Bomhycc. It has been se\eral limes re-
published, ihe best edition being that in French, which dates
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66 BIOLOGY AN'U ITS MAKERS
from Montpdiicr, in 1878, and which is prefaced by an
account of ihc life and labors of Malpighi.
Anatomy of Plants. — ^^aIpighi's anatomy of plants con-
stitutes one of his best, a.s well as one of his most extensive
works. In the folio edition of his worl;s, 1675-79, ^^^
Anatome Planiarum occupies not less than 152 ]Kiges and
is illustrated by ninety-three plates of figures. It comprises
an exposition of the structure of bark, stem, roots, seeds, the
process of germination, and includes a treatise on galls, etc.,
etc.
In this work the microscopic structure of plants is amply
illustrated, and he anticijated to a certain degree the ideas on
the cellular structure of plants. Burnett says: "Hisobser-
\'ations appear to have been very accurate, and not only did
he maintain the cellular structure of plants, but also declarei'.
that it was comjxwed of scjjarale cells, which he designated
' utricles.' " Thus did he foreshadow the cell Iheon,- of plants
as developed by Schleiden in the nineteenth century. When
it came to interpretations, he made several errors. Applying
his often-asserted principle of analogii's, he concluded that
the vessels of plants are organs of respiration and of circula-
tion, from a certain resemblance that they hear to the breath-
ing-tubes of insects. Bui his ob.ervations on structure are
good, and if he had accomplished nothing more than this
work on plants he would have a place in the history of tx»tany.
Work in Embryology.— I) ilVicult as was his task in insLTt
anatomy and plant histology, a more ditlicult one remains to
be mentioned, viz., his obsen'ations of the develojiment of
animals. He had pushed his resuirchcs into the finer struc-
ture of organisms, and now he r.'.iempied to answer this
([ucslion: How does one of these onjanisms begin its life,
and by what series of steps is its baly built up? He turned
to the chick, as the most available form in which to get an
insight into this ]>rocess, but he coulii not e.xtend his obser-
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INTRODUCTION OF THE MICROSCOPE 67
vat ions successfully into periods earlier than about the
twenty-four-hour stage of de\-elopment. Two memoirs were
written on this subject, both in 1672, which were published
by the Royal Society of England under (he titles Dc Forma-
tione Pulli in Ovo and De Ovo Incubalo. Of all Malpighi's
work, this has received the least attention from reviewers,
but it is, for his time, a very remarkable achievement. \o
one can look over the ten folio plates without being impressed
with the extent and accuracy of his obseri-ations. His
sketches are of interest, not only to sludcnl?of embryology,
but also to educated people, to sec how far observations
regarding the development of animals had progressed in 1672,
Further consideration of his position in cmbryolog)- will be
found in the chapter on the rise of that subject.
Little is known regarding the form of microscope em-
ployed by Malpighi. Doubtless, much of his work was done
with a simple lens, since he speaks of examining the dried
lungs with a microscope of a single lens against the hori-
zontal sun; but he is also known to have observed with an
instrument consisting of two lenses.
Malpighi was a naturalist, but of a new type; he began to
look below the surface, and essayed a deeper level of analysis
in obsening and describing the internal and minute structure
of animals and plants, and when he took the further step of
investigating their development he was anticipating the work
of the nineteenth ccnturj'.
Jan Swammerdam (1637-1680)
Swammerdam was a diflcrcnt type of man — nen-ous,
incisive, ver\' intense, stubborn, and self-willed. Much of his
character shows in the ix)rtrait by Rembrandt represented
in Fig. 15. .\llhough its authenticity has been qucstioncfl,
il is the only known portrait of Swammerdam.
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68 BIOLOGY AND ITS MAKERS
Early Interest in Natural History. — He was bom in 1637,
nine years aflcr Malpighi, His falher, an apothecary of Am-
sterdam, had a taslc for collecting, which was shared by many
of his fcUow- towns men. The Dutch people of this time
sent their ships into all parts of the world, and this vast com-
merce, together with their extensive colonial possessions,
fostered the formation of private museums. The elder
Swammerdani had the finest and most celebrated collection
in all Amsterdam. This was stored, not only with treasures,
showing the civilization of remote countries, but also with
specimens of natural histor;-, for which he had a decided
liking. Thus "from the earliest dawn of his understanding
(he young Swammerdani was surrounded by zoological
specimens, and from the joint influence, doubtless, of hered-
itary taste and early association, he became passionately
de\-oted to the study of natuml history,"
Studies Medicine. — His father intende<l him for the
church, but he had nolaste for theology, though he became
a fanatic in religious mailers toward the close of his life;
at this period, however, he could brook no restraint in worI
or action. He consented to .^tudy medicine, but for some
reason he was twenty-six years old before entering the Uni-
versity of Leyden. This delay was very likely owing to his
]>recarioushe-aIth, but, in the mean time, he had not been idle;
he ha'l devotfl himself to observation and study with great
ardor, and had alrc'ady become an expert in minute dissec-
tion. When he went to the University of I-eyden, therefore',
he at once look high rank in anatomy. Anything demanding
fine manipulation and dexterity was directly in his line. He
coniiniii-d hissliidits in Paris, and about 1667 look his degree
of Doctor of Me<!icinc.
During this pcrio<l of medical study he made some rather
ini|H>r(ani oljsen'al ions in human anatomy, and inlroduct.'d
the method of injection that was afterward claimed bv
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FlO 15.— SWAMMERDAM. 16,17-'
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7° BIOLOGY AND ITS MAKERS
Ruysch, In 1664 he discovered the valves of lymphatic
vessels by the use of slender glass tubes, and, three years
later, first used a waxy material for injecting blood-vessels.
It should be noted, in jossing, ihat Swammerdam was the
first to obscnc and describe the blood corpuscles. As early
as 1658 he described them in the blood of the frog, but not
till fifty-seven years after his death were his obsenations
published by Boerhaavc, and, therefore, he does not get the
credit of this discover)-. Publication alone, not first observa-
tion, establishes priority, but there is conclusive evidence
that he observed the blood corpuscles before either Malpighi
or Leeuwenhoek had published his findings.
Love of Minute Anatomy. — After graduating in medi-
cine he did not practice, but followed his strong inclination
to devote himself to minute anatomy. This led to differences
with his father, who insisted 011 his going into practice, but
the self-willed stubbornness and firmness of the son now
showed themselves. It was to gratify no love of ease that
Swammerdam thus held out against his father, but to be
able to follow an irresistible leading toward minute anatomy.
At last his father planned to stop supplies, in order to force
him into the desired channel, but Swammerdam made efforts,
without success, to sell his own personal collection and pre-
serve his independence. His father died, leaving him suffi-
cient property to live on, and brought the controversy to a
close soon after the son had consented to yield to his wishes.
Boerhaave, his fellow-countryman, gathered Swammer-
dam's complete writings after his death and published them
in 1737 under the title Biblia Nalur<F. With them is in-
cluded a life of Swammerdam, in which a graphic account is
given of his phenomenal industry, his intense application, hi^
metho<ls and instruments. Most of the following passages
are selected from that work.
Intensity as a Worker. — He was a verj- intemperate
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INTRODUCTION OF THE MICROSCOPE 71
worker, and in finishing his treatise on bees (1673) he broke
himself down.
"It was an undertaking too great for the strongest con-
stitution to be conlinuallyemployed by day in making obser-
vations and almost as constantly engaged by night in record-
ing them by drawings and suitable explanations. This being
summer work, his daily labors began at six in the morning,
when the sun afforded him light enough to enable him to
survey such minute objecis; and from that time till twelve
he continued without interruption, all the while exposed in
the open air to the scorching heat of ihe sun, bareheaded,
for fear of interrupting the light, and his head in a manner
dissolving into sweat under the irresistible ardors of that
powerful luminar)-. And if he desisted at noon, it was only
because the strength of his eyes was too much weakened by
the cxtraordinarj- efflux of light and the use of microscopes
to continue any longer u]K)n such small objects.
"This fatigue our author submitted to for a whole month
together, without any interruption, merely to examine, de-
scribe, and represent the intestines of bees, besides many
months more bestowed upon the other parts; during which
time he spent whole days in making obsen'ations, as long as
there was sufficient light to make any, and whole nights in
registering his obsen'ations, till at last he brought his treatise
on bees to the wished-for yjcrfection."
Method of Work.^" For dissecting verj' minute objects, he
had a brass (able made on ])Urposc by that ingenious artist,
Samuel Musschcnbroek, To this table were fastened two
brass arms, movable at pleasure to any part of it, and the
upper portion of these arms was likewise so contrived as to
be susceptible of a very slow vertical motion, by which means
the operator could readily alter their height as he saw most
convenient lo his purpose. The office of one of these arms
was lo hold the Httlc corpuicles, and that of the other to apply
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J2 BIOLOGY AND ITS MAKERS
the microscope. His microscopes were of various sizes and
curvatures, his microscopical glasses being of various diam-
eters and focusc-s, and, from llu- least to the grcalest, the best
that could be procured, in regard to the exactness of the work-
manship and the transparency of the substatice.
"But the constructing of verj- fine scissors, and giving
them an extreme sharpness, seems to have been his chief
secret. These he made use of to cut verj' minute objects,
because they dissected them equably, whereas knives and
lancets, let them be ever so fine and sharp, are apt lodisorder
delicate substances, iii knives, lancets, and styles were so
fine that he cculd not '•ce tc, sharpen (hem without the assist-
ance of the microscope; but with them he could dissect ihu
intestines of bees with the same accuracy and distinctness
that others do those of large animals.
"He was i)articularly dexterous in the management of
small tubes of glass no thicker than a bristle, drawn to a ver\
fine (xjint at one end, but thicker at the other."
These were used for inflating hollow structures, and also
for making fine injections. He dissolved the fat of inst-cts
in turpentine and carried on dissections under water.
An unbiased examination of his work wilt show tlial il i:-
of a higher quality than Malpighi's in regard to critical
observation and richness of detail. He also workwl wiiii
minuter objects and displayed a greater skill.
The Religious Devotee.— The last jiart of his life was
dimmed by fanaticism. He read the works of .\nloineUe
Bourignon and fell under her infiuence; he began lo subdue
his warm and stubborn temper, and to give himself up tn
religious contcm[)lu(ion. She taught him to regard scieni ilk-
research as worldly, and, following her advice, he gave iqi lii>
pas.sionate fondness for stUflying the works of the Creator,
to devote himself to the love and adoration of that sunu'
Being. Always extreme and intense in everything he under
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INTRODUCTION" OF THE MICROSCOPE 73
took, he likewise overdid ihis, and yielded himself to a sort
of fanatical worship until (he end of his life, in 1680. Had
he possessed a more vigorous constitution he would have
been grealer as a man. He lived, in all, but forty-three years;
the last six or seven years were unproductive because of his
menial distractions, and before that, much of his time had
been lost through sickness.
The Biblia Naturas.— It is time 10 ask. What, with all his
talents and prodigious application, did he leave to science?
Thi^ is best answered by an examination of the Bibtia Na-
luree, under which title all his work was collected. His treatise
on Bees" and Mayflies snd a few other articles were pub-
lished during his lifetime, but a large part of his obsenations
remained enlirely unknown until they were published in this
book fifly-sevcn years after his death. In the folio edition
it embraces 410 pages of text and fifty-three plales, replete
with figures of original obsenations. It "contains about a
dozen life-histories of insects worked oul in more or less
detail. Of these, Ihe mayfly is the most famous; that on
the honey-bee the most elaborale." The greater amount of
his work was in structural enlomolog>-. Il is known that he
had a collection of about three thousand different species of
insects, which for that period was a \cry large one. There
is, however, a considerable amount of work on olheranimals;
Ihe line anatomy of the snail, the structure of the clam, the
sc|uid ; ohser\alions on the structure and development of the
frog; obsen'ationson the contraction of the muscles, e1c.,elc.
It is lo be remembered that Swammerdam was extremely
exact in all that he did. His descriptions are models of
accuracy and comjdetencss.
Fig. 16 shows reduced sketches of his illustrations of the
structure of the snail. The upper sketch shows the central
nervous system and the nerve trunks connected therewith,
and the lower figure shows the shell and the principal muscles.
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INTRODUCTION OF THE MICROSCOPE 75
This is an exceptionally good piece of anatomization for that
time, and is a fair sample of the fidelity wilh which he worked
out details in the structure of small animals. Besides show-
ing this, these figures also serve the purpose of pointing out
that Swammerdam's fine anatomical work was by no means
confined to insects. His determinations on the structure of
the young frog were equally noteworthy.
But we should have at least one illustration of his handling
of insect anatomy to compare more directly with that of
Malpighi, already given. Fig. 17 is a reduced sketch of the
anatomy of the Iar^■a of an ephemerus, showing, besides other
structures, the central nervous system in its natural position.
When compared with thedrawings of Malpighi, we see there
is a more masterly hand at the task, and a more critical spirit
back of the hand. The nen-ous system is verj' well done,
and the greater detail in other features shows a disposition
to go into the subject more deeply than Malpighi.
Besides working on ihe structure and life-histories of ani-
mals, Swammerdam showed, experimentally, the irritability
of nerves and the response of muscles after Ihcir removal
from the body. He not only illustrates this quite fully, but
seems to have had a pretty good appreciation of the nature
of the problem of the physiologist. He says:
" It is evident from the foregoing obser\ations that a great
number of things concur in the contraction of the muscles,
and that one should be thoroughly acquainted with that
wonderful machine, our bofiy, and the elements with which
we are surrounde'), to describe exactly one single muscle
and explain its action. On this occasion it would be neces-
sar\' for us to consider the atmosphere, the nature of our food,
the blood, the brain, marrow, and ner\-es, that most subtle
matter which inslantaneously flows to the fibers, and many
other things, before we could expi-ct lo attain a sight of the
perkTt and certain truth."
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INTRODUCTION OF THE MICROSCOPE 77
In reference to the formation of animals within the egg,
Swammcrdam was, as Malpighi, a believer in the pre-forma-
tion lheorj\ The basis for his position on this question will
be set forth in the chapter on the Rise of Embryology,
There was another question in his time upon which philos-
ophers and scientific men were divided, which was in reference
to the origin of living organisms: Does lifeless matter, some-
times, when submitted to hi-at and moisture, spring into life?
Pid the rats of Egj-pt come, as the ancients believed, from
the mud of the Nile, and do frogs and toads have a similar
origin ? Do insects spring from the dew on plants? etc., etc.
The famous Redi performed his noteworthy experiments
n'hcn Swammerdam \i'as twenty-eight years old, but opinion
was divided upon the question as to the possible spontanc'ous
origin of life, especially among the smaller animals. Upon
this question Swammerdam took a positive stand; he fanned
himself on the side of the more .scientific naturalists against
the spontaneous formation of life.
Antony van Lekiwenhoek (i632-!72.i)
In T.eouwenhock we find a comix)scd and better-balanced
man. Blessed with a vigorous constitution, he lived ninety-
one years, and worked to the end of his life. He was bom
in i0?2, four years after Malpighi, and five before Swammer-
dam; they were, then, strictly speaking, contemporaries.
He stamis in contrast with the other men in being self-taught ;
he did not have the advantage of a university training, and
apparently never had a master in scientific study. This lack
of systematic training shows in the desultorj' character of his
extensive observations. Impellc<i by the same gift of genius
that drove his confreres to study nature with such unexampk-d
activity, he too followed the path of an independent and
enthusiastic investigator.
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78 BIOLOGY AND ITS MAKERS
The portrait {Fig. 18) which forms a frontispiece to his
Arcana Nalura represents him at the age of sixty-three,
and shows the pleasing countenance of a firm man in vigor-
ous health. Richardson says: "In the face peering through
the big wig there is the quiet force of Cromwell and the
delicate disdain of Spinoza." "It is a mixed racial iy\ye,
Semitic and Teutonic, a Jewish-Saxon; obstinate and yet
imaginative; its vcr\' obstinacy a virtue, saving it from flying
too far wild by its imagination."
Recent Additions to His Biography. — There was asingular
scarcity of facts in reference to Leeuwenhoek's life until 1885,
when Dr. Richardson published in TkeAsdepiad * the results
of researches made by Mr. .\.Wynter BlythinT.eeuwcnhoek's
native town of Delft. I am indebted to that article for much
that follows.
His Arcana Naluris and other scientific letters contained
a complete record of his scienlific activity, but "about his
parentage, his education, and his manner of makinga living
there was nothing but conjecture to go upon." The few
scraps of personal hislon.- were contained in the Kncyclo-
pa-dia articles by Carpenter and others, and these were
wrong in sustaining the hypothesis that I.eeuwenhock was
an optician or manufacturer of lenses for the market. .\1-
though he ground Icnsts for his own use, there was no need
on his part of increasing his financial resources by their sale.
He held under the court a minor oflice designated 'Chamber-
lain of the SheriiT.' The duties of the otTice were those of a
beadle, and were set forth in his commission, a document
still extant. The rerjuirements were light, as was also the
salary', which amounieti to about £2(1 a year. He held this
I>osl for thirty-nine yt'ars, ami the sli]>end was thereafter
continuefl to him to the end of lu's life.
Van Leeuwenhoek was deri\'ed from a good I>elfl family.
* Ufu'^-caluxk and Ihe KiV of IlUloUgy. Thr Asclepiad, Vol, II, 18S5,
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Digitized by VjOOQIC
So BIOLOGY AND ITS MAKERS
Hisgrandfatherand his great-grandfalhcr were Delft brewers,
and his grandmother a brewer's daughter. The family were
doubtless wealthy. His schooling seems to have been brought
to a close at the age of sixteen, when he was '' reniovwj to a
clothing business in Amsterdam, where he filled the olTicc of
bookkeeper and cashier." After a few years he returned to
Delft, and at the age of twenty-lwo he married, and gave
himself up largely to studies in natural histor;\ Six years
after his marriage he obtained the appointment menlioncfl
above. He was twice niarrierl, but left only one child, a
daughter by his first wife. In the old church at Delft is a
monument erected by this daughter to the raemor}' of her
father. ,
He led an easy, prosperous, but withal a busy life. The
microscope had recently been invented, and for obscrvLilion
with that new instrument Leeuwenhoek showed an avidity
amounting to a passion.
"That he was in comfortable, if not affluent, circum-
stances is clear from the character of his writings; that he
was not troubled t)y any very anxious and responsible dulies
is certain from the continuity of his scientific work; thai he
could secure the ser\'iccs of persons of influence is discernible
from the circumstances that, in 1673, De Craaf sent liis first
paper to the Royal Society of London ; that in 1680 thf same
society adniillcd him as fellow; that the directors of the Kast
India Company sent him specimens of natural history, and
that, in 1698, Peter the Great paid him a call lo inspect his
microscopes and their revelations."
Leeuwenhoek seems to have been fascinated by the mar-
vels of the microscopic world, but (he extent and (]ualily of
his work lifted him above the level of the diletlanle. He
was not, like Malpighi and Swammerdam, a skilled dissector,
but turned his microscope in all directions; to the mlniral
as well as lo the vegetable and animal kingdoms. Just when
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INTRODUCTION OF THE MICROSCOPE 81
he began to use the microscope is not known; his first pub-
lication in reference to microscopic objects did not appear
till 1673, when he was forty-one ycai-s old.
His Microscopes. — He gave good descriptions and draw-
ings of his instruments, and those still in existence have been
described by Carpenter and others, and in consequence we
have a very good idea of his working equipment. During
his lifetime he sent as a present to the Royal Society of
Ixindon twenty-six microscopes, each provided with an object
to examine. Unfortunately, these were removed from the
rooms of the society and lost during the eighteenth century.
His lenses were of fine quality and were ground by himself.
They were nearly all simple lenses, of small size but con-
siderable curvature, and needed to be brought close to the
object e.\amined. He had different microscopes for different
purposes, giving a range of magnifying powers from 40 to 270
diameters and possibly higher. The number of his lenses is
surprising; he possessed not less than 247 complete micro-
scopes, two of which were provided with double lenses, and
one with a triplet. In addition to the above, he had 172
lenses set between plates of metal, which give a total of 419
lenses used by him in his observations. Three \\ere of
quartz, or rock crystal; the rest were of glass. More than
one-half the lenses were mounted in silver; three were in
gold.
It is to be understood that all his microscopes were of
simple construction; no tubes, no mirror; simple pieces
of metal to hold the magnifying -glass and the objects to
be examined, with screws to adjust the posiiion and the
focus.
The three aspects of one of l-ccuwenhoek's microscopes
shown in Fig. 19 will give a very good idea of how they were
constructed. These pictures represent the actual size of
the instrument. The photographs were made by Professor
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S3
BIOLOGY AND ITS MAKERS
Nierstrasz from the specimen in possession of the Univeisity
of Utrecht. The instrument consists of a double copperplate
in which the circular lens is inserted, and an object-holder —
represented in the right-hand lower figure as ihrown to one
side. By a vertical screw ihc object could be elcvatwi or
depressed, and by a transverse screw it could be brouf^lii
nearer or removal farther from the lens, and thus be broii^iii
into focus.
Fig. 2oa shows the way in which Ihe microsco])e was
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INTRODUCTION OF THE MICROSCOPE %
arranged to examine the circulation of blood in the trans-
parent tail of a small fish. The fish was placed in
water in a slender glass tube, and the latter was held in a
metallic frame, to which a
plate {marked D) was joined,
carrying the magnifying
glass. The latter is indi-
cated in the circle above the
letter D, near the tail-fin of
the fish. The ej'e was ap-
plied close to this circular
magnifying-glass, which was
brought into position and
adjusted by means of screws.
In some instances, he had a
concave reflector with a hole
in the center, in which his
magnifying-glass was insert-
ed; in this form of instru-
ment the objects were illu-
mined by rellected, and not
by transmitlcd light.
His Scientific Letters.^
His microscopic obsenations
were ^Icscribed and sent to
learned societies in the form
of letters. " AH or nearly all
ihal he did in a literar\' wuy
was after the manner of an
epistle," and his written com-
munications were so numer-
ous as (o justify the cogno-
men, "The man of manv „ F""-, aoa. — Lcpun-enliooVs
Mechanism tor bx^imining the
letters. ' The French Acad- Circulation of the lllood.
1
4
c
V
^
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84 BIOLOGY AND ITS MAKERS
cmy of Sciences, of which he was elected a corresponding
member in 1697, got twenty-seven; but the lion's share
fell to the young Royal Society of London, which in fifty
years — 1673-1733 — received 375 letters and papers." " The
works themselves, except that they lie in the domain of
natural history, are disconnected and appear in no order
of systematized study. The philosopher was led by what
transpired al any moment to lead him."
The Capillaiy Circulation. — In 1686 he obsencd the
minute circuhitiop of the blood, and demonstrated the cajiil-
lary connfction between arlcrie
■ and veins, thus forging the
final link in the chain of
obscr\*alion showing the
relation between these
blood-vessels. This v.as
perhaps his most imjiortant
observation for its bearin.n
on physiolog)-. It must be
remembered that Han-ey
had not actually seen the
circulation of the blood,
which he announced in
1628. He assumed on en-
tirely sufticient grounds the
existence of a complete cir-
culation, but there was
wanting in his scheme the
direct ocular proof of the
passage of blood from arteries to veins. This was suj^plied
by Lceuwenhock. Fig. 20ft shows one of his sketches of the
capillar)- circulation. In his elTorts lo sec the circulation
he tried various animals; the comb of the young cock, the
ears of white rabbits, (he membraneous wing of the bat were
progressively examined. The next advance came when he
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INTRODUCTION OF THE MICROSCOPE 85
directed his microscope to the tail of the tadpole. Upon
examining this he exclaims:
" A sight presented ilsdf more delightful than any mine
eyes had ever beheld; for here I discovered more than fifty
circulations of the blood in different places, while the animal
lay quid in the water, and I could bring it before my micro-
scope to my wish. For I saw not only that in many places
the blood was conveyed through exceedingly minute vessels,
from the middle of the tail toward the edges, but that each
of the \fs?els had a cun-e or turning, and carried the blood
back toward the middle of the tail, in order to be again con-
veyed to the lieart. Hereby it plainly appeared to me tliat
the blood-vessels which I now saw in the animal, and which
boar the nam(^ of arteries and veins arc, in fact, one and the
same; that is to say, that they are properly termed arteries
so long as they convey the bloal to the furtherest extremities
of its vessels, and veins when they bring it back to the heart.
And thus it appears that an artery and a vein are one and
the same ve-s^el prolonged or extended."
Thi^, description shows that he fuily appreciated Ihe course
of ilio minute vascular circulation and the nature of the
communication between arteries and veins. He afterward
extendwt his obseirations to the web of the frog's foot, the
tail of young fishes and eels.
In connection with this it should be remembered that
Malpighi, in iftGi, obsened the flow of blood in the lungs
and in the mi'sentery of the frog, but he made little of the
discovery. Leeuwenhoek did more with his, and gave the
first clear idea of the capillary circulation. Leeuwenhoek
was anlicipaiLtl also by Malpighi in rcftTcncc to the micro-
sco|)ic structure of tlie blood. (Sec also under Swammer-
dam.l To Maljiiglii the corpuscles appeared to be globules
offal, while Leeuwenhoek noted that the blood disks of
birds, fr(iu'>, and fishes were oval in outline, and those of
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86
BIOLOGY AND ITS MAKERS
mammals circular. He reserved the term ' globule ' for
those of the human body, erroneously believing them to
be spheroidal.
Other Discoveries. — Among his other discoveries bear-
ing on physiology and medicine may be mentioned: the
branche<l character of heart muscles, the stripe in voluntarj'
muscles, the st™cture of the crystalline lens, the description
of spcrmalozoa after they ha<l been pointed out to him in
1674 by Hamen, a medical student in Leydcn, etc. Richard-
son dignified him with the title 'the founder of histology,'
but this, in view of the work of his great contemporary,
Malpighi, seems to mc an overestimate.
Turning his microscope in all directions, he examined
water and found it peopled with niinulc animalcules, those
simple forms of animal life projjcllcd through the water by
innumerable hair-like cilia extending from the body like
banks of oars from a galley, except that in
many cases they extend from all surfaces.
He saw not only the animalcules, but also
the cilia that move their bodies.
He also discovered the Rotifers, those
favorites of the amateur microscopists, made
so familiar to the general public in works
like fiosse's Evenings at Ihe Microscope.
He obscn,-cd that when water containing
these animalcules
eva];orated they were
reductf! to fine dust,
but became alive
again, after great
lap'ies of lime, by the
introduction of water.
He made many
obsenations on the
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INTRODUCTION OF THE MICROSCOPE 87
microscopic structure of plants. Fig. 21 gives a fair sample
of the extent lo which he observed the cellular construction
of vegerablcs and anticipated the cell theor>'. While Mai-
pighi's research in that field was more extensive, these
sketches from Lceuweuhock represent very well the char-
acter of the work of the period on the minute structures
of plants.
His Theoretical Views. — It remains to say that on the
two biological questions of the day he took a decisive stand.
He was a believer in preformation or pre-dclinealion of the
embrjo in an extreme degree, seeing in fancy the complete
oulline of both maternal and paternal individuals in the
s[KTmalozoa, and going so far as lo make sketches of the
same. But on the question of the spontaneous origin of life
he took the side that has been supported with such triumphant
demonstration in this century; namely, the side opposing the
theon,' of the occurrence of spontaneous generation under
present conditions of life.
Comparison of the Three Men. — We sec in these
three gifted contemporaries different personal characteristics.
I-eeuwciihoek, the composed and strong, attaining an age
of ninety-one; Malpighi, always in feeble health, but direct-
ing his energies with rare capacity, reaching the age of sixly-
sevcn ; while the great intensity of Swammerdam stopped his
scientific career at thirty-six and burned out his life at the
age of forty-three.
They were all original and accurate observers, but there
is variation in the kind and quality of their intellectual prod-
uct. The two university- 1 rained men showed capacity for
coherent observation; they were both better able to direct
their efforts toward some definite end; Leeuwenhoek, with
the advantages of vigorous health and long working period,
lacked the systematic training of the schools, and all his life
wrought in discursive fashion; he left no coherent |)iecc of
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88 BIOLOGY AN'D ITS MAKERS
work of any extent like Malpighi's Analome Planlarum or
Swammcrdam's Anatomy and Metamorphosis of Insects.
Swammerdam was the most critical observer of the three,
if wc may judge by his labors in the same field as Malpighi's
on the silkworm. His descriptions are models of accuracy
and completeness, and his anatomical work shows a higher
grade of finish and completeness than Malpighi's. Malpighi,
it seems to me, did more in ihe sum total than either of Ihc
others to advance the sciences of anatomy and physiology,
and through them the interests of mankind. Leeuwenhock
had larger opportunity; he devoted himself to microscopic
observations, but he wandered over the whole field. \\ hile
his observations lose all monographic character, nevertheless
they were important in opening new fields and advancing the
sciences of anatomy, physiology, botany, and zoSlogj'.
The rombined force of their labors marks an epoch
characterized by the acceptance of the scientific method and
the establishment of a new grade of intellectual life. Through
their efforts and that of their contemporaries of lesser ucw
the new intellectual movement was now well under wav.
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CHAPTKR V
THE PROGRESS OF MINUTE ANATOMY.
The work of Malpighi, Swammordam, and Lceuwenhoek
stimulated investigations into the structure of minute an-
infials, and researches in thai field became a frature of the
advance in the next centiir}-. Considerable progress was
made in the province of minute anatomy before comparative
anatomy grew into an independent subject.
The attractiveness of oleen-ations upon the life-histodes
and the structure of insects, as shown particularly in ihe pub-
lications of Malpighi and Swammerdam, made those animals
the favorite objects of study. The obsencrs were not long
in recognizing that some of the greatest beauties of organic
architecture arc displayed in the internal staicture of
insects. The delicate tracery of the organs, their minuteness
and perfection are well calculatefl to awaken surprise. Well
might those early anatomists be moved to enthusiasm over
their researches. Ever)' excursion into this domain gave
only beautiful pictures of a mechanism of exquisite delicacy,
and their wonder grew into amazement. Here began a new
train of ideas, in the unexpected revelation that within the
small compass of the body of an insect was embraced such
a complex set of organs; a complete nen'ous system, fine
breathing-tubes, organs of circulation, of digestion, etc., etc.
Lyonet. — The first piece of structural work after Swam-
mcrdam's to which we must give attention is that of Lyonet,
who produced in the middle of the eighteenth century one of
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9°
BIOLOGY AND ITS MAKERS
the most noteworthy monographs in the field of minute
anatomy. This was a work like that of Malpighi, upon the
anatomy of a single form, but it was carried out in much
greater dclail. The 1,^7 figures on the iS plates arc models
of close obser\ation and fine execution of drawings,
I.yonct (also wntlen T-yonnei) was a Hollander, born in
The Hague in 1707. He was a man of varied talents, a
painter, a sculptor, an engraver, and a vcrj' gifted linguist.
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PROGRESS OF MINUTE ANATOMY 9^
It is said that he was skillwJ in at least eight languages; and
at one time he was the cipher secretan' and confidential
translator for the United Provinces of Holland. He was
educated as a lanTcr, but, from interest in the subject, de-
voted most of his time to engraving objects of natural history.
.\mong his cariiest published drawings were the figures for
Lester's Theology 0} Insects (1742) and for Tremblcy's
famous treatise on Hydra (174-1)-
His Great Monograph.^Finally Lyonct decided to branch
out for himself, and produce a monograph on insect anatomy.
After some preliminarj- work on the sheep-tick, he settled
u|X)n the caterpillar of the goat moth, which lives upon the
willow-trcc. His work, first published in 175c, bore the title
Train Anaiovuque ile la Chenille qui range le bois lie Saale.
In exploring the anatomy of the form chosen, he displayed
not only jjaticnce, but great skill as a dissector, while his
superiorily as a draughtsman was continually shown in his
sketches. He engraved his own figures on copper. Thcdraw-
ingsarcverj- remarkable for the amount of detail that they
show. He dissected this form with the same thoroughness
with which medical men liave dissected the human body.
The superficial muscles were oircfully drawn and were then
cut away in order to expose the next underlying layer which,
in turn, was sketched and then removed. The amount of
detail involved in this work may be in part realized from the
circumstance that he distinguished 4,041 separate muscles.
His sketches show these muscles accurately drawn, and the
principal ont-s are leltcre-d. When he came to expose the
ncn-cs, he followed the minute branches to individual small
muscles and sketched them, not in a diagrammatic way, but
as accurate drawings from the natural object. The breath-
ing-tulx-s we-c followed in the same manner, and the other
organs of the body were all dissected and drawn with remark-
able thoroughness. Lyonet was not Irained in anatomy
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BKJUMiV AND ITS MAKERS
like >[alpighi and Siva:
[Kilience and manual
results. His fireat qu;
scription of the fig^lre^
tire head is not more
cter, but in a si-rii-s of
internal organs in ihi
mmcrdam, but being a nmn of unusual
(k'xicrily, he acconiplishwl notable
larlo volume is, however, merely a de-
;, and lacks the insight of a trained
anatomist. His skill as a dissector
is far ahead of his knowledge of
anatomy, ajid he becomes lost in
the details of his subject.
Extraordinary Quality of the
Drawings. — A few fiKurcs will ser\ e
to illustrate the character of his
work, but the reduced reproduc-
■ions which follow can not do justice
to the copper plates of the orii'inal.
Fig. 27, gives a view of the exter-
na! appeat^ance of the caterpillar
which was dissected, \\hen the
skin was removed from the outside
the muscles came into view, as
shown in Fig. 2j. This is a view
from the ventral side of the animal.
On the left side the more sujier-
ticial muscles show, anfl on the
right the next deeper layer.
Fig. 25 shows his dissection of
the nen-cs. In this figure the mus-
cles arc indicated in oiitlinc, and
the distribution of nerves to partic-
ular muscks is shown.
l.yonet's dissection of the hiad
is an extraordinar)- ft-at. The iii-
than a i|uaner of an inch in diani-
seven dissections he shi)w< all of ihe
head. Fig. 26 shov,> \v.ii >ke?chi-
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Fic. 14 —Muscles of the l.arvn t)E the Williiw Motli- [From
I.V'inet's Mtinugraph. )
Fi'.-.. 35. — Central Nervous System iind Nervts uf the Sfinie.
Digitized by VjOOQIC
9+
BIOLOr.Y AND ITS MAKERS
exhibiting the nervous gani^lia, the air Uibcs, and muscles of
the head in their natural jxisilion.
Fig. 27 shows the nen-ous system of the head, including
the extremely fine ncn'ous massc-s which arc designated the
sympathetic ner\*ous system.
The extraordinary character of the drawings in Lyonet's
monograph created a sensation. The existence of such com-
plicated slruclures wilhin ihc l)ody of an insect was <iis-
■6.— Dissection of the Head of the Larva of the Willow Moth,
credited, and, furthermore, some of his critics declara! thai
tTen if such a fine oi^ni/alion existed, it would be beyond
human jiossiijilities to ex]K>se the details as shown in his
sketches, .\ccordingly, T.yonet was accused of drawing on
his imagination. In order 10 silence his critics he published
in the second wlition of his work, in 1752, drawings of his
instruments and a di-scription of his methods.
I.yonel intended 10 work out the anatomy of the chr^^sidis
and llie adult form of the same animal. In pursuance of
;dbyGOOglC
PROGRESS OF MINUTE ANATOMY
95
this plan, he made niany disseclions and drawings, but, at
ihe age of sixty, on account of the condition of his eyes, he
was obliged lo stop all close work, and his project remained
unfinished. The sketches which he had accumulated were
published later, but they fall far short of those illustrating
F(c,
1 and Head Nei
the TraiU Aiuitomique. Lyonct died in 1789, at the age of
eighty -one.
Roesel, Reaumur, and De Geer on Insect Life. — We must
also take note of the fact that, running parallel with this work
on the anatomy of insects, obscnatioiis and publications had
gone fonvard on form, habits, and metamorphosis of insects,
that did more to advance the knowjedi-e of insect life than
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96 BIOLOGY ASD ITS MAKERS
Lyonct's researches. Rocscl, in Germany, Reaumur, in
France, and De Geer, In Swwien, were all Hislinguislifi ob-
scr\'crs in this line. Their works are voluminous and arc
well ijluslralfd. Those if R<5aumiirand De Geer look the
currenl French title of Mimciii-s pour srn-ir a I'Hisloire fivs
Insfcles. The plates with which the collcctal publications
of each of Ihc three men are provided show many sketches
of external form and details of external anatomy, but very-
few illustrations of internal anatomy occur. The sketches
of Roesel in particular are worthy of examination at the pres-
ent lime. Some of his masterly figures in color are fine
examples of the art of jminting in miniature. The name of
Roesel (Fig. a8) is connected also with the earliest observa-
tions of protoplasm and with a notable publication or. the
Batrachians.
Rfeumur (Fig. 2(>), who \\as distinguished for kindly
and amiable personal qualities, was also an important man
in his influence upon the progress of science. He was both
physician and naturalist; he made experiments u]K>n the
physiology of digestion, which aided in the understanding of
that process; he invented the thermometer which beari his
name, and did other services for the advancement of sci-
ence.
Straus-Durckheim's Monograph on Insect Anatomy. —
Insect anatomy continued to attract a number of obscrven;,
but we must go fonvard into the nineteenth century before
we find the subject taking a new direction and merging into
its modern phase. The remarkable monogra])h of Straus-
Diirckhcim represents the next step in the development of
insect anatomy toward the position that it occupies to-day.
His aim is clearly indicated in the opening sentence of his
preface; "Having been for a long time occupitfl with the
study of articulated animals, I propose to publish a general
work upon the comparative anatomy of that branch of the
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9° BIOLOGY AND ITS MAKl-.RS
animal kingdom." He was workin;.^ under ihc inlluencf of
Cuvitr, who, sonic years earlier, liad foundwl Ihe scienctr of
com|aralive anatomy and whom he recognizwi as his f;reat
exemplar. His work is dcdicale-d to Cuvier, and is accom-
. 1683-1
panie<i by a letter to that fxrv:u anatomist expri-^sinf^ lii
thanks for en co Lira Yemeni and asM>tame.
Straus- Diircklieim liyc^o-iSI)^) intended that the j;eiuni
Consi<lerations >i!i«ii!d be ihe chief fi-;ilure of his mono^^a|ll^
but Ihey failed in this particular because, with (he furihe
developments in anatomy, iiicludiiii^ embiyolo^y and Ui
cell-thwr)-, his general di^cu-si(^ns reganling the artitulatii
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PROGRESS OF MINUTE ANATOMY 99
animals became obsolete. The chief value of his work now
lies in what he considered its secondary feature, viz., that of
the detailed anatomy of the cockchafer, one of the common
beetles of Europe, Owing to changed conditions, therefore,
it takes rank with the work of Malpighi and Lvonct, as a
monograph on a single form. Originally he had intended
to publish a series of monographs on the structure of insects
typical of the different families, but that upon the cockchafer
was the only one completed.
Comparison with the Sketches of Lyonet. — ^The quality
of this work upon the anatomy of the cockchafer was excel-
lent, and in 1824 it was accepted and crowned by the Royal
Institute of France. The finely lithographed plates were
prepared at the expense of the Institute, and the book was
published in 1828 with the following cumbersome title: Con-
sidiraiions G^vSrales sur I'Aiuilomie compares des Animaitx
ArlkuUs auxquelles on a joint I'Aiialomie Descriptive du
Melolontha Vulgaris (Hanneton) donnie comme example de
rOrganisalion des CoUopiire'i. The log sketches with which
the plates are adorned are very beautiful, but one who com-
pares his drawings, figure by figure, with those of Lyonet
can not fail to see that those of the latter are more detailed
and represent a more careful dissection. One illustration
from Slraus-Durckheim will suflicc to bring the achievements
of the two men into comparison.
Fig. 30 shows his sketch of the anatomy of the central
ner\-ous system. He undertakes to show only the main
branches of the nerves going to the different segments of the
body, while Lyonet brings to view the distribution of the
minute terminals to particular muscles. Comparison of other
figures — notably that of the dissection of the head--will
bring out the same point, viz., that Lyonet was more detailetl
than Straus-Durckhcim in his explorations of the anatomy of
insects, and fully as accurate in drawing what he had seen.
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lOO BIOLOGY AND ITS MAKERS
Nevertheless, the work of Straus-Durckheim is conceived
ill a (iitTerent spirit, and is the first serious attompl to make
insect anatomy broadly comparative.
Comment. — Such researches as those of Swamnierdam,
Lyonct, and Slraus-Durckhcim reprt-sent a phase in the
progress of the study of nature. Perhaps their chief value
lies in the fact thai ihey embody the idea of critical obsena-
tion. As examples of faithful, accurate obsenations the re-
searchi-s helped to bring about that close study which is our
only means of gelling at basal facts. These men were all
enlistwl in the crusade against superficial obsen'alion. This
had to have iis beginning, and when we witness it in its i-arly
stages, before the researches have become illuminated by great
ideas, the prodigious effort involvwi in the detailed researchc's
may seem to be iKX>rly expended labor. Nevertheless, though
the writings of these pioneers have become obsolete, their
work was of im|K)rtance in helping to lift observations ujKin
nature to a higher level.
Dufour. — Lfon Dufour exlende<i the work of Stnius-
Diirckheim by publishing, between i8_^i and 1834, rL-si-arches
ujKjn the anatomy and physioiog)' of different families of
insects. His aim was to found a general science of insect
anatomy. That he was unsuccessful in accomplishing this
was owing partly to the absence of embryology' and histology
from his method of study.
Newport. — The thing most needed now was not griater
devotion to details and a willingness to work, bui a broaden-
ing of the horizon of ideas. This arrived in the Englishman
Newjwrt, who was remarkable not only for his skill as a
dissector, but for his recognition of the imjxirtance of einbn,--
ologj' in eluci<laiing the problems of sinicture. His article
"Insecia" in Todd's Cyrhpa-dt'a 0} Analomy and Physiol-
ogy, in 1841. and his ]Kipers in the I'ltilo.topliical Transar
lions of the Royal Society contain this new kind of rest-sirch.
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Diirckheim's Monugrapli, 1818,)
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102 BIOLOGY AMD ITS MAKERS
Von Bucr had founded cmbnology b)' his great work on ihe
devclopmenl of animals in 1828, before ihe investigations of
Dufour, but it was rcser\-e<i for Xe\viK)rt to recognii'ic its
grrat imi)orlance and to apply it lo insect anatomy. He saw
cUurly that, in order to comprehend his problems, the anat-
omist must takcinio account the processof building the body,
as well as ihe complcttil architecture of the adult. The in-
Iroduclion of this Lm]X)rtant idea made his achievement a
distinct advance beyond that of his predecessors.
Leydig, — Just as \ew}>ort was publishing his conclusions
the cell-lheory was established (in 1838-39); and this was
destined to furnish the basis for a new advance. The in-
lluencc of the doctrine that all tissues are conijxjsed of similar
vital units, ralletl cells, was far-reaching. Investigators began
lo apply Ihe idea In all directions, and there resulti.-d a new
dejjartmcnl of anatomy, called histologj'. The subject of
insect histology was an unworked field, but manifc-stl)' one
of imponance. Franz Leydig {for portrait see p. 175)
entered the new terriiory with enthusiasm, and through his
cMcnsive invc-siigations all structural studies ujxin insects
assumed a new aspect. In 1864 ap[>cared his Votti Ban iles
Thierclmt Korpcrs, which, together with his spc-cial articles,
created a new kind of insect anatomy based ujxjn the micro-
scopic study of tissues. The application of this method of
investigation is easy lo see; just as it is impossible to under-
stand the working of a machine without a knowkflge of its
construction, so a knowk-dgc of the working units of an organ
is necessarj* lo comprehend its action. For illustration, it is
perfeclly evident that wc can not understand what is taking
place in an orgiin for receiving sensory impressions without
first understanding its mechanism and the nature of the
connections between it and the central [»art of the nervous
system. The sensor}' organ is on Ihe surface in onler more
ri'adily to receive impressions from the outside world. The
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PROGRESS OF MINUTE ANATOMY 103
sensory cells are also modifications of surface cells, and, as
a. preliminary step to understanding their particular office,
we must know the line along which they have become modi-
fied to fit them to receive stimulation.
Then, if we attempt to follow in the imagination the way
by which the surface stimulations reach the central nervous
system and affect it, we must investigate all the connections.
It thus appears that we must know the intimate structure of
an organ in order to understand its physiology, Leydig
supplied this kind of information for many organs of insects.
In his investigations we see the foundation of that delicate
work u[K)n the microscopic structure of insects which is still
going forward.
Summary. — In this brief sketch we have seen that the
study of insect anatomy, beginning with that of Malpighi
and Swammerdam, was lifted to a plane of greater exactitude
by Lyonet and Straus-Diirckheim. It was further broadened
by the researches of Dufour, and began to take on its modem
aspects, first, through the labors of Newport, who introduced
embryology as a feature of investigation, and, finally, through
Leydig's step in introducing histology. In the combination
of the work of these two observers, the subject for the first
time reached its proper position.
The studies of minute structure in the se\'enteenth and
eighteenth centuries were by no means confined to insects;
investigations were made upon a number of other forms.
Trcmbley, in the time of Lyonet, produced his noteworthy
memoirs upon the small fresh-water hydra (Mimoires pour
servir a rhisloire des polypes d'eau douce, 1744); the illustra-
tions for which, as already staled, were prepared by Lyonet.
The structure of snails and other moUusks, of tadpoles, frogs,
and other balrachia, was also investigated. \Ve have seen
that Swammerdam, in the seventeenth century, had begun
obscn*alions upon the anatomy of tadpoles, frogs, and snails,
;dbyGOOglC
104 BIOLOGY AND ITS MAKERS
and also upon the minute cnislacea commonly called walcr-
fleas, which are just large enough to be distinguished by the
unaided eye. We should remember also that in the same
period the microscopic structure of plants began to be inves-
tigated, notably by Grew, Malpighi, and Lecuwenhock (sec-
Chapter IV).
In addition to those essays into minute anatomy, in which
scalpel and scissors were employal, an endeavor of more
subtle difficulty made its appc-al ; there were forms of animal
life of still smaller size and simpler organization that began
to engage the attention of microscopists. .\ brief account of
the discovery and subsequent observation of these micro-
scopic animalcula will now occupy our attention.
The Discovery of the Simplest Animals and the Prog-
ress OF Observations upon Them
These single-celled animals, since 1845 called proiozoii,
have become of unusual interest to biologists, because in them
the processes of lite are reduced to their simplest cxprc-ssion.
The vital activities taking place in the bodies of higher animals
are too complicated and too intricately mixed to admit of
clear analysis, and, long ago, physiologists ieame<l that the
quest for explanations of living activities lay along (he line
of investigating them in their most rudimentary expres-sion.
The practical recognition of this is seen in our recent text
books upon human physiology, which commonly begin with
discussions of the life of these simplest organisms. That
greatest of all textbooks on general physiology, written by
Max Vcrwom, is devoted largely to experimental studies
upon these simple organisms as containing the key to llie
similar activities (carried on in a higher degree) in higher
animals. This group of animals is so important as a field
of experimental observation thai a brief account of lluir
;dbyGOOglC
DISCOVERY OF THE PROTOZOA 105
cry and the progress of knowledge in reference to them
will be in place in ihis chapter.
Discovery of the Protozoa. — Leeuwenhoek left so little
unnoticed in the microscopic world that wc are prepared to
find thai he made the first recorded observations upon these
animalcula. His earliest obser^'ations were communicated
by letter to the Royal Society of London, and were published
in their Transactions in 1677. It is verj' interesting to read
his descriptions expressed in the archaic language of the time.
The following quotation from a Dutch letter turned into
English will suffice to give the flavor of his wriling:
"In the year 1675 I discovered living creatures in rain-
water which had stood but four days in a new earthen pot,
glazed blew within. This invited me to view the water wilh
great atlenlion, especially those little animals appearing to
me ten thousand times less than ihose represented by Mons.
Swaramerdam, and by him called water-fleas or water-lice,
which may be perceive*! in the water with the naked eye.
The first sorte by me discovered in the said water, I divers
times obsened to consist of five, six, seven or eight clear
globules, without being able to discover any film that held
them together or contained them. When these animaUula,
or living atoms, did move they put forth two little horns,
continually moving themselves; the place between these
two horns was flat, though the rest of the body was roundish,
sharpening a little towanls the end, where ihcy had a tayle,
near four times the length of the whole body, of the thick-
ness (by my microscope) of a spider's web; at the end of
which appeared a globule, of the bigness of one of those
which made up the body; which layle I could not perceive
even in very clear water to bo mov'd by ihem. These little
creatures, if they chanced to light upon the least filament
or string, or olhcr such particle, of which there are many in
the water, especially after it has stood some days, they stook
;dbyGOOglC
Io6 BIOLOGY AND ITS MAKERS
entangled therein, extending their body in a long round, and
striving to dis-entangle their tayle; whereby it came to pass,
that their whole body lept back towards the globule of the
tayle, which then rolled together serpent -like, and after the
manner of copper or iron wire, that having been wound
around a stick, and unwound again, retains those v.indings
and turnings," etc.*
Any one who has examined under the microscope the well-
known bell -animalcule will recognize in this first description
of it, the stalk, and its form after contraction under the desig-
nation of a ' tayle which retains those windings and turnings.'
There are many other descriptions, but the one given is
typical of the others. He found the little animals in water,
in infusions of pepper, and other vegetable substances, and
on that account they came soon to be designated infusoria.
His obsenations were not at first accompanied by sketches,
but in 1711 he sent some drawings with further descriptions.
0. Fr. HiiUer. — These animalcula became favorite ob-
jects of microscopic study. Descriptions began to accu-
mulate and drawings to be made until it became evident that
there were many different kinds. It was, however, more
than one hundred years after their discovery by Lecuwenhoek
that the first standard work devoted exclusively to these
animalcula was published. This treatise by O. Fr. Mullcr
was published in 1786 under the tille of j4«inia/cij/a Injusoria.
The circumstance that this volume of quarto size had 367
pages of description with 50 plates of sketches will give some
indication of the number of protozoa known at that time,
Ehrenberg. — Obscnations in this domain kept accu-
mukting, but the next publication necessary to mention is that
of Ehrenberg (1795-1876). This scientific traveler and
eminent obscr\-er was the author of several works. He was
;dbyGOOglC
DISCOVERY OF THE PROTOZOA lO?
one of the early observers of nerve fibres and of many other
structures of the animal frame. His book of the protozoa
is a beautifully illustrated monograph consisting of 532 pages
of letterpress and 69 plates of folio size. It was published in
1836 under the German title of Die Injusionslhierchen ah
Vollkommene Organhmen, or " Tlic Infusoria as Perfect Or-
ganisms." The animalcula which he so faithfully represented
in his sketches have the habit, when feeding, of taking into
(he body collections of food-j^articles, aggregated into spher-
ical globules or food vacuoles. These are distinctly sepa-
rated, and slowly circulate around the single-ceiled bodywhilc
they are undergoing digestion. In a fully fed animal these
food-vacuoles occupy different positions, and are enclosed in
globular spaces in the protoplasm, an adjustment that gave
Ehrenberg the notion that the animals jmsscsscxl many
stomachs, .\ccordingly he gave to them the name " Poly-
gastrica," and assigned to them a much higher grade of
organization than they really possess. These conclusions,
based on the general arrangement of food globules, seem
very curious to us to-day. His publication was almost simul-
taneous with the announcement of the cell-theory (1838-39),
the acceptance of which was destined to overthrow his con-
ception of the protozoa, and lo make it clear that tissues and
organs can belong only to multicellular organisms.
Ehrenberg (Fig. 31) was a man of great scientific attain-
ments, and notwithstanding the groli-squeness of some of his
conclusions, was held in high esteem as a scientific investi-
gator. His obser\'ations were accurate, and the beautiful
figures with which his work on the protozoa is embellished
were executed with such fidelity reganling fine points of
microscopic detail that they are of value to-c!ay.
Dujaniin, whom we shall soon come to know as llic dis-
coverer of protoplasm, successfully combated the conclusions
of Ehrenberg regarding the organization of the protozoa.
;dbyGOOglC
i<» BIOLOGY AND ITS MAKERS
For a time the great German scientist tried to maintain his
point, that the infusoria have many stomachs, but this was
completely swept away, and hnally the contention of Von
Siehold was adopted to the effect that these animals are each
composed of a single cell.
In 1845 Stein is engrossed in proposing names for the
suborders of infusoria l>ascd upon the distribution of cilia
Fig.
-Kim
1705-1876.
upon their bodies. This sim[)k' method of classification, as
welt as the nanus inlnxliiced by Stein, is ^lill in use.
From Stein to Htitschli, one of the present authorities on
the group, ihcrc were many workers, but with the studii's of
BUlschli on proiozoa we enter the modem ei)och.
The imi»ortance of these animals in afforrling a field for
experimental ion on the simplest expressions of life has
;dbyGOOglC
DISCOVERY OF THE PROTOZOA leg
already been indicated. Many interesting problems iiave
arisen in conneclion with recent studies of them. The
group embraces the ver)' simplest manifestations of animal
life, and the experiments upon the different forms light the
way for studies of the vita! activities of thehigheranimals.
Some of the protozoa are disease-producing; as the microbe
of malaria, of the sleeping sickness, clc, while, as is well
known, most diseases that have been traced to specific germs
are caused by plants — the bacteria. Many cxperimenls of
Maupas, Calkins and others have a bearing upon the dis-
cussions regarding the immortality of the protozoa, an idea
which was at one time a feature of Weissmann's ihcorj' of
heredity. Binet and others have discussed the evidences of
]>sychic life in these micro-organisms, and the daily activity
of a protozoan became the lield for observation and record
in an American laboratorj' of psychology. The extensive
studies of Jennings on the nature of their responses to stim-
ulations form a basis for some of the discussions on animal
behavior.
;dbyGOOglC
CHAPTER VI
LINN-tlS AND SCIEXrrFIC NATl-RAL HISTORY
We turn now from the purely anaiomlcai ~kte to cwisKier
the paiallel development of ihe da^^mcatioa ot amnxiis and
of [dants. Descriptive natural hi^ton' reached a verv' low
Icvd in the early Christian centuries, and remained there
throu^oul the Middle Ages. The return to the writings of
.\ristotle «-as the first inSumce tending to lift it to the position
from which it had faDen. .-Vfter the decline of ancient civili-
zalicHi there was a period in which the writerj of classical
antiquity were not read. Not only were the v.Titings of the
ancient philosophers ne^ectcd, but so also were ihote of the
litciaiy tnen as well, the poets, the story-tellers, and the his-
lorianK. .\s relatwl in Chapter 1, there were Poobscr\ations
(rf animatetl riature, and the growing tendency of ihe educaifd
classes to envelop then^selves in metaphvjical >{H.cu!alions
wa-s a feature of inielktHial life.
The Physiologus or Sacred Natural History. — During this
[KTiod of cnidi; fancy, with a fog of mysticism obscuring all
phenomena of nature, there existctl a peculiar kind of natural
hiHtor)' Ihal wa:^ prfxlucttl under thtoiogical intluence. The
tnanusrripls in which this sacred natural hislon.- v.as em-
UkUhI exist in various forms and in about a dozen languages
of Kistern and Western Kurope. The writings are known
under ihi- general liilc of the I'hysiologus, or the Bestiarius.
This served tor niiirly a thousand years as the princi]);d
wnirce of ilioughl regarding natural hislor\*. It contains
;dbyGOOglC
LINN^US AND NATURAL HISTORY "i
accounts of animals mentioned in the Bible and others of a
purely mythical character. These are made to be symbolical
of religious beliefs, and are often accompanied by quotations
of texts and by moral reflections. The phcenix rising from
its ashes typifies the resurrection of Christ. In reference to
young lions, the Pbysiologus says: "The lioness giveth birth
to cubs which remain three days without life. Then cometh
the lion, breatheth upon them, and bringeth them to life. . . .
Thus it is that Jesus Christ during three days was deprived
of life, but God the Father raised him gloriously." (Quoted
from White, p. 35.) Besides forty or fifty common animals,
the unicorn and the tlragon of the Scriptures, and the fabled
basilisk and phcenix of secular writings are described, and
morals are drawn from the stories about them. Some of the
accounts of animals, as the lion, the panther, the serpent, the
v.casel, etc., etc., are so curious that, if space permitted, it
would be interesting to quote them ; but that would keep us
too long from following the rise of scientific natural history
from this basis.
For a long time the religious character of the contempla-
tions of nature was emphasized and the prevalence of theo-
logical influence in natural history is shown in various titles,
as Lcsser's Theology of Insects, Swammerdam's Biblia
NalurtE, SjKiIlanzani's Tracts, etc,
The zoQlogy of the Physiologus was of a much lower grade
than any we know about among the ancients, and it is a
curious fact that progress was made by returning to the
natural history of fifteen centuries in the past. The transla-
tion of Aristotle's writings upon animals, and the disposition
to read them, mark this advance. When, in the Middle
Ages, the boundaries of interest began to be extended, it
came like an entirely new disco\'cry, to find in the writings
of the ancients a storehouse of philosophic thought and a
higher grade of learning than that of the period. The
;dbyGOOglC
112 BIOLOGY AND ITS MAKERS
translation and recopying of the writers of classical anliquity
was, therefore, an important step in ihe revival of learning.
These writings were so much above the thought of the time
that the belief was naturally created that the ancients had
digested all learning, and they were pointed to as unfailing
authorities in matters of science.
The Return to the Science of the Ancients. — The return to
Aristotle was wholesome, and under its influence men turned
their attention once more to real animals. Comments upon
Aristotle began to be made, and in course of time independent
treatises upon animals began to appear. One of the first to
modify Aristotle to any purpose was Edwanl W'otton, the
English physician, who published in 1552 a book on the dis-
tinguishing characteristics of animals (De DifferenlHs Ani-
maiium). This was a complete treatise on ihe zoology of
the period, including an account of the different races of
mankind. It was beautifully printed in Paris, and was
dedicated to Edwartl VI. Although embracing ten books,
it was by no means so ponderous as were some of the treatises
that followed it. The work was based ujxjn Aristotle, but
the author introduced new matter, and also added llic group
of zoophytes, or plant-like animals of the sea.
Gesner.^The next to reach a distinctly higher plane was
Conrad Gesner (1516-1565), the Swiss, who «-as a contem-
porary of Vcsalius. He was a practising physician wlio, in
1553, was made professor of natural history in Zurich. \
man of extraordinaiy talent anil learning, he turned out an
astonishing (]uanlity of work. Besides accomplishing much
in scientific lines, he translated from Greek, .\rabic, and
Hebrew, and published in twenty volumes a uni\*ersal cat-
alogue of all works known in Latin, Greek, and Hcbri-w,
either prinlcd or in manuscript form. In the domain of
natural history- he began to look critically at animals wiih a
view lo describing them, and to collect with i^calous care new
;dbyGOOglC
LINN^US AND NATURAL HISTORY "3
observations upon their habits. His great work on natural
history (Hisloria Aninialium) began to appear in 1551, when
he was thirty-five years of age, and four of the five volumes
were published by 1556. The fifth volume was not pub-
lishel until 1587, twenty-two years after his death. The
complete work consists ofabout "41500 folio pages," profusely
illustrated with good figures. The edition which the writer
has before him^that of 1585-1604 — embraces 3,200 pages
of text and 953 figures.
Brooks says: " One of (lesner's greatest services lo nat-
ural science is the introduction of good illustrations, which he
gives his reader by hundreds." He was so exacting about
the quality of his illustrations that his critical supenision of
the work of artists and engravers had its influence upon con-
temporary art. Some of the best woodcuts of the period arc
found in his work. His friend Albrccht Diirer supplied one
of the originals — the drawing of the rhinoceros — and it is
interesting to note ihat it is by no means ihc bL'st, a circum-
stance which indicates how effectively Gesner held his en-
gravers and draughtsmen up to fine work. He was also care-
ful to mold his writing into graceful form, and this, combined
with the illustrolions, "made science attractive without sac-
rificing its dignity, and thus became a great educational
influence."
In preparing his work he sifted ihe writings of about two
hundrc'd and fifty authors, and while his book is largely a
compilation, it is enriched with many obsen'ations of his own.
His descriptions arc verbose, but discriminating in separating
facts and observations from fables and speculations. He
could not eniircly escape from old traditions. There are re-
tained in his book pictures of the sea-serpeni, the mermaids,
and a few other fanciful and grotesque sketches, but for the
most part the drawings are made from the natural objects.
The descriptions are in several parts of his work alphabet!-
;dbyGOOglC
"4 BIOLOGY AND ITS MAKERS
cally arranged, for convenience of reference, and thus ani-
mals thai were closely related are often widely separated.
Gesner (Fig. 32) sacrificed his life to professional zeal
during the prevalence of the plague in Zurich in 1 564. Hav-
ing greatly overworked in the care of the sick, he was seized
with the disease, and died at the age of forty-nine.
Considered from the standpoint of descriplions and illus-
trations, Gcsner's Hisloria Animalium remained for a long
Fig
2,— Ge!
time the best work in zoologj. He was the best zoologist
between Aristotle and John Ray, the immc-<liate predecessor
of Linnaeus.
Jonston and Aldrovandi. — -At about the same period as
Gesner's work there a|)peari'd two other voluminous publica-
tions, which are well known — those of Jonston, the Scot
;dbyGOOglC
LINN.EUS AND NATURAL HISTORY "S
{Historia Animaiium, 1 549-1 353), and Aldrovandi, the
Italian {Opera, 1599-1606). The former consisted of four
folio volumes, and the latter of thirteen, of ponderous size,
to which was added a fourteenth on plants. Jonston's works
were translated, and were better known in England than those
of Gesner and Aldrovandi. The wood -engravings in Aldro-
vandi's volume are coarser than those of Gesner, and are by
no means so lifelike. In the Institute at Bol<^na are pre-
ser\ed twenty volumes of figures of animals in color, which
were the originals from which the engravings were made.
These are said to be much superior to the reproductions.
The encyclopedic nature of the writings of Gesner, Aldro-
vandi, and Jonston has given rise to the convenient and
expressive title of the encyclopaxlists.
Ray. — John Ray, the forerunner of Linnxus, built upon
the foundations of G esner and others, and raised the natural-
history edifice a tier higher. He greatly reduced the bulk
of publications on natural history, sifting from Gesner and
Aldrovandi their irrelcvancies, and thereby giving a more
modem tone to scientific writings. He was the son of a
blacksmith, and was bom in southem England in 1628.
The original form of the family name was Wray. He was
graduated at the University of Cambridge, and became a
fellow of Trinity College. Here he formed a friendship with
Francis WiUughby, a young man of wealth whose tastes for
natural history were like his own. This association proved
a happy one for both parlies. Ray had taken orders in the
Church of England, and held his university fiosition as a
cleric; but, from conscientious scniples, he resigned his
fellowship in 1662, Thereafter he received financial assist-
ance from Willughby, and the two men traveled extensively
in Great Britain and on the Continent, with the view of inves-
tigaling the natural history of the places that they visited.
On these excursions Willughby gave particular attention to
;dbyGOOglC
ii6
BIOLOGY AND ITS MAKERS
animals and Ray to plants. Of Ray's several publications
in botany, his Hisloria Plantarum in three volumes (1686-
1704) is the most extensive. In another work, as early as
1682, he hail proposed a new classification of plants, which
Fio .1.1
in the next century was adojrted by Jussieu, and which gives
Ray a place in the histon,- of botany.
Willughby die<l in i66a, at (he age of thiny-eight, leaving
an annuity to Ray, and charging him with the e<lucalion of
;dbyGOOglC
LINNvEUS AND NATURAL HISTORY 11?
his two sons, and ihc editing of his manuscripts. Ray per-
formed these duties as a faithful friehd and in a generous
spirit. He edited and published Willughby's book on birds
{1678) and fishes ( 1686) with important additions of his own,
for which he sought no credit.
.\ftcr completing his tasks as the lilerarj- executor of Wil-
lughby, he returned in 1678 to his birthplace and continued
his studies in natural history. In 1691 he published "The
Wisdom of God manifested in llie Works of the Creation,"
which was often reprinted, and became the forerunner of the
works on natural theology like I'aley's, etc. This was an
amplification of ideas he had emixxiiefl in a sermon thirty-
one years earlier, and which at that time attracted much
notice. He now devoted himself largely to the study of ani-
mals, and in 1693 published a work on the quadrupeds and
stTpents, a work which gave him high rank in the history' of
the classification of animals. He died in 1705, but he had
accomplished much good work, and was not forgotten. In
1 844 there was founded, in London, in his memor\', the Ray
Society for the publication of rare books on botany and
^.oology,
Ray's Idea of Species. ^One of the features of Ray's
work, in the light of subsequent development, is of special
interest, and that is his limiting of species. He was the first
to introtluce into natural historj- an e.\act conception of
species. Before his time the wort] had been used in an
indefinite sense to embrace groups of greater or less extent,
but Ray applied it to individuals derived from simihr ]>ar-
ents, thus making the term species stand for a jtarticular kind
of animal or plant. He nole<J some variations among species,
and did not assign to them that unvarying and constant char-
acter ascribed to them by l.inna:us and his followers. Ray
also made use of anatomy as the foundation for zoological
classification, and introduced great precision and clit
;dbyGOOglC
into his definitions of gpups '^£anjj)ials and plants. In the
particulars indicated aiove he represents a great advance
beyond any of his precursors, and marks the parting of the
ways between medieval and mwiem natural history.
In Germany Klein (1685-1759) elaborated a system of
classification embracing the entire animal kingdom. His
studies were numerous, and his system would have been of
much wider influenceJn molding natural history had it not
been overshadowed by^hift irXiinfetfe:
Linneeus or Linne. — The'service of Linnaeus to naturaN
history was unique. The large number of specimen^fil
animals and plants, e\'er increasing through the collections
of travelers and naturalists, were in a confused state, and
there was great ambiguity arising from the lack of a method-
ical way of arranging and naming them. They were known
by verbose descriptions and local names. No scheme had
as yet been devised for securing uniformity in applying names
to them. The same animal and plant had different names
in the different sections of a country, and often different
plants and animals had the same name. In different coun-
tries, also, their names were greatly diversified. What was
especially needed was some great organizing mind to cata-
logue the animals and plants in a systematic way, and to give
to natural science a common language. Linnieus possessed
this methodizing mind and supplied the need. While he did
little to deepen the knowledge of the organization of animal
and plant life, he did much to extend the number of known
forms; he simplified the problem of cataloguing them, and he
invented a simple method of naming them which was ado])ted
throughout the world. By a happy stroke he gave to biology
a new language that remains in use to-day. The tremendous
influence of this may be realized when we remember that
naturalists everywhere use identical names for the same
animals and plants. The residents of Japan, of Italy, of
;dbyGOOglC
LINN^US AND NATURAL HISTORY "9
Spain, of all the world, in fact, as was just said, employ the
same Latin names in classifying organic forms.
He also inspired many students with a love for natural
history and gave an impulse to the advance of that science
which was long felt. We can not gainsay that a higher class
of ser\'ice has been rendered by those of philosophic mind
devoted to the pursuit of comparative anatomy, but the step
of Linnaeus was a necessary one, and aidid greatly in the
progress of natural history. Without this step the discoveries
and observations of others would not have been so readily
understood, and had it not been for his organizing force all
natural science would have been held back for want of a
common language. A close scrutiny of the practice among
naturalists in the time of Linnaeus shows that he did not
actually invent the binomial nomenclature, but by adopting
the suggestions of others he elaborated the system of classifi-
cation and brought Ihe new language into common use.
Personal History. — Leading for the present the system of
Linn<eus, we shall give attention to the personal history of
the man. The great Swedish naturalist was bom in Rashult
in 1 707. His father was the pastor of the village, and intended
his eldest son, Carl, for the same high calling. The original
family name was Ignomarsen, but it had been changed to Lin-
dclius, from a tall linden-tree growing in that part of the coun-
try. In 1761 a patent of nobility was granted by the crown
to Linn.eus, and thereafter he was styled Carl von Linn^.
His father's resources were very limited, but he man-
aged to send his son to school, though it must be confessed
that young Linna;us showed little liking for the ordinary
branches of instruction. His time was spent in collecting
natural-historj- specimens, and his mind was engaged in
thinking about them. The reports of his low scholarship
and the statement of one of his teachers that he showed no
aptitude for learning were so disappointing to his father that,
;dbyGOOglC
120 BIOLOGY AND ITS MAKERS
in 1726, he prepared to apprentice Carl to a shoemaker, but
was prevented from doing so through the encouragement
of a doctor who, being able to appreciate the quality of mind
possessed by the young I.inna;us, ad\ised allowing him to
study medicine instead of preparing for theology.
Accordingly, with a sum amounting to about S40, all his
father could spare, he set off for the Univcrsily of Lund, to
pursue the study of medicine. He soon transferred to the
Universityof Upsala, where the advantages were greater. His
povertyplaced himunder thcgrcalest sirails for the necessities
of life, and he enjoyed no luxuries. While in the university
he mended his shoes, and the shoes which were given to him
by some of his companions, with paper and bircJi-bark, to
keep his feet from the damp earth. But his means did not
permit of his taking his degree at Upsala, and it was not until
cightyears later, ini735, that he received his degree in Holland.
At Upsala he was relieved from his extreme poverty by
obtaining an assistant's position, and so great was his knowl-
edge of plants that he was delegated to read the lectures of
the aged professor of botany, Rudbeck.
In 1732 he was chosen by the Royal Socielj' of Upsala to
visit Lapland as a collector and observer, and left the univer-
sity without his degree. On returning to Upsala, his lack
of funds made itself again ]«infully felt, and he undertook
to supfxirt himself by giving public leciuren on botany, chem-
istry, and mineralogy. He secured hearers, but the con-
tinuance of his lectures was prevented by one of his rivals on
the ground that Linnseus had no degree, and was therefore
legally disqualified from taking pay for instruction. Pres-
ently he became tutor and traveling companion of a wi'althy
baron, the governor of the province of Dalecarlia, but this
employment was temi)onin,-.
Helped by His Fiancee. — His friends advised him 10
secure his medical degree and settle as a practitioner. Al-
;dbyGOOglC
LINN./EUS AND NATURAL HISTORY 121
ihoiigh he larked the ncccssarv funds, one circumstance con-
tributt-d to bring about this end: he had formed an attach-
ment for ihc daughter of a weahhy physician, named More
or Mortcus, and on applying for her hand in marriage, her
father made it a condition of his consent that Linnaeus should
take his medical degree and establish himself in the practice
of medicine. The young lady, who ivas thrifty as well as
handsome, offered her savings, amounting to one hundred
dollars (Swedish), to her lover. He succec<led in adding to
this sum by his own exertions, and with ihirty-six Swedish
ducats set off for Holland to qualify for his degree. He had
practically met ihe requirements for the medical degree by
his previous sludies, and after a month's residence at the
University of Hardcwyk, his thesis was accepted and he was
granted the degree in June, 1735, in the twenty-eighth year
of his age.
Instead of returning at once to Sweden, he went to
Leyden, and made the aciiuainlancc of several well-known
scientific men. He continued his botanical studies with great
cncrg)\ an<l now began to reap the benefits of his earlier
demotion to natural historj'. His heart-breaking and harass-
ing straggles were now o\-er.
The Systema Hatune. — He had in his possession the
manuscri])t of his Syslcnia Nalurff, and with the encourage-
ment of his new friends it was published in the same year.
The first edition (1735} of that notable work, which was
aftenvarri to bring him so much fame, consisted of twelve
printer! folio j^igcs. It was merely an outline of the arrange-
ments of plants, animals, and minerals in a methodical cat-
alogue. I'his work passed through twelve editions during
his lifetime, Ihc last one ap])caring in 1768. .After the first
edition, the books were printed in octavo form, and in the
later editions were greatly enlarged. A copy of the first
edition was sent to Bocrhaave, the most distinguished pro-
id byGoOglc
122 BIOLOGY AND ITS MAKERS
fcssor in the University of Leyden, and secured for Linnaeus
an interview with that distinguished physician, who treated
him with consideration and encouraged him in his work.
Boerhaave was already old, and had not long to live; and
when Linnffius was about to leave Holland in 1738, he ad-
mitted him to his sick -chamber and bade him a most affec-
tionate adieu, and encouraged him to further work by most
kindly and appreciative expressions.
Through the influence of Boerhaave, Linnxus became the
medical attendant of Cliffort, the burgomaster at Amsterdam,
who had a large botanic garden. Cliffort, being desirous of
extending his collections, sent Linnseus to England, where
he met Sir Hans Sloane and other eminent scientific men of
Great Britain. Mter a short period he returned to Holland,
and in 1737 brought out the GcMcroi'/antorMm, a very original
work, containing an analysis of all the genera of plants. He
had previously published, besides the Systema Natura;, hb
Fundamenla Bolanica, 1735, and Bibliolheca Botanica, 1736,
and these works served to spread his fame as a botanist
throughout Europe.
His Wide Recognition. — An illustration of his wide rec-
ognition is afforded by an anecdote of his first visit to Paris
in 1738. "On his arrival he went first to the Garden of
Plants, where Bernard dc Jussieu was describing some
exotics in Latin. He entered without opportunity to intro-
duce himself. There was one plant which the demonstrator
had not yet determined, and which seemed to puzzle him.
The Swede looked on in silence, but observing the hesitation
of the learned professor, cried out 'Hac plania jacicm Ame-
rkanam kabcl.' 'It has theappearanceof an American plant.'
Jussieu, surprised, turned about quickly and exclaimed 'Vou
arc Einnxus.' 'I am, sir,' was the reply. The lecture was
stopped, and Bernard gave the learned stranger an affec-
tionate welcome."
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LINN^US AND NATURAL HISTORY 123
Return to Sweden. — After an absence of three and one-
half years, Linnieus returned to his native countrj' in 1 738, and
soon after was married to the young woman who had assisted
him and had waited for him so loyally. He settled in Stock-
holm and began the practice of medicine. In the period of
his absence he had accomplished much : visited Holland,
England, and France, formed the acquaintance of many
eminent naturalists, obtained his medical degree, published
numerous works on botany, and extended his fame over all
Europe, In Stockholm, howwer, he was for a time neglected,
and he would have left his native country in disgust had it
not been for the dissuasion of his wife.
Professor in Upsala. — In i 741 he was elected professor
of anatomy in the University of Upsala, but by a happy stroke
was able to exchange that position for the professorship of
botany, materia medica, and natural history that had fallen
to his former rival, Rosen. Linnxus was now in his proper
element; he had opportunity to lecture on those subjects to
which he had been devotedly attached all his life, and he
entered upon the work with enthusiasm.
He attracted numerous students by the power of his per-
sonal qualities and the excellence of his lectures. He became
the most popular professor in the University of Upsala, and,
owing to his drawing power, the attendance at the university
was greatly increased. In 1 749 he had 140 students devoted
to studies in natural history-. The number of students at
the university had been about 500; " whilst he occupied the
chair of botany (here it rose to 1,500." A part of this in-
crease was due to other causes, but Linnxus was the greatest
single drawing force in the university. He was an eloquent
as well as an enthusiastic lecturer, and he aroused great in-
terest among his students, and he gave an astonishing impulse
to the study of natural history in general, and to botany in par-
ticular. Thus Linna'us, after having passed through great
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124
BIOLOGY AND ITS MAKERS
privations in his earlier years, found himself, at the age of
thirty-four, established in a jjosiuon which brought him rec-
ognition, honor, and large emolument.
In May, 1907, the University of Upsala celebrated the
two hundredth anniversary of his binh with appropriate ccr-
Oelegalions of ^cienlillc men from all oxer the
world were in altenilance to do honor to the memory of the
great founder of biologieul nomenclature.
;dbyGOOglC
LINN^US AND NATURAL HISTORY 125
Personal Appearance.— The portrait of Linnaeus al the
age of sixty is shown in Fig, 34. Ho was described as of
" medium height, with large limbs, brown, piercing eyes, and
acute vision." His hair in early youth was nearly white, and
changed in his manhood to brown, and became gray with
the advance of age. Although quick-tempered, he was natu-
rally of a kindly disposition, and secured the affection of his
students, with whom he associated and worked in the most
informal way. His love of approbation was vcri' marked,
and he was so much praised that his desire for fame became
his dominant passion. The criticism to which his work was
subjected from time lo time accordingly threw him into
fits of despondency and rage.
His Influence upon Natural History. — However much we
may admire the industry and force of Linna;us, we must
admit that he gave to natural history a one-sided develop-
ment, in which the more essential parts of the science received
scant recognition. His students, like their master, were
mainly collectors and classifiers. "In their zeal for naming
and classifying, the higher goal of investigation, knowl-
edge of the nature of animals and plants, was lost sight of
and the interest in anatomy, physiology, and embryolog}'
lagged."
R. Hertwig says of him: "For while he in his Syslema
NatuT<e treated of an extraordinarily larger number of ani-
mals than any earlier naturalist, he brought about no deep-
ening of our knowledge. The manner in which he divided
the animal kingdom, in comparison with the Aristotelian
system, is to be called rather a retrogression than an advance.
Linnicus divided the animal kingdom into six classes— Mam-
malia, Avc's, Amphibia, Pisces, Insecta, Vermes. The first
four classes corresjxind to Aristotle's four groups of animals
with blood. In the division of the invertebrated animals into
Insecta :ind \'ermes Linnaeus stands undoubtedly behind
;dbyGOOglC
136 BIOLOGY AND ITS MAKERS
Aristotle, who attempted, and in part indeed successfully, to
set up a larger number of groups,
" But in his successors even more than in Linna;us himself
we sec the damage wrought by the purely systematic method
of consideration. The diagnoses of Linnseus were for the
most part models, which, mulalis mutandis, could be employed
for new species with little trouble. There was needed only
some exchanging of adjectives to express the differences.
With the hundreds of thousands of different species of
animals, there was no lack of material, and so the arena was
opened for that spiritless zo61<^ of species- making, which
in the first half of the nineteenth century brought zoology
into such discredit. Zoology would have been in danger of
growing into a Tower of Babel of species-description if a
counterpoise had not been created in the strengthening of the
physioic^ico-anatomical method of consideration,"
His Especial Service. —Nevertheless, the work of Lin-
nieiis made a lasting impression upon natural history,and wc
shall do well to get clearly in mind the nature of his particular
service. In the first place, he brought into use the method
of naming animals and plants which is employed to-day. In
his Syslema Natura and in other publications he employed
a means of naming every natural production in two words,
and it is therefore called the binomial nomenclature. An
illustration will make this clearer. Those animals which had
close resemblance, like the lion, tiger, leopard, the lynx, and
the cat, he united under the common generic name of Felis,
and gave to each a particular trivial name, or specific name.
TTius the name of the lion became Felis leo, of the tiger Felis
ligriSfOi the leopard Felis pardus, oi thecal Felis calus ; and
to these the modem zoologists have added, making the
Canada lynx Felis Canadensis, the domestic cat Felis domes-
tiiala, etc. In a similar way, ihc dojT-likc animals were
unitixi into a genus designate*! Canis, and the particular
;dbyGOOglC
LINN^US AND NATURAL HISTORY 12?
kinds or species became Canis lupus, the wolf, Cams vulpes,
the fox, Cams jamiliaris, the common dog. This simple
method took the place of the vai7ing names appliefi lo the
same animal in diiTerent countries and local names in the
same country. It recognized at once their generic likeness
and their specific individuality.
All animals, plants, and minerals were named according
to this method. Thus there were introduced into nomencla-
ture two groups, the genus and the species. The name of
the genus was a noun, and' that of the species an adjective
agreeing with it. In the choice of these names Linnaeus
sought to e.tpress some distinguishing feature that would be
suggestive of the particular animal, plant, or mineral. The
trivial, or specific, names were first employed by Linnaeus in
1749, and were introduced into his Species Planiarum in
1753' and into the tenth edition of his Syslema Natura in
1-58.
We recognize Linnseus as the founder of nomenclature in
natural historj', and hy the common consent of naturalists
the date 1758 has come to be accepted as the starting-point
for determining the generic and specific names of animals.
The much vexed question of priority of names for animals is
settled by going back to the tenth edition of his Syslema Na-
/MrflT, while the botanists have adopted his Species Plantarum,
1753, as their base-line for names. As to his larger divisions
of animals and plants, he recognized classes and orders. Then
came genera and species. Linn«:us did not use the term
family in his formulae; this convenient designation was first
used and introduced in 1780 by Batch.
The Syslema Natura is not a treatise on the oi^nizatlon
of animals and plants; it is rather a catalogue of the produc-
tions of nature methodically arranged. His aim in fact was
not lo give full descriptions, but to make a methodical
arrangement.
;dbyGOOglC
128 BIOLOGY A\D ITS MAKERS
To do justice, however, lo Ihe discernment of Linnaeus, it
should be added that he was fully aware of ihc artificial
nature of his classification. As Kemcr has sai'i; "It is not
the fault of this accompli hed and renowned naturalist if a
f!;reater imjxirtance were attached to his system than he him-
self ever intended. Linnieus never regarded his twenty-four
classes as real and natural divisions of the vegetable kinirdom,
and specifically says so; it was constructed for convenience of
reference and identification of species. A real natural system,
founded on the true aflinities of plants as indicate<l by the
structural characters, he regarded as the highest aimof botan-
ical endeavor. He never completed a natural system, leaving
only a fragment (published in 17.^8)."
Terseness of Descriptions. — His descriptions were marked
by extreme brevity, but by great clearness. This is a second
feature of his work. In giving the diagnosis of a form he
was very terse. He did not employ fully formed sentences
containing a verb, but words concisely put together so as to
bring out the chief things he wished lo emphasize. .\s an
illustration of this, wo may lake his characterization of the
fortst rose, " Rosa syheslris vulgaris, jlore odorala incarnalo."
The common rose of the forest with a fiesh -colored, sweet-
smelling flower. In thus fi.xing the attention u|x>n essential
points he got rid of verbiage, a step that was of verj- great
imiK)rtance.
His.Idea of Species.^ — .\ third fealnrc of his work was
that of emphasizing the idea of species. In this he buill
uixjn ihe work of Ray. \Vc have alreach' seen that Kay
was the first lo define sj)C-cies and lo bring the conceplion
into natural hislon,'. Ray had s]ioken of the variability of
species, but Linna-us, in his earlier publications, declared
thai they were constant and invariable. His concept ion of a
specits was that of iri(!ivi<lua!s born from similar parents.
It was assume-cl that at the original stocking of the earth, one
;dbyGOOglC
LINN^US AND NATURAL HISTORY 1*9
pair of each kind of animals was crealed, and that existing
species were the direct descendants without change of form
or habit from the original pair. As to iheir number, he said:
"Species lot sunt, quot Jormm ab initio creala stinl" — there
arc just so many species as there were forms created in the
beginning; and his oft-quoted remark, ".Yw//a species nova,"
indicates in terse language his position as to the formation of
new species. Linn<eus took up this idea as expressing the cur-
rent thought, V,' it liout analysis of what was involved in it. He
readily might have seen that if there were but a single pair
of each kind, some of them must have been sacrificed to
the hunger of the carnivorous kinds; but, better than making
any theories, he might have looked for evidence in nature as
to the fixity of species.
WTiile Linnsus first pronounced upon the fixity of species,
it is interesting to note that his extended observations upon
nature led him to see that variation among animals and plants
is common and extensive, and accordingly in the later editions
of his Systema Natiira we find him receding from the position
that species are fixed and constant. Nevertheless, it was
owing to his influence, more than to that of any other writer
of the period, that the dogma of fixity of species was estab-
lished. His great contemporary BuSon looked upon species
as not having a fixed reality in nature, but as being fig-
ments of the imagination ; and we shall sec in a later section
of this book how the idea of LinnEeus in reference to the
fixity of species gave way to accumulating evidaice on the
matter.
Summary. — The chief services of Linnaeus to natural
science consisted of these three things: bringing into current
use the binomial nomenclature, the introduction of terse
formula- for description, and fixing attention upon species.
The first two were necessary steps; they introduced clearness
and order into the management of the immense number of
;dbyGOOglC
13° BIOLOGY AND ITS MAKERS
details, and they made it possible tor the observations and
discoveries of others to be understood and to take their place
in the great system of which he was the originator. The
effect of the last step was to direct the attention of naturalists
to species, and thereby to pave the way for the coming con-
sideration of their origin, a consideration which became such
a burning question in the last half of the nineteenth century.
Reform of the Linn^an System
Necessity of Reform. — As indicated above, the classifica-
tion established by Linnjeus had grave defects; it was not
founded on a knowledge of the comparative structure of
animals and plants, but in many instances upon superficial
features that were not distinctive in determining their position
and relationships. His system was essentially an artificial
one, a convenient key for finding the names of animals and
plants, but doing violence to the natural arrangement of those
organisms. An illustration of this is seen in his classification
of plants into classes, mainly on the basis of the number of
stamens in the flower,and into orders accord ing to the number
of pistils. Moreover, the true object of investigation was
obscured by the Linna^n system. The chief aim of bio-
logical study being to extend our knowledge of the structure,
development, and physiology of animals and plants as a
means of understanding more about their life, the arrange-
ment of animals and plants into groups should be the out-
come of such studies rather than an end in itself.
It was necessary to follow different methods to bring
natural history back into the line of true progress. The first
modification of importance to the Linna^an system was that
of Cuvicr, who proposed a grouping of animals based upon
a 1-jiowledge of their comparative anatomy. He declared
;dbyGOOglC
LiNN^US AND NATURAL HISTORY 131
ihat animals exhibit four types of organization, and his types
were substituted for the primary groups of Linnieus.
The Scale of Being. — In order to understand the bearing
of Cuvilt's conclusions we must take note of certain views
regarding the animal kingdom that were generally accepted
at the time of his writing. Between Linn;EUs and Cuvier
there had emerged the idea that all animals, from the lowest
to the highest, form a graduated series. This grouping of
animals into a linear arrangement was called exposing the
Scale of Being, or the Scale of Nature (Scaia Nalurte).
Buffon, Lamarck, and Bonnet were among the chief ex-
ponents of this idea.
That Lamarck's connection with it was temporary has
been generally overlooked. It is the usual statement in the
histories of natural science, as in the Encyclopedia Brtlannica,
in the History of Cants, and in Thomson's Science of Life,
that the idea of the scale of nature found its fullest expression
in Lamarck. Thomson says: "His classification (1801-1812)
represents the climax of the attempt to arrange the groups
of animals in linear order from lower to higher, in what was
called a scata natura:" (p. 14). Even so careful a writer as
Richard Hertwig has expressed the matter in a similar form.
Now, while Lamarck at first adopted a linear classification,
it is only a partial reading of his works that will support the
conclusion that he held to it. In his Syslime des Animaux
sans Verlibres, published in 1801, he arranged animals in
this way; but to do credit to his discernment, it should be
observed that he was the first to employ a genealogical tree
and to break up the serial arrangement of animal forms. In
1809, in the second volume of his PkUosophie Zoologique,
as Packard has pointed out, he arranged animals according
to their relationships, in the form of a trunk with divergent
branches. This was no vague suggestion on his part, but
an actual pictorial representation of the relationship between
;dbyGOOglC
1.5- BIOLOGY AND ITS MAKERS
dilTi'rem groujjs of animals, as conceived by him. Although
a crude atlcmpt, it is interesting as being the first o{ its kind.
This is so directly 0|>[)Osed to the idea of scale of being that
we make note of the fact that Lamarck forsook that view at
least twenty ytars before the close of his Ufcand substituted
for it that of the genealogical tree.
Lamarck's Position in Science. — Lamarck is coming into
full recognition for his ]>arl in founding the evolution theorv-,
but he is not generally, as yet, given due credit for his work
in zoolog}-. He was the most philosophical thinker engaged
with zofilogy at Ihc close of the eighteenth and the beginning
of the nineteenth cenlun.-. He was greater than Cuvier in
his reach of inU'llcct and in his discernment of the true
relationshi])s among living organisms. Wc are to recollect
that he forsook the dogma of fixity of species, to which Cuvier
held, ami founded the first comprehensive thcon,- of organic
c\'olution. To-day we can recognize the superiority of his
mental grasp over that of Cuvier, but, owing to the personal
magnetism of the latter and to his position, the ideas of
Lamarck, which Cuvier combated, received but lillle atten-
tion when they were promulgate<l. \\c shall have occasion
in a later chapter to speak more fully of Lamarck's contribu-
tion to the progress of biological thought.
Cuvier's Four Branches. — We now return to the ty[>e-
theory of Cuvier. By extended studies in comjiarative anat-
omy, he came to the conclusion ihal animals are constructed
ujKjn four distinct plans or types: ihe vertebrate type; the
mollu;-can type; ihearticulalcd type, embracing animals with
joints or segments; and the radiated type, the latter with a
radial arrangemenl of [Kirls, like the starfish; etc. These
types are distinct, but their representatives, instead of forming
a linear series, overlap so thai the lowi^st forms of one of the
higher groiijis are simpler in organization than the higher
forms of a lower group. This was ver)' illuminating, and,
;dbyGOOglC
LINN^US AND NATURAL HISTORY ^33
being fountled upon an analysis of structure, was important.
It was directly at variance with the idea of scale of being, and
overthrew that doctrine.
Cuvier first expressed these \iews in a pamphlet published
in 1795, and later in a better-known paper read before the
French Academy in 1812, but for the full development of
his lypc-lheory we look to his great volume on the animal
kingdom published in 1816. The central idea of his arrange-
ment is contained in the secondary title of his book, "The
.A.nin'^! Kingdom Arranged According to its Organization "
(Le R^gne Animal Dislribu£d'apris son Organisation, 1816).
The expression "arranged according to its organization"
embraces the feature in which this analysis of animals differs
from all previous attempts.
Correlation of Parts.— An important idea, first clearly
expresse<l by Cuvier, was that of correlation of parts. The
view that the different parts of an animal are so correlated
thai a change in one, brought about through changes in use,
involves a change in another. For illustration, the cleft hoof
is always associated with certain forms of teeth and with the
stomach of a ruminant. The sliarp claws of flesh-eating
animals arc associated with sharp, rutting teeth for tearing
the tk-sh of the victims, and with an alimentary tube adapted
to the digestion of a fleshy diet. Further account of Cuvier
is resencd for the chapter on the Rise of Comparative Anat-
omy, of which he was the founder.
Von Baer. — The next notable advance affecting natural
history came through the work of Von Baer, who, in 1828,
founded the science of development of animal forms. He
arrived at substantially the same conclusions as Cuvier.
Thus the system founded upon comparative anatomy by
Cuvier came to have the support of Von Bacr's studies in
embni'olog)'.
The contributions of these men proved to be a turning-
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134 BIOLOGY AND ITS MAKERS
point in natural history', ant! subsequent progress in syslcm-
atic botany and zoology resulted from thr application oi the
methods of Cuvier and Von Baer, rather than from following
that of Linna-us. His nomenclafirc remained a permanent
contribution of value, but- the knowledge of the nature of
living forms has been advanced chiefly by studies in com-
parative anatomy and cmbr>olog\-, and, also, in the applica-
tion of experiments.
The most significant advances in reference to the class-
ification of animals was to come as a result of the accept-
ance of the doctrine of organic evolution, subsequent to
1850. Then the relationships between animals were made
to depend upon community of descent, and a distinction
was drawn between superficial or apparent relationships
and those deep-seated characteristics that depend upon close
genetic affinities.
Alterations by Von Siebold and Leuckart. — Bui, in the
mean time, naturalists were not long in discovering that the
primary divisions established by Cuvier were not well bal-
anced, and, indeed, that they were not natural divisions of
the animal kingdom. The group Radiata was the least
sharply defined, since Cuvier had included in it not only those
animals which exhibit a radial arrangement of parts, but also
unicellular organisms ihat were asymmetrical, and some of
the worms ihal showed bilateral symmetry. Accordingly,
Karl Th. von Siebold, in 1845, separated these animals and
redistributed them. For the simplest unicellular animals he
adopted the name Protozoa, which they still retain, and the
truly radiateii forms, as starfish, sea-urchins, hydroid polyps,
coral animals, etc., were united in ihe group Zoophyta. Von
Siebold also changed Cuvier's branch, Articulata, separating
those forms as Crustacea, insects, spiders, and myriopods,
which have joinled appendages, inio a natural group called
Arthro[XKla, and uniting the segmented worms wiih those
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LINN-€US AND NATURAL HISTORY
135
worms that Cuvier has included in the radiate group, into
another branch called Vermes. This separation of the four
original branches of Cuvier was a movement in the right
direction, and was destined to be carried still farther.
SlEBOLD, 1804-1885.
Von Siebold fFig. 35) was an imi>orlant man in the
progress of zoology, especially in reference to the comparative
anatomy of the invertebrates.
Leuckart (Fig. 36), whose fame as a lecturer and teacher
;dbyGOOglC
1,16 BIOLOGY AND ITS MAKERS
attracted manj- young men to the University of Leipsic, is
another conspicuous personality in zoological progress.
This distinguished zoologist, following the lead of Von
Siebold, made further modifications. He split Von Siebold's
group of ZoSphytes into two distinct kinds of radiated animals:
the star-iishcs, sca-urchinn, sea -cucumbers, etc., having a
si)iny skin, he (k-si^naled Echinoderma; the jelly-fishes,
[X)ly|>s, coral animals, etc.. not jwssessing a true body cavity,
were also united into a natural sroup, for v.hich he projKweti
the name Calenlerata.
From all these change-s there ri'sulled the seven primarj-
;dbyGOOglC
LINN^US AND NATURAL HISTORY 137
divisions— branches, subkingdoms, or phyla— which, with
small modifications, arc still in use. These are Protozoa,
Cfelentcrata, Echinodcrma, Vermes, Arthro[X)da, MoHusca,
Vertebrata. These seven phyla are not entirely satisfaciorj-,
and there is being carried on a redistribution of forms, as in
the case of the brachiopods, the sponges, the tunlcates, etc.
While all this makes toward progress, the changes are of
more narrow compass than those alterations due to Von
Siebold and Lcuckart.
Summary. — In reviewing the rise of scientific natural
history, we observe a steady development from the time of
the Physiologus, first through a return to Aristotle, and
through gradual additions to his obsenalions, notably by
Gesncr, and then the striking improvements due to Ray and
Linnaeus. We may speak of the latter two as the founders
of systematic botany and zoology. But the system left by
Linnjeus was artificial, and the greatest obvious need was lo
convert it into a natural system founded upon a knowledge
of the structure and the development of living organisms.
This was begun by Cuvier and Von Bacr, and was continued
especially by Von Siebold and Lcuckart. To this has been
added the study of habits, breeding, and adaptations of or-
ganisms, a study which has given to natural history much
greater importance than if it stood merely for the systematic
classification of animals and plants.
Tabular View of Classifications. — \ table showing the
primary groups of Linnieus, Cuvier, Von Siebold, and
I.euckart will be helpful in picturing to the mind the modifi-
cations made in the classification of animals. Such a table
is given on the following page.
L. .\gassiz, in his famous essay on Classilication, reviews
in the most scholarly way the various systems of classifica-
tion. One peculiar feature of Agassiz's philosophy was his
adherence lo the dogma of the fixity of species. The same
;dbyGOOglC
138 BIOLOGY AND ITS MAKERS
year that his essay referred to was published {1859) appeared
Darwin's Origin 0} Species. Agassiz, however, was never
able to accept the idea, of the transformations of species.
Unnius
Cuvier
Von Siebold
Leuckart
Mammalia
Vertebrata
Vertebrata
Vertebrata
Aves
(Embracing five
cUs«.: M»m.
(Emljracingfi»e
(Five classes.)
Amphibia
milia, Aves, R«p-
tilia. Balrachia,
Pisces
Pisces.)
Insecla
MoUusca
Mollusca
Mollusea
{Including Ctiotsi-
Articulata
i Arthropoda
1 Vermes
Arthropoda
Vermes
(Including Uol-
lusca and all
lower fotmi.)
Radiata
iZotiphyta....
( Protoioa
Vermes
( Echinoderma
1 Cceknlernla
Protozoa
Steps in Biological Progress from Linnaeus to Darwin
The period from Linna;iis to Darwin is one full of im-
portant advances for biologj- in general. We have considered
in this chapter only those features that relatcxl to changes in
the system of classification, but in the mean time ihc morplio-
logical and the physiological sides of biolog\' were being ad-
vanced not only by an accumulalion of facts, but by their
better analysis. It is an interesting fact that, although during
this period ihc details of the subject were greatly niultiplierl,
prepress was relatively siraighlforward and by a series of
steps that can be clearly indicated.
It will be of advantage before the subject is taken up in
its jjarts to give a brief forecast in which the slcjw of i)rog-
ress can be represented in outline without the confusion
arising from the consideration of details. Geddes, in i8<)S,
jwinted out the steps in progress, and the account thai follows
is based upon his lucid analysis.
;dbyGOOglC
LINN^US AND NATURAL HISTORY 139
The Organism.^In the time of Linn^us the attention of
naturalists was mainly given to the organism as a whole.
Plants and ^nimah were considercH from the standpoint of
the organism— the external features were largely dealt with,
(he habitat, the color, and the general appearance — features
which charactcnze the organism as a whole. Linnieus and
Jussieu represent this phase of the work, and Buffon the
higher type of it. Modern studies in this line arc like addi-
tion to the Syslema Nalura:
Organs.— The first distinct advance came in investigating
animals and plants according to their stnicture. Instead
of the complete organism, the organs of which it is composed
became the chief subject of analysis. The organism was
dissected, the organs were examined broadly, and those of
one kind of animal and plant compared with another. This
kind of comparalive study centered in Cuvier, who, in the
early jiarl of the nineteenth cenliir}', founded the science of
comparative anatomy of animals, and in Hofmeister, who
cKaniincd (he structure of plants on a basis of broad com-
parison.
Tissues. — Bichat, the famous contemporar)' of Cuvier,
essayed a deeper level of analysis in directing attention to the
tissues that are combined to make up the organs. He dis-
tinguishcfl twenly-one kinds of tissues by combinations of
which the organs are comfXKcd. This step laid the founda-
tion tor the science of histologj-, or minute anatomy. Bichat
called it general anatomy (Analomie Ginerale, 1801).
Cells. — Before long it was shown that tissues are not the
real units of structure, hut that they arc composed of micro-
scopic elements calk'd cells. This level of analysis was not
reached until niagnifying-lenses were greatly improved —
it was a product of a closer scnuiny of nature with improved
instniments. The foundation of the work, especially for
plants, had been laid by Leeuwenhoek, Malpighi, and Grew.
;dbyGOOglC
I40 BIOLOGY A.\I» ITS MAKERS
But when the broad generalization, that all the tissues of
animals and plants are composed of cells, was given to ihc
world by Schleiden and Schwami, in 1838-39, the entire or-
ganization of living forms took on a new aspt-ct. This was
progress in understanding the morphology of aniinals and
plants.
Protoplasm.— With improved microscopes and atienlion
directed to cells, it was not long before the discovci^- was
made tliat ihc cells as units of slniclurc contain proloplasm.
That this substance is similar in plants and animals ami is
the seat of all vital activity was determined chiefly by (he-
researches of Max Schultze, published in 1861. Thus step
by step, from 1758, ihe <iale of the tenth wiilion of the
Systema ?\'>ilur(P, to 1861, there was a progress on the mor-
phological side, jiassing from the organism as a wholc'lo
organs, to tissues, to cells, and fmally to protoplasm, Ihe study
of which in all its phases is Ihc chief pursuit of biologists.
The physiological side had a paralKl development. In
the period of Linn:eus, the physiology of the organism was
investigated by Halkr and his school; following him the
physiology of oi^ns and lissues was advanced by J. Muller,
Bichal, and others. Later, Virchow investigated the physiol-
ogy of cells, and Claude Bernard the chemical activities of
protoplasm.
This set forth in outline will be amplified in the follow-
ing chapters.
;dbyGOOglC
CHAPTER VII
CUVIER AND THE RISE OF COMPARATIVE
ANATOMY
After observers lilte Linna-us and his followers had at-
tained a knowledge of the externals, il was natural that men
should turn their attention lo ihc organization or internal
structure of living beings, and when the latter kind of inves-
tigation became broadly comparative, it blossomed into com-
parative anatomy. The materials out of which the science
of comparative anatomy was constructed had been long
accumulating before the advent of Cuvier, bul the mass of
details had not been organized into a compact science.
As indicated in previous chapters, there had bcc-n an in-
creasing number of studies upon the structure of organisms,
both plant and animal, and there had resulted some note-
worthy monographs. .Ml this work, howe\*er, was mainly
descriptive, and nol comparative. Xow and then, the com-
paring tendency had been shown in isolated writings such as
those of Haney, .Malpighi, and others. As early as 1555,
Belon had compared the skeleton of the bin! with that of [he
human body "in the same jroslure and as nearly as possible
bone for bone"; but this was merely a. faint foreshadowing
of what was lo be done later in comparing the systems of the
more important oi^ns.
We must keep in mind that the study of anatomy em-
braces not merely ihe bony framework of animals, but also
the muscles, the nen'ous system, the sense organs, and all the
other structures of both animals and plants. In the rise of
;dbyGOOglC
142
BIOLOGY AND ITS MAKERS
comparative analomy there gra<lually emerged naturalists
whocom])are(i the structure of the higher animals with that
o{ the simpler ones. These comparisons brought out ;^o
many resemblances and so many remarkable facts that anat-
Fio. 37-
; 80-1656.
omy, which seems at first a dr.' subject, became endued with
great interest.
Severinus. — The first book expressly devoted lo eomi>ara-
tive analomy was that of Severinus (1580-1656), designalwi
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY "43
Zoolomia Democril(r. The title was derived from the Roman
naturalist Deniocritaus, and the date of its publicalion, 1645,
places the treatise earlier than the works of Malpighi, Leeu-
wcnhock, and Swammerdam. The book is illustrated by
numerous coarse woodcuts, showing the internal oi^ns of
fishes, birds, and some mammals. There are also a few
illustrations of stages in the development of these animals.
The comparisons were superficial and incidental ; neverthe-
less, as ihc first attempt, after the revival of anatomy, to
make the subject comparative, it has some especial inleresl.
Severinus (Fig. 37} should be recognized as beginning the
line of comparative anatomists which led up to Cuvier.
Forerunners of Cuvier, — Anatomical studies began to
take on broad features with the v.^ork of Camper, John
Hunter, and \'ic(j d'Azyr. These three men (javefl the way
for Cuvier, but it must be said of the two former that their
comparisons were limited and unsystematic.
Camper, whose portrait is shown in Fig. 38, was born in
Leyden, in i7?2. He was a versatile man, having a taste
for drawing, painting, and sculpture, as well as for scientific
studies. He received his scientific training under Boerhaave
and other eminent men in Leyden, and became a professor
and, later, rector in the University of Groningen. Possessing
an ample fortune, and also having married a rich wife, he
was in position to follov.* his ov.n lastcs. He travelled Mtcn-
sively and gathered a large collection of skeletons. He
showed considerable talent as an anatomist, and he made
several discoveries, which, however, he did not develop, but
left to others. Perhaps the possession of riches was one of
his limitations; at any rate, he lacked fixity of jmrpose.
Among his discoveries may be mentioned the semicircu-
larcanals in theearof fishes, thefact that the bones of flying
birds arc pcrmealcfl by air, the determination of some fossil
bones, with the suggestion that ihey belonged to extinct forms.
;dbyGOOglC
144 BIOLOGY AND ITS MAKERS
The latter point is of interest, as antedating the condusions
of Cuvier regarding the nature of fossil bones. Camper also
made obsen'ations ujton the facial angle as an index of in-
telligaice in the different races of mankind, and in lower
Fig, 38.
animals. He studied ihc anatomy of the ek'{>hant, the whale,
the orang, etc.
John Hunter (1728-1793), the gifted Scotchman whose
museum in London has been so juslly celebrated, was a man
of extraordinarj' originality, who read few hooks but went
dircclly lo nature for his facts; and, although he made errors
from which he would have been saved by a \vi(]er aci|ualnt-
;dbyGOOglC
RISE OP COMPARATIVE ANATOMY
M5
ance with the writings of naturalists, his neglect of reading
left his mind unprejudiced by the views of others. He was
a wild, unruly sjiiril, who would not bo forced into the con-
ventional mold as regards either education or manners.
His older brother, William, a man of more elegance and
refinemem, who well understood the value of wW^h in refer-
iMc. 3v-J'>H'-- HeNTEH, i^.a-.:-.^
ence to worldly success, tried to improve John by arranging
for him to go to the University of Oxford, but John rebelled
and would not have the classical education of the university,
nor would he take on the refinements of taste and manner of
which his brother was a good example. '' ^\'hy," the doughty
John is reported to have said, "ihey wanted to make me study
Toogli
146 BIOLOGY AND ITS MAKERS
Greek! The\' tried lo make an old woman of mc!" How-
e\'er much lack of appreciation this attitude indicated, it
shows also the Philistine independence of his spirit. This
independence of mind is one of his striking charact eristics.
This is not the place to dwell upon the unfortumilc con-
trcvcrsy that arose between these tivo illustrious brolhi:rs
regarding scientific discoveries claimed by each. The posi-
tion of both is secure in the historical development of mc<licine
and surger\\ Although the work of John Hunter was largeh'
medical and surgical, he also made extensive studies on the
com])arative anatomy of animals, and has a place as one of
the most conspicuous predecessors of Cuvicr, He was very
energetic both in making discoveries and in adding to his
great museum.
The original collections made by Hunter are still open to
inspection in the rooms of the Royal College of Surgeons,
London. It was his object to presen'e specimens lo illus-
trate the phenomena of life in all organisms, whether in
health or disease, and the extent of his museum may be
divined from the circumstance that he expended u|X)n it
about three hundred and scvcniy-five thousand dollars. Al-
though he describcil and compared many types of animals,
it was as much in bringing this collection together and leaving
it to i)osterity that he adi'anced comparative anatomy as in
what he wrote. After his death the House of Commons
purchased his museum for fifteen thousand pounds, and
placed it under the care of the corporation of Surgeons.
Hunter's portrait is shown in Fig. 39.
Vicq d'Azyr (Fig. 40), more than any other man, holds
the chief rank as a comjjarativc anatomist before the advent
of Cuvier into the same field. He was born in 1 748, the son
of a physician, and went to Paris at the age of seventeen to
study meificine. remaining in the metropolis to the time of
his death in 1794. He was celcbrateti as a physician, became
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY
M7
permanent secretary of the newly founded Academy of Med-
icine, consulting physician to the queen, and occupied other
positions of trust and responsibility. He married the niece
of Daubenlon, and, largely through his influence, was ad-
\'anced to social place and recognition. On the death of
Buffon, in 1788, he look the seat of that distinguished nat-
uralist as a member of the French Academy.
He made extensive studies upon the organization particu-
larly of birds and quadrupc-ds, making comparisons between
Iheir structure, and bringing out new [x>ints that were supe-
rior lo anything yet published. His comparisons of the limbs
of man and animals, showing a correspondence between the
flexor and extensor muscles of the legs and arms, were made
with great cxaciness, and they scn-ctl to mark the beginning
of a new kind of precise comjiarison. These were not merely
fanciful comparisons, biU exact ones — part for part; and
his general considerations based upon these comparisons were
of a brilliant character.
;dbyGOOglC
148 BIOLOGY AND ITS MAKERS
As Huxley has said, "he may beconsidered as the founder
of the modem science of anatomy." His work on the struc-
ture of the brain was the most exact which had appeared up
to that time, and in his studies on the brain he entered into
broad comparisons as he had done in the study of the other
parts of the animal organization.
He died at the age of forty-six, without being able to
complete a lai^e worli on human anatomy, illustrated with
colored figures. This work had been announced and en-
tered upon, but only that part relating to the brain had
appeared at the time of his death. Besides drawings of the
exterior of the brain, he made sections; but he was nol able
to determine with any particular degree of accuracy the
course of fiber traclb in the brain. This was left for other
workers. He added many new facts to those of his pred-
ecessors, and by introducing exact comparisons in anatomy
he opened the field for Cuvier.
Cuvier.— When Cuvier, near the close of the eighteenih
century, committed himself definitely to the progress of
natural science, he found vast accumulations of separate
monographs to build upon, but he undertook to dissect
represeniatives of all the groups of animaU, and to found
his comparative anatomy on personal obsenations. The
work of Vicq d'Ayzr marked the highest level of attain-
ment, and afforded a good model of what comparisons
should be; bul Cuvier had even larger ideas in reference
to the scope of comparative anatomy than had his great
predecessor.
The particular feature of Cuvier's service was ihai in his
investigations he covered the whole iicld of animal organiza-
tion from the lowest to the highest, and uniting his results
with what had already been accomplished, he established
comparative anatomy on broad lines as an independent
branch of natural science. Almost at the outset he conceived
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY 149
the idea of making a comprehensive study of the structure of
the animal kingdom. It was fortunate that he began his
investigations with thorough work ujion the invcrtebrated
animals: for from this view-point (here was gradually un-
folded to his great mind the plan of organization of the entire
series of animals. Not only is a knowledge of the structure
of the simplest animals an essential in understanding that of
the more modified ones, but the more delicate work required
in dissecting them gives invaluable training for anatomizing
those of more complex construction. The value attached to
this part of his training by Cuvier is illustrated by the advice
that he gave to a young medical student who brought to his
attention a supposed discover}' in anatomy. " Are you an
entomologist? " inquired Cuvier. "No," said the young man.
"Then," replied Cuvier, "go first and anatomize an insect,
and return lo me; and if you still believe that your obsen'a-
tions are discoveries I will then believe you."
Birth and Early Education. — Cuvier was bom in 1769,
at Montb^liard, a village at that time belonging to Wiirttem-
berg, but now a part of the French Jura. His father was a
retired military officer of (he Swiss army, and the family,
being Protestants, bad moved to Montb^liard for freedom
from religious persecution. Cuvier was christened LA)pold-
Chrislian-Fr61^ric-Dagobert Ciivier, but early in youth took
the name of Georges at the wish of his mother, who had lost
an infant son by that name.
He gave an early promise of intellectual leadership, and
his mother, although not well educated, took the greatest
pains in seeing that he formed habits of industry and con-
tinuous work, hearing him recite his k-ssons in Latin and
other branches, although she did not possess a knowledge of
Latin. He early showetl a leaning toward natural historj-;
having access to the works of Cifsner and ButTon, he prolited
by reading these two writer-. So great was his interest that
;dbyGOOglC
ISO BIOLOGY AND ITS MAKERS
he colored the plates in Buffon's Natural History from de-
scriptions in the text.
ll was at first contemplated by his family that he should
prepare for Iheclog;-, but failing, through the unfairness of
one of his teachers, to get an appointment to the theological
seminar}-, his education was continued in other directions.
He was befriended by the sister of the Duke of W'urttemberg,
who sent him as a pensioner to llie famous Carolinian acad-
emy at Stuttgart. There he showed great application, and
with ihe wonderful memory with which he was endowed, he
took high rank as a student. Here he met Kielmeyer, a
young instructor only four years older than himself, who
shared his tasie for natural history and, besides this, intro-
duced him to anatomy. In after years Cuvier acknowledged
the assistance of Kielmeyer in determining his future work
and in leaching him to dissect.
Life at the Seashore.— In 1788 the resources of his
family, which had always been slender, became further re-
duced by the inability of the govemmcnl to |>ay his father's
retiring stipend. As the way did not o])en for employ-
ment in other directions, young Cuvicr took the |X)st of in-
structor of the only son in the family of Count d'Hi?ricy,
and went with the family to the ?ea-coast in Normandy.
nt-ar Caen. For six years fi 788-1 794I he lived in this noble
family, with much lime at his disj>osal. For Cuvicr this
period, from the age of nineteen to twenty-five, was one of
constant research and retleciion.
While Paris was disrupted by the reign of (error, Cuvicr,
who, although of French descent, regarded himself as a (Jer-
man, was quietly carrying on his researchers into the >tnicure
of the life at the seaside. These years of diligent stmiy and
freiflom from distractions fixed his destiny. Here al the
s(-a coast, without the assi-itance of books and the stimulus
of intercourse with other naturalists, he was drawn directly
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY 151
to nature, and ihrough his great industry he became an in-
dependent observer. Here he laid the foundation of his ex-
tensive knowledge of comparative anatomy, and from this
quiet spot he sent forth his earliest scientific writings, which
ser\-ed to carry his name to Paris, the great center of scien-
tific research in France.
Goes to Paris.^His removal from these provincial sur-
roundings was mainly owing to the warm support of Tcssier,
who was spending the lime of the reign of terror in retirement
in an adjacent village, under an assumed name. He and
Cuvier met in a scicnlilic society, where the identity of Tessier
was discovered by C^uvior on account of his ease of speech
and his great familiarity wilh the lopics discussal. A friend-
ship sprung up between ihem, and Tessier addressed some
of his scientific friends in Paris in the inlort-st of Cuvier.
By this powerful inlroduclion, and also through the inter-
vention of GcofTroy Saint-Hilairc, he came to Paris in 1795
and was welcomed into the group of working naturalists
at the Jardin des Plantes, little dreaming at the lime that
he should be the leader of the group of men gathered around
this scientific insiituiion. He was mo<Iesl, and so uncertain
of his future that for a year he held to his post of instructor,
bringing his young cliarge wilh him to Paris.
Notwithslanding the doubt which he entertained regard-
ing his abilities, his career ]>rove(l successful from !he begin-
ning. In Paris he cnlered upon a brilliant career, which was
a succession of Iriumphs. His unmistakable talent, com-
bined with industry and unusual opjKjrt unities, brought him
rapidly lo (he front. The large amount of material already
collec'cd.and the -stimulating comjjanionship of other scien-
tific workers, affordiil an environment in which he grew
rapidly. He responded to the stimulus, and developc?d not
only into a great naturalist, but exjianded into a finished
gentleman of the world. Circumstances shaped themselves
;dbyGOOglC
»52
BIOLOGY AND ITS MAKERS
SO that he was called to occupy prominent oDices under the
government, and he came iillimatcly to be the head of the
group of pcicniific men inio which he had been welcomed as
a young man from the provinces.
His Physiognomy. — It is vcr\ interesting to note in his
portraits the change in his physiognomy accompanying his
transformation from a young m;in of provincial appearance
into an eU'gant personage. Fig. 41 shows his porinil in the
farly days when he was less mindful of his personal appe;
ancc. It is the face of an eager, strong, young man, stilt
taining traces of Jiis provincial life. His long, lighl-colore*!
hair is unkempt, but docs not hide the magnificent propor-
tions of his hi'ad. Fig. 42 shows the growing rcfincmci
features which canio with liis advancement, and ;ho aristo-
cratic look of supremacy which set ujHjn his connlenancc afii
;dbyGOOglC
RISE OF COMPARATIVK ANATOMY
153
his wide recognition passing by a gradation of steps from the
position of hrad of the educational system, to that of baron
and peer of France.
Cuvier was :l man of commandirif^ ix>wer and colosiil
attainments; he was a favorite of Napoleon Bonajjarte, who
ele\-atcd him to office and made him director of Ihe higher
educational institutions of the Empire. But to whatever
place of prominence he attainal in the govi-rnmenl, he never
Digitized oy^lOOQlC
154 BIOLOGY AND ITS MAKERS
lost his love for natural science. With hini ihis was an
absorbing passion, and it may tje said that he ranks higher
as a zo6logist than as a legislator.
Comprehensiveness of Mind. — Soon after his arrival in
Paris he began to lecture upon comparative anatomy and to
continue work in a most comprehensive way upon the subjects
which he had cultivated at Caen, He saw evcr^-thing on a
large scale. This led to his making extensive studies of what-
ever problems engaged his mind, and his studies were com-
bined in such a manner as to give a broad view of the subject.
Indeed, comprehensiveness of mind seems to have been
the characteristic which most impressed those who were
acquainted with him. Flourens says of him: " Ce qui ca-
racUrise par/out M. Cuvier, c'esl Vesprilvasle." His broad
and comprehensive mind enabled him to map out on great
lines the subject of comparative anatomy. His breadth \\as
at times his undoing, for it must be confessed that when the
details of the subject arc considered, he was often inaccurate.
This was possibly owing to the conditions under which he
worked; having his mind diverted into many other chan-
nels, never neglecting his state duties, it is reasonable lo
suppose that he lacked the necessary time to prove his ob-
scnalions in anatomy, and we may in this way account for
some of his inaccuracies.
Besides being at fault in some of his comparative anat-
omy, he adhered to a number of ideas that servi-d to retard
the progress of science. He was opposcil to the ideas of his
contemporary Lamarck, on (he evolulion of animais. He
is remembered as the author of the dogma of calaslrophism
in geolog)'. He adhcre<l to the old notion of ihc prc-forma-
lion of the enibr\*o, and also to the theory of the si)onta-
ncous origin of life.
Founds Comparative Anatomy. — Regardless of this
qualification, he was a great and distinguished student, and
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY 155
founded comparative anatomy. From 1801 to 1805 appearetl
his Lefons d'Analomie Coinparic, a systematic treatise on the
comparative anatomy of animals, embracing both ihe in-
vertebrates and the vertebrates. In 1812 was published his
great work on the fossil bones about Paris, an achievement
which founded tlie science of vertebrate palaeontology. His
extensive examination of the structure of fishes also added
to his already great reputation. His book on the animal
kingdom (Le Rhgnc Animal distribiii d'apris son Organisa-
tion, i^iti), in which he expounded his type-theory, has been
considcrcfl in a previous chapter.
He was also deeply interested in the historical develop-
ment of science, and his volumes on the rise of the natural
sciences give us almost the bist historical estimate of the
progress of science that we have at the present day.
His Domestic Life, — Mrs. Lee, in a chatty account of
Cuvier, shows one of his methods of work. Ho !iad the
faculty of making others assist him in various ways. Not
only members of his family, but also guests in his household
were presseri into service. They were invited to examine
different crlitions of works and to indicate the dif!"ercnces in
the plates and in the text. This practice rcsultctl in saving
much lime for Cuvier, since in the prcimration of his histor-
ical lectures he undertook to examine all the original sources
of the history with which he was engaged. In his lectures he
summarized facts relating to different editions of books, etc.
Mrs. Lee also gives a picture of his family life, which was,
to all accounts, very beautiful. He was devoted to his wife
and children, and m the midst of c.'^acting cares he found
time to bind his family in love and devotion. Cuvier was
called upon to suffer poignant grief in the loss of his chil-
dren, and his direct family was not continued. He was
especially broken by the death of his daughter who had
grown to young womanhood and was about lo be married.
;dbyGOOglC
15^ BIOLOGY AND ITS MAKERS
From the standpoint of a sincere admirer, Mrs. Lee
writes of his generosity and nobility of lemperament, fleclar-
ing that his career demonstrated that his mind was great
and free from both envy and smallnes;.
Some Shortcomings.— Xeverthcless, there arc certain
things in (he Hfe of Cuvier that w c wish might not have been.
His break with his old friends Lamarck and Sainl-Hilairc
seems to show a domination of qualities that were not gen-
erous and kindly; those obser\-ations of Lamarck showing a
much profounder insight than any of which he himself was
the author were laughed to scorn. His famous controversy
with Saint-Hilaire marks a historical moment that will be
dealt with in ihc chapter on Rise of Evolutionary Thought.
George Bancroft, the American historian, met him fhiring
a visit to Paris in 1827. He speaks of his magnificent eyi-s
and his fine appearance, but on the whole Cuvier seems lo
have impressed Bancroft as a disagreeable man.
Some of his shortcomings that ser\*cd lo retard the prog-
ress of science have been mentioned. Still, with all his fauhs,
he dominated zoological scierceat the beginning of ihe nine-
teenth century, and so imwerful was his inlluence and so un-
disputed was his auihoriiy among the French |ieo|ile ihat
the rising young men in natural science sideil wiih Cuvier
even when he was wrong. It is a noteworthy fact that Fitince,
under the iniiuence of the traditions of Cv.\ ier. was the last
country- slov.-iy and reluctantly to harbor as true the ideas
regarding the evolution of animal life,
Ci'vier's Successors
While Cuvier's theoretical conclusions exerci^al a rctarfl-
ing influence upon the progress of biology, his jiractical
studies more than conipen?.aied for this. It has been itoinied
out how his lype-ihi'ory led to the reform of the l,inn;ean
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY I."!?
system, but, besides this, the stimulus which his investiga-
tions gave to studies in ';oniparative anatomy was even of
more beneficent influence. As time passed the importance
of comparative anaiomy as one division of biological science
impressed itself more and more ujxin naturalists. A large
number of investigators in France, England, and Germany
entered the field and took up the work where Cuviei- had
l"ic.. 43— H. Mii-SK-EuwARDS, 1800-1885.
left it, Thf morf iioiiibic of these successors of Cuvier
should come under consideration.
His intellectual heirs in France were Milne-Kd wards and
Lacaze-Dutliiers.
Milne-Edwards.— H. Milne-Edwanls (1800-1885) was a
man of ijreiit indusjrv and line attainmenlii; prominent alike
in comjMiraliveanaloniv, comparative [ihysiolog)', and general
zoologj', professor for many years at the Sorbonne in Paris.
;dbyGOOglC
158 BIOLOGY AND ITS MAKERS
In 1827 he introduced into biology ihc fruitful idea of the divi-
sion of physiological labor. He completed and published
excellent researches iiijon the structure and development of
many animals, nolably Crustacea, corals, etc. His work on
comparative anatomy took the form of explanations of ihe
activities of animals, or comparative physiolog}'. His com-
prehensive treatise I^fons stir la Pliysiologie el TAnalomie
Comparie, in fourteen volumes, 1857-1881, is a mine of
information regarding comparative anatomy as v/ell as the
phii'siology of organisms.
Lacaze-Duthiers. — Henri de Lacaze-Duthiers (1821-
1901), the man of comprehensive mind, stimulating as an
instructor of young men, inspiring other workers, and pro-
ducing a large amount of original research on his own ac-
count, directorof the Seaside Stations at RoscofT and Banyuls,
the founder of a noteworthy periodical of experimental ^.oiil-
ogy — this great man, whose porlrail is shown in Fig. 44, was
one of the leading comparative anatomists in France,
R. Owen. — In England Richard Owen (1804-1 S92) carried
on the influence of Cuvier. At the age of fwenty-snrn he
went to Paris and renewed acquaintance with the great Cuvier,
whom he had met ihe previous ytar in Fngland. He spent
some time at the Jardin des Plitntes examining the extensive
collections in the museum. Although the idea was repudiated
by Owen and some of his friends, it is not tmlikely that the
collections of fossil animals and the researches upon them
which engaged Cuvier ;:t that time had great influence ujjon
the subserjuent stiidies of Owen. Although he never sludici!
under Cuvier, in a sense he may be regarded as his disciple.
Owen introiiuced into anatomy the im])ortant conce])tions
of analogv and homology, the former being a likeness baser!
upon the use to which organs are put, as Ihe wing of a butter-
fly and the wing of a bat; while homology,- is a true relation-
ship founde<l on likeness in structure and devclo])ment, as
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY
159
the wing of a bat and the foreleg of a dog. AiiRlogj- h a
superficial, and often a deceiving relationship; homologj' is
a iruc genetic relationship. It h obvious thai this distinction
4
is of great importance in comparing the different parts of
animals. I!e made a large number of independent discov-
eries, and |)ublished a monumental work on lhecomi:>arativt
Digitized oy^lOOQlC
i6o
BIOLOGY AND ITS MAKERS
anatomy of vertebrates {1866-68). In much of Iiis lliouylit
he was singular, and many of his general conclusions have
not slood the test of time. He undertook 10 establish the
idea of an archtype in vertebrate anatomy, lie clunj; 10 the
vertebral thcor}-of the skull long after Huxley hail shown such
a theory to be untenable. The idi-a that the skull is made up
of modified vertebra was jtropoujided by (Joelhe and Okcn.
In the hands of Okcn it became one of the anatomical con
elusions of the school of Nalurphilosophir. This school ol
transcendental philoso]>hy was founded by Schelling,
Okcn (Fig. 45) was one of its typical rcprescnlativt-s. The
vertebral thcor>' of the -ikull was, therefore, not ori,i;ina!
with Owen, but he iidopted il, i;real!y elaborated it, an<l
;dbyGOOglC
RISE Oi' aiMPARATlVE ANATOMY lOl
clung to it blindly loni; aflcr ihc foiinciations upon which it
reslefi wt-rc removal.
KichanJ Owen (Fif;. 46) was. succtcdcil by HiixiL-y (1S35-
i8q5J, whose exactni-ss of obscn'ation and rare judgment
as lo the main fact? of comparalive anatomy m.tri; him as
one of ihe K'aders in this field of research. The influence
of Huxley as a popular exponent of science is dealt with
in a latiT chapter.
Toogli
i62 BIOLOGY AND ITS MAKER3
Meckel.^ust as Cuvicr stands at the beginning of the
school of comparative anatomy in France, so does J. Fr.
Meckel in Germany. Meckel (i 781-1833) was a man of
rare talent, descended from a family of distinguished anat-
omists. From 180^ to 1806 he studied in Paris under Cuvier,
and when he came to leave the French capital to become
professor of anatomy at Halle, he carried into Germany the
(cachings and mclliwls of his master. He was a stronjj force
in tlie university, attracting students to his de|>ar'ment by
his excellent lectures and his abiliiy to arouse enthusiasm.
Some of these students ivere stimidatcd to undertake re-
searches in anatomy, and there came from his laboraton- a
number of investigations that were published in a perioflical
which lie foundixl. Meckel himself jiroduccd many scieniil'ic
papers and works on conijKirative anatomy, which assisted
;dbyGOOglC
RISE OP COMPARATIVE ANATOMY l(>3
materially in the advancement of that science. His portrait,
which is rare, is showTi in Fig. 47.
Rathke.— Martin Hcnrj' Rathkc (i 793-1860) greatly
advanced the science of comparative anatomy by insisting
upon the importance of elucidating anatomy with researches
in development. This is such an important consideration
that his influence upon the progress of comparative anatomy
can not be oveilookcd. After being a professor in Dorpat,
he came, in 1835, to occupy the position of professor of anat-
omy and zoolog}' at Konigsbcrg, which had been vacated by
Von Baer on the removal of the latter to St. Petersburg. His
writings are com]x>sc-d with great intelligence, and his facts
are carefully coordinated, Rathke belonged lo ihe good old
school of German writers whose researches were profound
and extensive, and whose expression was clear, being based
upon matured thought. His papers on the aortic arches
and the Wolffian body are those most commonly referred to
at the ]>resent time.
HiiUer. — Johannes MuHer (1801-185S), that phenomenal
man, besides securing recognition as the greatest physiol-
ogist of the nineteenth centun-, also gave attention to com-
parative anatomy, and earned the title of the greatest mor-
phologist of his time. His researches were so accurate, so
coni])Ieie, so discerning, that his influence upon the develop-
ment of comparative anatomy was profound, .-\lthough he
is accordc-d, in history, the double distinction of being a great
anatomist and a great physiologist, his teaching tended to
physiolog)-; and most of his distinguisherl students were
physiologists of the broadest type, uniting comparative anat-
omy with their researches upon functional activities. (For
Miiller's portrait see p. 187.)
Gegenbaur. — In Karl Gegenbaur (1826-1903) scientific
anatomy reached its highest expression. His work was char-
acterized by broad and masterly analysis of the facts of struc-
;dbyGOOglC
i64
BIOLOGY AND ITS MAKERS
ture, to which were adder] the ideas derived from the study of
the development of or^ns. He was endowed with an intensely
keen insight, an insight which enabled him to separate from
the vast mass of facts the important and essential featun-s,
so that they yielded results of great interest and of lasting im-
]>ortance. This gifted anatomist attracte^l manv young men
from the I'nitt'd Stales and from other counlrics to pursue
under his direction the study of comiiarative anatomy, Hg
died in Heidelberg in hjo^, where he had been for many years
professor of aiiatomy in the university.
In the group ol living German anatoniisls the names of
Furbringer, Waldeyer, and Wiedershcini can not go unmen-
tioned.
;dbyGOOglC
RISE OF COMPARATIVE ANATOMY 165
E. D. Cope. — In America the greatest comparative
anatomist was E, D. Cope (1840-1897), a man of the highest
order of attainment, who dealt with the comparative anatomy
not only of living forms, but of fossil life, and made contribu-
tions of a permanent character to this great science; a man
whose title to distinction in the field of comparative anatomy
will become clearer to later students with the passage of lime.
For Cope's portrait see p. 336.
Of the successors of Cuvier, we would designate Meckel,
Owen, Gegcnbaiir, and Cope as the greatest.
Comparative anatomy is a very rich subject, and when
elucidatetl by embryology, is one of the firm foundations of
biolog\-. If we regard anatomj' as a science of statics, we
recognize that it should be united with physiology, which
represents the dynamical side of life. Comparative anatomy
and comparative physiology should go hand in hand in the
attempt to interpret living forms. Advances in these two
subjects embrace nearly all our knowledge of hving organisms.
It is a cause for congratulation that comjiamtive anatomy
has now become cxpcrimentai, and that gratifying progress is
being made along the line of research designated as experi-
mental morphologj'. Already valuable results have been
attained in this field, and the outlook of experimental mor-
phology is most promising.
;dbyGOOglC
CHAPTER VIII
BICHAT AND THE BIRTH OF HISTOLOGY
We must recognize Bichal as one of the foremost men in
biological history, although his name is not well known to the
general public, nor constantly referred to by biologists as
that of one of the chief luminaries of their science. In him
was combined extraordinary talent with powers cf intense
and prolonged application; a combination which has always
produced notable results in the world. He died at ihc age
of thirty-one, but, within a productive period of not more
than seven years, he made observ-ations and published work
that created an epoch and made a lasting impression on bio-
logical historj-.
His researches supplemented those of Cuvier,and carried
the analysis of animal organization to a deeper level. Cuvier
laid the foundations of comparative anatomy by dissecting
and arranging in a comjjrehensive system the organs of ani-
mals, but Bichat went a step further and made a profound
study of the tissues that unite to make up the organs. -\s we
have already noted in a previous chapter, this was a step in
reaching the conception of the real organization of living
beings.
Buckle's Estimate of Bichat. — It is interesting to note
the impression made by Bichat upon one of the greatest
students of the hislor)- of civilization. Buckle says of him:
"Great, however, as is the name of Cuvier, a greater still
remains behind. I allude, of course, to Bichat, whose rcpu-
;dbyGOOglC
THE BIRTH OF HISTOLOGY 167
tation is steadily advancing as our knowledge advances;
who, if we compare the shortness of his life with the reach and
depth of his views, must be pronounced the most profound
thinker and consummate obsener by whom ihc organization
of the animal frame has yet been studied.
"We may except Aristotle, but between Aristotle and
Bichat I find no middle man,"
Whether or not we agree fully with this panegyric of
Buckle, we must, I Ihink, place Bichat among the most illus-
trious men of biological historv-, as \'esalius, J. Miiller, Von
Bacr, and Balfour.
Marie Francois Xavier Bichat was bom in 1771 at
Thoirette, department of the Ain, His father, who was a
physician, directed (he early education of his son and had
the satisfaction of seeing him lake kindly to intelleciiial pur-
suits. The young student was distinguished in Latin and
mathematics, and showed early a fondness for natural his-
tory. Having ek-cled to follow the calling of his father, he
went to Lyons to study medicine, and came under the
instruction of Pttit in surgen.-.
Bichat in Paris. — It was, on the whole, a fortunate cir-
cumstance for Bichat that the lurbuler.t events of the French
RLvoluiion drove him from Lyons to Paris, where he could
have the best training, the greatest stimulus for his growth,
and at the same time the widest field for the exercise of his
talents. We find him in Paris in 1793, studying under the
great surgeon Desault.
He attracted attention to himself in the class of this dis-
tinguished teacher and operator by an extemporaneous report
on one of the lectures. It was the custom in Desault's classes
to have the lectures of the professor reported upon before an
assistant by some student especially appointed for the pur-
pose. On one occasion the student who had been appointed
to prepare and deliver the review was absent, and Bichat,
;dbyGOOglC
Iti8 BIOLOGY AND ITS MAKERS
who was gifted with a i^wtrful memory, volunteered without
|>ri'vious notice to take his place. The lecture was a long and
ditVicult one on the fractures of the clavicle, but Bichat's
abstract was so ck-ar, forceful, and complete that its dcliven,-
in well-chosen language jiroduccd a great sensation both ujxjn
the instructor and the students. This notable performance
ser\-ed to bring him directly to the attention of Desaull, who
invited him to become his assistant and to live in his family.
The association of Bichat with the great surgeon was most
happy, Desault treated him as a son, and when he suddenly
die<l in 1795, the care of preparing his works for the printer
was left to Bichat.
The fidelity with which Bichat execute*! this trust was
characteristic of his noble nature. He laid aside his own
personal interesl-;, and his researches in which he was already
immersed, and by almost superhuman labor completed the
fourth volume of Desault's Journal of Surgery and at the
same time collected and published his scattered [japers. To
these he added observations of his own, making alteration:;
to bring the work up to the highest plane. Thus he paid
the debt of gratitude which he felt he owi-d to Desault (or
his friendship and assistance.
In 1797 he was ap|x>inted professor of anatomy, at the
age of twenty-six, and from then to the end of his life, in 1801,
h« continued in his career of remarkable industry.
The portrait of this ver}' attractive man is shown in
Fig. 49. His face shows strong intellectuality. He is de-
scribed as of " middling stature, with an agreeable face lighted
by piercing and expressive c)'cs," He was much belovwi t)y
his students and associates, being "in all relations of life
most amiable, a stranger to cmy or other hateful pa.isions,
modest in demeanor and lively in his manners, which were
oiH'n and free."
His Phenomenal Industry. — His industry- was phenum
;dbyGOOglC
THE BIRTH OF HISTOLOCY 1^9
enal; besides doing the work of a professor, he attended to
a considerable practice, and during a single winter he is said
to have examined with care six hundred bodies in the pur-
suance of his researches upon pathological anatomy.
In the year 1800, when he was thirly years old, began to
appear the results of his matured researches. We speak of
these as being mature<l, not on account of his age or the great
number of years he had labored ujwn them, but from the
;dbyGOOglC
170 BIOLOGY AND ITS MAKERS
intensity and completeness with which he had pursued his
investigations, thus giving to his work a lasting quality.
First came his treatise on the membranes (I'raiti des
Membranes); followed quickly by his Physiological Re-
searches into the Phenomena of Life and Death (Reclierches
Physiologiques sur la Vie el la Hforl); then appeared his
General Anatomy {Anatomic Ginirale) in 1801, and his trea-
tise upon Descriptive Anatomy, upon which he was working
at the time of his death.
His death occurred in 1801, and was due partly to an
accident. He slipped upon the stairs of the dissecting-room,
and his fall nas followed by gastric derangement, from which
he died.
Results of His Work. — The new science of the anatomy
of the tissues which he founded is now known as histology,
and the general anatomy, as he called it, has now become
the study of minute aimtomy of the tissues. Bichat studied
the membranes or tissues very profoundly, but he did not
employ the microscope and make sketches of their cellular
construction. The result of his work was to set the world
studying the (Oinute structure of the tissues, a consequence
of which led to- the modem study of histology. Since this '
science was constructed directly upon his foundation, it is
proper to recognize him as the founder of histology.
Carpenter saj's of him : " Altogether Bichat left an impress
upon the science of life, the depth of which can scarcely be
overrated; and this not so much by the facts which he col-
lected and generalized, as by the method of inquirj- which
he developed, and by the systematic form which he gave 10
the study of general anatomy in its relations both to physi-
ology an<l [Kitholog)-."
Bichat's More Notable Successors. — His influence ex-
tended far, and after ihe establishment of the cdl theory
took on a new phase. Microscopic study of the tissues has
;dbyGOOglC
THE BIRTH OF HISTOLOGY i?!
now become a separate division of the science of anatomy,
and engages the attention of a very laige number of workers.
While the men who buiU upon Bichal's foundation are nu-
merous, we shall select for especial mention only a few of the
more notable, as Schwann, Koclliker, Schultze, Virchow,
Leydig, and Ramon y Cajal, whose researches stand in the
direct line of development of the ideas promulgated by
Bichat.
Schwann.— Schwann's cell-theory was the resultof close
attention to the microscopic structure of the tissues of ani-
mals. It was an extension of the knowledge of the tissues
which Bichat distinguished and so thoroughly investigated
from other points of view. The cell-theory, which took rise
in 1839, was itself epoch-making, and the science of general
anatomy was influenced by it as deeply as was the science of
embrj'olog)-. The leading founder of (his theory was
Thcodor Schwann, whose portrait is shown on page 245,
where there is also a more extended account of his labors in
connection with the cell-lheorv'. Had not the life of Bichat
been cut oft in his early manhood, he might well have lived
to sec this great discover)' added to his own.
Koelliker. — Albrcchl von Koellikcr (1817-1905) was one
of the griatest histologists of the nineteenth century. He is a
striking figure in the development of biology in a general way,
distinguished as an embryologist, as a histologist, and in
other connections. During his long life, from 1817 to 1905,
he made an astounding number of additions to our knowledge
of microscopic anatomy. In the early years of his scientific
activity, "he helped in establishing the cell-theory, he traced
the origin of tissues from the segmenting ovum through the
developing embryo, he demonstrated the continuity between
nerve-fibers and nerve-cells of vertebrates (1845), ■ ■ ■ ^^'^
much more." He is mentioned further, in connection with
the rise of embryology, in Chapter X,
;dbyGOOglC
172 BIOLOGY AND ITS MAKERS
The strong features of this veteran of research are shown
in the portrait, Fig. 50, which represents him at the age of
seventy.
In 1847 he was called to the University of W'urzburg,
where he remained to the time of his death. From 1850 to
1900, scarcely a year passed without some important contri-
bution from Von Kocllikcr extending the knowledge of his-
tology. His famous textbook on the slructureof the tissues
(Handbiich der Gnvebdehre) jxissed through six editions from
1852 to 1893, the final edition of it being worked over and
brought up to date by this extraordinary man after he had
passed the age of seventy-five. By workers in biologj' this
will be recognized as a colossal task. In the second volume
of the last edition of this work, which appeared in 1893, he
went completely over the ground of the \ast accumulation of
information regarding the ncnous system which an army of
gifted and- energetic workers had produced. Thb was all
thoroughly digested, and his histological work brought down
to date.
Sdmltze.— The fine obsenations of Max Schullzef 1825-
1874) may also be grouped with those of the histologists,
V/c shall have occasion to speak of him more particularly in
the chapter on Protoplasm. He did memorable scnice for
general biology in establishing the protoplasm doctrine, but
many of his scientific memoirs are in the line of normal
histology; as, those on the structure of theolfacton- mem-
brane, on the retina of the eye, the muscle elements, the
nerves, etc., etc.
Normal Histology and Pathology. — But histolog\- has
two phases: the investigation of the tissues in health, which
is called normal histologjs and the study of the tissues in
disease and under abnornuil conditions of development,
which is dt-signated pathological histolog>-. The laller divi-
sion, on account of its im|X)r1ance to the medical man, ha/
;dbyGOOglC
174
BIOLOGY AND ITS MAKERS
bet'ii extensively cultivated, and the development of patho-
logical study has greatlj' extended the knowledge of the
tissues and has bad its influence upon the progress of normal
histology. Goodsir, in England, and Henle, in (>ermany,
entered the field of jjathological hislologj, both doing work
of historical imjjoilancc. They were soon followed by Mr-
chow, whose eminence as a man and a scientist has made
his name familiar to people in general.
Virchow. — Rudolph Virchow (1821 1903), for many
years a professor in the University of Berlin, was a notable
man in biological science and also as a member of the (ierman
;dbyGOOglC
THE BIRTH OF HISTOLOGY ^75
parliament. He assisted in molding the cell-theory into
better form, and in 1858 jjublished a work on Cellular
Patliology, which applied the cell-theory to diseased tissues.
It is to be remembered that Bichat was a medical man, in-
tensely interested in pathological, or diseased, tissues, and we
see in \'irchow the one who especially e.xlendcd Bichat's work
on the side of abnormal histology. \'irchow's name is asso-
ciated also with the beginning of Ihc idea of germinal conti-
nuity, which is the basis of biological ideas regarding hered-
ity (see, further. Chapter XV).
Leydig. — Franz Lcydig fFig, 52) was early in the field
as a histologist with his handbook (Lehrbtich der Histologie
;dbyGOOglC
176 BIOLOGY AND ITS MAKERS
des Menschen und der TJiiere) published in 1857. He agtplied
histologj- especially lo the lissues of insects in 1864 and sub-
sequent years, an account of which has already been (jivcn
in Chapter V.
Cajal as Histologist. — Ramon y Cajal, professor in the
University of Madrid, is a histologisi whose work in a special
field of research is of world-wide renown. His invesiiKations
into the microscopic texture of the nervous system antl sense-
organs have in larpe jMirl cleared up the (juestions of (he com-
plicatwl relations between Ihe ner\ous elements. In com-
pany with other Kuropean investigators he visilul the I'niud
Stali-s in 180Q on the inviiaiion of Clark University, where his
lecluri-s were a feature of (he ceJebralion of the tenth anni-
;dbyGOOglC
THE BIRTH OF HISTOLOGY 177
versary of that university. Besides receiving many honors in
previous years, in 1906 he was awarded, in conjunction with
the Italian histologist Golgi, one of the Nobel prizes in recog-
nition of his notable Investigations. Golgi invented the stain-
ing melhods that Ramon y Cajal has applied so extensively
and so successfully (o the histology of the nervous sjstcm.
These men in particular may be remembered as the inves-
tigators who expanded the work of Bichat on the tissues:
Schwann, for disclosing the microscopic elements of animal
tissues and founding the ccll-theor}- ; Koelliker, as the typical
histologist after the analysis of tissues into their elementary
parts; Virchow, as extending the cell-idea to abnormal his-
tology; Leydig, for applying histology to the lower animals;
and Ramon )■ Cajal, for investigations into the histology of
the ner\'ous system,
Text-Books of Histology.— Besides the works mentioned,
the text-books of Frey, Strieker, Ranvier, Klein, Schafer,
and others represent a period in the general introduction of
histology to students between 1859 and 1885. But these
excellent text-books have been largely supersetkd bj' the
more recent ones of Slohr, Boem- DavidofT, Picniol, Szy-
monowicz, and others. The number of living invesligaiors
In histology is enormous; and their work in the subject of
cell -structure and in the department of embryology now
overlaps.
In pathological histologj- may be observed an illustration
of the application of biological studies to medicine. While
no attempt is made to give an account of these practical ap-
plications, they are of too great importance to go unmcn-
tioned. Hislolc^ical methods are in constant use in clinical
diagnosis, as in blood counts, the study of InRammations, of
the action of phagocytes, and of all manner of abnormal
growths.
In attempting to trace the beginning of a definite founda-
;dbyGOOglC
178 BIOLOGY AND ITS MAKERS
tion for the work on the structure of tissues, we go back to
Bichat rather than to Leeuwenhoek, as Richardson has pro-
posed. Bichat was the first to give a scientific basis for
histologj' founded on extensive observations, since all earlier
observers gave only separated accounts of the structure of
particular tissues.
;dbyGOOglC
CHAPTER IX
THE RISE OF PHYSIOLOGY
Harvey Haller Johannes Mulleh
Physiology had a parallel development with anatomy,
but for convenience it will be considered separately. Anatomy
shows us that animals and plants are wonderfully con-
structed, but after we understand their architecture and even
their minute structure, the questions remain, What are all
the organs and tissues for ? and what takes place within the
parts that arc actually alive? Physiology attempts to answer
questions of this nature. It stands, therefore, in contrast
with anatomy, and is supplementary to it. The activities of
living organisms arc varied, and depend on life for their
manifestations. These manifestations may be called vital
activities. Physiology embraces a study of them all.
Physiology of the Ancients. — ^This subject began to at-
tract the attention of ancient medical men who wished to
fathom the activities of the body in order to heal its diseases,
but it is such a difficult thing to begin to comprehend the
activities of life that even the simpler relationships were im-
perfectly understood, and ihcy resorted to mythical explana-
tions. They spoke of spirits and humors in the body as
causes of various changes; the arteries were supposed to
carry air, the veins only blood ; and nothing was known of the
circulation. There arose among these early medical men
the idea that the body was dominated by a subtle spirit.
This went under the name pnenma, and the pneuma -theory
held sway until the period of the Revival of Learning.
;dbyGOOglC
l8o BIOLOGY AND ITS MAKERS
Among the ancient physiologists the great Roman phy-
sician Galen is the- most noteworthy figure. As he was the
greatest anatomist, so he was also the greatest physiologist
of ancient times. All physiological knowledge of the time
centered in his writings, and these were the standards of
physiology for many centuries, as they were also for anatomy.
In the early days anatomy, physiology, and medicine were all
unitc-d into a poorly digested mass of facts and fancies. This
state of alTairs lasted until the sixteenth century-, and then the
awakening came, through the efforts of gifted men, endued
with the spirit of independent invc-stigation. The advancc-s
made depended upon the work or leadership of these men,
and there are certain periods of especial importance for the
advance of physiolog)' that must be pointed out.
PeriocI of Harvey. — The first of these epoch? to be esj^e-
cially noled here is the period of Har\cy (1578-1657!. In his
time the old idea of spirits and humors was giving way, but
there was still much vagueness regarding the activilie-s of ihe
body. He helped to illuminate the subject by showing a con-
nection between arteries and veins, and by demonstrating
the circulation of the blood. As we have seen in an earlier
chapter, Harvey did not observe the blood [>assing through
the capillaries from arteries to veins, but his reasoning was
unassailable thai such a connection must exist, and lliat the
blood made a complete circulation. He gave his conclusions
in his medical lectures as early as 1619, but did not publish
his views until 1628. It was reserved for Malpighi, in iM>i,
actually to sec the circulation through the capillaries under
the microscope, and for Leeuwcnhoek, in 1669 and later
years, to extend these obsen'ations.
It was during Harvey's life thai the microscope was
brought into use and was of such great assistance in advanc-
ing knowledge. Harvey himself, however, made little use
of (his instrument. It was during his life also that the knowl-
;dbyGOOglC
THE RISE OF PHYSIOLOGY lai
edge of development was greatly (iromoled, first through his
own efforts, and later through those of Malpighi.
Harvey is to be recogniztd, then, as the father of modem
physiolog)-. Indeed, before his time physiologj- as such can
hardly be spoken of as having come into existence. He intro-
duced experimental work into physiologj-, and thus laid the
foundation of modem investigation. It was the method of
Harvey that made definite progiess in this line possible, and
accordingly we hcinor him as one of the grfatest as well as
the earliest of, physiologists.
Period of Haller. — From Haney's time we pass to the
period of Haller (1708-1777), aj: the beginning of which
physiolt^- was still wrapped up with medicine and anatomy.
The great workof Haller was to create an independent science
of physiology. He made it a subject to be studied for its
own sake, and not merely as an adjunct lo medicine. Haller
was a manof vast and variedleaming,and'lohipi was applied
by unsympathetic critics the title of '.' thai abyss of learning."
His portrait, as shown in Fig. 54, givte t^e impression of
a somewhat pompous and. overbearing personality. He
was egotistical, self-complacent, and possessed of great
self-esteem. The assurance in the inerranc)' of his own
conclusions was a marked characteristic of Haller's mind.
While he was a good observer, his own wOrk showing con-
scientious care in observation, he was not a good interpreter,
and we are to recollect that he vigorously opposed the idea
of development set forth by Wolff, and we must also recog-
nize that his researches formed the chief starting-point of an
erroneous conception of \'itality.
.\s \crwom points out, Haller's own experiments upon
the phenomena of irritability were exact, but they were
misinterpreted by his followers, and through the molding
influence of others the attempted explanation of their mean-
ing grew into the conception of a special vital force belong-
ed byGoOglc
162 BIOLOGY AND ITS MAKERS
ing to living organisms only. In its most complete form,
this idea provided for a distinct dualism between living and
lifeless matter, making all vital actions dependent upon the
708-177;.
operation of a mystical supernatural agency. This assump-
tion removed vital phenomena from the domain of clfar
scientific analysis, and (ora long time e,\ercis;td a retarding
influence u[X)n the i>rogrcss of physiologj'.
;dbyGOOglC
THE RISE OF PHYSIOLOGY 183
His chief service of permanent value was that he brought
into one work all the facts and the chief theories of physiology
carefully arranged and digested. This, as has been said,
made physiology an independent branch of science, to be
pursued for itself and not merely as an adjunct to the study
of medicine. The work referred to is his Elements of Physi-
ologj- (Elemenla Physiologies Corporis Humani, 1758), one
of the noteworthy books marking a distinct epoch in the
progress of science.
To the period of Haller also belongs the discovery of
oxygen, in 1774, by Priestley, a discovery which was destined
to have profound influence upon the subsequent de\elopment
of physiology, so that even now physiology consists largely
in tracing the way in which oxygen enters the body, the
manner in which it is distributed to the tissues, and the vari-
ous phases of vital activity ihal il brings about within the
living tissues.
Charles Bell.— The period of Haller may be considered
as extending beyond his lifetime and as terminating when the
influence of Mijller began to be felt. Another discovery com-
ing in the closing years of Haller's period marks a capital
advance in physiol<^. I refer to the discovery of Charles
Bell [1774-1842) showing that thener\-e .'ibersof the anterior
roots of the spinal cord belong to the motor type, while those
of the posterior roots belong to the sensory type.
This great truth was arrived at theoretically, rather than
as the result of experimental demonstration. It was first ex-
jx)unded by Bell in 181 1 in a small essay entitled Idea oj a
New Anatomy of the Brain, which was printed for private
(listribmion. It was expanded in his papere, beginning in
1821, and published in the Philosophical Transactions of
the Royal Society of London, and finally embodied in his
work on the ner\-ous system, published in 1830, At this
latter date Johannes Miiller had reached the age of twenty-
id byGoOglc
I04 BIOLOGY AND ITS MAKERS
nine, and had already entered upon his career as the lead-
ing physiolt^ist of Germany. What Bell had divined he
demonstrated by experiments.
Charles Bell (Fi(r. 55) was a surgeon of eminence; in
private life he was distinguished by " unpretending amenity,
and simplicity of manners and deportment."
Period of Johannes Hiiller. — The perio<l that mark?, the
beginning of modem physiology came next, and was due to
the genius and force of Johanni-s Miiller 1 1801-1858). Ver-
wom says of him: '"He is one of ihosL- monumental fig-
ures that the history of even,' science brings forth but once-
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THE RISE OF PHYSIOLOGY 185
They change the whole aspect of the field in which they work,
and all later growth is influenced by their labors." Johannes
Miiller was a man of ver^- unusual talent and attainments,
the possessor of a master mind. Some have said, and not
without reason, that there was something supernatural about
Miiller, for his whole appearance bore the stamp of the im-
common. His portrait, with its massive head above the broad
shoulders, is shown in Fig. 56, In his lectures his manner
and his gestures reminded one of a Catholic priest. Early in
his life, before the disposition to devote himself lo science
became so overwhelming, he thought of entering the priest-
hood, and there clung lo him all his life some marks of
the holy profession. In his highly intellectual face we find
"a trace of severity in his mouth and compressed lips, with
the expression of most earnest thought on his brow and eyes,
and with the remembrance of a finished work in e\er)-
wrinkle of his countenance."
This extraordinary man exercised a profound influence
upon those who came into contact with him. He excited
almost unbounded enthusiasm and great veneration among
his students. Thej' were allowed to work close by hi.s side,
and so magnetic was his personality that he stimulatc-d them
[jowerfully and succeeded in transmitting to them some
of his own menial qualities. As professor of physiology in
lierlin, Mullcr trained many gifted young men, among whom
were Briicke (1819-1892), Du Bois-Reymond (1818-1896),
and Helmholtz ( 182 1- 1894), who became distinguished
scholars and professors in German universities. Helmholtz,
speaking of Miiller's influence on students, paid this tribute
to the grandeur of his teacher: " Whoever comes into contact
with men of the first rank has an altered scale of values in life.
Such intellectual contact is the most interesting event that
life can offer."
The [articular service of Johannes MuUer to science was
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160 BIOLOGY AXD ITS MAKERS
to make physiologj" broadly comparative. So comprehensive
was Kis grasp upon the subject that he gained for himself
the title of the greatest physiologist of modem times. He
brought together in his great work on the physiology of man
not only all that had been previously made known, carefully
sifted and digested, but a great mass of new information,
which was the result of his own investigations and of ihose
of his students. So rigorous were his scientific standards
that he did not admit into this treatise anything which had
been untested either by himself or by some of his assistants
or students, \'envom says of this monumental work, which
appeared in 1833, under the title Handbuch der Physiologie
des ifenschen: "This work stands to-day unsurpassed in
the genuinely philosophical manner in which the materbl,
swollen to vast proportions by innumerable special researches,
was for ihe first time sifted and elaborated into a unitary
picture of ihe mechanism within Ihe living organism. In this
respect the Handbuch is to-day not only unsurpassed, but
unequalled,"
Miiller was the most accurate of observers; indeed, he is
the most conspicuous example in Ihe nineteenth century of a
man who accomplished a prodigious amount of work all of
which was of the highest quality. In physiology he stood on
broader lines than had ever been used before. He employed
every means at his command — experimenting, the obsen-a-
tion of simple animals, the microscope, the discoveries in
physics, in chcmistrj', and in psychology.
He also introduced into physiology the p.inciples of psy-
chology, and it is from the period of Johannes Miiller that
we are to associate recognition of the close connection be-
tween the oj>erations of the mind and the physiology of the
brain that has come to occupy such a conspicuous position
at the present lime.
Miiller died in 1858, having nachcd the age of fifty seven,
;dbyGOOglC
11
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■ *^L''^
^^" fj
Flo. 56.— Johannes Muller, 1801-1858,
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l8R BIOLOGY AND ITS MAKKRS
but his inHucncc was prolonged through the teachings of his
students.
Physiology after Muller.
Ludwig. — Among the men who handed on the torch of
Muller, Ludwig (Fig. 57) must be mentioned. Although
he «as never a pupil of Muller. he galhere<i stimulus from
his writings and researches. For many years he kitured
in the Univer.sitv of Keipsic. attracting to that university
high-minded, eager, an.l gifted young men. who receivai
;dbyGOOglC
THE RISE OF PHVSIOLOGV 189
from this great luminary of physiology by expression what
he himself had derived from contact with Miiller and his
writings. There are to-day distrihiited through the univer-
sities a number of young physiologists who stand only one
generation removed from Johannes Miiller, and who still
lahor in the spirit that was introfluced into this depart-
mt'ni of study by that great master,
Du Bois-Reymond.— Du Bois-Reymond (Fig. 58). an-
other of his distinguished pupils, came to occupy the chair
;dbyGOOglC
19° BIOLOGY AND ITS MAKERS
which MuUcr himself had filled in ihe University of Berlin,
and during the period of his vigor was in physiologj- one of
the lights of ihe world. It is no uncommon thing lo find
recently published physiologies dedicated cither lo ihe mem-
orj- of Johannes Mullcr, as in the case of that remarkable
General Physiology by Verwom ; or to Ludwig, or lo Du
Bois-Rcymond, who were in part his intellectual product.
From this disposition among physiologisls to do homage to
Miiller, we are able to estimate somewhat more closely the
tremendous reach of his influence,
Bernard. — When Miiller was twelve years old there was
bom in Sainl-Julicn, dep-arlment of the Rh6ne, Claude
Bernard, who attained an eminence as a physiologist, of which
the French nation are justly proud. Although he was little
thought of as a student, nevertheless after he came under the
influence of Magcndie, at the age of twenty-six, he developed
rapidly and showed his true metal. He exhibited great
manual dexterity in performing experiments, and also a
luminous quality of mind in interpreting his obsenations.
One of his greatest achievements in physiolt^ was the dis-
cover\' of the formation within the liver of glycogen, a sub-
stance chemically rclatc'd to sugar. Later he discoveretl the
system of vaso-molor ner\x-s that control and regulate the
caliber of the blood-vessels. Both of these discoveries as-
sisted materially in understanding the wonderful changes
that are going on within the human body. But besides his
technical researches, any special consideration of which lii^s
quite beyond the purpose of this book, he published in 1878-
1879 a work upon the phenomena of life in animals and
vegetables, a work that had general influence in extending
the knowledge of vital activities. I refer to his now classic
Le(ons siir les Phfnombnes de la vie communs aux animaux et
aux vigilaiix.
The thoughtful face of Bernard is shown in his portrait,
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THE RISE OF PHYSIOLOGY 191
Fig. 59. He was one of those retiring, silent men whose
natures are difficult to fathom, and who are so frequently
misunderstood. .\ domestic infclicit_v, that led to the separa-
tion of himself from his family, added lo his isolation and
loneliness. When touched by the social spirit he charmed
people by his personality. He was admired by the Emperor
Nai>oleon Third, through whose influence Bernard acquired
two fine laboratories. In 1868 he was elected to the
French Academy, and became thereby one of the "Forty
Immortals."
Foster describes him thus: "Tall in stature, with a fine
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19= BIOLOGY AND ITS MAKERS
presence, with a noble head, the eyes full at once of (bought
and kindness, he drew the look of obsen'ers upon him whcr-
cxer he appeared. As he walked in the streets passers-by
might bo heard to say ' I wonder who that is; he must be
some distinguished man.' "
Two Directions of Growth. — Physiology, established on
the broad foundations of Miiller, developed along two inde-
pendent pathwaj-s, the physical and the chemical. We find
a group of physiologists, among whom Weber, Liidwig,
Du Bois-Rcymond, and Helmhohz were noteworthy k-aders,
devoted to the investigations of physiological facts through
the application of measurements and records made by ma-
chinery. With these men came into use the time-markers, the
myographs, and the ingenious methods of recording blood-
pressure, changes in respiration, the responses of muscle and
nen-e to various forms of stimulation, the rate of transmission
of nerve -currents, etc.
The in\'estigation of vital activities by means of mtasiire-
ments and instrumental records has come to represent one
especial phase of modem physiolog)-. As might have been
predicted, the discoveries and extensions of knowledge re-
sulting from this kind of experimentation have been remark-
able, since it is obvious that permanent records made by
mechanical devices will rule out many errors ; and, moreover,
they afford an opportunity to study at leisure phenomena
that occupy a veiy brief lime.
The other marked line of physiolc^ical investigation has
been in the domain of chemistry, where ^\'6hlcr, Licbig,
Kiihne, and others have, through the study of the chemical
changes occurring in its body, obser\'cd the various activities
that take place within iheorganism. They have reduce<l all
tissues and all parts of the body to chemical analysis, studiitl
the chemical changes in digestion, in respiralion, elc. The
more recent observers have also made a [lariicular fi-alun- of
;dbyGOOglC
THE RISE OF PHYSIOLOGY 193
the Study of the chemical changes going on within the living
matter.
The union of these two chief tendencies into the physico-
chemical aspects of physiology has cslablishod the modem
way of looking upon vital activities. These vital activi-
ties are now regarded as being, in their ultimate analysis,
due to physical and chemical changes taking place within the
living substratum. All along, this physico-chemical idea has
been in contest with that of a duality between the body and
the life that is manifested in it. The vitalists, then, have had
many controversies with those who make their interpretations
along physico-chemical lines. We will recollect that vitalism
in the hands of the immediate successors of Haller became
not only highly speculative, but highly mystical, tending to
obscure any close analysis of vital activity and throwing
explanations all back into the domain of mysticism. Johannes
Miiller was also a vitalist, but his vitalism was of a more
acceptable form. He thought of changes in the body as
being due to vitality-— to a living force; but he did noi deny
the possibility of the transformation of this vital energj' into
other forms of energy; and upon the basis of Mtiller's work
there has been built up the modem conception that there is
found in the human body a particular transformation-form
of cnerg)*, not a mystical vital force that presides over all
manifestations of life.
The advances in physiologj-, beginning with those of
William Harvey, have had immense influence not only upon
medicine, but upon all biology. We find now the successful
and happy union between physiology and morpholog)' in the
work which is being so assiduously carried on to-day under
the title of experimental morphology.
The great names in physiology since Muller are numerous,
and perhaps it is invidious to mention particular ones; but,
inasmuch as Ludwig and Du Bois-Reymond have been
;dbyGOOglC
194 BIOLOGY AND ITS MAKERS
Spoken of, we may associate with [hem the names of Sir
^tichael Fosterand Burdon -Sanderson, in England; and of
Briicke (one of Wiillcr's disciples) and Venvorn, in Ger-
many, as modem leaders whose investigations have pro-
moted advance, and whose clear exposition of the facts and
the theories of physiology have added much to the dignity
of the science.
;dbyGOOglC
CHAPTER X
VON BAER AND THE RISE OF EMBRYOLOGY
Anatomy investigates the arrangement of organic tissues;
embryology, or the science of development, shows how they
are produced and arranged. There is no more fascinating
division of biological study. As Minot says: "Indeed, the
stories which embryology has to tell are the most romantic
known to us, and the wildest imaginative creations of Scott
or Dumas arc less startling than the innumerable and almost
incrediblu shifts of rdle and change of character which
embr\olog}' has to entertain us wilh in her histories,"
Embnology is one of the most important biological sci-
ences in furnishing clues to the past history of animals.
Ever)' organism above the very lowest, no matter how com-
pkx, begins its existence as a single microscopic cell, and
between ihal simple state and the fully formed condition
ever)' gradation of structure is exhibited. Every time an
animal is developed these constructive changes are repeated
in orderly sequence, and one who studies the series of steps
in development is led to recognize that the process of
building an animal's body is one of the most wonderful
in all nature.
Rudimentary Organs. — But, strangelyenough, the course
of development in any higher organism is not straightforward,
but devious. Instead of organs being produced in the most
direct manner, unexpected by-paths arc followed, as when
all higher animals acquire gill-clefts and many other rudi- ■
;dbyGOOglC
19^ BIOLOGY AND ITS MAKERS
nientar>' organs not adapted to their condition of life. Most
of the nidimentaT>- organs are transitoiy, and bear testimony,
as hcTcdilary survivals, to the line of anccstr)-. The)' are
clues by means of which phases in the evolution of animal
life may be deciphered.
Bearing in mind the continually shifting changes through
which animals pass in their embryonic development, one
begins to see why the aduh structures of animals are so diffi-
cult to understand. They arc not only complex; theyarealso
greatly modified. The adult condition of any organ or tissue
is the last step in a scries of gradually acquired modifications,
and is, therefore, the farthest departure from that which is
ancestral and archetyjjal. But in the process of formation
all the simpler condiiions are exhibited. If, therefore, we
wish to understand an or^n or an animal, we must follow its
development, and see it in simpler conditions, before the
great modifica lions have been added.
The tracing of the stages whereby cells merge into tissues,
tissues into organs, and determining how the organs by com-
binations build up the body, is embr)ologj-. On account of
the extended applications of this subject in biology, and the
light which il throws on all structural studies, we shall be
justified in giving its history at somewhat greater length
than that adopted in treating of other topics.
Five Historical Periods.— The story of the rise of this
interesting department of biolog)- can, for convenience, be
divided into five periods, each marked by an ad\ancc in
general knowledge. These arc: (i) the fieriod of Hancy
and Malpighi; (2) the period of Wolff; {3) the period of
Von Baer; (4) the period from Von Baer to Balfour; and
(5) the period of Balfour, with an indication of present tend-
encies, .^mong all the leaders Von Baer stands as a monu-
mental figure at the parting of the ways between the new
and the old — the sane thinker, the great obsen-cr.
;dbyGOOglC
the rise of embryology 197
The Period of Har\'ev and Malpighi
In General. — The usual account of the rise of embryol-
ogy is derived from German writers. But there is reason to
depart from their traditions, in which Wolff is heralded as its
founder, and the one central figure prior to Pander and
Von Baer.
The embryological work of Wolff's great predecessors,
Harvey and Malpighi, has been passed over too lightly.
Although these men have received ample recognition in
closely related fields of investigation, their insight into those
mysterious events that culminate in the formation of a new
animal has been rareSy appreciated. Now and then a few
writers, as Brooks and Whitman, have pointed out the great
worth of Harney's work in embryology, but fewer have
spoken for Malpighi in this connection. Koelliker, it is true,
in his address at the unveiling of the statue of Malpighi, in
his nali\e town of Crevalcuorc, in 1894, gives him well-
merited recognition as the founder of embryology, and the
late Sir Michael Foster has written in a similar vein in his
delightful Lectures on the History oj Physiology.
Honeier great was Harvey's work in embryology, I ven-
ture to say that Malpighi's was greater when considered as a
piece of observation. Harvey's work is more philosophical ;
he discusses the nature of development, and shows unusual
powers as an accurate rcasoner. But that part of his treatise
devoted to observation is far less extensive and exact than
Malpighi's, and throughout his lengthy discussions he has
the flavor of the ancients.
Malpighi's work, on the contrary, flavors more of the
modems. In terse descriptions, and with many sketches, he
shows the changes in the hen's e^ from the close of the first
day of development onward.
It is a noteworthy fact that, at the period in which he
;dbyGOOglC
I9B BIOLOGY AND ITS MAKERS
li%'ed, Malpighi could so successfully curb the tendency lo
indulge in wordy disquisitions, and that he was satisfied lo
observe carefully, and lell his story in a simple wa\'. This
quality of mind is rare. As Emerson has said: "I am im-
pressed with the fact that the greatest thing a human soul
ever does in this world is to sec somcihing, and lell ^\hat it
saw in a plain way. Hundreds of people can lalk for one
who can think, but thousands can think for one who can see.
To sec clearly is poetr>-, philosophy, and religion all in one."
But " to see" here means, of course, to interpret as well as
to obsen'e.
Although there were obser\ers in the field of embryology
before Har\ey, liiile of substantial \-alue had been produced.
The earliest attempts were vague and uncritical, embracing
only fragmcntar}' views of the more obvious features of body-
formation. Nor, indeed, should we look for much advance
in the field of embryologv- even in Haney's time. The reason
for this will become obvious when we remember that ihe
renewal of independent obser\ation had just been brought
about in the preceding ccnlurj- by Vi-salius, and that Harvey
himself was one of the pioneers in the intellectual awakening.
Studies on the development of the body are specializc-d,
involving obsenations on minute structures and recondite
processes, and must, therefore, wait upon considerable ad-
vances in anatomy and physiology. Accordingly, the science
of embr>olog>- was of late development.
Harvey. — Har\ey'5 was Ihe first attempt to make a criti-
cal analysis of the process of development, and that he did not
attain more was not owing lo limitations of his lowers of dis-
cemmenl, but to the necessity of building on the general level
of the science of his time, and, further, to his lack of instru-
ments of obf^ervation and technique. Xeverthcless, Har\cy
may be considered as having made the first independent
advance in embn.ology.
;dbyGOOglC
THE RISE OF EMBRYOLOGY 199
By clearly teaching, on the basis of his own obscirations,
the gradual formation of the body by aggregation of ils parts,
he anticifiatcd Wolff. This doctrine came to be knovvn under
the title of "epigcnesis," but Har\Ty's cpigcnesis* was not,
as Wolff's was, directed against a theory of pre-dclineation of
the parts of the embr}-o, but against the ideas of the medical
men of the time regarding the metamorphosis of germinal
elements. It lacked, therefore, the dramatic setting which
surrounded the work of Wolff in the next cenlury. Had the
doctrine of preformation been current in Harvey's lime, we
arc quite justified in assuming that he would have assailed it
as vigorously as did Wolff.
His Treatise on Generation.— Har\'cy's embryological
work was published in 1651 under the title Exercilationes de
Ceneralione Ammalium. It embraces not only obser\'ations
on the development of the chick, but also on the deer and some
other mammals. As he was the court physician of Charles I,
that sovereign had many deer killed in the park, at intervab,
in order to give Harvey the opportunity to study their devel-
opment.
As fruits of his observation on the chick, he showed the
position in which the embrjo arises within the egg, viz., in
the white opaque s\)ol or cicatricula ; and he also corrected
Aristollc, Fabricius, and his other predecessors in many par-
ticulars.
Haney's greatest predecessor in this field, Fabricius, was
also his teacher. When, in search of the best training in
medicine, Han-ey took his way from England to Italy, as
already recounted, he came under the instruction of Fa-
bricius in Padua. In 1600, Fabricius published sketches
showing the development of animals; and, again, in 1625,
si.\ years after his death, appeared his illustrated treatise on
♦ As \\'hilmaii has poinled oul, Arislollc taught cpigcnesis as clearly as
Hancy, and is, therefore, 10 be regarded as the founder of thai conception.
dbjGoogle
300 BIOLOGY AND ITS MAKERS
the development of the chick. Except ihe figures of Coitcr
(1573), those of Fabricius were the earliest published illus-
trations of the kind. Altogether his figures show develop-
mental stages of the cow, sheep, pig, galeus, scqwnt, rat, and
chick.
Hari'ey's own treatise was not illustrated. With that
singular independence of mind for which he was conspicuous,
the vision of the pupil «as not hampered by the authority of
his teacher, and, trusting only to his own sure observation
and reason, he described the stages of development as he
saw them in the egg, and placed his own construction on
the facts.
One of the earliest activities to arrest his attention in the
chick was a pulsating point, the heart, and, from this obser\a-
tion, he supposed that the heart and the blood were ihe first
formations. He says: "But as soon as the egg, under the
influence of the gentle warmth of the incubating hen, or of
warmth derived from another source, begins to pullulate,
this spot forthwith dilates, and expands like the fiupil of the
eye; and from thence, as Ihe grand center of the eg<;, the
latent plastic force brraks forth and germinates. This first
commencement of the chick, however, so far as I am aware,
has not yet been obser\ed by any one."
It is to be understood, however, that the descri]ilive ]iart
of his treatise is relatively brief (about 40 [lajjes out of 1,^0 in
Willis's translation), and that the bulk of the ic<) "exercises"
into which his work is divided i^ devoterl to comments on the
older writers and 10 discussions of the nature of the process
of development.
Thca]i]iorism, '" omiw vh-um ex m-o," tho\i^h not invented
by Harvey, wa-. broui;lil inio <ienerai use throufjh his writings.
.As usai in his day. however, it did not have its full mtxiern
significance, Wldi Harvey it meanl >iniply llial the embryos
of all animals, the viviparous as well a^ the ovi|^ar()u^, orit;-
;dbyGOOglC
I
Guliclmu* HarvcHs
J.-
Oencrfttione Araaiaiiiuu
202 BIOLOGY AND ITS MAKERS
natc in eggs, and it was directed against certain contrary
medical tlieories of the lime.
The first edition of his Generatione Animalium, London,
1G51, is provided with an allegorical frontispiece embodying
this idea. As shown in Fig. 60, it represents Jove on a
pedestal, uncovering a round box, or ovum, bearing the
inscription " ex ovo omnia," and from the box issue all forms
of living creatures, including also man.
Halpighi. — The obser\cr in cmbrjolog}' who looms into
prominence between Harvey and Wolff is Malpighi. He
supplied what was greatly needed at the time — an illustrated
account of the actual stages in the development of the chick
from the end of the first day to hatching, shorn of verbose
references and_ speculations.
His obsenations on development are in two separate
mcmoifs, both sent to the Royal Society in 1672, and pub-
lished by the Society in Latin, imdcr the titles De Formatione
Pulli in Ovo and De Oi-o Iniubalo. The two taken together
are illustrated by twelve plates containing eighty-six figures,
and the twenty-two quarto pages of text are nearly all devoted
to descriptions, a marked contrast to the 350 pages of Harvey
unprovided with illustrations.
His pictures, although not correct in all particulars, repre-
sent what he was able to see, and are ver>- remarkable for
the age in which they were made, and considering the instru-
ments of obsen-ation at his command. Thw show successive
stages from the time the embr\o is fir^l outlined, and, taken
in their entirely, they cover a wide range of stages.
His obsenations on the develo]>ment of the heart, com-
prising twenty figures, are the most com|)lete. He clearly
illustrates the aortic arches, those transitor\' structures of
such great interest as showing a phase in ancestral histor)'.
He was also the first to show by picturc-s the formation of
the hcad-folii and the neural groove, as well as Ihc brain-
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Digitized oyVjOOQlC
204
BIOLOGY AND ITS MAKERS
vesicles and eye-pockets. His delinealion of heart, brain,
and cyc-%'esiclcs are far ahead of those illustrating WolfT's
Theoria Generalionis, made nearly a hundred years later.
Fig. 6i shows a few selcctcti sketches from ihe various
plates of his cmhryological treatises, to comjiare with those of
Wolff. (Sec Fig. 63.)
The original drawings for De Ovo Jticubalo, still in pos-
session of iheRoyal Socicty.are made in pencil and red chalk,
and an examination of them shows that they far suqtass the
reproductions in finish and accuracy.
While Han'fv taught the gradual formation of jiarts,
Malpighi, from his own obscn'alions, sup|)oscd the rudiments
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THE RISE OF EMBRYOLOGY 205
of the embryo to pre-exist within the egg. He thought that,
possibly, the blood-vessels were in the form of tubes, closely
wrapped together, which b\' becoming filled with blood were
distended. Nevertheless, in the treatises mentioned above
he is vcrj' temperate in his expressions on the whole matter,
and evidently believed in the new formation of many parts.
The portrait of Malpighi shown in Fig. 62 is taken from
his life by Atli. From descriptions of his personal appear-
ance (see page 58) one would think that this is probably a
better likeness than the strikingly handsome portrait painted
by Tabor, and presented by Malpighi to the Royal Society
of London. For a reproduction of the latter see page 59.
Halpighl's Rank. — On the whole, Malpighi should rank
above Har\'ey as an embrjologist, on account of his dis-
coveries and fuller representation, by drawings and descrip-
tions, of the process of development. As Sir Michael Foster
has said: "The first adequate description of the long series
of changes by which, as they melt the one into the other,
like dissolving views, the little white opaque s[x>t in the egg
is transformed into the feathered, living, active bird, was
given by Malpighi. And where he left it, so for the most
[lart the mailer remained until even the present century.
For this reason we may speak of him as the founder of
embrv-ologj-."
The Period of Wolff
Between H2r\ey and WollT, embrjologj' had become
dominated by the lheor>- that the embr\'o exists already
preformed within the egg, and, as a result of the rise of this
new doctrine, the publications of Wolff had a different setting
from that of any of his predecessors. It is only fair to say
that to this circumstance is owing, in large ytuTt, the prom-
inence of his name in connection wilh the theory of cpigenesis.
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206 BIOLOGY AND ITS MAKERS
As wc ha\e already seen, Haney, more ihan a ccnlur)' before
the publications of Wolff, had dearly laught that develop-
ment is a process of gradual becoming. Nevertheless, Wolff's
work, as opposed to the new theory, was very imjxjrlant.
While the fads fail to support the contention that he was
the founder of epigeticsis, it is lo be remembered that he has
claims in other directions to rank as the foremost student of
embryology prior to \'on Baer.
As a preliminar)- to discussing Wolff's position, we should
bring under consideration the doctrine of preformation and
encasement.
Rise of the Theory of Pre-delineation. — The idea of pre-
formation in its first form is easily set forth. Just as when
we examine a seed we find within an embryo plantlet, so it
was supposed that the various forms of animal life existed
in miniature within the egg. The process of development
was supposed to consist of the expansion or unfolding of this
pre -formed embryo. The process was commonly illustrated
by reference lo flower -buds. " Just as already in a small bud
all the parts of the flower, such as stamens and colored petals,
are enveloped bj' the green and still unde\'eIoped sepals;
just as ihe parts grow in concealment and then suddenly
expand into a blossom, so also in Ihe development of animals,
it was thought that the already present, small but transparent
jiarts grow, gradually expand, and become discernible,"
(Hertwig.) From the feature of unfolding this was called
in the eighteenth centur}' the thcorj* of nvlulion, giving to
that term quite a different meaning from that ailached to it
at ihe present time.
This thcor)-, strange as it may seem to us now, was
founded on a basis of actual obsenation — not entirely on
speculation, .\lihough it was a product of the seventeenth
ccnturj-, from several printed accounts one is likely lo gather
the impression that it arose in the eighteenth century-, and that
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THE RISE OF EMBRYOLOGY 207
Bonnet, Hallcr, and Leibnilz were among its founders. This
implication is in part fostered by the circumstance that
Swammerdam's Biblia Nalura, which contains the germ of
the ihcorj-, was not published until 1737 — more than half a
centurj' after his death — allhough the observations for it were
completed before ilalpighi's first paper on embrjology was
published in 1672, While it is well to bear in mind that date
of publication, rather than date of obsenation, is accepted
as establishing the period of emergence of ideas, there were
other men, as Malpighi and Lceuwenhoek, contemporaries
of Swammerdam, who published in the seventeenth ccnlur>-
the basis for this theor).
Malpighi supj>osed (1672) the rudiment of the cmbr}-o to
pre-exist within the hen's egg, because he obsened evidences
of organization in the unincubaled egg. This was in the
heat of Ihe Italian summer (in July and August, as he him-
self records), and Darcsic suggests that ihe developmental
changes had gone fonvard to a considerable degree before
Malpighi opened the eggs. Be this as it may, the imperfec-
tion of his instalments and technique would have made it
verj' diflicull to see anything definitely in stages under
twenty-four hours.
In reference to his obsenations, he says ihat in the unin-
cubated egg he saw a small embrjo enclosed in a sac which
he subjected to the rays of the sun. " Fretjuently I opened
the sac with the point of a needle, so that the animals con-
tained within might be brought to (he light, nevertheless to
no purpose; for Ihe individuals were so jelly-like and so very
small that they were lacerated by a light stroke. Therefore,
it is right to confess that the beginnings of the chick pre-exist
in the egg, and have reached a higher development in no other
way than in the e^s of plants." ("Quare/>7(W/i/animainovo
pra-cxislerc, allior^mquc origincm nacta esse fateri convenit,
baud dispari ritu, ac in Plantarum ovis,")
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2o8 BIOLOGY AND ITS MAKERS
Swammcrdam (1637-1680) supplied a some^vhat belter
basis. He obscned that the parts of the butterfly, and other
insects as well, are discernible in the chr}-salis stage. .\lso,
on obser\-ing caterpillars Just before going into the pupa
condition, he saw in outline the organs of the future stage,
and verj' naturally concluded that development consists of
an expansion of alrtrady formed parts.
A new feature was introduced through the discoverj', by
Leeuwenhoek, about 1677,* of the fertilizing filaments of
eggs. Soon after, controversies began to arise as to whether
the embrj'o pre-existed in the sperm or in the egg. By
Leeuwenhoek, Hartsoeker, and others the egg was looked
upon as simply a nidus within which the sperm developed,
and ihey asserted that the future animal existed in miniature
in the sperm. These controversies gave rise lo the schools
of the animal culists, who believed the sperm to be the animal
germ, and of the ovulists, who contended for the o\-um in that
rfilc
It is interesting to follow the metajihysical speculations
which led to another aspect of the doctrine of pre-formation.
There were those, notably Swammcrdam, Lcihnilz, and
Bonnet, who did not hesitate to follow the idea lo the logical
consequence ihat, if Ihe animal germ exists preformed, one
generation after another must be encased within it. This
gave rise to the fanciful idea of encasement or cmboilcmeiil,
which was so greatly elaborated by Bonnet and, by Leibnilz,
applied to ihe development of the soul. Even Swammenlam
(who, by the way, though a masterly obsen'er, was always
a poor generalizer) conceived of the gernisof all forthcoming
generations as having been located in the common mother
Eve, all closely encased one within the other, like the boxes
of a Japanese juggler. The end of the human race was con-
* Ttic disriiviry is :ilso auribulcd lo Hamm, a medical student, and to
H.irisoeker, who ctaimed priori!)' in the discovi-Ty.
dbjGoogle
Fjc. 6j. — Plate from Wolll's Thcoria Gaitralionis (i75<)), Showing
Stuges in the Development of the Chick.
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210 BIOLOGY AND ITS MAKERS
cetved of by him as a nectssity, when ihc last germ of this
wonderful scries had been unfolded.
His successors, in efforts to compute the number of
homunculi which must have been condensed in the ovai^' of
Eve, arrived at the amazing result of two hundred millions.
Work of Wolff. — Friedrich Kaspar Wolff, as a yoimg
man of twenty-six years, set himself against this grotesque
doctrine of prc-formation and encasement in his Tlicoria
Generalionis, published in 1759. This consists of three
parts; one devoted to the development of plants, one to the
development of animals, and one to theoretical considera-
tions. He contended that the organs of animals make their
appearance gradually, and that he could actually follow their
successive stages of formation.
The figures in it illustrating the development of the chick,
some of which arc shown in Fig. 63, arc not, on the whole,
so good as Malpighi's. Wolff gives, in all, seventeen figures^,
while Malpighi published eighty-six, and his twenty figures
on the development of the heart are more detailed than any
of Wolff's. When the figures represent similar stages of
development, a comparison of the two men's work is favor-
able to Malpighi. The latter shows much better, in corrc-
sjionding stages, the series of cerebral vesicles and their rela-
tion to the optic vesicles. Moreover, in (he wider langc of
his work, he shows many things — such as the formation of
the neural groove, etc. — not includi-d in Wolff's observations.
Wolff, on the other hand, figures for the first time the prim-
itive kidneys, or "Wolfllan bodies," of which he was the
Although Wolff was able to show that developmcnl con-
sists of a gradual formation of parts, his theory of develop-
ment was entirely mystical and unsatisfactory. The fruitful
idea of germinal continuity had not yet emcrgc'd, and the
thought that the egg has inheriled an organization from
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THE RISE OF EMBRYOLOGY 211
the past was yet to be expressed. \A'oIff was, ihcrcforc, in
the same quandan.' as his predecessors when he undertook to
explain development. Since he assumed a total lack of
organization In ihe beginning, he was obliged to make devel-
opment " miraculous " through the action on Ihe egg of a
hyperphysical agent. From a total lack of organization, he
conceived of its being liflcd to the highly organized product
through the action of a " vis essetilialis corporis.'^
He returned to the problem of development later, and, in
176S-1769, published his best work in this field on the devel-
opment of the intestine.* This is a verj- original and strong
piece of obsen-ational work. While his investigations for the
Theoria Gaieralionis did not reach the level of Malpighi's,
those of the paper of 1768 surpassed them and held the posi-
tion of ihe best piece-of embr)-ological work up to that of
Pander and \'on Baer. This work was so highly appreciated
by Von Baer that he said: "It is the greatest masterpiece of
scientific observation which we possess." In it he clearly
demonstrated that the development of the intestine and its
a]»pendagcs is a true process of becoming. Still later, in
1789, he published further theoretical considerations.
Opposition to Wolff's Views. — But all Wolff's work was
launched into an uncongenial atmosphere. The great physi-
ologist Haller could not accept the idea of epigenesis, but
opposed it energetically, and so great was his authority that
the views of Wolff gained .-.o currency. This retarded
progress in the science of aumial development for more than
a half-century.
Bonnet was also a prolific writer in opposition to the ideas
of Wolff, and we should perhaps have a portrait of him
(Fig. 64) as one of the philosophical naturalists of the time.
His prominent connection with the theory of pre-delineation
* De Formaliant Inleslinarum, Nova CommerUar, Ac. Set. Petrop.,
Si, Petersburg, XII., i;68; XIII., 1769.
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2I^ BIOLOGY AND ITS MAKERS
in its less grotesque form, his tiiscoven- of (he development
of the cfTps of plant-lice without previous fertilization, his
researches on regeneration of parts in polyps and worms,
and other obsenalions place him among the conspicuous
naturalists of tlic jicriod. Ilis f^vstem of philo=ophy, which
has bec-n carefully analyzccl by Whitman, k designati'd by
ihat wriUT as a sy^lem of negations.
In iSai, J. Fr. Meckel, recognizilis the great \alue of
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THE RISF OF EMBRYOLOGY 213
Wolff's researches on ihe development of the intestines,
rescued the work from neglect and obscurity by publishing
a German translation of the same, and bringing it to the
attention of scholars. From that time onward Wolff's labor
was fruitful.
His De Formalione Inleslitiorunt rather than his Theoria
Gcneralionis embodies his greatest contribution to cmbry-
ologj. Not only is it a more fitting model of obser\'ation, but
in it he foreshadows the idea of gcrm-Iayers in the embryo,
which, under Pander and Von Baer, became the fundamental
conception in structural embryolog)'. Throughout his re-
searches both early and late, he likens the embryonic rudiments,
which precede the formation of oi^ns, to leaflets. In his
work of 1768 he described in detail how Ihc leaf-like layers
give rise to the systems of organs; showing that the nenous
sj-stem arises fii-st from a leaf-like layer, and is followed,
successively, by a flesh lajcr, Ihc \-ascular system, and lastly,
by the intestinal canal — all arising from original leaf-like
la'ycre.
In these important generalizations, although they are
verbally incorrc-ct, he reached the truth as nearly as it was
fx)ssiblc at the time, and laid the foundation of the germ-
layer theor\-.
\\'olff was a man of great power as an obscr.-er, and al-
though his influence was for a long time retarded, he should
he recognize*! as (he foremost in\'cstigator in cmbnologj'
before \on Haer.
Few Biographical Facts. — The little known of his life
is fTained through his corrcs]X)ndencc and a letter by his
amanuensis. Through personal neglect, and hostility to his
work, he could not secure a foothold in the universities of
Germany, and, in 1764, on the invitation of Catherine of
Russia, he went to the Academy of Sciences at St. Petersburg,
where he si>ent the last thirty years of his life.
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214 BIOLOGY AND ITS MAKERS
It has been impossible to discover a [xnlrait of Wolff,
although I have soughl one in various ways for several years.
The secrclary of the Academy of Sciences at St. Petersburg
writes that no portRiit of Wolff exists there, and that the
Academy will gratefully receive information from any source
regarding the existence of a porlrait of the great acade-
mician.
His sincere and generous spirit is shown in his corrc-spond-
ence with Halter, his great opponent. " And as to the matter
of contention between us, I think thus: For me, no more
than for you, glorious man, is truth of the vcr\- greatest con-
cern. Whether it chance that organic bodies emerge from
an invisible into a visible condition, or form themselves out
of the air, there is no reason why 1 should wish the one were
truer than the other, or wish the one and not the other. And
this is your view also, glorious man. We are investigating
for truth only; we seek that which is Inie. Why then should
I contend with you?" (Quoted from Wheeler.)
The Period of \'on Baek
What Johannes Miiller was for physiologj-, von Baer
was for erabryolog)- ; all subsequent growth was influenced
by his investigations.
The greatest classic in embryology is his Development of
Animals (Entu-kkelnngsgesciikhJe der Tiere — Beobachtung
find Reflexion), the first part of which was published in 1828,
and the work on the second part completed in 1834, although
it was not published till 1837. This second part was never
finished according lo the plan of Von Baer, but was issued by
his publisher, after vainly waiting for the finished manu-
script. The fmal portion, which Von Baer had withheld, in
order to perfect in some particulars, was published in 1888,
after his death, but in the form in which he left it in 1834.
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THE RISE OF EMBRYOLOGY 215
The observations for the first fart began in 1819, after he
had received a copy of Pander's researches, and co\'ered a
period of se\cn years of close devotion to the subject; and
the observations for the last part were carried on at intervals
for several years.
It is significant of the character of his Re flexionen that,
although published before the announcement of the cell-
theory, and before the acceptance of the doctrine of organic
evolution, they have exerted a molding influence upon
embryology to the present time. The position of von Baer
in embryology is owing as much to his sagacity in specula-
tion as to his powers as an observer. "Never again have
observation and thought been so successfully combined in
embiyological work " (Minot),
Von Baer was bom in 1792, and lived on to 1876, but his
enduring fame in embryology rests on work completed more
than forty years before the end of his useful life. After his
removal from Konigsberg to St. Petersburg, in 1834, he very
largely devoted himself to anthropology in its widest sense,
and thereby extended his scientific reputation into other
fields.
If space permitted, it would be interesting to give the
biography* of this extraordinar)' man, but here it will be
necessary to content ourselves with an examination of his
portraits and a brief account of his work.
Portraits.— Several portraits of von Baer showing him
at difle'rent periods of his life have been published. A very
attractive one, taken in his early manhood, appeared in
Harper's Magazine for 1898. The expression of the face is
]>oeticaI, and the picture is interesting to compare with the
more matured, sage-like countenance forming the frontispiece
* r„^i()(.^ biographical ski'tches l>y Slicda, \\'aldpycr, and othprs. we hai'e
'"" " lutobiography of Von Baer, publi5hed in 1864, for pri-
aflemard (1866) reprinted .md placed on sale.
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2l6
BIOLOGY AND ITS MAKERS
of Sticda's Lije oj Von Boer (see Fig. 65). This, perhaps
the best of all his portrails, shows him in the full devel-
opment of his powers. An examination of it impresses one
with confidence in his balance^! jud^mcnl and the thorotiijh-
ncss and profimdiiy of his mental ojieralions.
The ]>orlrail of Von ISaer at alxiut seventy years of iijjf,
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THE RISE OF EMBRYOLOGY 217
reproduced in Fig. 66, is, however, destined to be the one by
which he is commonly known to embnologisls, since it forms
the frontispiece of the gnat cooperative Handbook oj Em-
FiG. 66,— Vo:
bryology just piiblishwi under the editorship of Oskar
HcnwifT.
Von Baer's Especial Service. — Apart from special dis-
;dbyGOOglC
2l8 BIOLOGY AND ITS MAKERS
coveries, Von Baer greatly enrichttl embn-ology in three di-
rections; In the first place, he set a higher standard for all
work in ennbrj'ology, and thereby lifted the entire science to
a higher level. Activity in a great field of this kind is, with
the rank and file of workers, so largely imitative that this
feature of his influence should not be overlooked. In the
second place, he established the germ-layer theory, and, in
the third, he made embryologj' comparative.
In reference to the germ-layer theorj-, it should be recalled
that Wolff had distinctl)- foreshadowed the idea by showing
that the material out of which the embryo is constructed is,
in an early stage of development, arranged in the form of
leaf-like layers. He showed specifically that the alimentary
canal is produced by one of these sheet-like expansions fold-
ing and rolling together.
Pander, by obscnations on the chick (1817), had ex-
tended the knowledge of these layers and elaborated the
conception of Wolff. He recognized the presence of three
primary layers — an outer, a middle, and an inner — out of
which the tissues of the body are formed.
The Germ-Layers,— But it remained for Von Baer,* by
extending his obscn-ations into all the principal groups of
animals, to raise this conception to the rank of a general law
of development. He was able to show that in all animals
* It is lit more tlian [aasing interest to remember that Pander aii<l \'on
Baer were associated as friends and fellmv-slmicnts, uniier II6llinRer at
Wiiritjurg. It was partly through the influcnic of \'on Baer that Pander
came to slmly with DoliinEcr, anil look up investigations on lievelopnient.
His auiiilc private means made it possible for him to liear the cxiicnses con-
nected with llie investigation, and lo secure the sen-ices ot a fine artist for
making the ilkislralions. The ri'sull ivas a maRnillccnily illustrated treatise.
His uniliuslralcd ihcsis in Latin (1S.7) is more commonly linown. but the
illustratcil treatise in fjernian is rarer. \«n Baer did nol lalte up his re-
scanhcs st-rinusly unlil Panikr's "ere iiubli.«hcd. It is significant of their
continued bamioiiiiius relations thai Von Baer' s work is iledicaleil "An
meinen Jugenilfn-und, Dr. Christian Pander."
;dbyGOOglC
THE RISE OF EMBRYOLOGY 219
except the very lowest there arise in the course of devel-
opment leaf-like layers, which become converted into the
"fundamental organs" of the body.
Now, these elementary layers are not definitive tissues of
the body, but are embryonic, and therefore may appropriately
be designated "germ-layers." The conception that these
germ-layers are essenlially similar in origin and fate in all
animals was a fuller and later development of the germ-layer
theory, a conception which dominated embryological study
until a recent date.
Von Baer recognized four such layers ; the outer and inner
ones being formed first, and subsequently budding off a
middle layer composed of two sheets. A little later (1845)
Remak recognized the double middle layer of \'on Baer as a
unit, and thus arrived at the fundamental conception of three
layers — the ecto-, endo-,and mesoderm — which has so long
held sway. For a long time after Von Baer the aim of em-
bryologists was to trace the history of these germ-layers, and
so in a wider and much qualified sense it is to-day.
It will ever stand to his credit, as a great achievement,
that Von Baer was able to make a very complicated feature
of dc\-clopment clear and relatively simple. Given a leaf -like
rudiment, with the layers held out by the yolk, as is the case
in the hen's egg, it was no easy matter to conceive how
they are transformed into the nenous system, the body-wall,
the alimentary canal, and other parts, but Von Baer saw
deeply and clearly that the fundamental anatomical features
of the bod}' are assumed by the leaf -like rudiments being
rolled into tubes.
Fig. 67 shows four sketches taken from the plates illus-
trating von Baer's work. At A is shown a stage in the forma-
tion of the embryonic envelope, or amnion, which surrounds
the embryos of all animals above the class of amphibia. B,
another figure of an ideal section, shows that, long before the
;dbyGOOglC
220 BIOLOGY AND ITS MAKERS
day of microtomes, Von Bacr made use of sections to represent
the rclationshi])5 of his four germ-layers. Al C and D is
represented diagrammatically the way in which these layers
are rolled into tubes. He showed that the central nenous
system arose in the form of a tube, from the outer layer; the
body-wall in the form of a tube, com|x>sed of skin and muscle
layers; and the alimentary tube from mucous and vascukr
layers.
The generalization that embrj^os in development lend to
recapitulate their ancestral histor)' is frequently attributed to
Von Baer, but the qualified way in which he suggests some-
thing of the sort will not justify one in attaching this con-
clusion to his work.
Von Baer was the first to make embryology truly com-
parative, and to ix>int out its grrat value in anatomy and
zoology. By cmbryological studiL-s he rccogniztxl four types
of organization — as Cuvicr had done from the standpoint of
comparative anatomy. But, since these types of organiza-
tion have been greatly changed and subdividtxl, the imjmr-
tanccof the distinction has faded away. .-Xsa distinct break,
howe\er, with the old idea of a linear scale of being it was
of moment.
Among his c-specially noteworthy discoveries may be
mentioned that of the egg of mammals (1827), and the noto-
chord as occurring in all vertebrate animals. His discover)'
of the mammalian egg had bten preceded by Purkinje's
obsen'ations upon the germinalive six)t in the bird's epg
(■825)-
Von Baer's Rank. — Von Baer has come to be dignified
with the title of the "father of mo<iem enibrj'ology." Xo
man could have done more in his period, and it is owing to
his superb intellect, and to his talents as an observer, thai he
accomplished what he did. .\s Minol says: "Ik' wnrUitl
out, almost as fully as was [)Ossible at this time, the genesis
;dbyGOOglC
Fig. 67. — Sketches from Von Baer's Embryological Treatise (1828).
;dbyGOOglC
222 BIOLOGY AND ITS MAKERS
of all the principal organs from the germ -layers, instinctively
getting al the trulh as only a great genius could have done."
After his masterly work, ihe bcitncc of embrjoli^' could
never return to its former level; he had given it a new direc-
tion, and through his influence a period of great activity was
introduced.
The Period from \'on Baer to Balfoi'R
In the period between Von Baer and Balfour there were
great general advances in the knowledge of organic structure
that brought the whole process of development into a new
light.
Among the most important advances arc to be enumerated
the announcement of the cell-theory, the discovery of proto-
plasm, the beginning of iherccognition of germinal continuity,
and the establishment of the doctrine of organic evolution.
The Cell-Theory. — ^The generalization that the tissues of
all animals and plants are structurally composed of similar
units, called cells, was given to the world through the com-
bined labors of Schlciden and Schwann. The history of ihis
doctrine, together with an account of its being remodeled
into the protoplasm doctrine, is given in Chapter XII.
The broad -reaching effects of the cell-thcorj' may be easily
imagined, since it united all animals on the broad plane of
likeness in microscopic structure. Now for the firsi lime
the tissues of the body were analyzed into their units; now
for the first time was comprehended the nature of the germ-
layere of \'on Baer,
Among the first questions loemergc in the light of the new
researches were concerning the origin of cells in the organs,
the lissucs, and the germ-layers. The road to the investiga-
tion of these questions was already opened, and it was fol-
lowed, ste]) by step, until (he egg and the sperm came to be
;dbyGOOglC
THE RISE OF EMBRYOLOGY 223
recognized as modified cells. This position was reached,
for the egg, about 1861, when Gegenbaur showed that the
eggs of all vertebrate animals, regardless of size and con-
dition, are in reality single cells. The sperm was put in the
same category about 1865.
The rest was relatively easy: the egg, a single cell, by
successive divisions produces many cells, and the arrange-
ment of these into primary embryonic layers brings us to the
starting-point of Wolff and Von Baer. The cells, continuing
to multiply by division, not only increase in number, but also
undergo changes through di\'ision of physiological labor,
whereby certain groups are set apart to perform a particular
part of the work of the body. In this way arise the various
tissues of the body, which arc, in reality, similar cells per-
forming a similar function. Finally, from combinations of
tissues, the organs arc formed.
But the egg, before entering on the process of develop-
ment, must be stimulated by the union of the sperm with the
nucleus of the egg, and thus the starting-point of every animal
and plant, above the lowest group, proves to be a single cell
with protoplasm derived from two parents, ^^'hile questions
regarding the origin of cells in the body were being answered,
the foundation for the cmbryological study of heredity was
also laid.
Advances were now more rapid and more sure; flashes of
morphological insight began to illuminate the way, and the
facts of isolated observations began to fit into a harmonized
whole.
Apart from the general advances of this period, men-
tioned in other connections, the work of a few individuab
requires nolicc.
Rathkc and Remak were engaged with the broader aspects
of enibryolog;-, as well as with special investigations. From
Rathkc's rc-scarchcs came great ad\*anccs in the knowledge of
;dbyGOOglC
224 BIOLOGY AND ITS MAKERS
the development of insects and other invertebrates, and Remak
is notable for similar work with the vertebrates. As already
mentioned, he was ihc t"irst to recognize the middle layer as
a unit, through which the three germ-layers of later embry-
ologisis emerged into the literature of the subject.
Koellikcr, 1817-1905, the veteran embnologist, for so
many years a professor in the University of Wurzburg, carried
on investigations on the segmentation of the egg. Besides
work on the invertebrates, later he followed with care the
development of the chick and the rabbit; he encompassed
the whole field of cmbryolt^y, and published, in 1861 and
again in 1876, a general treatise on vertebrate embryologj*,
of high merit. The portrait of this distinguished man is
shown in Chapter VIII, where also his services as a hislologist
are recorded,
Huxlej' took a great step toward unifying the idea of germ-
layere throughout the animal kbgdom, when he maintained,
in 1849, that the two cell-layers in animals like the hydra
and oceanic hydrozoa correspond to the ectoderm and
endoderm of higher animals.
Kowale^-sky (Fig. 68) made interesting discoveries of a
general hearing. In 1866 he showed the practical identity,
in the early stages of de\'elopment, between one of the lowest
vertebrates (amphio.xus) and a tunicate. The latter up to
that time had been considered an invertebrate, and the effect
of Kowalevsky's obscn'alions was to break down the sharply
limited line supposed to e.xist between the invertebrates and
the vertebrates. This was of great infiuencc in subsequent
work. Kowalevsky also founded the generalization that all
animals in development jmss through a gastrula stage — a
doctrine associated, since 1874, with the name of Haeckel
under the title of the gastrica theory.
Beginning of the Doctrine of Germinal Continuity.—
The conception that there is unbroken continuity of germinal
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THE RISE OF EMBRYOLOGY
225
substance between all living organisms, and that the egg and
ihe sperm are endowc-d with an inherited organization of
great complexity, has become the basis for all current theories
of heredity and de\clo[iment. So much is involved in this
conception that, in the present de'cadc, it has been dc-signated
(Whitman) "the central fact of modem biology." The first
clear expression of il is found in Virchow's Cellular Pa-
thology, published in 1S58. Il was not, however, imtil the
period of Balfour, and through the work of Fol, ^'an Benedcn
(chromosomfs, 1883), Bovcri, Hcrtwig, and others, that the
great imjKjrtance of this conception began 10 be appreciated,
and came to be woven into the fundamental ideas of de-
velopment.
Influence of the Doctrine of Organic Evolution. — This
doctrine, although founded in its modem sense by I-amarck
in the early |tart of the ninetc'enth century', lay dormant until
Darwin, in 1859, brought a new feature into its discussion
;dbyGOOglC
226 BIOLOGY AND ITS MAKERS
by emphasizing the factor of natural selection. The general
acceptance of the doctrine, which followed after fierce oppo-
sition, had, of course, a profound influence on embr^-ol<^'
The latier science is so intimately concerned with the gene-
alogy of animals and plants, that the newly accepted doc-
trine, as affording an explanation of thisgenealog)-, was the
thing most needed.
The development of organisms was now seen in the light
of ancestral history", rudimentary organs began to have
meaning as hereditary survivals, and the whole process of
development assumed a different aspect. This doctrine
supplied a new impulse to ihe Interpretation of nature at
large, and of the embryological record in particular. The
meaning of the embrj-ological record was so greatly em-
phasized in the period of Balfour that it will be commented
upon under the next division of our subject.
The period between Von Baer and Balfour proved to be
one of great importance on account of the general advances
in knowledge of all oi^nic nature. Obser\'alions were
moving toward a better and more consistent conception of
the structure of animals and plants. A new comparative
anatomy, more profound and richer in meaning than Cu-
vicr's, was arising. The edifice on tlie foundation of \'on
Bacr's work was now emerging into recognizable outlines.
The Period of Balfolr, with an Indication of Presfnt
Tendenciks
Balfour's Masterly Work.^ — ^Thc workers of this period
inherited all the accumulations of previous efforts, and the
lime was ripe for a new step. Obser\-ations on the develop-
mt-nt of diiTerent animals, vertebrates and invertebrates, had
accumulati.'d in great number, but they were scattered
through technical yieriodicalfi, transactions of learned societies,
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THE RISE OF EMBRYOLOGY
227
monographs, etc., and (here was no compact science of em-
bryology with definite outHncs. Balfour reviewed all this
mass of information, digested it, and molded it into an organ-
ized whole. The results were published in the form of two
volumes with the title of Comparative Embryohgy. This
book of "almost priceless value" was given to the world in
1880-1881. It was a colossal undertaking, but Balfour was
Fig. 69.
a phenomenal worker. Before his untimely death at the age
of thirty -one, he had been able lo complete this work and to
produce, besides, a large number of technical researches.
The period of Balfour is lakcn arbitrarily in this volume as
beginning about 1874, when he published, with Michael
Foster, Tlu Elements 0} Embryology.
His University Career. — Balfour (Fig, 69) was bom in
;dbyGOOglC
228 BIOLOGY AXD ITS MAKERS
1851. During his days of preparation for the university he
was a good student, but did not exhibit in any marked way
the powers for which later he became distinguished. At
Cambridge, his distinguished teacher, the late Sir Michael
Foster, recognized his great talents, and encouraged him to
begin work in embrjologw His labors in this field once
begun, he threw himself into it with great intensity. He rose
rapidly to a professorship in Cambridge, and so great was
his enthusiasm and earnestness as a lecturer that in seven
years " voluntarj- attendance on his classes a(l\-anced from
ten to ninety." He was also a stimulator of research, and at
the lime of his dealh there were twenty students engaged in
his laborator)- on problems of development.
He was distinguished for jiersonal attractiveness, and
those who met him were impressed with his great sincerity,
as well as his personal charm. He was welcomed as an
addition to the select group of distinguished scientific men of
England, and a gnat career was jjredicled for him. Huxley,
when he felt the call, at a great personal sacrifice, to lay aside
the more rigorous pursuits of scientific research, and to devote
himself to molding science into the lives "of the people, said
of Balfour: "He is the only man who can earn,* out my
work."
His Tragic Fate. --Hut that was not destined to be. The
stor}' of his tragic end need be only referred to. After com-
pleting the prodigious labor on the Comparative Embry-
ology he went to Switzerland for recui)er,ition, and met his
death, with that of his guide, by slipping from an Alpine
height into a chasm. His death occurred in July, 1882.
The memorial edition of his works fills four ([Uarlo vol-
umes, but the " Con'.jwirative Kmbryolog)- " is Balfour's
monument, and will give him enduring fame. It is not only
a digest of the work of others, but contains also Keneral-
considerations of a far-seeing quality. He saw develop-
ed byGoOglc
THE RISE OF EMBRYOLOGY 229
mental processes in the light of the hypothesis of organic
wolution. His speculations were suflicicnlly resened, and
nearly always luminous. It is significant of the character
of this work lo say that the speculations conlatncxl in the
papers of Ihe rank and file of cmbr)ological workers for more
than two decades, and often fondly believed to be novel,
were for the most part anticipated by Balfour, and were also
better expressed, v.ilh belter qualifications.
The reading of ancestral histon- in the stages of dc'elop-
ment is such a characteristic feature of the cmbrj^ological
work of Balfour's period that some obscnations concerning
it will now be in place.
Interpretation of the Embryological Record.— Perhaps
the most impressive feature of animal dn-elopmcnt is the
series of similar changes through which all pass in the embryo.
The higher animals, especially, exhibit all stafjcs of organiza-
tion from the unicellular fertilized oiTJm to the fully formc-d
animal so far removed from it. The intermediate changes
constitute a long record, the [xjssibilily of interpreting which
has been a stimulus to its careful examination.
Meckel, in 1821, and later Von Bacr, indicated Ihe close
similarity between cmbn,-onic stapes of widely diiTerent
animals; Von liacr, indeed, confessed that he was unable lo
distinguish fxisilively between a reptile, a bird, and a mam-
malian embryo in certain early stages of growth.
In addition to this similarity, which is a constant feature of
the embr>-ological record, there is another one that may be
equally significant; viz., in the course of embrj'onic history,
sets of rudimentarj'Oi^ns arise anddisappe-ar. Rudiment-
ary- toelh make their appearance in the embryo of the whale-
bone whale, but they arc transiton,- and soon disappear with-
out having been of service to the animal. In the embryos
of all higher vertebrates, as is well known, gill-clefts and
gill-arches with an appropriate circulation, make their ap-
;dbyGOOglC
23° BIOLOGY AND ITS MAKERS
pcarancc, but disappear long before birth. These uidica-
tions, and similar ones, must have some meaning.
Now whatever qualities an animal exhibits after birth
are attributed to heredity. May it not be that all the inter-
mediate stages are also inheritances, and, therefore, represent
phases in ancestral history? If they be, indeed, clues to
ancestral conditions, may we not, by patching together our
observations, be able to interpret the record, just as the his-
tory of ancient peoples has been made out from fragments
in the shape of coins, vases, implements, hieroglyphics, in-
scriptions, etc.?
The Recapitulation Theory. — ^The results of reflection in
this direction led to the foundation of the recapitulation
theory, according to which animals are supposed, in their
individual development, to recapitulate to a considerable
degree phases of their ancestral history. This is one of the
widest generalizations of embrj'ologj'. It was suggested in
the writings of Von Bacr and Louis Agassiz, but received its
first clear and complete expression in 1863, in the writings of
Fritz Mullcr,
Although the course of events in development is a record,
it is, at best, only a fragmeniari- and imperfect one. Many
stages have been dropped out, others arc unduly prolonged
or abbreviated, or appear out of chronological order, and,
besides this, some of the structures have arisen from adapta-
tion of a particular organism to its conditions of develop-
mer.t, and are, therefore, not ancL'stral at all, but, as it were,
recent addiiions to the text. The interpretation becomes a
diflicuU task, which requires much balance of judgment and
profound analysis.
The recapitulation theory- was a dominant note in all
Balfour's sjn'Cula lions, and in that of his contemj)orar}' and
fellow -student ^Marshall. It has received its most sweeping
application in the works of Krnst Haeckel.
;dbyGOOglC
THE RISE OF EMBRYOLOGY
231
Widely spread throughoul recent literature is to be noted
a reaction against the too wide and unrescn-ed applicalion
of this doctrine. This is naturally to be expected, since it
is the common tendency in all fields of scholarship to demand
a more critical estimate of results, and to undergo a reaction
from the tarlier crude and sweeping conclusion?.
Xfarly all problems in anatomy and stnictural zoology
arc apj>roacht'd from the cmbr)-oiogical side, and, as a con-
sequence, the work of the great army of anatomists and
;dbyGOOglC
2,12 BIOLOGY AND ITS MAKERS
zoologists has been in a measure enibryol<^ical. Many of
ihem have produced beautiful and important researches, but
thework is loo extended to admit of review in this connection,
Oskar Hertwig, of Berlin (Fig. 70}, is one of the repre-
sentalivc embrjologists of Europe, while, in this country-,
lights of the first magnitude are Brooks, Minot, Whitman,
E. B. Wilson, and others.
.\lthough no attempt is made to review the researches of
the .ecent period, we cannot ]kiss entirely without mention
the discovery of chromosomes, and of (heir reduction in the
ripening of the egg and in the formation of sperm. This has
thrown a IIockI of light on ihc phenomena of f ertilizal ion, and
has led to the recognition of chromosomes as probably Ihc
bearers of heredity. Tlic nature of fertilization, investigated
by Fol, O. Hertwig, and others, formed the starling-point for
a series of brilliant discoveries.
The cmbrjological investigations of the laic Wilhelm Hi.i
(Fig. 71) are also dcser\'ing of especial notice. His luminous
researches on the development of the nen'ous syslem, the
origin of nerve fibers, and his analysis of the development of
the human cmhrj'o arc all very im]H>rtant.
Recent Tendencies. Experimental Embryology. — Soon
after the publication of Halfours great work on " Comiai^tive
Embrjology,'' a new tendency in research began to appt-ar
which led onward to the csfablishmcnt of e.\|>erimenlal cm-
br>olog>-. All previous work in this field had been concemwl
with the structure, or architecture, of organisms, but now the
pliysiological side began 10 receive atteniion. Whitman has
stalc<i with great aptness the interdepend ence of the.-e two
lines of work, as follows: "Morpholog;' raises the (|U(.-stion,
How came the organic mechanism into existence? flas it
had a history, reachiog its present stage of perfection through
a long series of gradations, the llrst term of wliieh w;i> a
relatively simple stage? The enibryological hislorj is tracal
;dbyGOOglC
dbjGoogle
234 BIOLOGY AND ITS MAKERS
out, and the paIa°ontoIogical records arc searched, until the
evidence from both sources establishes the fact that the organ
or organism under study is but the summation of modifica-
tions and elaborations of a relatively simple primordial. This
point settled, physiolog)' is called upon to complete the slor;-.
Have the functions remained the same through the ?cries?
or have they undergone a series of modifications, differentia-
tions, and improvements more or less parallel with the mor-
phological series ? "
Since physiolog)' is an experimental science, all questions
of this nature must be investigated with the help of experi-
ments. Organisms undergoing development have been sub-
jected lo changed condilions, and iheir res]X)nse5 to various
forms of stimuli have been notwl. In the rise of experimental
embryology we lia\e one of the most promising of the recent
departures from the older aspects of the subject. The results
already attaini-d in ihis attractive and suggestive field make
too long a story to justify its telling in this volume. Roux,
Herbst, Ix)eb, Morgan, E. B. Wilson, ami many olhers have
contributed lo tlie growth of ihis new division of embrj'olc^y.
Good reasons have been adduced for believing that qualitative
changes lake place in the protoplasm as development pro-
ceeds. And a curb has been put u|X)n that "grtat fault of
embryolog}-, the tendency to explain any and every ojjeration
of development as merely the result of inheritance." It has
been demonstrated that surrounding conditions have much
to do with individual development, and that the course of
events may depend largely upon stimuli coming from with-
out, and not exclusively on an inherited tendency.
Cell-Lineage. — Investigations on the structural side liave
reached a high grade of perfection in studies on cell-lineage.
The theoretical conclusions in the germ-layer theory- are
based upon the assumpiion of identity in origin of the differ-
ent layers. But the lack of agreement among obseners, cspc-
;dbyGOOglC
THE RISE OF EMBRYOLOGY 235
cially in reference to the origin of the mesoderm, niade it
necessary to study more closely the early developmental stages
before the establishment of the gcrm-laycrs. It is a great
triumph of exact observation that, although continually
changing, the consecutive history of the individual cells has
been followed from the beginning of segmentation to the time
when the germ-layers arc established. Some of the beautifully
illustrated memoirs in this field arc highly artistic,
Blochman (1882) was a pioneer in obsen-alions of ihb
kind, and, following him, a number of American investigators
have pursued studies on cell-lineage with great success.
The researches of Whitman, Wilson, Conklin, Kofoid, Lillie,
Mead, and Castle have given us the historj- of the origin of
the germ-layers, cell by cell, in a variety of animal forms.
These studies have showTi that there is a lack of uniformity
in the origin of at least the middle layer, and therefore
there can be no strict homology of its deri\ati\'es. This
makes it apparent that the earlier generalizations of the
germ-layer theory were too sweeping, and, as a result, the
theory is retained in a much modified form.
Theoretical Discussions. — Certain theoretical discus-
sions, based on embrj'ological studies, have been rife in recent
years. And it is to be recognized without question that dis-
cussions regarding heredity, regeneration, the nature of the
de\elopmcntal process, the question of inherited organiza-
tion within the egg, of germinal continuity, etc., have done
much to advance the subject of embryolog)'.
Embryology is one of the three great departments of
biolog}' which, taken in combination, supply us with a knowl-
edge of living forms along lines of structure, function, and
development. The cmbrjological method of study is of in-
creasing importance to comparative anatomy and physiology.
Formerly it was entirely structural, but it is now becoming
also experimental, and it will therefore be of more service to
;dbyGOOglC
=3^ BIOLOGY AND ITS MAKERS
physiologj'. While it has a slriclly technical side, the science
of embryology must always remain of interest to intelligent
people as embracing one of the most wonderful processes
in nature — the development of a complex organism from the
sin^e-celled condition, with a panoramic representation of
all the intermediate stages.
;dbyGOOglC
CHAPTER XI
THE CELL THEORY- SCHLEIDEN, SCHWANN,
SCHULTZE
The recognition, in 1838, of iho fact that all the various
tissues of animals and plants arc constructed on a similar plan
was an important step in the rise of biolog)-. It was progress
along the line of microscopical obsonation. One can readily
understand that the structural analysis of organisms could
not be completed until their elementary parts had been dis-
covered. When these units of structure were discovered
they were called cells — from a misconception of their nature^ —
and, although the misconception has long since been cor-
rected, they still retain this historical but misleading name.
The doctrine that all tissues of animals and plants arc
composed of aggregations of thc-se units, and the derivatives
from the same, is known as the cell-lheory. It is a general-
ization uhich unites all animals and plants on the broad plane
of sim.ilitude of structure, and, when we consider it in the
light of its consequences, it stands out as one of the great
scientific achievements of the nineteenth century. There is
little danger of overestimating the importance of this doctrine
as tending to unify the knowledge of living organisms.
Vague Fore shado wings of the Cell-Theory. — In attempt-
ing to trace the growth of this idea, as based on actual observa-
tions, we fir?l encounter vague foreshadowings of it in the
seventeenth and the eighteenth centuries. The cells were
seen and sketched by many early obseners, but were not
understood.
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238 BIOLOGY AND ITS MAKERS
As long ago as 1665 Robert Hookc, the great English
microscopist, obscned the cellular construction of cork, and
describee! it as made up of " little boxes or ceils distinguished
from one another," He made sketches of the appearance of
this plant tissue; and, inasmuch as the drawings of Hooke
are the earliest ones made of cells, thcj' possess especial in-
> (1665).
terest and consequently are reproduced here. Fig. 72, taken
from the Micrograpliia, shows this earliest drawing of Hooke.
He made thin sections with a sharp penknife; "and ujxjn
examination they wore found to be all cellular or porous in
the manner of a honeycomb, but not so regular."
Wc must not com])letely overlook the fact that .Arislollc
(384-322 B.C.) and Galen (130-20C A.n.), those profound
thinkers on anatomical structure, had reached the theoretical
position "that animals and plants, complex as they may
;dbyGOOglC
THE CELL THEORY
239
appear, are yet composcc] of comparalively few elementary
pans, frequcnily repeated"; but we arc not especially con-
cerned with the remote histon' of the idea, so much as with
the principal steps in its development after ihe beginning of
microscopical obserx'ations.
Pictures of Cells in the Seventeenth Century. — The
sketches illustrating the microscopic observations of Malpighi,
■ Lceuwcnhoek, and Grew show so many pictures of the ccl-
H lular construction of plants that one who views them for the
H first time is struck with surprise, and might readily exclaim:
H "Here in ihe seventeenth century wc have the foundation of
H the cell-theory." But these drawings were merely faitliful
H representations of the appL-arance of the fabric of plants;
Digitized ov Google
240 BIOLOGY AND ITS MAKERS
the cells were not thought of as uniform elements of organic
architecture, and no theory resulted. Jt is true that Malpighi
understood that the ceUs were separable " utricles," and that
plant tissue was the result of their union, but this was only
an initial step in the direction of the cell-theory, which, as
wc shall see later, was founded on the supposed identity in
development of cells in animals and plants. Fig. 73 shows
a sketch, made by Malpighi about 1670, illustrating the micro-
scopic structure of a plant. This is similar to the many
drawings of Grew and Lecuwenhock illustrating the struc-
ture of plant tissues.
Wolff. — Nearly a centurj' after the work of Malpighi, we
find Wolff, in 1759, proposing a theory regarding the organ-
ization of animals and plants leased upon obser\'ations of
their mode of development. He was one of the most acute
scientific observers of the ])criod, and it istobc noted that his
conclusions regarding structure were all founded upon what he
was able to see; while he gives some theoretical conclusions
of a purely speculative nature, lA'olff was careful to keep
these separate from his observ'ations. The purpose of his
investigations was to show that there was no preformation
in the embrj-o; but in getting at the basis of this question, he
worked out the identity of structure of plants and animals
as shown by their development. In his famous publication
on the- Thcon' of Dei'clopment ( Theoria Genrrationis) he used
both jilanls and animals.
Huxlc}' epitomizes Wolff's views on the de\'tlopmeni of
elementary jjarts as follows : " Ever}' organ, he says, is com-
posi-d at first of a little mass of clear, viscous, nutritive fluid,
which ]X)sscsses no organization of any kind, but is at most
comjx)scd of globules. In this semifluid mass caviliis
{Blaschen, Zellcn) are now (lcvelope<i: these, if they remain
round or jMalvRonal, become the subsequent cells: if they
elongate, the vessels; ami the process is identically the same.
;dbyGOOglC
THE CELL THEORY 241
whether it is examined in the vegetating point of a plant, or
in the young budding organs of an animal."
Wolff was contending against the doctrine of pre-fomu-
tion in the embrj-o (see further under the chapter on Embry-
ology), but on account of his acute analysis he should be
regarded, perhaps, as the chief forerunner of the founders of
the cell-theoiy. He contended for the same method of de-
velopment that was afterward emphasized by Schleidcn and
Schwann. Through the opposition of the illustrious physi-
delist HaUcr his work remained unappreciated, and was
finally forgotten, until it was revived again in 1812,
We can not show that Wolff's researches had any direct in-
fluence in leading Schleiden and Schwann to their announce-
ment of the ccll-thcorj'. Nevertheless, i( stands, intellectually,
in the direct line of development of that idea, while the \iews
of Hallcr upon the construction of organized beings are a
side-issue. Haller declared that "the solid parts of animals
and vegetables have this fabric in common, that their ele-
ments are either fibers or unorganized concrete," This
formed the basis of the iiber-theorj-, which, on account of the
great authority of Hallcr in physiology, occupied in the
accumulating writings of anatomists a greater place than
the views of Wolff.
Bichal, although he is recognized as the founder of his-
tolog)-, made no original observations on the microscopic units
of the tissues. He described very minutely Ihe membranes
in Ihe bodies of animals, but did not employ the microscope
in his investigations.
Oken.— In the work of the dreamer Oken ("1779-1851),
the great representative of the German school of "Nalur-
philosophie," we find, about 1808, a very noteworthy sute-
nienl to the effect that "animals and plants are throughout
nothing else than manifoldly divided or repeated vesicles, as
I shall prove anatomically at the proper time." This is
;dbyGOOglC
242 BIOLOGY AN'D ITS MAKERS
apparently a concise stalemenl of Ihe cell-idea prior to
Schleiden and Schwann; but we know that it was not
founded on obsenation. Oken, as was his wont, gave rein
to his imagination, and, on his part, the idea was entirely
theoretical, and amounted to nothing more than a lucky guess.
Mailer's fiber-theorj' gave place in the last part of the
eighteenth centurj' to the theor\* that animals and plants are
composed of globules and formless material, and this globular
thcor)- was in force up to the time of the great gcncralizalion
of Schleiden and Schwann. It was well expounded by ^^ilne-
Edwards in 1823, and now we can recognize that at least
some of Ihe globules which he described were the nucleated
cells of later writers.
The Announcement of the Cell-Theory. — We are now ap-
ptiaching the time when the ccll-theorj- was to be launched,
During the first third of the nineteenth century there had ac-
cumulated a great mass of separate obsenations on th(
roscopic structure of both animals and plants. For sc\-eral
'Cars botanists, in particular, had been obsen'ing and writing
about cells, and interest in these structures was increasing.
We must clearly recognize the fact that for some time prior
i 1838 the cell had come to be quite universally recognized
as a constantly recurring element in vegetable and animal
s, though little importance was attached to it as an
element of organization, nor had its character been clearly
detcTmined " (Tyson).
Then, in 1838, came the "master-stroke in gencTaliza-
tion " due to the combined labors of two friends, Schleiden
and Schwann. But, although these two men are recognized
as co-founders, they do not share honors equally; the work
of Schwann was much more comprehensive, and it was he
who first used the term ccU-thcorj-, and entered upon the
theoretical considerations which placed the theory before the
scientific world.
;dbyGOOglC
THE CELL THEORY 243
Schlciden was educated as a lawyer, and began the prac-
tice of that profession, but his tasle for natural science was
so pronounced that when he was (wcnty-scvcn years old
he deserted law, and went back lo the university to study
medicine. After graduating in medicine, he devoted himself
mainly lo botany. He saw clearly that the greatest thing
needed for the advancement of scientific botany was a study
of plant organization from the standpoint of development.
Accordingly he entered upon this work, and, in 1837, arrived
at a new view regarding the origin of plant cells. It must
be confessed that this new \-iew «as foimded on erroneous
observations and conclusions, but it was revolutionary', and
sensed to pro\'oke discussion and to awaken ohser\-ation.
This was a characteristic feature of Schleiden's influence upon
botany. His work acted as a ferment in bringing about new
activity.
The discover)- of the micieus in plant cells by Robert
Brown in 1831 was an imfjortant preliminary step lo the work
of Schleidcn, since the latter seized uyren the nucleus as the
starting-i>oint of new cells. He changed the name of the
nucleus to cytoblast, and sup[X)sed that the new cell started
as a small clear bubble on one side of the nucleus, and by
continued expansion grew inlo the cell, the nucleus, or
cytoblast, becoming encased in the cell-wall. All this was
shown by \agcli an<l other botanists to be wrong; yet, curi-
ously enough, it was through the help of these false obscna-
tions that Schwann arrived at his general conclusions.
Schleidcn was acquainted with Schwann, and in October,
18,58, while the two were dining together, he told Schwann
about his observations and theories. He mentioned in par-
ticular the nucleus and its relationship to the other parts of
the cell, Schwann was immediately struck with the simi-
larity between the obscn-ationsof Schlciden and certain of his
own upon animal tissues. Together they went to his labo-
;dbyGOOglC
244 BIOLOGY AND ITS MAKERS
raloryand examined ihe sections of thedorsal cord, the par-
ticular structure upon which Schwann had been working.
Schleidcn at once recognized the nuclei in this structure as
being similar to those which he had observed in plants, and
thus aided Schwann to come to the conclusion that ihe ek-
mcnls in animal tissues were practically identical with those in
])lant (issues.
Schwann. — The personalities of the co-founders of ihc
cell-theory are interesting. Schwann was a man of gentle,
pacific disposition, who avoided all controversies aroused by
his many scientific discoveries. In his portrait (Fig. 74)wcsee
a man whose striking qualities are good-will and benignity.
His friend Hcnlegivesthisdescriptionof him: "He was a man
of stature below the medium, with a beardless face, an almost
infantile and always smiling expression, smoolh, dark-brown
hair, wearing a fur-trimmed dressing-gown, living in a poorly
lighted room on the second floor of a restaurant which was
not c\en of the second class. He would pass whole da\s
there without going out, with a few rare books around him,
and numerous glass vessels, retorts, vials, and tubes, simple
apparatus which he made himself. Or I go in imagina-
tion to the dark and fusty halls of the Anatomical Institute
where we used to work till nightfall by the side of our exrcllent
chief, Johann Xlilllcr. We took our dinner in the e\cning,
after the English fashion, so that we might enjoy more of the
advantages of daylight,"
Schwann drew part of his stimulus from his great master,
Johannes Muller. Ho was associated with him as a student,
first in (he Univereity of Wijrzburg, where Miillcr, with rare
discernment for recognizing genius, selected Schwann for
especial favors and (or close personal friendship. The influ-
ence of his long association with Muller, the gri'atest of all
trainers of anatomists and physiologists of the nineteenth
century, must have been very uplifting. A few years later.
;dbyGOOglC
THE CELL THEORY
245
Schwann found himself al the University of Berlin, where
MuUcT had been called, and he became an assistant in the
master's laboratory. There he gained the powerful stimulus
of constant association with a great personality.
In 1839, just after the publioilion of his work on the cell-
theory, Schwann was called to a professorship in the Univer-
sity of Louvain, and after remaining there nine year^, was
IransfLTred lo the University of Lifege. He was highly re-
;dbyGOOglC
246 BIOLOGY AND ITS MAKERS
spcctcd in the university, ami led a useful life, although after
going to Belgium he published only one work— that on the
uses of the bile. He was recognized as an adept expcri-
FiG. 75. — M. ScHLEiDtN, 1804-188
menterand dcmonslrator,and "clearness, order, and method"
are designated as the characteristic qualities of his teaching.
His announcement of the cell-theor)- was his most impor-
;dbyGOOglC
THE CELL THEORY 247
tant work. Apart from that his best-known conlribulions to
science are: experiments iifx)n spontaneous generation, his
discovcrv- of the " sheath of Schwann," in nenc fibers, and
his theory of fermentation as produced by microbes.
Schleiden.— Schlciden (Fig. 75) was quite different in
temperament from Schwann. He did not have the fine self-
control of Schwann, but was quick to take up the gauntlet
and enter upon controversies. In his caustic replies to his
critics, he indulged in sharp personalities, and one is at times
inclined to suspect that his early experience as a lawyer had
something to do with his method of handling opposition.
With all this he had correct ideas of the object of scientific
study and of the methods to be used in its pursuit. He in-
sisted upon obsenation and experiment, and upon the neces-
sity of studying the development of plants in order to under-
stand their anatomy and physiologv'. He sjx^ks scornfully
of the botany of mere species-making as follows:
" Most people of the world, e^en the most enlightened, arc
still in the habit of regarding the botanist as a dealer in bar-
barous I^tin names, as a man who gathers flowers, names
them, dries them, and wraps ihem in paper, and all of whose
wisdom consists in determining and classifying this hay
which he has collected with such great pains,"
Although he insisted on correct micthods, his ardent nature
led him to champion conclusions of his own before they were
thoroughly tested. His great influence in the development
of scientific botany lay in his earnestness, his application of
new methods, and his fearlessness in drawing conclusions,
which, although frequently wrong, formed the starting-point
of new researches.
Let us now examine the original publications upon which
the cell-lheon- was founded.
Scbleiden's Contribution. — Schleiden's paper was par-
ticularly directed to the question, How does thecefl originate?
;dbyGOOglC
348 BIOLOGY AND ITS MAKERS
uid was published in Miillcr's Arckiv, in 183S, under the
German lillo of Ueber Phylogenesis. As slalixi above, the
cell had been recognized for some years, but the question of
its origin bad not been investigated. Schlciden says : " 1 may
omit alt historical introduction, for, so far as I am acquainted,
no direct obsenations exist at present U]K>n (he developmert
of the cells of plants."
He then goes on to define his view of the nucleus (cyto-
blast) and of the development of the cell around it, saying:
" As soon as the cytoblasts have attained their full size, a
delicate transparent vesicle arises ujxjn their surface. This
is the young cell." As to the position of the nucleus in the
fully developed cell, he is very- explicit: "It is evident," he
says, "from the foregoing that thecytoblast can never lie
free in the interior of the cell, but is always enclosed in the
cell-wall," etc.
Schleiden fastened these errors ujmn the cell-lht.x>r\', since
Schwann relied upon his obsenalions. On another point of
prime im|x>rtance Schleiden was wrong: he regarded all new
cdl-formation as the formation of " cells within cells," as dis-
tinguished fromcell-division.aswc now know it to lake place.
Schleiden made no attempt to elaborate his views into a
comprehensive ccU-lheor)', and therefore his connc-clion as
a co-founder of this great generalization is chiefly in i>aving
the way and giving the suggestion to Schwann, which enabled
the latter to establish the theorj. Schleiden's |)a|«;r occupies
some thirty-two pages, and is illustrated by two plates. He
was thirty-four years old when this jxiper was published, and
directly aftenvard was called to the ])ost of adjunct professor
of botany in the University of Jena, a [losition which with
promotion to the full professorship he occupied for twenty-
three years.
Schwann's Treatise. — In 18(8, Schwann also announced
his cell- theory in a concise form in a German scientific period-
id byGoOglc
THE CELL THEORY 249
ical, and, later, to the Paris Academy of Sciences; but it was
not till 1839 that the fully illustrated account was published.
This treatise with the cumbersome title, "Microscopical
Rc-searches into ihe Accordance in the Siructure and Growth
of Animalsand Plants" (Mikrascopische Untersuchungeniiber
(lie Uebereinstimmung in der Structur und dent Wachsthum
der Thiers und Pfiamen) takes rank as one of the great classics
in biology. It fills 215 octavo pages, and is illustrated with
four plates.
" The purpose of his researches was to prove the identity
of structure, as shown by their development, between animals
and plants." This is done by direct romiiarisons of the ele-
mentary' parts in the two kingdoms of organic nature.
His writing in the "Microscopical Researches" is clear
and philosophical, and is divided into three sections, in the
first two of which he confines himself strictly to descriptions
of obser\-ations, and in the third part of which he enters upon
a i)hiIosophical discussion of the significance of the observa-
liona. He comes to the conclusion that "the elementarj-
[Kirts of all tissues arc formed of cells in an analogous, though
very diversilied manner, so that it may be asserted that there
is one universal principle of development for the elementary
fjarts of organisms, however different, and that this principle
is the formalion of cells,"
It was in this treatise also that he made use of the term
cell-thc-ory, as follows : " The development of the proposition
that there exists one genera! principle for the formation of all
organic productions, and that this principle is the formation
of cells, as well as the conclusions which may be drawn from
this projK>sition, nia\' be comprised under the term ceU-thfory,
using it in its more extended signification, while, in a more
limilc-d sense, by the theory of cells we understand whatever
may be inferred from this proposition with respect to the
[)o\vcrs from which these phenomena resuU,"
;dbyGOOglC
250 BIOLOGY AND ITS MAKERS
One comes from the reading of these two contributions
to science with the feeling that it is really Schwann's cell-
theon-, and that Schlciden helped by lighting the way that
his fellow-worker so successfully trod.
Modification of the Cell-Theory. — The form in which the
cell-theory was given to the world by Schleiden and Schwann
was very imperfect, and, as already pointed out, it contained
fundamental errors. The founders of the thcorj- attached
too much importance to the cell-wall, and they described the
cell as a hollow cavity bounded by walls that were formed
around a nucleus. They were wrong as to the mode of the
development of the cell, and as to its nature. Nevertheless,
the great truth that all parts of animals and plants arc built
of similar units or structures was well substantiated. This
remained a permanent part of the theory, but all ideas re-
garding the nature of the units were profoundly altered.
In order to perceive the line along which the chief modifi-
cations were made we must take account of another scientific
advance of about the same period. This was the discovery
of protoplasm, an achievement, which takes rank with the
advances of greatest im]X)rtance in biologj', and has proved
to be one of the great events of the nineteenth centur>'.
The Discovery of Protoplasm and its Effect on the Cell-
Theory. — In 1835, before the announcement of the cell-
theor}', living matter had been observed by Dujardin. In
lower animal forms he noticed a semifluid, jelly-like sub-
stance, which he designated sarcodc, and which he described
as being endowed with all the qualities of life. The same
semifluid substance had previously caught the attention of
some observers, but no one had as yet announced it as the
actual living f>an of oi^nisms. Schlciden had seen it and
called it gum. Dujardin was far from appreciating the full
importance of his discover)', and for a long time his descrip-
tion of sarcode remained separate; but in 1846 Hugo von
;dbyGOOglC
THE CELL THEORY 251
Mohl, a botanist, obsened a similar jelly-like substance in
plants, which he called jilant schieim, and to which he attached
the name protoplasma.
The scientific world was now in the position of recogniz-
ing lining substance, which had been announced as sarcode
in lowiT animals, and as protoplasm in plants; but there
was as j'et no clear indication that these two substances
were practically identical. Gradually there came stealing
into the minds of obseners the suspicion that the sarcode of
the zoologists and the protoplasm of the botanists were one
and the same thing. This proposition was definitely main-
tained by Cohn in 1850, though with him it was mainly
theoretical, since his obsenat ions were not sufficiently ex-
tensive and accurate to support such a conclusion.
Eleven years later, however, as the result of extended
researches, Max Schullze promulgated, in 1861, the proto-
plasm doctrine, to the effect that the units of organization
consist of little masses of protoplasm surrounding a nucleus,
and that this protoplasm, or living substance, is practically
identical in both plants and animals.
The effect of this conclusion upon the cell-theorj' was
rcvolutionar\\ During the lime protoplasm was being ob-
ser\'cd the cell had likewise come under close scrutiny, and
naturalists had now an extensive collection of facts upon
which to found a theorj'. It has been shown that many
animal cells have no cell-wall, and the final conclusion was
inevitable that the essential part of a cell is the semifluid
living substance that resides within the cavity when a cell-
wall is present. JIoreo\-er, when the cell-wall is absent, the
protoplasm is the "cell." The position of the nucleus was
also determined to be within the living substance, and not,
a? Schleiden had maintained, within the cell-wall. The
definition of Max Schultze, that a cell is a globule of proto-
plasm surrounding a nucleus, marks a new era in the cell-
ed byGoOglc
252 BIOLOGY AXD ITS MAKERS
theory, m which the original generalization became consoli-
dated with the protoplasm doctrine.
Further Modifications of the Cell-Theory. — The reformi-d
cell-theory was, however, destined to undergo further rrodifi-
cation, and to become greatly extended in its application.
At first the cell was regarded merely as an element of struc-
ture; then, as a supplement lo this restricted view, came the
recognition that it is also a unit of physiolog)', viz., that all
physiological activities lake place within the cell. Matters
did not come to a rest, however, with the recognition of thi-se
two fundamental aspects of the cell. The importance of the
cell in development also took firmer hold uj«n the minds of
anatomists after it was made clear thai both the egg and its
fertilizing agents are modiiicd cells of the i:)arent's body. It
was necessary to comprehend this fact in order to get a clear
idea of the origin of cells within the body of a multicellular
organism, and of the relation between the primonlial element
and the fully developed tissues. Finally, when obsen-ers
found within the nucleus the bearers of hereditar\- (|ualilies,
they began to realize that a careful study of the behavior of
the cell elements during de\-elopment is ni-cesssiry for ihe
investigation of heredilarj- transmissions.
A statement of the cell-lheor)' at the prt-sent limi', ihcn,
must include these four conceptions: the cell as a unit of
structure, the cell as a unit of physiological activity, llie cell
as embracing al! herediiarj- qualities within il^ >ub>Kiiici-,
and the cell in the historical development of the oi;.;;inism.
Some of these relations may now be more fully illusiralwi.
Origin of Tissues. ^Thc egg in which all organism^alxne
the very lowest begin, is a single cell having, imderihe micro
scope, the appearance shown in I-'ig. 76. .^fier fertili/^ition,
this divides rejiealedly, and many cohering cells ri->ulL The
cells arc at first similar, but as they incre-.ise in number, and
as dcvclo]»men( [irocccds, they grow (lilTirenl, and certain
;dbyGOOglC
THE CELL THEORY
253
groupsareset apart to pi-'iform particular duties. The divi-
sion of physiological labor which arises at this time marks
the beginning of separate tissues. Jt has been demonstrated
over and over that all tissues are compxjsed of cells and cell-
products, though in some instances ihey are much modified.
The living cells ain be seen even in bone and cartilage, in
which they are separated by a lifeless matrix, the latter being
the product of cellular activity.
Fig. 77 shows a stage in the development of one of the
mollusks just as the differentiation of cells has commenced.
The Nucleus.— To the earlier observers the protoplasm
appeared to be a structureless, jelly-like mass containing
granules and vacuoles; but closer accjuaintance with it has
shown that it is in reality very complex in structure as well
as in chemical composition. It is by no means homogeneous;
adjacent parts are different in properties and aptitudes. The
nucleus, which is more readily seen than other cell elements,
Digitized ov Google
254 BIOLOGY AN'D ITS MAKERS
was shown lo be of great imponancc in cell-life — to be a
structure which lakes the lead in cell division, and in general
dominates the rest of the protoplasm.
Chromosomes. — After dyes came into use for staining the
protoplasm (1868), it became evident that certain parts of it
stain deeply, while other parts stain faintly or notatall. This
led to the recognition of protoplasm as made up of a densely
staining portion called chromatin, and a faintly staining por-
■^r-
tion designated achromaljn. This means of making different
parts of protoplasm visible under the microscope led to im-
portant results, as when, in 1883, it was discovered that the
nucleus contains a definite number of small (usually rod-
shaped) bodies, which become evident during nuclear divi-
sion, and play a wonderful part in that process. These bodies
take the stain more deeply than other components of the
nucleus, and arc designated chromosomes.
.\ttcntion having been directed to these little bodies,
continued obscnations showed that, although they var^- in
;dbyGOOglC
THE CELL THEORY
255
number — commonly from Iwo to twcnly-four — in different
pans of animals and pbnls, ihcy are, ncverihelcss, of the
same number in all the cells of any particular plant or ani-
Fic. 7S.— Highly Magnified Tissue Cells from the Skin of a
Salamander in an At-tive State of Growth. Dividing cells with
chromosomes are shown at a. h, and c,. (After Wilson.)
mal. As a conclusion to this kind of observation, il needs
to be said that the chromosomes are regarded as the actual
bearers of hcreditarj- fjualities. The chromosomes do not
;dbyGOOglC
256 BIOLOGY AND ITS MAKERS
show in resting-slagcs of the nucleus; their substance is
present, but is not aggregated into (he form of chromosomes.
Fig. 78 shows tissue celb, some of which arc in the divid-
ing and olhers in the restinf;-*lage. The nuclei in process of
jk^.j|B^
jmi\
. j^* . JBl.
w
G H
1
->"> WXl^.
■'•■ ■>,»,
division exhibit the rod-like chromosomes, as shown at a,
h, and <-.
Centrosome. — The discovery (1S76) of a minute s]x>t of
deejily staining protoplasm, usually just outside the nuclear
;dbyGOOglC
THE CELL THEORY
257
membrane, is another illustration of ihc complex structure
of the cell. Although the ccntrosomc, as this s|X)t is called.
has been heraldc-d as a dynamic agent, there is not complete
agreement as to its purpose, hut its presence niakcvs it necess-
sarj' to include il in the defmition of a cell.
The Cell in Heredity, — The problems of inheritance, in
so far as they can be elucidated by structural studies, have
come to be recognized as problems of cellular life. But we
cannot understand what is im|)lied by this conclusion without
referring lo the behavior of the chromosomes during cell-
division. This is a very complex process, and ^^aries some-
what in different tissues. We can,
however, with the help of Fig. 79,
describe what takes place in a typical
case. The nucleus does not divide
directly, but the chromosomes congre-
gate around the equator of a spindle
ID) formed from the achromatin ; they
then undergo division lengthwise, and
migrate lo the poles (£, F, G), after
which a ]«irtition wall is formed divid-
ing the cell. This manner of division
of the chromosomes secures an equable
[Mirtition of the protoplasm. In the
case of fertilized eggs, one-half of the
chromosomes are derived from the
sperm and one-half from the egg.
Hach cell thus contains hereditar)'
substance derived from both mater-
nal and [latemal nuclei. This is briePiV the basis for rc-
gartling inheritance as a phenomenon of cell-life.
.\ diagram of the cell as now understoo<l fFig. 8o) will
be helpful in showing how much the conception of the cell
has changed since the lime of Schleiden and Schwann.
;dbyGOOglC
258 BIOLOGY AND ITS MAKERS
Definition. — The definition of Verwom, made in 1895,
may be combined with this diagram: A cell is "a body con-
sisting essentially of protoplasm in its general form, including
the unmodified cytoplasm, and the specialized nucleus and
ccntrosomc; while as unessential accompaniments may be
enumeraltd: (i) the cell membrane, (2) starch grains, (3)
pigment granules, (4) oil globules, and {5) chlorophyll gran-
ules," No definition can include all variations, but the one
quoted is excellent in directing attention to the essentials —
to protoplasm in its general form, and the modified proto-
plasmic parts as distinguished from the unessential accom-
paniments, as cell membrane and cell contents.
The defmilion of Venvom was reached by a scries of
steps representing the historical ad\-ancc of knowledge regard-
ing the cell. Schlcidcn and Schwann looked ujxin the cell
as a hollow chamber ha\'ing a cell-wall which had been
formed around the nucleus; it was a great step when
Schultzc defined the cell in terms of living substance as "a
globule of protoplasm surrounding a nucleus," and it is a
still deeper le\el of analysis which gi\es us a discriminating
definition like that of Venvom.
When we are brought to realize that, in large [)art, the
questions that engage the mind cf the biologist have their
basis in the study of cells, we are ready to appreciate the force
of the statement that the establishment of the cell-theory
was one of the great events of the nineteenth century, and,
further, that it stands second to no iheor}', with the single
exception of that of organic evolution, in advancing bio-
logical science.
;dbyGOOglC
CHAPTER XII
PROTOPLASM, THE PHYSICAL BASIS OF LIFE
The recognition of the r61e that protoplasm plays in the
living world was so far-reaching in its results that we take
up for separate consideration the history of its discovei y. Al-
though it is not yet fifty years since Max Schultze established
the protoplasm doctrine, it has already had the greatest
influence upon the progress of biology. To the consideration
of protoplasm in the previous chapter should be added an
account of the conditions of its discover^', and of the person-
ality and \iews of the men whose pri\ilege it was to bring
the protoplasm idea to its logical conclusion. Before doing
so, however, we shall look at the nature of protoplasm
itself.
Protoplasm. — This substance, which is the seat of all
vital activity, was designated by Huxley " the physical basis
of Hfc," a graphic expression which brings before the mind the
central fact that life is manifested in a material substratum
by which it is conditioned. All that biologists have been able
to discover regarding life has been derived from the observa-
tion of that material substratum. It is not difficult, with the
help of a microscope, to get a view of protoplasmic activity,
and that which was so laboriously made known about i860
is now shown annually to students beginning biology.
Inasmuch as all living organisms contain protoplasm,
one has a wide range of choice in selecting the plant or the
aninr.al upon which to make obscr^•ations.
V.'e may, for illustration, take one of the simplest of animal
organisms, the amceba, and place it under the high powers
;dbyGOOglC
2t>0 BIOLOGY AND ITS MAKERS
of the microscope. This little animal consbts almost entirely
of a lump of living jelly. Within the living substance of
which its body is composed all the vital activities character-
istic of higher animals are going on, but they are manifested
in simpler form. These manifestations differ only in degree
of development, not in kind, from those we sec in bodies of
higher organisms.
We can watch the movements in this amceba, deter-
mine at first hand its inherent qualities, and then draw up
a sort of catalogue of its vital properties. We notice an
almost continual flux of the viscid substance, by means of
which it is able to alter its form and to change its position.
This quality is called that of contractility. In its essential
nature it is like the protoplasmic movement that takes place
in a contracting muscle. We find also that the substance
of the amceba responds to stimulations — such as touching
it with a bristle, or heating it, or sending through it a light
electric shock. This response is quite indepi-ndent of the
contractility, and by physiologists is designated the property
of being irritable
By further observations one may determine that the sub-
stance of the amatia is receptive and assimilative, that it is
respirator}-, taking in o.xygen and giving off carbonic dioxide,
and that it is also secretorv-. If the amoeba be watched
long enough, it may be sec-n to undergo division, thus produc-
ing another individual of its kind. We say, therefore, that it
exhibits the ]X)\ver of reproduction. All these properties
manifi-slcd in close association in the amceba arc exhibited
in the bodies of higher organisms in a greater degree of
perfection, and also in separation, particular organs often
Ijeing sL-1 apart for the performance of one of these [)ar-
ticulur functions. We should, however, bear in mind that
in the simple protoplasm of the amceba is found the germ of
all the activities of ihc higher animals.
;dbyGOOglC
THE PHYSICAL BASIS OF LIFE 2t»
It will be convenient now lo turn our attention to the
microscopic examination of a plant that is sufBciently trans-
parent lo enable us to look within its living parts and observe
the behavior of protoplasm. The first thing that strikes one
is the continual activity of the living substance within the
boundaries of a particular cell. This mo\'ement sometimes
Frij. 8i. — (A) Rotation of Protoplasm in the Cells of Nitella.
(B) Highly Magnified Cell of a. Tradescantia Plant, Showing
Circulation of Protoplasm. (After Sedgwick and Wilson.)
takes the form of rotation around the walls of the cell (Fig.
8i ^1), In other instances the protoplasm marks out for itself
now paths, giving a more complicated motion, called circula-
tion (Fig. 81 B). These movements are the result of chemi-
cal changes taking place within the protoplasm, and they are
usually to be observed in any plant or animal organism.
Under the most favorable conditions these movements, as
seen under the microscope, make a perfect torrent of un-
ceasing activity, and introduce us to one of the wonderful
sights of which students of biology have so many. Huxley
;dbyGOOglC
262 BIOLOGY AND ITS MAKERS
(with slight verbal alterations) says: "The spectacle afforded
by the wonderful energies imprisoned within the compass of
the microscopic cell of a plant, which we commonly regard
as a merely passive organism, is not easily forgotten by one
who has watched its movement hour by hour without pause
or sign of weakening. The possible complexity of many
other organisms seemingly as simple as the protoplasm of
the plant just mentioned dawns upon one, and the compari-
son of such activity to that of higher animals loses much
of its startling character. Currents similar to these have
been observed in a great multitude of very different plants,
and it is quite uniformly believed that they occur in more
or less perfection in all young vegetable cells. If such be
the case, the wonderful noonday silence of a tropical forest
is due, after all, only to the dullness of our hearing, and could
our ears catch the murmur of these tiny maelstroms as they
whirl in the innumerable myriads of living cells that con-
stitute each tree, we should be stunned as with the roar of a
great city."
The Essential Steps in Recognizing the Likeness of
Protoplasm in Plants and Animals
Dujardin. — This substance, of so much interest and im-
[wrlancc lo biologists, was first clearly described and dis-
tingiiisheti from olher viscid substance, as albumen, by Fdlix
Dujardin in 1S35. ^"^h the substance and the movements
therein had been seen and reconled by others: by Rosel
von Rosenhof in 1755 in the proteus animalcule; again in
1772 by Corti in chara; by Mayen in 1877 in Vallisnieria;
and in 1831 by Robert Brown in Tradescantia. One of these
records was for the animal kingdom, and three were for
plants. The obser.'ations of Dujardin, however, were on a
(h'fferent ]t]ane from those of the earlier raluralisls, and he
;dbyGOOglC
THE PHYSICAL BASIS OF LIFE 263
is usually credited with being ihc discoverer of protoplasm.
His researches, moreover, were closely connected with the
development of the ideas regarding the r61e played Jn nature
by this living substance.
Dujardin was a quiet modest man, whose attainments and
service to the progress of biology have usually been under-
rated. He was bom in 1801 at Tours, and died in i860 at
Rcnnes. Being descended from a race of watchmakers, he
received in his youth a training in that craft which cultirated
his natural manual dexterity, and, later, this assisted him in
his manipulations of the microscope. He had a fondness for
sketching, and produced some miniatures and other works
of art that showed great merit. His use of colors was very
effective, and in 1818 he went to Paris for the purpose of
perfecting himself in painting, and with the intention of
becoming an artist. The small fmancial returns, however,
"led him to accept work as an engineer directing the con-
struction of hydraulic work in SWan," He had already
shown a love for natural science, and this led him from engin-
eering into work as a librarian and then as a teacher. He
made field obsen-ations in geolt^' and botany, and com-
menced publication in those departments of science.
About 1834 he began to devote his chief efforts to
microscopic work, toward which he had a strong inclination,
and from that time on he became a zo&logist, with a steadily
growing recognition for high-class observation. Besides his
technical scientific papers, he wrote in a popular vein to
increase his income. Among his writings of this type may be
mentioned as occupying high rank his charmingly written
"Rambles of a Naturalbt" {Promenades d'un Naturaiiste,
1838).
By 1840 he had established such a good record as a sci-
entific investigator that he was called to the newly founded
University of Rennes as dean of the faculty. He found him-
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264 BIOLOGY AN'D ITS MAKERS
self in an atmosphere of jealous criticism, largely on account
of his being clc\atccl lo the station of dean, and after two
years of discomfort he resigned the deanship, but retained
his position as a professor in the university. He sc'cured a
residence in a retired s|X)t near a church, and lived there
simply. In his leisure moments he talked frequently with
the priests, and became a devout Catholic.
His contributions to science cover a wide range of subjects.
In his microscopic work he discovered the rhizoiKtds in 1834,
and the study of their structure gave him the key lo that of
the other protozoa. In 1835 he visited the Mediterranean,
where he studied the oceanic foraminifera, and demonstrated
that they should be grouped with the protozoa, and not, as
had been maintaim-d up lo that time, ivith the mollusca.
It was during the prosecution of these researches that he
made the obser^■a1ions upon sarcode that are of jtarticular
interest to us.
His natural histor}' of the infusoria (1841) makes a vol-
ume of 700 pages, full of original observations and sketches.
He also inventi-d a means of illumination for the microscojR-,
and wrote a manual of microscopic obsenalion. .^mong the
ninety-six publiaitions of F^ujardin listixl by Professor Joubin
there arc seven general works, twenty relating lo the protozoa,
twenty-four lo geology, three to botanj-, four to physics,
twenty-five to arthropods, eight to worms, etc., etc. But as
Joubin says: "The great modesty of Dujaniin alJowwl him
to sec published by others, without credit to himself, numer-
ous facts and obsenations which he had established." This
failure to assert his claims accounts in jjarl for the inadequate
recognition that his work has received.
No portrait of Dujardin was obtainable jirior to 1898.
Somewhat earlier Frofi-ssor Joubin, who succeeded other
occufianls of the chair which DujanUn held in the University
of Rcnnes, found in the possession of his descendants a
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THE PIIVSICAL BASIS OF LIFE 265
portrait, which he was permitted to copy. The earliest re-
production of this picture to reach this country- came to the
writer through the courtesy of Professor Joubin, and a copy
of it is roprcsenlcd in Fig. 82. His picture bespeaks his per-
sonality. The quiet re'inement and sincerity of his face are
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266 BIOLOGY AN'D ITS MAKERS
evident. Professor Joubin published, in rpoi (Archives de
Parasitologic), a biographical sketch of Dujardin, with sev-
eral illustrations, including this [wrtrail and another one
which is very interesting, showing him in academic costume.
Thanks to the spread of information of the kind contained
in that article, Dujardin is coming inlo wider recognition,
and will occupy the historical position to which his researches
entitle him.
It was while studying the protozoa that he began to take
particular notice of the substance of which their bodies are
composed; and in 1835 he described it as a living jelly
endowed with all the qualitiis of life. He had seen ihc same
jelly-like substance exuding from the injured parts of worms,
and recognized it as the same material that makes the body
of protozoa. He observed it very carefully in the ciliated
infusoria — in Parameccium, in Vorticella, and other forms,
but he was not satisfied with mere microscopic observation
of its structure. He tested its solubility, he subjected it to
the action of alcohol, nitric acid, potash, and other chemical
substances, and thereby distinguished it from albumen,
mucus, gelatin, etc.
Inasmuch as this substance manifestly was soft, Dujardin
proposed for it the name of sarcodc, from the Greek, meaning
jo//. Thus wc see that the substance protoplasm was for
the firet lime brought very definitely to the attention of nat-
uralists through the study of animal forms. For some lime it
occupied a position of isolation, but ultimately became recog-
nized as being identical with a similar substance that occurs
in plants. .\X the time of Dujardin's discover)-, sarcode was
su]>]X}sed to be peculiar to lower animals; it was not known
that the same substance made the living part of alt animals,
and it was owing mainly to this circumstance that the full
recognition of its im[x)rlance in nature was delayed.
The fact remains that the first careful studiL-su]X)n sarcode
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THE PHYSICAL BASIS OF LIFE
267
were due lo Dujardin, and, iherefore, Wf muj.1 include him
among Ihe founders of modem biolog)-.
Purkinje. — The obscn-ations of the Bohemian invcsli-
gator Purkinje (1787-1869) form a link in the chain of events
leading up lo the recognition of protoplasm. Athough
Purkinje is especially remembered for other scientific coiitri-
Fig. 83.— PvRKiNjE, 1787-1869.
butions, he was the first (o make use of the name protoplasm
for living mailer, by applying it lo the formalive substance
within the eggs of animals and within the cells of the embryo.
His porlrait is not frequently seen, and, therefore, is included
here (Fig, S3), to give a more complete series of pictures of
the men who were directly connected wilh the dn'elopment
of the protoplasm idea. Purkinje was successively a pro-
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a68
BIOLOGY AND ITS MAKERS
fcssor in the univcrsilies o[ Breslau and Prague. His ana-
tomical laboralon' at Breslau is notable as being one of the
earliest (1825) open to students. He went to Prague in
1850 as professor of physiolog)'.
Von Mohl.— In 1846, ele\en years after the discovery of
Dujardin, the eminent botanist Hugo von Mohl (1805-1872)
designated a particular part of the living contents of the vege-
table cell by the term protoplasma. The viscid, jelly-like
substance in plants had in the mean time come to be kno^.m
under the expressive term of ))lant " schldm." He distin-
guished the lirmer mucihif^inous and granular constituent,
found just under the cell membrane, from the water)' ccU-sap
that occupies the interior of the cell, li was to the former
part that he ga\e the name ])rotoplasma. Previous to this,
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THE PHYSICAL BASIS OF LIFE 269
the botanist Niigcli had studied this living substance, and
perceived that it was nitrogenous matter. This was a dis-
tinct step in advance of the vague and indefinite idea of
Schleiden, who had in rcalily noticed protoplasm in 1838,
but thought of it merely as gum. The highly accom])lished
investigator Nageli (Fig. 84) niade a great place for himself
Fig. 85.
805-1873.
in botanical investigation, and his name is connected with
several fundamental ideas of biolog)'. To Von Mohl, how-
ever, belongs the crtdit of having brought the word proto-
plasm into general use. He stands in the direct line of
development, while I'urkinje, who first employed the word
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27© BIOLOGY AND ITS MAKERS
protoplasm, stands somewhat aside, but his name, neverthe-
less, should be connected with the establishment of the
protoplasm doctrine.
Von Mohl {Fig. 85) was an important mati in botany.
Early in life he showed a great love for natural science, and
as in his day medical instruction afforded the best oppor-
tunities for a man with scientific tastes, he entered upon that
course of study in Tubingen at the age of eighteen. He took
his degree of doctor of medicine in 1823, and spent several
years in Munich. He became professor of physiologj' in
Bern in 1832, and three years later was transferred to
Tubingen as professor of botany. Here he remained to the
end of his life, refusing invitations to institutions elsewhere.
He never married, and, without the cares and joys of a
family, led a solitary and uneventful life, dc\otfd to botan-
ical investigation.
Cobn. — After Von Mohl's studies on "plant schicim"
there was a general movement toward the conclusion that
the sarcode of the zoSlogisls and the protoplasm of the bot-
anists were one and the same substance. This notion was in
the minds of more than one worker, but it is pcrhajis to Fer-
dinand Cohn {1828-1898) that the credit should be given
for bringing the question to a head. After a study of the
remarkable movements of the active spores of one of the
simplest ])lanls (protococcus), he said (hat vegetable proto-
plasm and animal sarcode, "if not identical, must be, at
any rate, in the highest degree analogous substances "
(Geddes).
Cohn (Fig. 86) was for ni'arly forty years ]>rofc5sor of
botany in the University of Rrcslau, and during his long life
as an investigator greatly advanced the knowledge of bac-
teria. His statement referred (o above was made when he
was twenty-two years of age, and ran too far ahrad of the
evidence then accumulated; it merely anticipated the com-
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THE PHYSICAL BASIS OP LIFE
271
inp period of the acceptance oE the conclusion in its full
signilicancc.
De Bary. — \\ c find, ihen, in the middle years of the
nineteenth century the idea launched that sarcode and pro-
toplasni arc identical, but it was not yet definitely established
ihat ihc Barcode of lower animals is the same as the living
substance of the higher ones, and there was, therefore, lacking
an essential factor to the conclusion that there is only one
general form of living matter in all organisms. It took
ano'.her ten years of investigation to reach this end.
The most important contributions from the botanical side
during this period were the si)k'ndid researches of Dc Bary
(Fig. 87) on the myxomycetcs, published in i85q. Here the
resemblance between sarcode and yirotojilasm "as brought out
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272
BIOLOGY AND ITS MAKERS
with great clearness. The myxnmvcctes arc, in one condition,
masses of vegetable protoplasm, the mo\enifnts and other
characteristics of which were shoivn to resemble strongly
those of the protozoa. De Barb's great fame as a botanist
has made his name widely known.
In 1858 Virchow also, by his extensive studies in the
patbolog}' of living cells, added one more link to the chain
thai was soon lo Ix- recognized as encircling the new domain
of modem biology.
Schultze. — As the culmination of a long period of work,
Max Schultzf, in jH(n, pbced the conception of the identity
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THE PHYSICAL BASIS OF LIFE 2/3
between animal sarcode and vegetable protoplasm upon an
unassailable basis, and therefore he has received the title of
"the falher of modem biologj-," He showed that sarcode,
which was supposed to be confined to the lower invertebrates,
is also present in the tissues of higher animals, and there ex-
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V
274 BIOLOGY AND ITS MAKERS
hibits the same properties. The qualities of contractility and
irritability were especially indicated. It was on physiolt^ical
likeness, rather than on structural grounds, that he formed
his sweeping conclusions. He showed also that sarcodc
agreed in physiological properties with protoplasm in plants,
and that the two living substances were practically identical.
His paper of 1861 considers the living substance in muscles
(Ueber Muskelkdrperchen und das was man eine Zelle zu
nenncn babe), but in this he had been partly anticipated by
Ecker who, in 1849, compared the "formed contractile sub-
stance" of muscles with the " unformed contract ile substance "
of the lower types of animal life (Geddes).
The clear-cut, intellectual face of Schultze (Fig. 88) is
that of an admirable man with a combination of the artistic
and the scientific temperaments. He was greatly interested
in music from his youth up, and by the side of his microscope
was his well-beloved violin. He was some time professor in
the University of Halle, and in 1859 went to Bonn as pro-
fessor of anatomy and director of the Anatomical Institute.
His service to hbtology has already been spoken of (Chapter
This astute obsener will have an enduring fame in
biological science, not only for the part he pla^'wl in the
development of the protoplasm idea, but also on account of
other extensive labors. In 18^ he founded the leading
periodical in microscopic anatomy, the Archiv jiir Mikro-
scopische Analomie. This periodical was continued after
the untimely dealh of Schulize in 1874, and to-day is one of
the leading biological periodicals.
It is easy, looking backward, to obser\'C that the period
between 1840 and i860 was a verj' important one for modem
biolog}'. Many new ideas were coming into existence, but
through this perio<l we can trace distinctly, step by step, the
gradual approach to the idea that protoplasm, the living
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THE PHYSICAL BASIS OF LIFE 275
substance of organism, is practically the same in plants and
in animals- Lei us picture to ourselves the consequences of
the acceptance of this idea. Now for the first time physiol-
ogists began to have their attention directed to the actually
living substance; now for the first time they saw clearly
thai all future progress was lobe made by studying this living
substance — the scat of vital activity. This was the beginning
of modem biologj'.
Protoplasm is the parlicular object of study for the biol-
ogist. To obscr\'e its i)ropcrties, to determine how it be-
haves under different conditions, how it responds to stimuli
and natural agencies, to discover the relation of the internal
changes to the outside agencies; these, which constitute the
fundamental ideas of biology, were for the first time brought
directly lo the attention of the naturalist, about the year
i860— that epoch-making time when appeared Darwin's
Origin oj Species and Spencer's First Principles,
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CHAPTER XIII
THE WORK OF PASTKUR, KOCH. AND OTHERS
The knowledge of bacteria, those minulcsl forms of life,
has exerted a profound influence upon the dcvcIo|)mcnl of
general biologj. There arc many questions relating to bac-
teria that are strictly medical, but other phases of their lite
and activities are broadly biological, and some of those
broader aspects will next be brought under consideration.
The bacteria were first described by Leeuwenhoek in
1687, twelve years after his discover)' of the microscopic
animalcula now called protozoa. Thcj- arc so infinitesimal
in size that under his microscope they appeared as mere
specks, and, naturally, obsen-ation of these minute organ-
isms was suspended until nearly the middle of the ninetfenlh
ccnlurj', after the improvement of microscojje lenses. It is
characteristic of the little knowledge of bacteria in Linna'us's
period that he grouped them into an order, with other micro-
scopic forms, under the name chaos.
At first sight, the bacteria appear too minute to ligure
largely in human affairs, but a great de|)artinent of natural
science — bacteriologj' — has been open«l by the study of iheir
activities, and it must be admitted that the de\elo]>ment of
the science of bacleriolog}* has Ixen of gri-at practical im-
portance. The knowledge derived from experimental studic-s
of the bacteria has been the chief source of light in an obscure
domain which profoundly aUccts the well-being of mankind.
To the advance of such knowtcfige wc owe the giTm-lheor)-
of disease and the ability of metlical men to toiie with con-
;dbyGOOglC
PASTEUR, KOCH, AND OTHERS 277
tagtous diseases. The three greatest names connected with
the rise of bactcriolog)' are those of Pasteur, Koch, and Lister,
the results of whose labors will be considered later.
Among the general topics which have been clustered
around the study of bacteria wc take up, first, the question
of the spontaneous origin of life.
The Spontaneous Origin of Liff-
It wilt be rc-adily understood that the question of the spon-
taneous generation of life is a fundamental one for the biol-
ogist. Does life always arise from previously existing life,
or under certain conditions is it developed spontaneously?
Is there, in the inorganic world, a happy concourse of atoms
that become chained together through the action of the sun's
rays and other natural forces, so that a molecule of living
matter is constructed in nature's laboratory without contact
or close association with living substance? This is a ques-
tion of biogenesis — life from previous life — or of abiogenesis
— life without pree.itistinglifeor from inorganic matter alone.
It is a question with a long histor;-. Its earliest phases do
not involve any consideration of microscopic forms, since the>-
were unknown, but its middle and its modem aspect are con-
cerned especially with bacteria and other microscopic organ-
isms. The historical development of the problem may be
conveniently considered under three divisions: 1. The period
from Aristotle, 325 B.C., to the experiments of Redi, in 1668;
II, From the expcrimenis of Redi to those of Schuize and
Schwann in 1836 and 1837; III. The modem phase, ex-
tending from Pouchel's obser\'ations in 1859 to ihe present.
I. From Aristotle to Redi. — During the first period, the
notion of siMintaneous generation was universally accepted,
and the whole question of spontaneous origin of life was in
a crude and grotesque condition. It was thought that frogs
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278 BIOLOGY AND ITS MAKERS
and toads and other animals arose from (he mud of ponds
and streams through the vivifying action of the sun's rays.
Rats were supposed to come from the river Nile, the dew was
supposed to give origin to insects, etc.
The scicntilic writers of this period had little openness of
mind, and they indulged in scornful and sarcastic comments
at the expense of those who doubted the occurrence of
spontaneous generation. In the seventeenth centur>' Alex-
ander Ross, commenting on Sir Thomas Brown's doubt as
to whether mice may be bred by putrefaction, flays his an-
tagonist in the following words; "So may wc doubt whether
in cheese and timber worms are generated, or if beetles and
wasps in cow-dung, or if butterflies, locusts, shell-fish, snails,
eels, and such life be procreated of putrefied matter, which
is to receive the form of that creature to which it is by
formative power disposed. To question this is to question
reason, sense, and experience. If h? doubts this, let him go
to Egypt, and there he will find the fields swarming with
mice begot of the mud of Nylus, to the great calamity of
the inhabitants."
n. From Redi to Schwann.— The second period cm-
braces the experimental tests of Redi (1668), Spallanzani
(1775)1 and Schwann (1837) — notable achievements that
resulted in a verdict for the adherents to the doctrine of
biogenesis. Here the question might have rested had it
not been opened upon theoretical ground by Pouchet in
1859-
The First Experiments. — ^The belief in spontaneous gen-
eration, which was so firmly implanted in the minds of natu-
ralists, was subjected to an experimental test in 1668 by the
Italian Redi. It is a curious circumstance, but one that
throws great light upon the condition of intellectual devcloii-
ment of the period, that no one previous to Redi had at-
tempted to test the truth or falsity of the theory of spon-
;dbyGOOglC
PASTEUR. KOCH. AND OTHERS 279
tancous generation. To approach this question from the
experimental side was to do a great service to science.
The experiments of Rcdi were simple and homely. He
exposed meat in jars, some of which were left uncovered, some
covered with parchment, and others with fine wire gauze. The
meat in all these vessels became spoiled, and flies, being at-
tracted by the smell of decaying meal, laid eggs in that which
was exposed, and there came from it a large crop of maggots.
The meat which was covered by parchment also decayed in
a similar manner, without the appearance of maggots within
il ; and in those vessels covered by wire netting the flies laid
ihcir eggs uixjn the wire netting. There they hatched, and
the maggots, instead of appearing in the meat, appeared on
the surface of the wire gauze. From this Redi concluded
that maggots arise in decaying meat from the hatching of
the eggs of insects, but inasmuch as these animals had been
supposed to arise spontaneously within the decaying meat, the
experiment took the ground from under that hypothesis.
He made other obser\'alions on the generation of insects,
but with acute scientific analysis never allowed his conclusions
to nm ahead of his obsen*ations. He suggested, however,
the proljabilily that all cases of the supposed pro<luction of life
fron. dead mailer were due to the introduction of living germs
from without. The good work begun by Redi was confirmed
and extended by Swammerdam {1637-1681) and Vallisnieri
(1661-1 730), until the notion of the spontaneous origin of any
forms of life visible lo the unaided eye was banished from
the minds of scientific men.
Ridi {Fig. 89) was an Italian physician living in Arentino,
distinguished alike for his attainments in literature and for
his achievements in natural science. He was medical adviser
to two of the grand dukes of Tuscany, and a member of the
.\cademy of Crusca. Poetry as well as other literary com-
positions shared his time with scientific occupations. His
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200 BIOLOGY AND ITS MAKERS
collected works, literan-, scientific, and medical, were pub-
lished in nine octavo volumes in ^filan, 1809-1811. This
collection includes his life and letters, and embraces one
6*6-1607.
volume of soniifls. The book thai has been refcrrwl to as
containinj^ his fxpcrinients was i-ntilUil Espcricnzc Iiilonto
Alia Cfitcrazione Dej-l'Inselli, and first saw ihe Ught in
quarto form in Florence In 1668. ll went through five
edilions in twenty vcars. Some of the volumes were trans-
id byGoOglc
PASTEUR, KOCH, AND OTHERS 281
latcd into Latin, and were published in miniature, tnakii^
books not more than four inches high. Huxley says: "The
extreme simplicity of his experiments, and the clearness of
hb arguments, gained for his views and for their conse-
quences almost universal acceptance."
New Fonn of the Question. — The question of the spon-
taneous generation of life was soon to take on a new aspect.
Seven years after the experiments of Red!, Leeuwenhoek
made known a new world of microscopic organisms— the
infusoria— and, as we have seen, he discovered, in 1687, those
still minuter forms, the bacteria. Strictly speaking, the
bacteria, on account of their extreme minuteness, were lost
sight of, but spontaneous generation was evoked to account
for the birth of all microscopic organisms, and the question
circled mainly around the infusorial aninialcula. While the
belief in the spontaneous generation of life among forms
visible to the unaided eye had been surrendered, nevertheless
doubts were entertained as to the origin of microscopic oi^n-
isms, and it was now asserted that here were found the be-
ginnings of life — the place where inorganic material was
changed through natural agencies into organized beings
microscopic in size.
More than seventy years elapsed before the matter was
again subjected to experimental tests. Then Needham,
using the method of Redi, began to experiment on the pro-
duction of microscopic animalcula. In many of his experi-
ments he was associated with Buffon, the great French nat-
uralist, who had a theory of organic molecules that he wished
to sustain. Needham (1713-1784), a priest of the Catholic
faith, was an Englishman living on the Continent; he was
for many years director of the Academy of Maria Theresa at
Brussels. He engaged in scientific investigations in connec-
tion with his work of teaching. The results of Ncedham's
first experiments were published in 1 748, These experiments
;dbyGOOglC
282 BIOLOGY AND ITS MAKERS
were conducted by extracting the juices of meat by boiling;
by then enclosing the juices in vials, the latter being carefully
corked and sealed with mastic; by subjecting the sealed
bottles, finally, to heat, and setting them away to cool. In
due course of time, the fluids thus treated became infected
with microscopic life, and, inasmuch as Necdham believed
that he had killed all living germs by repeated heating, he
concluded that the living forms had been produced by spon-
taneous generation.
SpaUaozaoi. — The epoch-making researches of Spallan-
zani, a f elIow-counlr\*man of Rcdi, were needed to point out
the error in Nccdham's conclusions. Sjxkllanzani (Fig, 90)
was one of the most eminent min of his time. He was
educated for the church, and, therefore, he is usually known
under thetitleof Abb^ Spallanzani. He did not, however,
actively engage in his churchly offices, but, following an innate
love of natural science and of investigation, devoted himself
to experiments and researches and to teaching. He was first
a professor at Bologna, and afterward at the Uni\ersit)' of
Pavia. He made many additions to knowledge of the
de\clopmcnt and the jjhysiology of organisms, and he was
the first to make use of glass flasks in the experimental study
of the question of the spontaneous generation of life.
Spallanzani thought that the experiments of Needham
had not been conducted with sufficient care and precision ;
acconiingly, he made use of glass flasks with slender necks
which could be hermetically sealed after the nutrient fluids
had been introduced. The vials which Xecdham us«l as
containers were simply corked and scaled with mastic, and
it was by no means certain that the entrance of air after
heating had been jtrevented; moreover, no record was made
by Needham of the temperature and the time of heating to
which his bottles and fluids had been subjected.
Si>allanzani took nutrient fluids, such as the juices of vege-
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PASTEUR, KOCH, AND OTHERS 283
tables and meats which had been extracted by boiling, placed
them in clean flasks, the necks of which were hermetically
sealed in flame, and aflcnvard immersed them in boiling
water for three-quarters of an hour, in order to destroy all
germs that might be contained in them. The organic infu-
sions of Spallanzani remained free from change. It was
then, as now, a well-kno«Ti fact that organic fluids, when
e\[)Osed to air, quickly decomiwse and acquire a bad smell;
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284 BIOLOGY AND ITS MAKERS
they soon become turbid, and in a lilllc time a scum is
formed upon their surface. The fluids in the flasks of
Spallanzani remained of thesameappcarancc and consistency
as when they were first introduced into the vessel, and the
obvious conclusion was drawn that microscopic life is not
spontaneously formed within nutrient fluids,
"But Needham was not satisfied with these results, and
with a show of reason maintained that such a prolonged
boiling would destroy not only germs, but the gcrminalivc,
or, as he called it, the 'vegetative force' of the infusion
itself. Spallanzani easily disposed of this objection by show-
ing that when the infusions were again exposed to the air,
no matter how severe or prolonged the boiling to which they
had been subjected, the infusoria reappeared. His experi-
ments were made in great numbers, with different infusions,
and were conducted with the utmost care and precision"
(Dunster), It must be confessed, however, that the success
of his experiments was owing largely to the purity of the air
in which he worked, the more resistant atmospheric germs
were not present: as Wyman showed, long afterward, that
germs may retain their vitality after being subjected for
several hours to the temperature of boiling water.
Schulze and Schwann. — The results of Spallanzani's ex-
periments were published in 1775, and were generally re-
garded by the naturalists of that period as answering in the
negative the question of the spontaneous generation of life.
Doubts began to arise as to the conclusive nature of Siial-
lanzani's experiments, on account of the discovery of the part
which oxjgen plays in reference to life. The discovery of
oxygen, one of the greatest scientific events of the eighteenth
century, was made by Priestley in 1774, It was soon shown
that oxygen is necessary to all forms of life, and the question
was raiscxl : Had not the boiling of the closed flasks changwl
the oxygen so that through the heating process it had lost its
;dbyGOOglC
PASTEUR. KOCH, AND OTHERS 285
life-giving properties? This doubt grew until a reexamina-
tion of the question of spontaneou? generation became nec-
essary under conditions in which the nutrient fluids were
made accessible to the outside air.
In 1836 Franz Schulze, and, in the following year,
Theodor Schiv'ann, devised experiments to test the question
on this new basis. Schwann is known to us as the founder of
the cell-theorj', but we must not confuse Schulze with Max
Schultze, who established (he protoplasm doctrine. In the
experiments of Schulze, a flask was arranged containing
nutrient fluids, with a large cork perforated and closely fitted
with bent glass tubes connected on one side with a series of
bulbs in which were placed sulphuric acid and other chemical
substances. An aspirator was attached to the other end of
this system, and air from the outside was sucked into the
flask, passing on its way through the bulbs containing the
chemical substances. The purpose of this was to remove
the floating germs that exist in the air, whUe the air itself
was shown, through other experiments by Schwann, to re-
main unchanged.
Tyndall says in reference to these experiments: "Here
again the success of Schulze was due to his working in
comparatively pure air, but even in such air his experiment
is a risky one. Germs will pass unwetted and unscathed
through sulphuric acid unless the most special care is taken
to detain them. I have repeatedly failed, by repeating
Schulzc's experiments, to obtain his results. Others have
failed likewise. The air passes in bubbles through the
bulbs, and to render the method secure, the passage of the
air must be so slow as to cause the whole of its floating
matter, e\'en to the very core of each bubble, to touch the
surrounding fluid. But if this precaution be observed water
u-ili be jound guile as efjeclual as sulphuric acid."
Schwann's apparatus was similar in construction, except
;dbyGOOglC
286 BIOLOGY AND ITS MAKERS
that tlie bent tube on one side was surroundL-d by a jacket
of metal and was subjected to a vcr>- high temperature while
the air was being drawn through it, the effect being to kill
any floating germs that might exist in the air. Great care
was taken by both experimenters to have their flasks and fluids
thoroughly sterilized, and the results of their experiments wore
to show thai the nutrient fluids remained uncontaniinated.
These experiments pro\'cd that there is something in
the atmosphere which, unless it be remo\'ed or rendered
inactive, produces life within nutrient fluids, but whether
this something is solid, fluid, or gaseous did not appear
from the experiments. It remained for Helmholtz to show,
as he did in 1843, that this something will not pass through
a moist animal membrane, and is therefore a solid. The
results so far reached satisfied the minds of scientific men,
and the question of the spontaneous origin of life was
regarded as having been &ially set at rest.
in. The Third Period. Pouchet. — Wc come now to con-
sider the third historical phase of this question. Although it
had apparently been set at rest, the question was unex])ecl-
edly opened again in 1859 by the Frenchmiin Pouchet, the
director of Ihe \atural History Museum of Rouen. The
frame of mind which Pouchet brought to his cxj)erimcnial
in vest igiit ions was fatal to unbiased conclusions: "A\hen,
by meditation" he says, in the opening paragraph of his book
on Helerogenesis, "it was evident to trie that s]K>ntancous
generaljon was one of Ihe means employed by nature for the
production of living beings, 1 applied myself to discover by
what means one could place these phenomena in evidence."
Although he experimented, his case was prcjudical by
metaphysical considerations. He repeated the experimenis
of previous obscr\'ers with opposite results, and therefore he
declared his belief in the falsity of the conclusions of Spal-
lanzani, Schulze, and Schwann.
;dbyGOOglC
PASTEUR. KOCH, AND OTHERS 287
He planned and executed one experiment which he sup-
posed was conclusive. In inlroducing it he said; "The
opponents of spontaneous generation assert thai the germs of
microscopic organisms exist in the air, which transports them
to a distance. What, then, will these opponents say if I
succeed in introducing the generation of living organisms,
while substituting artificial air for that of the atmosphere?"
He filled a flask with boiling water and sealed it with great
care. This he inverted over a bath of mercury, thrusting
the neck of the bottle into the mercurj'. When the water
was cookd, he opened the neck of the bottle, still under the
mercun,-, and connected it with a chemical retort containing
the constituents for the liberation of oxygen. By heating
the retort, oxygen was dri\'cn off from the chemical salts
contained in it, and being a gas, the oxygen passed through
the connecting tube and bubbled up through the water of
the bottle, accumulating at the upper surface, and by pressure
forcing water out of the botde. After the bottle was about
half filled with oxygen imprisonetl above the water, Pouchet
took a pinch of hay that had been healed to a high tempera-
ture in an oven, and with a j;air of sterilized forceps pushed
it imdemeath the mercurj- and into the mouth of the bottle,
where the hay floated into the water and distributed itself.
He thus produced a hay infusion in contact with pure oxj-
gen, and after a few days this hay infusion was seen to becloudy
and turbid. It was, in fact, swarming with micro-organisms.
Pouchet pointed with triumphant spirit to the apparently
rigorous way in which his experiment had been carried on:
"Where," said he, "does this life come from? It can not
come from the water which had been boiled, destroying all
living germs thai may have existed in it. It can not come
from the oxygen which was produced at the temperature
of incandescence. It can not have been carried in the hay,
which had been heated for a long period before being intro-
;dbyGOOglC
286 BIOLOGY AND ITS MAKERS
duccd into the water." He declared that this life was, there-
fore, of spontaneous origin.
The controversy now re\'ived, and waxed warm under the
insistence of Pouchct and his adherents. Finally the Acad-
emy of Sciences, in the hope of bringing it to a conclusion,
apfx>intcd a committee to decide upon conflicting claims.
Pasteur. — Pasteur had entered into the investigation of
the subject about i86o,and,with wonderful sliill and acumen,
was removing all possible grounds for the conclusions of
Pouchet and his followers. In 1864, before a brilliant
audience at the Sorbonnc, he repealed the experiment out-
lined above and showed (he source of error. In a darkened
room he directed a bright beam of light upon ihe apparatus,
and his auditors could see in the intense illumination that
the surface of the mercur)- was covered with dust particles.
Pasteur then showed that when a body was plunged beneath
Ihe mercury, some of these surface granules were carried
with it. In this striking manner Pasteur demonstrated
that particles from the outside had been introduced into !he
bottle of water by Pouchct, This, however, is probably not
the only source of the organisms which were developed in
Pouchct's infusions. It is now known that a hay infusion
is very difhcull to sterilize by heat, and it is altogether likely
that the infusions used by Pouchet were not completely
sterilized.
The investigation of the question requires more critical
methods than was at first supposed, and more factors enter
into its solution than were realized by Spatlanzani and
Schwann.
Pasteur demonstratc<l that the floating particles of the air
contained living germs, by catching them in the mi-shes of
gun cotton, and then dissolving the cotton with ether and
examining the residue. He also showed that sterilized
organic fluids could be protected by a plug of cotton sufli-
;dbyGOOglC
PASTEUR, KOCH. AND OTHERS 289
ciently porous to admit of exchange of air, but matted closely
enough to entangle the floating particles. He showed also
that many of the minute organisms do not require free oxj-gen
for their life processes, but are able to lake the oxygen by
chemical decomposition which they themselves produce from
the nutrient fluids.
Jeffries Wyman, of Harvard College, demonstrated that
some germs arc so resistant to heat that they retain their
vitality after several hours of boiling. This fact probably
accounts for the difference in the results that have been
obtained by experimenters. The germs in a resting-stage
are surrounded by a thick protective coat of cellulose,
which becomes softened and broken when ihey germinate.
On this account more recent experimenters have adopted a
method of discontinuous heating of the nutrient iluid that is
being tested. The Ruids are boiled at intenals, so that the
unusually resistant germs arc killed after the coaling has been
rendered soft, and when they are about to germinate.
After the brilliant researches of Pasteur, the question of
sfxjntancous germination was once again regarded as having
been answered in the negative; and so it is regarded to-day
by the scientific world. Nevertheless, attempts have been
made from time to time, as by Bastian,of England, in 1872,
to revive it on the old lines.
Tyndall. — John Tyndall (1820-1893), the distinguished
phj'sicist, of London, published, in 1876, the results of his ex-
periments on this question, which, for clearness and ingenuity,
have never been surpassed. For some time he had been
experimenting in the domain of physics with what he called
optically pure air. It was necessary for him to have air from
which the floating particles had been sifted, and it occurred
to him that he might expose nutrient fluids to this optically
pure air, and thus ver\' nicely test the question of the
spontaneous origin of life within them.
;dbyGOOglC
2go
BIOLOGY A\D ITS MAKERS
He demised a box, or chamber, as shown in Fig. 91,
having in front a larf;e glass window, two small glass win-
dows on the ends, and in the back a liltic air-tight trapdoor.
Through the bottom of this box he had filled ordinary' It-st
tubes of the chemist, with an air-tight surrounding, and on
the lop he had inserted some coiled glass tubes, which were
open at both ends and allowe-d the jiassagc of air in and out
of (he box through the tortuous passage. In the middle
of the lop of the box wa^ a round piece of rubber. When
he perforated this wiih a pinhole the elasticity of the rub-
;dbyGOOglC
PASTEUR, KOCH, AND OTHERS 29^
ber would close the hole again, but it would also admit of
the passage through it of a small glass tube, such as is
called by chemists a "thistle tube." The interior of this
box was painted with a sticky substance like glycerin,
in order to retain the floating particles of the air when they
had once settled upon its sides and bottom. The apparatus
having been prepared in ihis way, was allowed to stand, and
the floating particles settled by their own weight upon
the bottom and sides of the box, so that day by day the
number of floating particles became reduced, and finally all
of them came to rest.
The air now differed from the outside air in having been
purified of all of its floating jarticles. In order to test the
complete disappearance of all particles, Tyndall threw a
beam of light into the air chamber. He kept his eye in the
darkness for some time in order to increase its sensitiveness;
then, looking from ihc front through the glass into the box,
he was able to see any particles that might be floating there.
The floating particles would be brightly illuminated by the
condensed light that he directed into the chamber, and
would become visible. When there was complete darkness
within the chamber, the course of the beam of light was
apparent in the room as it came up to the box and as
it left the box, being seen on account of the reflection from
the floating particles in the air, but it could not be seen
at all within the box. When this condition was reached,
Tyndall had what he called optically pure air, and he was
now ready to introduce the nutrient fluids into his test tubes.
Through a thistle tube, thrust into the rubber diaphragm
above, he was able to bring the mouth of the tube successively
o\er the difTerent test tubes, and, by pouring different kinds
of fluids from above, he was able to introduce these into
differenl lest tubes. These fluids consisted of mutton broth,
of turnip broth, and other decoctions of animal and vegeta-
;dbyGOOglC
292 BIOLOGY AND ITS MAKERS
' bic matter. It is to be noted that ihe test tubes were not
corked and consequently that ihe fluids contained within
them were freely exposed to the optically pure air within the
chamber.
The box was now lifted, and the ends of the tubes extend-
ing below it were thrust into a bath of boiling oil. This set
the fluids into a stale of boiling, the purpose being to kill
any germs of lite that might be accidenlally introduced into
them in Ihe course of their conveyance to the test tubes.
These fluids, exposed freely to the optically pure air within
this chair.ber, then remained indcfiniloly free from micro-
organisms, thus dcnionslrating (hat putrescible fluids may
be freely exposed lo air from which the floating particles
have been removed, and not show a trace cither of spoiling
or of organic life wiihin them.
It might be objected that the continued boiling of the
fluids had produced chemical changes inimical to life, or in
some way destroyed their life-supporting properties; but
after they had remained for months in a perfectly clear state,
Tyndall opened the little door in the back of the box and
closed it at once, thereby admitting some of the floating
particles from the outside air. Wiihin a few days' time the
. fluids which previously had remained uncontaminaled were
spoiling and teeming with living organisms.
These experiments showed that under the conditions of
Ihe experiments no spontaneous origin of life takes place.
But while we must regard the hyjx)thesis of spontaneous
generation as thus having been disproved on an experimental
basis, it is still adhered to from the theoretical standpoint
by many naturalists; and there are also many who think
that life arises sponlaneou^ly at the present time in ultra-
microscopic particles. Weismann'shyimthctical "biophors,"
too minule for microscojiic obser\-ation, arc supjK>se<l lo arise
by s]K)ntani-ous generation. This phase of the question,
;dbyGOOglC
PASTEUR. KOCH. AND OTHERS 293
however, not being amenable to scientific tests, is theoretical,
and therefore, so far as the evidence goes, wc may safely say
lliat the spontaneous origin of life under present condi-
tions is unknown.
Practical Applications. — There are, of course, numerous
practical applications of the discovery that the spoiling of
pulrcscible fluids is due to floating germs that have been
introduced from the air. One illustration is the canning of
meats and fruits, where the object is, by heating, to destroy
all living germs that arc distributed through the substance,
and then, by canning, to keep them out. When this is
entirely successful, the presened vegetables and meats go
un contaminated. One of the most important and practical
applications came in ihc recognition (1867) by the English
surgeon Lister that wounds during surgical operations are
poisoned by Hoating jmrlicles in the air or by germs cling-
ing to instruments or the skin of the operator, and that to
render all appliances sterile and, by antiseptic dressings,
complclely to prevent the entrance of these bacteria into
surgical wounds, insures their being clean and healthy.
This led to antiseptic surgerj', with which the name of Lister
is indissolubly connected.
The Germ-Theory of Disease
The germ-theory of disease is another question of general
bearing, and It will be dealt with briefly here.
After the discovery of bacteria by Leeuwenhoek, in 1687,
some medical men of the time suggested the theory that con-
tagious diseases were due to microscopic forms of life that
passed from the sick tc the well. This doctrine of conlagium
zitum, when first promulgated, took no firm root, and grad-
ually disappeared. It was not revived until about 1840.
If we attempt briefly to sketch the rise of the germ-theory of
;dbyGOOglC
294 BIOLOGY AXD ITS MAKERS
disease, we come, then, first lo ihc year 1857, when the
Italian Bassi investigated the disease of sill^worins, and
showed ihat the transmission of that disease was the result
of the passing of minute glittering particles from the sick to
the healthy. Upon the basis of Bassi's obser\-ation, the
distinguished anatomist Henle, in 1840, expounded the
theory that all contagious diseases are due to microscopic
germs.
The matter, however, did not receive experimental proof
until 1877, when Pasteur and Robert Koch showed the direct
connection between certain microscopic filaments and the
disease of splenic fever, which attacks sheep and other cattle.
Koch was able to gel some of these minute filaments under
the microsrope, and to trace upon a warm stage the different
steps in their germination. He saw the spores bud and
produce filamentous forms. He was able to cultivate these
upon a nutrient substance, gelatin, and in this way to obtain
a pure culture of the organism, which is designated under
the term anthrax. He inoculated mice « ilh the pure culture
of anthrax germs, and prcxluced splenic fever in the inocu-
lated forms. He was able to do this through several genera-
tions of mice. In the same year Pasteur showed a similar
connection between splenic fever and the anihra.x.
This demonstration of the actual connection between
anthrax and splenic fever formal the first secure foundation
of the germ-thc-ory of disease, and this dejartment of inves-
tigation became an imjxjrlani one in general biolog)'. The
pioneer workers who reached the highest ix)silion in the de-
velopment of this knowledge are Pasteur, Koch, and Lister.
Veneration of Pasteur. — Pasteur is one of the most con-
spicuous figuri-s of the nineteenth centuri,'. The veneration
in whieli he is held by the French pi-ople is shown in the
result of a jiopiilar vole, taken in 1007. by which he was
placedat thehc-.id of all their nolabli- men. Oneof ihcmost
;dbyGOOglC
Dioiiized 3, Google
2g6 BIOLOGY AND ITS MAKERS
widely circulated of the French journals — the Petit Parisien—
appealed to its readers all over the country to vote upon the
relative prominence of great Frenchmen of the last century.
Pasteur was the winner of this interesting contest, having
received 1,338425 votes of the fifteen millions cast, and rank-
ing above Victor Hugo, who stood second in popular esti-
mation, by more than one hundred thousand votes. This
enviable recognition was won, not by spectacular achieve-
ments in arms or in politics, but by indefatigable industry
in the quiet pursuit of those scientific researches that have
resulted in so much good to the human race.
Pergonal Qualities. — He should be known also from the
side of his human qualities. He was devotedly attached to
his family, enjoying the close sympathy and assistance of his
wife and his daughter in his scientific struggles, a circum-
stance that aided much in ameliorating the severity of his
labors. His labors, indeed, overstrained his powers, so that
he was smitten by paralysis in 1868, at the age of forty-six,
but with splendid courage he overcame this handicap, and
continued his unremitting work until his death in 1895.
The portrait of Pasleur with his granddaughter (FiK- 92)
gives a touch of personal interest to the investigator and the
contestant ujxin the field of science. His strong face shows
dignity of pui|X)se and the grim determination which led to
colossal attainments; at the same time it is mtllowcd by
gentle affection, and contrasts finely with the trusting ex-
pression of the younger lace.
Pasteur was born of humble jwirents in I)6k- in the Jura,
on December the 27th, 1822. His father was a lanncr,
but wilhat, a man of fine character and stem exjjtrienci-, as
is "shown by the fact thai hi- hud fouglit in the legions
of the First Eni]>irc and been dc-corated on the field of
battle by Xapoleon," The filial devotion of Pasteur and his
justifiable pride in his father's militar\- sen-ice are ^liown
;dbyGOOglC
PASTEUR, KOCH, AND OTHERS ^97
in the dedication of his book, Studies on Fermentation,
published in 1876:
"To the memory of my Father,
Formerly a soldier under the Flrsl Empire, and Knight of the Legion of
The longer I live, the belter do I understand ihe kindness of thy heart
and the superiority of thy judgment.
The efforts which I have devoted to these studies and to Ihose which have
preceded them arc the fruits of thy ciample and of thy counsel.
Desiring to honor these precious recollections, I dedicate this book to thy
Uhcn Pasteur was an infant of two years his parents
removed to the town of Arbois, and here he spent his youth
and received his early education. After a period of indiffer-
ence to study, during which he employed his time chiefly in
fishing and sketching, he settled down to work, and, there-
after, showed boundless energy and enthusiasm.
Pasteur, whom we are to consider as a biologist, won his
first scientific recognition at the age of twenty-five, in chem-
istry and molecular physics. He showed that crystals of
certain tartrates, identical in chemical composition, acted
differenlly upon polarized light transmitted through them.
Hf concluded that the differences in optical properties
depended upon a different arrangement of the molecules;
and these studies opened the fascinating field of molecular
physics and physical chemistry.
Pasteur might have remained in this field of investigation,
but his destiny was different. As Tyndall remarked. "In
the investigation of microscopic organisms — the 'infinitely
little,' as Pasteur loved to call them— and iheir doings in this,
our world, Pasteur found his true vocation. In this broad
tit'ld it has been his good fortune to alight upon a crowd of
connected problems of the highest public and scientific
iniercsl, ripe for solution, and requiring for their successful
;dbyGOOglC
298 BIOLOGY AND ITS MAKERS
treatment the precise culture and capacities which he has
brought to bear upon them."
In 1857 Pasteur went to Paris as director of scientific
studies in the £cole Normalc, having previously been a
professor in Strasburg and in Lille. From this time on his
energies bqcame more and more absorbed in problems of a
biological nature. It was a momentous year (1857) in the
annals of bactcriolog)' when Pasteur brought convincing
proof that fermcnialion (then considered chemical in its
nature) was due to the growth of organic life. Again in i860
he demonstrated that both lactic (the souring of milk) and
alcoholic fermentation are due to the growth of microscopic
organisms, and by these researches he developed (lie
province ofc-biolog)- that has expanded into the science of
bactcriolog)'.
After Pasteur entered the path of investigation of microbes
his progress was by ascending steps; each new problem the
solution of which he undertook seemed of greater imjiorlance
than the one just con([uered. He was led from the discovery
of microbe action to the appliaition of his knowledge to the
productioo- of antitoxins. In all this he <iid not follow his
own inclinations so much as his sense of a call to sQr\-ice. In
fact, he ahva}'s retainc-d a regret that he was not permitted
to perfect his researches on crystallography. At the age of
seventy he said of himself: "If I have a regret, it is that 1 did
not follow that route, less rude it seems to me, and which
would have led, I am convinced, to wonderful discoveries.
A sudden turn threw mc into the study of fermentation, fer-
mentations set me at diseases, but I am still inconsolable to
think that I have never had the time to go back to my old
subject" (Tarbell),
.Although the results of his combined researches form a
succession of triumphs, ever^- point of his doctrines was the
subject of fierce controversy; no investigations ever met
;dbyGOOglC
PASTEUR, KOCH, AND OTHERS 299
with more determined opposition, no investigator ever fought
more strenuously for the establishment of each new truth.
He went from the study of the diseases of wines (1865)
to the investigation (1865-1868) of the silkworm plague
which had well-nigh crushed the silk industry of his country.
The result was the saving of millions of francs annually to
the people of France,
His Supreme Service. — He then entered upon his chief
sen'ices to humanity — the application of his discoveries to
the cure and prevention of diseases. By makinga succession
of pure cultures of a disease-producing virus, he was able to
attenuate it to any desired degree, and thereby to create a
vaccinating form of the virus capable of causing a mild affec-
tion of the disease. The injection of this attenuated virus
secured immunity from future attacks. The efficacy of this
form of inoculation was first proved for the disease of fowl
cholera, and then came the clear demonstration (1881) that
the \-accine was effective against the splenic fever of cattle.
Crowning this series of discoveries came the use of inoculation
(1885) to prevent the de\'elopment of hydrophobia in one
bitten by a mad dog.
The Pasteur Institute. — ^The time had now cc^e for the
establishment of an institute, not alone for the treatment of
hj'drophobia, but also for the scienlific study of means to
control other diseases, as diphtheria, typhoid, tuberculosis,
etc. A movement was set on foot for a popular subscription
to meet this need. The response to this call on the part of
the common people was gratifying. "The extraordinary en-
thusiasm which accompanied the foundation of' this great
institution has certainly not been equaled in our time.
Considerable sums of money were subscribed in foreign coun-
tries, while contributions poured in from every part of France.
Even the inhabitants of obscure little towns and villages
organized ffites, and clubbed together to send their small
;dbyGOOglC
300 BIOLOGY AND ITS MAKERS
gifts " (Franckland), The lotal sum subscribed on ihe date
of the opening ceremony amoimled to 3,586,680 francs.
The institute »-as formally opened on November 141b,
1888, with impressive ceremonies presided over by iht
Presidait of the Republic of France. The establishment
of this institute v.as an event of great scienlific importance.
Here, within the fir^t decade of its existence, were success-
fully treated more than t« cnij- thousand cases of hydrophobia.
Here has been fliscovered by Roux the antitoxin for diph-
theria, and here have been established the principlc-s of inoc-
ulation against the bubonic ]>la(*ue, against lockjaw, against
tuberculosis and other maladies, and of the recent microbe
inoculations of Wright of London. More than thirty
"Pasteur Institutes," with aims similar to the parent institu-
tion, have been eslablished in dilTerent jwrts of the civilized
world.
Pasteur died in 1895, greatly honorwl by the whole world.
On Saturflay, October 5th of that year, a national funeral
was conducted in the Church of Nolrc-Danie, which was
attended by the representatives of the stale and of numerous
scientific bodies and learned societies.
Koch. — Robert Koch (Fig. 93) was bom in 1841, and
is still living, engaged actively in work in the University of
Berlin. His studies have been mainly those of a medical
man, and have been crowned with remarkable success. In
1881 he discovered the germ of tuberculosis, in 1883 Ihe germ
that produces Asiatic cholera, and since that time his name
has been eonntxrted with a number of remarkable discoveries
thai are of continuous practical application in the science of
medicine.
Koch, with the rigorous scientific spirit for which he is
noleworlhy, established four necessary links in ihe chain
of evidence to show that a ixirticular organism is connected
with a (articular disease. 'Phesefour |)Ostulales of Koch arc:
;dbyGOOglC
PASTEUR. KOCH. AND OTHERS
301
First, that a microscopic organism of a particular type should
be found iii great abundance in the blood and the tissue of the
sick animal; second, that a pure culture should be made of
the suspected organism; third, that this pure culture, when
introduced into the body of another animal, should produce
Fic, 93, ROBEI
the disease; and, fourth, that in the blood and tissues of that
animal there should be found quantities of the particular
organism that is suspected of producing the disease. In the
case of some diseases this entire chain of evidence has been
established ; but in others, such as cholera and typhoid fever,
the last steps have not been completed, for the reason that the
;dbyGOOglC
302
BIOLOGY AND ITS MAKERS
animals experimented upon, namely, guinea-pigs, rabbits,
and mice, are not susceptible to these diseases.
Lister. — ^The other member of the great triumvirate of
bacteriolog}- is Sir Joseph Lister (Fig. 94); bom in 1827, he
has been successively professor of surgery in the universities
F[G, 94,— Sir J'
of Glasgow fi86o) and of Edinburgh (1869), and in King's
College, London (1877). His practical a|)plication of the
germ-lhcor}' introduced aseptic methods into surgery and
completely revolutionized that field. This was in 1867. In
an address given that year before the British Medical .\sso-
ciation in Dublin, he said : " \\ hen it had been shown by the
;dbyGOOglC
PASTEUR, KOCH, AND OTHERS 303
researches of Pasteur that the septic property of the atmos-
phere depended, not on oxygen or anj' gaseous constituent,
but on minute organisms suspended in it, which owed their
energy to their vitality, it occuiTcd to Die that decomposition
in the injured part might he avoided without excluding the
air, by applying as a dressing some material capable of de-
stroying the life of the floating particles." At first he used
carbolic acid for this purpose, "The wards of which he had
charge in the Glasgow Infirmary were especially affected by
gangrene, but in a short time b(x:amc the healthiest in the
world ; while other wards separated bj' a passageway retained
their infection." The method of Lislcr has been universally
adopted, and at the same lime has been greatly extended and
improved.
The question of immunity, i.e., the reason why after
having had certain contagious diseases one is rendered
immune, is of very great interest, but is of medical bearing,
and therefore is not dealt with here.
Bacteria and Nitrates. — One further illustration of the
connection between bacteria and practical affairs may be
mentioned. It is well known that animals arc dependent
upon plants, and that plants in the manufacture of protoplasm
make use of certain nitrites and nitrates which they obtain
from the soil. Now, the source of these nitrites and nilrates
is very interesting. In animals the final products of broken-
down protoplasm are carbon dioxide, water, and a nitrog-
enous substance called urea. These products are called
excretory products. The animal machine is unable to utilize
the energy which exists in the form of potential energy in
these substances, and they are removed from the body.
The history of nitrogenous substance is the one which at
present interests us the most. Entering the soil, it is there
acted upon by bacteria residing in the soil, these bacteria
possessing the power of making use of the lowest residuum
;dbyGOOglC
304 BIOLOGY AND ITS MAICERS
of energy left in the nitrogenous substance. They cause the
nitrogen and the hydrogen to unite with oxygen in such a way
that there are produced nitrous and nitric acids, and from
these two acids, through chemical action, result the nitrites and
the nitrates. These substances arc then utilized by the plant
in the manufacture of protoplasm, and the plant is fed upon
by animal organisms, so that a direct relationship is estab-
lished between these lower forms of life and the higher plant
and animal scries; a relationship that is not only interesting,
but that helps to throw an important side-light upon the
general nature of vital activities, their kind and their reach.
In addition to t'.ii: soil baclcria mentioned above, there
are others that form association with the rootlets of certain
plants and possess the power of fixing free nitrogen from
the air.
The nitrifying bacteria, are,of course, of great importance
to the farmer and the agriculturist.
It is not our purpose, however, to trace the difTerent
phases of the subject of bacteriology to their conclusions, but
rather to give a picture of the historical development of this
subject as related to the broader one of general biology.
;dbyGOOglC
CHAPTER XIV
HEREDITY AND GERMINAL CONTINUITY-
MENDEL, GALTON, WEISMANN
It is a matter of common obscn-ation thai in the living
world like tends to produce like. The olTspring of plants,
as well as of animals, resembles the parent, and among all
organisms endowed with mind, the mental as well as the
physical qualities are inherited. This is a simple statement
of the fact of heredity, bul the scientific study of inheritance
involves deep-seated biological questions that emerged late
in the nineteenth cenlurj', and the subject is still in its
infancy.
In investigating this question, we need first, if possible,
to locate the bt'arers of hereditary qualities within the physical
substance thai connecls one generation with the next; then,
to study ihcir behavior during the transmission of life in order
to account for the inheritance of both maternal and paternal
qualities; and, lastly, to determine whether or not transiently
acquired characlerisiics are inherited.
Hereditary Qualities in the Germinal Elements. — When
we take into consideration the fact established for all animals
and plants (setting aside cases of budding and the division
of unicellular organisms), that the only substance that passes
from one generation to another is the egg and the sperm in
aniiTials, and their representatives in plants, we see that the
first question is narrowed to these bodies. If all hereditary
qualities are carried in the egg and the sperm — as it seems
they must be— then it follows that these germinal elements,
20 305
;dbyGOOglC
3o6 BIOLOGY AND ITS MAKERS
although microscopic in size, have a verj' complex organiza-
tion. The discover)' of this organization must depend u|x>n
microscopic examination. Knowledge regarding the physical
basis of heredity has been greatly advanced by critical studios
of cells under the microscope and by the application of ex-
perimental methods, while other phases of the problems of
inheritance have been elucidated by the analysis of statistics
regarding hereditary transmissions. The whole question,
howc\Tr, is so recent that a clear formulation of the direction
of the main currents of progress will be more helpful than
any attempt to estimate critically the underlying principles.
Early Theories.— There were speculations regarding the
nature of inheritance in ancient and mcdiaixal times. To
mention any of them prior to the eighteenth century would
sen-e no useful purpose, since ihcy were \-ague and did not
form the foundation upon which the modem theories were
built. The controversies over pre-formation and epigonesis
(see Chapter X) of the eighteenth century embodied some
ideas that have been revived. The recent conclusion that
there is in the germinal elements an inherited organization
of great complexity which conditions inheritance seems, at
first, to be a return to the doctrine of prc-formation,but closer
examination shows that there is merely a general resemblance
between the ideas expressed by Haller, Bonnet, and philos-
ophers of their time and those current at the present time.
Inherited organization, as now understood, is founded on
the idea of germinal continuity and is vastly different from
the old theory of preformation. The meaning of cpigencsis,
as expressed by Wolff, has also been modified to include the
conception of prc-localization of hereditary qualities within
particular parts of the egg. It has come now to mean that
development is a process of differentiation of certain qualities
already laid down in the germinal elements.
Darwin's Theory of Paogenesis. — In attempting to
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HEREDITY AND GERJ.IIXAL CONTINUITY 3°7
account for heredity, Darwin saw clearly the necessity of
providing some means of getting all hereditary' qualities com-
bined within ihe egg and tlic sperm. Accordingly he orig-
inated his provisional thcorj' of pangenesis. Keeping in mind
the fact that all organisms begin iheir lives in the condition
of single cells, the idea of inheritance through these micro-
scopic particles becomes difficult to understand. How is it
possible to conceive of all the hcrcditar)- qualities being con-
tained wilhin the microscopic germ of the future being?
Danvin supposed that ver;- nu'nule partick^;, which he called
gcmmules, were set free from all the cells in the body, those
of the muscular system, of the nervous system, of the bony
tissues, and of all other tissues contributing their part. These
liberated gemmules were supposed to be carried by the cir-
culation anrl ultimately to be aggregated within the germinal
elements (ovum and sperm). Thus the germinal elements
would be a composite of substances derived from all organs
and all tissues.
With this conception of the blending of the parental
qualilies within the germinal elements we can conceive how
inheritance would be possible and how there might be in-
cluded in the cjrg and the sperm a representative in material
substance of all the qualities of the fjarcnts. Since de\-clop-
ment begins in a fertilized ovum, this complex would contain
minute jjarticlcs derived from cverj' part of the bodies of
both jxi rents, which by growth nould gi\-e rise to new tissues,
all of them containing representatives of the tissues of the
])arent form.
Theory of Pangenesis Replaced by that of Genninal Con-
tinuity.— This theorv- of Darwin sened as the basis for other
theories founded upon the conception of the existence of pan-
gens; and although the modifications of Spencer, Brooks, and
others were important, it is not necessan,' to indicate them in
detail in onlcr to understand what is to follow. The various
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3o8 BIOLOGY AND ITS MAKERS
theories founded upon the idea of paogens were destined to
be replaced by others founded on the conception of gcminal
continuity — the central idea in nineteenth-century biolog)-.
The four chief steps which have led to the advancement
of the knowledge of heredity, as su^ested by Thomson, are
as follows: " (a) The exposition of the doctrine of germinal
continuity, (b) More precise inAcstigation of the material
basis of inheritance, (c) Suspicions regarding the inherit-
ance of acquired characteristics, (d) Application of statis-
tical methods which have led to the formulation of the taw
of ancestral heredity." We shall take these up in order.
Exposition of the Doctrine of Germinal Continuity. -
From parent to offspring there passes some hereditar>- sub-
stance; although small in amount, it is the only living thread
that connects one generation with another. It thus appears
that there enters into the building of the body of a new organ-
ism some of the actual substance of both parents, and that
this transmitted substance must be the bearer of hercditarv'
qualities. Does it also contain some characteristics inherited
from grandparents and previous generations? If so, how-
far back in the history of the race docs unbroken continuity
extend ?
Briefly stated, genetic continuity means that the ovum
and its fertilizing agent are derived by continuous ccll-Iineage
from the fertilized ovum of previous generations, extending
back to the begiiming of life. The first clear exposition of
this theor\- occurs in the classical work of Virchow on Cellular
Pathology, published in 1858. Virchow (i82i-i(;o2), the
distinguished professor of the University of Hcrlin, has al-
ready been spoken of in connection with the development
of histology. He took the step of overthrowing the ihcor}-
of free cell-formation, and replacing it by the doctrine of
cell-succession. .According to the theory of Schleiden and
Schwann, cells arose from a blastema by a condensation of
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HEREDITY AND GERMINAL CONTINUITY 309
matter around a nucleus, and the medical men prior to 1858
believed in free cell-formation within a matrix of secreted
or excreted substance. This doctrine was held with tenacit)'
especially for [)athological growths. \'irchow demonstrated,
however, that there is a continuit)- of living substance in all
growths — that cells, both in health and in disease, arise only
by the growth and division of previously existing living cells;
and to express this truth he coined the formula "omnis
celluia e cellula." Manifestl>- it was necessary to establish
this law of cell -succession before any idea of germinal con-
tinuity could prevail. X'irchow's work in this connection
is of undying value.
When applied to inheritance the idea of the continuity of
living substance leads to making a distinction between germ-
cells and body-cells. This had Ix-cn done before the obser-
vations of Virchow made their separation of great theoretical
value. Richard Owen, in 1849, pointed out certain differ-
ences between the body-cells and the germinal elements,
but he did not follow up the distinction which he made.
Hacckel's General Morphology, published in 1866, forecasts
the idea also, and in 1878 Jaeger made use of the phrase
"continuity of the germ protoplasm." Other suggestions
and modifications led to the clear expression by Nussbaum,
about 1875, that the germinal substance was continued by
unbroken generations from the past, and is the particular
substance in which all heredilan,- qualities are included.
But the conception finds its fullest expression in the work
of Wcismann.
Weismaim's explanation of heredity is at first sight
relatively simple. In reply to the (|ueslion, "Why is the
offspring like the parent?" he says, "Because it is composed
of some of the same stuff." In other words, there has been
unbioken germinal continuity between generations. His idea
of germinal continuity, i.e., unbroken continuity, through ail
;dbyGOOglC
3'° BIOLOGY AND ITS MAKERS
time, of the germinal substance, is a conception of very great
extent, and now underlies all discussion of heredity.
In order to comprehend it, we must first distinguish
between the germ-cells and the body-cells, Weismann
regards the body, composed of its many cells, as a derivative
that becomes simply a vehicle for the germ-cells, Owen's
distinction between Rcrm-cclls and body-cells, made in 1849,
was not of much importance, but in the theory of Weismann
it is of vital significance. The germ-cells are the particular
ones which carr^- fonvard from generation to generation the
life of the individual. The body-cells arc not inherital di-
rectly, but in the transmission of life the germ-cells pass to
the succeeding generation, and they in turn have been inher-
ited from the previous gencralion, and, therefore, we have
the phenomenon of an unbroken connection with all previous
generations.
When the full significance of this conception comes to us,
we sec why the germ-cells have an inherited organization of
remarkable complexit}'. This germinal substance embodies
all the past historj- of the living, impressionable protoplasm,
which has had an unbroken scries of generations. During
all lime it has been subjeclixl to the molding influence of
e.xtemal circumstances to which it has resjwnded, so that
the summation of its experiences becomes in some way
embedded within its material substance. Thus we ha\e
the germinal elements possessing an inherited organization
made up of all the previous experiences of the ]>rotoplasm,
some of which naturally are much more dominant than tlie
others.
We have seen that this idea was not first exjircsM'd by
Weismann; it was a modification of the views of N'ussbaum
and Hertwig. While it was not his individually, his mn-
clusions were apparently reached inde|)cndently- This idea
was in the intellectual atmosphere of the times. Several
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HEREDITY AND GERMINAL CONTINUITY 311
investigators reached their conclusions independently, al-
though there is great similarit) between them. Although the
credit for the first formulation of the law of germinal con-
linuity docs not belong to Wcismann, that of the greatest
elaboration of it docs. This doctrine of germinal continuity
is now so firmly embedded in biological ideas of inheritance
and the evolution of animal bfe that we may say it has become
the corner-stone of modem biology.
The conclusion reached^that the hereditary substance is
thegerm-plasm — is merely preliminan,*; the question remains,
Is the germ-plasm homogeneous and endowed equally in ail
parts with a mixture of hereditary qualities? This leads
to the second step.
The More Precise Investigation of the Material Basis of
Inheritance. — The apjjlication of the microscope to critical
studies of the structure of ihc germ-plasm has brought
imi>ortant resuks which mci^e with the development of the
idea of germinal continuity. Can we by actual obsen'ation
determine the particular part of the protoplasmic substance
that carries the hereditarj- qualities? The earliest answer
to this question was that the protoplasm, being the living
substance, was the bearer of heredity. But close analysis
of the behavior of the nucleus during development led,
about 1875, to the idea that the hereditary qualities are located
within the nucleus of the cell.
This idea, promulgated by Fol, Koelliker, and Oskar
Hertwig, narrowed the attention of students of heredity
from ihe general protoplasmic conlcnts of the ceil to the
nucleus. Later investigations show that this restriclion was,
in a measure, right. The nucleus lakes an active part
during cell -division, and It was verj' natural to reach the
conclusion that it is the particular bearer of hereditarj'
substance. But, in 1883, \'an Bcneden and Boveri made
the discovcn' that within the nucleus are certain dis-
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$13 BIOLOGY AND ITS MAKERS
tinct little rod-likc bodies which make their appearance
during cell -division. These little bodies, inasmuch as they
stain very deeply with the dyes used in microscopic re-
search,arc called chromosomes, .\ndcontinucdinvcstigation
brought out the astounding fact that, although the number of
chromosomes vary in different animals (commonly from two
to twenty-four), they are of the same number in all the cells
of any i>articular animal or plant. These chromosomes are
reganlcd as the bearers of heredity, and their behavior during
fertilization and development has been followt^J with great
care.
nrilliant studies of the formation of the egg have
shown that the egg nucleus, in the process of becoming
mature, surrenders one-half lis number of chromosomes; it
approaches the surface of the egg and undergoes division,
squeezing out one-half of its substance in the form of a polar
globule; and this process is onccre|K-ated.* The formation
of polar globules is accomijanicd by a noteworthy process of
reduction in the number of chromosomes, so that when the
egg nucleus has reachixi its mature condition it contains only
one-half the number of chromosomes characteristic of the
species, and will not ordinarily undergo develoi)ment without
fertilization.
The precise steps in the formation of the sperm have also
been studied, and it has been determine<i that a jtarallel
scries of changes occur. The sperm, when it is fully formal,
contains also one-half the number of chromosomi-s charac-
teristic of ihc species. Now, egg and sinrm are the two ger-
minal elements which unite in development. FtTiitiz;ition
takes place by the union of s[>erm and egg, and inasmuch
as the nuclei of each of these structun-s contain one half of
the number of chromosomes characteristic of the -.periis,
■Thrre are a few rircjjliims to tliin rule, us in llli- ••gg'^ "* ]iliilll-lii i',
(-11 ,, in v.'hkh a single [xilar globuU; is ]inidu<i'<].
dbjGoogle
HEREDITY AND GERMINAL CONTINUITY 3^3
their union in fertilization results in the restoration of the
original number of chromosomes. The fertilized ovum is
ihc slarting-point of a new organism, and from the method
of its fertilization it appears that the parental qualities are
passed along to the cells of evcrj' tissue.
The complex mechanism exhibited in the nucleus during
segmentation is very wonderful. The fertilized ovum begins
to divide, the nucleus passing through a scries of complicated
changes whereby its chromosomes undergo a lengthwise
division — a division that secures an equable partition of the
substance of which they are composed. With each successive
division, this complicated process is repeated, and .the many
cells, arising from continued segmentation of the original cell,
contain nuclei in which are embedded descendajits of the
chromosomes in unbroken succession. Moreover, since these
chromosomes are bi-parental, we can readily understand that
c\er;- cell in the body carries both maternal and paternal
<|ualities.
The careful analysis of the various changes within the
nuclei of the egg proves to be the key to some of the central
questions of heredity. We see the force of the point which
was made in a previous chapter, that inheritance is in the
long run a cellular study, and we see in a new light the im-
portance of the doctrine of germinal continuity. This con-
ception, in fact, elucidates the general problem of inheritance
in a way in which it has never been elucidated by any other
means.
For some time the attention of investigators was concoi-
traled upon the nucleus and the chromosomes, but it is now
necessary- to admit that the basis of some structures is dis-
co\erable within the cytoplasm that surrounds the nucleus.
Experimental observations (Conklin, Lillie, Wilson) have
shown the existence of jsirticular areas within the apparently
sim]>le substance of the egg, areas which are definitely related
;dbyGOOglC
314 BIOLOGY A\-D ITS MAKERS
to the (ievelojuncnt of particular parts of the embrj'o. The
removal of any one of these pre- localized areas prevents the
development of the jiart with which it is genetically related.
Researches of this kind, necessitating great ingenuity in
mcihod and great talents in the obseners, are widening the
-field of obser\'ation ujxin the jihenomena of heredity.
The Inheritance of Acquired Characteristics. — ^The belief
in the inheritance of acquired characteristics was generally
accepted up to the middle of the nineteenth centurj-, but the
reaction against it started by Galton and others has assumed
great proportions. Discussions in this line have been carried
on extensively, and frequently in the spirit of great partizan-
ship. These discussions cluster verj' much about the name
and the work of Weismann, the man who has consistently
stood against the idea of acquired characteristics. More in
reference to this phase of the question is given in the chapter
dealing with Weismann's theorj' of evolution (see p. 398).
Wherever the truth may lie, the discussions regarding the
inheritance of acquired characteristics provoked by Weis-
mann's theoretical considerations, have resulted in stimulat-
ing experiment and research, and have, therefore, been
beneficial to the advance of science.
The Application of Statistical Methods and Experiments to
the Ideas of Heredity. Mendel.— This feature of investigating
questions of heredity is of growing imiwrUnce. The first
to comi)lete cxjjeriments and to investigate heredity to any
purjK)se was the .Austrian monk Mendel (1822- 1884I (Fig, 95),
the abbot of a monastery at Briinn, In his ;^arden he made
many exjuTiments u]x>n the inheritance, particulariy in iieas,
of color and of form; and through these experiments he
demonstrated a law of inheritance which l)ids fair to be one
of the great liiological discoveries of tlie nireleenlh centur\\
He published his pa]>er.= in 1866 and 1867. but since the minds
of naturalists at that time were very much occupied with the
;dbyGOOglC
HEREDITY AND GERMINAL CONTINUITY 3^5
queslions of organic evolution, raised through the publications
of Danvin, the ideas of Mcndt-I attracted ver)- little attention.
The principles that he established were re-discovered In iQoo
by De Vries and other botanists, and thus naturalists were led
to look up the H'ork of Mendel.
The great discover)' of Mendel ma\' be called that of
the purity of the germ-cells. By cross- fertilization of pure
breeds of peas of diffcR'nt colors and shapes he obtained
hybrids. The hjbrid cmbodictl the characteristics of the
crossed peas; one of the characteristics appearing, and the
other being held in abeyance— present within the organization
;dbyGOOglC
S'** BIOLOGY AND ITS MAKERS
of the pea, but not \isiblc. When peas of different color
were cross-fertilized, one color would be stronger apparently
than the other, and would stand out in the hybrids. This
was called the dominant color. The other, which was held
in abeyance, was called recessive; for, though unseen, it was
still present within the young seeds. That the recessive
color was not blotted out was clearly shown by raising a
crop from the hybrid, a condition under which they would
produce seeds like those of the two original forms, and in
equal number; and thereafter the descendants of these peas
would breed true. This so-called purity of the germ-cells,
then, may be expressed in this way; "The hybrid, whatever
its own character, produces ripe genn-cells, which produce
only the pure character of one parent or of the other"
(Castle).
Although Mendel's discovery was for a long time over-
looked, happily the facts were re -discovered, and at the
l>resent time extensile experiments arc being made wiih
animals to test this law: experiments in the inheritance of
jxiultiy, the inheritance of fur in guinea-pigs, of L-reclness
in the ears of rabbits, etc., etc. In this countn.' the ex[)iTi-
roents of Castle, Davenport, and others with animals lend
to support Mendel's conclusion and lift it to the |x>sItion of
a law.
Rank of Mendel's Discovery. —The discover>- by Mendel
of alternative inheritance wilt rank as one of the greatest
discoveries in the study of heredity. The fact thai in cross-
breeding the i>ari'nlal <|uatities are not blended, but that they
retain their individuahty in the offspring, has many ]K)hsil)le
practical applications both in horticulture and in the breedbg
of animals. The germ-cells of the hybrids have the dominant
and the recessive characters about e<juaily divided; this will
appear in the progeny of the second generalion, and ihc races,
when once separated, may be made to breed true.
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HEREDITY AND GERMINAL CONTINUITY
317
Mendel's name was not recognized as a prominent one
in the annals of biological history- until there-discover>of his
law in 1900; but now he is accorded high rank. It may be
remarked in jassing that the three leading names in the
tlc\elopment of the theories of heredity are those of Mendel,
Gallon, and Weismami.
Galton.— The application of statistical methods is well
illustrated in the theories of Francis Galton (Fig, 96). This
FlO. c)6
distinguished English statistician was bom in i822,and is still
living. He is the grandson of Dr. Erasmus Danvin and the
lousin of Charles. After publishing Ixxiks on his travels in
Africa, he ijcgan the experimental study of heredity and, in
1871, he read before the Royal Society of Ix)ndon a paper
;dbyGOOglC
3l8 BIOLOGY AND ITS MAKERS
on Pangenesis, in which he departed from that theorj' as
developed by Darwin. The obscr\'ation5 upon which he
based his conclusions were made upon the transfusion of
blood in rabbits and their aflcr-brccding. He studied the
inheritance of stature, and other characteristics, in human
families, and the inheritance of spots on the coat of certain
hounds, and was led to formulate a law of ancestral inher-
itance which received its clearest expression in his book,
Natural Inheritance, published in 1889.
He undertook lo determine the proiK>rtion of heritage
that iSj on the average, contributed by each parent, grand-
parent, etc., and arrived at the following conclusions: " The
parents together contribute one-half Ihc total heritage, the
four grandparents together one-fourth, the eight great-grand-
parents one -sixteenth, and all the remainder of the ancestry
one-sixteenth."
Karl Pearson has investigated this law of ancestral inher-
itance. He substantiates the law in its principle, but modifies
slightly the mathematical expression of it.
This field of research, which involves measurements and
mathematics and the handling of large bodies of statistics,
has been considerably cultivated, so that there is in existence
in England a journal devotc-d exclusively lo biometrics, which
is edited by Karl Pearson, and is entitled lihmetrika.
The whole subject of heredity is undergoing a thorough
revision. What seems to be most needc-d at the present time
is more exact experimentation, carried through several gen-
erations, together with more si'arching investigations into
the microsiopical conslifulion of egg and sperm, ami close
analysis of just what tpkes place during fertilization and the
carlv stagus of the de\'eio])ment of the individual. Experi-
ments are being conduitfri on an exlL'ntk-d stale in endowed
inslilutions. There is notably in this country, eslablishcfl
undiT the Cumegic Institution, a station for experimental
;dbyGOOglC
HEREDITY AND GERMINAL CONTINUITY 319
evolution, at Cold Spring Harbor, New York, of which C. B.
Davenport is director. Other experimental stations in Eng-
land and on the Continent have been established, and we
are to expect as the result of codrdinaled and continuous
experimental work many substantial contributions to the
knowledge of inheritance.
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CHAPTER XV
THE SCIENCE OF FOSSIL LIFE
It gradually dawned on the minds of men that the crust
of the earth is like a gigantic mausoleum, containing within it
the remains of numerous and varied forms of life that for-
merly existed upon the surface of the earth. The evidence
is clear that untold generations of living forms, now pre-
sened as fossils, inhabited the earth, disported themselves,
and passed away long before the advent of man. The knowl-
edge of this fossil life, on account of its great diversity, is
an essential part of biology, and all the more so from the
circumstance that many forms of life, remains of which
are exhibited in the rocks, have long since become extinct.
No history of biology would be complete without an account
of the rise and progress of that department of biology which
deab with fossil life.
It has been determined by collecting and systematically
studying the remains of this ancient life that they bear testi-
mony to a long, unbroken history in which the forms of both
animals and plants have been greatly altered. The more
ancient remains are simple in structure, and form with the
later ones, a series that exhibits a gradually increasint; com-
plexity of structure. The study of the fossil siries has
brought about a very great extension of our knowledge
rcganling the age of the world and of the conditions undir
which life was evolved.
Strange Views Regarding Fossils.— Hut this state of our
knowledge was a long time cominj;, and in the devcloiiment
;dbyGOOglC
SCIENCE OF FOSSIL LIFE 321
of the subject we can recognize several distinct epochs, " well-
marked by prominent features, but like all stages of intellec-
tual growth, without definite boundaries." Fossils were
known to the ancients, and by some of the foremost philos-
ophers of Greece were understood to be the remains of
animals and plants. After the revival of learning, however,
lively controversies arose as to their nature and their meaning.
Some of the fantastic ideas that were entertained regarding
the nature of fossil remains may be indicated. The fossils
were declared by many to be freaks of nature; others main-
tained that they were the results of S[X)nlaneous generation,
and were produced by the plastic forces of nature within the
rocks in which they were found embedded. Another opinion
expressed was that they were generated by fermentations.
As the history of intellectual development shows, the mind
has ever seemed benumbed in the face of [phenomena that
are comjdctely misconcei\ed ; mystical explanations ha\e ac-
cordingly been devised to accoimt for them. Some of the
pious persons of that period declared that fossils had been
made and distributed by the Creator in pursuance of a plan
beyond our comprehension, .\nother droll opinion expressed
was that the Creator in His wisdom had introduced fossil
forms into the rocks in order that they should be a source of
confusion to the race of geologists that was later to arise.
And still another fantastic conception suggested that the
fossils were the original molds used by the Creator in form-
ing different varieties of animals and plants, some of which
had been used and others discarded. It was supposed that
in preparing for the creation of life He experimented and
discarded some of His earliest attempts; and that fossils
represented these discarded molds and also, perhaps, some
that had been used in fashioning the created forms,
When large bones, as of fossil elephants, began to be
exhumed, they became for the most part the objects of stupid
;dbyGOOglC
322 BIOLOGY AND ITS MAKERS
wonder. The passage in the Scriptures was pointed out,
that "there were giants in those days," and the bones were
taken to be e\idences of the former existence of giants. The
opinions expressed regarding the fossil bones were \'aried and
fantastic, "some saying that they were rained from Heaven,
others saying that they were the gigantic limbs of the ancient
patriarchs, men who were bclie\ed lo be tall because ihcy
were known lo be old." Following out this idea, "Henrion
in 1718 published a work in which he assigned to Adam a
height of 123 feet 9 inches, Noah being 20 feet shorter, and
so on."
Determination of the Nature of Fossils.— In due course
it came to be recognized that fossils were the remains of forms
that had been alive during earlier periods of lime; but in
reaching this position there was continual controvcrs)-. Ob-
jections were e5[x;cial[y vigorous from theological quarters,
since such a conclusion was deemed to be contradictory to
the Scriptures. The true nature of fossils had been clearly
perceived by Leonardo da Vinci (1452-1519) and certain
others in the sixteenth ccniurj'.
The work, however, that approached more nearly to sci-
entific demonstration was that of Stcno (1638-1686), a
Dane who migrated to Italy and became the court physician
to the dukes of Tuscany. He was a versatile man who had
laid fast hold upon the new learning of his day. Eminent
as anatomist, physiologist, and physician, with his ever
active mind he undertook to encompass all learning. It is
interesting that Sleno — or Sicnsen — after being passionately
devoted to science, became equally de\'oled to religion and
thcolog}', and, forsaking all scientific pursuits, look orders
and returned to his native country with the title of bishop.
Here he worked in the sen'ice of humanity and religion to
the end of his life.
In reference to his work in geology, his conclusions
;dbyGOOglC
SCIENCE OF FOSSIL LIFE 3^3
regarding fossils (1669) were based on the dissection of the
head of a shark, by which means he showed an almost exact
correspondence between certain glossy fossils and the teeth
of li\-ing sharks. He applied his reasoning, that like effects
imply like causes, to all manner of fossils, and clearly estab-
lished ihe point that the)' should be regarded as the remains
of animals and plants. The method of in\'cstigation prac-
ticed by Steno was that "which has consciously or uncon-
sciously guided the researches of palieontologists ever since."
Although his conclusions were well supported, they did not
completely overthrow the opposing views, and become a fixed
basis in geolog)\ WTien, at the close of the eighteenth cen
turj' and the beginning of the nineteenth, fossil remains were
Ijcing exhumed in great quantities in the Paris basin, Cuvier,
the great French naturalist, reestablished the doclrinc that
fossils are the remains of ancient life. An account of this
will be given presently, and in the mean time we shall go on
with the consideration of a question raised by the conclusions
of Steno,
Fossil Deposits Ascribed to the Flood. — After it began to
be reluctantly conceded that fossils might possibly be the
remains of former generations of animals and plants, there
followed a period characterized by the general belief that these
entombed forms had been deposited at Ihe time of the
Mosaic deluge. This was the prevailing view in the eight-
eenth cenlun-. As obsenation increased and the extent and
variety of fossil life became knowTi, as well as the positions
in which fossils were found, it became more difficult to hold
this \\cvf with any appearance of reason. Large forms were
found on the tops of mountains, and also lighter forms were
found near the bottom. Miles upon miles of superimposed
rocks were discovered, all of them bearing quantities of
animal forms, and the interpretation that these had been
killed and distributed by a deluge became verj' strained. But
;dbyGOOglC
SH BIOLOGY AND ITS MAKERS
to the reasoners who gave free play to their fancies the facts
of obsen'ation afforded little difficulty. Some declared that
the entire surface of the earth had been reduced to the con-
dition of a pasty mass, and that the animals drowned by the
Deluge had been deposited within this pasty mass which,
on the receding of the waters, hardened into rocks.
The belief that fossil deposits were due to the Deluge
sensibly declined, however, near the close of the eighteenth
centurv", but was still warmly debated in the early part of the
nineteenth century. Fossil bones of large tropical animals
having been discovered about 1821, embedded in the stalag-
mite-covered floor of a ca^cm in Yorkshire, England, some
of ihc ingenious supporters of the flood-theorj' maintained
that caves were produced by gases proceeding from the bodies
of decaying animals of large size; that they were like large
bubbles in the crust of the earth, and, furthermore, that bones
found in caverns were either those from the decayed carcasses
or others that had been deposited during the occurrence of
the Flood.
Even the utterances of Cuvier, in his theon.' of catastro-
phism to which we shall presently return, ga\e countenance
to the conclusion thai the Deluge was of universal extent.
As late as 1823, William Buckland, reader in geology in
Oxford, and later canon (1825} of Christ Church, and dean
(1815) of Westminster, published his Retiquue Dituviamt, or
Observations on the Organic Remains Attesting the Action 0}
a Universal Deluge.
The theor}' that the Mosaic deluge had any part in the
deposit of organic fossils was finally surrendered through the
ad\ancc of knowledge, owing mainly to the lators of Lyell
and his followers.
The Comparison of Fossil and Living Animals. — The very
great interest connected ^vith the rcestablishment of the con-
clusion of Sleno, that fossils were once alive, leads us to
;dbyGOOglC
SCIENCE OF FOSSIL LIFE 3=5
speak more at length of the discoveries upon which Cuvier
passed his opinion. In the gypsum rocks about Paris the
workmen had been turning up to the tight bones of enormous
size. While the workmen could recognize that they were
bones of some monsters, they were entirely at loss to imagine
to what kind of animals they had belonged, but the opinion
was frequently expressed that they were the bones of human
giants.
Cuvier, with his extensive preparation in comparative
anatomy, was the best &tted man perhaps in all the world
to pass judgment upon these particular bones. He went
to the quarries and, after observing the remains, he saw
very clearly that they were different from the bones of any
animals now existing. His great knowledge of comparative
anatomy was founded on a comprehensive study of the bony
system as well as the other structures of all classes of living
animals. He was familiar with the anatomy of elephants,
and when he examined the large bones brought to light in the
quarries of Montmartre, he saw that he was confronted with
the bones of elephant-like animals, but animals differing in
their anatomy from those at present living on the earth.
The great feature of Cuvier's investigations was that he
instituted comparisons on a broad scale between fossil re-
mains and living animals. It was not merely that he fol-
lowed the method of investigation employed by Stcno; he
went much further and reached a new conclusion of great
importance. Xot only was the nature of fossil remains
determined, but by comparing their structure with that of
living animals the astounding inference was drawn that the
fossil remains examined belonged to forms that were truly
e.flinct. This discovery marks an epoch in the development
of the knowledge of extinct animals.
Cuvier the Founder of Vertebrate Palteontology, — The
interesting discovery' that the fossil relics in the Eocene rocks
;dbyGOOglC
326 BIOLOGY AND ITS MAKERS
about Paris embraced extinct species was announced to the
Institute by Cuvier in January, 1796; and thereafter he con-
tinued for a quarter of a century to devote much atlcniion
to the systematic study of collections made in that district.
These obsenations were, ho\ve\cr, shared with other labors
upon comparati\e anatomy and zoology-, which indicates the
prodigious industry- for which he was notable. In 1812-
1813 he published a monumental work, profusely illustrated,
under the title Ossemens Fossilcs. This standard publication
entitles him to recognition as the founder of vertebrate
palaeontology.
In examining the records of fossil life, Cuvier and others
saw that the evidence indicated a succession of animal popu-
lations that had become extinct, and also that myriads of new
forms of life appeared in the roc]:s of succeeding ages. Here
Cuvier, who lx'lie\X'd that six'cies were fixed and unalterable,
was confronted with a puzzling problem. In attempting to
account for the extinction of life, and what seemed to him
the creation of new forms, he could see no way out consistent
with his theoretical views except to assume that the earth
had periodically been ihe scene of great calastrophcs, of
which the Mosaic deluge was the most recent, but ]x>ssibly
not the last. He supposed that these cataclysms of nature
rcsulte<l in the extinction of all life, and that after each catas-
trophe the salubrious condition of the earth was restored,
and that it was re-peopled by anew creation of living beings.
This conception, known as the theorj- of catastrophism,
was an obstacle to the progress of science. It is to be re-
grellcd that Cu\icr was not able to accept the views of his
illustrious contemporary Lamarck, who believed that the
variations in fossil life, as well as those of living forms, were
owing to gradual transformations.
Lamarck Founds Invertebrate Palfeootology. — The credit
of founding the science of palEontologj- does not belong
;dbyGOOglC
SCIENCE OF FOSSIL LIFE S^?
exclush-ely to Cuvier. Associated with his name as co-
founders are those of Lamarck and William Smith. Lamarck,
that quiet, forceful thinker who for so many years worked
by the side of Cuvier, founded the science of in\ertebrate
paleontology. The large bones with which Cuvier worked
were more easy to be recognized as unique or as belonging
to extinct animals than the shells which occurred in abundance
in the rocks about Paris. The latter were more difficult to
place in their true position because the number of forms
of life in the sea is very extended and ver\' di\erse. Just as
Cuvier was a complete master of knowledge regarding verte-
brate organization, so Lamarck was equally a master of that
vast domain of animal forms which are of a lower grade
of organization — the invertebrates. From his study of the
collections of shells and other invertebrate forms from the
rocks, Lamarck created invertebrate palieontology and this,
coupled with the work of Cuvier, formed the foundations of
the entire field.
Lamarck's study of the extinct invertebrates led him to
conclusions widely at variance with those of Cuvier. Instead
of thinking of a scries of catastrophes, he saw that not all of
the forms of life belonging to one geological jx^riod became
extinct, but that some of them were continued into the suc-
ceeding period. He saw, therefore, that the succession of
life in the rocks bore testimony to a long scries of gradual
changes upon the earth's surface, an<i did not in any way
indicate the occurrence of catastrophes. The changes, ac-
cording to the views of Lamarck, were all knit together into
a continuous process, and his conception of the origin of life
upon the earth grew and expanded until it culminated in the
elaboration of the first consistent theory of evolution.
These two men, Lamarck and Cuvier, form a contrast
as to the favors distributed by fortune: Cuvier, picturesque,
highly honored, the favorite of princes, advanced to the
;dbyGOOglC
32S BIOLOGY AND ITS MAKERS
highusi places of recognition in the government, acclaimed
OS the Jove of natural science; Lamarck, hard-working, ha-
rassed by poverty, insufficiently recognized, ami, although
more gifted than his confr&re, overlookc'd by the scientific
men of the time. The judgment of the relative position of
thcsi' two men in natural sc-iencc is now being reversed, and
on the basis of intellectual supremacy Lamarck is coming
into general recognition as the better man of the two. In
the chapters dealing w^lh organic evolution some events in
thi' life of this remarkable man will be given.
The Arrangement of Fossils in Strata. — The other name
as>ociated with Lamarck and Cuvier is that of William Smith,
the English surveyor. Both Lamarck and Cuvier were men
of e.\len(ied scientilic training, but William Smith Iiad :i
moderate education r.s a surveyor. While the tv.o fijnr.er
were able to exjiress scientific opinions ujK»n the nature of
the fossil forms discovered, William Smith went at his task
as an obscTver with a clear and unprejudiced mind, an
obsiTver who walked about over the fields, noticing the con-
ditions of rocks and of fossil forms embedded therein. He
nnied that the organic remains were (listributul in strata,
and iliiU particular forms of fossil lifr cbaracleri^'.ed par-
ticular strata and occupied the same relative ]>osilion to one
annilier. He found, for illuslralion, that certain ]>articukir
forms would be found underlying certain other forms in one
mass of rocks in a certain ])arl of the country. Wherever
he traveled, and whatever rocks he examined, he found ihesi-
forms occupying the same relative posiiinns. and thus he
came to the conclusion that the living forms within the nxks
constitute a siratilied scTies, having definite and unvarying
arrangement with reference to one another.
In short, the work of these three men — Cuv ier, Lamarck,
and William Sniilh —placed Ihe new science of ]ial;eontology
upon a secure liii^is :it the beginning of the nineteen th cinlury.
;dbyGOOglC
SCIENCE OF FOSSIL LIFE 3^9
Suminary.— The chief steps up to this time in the growth
of the science of fossil hfe may now be set forth in cate-
gories, though we must remember that the advances pro-
ceeded concurrently and were much intermingled, so that,
whate\cr arrangement we may adopt, it does not represent
a strict chronological order of events:
I. The determination of the nature of fossils. Owing to
the labors of Da \'inci, StenO|and Cuvicr,lhe truth was estab-
lished that fossils are the remains of former generations of
animals and plants.
II. The comparison of organic fossils with living forms
that was instituted on a broad scale by Cuvier resulted in the
Conclusion that some of the fossils belong to extinct races.
The belief of Cuvier that entire [wpulalions became e.\tinct
simuitananisly, led him to the thcxjry of catastrophism. The
obsiTvalions of Lamarck, that, while some sjx-cies disappear,
others are continued and pass through transmutations, were
contrary to that theory.
III. The recof^ition that the stratified rocks in which
fossils arc distributed are sedimentary deposits of gradual
formation. This observation and the following took the
groimd from under the theon." that fossils had been deposited
during the Mosaic deluge.
I\'. The discovery by William Smith that the arrangement
of fossils within rocks is alwa>'s the same, and the relative
age of rocks may be determined by an examination of their
fossil contents.
U]X)n Ihc basis of the foregoing, we come to the next
advance, viz.:
\'. The application of this knowledge to the determination
of the histor}- of the earth.
Fossil Remains as an Index to the Past History of the
Earth.— The most advanced and enlightened position that
had been taken in reference to the fossil scries during the
;dbyGOOglC
33° BIOLOGY AXD ITS MAKERS
first third of the nineteenth centur)- was that taken by
Lamarck, he being the first to read in the series the history
of life upon the globe, wca\ing it into a connected storj', and
establishing thereon a doctrine of organic evolution. It was
not until after 1859, however, that the truth of this conclusion
was generally admitted, and when it was accepted it was not
through the earlier publications of Lamarck, but through
the arguments of later obser^■ers, founded primarily upon
the hypothesis set forth by Darwin, There were several
gradations of scientific opinion in the period, short as it
was, between the time of Cuvierand of Darwin; and this
intermediate period was one of contention and warfare
between the theologians and the geologists, Cuvier had
championed the theon' of a succession of catastrophes, and
since this hypothesis did not come into such marked conllict
with the prevailing theological opinion as did the views of
Lamarck, the theologians were ready to accept the notion of
Cuvier, and lo point with considerable satisfaction lo his
unique position as an authority,
Lyell. — In 1830 there was published an epoch-making
work in gwlogy by Charles Lyell (Fig, 97), aftenvard
Sir Charles, one of Ihe most brilliant geologisis of all Ihc
world. This Brilish leader of scienlific thought showed the
prevalence of a uniform law of development in aference lo
the earth's surface. He |»inled out the fact that had been
maintained by Hutton, that changes in the past were to be
interpreted in the light of what is occurring in the present.
By making a careful study of the work performed by the
waters in cutting down the continents and in transferring the
eroded material to other places, and distributing it in the form
of deltas; by obsening also the action of frost and wind and
wave; by noting, furthermore, the conditions under which
animals die and are subsi-i | uently covered up in the matrix
of detritus — by all this he showed evklences of a series of
;dbyGOOglC
SCIENCE OF FOSSIL LIFE 331
slow, continuous changes Ihat have occurred in the past and
ha\c molded the earth's crust into its present condition.
He showed, further, that organic fossils are no exception
to this law of uniform change. He pointed to the evidences
that ages of time had been required for the formation of the
rocks bearing fossils; and that the regular succession of animal
Fic. 97.— Charles Lvell. i7<)7-i8r5-
forms indicates a continual process of development of animal
life; and that the disappearance of some forms, that is, their
becoming extinct, was not owing to sudden changes, but to
gradual changes. When this view was accepted, it overthrew
the theorj' of catastrophism and replaced it by one designated
uniformatism, based on the pre\alence of uniform natural
laws.
This new conception, with all of its logical inferences,
;dbyGOOglC
332 BIOLOGY AND ITS MAKERS
was scouted by ihose of theological bias, but it won its way
in ihc scientific world and became an important feature in
preparing for the reception of Darwin's great book upon the
descent of animal life.
We step forward now to the year 1859, to consider the
effect upon the science of palaeontology of the publication of
Darwin's Origin 0} Species. Its influence was tremend-
ous. The geological theories that had provoked so much
controversy were concerned not merely with the disappear-
ance of organic forms, but also with the introduction of new
species. The Origin oj Species made it clear that the only
rational point of view in reference to fossil life was that it
had been gradually developed, that it ga\c us a picture of
the conditions of life upon the globe in past ages, that the
succession of forms wilhin the rocks represented in outline
the successive steps in the formalion of different kinds of
animals and plants.
Owen. — Both before and after Darwin's hypothesis was
given to science, notable anatomists, a few of whom must be
mentioned, gave attention to fossil remains. Richard Owen
(1804-1892) had his interest in fossil life stimulated by a
visit to Cuvier in 1831, and for more than forty years there-
after he published studies on the structure of fossil animals.
His studies on the fossil remains of Australia and New
Zealand brought to light some inleresling forms. The ex-
tinct giant bird of New Zt.'aland (Fig. 98) was a s[>eclacu]ar
demonstration of the enormous size to which birds had
attained during the Eocene i)eriod. Owen's monogra]>h
(1879) on the oldest known bird — the archa'opteryx — tie-
scribed an interesting form uniting both bird-like and rep-
tilian characleri sties.
Agassiz.- Louis .\gassiz (1807-1873) (Fig. i.)i)) also came
into close jHTSonal cnniart wilh ("uvier, and pnxiucttl his
lirsi m-al work parilv under iJie stimulus of the latter. When
;dbyGOOglC
■rmiviion of U. AppkloT, ^ Co.
;dbyGOOglC
334
BIOLOGY AND ITS MAKERS
Agassiz visited Paris, Cuvier placed his collections at Agassiz^
disposal, together with numerous drawings of fossil fishes.
The profusely illustrated monc^aph of Agassiz on the fossil
fishes {1833-1844) began to appear in 1S33, the year after
S07-.873,
Cuvicr's eleulh, ant! was carried on eleven _vears before it was
completed.
Agassiz, with liiscxlensive knowledge of the developmen-
tal stages of animals, came to see a marked parallelism
between the stages in dc\*eto])mcnt of the embryo and the
successive forms in the geological scries. This remarkable
parallelism between (he fossil forms of life and Ihe stages
;dbyGOOglC
SCIENCE OF FOSSIL LIFE 335
in the development of higher forms of recent animals is
very interesting and \'er}- significant, and helps materially
in elucidating the idea that the fossil series represent roughly
the successi\-e stages through which animal forms have
passed in iheir upward course of development from the
simplest to the highest, through long ages of time. Curi-
ously enough, however, Agassiz failed to grasp the meaning
of the principle that he had worked out. After illustrating
so nicely the process of organic evolution, he remained to the
end of his life an opponent of that theory.
Huxley, — Thomas Henrj- Huxley (1825-1895) was led
to study fossil life on an extended scale, and he shed light in
this province as in others upon which he touched. With crit-
ical analysis and impartial mind he applied the principles
of evolution to the study of fossil remains. His first conclu-
sion was that the evidence of e\-olution deri\-ed from palaren-
tolog)' was negati\-e, but with the advances in discover}' he
grew gradually to recognize that pala»ntologists, in bringing
to light complete e\olutionan- series, had supplied some of
the strongest supporting e^-idence of organic evolution. By
many geologists fossils have been used as time-markers for
the determination of the age of various deposits; but, with
Huxley, the stud)' of them was always biological. It is to
the latter point of view that paleontology owes its great
importance and its great de\elopmcnt. The statement of
Huxlej', that the only difference between a fossil and a recent
animal is that one has been dead longer than the other,
represents the spirit in which the study is being carried
forward.
With the establishment of the doctrine of organic evolu-
tion pala?onlolog\' entered upon its modem phase of growth;
upon this basis there is being reared a worthy structure
through the efforts of the recent votaries to the science. It
is neither essential nor desirable that the present history of
;dbyGOOglC
33^ BIOLOGY AND ITS MAKERS
the subject should be followed here in detail. The coHcc-
lions of material upon which paheontologists arc working
have been enormously increased, and there is perhaps no
place where activitj' has been greater than in the United
States. The rocks of the Western States and Territories
embrace a ver\' rich collection of fossil fnmis, and, through
the generosity of siveral wealthy men, exploring ]tarties ha\ e
been providul for and immense collections have been brought
back lo he jiresi-rved in the must'ums, esjH'ciaily of New
li:i\( n. Ciinn.. and in the American .Museum of Natural His-
tnn in \,^v Vi>rk Cilv.
;dbyGOOglC
SCIENCE OF FOSSIL LIFE
337
Leidy, Cope, and Harsh. — Among the early explorers of
the fossils of the West must be named Joseph Leidy, E. D,
Cope (Fig, too), and O, C. Marsh. These gentlemen all
had access to rich material, and all of them made notable
contributions to the science of palieontology. The work of
G;]>e fi840-r8()7) is ver\' noteworthy. He was a compar-
ative anatomist e([ual to Ciivicr in the extent of his knowl-
edge, and of larger phi lose ])hical views. His extended jmbli-
cations under the direction of the United Slates (lovernmenl
ha\e \er>' greatly extended the knowledge of fossil vertebrate
life in .\mcrica.
;dbyGOOglC
33^ BIOLOGY AN'D ITS MAKERS
O. C. Marsh (Fig. loi) is noteworthy for similar explora-
tions; his discovery of loothed birds in the Western rotks
and his collection of fossil horses, until recently the most com-
plete one in existence, arc all ver\- well known. Throughout
his long life he contributed from his own ])rivale fortune, and
intellectually through his indefatigable labors, to the progress
of pal;eontolog}\
Zittel.^The name most widely known in pala>ontoIog\'
is that of the late Karl von Zillel (i83(>-i904), who devoted
all his working life to the advancement of the science of fos-
sils. In his great work, Ifaitilbtich der PaJaeonlotogie (1876-
1893), he brought under one view the entire range of fossils
from the protozoa up to the mammals. Osbom says: "It
is probably not an exaggeration to say that he did more for
the promotion and diffusion of palxontolog}' than any other
single man who lived during the nineteenth century. While
not gifted with genius, he ])ossessed extraordinary judg-
ment, critical capacity, and untiring industn.." His portrait
(Fig. 102) shows a face "full of keen intelligence and enthu-
siasm."
Zittcl's influence was exerted not otily through his writ-
ings, but also through his lectures and the stimulus imparted
to the lai^e number of young men who were attracted to
Munich to study under his direction. These disciples are
now distributed in various universities in Europe and the
United States, and are there carrying forward the work begun
by Zittel. The great collection of fossils which he left at
Munich contains illustrations of the whole story of the evolu-
tion of life through geological ages.
Recent Developments. — The greatest advance now being
made in the study of fossil vertebrate life consists in establish-
ing the lineage of families, orders, and elassc'S. Investigators
have been esjiecially fortunate in working out the direct line
of descent of a number of living mammals. Fossils have
;dbyGOOglC
SCIENCE OF FOSSIL LIFE
339
been collected which supply a panoramic view of the line of
descent of horses, of camels, of rhinoceroses, and of other
animals. The most fruitful worker in this field at the present
time is perhaps Henrj' F. Osbom, of the American Museum
of Natural Histon,-, New York City. His profound and
important investigations in the ancestry of animal life are
now nearing the time of ihi-ir jjuMicalion in e!al>orated
form.
;dbyGOOglC
34° BIOLOGV AND ITS MAKERS
Palreontolog)-, by treating fossil life and recent life in iJic
same category, has conic To be one of ihc imjxjrtani lines of
invesligation in biology. It is, of course, especially rich in
giving us a knowledge of the hard parts of animals, but by
ingenious methods we can arrive at an idea of some of the
soft ]>arls that have completely disappeared. Molds of the
inierior of (he cranium can be made, and thus one may form
a notion of the relative size and development of the brain
in (lifferenl verlebrated animals. This method of making
mokis and studying them has show-n thai one characteristic
of the geological time of the tertiary period was a markeil
development in regard to (he brain size of the different
animals. There was apparently, just prior to the quaternary
epoch, a need on the part of animals lo have an increast.'d
brain-growth; and one can not doubt thai this feature' which
is demonstrated by fossil life had a great influence in the
development of higher animal forms.
The melliofis of collecting fossils in the field have been
gready developed. By means of spreading mucilage and
tissue pa[)er over delicate bones that crumble on ex]iosure
to the air, and of wrapping fossils in plaster casts for trans-
portation, it has been made possible to uncover and preser\e
many structures which with a rougher method of handling
would have been lost to science.
Fossil Han. — One extremely interesting section of pake-
ontology deals with the fossil remains of the supposed
ancestors of the present human race. Geological evidence
establishes the great antiquity of man, but up to the pn'Sent
time litde systematic exploration has been carriwl on with
a view to discover all possible traces of fossil man. From
time to time since 1840 there have been discovered in ca\'ems
and river-gravels bones which, taken together, constitute an
interesting series. The parts of the skull are of esj)ecial
imtx)rlance in (his kind of study, and there now exisis in
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SCIENCE OF FOSSIL LIFE 341
different collections a scries containing the Neanderthal
skull, the skulls of Spy and Engis, and the Java skull de-
scribed in 1894 by Dubois. There ha\c also Iwen found
recently fXovember, kjo*)! in deposits near Lincoln, Xeb.,
son:e fossil human remains that occupy an inlermediate
jX)sition between the Neanderthal skull and the skulls of the
lower reprc'sentatives of living races of mankind. We shall
ha^e occasion to revert to this f|uestion in considering the
evidences of organic evolution. (See page 364.)
The name palaMntology was brought into use about 1830.
The science affords, in some particulars, the most interesting
field for biological research, and the feature of the rc-con-
struction of ancient life and the determination of the lineage
of living forms has taken a strong hold on the jxjpular imag-
ination. According to Osbom, the most im[x>rtanl pakeon-
tological event of recent limes was the disco\er}', in i()oo, of
fossil Ijeds of mammals in the Fayflm lake-province of Egypt,
about forty-seven miles st)mh of Cairo. Here are embc'ddc-d
fossil forms, some of which have !)een already descriljed in a
volume l>y Charles \V. .\ndrews, which Osl>om says "marks
a tuming-])oint in the history of mammalia of the world."
li is now established that "Africa was a ver>' important center
in ilii' evolution of mammalian life." It is exiK;ctcd that the
lineage of several orders of mammalia will be cleared up
through the further study of fossils from this district.
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THE DOCTRINE OF ORGANIC
EVOLUTION
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CHAPTER XVI
WHAT EVOLUTION IS: THE EVIDENCE UPON
WHICH IT RESTS, ETC.
The preceding pages have been devoted mainly to an
account of the shaping of ideas in reference to the architec-
ture, the physiology, and the development of animal life.
We come now to consider a central theme into which all
these' ideas have been merged in a unified system; viz., the
process by which the diverse forms of animals and plants
have been produced.
Crude speculations regarding the derivation of living
forms are very ancient, and we may say that the doctrine of
organic evolution was foreshadowed in Greek thought. The
serious discussion of the question, however, was reser%cd
for the nineteenth century. The earHcr naturahsts accepted
animated nature as they found it, and for a long time were
engaged in becoming acquainted merely, with the different
kinds of animals and plants, in working out their anatomy
and development; but after some progress had been made
in this direction there came swinging into their horizon
deeper questions, such as that of the deri\-ation of living
forms. The idea that the higher forms of Ufe are de-
ri\cd from simpler ones by a process of gradual evolution
received general acceptance, as we ha\e said before, only
in the last part of the nineteenth century, after the work of
Charles Darwin; but we shall presently see how the theory
of organic development was thought out in completeness by
345
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340 BIOLOGY AND ITS MAKERS
Lamarck in the last years of the eighteenth centur>', and was
further molded by others before Darwin touched it.
Vagueness Regarding Evolution.^Although "evolution"
is to-day a word in constant use, there is still great vagueness
in the minds of most people as to what it stands for; and,
what is more, there is vcrj- little genera! information dissem-
inated regarding the evidence b\' which it is supported , and re-
garding the present statusof thedoctrine in the scientific world.
In its broad sense, evolution has come to mean the devel-
opment of all nature from the past. We may, if we wish,
think of the long train of events in the formation of the world,
and in supplying it with life as a ston- inscribed tipon a scroll
that is being gradually unrolled. E\'er\thing which has
come to pass is on that part so far exposed, and everything
in the future is still covered, but will appear in due course
of time; thus the designation of evolution as "the unrolling
of the scroll of the uni\'crsc" becomes picturesquely sug-
gestive. In its wide meaning, it includes the formation of
the stars, solar systems, the elements of the inorganic world,
as well as all living nature — ihis is general evolution; but
the word as commonly employed is limited to organic ev'olu-
tion, or the formation of life upon our planet. It will be
used hereafter in this restricted sense.
The vagueness regarding the theory of organic e\'olution
arises chiefly from not understanding the points at issue.
One of the commonest mistakes is to confuse Darwinism
with oi^anic evolution. It is known, for illustration, that con-
troversies are current among scientific workers regarding
Danvinism and certain phases of evolution, and from this
circumstance it is assumed that the doctrine of organic
evolution asa whole is losing ground. The discussions of De
Vries and others^all believers in organic evolution — at the
Scienlific Congress in St. I.ouis in n/34, k-d to the statement
in the public press thai the scientific world was haggling
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ORGANIC EVOLUTION 347
over the evolution-theon', and that it was beginning to sur-
render it. Such statements are misleading and tend to per-
petuate the confusion regarding its present slatus. Further-
more, the matter as set forth in writings like the grotesque
little book, Al llie Deathbed oj Danvinism tends to becloud
rather than to clear the atmosphere.
The ihfor)' of organic evolution relates to the histor>- of
animal and plant life, while Darwin's theon- of natural selec-
tion is only one of the various attempts to point out the
causes for that histon.*'s being what it is. .\n attack upon
Danvinism is not, in itself, an attack upon the genera! the-
orj% but upon the adequacy of his explanation of the way
in which nature has brought about the di\-crsity of animal
and plant life. Xatural selection is the particular factor
which Danvin has emphasized, and the discussion of the
part played by other factors tends only to extend the knowl-
edge of the cvolutionarj' process, without detracting from it
as a general theon,-.
While the controversies among scientific men relate for
the most part to the influences that have been operative in
bringing about organic evolution, nevertheless there are a few
in ihc scientific camp who repudiate the doctrine. Fleisch-
mann, of Erlangcn, is perhaps the most conspicuous of those
who are directing criticism against the general doctrine,
maintaining that it is untenable, \^'o^king biologists will be
the first to admit that it is not demonstrated by indubitable
c\idence, but the weight of evidence is so compelling that
scientific men as a body regard the doctrine of organic evolu-
tion as merely expressing a fact of nature, and we can not
in truth speak of any considerable opposition to it. Since
Fleischmann speaks as an anatomist, his suppression of
anatomical facts with which he is acquainted and his form of
special pleading have impressed tlie biological world as lack-
ing; in sincerity.
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348 BIOLOGY AXD ITS MAKERS
This is not the place, howc\'cr, to deal with the technical
aspects of the discussion of ihc factors of organic evolution;
it is rather our purpose here to give a descriptive account of
the theon' and its various explanations. First \vc should
aim to arrive at a clear idea of what the doctrine of ovoiulion
is, and the basis upon which it rests; then of the factors which
have been emphasized in attempted explanations of it; and,
finally, of the rise of evolutionary thought, especially in the
nineteenth centur\-. The bringing forw^ard of these points
will be the aim of the following pages.
Nature of the Question. — It is essential at the outset to
perceive the nature of the question involved in ihe theories
of organic evolution. It is not a metaphysical question, ca-
pable of solution by reflection and reasoning with symlxils;
the data for it must rest ujwn observation of what has taken
place in the past in so far as the records are accessible. It
is not a theological question, as so many have been disposed
to argue, depending upon theological methods of interjireta-
tion. It is not a question of cn'ation through divine agencies,
or of non-creation, but a question of metho<l of creation.
Evolution as used in biology is merely a history of the
steps by which animals and plants came to be what they aa'.
It Is, therefore, a historical question, and must be invi-sligated
by historical methods. Fragments of the story of creation
are foimd in the strata of the earth's crust and in the stages
of embryonic develojjmcnt. Thesi' clues must be brought
together; and the reconstruction of the slon- is mainly a
matter of getting at the records. Drummoml says that evo-
lution is "the sior)- of creation as told by thosc' who know
it best."
The Historical Method.— The historical meliiod as ap-
plied to searching out the early history of mankinil finds a
parallel in the investigations into the question of organic
evolution. In the buried cities of Palestine e\plorcrs have
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ORGANIC EVOLUTION 349
uncovered traces of ancienl races and have in a measure
reconslrutted their histor>- from fragments, such as coins,
various objects of art and of household use, together with
inscriptions on tombs and columns and on thosecurious litllc
bricks which were used for public records and corrcsjxjnd-
encc. One city having been uncovered, il is found by lifting
llie floors of icmples and other buildings, and the pavement
of public 5(]uarcs, that this city, although very ancienl, is
built \]]K>n the ruins of a more ancient one, which in turn
covers the ruins of one still older. In this way, as many as
seven successive cities have been found, built one on to]> of
the other, and new and unex[X'cte(l facts regarding ancienl
civilization have Ixrn brought to light. \Vc must admit that
this gives us an imjjcrfeet hislor)-, with many gaps; but it is
one that commands our confidence, as being based on facts
of obsiTvaiion, and nol on sjjeculation.
In like manner the knowledge of the past history of animal
life is ihe R-'sult of explorations by trained scholars into the
records of the jnisl. We have remains of ancient life in ihe
n;ck5, ;.iid also traces of past conditions in the developing
staples of animals. These are all more ancient than the
inscripiions left by the hand of man u)x»n his tombs, his
li-mples, and his columns, but nevertheless full of meaning
if \\e can only understand them. This historical method of
invest ligation applied to the organic world has brought new
and unexjiecled views regarding the antiquity of life.
The Diversity of Living Forms. — Sooner or later the
question of ihe derivation of the animals and plants is
Ixiurd to come to the mind of the observer of nature. There
i.'.\ist al present more than a million different kinds of
animals. The waters, the earth, the air teem with life.
The fislies of the sea arc almost innumerable, and in a sin-
gle order of the insect-world, the beetles, more than 50,000
species are known and described. In addition to living
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35° BIOLOGY AND ITS MAKERS
animals, there is entombed in the rocks a great multitude
of fossil forms which lived centuries ago, and many of which
have become entirely extinct. How shall this great diversity
of life be accounted for? Has the great varictj- of forms
existed unchanged from the days of their creation to the
present ? Or have they, perchance, undergone modifications
so thai one original form, or at least a few original types,
may have through transformations merged into different
kinds? This is not merely an idle question, insoluble from
the very nature of the case; for the present races of animals
have a lineage reaching far into the past, and the question
of fixity of form as against alteration of type is a historical
question, to be answered by gelling evidence as to their line
of descent.
Are Species Fixed in Nature? — The aspect of the matter
which pressc'S first upon our attention is this: Are the species
(or different kinds of animals and plants) fixed, and, within
narrow limits, permanent, as Linnxus supjxjsed ? Have
they preserved their identity through all lime, or have they
undergone changes? This is the heart of the question of
organic evolution. If observation shows species to be con-
stant at the present lime, and also to have lKx;n continuous
so far as we can trace their parentage, we must conclude that
they have not Ix-en formed b\- evolution; but if we find
evidence of their transmutation into other species, then there
has been e\olution.
It is well established ihat there are wide ranges of varia-
tion among animals and plants, both in a wild state and under
domestication. Great changes in flowers and \egetables arc
brought about through cuhivation, while breeders produce
different kinds of pigeons, fowls, and stock. We know,
therefore, thai living beings may change through modification
of the circumstances and conditions that affect their lives.
Bui general observations extending over a few decades arc
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ORGANIC EVOLUTION 35^
not sufficient. We must, if possible, bring the history of
past ages to bear upon the matter, and determine whether or
not there had been, with the lapse of time, any considerable
alteration in li\'ing forms.
Evolutionary Series. — Fortunately, there are prescned
in the rocks the petrified remains of animals, showing their
history- for many thousands of years, and we may use them
to test the question. It is plain that rocks of a lower level
were deposited before those that co\cr them, and we may
safely assume that the fossils ha\e been prcser\-ed in their
proper chronological order. Now, wc ha\e in Slavonia some
fresh-water lakes that have been drying up from the tertiary
period. Throughout the ages, these waters were inhabited
by snails, and naturally the more ancient ones were the par-
ents of the later broods. As the animals died their shells
sank to the bottom and were covered by mud and debris,
and held there like currants in a pudding. In the course of
ages, by successive accumulations, these layers thickened
and were changed into rock, and by this means shells have
been preser\cd in their proper order of birth and life, the most
ancient at the bottom and the newest at the top. We can
sink a shaft or dig a trench, and collect the shells and arrange
them in proper order.
Although the shells in the ui>pcr strata are descended from
those near the bottom, they are very different in appearance.
No one would hesitate to name them different species; in
fact, when collections were first made, naturalists classified
these shells into six or eight different species. If, however, a
collection embracing shells from all levels is arranged in a
long row in proper order, a different light is thrown on the
matter; while those at the ends are unlike, yet if we begin
at one end and pass to the other we observe that the shells
all grade into one another b}' such slight changes that there
is no line showing where one kind leaves off and another
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352 BIOLOGY AND ITS MAKERS
begins. Thus their histor\- for thousands of years bears
testimony to the fact that the spctics have not remained
constant, but ha\'c cliangci:! into other species.
Fig. 103 will give an idf.i of the varieties and gradations.
It represents shells of a genus. Paludina, which isslill abun-
dant in most of the fresh waters of our globe.
•444*
4 44 4
A similar scries of shells has lurn brought li> light in
Wiintemberg in which the variations pass through wider
limits, so that not only ditTerent species muy Ije obsened,
but different genera Lonneete-d by ahiiost insensible grada
tions. These transformations are found in a liitk' flattfuwi
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OKGAXir IvVOlA'TlOX
[Hind-shdl similar in the ])lanor!)is, which is s<i romm<m at
ihf ijrcscnt linii'.
Fifi- 104 sJiows sonic of thcst' Iransformalions, ihL' finer
j;raiialions hfirif; omiltt'iL Tho shells frtun thcsi- two smiri-cs
hear (iiri'clly iiiiiin (hf qiifstion of whi'lhcr or mil sjniii-s have
hd<l ri;;i(lly lo ihi-ir original form.
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354 BIOLOGY AND ITS MAKERS
After this kind of revelation in reference to lower animals,
we turn with awakened interest to the fossil bones of the
higher animals.
Evolution of the Horse. — \Vhen we take into account the
way in which fossils have been produced wc see clearly that
it is the hard parts, such as the shells and the bones, that will
be presented, while the soft parts of animals will disappear.
Is it not possible that we may find the fossil bones of higher
animals arranged in chronological order and in sufficient
number to supplement the testimony of the shells? There
has been preserved in the rocks of our Western States a vcn'
complete history' of the evolution of the horse familj', written,
as it were, on tablets of stone, and extending over a period
of more than two million years, as the geologists estimate
time. Geologists can, of course, measure the thickness of
rocks and form some estimate of the rate at which they were
deposited by observing the character of the material and com-
paring the formation with similar water deposits of the
present time. Near the surface, in the deposits of the
quarternary period, are found remains of the immediate
ancestors of the horse, which are ricognized as belonging
to the same genus, Equus, but to a different s[)ecies; thence,
back to the lowest beds of the tcrtiar)- period we come
upon the succcssi\e ancestral forms, embracing several dis-
tinct genera and exhibiting an interesting SL-ries of trans-
formations.
If in this way we go into the past a half-million years, we
find the ancestors of the horse reduced in size and with three
toes each on the fore and hind feet. The living horse now
has only a single toe on each fool, but it has small splint-like
bones that R-present the rudiments of two more. If we go
back a million years, we find three toes and the rudiments
of a foiulh; and going back two million years, wc find four
fully developed toes, and bones in the feet to sup|x>rt them.
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ORGANIC EVOLUTION 355
It is believed that in still older rocks a fi\-e-tocd form will be
discovered, which was the parent of the four-toed form.
In the collections at Yale College there are preserved
upward of thirty steps or stages in the history of the horse
family, showing that it arose by e\'olution or gradual change
from a four- or five-toed ancestor of about the size of a fox,
and that it passed through many changes, besides increase
in size, in the two million years in which we can get facts
as to its histor>-.
Remarkable as is this feature of the Marsh collection at
New Haven, it is now surpassed by that in the Museum of
\atural History in New York City. Here, through the
munificent gifts of the late W. C. UTiitney, there has been
accumulated the most complete and cxiensive collection of
fossil horses in the world. This embraced, in 1904, some
portions of 710 fossil horses, 146 having been derived from
explorations under the Whitney fund. The extraordinary
character of the collection is shown from the fact that it
contains five complete skeletons of fossil horses — more than
existed at that time in all other museums of the world.
The sjx'cimens in this remarkable collection show phases in
the parallel development of three or fourdistinct races of horse-
like animals, and this o[>ens a fine problem in comparative
anatomy; viz., to separate those in the direct line of ancestry
of our modem horse from all the others. This has been
accomplished by Oslwm, and through his critical analysis
wv ha\'c become aware of ihe fact that the races of fossil
horsc'S had not been distinguished in any earlier studies,
.\s a result of these .studies, a new anceslrj- of the horse,
differing in details from that given by Huxley and Marsh, is
forthcoming.
Fig. 105 shows the bones of the foreleg of the modem
horse, and Fig, 106 some of the modifications through which
it has passc'd. Fig. 107 shows a reconstruction of the ances-
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350
BIOLOGY AND ITS MAKERS
tor of Ihc horse made by Charles R. Knight, the animal
painter, under the direction of Professor Osbom.
While the limbs were undergoing the changes indicated,
other parts of the organism were also being transfonned
Ihe Foreleg and Hindleg of a Hoi
and adapted to the changing conditions of its life. The
evolution of the grinding tcclh of the horse is fully exhibited
in the fossil remains. All the facts bear testimony that
the horse was not originall)- created as known to-day, but
that his anitstors existed in different forms, and in evolution
have transcended several genera and a considerable num-
Ikt of s])ecies. The highly specialized limb of the horse
adapted for speed was the product of a long scriesof changes,
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ORGANIC EVOLUTION'
357
of which the record is fairly well preserved. Moreover, the
records show that the atavus of the horse began in North
America, and that by migration the primitive horses spread
from this continent to Europe, Asia, and Africa.
So far we have treated the question of fixity of species as
a historical one, and ha\c gone searching for clues of past
conditions just as an archaeologist explores the past in buried
cities. The facts we have encountered, taken in connection
with a multitude of others pointing in the same direction,
begin to answer the initial question. Were the immense num-
bers of living forms created just as we find them, or were
they evolved by a process of transformation ?
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35^ BIOLOGY AND ITS MAKERS
The geological record of other families of mammals has
also been made out, but none so completely as that of the
horse family. The records show that the camels were native
in North America, and that they spread by migration from
the land of their birth to Asia and Africa, probably crossing
by means of land-connections which have long since become
submerged.
The geological record, considered as a whole, shows that
the earlier formed animals were representatives of the lower
groups, and that when \crtebrate animals were formed, for
a very long time only fishes were living, then amjthibians,
reptiles, birds, and finally, after immense reaches of time,
mammals began to apjK'ar.
Connecting Forms.— Interesting connecting forms be-
tween large groups sometimes arc found, or, if not connecting
forms, generalized ones embracing the structural character-
istics of two separate groups. Such a form is the archa»p-
tervx (Fig. io8), a primitive bird with reptilian anatomy,
with teeth in its jaws, and a long, lizard-like tail covered with
feathers, which seems to show connection between birds and
reptiles. The wing also sliows the supernumerary fingers,
which have been suppresscfl in modem birds. .Another sug-
gestive type of this kind is the flying reptile or pterodactyl,
of which a considerable number ha^e been discovered.
Illustrations indicating that animals have hod a common line
of descent might be greatly muUiplic'd.
The Embryological Record and its Connection with Evo-
lution.— The most interesting, as well as the most compre-
hensive clues Ix'aring on ihe exolution of animal life arc
found in the various stages through which animals pass on
their way from the egg to the fully formed animal. All
animals above the proto/^a begin their lives as single cells,
and between that rudimentary condition and the adult stage
every gradation of structure is exhibili.'d. As animals de-
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360 BIOLOGY AND ITS MAKERS
vclop they become successively more and more complex,
and in their shifting history many rudimentary organs arise
and disappear. For illustration, in the young chick, devel-
oping within the hen's egg, there ap[)car, after three or four
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ORGANIC EVOLUTION 3*»i
days of incubation, gill-slits, or openings into the throat,
like the gill-openings of lower fishes. These organs belong
primarily to water life, and arc not of direct use to the chick.
}. — The Gill-clefts of a Shark (upper fig.) Compared with
Those of the Embryonic Chick (to the left) and Rabbit.
The heart and the blood-vessels at this stage are also of the
fish-like type, but this condition does not last long; the gill-
slits, or gill-clefts, fade away within a few days, and the
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3^2 BIOLOGY AND ITS MAKERS
arteries of the head and the neck undergo great changes long
before the chick is halched. Similar gill-clefts and similar
arrangements of blood-vessels appear also very early in the
development of the young rabbit, and in the development
of all higher life. Except for the theory of descent, such
things would remain a lasting enigma. The universal pres-
ence of gill-clefis is not to be looked on as a haphazard
occurrence. Thcj' must have some meaning, and the best
suggestion so far offered is that they are sur\-ivals inherited
from remote ancestors. The higher animals have sprung
from simpler ones, and the gill-slits, along with other rudi-
mcntar}' organs, have been retained in their history. It is
not necessary to assume that they arc inherited from adult
ancestors; they are, more likely, embryonic structures slill
retained in the developmental history of higher animals.
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ORGAN'IC EVOLUTION' 363
Such traces are like inscriptions on ancient columns — they
arc clues to former conditions, and, occurring in the animal
scries, they weigh heavily on the side of evolution.
An idea of the appearance of gill-clefts may be obtained
from Fig. 109 showing the gill-clefts in a shark and those in
the embryo of a chick and a rabbit.
Of a similar nature are the rudimentary teeth in the jaws
of the embryo of the whalebone whale (Fig. no). The
adults have no teeth, these appearing only as transitory rudi-
ments in the embr^'o. It is to be assumed that the teeth are
inheritances, and that the toothless baleen whale is derived
from toothed ancestors.
If we now turn to comparative anatomy, to classification,
and to the geographical distribution of animals, wc find that
it is necessary to assume the doctrine of descent in order
to explain the obsen'ed facts; the evidence for evolution,
indeed, becomes cumulative. But it is not necessary, nor
will space permit, to give extended illustrations from these
various departments of biological researches.
The Human Body. — Although the broad doctrine of evo-
lution rests largely upon the obser^'ation of animals and plants,
there is naturally unusual interest as to its teaching in ref-
erence to the development of the human body. That the
human body belongs to the animal scries has long been
admitted, and that it has arisen through a long series of
changes is shown from a study of its structure and develop-
ment. It retains marks of the scaffolding in its building.
The human body has the same devious course of embryonic
development as that of other mammals. In the course of
its formation gill-clefts make their appearance; the circula-
tion is successively that of a single-, a double-, and a four-
chambered heart, with blood-vessels for the gill-clefts. Time
and encrgv- are consumed in building up rudimentary struc-
tures which are evanescent and whose presence can be best
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364 BIOLOGY AND ITS MAKERS
explained on the assumption that they arc, as in other animals,
hereditan' survivals.
Wiedershcim has pointed out more than one hundred
and eighty rudimentary or vestigial structures belonging to
the human body, which indicaie an evolutionarj' relation-
ship with lower vertebrates. It would require a considerable
treatise to present the discoveries in reference to man's
organization, as Wiedershcim has done in his Structure of
Man. As passing illustrations of the nature of some of these
suggestive things bearing on the question of man's origin
may be mentioned: the strange grasping power of the newly
bom human infant, retained for a short time, and enabling
the babe to suslain its weight ; the presence of a tail and
rudimentary tail muscles; of rudimentary ear muscles; of
gill-clefis, etc.
Antiquity of Man. — The geological histor>' of man is
imperfectly known, although si^radic explorations have
already accumulated an interesting series, especially as
regards the shape and capacity of skulls. The remains of
early quarlemary man have been unearthed in various parts
of Europe, and the probable existence of man in the tertiary
period is generally admittal. As Osbom says, "Virtually
three links have been found in the chain of human ancestry."
The most primitive pre-human S[X'cies is represented by
portions of the skull and of the leg bones found in Java by
the Dutch surgeon Dubois in the years i8qi and 1892.
These remains were found in tertiary deposits, and were
baptized under the name of Pilkecantkropus crcclus. The
structural position of this fossil is between ihe chimpanzee,
the highest of anthropoid apes, and the " Xeandcrthal man."
With characteristic .scientific caution Osborn says that the
Pithecanthropus "belongs in the line of none of the existing
anthropoid apes, and falls very near, but noi directly, in
the line of human ancestry."
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ORGANIC EVOLUTION 3^5
The second link is supplied by the famous Neanderthal
skull found in the valley of the Neander, near Diisseldorf,
in 1857. The discovery of this skull, with its receding fore-
head and prominent ridges above the orbits of the eyes, and
its small cranial capacity, created a sensation, for it was soon
seen that it was intermediate between the skulls of the lowest
human races and those of the anthropoid apes. Virchow
declared that if the skull was pre-human its structural char-
acteristics were abnormal. This conclusion, however, was
rendered untenable by the discover)' in 1886 of similar skulls
and the skeletons of two persons, in a cave near Spy in Bel-
FiG. 1 1 1 . — Profile Reconstructions of the Skulls of Living and
Fossil Men; 1. Brachy cephalic European; 2, The more ancient
of the Nebraska skulls; 3. The Neanderthal man; 4, One of the
Spy skulls; 5. Skull of the Java man. (Altered from Schwalbe
and O shorn.)
gium. The " Spy man " and the " Neanderthal man " belong
to the same type and are estimated to have been living in the
middle of the palaeolithic age.
The third link is in the early Neolithic man of Eogis.
And now to this interesting series of gradations has been
;dbyGOOglC
3^6 BIOLOGY AND ITS MAKERS
added another by the discovery in 1906 of a supposed prim-
itive race of men in Nebraska. The two skulls unearthed
in Douglass County in that State indicate a cranial capacity
falHng below that of the " Australian negro, the lowest existing
type of mankind known at present,"
Fig. Ill shows in outline profile reconstructions of the
skulls of some of the fossil types as compared with the short-
headed type of Europe,
Pal^ontological disco\eries are thus coming to support
the evidences of man's evolution derived from embryologj-
and archieology. While we must admit that the geological
evidences are at present fragmentar\-, there is, nevertheless,
reasonable ground for the expectation that they will be
extended by more systematic explorations of caverns and
deposits of the quartemary and late tcrliarj' periods.
Mental Evolution. — Already the horizon is being wid-
ened, and new problems in human evolution have been opened.
The evidences in reference to the evolution of the human
body are so compelling as to be already generally accepted,
and we have now the question of evolution of mentality to
deal with. The progressive intelligence of animals is shown
to depend upon the structure of the brain and the ner^-ous
system, and there exists such a finely graded series in this
respect that there is strong evidence of the derivation of hu-
man faculties from brute faculties.
Sweep of the Doctrine of Evolution. — The great sweep
of the doctrine of evolution makes it "one of the greatest
acquisitions of human knowledge." There has been no
point of intellectual vantage reached which is more inspiring.
It is so comprehensive that it enters into all realms of thought.
Weismann expresses the opinion thai "the theory of descent
is the most progressive step that has been taken in the devel-
opment of human knowledge," and says that this {wsition
"is justified, it seems to me, even by this fact alone: that the
;dbyGOOglC
ORGANIC EVOLUTION 367
e\-olulion idea is not merely a ne«- light on the special region
of biological sciences, zoology and botan\', but is of quite
general importance. The conception of an evolution of life
upon the earth reaches far beyond the bounds of any sin-
gle science, and influences our whole realm of thought. It
means nothing less than the elimination of the miraculous
from our knowledge of nature, and the placing of the phe-
nomena of life on the same plane as the other natural proc-
esses, that is, as having been brought about by the same
forces and being subject to the same laws."
One feature of the doctrine is \cr)' inleresling; it has
enabled anatomists to predict that traces of certain structures
not present in the adult will be found in the embr>'onic condi-
tion of higher animals, and by the verification of these predic-
tions, it receives a high degree of plausibility. The presence
of an OS centrale in the human wrist was predicted, and after-
ward found, as also the presence of a rudimentar>' thirteenth
rib in early stages of the human body. The predictions, of
course, arc chief!)- technical, but they are based on the Idea
of common descent and adaptation.
It took a long time c\en for scientific men to arrive at a
belief in the continuity of nature, and having arrived there,
it is not easy to surrender it. There is no reason to think
that the continuity is broken in the case of man's develop-
ment. Naturalists have now come to accept as a mere state-
ment of a fact of nature that the vast variet;' of forms of life
upon our globe has been produced by a process of evolution.
If this position be admitted, the next question would be,
What are the factors which have been operative to bring this
about? This brings us naturally to discuss the theories of
evolution.
;dbyGOOglC
CHAPTER XVII
THEORIES OF EVOLUTION: LAMARCK, DARWIN
The impression so generally entertained that the doctrine
of organic evolution is a vague hypothesis, requiring for its
support great stretches of the imagination, gi\es way to an
examination of the facts, and we come to recognize that it is
a well-founded theon', resting upon great accumulations of
evidence. If the matter could rest here, it would be rela-
tively simple; but it is necessary to examine into the causes
of the evo!utionar>' process. While scientific obsenation has
shown that species are not fixed, but undergo transforma-
tions of considerable extent, there still remains to be accounted
for the way in which these changes ha^e been produced.
One may assume that the changes in animal life are the
result of the interaction of protoplasm and certain natural
agencies in its surroundings, but it is evidently a vcr>' diffi-
cult matter to designate the particular agencies or factors of
evolution that have operated to bring about changes in spe-
cies. The attempts to indicate these factOES give rise to differ-
ent theories of evolution, and it is just here that the contro-
versies concerning the subject come in. We must remember,
however, that to-day the controversies about evolution are
not as to whether it was or was not the method of creation,
but as to the factors by which the evolution of different
forms was accomplished. Says Packard : " We arc all evo-
lutionists, though we may differ as to the nature of the
efficient causes."
Of the various theories which had been advanced to
368
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 369
account for evolution, up to the announcement of the muta-
tion-lheon' of De Vries in 1900, three in particular had
commanded the greatest amount of attention and been the
field for varied and extensive discussion. These are the
theories of Lamarck, Darwin, and Weismann. They are
comprehensive theories, dealing with the process as a whole.
Most of the othersarc concerned with details, and emphasize
certain phases of the process.
Doubtless the factors that have played a part in molding
the forms that have appeared in the procession of life upon
our globe have been numerous, and, in addition to those that
have been indicated, Osbom verv- aptly suggests that there
may be uodiscovered factors of evolution. Within a few
years De Vries has brought into prominence the ideaof sudden
transformations leading to new species, and has accounted
for organic evolution on that basis. Further consideration of
this theory', however, will be postponed, while in the present
chapter we shall endeavor to bring out the salient features
of the theories of Lamarck and Darwin, without going into
much detail regarding them.
Lamarck
Lamarck was the first to give a theory of evolution that
has retained a place in the intellectual world up to the present
time, and he may justly be regarded as the founder of that
doctrine in the modem sense. The earlier theories were
more restricted in their reach than that of Lamarck. Eras-
mus Darwin, his greatest predecessor in this field of thought,
announced a comprehensive theorj', which, while suggestive
and forceful in originality, was diffuse, and is now only of
historical importance. The more prominent writers on evo-
lution in the period prior to Lamarck will be dcah with in
the chapter on the Rise of Evolutionary Thought.
;dbyGOOglC
37° BIOLOGY AND ITS MAKERS
Lamarck was l>om in 1744, and led a quiet, monolonous
life, almost pathetic on account of his struggles with ]>overty,
and the lack of encouragement and projxr recognition by his
contemporaries. His life was rendered more bearable, how-
ever, e\'cn after he was 04crtakcn b\- complete blindness,
by the intellectual atmosphere that he created for himself,
and by the superb confidence and affection of his devoted
daughter Com^lic, who sustained him and made the truthful
prediction that he would be recognized by posterity (" La
posUriti vous hotwrrra").
His Family. — He came of a militar>- family possessing
some claims to distinction. The older name of the family
had been dc Monel, but in the branch to which Lamarck
bclongctl the name had been changed to de Lamarcjue, and
in the days of the first Republic was signed plain Lamarck
by the subject of this sketch. Jean Baptislc Lamarck was
the eleventh and last child of his parents. The other male
members of the family having been provided with military-
occupations, Jean was selected by his father, although
against the lad"s own wish, for the clerical profes.sion, and ac-
cordingly was placed in the college of the Jesuits at .Amiens.
He did not, however, develop a taste for theolof^ical studies,
and after the death of his father in 1760 "nothing could
induce the incipient ablx?, then seventeen years of age,
longer to wear his bands."
His ancestry asserted itself, and he forsook the college to
follow the French army that was then campaigning in Cler-
many. Mounted on a broken-down horse which he had suc-
ceeded in buying with his scanty means, he arrived on the
scene of action, a veritable raw recruit, ai)pearing before
Colonel Laslic, to whom he had brought a letter of recom-
mendation.
Military Experience. — The Colonel would have liked lo
be rid of him, but owing to Lamarck's jx-rsislence, assignwl
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 371
him to a company; and, being mounted, Lamarck took rank
as a sergeant. During his first engagement his company
was c'X[x>sed lo the direct fire of the enemy, and the officers
one after another were shot until Lamarck by order of suc-
cession was in command of the fourteen remaining gren-
adiers. Although the French army retreated, Lamarck
refused to move with his scjuad until he received directions
from headquarters to retire. In this his first battle he
showed the courage and the independence that characterized
him in later years.
Adopts Natural Science. — .\n injury lo the glands of the
neck, resulting from being lifted iiy the head in sport by one
of his comrades, unfitted him for militar)' life, and he went to
Paris and began the study of medicine, supporting himself
in the mean time by working as a bank clerk. It was in his
medical course of four jears' severe study that Lamarck
received the exact training that was needed to convert his
enthusiastic !o\"e for science into the working powers of an
investigator. He became especially interested in Ixitany,
and, after a chance interview with Rousseau, he determined
to follow the ruling passion of his nature and devote himself
lo natural science, .^fter about nine years' work he published,
in 1778, his Flora oj France, and in due course was appointed
to a post in botany in the Academy of Sciences. He did not
hold this position long, but left it to tra\'el with the sons
of Buffon as their instructor. This agreeable occupation
extended o\er two years, and he then returned to Paris, and
soon after was made keeper of the herbarium in the Royal
Garden, a subordinate position entirely beneath his merits.
Lamarck held this poorly paid position for several years, and
was finally relieved by being apjwinted a professor in the
newly established Jardin des Planles.
He took an acti\c part in the reorganization of the Royal
Garden (Jardin du Roi) into the Jardin des Planles. When,
;dbyGOOglC
372 BIOLOGY AND ITS MAKERS
during the French Resolution, cvcn'thing that was suggestive
of royalty became obnoxious to the people, it was Lamarck
who suggesied in 1790 that the name of the King's Garden
be changed to that of the Botanical Garden (Jarditt des
Planles). The Royal Garden and the Cabinet of Natural
History were combined, and in 1795 the name Jardin des
Plantes proposed by Lamarck was adopted for the in-
stitution.
It was through the endorsements of Lamarck and Geodroy
Sainl-Hilaire that Cuvier was brought into this great scientific
institution ; Cuvier, who was later to be advanced alxjve him
in the Jardin and in public fa\or, and who was lo break
friendship with Lamarck and become the oj)|)onent of his
views, and who also was to engage in a memorable debate
with his other su[jjx>ner, Sainl-Hilaire.
The jrortrait of Lamarck shown in Fig. 112 is one not
generally known. Its dale is undetermined, Imt since it was
published in Thornton's British Plants in 1805, we know
that il was painted before the publication of Lamarck's
Philosophie Zoologiqtie, and before the full force of the cold-
ness and heanless neglect of the world had Ix-en exjjtrienced.
In his features we read supremacy of the intellect, and the
unflinching moral courage lor which he was notable. La-
marck has a more ho|}cfu! expression in this jwrtrait than in
those of his later years.
Lamarck Changes from Botany to Zoology. — Unlit 1794,
when he was fifty years of age, Lamarck was demoted to
botany, but on being urged, after the n-organization of Ihe
Jardin du Roi, to take charge of the department of inverte-
brates, he finally consented and changed from the study of
plants to that of animals. This change had profound in-
fluence in shaping his ideas. He found the invertebrates in
great confusion, and sel about to bring order out of chaos,
an undertaking in which, to his credit be it acknowledged,
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 37i
he succeeded. The fruit of his labors, the Natural His-
tory of Invertebrated Animals {Historie nalurelie des Ani-
maux sans Verlfhres, 1815-1822), became a work of great
importance. He took hold of this work, it should be re-
membered, as an expert observer, trained to rigid analysis
;dbyGOOglC
374 BIOLOGY AND ITS MAKERS
by his previous critical studies in botan)'. In ihc progress
of the work he was impressed with the differences in ani-
mals and the difficulty of separating one species from an-
olher. He had occasion to observe the variations produced
in animals through the influence of climate, temperature,
moisture, elevation above the sea-level, etc.
He observed also the effects of use and disuse ujxin the
development of oi^ans; the exercise of an organ leading to
its greater development, and the disuse to its degeneration.
Numerous illustrations are cited by Lamarck which serve to
make his meaning clear. The long legs of wading birds
are produced and extended by stretching to keep above the
water; the long neck and bill of storks are produced by their
habit of life; the long neck of the giraffe is due to reaching
for foliage on trees; the web-fooled birds, by spreading
the toes when they strike the water, have stimulated the
development of a membrane between the toes, etc. In the
reverse direction, the loss of the power of flight in the " wing-
less" bird of New Zealand is due to disuse of the wings;
while the loss of sight in the mole and in blind cave animals
has arisen from lack of use of eyes.
The changes produced in animal organization in this
way were believed to be continued by direct inheritance and
improved in succeeding generations.
He belicxed also in a perfecting principle, tending to
improve animals — a sort of conscious endea\'or on the part
of the animal playing a part in its better development. Fi-
nally, he came to believe that the agencies indicated above
were the factors of the evolution of life.
His Theory of Evolution. — AH that Lamarck had written
before he changed from botany to zoology (1794) indicates
his belief in the fixity of species, which was the prevailing
notion among naturalists of the period. Then, in iSoo, we
find him a]>parently all at once expressing a contrary opinion,
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 375
and an opinion to which he held unwaveringly to the close
of his life. It would be of great inlercsl to determine when
Lamarck changed his views, and ujxtnwhat thisradical rever-
sal of opinion was based; but we ha\e no sure record to
depend upon. Since his theor>' is developed chiefly upon
considerations of animal life, it is reasonable to assume that
his evolutionarj' ideas took form in his mind after he began
the serious study of animals. Doubtless, his mind having
been prepared and his insight sharpened by his earlier studies,
his obser\ations in a new field supplied the data which led
him directly to the conviction that species are unstable.
As Packard, one of his recent biographers, points out, the
first expression of his new views of which we ha\e any record
occurred in the spring of 1800, on the occasion of his opening
lecture to his course on the invertebrates. This a\'owal of
belief in the extensive alteration of species was published in
1801 as the preface to his Syslime ties Animaitx sans
Vertibres. Here also he foreshadowed his theory of evo-
lution, saying that nature, having formed the simplest
organisms, "then with the aid of much time and favor-
able circumstances . . . formed all the others." It has
been generally believed that Lamarck's first public ex-
pression of his views on evolution was published in 1802
in his Reclierches sur VOrganisation des Corps Vivatts,
but the researches of Packard and others have established
the earlier date.
Lamarck continued for several years to modify and am-
plif_\- ihe expression of his A-iews. It is not necessar>-, how-
ever, to follow the molding of his ideas on evolution as
expressed in the opening lectures to his course in the years
iSoc, 1802, 1803, and 1806, since we find them fully elab-
orated in his Philosophie Zoologique, published in 1809,
and this may be accepted as the standard source for the
study of his theory. In this work he states two propositions
;dbyGOOglC
376 BIOLOGY AND ITS MAKERS
under the name of laws, which have been translated by
Packard as follows t
" First Law : In every animal which has not exceeded the
term of its development, the more frequent and sustained
use of any organ gradually strengthens this organ, develops
and enlarges it, and gives it a strength projwrtioned to the
length of time of such use; while the constant lack of use of
such an organ impwrceptibly weakens it, causing it to become
reduced, progressively diminishes its faculties, and ends in
its disappearance.
" Second Law : Everything which nature has caused
individuals to acquire or lose by the influence of the circum-
stances to which their race may be for a long time exposed,
and consequently by the influence of the prL-dominant use of
such an organ, or by thai of the constant lack of use of such
part, it preserves by heredity and passes on to the new indi-
viduals which descend from it, provided that the changes
thus acquired are common to both sexes, or to those which
have gi\en origin to these new individuals.
" These are (he two fundamental truths which can be mis-
understood only by those who have never obsent-d or
followed nature in its o]>erations," etc. The first law
embodies the principle of use and disuse, the second law that
of herc'dily.
In 1815 his theory received some extensions of minor
importance. The only points to which attention need Ix;
called are that he gives four laws instead of two, and that a
new feature occurs in the second law in the statement that
the ])roduction of a new organ is the result of a new need
{besoin} which continues to make itself felt.
Simplified Statement of Lamarck's Views. ^For practical
exposition the theon- may be simjililied into two sets of facts:
First, those (o be classed under varialion; and, second, those
imder heredity. Variations of organs, according to Lamarck,
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 377
arise in animals mainly through use and disuse, and new
organs have their origin in a physiological need. A new need
feltbylheanimalimprcssesitsclfon the organism, stimulating
growth and adaptations in a particular direction. This part
of Lamarck's theory has been subjected to much ridicule.
The sense in which he employs the word bcsoin has been
much misunderstood; when, however, we take into ac-
count that he uses it, not merely as expressing a wish or
desire on the part of the animal, but as the reflex action
arising from new conditions, his statement loses its alleged
gioiesqueness and seems to be founded on sound physiology.
Inheritance.^ — Lamarck's view of heretlity was uncritical;
according to his conception, inheritance was a simple, direct
transmission of those superficial changes that arise in organs
within the lifetime of an individual owing to use and disuse.
It is on this question of the direct inheritance of variations
acquired in the lifetime of an individual that his theor)- has
been the most assailed. The belief in the inheritance of
acquired characteristics has been so undermined by experi-
menlal evidence that at the present time we can not point
to a single unchallengc-d instance of such inheritance. But,
while Lamarck's thcor\- has shown weakness on that side,
his ideas regarding the production of variations have been
revived and e.\lended.
Variation. — The more commendable part of his theorj-
is the attempt to account for \arialion. Danvin assumed
variation, but Lamarck attempted to account for it, and in
this feature many discerning students maintain that the
theory of Lamarck is more philosophical in its foundation
than that of Darwin.
In any thcon,- of evolution we must deal with the variation
of orftanisms and heredil)', and thus we obsene that the two
factors discussed by Lamarck arc basal. .Although it must
be admitted that even to-day we know little about either
;dbyGOOglC
378 BIOLOGY AND ITS MAKERS
variation or heredity, they remain basal factors m any theory
of evolution.
Time and Favorable Conditions. — Lamarck supposed a
very long time was necessary to bring about the changes which
have taken place in animals. The central thought of time
and favorable conditions occurs again and again in his
writings. The following quotation is interesting as coming
from the first announcement of his views in i8co:
" It appears, as I ha\'e already said, that lime and javorahle
conditions are the two principal means which nature has
employed in giving existence to all her productions. We
know that for her lime has no limit, and that consequently
she has it always at her disposal.
"As to the circumstances of which she has had need and
of which she makes use ever)' day in order to cause her pro-
ductions to vary, we can say that in a manner they are
inexhaustible.
"The essential ones arising from the influence and from
all the environing media, from the diversity of local causes,
of habits, of movements, of action, finally of means of living,
of prescning their lives, of defending themselves, of mul-
tiplying themselves, etc. Moreover, as the result of these
different inlluences, the faculties, developed and strengthened
by use, become diversified by the new habits maintained for
long ages, and by slow degrees the structure, the consistence —
in a word, the nature, the condition of the ]>ans and of the
organs conscTjuenlly participating in all these inlluences,
became presened and were propagated by heredit)- (g^n^ra-
tion)." (Packard's translation.)
Salient Points. — The salient points in Lamarck's theory
may be compacted into a single sentence: It is a theory of
the evolution of animal life, dei>ending u[)on variations
brought alx)ut mainly through use and disuse of parts,
and also by resjranscs to external stimuli, and the direct
;dbyGOOglC
THEORIES OF LAMARCK A\D DARWIN 379
inheritance of the same. His iheorj' is comprehensive,
so much so that he includes mankind in his general con-
clusions.
Lamarck supposed that an animal having become
adapted to its surroundings would remain relatively stable
as to its structure. To the objection raised by Cuvier that
animals from Egj]>t had not changed since thn days when
they were preserved as mummies, he replied that the climate
of Egypt had remained constant for centuries, and therefore
no change in its fauna was to be expected.
Species. — Since the question of the fixity of species is the
central one in theories of evolution, it will be worth while to
quote Lamarck's definition of species: "All those who have
had much to do with the study of natural historv' know that
naturalists at the present day are extremely embarrassed in
defining what they mean by the word species. . . . We call
species ever)' collection of individuals which arc alike or
almost so, and we remark that the regeneration of these
individuals conserves the species and propagates it in con-
tinuing successively to reproduce similar individuals." He
then goes on with a long discussion to show that large collec-
tions of animals exhibit a great variation in species, and that
they have no absolute stability, but "enjoy only a relative
stability."
Herbert Spencer adopted and elaborated the theor>- of
Lamarck. He freed it from some of its chief crudities, such
as the idea of an innate tendency toward perfection. In
many controversies Mr, Spencer defended the idea of the
transmission of acquired characters. The ideas of Lamarck
ha\e, therefore, been transmitted to us largely in the Spence-
rian mold and in the characteristic language of that great
philosopher. There has been but little tendency to go to
Lamarck's original wTitings. Packard, whose biography of
Lamarck appeared in 1901, has made a thorough analysis
;dbyGOOglC
380 BIOLOGY AND ITS MAKKRS
of his, writings and had incidentally corrected several erro-
neous conception.
Heo-Lamarckism.— The ideas of Lamarck regarding the
beginning of variations have been re\ived and accorded much
respect under the designation of Xeo-Lamarckism. The
revival of Lamarckism is especially owing to the paiaeon-
tological investigations of Cope and Hyatt. The work of
E. D. Cope in particular led him to attach importance to the
effect of mechanical and other external causes in producing
variation, and he jwints out many instances of use-inher-
itance. Neo- Lamarckism has a considerable following; it
is a revival of the fundamental ideas of Lamarck.
Darwin's Theory
While Lamarck's theory rests upon two sets of facts,
Dar\vin's is founded on three: viz., the facts of variation,
of inheritance, and of natural selection. The central feature
of his theory is the idea of natural selection. No one else
save Wallace had seized uj>on this feature when Darwin
made it the center of his system. On account of the part
taken by Wallace simultaneously with Danvin in announcing
natural selection as the chief factor of evolution, il is appro-
priate to designate this contribution as the Danvin -Wallace
principle of natural selection. The interesting connection
between the original conclusions of Darwin and Wallace is
set forth in Chapter XIX.
Variation. — It will be noticed that two of the causes
assigned b>' Danvin are the same as those designalcti by La-
marck, but (heir treatment is quite different. Danvin (Fig.
1 13) assumed variation among animals and ]>lants without at-
tempting to account for il, while Lamarck underloolc to slate
the particular intluencfs which produce variaiion, and al-
though we must admit thai Lamarck was nol entirely suc-
;dbyGOOglC
382 BIOLOGY AND ITS MAKERS
ccssful in this attempt, the fact that he undertook the task
places his contribution at the outset on a very high plane.
The existence of variation as established by obse^^■ation
is unquestioned. No two living organisms are exactly alike
at the time of their birth, and even if they are brought up
together under identical surroundings they \ar}'. The varia-
tion of plants and animals under domestication is so con-
spicuous and well known that this kind of variation was the
first to attract attention. It was asserted that these varia-
tions were perpetuated because the forms had been protected
by man, and it was doubtc'd that animals varied to any con-
siderable extent in a state of nature. Extended collections
and obser\ations in field and forest have, however, set this
question at rest.
If crows or robins or other birds arc collected on an exten-
sive scale, the variability of the same species will be evident.
Many examples show that the so-called species differ greatly
in widely separated geographical areas, but collections from
the intermediate tcrritorj' demonstrate that the variations
are connected by a series of fine gradations. If, for illustra-
tion, one should pass across the United Stales from the
Atlantic to the Pacific coast, collecting one species of bird,
the entire collection would exhibit wide variations, but the
extremes would be connected by intermediate forms.
The amount of variation in a state of nature is much
greater than was at first supposed, because extensile collec-
tions were lacking, but the existence of wide \ariation is now
established on the basis of obser\ation. This fact of varia-
tion among animals and plants in the state of nature is
unchallenged, and affords a good point to start from in con-
sidering Darwinism.
Inheritance. — The idea that these \arialions are inher-
ited is the second point. But what particular variations will
be preser\ed and fostered by inheritance, and on what
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 3^3
principle they will be selected, is another question — and a.
notable one. Danvin's reply was ihat those variations which
are of advantage to the individual will be the particular ones
selected by nature for inheritance. While Darwin implies
the inheritance of acquired characteristics, his theory of
heredity was widely different from thai of Lamarck. Dar-
win's theory of heredity, designated the provisional theory of
pangenesis, has been already considered (see Chapter XIV),
Natural Selection. — Since natural selection is the main
feature of Darwin's doctrine, we must devote more time to
it. Darwin frequently complained that very few of his
critics took the trouble \o find out what he meant by the term
natural selection. A few illustrations will make his meaning
clear. Let us first think of artificial selection as it is applied
by breeders of cattle, fanciers of pigeons and of other fowls,
etc. It is well known that by selecting particular variations
in animals and plants, even when the variations are slight,
the breeder or the horticulturatist will be able in a short
time to produce new races of organic forms. This artificial
selection on the part of man has given rise to the various
breeds of dogs, the 150 different kinds of pigeons, etc., all
of which breed true. The critical question is. Have these all
an individual ancestral form in nature? Obser^^ation shows
that many different kinds — as pigeons — may be traced back
to a single ancestral form, and thus the doctrine of the fixity
of species is overthrown.
Xow, since it is demonstrated by obsenation that varia-
tions occur, if there be a selecti\e principle at work in
nature, effects similar to those caused by artificial selec-
tion will be produced. The selection by nature of the forms
fittest to sunive is what Darwin meant by natural selection.
We can never understand the application, however, unless
we take into account the fact that while animals tend to
multiply in geometrical progression, as a matter of fact the
;dbyGOOglC
3^4 BIOLOGY AND ITS MAKERS
number of any one kind remains practically constant.
Although the face of nature seems undisturbed, lluTc is
nevertheless a struggle for existence among all animals.
This is easily illustrated when we take into account the
breeding of fishes. The trout, for illustration, lays from 60,000
to joo,ooo eggs. If the majority of these arrived at maturity
and gave rise to progeny, the next generation would represent
a prodigious number, and the numbers in the succeeding
generations would increase so rapidly that soon there would
not be room in the fresh waters of the earth lo contain Ihcir
descendants. What becomes of the immense number of
fishes that die? They fall a prey to others, or they are not
able to get food in competition with other more hardy rela-
tives, so that it is nol a matter of chance that determines
which ones shall sunive; those which are the strongest, the
better fitted to their surroundings, arc the ones which will
be perpetuated.
The recognition of this struggle for existence in nature,
and the consequent suni\al of the fittest, shows us more
clearly what is meant by natural selection. Instead of man
making the selection of those particular forms that are to
survive, it is accomplished in the course of nature. This is
natural selection.
Various Aspects of Natural Selection.— Further illustra-
tions are needed to gi\e some idea of the \arious phase's of
natural selection. Speed in such animals as antelopes may
be the particular thing which leads to their protection. It
stands to reason that those with the greatest sjx'cd would
escape more readily from their enemies, and would be the
particular ones lo survi\'c, while the weaker and slower ones
would fall victims to their prey. In all kinds of strain due to
scarcity of food, inclemency of weather, and other untoward
circumstances, the forms which are the strongest, jihysio-
logically speaking, will have the best chance to weather the
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 3^5
strain and to survive. As another illustration, Darwin
)X)inled out that natural selection had produced a long-legged
race of prairie wolves, while the timber wolves, which have
less occasion for running, arc short-legged.
\Vc can also see the operation of natural selection in the
production of the sharp eyes of birds of prey. Let us con-
sider the way in which the eyes of the hawk ha\'e been [x;r-
fected b}' evolution. Natural selection compels the eye to
come up to a certain standard. Those hawks that are bom
with weak or defective vision cannot cope with the conditions
under which Ihey get their food. The sharp-eyed forms
would be the first io discern their prey, and the most sure in
seizing u|X)n it. Therefore, those with defective vision or
with vision that falls below the standard will be at a very
great disadvantage. The sharp-eyed forms will be presenx-d
b\' a selective process. Nature selects, we may say, the
keener-eyed birds of ])rey for survival, and it is easy to see
that this- process of natural selection would establish and
maintain a standanl of vision.
But natural selection lends merely to aflapt animals to
their surroundings, and does not always oixrrale in the direc-
tion of increasing the efTiciency of the organ. \Vc take an-
other illustration to show how Danvin ex])lains the origin of
races of short-winged beetles on certain oceanic islands.
Madeira and other islands, as Kerguelen island of the Indian
(^can, arc among the most windy places in the world. The
strong-winged beetles, being accusiometl to dis[X)rt them-
seh'cs in the air, would be carried out to sea by the sudden
and \iolent gales which sweep over those islands, while ihe
weaker-winged forms would be left to perpetuate their kind.
'I"hus, generation after generation, the strong-winged beetles
would be eliminated by a process of natural selection, and
there would be left a race of shorl-winged beetles deri\'ed
from long-winged ancestors. In this case the organs are
;dbyGOOglC
386 BIOLOGV -VXD ITS MAKERS
reduced in their development, rather than increased; but
manifestly the short -winged race of beetles is better adapted
to live under the particular conditions that surround their
life in these islands,
WTiilc this is not a case of increase in the particular organ,
it illustrates a progressive series of steps whereby the organ-
ism becomes belter adapted to its surroundings. A similar
instance is found In the suppression of certain sets of organs
in internal parasites. For illustration, Ihe tapeworm loses
particular organs of digestion for which it does not have
continued use; but the reproductive organs, upon which the
continuance of its life depends, are greatly increased. Such
cases as the formation of short-winged beetles show us that
the action of natural selection Is not alwajs to prcsene what
we should call the best, but simply to preserve the fittest.
Development, therefore, under the guidance of natural selec-
tion is not always progressive. Selection by nature does
not mean the formation and presenatlon of the ideally per-
fect, but merely the survival of those best fitted to their
environment.
Color. — The various ways in which natural selection acts
are exceedingly diversified. The colors of animals may be
a factor in their prcscr\-ation, as the stripes on the zebra
tending to make it inconspicuous in its surroundings. The
stripes upon the sides of tigers simulate the shadows cast by
the Jungle grass in which the animals li\e, and ser\e to con-
ceal them from their prey as well as from enemies. Those
animals that assume a white color in winter become thereby
less conspicuous, and they are protected by their coloration.
As further illustrating color as a factor in the prcsen'a-
tion of animals, we may cite a slory originally told by
Professor E. S. Morse, When he was collecting shells on the
white sand of the Japanese coast, he noticed numerous white
tiger- beetles, which could scarcely be seen against the white
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 387
background. They could be delected chiefly by their
shadows when the sun was shining. As he walked along
the coast he came to a wide band of la\a which had flowed
from a crater across the intervening counlry and plunged
into the sea, leaving a broad dark b.-ind some miles in breadth
across the while sandy beach. As he passed from the white
sand to the dark lava, his attention was attracted lo a tiger-
beetle almost identical with Ihc while one except as to color.
Instead of being white, it was black. He found this broad,
black band of lava inhabited by the black tiger beetle, and
found ven- few, if any, of the white kind. This is a striking
illustration of what has occurred in nature. These two
beclles arc of the same species, and in examining the condi-
tions under which they grow, it is discovered that out of the
e^s laid by the original white forms, ihere now and then
appears one of a dusky or black color. Consider how con-
spicuous this dark object would be against the white back-
ground of sand. It would be an easy mark for the birds
of prey that lly about, and therefore on the white surface
the black beetles would be destroyed, while the while ones
would be left. But on the black background of lava the
conditions are reversed. There the white forms would be the
conspicuous ones; as ihey wandered ufxjn the black surface,
they would be pickc-d up by birds of prey and the black ones
would be left. Thus we see another instance of ihc operation
of natural selection.
Mimicry. — \Vc have, likewise, in nature a great numlier
of cases that are designated mimicr}\ For illustration, cer-
tain caterpillars assume a stiff ]x>sition, resembling a twig
from a branch. We have also leaf-like butterflies. The Kal-
lima of India is a conspicuous illustrallon of a butterfly
having the upper surface of its wings bright-colored, and the
lower surface dull. When it settles upon a twig the wings
are closed and the under-sides have a mark across them
;dbyGOOglC
3ao BIOLOGY AND ITS MAKERS
resembling the mid-rib of a leaf, so that the whole butlerfiy
in the resting position becomes inconspicuous, being pro-
tected by mimicry.
One can readily sec how nalural selection would be evoked
in order to explain this condition of alTairs. Those forms
that varied in the direction of looking like a leaf would be
the most perfectly protecled, and this feature being fostered
by natural selection, would, in the course of time, produce a
race of butterflies the resemblance of whose folded wings to
a leaf would serve as a protection from enemies.
It may not be out of place to remind ihe reader that the
illustrations cited are introduced merely to elucidate Dar-
win's theory and (he writer is not committed to accepting
them as cx]>lanations of the phenomena involved. He is
not unmindful of the force of the criticisms against the ade-
quacy of natural selection to explain the evolution of aU
kinds of organic structures.
Many other instances of the action of color might be
added, such as the wearing of warning colors, those colors
which belong to buttcrllics, grubs, ami other animals that
have a noxious laste. These warning colors have taught
birds to leave alone the forms possessing those colors. Some-
times forms which do nol |>ossess a disagreeable taste
secure protection by mimicking the colors of the noxious
varieties.
Sexual Selection. — Tiicre is an entirely different set of
cases which at first sight would seem difficult to explain on
the principle of selection. How, for instance, could we
explain the feathers in the tails of the birds of paradise, or
that peculiar arrangement of feathers in the tail of the lyre-
bird, or the gorgeous display of tail-feathers of the male
peacock? Here Mr. Darwin seized upon a selective prin-
ciple arising from the influence of mating. The male birds
in becoming suitors for a particular female have Ijcen accus-
ed byGoOglc
THEORIES OF LAMARCK AND DARWIN i^g
tomcd to display their tail-feathers; the one with the most
attractive display excites the pairing instinct in the highest
degree, and becomes the selected suitor. In this way,
through the operation of a form of seleclion which Darwin
designates sexual selection, possibly such curious adaptations
as the peacock's tail may be accounted for.
It should be pointed out that this part of the theory is
almost wholly discredited by biologists. Experimental evi-
dence is against it. Nevertheless in a descriptive aecount
of Darwin's theory it may be allowed to stand without
critical comment.
Inadequacy of Natural Selection,— In nature, under the
struggle for e.\istencc, the fittest will be preserved ; and natural
seleclion will ojierate toward the elaboration or the suppres-
sion of certain organs or certain characteristics when the elab-
oration or the sup]Jression is of advantage to the animal form.
Much has been said of late as to the inadequacy of natural
selection. Herbert Spencer and Huxley, both accepting
natural selection as one of the factors, doubted its complete
adequacy.
One point is often overlooked, and should be brought out
with clearness; viz., Ihat Darwin himself was the first to
poinl out clearly ihe inadequacy of natural selection as a
uni\L-r^al law for the production of the great variety of
animals and plants. In Ihe second edition of the Origin of
Sl>irks he says: "But, as my conclusions have lately been
much misrc]>resentcd, and it has been stated that I attribute
the modification of species exclusively to natural selection,
I may be permitted to remark that in the first edition of this
work and subsequently I placed in a most conspicuous
position, — namely, at the close of the introduction — the follow-
ing words: 'I am convinced that natural selection has been
the main, but not the exclusive means of modification.' This
has been of no a\'ail. Great is the power of steady mis-
;dbyGOOglC
390 BIOLOGY AND ITS MAKERS
representation. But the history of science shows that for-
tunately this power does not long endure."
The reaction against the all-sufficiency of natural selec-
tion, therefore, is something which was anticipated by Dar-
win, and the quotation made above will be a novelty to many
of our readers who supposed that they understood Darwin's
position.
Confusion between Lamarck's and Darwin's Theories. —
Besides the failure to understand what Darwin has written,
there is great confusion, both in pictures and in wTitings, in
reference to the theories of Darwin and Lamarck. Poulton
illustrated a state of confusion in one of his lectures on the
theory of organic e\'olution, and the following instances are
quoted from memory.
We are most of us familiar with such piciiu-es as the
following: .^ man slanding and waving his arms; in the next
picture these arms and hands become enlarged, and in the
succcssi\'e pictures they undergo transformations into wings,
and the transference is made into a flying animal.
Such piclures are designated "The origin of flight after
Danvin." The intercsling circumstance is this, that the
illustration docs not apply to Darwin's idea of natural selec-
tion at all, bul is jjure Lamarckism, Lamarck contended
for the production of new organs through the influence of
use and disuse, and this particular illustration refers to that,
and not to natural seleclion at all.
Among the examples of ridicule to which Darwin's ideas
have been exposed, we cite one verse from the song of Lord
Ncavcs. His lordship \\TOte a song with a large number of
verses hitting off in jocular vein many of the claims and
foibles of his time. In attempting to make fun of Darwin's
idea he misses completely the idea of natural selection, but
hits U]»on the princii>le enunciated by Lamarck, instead.
He .savs:
;dbyGOOglC
THEORIES OF LAMARCK AND DARWIN 39^
"A deer with a neck which was longer by half
Than the rest of his family's — try not to laugh —
By stretching and stretching became a giraffC;
Which nobody can deny."
The clever young woman, ^tiss Kendall, however, in her
Song 0} the Ichthyosaurus, showed clearness in grasping
Darwin's idea when she wrote:
"Ere man was develoj>ed, our brother,
Wc swam, we ducked, and we dived,
And we dined, as a rule, on each other.
What matter? The toughest survived."
This hils the idea of natural selection. The other two illus-
trations miss it, bul strike the principle which was enunciated
by Lamarck. This confusion between Lamarckism and Dar-
winism is \ery wide-spread.
Darwin's book on the Origin of Species, published in
1859, was epoch-making. If a group of scholars were asked
to designate the greatest book of the nineteenth century —
that is, the book which created the greatest intellectual stir — -
il is likely that a large proportion of them would reply that
it is Darwin's Origin oj Species. Its influence was so great
in the different domains of thought that we may observe a
natural cleavage between the thought in reference to nature '
between 1859 and all preceding time. His other less widely
known books on Animals and Plants Under Domestication^
ihc Descent 0} A/aw, etc.etc, are also important contributions
to the discussion of his theory. A brief account of Darwin,
the man, will be found in Chapter XIX.
;dbyGOOglC
CHAPTKR XVIII
THKORIES OF EVOLUTION* CON'TINUKDi
WEISMAXX. DR VRIES
Weismann's views have passed ihrough various stages of
remodeling since his first ]»ublic chamiMonsliip of tlie Tlieorv'
of Dcscenl on assuming, in 1867, the ]x>silion of professor of
zo6log\' in the University of Freiburg. Some time after that
date he originated his now famous theory of liercdity, which
has iR'tn retouched, from time lo lime, as the result of
aggressive criticism from others, ;ind the expansion of his
owTi mental horizon. .As he s;iid in igoj, regarding his
lectures on evolution wliith ha\c bcx.-n de!i\*ered almost reg-
ularly every year since 1880, they "were gradually modified
in accordance with the slate of my knowledge at the time,
so that they have been, J may say, a mirror of my own intel-
lectual evolution."
Passing over his book, I'he Germ Plasm, published in
English in iS<j?, we may fairly take his last book. The
Evolution 'I'lirory, 1904, as the best exj^sition of his con-
clusions. The theoretical views of Weismann have been
the tield of so much strenuous contro\ersy liiat it will be well
jx-rhaps to lake note of the spirit in which they have been
presented. In the [ircface of his book just mentioned, he
says: "I maki' this atlemjit to sum uji and present as a har-
monious whole the thctiries wliieh for forly years I have been
gradually liuilding up on the basis of the legacy of the great
workers of the past, anil on the resuhs of my own investijja-
;dbyGOOglC
THEORIES OF WEISMANN AND DE VRIES 393
tioiis and those of my fellow-workers, not because I regard
the picture as incomplete or incapable of improvement, bul
because I believe its essential features to be correct, and
because an eye-trouble which has hindered my work for
many years makes it uncertain whether I shall have much
more time and strength granted to me for its further elabora-
tion,"
The germ-plasm theor\' is primarily a iheor}' of heredity,
and only when connected with other considerations does it
become the full-fledged theory of evolution known as Weis-
mannism. The theon.- as a whole involves so many intricate
details that il is dilVicult to make a clear statement of it for
general readers. If in considering the theories of Lamarck
and Darwin it was found advantageous to confine attention
lo salient jxjinis and to omit details, it is all the more essential
to do so in the discussion of Wcismann's theor)\
In his prefator\- note to tlie English edition of The
Evolution Theory l"homson, the translator, summarizes W'eis-
mann's especial conlribiilions as: "(i ) the illumination of the
evolution i>rocess with a wealth of fresh illustrations; (2)
the vindication of the 'gL-rm-plasm' concept as a valuable
working hypothesis; (3I the final abandonment of any
assumption of transmissible acrjuired characters; (4) a
further analysis of the nature and origin of variations; and
(51. alwve all, an extension of the selection principle of
Darwin and Wallace, which fimls its logical outcome in the
suggestive theory of germinal selection."
Continuity of the Germ-Plasm,— A\'eismann's theory is
designated that of continuity of the germ-plasm, and in con-
sidering it we must tlrst give attention to his conception of
(he germ-plasm. As is well knowTi, animals and plants
spring from germinal elements of microscopic size; these are,
in i>lan(s, the sixjres. the seeds, and their fertilizing agents;
and, in animals, the eggs and the sperms. Now, since all
;dbyGOOglC
394 BIOLOGY ANY ITS MAKERS
animals, even the highest de\-cloped, begin in a fertilized egg,
that structure, minute as it is, must contain all hereditary
qualities, since it is the only material substance that passes
from one generation to another. This hereditary substance
is the germ-plasm. It is the living, vital substance of organ-
isms that takes part in the development of new generations.
Naturalists are agreed on this point, that the more com-
plex animals and plants have been derived from the simpler
ones; and, this being accepted, ihc attention should be fixed
on the nature of the connection between generations during
their long line of descent. In the reproduction of single-
celled organisms, the substance of the entire body is divided
during the transmission of life, and the problem both of
heredity and origin is relatively simple. It is clear that in
these single-celled creatures there is unbroken continuity of
body-substance from generation to generation. But in the
higher animals only a minute portion of the organism is
passed along.
Weismann points out that the many-celled body was
gradually produced by evolution; and that in the trans-
mission of life by the higher animals the conlinuity is not
between body-cells and their like, but only between ger-
minal elemcnls around which in due course new body-cells
are developed. Thus he regards ihe body cells as constitut-
ing a sort of vehicle within which the germ-cells are carried.
The germinal elements represent the primordial substance
around which the body has been developed, and since in all
the long process of evolution the germinal elements have been
the only form of connection between different generations,
they have an unbroken conlinuity.
This conception of the continuity of the germ-plasm is
the foundation of Weismann's doctrine. As indicated before,
the general way in which he accounts for heredity is that the
offspring is like the parent because it is composed of some of
;dbyGOOglC
THEORIES OF WEISMANN AND DE VRIES 395
the same stuff. The rise of the idea of germinal continuity
has been indicated in Chapter XIV, where it was pointed out
that Wcismann was not the originator of the idea, but he is nev-
ertheless the one who has de\-eloped it the most extensively.
Complexity of the Germ-Plasm.— The germ-plasm has
been molded for so many centuries by external circum-
stances that it has acquired an organization of great com-
plexity. This appears from the following considerations:
Protoplasm is impressionable; in fact, its most characteristic
feature is that it responds to stimulation and modifies itself
accordingly. These subtle changes occurring within the
protoplasm affect its organization, and in the long run it is
the summation of experiences that determines what the pro-
toplasm shall be and how it will behave in development.
Two masses of protoplasm differ in capabilities and poten-
tialities according to the experiences through which they have
passed, and no two will be absolutely identical. All the time
the body was being evolved the protoplasm of the germinal
elements was being, molded and changed, and these ele-
ments therefore possess an inherited orgnization of great
complexity.
When the body is built anew from the germinal ele-
ments, the derived qualities come into play, and the whole
process is a succession of responses to stimulation. This is
in a sense, on the part of the protoplasm, a repeating of its
historical experience. In building the oi^anism it does not
go o\'er the ground for the first time, but repeats the activities
which it took centuries to acquire.
The evident complexity of the germ-plasm made it
necessary- for Weismann, in attempting to explain inheritance
in detail, to assume the existence of distinct vital units within
the protoplasm of the germinal elements. He has invented
names for these particular units as biophors, the elementary
vilal units, and their combination into determinants, the
;dbyGOOglC
39^ BIOLOGY AND ITS MAKERS
ktter being united into ids, idaats, etc. The way in which
he assumes the interactions of these units gives to his theory
a highly speculative character. The conception of the
complex organization of the genn-plasm which Weismann
reached on theoretical grounds is now being establi^ed on
the basis of observation (see Chapter XIV, p. 313)-
The Origin of Variatioiis. — ^The way in which Weismann
accounts for the origin of variation among higher animals
is both ingenious and interesting. In all higher organisms
the sexes are separate, and the reproduction of their kind is
a sexual process. The germinal elements involved are seeds
aod pollen, eggs and sperms. In animals the egg bears all
the hereditary qualities from the maternal side, and the
sperm those from the paternal side. The intimate mixture
of these in fertilization gives great possibilities of variations
arismg from the different combinations and permutations of
the vital imits within the germ-plasm.
This union of two germ-plasms Weismann calls amphi-
mixis, and for a long time he maint^el that the purpose
of sexual reproduction in nature is to give origin to varia-
tions. Later he extended his idea to include a selection,
mainly on the basis of nutrition, among the ntal elements
composing the germ-plasm. This is germinal selection,
which aids in the prwiuclion of variations.
In The Evolution Theory, \'olume II, page 196, he says:
"Now that I understand these jjrocesses more clearl}', ny
opinion is ihat the roots of all heritable variation lie in the
germ-plasm; and, furthermore, that the determinants arc
continually o?cillating hither and thither in response to
very minute nutritive chanf;es and are readily compelled
to variation in a definite direction, which may ultimately lead
to considerable variations in the structure of the sjiecies, if
they are fa\-ored by personal selection, or at least if they are
not suppressed by it as prejudicial."
;dbyGOOglC
HEORIES OF WEISMANN AND DE VRIES 397
But while sexual reproduclion may be evoked to explain
the origin of variation in higher animals, Wcismann thought
it was not applicable to the lower ones, and he found himself
driven to assume that variation in single-celled organisms is
owing to the direct influence of environment ujxin them,
and thus he had an awkward assumption of variations ari^g
in a different maimer in the higher and in the simplest organ-
isms. If I correctly understand his present position, the
conception of variation as due to the direct influence of
environment is being surrendered in favor of the action of
germinal selection among the simplest organisms.
Extension of the Principle of Hatural Selection. — These
variations, once started, will be fostered by natural selection
provided they are of ad\antagc to the organism in its struggle
for existence. It should be pointed out that Weismann is a
consistent Dar\vinian; he not only adopts the principle of
natural selection, but he extends the field of its operation
from externals to the internal parts of the germinal elements.
" Roux and others have elaborated ihc idea of a struggle
of the parts within the organism, and of a corresponding
inlra-seleclion ; . . . but Weismann, after his manner, has
carried the selection-idea a step farther, and has pictured
the struggle among the determining elements of the germ-
cell's organization. It is at least concei\able that the stronger
'determinants,' i.e., the particles embodying the rudiments
of certain qualities, will make more of the food-supply than
those which arc weaker, and that a selective process will
ensue" (Thomson), This is the conception of germinal
selection.
He has also extended the application of the general
doctrine of natural selection by supplying a great number
of new illustrations.
The whole theory of Weismann is so well constructed
that it is \'cr)' alluring. Each successiv'e position is worked
;dbyGOOglC
390 BIOLOGY AND ITS MAKERS
out with such detail and apt illustration that if one follows
him step by step without dissent on some fundaracnlal prin-
ciple, his conclusion seems justified. As a sjstcm it has
been elaborated until it makes a coherent appeal to the
intellect.
Inheritance of Acquired Characters. — Another funda-
mental point in Wcismann's iheorv is the denial that acquired
characters are transmitted from parent to offspring. Prob-
ably the best single discussion of this subject is contMned
in his book on The Evolution Theory, 1904, to which readers
are referred.
A few illustrations will be in [ilace. Acquired characters
are any acquisitions made by the bod)--cells during the
lifetime of an individual. They may be obvious, as skill
in piano-playing, bicycle-riding, etc.; or they maj' be very
recondite, as turns of the intellect, acquired beliefs, etc.
Acquired bodily characters may be forcibly impressed upon
the organism, as the facial mutilations practiced by certain
savage tribes, the docking of the tails of horses, of dogs, etc.
The question is, Are any acquired characters, physical or
mental, transmitted by inheritance?
Manifestly, it will be difhcult to determine on a scientific
basis whether or not such qualities arc inheritable. One
would naturally think first of ap]>lying the test of experiment
to supposed cases of such inheritances, and this is the best
ground to proceed on.
It has been maintained on the basis of the classical
exijerimenis of Brown-S^quard on guinea-pigs that induced
epilepsy is transmitted to offs|)ring; and, also, on the basis
of general observations, that certain bodily mutilations are
inherited. Weismann's analysis of the whole situation is
very incisive. He experimented by cutting off the tails of
both parents of breeding mice. The experiments were
carried through twenty-two generations, both parents being
;dbyGOOglC
THEORIES OF WEISMANN AND DE VRIES 399
deprived of their tails, without jielding any evidence that
the mutilations were inheritable.
To take one other case that is less superficial, it is gener-
ally believed that the thirst for alcoholic liquors has been
transmitted to the children of drunkards, and while Weismann
admits the possibility of this, he maintains that it is owing
to the germinal elements being exposed to the influence of
the alcohol circulating in the blood of the parent or parents;
and if this be the case it would not be the inheritance of an
acquired character, but the response of the organism to a
drug producing directly a variation in the germ-plasm.
Notwithstanding the well-defined opposition of Weismann,
the inheritance of acquired characters is still a mooted ques-
tion. Herbert Spencer argued in favor of it, and during his
lifetime had many a pointed controversy with Weismann.
Eimer stands unalterably against Weismann's position, and
the Neo-Lamarckians stand for the direct inheritance of use-
ful variations in bodily structure. The question is still
undetermined and is open to experimental observation. In
its present state there are competent observers maintaining
both sides, but it must be confessed that there is not a single
case in which the supposed inheritance of an acquired char-
acter has stood the test of critical examination.
The basis of Weismann's argument is not difficult to
understand. Acquired characters affect the body-cells, and
according to his view the latter are simply a vehicle for the
germinal elements, which arc the only things concerned in
the transmission of hereditary qualities. Inheritance, there-
fore, must come through alterations in the germ-plasm, and
not directly through changes in the body-cells,
Weismann, the Man. — The man who for more than forty
years has been elaborating this theory (Fig. 1 14) is still living
and actively at work in the University of Freiburg. August
Weismann was bom at Frankfort-on-the-Main in 1834. He
;dbyGOOglC
400 BIOLOGY AND ITS MAKERS
was graduated at Goltingen in 1856, and for a short time
thereafter engaged in the practice of medicine. This Hne of
activity did not, however, satisfy his nature, and he turned
to the pursuit of microscopic investigations in embryology
and morpholofiy, \mnn cncouraKfd in (his work by Lcuckart,
whose name wi' liavc already mcl in this history. In 1863
hu setlU'cl in Freiburj; a.s privat-flotcnt. anil has remained
coniurted with the univursiiy ever .since. Krom iSd; onward
;dbyGOOglC
THEORIES OF WEISMANN AND DE VRIES 401
he has occupied the chair of zoology in ihat institution. He
has made his department famous, especially by his lectures
on the theory of descent.
He is a forceful and interesting lecturer. One of his
hearers in 1896 wTote: " His lecture-room is always full, and
his popularity among his students fully equals his fame
among scientists."
It is quite generally know-n that Weismann since he
reached the age of thirty has been afflicted with an eye-
trouble, but the inference sometimes made by those unac-
quainted with his work as an in\cstigator, that he has been
obliged to forego practical work in the field in which he has
speculated, is wTong. At intervals his eyes ha\-e strengthened
so that he has been able to apply himself to microscopic
observations, and he has a distinguished record as an obserier.
In embryology his studies on the development of the diptera,
and of the eggs of daphnid Crustacea, are well known, as are
also his obscTvations on variations in butterflies and other
arthropods.
He is an accomplished musician, and during the period
of his enforced inactivity in .scientific work he found much
solace in ]}laying " a goo<l deal of music." " His continuous
eye irouble must have been a terrible obstacle, but may have
been the prime cause of turning him to the theories with
which his name is connected."
In a short autobiography published in The Lamp in 1903,
allhmigli written several years earlier, he gi\cs a glimpse of
his family life. "During the ten years (1864-1874) of my
enforced inactivity and rest occurred my marriage with
Fraulein ilarie Gruber, who became the mother of my
children and was my true companion for twenty years, until
her death. Of her now I think only with love and gratitude.
She was ihc one who, more than any one else, helped me
through the gloom of this period. She read much to me
;dbyGOOglC
402 BIOLOGY AND ITS MAKERS
at this time, for she read aloud excellently, and she not only
took an interest in my theoretical and experimental work,
but she also gave practical assistance in it."
In 1893 he published The Germ-Plasm, A TIteory 0}
Heredity, a treatise which elicited much discussion. From
that time on he has been actively engaged in replying to his
critics and in |}erfecting his system of thought.
The Mutation-Theory of De Vries.— Hugo de Vries
(Fig. 115), director of ihe Botanical Garden in Amsterdam,
has experimented widely with the growth of plants, especially
the evening primrose, and has shown that different species
appear to rise suddenly. The sudden variations that breed
true, and thus give rise to new forms, he calls mutations, and
this indicates Ihe source of the name applied to his theory.
In his Die Mutalionslheorie, jtublished in 1901, he argues
for the recognition of mutations as the universal source of
the origin of sjx'cies. Although he evokes natural selection
for the perpetuation and improvement of variations, and
Doints out that his theory is not antagonistic to that of natural
seleclion.it is nevertheless directly at variance with Darwin's
fundamental conception — that slight individual variations
"arc probably Ihe sole differences which are effective in the
production of new species" and thai "as natural selection
acts solely by accumulating slight, successive, favorable
variations, it can produce no great or sudden modifications."
The foundation of De Vrie.s's theory is that '"species have
not arisen through gradual .seli-ction. continued for hundreds
or thousands of years, but by jumps through .sudden, through
small transformations." (Whitman's translation.)
The work of De Vries is a most imj>orlant contribution
to the stmiy of the origin of .species, and is indicative of the
fact that many factors mu.sl be taken into consideration when
one attempts to analyze the process of organic evolution.
One great \'alue of his work is that it is based on cxj)criments,
;dbyGOOglC
THEORIES OF WEISMANN AND DE VRIES 403
and that it has given a great stimulus to experimental studies.
Exiwrimcnl was likewise a dominant feature in Darwin's
work, but that seems to ha\c been almost o\erlooked in
the discussions aroused by his conclusions; Dc Vries, by
building ujKin experimental evidence, has led naturalists to
realize that the method of evolution is not a subject for
argumenfative discussion, but for experimental investigation.
This is most commendable,
De Vries's theory tends also to widen the field of explo-
ration. Da\enport, Tower, and others have made it clear
that species may arise by slow accumulations of trivial varia-
tions, and that, while the formation of species by mutation
;dbyGOOglC
404 BIOLOGY AND ITS MAKERS
may be admitted, there is still abundant e\idencc of evolu-
tion without mutation.
Reconciliation of Different Theories. — All this is leading
to a clearer appreciation of the points involved in the dis-
cussion of the theories of c\'olution; the tendency is not for
the breach between the dilTcrcnt theories to be widened, but
for e\-olutionists to realize more fully the great complexity
of the process they are trying to explain, and to see that no
single factor can carry the burden of an explanation. Muta-
tion is not a substitute for natural selection, but a cooperating
factor; and neither mutation nor natural selection is a sub-
stitute for the doctrine of the continuity of the germ-plasm.
Thus we may look forward to a reconciliation between
apparently conflicting views, when naturalists by sifting
shall have determined the truth embodied in the various
theories. One conviction that is looming into prominence is
that this will be promoted by less argument and more ex-
perimental observation.
That the .solution of the underlying question in evolution
will still require a long time is evident; as \\'hitman said
in his address before the Congress of ,-\rts and Science in
St. Louis in i()o4: "The problem of problems in biology
to-da)', the jirobiem which promises to sweep through the
present century as it has the past one, with cumulative inter-
est and corresi>ondingly important results, is the one which
became the iife-work of Charles Darwin, and which can not
be better or more simjily expressed than in the title of his
CjMJch-making book, The Origin oj Species."
Summary. — The number of ]>oints involved in the four
theories considered above is likely to be rather confusing,
and we may now bring them into close juMa]>osilion. The
salient features of these theories are as follows:
;dbyGOOglC
THEORins OF WEISMANN AND DE VRIES 405
I. Lamarck's Theory of E\olution.
1. Variation is es[)laincd on ihi; principle of use and
disuse.
2. Heredity: The variations arc inhcrilcd directly and
impro^'ed in succeeding generations.
A long time and favorable conditions are required
for the production of new species.
II. Darwin's Theory of Natural Selection.
1. Variations assumed.
2. Heredity: Those slight variations which arc of use
to the organism will be pcr]>etuated by inher-
itance,
3. Natural selection is the distinguishing feature of
the theory. Through the struggle for existence
nature selects those best fitted to survive. The
."election of trivial variations that are of advantage
to the organism, and their gradual improvement,
leads to the production of new species.
III. Weismann's Theory of C'ontinuity of the Germ-plasm,
1. The germ-plasm has had unbroken continuity from
the beginning of life. Owing to its impression-
able nature, it has an inherited organization of
great complexity.
2. Heredity is accounted for on the principle that the
ofrs]>ring is composed of some of the same stuff
as its parents. The body-cells are not inherited,
i.e.,
3. There is no inheritance of acquired characters.
4. \'aria!ions arise from the union of the germinal
elements, ginng rise to varied combinations and
permutations of the qualities of the germ-plasm.
The purpose of amphimi\i.s is to give rise to vari-
ations. The direct influence of environment has
produced variations in unicellular organisms.
;dbyGOOglC
406 BIOLOGY AND ITS MAKERS
5. W'cismann adopts and extends the principle of
natural selection. Germinal selection is exhibited
in the germ- plasm.
IV. De Vrics's Theory of Mutations.
1. The formation of species is due not to gradual
changes, but to sudden mutations.
2. Natural selection presides over and improves varia-
tions arising from mutation.
Among the other theories of evolution that of Eimer is
the most notable. He maintains that variations in organisms
take place not fortuitously or accidentally, but follow a per-
fectly determinate direction. This definitely directed evolu-
tion is called orthogenesis. He insists that there is con-
tinuous inheritance of acquired characters, and he is radically
op(XJscd to the belief that natural selection plays an important
part in evolution. The title of his pamphlet published in
1898, On Onlwgenesis and the Impotence 0} Natural Selection
in Species-Formation, gives an indication of his [Xisition in
reference to natural selection. A consideration of Eimer's
argument would be beyond the j}ur]>ose of this book.
The cause for the f;<^nL'raI confusion in the popular mind
regardint; any distinction between organic evolution and
Darwinism is not far to seek. As has been shown, Lamarck
launched the doctrine of organic evolution, but his views did
not e\'en get a public hearing. Then, after a period of tem-
porary disappearance, the doctrine of evolution emerged
again in iS^y. And this time the discussion of the general
theory centered around Darwin's hyi>othesis of natural selec-
tion. It is quite natural, therefore, that people should think
that Darwinism and organic e\'olution are synonymous terms.
The distinction between the general theory and any particular
explanation of it has, I trust, been made sufficiently clear in
the preceding pages.
;dbyGOOglC
CHAPTER XIX
THE RISE OF EVOLUTIONARY THOUGHT
A CURRENT of evolutionary thought can be traced through
the literature dealing with organic nature from ancient times.
It began as a small rill among the Greek philosophers and
dwindles to a mere thread in the Middle Ages, sometimes
almost disappearing, but Is never completely broken off.
Xear the close of the eighteenth century it suddenly expands,
and becomes a broad and pre\ailing influence in the nine-
teenth century. Osborn, in his book, From the Greeks to
Dam-in, traces the continuity of evolutionary thought from
the time of the Greek philosophers to Darwin. The ancient
phase, although interesting, was vague and general, and
may be dismissed without much consideration. After the
Renaissance naturalists were occupied with other aspects of
nature-study. They were at first attempting to get a knowl-
edge of animals and plants as a whole, and later of their
structure, their developments, and their physiology, before
questions of their origin were brought under consideration.
Opinion before Lamarck. — The period just prior to
Lamarck is of particular interest. Since Lamarck was the
first to give a comprchcnsi\e and consistent theory of evolu-
tion, it will be interesting lo determine what was the state
of opinion just prior to ihe appearance of his writings.
Studies of nature were in such shape at that time that the
question of the origin of species arose, and thereafter it would
not rcceflc. This was owing mainly lo the fact that Ray and
Linnaus by defining a species had fixed the attention of
;dbyGOOglC
4O0 BIOLOGY AND ITS MAKERS
naturalists upon the distinguishing features of the particular
kinds of animals and plants. Are s|jecies realities in nature ?
The consideralion of this apparently simple question soon
led to di\'crgent \icws, and then to warm controversies that
extended over several decades of time.
The view first adopted without much thought and as a
matter of course was that species are fixed and constant; i.e.,
that the existing forms of animals and plants arc the descend-
ants of entirely similar parents that were originally created
in pairs. This idea of the fixity of sjiecies was elevated to the
position of a dogma in science as well as in theology. The
opposing view, that species are changeable, arose in the
minds of a few independent observers and thinkers, and, as
has already been jxiinled out, the discussion of this question
resulted ultimately in a complete change of view regarding
nature and man's relation to it. When the conception of
evolution came upon the scene, it was violently combated.
It came into conflict with the theory designated special
creation.
Views of Certain Fathers of the Church. — And now it is
essential that wc should be clear as to the sources of this
dogma of s[>ecial creation. It is perhaps natural to assume
that there was a conflict existing between natural science
and the views of the theologians from the earliest times;
that is, between the scientific method and the method of the
theologians, the latter being based on authority, and the
former upon observation and cx]>criment. Although there
is a conflict between these two methods, there nevertheless
was a long period in which many of the leading theological
thinkers were in harmony with the men of science with refer-
ence to their general conclusions regarding creation. Some
of the early Fathers of the Church exhibited a broader and
more scientific spirit than their successors.
St. Augustine (353-430), in the fifth century, was the
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 4^9
first of the great theologians to discuss specifically the ques-
tion of creation. His jKisition is an enlightened one. He
says: "It very often happens that there is some question as
to the earth or the sky, or the other elements of this world
. . . respecting which one who is not a Christian has knowl-
edge derived from most certain reasoning or obsen-ation"
{that is, a scientific man); "and it is very disgraceful and
mischievous and of all things to be carefully avoided, that a
Christian speaking of such matters as being according to the
Christian Scriptures, should be heard by an unbeliever talk-
ing such nonsense that the unbeliever, perceiving him to be
as wide from the mark as east from west, can hardly restrain
himself from laughing." (Quoted from Osbom.)
Augustine's view of the method of creation was that of
derivative creation or creation catisaliler. His was a natural-
istic interpretation of the Mosaic record, and a theory of
gradual creation. He held that in the beginning the earth
and the waters of the earth were endowed with power to
produce ])lants and animals, and that it was not necessary to
assume that all creation was formed at once. He cautions
his readers against looking to the Scriptures for scientific
truths. He said in reference to the creation that the days
spoken of in the first chapter of Genesis could not be solar
days of twenty -four hours each, but that they must stand
for longer periods of time.
This view of Si. .\ugustine is interesting as being less
narrow and dogmatic than the position assumed by many
theologians of the nineteenth century.
The ne.\t theologian to take up the question of creation
was St, Thomas .\<|uinas (1225-1274) in the thirteenth cen-
tury. He quotes St. .Augustin.'s view with approval, but
does not contribute anything of his own. One should net
hastily conclude, howe\'er, because these views were held by
leaders of theological thought, that they were universally
;dbyGOOglC
4'0 BIOLOGY AND ITS MAKERS
accepted, "The truth is that all classes of theologians
departed from the orighial philosophical and scientific stand-
ards of some of the Fathers of the Church, and that special
creation became the uni\ersal teaching from the middle of
the sixteenth to the middle of the nineteenih centuries."
The Doctrine of Special Creation. — About the seven-
teenth century a change came about which was largely o^ing
to the writings and influence of a Spanish theologian named
Suarez {i548-i6r7). Although Suarez is not the sole
founder of this conception, it is certain, as Huxley has shown,
thai he engaged himself with the questions raised by the Bib-
lical account of creation; and, furthermore, that he opposed
the views that had been expressed by Augustine. In his
tract upon the work of the six days {Tractatus de opcre sex
dierum) he takes exception to the views expressed by St.
Augustine; he insistc<l that in the Scriptural account of
creation a day of twenty-four hours was meant, and in all
other ca.'ics he insists upon a literal interpretation of the
Scriptures. Thus he introduced into theological thought the
doctrine which goes under the name of s]>ccial creation.
The interesting feature in all this is that from the time of
St. .\ugustine, in the fifth century, to the lime when the ideas
of Suarez began to prevail, in the seventeenth, there had been
a harmonious relation between some of the leading theolo-
gians and scientific men in their outlook upon creation.
The opinion of .\ugustine and other theologians was
largely owing to the influence of Aristotle, "We know,"
says Osborn, "that Greek philosophy tinctured early Chris-
tian theology; what is not so generally realized is that the
.\rislotelian notion of the development of life led to the true
inlcrprctalion of the ^fosaic account of the creation.
"There was in fact a long Greek periwl in the history
of the evolutionary idea extending among the Fathers of the
Church and later among some of the schoolmen, in their
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 4"
commentaries uix>n creation, which accord very closely with
the modem thcistic conception of e\olulion. If the ortho-
doxy of Augustine had remained the teaching of the Church,
the final establishment of evolution would have come far
earlier than it did, certainly during the eighteenth century
instead of the nineteenth century, and the bitter contro\'ersy
over this truth of nature would never have arisen."
The conception of special creation brought into especial
prominence upon the Continent by Suarez was taken up by
John Milton in his great epic Paradise Lost, in which he
gave a picture of creation that molded into specific form
the opinion of the English-speaking clerg>- and of the
masses who read his book. WTicn the doctrine of organic
evolution was announced, it came into conflict with this
particular idea; and, as Huxley has very pointedly remarked,
the new theory of organic e\-oiution found itself in conflict
with the Miltonic, rather than the Mosaic cosmology. All this
re[)resents an interesting phase in intellectual development.
Forerunners of Lamarck. — We now take up the imme-
diate predecessors of Lamarck. Those to be mentioned are
BulTon, Erasmus Darwin, and Goethe.
Buffon (1707-1788) {Fig. 116), although of a more philo-
sophical mind than many of his contemporaries, was not a
true investigator. That is, he left no technical papers or
contributions to science. From 1739 to the time of his death
he was the sujierin ten dent of the Jartlin du Roi. He was a
man of elegance, with an assured position in society. He
was a delightful writer, a circumstance that enabled him to
make natural history popular. It is said that the advance
sheets of BufTon's Hisloire Naturelle were to be found on the
tables of the boudoirs of ladies of fashion. In that work he
suggested the idea that the difl"crcnt forms of life were grad-
ually produced, but his timidity and his prudence led him
to be obscure in what he said.
;dbyGOOglC
433
BIOLOGY A-ND ITS MAKERS
Packard, who has studied his writings \rilh care, sa#
that he was an evolutionist through all !)erio<ls of his life, not
as is commonly maintained, bclic\'ing first in Ihc fi.xily oi
species, later in ihcir changeability, and lastly returning to
his earlier jxisition. "The impression left on the mind after
reading Ruffon is that even if he threw out these si
and then retracted them, from fear of annoyance or e»(
persecution from the bigots of his lime, he did not hid
always lake them seriously, but rather joilcd them down I
passing thoughts. Certainly he did not present thctn in ti
^oogTi
RISK OF EVOLUTIONARY THOUGHT
413
formal, forcible, and scientific way that Erasmus Darwin did.
The result is that the tentative views of Buffon, which have
to be with much research extracted from the forty -four vol-
umes of his works, would now be regarded as in a degree
su[)crficial and valueless. But they ap|)carcd thirty-four
years before Lamarck's theory, and though not epoch-making.
they arc such as will render the name of Button memorable
for all lime." (Packard.)
Erasmus Danvin (Fig. 1 17) was the greatest of Lamarck's
prwicci'ssors. In 1794 he published the Zoonomia. In this
work he staled ten principles; among them he vaguely
sugf^ested the transmisiiion of acquired characteristics, the
law of sexual selection — or the law of battle, as he called it^
;dbyGOOglC
414 BiOLOGV AND ITS MAKERS
protective coloration, etc. His work received some notice
from scholars, Paiey's Natural Theology, for illustration,
was written against it, although Paley is careful not to men-
lion Darwin or his work. The success of Paiey's book is
probably one of the chief causes for the neglect into which
the views of BufTon and Erasmus Darwin fell.
Inasmuch as Darwin's conclusions were published before
Lamarck's book, it would be interesting to determine whether
or not Lamarck was influenced by him. The careful con-
sideration of this matter leads to the conclusion that Lamarck
drew his inspiration directly from nature, and that points of
similarity between his views and those of Erasmus Darwin
are to be looked upon as an example of parallelism in
thought. It is altogether likely that Lamarck was wholly un-
acquainted with Darwin's work, which had been published
in England.
Goethe's connection with the rise of evolutionary thought
b in a measure incidental. In 1790 he published \\is Meta-
morphosis of Plants, showing that flowers arc modified
leaves. This doctrine of metamorphosis of parts he presently
applied to the animal kingdom, and brought forward
his famous, but erroneous, viTlebrale theory of the skull.
As he militated on the extent of modilicalions there arose
in his mind the conviction that all plants and animals have
been evolved from the mo<iificalion of a few parental types.
Accordingly he should be accorded a place in the history of
evolutionary thought.
Opposition to Lamarck's Views. — Lamarck's doctrine,
which was published in dermite form in i8o(), has been
already outlined. We may well in<[uire, Why did not his
views take hold? In the first place, they were not accepted
by Cuvicr. Cu\-icr's opposition was strong and vigorous,
and succeeded in causing the theon,- of Lamarck to be com-
pletely neglected by the French [leople. .\gain, we must
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 415
recognize that the time was not ripe for the acceptance of
such truths; and, finally, that there was no great principle
enunciated by Lamarck which could be readily understood
as there was in Darwin's book on the doctrine of natural
selection.
The tem|K)rary disappearance of the doctrine of organic
evolution which occurred after Lamarck expounded his theory
was also owing lo the reaction against the speculations of
the school of N aiur-Philosophk. The extravagant specula-
tion of Oken and the other represent at i\'es of this school
complelely disgusted men who were engaged in research by
obser\alion and ex[)eriment. The reaction against that
school was so strong thai it was diflicuit to get a hearing for
any theoretical speculation; but Cuvier's influence must be
looked uix>n as the chief one in causing disregard for La-
marck's writings.
The work of Cu\ier has been already considered in con-
nection both with comparati\"e anatomj' and ?x)ology, but
a few points must still be held under consideration. Cuvier
brought forward the idea of cataslrophism in order to explain
the disappearance of the groups of fossil animals. He be-
lieved in the doctrine of spontaneous generation. He held
to the doctrine of pre -delineation, so that it must be admitted
that whenever he forsook obsenation for speculation he
was singularly unhappy, and it is undeniable that his posi-
tion of hostility in reference to the speculation of Lamarck
retarded the progress of science for nearly half a century.
Cuvier and Saint-Hilaire,— In 1830 there occurred a
memorable controversy between Cmier and Saint-Hilaire.
The latter {Fig. 1 18) was in early life closely associated with
Lamarck, and shared his \iews in reference to the origin of
animals and plants; (hough in certain points Saint-Hilaire
was more a follower of Bullon than of Lamarck. Strangely
enough, Saint-Hilaire was regarded as the stronger man of
;dbyGOOglC
4i6
BIOLOGY AND ITS MAKERS
the two. He was more in the public eye, but was not a man
of such deep intellcctuahty as Lamarck. His scientific repu-
tation rests mainly upon his Pliilosopliie Atiatomtque. The
contro\crsy between him and Cu^icr was on the subject of
unity of type; but it involve<I the (luesiion of llie fixity or
mutabiliiy of species, and therefore it involvwi the foundation
of the question of orijanic evolution.
This (iehalu slirreii all inielleciual Iuiro|ie. (."uvit-r won
as being the belter debatLT and the belter manager of his
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 41?
case. He pointed triumphantly to the four branches of the
animal kingdom nhich he had established, maintaining that
these four branches represented four distinct types of organi-
zation; and, furthermore, that fixity of species and fixity of
type were necessary for the existence of a scientific natural
history. W'c can see now that his contention was wrong,
but at the time he won the debate. The young men of
the period, that is, the rising biologists of France, were
nearly all adherents of Cuvier, so that the effect of the de-
bate was, as previously stated, to retard the progress of sci-
ence. This noteworthy debate occurred in February, 1830.
The wide and lively interest with which the debate was
followed may be inferred from the excitement manifested
by Goethe. Of the great poel-naturalist, who was then in
his eighty-first year, the following incident is told by Soret :
"Monday, .Aug. 2d, 1830, — ^The news of the outbreak of
the revolution of July arrived in Weimar to-day, and has
caused general excitement. In the course of the afternoon
I w ent to Goethe. ' Well,' he exclaimed as I entered, ' what
do you think of this great event? The volcano has burst
forth, all is in flames, and there are no more negotiations
behind closed doors.' 'A dreadful affair,' I answered;
'but what else could be expected under the circumstances,
and with such a ministry, except that it would end in the
expulsion of the present royal family?' *We do not seem
to imderstand each other, my dear friend,' replied Goethe.
'I am not speaking of those people at all; I am interested
in something very difftrent. I mean the dispute between
Cuvier and Gcoffroy de Saint-Hilaire, which has broken out
in the -Academy, and which is of such great importance to
science.' This remark of Goethe came upon me so unex-
pectedly that I did not know what to say, and my thoughts
for some minutes seemed to ha\e come to a complete stand-
still. 'The affair is of the utmost importance,' he con-
;dbyGOOglC
4i8 BIOLOGY AND ITS MAKERS '
tinued, ' and you can not form any idea of what I felt on
receiving the news of the meeting on the 19th. In Gcoffroy
de Saint-Hilaire we have 'now a mighty ally for a longtime
to come. But I see also how great the sympathy of the
French scientific world must be in this affair, for, in spile of
the lemble political excitement, the meeting on the 19th
was attended by a full house. The best of it is, however,
that the sjnthetic treatment of nature, introduced into
France by Geoftroy, can now no longer be stopped. This
matter has now become public through the discussions in the
Academy, carried on in the ])resencc of a large audience;
it can no longer be referred lo secret committees, or be settled
or suppressed behind closed doors.' "
Influence of Lyell's Principles of Geology. — But just as
Cu\ner was triumphing over Saint-Hilaire a work was being
published in England which was destined to overthrow the
position of Cuvier and to bring again a sulTicient foundation
for the basis of mutability of species. I refer to Lyell's
Principles 0} Geology, the influence of whicli has already
been spoken of in Chai)ler X\'. Lyell laid down the prin-
ciple that we are to interpret occurrences in the past in the
terms of what is occurring in the present. He demonstrated
that observations upon the present show that the surface of
the earth is undergoing gradually slow changes through the
action of various agents, and he ]X)inted out thai we must
view the occurrences in the past in ihe light of occurrences
in the present. Once this was applied to animal forms it
became evident that the observations u|K)n animals and jflants
in the present must be ai)piied to the lifeof the fossil series.
These ideas, then, paved the way for the concf|>lion of
changes in nature as being one continuous series.
H, Spencer. — In 1852 came the publication of Herl>ert
Spencer in the Leader, in which he came very near anlici-
pating the doctrine of natural selection. He advanced ihe
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 4^9
developmental hypothesis, savnng that c\'en if its supporters
could "merely show that the production of species by the
process of modification is concei\abIc, ihey would be in a
better position than their opjwnents. But they can do much
more than this; they can show that the process of modifica-
tion has affected and is affecting great changes in all organ-
isms subject lo moi"lif)ing influences- . • • They can show
that any existing spc'cies, animal or \egctablc, when placed
under condilions different from its previous ones, imme-
diately begins to undergo certain changes of structure fitting
it for the new conditions. The)' can show that in successive
generations these changes continue, until ultimately the
new condilions become the natural ones. The)' can show
that in cultivated plants and domesticated animals, and in the
several races of men, these changes ha\'e uniformly taken
place. They can show that the degrees of difference so pro-
duced are oflen, as in dogs, greater than those on which dis-
tinctions of species are in other cases founded. They can show
that it is a matter of dispute whether some of these modified
forms are varieties or modified species. .\nd thus they can
show that throughout all organic nature there is al work a
modifying influence of the kind they assign as the cause of
these specific differences; an influence which, though slow
in its action, does in time, if the circumstances demand it,
produce marked changes; an inllucnce which, to ail appear-
ance, would produce in the millions of years, and under ihc
great \'arieties of condilions which geological records imply,
any amount of change."
"It is impossible." says Marshall, "to depict better than
this the condition prior to Darwin. In this essay there is full
recognition of the fact of transition, and of its being due to
natural influences or causes, acting now and at all times.
Vet it remained comparatively unnoticed, because Spencer,
like his contemporaries and predecessors, while advocating
;dbyGOOglC
420 BIOLOGY AND ITS MAKERS
evolution, was unable to state explicitly what these causes
were."
Darwin and Wallace. — In 1858 we come to the crow-n-
ing c\ent in ihe rise of evolutionary thought, when Alfred
Russcl Wallace sent a communication to Mr. Danvin, beg-
ging him to look it over and givehimhisopinionof it. Dar^vin,
who had been working upon his theory for more than twenty
years, patiently gathering facts and testing the same by
exi>erimenl, was greatly surprised to find that Mr. Wallace
had independently hit upon the same principle of explaining
the formation of species. In his generosity, he was at first
disposed to withdraw from the field and publish the essay of
Wallace without saying anything about his own work. He
decided, however, to abide by the decision of two of his
friends, to whom he had submitted the matler, and the result
was that Ihe paper of W'allace, accompanied by earlier com-
munications of Darwin, were laid before the Linnaean Societ)-
of London, This was such an im[K)rtant c\'ent in the his-
tOTy of science that its consideration is extended by quoting
the following letter:
" London, June jolh, 1858.
"My Dear Sir: The accompanying pajKrrs, which we
have the honor of communicating to the Linna;an Society,
and which all relate to the same subject; viz., the laws which
affect the |>roduction of varieties, races, and species, contain
the results of the investigations of two indefatigable natural-
ists, Mr. Charles Danvin and Mr. Alfred Wallace.
"These gentlemen hanng, independently and unknown
to one another, conceived the same very ingenious Iheorj' to
account for the a])])carancc and perpetuation of varieties
and of specific forms on our planet, may both fairly claim the
merit of being original thinkers in this imporlanl line of
inquiry; but neither of ihem having published his views,
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 421
though Mr. Darwin has for many years pasl been repeatedly
urged by us lo do so, and bolh authors having now unreser\'-
edly placed their papers in our hands, we think it would
best promote the interests of science thai a selection from
them should be laid before the Linna'an Societ)-.
"Taken in the order of their dates, they consist of:
"i. Extracts from a MS. work on species, by Mr. Dar-
win, which was sketched in 1839 and copied in 1844, when
the cop)' was read by Dr. Hooker, and its contents afterward
communicated to Sir Charles Lycli. The first part is devoted
to The Variation of Organic Beings under Doineslication and
-H llteir Xatural Stale; and the second chapter of that part,
from which we projjose to read to the Socicl)' the extracts
referred to, is headed On the Variation 0} Organic Beings in
J Stale 0} Xalnrc; on the Natural Means 0} Selection; on the
Comparison o'j Domestic Races and True Species.
" 2. An abstract of a private letter addressed to Professor
Asa Gray, of Boston, U. S.. in October, 1857, by Mr. Danvin,
in which he repeats his views, and which shows that these
remained unaltered from 1839 to 1857.
"3. .\n essay by Mr. Wallace, entitled On the Tendency
of Varieties to Depart Indefinitely from the Original Type.
This was written at Tematc in February, 1858, for the
perusal of his friend and correspondent, Mr, Darwin, and
sen! to him with the expressed wish that it should be for-
warded to Sir Charles Lyell, if Mr Darwin thought it suffi-
cicntl}- novel and interest in!:;. So hi<ihly did Mr, Darwin
appreciate the \alue of the \iews therein set forth that he
proposed, in a letter to Sir Charles Lyell, to obtain Mr.
Wallace's consent to allow the essay to be published as soon
as possible. Of this step we highly a])proved, provided Mr.
Darwin did not withholti from the ])ublic, as he was strongly
inclined to do (in favor of Mr. Wallace), the memoir which
he had himself written on the same subject, and which, as
;dbyGOOglC
422 BIOLOGY AND ITS MAKERS
before stated, one of us had perused in 1844, and the con-
tents of whicii we had both of us been pri\'y lo for many years,
" On representing this lo Mr. Darwin, he gave us ]>t-rmis-
sion lo make ivhat use we though! proper of his memoir, etc. ;
and in adoj>ting our present course, of presenting it to the
Linna;an Society, we have e.xplaincd to him that we arc not
solely considering the relative claims to priority of himself
and his friend, but the interests of science generally; for we
feel it lo be desirable that views founded on a wide deduction
from facts, and matured by years of reflecting, should con-
stitute at once a goal from which others may start; and thai,
while the scientific world is wailing for the appearance of
Mr. Darwin's complete work, some of ihe leading results of
his labours, as well as those of his able correspondent, should
together be laid before the public.
"We have the honour lo be yours very obcdieniiy,
Charles Lvell,
Jos. D, Hooker."
Personality of Darwin. — The personality of Darwin is
extremely interesting. Of his numerous iwrtraits, the one
shown in Fig. iiq is less commonly known than those show-
ing him with a beifti and a much furrowed forehead. This
portrait re]>rcscnts him in middle life, about ihe lime of the
])ublication of his Origin oj Species. It shows a ra;her
typical British face, of marked individuality. Sleadiness,
sincerity, and urbanity are all depicted here. His bluish-
gray cjes were overshadowed by a |)rojecting ridge and vcrj'
prominent, bushy eyebrows that make his ])ortrait, once seen,
easily recognized thereafter. In the full-length imrtraits
representing him scaled, every line in hisbody shows thcquiet,
philosophical temper for which he was notable. .An inlimale
account of his life is contained in the I.ije and Letters oj
Charles Dam'in (1887) and in More /Ailirs oj Dam-in [igo^,],
;dbyGOOglC
RISE OP EVOLL'TIOM.VRY THOUGHT
423
both of which are illuslraltxl by portraits and other pictures.
The books about Darwin and his work arc numerous, but
the reader is referred in particular to the two mentioned as
giving the best conception of the great naturalist and of his
personal characteristics.
He is described as being about six feet high, but with a
stoop of the shoulders which diminished his apparent height;
"of active habits, but with no natural grace or neatness of
movement," "In manner he was bright, animated, and
cheerful; a delightfully considerale host, a man of never-
failing courtesy, leading him to re])ly at length to letters
from anybody, and sometimes of a most foolish kind."
His Home Life.— "Darwin was a man greatly loved and
res|)ected by all who knew him. There was a peculiar charm
;dbyGOOglC
424 BIOLOGY AND ITS MAKBKS
about his manner, a constant deference to others, and a
faculty for seeing the best side of e\er_vthing and everj--
body."
He was most affectionate and considerate at home. The
picture of Darwin's life with his children gi^cs a glimpse
of the tenderness and deep affection of his nature, and the
re\'crent regard with which he was held in the family circle
is very touching. One of his daughters wTites: "My first
remembrances of my father arc of the delights of his playing
with us. He was passionately attached to his own children,
although he was not an indiscriminate child-lover. To all
of us he was the most delightful playfellow, and the most
perfect sympathizer. Indeed, it is im[jossible adequately to
describe how delighlful a relation his was to his family,
whether as children or in ihcir later life.
" It is a proof of the terms on which we were, and also of
how much he was valued as a playfellow, that one of his sons,
when about four years old, tried to bribe him with a sixpence
to come and play in working hours. We all knew the sacre<l-
ness of working time, but that any one should resist six])cnce
seemed an impossibility."
Method of Work. — Darwin's life, as might be inferred
from the enduring quality of his researches, shows an
unswcr\'ing purpose. His theory was not the result of a
sudden flash of insight, nor was it struck out in the heat
of ins])iralion, but was the product of almost unexample<l
industry and conscientious endeavor in the face of unfavor-
able circumstances. Although strikingly original and inde-
pendent as a thinker, he was slow to arrive at conclusions,
examining with the most minute and scrupulous care the
ground for every conclusion. "One quality of mind that
sceme'l to be of especiid advantage in leading him to make
iliscoveries was the habit of never letting cxcc|>tions pa.ss
unnolice<l." He enjoyed experimenting much more than
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 4^5
work which only entailed reasoning. Of course, he was a
great reader, but for books as books he had no respect, often
cutting large ones in two in order to make them easier to
hold while in use,
Darwin's Early Life. — Charles Darwin was bom in iSog
at Shrewsbury, England, of distinguished ancestry, his grand-
father being the famous Dr. Erasmus Darwin, the founder,
as we have seen, of a theory of evolution. In his youth he
gave no indication of future greatness. He was sent to
Edinburgh to study medicine, but that the work failed to
arouse in him an absorbing interest is shown by his charac-
terizing .some of the lectures as '" incredibly dull." Alter two
sessions, at the suggestion of his father, he left Edinburgh to
study for the Church. He then entered Christ's College,
Cambridge, where he remained for three years, .\fter ta-
king his baccalaureate degree at Cambridge, where he had
manifested an interest in scientific study, and had been
encouraged by Professor Hcnslow, came the event which
proved, as Darwin says, "the turning-point of my life."
This was his ap]>ointment as naturalist on the surveying
expedition about lo be entered upon by the ship Beagte.
.\n amusing circumstance connected with his appointment
is thai he was nearly rejected by Captain Fitz-Roy, who
doubted "whether a man with such a sha|>ed nose could
possess sufficient energy and determination for (he voyage,"
Voyage of the Beagle. — The voyage of the Beagle ex-
tended over five years (1831-18.^6), mainly along the west
coast of South .\merica. It was on this voyage that Darwin
acquired the habit of constant industry. He had also oppor-
tunity to take long trips on shore, engaged in observation
and in making extensive collections. He observed nature in
the field under exceptional circumstances. .As he traveled
he noted fossil forms in rocks as well as the li\ing forms in
field and forest. He observed the correspondence in type
;dbyGOOglC
426 BIOLOGY AND ITS MAKERS
between certain extinct forms and recent animals in South
America. He noticed in the Galapagos Islands a fauna similar
in general characteristics to that of the mainland, five or six
hundred miles distant, and yet totally ditTcrent as to sfwcies.
Moreover, certain species were found to be confined to ]>ar-
ticular islands. These observations awakened in his mind,
a mind naturally given to inquiring into the causes of things,
questions that led to the formulation of his theory. It was
not, however, until 1837 ihat he commenced his first note-
book for containing his observations upon the transmulatious
of animals. He started as a tirm believer in the fixity of
species, and s|>cnt several jcars collecting and considering
data before he changed his views.
At Down.— On his return to England, after si)ending
some time in London, he purchased a country-place at Down
and, as his inheritance made it possible, he devoted himself
entirely to his researches.
But, as is well known, he found in his illness a great
obstacle to steady work. He had been a vigorous youth and
young man, fond of outdoor sports, as fishmg, shooting,
and the like. After returning from his long voyage, he was
affected by a form of constant illness, involving a giddiness
in the head, and "for nearlj- forty years he never knew one
day of the health of an ordinary man, and thus his life was
one long struggle against the weariness and strain of ack-
ncss." Gould in his Biographical Clinics attributes his ill-
ness to eye-strain,
" Under such conditions absolute regularity of routine was
essential, and the day's work was carefully planned out. At
his best, he had three periods of work: from 8.00 to 9.30;
from 10.30 to 12.15; ^"'' from 4.30 to 6.00, each period being
under two hours' duration."
The patient thoroughness of his experimental work and of
his observation is shown by the fact that he did not publish
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 42/
his book on the Origin of Spicies until he had worked on
his theory twenty-two years. The circumstances that led
to his publishing it when he did ha\'e already been indi-
cated.
Parallelism in the Thought of Darwin and Wallace.-—
Xo one can read the letters of Darwin and Wallace explaining
how they arrived at their idea of natural selection without
marveling at the remarkable parallelism in the thought of the
two. It is a noteworthy circumstance that the idea of natural
selection came to both by the reading of the same book, Mal-
Ihus OH Population.
Danvin's statement of how he arrived at the concei>-
tion of natural selection is as follows; "In October, 1838,
that is, fifteen months after I had begim ray systematic
inquiry, I happened to read for amusement Mallhus on
Population, and being well prepared to appreciate the
struggle for existence which e\'cr\-\vhere goes on from long-
continued observations of the habits of animals and plants,
it at once struck me that under these circumstances favourable
variations would tend to be jireserved and unfaiourable ones
to be destro_\'cd. The result 0} this 'u.-oidd be the formation
oj «fi;- species. Here then I had at last got a theory by
which to work, but I was so anxious to avoid prejudice that
I determined not for some time to write even the briefest
sketch of it. In June, 1842, I first allowed myself the satis-
faction of wTiting a \ery brief abstract of mj' theory in pencil,
in lhirty-fi\-e pages, antl this was enlarged during the summer
of 1844 into one of 230 pages."
And Wallace gives this account: "In February, 1858, I
was suffering from a rather se\'ere attack of intermittent fever
at Temate, In the Moluccas; and one day, while I>ing on
my bed during the cold fit, wrapped in blankets, though the
thermometer was al 88° Fahr., the problem again presented
itself to me, and something led me to ihink of the 'positive
;dbyGOOglC
428
BIOLOGY AND ITS MAKERS
checks' described by Malthus in his Essay on Population,
a work I had read several years before, and which had made
a deep and permanenl impression on my mind. These
checks — war, disease, famine, and ihe like- — musi, it occurred
to me, act on animals as well as man. Then I thought of
the enormously rapid multiplication of animals, causing these
checks to be much more ctTcctive in them than in the case of
man; and whik- pondering vaguely on this fact, there sud-
denly fia.'-lK-d upon mc the i'hv of ihe survival of the fittest-
thai the individuals removed bv these checks must be on the
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 429
whole inferior to those that survived. In the two hours that
elapsed before my ague fit was over, I had thought out
almost the whole of the theory; and the same evening I
sketched the draught of my paper, and in the two succeeding
evenings wrote it out in full, and sent it by the next post to
Mr. Darwin,"
It thus appears that Ihe announcement of the Darwin-
Wallace theory of natural selection was made in 1858, and
in the following year was published the book, the famous
Origin of Species, upon which Darwin had been working
when he received Mr. Wallace's essay. Darwin spoke of this
work as an outline, a sort of introduction to other works
that were in the course of preparation. His subsequent
works upon Animals and Plants under Domestication, TIte
Descent oj Man, etc., etc., expanded his theory, but ncaie of
them effected so much stir in the intellectual world as the
Origin oj Species.
This skeleton outline should be filled out by reading
Darwin's Life and Letters, bj' his son, and the complete
papers of Darwin and Wallace, as originally published in
the Journal of Ihe Linnaan Society. The original papers
are reproduced in the Popular Science Monthly for Xovem-
bcr, 1 901.
Wallace was bom in 1823, and is slill living. He shares
wilh Darwin the credil of propounding the theory of natural
selection, and he is notable also for the publication of import-
ant books, as the Malay A rcliipclago, The Geographical Distri-
bution of Animals, The Wonderful Century , etc.
The Spread of the Doctrine of Organic Evolution. Hux-
ley.— Darwin was of a quiet habit, not aggressi^'e in the
defense of his views. His theory provoked so much oppo-
sition that it needed some defenders of Ihe pugnacious type.
In England such a man was found in Thomas Henry Huxley
(1825-1895). He was one of the greatest popular exponents
;dbyGOOglC
4,^o
BIOLOGY AND ITS MAKERS
of science of the nineteenth century; a man of most thorough
and exact scholarship, with a keen, analytical mind ihat went
(lirc'Ctly to ihe center of questions under consi<]eration, and
powers as a writer that ga\'e him a wi<ie circle of readers.
He was magnificently sincere in his fight for the prevalence
of intellectual honesty. Doubtless he will be longer remem-
bered for this service than for anythinfj else.
He defended the doctrine of evolution, not only against
oratorical attacks like that of Bishop \\'illK'rforce, but against
well -con side red arguments and more worthy opponents. He
advancwl the .standing of the theory in a less direct way
by urging the pursuit of scientific studies by high-school
and university students, and by bringing science closer to
;dbyGOOglC
RISE OF KVOLL'TKjNAKY THOUGHT 431
the people. He was a pioneer in the laboratory leaching of
biology, and his Manual ha^ been, ever since its publica-
tion in 1874, the inspiration and the motlel for writers of
directions for practical work in that field.
It Is not so generally known that he was also a preat
investigator, producing a large amount of purely technical
researches. After his death a memorial edition of his scien-
tific memoirs was published in four large quarto volumes.
The extent of his scientific output when thus assembled was
a surprise to many of his co-workers in the field of science.
His other writings of a more general character ha\'e been
collected in fourteen volumes. 5>omc of the essays in
this collection arc models of clear and vigorous English
style. Mr. Huxley did an astonishing amount of scientific
work, e5i>ecially in morphology and pala^ntology. Those
who have been privileged to look over his manuscripts and
unpublished drawings in his old room at South Kensington
could not fail to have been impressed, not only \vith the
extent, but also with the accuracy of his work. Taking
Johannes ^^ullcr as his exemplar, he investigated animal
organisms with a completeness and an exactness that have
rarely been equaled.
An intimate account of his life will be foimd in The Life
and Letters of Thomas Henry Huxley, b\' his son.
Haeckel.— Ernst Haeckel, of Jena, bom in 1834 (Fig. 122),
was one of the earliest in Germany to take up the de-
fense of Darwin's hyjxjthesis. .\s early as 1866 he applied
the doctrine of evolution to all organisms in his Gemrelle
Morphologic. This work, which has been long out of print,
represents his best contribution to evolutionan- thought.
He has written widely for general readers, and although his
writings are popularly believed (o represent the best scientific
thought on the matter, those written for the general public
are not regarded by most biologists as strictlj- represent at i\-e.
;dbyGOOglC
432
BIOI-OGY AND ITS MAKERS
As a thinker he is more careless than Huxley, and as a result
less critical and exact as a writer.
There can be no doubt that the germs of evolutionary
thought existed in Greek philosophy, and that they were
relaint-ii in a Mate of low vitality arnon^; the medi;i-val thinkers
who rellecleii upon the itrobli-ni of creation. It was not,
however, until the hef^inninj^ of the nineteenih century thai,
under the nurture of I-amarck, they f^rew into what we may
s])cak of as the modern theory of evolution. After various
vicissitude.s this doctrine was made fertile by Darwin, who
supplied it with a new principle, that of natural selection.
The fruils of this lonj; [;ro\vth are now beinj^ f;alhered.
After Darwin the i)rohlem of biolof;y became not merely
to describe phenomena, but lo LNjilain them. This is the
;dbyGOOglC
RISE OF EVOLUTIONARY THOUGHT 433
outcome of the rise and progress of biology: first, crude and
uncritical obscn'ations of the forms of animaled nature;
then descriptive analysis of their structure and development;
and, finally, experimental studies, the effort to exiilain vital
phenomena, an cfTorl in which biologists are at present en-
gaged.
;dbyGOOglC
CHAPTER XX
RETROSPECT AND PROSPECT. RECENT TENDEN-
CIES IN BIOLOGY
W'hfn one \'niv:s llie progress of biology in retrospect, the
broad truth stands out that there has been a continuity of
development in biological thought and interpretation. The
new proceeds out of the old, but is genetically related to it.
A good illustration of this is seen in the motlified sense in
which the theories of e]»igenesis and prc-formation ha\'e been
retained in the biological philosophy of the nineteenth cen-
tury. The same kind of (jucstion that divided the philos-
ophers of the seventeenth and eighteenth centuries has
remained to vex those of the nineteenth; and, although both
processes have assumed a different aspect in the light of ger-
minal conlinuily, the theorists of the last i)art of the nineteenth
century were divided m their outlook ujKjn biological i>roc-
esses into those of the epigenetic school and those who arc
persuaded of a prc-organizalion in the germinal elements of
organisms. Leading biological questions were warmlj- dis-
cussed from these dilTerent points of \'iew.
In its general character the progress of natural science
has been, and still is, a crusade again.st .suix^rstition; and it
may be remarked in passing that "the nature of su|x.Tstition
consists in a gross misunderstandinj; of the causes of nat-
ural phenomena." The strugf-le has been more marke<i in
biology than in otlu-r deparlmeni.s of science because biology
involves the consideration of livinj^ organi.sms and undertakes
;dbyGOOglC
RECENT TENDENCIES IN BIOLOGY 435
to establish the same basis for thinking about the organization
of the human body as about the rest of the animal series.
The lirst triumph of the scientific method was the over-
throw of authority as a means of ascertaining truth and sub-
stituting therefor the method of observation and experiment.
This carries us back to the days of \'esaniis and Harvey,
before the framework of biology was reared. But the scien-
tific method, once established, led on gradually to a belief in
the constancy of nature and in the prevalence of universal
laws in the production of all phenomena. In its progress
biology has exhibited three phases which more or less
overlap: The first was the descriptive phase, in which
the obvious features of animals and plants were merely
described; the descriptive was supplemented by the com-
parati\-c method; this in due course by the experimental
method, or the sludy of the processes that lake place in
organisms. Thus, description, comparison, and experiment
represent Ihc great phases of biological development.
The Rotable Books of Biology and their Authors, — The
progress of biology has been owing to the efforts of men of
very human qualities, yet each with some special distinguish-
ing feature of eminence. Certain of their publications are
the mile-stones of the way. It maj' be worth while, therefore,
in a brief recajiitulation to name the books of widest general
influence in the progress of biology. Only those publica-
tions will be mentioned that have formed the starting-point
of some new mo\-ement, or have laid the foundation of some
new theory.
Beginning with the revival of learning, the books of
Vesalius, De Corporis Humaiii Fabrica (1543), and Harvey,
De Motu Cordis el Sanguinis (1628), laid the foundations of
scientific method in biology.
The pioneer researches of Malpighi on the minute anat-
omy of plants and animals, and on the development of the
;dbyGOOglC
43^ BIOLOGY AND ITS MAKERS
chick, best represent the progress of investigation between
Harvey and Linnfeus. The three contributions referred to
are those on the Anatomy oj Plants {Anatome PlatUarum,
1675-1679); on the Anatomy oj llie Silkworm {De Bombyce,
1669) ; and on the Development 0} the Chick {De Formatione
PiUli in Ovo and De Ovo Incubalo, both 1672).
Wc then pass lo the Syslcma Natura (twelve editions,
1735-1768) of Linn<eus, a work that had such wide in-
fluence in stimulating activity in systematic botany and
zoology.
Wolff's Theoria Cenerationis, 1759, and his De Formaiiotie
InleslitwTum, 1764, csjjecially the latter, were pieces of
observation marking the highest level of investigation of
development prior to that of Pander and Von Baer.
Cuvier, in Le Rkgne Animal, 1816, applied the principles
of comparative anatomy lo ihc entire animal kingdom.
The publicaiion in 1800 of Richat's Trails des Membranes
created a new dej»artment of anatomy, called histology.
J^amarck's book, La Philosophie Z.oologique, 1809, must
have a place among the great works in biology. Its influence
was delayed for more than fifty years after its publication.
The monumental work of Von Kaer on Development
(Ufbi-r Enfu-icklungsgescliich/e drr Thiere), 1828, is an almost
ideal combination of observation and conclusion in embry-
ology.
The Microscopiscbe Vnlcrsiuhungen, i&y), of Schwann
marks the foundation of the ccll-Lheory.
The Handbook of Johannes Xliiller {Handbiuk der
Physiologie des Mcnschen), 1846, remains unsurpassed as to
its plan and its execution.
Max Schullze in his treatise Uiber Muskclkorperchen und
das was man eine Zrllc zu nennen lialv. 1861 , established one
of ihi- most im[H>riant conceptions with which biologj' has
h(,H;n enriclicd, viz., the protoplasm doctrine.
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RECENT TENDENCIES IN BIOLOGY 437
Darwin's Origin oj Species, 1859, is, from our present
outlook, the greatest classic in biology.
Pasteur's Studies on Fermenlation, 1876, is typical of Ihe
quality of his work, though his later investigations on in-
oculations for ihc prcvcniion of hydrophobia and other
maladies are of gitater importance to mankind.
Ii is somewhat puzzling to selcci a man to represent the
study of fossil life, one is templed to name E. D. Cope,
whose researches were conceived on the highest plane.
Zittcl, however, co\-cred the entire field of fossil life, and his
Handbook of Paleontology is designated as a mile-post in the
development of that science.
Before the Renaissance the works of Aristotle and Galen
should be included.
From the view-point suggested, the more notable figures in
the development of biology are: Aristotle, Galen, Vesalius,
Harvey, Mal]>ighi, Linnaeus, WolfT, Cuvier, Bicliat, Lamarck,
Von Baer, J. MUlIer, Schwann, Schultze, Darwin, Pasteur,
and Ziitcl.
Such a list is, as a matter of course, arbitrary, and can
serve no useful jjurpose except that of bringing into coni-
binaiion in a single group the names of the most illustrious
founders of biological science. The individuals mentioned
are not all of the same relative rank, and the list should be
eMendef.i rather than contracted. Schwann, when the entire
output of the two is considered, would rank lower as a scien-
tific man than Koellikcr, who Is not mentioned, but the
former must stand in the list on account of his connection
with the cell-theory. Virchow, the presumptive foimder of
pathology, is omitted, as are also investigators like Koch,
whose line of activity has been chiclly medical.
Recent Tendencies in Biology. Higher Standards. — In
attempting to indicate some of the more evident influences
that dominate biological investigation at the present time.
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43^ BIOLOGY AND ITS MAKERS
nothing more than an enumeration of tendencies with a
running commentary is ]K)Ssib!c. One notes first a whole-
some influence in ihe establishment of higher standards, both
of research and of scientific publication. Investigations as a
whole ha\c become more intensi\'e and more critical. Much
of the work that would have passed muster for publication
two decades ago is now regarded by the editors of the best
biological periodicals as too general and loo superficial. The
requisites for the recognition of creditable work being higher,
tends to elevate the whole level of biological science.
Improvement in Tools and Methods. — This has come
about partly through impro\'cment in the tools and in the
methods of the in\'estigators. It can hardly be said , however,
that thinking and discernment ha\c been advanced at the
same rate as the mechanical helps to research. In becoming
more intensive, the investigation of biological problems has
lost something in comprehensiveness. That which some of
the earlier investigators lacked in technique was compensated
for in the breadth of their preliminary training and in their
splendid appreciation of the relations of the facts at their
disposal.
The great improvement in the mechanical adjustments
and in the optical powers of microscopes has made it possible
to see more regarding the physical structure and the activities
of organisms than ever before. Microtomes of the best work-
manship have placed in the hands of histologists the means
of making serial sections of remarkable thinness and regiilar-
itj'.
The great development of micro-chemical technique also
has had the widest influence in promoting exact researches
in biology. Special staining methods, as those of Golgi
and Hcthc, by means of which the wonderful fabric of the
nervous sy.slcm has been revealed, arc illustrations.
The separation by maceration and smear preparation of en-
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RECENT TENDENCIES IN BIOLOGY 439
tire histological elements so that they may be \-ie\ved as solids
has come to supplement the study of sections. Reconstruc-
tion, by carving wax jtlates of known thickness into the form
of magnified sections drawn upon their surfaces to a scale,
and then filling the plates together, has been very helpful in
picturing complicated anatomical relations. This method
has made it jjossiblc to produce permanent wax models of
minute structures magnified lo any desired degree. Minute
dissections, although not yet sufficiently practiced, are never-
theless better than the wax models for making accurate
drawings of minute structures as seen in relief.
The injection of the bkxxl -vessels of extremely small
embryos has made it i)ossib!c to study advantageously the
circulatory system. l"he softening of bones by acid after
the tissues arc already embedded in celloidin has offered a
means of investigating the structure of the internal ear by
sections, and is widely applicable to other tissues.
With the ad\antage of the new appliances and the new
methods, tlie old problems of anatomy are being worked over
on a higher level of requirement. Still, it is doubtful whether
even the oki problems will t>e solved in more than a relative
way. Il is characteristic of the progress of research that as
one proceeds the iiorizon broadens and new questions spring
up in the pathway of the investigator. He does not solve
the problems he sets out to solve, but opens a lot of new ones.
This is one of the features of scientific research that make
its votaries characteristically optimistic.
Experimental Work. — .\mong the recent influences tend-
ing to advance biology, none is more im[x>rtant than the ap-
plication of experiments to biological studies. The cxjKjr-
imental metho<l is in reality applicable to di\Trse fields of
biological research, and its extensi\T use at present indicates
a movement in the right direction; that is, a growing interest
in the study of processes. One of the earliest problems of
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44° BIOLOGY AND ITS MAKERS
the biologist is to investigate the architecture of living beings;
then there arise questions as to the processes that occur within
the organism, and ihe study of jnocesses involves the employ-
ment of experiments. In the pursuit of physiology exper-
iments have been in use since the time of Harvey, but even
in that science, where the}- are indispensable, experiments
did not become comparative until ihc nineteenth century.
It now appears that various forms of experiment give also
a better insight into the structure of organisms, and the prac-
tice of applying experiments to slructural studies has given
rise to the new department of experimental morphology.
For the purpose of indicating some of the directions in
which biology has been furthered by the cxfxirimental method
of investigation, we designate ihe fields of heredity and evo-
lution, changes in the environment of organisms, studies on
fertilization and on animal behavior.
The recognition that both heredity and the process of
evolution can be subjected to experimental tests was a revela-
tion. Danvin and the early evolutionists thought the evolu-
tionary changes too slow to be appreciated, but now we
kno\v that man\- of the changes can be in\estigated by
experiment. Numerous experiments on heredity in poultry
(Davenport), in rats, in rabbits, and in guinea-pigs (Castle)
have been carried out — experiments that test the laws of
ancestral inheritance and ihrow great light upon the ques-
tions introduced by the investigations of Mendel and De
Vries. The investigations of De \ries on the evolution of
plant-life occupy a notable position among the experimental
studies.
A large number of experiments on the effects produced
by changes in Ihe external conditions of life have been made.
To this class of in\ostigations belong studies on the regulation
of form and function in organisms (I.oeb, Child), the effects
j)roduced by altering mechanical conditions of growth, by
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RECENT TENDENCIES IN BIOLOGY 44^
changing the chemical environment, etc. There is some
internal mechanism in living matter that is influenced by
changes in external conditions, and the study of the regulation
cf the internal processes thai produce form and structure
have given rise to a variety of interesting problems. The
regeneration of lost parts and regeneration after intention-
ally-imposed injury has received much attention (Morgan).
Marine animals arc especially amenable to manipulations of
this nature, as well as to alterations in their surroundings,
on account of the ease in altering the chemical en\'ironment
in which they li\c. The latter may be accomplished by
dissolving harmless chemical salts in the sea-water, and
obsening the changes produced by the alterations of the
surrounding conditions. By this means Herbst and others
have produced very interesting results.
In the field of artificial fertilization, free swimming larvx
have been raised from eggs artificialh' fertilized by changes
in osmotic pressure, and also bj' treating them with both
organic and inorganic acids; and these studies have greatly
altered opinion regarding the nature of fertilization, and of
certain other phenomena of development.
Animal Behavior. — The study of animal behavior (Jen-
nings) is a very characteristic activity of the present, in which
certain psychological processes are in\'cstigaled. These in-
\'estigations ha\'c given rise to a distinct line of research par-
ticipated in by psychologists and biologists. The study of
the way in which animals will react toward light of different
colors, to variations in the intensity of light, to alterations in
temperature, and to various other forms of stimuli are yield-
ing \-ery important results, that enable in\-estigators to look
beneath the surface and to make imixirtant deductions
regarding the nature of psychological processes.
A line closely allied to experimentation is the application
of statistics to biological j)rocesscs, such as those of growth.
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443 BIOLOGY AND ITS MAKERS
stature, the la.w of ancestral inheritance, the statistical study
of variations in spines, markings on shells, etc., etc. (Gaiton,
Pearson, Davenport).
Other branches of biology that have been greatly devel-
oped by the experimental method are those of bacteriology
and physiological chemistry. The advances in the latter
have greatly widened the horizon of our view regarding the
nature of vital activities, and they compose one of the leading
features of current biological investigation.
Some Teodeacies in Anatomical Studies. Cell-Lineage. —
While experimental work occupies the center of the stage,
at the same time great improvements in morphological
studies are evident. It will be only possible, however, to
indicate in a general way the direction in which investigations
are moving. We note, first, a^ in a previous paragraph, that
the improvement in morphology is generic as well as specific.
Anatomical analysis is being carried to its limits in a number
of directions. The investigations that are connected with
the study of cells afford a conspicuous illustration of this
fact. Studies in ccll-Iincage have led to an exact determina-
tion of eel 1-succ fusion in the development of certain animals,
and such studies arc still in progress. Great progress also
has been made in the study of physical structure of living
matter. The tracin.i^ of ccU-lineagc is a feat of rcmarkably
accurate and patient work. But, however much this may
command our admiration, it has been surpassed (as related
in Chapter XI) by investigations regarding the or^^anization
of the egg and the analysis of chromosomes. Boveri, Conk-
lin, Wilson, and others have shown that there are recognizable
areas within the protoplasm of the egg that have a definite
historical relationship to certain structures In process of
development. This is the basis upon which rests the doctrine
of prc-iocalii!a(ion of tissue- forming substances within the
protoplasm of the egg.
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RECEXT TENDEMCIES IN BIOLOGY 443
Anatomy of the Nervous System. — In another direction
the progress of anatomical studies is very evident, that is,
investigations of the ner\'ous system and the sense-organs.
The wonderfully complicated relations of nen'c elements
ha\c been worked out by Ramon y Cajal. The studies of
Hodge anri others upon optical changes occurring within the
ceils of the ner\'ous system owing to their functional activity
ha\e opened a great field for in\'estigation. The studies of
Strong, Herrick, and others upon the distribution of ner\e-
componcnts in the nerves of the head and the investigations
of Harrison on the growth and the regeneration of ner\'e-
fibers give illustrations of current tendencies in biological
investigation. The analysis of the central nenous system
into segmental divisions on the basis of functional actiWty
(Johnston) is still another illustration.
The Application of Biological Facts to the Benefit of Alan-
kind. — The practical application of biology to the benefit
of mankind is a striking feature of present-day tendencies.
The acti\ity set on foot by the researches of Pasteur, Koch,
and others has created a department of technical biology of
the greatest imyxirtance to the human race.
Under the general heading should be included tiie demon-
stration of the connection between insects and the propagation
of yellow fever, malaria, and other disorders; and as an illus-
tration of activity in 1907, we think of the commission recently
api>ointed to investigate the terrible scourge of the sleeping-
sickness which has been pre\alcnt in .Africa. Here also we
would group studies of a pathological character on blood-
immunity, toxin and antitoxin, also studies on the inoculation
for the pre\ention of various diseases that aJTect animals and
mankind. \'ery much benefit has already accrued from the
practical application of biological researches of this nature,
which, in reality, are still in their infancy.
We find the application of biological facts to agriculture
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444 BIOLOGY AND ITS MAKERS
in the form of soil-inoculation, in (he tracing of the sources
of nitrates in the soil, and studies of the insects injurious to
vegetation; their further application lo practical forestry,
and in sanitary sciences. This kind of research is also ap-
plie<l lo the study of food-supply for fishes, as in the case of
Plankton studies.
The Establishment and Maintenance of Biological Lab-
oratories.— The establishment of seaside biological observa-
tories and \'arious other .stations for research have had a great
influence on the development of biology. The most famous
biological station is that founded at Naples (Fig. 123) in 1872
by Anton Dohrn, and it is a gratification to biologists to
know that he still remains its director. This international
station for research has stimulated, and is at present stim-
ulating, the growth of biology by pro\iding the best condi-
tions for carrying on researches and by the distribution of
material which has been put up at the scacoast by the most
skilled prcscrvators. There are many stations modeled
after that at Xaples, The Marine Biological Laboratory
at Woods Holl, Mass., is of especial prominence, and
the recently reorgani^.ed Wistar Institute of Anatomy at
Philadelphia is making a feature of the promotion of ana-
tomical researches, especially those connected with the anat-
omy of the nervous system.
Laboratories similar to those at the seaside have been
established on several fresh-water lakes. The studies carried
on in those places of the complete biology of lakes, taking
into account the entire surroundings of organisms, are very
interesting and imi^rtant.
Under this general head .should be mentioned stations
under the conlrol of the Carnegie In,stilution, the various
scientific sur\X'ys unrler the Go\emmenl , and the United States
Fish CommisMon, which carries on inve^tigalions in the bi-
ology of fi.shes as well as obser\'alions that alTect their use
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446 BIOLOGY AND ITS MAKERS
as articles of diet. The combined output of the various
laboratories and stations of this nature is very considerable,
and their influence upon the progress of bioiog>' is properly
included under the head of present tendencies.
The organization of laboratories in our great universities
and their product exercise a wide influence on the progress of
biology, that science having within twenty-five years corae to
occupy a position of great importance among the subjects of
general education.
Establishment and Maintenance of Technical Periodicals.
— ^It is manifestly very important to provide means for the
publication of results and, as needed, to have technical
periodicals established and properly maintained. Their
maintenance can not be effected on a purely commercial
basis, and the result is that some of our best periodicals re-
quire financial assistance in order to exist at all. The sub-
sidizing and sup])ort of these periodicals aid materiaUy in
the biological advance. A typical technical periodical is
Schultze's famous Arcbiv jiir Mikroscopiscbe Analomie,
founded in 1864 by Schultze and continued to the present
time. Into its pages go the highest grade of investigations,
and its continued existence has a salutary intlucnce upon the
progress of biology. The list of technical ]»criodicals would
be loo long to name, but among others the Morphologisckes
Jalirbucit of Gegenbaur,and KocllHicT'^ZeilschrilljUrWissen'
schajUiche Zoologie have had Hide influence. In England
the Quarterly Journal 0} Microscopical Science is devoted to
morphological investigations, while physiology is provided
for in other journals, as it is also in (icrmany and other
countries. In the United States the Journal oj Morphdogy,
edited by C. O. Whitman, passed through seventeen volumes
and was maintained on the highest plane of scholarship.
The fine execution of the plates and the high grade of typo-
graphical work made this journal conspicuous. Ii repre-
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RECENT TENDENCIES IN BIOLOGY 447
sents in e\ery way an enterprise of which Americans can be
justly proud. The American Journal oj Anatomy is now
filling the field left unoccupied by the cessation of the Journal
oj Morphology* In the department of experimental work
many joumaUhave sprung up, as Biomelrka, edited by Carl
Pearson, Roux's Archiv jiir E^Uivicklungs-Mcchanik, the
Journal oj Experimental Zoology recently established in the
United States, etc., etc.
Exploration of the Fossil Records.— Explorations of the
fossil records have been recently carried out on a scale never
before attempted, invobing the expenditure of large sums,
but bringing results of great importance. The American
Museum of Natural History, in New York City, has carried
on an extensive suney, which has enriched it with wonderful
collections of fossil animals. Besides explorations of the
fossil -bearing rocks of the Western States and Territories,
operations in another locality of great importance are con-
ducted in the Fayflm district of Egi'pt. The result of the
studies of these fossil animals is to make us acquainted not
only with the forms of ancient life, but with the actual line
of ancestry of manj' living animals. The advances in
this direction arc most interesting and most important.
This extensive investigation of the fossil records is one of the
present tendencies in biology.
Conctusion. — In brief, the chief tendencies in current bio-
logical researches are mainly included under the following
headings: Experimental studies in heredity, evolution, and ani-
mal behavior; more exact anatomical investigations, especially
in cytology and neurology, the promotion and dissemination
of knowledge through biological periodicals; the provision of
better facilities in specialty equipped laboratories, in the
• It is a source of gralification to biologists that— Chanks to the Wislar
Institute of Anatomy — the publication of the Journal oj Morphology is la
be conlinued.
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448 BIOLOGY AND ITS MAKERS
application of results to the benefit of mankind, and in the
investigation of the fossil records.
The atmosphere of thought engendered by (he progress of
biology is beneficial in every way. While its progress has
dealt the death-blow to many superstitions and changed
materially \iew-s regarding the universe, it is gratifying to
think that it has not been iconoclastic in its influence, but
that it has substituted something belter for that which was
taken away. It has gi\en a broader and more wholesome
basis for religion and theories of ethics; it has taught greater
respect for truth and morality. However beneficial this
progress has been in the past, who can doubt that the mission
of biology to the twentieth century will be more important
than to the ])ast, and that there will be embraced in its
progress greater benefits than any we have yet known ?
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READING LIST
The books and arliclfs rclaling In (he history of biologj-
Thosc dcsignalcd below embrace some of ihe more readilv accessible
While some altcniion has been given to selecting the best source
allempl has been made to give a comprvhensive list.
I. GENERAL REFERENCES
CuviER. Histoire des Sciences Nalurelles. 5 vols., 1841-1845. Ex-
cellent. Written from examination of Ihe original documents.
Carus. Geschichle der Zoologic, 1872. .\l30 Histoire dc la Zoologie,
18S0. A work of scholarship. Contains excellent account of the
Physiologus.
Sachs. History of Botany. iSqo. Excellent. Articles in the Botanical
CaaUe for 1895 su|)plemcnt his account by giving the more reccnl
development of botany.
White. A History of the Warfare of Science with Theology in Christen-
dom, 3 vols., igoo. Good account of Vcsalius and the overthrow of
authority in science.
Whewell. History of the Inductive Sciences, vol. II, 1863. Lacks
insight into the nature of biolog)- and the steps in its progress. Men-
tioned because so generally known.
Williams. A History of Science, 5 vols., 1904. Finely illustrated. Con-
tains many defects in ihe biological part as to the relative rank of the
founders: Vesalius diminished. Paracelsus magnified, etc. Also, the
Story of Nineteenth Century Science, 1900. Collected articles from
Harper's Magmiitr. Good portraits. I'ncrilical on biological matters,
Thomson. The Science of Life, iSqq. An excellent brief history of
biology.
Foster. Lectures on the History of Physiologi-, 1001. Fascinatingly
written. Notable tor poise and correct estimates, based on the use of
the original documents.
fjEDDFS. A Synthetic Outline of the History of Bi.4ogy. Froc. Roy. Soe.
Edinh.. 1885-1886. Good.
2r> 449
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45° READING LIST
RlCHASDSON. Disciples of -tstulapius, a vols., 1901. Collected pipers
from Tkf Asilepiad. Svmpathelic accounts of Vesalius, Malpighi,
J. HunliT, and others. Good illustrations.
LANkESTEB. The History and Scope of Zoology, in The Advancement
of Science, 189O. Good. Same article in Kncy. Brit, under the title
of Zoology.
Spencer. Principles of Biologi', 2 vols., 1866.
Hertwic. The Growth ot Biologj' in the Nineteenth Century, Ann.
Reft. SmUhson. Insl., igoo.
Buckle. History of Civilization, vol. I. second edition, 1870.
Maccilivbav. Lives of Eminent Zoologists from Aristotle to Linnieus.
Mebz. a History of European Thought in the Nineteenth CentUO", vol. II,
Scientific Thought, 190,1.
RotJTLEDCE. A Popular History of Sciencr, General and uncritical as
to biology.
HoEFER. Histoire de la Zootogie, 1873. Nirt i-ery good.
Encvclomdia Bkita.snica. Among the m<)re excellent articles are:
Biology by Hoxley; Protoplasm by Geddes; History ot Anatomy
by Turner.
Chaubers's ENcvctx>P.€DlA. Ncw Edition. Discerning articles by
Thomson on Ihe Cell -theory, by Geddes on Biology, Evolution.
NoiA'ELLE BtOCRAPHiE G£n£r,vle. G'xxl articles on the older uTJlers.
Often unreliable as u> dates.
Haeckel. The hisKirical chafjlers in The Evoluti<jn of Man, 1891, and
Anthro|K>genie, filth edition. n;o.v Ginid.
Haeckel. The History of Creation, vol. 1, 1KS4,
Hebtwii;. The General Survey of the llislorj- .i( Zoology in his Manual
of Zoology, »»i. Brief but excellent,
Parker and Hasweli., Te.\i-book of Z^wlogy, iBo;. ilislorical chapter
in vol. II.
NiCKOI-SOS. Natural Hislorv, ils Rise ar.l Progress in Britain, 1886.
Also Biology.
Pettk;re«-. Gallery of Me-lieal V
traits and biograjihiial skelihe;
Galen. Malpighi, etc.
PCSCHMAN-N. Handhuch der tlesrhichte der Medizin, 3 vols. Good for
topics in anatomy anil physiology.
Baas. The History r.f Medicine. i«8g.
Raiii,. Geschichle der Bioli^ischenTheorien seil deni Ende des Siebzchn-
ten J;ihrhundert, iqo-,.
J,*NTS, A Periocbcal devoted t.> Ihe hi-.i..ry of medicine and natural
srienre, founrled in i8i}fi.
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READING LIST 45'
MiTTElLCNC.EX ZITR GESCUICeTF. DF.K MEWZIN US'D XATURWiSSEXSCHAf-
T£N, founded Ir)OI.
-SuBCBON Gesehal's LiBHAHV. The Catalogui- shoul.i be ctin^ulli-.)
for ils many bic^raphic.il rofcrpiKes to biiilogisls. Tho Library is ts
jirciatlr rich in hidloric.il documents, as o1<l an.itoniics, physiologies,
EVOLUTION. The bibliography nl Evulmion i* Riven lielow uncier the
chapters dealing with the evnlutiiin theiiry.
II. SPECIAL REFERKNCES
Ancient nioLOGiCAi. Sciesce; Cams; Botany a/ier 1530, Sachs. Aris-
totle; Cuvier, a [lanejpric; Lowes, Aristotle— A Chapter from the History
.jf Stience, 1864. a 1 riliial study; Huxley, On some Mistakes Attributed
lo Arislolle; Maegilivray; Aristotle's History of Animals Iranslated in
Bohn's Classical Library, 1S87. Pi.iw: Magilivriiy; Thomdikc. The
Place of Magic in the Intellectual Histotj' of Kurope, 1005. thap. IlL The
Renai.ssaxce; Symonds. f^octis ln BiciLOCiCAL IIisiokv. Gcddes (see
General List).
chaptp:r II
Vesaltos: Rolh. Andreas Vesalius BruTellcnais, the edition of 1R02,
the standard source of knowledge of \'esalius and his times, contains bibli-
ography, references to his diflert-nt ]jorlraits, the resurrection bone, elc.. etc.;
Koster (see General List). Leelure 1, excellent; Richardson in Disciples of
lEsculayiius, i-ol. 1, contains picturea, his signature, etc.; Pcltigrew; White,
vol. 11, pp. 51-55; The Practitioner, i8q6, vol. 56; The Asclqriad. 1885,
vol. 11; De Huiiiani Coqwris Fabrica, editions of 1543 and 1555, 0|)era
Omnia, edited by Boerhaave. i vols., 1715. Gales: Peltigrew; Huileyin
his essay on William Harvey.
CHAPTKR III
T II, «iih ciuolation^. exfellcnl; Palton, History
V, William Harvey, a critical essay; Harvey's
iviih biography, Sydenham Society. 1847; Liie
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45» READING UST
o( Harvey by D'Arq" Power, 1898; Brooks, Harvey as Kmbryologist,
Bull. Johns Hop. Hospit., vol. VIII, 1S97, good. An Anatomical Disser-
tation upon the Movement oC the Heart and Blood in Animals, a facsimile
reproduction of the first edition of the famous De Motu Cordis et Saaguinis^
1628. Privately reproduced by Dr. Moreton in 1894. Veiy ii
CHAPTER IV
Hooke: Biography in encyclopsdias, his microscope in Carpenter, The
Microscope and lis Revelations, 8th ed., 1900.
Malpighi: Richardson, vol. II; Same article in The Atctepiad, voL X,
1893; AIti, Life and Work, in lulian, 1847, portrait; Peltigrew, vol. II;
Marcello Malpighi e I'Opera Sua, 1897, a collection of addresses at the
unveiling of Malpighi's monument at Crevolcuore, that by KoelUker ex-
cellent; Locy, Malpighi, Swaromerdani, and Leeuwenhoek, Pop. Sti. Mo.,
1901 — protrait and pictures from his works; MacCallum, J. Hop, Unnr.
Hospil. Bull. Malpighi's Wrttincs: Opera Omnia, difficult to obtain,
the Robt. Littlebury edition, Lond., 1687, contains posthumous papers and
biography; separate works not uncommon; Trait£ du Ver i Soie, Mont-
pellier, 1878, contains his life and works.
SwAUUESDAU: Life by Boerhaave in Biblia Natune, 1735; aba Bibel
der Natur, 1752; also The Book of Nature, 175S; VoD Baer, Jcdiann
Swammerdam's Leben und Verdienste um die Wissenschaft, 1864, in
Redtn, vol. I; Locy, lac. cil. — portrait.
LeeUwenhokk; Ntw biographiia! facts in Richardson, vol, I, p. 108;
same article in TJte Asckpidd. vol. II, 18S5, portrait, signature, and other
illustrations; Arcana Naturae; Selected works in Etiglish, 1758; Locy,
Pop. Sci. ilo., April, 1901,
CHAPTER V
Lvonet: The Ctntlcman's Magazine, LI\", 1789; the famous Trait*
Anal..Tiiit|uc, etc., 1750. 175J, not rare. Rkauhuhi Portrait and life in
Li! Savanii Modernes, \<. 333. Roesel: Portrait and biography in Dtr
monallUlt lierauigtgebeiun Imeclcn Bclusligung, part I\', 1761; Zeigler in
Xatur und llaus, IQ04 — nine figs. STBAUS-DtJBCKHF.lM: his monograph
on Anatomy of the Cockchafer, rather rare. TiiE Mintite Anatouists:
Straus-Dilrckheim, Dutour, Newiwrt, Leidig, etc., in Miall and Denney's
The Cockroach, 1S86.
nisro\ERV OF THE pR0TOZ0.\: Ijrcun'enhcx'k, MUUer, Ehrenberg,
Dujiirdin, etc., Kent's Manual of the Infuairia, vol. I. Errenberg:
Life by Lauc. 1S95.
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CHAPTER VI
The PevsiOLOGns: Carus, While (for titles see General List). Gesmer:
Brooks in Pop. Sci. Mo., [885 — illustrations; Cuvicr, tec. cit.; Jardinc'a
Naturalist's Librarj', vgl. \'l; Gesncr's Historia Animalium, 1551-1585.
Aldhovandi; Naturalist'sLibrary, vol. Ill; Macgilivray, foe. cA Jonston:
Macgilivray. Rav: Maegilivray; Nicholson; Memorial of, in the Ray
Society, 1846; Correspondence of, Ray Soc., 1848. Linn^us : Mac-
gilivray; Janus, vol. 8, J90J; Cuvier, toe. cil.; .Agaasiz, Essay on Classi-
fication, 185(1; Jubilee al Upsala, Science, .^pl. a6, icjo?; Caddy, Through
the Fields with LinnEcus, 18S;; The Syslema Nalurse, especially the tenth
edition, 1758. LeuckarT: Archives de Parasit,, vol. I, no. 2; Nature,
1898. Gesebal Biological Progress fbo« Linn^us to Darwin:
Geddes, Proc, Roy. Soc. Edinb., vol. 13, 1884-1886,
CHAPTER VII
Camper: Naturalist's Library, vol. VII; Vorlesungen, by his son, with
short sketch of his life, 1793; Cuvier, toe. cit.; Kleinere Schrijtea, 1 vols,
with copper plates illustrating brain and car of fishes, etc., 1782-1785.
John Hunter: The Scientific Works of, i vols., 1861 ; The Asctepiad, vol,
VIII, 1891; Ihc same article with illustrations in Richardson, loc. cit.; Pctli-
grew, loc. cit. VlcQ d'Azvh: Cuvier, loc. cit.; Huiley in Life of Owen,
p. iSq; His works in 6 vols., 1805. Cuvier: Life by Flourens; Memoirs by
Mrs. Lee, 1833; Buckle, Hisl. Civ., vol. I, p. 633 el seq.; Lettres de Geo.
CuvicrkC.M. Pall, 1788-1792, translated from the German, 1858. Cuvier's
numerous writings— The Animal Kingdom, Lemons d'Anat. Comparfc, elc.
— arereadily accessible. H. Milxe-Edwards: Biographicalskelchin^nn.
Sept. Smitlison. Inst, for 1893. Lacaze-Duthiers: Life with portraits
in Arcliivts de Zool. Expirimrnl.. vol. 10, 1902. Richard Owes: Life and
Letters, 2 vols., 1894; Clark, Old Friends at Cambridge and Elsewhere,
p. 349 ct seq. J. Fh. Mkckei: Carus, loe. cil. GEGENBAtJB: Erlebtes und
Erstrebtcs, portrait, 1901; Anat. .^nz., vol. 13, 1903; Ann. Rept. Smithson.
Inst., 1904. Cope: Osbom in Tlie Century, vol. a, 1897; Gill, Edward
Drinker Cope, Xaluralist, A Chapter in the History of Science. A m. Nalur-
atisl, 1897; Obituary notice, with portraits. Am. Naturalist, 1897; Pap.
Sci. A/o., vol. 19, 1881.
CHAPTER VIII
Bichat: Pcttigrew; Buckle, Hist. Civ., vol. I, p. 639; The Hundred
Greatest Men; Les Savants Modernfi, p. 394; TItc Ptactttiontr, vol. 56,
1S96. Koelliker: His -Autobiography, Erinnerungen aus Meinem
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Leben, 1S99, several portiuits, intcresdng; Weldon, Life and Worlu in
Nature, vol, 58, with fine portrait; Stet&ig, Ann. Sepi. Smilliiim. Iml., 1905.
SCBGi-TZE : FoTtrait aod Necrology by Schwalbe in A rckiv fUr Mikroicef^
Anal., vol. to, 1874; See further under chapter XII. VntCHow: /. Hop
t/fl(ii. CfrfuAwi, vol. XI, 1891, Celebration of Seventieth Birthday of Virchow
Addresses by Osier, Welch, and others; Jacobi, Medical Record, N. Y.
vol. XX, 1881, good; Ismel, in^nn. Stpt. Smitkion. Irut., 190a. Levdig,
Brief sketch in his Hors Zoologies, 1901. Rauon y Cajal: Portrait in'
Tenth Anniveisary of Clark Univcisitj, 1899.
CHAPTER IX •
The best brief account cf ihe Rise of Physiology in Verwom's General
Physiology, 1899. More recent German editions of the same work. His-
torical outline in Rutherford's Text-Book of Physiology, iSSo. Galen's
Pbvsiology: Verwom. Hakvey; See references under Chapter III; The
analysis of his writings by Willis in The Works of Harvey, tranalaled into
English, Sydenham Soc., 1847; See also Dr. Moreton's facsimile repro-
duction of the first edition (1616) of De Motu Cordis et Sanguinis, 1894.
Haller: Fine portrait in his Elemcnta Physiolo^e, 1758; English truts-
lalions of Ihe Elcmenta. Cbarles Bell; Pettigrew; Good summaiy in
Foster's Life of Claude Bernard, p. 38 et seq. Johannes MCllek: His
life, complete list of works, etc., in Gedachlrussrede auf Johannes MQller
by Du Bois-Rcymond, i860; EJoge by Vichow in Edinburgh Med. Joum.,
vol. 4; Pirturcof his monument in Coblcnz, Jrdm' /..!/(>. ^na/., vol. 55;
Bricfe von J. MulliT an Andn's Rctzius (1830-1857), iqoo; His lamous
Hamlbuih <k-r Physiulogie and English translations should be inspcclod.
LUDWIG : Bur(lon-S:indi'rs.m, Ludwig and Modern Physiology, Sei. Progress,
vol. V, iSi)6: The same ankhin Ann. Rfpt. Smilhson. IhsI., i8i)6. ClaOde
Beh.vard; Life by M. Foslt-r, 1899, cxtcllenl.
CH.\PTF,R X
Good general accounlot tho Riseof Embnologi'in Koelliker'sEmbrjolo-
gic, 18S0; Minol, Embryologj- and Medical Progress, Pop. Sci. Mo., vol. 60,
1906; Eyclcshymer, .'V Skcleh of the Past and Future of Embr>'ology,
.St. iMtiis Med. Rev.. 1904. HaRVEV: As Embrj-ologist, Brooks in J. Hop.
Cnh: llospit. Bull., vol. VIII. 1807. Sec abo\'e, Chaps. Ill and IX
for further n-ffrencos to Harvey. Mai.pighi: in Embrj'ology, Locy in
Pop. Sri. Mo., ii)o;— iKirtrait and selcctcii sketches from his embryological
irealiscs. Wcii.Fr: Wheck-r, Wolff and the Theoria Generalionis, in
W(.jrU Holl Bi.jlogical LcLiurcs, i8c;8; Kirfhoff in Jcnaisdte Zrilschr.,
;dbyGOOglC
READING LIST 455
vol. 4, 1868; Waldeyer, Fcslrede in Siubr. d. K. Preus. Akad. d. Wissen-
schaft., 1904; Haeckel m Evoiuiion of Man, vol. I, 1891. Bonnet and
Pbe-deuneation; Whitman, Bonnci's Theory of Evolution, also Evolution
and Epigenesis, both in Woods Moll Biological Lectures, 1S95. VON
Baer: Lcben und Schriftrn. his autobiography {1864), 2d edition, 18S6;
Life by Steida, 1886; Obituary, Proc. Roy. Soc., 1878; Waldeyer in AUg.
Witn. Med. ZIg., 1877; Nature, vol. 15; Life by Slolile, 1897; Haeckel,
loc. fit., vol. I; Locy, V. Baer and the Rise of Embryology, Pap. Sci. Mo.,
1905; Fine portrait as young man in Harper's Mag. for 1899; Rev. Sciei^.,
1879. KowALEVSKV: Lankesler in Nature, vol. 66, 1902; Portrait and
biog. in Ann. Mm. Hist. Nat. Marseille, vol. 8, 1903. Balfour: M.
Foster in Nature, vol. 19, 1882; Also Life with portrait in the Memorial
Edition of Balfour's Works; Waldeyer in Arch. /. Mik. Anal., vol. ai, 1881;
Osbom Recollections, with portrait, Science, vol. 2, 1883. His: Mall in
Am. Journ. Anal., vol. 4, 1905; Biography in Anal, Ans., vol. 26, 1904.
CHAPTER XI
The Cetl-Doctrine byTyson. 1878. The Cell-Tbeory, Huxley, Mtdtco-
ekir. Review, 1853, also in Scientific Memoirs, vol. I, 1898; The Modem
Cell-Theory, M'Kendrick. Proc. Phil. Soc. Glasgow, vol. XIX, 1887; The
Cell-Theory. Past and Present, Turner, Nature, vol. 43, 1890; The Ccll-
Doctrinc, Burnett, Trnnj. /Im. Med. Assn., vo\. VI, 1853; First illustration
of cells in Rob'l Hookc's Micrographia. i66s, 1780, etc.; The Cell in De-
velopment and Inheritance, Wilson, 1896; Article Cell, in Chambers's (New)
Cyclopedia, by Thomson. SchleIden; Sketch of, Fop. Sci. Mo., vol.
33, 1882-1883; Sachs' Hist, of Botany iSgo; Translation of his original
paper of 1838 (l"el>er Phytogenesis) — illustrations — S)-dcnham Soc, 1874.
Schwann: Life, Pop. Sei. Wo., vol. 37, 1900; Sa \'ic et Ses Travaui,
FrWMcq, 1884; Nachruf, Henic, Archh f. Mik. Anal., vol. 71, 1881;
Lankesler, Nature, vol. XXV, 1882; The Praclilioner, vol. 41), 1897; The
Catholic World, vol. 71, 1900. Translation of his tonlribulion of 1839
(Mikroscopische L'ntersuchungcn uetier die I'ebercinstimmung in der Struc-
tur und dem Wachstum der Thiere und Pflanzen), Sydenham Soc, [S47.
CHAPTER XII
On the Physical Basis of Life, Huxley, 186S; Reprint in Methods and
Results, 1894. Article Protoplasm in Ency. Brit, by Geddes. Dujabdin:
Notice Biographique, with portraits and other illustrations, Joubin, Archives
ie Parasilot., vol. 4, 1901 ; portrait of Dujardin hitherto unpublished. Du-
jardin's original description of Sarcodc, Ann. des Sci. Nat. (Bolanigue),
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vol. 4, p. 367, 1835. Von Mohl: Sachs" History of Botany, iSgo. Trans-
lation of his researches, Sydenham Soc, 1847. Cohn: Blatter der Er-
innerung, i8i)8, with ponrail. ScmJLTZE: Necrology, by Schwalbe in
Arckiv f. Mik. Atial., vol. 10, 1874, with portrait. Schuluc's paper found-
ing the protoplasm doctrine in Arthiv /. Anal, and Phys., 1861, entitled
LTeber MuskelkCrperchcn und das was man eine Zcllc zu nennen habe.
CHAPTER XIII
Spontaneous Generation: Tymlall, Pop. Sci. Mo., vol. u, 1878;
Also in Floating Matter of the Air, 1881 ; J. C, Dallon in N. V. Mtd. Jour«.,
1871; Dunsler, good account in Proc. Ann Arbor Sci. Assn.. 1876; Hun-
ley, Rtpl. Bril. Ann. jor Adv. Sci., 1870, republished in many journals,
reprint in Scicntif. Memoirs, vol. IV, 1901. Redi; Works in g vols., 1809-
1811. with life and letters and portraits; Good biographical sketch in
Archives dt Parasilol.,\o\.\, i8q8; Reiii's Espericnze Intorno Alia Gi-ncra-
zionc Drgl' I nsctli. i plates, first edition, 1668, in Florence, 40; reprinted
at various dates, not uncommon. Spallanzani: Foster, Lccts. on Physiol.;
Huxley, ioc. cil.; Dunsler./oc. eil.; L'Abbato Spallanzani, by Pavesi, 1901,
portrait. Pouchet: His treatise of historical importance — HStSrogftuc; ou
TrailidelaG*n*rationSponlanfr, l)aB*surdesNouvcllcsE]q)ttences, 1859,
Pasteur: Life by Reni^ \'allery-Raclol, 2 vols., igoj; Perqr and G.
FrankUnd, 1901; Pasteur at Home, illustrated, Tarbell in MeCluri's
Mag., vol. I, 1893; Also McClure's, vol. 19, 190J, review of Vallerj--
Radot's Life of Pasteur; Nature, vol. 51, 1895; Lis SavatUt Modernts,
p. 316; Life by his son-in-law, translated by Lady Hamilton, 1S86;
Sketches of Pasteur, very numerous. Bacteriolocy: Woodhcad, Bacteria
«nd their Products, 1S91; Fraenkel, Teil-Book of Bactcriolog)-, 1891;
Pnidden, The Story of Bacteria, etc., 1891. Gebu-Theobv of Disease:
Crookshank'a Bacteriology, 3d edition, i8go. Koch: Pap. Sci. Mo., vol.
36, 1889; Review o/ Reviews, vol. 1, 1890; Sketches and references to
his discoveries numerous. Lister: Pop. Sci. Mo., vol. 53, 1898; Reviev
af Reviews, vol. 14, 1896; celebration of Lister's 80th birthday. Fop. Sci.
Mo., June, 1907; Janus, vol. 5, 1900. The New Microbe Inoculation of
Wright, Harper's Mag., July, 1907,
CHAPTER XIV
The History and Theory of Heredity, J. A. Thomson, Proe. Roy. Soc
EdiHb., vol. XVI, 1889; Chapter On Heredity in Thomson's Science of
Life, 1899; also in hia Study of .\nimal Life, iSgi. Mendel: Mendel's
Principles of Heredity, with translations of his original papers on hybrid)-
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zation, Bateson, 1901; Mendel's Versuchc Uber Pflatizenhybridcn, two
papers (1865 and i86q), e<IUed by Tschermak, 1901; Ami. Repl. Smilhson.
Intl., 1901-190J; Po/i, Sci. Mo., vol. 63, 1903; vol. 63. 1904; Scitnce, vol.
93. '903- Galtok: Pop. Sci. Mo., vol. 29, 1886; Salurr, vol. 70. 1907:
Gallon's Natural Inhcrilance, 1889. Weisuans: Brief Autobiography,
with portrait, in Thi Lamp. vol. i6, 1903; Siilomonscn, Bcricht Uber die
Feicr des 70 Geburlslages von August W'eismann, 1904; Weismann's The
Germ-Plasm, 1893, and The Evolution Theorj- 1904.
CHAPTER XV
History of Geology and Paleontology, Zittel, 1901. The Founders of
Geology, Gcikie, 2d edition, 1905. History and Methods of Palconto-
logical Discovery, Marsh, Proceed. Am. Adv. Sci., 1879. Same article in
Pop. Sci. Mo,, vol. 16, 1879-1880. The Rise and Progress of Paleontology,
Huxley, Pop. Sci. Mo., vol. ao, 1881. LvELL: Charles Lycll and Modern
Geology, Bonney, 189;;; Sketch in Pop. .?ci. Ma., vol. I, i8;i, also vol.
10, 1881-1882. Owen: Lite of, by his grandson, 2 vols., 1894; See also
above under Chapter \'ll. AcASSlz: Life and Correspondence, bj- his
wife, 2 vols., 1885; Life, letters and works, Marcuu, 3 vols., 1896: What
wo Owe lo Agassiz, Wilder, Pop. Sci. Mo., July, 190;; Agassiz at Penikese,
Am. Nat., 1S98. Cope: A Great Naturalist, Osborn in The Century. 1897;
Sec above, under Chapter VII, for further references. MaRSB: Pop. Sci. Mo.,
vol. 13, 1878; Sketches of. Nature, vo!. 59, 1898-99; Science, vol. 9, 1899;
Am. J. Sci., vol. 157, 1899. Zittel: Biographical .Sketch with portrait,
Schucherl, Ann. Rept. Smilhson. Inst., 1903-1904. Osliom, Papers on
Paleonlological Discovery in Science from 1899 onward. The Fa>ilm
Expedition of the Am. Museum of Nal. History, Science, March 29, 1907.
Note. Since the four succeeding chapters deal with the Evolution
Theory, it may be worth while lo make a few general comments on the liter-
ature pertaining to Oi^anic Evolution. The number of books and articles
is very extensive, and I have undertaken to sift from the great number a
limited list of the more meritorious. Owing to the prevalent vaguenes-s
regarding evolution theories, one is likely to read only about Daruin and
Darwinism. This should lie avoided by reading as a minimum some good
reference on Lamarck, Weismann, and De \'ries, as well as on Darwin.
It is well enough to begin with Darwin's Theori-, but it is not best to take
his Origin of Species as the first book. To do (his is to place oneself fifty
years in the past. The evidences of Organic Evolution have greatly multi-
plied since 1859, and a better conception ot Darwin's Theory' can be ob-
tained by reading first Romanes's Darwin and After Darwin, vol. I . This to
be followed by Wallace's Darwinism, and, thereafter, the Origin of Species
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may be taken up. These will give a good conception of Darwin's Theory,
and they should be followed hy reading in the order named: Packard's
Lamarck; Wcismann's The Evolution Theory; and Dc Vrics's The Origin
of Species and \'arieiies by Mutation, Simultaneously one may read with
great profit Osborn's From the Greeks lo Darwin.
CH.\PTER XVI
General: Romanes, Darviin and After Damin, iSgi, vol. I, chaps.
I-V; Same author, The Scientific Evidences of Organic Evolution; Weis-
mann Introduction lo the Evolution Theory, 1904; Osborn, AlleundNeuc
Problemcder Phylogenese, Ergehniue dcr Anal. u. Entu-ickeI.,\o\. Ill, 1893;
Ziegler, Ucber den derzeiligen Stand der Descend cnzlehre in derZoologie,
igo2; Jordan and Kellogg, Evolution and Animal Life, 1907, chaps. I and
XIV. EvoLtrriONARY Series — Sheli.s: Romances, loe. cil.; Hyatt. Trans-
formations of PlanorbisalSleinheim,Pf-i«;.ilin..4li.^rfi'.S£i.,voLi9, 1B80.
Hohse: Lucas, The Ancestry of the Horse, McClure't Mag., Oct., iQOo;
Huxley, Three Lectures on Evolution, in Amer. Addresses. Eubrvolocy —
Recapitulation Theory: Marshall, Biolog. Lectures and Addresses,
1897; Vertebrate Embrjology, 1893; Haeckcl, Evolution of Man, 1891.
Primitive Man: Osljorn, Discovery of a Supposed Primitive Race of
Men in Nebraska, Cenlury Mag., Jan., 1907; Haeckcl, The Last Link,
1898. Huxley, Man's Place in Nature, collected essays, 1900; published
in many forms. Romanes, Mental Evolution in Man and Animals.
CHAPTER XVII
Lauaeck: Packard, Lamarck, the Founder of Evolution, His Life
and Work, with Translations of his Writings on Organic Evolution, 1901;
Lamarck's Philosophie Zoologiquc, 1S09. Recherches sur 1 'Organisation
des coTfK vivans, 1801, contains an early, not however the first statement of
Lamarck's views. For ihc first [lublished account of Lamarck's theory
see the introduction to his Syst^me des .Animaux sans Vcrtibres, 1801.
Neo-Lamarckism: Packard, loe. cit.; also in the Introduction to the
Standard Natural History, 18S5; Silencer. The Principles of Biology, 1866
—based on the Lamarckian principle. Cope, The Origin of Genera, 1866;
Origin of ihc I'itlcsl, 1887; Primarj' Factors <jf Organic Evolution, 1S96,
the hitler a very notable lx>ok. Hyatt. Jurassic .Ammonites, Proced. Beit.
.Sci. S'al. Ilisl.', i»u- OsU^m, Trans. Am. Phil. .Sot., vo]. 16,1890. Eigen-
mann, The Eyes of the Blind Vertebrates of North America, Archiv /.
linlTi-Uieliingsmeirlianil!, vol. 8, 1S9I).
Darwin's Theory (For biographical references lo Darwin sec below
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under Chapler XIX) : Wallace, Darwinism, 1889; Romanes, Darwin
and After Darwin, vol. I, 1893; Melcalt, An Outline of the Theory of
Organic Evolution, 1904, good for illustrations. Colok; Poulton, The
Colors of Animals; Chaplcrs in Weismann's The Evolution Theory, 1904.
Mimichy: Weismann, iK. eif. Sexual Selection: Darwin, The Descent
of Man, new ed., 1891. Inadequacy of Nat. Selection: Spencer, The
Inadequacy of Natural Selection, 1893; Morgan, Evolution and Adapta-
tion, 1903. Kellogg, Darwinism To-day, 190;, contains a good account
s against Daminism.
CHAPTER XVIII
Weismann's The E\-oIution Theory, translated by J. A. and Margaret
Thomson, i vols., 1904, contains the best statement of Weismann's views.
It is remarkably clear in its exposition of a complicated theory. The
Germ-Plasm, 1893; Romanes's An Examination of Weismannism, 1893.
Inhepitance of Acquired Cuaracters: Weismann's discussion, loc. cU.,
vol. II, very good. Romanes's Darwin and After Darwin, vol. II. Per-
sonality OF Weismans: Sketch and brief autobiography, in Tlie Lamp,
vol, i6, 1903, portrait; Solomonsen, Bericht flbcr die Fcier dcs 70 Gebuns-
tages von August Weismann, 190;, 3 portraits.
Mutatiom-Theorv of De \'eies: Die Mutations-Thcorie, looi;
Species and Varieties, Iheir Origin by Mutation, 1905; Morgan, Evolution
and Adaptation, 1903, gives a good statement of the Mutati()n Theory,
which is favored by the author; Whitman, The Problem of the Origin of
Species. Congress 0} Arts and ScitHCC, Universal Exposition, St. Louis, 1904;
Davenport, Evolution without Mutation, Joum. Exp. Zool., April, 1905,
CHAPTER XIX
For early phases of Evolutionary thought consult Osborn, From the
Greeks to Darwin, 1894, and CUnld, Pioneers of Evolution, 1897. Suarez
AND THE Doctrine of Special Creation; Huxley, in Mr. Darwin's
Critics, Cant. Rev., p. 187, re])rinled in Critiijucs and Addresses, 1873.
Buffon: In Packard's Life o( Lamarck, chapter 13. E. Darwin:
Krause's Life of E. Darwin translated into English, 1879: Packard, he.
cil. Goethe: Die Idee der Pflanzenmctamor[)hose bei Wolff und bei
Goethe, Kirchoif, 1867; Goethe's Die Metamorphose der Pflanzen, 1790.
Oken: His Elements of Physiophilosophy, Ray Roc., 1847. Cuiier and
St. HlLAlkE: Porrier, I,a Philosophic Zoologique avant Darwin, t8S4;
O.'iborn, loc. cil. Dakuis and Wallace: The original communications of
Darwin and Wallace, 'vith a letter of Iransmissal signed by Hooker and Lyell,
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published in the Tratts. Linnaan Soc. for 1858, were reprinted in the Fop.
Sci. Mo., vol. 60. 1901. Dahwin: Personality and biography (For refer-
ences to his theory sec under Chapter XVII); Life and letters by his son
3 vok., 1887, new ed., i8g6; More Letters of Charles Darwin, 2 vols.
1903; Chapter in Marshall's Lectures on the Darn'inian Theorj-; I>arwin
Naturahst's Voyage around the World, 1880; Gould. Biographical Clinics
for Darwin's illness due to eye-strain; Poulton, Chas. Darwin and the
Th-ory of Natural Sclertion, 1896. Wallace: My Lite, a vols., iq
The Critic, Oct., 11)05. HlDtLEV: Lite and Letters by his wn, iqoi; ;
merous sketches at the time of his death, 18Q5, in ,\alurf, Xinelrtitlh C
lury. Pop. Sci. Ma., etc., etc. Haeckel: His Life and Work by Bolsche,
CHAPTER XX
It is deemed best to omit the references to Technical papers U[ion which
the summaries of recent tendencies are based. Morgan's Experimental
Zoology, 1907. Jennings, Behavi()r ot the Lower Organisms, 1906. Mos-
quitoes and other insects in connection with the transmission of disease,
see Kolsom, Entomologj-, 1906, chapter IX, p. 299. IliOLOGiCAL Lab-
Oratories: Dean. The Marine Biological Stations ot Euro[ie, Ann. Repl.
SmilhsoH. Insl., 1S94; Marine Biol<^. Station at Naples, Harper's Mag.,
1901: The Cenlury, vol. 10 (Emily Nunn Whitman); Williams, A
History ot Science, vo\. V, chapter V, 1904; Am. Nat., vol. 31, 1897;
Pap. Sci. Ma., vol. 54, 181)9; '*'^., vol. 59, 1901. Woods Holl Station — A
Marine University, Ana. Repl. Smiihson. Insl., igoi.
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INDEX
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Agassiz. essay on classifi ration, 1,17;
agrecn'.cnt of emhr\'olof^cal stages
and (he fossil rcrord, 334; fossil
fishes, 334; portrait. 334
Batloria. distovery of, 176; diseasc-
protlucing, 300; and antiseptic
surgery, 301; nilrifying, of ihe
soil, 303 ■
teriolrigy, dcvelopnteni of, 276
r, \'on, and ihc rise of cmtiryol-
■236; his Ereat (lassie
m6
Anatomical sketches, the earliest, 32;
from \'esalius, 31, 33
Anatomical studies, recent tenden-
cies nf, 44>
Anatnmy, of AKstolIe, 23; l>egin-
nings of, 13; earliesi known ill us
iraliont, 32; of Oali-n, 24; of the
Middle Agfs, 14; comiiarative,
rise of, 141-16^; of insects,
Dufour, loi); Lyonet, gi; Mal-
jiiRhi, 63; Newport, too; Reau-
mur, 06; Rocsel, rj6; Slraus-
DUrckhcim, i)6; Swammerdam,
7°- 73-77; minute, pnigress of,
8i)-i04: of plants. Grew, 56;
Malpighi, 66
, return to the scicn
il liehavior, studies of, ;
il kingdom of CuvicT, jj
as, St. Thomas, on en
Arisioile, 9-13; books of, 1.
of, 13: estimate of. 10. <
knowk-dRC of animals,
founder of natural hislor;
■clupmi
.of ai
c of.
iS; makes embo'ol-
op' (omparafive, 120; and Pan-
der, 2i8; [leriod in cmbryolon)-,
214-226: imnrails, »(6, 117; his
rank in embmilog)', 120; his es-
pecial senile. 217: skelehes frotn
his embryoloRical treatise. 121
Balfour, maslerly «-ork of, 226; his
fM-riod in cmtirj-olo);)', 226-232;
[>ersonatily, 228; jKirtrait. itj;
tragic fate, 228; university career.
Bell, Charles, discoveries on Ihe 1
vous sysn-in, 183; portrait, 18
Bcrengarius, 36
Bernard, Claude, in physiolog}-, 1
167: iK-rsona
d industn-,
esulls of hi
lily. 168; phe-
168; portrait.
5 work, 17c;
mlr^iidalur
■ssesof. 170
c of Linna'us.
Arrest of ini|uir>-, effect o
AuKUSline, .Si., on crealio
Aulhoritv declared the
knowli^ge. 18
il perindirals, 446
itmospfiere cngenderecl by,
dbjGoogle
464
44^; from Linnicus to Darwin,
138-140
Biulogy. defined, 4; domain cif, 4, 5
cpoths of, lo; progress of, 3, 5
appliL-d, 443
Boerhaave, quoted, 71, 71; and
Linnieus, 112
Biiis-Reymond, Du, 189; portrait,
.89
Bones, fossil, J2Z, 324
BonncI, and emboltcnicnl, 208; op-
position to Wolff, 211; iHirlrait,
Books, the nolalilc, of l>io1ogi', 43;
Brown, Robert, disrovcra the nu-
cleus iti plant-cells, 243
Buckland, 314
Buckle, on Bich.il, 166. 16;
BtUIon, i2c>,4ii; [wjrtrail, 412; |k)-
Caisalpinus, on ihi
Caial, Ramon y.
Calkins, on proioz
" mpiT, analomi.
ork of. I
CariKnler, ijuoli'd, 170
Car|ii, the analimiisl, 26
Castle, cxjK'rimenls on inheritani
Cataslrophisni. ihrorv of, Cuvii
32(); Lyellon, 331
Cell, definition of, 256; diagram
»57; rarliesi known pictures
238. 23CJ; in hcrtdily, 257
Cell-lineage, 234. 442
Ccll-th™r>-, ann..unccmcnl of, 2.
effect
ilogy.
founded hv Schleiden and
Schwiinn. 242; Schleiden 's ciin-
tribulicm, 247; Schwann's trea-
tise, 248; m,Kiiricalions of, 250;
vague foreshadow! nRS of, 237
Chilli, studies un regulation, 440
Chnimiisomc.*, 134, 3t!
Circulation of the blood. Hart'ev,
46, 47; Servetus, .so; Oilumliu",
50; Cisalpinus, 50; in the capil-
laries, 84, Leeuuenhock'.s skeldi
of, 83; VesalLus on, with illuslra-
Color, in evolution, 386
Columbus, on the circulation, 50
Comparative anatomy, rise of, 141-
165; becomes experimental, 165
Cope, in comparative anatomy, 161;;
portrait, 336; important work in
pala-onlology, 337, 437
Creation, Aquinas on, 409; St.
Augustine on, 408; special, 410;
evolution the method of, 348
Cmner, birth and early education,
149; and calastrophism, 326;
comprehensiveness of mind, 154;
lurrelation ot parts, 133; debate
with St. Hilaire, 416; domestic
life, T35; forerunners of, 143;
founds comparative anatomy. 154;
founder of vertebrate paliBontol-
ogy.325; his four branches of the
animal kingdom, 137; goes to
PariK. 151; life at the seashore,
150: opposition to Lamarck, 414;
[lortrails, 152, i^y, phj-siognomy,
152; and the rise of comparatii'e
anutomv. 141-156; shortcomings
of, 156;' successors of, is6; lype-
Ihc-ofy of, 133
D
DarH'in, Charles, his account of the
way his thcon- arose, 4*7; factor*
of et-olution. 180; haiiits of work,
421^; home life, 423: at Down,
426; ill health, 426; naturalist on
Xhe Braglf, ^ly, natural stlec lion,
383; opens note IxKik on the origin
of species, 426; )iersonalily, 421;
Jiortraits, 381, 423; |iaraUelism in
thought with Wallace, 427: pub-
lication of the Origin of Sprcies,
4211; his other n'orks, 391, 421);
theor}' of jMingcnesis, 306; varia-
tion in nature, 383; the original
drafts of his theory sent by
Hooker and Lyell to the IJnna^an
Society, 420-423; working hours,
426; summary- of his iheorv', 405
Daru'in, Erasmus, 413; portrait,
Darwinism and Lamarckism eon-
I the deposit of fossils.
dbjGoogle
De Vries, mutation theory of, 402;
portrait, 403; summary, 406
Dufout, Lton, on insect anatomy,
Dujardin, 250, 261; discovers sar-
fodt. 250. 266; portrait, 265;
writings, 164
Edwards, H, Milne-, 157; portrait,
■57
Ehronbei^, 106, 107; portrait, 108
Embryological record, inler|ircla(ion
Embryology, Von Baer and the rise
of, IQ4-236; cxperimenlal, 232;
pil-tlefts and other rudimentary
organs in embrj-os, 361; theoret-
ical. 23s
Epochs in biological history, 20
Evolution, doctrine of, generalities
regarding, 345; eontrovcreies rv-
garding the factors, 346, 369; fac-
torsof,36S; effect on em brj'ologj-,
225: on paljconlology, 332; na-
ture of the <|ucstiun regarding,
348; a historical (jucstion, 348;
the historical method in, 348;
sweep of, 366; one of the greatest
acijuisitions of human knowledge,
366; predictions verified, 367;
theories of, 36^; Lamarck, 361);
Darwin, 386; Weismann, 392;
De Vrics, 403; summary of evo-
lution theories, 404; vagueness
regarding, 346
Evolutionary series, 331; shells, 351;
hors<
- 354
Evolutionary thought, rise of, 407-
433; viewsofcertainfathcrsof the
church, 408
Experimental ohser\'ation, intro-
(luccd by Harvey, 3<)-53
Experimental work in biolog;-, 439
EX 465
Haven, 355; in New York, 355;
man, 340, 364; Neanderthal skull,
365; ape^like man, 364
Fossil remaitis an index to past his-
torj-, 32c,
Fossils, arrangement in strata, 338;
ascribed to the flood, 313; their
comparison viilh living animals,
324; from the Fayllm district, 341;
method of collecting, 34a; nature
of, 322; determination of, by
Cuvicr, 31?; Da Vinci, 322;
Stcno, 322; strange views regard-
ing, 320
Galen, 23, 180; portrait, 25
Gallon, law of ancestral inheritance,
318; portrait, 317
Geer, De, on insects, gj
Gcgenbaur, 163; portrait, 164
Generation, Wolffs theori- of, 210
Germ-cells, organization of, 210
Genn-Iaycrs, 218
Germ-plasm, continuity of, 393;
complexity of, 3g5; the hereditary
aulistance, 311; union of germ-
plasms the source of variations,
Germ-theory of disease, 21)3
Germinal contintiity, 324, 308; doc-
trine of, 224, 311, 393
Germinal elements, 305
Germinal selection, 397
Germinal substance, 310
Gesner, iii; personality, 113; por-
trait, 114; natural history of, 113
Gill-clefts in embryos, 361
Grew, work of, 56
Fabrica, of Vesalius, 30
Fabricius, Harvey's teacher,
portrait, 43
Factors of evolution, 369
Fallopius, 361 portrait, 37
Haeckcl, 431; portrait, 43=
Haller, til>cr-theor\', 242: opposition
to WoIfT, J 1 1 ; in physiology, 181 ;
piirtrail, 182
Harvey, and experimental observa-
tion, 39-33; his argument for the
circulati()n, 51; discovery of the
circulation, 47; his great classic,
46; education, 40 ; in embryology,
198; embryological treatise, igq,
20o; frontispiece from his genera-
tion of animals (1651). 201; in-
fluence of, 52; introduces expcr-
dbjGoogle
is teacher, 43; Klrii
466 IM
imental method, 47: al Padua. 41;
period in physiology, iSo; [>rr-
sonal appearance and qualities,
4a, 44, 4;; porlrail, 44; prtii-
eccssors of, 48; iiueslion as lo
his originality, 46; his ti
writings, 45 '
Heredity. 305: a cellular study. 257;
according to Darwin. ,107; Weis-
mann, 30c); application of stalls-
lies to, 314; inheritance of ac-
quired characters. 314; steps in
advance of knowledge of, 308
HertM'ig, Oskar, portrait, 231; ser-
vice in emhryology, 232; Rich-
ard, qtioted. 115
Hilaire, Si., portrait, 416; see !^1.
His, WUhelm, 13); iKinraii, 133
Histology, birlh of, 166-178; Bichal
lis founder, 170; normal and
pathological, 172; text-books of,
177
Hooke, Rolierl. 55; his microsc.ijie
illustrated, 55
H<>..ker, letter on the work of Dar-
win and Wallace, 420-431
Horse, evolution of, 354
Human anceslrv, links in, 364. jfi^
Human l-.dy. evolution of,' 3(13
Human fosals. 340, 364
Hunter, John, 144; |H>rtmit, 145
. -130
I
Inheritance, alternative, Mendi
3,6^ amestnil, 3.8; Darvvin
311-313; nature of. 30;
Inhei
I.am
In.
3'lH
, 377^ W-^is-
of. 1;
if, Duf.m
Mal[iighi, 63I illustratio
Newport, looi Lej-dig. loi,
Dlirtkheim, 06; Swamni
70, 7i; illustration, 76, ll
Jennings, on a
Koch, Robert, discoveries of, 3
portrait, 301
Koelliker. in embryology, 224;
histolog)*, 171; portrait, 173
Kowalevsky. in enibrj-ology, a
]>ortrait. 225
Lacazc-Duthiers, 158; portrait, 159
I-aniarck, changes from botany lo
7cK)lr]gy. 372; compared with
Cuvier. 327; education. 371; lirsl
announcement of his evolulionary
first use of a genealogical tree, 131;
founds in(-ertel)ratc pal.xonlolog>-,
32(1; on heredity, 377; laws of
eiiilution. 376; militaiy experi-
ence, 37c; opposition to, 414;
Ph:l..s..phie Zoologique, 375 ; \<ot-
"■ajt, 37.i; T">^ili"n in science. 132;
salient points in his theorv, 378;
hislheon-of cnilution. i;.;; com-
lared with that of Darwir, 3,10.
3rii; time and favorable condi-
Ui'uwenhcje'k, 77-87; new bio-
gtaphiial facts, 78; rapiUarv
circulation. S4. K5, sketch of. 83;
conipariwin with Malpighi and
Swammcrdam, 87; discover)- of
the prolo»ia. 105; olhtr discov-
eries, 8^; and hiilokigy, 178; his
microscopes, 81; pictures of, 82,
83; occujKilion of, 78; portrait,
7(,; scientific letters, 83; Ihccreti-
cal riews. 86
r^c'ibnit/,, 208
I,ci.lyiniiala'ontolog)', 337
J^esscr's thmlogj- of insects, 91
l>-uikan, 1361 [xirtrait, 136
loj; in histologj-, 175; portrait,
I,ii
ivslem, reform of, 130-138
118-130; liinomial noinen-
127: his especial service,
s idea of sjiecies, 128, 121);
dbjGoogle
influence on natural history, 115;
personal apjifarantc, 125; prr-
sunal hi&tor^'. 119; ]x>rtrait, 114;
het;>ed by his fianrec, 120; relum
10 Sweden, 113; and the rise ot
natural histon-, 100-ijo; Ihc Sys-
(ema Natura:, 121, 115, 1 17; pro-
fessor in L'psala, 123; celebration
of two hundredth anniversarj' of
his birth, 124; as unii-craity lec-
turer, 123; wide recognition, 122;
summary on. 120-1.^0
Lister, Sir Joseph, and antiseptic
surgeri', 302; portrait, 302
Loeb, 134: on artificial ferlilizaticn,
441; on regulation, 440
Ludwig, in phj-siology, 160; jmr-
Lyell, c[Kich-making work in geol-
ogy. 330 i
on Dar
Wallace, 420-422; portrait, 331
Lyonet, 89; portrait and personal-
ity. 90; great monograph on in-
sect anatomy, gi; illustrations
from, 92, 03, 94, 95; eitraordi-
iMry quality of his sketches, 92
Malpighi, 58-67; activity in re-
search, 61; anatomv of plants, 66;
anatomy of the silkworm, 63;
compared with Leeuwenhock and
Rwammerdam, 87; work in em-
brj-ologj, 66, 202 ; rank as embry.
ologisl, 105; honors at home and
abroad, 6[; personal appearance,
58; portraits, 59, 204; sketches
from his cmbrjological treatises,
103; andlhetheory of pre-dchnea-
lion, 203
Man. anti(|uily of, 364; evolution of,
363; fossil, 340. 364
Mar^, O. C, portrait, 33;
Meckel, J. Fr., 162; portrait, 162
Men, of biology, 7, 8; the foremost,
437; of science, 7
Mendel, 315; alternative inherilance,
316; law of, 315; purity of ihe
n-cells.
port.
rank of Mendel's discoverv, 316,
Microsrojie, Hookc's, Fig. of. 3;;
Lfcllivcnlioi>k\s, 81, Fig';, of, 82,H3
Microscopic otiscrvali<m, introduc-
tion of, 54; of Hooke, 55; Grew.
467
Milne-Ed wards, portrait, 157
Mimicrv, 387
Mnhl, Von. 268; portrait, 26-)
Miiller, Fritz, 230; O. Fr., 106
MUUcr, Johannes, as anatomist, 163;
general influence, 18;; influence
on physiology, 185; as a teacher,
185; his period in phvsiolt^y, 1S4;
|>e^nalily, 183; [iorlrait. 187;
physiology after MUller, 188
N'Sgeli, portrait, J68
Naples, biological station at, 44*
picture of, 44S
Natural hislor*-, of Gesner, 111, 1 1 ■
114; of Ray, 11J-118; of I.ir
[30; sacred, 110; ris
ilific.
-130
Natural selection, 383; discovery of,
427; Darwin and Wallaceon, 429;
extension of, by WeJsmann, 397;
illustrations of, 384; inadequacy
of, 389
Xalure, continuity of, 367; return
to, 19; renewal of observation, 19
Naluruhilosophie, school of, 160
Neanderthal skuil, 365
Needham, experiments on sjKinta-
neous generation, 181
NeO'I.amarckism, 380
Nomenclature of biology, 126, 127
Nucleus, discover}- of, by Brown,
243; diWsion of',, 256, 313
Observation, arrest of, 17; renew
of, 19: in anatomy. 26; and e
pcrimcnt the metiiod of scienr
2 J. .!'J
Oken, on cells. »4i; jionraii, 160
Omne vi\-uni ex ovo, 200
Omnis cellula c cellula. 301,
Organic evolution, doctrine of, iji
225; theories of, '368-4o6;'rise.
;dbyGOOglC
468 INDEX
evolutionary thought, 407--133i
sweep of ihc doctrine of, ,^66 Ralhki
Oabom, qumed, lO, 364, .
palasonlulogv, 3J')
Paliontolog)-, Cuvier founds i-crle-
brale. ,115; of the Fayflm dislrirl,
,141; Lamarck founder of invertc-
biale, ,ti6i Agassis, 331: Co|>e,
337; Huxky, ,1,15; I.yell. ,130;
ibryology. i?j
Kay, John, 115; portrait, 116: and
Reaumur, i/b; jxirtrait. 9S
Recapitulation theory, 130
Recent tendencies, in biologj*, 437
ml)r>-olog>-, 131
I the
Pander, gcpm-lnyer theorj', 118
Pangenesis, Darnin's theor>- of, 306
Pasleur, on fi-rmcntation, 204:
spontaneous generation. 2X8; in-
orulalion for hydropholiia, 201);
int'eslignlion u( niicrolx-i, 2i;8:
personality, 20A; |>ortrail, 21J5;
his supreme service, nii)', venera-
tion of, »D4
Pasleur Instil ulr, foundation of, nil);
Pearson. Karl, and aneeslral inher-
ilami-, siK
Phitosophie Analomi<[ue of St. Hi-
Philosophie Z(Hilogir|Ue of Lamarck.
375
Physu>logus. the sacred natural his-
Fhysiology. of (he am ii-nl». 171);
Sarrode and jirofoplasm. 27.
Scala Natura;, 131
Scale of being, .31
Sthlciden. 243; oinlribulioi
rcU-lheor)-. 248; personal!
246
Schultze, Max, eslalilishes the proto-
plasm doctrine, 272; in histology-.
171; portrait, 273
Schulze, Franz, on sjiontaneous gen-
eralion, 284
Schwann, and the cell-theor>-, 142.
344, »48, *4<); in hislolo^-, 171;
and 5]iiinlaneous generation. 284
Science, of the ancients, return 10.
iiz; cmdilions under which it
de\'eli>|H.'d. 8; liiologital. 4
Svrvctus. on circulation of Ihe bkxMl.
rise of, 170-11J4; [K-rirxl of llar-
Sevcrinas, in rompara
live anatomy.
wy, 180; of Haller, 181; of J.
143; portrait, 143
MUller, 184: great influence of
Sexual scleclion, 388
Mtiller, 18s; after Miiller, i8g
>^- 353
Pitheranihrcipus erectus, 341, 360
Siebold.Von, 134. 135;
; portrait, 135
Pliny, jvinrait, 16
Silkw-orm, Malpighi 01
1, 63; Pasteur
on. 2<w
See Pre-<lelineali
of. 26i>; its {lowers. 26a
Pn>loz«u, discovery tiS, 104;
of knowle-lge cr>ni crninK. '
Purkinje, portrait, 267
Smith, Wm., in geoloRj-, 328
Spallanzani, exjieriments on genera-
tion, 281; i«rlrait, 183
Special creation, theory of. 410
S|>ecie5, Kay, 117; LinnaMis, i
igin of,' 3
■-3^
aeration, belief in,
; new form of the
Redi, 179; Ppt-
;dbyGOOglC
469
teur, 288; Pouchel. a86; Spallan-
zani, 181; Tyndall, 390
Stcno, on fossils, 322
StrauS'Diirckhcim, his mono^aph,
96; illuslralions from. lot
Suarcz, and Ihf theory of special
Swammi^rdam, his Biblia Naturx.
73; illustrations from, 74, 76:
early interest in natural histor}',
68; life and works. 67-77; I"*''-'
of minute anatomy, 70; method of
work, 71; pcreonalily, 67; por-
trait, 6q: compared with Mai pighi
and Leeu wen hock, 87
, Linnaian, reform of, 130-
■38
Systema
. Nalunc, of Linna'us
Thetin-. the tell-, 242; the ))rotc)-
plasm, 272; of organic evolution.
345-368; of special trealion. 410
Tyndall, on spontaneous generation,
'289; his apjiaratus for getting op-
litallv pure air, 21)0
Typi'-tiicory, of Cuiicr, 132
34; personality, 23, 27, 30; phys-
iognomy, 30; portrait, 39; pred-
ecessors of, 26; especial service
of, 37; sketches from his works,
3'.33. 34, 49
I icq d'Azyr, 146; portrait, 147
'' ', Leonardo da. and fossils, 332
n histology, 174;
I'ries. Hugo de. his
403; portrait. 403.
theory, 406
portrait.
Variation, of animals, in a state of
nature, 383; origin of, according
to Weismann, 396
Vesalius. and the overthrow of au-
thority, in science, at-jS; great
hook of, 30: as lourt physician,
35; death, ,i6; force and inde-
pendence, 27; method of leaching
anatomy, 28. 21), opposition to,
Wallace, and Darain, 410: his ac-
count of the conditions under
which his theory originated, 427;
portrait, 4^8; writings, 427
Weismann, the man, 399; quotation
from autobiography. 401; per-
sonal qualities, 399; portmil, 400;
his theory of the germ-plasm. 3132-
399; summarv of his lhe<)n-. 40;
Whitney collccli
35 S
Willoughbv, hi
Rav, ii'i;
WolU; on iells. 340; his best work,
2ii; and epigcncsis, lot;; and
Hallcr, 311, 214; opiKi'scd by
Bonnet and Haller, 211; his [le-
riod in embryology, 205-114; jier-
sonalily. 214; plate from his
Theory of Generation, 209; the
Theoria Gcnerationis, 210
Wyman, Jeffries, on spontaneous
generation, 289
jn of fossil horses,
, connection with
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