By WESLEY K. COE

This article is intended as a brief survey of the development of

zoology in America, and no attempt is made to give a general history of

the science. There are numerous accounts in several languages of

zoological history in general, among them being W. A. Locy’s “Biology

and its Makers.” Brief outlines of the history of zoology may be found

in many zoological and biological text-books.

For the history of American zoology the reader is referred to Packard’s

report on “A Century’s Progress in American Zoology,” published in the

American Naturalist, (10, 591, 1876), to Packard’s “History of Zoology,”

published in volume 1 of the Standard Natural History (pp. lxii to

lxxii, 1885); to G. B. Goode’s “Beginnings of Natural History in

America,”[172] and “Beginnings of American Science,”[173] and to H. S.

Pratt’s Manual of the Common Invertebrate Animals (pp. 1–9), 1916. In

Binney’s “Terrestrial Air-breathing Mollusks of the United States”

(1851) is a chapter on the rise of scientific zoology in the United

States which well describes the zoological conditions in the early part

of the century, while numerous monographs and papers give the history of

the investigations on the various groups of animals or on special fields

of study.

Brief biographical sketches of the most distinguished of our older

Naturalists—Wilson, Audubon, Agassiz, Wyman, Gray, Dana, Baird, Marsh,

Cope, Goode and Brooks are given in “Leading American Men of Science,”

edited by David Starr Jordan, 1910. More extensive biographies have been

published separately, and the activities of a number of the more

prominent American zoologists have been recorded in the Biographical

Memoirs of the National Academy of Sciences.

The developmental history of zoology in America falls naturally into

four fairly well marked periods, namely:—1, _Period of descriptive

natural history_, previous to 1847, embracing the early studies on the

classification and habits of animals, characteristic of the zoological

work previous to the arrival of Louis Agassiz in America. 2, _Period of

morphology and embryology_, 1847–1870, during which the influence of

Agassiz directed the zoological studies toward problems concerning the

relationships of animals as indicated by their structure and

developmental history. 3, _Period of evolution_, 1870–1890, when the

principle of natural selection received general recognition and the

zoological studies were largely devoted to the applications of the

theory to all groups of animals. 4, _Period of experimental biology_,

since 1890, during which time have occurred the remarkable advances in

our knowledge of the nature of organisms through the application of

experimental methods in the various branches of the modern science of

biology.

_American Zoology in 1818._

At the beginning of the century which this volume commemorates, the

accumulated biological knowledge of the world consisted mainly of what

is to-day called descriptive natural history. The zoological treatises

of the time were devoted to the names, distinguishing characters and

habits of the species of animals and plants known to the naturalists of

Europe either as native species or as the results of explorations in

other parts of the world. This required little more than a superficial

knowledge of their general anatomical structures.

The naturalists of those days had no conception of the life within the

cell which we now know to form the basis of all the activities of

animals and plants, nor had they even the necessary means of studying

such life. The compound microscope, so necessary for the study of even

the largest of the cells of the body, was not adapted to such use until

1835, although the instrument was invented in the seventeenth century.

With the perfection of the microscope came a period of enthusiastic

study of microscopic organisms and microscopic structures of higher

animals and plants. It was not until twenty years after the founding of

the Journal that the cell theory of structure and function in all

organisms was established by the discoveries of Schleiden and Schwann.

The beginning of the nineteenth century saw great zoological activity in

Europe, and particularly in France. Buffon’s great work on the Natural

History of Animals had recently been completed, Cuvier had only one year

before published his classic work in comparative anatomy, “Le Regne

Animal,” and Lamarck’s “Philosophie Zoologique” had then aroused a new

interest in classification and comparative anatomy from an evolutionary

standpoint. E. Geoffroy St.-Hilaire was at the same time supporting an

evolutionary theory based on embryonic influences resulting in sudden

modifications of adult structure. These epoch-making discoveries and

theories gained a considerable following in France, Germany and England,

but seem to have had little influence on the zoological work of the

following half century in America.

The science of zoology as understood to-day is commonly said to have

been founded by Linnæus by the publication of the modern system of

classification in the tenth edition of his “Systema Naturæ” in 1758. The

influence of Linnæus aroused an interest in biological studies

throughout Europe and stimulated new investigations in all groups of

organisms. Such studies as related to animals naturally followed first

the classification and relationship of species, that is, systematic

zoology, and then led gradually into the development of the different

branches of the subject, as morphology, comparative anatomy, physiology,

and embryology, which eventually were recognized as almost independent

sciences.

Of these sciences systematic zoology, which has come to mean the

classification, structure, relationship, distribution and habits, or

natural history, is the pioneer in any region. Thus we find in our new

country at the time of the founding of the Journal in 1818, only sixty

years after the publication of Linnæus’ great work, the beginning of

American zoology taking the form of the collection and description of

our native animals.

It is true that many of our more conspicuous and easily collected

animals were described long before the opening of the nineteenth

century, but this is to be credited mainly to the work of European

naturalists who had made expeditions to this country for the purpose of

studying and collecting. These collections were then taken to Europe and

the results published there. We thus find in the 12th edition of Linnæus

descriptions of over 500 American species, about half of which were

birds. As an illustration of the extent to which some of these works

covered the field even in those early days may be mentioned a monograph

in two quarto volumes with many beautifully colored plates on the

“Natural History of the rarer Lepidopterous Insects of Georgia.” This

was published in London in 1797 by J. E. Smith from the notes and

drawings of John Abbot, one of the keenest naturalists of any period.

During the early years of the nineteenth century, however, economic

conditions in our country became such as to give opportunity for

scientific thought. Educated men then formed themselves into societies

for the discussion of scientific matters. This naturally led to the

establishment of publications whereby the papers presented to the

societies could be published and made available to the advancement of

science generally. The most influential of these was the Journal of the

Philadelphia Academy of Natural Science, which was established in 1817,

and was devoted largely to zoological papers. The Annals of the New York

Lyceum of Natural History date from 1823, and the Journal of the Boston

Society of Natural History from 1834. The Transactions of the American

Philosophical Society in Philadelphia and the Memoirs of the American

Academy of Arts and Sciences in Boston also published many zoological

articles.

In these publications and in the Journal, which was founded in 1818,

appear the descriptions of newly discovered animal species, with

observations on their habits.

The number of investigators in this field in the first quarter of the

nineteenth century was but few, and most of these were compelled to take

for the work such time as they could spare from their various

occupations.

Gradually the workers became more numerous until about the middle of the

century zoology was taught in all the larger colleges. The science

thereby developed into a profession.

For some years the studies remained largely of a systematic nature, and

embraced all groups of animals, but long before the close of the century

the attention of the majority of the ever increasing group of zoologists

was directed into more promising channels for research and there came

the development of the sciences of comparative anatomy, physiology,

embryology, experimental zoology, cytology, genetics, and the like,

while the systematists became specialists in the various animal groups.

But the work in systematic zoology remains incomplete and many native

species are still undescribed or imperfectly classified. It is perhaps

fortunate that a few faithful systematists remain at their tasks and

tend to keep the experimentalists from the disaster which might

otherwise result from the confusion of the species under investigation.

_Period of Descriptive Natural History.—Previous to 1847._

Of the few American naturalists whose writings were published toward the

end of the eighteenth century and at the beginning of the nineteenth the

names of William Bartram (1739–1823), Benjamin Barton (1766–1815),

Samuel Mitchill (1764–1831), William Peck (1763–1822), and Thomas

Jefferson (1743–1826), require special mention. Bartram’s entertaining

volume describing his travels through the Carolinas, Georgia and

Florida, published in 1793, contains a most interesting account of the

birds and other animals which he found.

Barton wrote many charming essays on the natural history of animals, but

was more particularly interested in botany. Mitchill’s most important

works include a history of the fishes of New York (1814), and additions

to an edition of Bewick’s General History of Quadrupeds. The latter,

published in 1804, contains descriptions and figures of some American

species and is the first American work on mammals.

Peck has the distinction of writing the first paper on systematic

zoology published in America. This was a description of new species of

fishes and was printed in 1794. He is also well known for his work on

insects and fungi.

Jefferson in 1781 published an interesting book describing the natural

history of Virginia, and during his presidency was of inestimable

service to zoology through his support of scientific expeditions to the

western portions of the country.

Previous to Agassiz’s introduction of laboratory methods of study in

comparative anatomy and embryology in 1847, American naturalists

generally confined their attention to the study of the classification

and habits of the multitude of undescribed animals and plants of the

region.

Such studies were naturally begun on the larger and more generally

interesting animals such as the birds and mammals, and although many of

these were fairly well described as to species before the opening of the

nineteenth century, little was known of their habits. The natural

history of our eastern birds first became well known through the

accurate illustrations and exquisitely written descriptions of Alexander

Wilson (in 1808–1813). Bonaparte’s continuation of Wilson’s work was

published in four folio volumes beginning in 1826.

In 1828 appeared the first of Audubon’s magnificent folio illustrations

of our birds. These were published in England, with later editions of

smaller plates in America. Nuttall’s Manual of the Ornithology of the

United States appeared in 1832–1834.

The second work on American mammals appeared in the second American

edition of Guthrie’s Geography, published in 1815. The author is

supposed to have been George Ord, although his name does not appear. In

1825 Harlan published his “Fauna Americana: Descriptions of the

Mammiferous Animals inhabiting North America.” This was largely a

compilation from European writers, particularly from Demarest’s

Mammalogie, and had little value.

In 1826 Amos Eaton published a small “Zoological Text-book comprising

Cuvier’s four grand divisions of Animals: also Shaw’s improved Linnean

genera, arranged according to the classes and orders of Cuvier and

Latreille. Short descriptions of some of the most common species are

given for students’ exercises. Prepared for Rensselaer school and the

popular class room.” “Four hundred and sixty-one genera are described in

this text-book. They embrace every known species of the Animal Kingdom.”

This is a compilation from European sources with a few American species

of various groups included. On the other hand, Godman’s Natural History,

in three volumes (1826–1828), was an illustrated and creditable work.

Such was also the case with Sir John Richardson’s Fauna Boreali

Americana of which the volume on quadrupeds was published in England in

1829. The other volumes on birds, fishes and insects appeared between

1827 and 1836. Audubon and Bachman’s beautifully illustrated “Quadrupeds

of North America” was issued between 1841 and 1850.

About 1840 several of the states inaugurated natural history surveys and

published catalogues of the local faunas. The reports on the animals of

Massachusetts and New York are the most complete zoological monographs

published in America up to that time. This is particularly true of

DeKay’s Natural History of New York published between 1842 and 1844 in

beautifully illustrated quarto volumes.

The leader in the systematic studies in the early part of the century

was Thomas Say, who published descriptions of a large number of new

species of animals, particularly reptiles, mollusks, crustacea and

insects. Say’s conchology, printed in 1816 in Nicholson’s Cyclopedia, is

the first American work of its kind. This was reprinted in 1819 under

the title “Land and Fresh-water Shells of the United States.” In

1824–1828 appeared the three volumes of Say’s American Entomology.

The prominent position held by Say in the zoological work of this period

is illustrated by the following paragraph from Eaton’s Zoological

Text-book (1826, p. 133): “At present but a small proportion of American

Animals, excepting those of large size, have been sought out ... And

though Mr. Say is doing much; without assistance, his life must be

protracted to a very advanced period to afford him time to complete the

work. But if every student will contribute his mite, by sending Mr. Say

duplicates of all undescribed species, we shall probably be in

possession of a system, very nearly complete, in a few years.” How

different is the attitude of the zoologist of to-day who sees the goal

much further away after a century’s progress through the industry of

hundreds of investigators.

During the period of Say’s most active work he is reported to have

“slept in the hall of the Philadelphia Academy of Natural Sciences,

where he made his bed beneath the skeleton of a horse and fed himself on

bread and milk.”

Next to Say, the most active zoologist of the early part of the century

was Charles Alexander Lesueur, who described and beautifully illustrated

many new species of fishes, reptiles, and marine invertebrates. A memoir

by George Ord, published in this Journal (=8=, 189, 1849), gives a full

list of Lesueur’s papers.

One of the most prolific writers of the period was Constantine

Rafinesque, a man of great brilliancy but one whose imagination so often

dominated his observations that many of his descriptions of plants and

animals are wholly unreliable.

_United States Exploring Expedition._—In 1838 a fortunate circumstance

occurred which eventually brought American systematic zoology into the

front ranks of the science. This opportunity was offered by the United

States Exploring Expedition under the command of Admiral Wilkes. With

James D. Dana as naturalist, the expedition visited Madeira, Cape Verde

Islands, eastern and western coasts of South America, Polynesia, Samoa,

Australia, New Zealand, Fiji, Hawaiian Islands, west coast of United

States, Philippines, Singapore, Cape of Good Hope, etc.

Of the extensive collections made on this four-years’ cruise, Dana had

devoted particular attention to the study of the corals and allied

animals (Zoophytes) and to the crustacea. In 1846 the report on the

Zoophytes was published in elegant folio form with colored plates. Six

years later the first volume of the report on Crustacea appeared, with a

second volume after two additional years (1854). These reports describe

and beautifully illustrate hundreds of new species, and include the

first comprehensive studies of the animals forming well-known corals.

They remain as the most conspicuous monuments in American invertebrate

zoology. Unfortunately the very limited edition makes them accessible in

only a few large libraries. The other, equally magnificent, volumes

include: Mollusca and Shells, by A. A. Gould, 1856; Herpetology, by

Charles Girard, 1858; Mammalogy and Ornithology, by John Cassin, 1858.

_Principal investigators._—Of the many writers on animals at this period

of descriptive natural history, the following were prominent in their

special fields of study:

Ayres, Lesueur, Mitchill, Storer, Linsley, Wyman, DeKay, Smith,

Kirtland, Rafinesque and Haldeman described the fishes.

Green, Barton, Harlan, Le Conte, Say, and especially Holbrook, studied

the reptiles and amphibia. Holbrook’s great monograph of the reptiles

(North American Herpetology) was published between 1834 and 1845.

Wilson, Audubon, Nuttall, Cooper, DeKay, Brewer, Ord, Baird, Gould,

Bachman, Linsley and Fox were among the numerous writers on birds.

Godman, Ord, Richardson, Audubon, Bachman, DeKay, Linsley and Harlan

published accounts of mammals.

On the invertebrates an important general work entitled “Invertebrata of

Massachusetts; Mollusca, Crustacea, Annelida and Radiata” was published

by A. A. Gould in 1841, which contains all the New England species of

these groups known to that date.

Lea, Totten, Adams, Barnes, Gould, Binney, Conrad, Hildreth, Haldeman,

were the principal writers on mollusks. The crustacea were studied by

Say, Gould, Haldeman, Dana; the insects by Say, Melsheimer, Peck,

Harris, Kirby, Herrick; the spiders by Hentz; the worms by Lee; the

coelenterates and echinoderms by Say, Mantell and others.

The history of entomology in the United States previous to 1846 is given

by John G. Morris in the Journal (=1=, =17=, 1846). In this article F.

V. Melsheimer is stated to be the father of American Entomology, while

Say was the most prolific writer. Say’s entomological papers, edited by

J. L. Le Conte, were completely reprinted with their colored

illustrations in 1859. The first economic treatise is that by Harris on

Insects Injurious to Vegetation; printed in 1841. This has had many

editions.

_Zoology in the American Journal of Science, 1818–1846._

The establishment of the Journal gave a further impetus to the

scientific activities of Americans in furnishing a convenient means for

publishing the results of their work. In the first volume of the

Journal, for example, are two zoological articles by Say and a dozen

short articles on various topics by Rafinesque, the latter being curious

combinations of facts and fancy. Most of the zoological papers appearing

in its first series of 50 volumes are characteristic of an undeveloped

science in an undeveloped country. They deal, naturally, with

observational studies on the structure and classification of species

discovered in a virgin field, with notes on habits and life histories.

Many of the papers are purely systematic and include the first

descriptions of numerous species of our mollusks, crustacea, insects,

vertebrates and other groups. Of these, the writings of C. B. Adams,

Barnes, A. A. Gould and Totten on mollusks, of J. D. Dana on corals and

crustacea, of Harris on insects, of Harlan on reptiles, and of Jeffries

Wyman and D. Humphreys Storer on fishes are representative and

important.

The progress of zoology in America during the first twenty-eight years

of the Journal’s existence, that is, up to the year 1846, is thus

summarized by Professor Silliman in the preface to vol. 50 (page ix),

1847:

“Our zoology has been more fully investigated than our mineralogy and

botany; but neither department is in danger of being exhausted. The

interesting travels of Lewis and Clark have recently brought to our

knowledge several plants and animals before unknown. Foreign

naturalists are frequently visiting our territory; and, for the most

part, convey to Europe the fruits of their researches, while but a

small part of our own is examined and described by Americans:

certainly this is little to our credit and still less to our

advantage. Honorable exceptions to the truth of this remark are

furnished by the exertions of some gentlemen in our principal cities,

and in various other parts of the Union.”

During these 28 years the Journal had been of great service to zoology

not only in the publication of the results of investigations but also in

the review of important zoological publications in Europe as well as in

America. There were also the reports of meetings of scientific

societies. In fact all matters of zoological interest were brought to

the attention of the Journal’s readers.

_The Influence of Louis Agassiz._

At the time of the founding of the Journal and for nearly thirty years

thereafter descriptive natural history constituted practically the

entire work of American zoologists. In this respect American science was

far behind that in Europe and particularly in France. It was not until

the fortunate circumstances which brought the Swiss naturalist, Louis

Agassiz, to our country in 1846 that the modern conceptions of

biological science were established in America.

Agassiz was then 39 years of age and had already absorbed the spirit of

generalization in comparative anatomy which dominated the work of the

great leaders in Europe, and particularly in Paris. The influence of

Leuckart, Tiedemann, Braun, Cuvier and Von Humboldt directed Agassiz’s

great ability to similar investigations, and he was rapidly coming into

prominence in the study of modern and fossil fishes when the opportunity

to continue his research in America was presented. On arriving on our

shores the young zoologist was so inspired with the opportunities for

his studies in the new country that he decided to remain.

Bringing with him the broad conceptions of his distinguished European

masters, he naturally founded a similar school of zoology in America. It

is from this beginning that the present science of zoology with its many

branches has developed.

It must be remembered in this connection that the great service which

Agassiz rendered to American zoology consisted mainly in making

available to students in America the ideals and methods of European

zoologists. This he was eminently fitted to do both because of his

European training and because of his natural ability as an inspiring

leader.

The times in America, moreover, were fully ripe for the advent of

European culture. There were already in existence natural history

societies in many of our cities and college communities. These societies

not only held meetings for the discussion of biological topics, but

established museums open to the public, and to which the public was

invited to contribute both funds and specimens. This led to a wide

popular interest in natural history. It was therefore comparatively easy

for such a man as Agassiz to develop this favorable public attitude into

genuine enthusiasm.

The American Journal of Science announces the expected visit of Agassiz

as a most promising event for American Zoology (=1=, 451, 1846): “His

devotion, ability, and zeal—his high and deserved reputation and ... his

amiable and conciliating character, will, without doubt, secure for him

the cordial cooperation of our naturalists ... nor do we entertain a

doubt that we shall be liberally repaid by his able review and

exploration of our country.” We of to-day can realize how abundantly

this prophecy was fulfilled.

In the succeeding volume (=2=, 440, 1846) occurs the record of Agassiz’s

arrival. “We learn with pleasure that he will spend several years among

us, in order thoroughly to understand our natural history.”

Immediately on reaching Boston, Agassiz began the publication of

articles on our fauna, and the following year he was appointed to a

professorship at Harvard. The Journal says (=4=, 449, 1847): “Every

scientific man in America will be rejoiced to hear so unexpected a piece

of good news.” The next year the Journal (5, 139, 1848) records

Agassiz’s lecture courses at New York and Charleston, his popularity

with all classes of the people and the gift of a silver case containing

$250 in half eagles from the students of the College of Physicians and

Surgeons.

The service of Agassiz to American zoology, therefore, consisted not

only in the publication of the results of his researches and his

philosophical considerations therefrom, but also, and perhaps in even

greater degree, in the popularization of science. In the latter

direction were his inspiring lectures before popular audiences and the

early publication of a zoological text-book. This book, published in

1848, was entitled “Principles of Zoology, touching the Structure,

Development, Distribution and Natural arrangement of the races of

Animals, living and extinct, with numerous illustrations.” It was

written with the cooperation of Augustus A. Gould. The review of this

book in the Journal (=6=, 151, 1848) indicates clearly the broad modern

principles underlying the new era which was beginning for American

zoology.

“A work emanating from so high a source as the Principles of Zoology,

hardly requires commendation to give it currency. The public have

become acquainted with the eminent abilities of Prof. Agassiz through

his lectures, and are aware of his vast learning, wide reach of mind,

and popular mode of illustrating scientific subjects ... The volume is

prepared for the student in zoological science; it is simple and

elementary in style, full in its illustrations, comprehensive in its

range, yet well considered and brought into the narrow compass

requisite for the purpose intended.”

The titles of its chapters will show how little it differs in general

subject matter from the most recent text-book in biology. Chapter I, The

Sphere and fundamental principles of Zoology; II, General Properties of

Organized Bodies; III, Organs and Functions of Animal Life; IV, Of

Intelligence and Instinct; V, Of Motion (apparatus and modes); VI, Of

Nutrition; VII, Of the Blood and Circulation; VIII, Of Respiration; IX,

Of the Secretions; X, Embryology (Egg and its Development); XI, Peculiar

Modes of Reproduction; XII, Metamorphoses of Animals; XIII, Geographical

Distribution of Animals; XIV, Geological Succession of Animals, or their

Distribution in Time.

A moment’s consideration of the fact that all these topics are

excellently treated will show how great had been the progress of zoology

in the first half of the nineteenth century. The sixty years that have

elapsed since the publication of this book have served principally to

develop these separate lines of biology into special fields of science

without reorganization of the essential principles here recognized. This

remained for many years the standard zoological and physiological

text-book, and was republished in several editions here and in England.

Another popular book is entitled “Methods of Study in Natural History”

(1864).

More than 400 books and papers were written by Agassiz, over a third of

which were published before he came to America. They cover both

zoological and geological topics, including systematic papers on living

and fossil groups of animals, but most important of all are his

philosophical essays on the general principles of biology.

One of Agassiz’s greatest services to zoology was the publication of his

“Bibliographia Zoologiæ et Geologiæ” by the Ray Society, beginning with

1848. The publication of the Lowell lectures in Comparative Embryology

in 1849 gave wide audience to the general principles now recognized in

the biogenetic law of ancestral reminiscence. As stated in the Journal

(=8=, 157, 1849), the “object of the Lectures is to demonstrate that a

natural method of classifying the animal kingdom may be attained by a

comparison of the changes which are passed through by different animals

in the course of their development from the egg to the perfect state;

the change they undergo being considered as a scale to appreciate the

relative position of the species.” These “principles of classification”

are fully elucidated in a separate pamphlet, and are discussed at length

in the Journal (=11=, 122, 1851).

One of the most interesting of Agassiz’s numerous philosophical essays,

originally contributed to the Journal (9, 369, 1850), discusses the

“Natural Relations between Animals and the elements in which they live.”

Another philosophical paper contributed to the Journal discusses the

“Primitive diversity and number of Animals in Geological times” (=17=,

309, 1854). Of his systematic papers, those on the fishes of the

Tennessee river, describing many new species, were published in the

Journal (=17=, 297, 353, 1854).

[Illustration: Ls Agassiz]

Agassiz’s beautifully illustrated “Contributions to the Natural History

of the United States” cover many subjects in morphology and embryology,

which are treated with such thoroughness and breadth of view as to give

them a place among the zoological classics. The Essay on Classification,

the North American Testudinata, the Embryology of the turtle, and the

Acalephs are the special topics. These are summarized and discussed at

length in the Journal (=25=, 126, 202, 321, 342, 1858; =30=, 142, 1860;

=31=, 295, 1861).

The volume on the “Journey in Brazil” (1868) in joint authorship with

Mrs. Agassiz is a fascinating narrative of exploration.

The conceptions which Agassiz held as to the most essential aim of

zoological study are well illustrated in his autobiographical sketch,

where he writes:[174]

“I did not then know how much more important it is to the naturalist

to understand the structure of a few animals, than to command the

whole field of scientific nomenclature. Since I have become a teacher,

and have watched the progress of students, I have seen that they all

begin in the same way; but how many have grown old in the pursuit,

without ever rising to any higher conception of the study of nature,

spending their life in the determination of species, and in extending

scientific terminology!”

It is not surprising, then, that under such influence the older

systematic studies should be replaced in large measure by those of a

morphological and embryological nature.

The personal influence of Agassiz is still felt in the lives of even the

younger zoologists of the present day. For the investigators of the

present generation are for the most part indebted to one or another of

Agassiz’s pupils for their guidance in zoological studies. These pupils

include his son Alexander Agassiz, Allen, Brooks, Clarke, Fewkes, Goode,

Hyatt, Jordan, Lyman, Morse, Packard, Scudder, Verrill, Wilder, and

others—leaders in zoological work during the last third of the

nineteenth century. Through such men as these the inspiration of Agassiz

has been handed on in turn to their pupils and from them to the younger

generation of zoologists.

The essential difference between the work of Agassiz and that of the

American zoologists who preceded him was in his power of broad

generalizations. To him the organism meant a living witness of some

great natural law, in the interpretation of which zoology was engaged.

The organism in its structure, in its development, in its habits

furnished links in the chain of evidence which, when completed, would

reveal the meaning of nature. Of all Agassiz’s pupils, probably William

K. Brooks most fittingly perpetuated his master’s ideals.

_Period of Morphology and Embryology, 1847–1870._

The new aspect of zoology which came as a result of the influence of

Agassiz characterized the zoological work of the fifties and sixties,

that is, until the significance of the natural selection theory of

Darwin and Wallace became generally appreciated.

The work in these years and well into the seventies was largely

influenced by the morphological, embryological and systematic studies of

Louis Agassiz and his school. The structure, development, and homologies

of animals as indicating their relationship and position in the scheme

of classification was prominent in the work of this period. The

adaptations of animals to their environment and the application of the

biogenetic law to the various groups of animals were also favorite

subjects of study.

The most successful investigators in this period on the different groups

of animals include:—Louis Agassiz on the natural history and embryology

of coelenterates and turtles; A. Agassiz, embryology of echinoderms and

worms; H. J. Clark, embryology of turtles and systematic papers on

sponges and coelenterates; E. Desor, echinoderms and embryology of

worms; C. Girard, embryology, worms, and reptiles; J. Leidy, protozoa,

coelenterates, worms, anatomy of mollusks; W. O. Ayres and T. Lyman,

natural history of echinoderms; McCrady, development of acalephs; W.

Stimpson, marine invertebrates; A. E. Verrill, coelenterates,

echinoderms, worms; A. Hyatt, evolutionary theories, bryozoa and

mollusks; Pourtales, deep sea fauna; C. B. Adams, A. and W. G. Binney,

Brooks, Carpenter, Conrad, Dall, Jay, Lea, S. Smith, Tryon, mollusks; E.

S. Morse, brachiopods, mollusks; J. D. Dana, coelenterates and

Crustacea; Kirtland, Loew, Edwards, Hagen, Melsheimer, Packard, Riley,

Scudder, Walsh, insects; Gill, Holbrook, Storer, fishes; Cope,

evolutionary theories, fishes and amphibia; Baird, reptiles and birds;

J. A. Allen, amphibia, reptiles and birds; Brewer, Cassin, Coues,

Lawrence, birds; Audubon, Bachman, Baird, Cope, Wilder, mammals.

The progress of ornithology in the United States previous to 1876 is

well described in a paper by J. A. Allen in the American Naturalist

(=10=, 536, 1876). A sketch of the early history of conchology is given

by A. W. Tryon in the Journal (=33=, 13, 1862).

Jeffries Wyman was the most prominent comparative anatomist of this

period. His work includes classic papers on the anatomy and embryology

of fishes, amphibia, and reptiles.

_Zoology in the American Journal of Science, 1846–1870._

The fifty volumes of the second series of the Journal, including the

years 1846 to 1870, cover approximately this period of morphology and

embryology. During this period the Journal occupied a very important

place in zoological circles, for J. D. Dana was for most of this period

the editor-in-chief, while Louis Agassiz and Asa Gray were connected

with it as associate editors. Moreover, in 1864 one of the most

promising of Agassiz’s pupils, Addison E. Verrill, was called to Yale as

professor of zoology and was made an associate editor in 1869.

In the Journal, therefore, may be found, in its original articles,

together with its reports of meetings and addresses and its reviews of

literature, a fairly complete account of the zoological activity of the

period. The most important zoological researches, both in Europe and

America, were reviewed in the bibliographic notices.

The most important series of zoological articles are by Dana himself. As

his work on the zoophytes and crustacea of the U. S. Exploring

Expedition continued, he published from time to time general summaries

of his conclusions regarding the relationships of the various groups.

Included among these papers are philosophical essays on general

biological principles which must have had much influence on the

biological studies of the time, and which form a basis for many of our

present concepts.

The importance of these papers warrants the list being given in full.

The titles are here in many cases abbreviated and the subjects

consolidated.

General views on Classification, =1=, 286, 1846.

Zoophytes, =2=, 64, 187, 1846; =3=, 1, 160, 337, 1847.

Genus Astraea, =9=, 295, 1850.

Conspectus crustaceorum, =8=, 276, 424, 1849; =9=, 129, 1850; =11=,

268, 1851.

Genera of Gammaracea, =8=, 135, 1849; of Cyclopacea, =1=, 225, 1846.

Markings of Carapax of Crabs, =11=, 95, 1851.

Classification of Crustacea, =11=, 223, 425; =12=, 121, 238, 1851;

=13=, 119; =14=, 297, 1852; =22=, 14, 1856.

Geographical distribution of Crustacea, =18=, 314, 1854; =19=, 6;

=20=, 168, 349, 1855.

Alternation of Generations in Plants and Radiata, =10=, 341, 1850.

Parthenogenesis, =24=, 399, 1857.

On Species, =24=, 305, 1857.

Classification of Mammals, =35=, 65, 1863; =37=, 157, 1864.

Cephalization, =22=, 14, 1856; 36, =1=, 321, 440, 1863; =37=, 10, 157,

184, 1864; =41=, 163, 1866; =12=, 245, 1876.

Homologies of insectean and crustacean types, =36=, 233, 1863; =47=,

325, 1894.

Origin of life, =41=, 389, 1866.

Relations of death to life in nature, =34=, 316, 1862.

Of the above, the articles on cephalization as a fundamental principle

in the development of the system of animal life have attracted much

attention. The evidence from comparative anatomy, paleontology, and

embryology alike supports the view that advance in the ontogenetic as

well as in the phylogenetic stages is correlated with the unequal growth

of the cephalic region as compared with the rest of the body. Dana shows

that this principle holds good for all groups of animals. His homologies

of the limbs of arthropods and vertebrates, however, do not accord with

more modern views.

Other papers on the same and allied topics were published by Dana in

other periodicals. His most conspicuous zoological works, however, are

his reports on the Zoophytes and Crustacea of the United States

Exploring Expedition, 1837–1842. The former consists of 741 quarto pages

and 61 folio plates, describing over 200 new species, while the

Crustacea report, in two volumes, has 1620 pages and 96 folio plates,

with descriptions of about 500 new species. Each of these remains to-day

as the most important contribution to the classification of the

respective groups. The relationships of the species, genera and families

were recognized with such remarkable judgment that Dana’s admirable

system of classification has remained the basis for all subsequent work.

Dana’s critical reviews (=25=, 202, 321, 1858) of Agassiz’s

“Contribution to the Natural History of the United States” are among the

most interesting of his philosophical discussions concerning the

relationships of animals as revealed by their structure, their

embryology, and their geological history.

The remaining zoological articles in this series cover nearly the whole

range of systematic zoology. Especially important are the articles by

Verrill on coelenterates, echinoderms, worms and other invertebrates.

In the years following the publication of Darwin’s Origin of Species in

1859 occur many articles on the theory of natural selection. Some of the

writers attack the theory, while others give it more or less

enthusiastic support.

Experimental methods in solving biological problems were little used at

this time, although a few articles of this nature appear in the Journal.

Of these, a paper by W. C. Minor (35, 35, 1863) on natural and

artificial fission in some annelids has considerable interest to-day.

_Exploring Expeditions._

Of the important zoological expeditions the following may be selected as

showing their influence on American Zoology:

The North Pacific Expedition, with William Stimpson as zoologist,

returned in 1856 with much new information concerning the marine life of

the coasts of Alaska and Japan and many new species of invertebrates.

In 1867–1869 the United States Coast Survey extended its explorations to

include the deep sea marine life off the southeastern coasts and Gulf of

Mexico under the leadership of Pourtales and Agassiz.

The Challenger explorations (1872–1876) added greatly to the knowledge

of marine life off the American coast as well as in other parts of the

world.

The explorations of the United States Fish Commission succeeded those of

the Coast Survey in the collection of marine life off our coasts and in

our fresh waters. These have continued since 1872 and have yielded most

important results from both the scientific and economic standpoints.

Under the charge of Alexander Agassiz the Coast Survey Steamer “Blake,”

in 1877 to 1880, was engaged in dredging operations in three cruises to

various parts of the Atlantic. The U. S. Fish Commission Steamer

“Albatross,” also in charge of Agassiz, made three expeditions in the

tropical and other parts of the Pacific in the years from 1891 to 1905.

The study of these collections has added greatly to our knowledge of

systematic zoology and geographical distribution. The reports on some of

the groups are still in course of preparation.

_Period of Evolution, 1870–1890._

The time from 1870 to 1890 may be appropriately called the period of

evolution, for although it commences eleven years after the publication

of the Origin of Species, the importance of the natural selection theory

was but slowly receiving general recognition. The hesitation in

accepting this theory was due in no small degree to the opposition of

Louis Agassiz. After the acceptance of evolution, although morphological

and embryological studies continued as before, they were prosecuted with

reference to their bearing on evolutionary problems.

Following closely the methods which had produced so much progress during

the life of Agassiz, the field of zoology was now occupied by a new

generation, among whom the pupils of Agassiz were the most prominent.

[Illustration: Thomas H. Huxley]

The teaching of biology at this time was also strongly influenced by

Huxley, whose methods of conducting laboratory classes for elementary

students were adopted in most of our large schools and colleges. This

placed biology on the same plane with chemistry as a means for training

in laboratory methods and discipline, with the added advantage that the

subject of biology is much more intimately connected with the student’s

everyday life and affairs.

This increasing demand for instruction in biology and the consequent

necessity for more teachers brought an increasing number of

investigators into this field.

Conspicuous in this period was the work of E. D. Cope, best known as a

paleontologist, but whose work on the classification of the various

groups of vertebrates stands preeminent, and whose philosophical essays

on evolution had much influence on the evolutionary thought of the time.

He was a staunch supporter of the Lamarckian doctrine. Alpheus Hyatt

also maintained this theory, and brought together a great accumulation

of facts in its support. He thereby contributed largely to our knowledge

of comparative anatomy and embryology. A. S. Packard, whose publications

cover a wide range of topics, was best known for his text-books of

zoology and his manuals on insects.

W. K. Brooks was a leading morphologist and embryologist. S. F. Baird,

for many years the head of the United States Fish Commission, was the

foremost authority on fish and fisheries and is also noted for his work

on reptiles, birds and mammals. The man of greatest influence, although

by no means the greatest investigator, was C. O. Whitman. It is to him

that we owe the inception of the Marine Biological Laboratory, the most

potent influence in American zoology to-day; the organization of the

American Morphological Society, the forerunner of the present American

Society of Zoologists; and the establishment of the Journal of

Morphology. G. B. Goode was distinguished for his work on fishes and for

his writings on the history of science.

E. L. Mark, C. S. Minot, and Alexander Agassiz were acknowledged leaders

in their special fields of research—Mark in invertebrate morphology and

embryology, and Minot in vertebrate embryology, while Alexander Agassiz

made many important discoveries in the systematic zoology and embryology

of marine animals, and to him we owe in large measure our knowledge of

the life in the oceans of nearly all parts of the world.

The knowledge of the representatives of the different divisions of the

American fauna had now become sufficient to allow the publication of

monographs on the various classes, orders and families. At this time

also particular attention was given to the marine invertebrates of all

groups.

Of the many investigators working on the various groups of animals at

this time only a few may be mentioned. The protozoa were studied by

Leidy, Clark, Ryder, Stokes; the sponges by Clark, Hyatt; the

coelenterates by A. Agassiz, S. F. Clarke, Verrill; the echinoderms by

A. Agassiz, Brooks, Kingsley, Fewkes, Lyman, Verrill; the various groups

of worms by Benedict, Eisen, Silliman, Verrill, Webster, Whitman; the

mollusks by A. and W. G. Binney, Tryon, Conrad, Dall, Sanderson Smith,

Stearns, Verrill; the Brachiopods by Dall and Morse; the Bryozoa by

Hyatt; the crustacea by S. I. Smith, Harger, Hagen, Packard, Kingsley,

Faxon, Herrick; the insects by Packard, Horn, Scudder, C. H. Fernald,

Williston, Norton, Walsh, Fitch, J. B. Smith, Comstock, Howard, Riley

and many others; spiders by Emerton, Marx, McCook; tunicates by Packard

and Verrill; fishes by Baird, Bean, Cope, Gilbert, Gill, Goode, Jordan,

Putnam; amphibians and reptiles by Cope; birds by Baird, Brewer, Coues,

Elliott, Henshaw, Allen, Merriam, Brewster, Ridgway; and the mammals by

Allen, Baird, Cope, Coues, Elliott, Merriam, Wilder.

Interest in the evolutionary theory continued to increase and eventually

developed into the morphological and embryological studies which reached

their culmination between 1885 and 1890 under the guidance of Whitman,

Mark, Minot, Brooks, Kingsley, E. B. Wilson and other famous zoologists

of the time. In these years the Journal of Morphology was established

and the American Morphological Society was formed.

The morphological, embryological and paleontological evidences of

evolution as indicated by homologies, developmental stages and

adaptations were the most absorbing subjects of zoological research and

discussion.

[Illustration: A. E. Verrill March 1904]

_Zoology in the American Journal of Science, 1870–1918._

The third series of the Journal (1870–1895), likewise including fifty

volumes, embraces this period of zoological activity in morphological

and embryological studies, culminating with the inception of the modern

experimental methods.

In this period also occurred the greatest progress in marine systematic

zoology, due to the explorations of the United States Fish Commission

off the Atlantic Coast. The Journal had an important share in the

zoological development of this period also, for A. E. Verrill, who was

now an associate editor, was in charge of the collections of marine

invertebrates. Consequently most of the discoveries in this field were

published in the Journal in numerous original contributions by Verrill

and his associates. The explorations of the U. S. Fish Commission

Steamer “Albatross” are described from year to year by Verrill, with

descriptions of the new species of invertebrates discovered.

The numerous original contributions by Verrill on subjects of general

zoological interest as well as on those of a systematic nature give this

third series of the Journal much zoological importance. Verrill’s papers

cover almost the whole field of descriptive zoology, but are mainly

devoted to marine invertebrates. Those which were originally contributed

to the Journal or summarized by him in his literature reviews include

the following topics:

Sponges, =16=, 406, 1878.

Coelenterates, 37, 450, 1864; =44=, 125, 1867; =45=, 411, 186; =46=,

143, 1868; =47=, 282, 1869; =48=, 116, 419, 1869; =49=, 370, 1870;

=3=, 187, 432, 1872; =6=, 68, 1873; =21=, 508, 1881; =6=, 493, 1898;

=7=, 41, 143, 205, 375, 1899; =13=, 75, 1902.

Echinoderms, =44=, 125, 1867; =45=, 417, 1868; =49=, 93, 101, 1870;

=2=, 430, 1871; =11=, 416, 1876; =49=, 127, 199, 1895; =28=, 59, 1909;

=35=, 477, 1913; =37=, 483, 1914; =38=, 107, 1914; =39=, 684, 1915.

Worms, =50=, 223, 1870; =3=, 126, 1872.

Mollusks, =49=, 217, 1870; =50=, 405, 1870; 3, 209, 281, 1872; =5=,

465, 1873; =7=, 136, 158, 1874; =9=, 123, 177, 1875; 10, 213, 1875;

=12=, 236, 1876; =14=, 425, 1877; =19=, 284, 1880; =20=, 250, 251,

1880; =2=, 74, 91, 1896; =3=, 51, 79, 162, 355, 1897.

Crustacea, =44=, 126, 1867; =48=, 244, 430, 1869; =25=, 119, 534,

1908.

Ascidians, =1=, 54, 93, 211, 288, 443, 1871; =20=, 251, 1880.

Dredging operations and marine fauna, =49=, 129, 1870; =2=, 357, 1871;

=5=, 1, 98, 1873; =6=, 435, 1873; =7=, 38, 131, 405, 409, 498, 608,

1874; =9=, 411, 1875; =10=, 36, 196, 1875; =16=, 207, 371, 1878; =17=,

239, 258, 309, 472, 1879; =18=, 52, 468, 1879; =19=, 137, 187; =20=,

390, 1880; =22=, 292, 1881; =23=, 135, 216, 309, 406, 1882; =24=, 360,

477, 1882; =28=, 213, 378, 1884; =29=, 149, 1885.

Miscellaneous, =39=, 221, 1865; =41=, 249, 268, 1866; =44=, 126, 1867;

=48=, 92, 1869; =3=, 386, 1872; =7=, 134, 1847; =10=, 364, 1875; =16=,

323, 1878; =20=, 251, 1880; =3=, 132, 135, 1897; =9=, 313, 1900; =12=,

88, 1901; =13=, 327, 1902; =14=, 72, 1902; =15=, 332, 1903; =24=, 179,

1907; =29=, 561, 1910.

S. I. Smith describes the metamorphosis of the Crustacea (=3=, 401,

1872; =6=, 67, 1873), species of crustacea (=3=, 373, 1872; =7=, 601,

1874; =9=, 476, 1875), and dredging operations in Lake Superior (=2=,

373, 448, 1871). In this series occurs also a series of papers on

comparative anatomy and embryology from the Chesapeake Zoological

Laboratory in charge of W. K. Brooks. In the 39th and 40th volumes of

the third series (1890) occur several papers on evolutionary topics by

John T. Gulick (=39=, 21; =40=, 1, 437) which have attracted much

attention.

Before the end of this period, however, the Journal was relieved from

the necessity of publishing zoological articles by the establishment of

several periodicals devoted especially to the various fields of zoology.

We find, therefore, but few exclusively zoological papers after 1885,

although articles of a general biological interest and the reviews of

zoological books continue.

In the fourth series of the Journal, beginning in 1896, occur also a

number of articles on systematic zoology by Verrill and others and

several papers having a general biological interest. Brief reviews of a

small number of zoological books are still continued, but at the present

day the Journal, which played so important a part in the early

development of American zoology, has been given over to the geological

and physical sciences in harmony with the modern demand for

specialization.

_Period of Experimental Biology, since 1890._

Zoological studies remained in large measure observational and

comparative until about 1890 when the experimental methods of Roux,

Driesch and others came into prominence. Interest then turned from the

accumulation of facts to an analysis of the underlying principles of

biological phenomena. The question now was not so much what the organism

does as how it does what is observed, and this question could be

answered only by the experimental control of the conditions. These

experimental studies met with such remarkable success that in a few

years the older morphological studies were largely abandoned, the

Morphological Society changed its name to the Society of Zoologists, and

in 1904 the Journal of Experimental Zoology was established. The

experimental methods were applied to all branches of biological science,

and while it must be freely admitted that little progress has been made

toward an understanding of the ultimate causes which underlie biological

phenomena, a great advance has been made in the elucidation of the

general principles involved.

Experimental embryology, histology, regeneration, comparative

physiology, neurology, cytology, and heredity have in recent years

successfully adopted an experimental aspect and have made significant

progress thereby. Biology has now taken its place beside chemistry and

physics as an experimental science.

The latest great advance in biology has been in the field of heredity.

The rediscovery of the Mendelian principles of heredity in 1900 brought

to light the most important generalization in biology in recent times.

The new science of genetics is essentially the experimental study of

heredity.

We are at the moment in the midst of an effort to establish in biology a

few relatively simple laws by using for the purpose the vast

accumulations of observational data gathered in past years, supplemented

by such experimental data as have been provided by these more recent

investigations. Such hypotheses as have been formulated are for the most

part only tentatively held, for their validity is generally incapable of

a critical test. But wherever such tests have been possible, the laws of

mathematics, physics and chemistry are found applicable to biological

phenomena.

The number of investigators has now become so great and their activities

so prolific that the list and synopses of the zoological publications

each year cover upwards of 1000 to 1500 pages in the International

Catalogue of Scientific Literature.

_American Leadership._—During the first half of the century the progress

of zoology in America remained distinctly behind that of Europe. At the

beginning of the century the science was farthest developed by the

French and English, although Linnæus was a Swede and took his degree in

Holland. Under the influence of Von Baer and his monumental treatise on

embryology (Ueber Entwicklungsgeschichte der Thiere, 1828), and

supported later by the great physiologist, Johannes Müller, whose

“Physiologie des Menschen” (1846) forms the basis of modern physiology,

the German school forged rapidly ahead and eventually assumed the

leadership in zoology, as in several other branches of science.

In the latter half of the century the influence of the German

universities dominated in a large measure the zoological investigations

in America. The reason for this is partly due to the fact that many of

our young zoologists, after finishing their college course, completed

their preparation for research by a year or more at a German university.

The more mature zoologists, too, looked forward with keen anticipation

to spending their summer vacations and sabbatical years in research in a

German laboratory or at the famous Naples station in which the German

influence was dominant.

With the rise of experimental biology since 1890, however, the American

zoologists have shown so high a degree of originality in devising

experiments, so much skill in performing them, and such keenness in

analyzing the results, that they have assumed the world leadership in

several of the special fields into which the science of zoology is now

divided.

_Biological Periodicals._

Perhaps in no better way can the progress of biology in America be

illustrated than by a brief survey of the origin and development of the

more important biological journals. For it will be seen that these

publications have become more numerous and more specialized as the

science has advanced in specialization.

The early publications—which as is well known, treated mainly of the

birds, mammals and other vertebrates, and of insects, crustacea and

shells—consisted mainly of separate books or pamphlets, published by

private subscription. After the establishment of the so-called Academies

of Science, or of Arts and Sciences, toward the end of the eighteenth

and in the first quarter of the nineteenth century, the reports of the

meetings began to be published as periodical Journals, supported by the

academies. In these publications, and in the Journal which was founded

at the same time, appear papers on all branches of science, including

zoology. As soon as zoology in America assumed its modern aspects

through the influence of Louis Agassiz and his followers the earliest

strictly zoological journals were established.

It should be noted, however, that the journals of the scientific and

natural history societies were more or less fully devoted to zoological

topics according to the nature of the activities of the members and

correspondents. After the establishment of the Museum of Comparative

Zoology by Louis Agassiz came the founding in 1863 of its Bulletin and

later its Memoirs. These publications have continued to the present day

as a standard of excellence for the reports of zoological

investigations. In connection with the systematic work on mollusks, the

American Journal of Conchology was established in 1865. The American

Naturalist was founded in 1867 by four of Louis Agassiz’s pupils, Hyatt,

Morse, Packard and Putnam. It was later edited by Cope as a leading

periodical for the publication of biological papers, particularly those

relating to evolution, and is at present devoted to evolutionary topics.

It is now in the 52d volume of its new series.

With the awakened interest in comparative anatomy and embryology came

the need for an American journal which should supply a means of

publication for the reports of researches accomplished by the increasing

number of workers in these fields. This need was fully met by the

establishment of the Journal of Morphology in 1887. This publication,

now in its 30th volume, has equalled the best European journals in the

character of its papers. A few years later (1891) came the Journal of

Comparative Neurology for the publication of investigations relating to

the morphology and physiology of the nervous system and to nervous and

allied phenomena in all groups of organisms. Twenty-eight volumes of

this journal have been completed. The Zoological Bulletin was started

under the auspices of the Marine Biological Laboratory in 1897 for the

publication of papers of a less extensive nature and which could be more

promptly issued than those in the Journal of Morphology where elaborate

plates were required. After two years the scope of the Bulletin was

enlarged to include botanical and physiological subjects. The name was

correspondingly changed to the Biological Bulletin. Of this important

periodical 33 volumes have been issued.

For the publication of papers on human and comparative anatomy and

embryology, the American Journal of Anatomy was established in 1901, and

is now in its twenty-third volume.

Meanwhile the trend of zoological interest was toward topics connected

with the ultimate nature of biological phenomena. The meaning of these

phenomena could be determined only by the experimental method.

Researches in this field became more prominent and the adequate

publication of the numerous papers required the establishment of a new

journal in 1904. This was named the Journal of Experimental Zoology. It

immediately took its place in the front rank of American zoological

periodicals. Twenty-four volumes have been published.

In spite of the constantly increasing number of journals, the science

grew faster than the means of publication. So crowded did the American

journals become that long delays often resulted before the results of an

investigation could be issued. This condition was met in part by the

sending of many papers to be published in European journals (a necessity

most discreditable to American zoology) and in part by the establishment

of additional means of publication. Of the latter the Anatomical Record,

now in its fourteenth volume, was begun in 1906 for the prompt

publication of briefer papers on vertebrate anatomy, embryology and

histology and for preliminary reports and notes on technique.

During the past few years has come a great advance in the experimental

breeding of plants and animals. Problems in heredity and evolution have

taken on a new interest since the importance and validity of Mendel’s

discovery have been recognized. To meet this development of biology the

journal Genetics was begun in 1916 for the publication of technical

papers, while the Journal of Heredity, modified from the American

Breeders Magazine, is devoted to popular articles on animal and plant

breeding, and Eugenics.

On the whole, the science of zoology is now assuming a closer relation

to practical affairs. Entomology, for example, is now represented by the

Journal of Economic Entomology, of which 10 volumes have been issued

since 1907. The Journal of Animal Behavior covers another practical

field of research. The Proceedings of the Society for Experimental

Biology and Medicine, starting in 1903, the American Journal of

Physiology, and several other publications cover the physiological

field. The Journal of Parasitology, established 1914, now in its fourth

volume, is devoted to the interests of medical zoology. The Auk, now in

the 34th volume of its new series (42d of old series), is the official

organ of the American Ornithologists Union and is devoted to the

dissemination of knowledge concerning bird life. The Annals of the

Entomological Society of America, established in 1908, and now in its

10th volume, is one of several important entomological journals. The

Nautilus, of which 28 volumes have been issued, is one of the more

successful journals devoted to conchology. This list might be extended

to include numerous other periodicals of importance, both technical and

popular, which have been of great service in the various fields of

biology.

In addition to these are the many volumes of systematic papers in the

Proceedings of the United States National Museum, the practical reports

in the Bulletin of the United States Fish Commission, the vast

literature issued yearly by the various divisions of the United States

Department of Agriculture, Public Health Service and other Governmental

departments, while the list of publications by scientific societies,

museums, and other institutes is constantly increasing and covers all

fields of biological research.

At the present time facilities for the publication of research on any

branch of zoology are as a rule entirely adequate. For this highly

satisfactory condition the science is indebted to the support given five

of its most important journals by the Wistar Institute of Anatomy and

Biology.

_Biological Associations._

An important light on the history of biology in America can be thrown by

a glance at the rise and development of societies or associations for

the report and discussion of papers relating to that branch of science.

In the first half of the nineteenth century natural history societies

were formed in most cities and centers of learning. These were very

important factors in the promotion of scientific research as well as in

the diffusion of popular knowledge of living things. The aims and

activities of twenty-nine such scientific societies, many of which were

devoted especially to natural history, are described in one of the early

volumes of the Journal (=10=, 369, 1826). The Connecticut Academy of

Arts and Sciences, dating from 1799, the Philadelphia Academy of Natural

Sciences from 1812, and the New York Lyceum of Natural History (in 1876

name changed to New York Academy of Sciences) from 1817 are among the

oldest of those which still exist.

Of national institutions the American Philosophical Society was founded

in 1743, the American Academy of Arts and Sciences in 1780, and the

National Academy of Sciences in 1863.

The American Association for the Advancement of Science, with its

thousands of members, now has separate sections for each of the special

branches of science. This great association was organized in 1848, as

the successor of the Association of American Geologists and Naturalists.

This was itself a revival of the American Geological Society which first

met at Yale in 1819. Its meetings have given a great support to the

scientific work of the country.

The American Society of Naturalists was founded in 1883. The original

plan of the society was for the discussion of methods of investigation,

administration and instruction in the natural sciences, but its program

is now entirely devoted to discussions and papers of a broad biological

interest. It also arranges for an annual dinner of the several

biological societies and an address on some general biological topic.

In 1890, toward the end of the period in which morphological studies

were being emphasized, the professional zoologists of the eastern states

founded the American Morphological Society. This association held annual

meetings during the Christmas holidays for the presentation of

zoological papers. This name became less appropriate after a few years

because of the gradual decrease in the proportion of morphological

investigations owing to the greater attention being directed to problems

in experimental zoology and physiology. Consequently the name was

changed to the American Society of Zoologists. To be eligible for

membership in this society a person must be an active investigator in

some branch of zoology, as indicated by the published results.

The American Association of Anatomists includes in its membership

investigators and teachers in comparative anatomy, embryology, and

histology as well as in human anatomy. Many professional zoologists and

experimental biologists present their papers before this society, or at

the meetings of the American Physiological Society. The Entomological

Society of America and the American Association of Economic

Entomologists are large and active societies.

These national societies have been of great service in fostering a high

standard of zoological research. A still more important service, though

generally less conspicuous, is rendered by the journal clubs in

connection with all the larger zoological laboratories, and by local

scientific societies which are now maintained in all the larger centers

of learning throughout the country. There are also specific societies

for some of the different fields of biological work.

_Biological Stations._

No insignificant factor in the development of biological science has

been the establishment of biological stations where investigators,

teachers and students meet in the Summer vacation for special studies,

discussions and research. The most successful of these laboratories have

been located on the seashore and here the study of marine life in Summer

supplements the work of the school or university biological courses. The

famous Naples Station was founded in 1870, and was shortly after

followed by several others. Similar biological stations are now

supported on almost every coast in Europe and in several inland

localities.

The first such American school was established by Louis Agassiz at the

island of Penikese on the coast of Massachusetts in 1873, succeeding his

private laboratory at Nahant. During that Summer more than forty

students gained enthusiasm for the work of future years. Unfortunately

the laboratory so auspiciously started was of brief duration, for the

death of Agassiz occurred in December of the same year, and the

laboratory was discontinued at the end of the following Summer. Shortly

afterward Alexander Agassiz equipped a small private laboratory at

Newport, Rhode Island, and W. K. Brooks established the Chesapeake Bay

Zoological Laboratory.

At this time the United States Fish Commission was engaged under the

direction of Spencer F. Baird in a survey of the marine life of the

waters off the Eastern Coast. Between 1881 and 1886 the Commission

established the splendidly equipped biological station at Woods Hole,

Massachusetts. Both here and at the Fish Commission Laboratory at

Beaufort, North Carolina, much work in general zoology as well as in

economic problems is accomplished. These laboratories are designed

particularly for specialists engaged in researches connected with the

work of the Fish Commission.

A need was soon felt for a marine laboratory along broader lines, and

one available to the students and teachers of the schools and colleges.

To meet these requirements the Woods Hole Marine Biological Laboratory

was started in 1887, as the successor to an earlier laboratory at

Annisquam, and has since become a great Summer congress for biologists

from all parts of the country. It is safe to say that no other

institution has been of equal service in securing for biology the high

plane it now occupies in American science. The leading spirit in the

establishment of this laboratory and its director for many years was

Charles O. Whitman.

Successful marine laboratories are located also at Cold Spring Harbor,

Long Island; at Harpswell, Maine; and at Bermuda. The Carnegie

Institution maintains a laboratory at Tortugas Island, Florida, for the

investigation of tropical marine life.

On the Pacific Coast marine laboratories are located at Pacific Grove

and at La Jolla, California, and at Friday Harbor, Washington. Several

other biological laboratories are open each Summer on our coasts, as

well as a number of fresh-water laboratories on the interior lakes.

There are also several mountain laboratories. The influence of these

laboratories on American biology is immeasurable.

_Natural History Museums._

Museums of Natural History or “Cabinets of Natural Curios” as they were

sometimes called, were established in the first half of the nineteenth

century in connection with the various natural history societies. These

were of much service in stimulating the collection of zoological

“specimens” and in arousing a popular interest in natural history.

The zoological museum of earlier days consisted of rows on rows of

systematically arranged specimens, each carefully labelled with

scientific name, locality, date of collection and donor—much like the

pages of a catalogue. All this has now been changed; the bottles of

specimens have been relegated to the storeroom, and the great plate

glass cases of the modern museum represent individual studies in the

various fields of modern zoological research, or individual chapters in

the latest biological text-books. Often the talent of the artist and the

skill of the taxidermist are cunningly combined to produce most

realistic bits of nature.

The United States National Museum, the American Museum of Natural

History, the Field Columbian Museum and the Museum of Comparative

Zoology are among the finest museums of the world, while many of the

states, cities, and universities maintain public museums as a part of

their educational systems.

_Systematic Zoology and Taxonomy._

The work in systematic zoology is now mainly carried on by specialists

in relatively small groups of animals. This is necessitated both by the

increasingly large number of species known to science and by the

completeness and exactness with which species must now be defined. The

majority of systematic workers are now connected with museums where the

large collections furnish material for comparative studies.

Prominent in this field is the United States National Museum, the

publications of which are mainly taxonomic and zoogeographic, and cover

every group of organism. The adequacy of this great museum for such

studies may be illustrated by the collection of mammals. This museum has

the types of 1135 of the 2138 forms (including species and subspecies)

of North American mammals recognized in Miller’s list,[175] and less

than 200 forms lack representatives among the 120,000 specimens of

mammals. Systematic monographs of several of the orders of mammals have

been published.

Systematic study of the birds has brought the number of species and

subspecies known to inhabit North and Middle America to above 3000. The

most comprehensive systematic treatise is the still incomplete report of

Ridgeway[176] of which seven large volumes have already been issued.

On the reptiles, the most complete monograph is that by Cope[177]

entitled “The Crocodilians, Lizards and Snakes of North America.”

The Amphibia have also been studied by Cope, whose report on the

Batrachia of North America[178] is the standard taxonomic work.

The most comprehensive systematic work on fishes is the “Descriptive

Catalogue of the Fishes of North and Middle America” by Jordan and

Evermann.[179]

The invertebrate groups have been in part similarly monographed by the

members of the U. S. National Museum staff and others, and further

studies are in progress. Other taxonomic monographs published by this

museum include the various groups of animals from many different parts

of the world.

A number of the larger State, municipal, and university museums publish

bulletins on special groups represented in their collections as well as

articles of general zoological interest.

Expeditions, subsidized by museum and private funds, are from time to

time sent to various parts of the world and their results are often

published in sumptuous manner.

The total number of living species of animals is unknown, but

considering that about a quarter of a million new species have been

described during the past thirty years, it is probable that several

million species are in existence to-day. More than half a million have

been described. These are probably but a small fraction of the number

that have existed in past geological ages.

Thus, in spite of all the work that has been done in systematic zoology

and as the number of known species continues to increase, there still

remain many groups of animals, some of which are by no means rare or

minute, in which probably only a small proportion of the species are as

yet capable of identification.

It is only since the publication of Ward and Whipple’s “Fresh-water

Biology” within the past year that the amateur zoologist could hope to

find even the names of all the organisms which may be collected from a

single pool of water. And in many cases he will still meet with

disappointment, for many of our protozoa and other fresh-water organisms

have not yet been described as species.

During the past few years there has been a tendency on the part of some

of our biologists engaged in experimental work to disparage the studies

of the systematists. It must be granted, however, that both lines of

work are essential to the sound development of zoological science, for

experimental investigations in which the accurate diagnosis of species

is ignored always result in confusion.

_Ecology._—The marvelous modifications in structure and instincts by

which the various animals are adapted to their surroundings now forms a

special topic in biological research and one of the most fascinating.

The adaptations in habitat, time, behavior, appearance and even in

structure are found capable of a certain individual modification when

studied experimentally.

_Zoogeography._—Closely associated with systematic zoology, and indeed a

part of the subject in its broader sense, is the study of the

geographical distribution of animal species and larger groups.

_Paleontology._—The geological succession of organisms embraces a field

where zoologist and geologist meet. The wonderful progress made by

American investigators is well described in the preceding chapters on

Historical Geology and Vertebrate Paleontology.

_Biometry._

Since Darwin’s theory of evolution postulated the origin of new species

by means of natural selection, it was obviously necessary in order to

apply a critical test to determine the precise limits of a species. It

was, therefore, proposed to subject a given species to a strict

examination by the application of statistical methods to determine the

range of variation of its members and the extent to which the species

intergrades with others. Other problems, particularly those concerning

heredity, were treated in similar manner. This branch of biological

science was particularly developed by the English School, led by Sir

Francis Galton, followed by Karl Pearson and William Bateson.

In America the methods of biometry have been utilized extensively by

Charles B. Davenport, Raymond Pearl, H. S. Jennings and others in the

solution of problems in genetics and evolution. Their work shows the

great value of critical statistical analysis in the interpretation of

biological data. A thorough training in mathematics is now found to be

hardly less important for the biologist than is a knowledge of physics

and chemistry, for the science of biometry has become one of the most

important adjuncts to the study of genetics.

_Comparative Anatomy and Embryology._

_Comparative Anatomy._—Upon the foundations laid down by Cuvier a

century ago the present elaborate structure of comparative anatomy of

animals, both vertebrate and invertebrate, has been developed. Vast as

is the present accumulation of facts and theories many important

problems still await their solution. Jeffries Wyman was long a leader in

this field, where many workers are now engaged.

_Embryology._—The embryological studies, so brilliantly begun by Von

Baer early in the nineteenth century, are still in progress. They have

now been extended to the groups more difficult of investigation and into

the earliest stages of fertilization and implantation in the mammals.

Artificial cultural methods have yielded important results. Louis and

Alexander Agassiz, Mark, Minot, Brooks, Whitman, Conklin and E. B.

Wilson have taken prominent parts in this work.

In the early nineties embryological studies were directed to the

arrangement of cells in the dividing egg, and there was much discussion

of “cell lineage” in development. Valuable as were these studies they

threw comparatively little light on the general problems of evolution.

_Experimental Embryology._—A more fertile field, developed at the same

period and a little later, was found in experimental embryology. The

discoveries made by Driesch and others in shaking apart the cells of the

dividing egg or by destroying one or more of these cells gave a new

insight into the potency of cells for compensatory and regenerative

processes. These studies attracted many able investigators, who made

still further advance by subjecting the germ cells, developing eggs,

embryos, and developing organs to a great variety of artificial

conditions.

_Artificial Parthenogenesis._—Another question concerns the nature of

the process of fertilization and the agencies which cause the fertilized

egg to develop into an embryo. In 1899 Jacques Loeb succeeded in causing

development in unfertilized sea-urchin eggs by subjecting them to

concentrated sea water for a period and then returning them to their

normal environment. To this promising field of experimental work came

many of the foremost biologists both in America and Europe. It was soon

found that the eggs of most groups of animals except the higher

vertebrates could be made to develop into more or less perfect embryos

and larval forms by treatment with a great variety of chemical

substances, by increased temperature, by mechanical stimuli and by other

means. This artificial parthenogenesis, as it is called, has also been

successful in plants (_Fucus_), and recently Loeb has reared several

frogs to sexual maturity by merely puncturing with a sharp needle the

eggs from which they were derived. Loeb, then, maintains that “the egg

is the future embryo and animal; and that the spermatozoon, aside from

its activating effect, only transmits Mendelian characters to the

egg.”[180]

Further experimental analyses of the nature of the fertilization

mechanism have recently been made by Morgan, Conklin, F. R. Lillie, and

others.

_Germinal Localization._—The question as to whether the egg contains

localized organ-forming substances has been studied experimentally

particularly by means of the centrifuge. The results indicate that

neither of the older opposing theories of “performation” or “epigenesis”

is applicable to all eggs, but that in certain organisms the eggs

possess a well marked differentiation while in others each part of the

egg is essentially, although probably not absolutely, equipotential.

_The Germplasm Cycle._—Since Weismann’s postulation of the independence

of soma and germplasm in 1885 many attempts have been made to trace the

path of the hereditary substance from one generation to the next. A

recent book by Hegner[181] summarizes the success attained in various

groups of animals.

_Cytology._

Another important field of investigation which has attracted many

workers is that which pertains to the life of the cell—the science of

cytology. Although the celltheory was established as early as 1839,

little advance was made in this subject in America before 1880. Since

that time, however, Americans have been so successful in cytological

discoveries that they are now among the world’s leaders in this field.

These studies have been followed along both descriptive and experimental

lines. The most prominent of the early workers in this field are E. L.

Mark and E. B. Wilson. Mark’s description of the maturation,

fecundation, and segmentation of the egg is the most accurate and

complete of the early cytological studies. Wilson’s discoveries

concerning the details of fertilization and his “Atlas of Fertilization

and Karyokinesis,” published in 1895, have now become classic. Wilson,

too, has published the only American text-book on cytology,[182] and has

more recently taken the lead in studies concerning the relation between

the chromosomes and sex. Besides Wilson, Montgomery, Mark, McClung,

Morgan, Miss Stevens, Conklin and their associates and students have now

furnished conclusive evidence that the sex of an organism is determined

by, or associated with, the nuclear constitution of the fertilized egg.

This constitution is moreover shown to be dependent upon the chromosomes

received from the germ cells.

This explanation is in strict accordance with the results of

experimental breeding. It is also quite in harmony with the Mendelian

law of inheritance, and in fact forms one of the strongest supports for

the view that all Mendelian factors are resident in the chromosomes.

Recent work has also discovered the mechanism which governs the

complicated conditions of sex which occur in those animals which exhibit

alternating sexual and parthenogenetic generations. These remarkable

processes are in all cases found to depend upon a definite distribution

of the chromosomes.

Other recent experimental work has shown that while the sex is thus

normally determined in the fertilized egg, it is in some animals not

irrevocably fixed, and the normal effect of the sex chromosomes may be

inhibited by abnormal conditions in the developing embryo, as is

demonstrated by the recent work of Lillie and others.

The cytological basis for Mendelian inheritance has been very

extensively studied by Morgan and his pupils in connection with their

work on inheritance in the common fruit fly _Drosophila_. The evidence

supports Weismann’s earlier hypothesis that the chromosomes are the

bearers of the heritable factors, and that these are arranged in a

series in the different chromosomes. This theory is shown to be in such

strict accord with both the cytological studies and the results of

experimental breeding that Morgan has ventured to indicate definite

points in particular chromosomes as the loci of definite heritable

factors, or genes.

Confirmation of this view is furnished by the behavior of the so-called

sex-linked characters, the genes for which are situated in the same

chromosome as that which carries the sex factor. Many ingenious breeding

experiments indicate further that all the hereditary characters in

_Drosophila_ are borne in four great linkage groups corresponding with

the four pairs of chromosomes which the cells of this fly possess.

_Comparative Physiology._

None of the experimental fields has been of greater importance in

zoological progress than that which concerns the functions of the

various organs. Without this companion science morphology and

comparative anatomy would have become unintelligible. American

investigators, among whom G. H. Parker stands prominent, have taken a

leading part in this field also.

_Neurology._—The physiological analysis of the components of the nervous

system, both in vertebrates and invertebrates, is another important

branch of experimental biology. The 28 volumes of the Journal of

Comparative Neurology attest the large influence that American

investigators have had in the development of this science.

_Regeneration._—Experimental studies on the powers of regeneration in

plants and animals have been made from the earliest times. During the

past few years, however, there has been made a concerted attempt to

analyze the factors which determine the amount and rate of regeneration.

Much progress has been made toward the postulation of definite laws

applicable to the regenerative processes of the parts of each organism.

The critical analyses of Morgan, Loeb and Child have been particularly

stimulating.

_Tissue Culture._—Another line of experimental work which has been

developed within the past few years by Harrison, Carrell, and others is

the culture of body tissues in artificial media. These experiments have

included the cultivation in tubes or on glass slides of the various

tissues of numerous species of animals. They have yielded much

information regarding the structure, growth and multiplication of cells,

the formation of tissues, and the healing of wounds.

_Transplantation and Grafting._—Closely associated experiments consist

in the transplantation of organs or other portions of the body to

abnormal positions, to the bodies of other animals of the same species

or of other species. In this way much has been learned about the

potentiality of organs for self-differentiation, for regulation, for

regeneration and for compensatory adaptations. The experiments have

shown, further, the independence of soma and germplasm and have revealed

the nature of certain organs whose functions were previously obscure.

_Tropisms and Instincts._—Another field of experimental biology concerns

the analysis of behavior of organisms in response to various forms of

stimuli. These studies are being prosecuted on all groups of organisms,

including the larval stages of many animals, and are yielding most

remarkable results. The success in this field of research is largely due

to stimulating influence of Jacques Loeb, Parker, Jennings, and their

co-workers.

_Biological Chemistry._—Still another experimental field which has

developed into one of the most important of the biological sciences

relates to the fundamental chemical and physical changes which underlie

all organic phenomena. A knowledge of both physiological and physical

chemistry is to-day essential for all advanced biological work. The

peculiar nature of life itself, of growth, disease, old-age,

degeneration, death and dissolution are presumably only manifestations

of chemical and physical laws. The ultimate goal of all experimental

biology, therefore, will be reached only when the basic physico-chemical

properties of life are understood. At that time only will the perennial

controversy between vitalism and mechanism be ended.

_Economic Zoology._

A moment’s reflection will show that economic biology is the most

essential of all sciences to the human welfare and progress. For man’s

relation to his environment is such that the penalty for ignorance or

neglect of the biological principles involved in the struggle for

existence quickly overwhelms him with a horde of parasites or other

enemies.

It is only by the intelligent application of biological knowledge that

our food supplies, our forests, our domesticated animals and our bodies

can be protected from the ever ravenous organisms which surround us.

The losses to food supplies and other products by insects alone amounts

to 100 millions of dollars a month in the United States. And the

parasites cause losses in sickness and premature deaths each year of

many millions more. Then there are the destructive rodents and other

animals which add largely to our burdens of support. These enemies next

to wars and fungi are the most destructive agencies on earth. Could they

but be eliminated man’s struggle against opposing forces would be in

large measure overcome. The results of recent work in economic zoology,

both in regard to the destruction of enemies and protection of useful

mammals, birds and fishes, furnish a bright outlook for the future.

_Protozoology._—Partly as an experimental field for the solution of

general biological problems and partly because of its practical

applications the study of protozoa has now developed into a special

science.

The results of the investigations of Calkins, Woodruff, Jennings and

others have greatly supplemented our understanding of the signification

of such important biological phenomena as reproduction, sexual

differentiation, conjugation, tropisms, and metabolism.

From an economic standpoint the protozoa have recently been shown to be

of the greatest importance because of the human and animal diseases for

which they are responsible.

_Parasitology._—The animal parasites of man, domesticated animals and

plants include numerous species of protozoa, worms, and insects.

Together with the bacteria and a few higher fungi they cause all

communicable diseases. When we consider that not only our health but

also our entire food supply is dependent upon the elimination of these

organisms we must admit that parasitology is the most important

economically of all the sciences.

The reports of the investigations of Stiles and his associates in the

Hygienic Laboratory and of Ransom and his staff in the Bureau of Animal

Industry are widely distributed by the federal government. The

systematic studies so ably begun by Joseph Leidy in the middle of the

last century have been continued by Ward, Linton, Pratt, Curtis and

others on the parasites of many groups of animals.

_Economic Entomology._—Another extremely important biological science,

the practical applications of which are second only to those of

parasitology in importance, is entomology. In the last few years

economic entomology has exceeded any of the other branches of biology in

the number of its investigators. The American Association of Economic

Entomologists has a membership of about five hundred. The work of most

of these is supported by appropriations from the State and federal

governments, and the results of their investigations are widely

published.

It is now well known that some of the protozoon parasites are conveyed

from man to man only through the bites of insects. The local eradication

of several of our most fatal diseases has recently been brought about by

the application of measures to destroy such insects. This is the

greatest triumph of economic zoology.

_Economic Ichthyology._—The U. S. Fish Commission has for many years

been actively engaged in investigations on the food fishes, including

methods for increasing the food supply by suitable protection and

artificial propagation. The work includes also edible and otherwise

useful mollusks and crustacea. Their marine and fresh-water laboratories

have also been of great service to general biological science.

_Economic Ornithology and Mammalogy._—In addition to the local bird

clubs and the American Ornithologists Union for the study and

preservation of bird and mammal life, the Bureau of Biological Survey

has for some years conducted investigations on the economic importance

of the various species. The publications of this Bureau are of great

value both in determining the economic status of our birds and mammals,

and also in recommending means for the protection of the beneficial

species and the destruction of the injurious. Several of the States

issue similar publications.

_Genetics._

One of the most interesting chapters in biology relates to the

development of the modern science of heredity, or genetics.

Previous to the year 1900, when the Mendelian principle of inheritance

was re-discovered, the relative importance of heredity and of

environment in the development of an organism was little understood. It

is true that Weismann had insisted on the independence of soma and

germplasm some years earlier (1883), but the body of the individual was

still generally considered the key to its inheritance.

The recognition of the general application of Mendel’s discovery gave a

great impetus to experimental breeding both in plants and animals. While

heretofore it had been necessary to depend upon the somatic characters

as evidence of the hereditary constitution of an individual, it now

became possible, knowing the hereditary constitution of the parents of

any pair of individuals, to predict with almost mathematical certainty

the characters of their possible offspring.

In general, the laws of possible chance combinations of any group of

characters determine the probability of any particular offspring

possessing one or many of those characters. The physical basis for such

Mendelian inheritance is evidently the chance combinations of

chromosomes which result from the processes of maturation and union of

the germ cells.

Certain limitations to the law are met with because the relatively small

number of chromosomes involves linkage of genes, because of the

occasional interchange of groups of genes between homologous

chromosomes, and because the relative activity or potency of any

particular gene may differ in different races, and, finally, because the

normal activity of any given gene may be modified or inhibited by the

action of other genes. It is by no means certain, however, that all

inheritance is Mendelian, for there still remains much evidence that the

hereditary basis of certain characters may be resident in the cytoplasm,

rather than in the chromosomes. A recent book by Morgan, Sturtevant,

Müller and Bridges (1915), entitled “the mechanism of Mendelian

heredity” gives the cytological explanation of Mendelian inheritance.

Americans have from the first taken a leading part in this field of

research and have been quick to recognize its practical applications to

the improvement of breeds in both animals and plants. This prominent

position is largely due to the experimental work of Castle, Davenport,

Morgan, Jennings, Pearl, and their co-workers on animals and that of

East, Emerson, Davis, Hayes and Shull on plants.

The geneticist now realizes that the appearance of the body (phenotype)

gives but little clue to the inheritance (genotype). That two white

flowers produce only purple offspring, or two white fowls only deeply

colored chickens, or that a pair of guinea pigs, one of which is black

and the other white, have only gray agouti offspring, while other

apparently similar white flowers or white animals produce offspring like

themselves, is now readily comprehensible and mathematically

predictable.

The most important application of our newly acquired knowledge of

inheritance is in the improvement of the human race. The wonderful

opportunity in this direction must be apparent to all. The welfare of

humanity depends upon the immediate adoption of eugenic principles. The

Eugenics Record Office has secured many of the essential data.

With the destruction of the world’s best germ plasm at a rate never

equalled before, the outlook for the future race would be appalling were

it not for the hope that with the advent of a righteous peace will come

a realization of the necessity of applying these new biological

discoveries to improving the races of men. That the discoveries have

been made too late in the world’s history to be of such use to humanity

must not be thought possible.

_Evolution._

Previous to the publication of Darwin’s “Origin of Species” in 1859,

American zoologists were generally inclined toward special creation, in

spite of the evidences for evolution which had been presented by Erasmus

Darwin, Buffon, Lamarck, and Geoffroy St.-Hilaire. This attitude of mind

continued for some years after the publication of the natural selection

theory of Darwin and Wallace. This was in part due to the powerful

influence of Louis Agassiz and others who bitterly opposed the Darwinian

theory. The influence of Asa Gray in gaining a general acceptance for

this theory is explained in the following chapter.

A modified Lamarckian doctrine was widely accepted in the last quarter

of the century, due largely to the influence of Cope, Hyatt and Packard.

The inheritance of “acquired characters” demanded by this theory seems

incompatible with the discoveries of recent times, so that “to-day the

theory has few followers amongst trained investigators, but it still has

a popular vogue that is wide-spread and vociferous.”[183]

The origin of new varieties and species by accidental and fortuitous

modifications (mutations) of the germplasm is now the most widely

accepted theory of evolution.

Some of the most important discoveries regarding the origin of new forms

have been recently made by Morgan and his pupils. From a stock of the

common fruit fly (_Drosophila ampelophila_) more than 125 new types have

arisen within six years. Each of these types breeds true. “Each has

arisen independently and suddenly. Every part of the body has been

affected by one or another of these mutations.” To arrange these

mutations arbitrarily into graded series would give the impression of an

evolutionary series, but this is directly contrary to the known facts

concerning their origin, for each mutation “originated independently

from the wild type.” “Evolution has taken place by the incorporation

into the race of those mutations that are beneficial to the life and

reproduction of the individual.” This evolutionary process is usually

accompanied by the elimination of those forms which have remained stable

or which have developed adverse mutations.

A question that is being vigorously debated at this time concerns the

possible effects of selection on the hereditary factors. Are the genes

fixed both qualitatively and quantitatively or does a given gene vary in

potency under different conditions and in different individuals? In the

former case selection can only separate the existing genes into separate

pure strains. But if the gene be quantitatively variable, then selection

will result in the establishment of new types.

Castle has long stoutly maintained the effect of such selection, and his

forces have recently been augmented by Jennings. The experimental work

now in process will doubtless yield a decisive answer.

_Conclusion._

A comparison of the simple descriptive natural history of a century ago

with the foregoing manifold developments of modern biology will indicate

the wonderful progress which has occurred during this period. The path

has led from the crude methods of the almost unaided eye and hand to the

applications of the most delicate experimental apparatus. For the

marvelous success which zoology has attained has been possible only by

the skillful use of scalpel, microscope, microtome and other mechanical

devices and by the refined methods of the chemist and physicist.

The central truth to which all these discoveries consistently point is

the unity and harmony of all biological phenomena, and indeed of all

nature. No longer does the zoologist find any demarcated line separating

his field of research from that of the botanist or the chemist or even

of the physicist, for all the natural sciences obviously deal with

closely associated phenomena. The aim of the future will be both to

complete fields of study already marked out and to derive a

comprehensive explanation of the general principles involved.

_Notes._

Footnote 172:

Proc. Biol. Soc. Washington, =3=, 35, 1886.

Footnote 173:

Ibid., =4=, 9, 1888. Both of these papers are reprinted in Ann. Rept.

Smithsonian Inst., 1897, U. S. Nat. Mus., Pt. 2, pp. 357–466, 1901.

Footnote 174:

Louis Agassiz: his Life and Correspondence, by Elizabeth Carey

Agassiz, p. 145, 1885.

Footnote 175:

List of North American Land Mammals in the United States National

Museum, 1911. Bull. 79, U. S. Nat. Mus., 1912.

Footnote 176:

Birds of North and Middle America, Bull. 50, parts I-VII, U. S. Nat.

Mus., 1901–1916.

Footnote 177:

Report U. S. Nat. Mus. for 1898, pp. 153–1270, 1900.

Footnote 178:

Bull. 34, U. S. Nat. Mus., 1889.

Footnote 179:

Bull. 47, parts I-IV, U. S. Nat. Mus., 1896–1900.

Footnote 180:

J. Loeb, The Organism as a Whole, p. 126, 1916.

Footnote 181:

The Germ-cell Cycle in Animals, 1914.

Footnote 182:

The Cell in Development and Inheritance, 1896; second edition, 1900.

Footnote 183:

Morgan, T. H. A critique of the theory of evolution, p. 32, 1916.

XIII

THE DEVELOPMENT OF BOTANY SINCE 1818