Page:EB1911 - Volume 28.djvu/1052

CLASSIFICATION]

It is unnecessary to follow in this article all these subjects, since they are for the most part treated under separate headings, not indeed under these names—which are too comprehensive for that purpose—but under those of the more specific questions which arise under each. Thus Bionomics is treated in such articles as, , , , , , &c.; Zoo-dynamics under , , , , , and allied articles; Plasmology under , , &c.; and Philosophical Zoology under numerous headings, , , &c. See also, , , , &c.

It will be more appropriate here, without giving what would be a needless repetition of considerations, both historical and theoretical, which appear in other articles, to confine ourselves to two general questions, (1) the history of the various schemes of classification, or Morphography, and (2) the consideration of the main tendencies in the study of zoology since Darwin.

Morphography includes the systematic exploration and tabulation of the facts involved in the recognition of all the recent and extinct kinds of animals and their distribution in space and time, (1) The museum-makers of old days and their modern representatives the curators and describers of zoological collections, (2) early explorers and modern naturalist-travellers and writers on zoo-geography, and (3) collectors of fossils and palaeontologists are the chief varieties of zoological workers coming under this head. Gradually since the time of Hunter and Cuvier anatomical study has associated itself with the more superficial morphography until to-day no one considers a study of animal form of any value which does not include internal structure, histology and embryology in its scope.

The real dawn of zoology after the legendary period of the middle ages is connected with the name of an Englishman, Edward Wotton, born at Oxford in 1492, who practised as a physician in London and died in 1555. He published a treatise De differentiis animalium at Paris in 1552. In many respects Wetton was simply an exponent of Aristotle whose teaching, with various fanciful additions, constituted the real basis of zoological knowledge throughout the middle ages. It was Wotton’s merit that he rejected the legendary and fantastic accretions, and returned to Aristotle and the observation of nature.

The most ready means of noting the progress of zoology during the 16th, 17th and 18th centuries is to compare the classificatory conceptions of successive naturalists with those which are to be found in the works of Aristotle himself. Aristotle did not definitely and in tabular form propound a classification of animals, but from a study of his treatises Historia animalium, De generatione animalium, and De partibus animalium the following classification can be arrived at:—

A.  , blood-holding animals ( = Vertebrata).
 * 1. , viviparous Enaema (= Mammals, including the Whale).
 * 2. , ( = Birds).
 * 3. , four-footed or legless Enaema which lay eggs (= Reptiles and Amphibia).
 * 4.  ( = Fishes).

B.  , bloodless animals ( = Invertebrata).
 * 1. , soft-bodied Anaema ( = Cephalopoda).
 * 2. , soft-shelled Anaema ( = Crustacea).
 * 3. , insected Anaema or Insects ( = Arthropoda, exclusive of Crustacea)
 * 4. , shell-bearing Anaema ( = Echini, Gastropoda and Lamellibranchia).

Wotton follows Aristotle in the division of animals into the Enaema and the Anaema, and in fact in the recognition of all the groups above given, adding only one large group to those recognized by Aristotle under the Anaema, namely, the group of Zoophyta, in which Wotton includes the Holothuriae, Star-Fishes, Medusae, Sea-Anemones and Sponges. Wotton divides the viviparous quadrupeds into the many-toed, double-hoofed and single-hoofed. By the introduction of a method of classification which was due to the superficial Pliny depending, not on structure, but on the medium inhabited by an animal, whether earth, air or water Wotton is led to associate Fishes and Whales as aquatic animals. But this is only a momentary lapse, for he broadly distinguishes the two kinds.

The Swiss professor, Konrad Gesner (1516–1565), is the most voluminous and instructive of these earliest writers on systematic zoology, and was so highly esteemed that his Historia animalium was republished a hundred years after his death. His great work appeared in successive parts—e.g. Vivipara, ovipara, aves, pisces, serpentes et scorpio—and contains descriptions and illustrations of a large number of animal forms with reference to the lands inhabited by them. Gesner’s work, like that of John Johnstone (b. 1603), who was of Scottish descent and studied at St Andrews, and like that of Ulysses Aldrovandi of Bologna (b. 1522), was essentially a compilation, more or less critical, of all such records, pictures and relations concerning beasts, birds, reptiles, fishes and monsters as could be gathered together by one reading in the great libraries of Europe, travelling from city to city, and frequenting the company of those who either had themselves passed into distant lands or possessed the letters written and sometimes the specimens brought home by adventurous persons.

The exploration of parts of the New World next brought to hand descriptions and specimens of many novel forms of animal life, and in the latter part of the 16th century and the beginning of the 17th that careful study by “specialists” of the structure and life-history of particular groups of animals was commenced,which, directed at first to common and familiar kinds, was gradually extended until it formed a sufficient body of knowledge to serve as an anatomical basis for classification. This minuter study had two origins, one in the researches of the medical anatomists, such as Fabricius (1537–1619), Severinus (1580–1656), Harvey (1578–1657), and Tyson (1649–1708), the other in the careful work of the entomologists and first microscopists, such as Malpighi (1628–1694), Swammerdam (1637–1680), and Hook (1635–1702). The commencement of anatomical investigations deserves notice here as influencing the general accuracy and minuteness with which zoological work was prosecuted, but it was not until a late date that their full influence was brought to bear upon systematic zoology by Georges Cuvier (1769–1832).

The most prominent name between that of Gesner and Linnaeus in the history of systematic zoology is that of John Ray (1628–1705). A chief merit of Ray is to have limited the term “species” and to have assigned to it the significance which it bore till the Darwinian era, whereas previously it was loosely and vaguely applied. He also made