134 HISTOBICAL EEYIEW. 



continents became known. In consequence of these extended obser- 

 vations and a continually growing eagerness to collect curiosities from 

 foreign countries, the zoological material increased so largely that, 

 in the absence of precise distinctions, nomenclature and arrangement, 

 the danger of error was great, and a general review of the facts 

 almost impossible. Tinder such conditions, the appearance of the 

 systematiser Carl Linnaeus (1707 1778) must have been of the 

 greatest importance for the further development of Zoology. 



Kay, who is justly placed in the first rank of Linnaeus' prede- 

 cessors, had earlier endeavoured to acquire a basis for the systematic 

 treatment, and with a certain amount of success, but he failed to 

 organise a thoroughly methodical arrangement. He was the first 

 to introduce the conception of " species " and to consider anatomical 

 characters as the basis of classification. In his work, entitled 

 " Synopsis of Mammalia and Reptilia " (1693), he adopted Aristotle's 

 division of the animal kingdom into animals with and animals 

 without blood. With regard to the first he laid the basis of the 

 definitions of Linnaeus' first four classes ; the latter he divided into 

 a greater group, containing Cephalopods, Crustacea, and Testacea, 



rnd into a smaller containing the Insecta. 

 The importance of Linnaeus' work to the development of science 

 depended not on any far-reaching investigations or important dis- 

 coveries, but on his acute sifting and exact division of the then exist- 

 ing facts, and on the introduction of a new method of more certain 

 diagnosis, nomenclature, and arrangement. 



By erecting for groups of different value a series of categories 

 based on the ideas of species, genus, order, class, he obtained a means 

 of creating a much more precise system of classification. On the 

 other hand, by the introduction of the principle of binary nomencla- 

 ture, he obtained a fixed and more certain method. Every animal 

 received two names taken from the Latin language the generic 

 name, which was placed first, and the specific name, which together 

 denote the fact that the animal in question belongs to a definite 

 genus and species. In this way Linnaeus not only arranged the 

 facts then known, but also created a systematic framework in which 

 later discoveries would easily find their proper place. 



Linnreus's great work, the " Systema Naturae," which in its thirteen 

 editions received many changes, embraced the animal, vegetable, and 

 mineral kingdoms, and in its treatment can only be compared to an 

 exhaustive catalogue, in which the contents of nature, like that 

 of a library, are registered in a definite order with a statement of 



