r 



OCTOBEB 18, 1907] 



SCIENCE 



503 



unicellular plants under the general term 

 Protista. One of the prominent features 

 of this idea was accepted by Thomas Henry 

 Huxley (1874) with, however, the very 

 important modification of retaining the old 

 name Protozoa as the collective name of 

 the animals and taking a suggested name 

 of Haeckel's (Metazoa) for the multicel- 

 lular animals. 



GRADUAL DELIMITATION OF GENERA 



As has been already noted, the animal 

 genera of Linne were mostly extremely 

 comprehensive, answering, when natural 

 groups, to families, superfamilies, and even 

 orders or classes of modern naturalists. 

 Such contrast, however, with others of the 

 Linnffian genera, and when this fact became 

 recognized and it was discovered that the 

 large genera embraced types exhibiting 

 many differences in detail, the latter were 

 subdivided; early in the past century, at 

 first owing especially to French and Ger- 

 man naturalists, the subdivision of old 

 genera on approximately present lines was 

 commenced and applied at different times 

 to various classes. It is noteworthy that 

 in some instances the authors of the new 

 genera c^uite abruptly changed their minds 

 regarding the nature of such groups. For 

 example, Laoepede, in 1798, in the closing 

 lecture of his course at the Museum of 

 Natural History, recognized only 51 genera 

 of mammals, but a few months later (in 

 1799), in a "tableau," admitted and de- 

 fined 84 genera. 



It seems to be generally supposed that 

 there has been an uninterrupted tendency 

 among zoologists to refinement and increase 

 of number of genera to the present time, 

 but such is by no means the case. Half 

 a century ago and more some ornithologists 

 subdivided old genera and made new ones 

 to an extent to which none of the present 

 time is prepared to go. For example, 

 Charles Bonaparte, Prince of Canino, re- 



quired eleven genera of gulls to include 

 those now congregated in one. About the 

 same time, some herpetologists were equally 

 radical. Leopold J. F. J. Fitzinger, in 

 1843, distributed species which are now 

 combined by all in the genus Anolis among 

 no less than fifteen genera. The genus 

 Bufo, as now understood, was split by some 

 herpetologists into a dozen or more. These 

 are only samples of numberless analogous 

 cases. 



THE OLD AND THE NEW 



A comparison of systematic zoology at 

 its dawn with that of the present time is 

 rather a contrast of different themes. 



The old naturalists believed that all 

 species of animals were created as such by 

 a divine fiat ; the modern consider that all 

 animals are derivatives from former ones 

 and that their differences have been ac- 

 quired during descent and development. 



The Linnteans based their systems on 

 superficial characteristics, and the moderns 

 take into consideration the entire animal. 



The early systematists assumed that 

 characters drawn from structures or parts 

 most useful to the animals were the best 

 guides to the relationship of the animals; 

 the latest ones have learned to distrust the 

 evidential value of similarity of structures 

 unaccompanied by similarity of all parts. 

 The former were guided mainly by physio- 

 logical characters ; the latter take morpho- 

 logical ones. 



The LinniEans confined their generaliza- 

 tions to few categories— genera, orders, 

 classes ; the moderns exhibit the manifold 

 modifications and coordinations of all 

 structural parts in many categories — 

 genera, subfamilies, families, superfami- 

 lies and various higher groups. 



The old naturalists believed more or less 

 in the existence of a regular chain of 

 beings from high to low; the new ones 



