6 GENERAL PRINCIPLES OF ZOOLOGY 



This neglect of the systematic side is further shown in the fact that the 

 great philosopher is satisfied with two systematic categories, with etSos, 

 species or kind, and yeVos or group. His eight yevrj //.eyio-ra would about 

 correspond with the Classes of modern zoology; they have been the start- 

 ing-point for all later attempts at classification, and may therefore be 

 enumerated here: i. Mammals (OJOTOKOVVTO. ev auroTs) . 2. Birds (opvi0es). 

 3. Oviparous quadrupeds (rerpaTroSa woroKoiWa) . 4. Fishes (t^ves) . 

 ^. Molluscs (/xaAaKia). 6. Crustaceans (/mAa/co'crT-para) . 7. Insects 

 (evro/Aa). 8. Animals with shells (oo-TpaKoSep/iaTo). Aristotle also noticed 

 the close connection of the first four groups, since he, without actually 

 carrying out the division, contrasted the animals with blood, erat^o. (better, 

 red blood), with the bloodless, avai/u.a (better, colorless blood or no 

 blood at all). 



DEVELOPEMENT OF SYSTEMATIC ZOOLOGY. 



Pliny. It is a remarkable fact that after Aristotle, an exclusively 

 systematic direction should have been taken. This is explicable only 

 when we consider that the continuity of investigation was interrupted by 

 the decline and ultimate complete collapse of ancient civilization, and by 

 the triumphant advance of Christianity. The decay is seen in the writings 

 of Pliny. Although this Roman scholar was long lauded as the foremost 

 zoologist of antiquity, he is now given the place of a not even fortunate 

 compiler, who collected from the writings of others the accurate and 

 the fabulous indiscriminately, and replaced the natural classification 

 according to structure by the unnatural division according to the place 

 of abode (flying animals, land animals, water animals). 



Zoology of the Middle Ages. The rise of Christianity resulted in 

 the complete annihilation of science and investigation. Then came a 

 time when answers to questions capable of solution by the simplest obser- 

 vation were sought by rummaging of the works of standard authors. 

 How many teeth the horse has, was debated in many polemics, which 

 would have led to bloodshed if one of the authors had not thought 

 to look into a horse's mouth. Significant of this mental bias which 

 prevailed throughout the entire Middle Ages is the 'Physiologus' or 

 'Bestiarius,' from which the zoological authors of the Middle Ages 

 drew much material. The book in its various editions names about 

 seventy animals, among them many creatures of -fable: the dragon, 

 the unicorn, the phoenix, etc. Most of the accounts given of 

 various animals are fables intended to illustrate religious or ethical 

 teachings. There are indeed, exceptions to this general characteristic of 



