4 THE BEGINNINGS OF COMPARATIVE ANATOMY 



describes more than 500 kinds. 1 Not only does he know 

 the ordinary beasts, birds, and fishes with which everyone is 

 acquainted, but he knows a great deal about cuttlefish, snails 

 and oysters, about crabs, crawfish (l\i/i/uints}, lobsters, 

 shrimps, and hermit crabs, about sea-urchins and starfish, 

 sea-anemones and sponges, about ascidians (which seem to 

 have puzzled him not a little ! ). He has noticed even fish- 

 lice and intestinal worms, both flat and round. Of the 

 smaller land animals, he knows a great many insects and 

 their larvae. The extent of his anatomical knowledge is 

 equally surprising, and much of it is clearly the result of 

 personal observation. No one can read his account of the 

 internal anatomy of the chameleon (Hist. At/ini., ii.), or his 

 description of the structure of cuttlefish (Hist. Auini., iv.), or 

 that touch in the description of the hermit crab (Hist. Ani>u., 

 iv.) "Two large eyes . . . not . . . turned on one side like 

 those of crabs, but straight forward" -without being con- 

 vinced that Aristotle is speaking of what he has seen. 

 Naturally he could not make much of the anatomy of small 

 insects and snails, and, to tell the truth, he docs not seem to 

 have cared greatly about the minutiae of structure. Me was 

 too much of a Greek and an aristocrat to care about laborious 

 detail. 



Not only did he lay a foundation for comparative anatomy, 

 but he made a real start with comparative embryology. 

 Medical men before him had known many facts about human 

 development ; Aristotle seems to have been the first to study 

 in any detail the development of the chick. He describes 

 this as it appears to the naked eye, the position of the 

 embryo on the yolk, the palpitating spot at the third day, the 

 formation of the body and of the large sightless eyes, the 

 veins on the yolk, the embryonic membranes, of which he 

 distinguished two. 



& 1 



(2) Aristotle had various systems of classifying animals. 

 They could be classified, he thought, according to their 

 structure, their manner of reproduction, their manner of life, 

 their mode of locomotion, their food, and so on. Thus you 



1 T. E. Lones, Aristotle's Researches in A<itur<il Science, pp. 8^-3, 

 London, 



