70 ARISTOTLE. 



tain ; although it is plain that they sleep, as do the 

 aquatic animals, fishes, mollusca, testacea, and Crus- 

 tacea. A transition is then made to the subject of 

 sex, for the purpose of showing that in the mollusca, 

 Crustacea, testacea, and eels, there is no difference in 

 that respect between individuals of the same species. 



The subjects of generation and parturition occupy 

 the fifth, sixth, and seventh books. From the com- 

 paratively large space which lie has devoted to the 

 result of his inquiries in these departments, the 

 minuteness with which he describes the phenomena 

 presented by them in man and the domestic ani- 

 mals, and the accurate knowledge which he fre- 

 quently exhibits, it may be inferred that they were 

 favourite subjects with Aristotle. It is sufficient 

 for our purpose to mention some of the cases in 

 which he attained the truth, and others in which 

 he failed. 



He describes the membranes with which some 

 of the mollusca envelope their eggs, mentions the 

 changes through which insects pass before they ac- 

 quire the perfect state, and speaks with toleral)le ac- 

 curacy of the economy of bees and wasps. He states, 

 however, that the former make wax from flowers, but 

 gather their honey from a substance w liich falls from 

 the air upon trees. The eggs of tortoises, he says, 

 are hard, like those of birds, and are deposited in 

 the ground. His remarks on those of lizards and 

 the crocodile are also correct. He states accurately 

 that some serpents bring forth their young enclosed 

 in a soft membrane, which they afterwards burst ; 

 but that sometimes the little animals escape from 

 the egg internally, and are produced free. Other ser- 

 pents, he observes, bring forth eggs cohering in the 



