ARISTOTLE. 29 



illustrated. At the close of this book Aristotle has some 

 remarks on milk, and mentions the occasional appearance 

 of milk in male animals. He speaks of a male goat at 

 Lemnos which yielded so much that cakes of cheese 

 were made from it. Similar instances of this phenomenon 

 have been recorded by Humboldt, Burdach, Geoffroy 

 St. Hilaire, and others. 



In the first four chapters of the fourth book the 

 anatomy of the invertebrata is dealt with, and the accounts 

 given of certain mollusca and Crustacea are very careful 

 and minute. The rest of the book is devoted to a de- 

 scription of the organs of sense and voice ; of sleep, and 

 the distinctions of sex. The accurate knowledge which 

 Aristotle exhibits of the anatomy and habits of marine 

 animals, such as the Cephalopoda and the larger Crus- 

 tacea, leaves no doubt that he derived it from actual 

 observation. Professor Owen says, " Respecting the living 

 habits of the Cephalopoda, Aristotle is more rich in detail 

 than any other zoological author." What is now spoken 

 of as the hectocotylization of one or more of the arms 

 of the male cephalopod did not escape Aristotle's eye. 

 And while he speaks of the teeth and that which serves 

 these animals for a tongue, it is plain from the context 

 that he means in the one case the two halves of the 

 parrot-like beak, and in the other the anterior end of the 

 odontophore. 



Books five to seven deal with the subject of generation. 



