ARISTOTLE AS A BIOLOGIST 19 



yolk-sac, attached (in apparent contrast to the chick's) 

 to the little creature's developing head. 



But there is one other remarkable structure that he 

 knew, centuries before it was rediscovered almost in our 

 own time. In certain male cuttle-fishes, in the breeding 

 season, one of the arms develops in a curious fashion 

 into a long coiled whip-lash, and in the act of breeding 

 may then be transferred to the mantle-cavity of the female. 

 Cuvier himself knew nothing of the nature or the function 

 of this separated arm, and indeed, if I am not mistaken, 

 it was he who mistook it for a parasitic worm. But 

 Aristotle tells us of its use and its temporary development, 

 and of its structure in detail, and his description tallies 

 closely with the accounts of the most recent writers. 



Among the rarer species of the group he knew well the 

 little Argonaut, with its beautiful cockle-shell, and tells 

 how it puts up its two broad arms to sail with, a story 

 that has been rejected by many, but that after all may 

 perhaps be true. 



Now in all this there is far more than a mass of frag-" 

 mentary information gleaned from the fishermen. It is 

 a plain orderly treatise, on the ways and habits, the 

 varieties, and the anatomical structure of an entire 

 group. Till Cuvier wrote there was none so good, and 

 Cuvier lacked knowledge that Aristotle possessed. 



Not less exact and scarcely less copious is the chapter 

 in which Aristotle deals with the crab and lobster, and 

 all such crustacean shell-fish, nor that in which he 

 treats of insects, after their kind. Most wonderful of all, 

 perhaps, are those portions of his books in which he 

 speaks of fishes, their diversities, their structure, their 

 wanderings, and their food. Here we may read of fishes 

 that have only recently been rediscovered, 1 of structures 



1 e.g. Parasilurus A ristotelis, a siluroid fish of the Achelous. 



