320 GENERAL ZOOLOGY 



never talks to himself. As Huxley says of the crayfish, he " has 

 nothing to say to himself or anyone else." He does not reflect ; 

 he makes no generalizations. All his thinking is in the present 

 and in concrete terms. He has no voluntary attention, no voli- 

 tion in the true sense, no self-control. 



The food of the young perch at first consists entirely of 

 small, delicate crustaceans, such as Cyclops and its allies ; 

 from the time the perch are about an inch and a half in 

 length they begin to add insects to the bill of fare. Adult 

 perch have a still more varied diet, consisting of the larger 

 crustaceans, mollusks, and other fishes. The young are 

 gregarious, and those of about the same size tend to keep to- 

 gether, so that every farmer boy knows his chances of catch- 

 ing "a big one" are small indeed when he has his hook in a 

 swarm of little fishes. He has, however, this consolation, — 

 that the supply of the one size is likely to last ; for 



Perch, like the Tartar clans, in troops remove, 

 And, urged by famine or by pleasure, rove ; 

 But if one prisoner, as in war, you seize, 

 You'll prosper, master of the camp, with ease 

 For, like the wicked, unalarmed they view 

 Their fellows perish, and their path pursue. 



Oppian, Halientica 



