90 Bullctm of Laboratories of Denison University. [Voi. xii 



tance of the tactile and gustatory elements of the sensation com- 

 plex in the normal reflex life of the fish. 



It would be interesting to inquire the part played by 

 memory in these reactions. In the case of Ameiurus, where 

 the tactile and gustatory elements of the reflex ot seizing food 

 can be experimentally isolated by training, it would doubtless 

 be possible to measure quantitatively the duration of the per- 

 sistence of this acquired discrimination. I have made no accu- 

 rate observations on this point, but can say in general that the 

 memory of these fishes seems to be fairly good. (By the term 

 memory I do not mean to prejudice the question of the part 

 played by consciousness here. The original reaction may be 

 largely or wholly an unconscious or automatic response and the 

 "memory" may be an organic memory more closely allied to 

 habit.) At the beginning of the tests with cotton the cat fishes 

 generally seized the cotton just as they did the meat. At the 

 close of the first day's experiments they had learned to ignore 

 the cotton as a rule, and half an hour after the close of this se- 

 ries of tests they still would pay small attention to the cotton ; 

 but by the day following, if tested first with meat, they would 

 take the cotton for a few times or would react to it slightly 

 during the first few tests, but would learn to let it alone sooner 

 than on the first day. But toward the close of the experiments 

 after several weeks of practice I rarely got any reaction at all 

 with the cotton under any circumstances, even if the fishes had 

 not been tested for several days. With the gadoids the num- 

 ber of experiments was much smaller and they were continued 

 for a shorter time, but I never got so good evidence of memory 

 of the discrimination. On successive days the tests were much 

 alike. The inability of the tom cod to remember to ignore a 

 tactile contact which is not followed by satisfaction so long as 

 the cat fish remembers a similar discrimination I take to be an 

 indication that the tactile element plays a much larger part in 

 the reflex complex in the gadoids. The known distribution of 

 the terminal buds favors this view also, for while they are very 

 abundant on the barblets and body of the cat fish they are 

 rather sparse on the free fins of the gadoids and the general cu- 



