8o Bulletin of Laboratories of Denison University. [Voi. xii 



the bottom. When food particles are located,' they are 

 snapped up by a quick lateral movement similar to that of the 

 cat fishes. Sometimes, however, stimulus of the ventral fins is 

 followed by a reversed swimming movement, the fish backing 

 up to take the bait. At other times the fish when exploring 

 the bottom swims slowly backwards, so that no change of di- 

 rection is necessary when food is located. 



I made a series of tests with cotton wool and cotton 

 dipped in clam juice similar to those described for the hake and 

 with the same results. I also repeated the tests made with sea 

 water and with strained clam juice by the aid of a pipette, with 

 identically the same results as with the hake. After a few tests 

 the fishes ignore sea water and plain cotton, but invariably re- 

 spond to cotton soaked in clam juice and to the juice itself as 

 they do to meat. The tom cod reacts to bits of clear gelatin 

 soaked up in water essentially as the hake does. 



I also tested the tom cod with hydrochloric acid, 0.2% in 

 distilled water and i % in sea water. Both are obviously 

 avoided. I filled a fine pipette with a solution of quinine sul- 

 phate in sea water, about o. i % — a very bitter solution. The 

 tom cod swims away immediately if applied either to the lips or 

 to the pelvic fins, but appears not to notice it if applied to other 

 parts of the body. 



Within two old clam shells which had been lying in the 

 tank with the tom cods for several days and had remained un- 

 noticed was placed a piece of fresh clam. They were then 

 closed together and laid on the bottom of the aquarium con- 

 taining a tom cod. Shortly the fish passed near it, appeared to 

 perceive it, turned from his course and passed and repassed the 

 spot until the shell was located, apparently by smell, by a 

 method of "trial and error," Then he rooted at the shell vig- 

 orously until the two halves were separated and he could get 

 the meat. I repeated this with a piece of squid within the 

 shells with the same result. I tried two empty shells in the 

 same way. He saw me put them into the water, came up to 

 investigate, smelled(?) of the shells, and went away without so 

 much as touching them and never came back to them again. 



