56 GERTRUDE M. WHITE 



to notice it, at least they were not observed to eat. A stream 

 of meat juice directed against the body was avoided in the 

 same manner as a jet of clean water. After a week or less, 

 however, the trout began to take bits of food into their mouths 

 as they chanced upon them and often to swallow them. From 

 this time on they were observed to dart after pieces of meat 

 floating about in the water, although they often rested directly 

 upon meat lying on the bottom without appearing to pay any 

 attention to it. They were also seen to chase bubbles and bits 

 of filter paper, and to take them into their mouths, but they 

 never swallowed them. The fish were fed in dishes with black 

 or white bottoms. The trout were found to take food more 

 eagerly from the dishes with black bottoms where the food was 

 more plainly visible, although they would also eat pieces of 

 meat over the white backgrounds. This fact is made use of by 

 the fish-hatchers who feed the larvae in blackened troughs. 



In order to discover what part is played by the chemical 

 sense in helping the Brook Trout to find its food, a bag con- 

 taining meat was placed in the water; this was nosed by the 

 trout and one fish bit at it. At other times two bags, one with 

 food and one without it, were set in the dish. The trout inves- 

 tigated both bags, but they bit at neither. They were appar- 

 ently unable to discover meat hidden under a paper in the 

 bottom of the dish. Although they wandered over it as they 

 swam about, it was not noted that its presence had any effect 

 upon the fish. 



The Brook Trout apparently first react through sight to the 

 presence of food, since they were often observed to leave pieces 

 of meat near them to dart after bits farther away, which would 

 not be the case, were it the chemical sense which was most 

 strongly stimulated. The gustatory sense appears to determine 

 whether or not the food is swallowed. 



C. GENERAL DESCRIPTION OF THE EARLY LIFE OF THE 



BROOK TROUT 



Let us follow a developing Brook Trout on the pebbly bottom 

 of a swift flowing stream. During the first six weeks of its 

 existence it does not move far from the spot where it was hatched, 

 but lies quietly in the shadows among the stones, out of sight 

 of its enemies. It is not affected by objects passing over head. 



