50 



GERTRUDE M. WHITE 



wide and three inches deep with straight sides. A piece of 

 rubber tubing connecting with a faucet was attached to the 

 center of one end, in such a way that a current of uniform in- 

 tensity flowed through the whole length of the trough; at the 

 other end, was an outlet covered with netting to prevent the 

 loss of the fish. 



After testing various strengths of current, the one which 

 brought about the greatest number of reactions was found to 

 be that which carried carmine solution the length of the trough 

 in half a minute. Therefore, this strength of current was used 

 in most of the experiments. Since all tests were made in a 

 dark room, it was a simple matter to turn on the faucet a cer- 

 tain distance with the room in total darkness, in that way elim- 

 inating all reactions to light. Nevertheless, since it was found 

 that the daylight had little effect on the results, the room was 

 not darkened for all the experiments. 



Nearly all stages of young Brook Trout from the time of hatch- 

 ing to the absorption of the yolk sac were tested. Table 1 shows 

 some of the results. 



TABLE 1 

 Showing the Reactions of Brook Trout to Current 



The fish were placed in the trough one at a time in most cases, 

 with right and left sides alternately toward the current before 

 the water was turned on. The fact that the older trout showed 

 a slightly smaller percentage of positive reactions is probably 

 not significant, as there appears to be no difference in their 

 reactions, except such as would be caused by their greater 

 activity and strength. Although it is not recorded in table 1, 

 embryos which had just been hatched were found to react posi- 



