EAR OF THE SQUETEAGUE. 1217 



lost orientation and would even rest on their sides on the bottom of the aqua- 

 rium. In only such fishes as responded to the tapping and swam upright after 

 the blinders had been put on them were the utriculus and the semicircular 

 canals destroyed. The following records from one of the five sets of fishes 

 tested will give a fair idea of the results of these experiments: 



Fish No. I was operated upon for the destruction of the right and left 

 utriculi and the semicircular canals. After the operation the fish swam irreg- 

 ularly, often revolving on its long axis. It died about three hours after the 

 operation. Dissection showed extensive hemorrhages within the cranium. 



Fish No. 2 was subjected to the same operation as No. i . After the oper- 

 ation the fish swam irregularly for about half an hour. It then reassumed 

 normal equilibrium both in resting and in swimming. Five hours after the 

 operation it still swam normally. The blinders were then put on it and it lost 

 equilibrium and swam in irregular spirals, but it regained its equilibrium as 

 soon as the blinders were removed. This test was repeated several times during 

 the next few hours and always with the same results. During this period the 

 fish was also placed several times in the wooden aquarium ; it always responded 

 normally to the taps of the mallet on the aquarium wall. At all times after the 

 operation the locomotor movements of the fish were weaker than they had been 

 before the utriculus was destroyed, a condition that made it much easier to 

 catch the fish in a hand net after the operation than before it. The fish retained 

 its power of orientation till about the time of its death, thirty-two hours after 

 the operation. On dissection the utriculi and semicircular canals were found 

 to be cut through in many places, but the sacculi and brain were intact. 



Fish No. 3 was subjected to the same operation as No. i. The fish swam 

 irregularly and rested in unusual positions; it never regained its equilibrium. 

 It died in about twenty hours after the operation. A post-mortem examination 

 showed that the medulla had been partly cut. 



Fish No. 4 was subjected to the same operation as No. i. The fish at first 

 swam irregularly, but twenty minutes after the operation it had regained its equi- 

 librium. In its response to tapping, its method of swimming when blinded, and 

 in its muscular weakness it resembled No. 2. It lived for about two days after 

 the operation. On examination, its utriculi and semicircular canals were found 

 much cut to pieces, but the sacculi and brain had not been injured. 



Of the total of twenty fishes in which the utriculi and semicircular canals had 

 been destroyed , 1 1 through early death or other unfavorable conditions proved to 

 be useless for experimentation. The remaining 9 reacted much the same as No. 2 

 and No. 4 in the set just described. In all 9, so far as I could judge, the animals 

 were as sensitive after the operation as before it to the noise produced by tap- 

 ping on the side of the aquarium. Immediately after the operation all swam 

 with disturbed equiUbrium, but within an hour, and often in even less time, 



