No. 448.] C A A SSI US AURATUS L. 



respond, I3 were in the case of the albino fi.sh aboxe mentioned, 

 and many of the remaining 31 were probably due to faulty 

 observations caused by the extreme activity of the ti.shcs. In 

 this respect, there is a great difference between different individ- 

 uals, some being in such continual moxement that it is diriicult 

 to test them, while others are more generally quiet. 



IV. Fishes wtth Ixsknsiti vf. Skins. 



The second class of fishes tested were those in which the 

 greater part of the skin had been rendered insensitive by cutting 

 the spinal cord just posterior to the pectoral fins, as well as 

 both lateral branches of the tenth, and the fifth and seventh 

 nerves on both sides of the body. The fifth and seventh nerves- 

 were cut at a point just above the dorsal end of the opercular 

 opening, where they come close to the skin. The fishes were 

 etherized before the operation, and usually reco\'ered and li\ed 

 many weeks. The individuals selected for this operation were 

 those which showed good pectoral-fin reactions when tested with 

 the tuning fork. Such fishes after recovery lay on their sides 

 on the cloth bottom of the aquarium, and were perfectly quiet 

 unless stimulated. That their skins were practically insensitive 

 was shown by the fact that they were quite indifferent to touch 

 with a bristle or the like. 



In 65 tests on 6 such fi.shes, I ob.served 52 responses (Scv ; ) 

 to the vibrating fork, a condition essentially the same as that of 

 normal fishes. These experiments demonstrate then, that with 

 an almost insensitive skin, a goldfish will respond to .sound a> a 

 normal fish does. 



V. FiSHKS WITH InSHNSITIVK l-..\K>. 



The third class of fishes tested were those in which the eighth 

 nerves had been cut on both sides. In i)rei)aring for this opera- 

 tion a number of fishes were tested and only such as showed a 

 clear reaction to sound were operated on. They were etherized, 

 and their eighth nerves were cut by i)iercing the skull in an 

 appropriate position and cutting downward with a small chisel- 



