280 MORRIS M. WELLS ,' 



leave the fresh water. In October, 1883, one of the fishes ''jumped 

 out of the pond onto the bank. By the end of November, several 

 had jumped out onto the bank and died there (they usually 

 jumped during the night or early morning). In the following 

 May, 16 of the fishes were found dead on the bank. Then the 

 following October (1884) they commenced constantly jumping 

 out of the pond and meeting with fatal injuries. It was ob- 

 served that the fishes did not feed at this latter date; this failure 

 to take food is characteristic of salmon entering fresh water to 

 breed. 



Examination of the fishes which had jumped out of the pond 

 showed that all were approaching maturity and in the later 

 cases, the eggs and sperm were ripe. An attempt was made to 

 fertiUze the eggs with the sperm, with good success. Day states 

 that this second generation was normal and vigorous up to 20 

 months and concluded that it was definitely proved that a so- 

 journ in salt water is not necessarily for the development of 

 the sexual products. If this is true, the migration of the salmon 

 into the salt water, and back again, is all the more curious. There 

 would be advantages and disadvantages to such behavior but 

 the above data prove that the fishes are reacting to the environ- 

 ment in a way that is not inmiediately essential though the 

 stimulus seems to be a very strong one. A study of the behavior 

 of these fishes in salt, acid and alkali gradients at different stages 

 in their life history, would undoubtedly prove very suggestive 

 and such a stud}' correlated with physiological investigations of 

 the fishes at similar stages will without doubt solve the question 

 of the movements of anadromous fishes. 



VI. GENERAL CONCLUSIONS 



1. Fresh water fishes recognize and react to the presence of 

 salts in solution. The reaction is one which tends to bring them 

 into their optimmn salt concentration. 



2. Fresh water fishes (and probably marine fishes also, Shel- 

 ford and Powers '15) are not as sensitive to salt ions as they are 



