262 



MORRIS M. WELLS 



1. Reactions of starved fishes to CaCh 



Normal bull-heads are negative to 0.01 N calcium chloride in 

 a gradient. It was noticed, however, that when food was given 

 these fishes they often became positive to the salt half of the 

 tank. To check this reaction 23 experiments with normal, well 

 fed and starved bull-heads were run. Table 3 shows the results 

 obtained. It shows that normal fishes (bull-heads) are negative 

 to O.OIN calcium chloride well-fed ones positive, and starved 

 negative again. The well-fed bull-heads were in fact given all 

 the food they would eat and thus were really over fed, as they 

 ate until their abdomens were much puffed out. The data in 



TABLE 3 



Showing the reactions of normal, over-fed, and starved hull-heads (Ameiurus melas) 

 to .OIN calcium chloride, in a gradient. Data shows per cent of time spent in 

 the halves of the tank 



table 3 is taken from the graphs made with 5 fishes. The normal 

 reaction of each fish was determined immediately upon bringing 

 it into the laboratory from the streams. On the next day the 

 fishes were fed all the beef they would eat and graphed again on 

 the third day. They were then starved and graphed from day 

 to day. The figures in column 4, table 2, are those obtained 

 after from 5 to 10 days starving. Each day calcium chloride 

 was run into the end of the tank opposite that of the day before. 

 The method of experimenting with the rock bass in the resist- 

 ance experiments was to bring them in from the creeks in which 

 they live and to weigh them individually, and at once. The 

 process of starvation was then kept track of by successive weigh- 

 ings. Twenty-six experiments with these starving fishes were 



