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CaClo. It was now placed in a 20-gallon-jar full of a 0.01 N 

 solution of this salt. Each succeeding day it was taken from 

 the jar and its reaction in the gradient graphed, when it was re- 

 turned to the jar. This was continued for 6 days; the con- 

 centration of the solution in the jar was then riased to 0.05N. 

 The fish was left in this solution 4 days longer, being graphed 

 each day. It was then returned to the tap water and graphed 

 again after 2 days. In making the graphs each day, the salt 

 solution was run into the end of the gradient tank, opposite 

 that of the day before. A series of the graphs made by this 

 fish are shown in figure 3. They show the different stages in 

 the process of acclimatization. In short they indicate that the 



Fig. 3 Showing the reversal in reaction to 0.01 N CaClo, upon the part of a 

 45-gram rock bass (Ambloplites rupestris), after being kept in the salt solution 

 for a week, and the return to normal reaction upon being placed in tap water 

 again. In the experiments the salt was made to flow into alternate ends, but in 

 the chart the graphs have been copied so that the reaction will be more easily 

 seen, by keeping the same relation between the tap and CaCh ends. 



