REACTION AND RESISTANCE OF FISHES. 



223 



In establishing the gradient the flow at each end of the tank was 

 fixed at 500 c.c. per minute in practically all the experiments. 

 The flow of tap water was regulated to 500 c.c. per min. at one 



r - 1 

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C <u 3 bo O o *i in 



1 .S S 1 -S 



5 1 



+ 0) " 



S 



.S S 2 S. .5 S -a S 



end and to 400 c.c. per min. at the other. Then 100 c.c. per min. 

 of a solution of treated water was introduced into the 400 c.c. 

 flow from a mixing bottle (MB). The 100 c.c. flow was kept 



