REACTIONS OF FISHES TO SALTS 261 



of the experiments were in gradients of CaCl2 since it seemed 

 best to confine the experiments to a few salts at the most. It 

 was decided that the starving fishes should not be handled to 

 any great extent during the obtaining of the data for which the 

 material was originally intended. A few experiments were run 

 in gradients of Ca(N03)2 and MgCl2 the results of which were 

 much like those for CaCl2. Nine expriments with starving fishes 

 in low oxygen gradients are included as they are significant. 



The experiments with starvation and resistance of fishes showed 

 in brief the following points : The fishes as they began to starve 

 became more resistant to KCN and low oxygen. This rise in 

 resistance which is a decrease in susceptibility, continued for some 

 weeks (varied with species). There was then a rather sudden 

 decrease in resistance (increase in suseptibility) which was found 

 to be a close fore-runner of death. In terms of metabolism, as 

 starvation in certain fishes proceeds the rate of metabolic acitvity 

 is at first decreased. After remaining below normal for some 

 weeks (or even months) the forces which are inhibiting the rate 

 of reaction, give way and the rate runs up rapidly to, and beyond, 

 the normal rate. Whether the changes in the physiological 

 condition of the fishes are wholly quantitative is not certain. It 

 is very probable that a change in the rate of metabolism does not 

 express all that takes place but there may be alterations in the 

 kind of metabolism also; in other words starvation in fishes may 

 produce qualitative as well as quantitative changes in metabolism. 



Starvation experiments were run with several species of fishes 

 including the rock bass (Ambloplites rupestris), small mouth 

 black bass (Micropterus dolomieu), pumpkin seed (Eupomotus 

 gibbosus), mud minnow (Umbra limi), and the black bull-head 

 (Ameiurus melas). The fishes seemed to be divided into two 

 groups as far as their starvation reactions are concerned. The 

 bull-heads made up one group and the other fishes a second. 

 Most of the work was done with the bull-heads and the rock 

 bass as representatives of the two groups. In the case of the 

 rock bass some quantitative data can be presented. 



