448 MORRIS M. WELLS. 



starved animals are beginning to show a greater susceptibility 

 to the detrimental condition, than is shown by the control. A 

 comparison of the control and experimental animals at this time 

 shows that the experimental fishes in groups 3, 5 and 6 are more 

 susceptible, in groups I and 4 they are still less susceptible while 

 control and experiment in group 2 show the same susceptibility. 

 In experiments performed on the sixtieth day of starvation 

 groups i, 2 and 4 were found to be much more susceptible than 



the controls. 



5. Comparison of Species. 



Further evidence pointing toward a similarity in the physio- 

 logical action of lack of oxygen and KCN is suggested by the 

 results of a series of experiments that were conducted with the 

 idea of comparing the effects of the two treatments upon other 

 species of fishes and upon frog tadpoles. Table IV. shows the 

 results of an experiment with KCN in jV/25,ooo concentration 

 and a series of tadpoles and fishes whose relative resistance to 

 low oxygen had been previously determined (Wells, '13). The 

 relative resistance or susceptibility of the species in KCN solution 

 is the same as had already been found for these species in low 

 oxygen water. The tadpoles are markedly most resistant, the 

 catfish is next, the rock bass third and the darter least. In 

 experiments of this kind size differences were eliminated by 

 selecting individuals of a given weight. Thus the weights varied 

 only between 1.5 and 3 grams. 



TABLE IV. 



Showing the comparative resistance of different species to N/2$,ooo KCN solution 

 The species are arranged in the order of their increasing resistance. This is 

 the same order that they show in low oxygen water. All the individuals used 



weighed between 1.5 and 3 grams. 



Dving Time in 

 Species. Hrs. and Min. 



Darter (Etheosloma cceruleum) 35 niin. 



Rock bass (Ambloplites rupestris) i hr. 5 min. 



Catfish (Ameiurus melas) 27 hrs. 50 min. 



Tadpole (Rana catesbiana) 208 hrs. 50 min. 



V. DISCUSSION. 



From the data here presented it is evident that the relative 

 deleterious effects of lack of oxygen and a TV/25, ooo solution of 

 KCN are much the same for the animals in question. This 



