EFFECT OF ETHER AND CHLOROFORM ON FISHES. 245 



ments were used to determine the ether curve and 15 for that of 

 chloroform. This does not seem to be sufficient data to establish 

 a law although it appears obvious that there may be one here. 

 The upper limb of the chloroform curve is nearly a straight line 

 and in it c X / = k, about 4,200, c being concentration in cu. mm. 

 per liter and t being time until death. It is probable that time, 

 weight of fish, and concentration of poison used, will prove the 

 determining factors for relative toxicity. 



The similarity of the chloroform and ether curves suggest that 

 after the location of a toxic zero, Krogh's ('14) Law may be 

 found to govern under certain limitations. Should a law be here 

 discovered and prove to hold closely enough, it is easily seen 

 that it will prove of very great value in the standardization of 

 poisons by means of fish. 



V. POISONING SYMPTOMS. 



1. Ether. No particular irritability or spasmodic movements 

 were noted. The fish at first acted normal, then swam vertically 

 with head up, lastly quieted down and lay on its back or side, 

 very usually at the surface of the water. 



2. Chloroform. For ansesthesia with either chloroform or 

 ether Cushny 1 notes three stages: (i) Imperfect consciousness, 

 (2) excitement, (3) ansesthesia. In fish, although the first stage 

 is almost impossible to distinguish from the normal, the others 

 may be definitely noted. The second stage is characterized 

 through all concentrations used by a variable period of violent 

 muscular contraction, which throws the fish wildly in all directions 

 so that it bumps its nose strongly on the glass each time. Each 

 bump is followed by a motionless pause of one half to one second. 

 The third stage, coma, is reached in a time increasing as the 

 concentration decreases. The fish lies on its side, or rarely on 

 its back, at the bottom of the jar and the opercular movement is 

 regular at first, then intermittent, and finally ceases. While the 

 fish respires regularly it may recover if held under a stream of 

 running water. 



3. Comparison of Ether and Chloroform. (a) In ether the 

 stage of excitement is short or omitted while in chloroform it is 



1 Pharmacology, p. 151. 



