490 ON THE PHYSIOLOGICAL ACTION OF CASCA BAltK. 



GENLn?AL Action on Fishes and Frogs. 



In fishes and frogs there is but slight susceptibility to the 

 poison, and the effects produced by it are similar in the two 

 classes. The most obvious general systems are muscular 

 paralysis and cessation of respiration, preceded by spasmodic 

 movements. It will be seen later, however (Experiment XVIII), 

 that the particular action of the drug on the heart is well 

 shown in frogs. 



Experiment VL — February 21. 



One-third of a c.c. of the solution was injected beneath the 

 skin of a medium-sized frog. In 2 minutes slight tonic 

 contraction of the limbs was observed; in 4 minutes it was 

 jumping rather actively, but fell over on its back ; in 12 

 minutes the respiratory movements had become almost imper- 

 ceptible ; and from this time the reflex movements of the limbs 

 on irritation gradually got weaker and weaker, and finally 

 ceased 33 minutes after the injection. 



After deatli, the ventricle was found firmly contracted, the 

 auricles and venous trunks engorged. 



Experiment VII. — February 21. 



Experiment VI was repeated with double the dose. Tlie 

 frog was slightly larger than the one first used ; but reflex 

 action ceased within a few seconds of the same time after 

 injection. The general effects were almost the same as in 

 Experiment VT, save that 5 minutes before reflex move- 

 ments ceased there were four spasmodic inspirations. 



Experiment VITI. — April 18. 



The effect on fishes was tried. First, 55 c.c. of a -j^ watery 

 solution of casca were added to 3 litres of water in which a 

 gold-fish weighing 3 ounces was swimming. At the end of 

 3 hours no effect was produced on the fish. 1*3 c.c. of the 

 alcoholic solution were then injected into tlie side of the fish, a 

 little in front of the tail. In 5 minutes it began to roll from 

 side to side ; the respirations were catching. For the next 10 



