ANTAGONISM TO ATROPIA AND CHLORAL. 525 



Experiment LIV. 



The heart of a frog was exposed and casca administered. 

 As soon as the heart had ceased to beat the heart of a second 

 frog was ligatured at the root of the aorta so as completely to 

 arrest the circulation. At first both frogs were able to jump 

 readily ; but gradually their movements became more sluggish, 

 and after a jump their legs trailed out behind them and were 

 only slowly drawn up to the body. They became less and less 

 sensitive to pinching, and insensibility and loss of motor power 

 occurred simultaneously in both. 



The diminished power of movement and diminished reflex 

 action observed in the frog after the administration of casca is 

 therefore due to the arrest of the circulation caused by it, not 

 to any action of the drug upon the nervous system. 



Antagonism between Casca and Atropia and Chloeal 

 Hydrate. 



The remarkable result of Experiment XXIV, in which a dose 

 of casca, usually fatal, produced no effect in an animal with 

 divided vagi, seemed to render it probable that such a drug as 

 atropia, which paralyzes the ends of the vagus in the heart, 

 might have an antagonistic action. On trying it, however, it 

 was found that the vomiting caused by the casca was even more 

 violent than usual ; and therefore a combination of atropia with 

 chloral hydrate was employed, the chloral being given to lessen 

 the irritability of the vomiting centre in the medulla. 



The results were not satisfactory, as will be seen fiom the 

 two following experiments. 



Experiment LY.— May 1, 1876. 



About 11.40. Injected 4 c.c. of liquor atropire under skin of 

 flank of cat A. 



12^. Injected 4 c.c. of a saturated alcoholic solution of alco- 

 holic extract of casca under skin of flank of cats A and B 



