496 o^^ THE physiological action of casca bark. 



Comparative Action of the Alcoholic and Wateky 

 Extracts. 



The action of the alcoholic and watery extracts of casca, when 

 administered subcutaneously to cats in large doses, is almost 

 identical; and their activity as poisons appears to be about 

 equal, the watery extract, if anything, being rather the more 

 powerful. 



Experiment XXIL— April 28. 



Two equal quantities of the alcoholic and watery extracts-' 

 were dissolved in equal Aolumes of alcohol and water re- 

 spectively. The quantities were 3 grammes of the extracts 

 and 4 c.c. of the fluids. These solutions were injected beneath 

 the skin of two cats of the same size. In the case of the alco- 

 holic extract vomiting came on 15 minutes after injection, with 

 the other symptoms of poisoning by the drug {i.e., respiratory 

 difficulty and staggering gait). The vomiting was repeated 

 violently, and the animal died 1 hour and 15 minutes after in- 

 jection, death being preceded by general convulsions. 



In the case of the watery extract vomiting did not come on. 

 for 35 minutes, but death occurred, with symptoms similar to- 

 those of the former case, in 1 hour after the injection. 



In order to ascertain whether the vomiting was due to the; 

 action of the drug upon the sensory nerves in the stomach, 

 itself, after it had been conveyed to that organ by the circula- 

 tion, or to its action upon the nervous centre in the medulla, 

 oblongata regulating the movements of vomiting, the vagi were 

 cut, and the cliief sensory nerves of the stomach thus divided,, 

 before administering the poison. By this procedure the retch- 

 ing and vomiting were either completely prevented or very 

 greatly diminished, the dyspna^a rendering it ratlier difficult to- 

 decide in some cases whetlier some convulsive movements were 

 due to it or were movements of retching. The vomiting is. 

 therefore chiefly, and in all probability entirely, due to the 

 action of the drug on the sensory nerves of the stomach itself,, 

 as the retching, if indeed really present, might be due to irrita- 

 tion conveyed to the medulla through the splanchnics after the 

 vagi had been divided. 



