8G PHYSIOLOGY AND TOXICOLOGY 



ficial respiration failed almost totally to sustain the cardiac power ; but even in 

 these the heart remained irritable to direct stimulus, and there was consequently 

 no such thorough paralysis of the sarcous elements as is seen in some other 

 poisonings. 



Aciio7i of Venom on the Capillary Sijstem. — The experiments on the heart force 

 furnish incidental information as to the absence of capillary irritation from the 

 presence of venom in the circulation. 



John Reid, of Edinburgh, has very well shown in his experiments on asphyxia 

 that when black blood, or any other stimulant, enters the capillaries, the arterial 

 pressure increases largely, as is proved by the rise of the mercury in the cardio- 

 meter. No such increase of pressure followed the introduction of venom into the 

 system, and we may therefore infer that it exerts no very marked influence of this 

 kind upon the vessels in question. 



In frogs, poisoned by venom, the capillary circulation is unaltered, until the heart 

 itself becomes too feeble to sustain it. 



When the frog's foot is placed under the microscope, and wetted with venom, no 

 change occurs, because the skin refuses to admit the poison. If we attempt to 

 introduce it into the web through a wound, the mechanical irritation produced by 

 the instrument so affects the local circulation as to baffle the observer completely. 



Action of the Venom ujton the Intestinal Movements. — The motions of the intestinal 

 canal were unaffected by Crotalus poisoning, and in all cases were as active as after 

 other modes of death. 



Action of the Venom upon Ciliary Movement. — In a number of cases of acute and 

 chi'ouic poisoning, I examined the cilia from the mucous membrane of the throat of 

 the frog. Their activity appeared to be undisturbed in both forms of the malady. 



Action of the Venom on the Nervous System. Direct Effects of Venom on Nerve 

 Trunks. — The older observers had already shown that the direct contact of venom 

 and nerve matter produced no early local paralysis of the nerve thus treated. I 

 have repeated and modified these experiments, making use of the venom of the 

 Crotalus. 



Experiment. — The leg of a frog, prepared as if for use for a galvanoscope, was 

 placed in a wide test-tube, and the long sciatic nerve laid upon a glass slide. Upon 

 applying gentle mechanical or galvanic irritants to the nerve trunk, the muscles of 

 the leg moved freely. A drop of pure venom was then let fall on the nerve, along 

 which it ran by capillary attraction, so as to wet about one-third of an inch of its 

 length. At the close of ten minutes the nerve still reacted well. In a second case 

 treated in the same way, but subjected to rather more of the venom, the nerve 

 acted well after eighteen minutes; and in a third nerve similarly situated, irrita- 

 bility was excellent at the close of thirty-two minutes. 



In a second series of experiments, the same conclusion was reached by another 

 route. 



Ej-pcrime7it. — A large frog was chosen, and the right sciatic nerve isolated in 

 almost half an inch of its course. A little gutter of wax was slipped under the 

 nerve, and a rather thin solution of venom in water applied to the nerve trunk 

 during five minutes. The wax groove, in which lay tlie nerve, served to retain 



