OF THE VENOM OF THE RATTLESNAKE. 87 



the venom in contact with its exterior. At the close of seven minutes the leg still 

 moved with ease, when the frog's body was irritated. The nerve was then incised 

 lengthwise, and a little pure venom dropped within the slit and on the nerve. 



A minute amount of moisture being applied to the nerve, with the aid of a 

 camel's hair brush, from time to time, it was found to carry impressions to or from 

 the nerve centres quite well at the end of an hour. On irritating the right foot, 

 both legs were moved freely, and on irritating the unwounded left leg, a like result 

 was observed. When released, the frog leaped about, using both legs with ease 

 and activity. Twenty-four hours later it was still able to use both legs, although 

 the muscles about the wounded part were softened by the venom, a change which 

 had not visibly acted on the nerve trunk. The frog finally recovered. Upon 

 several occasions, as opportunity oflered, I repeated these experiments, but without 

 arriving at any other conclusion than that the venom exerted no early action upon 

 the vital properties of nerves to which it was applied. 



Actio7i of the Venom upon the Sensory and Motor Nerves, and tqmn the Nerve 

 Centres.— In the conduct of this portion of my research, I endeavored to ascertain 

 which order of nerves was first affected by the venom. For this purpose. 



Experiment.— 1 tied the left femoral artery of a frog high up, and then had the 

 frog bitten in the back by two snakes. At the seventy-sixth minute all motion, 

 voluntary and reflex, had ceased. On galvanizing the right sciatic nerve, no reflex 

 acts ensued, but the muscles of the right leg moved as freely as those of the other 

 limb, which I had insulated from the effects of the venom by cutting ofl" its circu- 

 lation. The motor nerves were therefore unaffected. If the sensory nerves and 

 the centres had been also capable of transmitting impressions, and responding to 

 them, there would have been reflex movements produced. 



Numerous repetitions of this experiment convinced me that either the sensory 

 nerves had lost their powers, or that the nerve-centres were at fault. This question 

 was set at rest by the following means : — 



Experunent.—N frog was poisoned, and as soon as all movement was over except 

 that of the heart, the spine was divided, and a probe thrust up and down. No 

 motion resulted. The irritability of the motor nerves in the sciatic trunk was next 

 tested, and found to be nearly perfect. 



The loss of nervous function begins, then, at the centres ; and such being the 

 case, we cannot infer logically that the sensory nerves are paralyzed, but only that 

 they have no longer any means of expressing 'their sensibility, if it still exists. 



These experiments were repeated again and again upon warm-blooded animals, 

 in whom tlie action of the heart proved capable of being sustained for a time by 

 artificial respiration. 



Experiment.— A. large rabbit, male, was twice struck at 5.10. At 5.20 it fell, 

 and in twenty-eight minutes from the time of the bite, the respiration stopped. 

 Artificial insufflation was then employed, as usual. It seemed to sustain the heart's 

 action pretty well for about twelve minutes. During this time the dorsal spine 

 was cut across; no motion resulted. A probe being thrust up and down the spine, 

 feeble quivering of the nearer spinal muscles took place, but the limbs did not 



