46 
ACTION OF URARI AND OF STRYCHNIA. 
affected an hour or two later. If, after the nervous extremi- 
ties have become paralysed, the heart of the animal be excised 
so as to prevent the nerves from receiving any further share 
of the poison, the nervous trunks may retain their excitability 
for three or four hours. 
4. The brain is less affected by the urari than the nerves in 
the muscles ; still when, by ligature of the two aortic 
arches, in frogs, the poisoning is confined to the anterior half 
of the body, the voluntary movements of the limbs speedily 
cease, while automatic movements, of doubtful nature, and 
probably proceeding from the medulla oblongata, may be 
still observed for half an hour or an hour after the poison has 
begun to operate. 
5. The spinal cord is considerably less affected than the 
brain by this poison, and by local limitation of the poisoning 
(as in No. 4) it is found that the cord retains its reflex 
activity from half an hour to an hour and a half, and the ex- 
citability of its white substance, or its conducting power, from 
two to three hours after the poison has taken effect. It is 
worthy of remark that in such cases the impaired reflex 
activity of the spinal cord may be revived by strychnia di- 
rectly applied to it. 
6. The sensory nerves, as shown also by locally limited 
poisoning, retain their functional activity as long at any rate 
as reflex actions can be excited, and when the depressed 
reflex activity has been revived by means of strychnia, these 
nerves are found not to have been in the slightest degree 
injured, so that it seems doubtful whether the urari in any 
way affects them. 
7. The nerves of the involuntary muscles and of the glands 
are also paralysed by the action of urari, at least I find this 
to be true in the following cases, viz. — 
a . The pneumogastric, as regards its influence on the 
heart. 
b. The sympathetic (its cervical portion), in its relation to 
the iris. 
c. The nerves of the posterior lymph-hearts of the frog. 
d. The nerves of the vessels in the web of the frog’s foot. 
e. The splanchnic nerves of the rabbit, as affecting the 
peristaltic motions. 
/. The nerves governing the secretion of the submaxillary 
gland in dogs. 
8. The voluntary muscles remain perfectly excitable, but 
show a greater tendency than usual to merely local contrac- 
tions. In general the cadaveric rigidity of these muscles 
appears to set in later than usual. 
