ACTION OF URARI AND OF STRYCHNIA. 47 
9. The plain or non-striated muscles also remain long irri- 
table after poisoning by urari. 
10. The hearty in amphibia, is little affected by urari. Its 
pulsation as well as the circulation of the blood goes on 
regularly for many hours after the poisoning is established. 
The only thing worthy of note is that the beat of the heart 
appears to be somewhat quickened, probably from paralysis 
of the pneumogastric nerves. In frogs poisoned with urari, 
the heart, when cut in two, shows the usual phenomenon, 
namely, that the half which contains the ganglia continues to 
pulsate while the other does not ; from which it may be in- 
ferred that these ganglia are not paralysed. As to the nerves 
in the substance of the heart, those at least which are derived 
from the pneumogastric are unquestionably paralysed {vide 
No. 7). 
11. The lymph-hearts of frogs poisoned with urari soon 
cease to move. 
12. The blood of animals poisoned by urari is fluid and 
dark, but coagulates when drawn from the vessels, and forms 
a weak clot which is but little reddened by exposure to air. 
Directly mixed with blood, urari does not prevent coagula- 
tion; but the blood in this case also remains dark, and 
scarcely reddens on exposure. 
13. The blood of animals poisoned by urari has the same 
poisonous qualities as that substance itself, but not in a de- 
gree sufficient to produce the full effects of the poison. Urari 
when directly mixed with blood loses none of its efficacy. 
14. Urari, in concentrated solution, applied locally to 
nerves extinguishes their excitability, but only after a con- 
siderable time ; and it appears to act similarly on the nerves 
in the substance of the muscles. Dilute solutions have no 
injurious operation. Applied directly to the brain and spinal 
cord, urari is altogether harmless provided its absorption be 
prevented. 
15* When artificial respiration is kept up in quadrupeds 
poisoned with urari, I find that, as observed by Bernard, 
many of the secretions become increased — as the tears, saliva, 
urine, and mucus of the air-passages, which effect appears to 
be owing to the paralysis of the vascular nerves, and conse- 
quent dilatation of the vessels caused by the poison. 
16. In mammalia urari causes death by paralysis of the 
respiratory nerves and suppression of the respiration, which 
brings on convulsions in these animals as a collateral effect. 
In frogs the final extinction of the functions may also be 
partly ascribed to suppressed action of the lungs and defec- 
tive oxidation of the blood, which at length renders the heart 
