NATURE AND ANALYSIS OF THE POISONS. 1381 
from tenesmus, but was so weak that he stood up with 
difficulty. 
His gums were bleeding, a symptom I had seen before, and 
his eyes were deeply injected. (The most characteristic symp- 
tom of yellow fever, according to Manzini.) 
Twenty-seven hours and a half after the time he was bitten, 
his hind legs were twitching, and the dysentery continued. 
No clot was found in the blood. This case is doubly im- 
portant, because it shows how long the poisoning must con- 
tinue before the blood becomes diffluent. 
Dr. Mitchell continues: 
“The study of envenomed blood has thus far taught: us : 
“1st. That in animals which survive the poisoning for a 
time, the blood is so altered as to render the fibrin incoagu- 
lable. 
“9d, Experiments in and out of the body have given proof 
that. this change is gradual, and that the absence of coagu- 
lation is not due to checked formation of fibrin, but to alter- 
ations produced by the action of the venom in that fibrin 
which already exists in the circulating blood. 
“3d. The influence thus exerted is of a putrefactive nature, 
and imitates, in a few hours, the ordinary work of days of 
change. It is probably even more rapid within the body, on 
account of the higher temperature of the economy. 
“Ath. The altered blood retains its power to absorb gases, 
and thus to change its own color. 
“5th. The blood-corpuscles are unaffected in acute poison- 
ing by Crotalus venom, and are rarely doubtfully altered in 
the most prolonged cases which result fatally. ; 
“6th. The contents of the blood-globules of the Guinea pig 
ean be made to crystallize, as is usual after other modes of 
death. 
