CHAPTER XI. 
EXPERIMENTAL VENOM POISONING IN ANIMALS. 
The accurate nature of the actions of venom on organisms can best be 
studied by introducing the known amounts of venom, either modified or 
unmodified, into the system by various modes of inoculation under variable 
conditions. The symptoms observed in human cases can thus be approxi- 
mately reproduced in certain animals and studied by the aid of different 
physiological and pharmacological methods. In treating this topic it appears 
to me to be most convenient to describe the symptoms and afterwards analyze 
them. I will also describe later the effects of venom upon different organs, 
body-fluids, tissues, and cells. With the exception of the frog, the experi- 
ments made on cold-blooded animals will be given in a subsequent chapter, 
and those made on warm-blooded animals will be chiefly considered here. 
THE VIPERID&. 
CROTALUS ADAMANTEUS. 
Weir Mitchell found that the effect of the venom of this snake on birds 
is extremely virulent, and so sudden in some cases that when the dose is 
large there is hardly time to observe the resulting phenomena. Acute poison- 
ing of pigeons is very common. When pigeons are bitten by Crotalus the 
symptoms which immediately follow the bite are feebleness and dyspncea. 
Convulsions and gasping are always observed. Respiration may cease in a 
few minutes or sometimes after half an hour. Convulsions may precede the 
respiratory cessation. Twitching of the muscle near the bitten spot may be 
seen. The pupil usually remains unaltered, or perhaps slightly contracted. 
Coagulability of blood seems to be normal. Irritability of the sciatic nerve 
may continue to exist for nine minutes after death. The heart stops several 
minutes or longer after the cessation of breathing. The irritability of the 
muscles is well preserved ten minutes after death. The fang marks are sur- 
rounded by circles of extravasated blood. In one instance death took place 
in 30 seconds, during which time the bird became completely paralyzed. 
The chronic form of poisoning was also described by Mitchell. When 
pigeons are not killed rapidly they may partially recover for some days, 
during which time local necrosis becomes appalling. Death usually occurs 
within a few days, or it may result in 12 to 24 hours. The peculiarities of 
the chronic poisoning are the loss of coagulability of blood, and numerous 
ecchymoses in internal viscera, serous and mucous membranes, and muscular 
tissue adjacent to the fang marks. 
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