120 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



the circulation. In dogs doses over o.oooi gm, per kilo body- weight produce 

 extensive intravascular (arterial and venous) thrombosis and death may 

 occur within several minutes. The respiration is seen to continue i or 2 

 minutes after the heart ceases to beat. When the concentration falls short 

 of that necessary to raise the coagulabihty of the blood sufficiently to cause 

 thrombosis, the blood shortly afterwards loses its capacity to clot when with- 

 drawn. In this condition any further injection of venom fails to produce 

 thrombosis. 



The action of the poison upon the heart and respiratory center is usually 

 simultaneous. But with higher concentration of the venom the heart is more 

 rapidly affected than the respiration, so that by varying the rapidity with 

 which the venom reaches the circulation, the death of an animal may be com- 

 passed in any one of three ways: either by clotting the blood in the vessels, 

 cardiac failure, or respiratory paralysis. If animals escape the three possi- 

 bihties of fatal issue above mentioned, they may succumb to the effects of the 

 pathological changes in the lungs and kidneys. This last danger is, however, 

 not a large one, except with dogs, and the animals usually recover with wonder- 

 ful rapidity. 



Violent convulsions are always observed in cases in which death results 

 from the intravascular thrombosis, and is due to the effect of asphyxia. In 

 cases where death is due to the paralytic action of the venom upon the nervous 

 system, there is first uneasiness, then lethargy, and often vomiting. The 

 lethargy increases and is succeeded by weakness, which first affects the hind 

 quarters. The animal remains quiet, and is disinchned to move. If forced 

 to walk its gait is unsteady and lacks coordination. Later it is quite unable 

 to stand, the pupil becomes dilated and insensitive to fight, and breathing is 

 shallow and slower. Reflex action gradually disappears, and the respiration 

 becomes very sluggish and gasping, and ultimately ceases. Death is followed 

 usually, but not always, by a few feeble, convulsive movements. 



DISTIRA. 



The symptoms observed in animals after the bite or injections of the venom 

 of the Hydrophiinae are similar to those of cobra-venom toxication. The local 

 symptom is, however, very slight; and there are no symptoms pointing to any 

 action of the venom upon the coagulability of the plasma or on red corpuscles. 

 Progressive paralysis is accompanied by dyspnoea. 



The symptoms produced by the bite of Distira cyanocincta on fowls depend 

 upon the amount of the poison introduced into the system. The bite may 

 kill a fowl within a minute or death may occur after 10 to 20 minutes, accom- 

 panied by paralytic symptoms. The fangs are very minute and often fail to 

 make distinct marks at the spot of the bite, although slight bleeding may 

 sometimes result. Local reaction is entirely negfigible. This snake is rather 

 active and may voluntarily bite the animal brought before it. Coagulability 

 of the blood usually remains unaltered from the effect of its bite. The symp- 



