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PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 207 
previously heated to 85° C. for five minutes, the corresponding 
amount required to kill was -0030 gramme. 
These observations show that either 
(1) Heating vo 85° destroys the component of venom which 
possesses the power of destroying corpuscles to the greatest 
degree, —or 
(2) Heating attenuates the toxic properties of venom in this 
particular direction to a much greater extent than it does 
its toxic power generally. 
Heating to 85° C. does indeed separate one of the proteid con- 
stituents which at this temperature is coagulated and rendered 
inert. It is therefore quite possible that the difference in the action 
of venom before and after heating to 85° O. may be so explained. 
We must however bear in mind that the action of heat on solutions 
of toxic proteids is a twofold one— 
(1) By converting some of the proteids into an inert precipitate. 
(2) By impairing their toxic power, without influencing their 
solubilities, or indeed changing them in any way recog- 
nisable by chemical tests. 
The first method of action is sudden. When the solution is 
: aed to a definite temperature, some portion of the proteid con- 
: : stituents is coagulated. ‘The second is gradual, and the extent of 
attenuation depends on the duration of the heating, and the 
Yemperature and dilution of the solution. 
7 th the case of Crotalus venom Mitchell and Reichert have shown 
“9 the coagulable proteids are the constituents which produce a 
destructive effect on the blood cells and vessel walls to the greatest 
es but I have not yet determined for Pseudechis poison to 
“an ®xtent the difference in physiological action between venom 
ett heated to 85° C. and unheated venom is to be attributed 
ati “een of one of the constituents or to gradual attenu- 
tae of its power in a particular direction. 
