THE PHYSIOLOGY OF POISONING 191 
The venoms of Ancistrodon contortrix and À. piscivorus (CRo- 
TALINÆ) proved entirely inactive. 
No COLUBRINE venom exhibited coagulant power, whatever the 
dose employed. 
There is, therefore, a very decided difference between venoms 
of divers origins as regards their effects upon the coagulation of 
the blood. 
Noc has determined more especially the coagulant action of 
the venom of Lachesis lanceolatus (Fer-de-lance of Martinique) 
upon | per cent. citrate-plasmas, 1 per cent. oxalate-plasmas, 4 per 
cent. chloridate-plasmas, and upon blood rendered non-coagulable 
by extract of leeches’ heads. He found that, while weak doses of 
venom (1 milligramme per cubic centimetre of horse- or rabbit- 
plasma) produce coagulation in a few minutes in the citrate- 
plasmas, chloridate-plasmas, or those treated with extract of 
leeches, the doses of the same venom greater than 4 milligrammes 
on the contrary suppress the coagulability of these plasmas, even 
when there be added to them doses of chloride of calcium (for the 
citrate- and oxalate-plasmas), or of distilled water (for the chlori- 
date-plasma), or of fibrin-ferment (for the plasma treated with 
leech-extract) sufficient to cause rapid coagulation in the control 
tubes that do not contain venom. 
Noc also observed that the venom of the same species of snake 
(Lachesis lanceolatus), when heated to 75° C., entirely loses its 
coagulant properties; and that, with a temperature of 58° C., its 
coagulant power already commences to diminish. When heated 
for thirty minutes at a temperature of 65° C., a dose of 1 milli- 
gramme does not coagulate more than 1 c.c. of citrate-plasma 
in one hour. G. Lamb has likewise found that the venom of 
Vipera russellii loses its coagulant power when heated to 75 C. 
The coagulant substance in these venoms is precipitable by 
alcohol at the same time as the neurotoxin and other active sub- 
stances. The precipitate, when dissolved again in physiological 
water, preseryes all the properties of the original solution, 
