136 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
the smallest amount of venom capable of coagulating 1 c.c. of the whole 
blood containing 1 : 100 citrate salt. 
Although the presence of an excess of the citrate does not prevent the 
venom from inducing coagulation of the citrate blood, certainly it lessens this 
power to a certain extent. 
The experiment with the citrate and oxalate plasmas obtained free from 
the blood corpuscles by a process of sedimentation! give similar results. 
0.003 to 0.005 gm. of daboia venom added to 2 c.c. of the citrate plasma 
clotted it in less than 3 hours, and 0.0004 to 0.001 gm. did so in 20 hours, 
but 0.0002 gm. caused only a slight clot in 20 hours. On the other hand, 
0.005 gm. of daboia venom added to 2 c.c. of the oxalate plasma produced 
only a slight coagulum in 20 hours, and the same was true with smaller quan- 
tities down to 0.0006 gm., but no more effect was obtained when 0.0004 gm. 
was used. If the quantity of the potassium oxalate percentage be reduced 
by adding an adequate amount of calcium chloride solution to the point 
where coagulation of the plasma is just prevented from occurring after 20 
hours, then 0.005 gm. of daboia venom can induce coagulation within 10 
minutes. This difference is explained by Lamb to be due to the less solu- 
bility of the oxalate than the citrate of calcium, and the coagulating effect 
of daboia venom is more rapid and pronounced with the latter salt. 
Hydrocele fluid, either with or without addition of lime solution, could 
not be coagulated by means of daboia venom; but it quickly clotted when a 
small amount of oxalate plasma was added. 
Lamb expresses the belief that the ultimate cause of this increase of coagu- 
lability produced by daboia venom is some obscure interaction between the 
poison and the nucleo-proteids, or between the poison and fibrin ferment, 
but not the result of the setting free of normal nucleo-proteids through the 
destruction of the cells by the poison. 
In 1904 Noc,? under Calmette, made similar observations on the venoms 
of different species of Lachesis. He employed the plasmas obtained from the 
blood of rabbits or horses by first rendering the whole blood incoagulable 
by adding various salts or leech extract. Of the salts, there were employed, 
sodium citrate I : 100; potassium oxalate 2 : 1000; sodium chloride 4 : 100; 
sodium fluoride 3: 1000. The plasma containing one of the above salts 
coagulated in 15 to 20 minutes when 1 c.c. was mixed with 0.4 gm. to 0.6 c.c. 
of a o.5 per cent solution of calcium chloride. Noc found that rapid coagula- 
tion is produced when, in the place of calcium chloride solution a small 
quantity of the venom of Lachesis lanceolatus is added to these plasmas. 
To 1 c.c. of the plasma 0.001 to 0.002 gm. of the lachesis venom caused 

1 With the flasks containing 50 c.c. of 20 per cent solution of sodium citrate (in 0.75 per cent NaCl) 
on one hand, and 40 c.c. of 5 per cent solution of potassium oxalate (in 0.75 per cent NaCl) on 
the other, one liter of horse blood was drawn into each flask respectively, and then allowed 
to stand at 14° C. for 48 hours, during which time the corpuscles settled down and clear super- 
natant fluid or plasma was obtained. In the case of the citrate it contained this salt in 1 per 
cent, while in the case of the potassium oxalate o.2 per cent was the resultant concentration. 
2Noc. Sur quelques propriétés physiologiques des différents venins des serpents. Anns. de I’Inst. 
Pasteur, 1904, XVIII, 387. 
