136 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



the smallest amount of venom capable of coagulating i c.c. of the whole 

 blood containing i : loo 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 S^- o^ daboia venom added to 2 c.c. of the citrate plasma 

 clotted it in less than 3 hours, and 0.0004 to 0.00 1 gm. did so in 20 hours, 

 but 0.0002 gm. caused only a slight clot in 20 hours. On the other hand, 

 0.005 gn^- 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 E^- 

 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 g^i. 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 i c.c. was mixed with 0.4 gm. to 0.6 c.c. 

 of a 0.5 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 I c.c. of the plasma o.ooi 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 ini per 

 cent, while in the case of the potassium oxalate 0.2 per cent was the resultant concentration. 



2 Noc. Sur quelques proprietes physiologiques des differents renins des serpents. Anns, de I'lnst. 



Pasteur, 1904, XVIII, 387. 



