COBRA HEMOLYSIN TEST. 



+ Signifies hemolysis. 

 Signifies no hemolysis. 



Cobra Hemolysin Test. 



1. Washing of Erythrocytes. The blood is collected into sterile flasks containing 

 sterile glass beads. It is then shaken and thus defibrinated to prevent coagulation. 

 The defibrinated blood is next centrifugalized and the serum separated and drawn off 

 by means of a pipette. The red blood cell sediment is then mixed with physiological 

 salt solution and again centrifugalized. This procedure is repeated several times until 

 all the serum is removed. The red blood-cells as used are in a 5 percent, suspension; 

 i.e., i part of washed erythrocytes suspended in 19 parts of saline. 



2. The Activating Agent. In order to obtain an activating agent 0.2 of serum or a 

 o.i per cent, of a lecithin solution is employed. The lecithin can be kept as a stock 

 solution consisting of i g. lecithin in 100 c.c. of methyl alcohol. Ao.i per cent, solution 

 of the stock mixture is made by mixing o.i c.c. of the solution with 9.9 c.c. of physiological 

 salt solution. 



3. The snake poison, hemotoxin, is resistant toward heat so that it may be heated to 

 almost 70 C. without interfering with its activity. Cobra poison contains the greatest 

 amount of hemotoxin. While i mg. of cobra toxin hemolyses i c.c. of 5 per cent, horse's 

 red blood-cells in five to ten minutes, a similar amount of viper toxin requires thirty 

 minutes for the same action. 



V. Dungera and Coca explain this type of hemolysis on the ground of the 

 existence of a ferment within the snake poison which breaks up the lecithin 

 with the liberation of oleic acid. This acid has long been known as a 

 hemolytic agent. The necessity for adding lecithin or serum to certain 

 species of blood is explained by the variability in the lecithin content of the 

 erythrocytes. 



