94 Messrs. J. A. Gunn and R. St. A. Heathcote. 



the composition of the venom. The times of centrifuging and keeping the 

 blood of the two animals were exactly the same, so that the experiments were 

 as nearly as possible paralleled. 



The following Table gives a skeleton of the experiments performed to 

 determine the minimum haemolytic dose of the venom for rabbit's and cat's 

 corpuscles respectively : — 



Table II. — Scheme of Haimolytic Experiments. 





1. 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 



10. 



C.V. 01 per cent. 



C.V. 0-01 per cent. 



Blood suspension, c.c. ... 



Cobra venom, c.c 



Saline solution, c.c 



0-25 



0-25 

 



0-25 



0-2 



005 



0-25 

 015 

 0-1 



0-25 



01 



0-15 



0-25 

 005 

 0-2 



0-25 

 0-25 

 



0-25 



0-2 



005 



0-25 

 015 

 01 



025 



01 



015 



0-25 





 0-25 



Concentration of Tenom 

 per cent. 



005 



0-04 



0033 



0-02 



001 



0-005 



0004 



0-0033 



0-002 







The tubes, therefore, each contained the same amount of corpuscles (as far 

 as can be judged without actually counting them), the same concentration of 

 sodium chloride, and the same amount of total solution, but differed only in 

 their venom-content. 



Two parallel experiments were done in this way with rabbit's and cat's 

 corpuscles. The tubes were incubated at 35° C. In 3^ hours the cat's corpuscles 

 were hsemolysed completely in tubes 1, 2, 3, and 4, and just not completely 

 in 5. The rabbit's corpuscles were also completely hsemolysed in tubes 1, 2, 

 3, and 4 and there was a trace of heemolysis in 5. There was no trace of 

 haemolysis in any of the other tubes. The tubes were re-shaken, allowed to 

 stand at room temperature overnight and read 15 hours later. The cat's 

 corpuscles were then found to be completely haemolysed in the first six tubes 

 and the rabbit's in the first five. Otherwise stated, in 3^ hours cat's 

 corpuscles are completely haemolysed by a concentration of 0"02 per cent, and 

 almost completely hsemolysed by 0"01 per cent. Eabbit's corpuscles are com- 

 pletely hsemolysed by 0-02 per cent, and slightly hsemolysed by 0*01 per cent. 

 In 18J hours cat's corpuscles are completely hsemolysed by 0-005 per cent, and 

 labbit's corpuscles by O'Ol per cent., under the same temperature conditions. 

 There is, therefore, only a slight difference between the susceptibility of the 

 cat's and rabbit's corpuscles to the haemolytic action of the cobra venom, the 

 cat's corpuscles being haemolysed by slightly lower concentrations. 



The conclusion to be drawn from these experiments is that, though the 



