The bacteriolytic substance in venom is distinct from that which produces proteolysis, for the latter is destroyed at 80° C., while the former only disappears with a temperature of and beyond 85° C. maintained for half an hour. It is likewise distinct from the hæmolysin, for this resists temperatures considerably higher than 85° C. Moreover, venom which has dissolved microbes until the saturation point has been reached, is found to have preserved in its entirety its hæmolytic power upon the red corpuscles of the horse. Neither does it act upon the microbes owing to the presence of a _cytase_ or _alexin_. The well-known characteristics of alexins are not met with here--destruction at 55° to 56° C., sensitivity to light, rapid alteration at ordinary temperatures, &c. We cannot, again, compare the bacteriolytic action of venom to that of rat-serum, which dissolves _B. anthracis_ by aid of a substance distinct from vibrionicide alexin. According to the researches of Malvoz and Y. Pirenne, the lysin of rat-serum appears to be a basic substance, the neutralisation of which destroys its activity. Now _Cobra_-venom in a very active solution is perfectly neutral to sensitive litmus papers, while these are turned blue by rat-serum. Moreover, venom acts not only upon microbes of the same kind, but also on very different species which are not affected by rat-serum, especially upon _B. pestis_, for which, on the contrary, this serum, when fresh, proves a favourable culture medium. The bacteriolytic power of _Cobra_-venom therefore constitutes a special property of venom. “In their work on the cytolysins of venom, S. Flexner and Noguchi have shown that animal cells, when heated to 55° C. and rendered inactive, do not undergo complete dissolution under the influence of venoms which destroy the fresh cells. The authors in question infer the existence of cellular receptors (_endo-complements_, according to the theory of Ehrlich), which fix the amboceptors of venom. Pursuing the same order of ideas, I have observed that bacteria killed by heating for one hour at 60° C. do not undergo total disintegration as do living bacteria. But, while Flexner and Noguchi infer the plurality of the cytolysins in venom for different animal cells, I have not been able to prove the same thing with regard to the bacteriolysin; venom saturated with cholera vibrios to such an extent that vibrios added at repeated intervals are no longer dissolved, is incapable of dissolving another highly sensitive species of microbe, such as the asporogenous bacterium, and _vice versâ_. Besides, it would be difficult to understand the existence in venom of cytolysins specific for a whole series of species of micro-organisms” (Noc).[59]