They employed for their experiments 5 per cent. emulsions of organs, spermatozoids, or ova in physiological saline solution. The solution of venom at a strength of 1 per cent. was kept in contact with the different kinds of cells for three hours at a temperature of 0° C.; the liquid was then centrifuged and examined with the naked eye and under the microscope. The venoms experimented upon dissolved more or less rapidly the parenchymatous cells of the liver, kidney and testicle of the dog, guinea-pig, rabbit, rat and sheep. The most active venoms in this respect were those of _Vipera russellii_, _Ancistrodon_ and the _Cobra_; the venom of _Crotalus_ was the least active. With regard to the nerve-cells, spermatozoids and ova of cold-blooded animals (frogs, fish, arthropods, worms, and echinoderms) _Cobra_-venom proved to be the most active; then that of _Ancistrodon_, and lastly that of _Crotalus_. These cytolysins are not destroyed by heating for thirty minutes at 85° C. in a damp medium, nor by dry heating for fifty minutes at 100° C. C.--BACTERIOLYTIC ACTION. If we bring into contact with a 1 per cent. solution of _Cobra_-venom, rendered aseptic by filtration through porcelain, sensitive micro-organisms, such as the cholera vibrio, or the bacterium of anthrax in a very young non-sporulated culture, or in its non-spore-producing variety, we find that these microbes are dissolved by the solution of venom in varying periods of time. On making a direct microscopical examination we see that Koch’s vibrios become immovable, then break up into granulations and disappear in the liquid. The bacteriolysis is even more distinct in the case of the bacterium. The enveloping membrane seems to dissolve, and the microbe appears as though composed of a series of granulations placed end to end, which finally disperse and disappear. By my instructions this bacteriolytic property of venom with respect to different species of micro-organisms was studied by Noc. It was especially clearly seen with the non-spore-producing bacterium of anthrax, the cholera vibrio, _Staphylococcus aureus_, the bacillus of diphtheria, and _B. subtilis_ in a young culture; it is less distinct with _B. pestis_, _B. coli_, and _B. typhi_, is almost _nil_ with the pyocyanic bacillus and _B. prodigiosus_, and _nil_ with _B. tuberculosis_. Investigations have likewise been made by Noc, and subsequently by Goebel,[58] in order to determine whether cobra-venom dissolves Trypanosomes. These hæmatozoa are more resistant than bacteria, but they nevertheless end by being dissolved after twenty to thirty minutes’ contact in the 1 per cent. solution.