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Diminution of malignancy can be secured in other 

 ways also, which seem to accomplish practically the same 

 result, dilution of the virus. Nocard and Mollereau found 

 that anthrax virus is attenuated by simply mixing it with 

 twice its volume of oxygenated water under pressure. 

 Four hours' contact produces Pasteur's premier vaccin 

 (for the guinea-pig), ninety minutes' exposure the second. 

 Chauveau makes the premier vaccin by exposing anthrax 

 blood to a temperature of 50 C. for fifteen minutes ; and 

 the second vaccin by the same exposure for nine to ten 

 minutes. Since oxygen under pressure, as well as a high 

 temperature, destroys the anthrax bacilli, it would seem 

 that these methods accomplished merely a dilution of the 

 virus by killing a certain number of the contained organ- 

 isms ; for in the brief time required in these experiments 

 a physiological modification seems scarcely possible. 



According to a communication presented by Bouley 

 to the French Academy of Medicine, Peuch discovered 

 that the effects of tag-sore virus (variola in sheep) de- 

 creased by simple dilution with distilled water. 

 Is. In the case of chicken cholera also, the characteristic 

 organisms of which have been " modified " by Pasteur 

 through a long and interesting process, there is reason to 

 suppose that this modification may be simply a dilution. 

 For vaccination against the disease has been successfully 

 practised by simply introducing into the animal a piece 

 of blotting-paper on which the blood of an infected ani- 

 mal has dried. The bacteria in dried anthrax blood die 

 in a few weeks, but those still living at a given moment 

 exhibit their original functions if transferred to a proper 

 soil, and it seems probable that the diminished virulence 

 of dried chicken cholera blood is due to the death of 

 some of the contained organisms rather than to a physio- 

 logical modification. This belief is strengthened by a 

 letter recently received from Dr. D. E. Salmon, of Ash- 

 ville, N. C., in which he says : "I have vaccinated fowls 

 experimentally, both by Pasteur's method and by a 

 method of my own. My method is simply inoculation 

 with a very diluted virus ; when sufficiently diluted it 



