The attenuation of the causal agent of fowl cholera
نویسنده
چکیده
1 WOULD LIKE TO REITERATE THE following results, which I have previously had the honor of presenting to the academy: 1. Fowl cholera is a virulent disease of the first order. 2. The virus * consists of a microscopic parasite which multiplies readily in culture away from the animal body: From this it IS possible to obtain the virus in a state of purity and demonstrate irrefutably that it is the sole cause of the disease and death. 3. The virus may vary in its virulence. At times the disease is followed by death, while at other times, after causing disease symptoms of variable intensity, recovery occurs. 4. These differences in the virulence of the virus are not merely the result of natural variations, as the experimenter can alter them at his will. 5. As is generally the case for all virulent diseases, fowl cholera does not recur, or rather the recurrence is of such a degree that it is inverse in intensity with that of the earlier infection, and it is always possible to extend
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