Manual of veterinary microbiology / by Professors Mosselman and Liénaux ; translated and edited by R.R. Dinwiddie.

  • Mosselman, Gustave.
Date:
1894
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Manual of veterinary microbiology / by Professors Mosselman and Liénaux ; translated and edited by R.R. Dinwiddie. Source: Wellcome Collection.

    314/360 (page 310)
    In order to obtain a regular and stable attenuation Pasteur starts with the cord of a rabbit which has been rendered rabid by means of fixed virus; he di- vides it into segments of two centimeters in length and these he suspends in a wide-mouthed liter bot- tle containing pieces of caustic potash; this bottle is placed in a chamber in which the temperature is maintained at 20° C. Variations in the temperature lead to modifications in the attenuation; at 28° the virulence is destroyed in five days ; at 35° in four hours. The Russian rabbit, which has a smaller cord, al- lows of a more rapid attenuation. The temperature and the oxygen of the air are instrumental in producing this loss of pathogenic activity; the attenuation is slower in carbonic acid; the loss of humidity seems to have less influence; Protopopoff has, indeed, shown that this medication occurs also in glycerin-bouillon. Authorities are far from being unanimous as to the theory of this attenuation. Pasteur thinks that it consists merely in an impoverishment in active virus and not in a diminution of activity. The hypothesis of a chemical vaccine has been dis- pelled by Babes who showed that the rabic sub- stance filtered through porcelain, as well as that heated to 100°, has no vaccinal property. Gamaleia has demonstrated that vaccinal injections have no. action on an individual already affected with the dis- ease, which also dispels the theory of a chemical vac- cine. Virus attenuated by desiccation regains the activity of the fixed virus on its second passage through the rabbit,