"The Lancet" reports of the International Congresses of Hygiene and Demography : held from 1876 to 1889.

  • The Lancet
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: "The Lancet" reports of the International Congresses of Hygiene and Demography : held from 1876 to 1889. Source: Wellcome Collection.

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    formed by a special cultivatable microbe, and other and various microbes capable of occasioning death by the exaggerated production of pus, by excessive local disorders, and sometimes by the introduc- tion into the blood of ordinary microbes. The new microbe dis- covered in the saliva of persons suffering from hydrophobia has sub- sequently been found in the saliva of persons who died from other diseases ; it therefore accompanies, but has no special relation with, the virus of rabies. Nevertheless, this is the third virulent microbe which can be attenuated by the action of oxygen, and the history of this third microbe is as yet unpublished. M. Pasteur offered the Congress the first record of these new experiences. He found that the microbe of the saliva was governed by the same laws as those that influenced the virulence of the microbe of the cholera in chickens. M. Thullier had the patience to cultivate eighty gene- rations of microbes found in the saliva of a patient who died of hydrophobia, and the eightieth generation was as virulent as the first. But if the successive cultures were submitted to the action of air, then the result is not similar to that obtained with the microbe of chicken cholera. The microbe from saliva dies very rapidly. Two or three days’ exposure to air often suffices to render the microbe sterile. A culture coming from virulent blood will live from six to twelve days, but in each successive batch the duration of virulence is reduced. The eighth generation will not live longer than three or four days; the twenty-fifth, twenty-six hours; and the forty-eighth, twenty hours. .These latter cultures, if inoculated in rabbits, will not always kill them, and the rabbit, having survived the mild inocula- tion, can then take the virulent poison with impunity. Yet the rapidity with which this microbe loses its virulence renders it very difficult to discover the moment when in its increasing vitality it would constitute a safe vaccine. ‘To do this itis necessary to prolong the life of each crop. This great end can now be attained by employing a new vehicle. The microbes generally live best in veal broth ; but by mixing two parts of this broth with one part of pure rabbit’s blood, M. Pasteur finds that the life of microbes derived from saliva can be prolonged to forty or fifty years. By taking the microbes during the last ten days cultures of graduated virulence can be made, and thus a vaccine of various degrees of strength obtained. It is to the action of oxygen that we must again attri- bute the modified strength of these cultures. To the microbes men- tioned—the microbe of chicken cholera, the microbe of charbon, the microbe of saliva, especially the saliva of rabies—M. Pasteur concluded by adding a fourth microbe that was discovered in the foam taken from the nostrils of the horses that died during the typhoid epidemic at Paris in 1881. By inoculation with this germ rabbits died of true typhoid. With infinite pains M. Pasteur succeeded, and still by the use of oxygen, in so cultivating and reducing the virus of the typhoid microbe, that he was at last able to vaccinate rabbits without killing them; but, on the contrary, when he subsequently inoculated them. with the virulent poison, they did not feel its effects. Thug
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