18T7— 1879 259 



blood. The result was identical: death ensued, but no bac- 

 teridia. Were there then two diseases? 



Others made observations in their turn. It occurred to a 

 young German physician, Dr. Koch, who in 1876 was begin- 

 ning his career in a small village in Germany, to seek a culture 

 medium for the bacteridium. A few drops of aqueous humour, 

 collected in the eyes of oxen or of rabbits, seemed to him 

 favourable. After a few hours of this nutrition the rods seen 

 under the microscope were ten or twenty times larger than at 

 first; they lengthened immoderately, so as to cover the whole 

 slide of the microscope, and might have been compared to a 

 ball of tangled thread. Dr. Koch examined those lengths, and 

 Piter a certain time noticed little spots here and there looking 

 like a punctuation of spores. Tyndall, who knew how to secure 

 continuous attention by a variety of comparisons, said at a scien- 

 tific conference in Glasgow a few months later that those little 

 ovoid bodies were contained within the envelope of the filament 

 like peas in their pods. It is interesting to note that Pasteur, 

 when he studied, in connection with silkworm diseases, the 

 mode of reproduction of the vibriones of flachery, had seen 

 them divided into spores similar to shining corpuscles; he had 

 demonstrated that those spores, like seeds of plants, could re- 

 vive after a lapse of years and continue their disastrous work 

 The bacterium of charbon, or 'bacillus antJiracis as it now began 

 to be called, reproduced itself in the same way, and, when 

 inoculated by Dr. Koch into guinea-pigs, rabbits and mice, pro- 

 voked splenic fever as easily and inevitably as blood from the 

 veins of an animal that had died of the disease. Bacilli and 

 spores therefore yielded the secret of the contagion, and it 

 seemed that the fact was established, when Paul Bert, in 

 January, 1877, announced to the Societe de Biologie that it was 

 *' possible to destroy the bacillus anthracis in a drop of blood by 

 compressed oxygen, to inoculate what remained, and to re- 

 produce the disease and death without any trace of the bac- 

 teridium. . . . Bacteridia," he added, *'are therefore neither 

 the cause nor the necessary effect of splenic fever, which must 

 be due to a virus." 



Pasteur tackled the subject. A little drop of the blood of an 

 animal which had died of anthrax — a microscopic drop — was 

 laid, sown, after the usual precautions to ensure purity, in a 

 sterilized balloon which contained neutral or slightly alkaline 

 vi'me. The culture medium might equally be common house* 



