8o 4 THE POPULAR SCIENCE MONTHLY. 



veloprnent, they will, when inoculated with virulent virus, suffer no evil 

 effects, or only effects of a passing character. In fact, they no longer 

 die from the mortal virus, and, for a time sufficiently long, which in 

 some cases may exceed a year, chicken -cholera can not touch them, 

 especially under the ordinary conditions of contagion which exist in 

 fowl-houses. At this critical point of our manipulation that is to 

 say, in this interval of time which we have placed between two cult- 

 ures, and which causes the attenuation what occurs ? I shall show 

 you that, in this interval, the agent which intervenes is the oxygen of 

 the air. Nothing more easily admits of proof. Let us produce a cult- 

 ure in a tube containing very little air, and close this tube with an 

 enameler's lamp. The microbe, in developing itself, will speedily take 

 all the oxygen of the tube and of the liquid, after which it will be quite 

 free from contact with oxygen. In this case, it does not appear that 

 the microbe becomes appreciably attenuated, even after a great lapse 

 of time. The oxygen of the air, then, would seem to be a possible 

 modifying agent of the virulence of the microbe of chicken-cholera 

 that is to say, it may modify more or less the facility of its develop- 

 ment in the body of animals. May we not be here in presence of a 

 general law applicable to all kinds of virus? What benefits may not 

 be the result ? We may hope to discover in this way the vaccine of 

 all virulent diseases ; and what is more natural than to begin our in- 

 vestigation of the vaccine of what we, in French, call charbon ; what 

 you, in England, call splenic fever; and what, in Russia, is known as 

 the Siberian pest ; and, in Germany, as the Milzbrand ? In this new 

 investigation I have had the assistance of two devoted young savants 

 MM. Chamberland and Roux. At the outset we were met by a 

 difficulty. Among the inferior organisms, all do not resolve them- 

 selves into those corpuscle-germs which I was the first to point out as 

 one of the forms of their possible development. Many infectious 

 microbes do not resolve themselves, in their cultures, into corpuscle- 

 germs. Such is equally the case with beer-yeast, which we do not see 

 develop itself usually in breweries, for instance, except by a sort of 

 scissiparity. One cell makes two or more, which form themselves in 

 wreaths ; the cells become detached, and the process recommences. 

 In these cells real germs are not usually seen. The microbe of chicken- 

 cholera and many others behave in this way, so much so that the cult- 

 ures of this microbe, although they may last for months without losing 

 their power of fresh cultivation, perish finally like beer-yeast which has 

 exhausted all its aliments. The anthracoid microbe in artificial cult- 

 ures behaves very differently. In the blood of animals, as in cultures, 

 it is found in translucid filaments more or less segmented. This blood 

 or these cultures freely exposed to air, instead of continuing according 

 to the first mode of generation, show, at the end of forty-eight hours, 

 corpuscle-germs distributed in series more or less regular along the 

 filaments. All around these corpuscles matter is absorbed, as I have 



