ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 499 



countries, undoubtedly lies dormant for certain periods in a mitigated 

 form ; and the same is the case with the typhus of camps, which 

 is not thiis limited in space ; man himself may carry the germs 

 until circumstances, such as climatal conditions, famine, and weak- 

 ness, give opportunities for their development. 



Inoculation a means of protecting Sheep against Charbon.* — 

 This fact is admitted by Messrs. L. Pasteur, Chamberland, and 

 Eoux, to have been already proved by M. Toussaint.f but lhey 

 dispute some of his opinions and facts relating to the subject. Thus 

 his view that the virus-vaccine of this disease is a lifeless substance 

 produced by the bacterium is in conflict with M. Pasteur's facts 

 proving the vaccinating agent in cholera and fowl-cholera to be an 

 organized body. Experiments made by the above-named authors to 

 test M. Toussaint's conclusions show that the bacterium of charbon 

 is not killed by a temperature of 55° C, even after an exposure to it of 

 thirty minutes, but that its vitality is modified ; when it really is 

 killed, the solution thus sterilized does not confer immunity from the 

 disease, as M. Toussaint asserts ; hence his many failures to confer 

 this immunity. With regard to blood supjjosed to be sterilized by 

 filtration, such blood either gives the disease, or it has no preservative 

 action, and the method of filtration is defective. A difference which 

 appears to exist between the mitigated form of the charbon and that 

 of fowl-cholera is, that it is only the latter which is capable of repro- 

 ducing itself in a condition in which it maintains its harmless 

 properties ; the absence of this property in charbon is a most serious 

 difficulty, and involves great risk in the application of inoculation. 



Charbon-vaccin |— Enlarging upon the facts already known of 

 this material, the same three authors state that the bacterium under 

 its most deadly form undergoes sufficient modification by twelve days' 

 exposure to the air in fowls' broth at 42°-43° C. to prevent its being 

 fatal to adult guinea-pigs; in thirty-one days these animals, as well 

 as rabbits and sheep, withstood the effects of a fresh growth prepared 

 at 35° C. from the former one ; in forty-three days a fresh growth 

 killed only guinea-pigs a few hours old. The bacterium now never 

 resumes its virulence. It is remarkable that this modified form 

 differs from the deadly agent of charbon only in its shorter and more 

 divided filaments when grown in small quantities : it forms a uniform 

 deposit on the walls of the vessel instead of cottony tufts made up 

 of long threads ; but if it forms spores, they give rise to a more 

 deadly form. The bacterium differs from fowl-cholera in this pro- 

 perty of producing spores ; those formed by its less deadly stages 

 retain the degree of modification possessed by these stages, and do 

 not revert to the original virulence. 



M. Bouley,§ referring to the two preceding papers by M. Pasteur, 

 points out, what M. Pasteur had admitted, that M. Toussaint had 

 already withdrawn his erroneous conclusions referred to. 



* Comptes Eendus, xcii. (1881) pp. 662-5. 

 t Cf. this Journal, iii. (1880) pp. 1016-18. 

 X Comptes EeaduB, xcii. (1881) pp. 666-8. § Ibid., p. 6i,8. 



