ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 599 



develope the antlirax vinis iu tlic living organism ; tliougli tbey are 

 not the primary but the secondary factor, and derive their virulence, iu 

 the first instance, from the action of an unorganized chemical poison. 

 These conclusions are somewhat out of date at the present time, 

 and misleading. It has been proved to demonstration that in the case 

 of anthrax, the organism does, per se, constitute the active contagium. 

 The results obtained by Professor Rosenberger, referred to, have been 

 shown* to have been due to imperfect sterilization. In those here 

 described, the absence of infection with small quantities of the super- 

 heated virus, and its occurrence with large quantities, shows evidence 

 of the same phenomena ; some germs or spores of the bacilli survived 

 the boiling, but these were too few in number to be infectious in every 

 small portion of the fluid, though they were so in large quantities. 

 Were a chemical poison, of which comparatively large quantities are 

 requisite, as asserted, the primary factor in infection, the micro-organ- 

 isms alone could never be active in unusual quantities, viz. in the 

 100-millionth of a drop (minim) as has been shown to be the case. 

 The final conclusion of the author here is an obvious paradox, viz. 

 that the micro-organism is at once both cause and effect ; it alone pro- 

 duces the virus — a soluble chemical poison — and is produced by it. 



Attenuation of Virus in Cultivations by Compressed Oxygen. t 

 — Experiments were made by M. Chauveau with compressed oxygen 

 on the bacilli of anthrax, to ascertain whether their virulence could 

 be modified by its graduated action, as by that of heat and other 

 agents ; with the result, at first, that in the case of guinea-pigs the 

 cultivations of the organism exposed to its influence either became more 

 actively virulent at moderate i^ressures, or at high tension completely 

 inactive ; but with sheep, by the action of the agent, the cultivations 

 are modified in their virulence, so that it is not increased by moderate 

 pressure as with guinea-pigs, but on the contrary decreased ; and at 

 a point short of that which stops all development of the microbe, 

 spores are formed, which, though still fatal to guinea-pigs, are 

 innocuous to sheep. 



At this stage of attenuation, however, they produce a temporary 

 affection, more or less pronounced, in all the sheep inoculated, which 

 passes off within a few days, and the animals are found to have 

 acquired immunity from subsequent infection with the most virulent 

 material ; and that by the single inoculation. 



Tliis modification of virus is transmissible to cultivations of the 

 second generation, kept at 36-37° C. under normal pressure. 



It is, too, very remarkable liere, that though usually tlie blood 

 of guinea-pigs wliicli have died of anthrax is fatally infective to sheei^, 

 yet in the case of tlic former the blood of animals that have suc- 

 cumbed to inoculation with cultivations modified by pressure, is 

 innocuous to the latter, and moreover confers on them immunity from 

 future infection. 



Further, these cultivations are so surely attenuated that no single 



♦ PivKT. Roy. Rw., xxxiv. (1882) p. ir>0. 



t ComptcH HfciiduH, xcviii. (1884; pp. 1232-5. 



