^ XII.] Anthrax. 129 



in by the animal. The starting-points in this migration must 

 then be the places where the fodder is produced, meadows, 

 grazing-grounds, &c. It is obvious that the Bacillus finds 

 opportunity for its vegetation, and in the heat of the summer 

 season the requisite temperature for forming its spores, on the 

 dead organic bodies which are always to be found in these 

 localities, and that when it has once established itself it can pass 

 the winter there (see above, page 51), and thus remain from year 

 to year in readiness to establish itself in a suitable host. 



It is more difficult to say precisely why certain localities 

 are the favourite homes of anthrax whilst others are free from 

 it. Koch has shown some ground for thinking that the 

 preference may be connected with conditions of moisture and 

 inundation, so far as these affect the vegetation and diffusion 

 of the Bacillus. I have not the requisite material for forming 

 a decided opinion. It follows from what has been before said 

 that the Bacillus is not obliged to return from its existence 

 as a parasite and from the body of the attacked or dead 

 animal to saprophytic vegetation in the infected places ; as it is 

 not obliged to pass through the state of parasitism, it can, as we 

 learn from cultures, live as a saprophyte through an unlimited 

 number of generations. On the other hand experience as cer- 

 tainly shows that it can return from the sick or dead animal to 

 the life of saprophytism, for it remains in the animal long after 

 its death and continues alive and capable of growth, and it can 

 in fact return to the ground and to the condition of a sapro- 

 phyte with the bloody dejecta, which, as we are told, larger 

 animals void in a severe attack of anthrax, or with the decom- 

 posing carcases and the substances flowing out therefrom, which 

 are excellent food for them. 



The Bacillus can at the same time also be transported as a 

 parasite from one place to another, and the spots on which sick 

 animals fall down or their dead bodies are buried may become 

 the abodes of the disease, as experience has long since shown. 

 For the same reason a locality may possibly continue perma- 



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