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132 .., 'BACTERIOLOGY. 



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resistance to the action of chemical reagents and 

 heat than the parent cells. 



Spore- formation has been regarded by some as 

 occurring when the nourishing soil is exhausted, 

 thus providing for the perpetuation of the species. 

 For instance, anthrax bacilli do not form spores in 

 the living body, but when the animal dies it has 

 been stated that development of spores takes place, 

 and hence the danger of contaminating the soil if 

 the body is disposed of by burial. Klein, however, 

 has pointed out that if mice and guinea-pigs which 

 have died of anthrax are kept unopened, the bacilli 

 simply degenerate and ultimately disappear. Thus 

 there is good reason for believing that spore-forma- 

 tion is not due to exhaustion of the pabulum, but 

 probably free access to oxygen constitutes an im- 

 portant factor in inducing this condition. If we 

 inoculate a potato with anthrax, copious spore-for- 

 mation occurs, though we cannot consider that the 

 nourishing soil has been exhausted. But we have 

 in this case the surface of the potato freely exposed 

 to the air in the damp-chamber. In the same way, 

 in cultivations on agar-agar solidified obliquely, so 

 as to get a large surface, spore- formation readily 

 takes place. Contamination of a burial-ground 

 must result, therefore, from bodies in which a post- 

 mortem examination has been made, by which the 

 blood and .organs have been freely exposed to 

 the air, or from animals which have not been 

 examined, owing to their hides being soiled with 



