CHAPTER X 



MODES OF DESTRUCTION OF BACILLI PESTIS 



1. By Drying. 2. Spontaneous. 3. By Chemical 

 Disinfection. 



1. Drying. — Already in Chapters VII. and IX. we have 

 fully described experiments by which it was shown that 

 plague materials exposed in the laboratory to various 

 forms of drying on different materials — cloth, linen, wood, 

 grain, in earth, and in sand — lose their infective power, i.e. 

 their efficacy qua B. pestis ; that is to say, the B. pestis 

 contained in these materials become sooner or later 

 devitalised; and there is no reason to doubt that such 

 would be the case also under natural conditions. Experi- 

 ments of drying thin watery or salt emulsions or broth 

 cultures, applied as thin films on cover-glasses— a method 

 practised by some observers in determining the death 

 point of B. pestis by drying — are not of much practical 

 value, since this method of drying does not occur in nature. 

 The experiments with plague organs and gelatine cultures 

 which I have described in Chapter VII. were fully in 

 harmony with and in imitation of what we might suppose 

 to occur under natural conditions. The B. pestis, being 

 a non-sporing microbe, comports itself like other non- 

 sporing bacteria, inasmuch as when thin films of salt or 



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