Transformation y etc., of Pathogenic Microbes. 85 



less serious, and the chances of infection for the indi- 

 viduals yet exempt and which are, moreover, the 

 most refractory, will rapidly diminish. 



The disease may be continuous (charbon), remittent 

 (tuberculosis), or intermittent (malaria). 



CHAPTER III. 



TRANSFORMATION AND DESTRUCTION OP PATHOGENIC MI- 

 CROBES IN THEIR RELATION WITH HYGIENE AND 

 THERAPEUTICS. 



1. Morphological and physiological variations of pathogenic mi- 

 crobes. — 2. Attenuation. — 3. Preventive inoculations. Vac- 

 cinations. — 4. Destruction and annihilation of pathogenic 

 germs. 



1. Morphological and 'physiological variations of patho- 

 genic microbes. 



"We have already, in the first part of this work, re- 

 ferred briefly to the influence of the media upon mi- 

 crobes in general. This influence acquires great 

 importance when pathogenic germs are in question. 

 The latter may undergo considerable changes under 

 the influence of external conditions. 



Pathogenic germs undergo, from this cause, varia- 

 tions of form and of function. 



Physical variations are quite common : the microbe 

 of avian cholera shrinks when its cultures become 

 old; that of rouget, cultivated after its passage 



