X Introduction. 



nition of the germs is the only mode of definitely 

 establishing the nature of a lesion. 



Every one can understand how desirable it is that 

 the practitioner, meat inspector or sanitary veterina- 

 rian, whose decisions very frequently run counter to 

 some particular interest, should pronounce himself 

 only after having made use of this last resource 

 which will protect him from scientific mistakes and 

 contradictions, always much to be regretted. 



A like exactitude is to be desired in private prac- 

 tice, where it will form a basis for sound therapeutics. 



"We will briefly trace the history of those microbes 

 which may be of interest to the practitioner, and de- 

 scribe the technique of those investigations which he 

 may daily be called upon to make. Our study will 

 embrace three divisions. In the first we will briefly 

 consider the subject of microbes in general ; in the 

 second we will study pathogenic germs collectively ; 

 and in the third notice those particular microbes 

 which occasion disease in animals and even in man- 

 kind. 



