318 THE CONTAGIOUS TYPHUS 



We think that we receive from animals 

 some of their diseases, because the fact is pal- 

 pably evident; thus they have parasitical 

 diseases, such as favus, tsenia, psora, trichi- 

 nosis, which they transmit to us. They are 

 likewise smitten with small-pox, typhoid 

 fever, and with typhus ; and under certain 

 given conditions they may transmit them to 

 us. They die of consumption and cancer, and 

 it is probable that they transfuse into us 

 through their milk and flesh the germs of 

 these diseases. Finally, we have our epidemics 

 as they have their epizootics ; and here we 

 will limit our instances of this reciprocation. 



It is certain that the study of these maladies 

 in animals would have been for us the source 

 of precise knowledge, which, if well under- 

 stood and explained, would have often led to 

 their preventive treatment. This is what has 

 occurred in the case of small-pox ; it is what 

 will one day occur in typhoid fever, in times 

 of epidemic, as will be the case in a certain 

 number of other general or local diseases. 



In truth, some complaints now looked upon 

 as inherent to the human species, were ori- 

 ginally foreign to it ; most parasitical diseases 



