GENERAL DISEASES. 71 



degree favourable to the growth and development of these 

 low forms of vegetable life. 



The same influences also may act upon animals, rendering 

 them more fitted for the reception of these germs, and we 

 know, from many experiments, of what great significance 

 the nature of the soil or pabulum is to the growth and mul- 

 tiplication of bacteria. We may mention three instances : 



Fowls were once believed to possess an immunity against 

 anthrax, Now, M. Pasteur showed, by immersing fowls in 

 water and thus lowering their temperature, he was able to 

 inoculate them with the disease, though when not thus 

 immersed he was unable to induce the development of 

 anthrax in them. 



Again, rats, when fed on animal diet, resisted inoculation, 

 while others, fed on bread, readily contracted the disease. 



Chauveau was unable to inoculate Algerian sheep by the 

 ordinary method, though virus from the same vessel readily 

 induced the disease in other sheep. 



These experiments illustrate clearly of what importance 

 the nature of the soil is to the growth of the germs placed 

 in it. Animals in which no other disease is present, and 

 those in a plethoric condition, are especially liable to attack, 

 and young animals, also, are more likely to contract the 

 disease than older ones. And it is in those warm, low-lying, 

 marshy districts, where food especially rich in nutritive 

 value is grown, and where, in consequence, animals are 

 best nourished, that they afford a more genial soil for the 

 reception of these vegetable parasites. 



Again, it has been shown in many cases in moist districts, 

 where anthrax has been long endemic, that after thorough 

 drainage the disease disappeared entirely. 



A hot, stifling atmosphere, charged with electricity, is 

 said also to favour the development of these germs. 



Modes of Propagation of this Disease. — Many attacks 



