.ETIOLOGY AND PATHOLOGY. 187 



immunity by producing the disease in other sheep at the first 

 operation. 



With two conditions of system favourable to the develop- 

 ment of anthrax we are from long experience familiar. These 

 are, that there be no other disease present, and, as we also 

 mentioned when speaking of its general characters, that the 

 animal be in what is commonly known as a ' thriving condi- 

 tion;' and it appears to us that where the elaboration and 

 assimilation processes are put to their utmost tension we have 

 the most genial soil or the highest state of receptivity. In the 

 same light we may view the reason of youth being the most 

 frequent period of attack. To induce this plethoric habit of 

 the animal it is essential that its food shall not only be 

 abundant but highly charged with nutritious matter. That 

 food of this character is grown more especially in low-lying 

 moist lands in warm weather is well enough known to most 

 people, as is the fact that manurial richness is most conducive 

 to its production. 



Here then we have three conditions which seem to be most 

 favourable to the growth of highly stimulating fodder — moisture, 

 heat, and manurial richness. As we proceed to look more 

 closely into the life-history of bacillus anthracis, we shall find 

 that the same conditions are probably the most congenial to 

 its growth and development. 



Though there has been much variety of opinion as to some 

 parts of the pathology of anthrax, there has been a general 

 agreement that it is much more prevalent in low-lying lands 

 and swamps— thus it has been attributed to malaria, etc. ; 

 while as to the beneficial results of removing water from the 

 surface of lands by draining, etc., we have abundant proof. 

 That heat is essential to render conditions favourable to 

 activity of bacillus anthracis is sufficiently evident to us, not 

 only from experiment in the artificial cultivation, but also from 

 actual observation of the disease as naturally occurring. The 

 same may be said when referring to the effect of vegetable 

 infusions, as we may, we think, appropriately term the stag- 

 nant moisture we meet with under certain circumstances on 

 swamps, morasses, etc. Having regard to these facts, it is 

 scarcely to be wondered at that, at a time not far distant, 

 anthrax was held to be the result of malaria and miasmata. 



