Epidemics. 159 



isolated to given orders of organized beings and objects, 

 and by fine forms of differentiation, amidst a thousand forms 

 of vegetable growth, a potato or a wheat field is selected ; 

 and every spot of vegetable life surrounding this field, or 

 particular class of vegetable, is growing in luxuriance, 

 amidst the cold sheet of death which is shrouding in decay 

 its smitten neighbour. 



The fox runs to and fro from place to place, and, just 

 infected by contact with a neighbouring fox, enters a hen 

 roost, kills a hen, and leaves the rest, from fear of a sur- 

 prisal by the farmer's dog, whose approach is known by his 

 cry. Not a death occurs from his disease; no pheasants, 

 hares, or ruminants of any kind fall victims to the dis- 

 temper the fox holds within his active frame ; but himself, 

 and every fox he meets, falls a victim to that particular 

 disease he has. Again, if it is not infectious, then all the 

 more singular it is that an influence which is diffused over 

 a. large tract of land should only isolate one species; and, by 

 some subtle differentiation in vital conditions between the 

 fox and every living being by which the fox is surrounded, 

 the evil or the destructiveness of the differentiation only 

 falls to the special organism called the fox, whose shade of 

 differentiation in vital power and function is bound by such 

 fine lines of variation as to defy the most exact scan of 

 human induction and human knowledge. 



The tenants of the deep, from time to time, have shown 

 the same tendency for epidemic influence to spend its devita- 

 lizing force, or to divert the vital force into an especial 

 channel or order of organism. What applies to vegetables 

 and animals applies with equal force to man. From one 

 end of nosology to the other, in every widespread epidemic, 

 we have the reiterated assurance that this form of disease is 

 a part of the existing epidemic influence ; and the other 

 form of disease belongs to a distinct order of affection to 

 the prevailing epidemic. 



