Histojy of Animal Plagues. 293 



of it, in all, even the most virulent of contagious distempers. In 

 what this disposition in an animal to be acted upon immediatelv 

 consists, we are not enough in the secrets of nature to explain, 

 any more than we can tell what constitutes the specific essence 



of any contagion I never denied it to be possible in the 



height of some very violent plagues (when a great quantity of j 

 pestilential vapours are continually exhaling from innumerable 

 bodies — both living and dead), for some of the contagious effluvia 

 to be carried from the places of their emission, by a current of 

 wind constantly running in the same direction, to a considerable 

 distance; by which means I can easily conceive it possible for 

 some people, who have no commerce with the infected, to live 

 within the limits of the progress of these contagious effluvia, and 

 consequently within the influence of their power. But supposing 

 these facts could not be thus accounted for, I would beg leave to 

 ask, whether these authors do not seem to have been too hasty in 

 affirming there was no communication between these people 

 living at a distance and the infected places ? For what they 

 affirm is a negative which cannot be proved, and therefore ought 

 not to be admitted. If by no communication they mean only no 

 communication of the same species of animals, that will not 

 answer their purpose; because contagion may undeniably be com- 

 municated by many other ways, many of which might be practised 

 without falling under the observation of the persons who re- 

 ceived the infection. All other species of animals may carry it 1 

 without being infected by it themselves, and as nothing is known 

 to retain infection more than hair, it mav, and doubtless has been , 

 carried by animals who have strayed from the infected to the 



sound Neither does diet any better account for this ) 



excessive mortality. For these exclusively mortal distempers 

 equally destroy all creatures of the same species, however differ- 

 ently dieted. We cannot, therefore, but subscribe to the general 

 opinion concerning the principal cause of such excessive mortality, 

 and acquiesce in their judgment, who have imputed this eilect 

 to pestilential contagion. It only remains, then, to incpiire 

 whether the confessed mortality of the present distemper lias not 

 always been excessive in every condition of air and diet, for a 

 long time after its first breaking out? And as a proof that it 



