THE 
VETERINARIAN. 
VOL. XLII. 
No. 501. 
SEPTEAIBER, 1869. 
Fourth Series. 
No. 177. 
Communications and Cases. 
ON THE EECIPEOCAL INFLUENCE OF ANIMALS 
IN THE PRODUCTION OF DISEASE. 
By G. Fleming, Royal Engineers. 
Among the many more notable causes which tend to the 
production of disease in man and the lower animals, there is 
one which, I think, has received hut little attention, probably 
from the comparative obscurity which attends its operations, 
the fact that these operations are generally overlooked in dis¬ 
cussing the more salient characteristics of the actual organic 
disturbance, and also, in all likelihood, because the observa¬ 
tions necessary to accurately define this influence and the ex¬ 
tent of its power are somewhat few and far between. I allude 
to the reciprocal action or influence of animals of the same or 
diverse races on each other in the production of special 
maladies, even when previously healthy. 
Among the observations which appear to establish the ex¬ 
istence of such an influence there are some which have long 
been accepted as correct, and therefore reliable, while others 
require further investigation before they can fairly be admitted 
as evidence. In the following remarks I will adduce the 
principal facts relating to this matter with which I am 
acquainted, my desire being merely to point out to those who 
are favorably situated for the observation of such interesting 
occurrences in comparative pathology that such an influence is 
in operation, and that by extending the sphere of inquiry much 
valuable information may be added to that already acquired. 
XLII. 44 
