ON THE EXTERNAL CAUSES OF DISEASE. 5o3 
experiment of transfusing the blood of a glandered horse into the 
veins of a healthy one, previously prepared by copious blood¬ 
letting,—he produced the disease in all its virulent characters. 
Therefore the question now is, do the morbid changes which 
are observable in the fluids merit the name of disease? Or, in 
other words, can they be the seat of primitive alterations or not ? 
We are of opinion that they are. 
We have already shewn the mode and channel by which the 
blood may become empoisoned; and we have likewise stated, 
that in all diseases arising from aerial poison, it was contami¬ 
nated : the latter part of this sentence, w^e believe, no one will 
attempt to dispute. The following experiments confirm w'hat 
Ims been before stated, for they prove, beyond a doubt, that the 
different agents which produce specific diseases are first carried 
into the circulation before they produce specific effects upon par¬ 
ticular parts. Mr. Hunter found that infusions of opium, ipeca¬ 
cuanha, rhubarb, jalap. See., when received into the circulation 
by the jugular vein, produced the same effects as when taken 
by the mouth. 
Sir E. Home proved the same with colchicum. In instances 
of animals being killed by arsenic taken internally, the stomach 
is found bearing marks of inflammation ; the generally received 
opinion is, that it is caused by the actual contact of the arsenic 
on the internal coat of the stomach. But many circumstances 
tend to shew, that it is not altogether correct, since in whatever 
way the poison is administered, the inflammation is confined to 
the stomach and bowels. “ Mr. Hunter applied arsenic to a 
wound in a dog: the animal died in 24 hours, and the stomach 
was hijiamed. Mr. Brodie repeated the experiment several times, 
taking the precaution to apply a bandage to prevent the animal 
from licking the wound, and the result W'as, that the inflamma¬ 
tion of the stomach was commonly more violent and more im¬ 
mediate than when the poison was administered internally*.” 
From this w^e may safely conclude, that arsenic, in whatever way 
' it is administered, does not produce its effects on the stomach 
until it is first absorbed and carried into the circulation. 
* Philosophical Transactions, 1812. 
