444 
ESSAYS ON HOUSE MEDICINE. 
this imaginary acrimonious matter, instigates a diseased action in 
the constitution for that purpose ; which it may be right to pro¬ 
mote, but is on all occasions wrong, on the part of the practitioner, 
either to check or to suppress. On which accounts it was that 
this doctrine, when introduced into practice, turned out to be 
pregnant with all sorts of dangers. 
Unsupported by the progress of science, and both inefficacious 
and dangerous in practice, the humoral pathology gave place to 
a set of more sound and wholesome principles: as commonly 
happens however, on such occasions, the introduction of an en¬ 
tirely new doctrine has not been brought about altogether exempt 
from error, or, at least, from that which has given rise to fresh 
dispute. 
For example, the blood, the principal of the humours, although 
it occasionally exhibits morbid appearances, is yet, it is said, 
never in itself diseased ; in other words, does not imbibe any 
morbific ingredient. In support of which doctrine, the two 
principal arguments are, first, that if it were in itself in a state of 
disease, at it flows to every part of the body, the morbid matter 
it contains ought to create general and not local irritation; and, 
secondly, that if it were so in contagious diseases, we ought, by 
means of inoculation with it, to produce effects such as arise from 
the actual introduction of contagious matter. In reply to the first 
of these arguments, it may be asked, if there exists any disease 
that affects alike all parts; and why, on the contrary, so many 
seem to have a predilection for particular organs or structures ? In 
man, for instance, small-pox and measles manifest their influence 
upon the skin in particular; scrofula is a disease of the absorbent 
system; the venereal disease attacks the organs of generation, 
the throat, the skin, and the bones. In the horse,we have farcy, 
which is a disease of the superficial absorbents, in exclusion to 
vessels of the same class and kind that are deep-seated; and 
glanders generally confines its ravages to the mucous membranes 
of the nose and sinuses of the head. And yet, all these are (with 
the exception of scrofula) contagious diseases, in most of which, 
if not in all, the circulating mass of blood is contaminated. 
The second of these positions is still less tenable than the first. 
No one ever imagined that any morbific matter the blood might 
contain, existed therein in so concentrated a form as to take 
effect through the medium of a drop or two of that fluid ; any 
more than that glandered or venereal virus, diluted with fifty or a 
hundred times its weight of healthy matter, would impart the 
disease through inoculation with a fiftieth or a hundredth part of 
such a mixture. Do we not, medicinally, take (not only without 
any baneful influence, but with great and decided benefit) small 
