SOCIETY MEETINGS. 
749 
great and useful sphere in veterinary practice. Their use in 
human medicine is of great antiquity, for they were mentioned 
b) ancient wiiteis on medicine, but there are few of our people 
to-day who would consent to be “marked” with a hot iron for 
the alleviation of pain or the cure of disease. True, the hot 
iron is still used as a counter-irritant, but only to promote a 
slight congestion of the skin, and when so used, is first heated 
m boiling water and then lightly applied, or if heated to a red- 
heat, the iron is slowly waved back and forth near the skin. 
Counter-irritants are commonly divided into two classes, in¬ 
ternal and external. Internal counter-irritants are known as 
revulsives or derivatives, and may be defined as remedies 
which, by producing a modified action in some organ or tis¬ 
sue, derives from the morbid condition of some other organ or 
tissue. ’ A very familiar example is the administration of a 
drastic purgative to relieve active cerebral hyperemia or a pow¬ 
erful diuretic to deplete the system in dropsical conditions. Ex¬ 
ternal‘counter-irritants are those which are used upon the surface 
of the body and is the more common use. These only will be 
considered as within the scope of this article. They may be 
defined as “ substances used externally to produce a reflex influ¬ 
ence on a part more or less remote from the site of application.” 
It is true that these drugs are sometimes directly applied to the 
part to be relieved or strengthened, but as the subject of coun¬ 
ter-irritants is too extensive to be discussed in all of its phases 
we will omit this one as of minor importance. 
This second class is again divided according to severity of 
action: (i) Those of mild action or rubefacients, which only 
cause a congestion of the skin. If their action is continued, 
they may become vesicants, in which vesicles or blisters are 
formed. This is an eructate or outpouring of serum into the 
lower layers of the epithelium and liquefaction of epithelial cells 
beneath the horny layer, which causes vesicles to appear to be 
between the epidermis and derma. If contact is still continued, a 
third subdivision is reached called escharotics, involving destruc¬ 
tion of all tissues to which the irritant is applied and the forma¬ 
tion of a. slough. A fourth subdivision, still more severe in 
I action, is pustulants, which give rise to pustules on the parts to 
which the) 7 are applied, as the orifices of the cutaneous glands. 
A fifth subdivision is setons and rowels, which are inserted 
through openings in the skin or the injection of an irritant sub¬ 
stance beneath the skin, and are used to set up a deep-seated 
long-continued and extensive inflammation. 
