378 
ON THERAPEUTICS. 
secretions and lessening the capillary circulation; they are, 
consequently, directly opposed to the element excess; in 
the course of their operation they improve the tone of relaxed 
membranes, and thus act as tonics, but only indirectly 
through the medium of their astringent properties; their 
characteristic action is to diminish secretion by causing con¬ 
traction of the textures, and at the same time limiting the 
supply of blood and lessening the calibre of the tubes through 
which the secretion passes. 
Internally and externally, ail astringent agents operate in the 
same way, chemically affecting the fluids by coagulating their 
albuminous or gelatinous principles, thus retarding their 
flow, besides inducing a tense and contracted condition 
of the surface. 
Therapeutically, astringents are indicated in a variety of dis¬ 
eases associated with excessive evacuation—in chronic 
diarrhoea or dysentery, in nasal gleet, in excessive discharge 
from wounds or ulcers, instanced in the different stages of 
grease, cankers, thrushes, quittors, fistulous wounds in any 
situation, and in haemorrhage from small vessels. 
The exhibition of astringent drugs internally, with the 
view of producing an action upon a part through the in¬ 
fluence of the agent upon the system, is a mode of procedure 
open to question, as it seems scarcely probable that the 
medicine will circulate unchanged until the desired spot be 
reached; indeed, it is utterly impossible that it should do so; 
but, by its coagulent effect upon the blood, the consistency of 
that fluid may be so modified that excessive exudation is pre¬ 
vented; nevertheless it may be admitted, as a rule, that the 
action of astringents is most decided and most beneficial 
wffen directly induced by contact with the diseased surface, 
and, save in very few cases, such contact may be readily 
effected by the aid of powder or solution. 
The most powerful astringent agents are tannin, matico, 
catechu, and alum. The milder drugs are Armenian bole 
and carbonate and oxide of zinc, all of which may be applied 
as dry powders, or as unguents. Internally alum, catechu, 
and tannin are most commonly exhibited; matico leaves, 
Armenian bole, and the oxide of zinc being generally limited 
to external use. 
In the employment of astringents it is necessary to recol¬ 
lect that they indiscriminately arrest secretions and dis¬ 
charges, without reference to the condition of the part from 
whence the secretion flows; it becomes, therefore, important to 
ascertain whether the flux is of a nature to allow of the 
effects of astringent agents without danger. When the 
