ON THE VETERINARY MATERIA MEDIC A. 45 
agulum will be instantly formed, firm, not subject to putrefac¬ 
tion, and insoluble except in an excess of gelatine. Into a small 
quantity of soup, or broth, let a little of the solution of tannin be 
dropped, and a curdy precipitate will be formed. Tannin con¬ 
stitutes half of the substance of catechu, and something: re- 
sembling these experiments, but, modified by the influence of the 
vital principle, may be the effect of the catechu when taken medi¬ 
cinally. Either it may constringe or contract the parietes of the 
exhalent vessels, composed principally of gelatine, or it may 
coagulate the fluids contained in them, and arrest their progress. 
The first and immediate effect is, to restrain excessive dis¬ 
charge. That discharge is kept up by the irritable state of the 
exhalent mouths. The discharge being stopped or lessened, this 
irritability rapidly subsides, and the irritability of the neighbour¬ 
ing parts over which the discharge had flowed, and, gradually, 
of the system generally, and of the determination of blood to the 
over-excited part, and the exhaustion of the system, and health, 
rapidly returns. 
Some narcotics are valuable as astringents. Opium is our 
sheet anchor in superpurgation of the horse, the ox, and the sheep. 
The undue discharge is prolonged by the irritable state of the 
vessels: that irritability is diminished by opium, and the discharge 
is lessened, or ceases. 
The principal action of catechu is on the exhalent vessels of 
the intestines. It follows the rule of many other drugs, whose 
primary influence is chiefly or entirely excited on some particular 
organ or portion of the frame. 
The astringent power of catechu in the horse is not very great, 
although we are disposed to consider it as a valuable addition to 
opium and chalk in the treatment of superpurgation. The 
usual quantity exhibited would be a drachm and a half or two 
drahms, repeated twice or thrice in the day, according to the 
urgency of the case, combined with a drachm or a drachm and 
a half of opium to allay the intestinal irritation, and four drachms 
of chalk to neutralise the acid principle which is uniformly 
evolved in severe purging. 
In the East Indies catechu is exhibited, and, it is said, suc¬ 
cessfully, to tame vicious horses. The dose is two ounces daily. 
The modus operandi is not quite evident, except that not only 
may the passage of fluids through the exhalent vessels be ar¬ 
rested, but also through the lacteals, and, therefore, a sufficient 
quantity of nutriment may not be absorbed. 
Of the effects of catechu in arresting the diarrhoea and even 
the dysentery of cattle, we can speak with more confidence. It 
is given, combined with opium and chalk, in doses of from two 
