The originator of the use of that peculiar instrument, the ecraseur (Fig. 7), so valuable an adjunct in the operation of castration, is Mr. H. Bouley, who brought it into use at a date as early as the year 1857. It is not, therefore, an American invention, as has sometimes been claimed. The function of this instrument is to effect the division of living parts without hemorrhage. The original ecraseur of Chassaignac has received many modifications, all of which, however, operate upon the same principle The essential design of all is to produce a general constriction of the blood vessels, by which their internal and middle coats being first divided, may contract within the cavity of the vessel in such a manner as to close their cavity and form a sort of stopper to the artery, while the external cellular covering, the last to undergo division, is so stretched, under the action of the instrument, and so closely adapts itself by its ends, that insufflation through the free ends of the vessels fails to remove the closing arrangement of the two coats first divided. [Illustration: FIG. 8. HOUSE CLAMPS.] _Modus Operandi._--The operation is comparatively a very simple one. The testicle being exposed, as in all the other methods, the chain of the instrument is so placed around the cord that the pressure takes place upon the greater mass of tissue, in order that it may continue the longer; which being done, the lever of the instrument is brought into action, and the constriction caused by the chain slowly kept up until the definite division of the tissue is accomplished. The essential condition of success in the operation, having in view the desired hemostatic effect, is to _act slowly_. According to Prof. Bouley, an interval of several seconds should be suffered to elapse after each rotation of the wheel which moves the chain. If the tissues are divided too rapidly, the section of the artery is apt to be too clean, and a hemorrhage is likely to be the result. This objection, however, though made by one of the highest authorities in veterinary surgery, does not seem to be justified by the results obtained by American operators, most of whom both recommend and practice its execution as rapidly as possible; and according to their own statements, a serious hemorrhage is seldom encountered. The fact that it has been observed in any case, however, confirms the wisdom of the recommendation of Prof. Bouley, and as most of our American _confrères_ prefer the operation with the animal in the standing posture, the reason of their neglect of the prudent and more truly surgical process can be readily appreciated. To avoid the hemorrhage Dr. House invented a clamp which he applied upon the cord previous to the amputation with the ecraseur (Fig. 8). This mode of castration is not very extensively practiced by European practitioners. The reason of this is probably to be looked for in the essential necessity of safety which so protracts its performance. FIRING.