460 
W. L. WILLIAMS. 
the canula. If the patient is lying- down the intestines are 
quite probably displaced somewhat, but most likely the most 
distended intestine occupies the highest point of the abdom¬ 
inal cavity, whether that be the middle or lower region of the 
flank, right or left side. 
There has been an endless variety of trocars invented, the 
simplest being distinctly the best. The caliber of the trocar 
usually kept lor sale is too great, being one-eighth inch in di¬ 
ameter or more, while three thirty-seconds of an inch is ample 
and adds to safety by decreasing the area of the wound about 
one-half. This reduction in size necessitates the use of the 
. best of steel, well tempered so it will not bend. The point 
of the trocar should be far more tapering, the sharp part be¬ 
ing two to three times as long as in those generally offered, 
and delicately sharpened so that its use occasions an incised 
and not a punctured wound. The canula should fit the tro¬ 
car closely and perfectly, leaving no space between them, and 
the end of the canula should be well rounded and smooth so 
that no foreign matter can be lodged between the end of it 
and the trocar and carried into the tissues, or the peritoneum 
or intestine caught and pushed along before the canula. The 
trocar should be fastened immovably in the handle. Revers¬ 
ible trocars cannot be kept in order, their points always be¬ 
ing dulled by contact with the handle when reversed. 
If the instrument is to be carried in the pocket it should 
be supplied with an appropriate case. A very serious defect 
in the construction of most reversible instruments is the mak¬ 
ing of the trocar too short for the canula, so that when used 
the set-screw fails to hold it in place, allowing it to push 
back into the handle so far that the point is partly hidden 
within the canula, allowing the end of the latter to tear and 
abrade the tissues, marring or wholly preventing a successful 
operation. The minimum net length of canula should be six 
inches and even this will be found short for very fat, heavy 
draft horses. If too short the gut slips off the end very 
readily either from peristaltic movement or collapse of the 
engaged portion. Besides, it may be necessary to pass 
through one intestine and enter another part. Before using, 
