IN HERBIVOROUS ANIMALS. 
233 
This operation appears to us to offer the double advantage, on 
the one hand, of rendering possible the evulsion of the organ, the 
principal cause of the derangements to be combatted, and on the 
other hand, of giving access into the sinuses which are the depots 
of purulent collections and pathological productions, against which 
it is necessary to act directly and with great energy. 
This latter consideration is of very great importance, since, even 
though we might by the ordinary means obtain the extraction of 
the diseased tooth, it would still be necessary to trephine the si- 
nuses, in order to evacuate the pus which they enclose, and mo- 
dify the state of the membrane which secretes it. 
This operation being very unusual, and the observance of some 
rules requisite for practising it, we will consider it somewhat in 
detail : — 
The carious tooth once recognised, and the impossibility to ex- 
tract it by the mouth well established, either from the state of the 
diseased parts or from the vain attempts with the ordinary instru- 
ments, the animal should be cast upon the side opposed to that 
where the disease exists. The operator then assures himself anew, 
by direct exploration with the hand in the mouth, of the exact 
situation of the carious tooth. 
If, as sometimes happens, the swelling at the corresponding sinus 
is little sensible, it would be well to be guided by a head prepared 
in advance, with the sinuses laid open, in order to find the exact 
place necessary to apply the trephine ; this is always to be directly 
above the diseased root. When the diagnostic is precisely deter- 
mined on this point, a large Y incision, or a crucial one, must be 
made, and the trephining instrument manipulated until the sinus 
is properly laid open. Now, this opening into the sinus must not 
be confined, but, on the contrary, very extensive ; and it is more 
convenient to apply upon the parietes of the sinuses three crowns 
of the trephine tangent reciprocally at their circumferences ; then, 
by the aid of a very sharp cutting instrument and a small ham- 
mer, the angles may be removed from the borders of the opening. 
The sinus being thus laid open, we observe the interior to be 
filled with pultaceous matter, much resembling curds, and of a 
particularly foetid odour ; this matter must then be extracted, and 
the sinuses completely cleaned out with injections, which may 
be composed of a weak solution of chlorinated lime, in order to 
destroy the extreme foetor. 
As soon as the mucous lining membrane of the cavities has 
been laid bare, the transformations which it has suffered may be 
observed, as also the vegetations springing from it. At the bottom 
of the sinus, towards the alveolar border of the maxilla, and in the 
midst of these vegetations, may be recognised a surface, hard. 
