EMETIC TARTAR OM RUMINANTS. 
667 
tartar have, on various occasions, been introduced, by means of 
the artificial passage into the first and second stomachs, but no 
immediate effect has ever been produced : we say immediate, 
because the consecutive effects, very feeble, which have some¬ 
times been observed, depended evidently on the subsequent pas¬ 
sage of this active substance into the fourth stomach. As to 
this fourth stomach, when the emetic tartar has been introduced 
into it, not directly, because we have seen that a mechanical 
lesion has produced effects analogous to those which resulted 
from the injection of the medicine into the veins, but by means 
of an artificial passage made in the nearest stomach (the mani- 
plus), the symptoms already described have uniformly appeared, 
viz. swelling of the belly, grinding of the teeth, and attempts to 
vomit. 
This point having been established, that it is on the fourth 
stomach, and the fourth stomach only, that the emetic acts, it 
is easy to explain why regurgitation is so easy, and vomiting so 
difficult, in these animals. It is because they are different sto¬ 
machs that are acted upon in the production of these pheno¬ 
mena. 
The two first stomachs are concerned in regurgitation, either 
directly or by means of the peculiar apparatus which they con¬ 
tain ; and it is upon neither the one nor the other of them that 
the emetic acts ; but it does act on the fourth stomach, which 
has nothing at all to do with regurgitation. 
When we examine the structure of the two first stomachs, and 
of the demi-canal of the oesophagus, that is to say, of the parts 
which are concerned in regurgitation, we see every thing disposed 
so as to facilitate the return of the food to the mouth : in the 
fourth stomach, on the contrary, every thing is arranged to render 
that return more or less difficult. Beside, that this stomach is 
the last of the whole, and that all kinds of matters rejected 
must traverse the other three, in order to arrive at the mouth : 
there is also at the opening by means of which it communicates 
with the maniplus, a fold more or less developed, and which 
answers, in a certain, degree, the office of a valve, and this op¬ 
poses itself to the rapid escape of the substances before which it 
is placed. Besides, the fourth stomach, pressed by the abdomin¬ 
al muscles and the diaphragm, cannot contract without the 
other stomachs and especially without the contraction of the 
maniplus, and that cannot contract without its upper opening 
becoming firmly closed. Finally, the fourth stomach being the 
softest, the most relaxed, and the least resistent of the four, it 
follows, that the compression of the abdominal muscles and the 
diaphragm will act less efficaciously on this stomach than on the 
others, and particularly than on the two first. 
