WHY THE HORSE RARELY VOMITS. 
129 
easily thrown into numerous folds, appears a provision to 
allow of the rapid and extensive dilatation of the thick mus- 
cular investment ; and that, consequently, supposing the 
stimulus to cardiac dilatation to be conveyed to the muscular 
coat, the very condition which they regard as an obstruction 
would permit the opening of a capacious channel. When 
they pressed the dead stomach, and saw the dead, thick, and 
loose cardiac lining, fold and plug the aperture, they did not 
take into consideration the fact that in the act of vomiting 
in the dog, compression by the abdominal muscle and 
diaphragm is but one of the reflex muscular movements con- 
ducive to the rejection of the contents of the stomach ; 
another is the anti-peristaltic movement of the viscus and 
of the oesophagus, whereby the cardia is opened and the 
stomach’s contents collected near it, so as to be suddenly 
jerked out by the violent extrinsic compression. The obser- 
vations of Wepfer, Haller, Beclard, and Legallois, prove these 
propositions, and it can no longer be matter of question, that 
the nervous impression of emetics is reflected to the stomach, 
oesophagus, and pharynx, no less than to the diaphragm and 
abdominal walls; and that, consequently, any attempt to 
explain inability to vomit, which, like Ercolani’s and Vella’s 
altogether ignores the great indisposition to emetic action, and 
assumes the stomach and oesophagus to be dead and inert, is 
inconsistent with the true solution of the problem. 
We have finally to examine the teaching of M. Colin, as 
propounded in his very elaborate physiological treatise. 
After avowing that “ Bertin was in the truth when he 
regarded the sphincter at the cardiac orifice as the essential 
obstacle to vomiting in the horse,” M. Colin admits that 
my observations as to the insensibility of that animal to 
emetics is full of justice, and that it had not been made by the 
experimentalists who preceded me. But this admission did 
not prevent him reverting, in 1854, to his old explanation 
according to hydraulic laws, which I had combated in 1852. 
The assumption necessary to the application of this theory, 
that the cardiac sphincter is permanently constricted, 
is a gratuitous one ; and moreover, to the stomach and 
oesophagus, as living and active organs, cannot be applied 
the explanation of purely physical phenomena enunciated by 
hydraulic law. Nevertheless, our author believes the doc- 
trine which I contest, so rational, and so perfectly in accord- 
ance with the conditions of the stomach, as not to require 
experimental demonstration ; yet he searched for it, and 
found it. As to the alleged rationality of the doctrine, 
I repeat it is not reasonable to assume, before the fact is 
xxx. 18 
