THE MECHANISM OF THE ACT OF VOMITING. 571 
for awhile to be every way likely to be cured! I, perhaps, 
ought to remark, that I might, probably, have saved more animals 
if they had been properly attended to. It is always bad when a 
disease is considered as incurable, for it is then with great difficulty 
that the country people can be induced to pay any attention to, or 
take any care of animals which they consider to be lost. It is 
indispensable to encourage them, and to engage them to attend to 
the animals the moment they are attacked by the disease. 
Journ. de Med. Vet., 1830. 
THE MECHANISM OF THE ACT OF VOMITING. 
By Dr. Marshall Hall. 
Two opinions have divided physiologists respecting the me- 
chanism of the act of vomiting. It was originally and long 
thought that this act consisted simply in a sudden and forcible 
contraction of the stomach itself. Afterwards Bayle and Chirac, 
and, more recently, M. Magendie, considered that the stomach is 
inactive, and evacuated by being subjected to pressure by simul- 
taneous contraction of the diaphragm and abdominal muscles. It 
appears to me that neither of these opinions is correct. M. 
Magendie distinctly proves, by actual observation, and by the 
substitution of a bladder in the place of the stomach, that the con- 
traction of this organ is not usually subservient or necessary to the 
act of vomiting. I refer to the interesting paper (Paris, 1813) of 
that eminent physiologist for the more full elucidation of this first 
question. I proceed to state such observations as appear to me to 
controvert the second, and to establish that view of this subject 
which I have myself been led to adopt. It is obvious that, if 
vomiting were effected by a contraction of the diaphragm, it must 
be attended by inspiration. If this were the case, the fluids 
ejected from the stomach would be drawn into the larynx and 
induce great irritation, events which have not been observed. 
These events are, indeed, effectually prevented by an accurate 
closure of the larynx, a fact observed in an actual experiment by 
M. Magendie, who makes the following observation : — “ Dans le 
vomissement, au moment au les matiers vomies traversent le 
pharynx, la glotte se ferme tres-exactement.” It is astonishing 
that this observation did not lead its acute author to see that, 
under such circumstances, a contraction of the diaphragm, unless 
the thorax followed precisely pari passu, was impossible. Com- 
plete vomiting has been observed, too, in cases in which the 
