394 
REVIEW. 
stomach, we need only remark, that since both these conditions 
are susceptible of alteration by the muscular activity of those 
organs, no arguments, based upon the assumption of their being 
invariable, can be accepted as conclusive. To the position of 
the stomach (near the spine, and separated from the floor of the 
abdomen by the enormous large intestines), even I, at one time, 
attributed a great part of the horse’s difficulty to vomit. It 
occurred to me, however, that the act of parturition in the mare 
is one of great rapidity; that abdominal respiration during dis¬ 
ease or severe exercise is, in the horse, very easily effected; in 
the performance of these functions, and in the voidance of urine 
and faeces, the abdominal muscles take a very active part; and 
yet the uterus, bladder, and rectum are as disadvantageously 
placed, with reference to the floor of the abdomen, as is the 
stomach; the fact is, that the abdomen being completely full, 
pressure is transmitted very effectively from its muscular walls 
to the contained organs. 
Different as are the opinions we have hitherto commented 
upon, they yet present one remarkable point of analogy, inas¬ 
much as all their authors attributed the horse’s difficulty to 
vomit to a mechanical obstacle. It affords me pleasure grate¬ 
fully to acknowledge, that for not falling into the same error I 
am indebted to Dr. Sharpey, who gave me an all-important hint 
by suggesting an inquiry into the action of emetics on the horse. 
It at once occurred to me, that as the mechanical part of the act 
of vomiting is excited by a reflex stimulus from the nervous 
centre, it behoved those who undertook to demonstrate why the 
horse rarely vomits, to study two classes of phenomena —the 
nervous and the mechanical :—for it is quite obvious that if the 
stimulus to the expulsive effort be wanting, it is useless to attri¬ 
bute the impossibility of the evacuation of the stomach by the 
esophagus to mechanical obstacles, for they have no oppor¬ 
tunity of coming into operation. Moreover, since I have 
excluded the existence of any mechanical impediments to 
vomiting in the horse, it is evident that the question which 
forms the subject of my inquiry can alone be solved by deter¬ 
mining what is the action of emetics on the nervous system of 
the horse. 
It is since I received and worked upon Dr. Sharpey’s hint, 
that I have carefully studied M. Mignon’s report, and have 
found that it occurred to him and his collaborators, that the 
efforts of those who had studied the subject as pure mechanists 
could but prove abortive. “ Is not the stomach of the horse 
that vomits,” asks the reporter, “ in conditions which no expe¬ 
riment would reproduce? And do you give no consideration to 
the nervous element, which you forget to regard as one of the 
