124 FURTHER INQUIRY INTO 1HE REASONS 
going paragraph. Furthermore, he regarded the position of 
the stomach near the spine, and separated from the floor of 
the abdomen by the intestines, as an obstacle to its being 
sufficiently compressed to reject its contents. But even this 
objection is frail; the act of parturition in the mare is one 
of great rapidity ; abdominal respiration during disease 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 relatively as disadvan- 
tageously placed as the stomach with reference to the floor 
of the abdomen ; the fact is, that the abdomen being com- 
pletely full, pressure is transmitted very effectively from its 
muscular walls to the contained organs. 
Having thus examined and disproved the existence of 
the anatomical conditions which were said mechanically to 
impede regurgitant evacuation of the horse’s stomach, I sub- 
mitted 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 attribute 
the impossibility of the evacuation of the stomach by the 
oesophagus to mechanical obstacles, for they have no oppor- 
tunity of coming into operation. Accordingly, I directed 
my inquiries to the question, What is the action of emetics 
in the horse? and after noting the fact that in general prac- 
tice they are never employed, because of the general impres- 
sion that they are wholly inoperative, I proceeded to analyse 
the experiments instituted for the purpose of determining 
the effect of injecting tartar emetic into the horse’s veins by 
Dupuy, Renault, Leblanc, and Mignon. The conclusion to 
wffiich this inquiry led me, was thus expressed: (( there is 
strong ground for the belief that the horse is unsusceptible 
of the specific action of emetics, even when directly injected 
into the circulatory system.” In order to settle the question 
I determined to appeal to experiment, and injected into the 
jugular veins of a horse and mule of sound constitution, 
various watery solutions containing from five to fifty grains 
of the potassio-tartrate of antimony, but without ever wit- 
nessing efforts to vomit; wffiereupon I thus concluded the 
memoir: “I feel myself justified in stating that all the 
attempts hitherto made to excite efforts to vomit in the 
horse by emetics have t failed. This unsusceptibility to emetic 
action, and the very rare manifestation of the phenomena 
