WHY THE HORSE RARELY VOMITS. 131 
very violent compression only sufficed partially to evacuate 
the stomach through the pylorus, even when the contents 
were fluid, might have suggested to M. Colin that it was 
precisely as logical to say that the most forcible pressure did 
not suffice thoroughly to evacuate the fluid contents of a 
living horse’s stomach through the duodenum, as it was 
to say that such pressure altogether failed to press the con- 
tents of it through the cardia. M. Colin was arguing on the 
functional activity of a healthy stomach and its orifices, after 
having exposed and handled that viscus in such a manner as 
certainly to impair, possibly utterly to neutralize the opera- 
tion of that function. The normal peristaltic movement of 
the stomach, under the healthy stimulus, suffices thoroughly 
to empty the contents of the horse’s stomach into the gut ; and 
absolute and comparative observation discloses no condition 
in the structure of the stomach which can oppose reverted 
evacuation of its contents through the cardia, provided the 
abnormal stimulus come into operation, which in other ani- 
mals is known to excite anti-peristaltic movement of the 
stomach and oesophagus, and aperture of the intermediate 
passage, in addition to violent efforts of the diaphragm and 
abdominal muscles. 
Our author performed many other experiments, with a 
view to defend the position he had taken ; but they are, for 
the purpose required, amenable to the same criticism as, 
with much deference, I have ventured to pronounce on the 
preceding ; and when M. Colin states, if he be not deceived , 
those experiments demonstrate that the obstable to vomiting 
in solipedes resides in the cardiac sphincter, I believe he was 
deceived in the reality of his demonstration. 
But exclusive as M. Colin represents himself in devising, 
indicating, and arguing on the experiments above referred 
to, he is essentially eclective when exercising the functions 
of a didactic writer; and accordingly we find him sum up by 
teaching, that the constriction of the cardiac sphincter, and 
of the thick muscular lower end of the oesophages are the 
chief impediments to vomiting in the horse ; but that we 
must regard as auxiliary impediments, the smallness of the 
stomach, its distance from the abdominal wall, its not being 
subject to great distension under ordinary circumstances, the 
short period during which alimentary matters remain in it, 
and finally, the slight degree in w hich the viscus is suscep- 
tible to the exciting causes of vomition ; in exposition of the 
last statement, M. Colin grants that the introduction of tartar 
emetic into the digestive organs neither provokes efforts to 
vomit, nor nausea ; that those phenomena are but rarely and 
