REVIEW. 
541 
Nevertheless, so far from its being an impossible act, there 
are, as we have seen, several instances of its occurrence 
on oral and scriptural record, the theory of which extra¬ 
ordinary or unnatural performances it behoves us here to 
deduce from inquiry. In three of the cases out of the seven, 
whereof we have given abstracts, obstruction of the pylorus , 
or of parts in direct communication with it, was demonstra¬ 
tive ; and though in the other four no such obstruction was 
physically demonstrable, yet might we, we think, be justified 
in assuming that such existed either on account of spasm or 
other cause, which proved of but temporary duration, and 
yielded after such duration either spontaneously or to remedy. 
We believe, in the horse as in the human subject, pyloric 
obstruction to be a necessary condition to the production of 
emesis ; and, with Mignon, that “ when this becomes the con¬ 
dition of parts, the act (of vomition) is, for the first time, 
performed through the contraction of the abdominal parietes 
alone, (or in conjunction with the stomach,) favoured by the 
straightened rigidity of the (passage along the) neck.” At 
the same time, we must suppose that pyloric obstruction is 
required to be of greatly more force and persistence in the 
case of the horse than in that of the man, in consequence of 
the natural obstacles to vomiting being so much less sur¬ 
mountable in the one case than in the other, and which must 
be overcome before the act itself can take place. Disease of 
the pylorus, or obstructed small intestine, &c., may give rise 
to the stoppage of the ordinary passage for the aliment, and 
cause it to reascend, in spite of all natural mechanical ob¬ 
stacles, through the oesophagus ; likewise spasm or paralysis, 
it would seem, may have,^ro tempore at least, the same effect. 
Indeed, it is not impossible but that there may occur cases of 
pyloric obstruction, temporary or permanent, in which col¬ 
lections of air may force their way, by expansive force, 
through the cardia, as in Mr. Percivall’s case, giving rise to 
a kind of gulping or eructation, with discharge of air, which 
maybe accompanied with simultaneous ejection of aliment,— 
though it must be acknowledged such instances among 
horses are rare. 
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VOL. XXV. 
