INTRO-SUSCEPTION IN A HORSE. 453 
All practitioners — MM. Bouley, jun., Dufour, Renault, 
Debeaux, &c. — agree that the symptom first observed is intes- 
tinal pain, manifesting itself in cholics, at times slight, at times 
violent, sometimes intermittent, and always assuming an alarm- 
ing character previous to the termination, too often a grievous 
one, of cases of intus-susception. 
Taking, then, cholic as the symptom, and congestion as the 
morbid lesion, as unequivocally present in intus-susception, a 
question presents itself to our notice, which is — is the congestion 
of the parietes of the intestine a forerunner of the intus-suscep- 
tion, or is it the exclusive consequence of it 1 
To us, the first of these opinions appears, looking at it in all 
its bearings, more admissible than the second. In our eyes, 
effusion is both a cause and an effect of invagination : in other 
words, we are of opinion that congestion precedes invagination, 
and that the latter, once produced, determines, in opposing an 
obstacle to the circulation, a sanguineous stasis over and above 
the primitive congestion. 
These considerations being premised, the production of intus- 
susception seems to us to admit of satisfactory explanation. 
Let us admit for a moment, in order to render our ideas the 
more intelligible, that some part of the small intestine becomes 
the seat of active or passive congestion. From this moment its 
coats begin to thicken and its caliber to visibly contract. The 
alimentary matters, in their passage through the open canal, 
will experience, when they come to arrive at this part, an ob- 
stacle more or less difficult to overcome ; their course, conse- 
quently, will be, if not arrested, at least retarded. But, the 
peristaltic motion continuing without intermission, is there not 
room for strong presumption that this congested portion, pushed 
on by a vis a tergo, will force its way into the successive portion 
of gut, frequently in a state of dilatation from the presence of 
gas 1 
Once invagination of the small within the large intestines, as 
the caecum, effected, we may add to the cause already in exist- 
ence that of the weight of the congested gut, suspended as it is 
within the caecal cavity. 
In fact, the contraction of the intestine at any given part tinder 
the influence, ordinarily, of cold water or sanguineous conges- 
tion ; the dilatation, or even the conservation of the normal 
caliber of the part, which is constantly in peristaltic motion ; 
lastly, the operation of weight from the moment invagination 
has taken place into the caecum ; — such are the conditions under 
the influence of which intestinal intus-susceptions become fre- 
quently produced. 
Etiology. — The question of the etiology of the intus-suscep- 
VOL. XXIV. 3 Q 
