This metamorphosis sometimes attacks the entire patch, sometimes it only affects single portions or separate folliculi; in the latter case the remainder of the patch passes through a retrograde metamorphosis; absorption causes it to collapse, and a lax, succulent, plicated tumefaction of the glandular plexus remains. Accordingly, the above-mentioned slough is in the former instance embraced by the mucous membrane, which invests the marginal surface of the typhous patch; in the latter, by the retrograde 1 portion (retrograder antheil) of the glandular plexus.

A similar metamorphosis takes place in the tumefaction of the solitary glands, though it appears to commence later, and to advance less rapidly; the sloughs are small and rounded, and seem generally to undergo the retrograde process.

This metamorphosis commences in the neighborhood of the caecal valve, and is commonly in advance of that which takes place at the upper part of the ileum.

The intestine is more or less distended with gas (meteorismus); it also contains yellow or brownish muco-gelatinous or biliary matters, mixed up with grumous, furred particles; it always occupies a low position in the hypogastrium, and even sinks into the pelvic cavity. The caecum is very often found to contain the trichocephalus dispar in larger or smaller numbers.

The mesenteric glands, which almost invariably pass through the stages of the metamorphosis with less rapidity than the typhous products in the intestine, now attain their largest bulk; they reach the size of pigeons' eggs, and, in the vicinity of the caecal valve, even of hens' eggs, and form a tuberculated chain which extends in a slanting direction from the terminal portion of the ileum to the lumbar plexus. Their color is blue or bluish-red; they are much congested, and the vessels, spread out in the cellular capsule of the gland, present a vascular network which is perceptible through the mesenteric laminae. Their sub-•stance is firm, but they are soon converted into a grayish-red, lax, medullary matter, in which we frequently discover extensive extravasations of blood; they then become soft and elastic, or even present distinct fluctuation.

1 [The terms "retrograde" and "retrogression" are intended to designate the return of a diseased part to its normal condition by absorption of the deposit, or otherwise. They have been adopted from the absence of any terms which exactly convey the author's meaning. -Ed].

Fourth Stage

After the morbid product has been detached, a cavity remains on the internal surface of the intestine, which represents the true typhous ulcer.

If the entire morbid growth is removed at once, that portion of the intestinal mucous membrane which invested the marginal surface of the heterologous product sinks down upon the ulcer, and thus forms a mucous fringe, which varies in width and extent according to the previous elevation (thickness) of the morbid growth; and from being at first dark-red, subsequently assumes a blackish-blue or slate-gray color. If the morbid growth has only been partially detached, the remaining portion of the patch becoming retrograde, we find the smaller ulcerated surface equally surrounded by a margin of glandular tissue.

In the former case the base of the ulcer corresponds in form and size to the previous infiltration (plaque); varying in size, it is either round or, more frequently, elliptic; the latter shape prevails at the terminal portion of the ileum, and the long diameter of the ulcer corresponds with the longitudinal axis of the intestine. In the second case the ulcer is, at all events, smaller than the entire Peyerian gland, its shape irregular, the margin sinuous or round. Several ulcers are often grouped together. For the typhous infiltration of a solitary follicle a circular or slightly oval ulcer is substituted.

The deep submucous cellular layer, which invests the muscular coat, forms the base of the ulcer.

The mesenteric glands decrease in size, as soon as the detachment of the intestinal morbid growth has commenced, in proportion as the grayish-red medullary substance, with which they are infiltrated, is removed, though they still continue larger than they are in the healthy condition; in consequence of the enduring congestion and enlargement of the vessels they present a reddish-blue tinge.

The typhous ulcer consequently presents the following characters:

Firstly

Its form is elliptical when it corresponds to the infiltration and detachment of a larger patch of Peyer's glands; it is round when it corresponds to a solitary follicle or a rounded patch, or to the partial detachment of a glandular plexus; and, lastly, it may also be irregular or sinuous when corresponding to a partial detachment.

Secondly

The size or circumference of the ulcer varies, from that of a hemp-seed or a pea to that of half-a-crown.

Thirdly

The position is peculiar in reference to those of an elliptical shape; they are placed opposite to the insertion of the mesentery, and their long diameter is always parallel to the longitudinal axis of the intestine; the typhous ulcer never forms a zone; at least, we have only once seen this occur in many hundred cases.

Fourthly

The margin of the ulcer is invariably formed by a well-defined fringe of mucous membrane, which is a line or more wide, detached, freely movable, of a bluish-red, and subsequently of a slaty or blackish-blue color.

Fifthly

The base of the ulcer is formed by a delicate layer of submucous tissue which covers the muscular coat; like the marginal substance, it is quite void of morbid growth.

Sixthly

The small intestine is the seat of the ulcerative process, and the lower third is most liable to be involved - the number and size of the ulcers increase as they advance towards the caecal valve.

The cure of the typhous ulcer to be complete, requires several local and general conditions, of which the chief are the termination of the local process, and the complete extinction of the typhous dyscrasia. When such favorable circumstances occur, the cure is effected in the following manner: