2 - We are acquainted with the dysenteric process as a substantive disease of the mucous membrane of the colon, and inasmuch as it is here presented in its most exquisite form, its habitat has been correctly fixed ever since the days of Hippocrates.

The dysenteric process is divisible into four natural degrees or forms.

In the lowest degree, the mucous membrane commonly presents a layer of a thin secretion, of a dirty gray and reddish color, underneath which, certain parts, commonly the projecting folds of the mucous membrane, are reddened and swollen. In this manner striae are produced, which more or less encircle the intestine. The epithelium is either raised in the shape of small vesicles which contain clear serum, or it forms a grayish-white layer, resembling the mealy scurf of the epidermis, an appearance which probably induced Linnaeus to term dysentery Scabies intesti-norum interna. The subjacent mucous membrane seems excoriated, slight pressure induces hemorrhage, and it may be easily detached in the shape of a light red sanguineous pulp; its submucous cellular tissue appears infiltrated.

1 We must leave a further development of this doctrine to oral instruction. Dr. Mohr, in his Contributions to Pathological Anatomy (Stuttgart, 1838, p. 131), quotes, in connection with this subject, an authority which is quite foreign to the matter.

2 Vide Oestr. Jahrb. xx. I.

The anatomical characters may be summed up as - swelling, injection and reddening, softening (red and bleeding), serous exudation in the shape of a delicate vesicular eruption and consequent branny desquamation of the epidermis.

In the second degree, the textural alterations are not limited in the manner described, but extend over a larger surface, still, however, presenting a greater development at one part than at another. The mucous membrane is invested to the same extent, by a dirty-gray layer, consisting of desquamated epithelium and a thick glutinous exudation; or this may already have been removed, and the subjacent mucous membrane, in either case, appears converted into a soft, sanguineous, pale-red and yellowish gelatinous substance, which may be easily detached. The internal surface of the intestine commonly presents more or less numerous protuberances, which closer examination proves to consist of a very copious infiltration of the submucous cellular tissue: these projections or tumors were first observed by Hewson and Pringle; other authors speak of them as warty tubercular swellings, or fungoid excrescences, and M. Gely has lately termed them Hypertrophie mamelonnee du tissue sous-muqueux.

They correspond to those points of the mucous membrane at which the morbid affection is most developed; with the exception of slight redness and intumescence, especially in the circumference of the follicles, an increase in the mucous secretion, and a slight desquamation of epithelium, the intervening parts of the mucous membrane do not generally offer any marked textural changes. The entire portion of intestine is generally in a state of passive dilatation; it is distended with gas and with a dirty brown fluid, which consists of the most different materials, such as intestinal secretions, epithelium, lymph, blood, and faeces; its coats are thickened, and the submucous tissue particularly is in a state of tumefaction.

At this stage we meet with the laminated and tubular coagula in the evacuations, described by ancient and modern authors, especially if the exudation be of a more plastic character.

Occasionally the affection of the follicles predominates and is accompanied by irritation, exhausting secretions, and softening: these probably constitute the characteristic signs of the so-called catarrhal or white dysentery, but which, in an anatomical point of view, is the same follicular affection of the colon as that which we have already described as accompanying chronic diarrhoea.

In the third stage, we find the protuberances more closely set, so as to produce an uneven, lobulated appearance. The mucous membrane that invests these protuberances partly retains the above-described conformation; in part it is converted into a slough, which is here and there blended with the desquamated epithelium and the exudation, and is firmly attached to them; it is of a dark-red or blackish-brown, sugillated, or grayish-green color; or the mucous membrane may have disappeared, so as to expose the infiltrated submucous cellular tissue, to which the remnants of the mucous membrane remain attached in the shape of solitary, dark-red, flaccid, and bleeding vascular tufts, or as dilated follicles, which are easily removed. The interstices of the mucous membrane are the seat of the affection in a lower degree.

The protuberances occasionally are found to have coalesced, and the intestine then presents an uneven plicated surface, accompanied by an equable degree of infiltration and thickening of its parietes; the mucous membrane is uniformly affected over a large extent, and there are no free interstices.

The contents of the intestine are of a dirty-brown or reddish, ichorous, fetid, flocculent and grumous character.

In the fourth and highest degree, the mucous membrane degenerates into a black, friable, carbonified mass, which may often be subsequently voided in the shape of tubular lamime (so-called mortification of the mucous membrane). The submucous cellular tissue appears to be previously infiltrated with carbonified blood, or a sero-sanguinolent fluid; or it is pallid, and the blood contained in its vessels is converted into a black, solid or pulverulent mass: subsequently it shows purulent infiltration, in consequence of the reactive inflammation which is induced in the lower healthy strata, for the purpose of eliminating the gangrenous portions.

The affected portion of intestine, which contains a putrid, brownish-black fluid, resembling coffee-grounds, may appear in a state of passive dilatation, as above described, but it is much more frequently collapsed; and if the two highest degrees continue for any length of time, the muscular coat will be reduced. The tissue of the latter is condensed, pale, ashy, peculiarly elastic and friable, and analogous to the yellow fibrous tissue.