The other imperforations to which allusion has been made, are dissimilar to those of the eyelids. Imperforation of canals opening upon the surface of the body is a case in which, al most always, there has been an arrest of de velopment ; all the canals which in the adult are lined by a mucous membrane, continuous with the skin at their orifice, are naturally, at a certain epoch of embryo life, imperforate. These organic states, which nosologists have so . often considered as diseases, are, therefore, simply primitive conditions preserved by ano maly, and become permanent instead of tran sient.* It may, therefore, be inferred that the greater number of cases adduced as evidence of adhesion in intrauterine life are not in point, and if they were it may still be asserted, and the assertion be borne out by analogy, that they had not occurred in the absence of inflammation.
John Hunter seems to have had the idea that adhesion may occur in the absence of inflam mation in certain cases, namely, in those where blood has been effused, that this blood may become organized and form a bond of union. Ile says, " It does not seem necessary that both surfaces, which are to be united, should be in a state of inflammation for the purpose of effecting an union ; it appears only necessary that one should be in such a state, which is to furnish the materials, viz. to throw out the coagulating lymph, and the opposite unin flamed surface accepts simply of the union ; nor is it even necessary that either surface should be in a state of inflammation to admit of union : we often find adhesions of parts which can hardly be called inflamed."t I believe that no solution of continuity can be obliterated in the absence of inflammation, the injury which has occasioned the solution of continuity, and the effusion of blood, being sufficient to excite inflammation. The only circumstance under which it seems to me to be possible that union could be produced in the absence of inflammation, is one which can only rarely occur ; and even then, although the possibility of the occurrence can hardly be denied, its reality may be reasonably ques tioned. If a portion of blood, for instance, be effused into a serous cavity, its colouring matter is, after a time, removed, and a fibrino albuminous coagulum remains. This coagulum coming in contact with a previously uninflamed serous membrane, may become united to this membrane : and it is believed by some pa thologists that this union occurs without the supervention of inflammation. Another si tuation where it is believed by certain patho logists that union is produced by similar means, is in a portion of artery included be tween two ligatures, the blood which has been included between the two points undergoing a similar change to that which I have already described, and adhesion of the clot to the in ternal tunic of the artery being effected in the absence of inflammation.
Such cases may carry conviction to the mind of a superficial observer, but a more careful in vestigation will lead to an opposite conclusion. My own observations induce me to think, that of all the causes by which adhesive inflam mation of serous membranes may be produced, the most remarkable perhaps is an extravasatiori of blood into their cavities, which appears to excite just the precise quantity of inflammation necessary for the production of adhesion. If we examine the point at which such coagula are maintained in contact with serous mem branes, before perfect union is established, we shall find between the coagulum and the mem branes a stratum of exhaled matter, the exist ence of which would lead to the conclusion that the clot has excited in the membrane as much inflammation as is necessary for the pro duction of such exhalation.
In solutions of continuity where blood has been effused between the edges, it was main tained by John Hunter* that this blood was the provisional bond of union ; this, I appre hend, is not the case. Whether protected from the atmospheric air, which appears to exercise a very decided influence in decomposing it, as in some fractures, or directly exposed to it, as in ordinary solutions of continuity, this coagu lum never, during the early periods, adheres with sufficient firmness to attach to each other the borders of a wound If, however, any por tion of the coagulum remain after a fibrino albuminous exhalation has been formed upon the divided surfaces, it may become in this way organised, and permanently adherent.
After the preceding remarks, it will therefore be held in this article that whenever an adhe sion has been effected between two surfaces, naturally or artificially separated, that that adhesion must have taken place through the in tervention of inflammation ; that inflammation arrived at a certain height will be accompanied by a fibrino-albuminous exhalation ;—that if the inflammation be carried beyond that point, a purulent secretion may be established, and when this is developed, union, by what is termed the first intention, cannot occur ; granu lations are then developed, and union by what is termed the second intention, may follow. The process by which each kind of union is effected I shall now proceed to describe in de tail.