As the new cuticle covers the granulations, then, these two striking changes immediately take place in their state; the secretion of pus is stopped, the surface becoming dry, and that process of shrinking or contraction begins which we shall find to continue for a conside rable period after the whole sore is apparently healed. The contractile action takes place in every direction, producing that depression of the cicatrix which is observed to follow the spreading of the cutic!e over the granulations. Thus those parts which were soft and spongy now acquire firmness, and form a condensed layer, which occupies the position, and per forms some of the _functions of the original cutis which had been destroyed.
It is an interesting question, why the cuticle in covering an ulcer, though evidently formed from the granulations, is arising not over the whole surface of the ulcer at once, as it is when abraded from the healthy skin, but creeps from the circumference towards the centre, in a slow, progressive manner ? It seems that a greater perfection of org,anization is necessary for the production of cuticle than for the for mation of granulations capable of secreting pus. If we examine the vascular structure of these newly formed parts, we find that the bloodvessels apparent on the granulations are few and very irregular in their course, and often in figure also, having an appearance re sembling a varicose or unequally dilated state; this we take to be an indication of a feeble and incomplete state of organization. On the contrary, the vessels in the immediate vicinity of the new skin,- are more regular in form and direction, and may often be seen running on wards through the neighbouring granulations towards the centre of the sore, having a good deal the appearance of the vessels of the in flamed cornea; and where this is not remark ably apparent, the granulations in the imme diate neighbourhood of the parts in which the skinning process is going on are more vascular than the internal ones. Our observations vvould lead us to believe that this more perfect system of circulation commences by an anasto mosis newly set up from the vessels of the edge of the healthy skin first, and by the action of these newly formed vessels the cuticle is secreted. From these, others are still sent on over the surface of the sore, or immediately under it, and thus by progressive steps the necessary degree of perfection of structure is acquired, and is immediately followed in its progress by the development of the cuticle.
This, be it remembered, is still a different state of the granulations from the contracted un secreting layer which constitutes the new cho rion. If this description of the process is consistent with Nature, it is reasonable to sup pose that the new vessels shooting from the edges of the healthy skin would be more per fect, and more equal to the task required than those which would pass through the granu lations from the subjacent cellular tissue; and in the same way we may suppose that one part being. in the before-mentioned manner com pleted, is better fitted to send on new vessels for the organization of the next portion of granulations than the granulations themselves. It is moreover to be expected that the power of organizing its neighbouring parts must be superior in the healthy skin to that of any newly formed structure, and that this power will in an extensive sore gradually diminish as the distance from the healthy parts in creases ; and this accords with the well-known fact that the cicatrization goes on much more slowly in the latter stages of healing than at the commencement Thus the external process of skinning is completed, but the internal changes are not yet finished. A slow but remarkable change is going on for a considerable time longer, by which the appearance and structure of the cicatrix becomes modified. From a red colour it becomes gradually paler, till it is almost white; this at least is the general rule, though under circumstances, to be presently mentioned, the result is different. The cicatrix also conti nues to contract in all its dimensions, thus not only diminishing in extent, but sinking below the level of the surrounding skin, and becoming more dense and thin and more perfect in its organization, till it has assumed the appearance and character which it will retain through the rest of life.
It is this power of contraction resident in the new chorion of the cicatrix, that produces those bridles which are such frequent causes of deformity after the healing of extensive burns. In these cases there does not seem any neces sity to have recourse to any peculiarity of hypothesis in explaining the great degree of shrinking that so commonly occurs. On the contrary, we conceive that the phenomena at tending the healing up of burns are to be ac counted for by means of the usually recognized causes of the shrinking in the cicatrices of wounds in general.