We cannot doubt then that all these vascular elongations serve powerfully to unite the epidermis to the chorion. How is the adhesion formed in their interstices? I know not; but it exists, though it is less evident. The cellular texture, as I have said, appears to take no part in it. Every one knows that many causes destroy the adhesions of the epidermis, and raise it up. These causes are, 1st, every severe inflammation, whatever may be its species. We know that after erysipelas, phlegmon, biles, and cutaneous eruptions of different natures, the epidermis is always detached; there is then no fluid that raises it up. The exhalants cannot furnish it, as they are full of blood; it is dry when detached. 2d. Various cutaneous eruptions, which have not an inflammatory character, as herpes, &c. also detach the epidermis at the place where they are. It most commonly comes off then in the form of dry scales; hence no doubt the idea of some authors who have attributed to it a scaly structure, which neither observation nor experiment upon the epidermis in the natural state have proved. This pealing off in scales is owing to the same cause precisely as the formation of vesicles which take place the instant after the skin has been plunged into boiling water, viz. to the greater adhesion of the exhalant vessels which go to the epidermoid pores. Observe in fact that it is always in the space between these pores that the scales are produced, which do not exist in nature, but which arise only from the manner in which the membrane is raised up. For example, when herpetic eruptions take place on the chin, the pores through which the hairs pass are not detached; it is only the epidermis in the space between these pores; now as these are very near together, these scales are extremely small; they are almost like dust. 3d. Whenever the epidermis is raised up by cutaneous inequalities, the least friction detaches it from these inequalities. Hence why, after strong dry frictions, a rough skin becomes scaly, whilst a smooth one experiences no alteration; it is this even, which in the external appearance, contributes much to the ugliness of the one and the beauty of the other. 4th. After idiopathic fevers, and even many affections of the internal viscera, the skin which has felt the sympathetic influence of the disease, becomes the seat of an alteration which without having any external sign, is sufficient to break the union of it with the epidermis, which is everywhere raised up. 5th. We know that the action of a blister, which draws a large quantity of serum to the external surface of the chorion, breaks off the exhalants which go from it to the epidermis; so that this serum is effused under it and forms a more or less considerable sac. The water does not escape through the open pores, because their oblique course through the epidermis makes their parietes, when brought in contact with each other by the pressure of the water, form an obstacle to it.