#The Healing Sore.#—­If a portion of skin be excised aseptically, and no attempt made to close the wound, the raw surface left is soon covered over with a layer of coagulated blood and lymph.  In the course of a few days this is replaced by the growth of granulations, which are of uniform size, of a pinkish-red colour, and moist with a slight serous exudate containing a few dead leucocytes.  They grow until they reach the level of the surrounding skin, and so fill the gap with a fine velvety mass of granulation tissue.  At the edges, the young epithelium may be seen spreading in over the granulations as a fine bluish-white pellicle, which gradually covers the sore, becoming paler in colour as it thickens, and eventually forming the smooth, non-vascular covering of the cicatrix.  There is no pain, and the surrounding parts are healthy.

This may be used as a type with which to compare the ulcers seen at the bedside, so that we may determine how far, and in what particulars, these differ from the type; and that we may in addition recognise the conditions that have to be counteracted before the characters of the typical healing sore are assumed.

For purposes of contrast we may indicate the characters of an open sore in which bacterial infection with pathogenic bacteria has taken place.  The layer of coagulated blood and lymph becomes liquefied and is thrown off, and instead of granulations being formed, the tissues exposed on the floor of the ulcer are destroyed by the bacterial toxins, with the formation of minute sloughs and a quantity of pus.

The discharge is profuse, thin, acrid, and offensive, and consists of pus, broken-down blood-clot, and sloughs.  The edges are inflamed, irregular, and ragged, showing no sign of growing epithelium—­on the contrary, the sore may be actually increasing in area by the breaking-down of the tissues at its margins.  The surrounding parts are hot, red, swollen, and oedematous; and there is pain and tenderness both in the sore itself and in the parts around.

#Classification of Ulcers.#—­The nomenclature of ulcers is much involved and gives rise to great confusion, chiefly for the reason that no one basis of classification has been adopted.  Thus some ulcers are named according to the causes at work in producing or maintaining them—­for example, the traumatic, the septic, and the varicose ulcer; some from the constitutional element present, as the gouty and the diabetic ulcer; and others according to the condition in which they happen to be when seen by the surgeon, such as the weak, the inflamed, and the callous ulcer.

So long as we retain these names it will be impossible to find a single basis for classification; and yet many of the terms are so descriptive and so generally understood that it is undesirable to abolish them.  We must therefore remain content with a clinical arrangement of ulcers,—­it cannot be called a classification,—­considering any given ulcer from two points of view:  first its cause, and second its present condition.  This method of studying ulcers has the practical advantage that it furnishes us with the main indications for treatment as well as for diagnosis:  the cause must be removed, and the condition so modified as to convert the ulcer into an aseptic healing sore.