2. The tissues adjacent to innocent growths are not further altered than in consequence of the pressure and the inflammation which the growth excites; neither is there any evidence that such growths prop& gate themselves from one part to another. 3. Innocent growths have no natural tendency to ulcerate or slough ; those changes happen to them only in the same manner and under the same circumstances as to the natural tissues of the body. Moreover, in ulcerating or sloughing they have no more tendency than the natural tissues in similar con. ditions have to involve the adjacent parts in their destruction. 4. The tissue of an Innocent growth is in general similar to that of some natural and fully-developed tissue of the body.
The class of innocent growths includes most of those to which the name of Sarcoma is now commonly given. Their appearances are se carious, that the most practised morbid anatomists frequently meet with ltampleis which they cannot certainly refer to any described variety : Tet there are some well-characterised forms, within the descriptions of which may be included a great majority of those which occur iu the iuman body; and these we shall describe under the names of the Fatty Tumour, or Growth; the Cellular ; the Fibrous, or Tendinous; be Cartilaginous ; the Osseous; the Fibro-autilagiuoue.
The Fatty or Adipose Tumour, to which the name of Lipoma >ften given, is the most common of all the tumours occurring in the auman body, and, happily, the most innocent, and the most usually :capable of remedy by extirpation. Its general seat is in the sub lutaneous cellular adipose tissue ; but in rare cases it is situated more ieeply, and then has a more compact structure and more intimate mnnection with the surrounding parts. It usually occurs singly ; but sometimes twenty or more of various small sizes are seen iu the same person. Its elementary tissue is exactly like that of the fat in which it lies, but from which it is separated by a layer of compact cellular tissue, and is generally distinguished by the smallness and distinctness of the lobes composing it. Its blood-vessels are few and of small size, and usually enter it at its base, where it is more closely than elsewhere :onnected with the adjacent tissues. It is insensible, and commonly grows very slowly, without producing pain, or any other inconvenience than is due to its weight or its pressure on adjacent parts. When left to itself, the adipose tumour may grow to an enormous size. Mr. Copeland removed one weighing 22 lbs. ; Sir Astley Cooper, one of 37 lbs. 10 ozs.; and M. Dagorn of Morlaix, one which weighed 46 French pounds. The size of the wound necessarily made in the removal of tumours of such magnitude renders the operation some what dangerous ; but, except for this circumstance, the extirpation of fatty tumours may usually be undertaken with full confidence of success. If not removed, they are apt, through the distension and
thinning of the skin over them, to give rise to ulceration and other more painful affections.
The Cellular Tumour, which derives its name from the similarity of its tissue to that of the common cellular tissue of the body, is a very rare disease. It is composed of a compact substance, infiltrated by a serous or half-gelatinous fluid, and may attain a great size. Mr. Lawrence, in hie ' Lectures on Surgery,' has described the best example yet known of it : perhaps also the disease which Mr. Abernethy, in his ' Classifi cation of Tumours,' named Common or Vascular Sarcoma, was of this kind. But altogether very little is known of this form of tumour: the great enlargements of the skin of the scrotum, supposed by some to be of the same nature, are widely different from it.
The Fibrous or Tendinous Tumour (the fleshy tubercle of Dr. Baillie) is a very frequent and well-marked growth. Its ordinary, perhaps its only, seat is in the walls or in the neighbourhood of the uterus. Its natural form is almost exactly globular; but when it hangs in a dependent position it generally becomes pyriform. Its tissue has the same microscopic character as that of the natural fibrous and tendinous tissues, and is equally little vascular. Its section pre sents a very compact and firm semi-transparent basis, intersected by numerous shining, tough, fibrous fasciculi, arranged sometimes in rays proceeding from its centre, but more frequently in irregularly arched and undulating lines. It grows slowly, and at first without paiu ; but when it has attained some size it usually excites painful and dangerous affections of the uterus ; and this is especially the case when the tumour projects into the cavity of that organ. One such tumour may grow alone in the uterus ; but more commonly two or more grow together, and sometimes there are from ten to twenty. They may increase so as to form masses nearly a foot in diameter, and in this case they usually end fatally by their pressure on important organs, or by haemorrhage when they project externally. In advanced stages of their growth, or at any time if they cease to increase in size, they are apt to be calcified; earthy matter being deposited around or within them, so as to form a shell or a coral-like mass of hard substance, which bears some resemblance to ivory, but has none of ite micro. scopie characters.