-GROWTHS.
§ 1. Growths possess texture which differs in physical characters from all natural tissues, the arrangement of their septa and loculi being, among other things, distinctive of themselves. They differ, further, from natural structures, in a total deficiency of modelling faculty ; they enlarge in all directions indiffer ently, careless, as it were, of the mechanical mischiefs their presence may inflict. They are composed of evanescent vegetating cells, in capable of propagation by artificial inoculation into the tissues of the individual producing them.
§ 2. The existence of structure in the order Growths is apparent on superficial in spection. And there is one unfitiling charac. teristic of this structure, as displayed to the naked eye; it consists of a stronta and an in terstitial matter occupying its meshes. This, which is the most striking peculiarity on the surface of some tumours (enchondroma, col loid cancer), is much less evident in others (milt-like variety of encephaloid, many spe cimens of simple scirrhus) ; but in these latter it is clearly disclosed by slight maceration. And the want of a clear definition at first of stromal and interstitial parts depends, not on their non-existence, but on the more than ordinary similarity in physical characters of both. Generally speaking, in truth, there is a very obvious difference in this respect : the stroma of fully developed colloid has the aspect of cellulo-fibrous membrane, opaque and close ; its interstitial matter all the out ward appearances of a jelly-like substance; in enchondroma, the interstitial mutter, resem bling jelly of a different tint, is enclosed in a stroma, in many cases formed of laminx of bone. But, on the other hand, in some cases (as those referred to), there is no such obvious difference in the visible character of the two divisions, as they may be called, of the growth. In yet other cases, again, the outward cha racters of the stromal and interstitial parts differ in colour, transparency, density, tenacity, when roughly examined, and yet their intimate constitution is almost identical ; this is the case in fibrous tumours.
In the majority of Growths, the stromal substance encloses spaces inclining to the spherical form, a form most distinct in en chondroma, colloid cancer, and fibrous tu mours ; only imperfectly seen in encephaloid ; almost conipletely absent in simple scirrhus and in erectile grovahs. The manner in which the sphericity of the loculi is produced will be considered further on.
Another element of Growths, which is vi sible to the naked eye, or may be' rendered so by means of injection, is blood-vessel. In varying proportions all Growths possess vessels, which may be limited to their stromal substance, or permeate both stromal and intrastromal substances. These vessels are in part those of the textures invaded, by the new formation, in part adventitious pro ducts.
Lymphatic vessels and nerves are occa sonally found within the area 'of a Growth ; but there is no evidence that they are ever of new formation.
§ 3. The ultimate essential elements of tumours are granules, molecules, cells, free nuclei, and fibrils. With these elements are accidentally associated Precipitates, Deposits, Exudation-Products, and certain of the sim pler Pseudo-Tissues.
(a.) The elementary granule is spherical in shape, flattened or amorphous; averages in size -nthrutli of an inch ; and is seated in the intenor of cells, or on the surface of fibres, or is free. The molecule is too minute for mea surement.
(b.) Some portion of the substance of all Growths consist of hollow vesicular bodies or cells. The quantity of these cells varies extremely in different genera of Growths ; constituting the greater part of the mass of simple sarcoma and of enchondroma, abun dant in colloid cancer, they are comparatively rare in scirrhus, and may be sought for in vain in the main substance of fibrous tumours.