(c.) In the fatty- class, the fatty matter is chemically the same as that of ordinary adipose tissue (e. g. in lipoma); or it is more or less closely allied to cholesterin (e. g. in cholesteatoma).
The fatty particles which exist in almost all Growths, even of the albuminous kind, and which do not form the essential part of the mass, are not contained in cells, as in true fatty Growths, but exist in the various forms enumerated in a former passage.
Carbonates, hydrochlorates, and phosphates of the alkalies and earths are the inorganic salts most commonly and largely associated with the animal constituents of growth.
§ 6. The PATHOLOGY of Growths em braces the subjects, first, of the morbid changes arising in, or in immediate connection with, those formations ; and, secondly, of the va rious conditions of the system which precede, accompany, and follow their evolution. Their pathology may, in other words, be regarded as local and general.
(a.) Local.—Under the head of physiology we have considered briefly the various changes arising in Growths, as essential phenomena of their complete development ; and which, however they may be regarded as morbid in respect of the system generally, are, on the part of the adventitious mass in which they take place, evidences of natural progress. But there are numerous changes occasionally occurring in Growths, that are actually morbid in essence in relation to the substance of the new product itself; and others of a sitnilar character which are produced in the sur rounding tissues. These two classes of changes (which can only be glanced at here) constitute the materials of the Local Pathos logy of Growths.
1. The changes observable in the substance of Growths, and which signify a departure from the regular process of evolution, are :— congestion ; infiltration with blood or with serosity; hremorrhage, and in consequence of these states, various forms of discolouiation; inflammation ; mortification ; and the deposi tion within or upon them of some adventitious material foreign to their nature. In fact, the chief morbid changes occurrin_g in the natural structures may wise in these formations.
2. The effects produced by Growths on surrounding tissues are nzechanical and vital.
The mechanical variety comprises detrusion and various other displacements; condensa tion ; discolouration ; infiltration ; blocking up of cavities ; interference with the motion of fluids, &c.
The detrusion produced by Growths may be simple, expansive, or causing peduncula tion, a peculiarity observed when certain Growths, endued with little or no tendency to infiltrate the parts around, originate be tween a mucous or serous surface, and a hard, resisting tissue. And this for obvious reasons; with the progress of their enlargement the distention they induce does not equably affect all surrounding parts (because the re sistance of these is unequal), but acts espe cially upon the least resisting structures. As they enlarge, they- carry these structures be fore them, until themselves eventually pro trude sufficiently from their precise seat of origin to leave a sort of process of the mem brane they push before them, acting as a stalk of attachtnent to the place of their original connection.
A growth thus pedtinculated is practically known as a Polypus, a term extremely injudi cious, as it leads the observer to neglect the important matter of the nature of the tumour, and to regard a mere accident of shape as an essential feature.
The vital effects are rarefaction ; condensa tion; atrophy ; hypertrophy ; inflammation, with its results—adhesion, softening, indura tion, ulceration, mortification, perforation, effusion of blood, enlargement of vessels, &c.; and, most important of' all, infiltration of the surrounding tissues with matter similar to that coinposing the new growth. This last effect occurs (as we believe) in connection with no growth except cancer, and constituting one of the most evident pathological and nosological distinctions between cancerous and other allied formations, will be presently examined.
§ 7. The nature of this work will not admit of any extended observations on the general Pathology of Growths, but some prominent facts can scarcely be passed over in silence.