The decay of Growths is preceded by soften ing of their substance; this softening, indeed, by its increase actually constitutes their de cay. The change is effected by infiltration of serosity, interstitial hmmorrhage, by satura tion with inflammation-products and by gan grene, either of inflammatory or simply mechanical origin. Or, there is an important class of cases, in which the softening of Growths seems analagous to that undergone by stagnating fibrin, and probably depends on chemical decomposition.
The renzoval of Growths (fibrous, cancerous, and others,) is sometimes effected by a spon taneous process, commonly comprising at tenuation and rupture, or ulceration of the investing natural tissues, and gradual liquefac tion of the morbid matter, which is poured through the opening ; or, in less common cases, consisting of sphacelus, whereby the mass, in whole or in part, is separated from its connections.
Cicatrisation of the ulcerated surfaces of Growths is occasionally witnessed. We have ourselves seen this change occur on the proper surface of formations possessing all the cha racters of scirrhus.
Growths of all descriptions are liable, when removed spontaneously or by art, to be repro duced in the spot they previously occupied, if the removal have not been absolutely com plete. The particles left behind act as at tractive forces for new blastema convertible into cells, similar to those of which themselves are composed. This mode of reproduction (as it is erroneously called, for it is nothing more than enlargement, facilitated by removal of pressure of pre-existing substance) occurs with Growths of all kinds, cancerous, sarcoma tous, fibrous, fatty, enchondromatous, erect ile, &c. But it would appear that in some cases of surgical removal, when the whole mass has, as is presumed, been extirpated, a new growth vegetates in it,s place. The dif ference of the cases is often rather apparent than real : we have distinctly found the ger mina of cancer in tissue, reputed healthy, surrounding a cancerous mass ; and it is manifest that such germina, though invisible to the naked eye, may, quite as readily as a fragment of diseased tissue of even consider able size, act as the efficient agents of new development. When, independently of this mode of generation, the disease returns in the seat of its former growth, the occurrence must depend upon the continuance of that depraved state of the blood vvhich is fitted to supply the necessary blastema, and likewise, possibly, upon some peculiar state of vessels of the part favouring its exudation here rather than elsewhere.
In other cases, hardly has a growth been removed from one place, when a mass of the same kind appears in some distant and appa rently unconnected part of the body : this occurrence, which is especially observed in the case of cancer, is termed its " distant repro duction," and is explicable in two ways. The newly discovered growth may have existed previously to the extirpation of the old one, and having simply acquired additional activity, so become obvious, after that extirpation. Or the new growth may really have first appeared subsequently to the removal of the old (this we believe to be rare) : in this case the simple explanation is that the vitiated state of the blood, proper for the supply of the neces sary blastema, continues ; and this blastema is poured out in some other part of the frame, the original tumour no longer existing to attract its deposition within or around itself.
§ 5. The chemical study of Growths is yet in its infancy. Miller's division into three chemi cal classes, the albuminous, the gelatinous, and the fatty (rational enough, chemically con sidered,) fails pathologically. Growths of very opposite tendencies and attributes are to be found in the same chemical class ; thus the most deleterious forms of cancer are albu minous, while sarcoma (per se most innocent) is the same in its chemical basis.
(a.) In the albuminous growth the other forrns of protein are frequently present as essential ingredients ; the term growth of protein-basis appears therefore more strictly applicable. A matter said to be allied to ptyalin has been found in this class. Con tinued ebullition scarcely furnishes a trace of gelatin ; and when some such trace does appear, is probably derived from natural gelatinous textures accidentally connected with the morbid mass.
(b.) Growths of the gelatinous class are almost completely reduced to jelly by boiling. The gelatin yielded is either of the common species, as in fibroma, or of the variety known as chondrin, and first detected by Miller in enchondrotna.