Secondary abscesses affect a special pre ference for the peripheric strata of the viscera ; so likewise do secondary cancers. In the instance of the lung, I believe this readily explicable, by the fact that the majority of the ultimate ramifications of the pulmonary artery reach the periphery of the organ before be coming continuous with the capillaries, where in stagnation must occur. n. Double organs are very rarely the sitnultaneous seats of pri mary abscess ; in cases of secondary abscess both invariably suffer : the same propositions hold good of cancer. a. Secondary cancer in the liver and lung occupies the same ele mentary seat (the lobules) as the pus of secondary abscesses." Some apparent ob jections to the doctrine here upheld are ex amined and (as we believe) refuted in the same place.
Or, thirdly, in certain cases where numerous parts are found to be the seats of tumours of the same species, it is more than probable that the development of these tumours has been simultaneous, and each mass been evolved independently of its fellows. There can be no doubt, for instance, that internal cancer is frequently described as secondary to external cancer (especially when the latter has been removed with the knife, and the former has not manifested its existence by symptoms until after the operation), where no proof of the two Growths not having originated at the same time can possibly be adduced. The sarne is true of Fibrous Growths.
The inoculability of Growths has not been maintained except in the instance of cancer, and, even in respect of this product, upon very imperfect evidence. Experimental re sults may be cited against (Dupuytren), and in favour of (Langenbeck), the transmissibility of the disease by inoculation ; while, on the other hand, we learn from M. Gluge that his attempts generally failed utterly, and in rare cases appeared to succeed. Theoretical con siderations, repudiating, as they do, the idea of the constant inoculability of cancer-ele ments in organisms of all varieties of morbid aptitude, nevertheless do not wholly oppose the notion, that where constitutional predispo sition to cancer exists in an animal, the ger niinal element of that product, introduced into its blood, may prove prolific. Unless this constitutional state exist, " even the ac tual elements of cancer only manifest them selves as simply irritative agents, the perfection of the seed is not enough to secure the de velopment of the plant; the soil, in which it is sown, must be capable of feeding it." Per haps these views furnish a clue to•the con tradictory statements of experimentalists.
§ 8. Clinical observers of disease have long been aware that certain Growths are of evil, others of innocent, tendency ; that they are " malignant" and " benignant." Morbid ana tomists have sought to connect definite and invariable structural characters with the pos session of one or the other tendency ; and their search has been vain. Micrologists are divided on this question ; some affirm that " malignancy" depends on the presence of a special cell ; others deny the distinctiveness of microscopical elements.
We, for our own parts, believe that the qualities of a growth cannot be determined by the characters of its cell. We have known
Growths, which had destroyed life with the cachexia of cancerous disease, and clearly exhibited the local progress and naked-eye characteristics of encephaloid; Growths which, nevertheless, were composed of non-nucle ated cells undistinguishable from those of common exudation-matter. Nor do we be lieve that any mode of association of cell and fibril (at least any mode now known and un derstood) can be considered distinctive of carcinoma. On the other hand, we believe that Growths of evil tendency have a manner peculiar to themselves (ascertainable by naked-eye observation) of accumulating in the tissues. We refer to accumulation by infiltration. The nature of infiltration is easily explained. The elementary molecules of the morbid matter, instead of accumulating round a central point equally in all directions, and pushing aside the tissues amid which they are deposited, spread between the primary ele ments of those tissues on every side. In proportion as this extension of the morbid matter is accomplished, interference with the healthy process of nutrition takes place. The effete particles of the natural tissues cease to be replaced by similar ones ; and an appearance of conversion (" transformation " or " degeneration") of a natural into a mor bid structure is worked out. But if the nature of the phenomenon be simple, its cause is obscure. Why it should occur (as we conceive it does) in the instance of cancer alone, and why peculiarities so important as those of' cancer, in respect of general influence on the system, should appear to hang upon the existence of a local pathological attribute, in nowise remarkable, strictly considered po se, is a difficulty which facts are wanting to explain away. Speculatively, as we have formerly said, " we must look elsewhere for an explanation of the evils practically con nected with infiltration, than to the mere physical phenomenon itself, — in a word, we must seek elsewhere some condition of which the process is but a consequence or invo lution. But the natural place to look for this condition is in the tissues themselves, which undergo infiltration ; and in these in some special morbid change within them — must reside the source and origin of the process. And this view is confirmed by the fact, that there is nothing in the mode of vegetation of cancer itself to explain why it alone, among vegetating new formations, should possess the power of infiltrating the natural tissues." We are aware that the property of infil tration has been ascribed to other Growths besides cancer ; that fibrous turnours have, for instance, been said to affect circumjacent tissues in this manner. But we are per suaded, from close examination of such al leged cases, that infiltration with common plastic matter (the produce of inflammation arising from irritating pressure on the part of the turnour) has been mistaken for infiltration with substance identical with that of the fibrous growth ; and that the distinction. is nosologically sound.
On the grounds just set forth, we propose to divide the order Growths into two sub orders — the NON-INFILT1RATING and the