382 PATHOLOGY cells of the appropriate type but also the appropriate grouping of such cells, the sperm-cells must be held to carry more than the influence of cell-units, and in fact to be representative of the whole structural and functional process in which they had played a part. Varieties of Cancer. The two main varieties of cancerous texture are the hard and the soft, or the scirrhous and the medullary. Scirrhous Scirrhous cancer is very often the "infiltrating" kind, with the cancer, epithelial cells lying in scattered groups or in single file within the spaces of a peculiarly dense and elastic connective tissue. It is Medul- common in the breast and not rare in the stomach. The medullary lary cancer consists of very much larger cancer, and closer groups of cells, which may be in nondescript heaps or in the more regular arrangement of glandular structure. When the glandular tvne is very distinct the n 1 IL l tumour is sometimes called a de- Colloid structive adenoma." Colloid can- cancer. ccr is a very peculiar variety, apt to occur in the stomach but not unknown in the breast ; most of the structure is changed into a brownish jelly - like substance which forms more or less definite spherical or alveolar masses sepa rated by narrow bands of stroma. Under the microscope (fig. 52) little of cellular structure of any kind is found remaining, but in place of it there are an immense FlG 52 . -Colloid cancer of the breast, number of spherical pearl - like bodies, each of which consists of several delicate concentric lamina? arranged round a more dense nuclear point. Cancer of Cancer of the skin, and of the lips and tongue, is generally termed skin, &c. epiUiclioma ; it is not a disorder of secretion in the same sense as (epitheli- other cancers are, but it is a disorder incidental to the constant oma). waste and repair of the epithelium of the skin. It is characterized by the encroachment of processes of the rete mucosum upon the corium and subcutaneous tissues, or, in the lips, tongue, upper part of the oesophagus, &c., of epithelial columns of cells upon the subepithelial region. The type of this encroachment is the papillary arrangement of the normal rete mucosum, where the appearance of regular columns of epithelium reaching down into the corium is equally due to the reciprocal protrusion of loops of blood - vessels upwards. The interlockin L epithelial -columns connective-tissue in epithelioma is more extensive and regular than in normal skin, and always difficult to cide, from the super ficial microscopic ap pearances, whether the encroachment of epithelium is men displacing or a trans forming encroachment (fig. 53). In some cases, such as destructive epi theliomas of the tongue, or of chimney-sweep s cancer, it is possible to find reliable evidence in the microscopic sections r Fio. 53. Epithelial cancer of skin deeply involv- tnat the progressiveness jng the side of the neck. The cylinders of of the disease is really epithelial cells, resembling those of the rete an infection, like that ""icosum, are surrounded by fibrous tissue in- of cancer elsewhere Crated with smaU nuclear cells, that is to say, the neighbouring tissues, and more especially the connective -tissue cells, are infected so that they assume the epi thelial type proper to the locality and that infection tends to spread without limit. But the doctrine of continuous growth from the rete mucosum downwards, by mere subdivision of pre-existing epithelium, appears to be justified as a part, at least, of the patho logy of cancer of the skin. As in cancers of the stomach and uterus, the regions liable to skin-cancer are especially those subject to re peated irritation or to prolonged functional disturbance. One of the most striking instances of this law used to be the cancer of the skin of the scrotum and groins in chimney-sweeps, a form of disease which has become much less common of late. Again, it is nearly always the lower of the two lips that suffers, and the rare cases of epithelioma of the lip that occur in women are among those of the sex who smoke pipes. Like other cancers, the cancer of the skin, lips, and tongue, &c., is a disease of later life ; according to Thiersch, it is due to a "disturbance of the bistogenetic equilibrium between epithelium and stroma, to the disadvantage of the stroma." The perfect balance of tissues would be exemplified by that regular interlocking of vascular papilla? from below and epithelial processes from above which the skin ordinarily shows ; as age advances the downward force of the epithelial growth prevails, owing to a certain decreased " turgor vitalis," or to loss of resistance on the part of the tissue carrying the blood-vessels, so that, when long-standing irritation of a particular spot is added, we should have the two great determining causes of cancer of the skin. But the question will always remain, whether the essence of the disease is not really an infective transformation of the quiescent cells of the connective tissue into the type and pattern of the irritated epithelial structure. The female breast is peculiar among the glands of the body in its great liability to cancer ; the disease is of essentially the same nature as that which ve find in the stomach and other epitheliated organs, but the occasion of it is quite different. It will therefore be convenient to reserve further remarks on cancer of the female breast until the next section that on the "liabilities of obsolescence." Extension of Cancer to Lymphatic Glands and other Discontinuous Discon- Parts. If the beginnings of cancer are to be sought for in some tinuous disorder of the apparatus and process of secretion, the disease very infectio soon passes the limits of the primarily disordered organ or part. The cancerous property of a tumour, as we have concluded, is from the first an affair of infection of the neighbouring tissues by epithelial products ; the infected neighbourhood is the seat of the primary tumour, the progressiveness or infiltrating character of which may soon cause a large area to be involved and a large growth to result. Sooner or later there is discontinuous infection, or the infection of more or less remote centres, whereby secondary tumours arise. This phase of cancerous infectiveness is by no means dependent on the extent of the primary infection or the infection of the original neighbourhood. That which distinguishes secondary can cerous nodules, wherever they are found, is the very close mimicry of the pattern of structure in the indigenous seat of disease, a pattern which is itself determined by the structural and func tional characters of the secreting organ or part concerned. In the majority of cases the nearest lymphatic glands become the subject of this mimetic process first ; the liver also is very liable to discontinuous infection, not only in cancers of the stomach and intestine, but even in cases of cancer of the breast, sub- maxillary glands, &c. There is always an interval of time before this secondary infection is set up ; and, although the cellular process is not different in kind from the infection of the neigh bourhood of the indigenous disease, it is necessary to regard the latter as, in a sense, the parent of the former. This parental Contra? relationship is made all the more probable by the fact that sar- betweei comatous tumours, which depend in many cases upon a reversion sarcom. to or survival of embryonic characters in the mesoblastic cells of a and particular locality, are also apt to be followed by tumours in distant cancer. parts, particularly in the lungs. In cancers, accordingly, we should distinguish three factors, and in sarcomas only two : in the former we have first the accumulation of cellular by-products of the secre tion, next the infection of the predisposed connective tissue by these epithelial products, and lastly the parental influence of the whole primary seat of infection ; in the latter we have the embryonic reversion of cells over a particular region, together with their increase or growth, and then the parental influence of the tumour which had so arisen. In both cases the primary tumour acquires a kind of individuality and a power to reproduce itself ; but it is only in some cases of sarcoma, especially those soft tumours of periosteal origin which become parosteal, that there is infection of the neighbourhood, whereas a cancer is not a cancer at all until the tissues adjoining or supporting the epithelial secreting structure are epithelially infected. This difference between sarcoma and cancer corresponds to the familiar fact that the former are only occasionally "infiltrating" tumours, being in most cases marked off from the neighbouring tissues by a definite capsule. The simplest case of discontinuous cancerous infection is in the lymphatic (/lands near the original seat of disease. It is only ex ceptionally that the lymphatic glands are infected in sarcomatous tumours, and those cases appear to be mostly the infiltrating sarcomas which have the distinctively cancerous property of in fecting the neighbourhood. Infection of the axillary lymphatic glands is the common sequel of cancer of the breast, while the epi gastric, portal, mesenteric, and other abdominal lymph-glands receive the infection in cancer of the stomach and intestine. In epithelioma of the lip and tongue the infection of lymph-glands is much slower, and is often so slight as to be undetected during life ; it specially affects the lymph-glands under the chin. In all cases the tendency is to reproduce the exact pattern of the primary tumour. In some, including those sarcomatous cases where this kind of infection does take place, the lymph-gland seems to have been transformed en masse, very rapidly and directly, so that steps in the process are hardly to be detected. But in other cases it is possible to find, either within the same gland or among the various glands of a cluster, a certain amount of instructive histogenetic detail as to the
