cells constituting the bulk of the tumour, and they bore a close resemblance to the "globes épidermiques" of epithelioma, the tendency to infiltration with calcareous salts forming their chief distinction from these.

Whether these tumours should be classed with the epitheliomata or simple papillomata, and what may be their origin and history, are questions interesting to the pathologist rather than to the practical surgeon, who is so little likely to encounter them that some apology is necessary for introducing them at all into a work whose scope is avowedly purely practical.

CHAPTER IX.

Epithelioma-Its Distinction from Carcinoma-Its Minute Structure — Columnar-cell Epithelioma-Rodent Cancer.

THESE sketches of the various new growths commonly called cancers, would not be complete without a reference to the well-known disease which, from its cancer-like nature, has been usually styled "cancroid"-a term which is objectionable from its vagueness, but which aptly enough expresses the clinical characteristics of the disease.

For EPITHELIOMA-by which is meant a new growth furnished by the proliferation of the epidermis, or by the epithelium of the mucous membranes-although sometimes in its later stages thoroughly malignant, affecting chain after chain of lymphatic glands, and cropping up luxuriantly in remote viscera, as the heart and lungs, is yet a growth far more under surgical control than any of those which we have been considering. For while with our present mode of operating we hesitate to affirm too boldly that we can eradicate a scirrhous cancer by cutting it out, there are few surgeons who would deny that they have finally extirpated a small epithelioma of the lip or scrotum by a comparatively trifling operation.

So it is that this disease has been almost always separated somewhat from the true cancers, whilst some able observers -the late Mr. Collis, of Dublin, for instance-have refused to place it in the same category at all. And yet the more modern pathologists, as Billroth and Rindfleisch, merely regard it as a variety of carcinoma, affirming a close analogy of minute structure in the two growths, and pointing to the

difference of origin of their cells—glandular, or surface epithelia as constituting the sole claim to separation into distinct varieties.

Nevertheless, although both growths are made up of epithelial cells and stroma, and in certain points are closely analogous, I cannot help thinking that we, in England, are wise in keeping them distinctly apart; for both in coarse physical appearances and in minute structure the disease to be now sketched differs from that which we have studied under the head of carcinoma as widely as it differs from it in the far more important features of clinical history and symptoms.

An epithelioma of the cutaneous surface, occurring usually as a shallow hard ulcer with thick fungous edges, presents a favorable specimen for exhibiting the characteristic microscopic structure of the growth, as well as its mode of origin and of invasion of the neighbouring parts. On examining a thin section from the margin of such an ulcer, one is at once struck by the fact that although here, as in carcinoma, we have before us clumps of epithelial cells in an irregularly alveolated stroma, yet the cells now differ hardly at allsave, perhaps, in their size and active nuclear proliferationfrom the normal epidermis cells from which they have descended. We lack here the rich variety of cell-forms which supplant the small regular gland epithelium in carcinoma of the mamma, for instance, and at the same time we notice how comparatively slight are the fatty changes occurring in the misplaced epidermis scales. They dry up, shrivel, become squeezed by circumferential pressure into curious onion-like masses-the "globes épidermiques," "epithelial pearls," or "bird's-nest bodies" met with wherever excessive epidermis growth is in progress, but in singular and characteristic abundance in epithelioma (see fig. 20, a, and fig. 21, a) -or they become distended with colloid material (fig. 20, c); but they seldom undergo much oily degeneration, save where inflammatory or ulcerative changes are actively at work. The cells further show a great tendency to cohere by their

margins, as do normal epidermal cells, and sometimes present beautiful objects for examination with the higher powers, by

FIG. 20.-Elements from an epithelioma of the lip. Magnified 220 times. a, An epithelial pearl, showing the production of these bodies by the multiplication and subsequent flattening of squamous cells; b, serrated cells; c, cells containing colloid matter.

dovetailing together by finely serrated edges, after the fashion of the upper cells of the healthy rete mucosum (see fig. 20, b). In fact, the new growth seems to consist simply of masses of surface epithelium, which, instead of appearing above and between the papillæ, dip down amongst the connective tissue, and there actively multiplying and thriving as much from the unwonted supply of fluid nourishment as from the absence of the desiccating process to which they are normally subjected as they are pushed on towards the surface of the body, form large tubular and branching collections, capable of more prolific development the further they are removed from the surface, and at the same time more freely subjected to the risk of single cells being taken up and hurried away in the lymph- or blood-streams to form similar collections elsewhere.

This seems to be, indeed, what really happens in the formation of a primary epithelioma. Why this invasion of

the subcutaneous tissues by epithelial elements takes place in certain cases, when all the physical conditions favorable to its production must be frequently present in any wart or condyloma, it is not easy to say; but there is nothing in the process, so far as we can observe it, to justify us in assuming a special condition of the blood as its determining cause, whilst the dispersion of the disease throughout the bodyrarely considerable in its extent, seldom involving more than the nearest chain of lymphatic glands, and always presenting the same epidermis-like scales wherever the secondary growth springs up is thoroughly and solely suggestive of transference of cells of the primary tumour and their multiplication in their new seats.

Thus, the one essential anatomical feature of epithelioma is the presence of proliferating epidermal cells in abnormal situations. So long as the change is limited to an excessive development of surface epithelium, with, it may be, considerable enlargement of the papillæ, the growth is a papilloma; or if the proliferation commence in a sebaceous gland, so long as the result is a mere accumulation of gland epithelium within the gland walls, this may go on to almost any extent, and be accompanied by secondary fatty changes, but the only issue will be a more or less inconvenient "atheromatous cyst"-both purely innocent formations. But once let the boundary be broken through, and the cells penetrate the deeper tissues, and lymphatic (or even vascular) infection may take place at any time-in all probability with a rapidity in proportion to the movement and moisture of the affected part; and with such infection the growth

1

1 In the paper contributed to the 'St. Thomas's Hospital Reports' for 1871, to which reference has been already made (vide footnote, p. 10), I have tabulated seventy-three cases of epithelioma recorded by me in the cancer tables of the Middlesex Hospital, with the object of setting forth this connection which exists between the physical conditions of locality and the malignancy of the disease. It is there shown "that the cases showing contamination of the glands and other parts are precisely those in which the growth is subjected to the greatest amount of movement. Thus, in the lip, tongue, genitals, groin, hand, and heel, the glands were affected in from 50 to 100 per cent. of the whole