that, although all three varieties of new growth are truly and formidably malignant, they exhibit this property in very different and definite degrees.

Thus, sarcoma, although in certain of its forms nearly as prone as carcinoma to infect remote parts, very rarely invades the lymphatic glands, and probably seldom appears as a secondary tumour until a comparatively late stage in the disease; hence the greater hope of a successful issue of any operation attempted for the removal of a sarcomatous growth, provided that the affected limb be divided at a safe distance from the tumour. Where this is not possible, as in certain cases of mammary sarcoma, although the patient may live long with no visceral or glandular complications, yet the local growth itself will be very apt to return with great pertinacity; the reason being, that sarcoma is as essentially an infiltrating or tissue-invading growth as carcinoma, and equally difficult to extirpate without a freer use of the knife than is commonly deemed necessary. Mr. De Morgan1 has suggested a rule for operative interference with these malignant tumours of the limbs. After narrating two cases of sarcoma of the lower limb before the Pathological Society of London last year, he remarked—“ Are there any means of diagnosing these sarcomatous tumours from true cancerous encephaloid growths, if such exist? There can be no doubt that in the latter disease amputation should be performed through the joint, not in the continuity of the bone. I do not think it is so necessary in a case of sarcoma. At any rate, I have amputated through the bone in some of these cases without return of the disease after many years." In the same contribution it is suggested that "generally the veins are less defined, and the growth is much more rapid in a sarcoma than in an encephaloid cancer." Whether this last observation is constantly true or not, I have no means of judging, for I confess to having myself very rarely seen primary soft carcinoma of a limb; and as I have seen very many malignant growths in such positions, I am led to believe 1 'Path. Trans.,' vol. xxi, p. 341.

that primary soft carcinoma of the extremities is seldom met with by surgeons. In the form of secondary growths in the viscera I know of no distinguishing naked-eye character of sarcoma save the absence of umbilication. Very few carcinomatous nodules, however soft, fail to exhibit more or less dimpling of the surface from contraction of the fibroid stroma upon the cells which, in the centre of the growths, so soon fattily degenerate; but I believe that secondary sarcomatous nodules have usually no such sign distinguishing them. For the rest, these sarcomata vary in consistence from tough fibrous tissue to a creamy softness, yield to the knife scraping the cut surface an abundant milky juice, blend intimately with surrounding healthy tissues, rarely being encapsuled, although occasionally shelling out from such a tissue as the lung as though they were so limited, and in all respects bear the closest resemblance to genuine soft carcinoma.

The main distinctive characters of sarcoma, therefore, are to be sought for solely in the form and arrangement of its microscopic elements; and a sarcoma may be described as a tumour made up of embryonic tissue, which may tend towards development into a perfect tissue. Hence a sarcoma is almost entirely a cellular growth, with more or less of visible intercellular substance, and the cells are usually of a spindle or fusiform type.

Although the prevalence of one form of cell in each tumour is the rule, it is not uncommon to meet with considerable variety in the size and shape of the component cells in a single tumour; and in classifying the sarcomata, therefore, one must have regard rather to the prevailing form of cell than to the exclusive presence of any one form. Thus, one may meet with fine oat-shaped, large plump spindle, small or large oval, small round, and huge myeloid cells; and, according to the proportion in which any one of these forms preponderates, sarcomatous tumours are subdivided into—(1) spindle-cell, (2) round- or oval-cell, and (3) myeloid sarcomata. Besides these general varieties, sarcoma takes a

special form, and receives a special name, Glioma, when affecting the neuroglia or fine connective tissue of the nervous system.

In all these several varieties, however, the one character remains-viz., that the bulk of the tumour is built up of simple cells, bound together by a scanty homogeneous or granular semi-fluid substance. Hence a marked distinction from carcinoma, in which the cells are, as a rule, quite free from any visible intercellular material, and float in the meshes of a fibrous stroma. A further difference is seen in the form of the component cells. It has been already said that the cells of carcinoma are of an epithelial type. Now, cells of this kind are very rarely met with in sarcoma. One does, indeed, occasionally meet with a formidable variety of sarcoma, in which huge angular and many-tailed cells are interspersed with the spindle cells forming the bulk of the tumour; and a scraping of such a growth might readily mislead an observer (see Plate II, fig. 3). But, in the great majority of cases, the cells of sarcoma, when they are not simply elongated and disposed in regular tracts, are plump and round or oval rather than angular, for they are imbedded in a soft fundamental substance, and are so not subjected to the changes of form brought about by mutual pressure in the case of the cell-elements of carcinoma. The semi-solid intercellular substance also accounts for the comparatively scanty juice yielded on scraping any but the softest sarcomas. This juice is also less freely miscible with water than that of carcinoma, the cells cohering in little flakes; and, in examining thin sections, very few detached cells float out into the water or glycerine in which the section is immersed, instead of the large number of cells so detached in carcinoma.

SPINDLE-CELL SARCOMA is by far the most common of all these tumours. Springing from connective tissue, and assuming the form met with in the development of granulation tissue into the fibrous texture of a scar, one meets with considerable differences in the size and appearance of the cells, which may vary from an extremely slender fusiform shape,

barely distended in the centre by a small elongated nucleus, to a plump cell with large oval nucleus and delicate tapering extremities. Whichever variety be present, a certain definite arrangement of the cells prevails, their axes being parallel to one another, and broad waving tracts of such parallel cells crossing and recrossing through the tumour. A scraping generally shows sufficiently the type of cell present (see fig. 12), but viewed in section the shape of the individual cells is

FIG. 12.

FIG. 12. Scraping from a spindle-cell sarcoma. Magnified 220 times.

by no means always so easily made out. The regular arrangement of oval or elongated nuclei, and the occurrence here and there of patches of apparently small round cells enclosed by these others (fig. 13, b)—in reality similar bands running at right angles to the first, and so cut across transversely-is tolerably suggestive; but at the edges of such a section one may generally see the fine tails bristling out, if indeed there be not a free cell or two showing yet more distinctly their precise form (fig. 13). In some parts of these tumours the spindle-cell growth gradually passes into ordinary connective or white fibrous tissue, in such a manner as to render it impossible to say whether the spindle-cells are developing into the formed tissue or whether they are themselves derived from this by a retrograde metamorphosis to an embryonic condition. Besides this common admixture of connective tissue, spindle cells

usually form the basis of other sarcomatous tumours, occurring in small number, indeed, in the round- and oval-cell

FIG. 13. Thin section of a spindle-cell sarcoma, showing in the centre groups of similar cells divided transversely. Magnified 220 times.

growths, but rarely wholly absent. A curious feature of this growth is the tendency shown by its elements to assume a larger, plumper form with each recurrence, and, together with this alteration in the size of the component cells, to exhibit an increased rapidity of growth and proneness to infiltration. So far as my own observation goes, the changes in form with recurrence are limited to these, but my friend Mr. Anderson has recorded a case in which a recurrent spindle-cell growth of the breast in its latest appearance assumed the form of the "alveolar sarcoma" of Billroth, large oval cells being contained in the small meshes of a delicate reticulated stroma.

Spindle-cell sarcoma (including, as it does, the tumours long recognised as "fibro-plastic," "recurrent fibroid," "fibro-cellular," and many of the "medullary sarcomata") exhibits very different degrees of malignancy in different