PATHOLOGY 369 the following may be conjectured. In the pigniented scar of an old ulcer of the same region the subcutaneous fibrillar tissue is found to be thickly occupied with large spindle-cells full of brown pigment granules (see fig. 15). Now, the skin for some distance round the tumour in question had precisely the brown pigmentation of a scar that had re-formed repeatedly, and the brown colour resided pre sumably in the same embryonic elements as are drawn in fig. 15. It cannot be supposed, however, that that explanation applies to all spindle-celled sarcomas with pigment, even if we do not include those of the choroid tunic of the eye. A more general explanation must be sought for the pigmentation, which will apply also to the pigment in scar-tissue itself. us of Cystic Sarcoma. The activity of tumours, even of those classes tion that we have hitherto considered, is not purely structural or forma tive ; it may be obviously functional, involving an instability of the >ur- structure. Even the fibrous tumours may become cystic in their .ture. interior, as notably in the case of fibroids of the uterus ; and it may be stated generally that all such traces of cyst-formation in solid masses of embryonic tissue are so many traces of the deeply-rooted embryonic function of those tissues. This important principle of tumour pathology may be conveniently introduced through a par ticular case of spindle-celled sarcoma, which grew to a great size on the outer side of the thigh of a boy aged fifteen, having its root deep down in the interval between the tensor fascia; muscle and the vastus extern us. In no part of this tumour were traces wanting of an embry onic function residing in its component cells. Although the section of the tumour was close and firm, yet found under the microscoj the appearance drawn figure (fig. 24). The tract; surface -modification of the spindle-cells. These are the blood -spaces of the tumour, and blood is to be seen in them here and there Where Flo . 24.-Sarcomat.ms tumour growing from the excavation has been ex- inter-muscular septum of the thigh; spaces tensive the spaces have formed lined by cubical epitlwlial-like cells, communications, and left the spindle-celled tissue projecting into them as free cylinders or columns, with rounded ends covered with the same cubical epithelial -like elements. A central area of the tumour was more spongy in consistence ; and that character is found to depend upon the greater development of the spaces, ap proaching remotely to a cystic development. It is here that one sees the true physiological or embryological significance of the inter stitial spaces, of their contents, and of the cubical cells round their walls. The surface-row of cubical cells loosen from their attach ment, fall into the space, and are succeeded by another row, which are detached in turn ; and so the excavation proceeds at many centres. The detached cells do not remain free solid elements ; they may sometimes change in toto into a mucous fluid, but their full physiological activity is the haema- toblastic or blood-making. The spaces contain the hrematoblastic cells and their derivatives in various forms. One may see the cubical cells on the margin of the space (fig. 24) acquiring a yellowish tint, then the same cells disengaged and lying free in the space and probably increased 3 in size (fig. 25), then red blood-disks @? of the same colour as the protoplasm of the haematoblasts, and cells with Fio. 25. Htematoblastic process in several nuclei corresponding to those the spaces of sarcomatous tumour already described as the surviving f^^^^ HS nuclei of the disintegrated hoemato- geneous; b, blood-disks of various blast, the whole lying in the midst shapes ; c, the surviving nuclei, of a mucus-like coagulum. This is neither more nor less than the early blood-making function of the mesoblast revived. The result is not by an} means always or altogether blood, and in cysts it is indeed for the most part a mucous or serous fluid. In one direction this process goes on to the ultimate destination of a thin-ioallcd cyst ; and the following case of spindle-celled sar comatous tumour may be regarded as an interesting intermediate phase. The tumour is the size of an orange, from the neck region of a dog ; the peculiarity of it is that it is excavated completely on the side next the skin, while the deeper half of the sphere is made up partly of a firm texture with slits or spaces lined by cubical cells, as already described, and partly of a beautiful interlacing system of polished cylinders crossing the cavity from side to side, or han"- ing free into it. The process of excavation has merely been an extension of that drawn in fig. 24 ; it may be compared to the ex cavation of the heart in the embryo, the columns; carnese and musculi papillares and pectinati of the latter corresponding to the columns and free projecting cylinders of the cyst. It is noteworthy that a trabeculated interior is characteristic of many cysts. Myxoma or Mucous Sarcoma. In another direction the hremato- Myxoma. blastic softening process goes on to the variety of tumour called myxoma or mucous sarcoma ; and this change may be actually observed in parts of the above-mentioned extensive spindle-celled sarcoma from the outer side of the thigh. A myxoma is that par ticular modification of embryonic mesoblast in which the softening or fluid disintegration takes place, not along definite or selected tracts, but uniformly over a particular area. The cells become excavated somewhat as in fat formation, the nucleus remaining at one side, arid their thin membranous walls appearing as branching processes, which join with those of the next cell. Hence the nuclei often lie as if at nodal points of a meshwork of fibres, and they are often triangular or lozenge- ,,* , /(5v *, ^-t f v, shaped. This is one common ; -. " : ^fg$MsmJ : ii form of myxomatous tissue. But the mucous transformation taking place in each individual cell may result in a tumour pre senting a very different appear ance. The figure (fig. 26) is taken from a soft gelatinous tumour of the subcutaneous tissue. Nothing could be more orderly than the grouping of its large mucus -yielding cells in rows following the waved course of the bundles of fibres or fibrils; they are as regular as the cell- plates of tendon. Their origin can be traced to the fixed con nective-tissue cells of the part, which have emerged from their inconspicuous state, and have FlG - 26.-Mucous sarcoma of subcuta- acquired breadth and thickness, a cubical form, and mucus-yielding protoplasm. Precisely the same process may end in a cystic excavation. The relation of this change to the indwelling tendency of the mesoblastic cells towards blood- making is revealed in the actual hrematoblastic character of the cells here and there, and in the blood-disks and cells with cleft nucleus lying around. Another intermediate or occasional form of the cells in this tumour reveals also the true affinities of spindle- cells filled with yellow or brown or black pigment. Such pigniented spindle-cells replace the mucous cells here and there ; we must consider them to be also a somewhat devious development in the hfematoblastic process, their pigment being practically the same as blood-pigment. Alveolar Sarcoma. In this connexion also we must take the Alveolar kind of tumour that is often called alveolar sarcoma. The epithelial- sarcoma, like form of cell, which lines the spaces among the spindle-cells in the case alread} 7 mentioned, now comes to predominate. The follow ing is an instance, with figure (fig. 27). A tumour the size of a large walnut, deeply pigmented, with the skin drawn tightly over it as if it had grown in the position of a mole or congenital mark, was removed from a man s leg. Al though the tumour is somewhat black throughout, the pigment is found to reside only in certain narrow tracts or clusters of cells. The structure is divided into oblong or alveolar spaces by narrow bands of fibres, the cells within the spaces being all of the epithelial type. Some of the cells are much larger than others, and these largest elements are tinted bright yellow or brown. It is no great step from this singular structure to the embryonic structure and function of former cases. Instead of a few cells at a p I(J- 27. Melanotic alveolar time forming an epithelial -like surface sarcoma of subcutaneous to an alveolar space (the great bulk of tissue, the tissue remaining as tracts and columns of spindle-cells), here the alveolation has been general through the whole area, and all the cells have become as if surface-cells. Furthermore, they have been fixed in that condition, proceeding to no further develop ment, whether mucus -forming or blood-forming, only certain groups of them, and these by far the largest and most epithelial- like, acquiring the yellow colour of hrematoblasts, or a brown colour. The pigment is otherwise contained in spindle-cells which occupy the interalveolar septa, and in them it is in a more granular form. XVIII. 47
