the supportive substance is so abundantly developed that the tumor becomes harder, and we then have the so-called "lymphosarcoma durum."

It is evident that a partial and local increase of this reticulum in the neighborhood of blood-vessels must result more and more in the formation of an "alveolar structure," and, as a matter of fact, forms are often seen which, in the point of alveolar arrangement, present the greatest similarity to carcinoma. This similarity is enhanced by the fact that sarcoma of this character, as a rule, is not of the small round-cell variety, the cellular elements being larger, richer in protoplasm, flattened and polygonal on account of being densely packed together, and thus simulating a true epithelial aggregation. Owing to this morphologic similarity to the type of the carcinoma and the resulting diagnostic difficulties the term sarcoma carcinomatodes has often been employed to describe this form; but the name ought to be sedulously avoided whenever it is possible to obtain information in regard to the real character of the tumor. Usually such information is obtained by careful analysis of the contents of the individual alveoli and their relations to the surrounding stroma. In alveolar large-cell sarcoma the cells have become more polymorphous. In addition to the simple round forms, numerous elongated, polygonal structures, provided with protoplasmic processes are seen, particularly in the peripheral portions of the alveoli, and, as a rule, a connection between these cellular processes or intercellular substance, if such is present, with the fibers of the reticulum that form the alveolar walls, can be demonstrated; the fibrous tissue of the alveolar walls may send out delicate, extremely minute filaments to form an intercellular substance. The individual alveoli themselves are unequal in size and usually spheric, in contradistinction to the cylindric cell-aggregations of carcinoma.

2. Spindle-cell Sarcoma (Sarcoma Fusicellulare).—In spindle-cell sarcoma we see a higher degree of cell-differentiation than in round-cell sarcoma. While the physiologie prototype of the latter is practically represented by

PLATE 53.

FIG. 1.-Fibroma Sarcomatosum of the Inguinal Glands (Recent Teased Preparation. × 280.): 1, Large spindle-cells imbedded in fibrous intercellular substance; 2, isolated spindle-cells; 3, spindle-cells with their cell-bodies in a state of partial fatty degen

eration.

FIG. 2. Spindle-cell Sarcoma of the Uterus (Hemat.-eosin. × 250.): 1, Long, spindle-shaped cells; 2, segments of the same without nuclei; 3, cells with stellate protoplasmic processes.

FIG. 3. Sarcoma Myxomatosum from the Brain (Hemat.eosin. × 250.): 1, Cells after the type of round cells; 2, spaces filled with mucoid ground-substance; 3, thin-walled blood-vessel.

the so-called small-cell inflammatory infiltration, the elements of the spindle-cell sarcoma find their prototype in the "fibroblasts," which, as we have seen, may play an important part in inflammatory proliferations and in regeneration.

In this variety, then, the connective-tissue character is more pronounced even in the form of the cells. The development of intercellular substance is variable; the tissue may present a distinctly fibrous type, and it may be so abundant as to bring about transitional forms between spindle-cell sarcoma and the cellular form of fibroma.

According to the average size of the cells, these tumors are divided into small and large spindle-celled sarcomata. In the former the individual cells are small in size, and in a recent preparation readily isolated, appearing as elongated structures with a central bulging and long processes drawn out into points, which project from each end of the cell. The nucleus is situated centrally in the thicker portion of the cell; the shape is that of a long ovoid, and the chromatin network is quite thick. The nuclei usually occupy the entire width of the cell, so that in a longitudinal section the body-protoplasm appears in the form of two peaked caps covering the two poles of the nucleus. The mutual arrangement of the cells is such that the point of one cell is inserted into the space between two other cells, thus bringing about a rhomboid arrange