24 BULLETIN 1449, U. S. DEPARTMENT OF AGRICULTURE 
sarcoma which are softer and more vascular. The less malignant 
spindle-cell fibrosarcoma may be encapsulated, and when subcuta- 
neously situated and multiple they are sometimes called " recurrent 
fibroids." 
The large spindle-cell sarcoma differs from the small spindle-cell 
sarcoma in the size of the cells, which range from 50 to 80 microns, 
or from four to six times the size of the small spindle-cell variety. 
The cells are less uniform in size, and often show all gradations in 
the size of the ceils. The nuclei are large, usually oval, sometimes 
granular, and often vascular. The bundles of cells are less inter- 
lacing and are more nearly parallel in disposition. Large spindle- 
cell sarcomas are not so compact, owing to a large amount of inter- 
cellular substance. Large spindle-cell sarcomas occur less frequently 
than the small spindle-cell variety. 
ROUND-CELL SARCOMA 
Round-cell sarcomas are found as commonly in domestic animals as 
in man. They are the most common variety of sarcoma in man, and 
according to some observers are even more frequent in domestic 
animals than spindle-cell sarcomas. The cells may be small or large. 
Small round-cell sarcomas are the most malignant form of sar- 
coma. Their malignancy is due to infiltration and destructive 
properties, as well as the readiness with which they form 
metastatic deposits in internal organs. Small round-cell sarcomas 
are soft to the touch, pinkish-red or fleshlike in color, very vascular, 
and often so hemorrhagic as to justify the name of " telangiectatic " 
or "bleeding sarcoma." The cells of the small round-cell sarcoma 
are about the size of lymphocytes, and their nuclei occupy practi- 
cally the entire cell, leaving very little cytoplasm around the granu- 
lar, well-staining nuclei. There is very little intercellular substance 
between the small globular cells, which enables the loosely clumped 
cells to metastasize more easily than the overlapping and compactly 
arranged cells of the spindle-cell sarcoma. Small round-cell sar- 
comas may occur in any part of the body wherever connective tissue 
exists. They grow rapidly, infiltrate the surrounding tissues, and 
recur after removal. Because of their rich blood supply and the 
thinness of the walls of their vessels, they give metastatic deposits 
to all internal organs, but especially to the lung, liver, spleen, and 
kidney. 
The large, round-cell sarcoma consists of cells that are often larger 
than the mononuclear leucocytes. The cells are more variable in size 
and less regular in shape than the cells of the small, round-cell 
variety. The nuclei are relatively smaller, with a generous quan- 
tity of cytoplasm around them, which gives them the appearance 
of cells of the epithelial type. The cells stain less deeply than in the 
small, round-cell variety, and appear more loosely arranged, on ac- 
count of the abundance of the interstitial substance. Large, round- 
cell sarcoma occurs less frequently than the small, round-cell sarcoma, 
and is not so malignant. Several cases in the mammary gland, the 
ovary, and the testicle have been described, but the neoplasm may be 
found in other locations. 
