80 TUMORS. 
They may contain many or few bloodvessels. These tumors are classed 
as benign. 
What are the characteristics of myxomata ? 
In structure they resemble mucous tissue. Branching cells with a 
relatively large amount of intercellular substance. This intercellular 
substance contains mucin. These tumors are benign but seldom occur 
as pure myxomata, usually combining with fibrous or fat tissue to form 
fibro- or lipo-myxomata. 
What form of tissue do the sarcomata resemble and into what 
varieties are they classified ? 
They resemble embryonal tissue, being made up of spheroidal or of 
spindle-shaped cells with a small amount of fibrillar intercellular sub- 
stance. They are classified according to the shape and size of their 
predominating cell elements, and are malignant. The varieties usually 
referred to are the large and small round-celled, the large and small 
spindle celled, the giant-celled sarcomata and also the melano-sarcoma. 
Combinations of sarcoma tissue with that of other forms of tumor may 
give rise to various compound tumors to be described later. 
What is the structure of the large- and of the small-celled sar- 
comata ? 
The small-celled form is made up of cells resembling lymph cells, 
and of about the same size. There may be much or little intercellular 
substance. The cells may be irregularly disposed or may be arranged in 
indistinct alveoli. In the large-celled variety the cells are of various 
sizes, but the majority of the cells are larger than those of the previous 
variety. Both forms are, as a rule, very vascular, and the small- 
celled variety is the more malignant of the two. 
Describe the spindle-celled sarcomata. 
The spindle-shaped cells may be large or small. There may be very 
little intercellular substance, or it may be so abundant as to resemble 
fibrous tissue, thus forming a fibro-sarcoma. These forms are as a 
rule less malignant than the round-celled varieties. 
What are the peculiar features of a melano-sarcoma ? 
Large and small particles of a blackish or brownish pigment are found 
irregularly distributed in the cells, less often in the intercellular sub- 
stance. The cell structure is most often of the spindle-shaped variety, 
although other-shaped cells may be found. 
