120 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



infiltrated, the fibres themselves being separated. Finally 

 the deeper dermal structures become involved, and in 

 the centre of the tumour the whole integument has 

 broken down, but even there the underlying systemic 

 muscle bundles remain unali'ected. 



Fig. 1, PI. II, represents a typical part of the fully 

 developed tumour as seen under a high power lens. It 

 has been drawn from a section made from a part of the 

 tumour fixed in vom Eath's fluid. The section was 

 treated with hydrogen peroxide, but the melanin was not 

 entirely removed. The stain was iron haematoxyliu, 

 followed by eosin. The sarcomatous cells are of various 

 types. Many of them are spindle-shaped and two of 

 these are represented in fig. 2, PL II, isolated from 

 their surroundings. In some of these cells the nucleus 

 is situated at one end, giving the cell a club-like 

 appearance, but usually it lies at about the middle of the 

 spindle. In these cells the nucleus is often quite normal 

 in appearance, though perhaps the chromatic skein, or 

 synapse, is more pronounced than in undifi'erentiated 

 cells, and the linin substance is colloid-like. As a rule, 

 however, the nucleus is not easily seen in these cells 

 and is, no doubt, the seat of melanin deposition and 

 degenerative changes. 



Many other cells are short spindles, or are " oat- 

 shaped," but the greater number are round, irregular, 

 and variable in size. Some of these are represented in 

 the figure ; like the larger spindle cells, they possess 

 nuclei wliicfi vary very greatly in appearance, owing to 

 I lie iiniouiil of melanin deposited. No traces of nu(;lei 

 are to be seen in some of them, and the cell looks like a 

 locus only for the aggregation of melanin granules. 



These cells, varying in shape and size from elongated 

 spindles about 008 mm. in diameter to round cells only 



