SEA-FISHERIES LABORATORY. 91 



aggregations of small oat-shaped cells occurs only at the 

 margin of the tumour and as the result of a stimulus 

 exerted by some substance secreted by the latter. 



Figs. 4 to 7 of Plate II represent the proliferation of 

 sarcomatous tissue along a region of fibrosis. Fig. 4 

 is a low-power drawing and shows the growing point of a 

 nodule, which elsewhere is surrounded by a feeble 

 capsule. Round the nodule is loose areolar connective 

 tissue with loosely arranged muscle fibres running in 

 various directions. A large area of the section, of which 

 the figure represents only a small part, is occupied by a 

 rather dense fibrous tissue, similar to that found in 

 benign, capsulated fibromata. Fig. 7 represents the 

 general nature of this tissue, and it is seen to consist of 

 bundles of fine fibres, pursuing a straight or slightly 

 convoluted course. Among them are some coarser fibres 

 staining red with Mallory's stain. These are shown to 

 the left in fig. 4. Towards the right in this figure they 

 are seen to be undergoing disintegration, and there also 

 are to be seen the remains of the original capsule of the 

 tumour. The stippling shows the locus of the truly 

 sarcomatous cells, and it is clear that there is no distinct 

 boundary between these and the adjacent fibrous tissue. 

 This is the growing margin of the tumour — the region of 

 active proliferation, and it is shown, highly magnified^ 

 in fig. 6. Here we see the fibrous tissue with some of its 

 own nuclei, and in it there are large numbers of very 

 small round cells. Fig. 7 represents part of the section 

 still further removed from the growing margin of the 

 tumour, and here the tissue represented is, for the most 

 part, that of the fibroma along which the sarcoma is 

 proliferating. The nuclei of this fibrous tissue are shown, 

 but there are also a few small round or ellipsoidal cells, 

 which are evidently those of the sarcoma. Fig. 5 



