SEA-FISHERIES LABORATORY. 93 



substance. The stroma is entirely absent. The tumour 

 here is what has been described as a small-round-celled 

 sarcoma. 



Finally the central part of this, and of most other 

 nodules, consists of a tissue represented in fig. 4. This is, 

 perhaps, the most characteristic tissue of the growths here 

 investigated. In it are found large numbers of small 

 spherical cells, but there are many other kinds. Some 

 are spindle-shaped, larger than those represented in 

 fig. 4, and with blunt, rounded ends. The nuclei of these, 

 and the small spherical cells, are apparently quite 

 normal. There are numbers of larger cells, oval, round, 

 or irregular in shape : many of these contain two nuclei. 

 Then there are structures which one may call ' ' giant 

 cells," and these are not all the same. Some have a large 

 central nucleus with several smaller peripheral nuclei. 

 Others can simply be called multinuclear cell masses. 

 Others again appear to be syncytia containing a number 

 of small nuclei distributed quite irregularly. Apparently 

 they have arisen from irregular nuclear division which 

 has not been followed by cell division, rather than from 

 the fusion of adjacent single-nucleus cells. Along with 

 all these elements are cell fragments, cells containing 

 melanin granules, and apparently loose melanin. Such 

 a section represents the conditions in a tumour which is 

 beginning to undergo necrotic degeneration. In the 

 central parts of the larger tumours some of the same 

 elements can be recognised, but here the process of 

 autolysis has gone on to a remarkable extent, and the 

 substance of the tumour consists of a thick liquid 

 containing disintegrated cells, with melanin granules. 

 The latter are the more abundant the further the process 

 of necrosis has proceeeded. 



Summing up, then, the specimen here described is a 

 good example of a fish suffering from multiple, melanotic 



