230 



remains. At the central part of the tumour the integument, 

 so altered, becomes very thin and finally breaks through at the 

 region where the internal part of the tumour is undergoing 

 necrosis. 



Cutting down into the latter, along its middle line, we 

 find this general liquefaction, and the necrosed contents rest 

 directly on the bones of the skull. In the firmer parts we have 

 the fibroid type of structure — fine fibres running in various 

 directions and, here and there, a few round cells. The latter, 

 however, do not characterise the histology, which is of the 

 nature of that seen in fibromata rather than in sarcomatous 

 growths. The malignancy is evident, however, when one looks 

 at the growing margin. On the left-hand side in Fig. 2 are a 

 number of isolated muscle fibres, here cut obliquely : in a 

 section of this region in a normal fish there would be a thick 

 layer of muscle bundles running in various directions. Here, 

 however, these are degenerate and are represented only by 

 detached fibres, becoming fewer as the tumour is approached. 

 The malignant tissue is represented by fine stippling in the 

 figure, and this is seen infiltrating the muscle tissue, intruding 

 between the fibres. It is, as in all other fish sarcomata that 

 I have seen, this intermuscular connective tissue that takes 

 on the conditions of malignancy and gives rise to the sarcoma- 

 tous tumours, 



Cestode Degeneration Cysts in Trout. 



The viscera of a 10-lb. yellow trout were sent to me by 

 Mr. J. Ritchie, of the Perth Natural History Museum. These 

 structures contain a number of cysts which are so very remark- 

 able that a description may be interesting even although the 

 parasites responsible cannot now be identified. 



The peritoneum over the liver and pyloric caeca bear a 

 number of little oat-shaped bodies which look almost like seeds. 

 They are about 4 or 5 by 8 to 10 mm. in their lesser and greater 



