Report on Diseases and Abnormalities in Fishes. 23 



by little refractile corpuscles. Much of the spongy fascia of the 

 tiiinour was green : the rest was red in colour. Little masses of 

 green granular substance enclosed in a thin skin were found inside 

 tne tumour. 



The tumour rested on the lower muscles, and it had evidently 

 replaced some of the superficial muscles. Fibres run from the skin, 

 covering the central region into the tissue of the tumour. 



Mesenteric Cyst from Skate (Raia). 



A mesenteric cyst, shown in approximately natural size in fig. 

 103, was fjound in the abdomen of a skate. It was translucent, and 

 contained a watery fluid. After preservation in formaline solution, 

 a white fiocculent precipitate was observed in the fluid, showing 

 that a part of it had coagulated. The mesentery (me.) and the wall 

 of the cyst was dotted all over with white tumours of various sizes, 

 measuring from 5 mm. to 8 mm. in diameter. They contained 

 a white coagulated fluid. The mesentery was blotched with amber- 

 colour here and there, the coloured patches varying from less than 

 a millimeter up to an area of 5 mm. by 3 mm. in extent. 



Tumour in Pharynx of a Salmon Caught in the Sea. 



It is shown in natural size in fig. 139. It was found loose in the 

 gill cavity after the fish had been killed by a blow on the head. Two 

 of the gills were found to be damaged. There was a sinus in the 

 free edge of the gill. It is not clear how the tumour was attached, 

 but the connection was apparently a slender one. The tumour is 

 lobulatecl, fibrous in structure, without any distinct lamina. 



Bony Tumour. — Osteoma. 



A rounded swelling was observed on the outside of a cod. It was 

 due to a bony tumour attached to the vertebral column, and extending 

 right to the skin. The tumour had displaced the trunk muscles. It is 

 shown in half-size in t., figs 131 and 135b. It was a tuberculated 

 mass, and it was covered with fibrous fascia. 



The tumour had pushed its way between the neural and haemal 

 spines, and had caused some of them to be deflected (fig. 135b). A 

 small round portion of the tumour projected into the neural canal. 

 It must have compressed the spinal cord. 



A section of the vertebral column and the tumour is shown in 

 natural size in fig. 140. It is seen that the tumour had arisen 

 from one vertebra, viz., (c ). Fig. 130 represents a longitudinal 

 horizontal section of a normal vertebra. The tissue which forms 

 the cancellous bone (sr.) is responsible for secreting the tumour. 

 The control which adjacent parts normally exert had been in some 

 way withdrawn, and the excessive bone formation resulted. The 

 striation in the tumour is all radiate. 



Ulcer on Plaice. 



A disease which takes the form of a rodent ulcer is common on 

 the upper and lower surfaces of plaice kept in confinement. It has 

 been described by Anderson. He regarded it as caused by 

 staphylococcus infection. The wound formed bv the ulcer some- 



