28 Fishery Board for Scotland. 



matter scraped oft' the inside of the cavity. I did not find any very 

 definite indications of fungus, but a few fine hypha-like filaments 

 were present. 



On dissecting the fish and separating the muscles along the dorsal 

 spines of the vertebrae, three blood-extravasations were found below 

 the fatty fin (fig. 105). Further forward, and immediately behind 

 the first dorsal fin, I found, just under the skin on the right side, a 

 small purple-coloured region. It appeared to have been an old sore. 

 The skin over it was quite normal. In the same region a dark red 

 patch was observed in the muscles above the dorsal spines. When 

 the dark red. muscle fibres were examined under the microscope the 

 capillaries were found to be distended with blood. Here and there 

 extensive groups of corpuscles indicated the rupture of capillaries. In 

 the two regions, then, the blood-vessels crossing the dorsal spines had 

 been ruptured. No bones appeared to have been broken, however. 

 The dark-red colouration was very small in extent. The flesh 

 generally was a light red, except in the anterior parts, where it was 

 of the normal j)ink colour. The pink muscle fibre and the red 

 muscle fibre were examined under the microscope. On teazing out 

 a piece of pink muscle one gradually lost the pink colour as the 

 pieces became smaller. The pink sheen could still be made out 

 with the naked eye in a piece of muscle 1 mm. in thickness. The 

 separate fibres were colourless. Only here and there among the 

 fibres was a portion of a capillary to be seen. It was made out by 

 the fact that it enclosed a few blood corpuscles. When the cor- 

 puscles are absent, the vessel is invisible. A few corpuscles 

 were made out : they were probably liberated when the fibres were 

 separated. Transverse striae may be seen in the fibre. In the 

 fibrillar are rows of little fat globules (fig. 111). The fibrils have 

 sheaths, and the oil globules are inside the sheaths. They may be 

 in the compartments into which the striae appear to divide the fibril. 



Now, the fibres of the bright red muscle are supplied with veiy 

 many capillaries (ca., fig. 106) filled with blood corpuscles. This 

 excessive quantity of blood gives, with the normal pink, a red colour 

 to the flesh. TJnder a high-power the corpuscles are yellowish- 

 amber or greenish in colour. The capillary appears to end blindly 

 in places : that is due to the absence of blood corpuscles at the part 

 and the probable contraction of the vessel. Many of the capillaries 

 have probably been ruptured. 



The effect of the injuries has been to cause the escape at certain 

 points of blood from vessels alongside the dorsal spines of the 

 vertebra?, also the suffusion with blood of the muscles in the 

 posterior half of the fish generally. How the latter has happened is 

 difficult to follow, unless it has resulted from the former. The 

 rupture of some veins may have interrupted the return of the blood 

 from the capillaries, which therefore remain distended. 



The injuries have not probably been recently done. They seem 

 to have been due to bites by a salmon. The aggressor had seized 

 the body of the other at the region of the fatty fin, and compressed 

 it dorso-ventrally. This would cause the rupture of the vessels 

 beside the dorsal spines. The sharp teeth of the salmon would 

 wound the fatty fin, and also the edge of the body behind the anal 

 fin. The injury in the region behind the first dorsal fin probably 

 resulted from a bite also. Owing to the fact that the wounds were 



