SEA-FISHERIES LABORATORY. 287 



" slinks," and in several cases there was extreme emaciation. 

 This was especially characteristic of one of the plaice — where, 

 however, there was healing of the ulcerated sores. In some 

 of the cod the emaciation, particularly on the head and 

 shoulders, was very great. In two cod there were other 

 malformations, a shortening of the length of the fish relative 

 to its girth. This was due to a twisting of the backbone, the 

 latter having a slightly spiral shape. 



The general appearance of the ulcers is, of course, highly 

 variable. Sometimes they are little more than inflamed spots 

 on the skin, but as a rule there is complete destruction of the 

 latter over a greater or less area. When this occurs there is 

 a typical " sore," the boundary of the ulcer being rather 

 sharply marked and its floor being formed by the underlying 

 body muscles, the skin being completely destroyed. Thus 

 there is a shallow cavity of irregular shape, partially filled with 

 pus and products of necrosis, including much blood. The 

 ulcer is never very deep, though occasionally there are small 

 pits going down into the muscles. Generally the edges are 

 highly inflamed, and the inflammation often extends over the 

 whole floor of the shallow cavity, though sometimes the colour 

 of the latter may be yellow-white. Beneath and round the 

 eroded area there is always a margin of inflamed skin or 

 muscular tissue. 



In the plaice examples all stages of healing were observed. 

 One fish was very greatly emaciated, the skin, in some places, 

 " clinging to the bones." There was an ulcer of about 3 inches 

 in diameter on the coloured side, but the greater part of this 

 had healed over and there had been regeneration of tissue. 

 Near the centre were the remains of the ulcer, as a cavity 

 about an inch in diameter, at the bottom of which several 

 vertebrae, with their haemal species, only very lightly covered 

 with colourless connective tissue. The whole area was thus 

 skinned over, and the greater part of this new shin was 



