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pigmented quite normally. In another plaice the process had 

 gone still further and, though the ulcerated cavity had not 

 completely filled up, the edges had smoothed down and the 

 pigmentation had, except for two small white spots, been 

 completely restored. This was on the coloured side of the fish : 

 on the colourless side was a patch of skin about an inch and a 

 half in diameter where there had been an ulcer. This was 

 level with the rest of the skin and of the same colour. In all 

 these cases of healing it is notable that there was no regeneration 

 of the scales. It would appear that, once destroyed in a fish, 

 these structures are not formed again. 



Often the first indications of the lesion are the apparent 

 swellings of the scales. Underneath a small patch of the latter 

 there is an obvious thickening, and the margins of the scales 

 become loosened so that their outlines are the more easily 

 seen. Each scale lies in a sort of dermal pocket and is covered 

 over with epidermis, and all these structures share in the 

 general disintegration of tissue which is the result of the 

 inflammatory process. 



On the whole, then, the sores are very obvious, very 

 familiar, in a kind of way, and are so repulsive that they are, 

 of course, sufficient to ensure the instant rejection of the fish 

 as an article of food. 



Sections were made of various parts of the ulcers, including 

 the edge, and other lesions where the surface was unbroken, 

 but where there was a region of inflammation beneath the 

 skin. Smears from the pus on the open sore were made and 

 stained, and these showed numerous bacteria, which had, of 

 course, infected the sore after the latter had been formed. 

 Staining of the sections so as to demonstrate the presence of 

 bacteria had very variable results : in some cases the latter 

 could not be detected. What was seen were only abundant 

 leucocytes, blood corpuscles, and broken-down tissue in 

 general. Round the margin of the ulcer there is a kind of ring 



