198 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
found with the initials of some fisher-lad, or sporting 
yachtsman, scored with a knife on the side. Such wounds 
form clean, not very conspicuous, scars, healing perfectly. 
Sometimes a fairly large piece of the body of the fish, 
along the back, or along the ventral side, behind the 
anus, may be bitten out cleanly by some other fish. In 
such a case a clean healed surface is formed. Even such 
comparatively delicate fish as the whiting, haddock, or 
mackerel, are occasionally found with a rubber band, or 
ring, sprung on to the body behind the gills. This 
causes a constriction from the continual pressure of the 
rubber band, but the skin is seldom damaged.  Plaice 
and flounders are often caught with split tails and fins, 
sometimes perfectly healed. Even when these injuries 
result from the handling of plaice or flounders in the 
trawl net, and when the fishes are kept in aquaria, the 
injuries heal. It is usually in the cases of fishes like the 
sole and dab, which possess strongly ctenoid scales, that 
injuries to the skin are lkely to prove of a serious or 
fatal nature. Probably a sole cannot afford to have even 
a comparatively small area of skin rubbed bare of scales ; 
in such a case the fish usually dies. 
The adventitious tissue present in the skin and core 
of the growth described above, consists, then, of granula- 
tion tissue produced to fill up and heal a fairly 
considerable cavity resulting from some mechanically 
caused injury. The very striking annular area of pigment 
round the growth is the result of an inflammatory process. 
There is always black (and red) pigment in the skin of 
the plaice, and the former has been produced in 
abnormally great quantity as the result of the increased 
blood supply in the region of the healing wound. The 
conclusion follows, of course, that we have not to deal 
here with a tumour properly so-called, either benign or 
malignant. 
