82 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Rays, Cod and Halibut. They are, probably, no less 

 uncommon in other edible sea fishes, but the above species 

 are large and fairly valuable fish, and more attention is 

 naturally paid to them. In speaking of "malignancy," 

 one means rather less than he would in referring to the 

 malignancy of human affections. In a fish suffering from 

 a tumour there is nothing in the nature of a " clinical 

 history," and it would be very difficult to make any really 

 gpod experiments with the object of investigating the 

 effects on metabolism, or general health, or bodily 

 functioning, of the presence of a progressive tumour. 

 One can only investigate the morbid anatomy and Gompare 

 this with human pathological conditions. It is difficult 

 also to be sure whether or not a tumour has any effect on 

 the health of the fish in which it occurs. There are 

 indications of normality or abnormality of functioning in 

 what one, rather vaguely, calls the "condition" of the 

 animal. There may be great emaciation, or the lack of 

 maturation of ovaries or testes ; the flesh may be thin and 

 watery, and tasteless if cooked ; there may be a poorness 

 in fat if the fish is one which, like the Halibut, 

 Salmonidae or Clupeidae, is rich in fat at certain seasons 

 of the year; or there may be a large deviation from the 

 average weight which one regards as characteristic of 

 fishes of various sizes and at different seasons of the year. 

 Usually one can say whether or not a fish is "in good 

 condition," meaning by that whether it has been well fed 

 or not; but that is all that is to be said as to the general 

 health of the animal. Post-mortem examination accom- 

 panied by detailed microscopic investigation may show 

 whether or not internal organs are diseased, but we do 

 not know enough about the naked-eye appearance of these 

 organs to say at once whether they are normal or 

 abnormal. Fishermen, who are very observant, take 



