QUEKETT MICROSCOPICAL CLUB. 101 



The scarcity of fish during the war was stated to be partially- 

 due to the over-fishing which had taken place previously, and 

 not entirely to submarines. It may possibly be better now, 

 but without legislation the inshore fisheries will again be 

 depleted. Experiments have been made with a view to finding, 

 a way of improving the fishing in the case of plaice. The 

 breeding places of these fish are inshore, and between the 

 Yorkshire ■ and Lincolnshire coasts and the Dogger Bank is a 

 deep valley which the fish do not crossuntil they are 10 or 11 inches 

 long. It was found that by transplanting 10-in. fish that had 

 been marked from the crowded breeding grounds to the better 

 feeding places on the Dogger Bank, and comparing them with 

 marked fish of the same size left in the nurseries, in the course 

 of nine months the transplanted specimens had increased 64: per 

 cent, in length and 360 per cent, in weight, as against 16 per 

 cent, increase in length and 59 per cent, in weight of the non- 

 transplanted fish. The fishermen took considerable interest 

 in the experiments, but made the objection that if the method 

 were adopted there was nothing to prevent fishermen from other 

 countries bordering the North Sea reaping the benefit of their 

 work. 



Mr. Martin Duncan then gave a brief account of the development 

 of a flat-fish, taking the flounder as an example. The young fish 

 is at first round and symmetrical, and lives in warm, shallow 

 water. Eventually it settles down, in the case of the plaice, on 

 its left side, and changes begin to take place. The body begins 

 to flatten, the left eye migrates until it almost touches the other, 

 the mouth is pulled to one side and the body becomes pigmented 

 on the right or upper side while the other remains white. If the 

 fish are kept in a glass-bottomed tank with a mirror under it, both 

 sides become pigmented. The monk or angel fish and the raya 

 are true symmetrical flat-fish. Their pigmentation shows 

 remarkable variation, according to the colouring of the sea 

 bottom where they live. 



Parental care is not much shown by fishes, but the pipe fishes, 

 to which family the sea-horses belong, are an exception. The male 

 has an incubatory pouch in which the young fish live, and when 

 they come out he protects them so far as he can from danger. 



The lecturer then described the two most accurate means of 

 determining the age of fish. If an otolith be examined against 



