BARENTS SEA IN AUGUST, 1907. 81 



one fish, 57 era., the testis, about 2 mm, wide, was such as is found 

 in tlie immature condition, but tlie measurement is the largest in the 

 records for the sex. As regards tlie other seven fishes, no definite testis 

 could be traced. 



Whether this phenomenon was due to tlie lifelong sterility of the 

 individuals, or to the fact that sterility had supervened on account of 

 the great age to which they must have survived, is an interesting 

 biological question which must for the present remain open. 



Having made an extensive examination of spawning plaice in the 

 southern parts of the North Sea in the spawning season (January- 

 February) this year (1907), I received the distinct impression that the 

 quantity of spermatic fluid and unextruded dead ova was far greater in 

 the Barents Sea fish than in those of the southern region. It would be 

 interesting if investigation should prove this to be actually the case. 



No females actually spawning or about to spawn were found, and it 

 will be seen from the summary of measurements that the number of 

 immature fish of both sexes was very small, particularly in the case of 

 the males. 



It is interesting to find that the greatest number of immature 

 occurred in the haul across the shoalest part of the bank (26 fms.) 

 at the end of the first day's fishing. The catch then consisted of 

 eighteen baskets of plaice, of which four were measured. These con- 

 tained 183 fish (73 males, 110 females). Of the males, 7, or 9| per 

 cent, were definitely immature; and 11, or 15 per cent, recorded as 

 doubtful. Of the females, 24, or 22 per cent, were immature ; and 5, 

 or 4|- per cent, doubtful. Thus, of the fish in this sample, 18 males, or 

 25 per cent, and 29 females, or 26 per cent were possibly immature. 

 Taking all the other stations, and classing the immature and doubtful 

 fish together in the same way as " possibly immature," I find only 

 about 3 per cent of the males, and 16 per cent of the females wo^ld 

 fall into that category. 



Asa result of the international investigations in progress, we know 

 that the same phenomenon, viz. an excess in the proportions of 

 immature females compared with that of immature males, also obtains 

 on the central grounds of the North Sea at a similar period. 



The length of the smallest mature male was 24 cm., and of the 

 smallest mature female, 35 cm. The largest immature female was 

 45 cm. The largest immature male was recorded as 41 cm., but this 

 record is rendered open to doubt by the curious condition of the eight 

 males recorded above. The average size of the mature males is 

 40"9 cm., and of the mature females, 48'3 cm. 



