156 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY 



latter method a certain amount of ovarian tissue is 

 estimated as ova, and a number of very small ova which 

 will not be spawned at the next spawning period are also 

 included. In two of Reibisch's estimations the weight 

 of the ovaries after complete spawning was T - 8 grins, and 

 18"3 grins. By employing this method Reibisch made a 

 large number of estimations, some of which are quoted 

 in the following: table : — 





Total length in 



Total weight in 



Total number of ova 





Cms. 



Grms. 



in the fish. 



1 



54 



1,770 



223,250 



2 



45 



969 



109,500 



3 



42 



1,100 



558,500 



4 



40-5 



693 



736,250 



5 



3S-5 



585 



250,750 



Reibisch did not count the very small eggs which are 

 always present in the ovary. If these had been included 



some cases, and this represents a degree of fecundity 

 certainly not attained by the plaice. Such very small 

 eggs he contends cannot ripen for the next spawning period. 

 All these results, and my own have the same tendency, 

 show, as Reibisch has observed, that there is no recog- 

 nisable relationship between the size or weight of the fish 

 and the number of eggs produced by it at the spawning 

 period. The age of the fish has in all cases to be consi- 

 dered. We know that the rate of growth is very variable. 

 Probably most plaice attain sexual maturity at the same 

 age, but the size and weight at this age may be very 

 different in a number of specimens. Thus a mature 

 female 13 inches long, and an immature female of 19 

 inches, have been taken from the Irish Sea. 



