SEA-FISHERIES LABORATORY. 



153 



• THE FECUNDITY OF THE PLAICE. 

 By E. D. Laurie. 



It may be useful to put on record two estimations 

 of the number of ova produced by a plaice, which I made 

 at Prof. Herdman's suggestion while working, during 

 last Easter vacation, at the Port Erin Biological 

 Station. The determinations were made by Dr. Fulton's 

 method,* in which a fractional portion of the roe (or 

 ovary) of the fish is weighed and the ova are counted, and 

 from the numbers so obtained, and the total weight of the 

 two ovaries, the total number of ova present is calculated. 

 No determinations of this kind have hitherto been made 

 from the fish in the Irish Sea. 



The fishes dealt with were two ripe mature females, 

 which died in the tanks at Port Erin during April, 190o. 

 The data are as follows : — 



Total length 

 (in centimetres). 



49 (19f inches) 

 52 (201 inches) 



Total weight 

 (in grammes). 



1,346 

 1,318 



Total weight of 

 both ovaries. 



3155 



181-5 



Small portions of the ovarian substance, weighing 10 

 grains each, were taken from various parts of the 

 organ, and the ova were counted. The results of these 

 counts are given in the following table : — 



9th An. Eeport Fish. Bd. for Scotland. Pt. III., pp. 243-268. 



