﻿Iu the Limfjord, on the whole, ripe specimens are so rare that 

 I am inclined to think that the plaice, as a rule, does not spawn in this 

 fjord, but leaves it a short time before the spawning-period. There are 

 found specimens, however, with strongly developed sexual organs, but I 

 never saw them rnyself (or heard them described as) smaller than about 

 10 — 11 inches. (See table V). The stock of this fjord, which now presume- 

 ably ought to be looked upon as a » nursery « of German Sea plaice, seems 

 then to be very little mixed with early ripe specimens which are so com- 

 mon east of the Skaw. 



It cannot be denied then, that there is a great individual variation 

 (chiefly in the seas east of the Skaw) with regard to the size (length) with 

 which the plaice attain ripeness for the first time. To be sure, I could 

 not always decide with certainty, whether a plaice had spawned before but 

 just then restored its sexual organs since its last spawning- time , and thus 

 draw a boundary-line which would hold good for all individuals, be- 

 tween immature fishes (which have never spawned) and mature ones 

 (which are just spawning or have spawned before). 1 have been obliged 

 to content myself with drawing the boundary-line in or near the spawning- 

 season between »ripe«, i. e. actually spawning (or nearly spawning) fishes, 

 and »not ripe«, i. e. spent and immature ones, a boundary which during the 

 spawning-season, in broad features and at a certain place, must be very nearly 

 the same as the former, if it is drawn as a straight line, i. e. when it cuts 

 off all the exceptions. (See Cunningham; J. M. B. A., vol. II., p. 227 — 28). 



I admit that it would have been of some importance to be able to 

 decide this question: mature or immature, for instance in the Limfjord, 

 table V, column 1 & 2, in order to see whether these large fishes were 

 really immature iu the sense that they had never spawned, or whether they 

 only suffered this spawning-season to pass by, a question I am unable to 

 settle here with certainty. I take it for granted, however, that every plaice 

 does not spawn every year, even though it is a mature fish*). 



*) E. W. L. Holt: Rep. Brit. Assoc. 1892, p. 765—766, says, that it is always . 



to see whether a fish (i marine teleostean*) is mature or not, as its sexual organs 

 will not again be quite as they were Isefore they developed ripe spawn for the 

 first time. (As to the males nothing is said with certainty). I am inclined, be- 

 forehand, to think that Holt is right here, but I have not myself carried through 

 the matter practically; perhaps I shall be able to do so by renewed investigations. 

 Cunningham and Fulton, however, have not been able to do so. 



