﻿Iii the following I shall call every fish mature (grown-up), when it must 

 he supposed to have spawned once (or several times), or is just spawning, 

 and ripe when it is spawning or at any rate is near spawning; a fish, 

 there/ore, cam become ripe several times in its life, even though it will not 

 become so every year after it has reached the mature stage of life. 



I speak distinctly of grown-up fishes, not of full-grown ones; for must 

 fishes, evidently, continue their growth after they have become ripe (and 

 thereby grown-up) for the first time. A glance at the table (I) will easily show 

 this. Differences between the various races, certainly, have some influence 

 on the size of the mature plaice, but that some specimens of them. 7 inches 

 long, should be full-grown, while others are not ripe till they are 22 Y 2 

 inches, nay. at Ireland even 2D or more (table IX), is most improbable. 



What we know, for instance, of the salmon is also contrary to the 

 supposition that all fishes must be full-grown when they spawn for the 

 first time. 



It seems that plaice, everywhere, generally become mature in their 

 third year, some already in their second, but, as a rule, they become 

 so with a smaller size in the Baltic than in the Belts, than in the Cattegat, 

 than in the Limfjord (and German Seal. The same thing has been proved 

 also on the shores of Great Britain, where Fulton, Cunningham, and Holt 

 have stated a corresponding difference in the length with which this fish 

 becomes mature at the various places, so it is not peculiar to our seas. 

 — We might think the reason of this was that plaice become ripe for 

 the first time at a different age, some two years old. others three. The age 

 certainly has some influence, but this cannot explain that, in our seas, it 

 is just in towards the Baltic Sea that the small ripe fish are found in the 

 greatest number. No, individual difference between the lengths attained by 

 the different individuals at their different ages must he. by far, the most 

 important condition for the understanding of the whole matter, which does 

 not exclude that also difference in age here may play a part. — Perhaps 

 we get nearest the truth by supposing that if the pelagic fry of the plaice in 

 their growing-period come under fortunate conditions (the northern Catte- 

 gat). then they will become large, if under less fortunate conditions (the 

 Belts), they will not become so large till they breed for the first time. They 

 may be compared to seed which is sown in good or less good soil; in the 

 former case the plants become large, in the latter small. It is. consequently 

 not necessary that there must be different races to explain the existence, at 

 certain regions, of smaller individuals, whether now these are plaice or plants. 



