﻿fix than the maximum or minimum size; therefore we had better always 

 take all three sizes into consideration in order to avoid mistakes*). 



With regard to size the plaice from the seas about the Lesser 

 Belt, the Great Belt (see table II), and Grenaa, are between the plaice 

 from the northern and the eastern part of the Cattegat, on one side, and 

 those from the Baltic Sea, properly so called, on the other, the latter sup- 

 posed to commence east of Sealand, Meen, and Falster. Whether this is 

 simply because the favourable natural conditions, which may be supposed 

 to regulate the size of the plaice, are just arranged in such a gradual suc- 

 cession from the Cattegat to the Baltic Sea, as, evidently, they generally 

 are, or whether the said decrease in size is owing to a migration of the 

 plaice, as they groiv larger, from the Baltic Sea and the Belts to the Catte- 

 gat, I do not know for certain. There are good reasons, however, to think 

 that the plaice of the Baltic Sea generally pass their pelagic larval stage in 

 the Cattegat (or the Belts) and do not enter into the Baltic till they are about 

 one year old (see later on); therefore we can scarcely speak of a particular 

 race of plaice as a whole breeding, generation after generation, in the Baltic 

 Sea; at most the question will be 1) whether the single individual, which has 

 been born at another place, will remain in the Baltic Sea (or in the Belts) 

 through its whole life, without surpassing the size which is the normal 

 size here; or 2) whether the individual, when it approaches this size, goes 

 farther northward where the large plaice are found, and not till it is there 

 reaches a considerable size; or 3) whether both these processes may occur, 

 sometimes one, sometimes the other. — However this may be, it is remarkable 

 to see a great number of rather short fish becoming ripe in the Baltic 

 and the Belts (as far north as Grenaa), while such are rarer in the northern 

 part of the Cattegat (and the Limfjord). 



Are we to think, perhaps, that also other brackish waters than the 

 Baltic can check the growth of the plaice, and that, for instance, every 

 little brackish fjord, where the young fish go up too far, has the same 

 influence? This deserved a further examination, just as the immigration 

 of Pleuronectes flesus into fresh water. I have repeatedly ' touched this 

 question with respect to the lower annuals and the herring. (More about 

 this later on). 



That of our seas where the plaice grows to the largest size, before it 

 becomes ripe, is evidently the Limfjord (The German Sea has not been 

 investigated by Danes). (See table V, column 1—2). 



*-) It is a matter of course that mere exceptional or rare sizes are of no moment 

 with respect to this question. 



