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i 

 the plaice and the duration of this season, about which I shall say that it 



extends over a very long time of the year, from November — April, both 

 months included, consequently over about half the year. 



On the 21. November 1893 great numbers of eggs of plaice with large 

 embryos were found floating in the water at Fasn0, and the number of eggs 

 is constantly increasing. (This is written in January 1894). 



In April 1892 eggs of plaice were still found at Feene, but in de- 

 creasing numbers. 



Everyone who knows pelagic eggs of fishes in our seas, will know 

 that the eggs of plaice are easily identified on account of their considerable 

 size (up. to 2 mm ) and other peculiar qualities, especially in the embryo, and I 

 find therefore this a more reliable way of determining the duration of the 

 spawning-season of this species of fish than a study of the ripe fish, which 

 are far more difficult to meet with in great numbers. (Cmp. Hensen's cal- 

 culations on the number of plaice in the Baltic Sea). It is a matter , of 

 course that the two methods supplement one another and in cam agree very 

 well, and I have got the impression that it is particulary in the months 

 of December — March that most plaice are spawning. — If then we will 

 state approximately the birth-time for the great mass of plaice, it may be 

 said to fall in the heart of the winter, and I have looked upon all the 

 little plaice of the 0-group as just passing into their completed first year 

 in the month of March. They are therefore in the tables marked I, while 

 they are marked through the whole preceding autumn. 



With the information that the spawning-season of the plaice lasts from 

 November — April, with a maximum in the heart of the winter, we shall 

 now return to the 0-group, which we found on the shores of the Cattegat 

 in the month of May and foUoved till November in the same year. 



It is astonishing that we do not find the young fry on the shores till 

 May, as some eggs at any rate are shed in November; for the hatching 

 of the eggs, in many cases, does not last long, judging from my examina- 

 tions of eggs which I have caught; but probaoly the duration is dependent, 

 to some degree, on the temperature. 



J. H. Fullarton: Ninth Ann. Rep. Fish Board. Scotland, p. 311. 

 1890, states that they are hatched after 16 — 18 days at 6°C. — The yolk- 

 sac was subsequently absorbed in the course of 12 days. 



While the larval fish have their yolk-sac, they are according to my 

 investigations c. 6 — 7 mm long, and when the yolk is absorbed and they 

 have grown somewhat unsymmetrical and compressed, with their left eye 

 sitting nearly on the edge of the brow, but while they are still transparent 



