l895- No. 9. HYDR.-BIOL. STUDIES OF THE XORW. FISHERIES. 6"] 



the most exact accounts of the movements of the fish, for subsequetit 

 a7id thorough revision. What knowledge would we not now have 

 had of the wandering of the Herring, if, from the old years of 

 plenty until now, there had been collected, each year, such varied 

 materials.^ At the close of this chapter I shall take the liberty of re- 

 ferring to this. 



The Herring, the Cod and the Mackerel besides passing their lives 

 during the migrations under the coast, li\"e there, too, when eggs, fri- 

 and }oung fish. I stated that the eggs of the Cod and Mackerel were 

 spawned freel}- in the sea, w^hilst those of the herring are attached to 

 the bottom — and there pass through the first phase of development. 

 From the ver}" first, the eggs of the Cod and Mackerel are thus at the 

 mercy of the surface currents, and from Sars Report we see how the\- 

 are drifted about b}" wind and weather, at one moment packed into 

 bays and sounds, at another driven out to sea. During the time I 

 spent at the Spring Herring Fisher}-, February and March i8g4, I suc- 

 ceeded in studying the development of the Herring. As the eggs of 

 the Herring are stick}', and therefore adhere to ever}-thing the}- touch, 

 I let the ripe eggs run from the female into large, wide, glass cylinders. 

 The eggs, at once, adhered to the side and bottom of the glass, and 

 were fructified b}- letting a drop of the male's milt fall into the vessel 

 which was filled with sea-water, almost all the eggs, as a rule, being 

 fertihzed thereby. I studied then further development by fastening the 

 glass, b}- means of a line, to a floating barrel which was anchored to 

 the bottom. The glasses thus moved about freel}' in the water, and 

 I was enabled to draw them up each da}', and obtain eggs at am' 

 period of development I wished. It appeared that the eggs (under the 

 stated h}'drographical conditions^ became developed to fr}', of a length 

 of 10 mm. each in the course of 21 to 22 da}'S. Boeck states that the 

 development requires 24 days. It depends, as is knowai, on the tem- 

 perature ^. After that period, in the month of March, I often found 

 the fr}' of the Herring swimming freely in the Plankton (but always in 

 ver}' few numbers). 



1 See Lilljeborg: Sveriges och Norges Fiskar. 1S91. (The Fishes of Sweden and 

 Norway). 



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