216 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the upper water layers, they will be largely dependent on 

 currents. After they have grown larger they also to a 

 very great extent take refuge under jellyfish and follow 

 their drift. 



No investigator, wishful of forming an unprejudiced 

 opinion, can justly ignore the possibility that the eggs and 

 young of the cod during this relatively long space of 

 time, while they are leading a pelagic life in the waters 

 of the sea, may, and under certain circumstances un- 

 doubtedly must, be subject to the movements of the waters 

 and dependent on these as to their fate. 



If we should endeavour to propagate the plants of a 

 field with seed which floated in the air for a couple of 

 months, surely we would have to consider the currents of 

 the air. It is thus obvious that an understanding of the 

 hydrographical changes in the fiords and their effects on 

 the larvae is essential for the solution of the problem. 

 The eggs and larvae live, according to my material, 

 chiefly in water between 20 and 30 per thousand salinity ; 

 such as the relatively fresh surface water, which covers 

 the salter water of the Skagerrak and fills the upper layers 

 in the Skagerrak fiords. Eggs and larvae are distri- 

 buted from about 20 metres and upwards in numbers 

 which generally diminish towards the surface, but occur 

 in the different depths in about the same relation to each 

 other. Thus the larvae do not float lower than the eggs. 



By experiments undertaken by Mr. Dannevig and 

 me in the Flodevigen hatchery the recently spawned eggs 

 and newly hatched larvae were all found to float at the 

 surface of water of a density (i.e., specific gravity in situ) 

 of 1,021 and in water of less density they floated or sank 

 in the same proportion to each other. Direct current 

 measurements have shown that this water-layer which 

 contains the eggs and larvae moves as well in as out of 



