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and the different velocity of these movements in the various regions of the sea. It is 

 evident that to give a quite exact and complete picture of these complicated conditions 

 would be a hard task, for which our present knowledge is, quite insufficient. For the 

 present we must be content with giving examples of a number ofcases, in which it 

 is possible and specially easy to indicate what happens from the moment 

 when the egg is spawned to the time when it completes its pelagic 

 existence. 



It is indeed obvious, that the difficulties in the way of following the newly spawned 

 egg in its development must be very different in the different cases. If, for example, we 

 have formed a picture of the spawning region of a certain species, it is naturally much 

 more difficult to determine the movements of the eggs within this region than to dis- 

 cover how far the boundaries for the occurrence of the newly spawned stages change. 

 The first task would namely require, either the determination of quantitative changes in 

 the distribution of the young stages within the spawning region, or even the possibility 

 of being able to follow the movements of the separate individuals ; neither of these can 

 however be carried out with accuracy for the time being. It is consequently also difficult, 

 to obtain really certain and precise information regarding the drift of the eggs and larval 

 stages from the Atlantic Ocean into the North Sea of the species which also spawn in 

 the North Sea, and yet this very probably plays a very great part in the economy of the 

 North Sea. 



As mentioned above, it is on the other hand much easier to gain certain knowledge 

 of the boundaries of the spawning places. It was through investigations of this kind 

 that we have come to the present results, and on comparing these with the observations 

 made by the hydrographers, especially through current measurements, the success was 

 obtained of being able to interpret the results in accordance with our knowledge of the 

 actual movements of the water. Of this we may give a few chosen examples. 



If first of all we regard the North Sea Bank as a separate region, for example, we 

 could cite numerous cases where the eggs spawned on this Bank fare distributed over other 

 regions. Whilst the eggs are quite restricted to the Bank itself at the spawning time in 

 spring, and no newly spawned gadoid eggs occur at this time over the Norwegian 

 Channel, in the Skager Rak or over the deep basin of the Norwegian Sea, in April — May 

 we find the small larvae distributed over the whole deep part of the Skager Rak, the 

 Norwegian Channel and in the Norwegian Sea. Thus a dispersion has occurred here, 

 which will be further discussed later. Considerable movements also take place however 

 within the North Sea Bank itself We have seen above, that numerous eggs of the cod 

 and whiting occur on the Dutch coast during the first months of the year (see fig. i8). 

 Later in spring these young stages decrease considerably in number, and in May, as the 

 Dutch investigations show, they have quite disappeared. Later, in July and August, we 

 find the small larvae in large quantities in the Northern North Sea, where on the other 

 hand the reproduction proceeds on a much smaller scale. We saw above that the cod 

 spawns on the east coast of Scotland in quantities; here also we find, that many of the 

 young stages of the cod are carried away from the spawning places in a southerly or 

 south-easterly direction. An important widening of the boundaries is shown, further, in 

 the movement of the small cod larvœ from the spawning places in the Southern North 

 Sea in towards the coasts of the German Bight. 



