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maximum 35,3 °'„„ and 9° 

 minimum 35 °/^^ and 6° 



Ail the other forms spawn chiefly or exclusively on the Atlantic deep-sea margin; 

 nevertheless, many differences also occur very probably in the temperatures at which 

 they spawn. 



Molva eloitgata is the species which has its northern boundary furthest to the 

 south; it disappears already at the Irish plateau, and its minimum temperature must there- 

 fore be placed at approximately 9°. 



The three remaining species, Molva byrkelange, Gadus poutassou and Gadiculus 

 argentans all go as far as the Iceland Bank, Molva byrke lange the furthest north (on 

 the west coast of Iceland). As both of the other species go far south, their maximum 

 temperature cannot be given; their minimum temperature must lie however between 

 6° and 8°. In agreement with this we have the very interesting fact, that the two species 

 Molva byrkelange and Gadiculus argenteîis spawn in deep Norwegian fjords, where 

 they find in deep water the same temperature as in their most northerly spawning place, 

 namely, the Atlantic deep-sea margin. 



III. The Distribution of the pelagic Larvae and young Fishes 

 and their Conditions of Life 



The investigations of recent years have yielded a number of new facts regarding the 

 ability of the water masses to distribute the eggs and to carry them more or less far 

 away from the spots where they were spawned. 



This dispersion of the eggs is however dependent on many conditions of various 

 kinds. The spawning time of the fishes is above all a determinative factor in this 

 connection. Since the rapidity with which the egg develops is in high degree dependent 

 on the temperature of the surrounding water, all the forms which spawn in the summer 

 have a much shorter larval and purely passive developmental stage with shorter depend- 

 ence on the oceanic currents. With this agrees the fact that a long drift has not been 

 found in the case of the eggs of bottom forms which spawn in summer, but only in the 

 pelagic summer forms. On the other side the spawning time may also be of great im- 

 portance owing to the fact that the movements of the oceanic currents may be quite 

 different during the different seasons. The specific gravity of the eggs is also an 

 important matter, and many observations are to hand which show that the eggs and even 

 more the larvas of the different species behave differently in the same water masses. 

 Whilst for example the eggs of the whiting and cod are to be found in the upper 

 water layers, the haddock eggs mostly occur in the deeper layers and the eggs of such 

 fishes as the halibut, Macrmus and Argentina are only found in great depths. 



The larvae differ still more in this connection. Thus, for example, such forms as 

 Gadus Esmarkii, the ling and the torsk in the North Sea very early seek the deeper 

 layers, the whiting and coalfish only in more advanced stages. 



These biological conditions give us already some notion of how very complicated 

 the question of the passive movements of Ihe pelagic stages under the influence of the 

 currents really is, and how it assumes a different form in each species. In addition to 

 these we have also the physical conditions, the movements of the different water layers 



