HOEK— INTRODUCTORY — XX — 



long before the beginning of the international investigations. In Appendix D, the 

 Brandt's %vork present General Report publishes a paper b}' Prof. K. Brandt on the production 

 and conditions of production in the sea, which will assuredl}' contribute to the 

 elucidation of the phenomena connected with this theme. The main object of the 

 work reported on in his paper, was to improve the methods of determining quanti- 

 tatively very small amounts of nitrogen compounds, silicic acid and phosphoric acid, 

 so that trustworthy observations might be made on the vertical and horizontal 

 distribution of these food-stuffs and their dependence on the seasons. When we 

 remember, that it is these inorganic substances, which are at the disposal of the 

 marine plants in such small quantities, that they control the amount of the production 

 in the sea, further, that marine animals are dependent on plants for their existence, 

 nothing need be added to what has been said above to show the fundamental im- 

 portance of these investigations of Prof. Brandt. 

 Other biological Qthcr blological investigations — e. g. over the part played by the bacteria in 

 investigations ^^^ ^^^^ ^^ ^^^ occurrcuce and distribution of various plankton-animals (as Calanus 

 finmarchicus) which form the main constituents of the food of fishes, also experiments 

 to ascertain whether the fin-rays, vertebrae etc. of fishes vary when the eggs and 

 young are reared in waters of low salinity — have also been taken in hand, but 

 have not yet so far advanced, that the results can be published in this General 

 Report. It is hardly necessary to call attention to the great importance of these 

 biological investigations, even for the solution of fisheries problems. Just as the 

 physical and chemical investigations are preliminary to the study of the hydro- 

 graphical conditions, so the biological investigations and observations are necessary 

 for the just understanding of fisheries problems. Only when exact knowledge of 

 all the biological conditions and phenomena is to hand, will it be possible to form 

 a true and reliable picture of the occurrence, distribution and migrations of the 

 animals, and of man's influence on their abirndance. 



