23 



tainly seems that tlie interacHon of the waler and tlie hottom of the sen is alone 

 sufficieut to produce this denser plankton, a supposition whieli, when \ve thiuk 

 of the special growtli and propagation of the diatomaceæ, is perhaps not quite 

 impossible eitlier. — 



During these plankton studies a number of questions have crowded upon 

 me, for the solution of which I still want the necessary information, such as: 

 Are masses of fisheggs carried from the North Sea iuto the Cattegat, and is 

 it in this way that the plaice is preserved in tlie Cattegat in spite of the over- 

 fishing? Which of our seas produces the greatest quantity of plankton per D 

 mile a year? Have our other fjords an Indepcndeut diatom-flora like that of 

 the Limfjord? Has the unequal density of the plankton of the Limfjord in the 

 various years auy perceptible influence on the sustenance of the stock of fishV 

 Befoi'e these and similar questions can be solved, the plankton investigations 

 must be carried on far more rationally, in all our seas and at all seasons, than 

 it has hitherto been possible for me to do. 



Mftp of the Limfjord with the Stations 1—11. 



