60 



ASTRID CLEVE-EULER, QUANTITATIVE PLANKTON RESEARCHES IN THE SKAGER RAK. 



Chaetoceras diadema is incomprehensible, if it be not meant to contribute to the floating- 

 power, af ter the spores have slipped out from the oid cell walls, and the species is, as is 

 well known, one utterly ready to spore-formation. 



Finally, a diagram of the frequency of Chaetoceras sociale, mostly present in spores, 

 will show the huge mäss of tliese spores floating at a middle horizon in the deep parts of 

 the Skager Rak. Downwards, the diagram continues for still some hundred of metres 

 as a regular asymptotic curve. 



Fig. 6. Chaetoceras sociale (the unbroken line) anil Leplocylindrus daiticns 

 (the broken line). S. Skag. 8. 25. IV. 1913. 



Fig. 7, finally, illustrates the various amount of diatomaceous crops, evaluated 

 in ind. per 1, at S. Extra II at different seäsons. 



100.000 200.000 300.000 



Fig. 7. Numbers of diatoms per 1 at S. Extra II. 



