Micrqplankton from t/w F/iuüs/i Wut ers duriiuj I/w Month of May 1912. 



35 



On account of the great supply of water from| land a nuinber of species of the 

 fresh water was found at this station. 



STATION F 50. 



This station bas a lo wer température and a higher salinity than station F 41. The 

 température decreases from 2,39° (0 mètres) to 0,14° (30 mètres), and then it inereases 

 towards deep water to 3,82" (75 mètres). The salinity inereases towards deep water 

 from 5,05 %o (P intres) to 9,16 °/oo (^^ mètres). Registrations of oxygen-tension are 

 only t "made in the depths of 50 mètres (73,4 u /o) an< i ?6 mètres (31,3 %). 



The tables show the average decrease of the plankton towards the deep water. 

 The sums of diatoms in the différent depths are placecl in the following table (table IV): 



'Table IV. St. F 50. Number of cells pr. litre. 



The table shows pretty equal distribution in the upper layers with the maximum 

 in the depth of 5 mètres. At this depth Gonyaulax catenata lias its greatest number too. 

 The chief-species were: 



Achnanthes taeniata without and with resting-spores. 

 Thalassiosira baltica 

 Gonyaulax catenata 

 Mesodinium rubrum. 



Achnanthes taeniata was further developed hère than at station F 41, in spite of 

 the température being lower. But the water of station F 50 being less nutritif than at 

 F 41, the formation of resting-spores lias begun earlier at station F 50 than at F 41. 



The resting-spores were far more numerous than the sporeless cells, especially in 

 the upper layers. This indicates that the formation of spores has begun very recently, 

 so that the sinking of the spores plays no part as yet. 



STATION F 61. 



Both the température and the salinity are somewhat higher than at the before- 

 mentioned station (F 50). The température, that of the surface being 3,19°, was de- 

 creasing to 0,73° in the depth of 50 mètres, and then it increased to 4,09° in the depth 



N;o 5 



