CRUISES OF THE "MICHAEL SARS " 117 



At Station 80 we became aware of the influence of Atlantic 

 water, and at the same time we got clear weather, but, as the 

 figure will show, it was at Station 81 that we first met with the 

 real Atlantic or Gulf Stream water with a salinity of about 35.5 

 per thousand, which extended in a layer 100-200 metres deep 

 right across to near the coast bank outside Ireland. Below 

 this layer the salinity and temperature decrease till we come 

 down to bottom-water, with a salinity of less than 35 per 

 thousand ; the temperature was the same as what we had found 

 in bottom-water to the south of the Azores, namely, a little 

 under 2^° C. Our investigations made it apparent that this 

 bottom-water is in continuity with the surface water in the 

 north-west corner of the Atlantic. 



Our investigation of the plants of the sea was continued Plants. 

 during this cruise ; we made collections with silk nets, and 

 centrifuged water - samples with the big steam centrifuge, 

 with the result that, in spite of high seas and heavy rolling of 

 the vessel on the eastern side of the ocean, Gran was able to 

 proceed with his classification and enumeration of the minute 

 living organisms that had hitherto eluded observation. 



At almost every station he determined the number of 

 extremely small organisms, chiefly coccolithophoridse, per litre 

 of sea-water, and ascertained that here, too, on our northerly 

 route they constituted the greater portion of the plant plankton. 

 An exception must, however, be made in the case of the coast 

 banks of Newfoundland and Ireland, where there was also a 

 very abundant plankton of larger organisms, large enough to 

 be retained by the tow-nets. One single species (a calcareous 

 flagellate) at a station just outside the European coast bank 

 numbered 200,000 per litre, and actually affected the transparency 

 of the sea. 



Gran succeeded in collecting abundant material for the 

 study of these little-known forms (many of them new to science), 

 and for a proper understanding of their significance in the total 

 plant life of the sea. In Chapter VI. he has set down the 

 chief results of his observations. 



We found again a complete accordance between the distri- 

 bution of the different water-masses and the occurrence of 

 characteristic "societies" of pelagic animal life. At Stations Pelagic life of 

 75-79 on the Newfoundland Bank (see Fig. 94) the boreal l^^^;^^ 

 organisms were mixed with arctic forms. Thus there were : 



