PLANKTONIC STUDIES. 635 



CYCLE OF MATTER IN THE OCEAN {Stoffwcchscl des Meeres.) 



The many and great questions which the mighty cycle of matter in 

 the ocean furnishes to biology, the questions of the source of the fun- 

 damental food supply, of the reciprocal trophic relations of the marine 

 flora and fauna, of the conditions of support of tlie bentbonic and 

 planktonic organisms, etc., have, within the last twenty years, since 

 the beginning of the epoch-making deep-sea investigation (13), been 

 much discussed and have received very different answers (11). Hen- 

 sen has also devoted considerable attention to this, and particularly 

 emphasizes the physiological importance of the fundamental food sup- 

 ply ( Urnahrung). He believes this complicated question can be solved 

 esi)ecially by quant it at ice determination of the fiin(Jamcntal food stippli/. 



I have already shown why this method of quantitative plankton 

 analysis must be regarded as useless. Even assuming that it were 

 possible and practicable, I can not understand how it could lead to a 

 definite solution of this question. On the other hand, I might here 

 point to one side of the oceanic cycle of matter whose further pursuit 

 seems very profitable. The two chief sources of the "oceanic fun- 

 damental food supply" have already been correctly recognized by 

 Mobius (11), Wyville Thompson (13, 14), Murray (6), and others: First, 

 the vast terrigenous masses of organic and particularly vegetable 

 substances, which are daily brought by the rivers to the sea; sec- 

 ondly, the immense quantities of plant food which the marine flora 

 itself furnishes. Of the latter we previously had in mind chiefly the 

 benthonic littoral flora, the mighty forests of alga', meadows of Zostera, 

 etc., which grow in the coast waters. ;Only in recent times have we 

 learned to value the astonishing quantity of vegetable food which the 

 planktonic flora i^roduces, the Fiicoids of the Sargasso Sea on the one 

 side, the Oscillatoriw and the microscopic Diatoms and Peridinew on 

 the other. But the smaller groups of i^elagic Protophytes^ which I have 

 mentioned above, the Ghromacete^ Murracytecc, Xantliellece, Divtyochece, 

 etc., also play an importantTole. Tlie great importance which devolves 

 upon the small symbiotic XantJieUea\ has been especially emphasized 

 by Brandt (24), Moseley (7), and Geddes. Evidently their multiplica- 

 tion is extremely rapid, and if each second milliard of such Protophytes 

 were eaten by small animals, new milliards would take their places. 

 \Yli6ther or not the number of these milliards is shown to us by the 

 quantitative planktonic analysis seems to me wholly indifferent. More 

 important for the understanding of their j)hysiological importance 

 ■would be the ascertainment of the rapidity of the increase. 



The importance of these Protophytes and of the Protozoa living ujion 

 thein has lately been particularly described by Chun (28, pp. 10, 13). He 

 has also rightly emphasized the extraordinary importance which the 

 vertical m igration of the bathy])elagic animals has for the support of the 

 deep-sea animals. They are to a great extent the under workmen, who 



