PLANKTONIC STUDIES. 635 



CYCLE OF MATTER IN TRK OCEAN {Stofwcchsel des Meeres.) 



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

 the ocean furnishes to bioh)oy, the questions of tlie 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 benthonic and 

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

 the beginning of the epoch-making deep-sea investigation (1.3), 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 ( Vrnalirung). He believes this complicated question can be solved 

 especially by quantltatire determination of the fnnrla mental food supply. 



I have already shown why this method of quantitative plankton 

 analysis must be regarded i\s 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 sinirces of the " oceanic fun- 

 damental food sui)p]y" have already been correctly recognized by 

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

 the vast terrigenous masses of organic and i)articularly vegetable 

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

 ondly, the i)nmense 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., ^yhich grow in the coast waters. Only in recent times have we 

 learned to value the astonishing quantity of vegetable food which the 

 planktonic flora produces, the Fucoids of the Sargasso Sea on the one 

 side, the Oseillatoria' and the micioscopic Diatoms and Pendincce on 

 the other. But the smaller groups of pelagic Protojjhytes, which I have 

 mentioned above, the Chromaceie, Murracytew, Xanthelle(c, Bictyochece, 

 etc., also play an important role. Tlie great importance which devolves 

 upon the small symbiotic Xanthcllew, has been esi)ecially emphasized 

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

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

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

 Whether 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 pliysiological imi)ortance 

 would be the ascertainment of the rapidity of the increase. 



The importance of these Protopkytes and of the Protozoa living upon 

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

 has also rightly emphasized the extraordinary importance which the 

 vertical migration of the bathypelagic animals has for the support of the 

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



