PLANKTONIC STUDIES. 635 
CYCLE OF MATTER IN THE OCEAN (Stoffwechsel des Mceres.) 
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 the benthonic 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 
especially by quantitative determination of the fundamental food supply. 
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 alge, meadows of Zostera, 
ete., 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 produces, the Fucoids of the Sargasso Sea on the one 
side, the Oscillatoriw and the microscopic Diatoms and Peridinee on 
the other. But thesmaller groups of pelagic Protophytes, which have 
mentioned above, the Chromacee, Murracytee, Xanthellew, Dictyochee, 
ete., also play an important rdle. The great importance which devolves 
upon the small symbiotic Xanthellec, 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 smali 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 physiological importance 
would be the ascertainment of the rapidity of the increase. 
The importance of these Protophytes 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 
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