584 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
IV.—_SUMMARY OF THE PLANKTONIC ORGANISMS. 
A.—PROTOPITYTES OF THE PLANKTON. 
The unicellular plants ( Protophyta*) lave very great importance 
in the physiology of the plankton and the cycle of matter in the 
sea (Stoffwechsel des Meeres), for they furnish by far the greater part — 
of the fundamental food ( Urnahrung). The inconceivable amount of 
food which the countless myriads of swimming marine animals consume 
daily is chiefly derived, directly or indirectly, from the planktonic flora, 
and in this the unicellular protophytes are of much greater importance 
than the multicellular metaphytes. Nevertheless the natural history 
of these small plants has thus far been very much neglected. As yet 
no botanist has attempted to consider the planktonic flora in general, 
and its relation to the planktonic fauna. Only that single class, so rich 
in forms, the diatoms, has been thoroughly investigated and systemat- 
ically worked up; as regards the other groups, not a single attempt at 
systemization has been made; and many simple forms of great impor- 
tance have lately been recognized for the first time as unicellular plants. 
I must, therefore, limit myself here to a brief enumeration of the most 
important groups of the plankton flora. Its general extent and quanti- 
tative development have in my opinion hitherto been much under- 
valued, and with reference to the cycle of matter in the sea (Stoffwechsel 
des Meeres) deserve a thorough consideration. I find masses of various 
protophytes everywhere in the plankton, and suspect that they have 
been neglected chiefly because of their small size and inconspicuous 
form. Many of these, indeed, have been regarded as protozoa or as 
eges of planktonic metazoa. 
As a foundation for a most important province of botany, the classi- 
fication of the protophytes, we must keep in the foreground the follow- 
ing considerations: (1) The kind of reproduction, whether by simple 
division (Schizophyta) into two, four, or many parts, or by formation 
of motile swarm-spores, Mastigophyta; (2) the constitution of the phy- 
tochroms, of yellow, red, or brown pigment, which is distributed in the 
protoplasm of the cell (usually in the form of granules), and has great 
Significance in assimilation (chlorophyll, diatomin, erethrin, pheodin, 
etc.); (3) the morphological and chemical constitution of the cell-mem- 
brane (cellulose, siliceous, capsular, or bivalvular, ete.). So long as we 
hold to the present view of the vegetable physiologists, that for the 
fundamental process of vegetal assimilation, for the synthesis of proto- 
plasm and amylum, the presence of the vegetal pigment matter is neec- 
essary, we can regard as true protophytes only such unicellular organ- 
isms as are provided with such a phytochrom, but we will have to 
*The separation of the Protophyta from the Metaphyta is as justifiable as that of the 
Protozoa from the Metazoa. The latter form tissues, the former do not. (Compare 
Natur). Schépfungsgeschichte, vii Aufi., 1889, pp. 420-453. ) 
