PLANKTONIC STUDIES. 589 
the greenish-yellow pigment granules in the protoplasm of the Dic- 
tyochide are chlorophyll or phytochrom, they must be placed with 
“unicellular algw.” If, as I believe, the supposition of Borgert is cor- 
rect, then the masses of Dictyochide shells found so abundantly in 
the calymma of Phwodarie can be regarded only as the empty shells 
of Silicoflagellata, which the skeletonless Pheodina has taken in as food. 
This supposition is much more probable since these, together with sili- 
eeous scales of diatoms and tintinnoids, have been found in great num- 
bers in the calymma of other radiolarians. This case would then be 
analogous to two similar appearances which I myself have previously 
described, Myxobrachia pluteus (4, p. 22) and Dalearomma calearea (4, 
p. 70, § 102). 
7. Peridinee (Dinoflagellata or Dinocytea, earlier Cilioflagellata).— 
This group of Flagellata (or Mastigophora) earlier placed with the In- 
fusoria, has lately, with more certainty, been recognized as a proto- 
phytic group with vegetable metabolism. They are represented in the 
plankton by numerous and, in part, remarkable and beautiful forms, 
a part of which have been lately figured by Stein under the name 
Arthrodele flagellata. Many such forms occur in the neritic, fewer in 
the oceanic plankton, and often in such masses that they take a great 
part in the formation of the fundamental food supply. Hensen cor- 
rectly points out the great importance of these Protista, of whose 
quantity he attempted to give a conception by counting (9, p. 71). 
Many of these participate in a prominent way in the marine popula- 
tion (Ceratium, Prorocentrum, etc.). John Murray very often found 
chains of Ceratium tripus (each composed of eight cells) floating in the 
plankton of the open ocean, without ciliary movements, while the 
ciliated single cells inhabited the neritic plankton in vast numbers 
close to the shore. Sometimes these crowds of Peridinea, like the 
diatoms, appeared so abundantly as to fill the tow net with a yellow 
slime (6, p. 934). ; 
B.—METAPHYTES OF THE PLANKTON. 
The only class of metaphytes which occurs in the plankton are the 
alge. The great majority of this class, so rich in forms, belong to 
the littoral benthos; only a few forms have adopted the pelagic mode 
of life, and of these only two, from their great abundance, are of any 
considerable importance in the oceanic fundamental food supply, the 
Oscillatorie which live in the depths, and the Sargassa which grow at 
the surface. A third group, the Halospherea, is much less abundant 
and important, but of considerable interest in many relations.* 
«The Oscillatoriw must be regarded as true alge, since their characteristic “jointed 
threads” (‘‘ Glieder-faden”) form an actual Thallus, and indeed a thread-like thallus, 
as in the Conferve. But on the same grounds also we must regard as alge the Volvo- 
cinew and Halospheree with spherical thallus ; they are also multicellular Metaphytes, 
which show the simplest form of tissue (Histones, 30, p. 420). The foregoing proto- 
types, on the other hand, have no tissue, since the entire organism is only a simple 
cell (Protista, 30, p. 453). 
