PLANKTONIC STUDIES. 689 



the greenish-yellow pigment granules in the protoplasm of the Die- 

 tyochida' are chlorophyll or phytochrom, they must be placed with 

 "unicellular alga^." If, as I believe, the supposition of Borgert is cor- 

 rect, then the masses of DictyocUdw shells found so abundantly in 

 the calymma of Ph(codaricv can be regarded only as the empty shells 

 of Silicqfiafiellata, which the skeletonlessP//ft'o^7/?ia has taken in as food. 

 This supposition is much more probable since these, together with sili- 

 ceous 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, My.vobrachia pliiteiis (4, p. 22) and Dalcaromma calcarea (4, 

 p. 70, § 102). 



7. Peridinece {Dinoflaficllata or Binoeytea, earlier Gdioflagellafa).— 

 This group of Flagellata (or Masfifjophora) 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. Henseu cor- 

 rectly points out the great importance of these Frotista, of whose 

 quantity he attempted to give a conception by counting (9, p. 73). 

 Many of these participate in a prominent way in the marine popula- 

 tion (Ce>v^^^^m, Prorocentrum, etc.). John Murray very often found 

 chains of Ceratmm tripuH (each composed of eight cells) floating in the 

 plankton of the open ocean, without ciliary movements, while the 

 ciliated single cells inhalnted the neritic plankton in vast numbers 

 close to the shore. Sometimes these crowds of Peridinew, like the 

 diatoms, appeared so abundantly as to till the tow net with a yellow 

 slime (G, p. 934). 



I?. — METArUYTES OF THE PlANKTOX. 



The only class of metaphytes which occurs in the plankton are the 

 alga^. 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 

 Oscillatorkc which live in the depths, and the /Sarfiassa which grow at 

 the surface. A third group, the Halosphwrea', is much less abundant 

 and important, but of considerable interest in many relations.* 



*The OscUlalorkv must be regarded as true algi«, since their characteristic "jointed 

 threads" {" Glicdcr-faden") form an actual ThaUm^. and indeed a thread-like thallus, 

 as iu the Conferva-. But on the same grounds also we must regard as algw the Volvo- 

 cinea and Halosplurrew with spherical thallus ; they are also multicellular Meiaphytts, 

 which show the simplest form of tissue (Hhfone.9, 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), 



