PLANKTONIO STUDIES. 585 



iiicliule here a great imiuber of protista, wiiicli have liitlierto been 

 reckoned as protozoa, e. </., the Murracytca', Dicfijorhecv, PcHdinea'. 

 As characteristic and important protopliytes of tlie plankton I here 

 mention sevem groups: (1) Chromacew, (2) Calcoeytew, (3) Ilurracytew, 

 (4) Diafomea', (5) Xanfhellca', (0) Dicfyochea', (7) Pcridinea\ 



1. Chromaceiv (30, p. 452), — In this lowest vegetable group is probably 

 to be placed a number of small "unicellular algw" of simplest form, 

 which occur in great abundance in the plankton, but on account of 

 their minute size and simple spherical shape have for the most part 

 been overlooked, or possibly regarded as germ cells of other organisms. 

 They may here be provisionally distinguished as Frocytella primordialis. 

 The diameter of the spherical cells in the sinaller forms is only about 

 .001 to .005 mm., in the larger .008 to .012 mm, seldom more. Usually 

 each cell contains only one phytochrom granule of greenish color, 

 sometimes approaching a yellow or red, sometimes a blue or brown. 

 Whether there is also a diminutive nucleus is doubtful. Increase takes 

 place simply by division into two or four parts, and appears to go on 

 with excessive rapidity, but swarm spores do not appear to be formed. 

 Hundreds or thousands of such green spheres may be united in a mass 

 of jelly. The decision Avhether these simplest Chromacecv belong to the 

 Chlorcoccece or rrofococcea', or to some other primitive protophytic group, 

 fnust be left to the botanist for further investigation, as well as the 

 question whether these diminutive ProcytelUv are actually true nucleated 

 cells or only unuucleated cytodes. For our plankton studies these are 

 of interest only so far as they develop in astonishing quantities in many 

 (the colder) regions of the ocean, like the diatoms; and with the latter 

 form a great part of the fundamental food ( Urnahning). Over wide 

 areas the sea is often colored brown or green, and they form the chief 

 food (described as Protococeus niannus) of inconceivable myriads of 

 copepods, as Kiikenthal lias mentioiied in his " Contributions on the 

 Fauna of Sintzbergen." 



2. GaJcocytece. — In the eighth edition of the ^'- Naturliehe Schopfungs- 

 gescJiicJitc''^ (30, p. 437) I have designated as Calcocytcw or "unicellular 

 calcareous alga? " those important minute organisms which, as " Coo- 

 cos2)h(erc(, Cyathosphwra, and Rhahdospluvra, play a great role in oceanic 

 life. They are found abundantly in the plaidvton of the tropical and 

 subtropical seas, less abundantly in colder zones, and are never absent 

 where pelagic ThaJamophora occur in great numbers. Like the latter, 

 they arebathy])clagic. Theball of protoplasm which completely fills the 

 interior of the small calcareous-shelled plastid seems, when stained red 

 with carmine or brown with iodine, to be unuucleated, and therefore a 

 cytode. Tlie beautiful calcareous jjlates which compose the shell ( Cocco- 

 Utha, Cyatholitha, Bhahdolitha), and whi(;h in the Phahdonphcvra bear a 

 radial spine, fall apart after death and are found in great numbers in all 

 parts of the warmer oceans and in the globigerina ooze of the bottom. 

 Murray (5, p. 533; 0, p. 930) and Wyville Th<mipson (14, i, p. 222) 



