244 
PACIFIC SCIENCE, Vol. XX, April 1966 
ED- 1 
Fig. 3. Vertical section at right angles to the coast line in about 162°W, between stations Ed— 1 and Ed— 2 
showing distribution of oxygen in ml/L. 
mass. But plankton would, nonetheless, be swept 
past it in all layers. However, the diatom T. 
arcticum is found only on the bottom and no- 
where else in the water column. 
According to Hendy (1937) many speci- 
mens of T. arcticum spend most of the time as 
bottom forms and seldom get into the plankton. 
At several stations in Vincennes Bay the author 
found many on the bottom and none in the 
plankton. Hendy also mentions that many speci- 
mens are epiphytic on algae. How then can 
this plant fix carbon in the absence of radiant 
energy? 
The fact that algae which appear to be de- 
composing are found in association with T. 
arcticum suggests the possibility of sapro- 
phytic nutrition. According to Kudo ( 1954) or- 
ganisms ( for example, Euglena gracilis and 
Chilomonas paramecium) receive saprophytic 
nutrition by diffusion through the body surface. 
This is accomplished without any organellae. 
There is only one known exception — marine 
dinoflagellates — in which saprophytic nutrition 
is accomplished through a special organella. Ac- 
cording to Dr. E. W. Putman 3 (conversation), 
3 Chairman, Department of Plant Physiology, Uni- 
versity of Hawaii. 
T. arcticum may well be a saprophyte when not 
photosynthesizing. 
An interesting by-product of this investiga- 
tion is shown in Figure 3- The high content 
of oxygen in the surface layers is probably 
due to the abundant population of holophytic 
organisms. 
CONCLUSIONS 
The circulation pattern off the Ross Ice Shelf 
is nearly identical with that found by Sverdrup 
(1953^) to exist off the shelf ice of Queen Maud 
Land. 
It is obvious to anyone interested in plankton 
ecology that organisms at subeuphotic depths 
cannot fix carbon and cannot be holophytic. 
Hence, Trigonium arcticum, under the condi- 
tions in which it was found, cannot fix carbon 
and be holophytic. This fact has been known at 
least since 1937 (Hendy). Still, no attempt has 
been made to explain how such plants do man- 
age to live in virtual extinction of visible radia- 
tion. It is likely, then, that this diatom, and 
possibly others, may be capable of using chem- 
ical energy derived from decaying algae as a 
means of nutrition. 
