THE NANNOPLANKTON OF BOMB-CRATER POOLS. 235
evidence, partly, no doubt, because the centrifuging was not
carried out long enough or vigorously enough to precipitate
these exceptionally small forms in great numbers. Occasionally
however, they were abundant and included many motile forms.
No attempt was made to deal with these organisms by bacterio-
logical methods and it is therefore not possible to say more than
that species of the following genera were noted :—Beggiatoa
(probably B. minima), Bacillus, Micrococcus, Spirillum, Spiro-
chaeta and ? Thiocystis.
Fungi.
The chief forms of fungi to be found in the nannoplankton
anywhere are yeasts, spores of many kinds, and small pieces of
hyphae of usually indeterminate origin. Zoospores of Chytrids
(Fig. 7) also occur occasionally, but were not seen from any of
the bomb-crater pools. No attempt was made to identify any
of the forms seen.