=16= 
for this group of radioelements. This observation is in 
agreement with the findings of the Taney survey (10) in 
which the major fission products in plankton were found to 
be Celt4_ppl4t4 | However, & gamma spectrum curve made on 
these plankton samples November 1957 by the present author 
revealed an appreciable amount of CoS0, zr95-Nb95 were not 
found in the Taney samples because of the short half life of 
Zr95 (65d). 
In the case of the non-fission-product radioelements, 
zinc, cobalt, and iron were present in the plankton (based 
on an average of the five samples) in approximately equal 
amounts at about 24 per cent each and manganese at a level 
of less than one per cent of the other three elements. All 
of these elements, from fallout in the sea, would exist 
initially in the insoluble form. 
Limited data from both control experiments (4) and 
field observations (21) suggest that the major route for up- 
take of fallout radioisotopes by marine animals is through 
the ingestion of radioactive particles. Chipman (5) noted 
also that, in addition to the filter feeding animals, two 
species of algae were able to concentrate Cel44 several 
thousand times over the levels in the water although the 
radioisotope was in the particulate form. The present work 
is in agreement with the postulate that the major source of 
radioactive elements from fallout to marine zooplankton is 
through the uptake of particulate material. The uptake may 
