of the difficulty in determining the 

 activity of an extract of such a low 

 specific activity, and because no 

 replication of the plating was made, this 

 result was only considered preliminary. 

 It served to establish the range of activity 

 to be expected in two further experiments. 



The next experiment was performed at Station 

 S-9 in the Central American thermal anticline 

 80 miles off Costa Rica (9°28' N latitude, 

 89 e l8' W longitude) on November 21, 1956. 

 Sixteen 250-ml . bottles of surface sea water 

 were incubated with 2,887,000 cpm. of C lk per 

 bottle for eight hours, and at 1200-1^00 f c . 

 and 25°C. After incubation the contents were 

 pooled in a plastic bucket, and 250 ml. of 

 this pool were immediately filtered through a 

 Millipore filter (MP-1-1) to determine the total 

 activity fixed. Then 1750 ml. were filtered 

 through an F-porosity sintered-glass filter 

 (maximum pore size 5 u). Two 250-ml. portions 

 Of the filtrate from this last filtration were 

 then filtered through Millipore filters 

 (MP-1-2 and MP-1-3) to determine the portion 

 of the activity not retained by the glass 

 filter. The residue on the filter was 

 washed twice with non-radioactive sea water 

 and then was extracted four times with 

 boiling 80°/,, ethanol. The combined extracts 

 were dried with a hot-air stream at 35°C and 

 then taken up in 7.5 ml. of twice-distilled 

 water to yield extract E-l. This whole 

 process was then repeated on the rest of the 

 pool to give Millipore pads PM-2-1, MP-2-2 

 and extract E-2 which had a final volume of 

 5 ml. derived from 1750 ml. of pool. The 

 glass filter used in this last extraction 

 had a maximum porosity of 1.2 u. Two 0.50 -ml. 

 aliquots of each extract were evaporated on 

 steel planchets at 35°C under a hot-air 

 stream and an infrared lamp (E-l-1, E-1-2j 

 E-2-1, E-2-2). The results of these 

 experiments are shown in the Table 19- 



The next experiment was performed at Station 

 S-10, 130 miles off Costa Rica (8°l*-2' N 

 latitude, 86°00' W longitude) on November 2k, 

 1956. Fourteen 250-ml. bottles of surface sea 

 water were incubated with 5,77^,000 cpm. of 

 Cl 1 *- per bottle for five hours at 1200-1^0 

 fc. at 26 <> C. After incubation the contents 

 of one bottle (260 ml.) were filtered through 

 a Millipore filter (MP-3-l) • The contents of 

 six bottles (1580 ml.) were filtered through 



an M-porosity sintered-glass filter 

 (maximum pore size 1*+ u). Two 250-ml. 

 portions of this filtrate were filtered 

 through Millipore filters (MP-3-2 and 

 MP-3-3). The residue on the glass filter 

 was washed and extracted in the same manner 

 as in experiments 1 and 2. The combined 

 extracts were made to lO.U-ml. final volume 

 without drying and re-extracting with water 

 to yield extract E-3. The whole process was 

 repeated with the seven remaining bottles to 

 yield Millipore pads MP-^-l, MPA-2, and 

 MP-1(— 3 and extract E- 1 * which was derived by 

 filtration of 1575 ml. of the original water 

 through an M-porosity glass filter and which 

 had a final volume of 7.6 ml. Two 0.50-ml. 

 aliquots of each extract were plated on 

 planchets as in experiments 1 and 2. The 

 results of these experiments are shown in 

 Table 20. 



These experiments show that about 15°/o of 

 the cellular carbon in naturally occurring 

 phytoplankton populations is alcohol soluble. 

 A similar proportion of soluble to insoluble 

 material (expressed on a dry-weight basis) 

 is found generally in those few algae which 

 have been investigated (cf. Fogg, 1953). It 

 is striking that there is little variation 

 in the percentage of extractable material 

 in phytoplankton from the three areas . 

 Presumably nutrient conditions might be 

 different in the various areas and the cells 

 might reflect thi6 by having differing 

 proportions of soluble material. 



It can be inferred from the data, if the 

 assumption e made that the alcohol-soluble 

 material is al60 soluble in sea water, that 

 when an algal cell dies 15° /o of the cell 

 material would be immediately released to the 

 water and would serve as food for bacteria and 

 other hetrotrophic organisms. A portion of 

 this material might also become a part of 

 that more resistent dissolved organic material 

 which accumulates in the ocean. It is also 

 probable that only 85°/o of the material 

 produced by phytoplankton has any chance at all 

 of reaching the bottom and becoming a part of 

 the organic material in sediments. 



If a phytoplankton cell is eaten before it 

 dies, then some 15°/o of its material is 

 immediately available for incorporation into 

 the body tissues of the animal which eats it. 



- 116 



