150 
BULLETIN OF THE BUREAU OF FISHERIES 
loss on ignition had not been any greater than during the interval from August 9 
to 20. The large increase in the organic phosphorus, however, suggests that more 
phosphorus had been used than would have been expected from the increase in the 
organic matter. The increase after August 30 occurs at the expense of the organic 
phosphorus. The first decline in dissolved phosphorus occurred simultaneously 
with an abundant growth of the blue-green alga, Sphaerozyga. This alga is attached 
to the bottoms and does not appear in the water samples on which the organic matter 
is determined. After this alga disappeared, the plankton and the organic matter 
increased and the soluble phosphorus decreased to a minimum. The dissolved 
phosphorus did not increase again until the organic matter decreased. A marked 
increase in dissolved phosphorus did not occur until after additional superphosphate 
had been added. The organic phosphorus remained uniformly low until after the 
first sharp decline in the amount of organic matter on August 9. The maximum 
of 0.50 p. p. m. occurred on August 30 and is correlated with a rise in organic matter 
and a decrease in the dissolved phosphorus. Two weeks later the organic phos- 
phorus was down to 0.140 p. p. m. again, but the soluble phosphorus had increased 
from 0.550 to 0.960 p. p. m. The variations in the organic and the dissolved phos- 
phorus are illustrated in Figure 2. 
In C 2 the dissolved phosphorus ranged from none at all to as much as 0.096 
p. p. m. Except for the maximum on August 20 and a near maximum value for August 
30 the dissolved phosphorus was uniformly low. On several occasions no soluble 
phosphorus was present. The rise in August is largely, if not altogether, due to the 
addition of fertilizer. (Through an error on the part of an assistant, 5 ounces of 
superphosphate were added to this pond along with the soybean meal on August 14.) 
It is not likely that much of this increase had come from the decomposing plankton. 
(Fig. 2.) The organic phosphorus ranges from a minimum of 0.070 p. p. m. to a maxi- 
mum of 0.410 p. p. m. Figure 2 gives little evidence that points toward the regenera- 
tion of dissolved phosphorus from the organic. The latter seems to accumulate 
gradually until the maximum is reached. There is nothing in the rest of the data to 
account for the decrease in the organic phosphorus between August 30 and September 
13. (The assumption might be made that on August 30 a very considerable amount 
of organic matter, rich in phosphorus, was colloidally dispersed in such fine particles 
that the centrifuge did not remove it.) 
In C 3 the dissolved phosphorous varied from a minimum of 0.005 p. p. m. on 
June 19 to a maximum of 0.90 p. p. m. on August 20. Table 5 and Figure 3 show that 
the lower values for the dissolved phosphorus correspond to the higher values for 
organic matter. The simultaneous rise in dissolved phosphorus and the organic 
matter between July 7 and 19 may be due either to the addition of fertilizer on July 
11 or to the degeneration of organic phosphorus. The increase in soluble phosphorus 
between July 19 and August 9 must have come from the decaying organic matter. 
The decrease between August 20 and 30 is accompanied by increases in organic matter 
and in the organic phosphorus. As soon as the organic matter begins to decline the 
soluble phosphorus goes up again. The organic phosphorus ranges from a minimum of 
0.050 p. p. m. to a maximum of 0.550 p. p. m. The minimum for organic phosphorus 
corresponds to the maximum for the soluble phosphorus. Figure 3 shows the varia- 
tions in organic matter, the dissolved phosphorus, and the organic phosphorus. Some 
degree of relationship between the soluble phosphorus and the organic matter is 
suggested by Figure 3. Yet one could not draw the conclusion that the soluble 
