PLANKTON PRODUCTION IN FISH PONDS 
155 
true for the organic matter is also true of the net plankton; namely, that the three 
ponds which were fertilized produced more plankton than did the control pond that 
was not fertilized. 
In Table 7 there is given a brief summary of the results of enumerating the 
animals in the net plankton samples. Only the most important genera are listed. 
For a more complete tabulation of these results the reader is referred to another paper 
Figure 5. — Variations in free carbon dioxide, dissolved oxygen, chloride, different forms of nitrogen 
and phosphorus, and organic matter expressed in p. p. m.; pH values and temperatures in degrees C. 
for ponds D 4 and D 5 
(Wiebe et ah, 1929). The results show that Cyclops, Bosmina, the copepod nauplii, 
and the rotifers of the genus Anuraea were by far the most important constituents of 
the zooplankton. The table reveals a large discrepancy between the number of 
Cyclops and the number of nauplii. Since other copepods were present in very small 
numbers only, this discrepancy may be referred to as existing between nauplii and 
Cyclops. The table also shows that Anuraea was more abundant in the control pond 
