116 University of California Publications in Zoology [Vol.22 



typical Protozoa (Mastigophora are included above with chlorophyll 

 bearers) and of the Rotifera. Examination of plate 6 discloses the 

 fact that Protozoa showed pulses at about the same periods as did the 

 chlorophyll bearers, slightly preceding the latter at the first and coin- 

 ciding at the second. The evidence which this gives of close associ- 

 ation of the two groups is the only important feature. The analysis 

 of the relationship presents some decided difficulties. In the first 

 place, most of the Protozoa found here at this time were of the type 

 which depends upon bacteria for food rather than upon green or- 

 ganisms (at least no Protozoa were ever observed with green organisms 

 in their bodies). The presence of green organisms might favor them, 

 however, by excretion of oxygen and absorption of carbon dioxide. 

 Aside from these considerations, the only reason for coincidence of 

 pulses in the two groups would seem to be in general conditions 

 favorable to both. 



In the case of the Rotifera, the abundance of food with which 

 most of them are furnished by an increase in green organisms would 

 seem sufficient to account for close correspondence of pulses of the 

 two groups. Unfortunately for the validity of this view, the first 

 rotiferan pulse (pi. 6) culminates on July 12, five days before the 

 culmination of the pulse of chlorophyll bearers. It is also true that 

 the second pulse coincides exactly with that of the green organisms. 

 If the food relationship were the deciding factor, the rotiferan pulse 

 should always follow. It is possible that here again is a case in 

 which the gaseous content of the water forms one of the connecting 

 links for two groups of organisms. 



Summary 



Considering the large numbers of factors which might influence the 

 location of pulses of various organisms or groups of organisms, it is 

 necessary for the present to say that the showing made by this daily 

 series of a single lunar cycle may be to some degree accidental. 

 Hence no inference can be regarded as proven. The important 

 inferences suggested by these daily records may be summarized as 

 follows : 



1. There was a very distinct increase in numbers of green organ- 

 isms as the light of the moon increased. 



2. There was an abrupt decrease in green organisms as Entomo- 

 straca increased, which was followed by a partial recovery after the 

 entomostracan maximum. 



