FR ME rah ee ae GER PERE Gage ee Ee SOB TERS Ce cS ee” Tag ee a ke ee ee 
RELATION OF ALGAE TO DISSOLVED GASES. 189 
with cloudiness and sunshine. The first figure, low, with 
3.3 ec. of oxygen, June 23, is after rain and cloudy weather, 
while the high figure, 7.34 cc., July 30, is after a long space 
of clear weather and the appearance of the ‘“water-bloom,” 
which seems to have been the important agent in producing 
the increased amount of oxygen. 
The lowest figure shown for oxygen, August 25, is after 
two days of cloudy weather, though the accompanying fall in 
temperature would increase the water’s capacity. Again, on 
August 28, we have combined rain, cloudiness and wind. 
The wind diminishes the oxygen content by stirring the water 
and making supersaturation impossible. September 5, these 
conditions are augmented by a heavy rain (2.5 inches), 
which reduced the oxygen figure to 3.44 cc. The heavy rain 
left the lagoon so clouded as to interfere with photosynthesis, 
and the organic matter carried in by surface drainage, in- 
cluding some sewage, would greatly reduce the oxygen. It 
is worthy of note that the decrease was not so great in the 
upper basin, or Fountain Pool, which was less affected by 
surface drainage (figures not shown in the table). 
At this time, also, the “bloom” sank out of sight for a time, 
apparently on account of the cooling of the water, or possibly 
on account of a change in the specific gravity of the organisms 
composing the “bloom,” so that photosynthesis probably was 
almost nil in the water darkened by the large amount of 
matter in suspension. The same conditions were repeated 
September 26, when the oxygen figure reached its minimum 
of 2.32 cc. These data, small in number, selected from a 
much larger number, are presented, not on account of their 
agreement with any particular theory, but because they are 
representative. Those not given are omitted simply because 
they are not significant. 
One thing might be misleading in the column on cloudi- 
ness, as long lists of clear days have been omitted during 
which there was no change. This brings a disproportionate 
number of cloudy days into too close a sequence. 
