Jan., 1921 
BERGMAN — OXYGEN CONTENT OF WATER 
53 
of the State Bog is much higher than that of the water in Spectacle Pond. 
This is due to the large amount of decaying organic matter which is con- 
stantly giving off carbon dioxide. The carbon dioxide content of the water 
of Cedar Pond and the State Bog ditches is higher and the oxygen content 
lower hi the morning for three reasons: First, because photosynthesis does 
not take place during the night and carbon dioxide is not withdrawn by the 
plants. Second, respiration is going on, as a result of which carbon dioxide 
is given off and oxygen taken up. Third, the organic matter on the bottom 
is slowly taking up oxygen and liberating carbon dioxide. This applies 
also in cloudy weather. 
Even after these facts had been ascertained, their significance as a factor 
in cranberry culture was not fully appreciated until the spring of 1919. 
Attention was then called forcibly to the importance of weather conditions 
in relation to the oxygen content of flooding water through the difficulty 
which many of the growers experienced in injury to the buds and new shoots 
of cranberry plants, resulting from the flooding of bogs during a period of 
cloudy weather. Although data had already been obtained which would 
apparently account for injury under such circumstances, it seemed advisable 
to make further investigations upon this point. 
Dr. H. J. Franklin, of the Massachusetts State Cranberry Station at 
East Wareham, had planned some experiments with cranberries to deter- 
mine whether or not reduction of light could cause injury to cranberry 
blossoms or tips. Four pieces of cranberry sod were dug up and placed in 
galvanized iron tubs. Two of these tubs were filled with ditch water and 
set in the main ditch of the State Bog so that the edge of the tub was an 
inch or more above the surface of the water in the ditch. This prevented 
the entrance of any water from the outside. One of the tubs was covered 
with pieces of corrugated metal roofing to exclude light, while the other 
was left exposed. Two other tubs containing pieces of cranberry sod were 
similarly placed in Spectacle Pond. 
The experiment began in the late afternoon of June 28, 1919. Analyses 
for the oxygen content of the water in each of the four tubs, in the main 
ditch, and in Spectacle Pond were made at the beginning of the experiment. 
Other analyses were made at sun-down, at 10:00 to 11 :oo p.m., before sun- 
rise the next morning, and two or three times during the day. This general 
procedure was followed throughout the experiment although samples were 
not taken as frequently after the second day. The experiment extended 
through four days for the vines in Spectacle Pond. The vines in the ditch 
were taken out after three days. The results of the analyses for oxygen 
are presented in figures i, 2, and 3. The determinations of oxygen content 
were made by the Winkler (7, p. 2843) method. 
The results were strikingly clear. The vines in the shaded tub in the 
ditch had all, or nearly all, of the blossoms and many of the growing tips 
either killed or injured. On the vines in the unshaded tub in the ditch 
