Jan., 1921] 
BERGMAN — OXYGEN CONTENT OF WATER 
57 
the respiratory quotient higher in young leaves than in those fully matured. 
Most of the experiments indicate (see table 2) that the flowers produce 
carbon dioxide at a slightly higher rate than the growing tips, although in 
the second trial on July 14 this is not true. In these experiments the 
flowers and growing tips produced carbon dioxide two to three times as 
fast as did the old shoots. Maige (3, p. i) has shown in experiments with 
a large number of plants that the intensity of respiration of floral organs is 
greater than that of leaves. A more rapid rate of respiration, however, 
means a greater oxygen requirement. This accounts for the injury to the 
flowers and growing tips resulting from prolonged submergence in water 
deficient in oxygen. 
From the data submitted it is evident that injury is most apt to occur 
to a bog by flooding during a period of cloudy weather. Naturally the 
injury is apt to be greater the longer the period of time during which the 
water is held on the vines, and especially if cloudiness prevails throughout 
the period. The degree of injury is probably not directly proportional to 
the reduction in light interfsity, for, as Brown and Heise (2, p. 85) point out, 
the published works on carbon dioxide assimilation "indicate a progressively 
smaller augmentation of the rate of assimilation for each increase in light 
intensity." A certain, as yet unknown, reduction in light intensity is 
necessary to bring about a balance between the photosynthetic and the 
respiratory activity. After this point has been reached, accepting the 
conclusions of Brown and Heise (2, p. 94), each decrement in light intensity 
should have a progresvsively greater injurious efiect. 
A number of other factors which m^ay affect the result are operative. 
Much depends upon the character of the water as it is placed on the bog. 
Clear pond or river water has a higher initial oxygen content, so that the 
oxygen is not depleted as rapidly as from a water supply initially deficient 
in oxygen. Where water from a cedar swamp, or other reservoir having a 
great deal of organic matter on the bottom, is used, the initial oxygen 
content may be very low. This, as indicated elsewhere, is due to the fact 
that organic matter absorbs oxygen and gives ofl^ carbon dioxide. In 
cloudy weather the initial oxygen content of water from a swamp reservoir 
would be considerably lower than in clear weather. All other factors 
remaining the same, greater injury would result during a period of warm 
weather than of cool, due to the increase in the rate of respiration with a 
rise of temperature. On the other hand, the ability of the water to absorb 
oxygen diminishes with an increase of temperature. 
In conclusion it may be pointed out that the matter of oxygen content 
as affected by light intensity and other factors is of great importance in 
combating insect pests by flooding. A combination of factors producing a 
low oxygen content in the flooding water at a time when the insect larvae 
are active is most desirable. Such conditions would, however, be highly 
detrimental to the cranberries. It would be necessary, therefore, to con- 
