THE KEEPING QUALITY OF CEAXBERBIES. 5 



picked berries show better keeping quality than those picked early. 

 The greater injury to the light-colored early-picked berries is appar- 

 ently due to the higher respiration rate of these berries. 



TEMPERATURE OF THE WATER. 



The effect of temperature is very important in determining the rate 

 of respiration. Morse (8) has recently proved that in the cranberry, 

 as in many other fruits (7); the rate of respiration is twice as rapid 

 at 10° as at 1° C. and that the rate doubles again at 20° C. This 

 means that the amount of oxygen necessary to maintain the normal 

 activity of the berries is twice as great at 10° and four times as great 

 at 20° as at 1° C. On the other hand, the capacity of water for 

 holding oxygen diminishes with the rise of temperature. Other 

 things being equal, then, the colder the water the better it is for use 

 in water-raking. It is obvious that in this respect the conditions 

 are more favorable for continued flooding in Wisconsin than in 

 Massachusetts or New Jersey. 



OXYGEN CONTENT OF THE WATER. 



The importance of the flooding water in the cranberry industry 

 has led to a careful study of different water supplies and their relation 

 to injury from flooding by one of the writers (Bergman). These 

 studies, which are in part unpublished, indicate that a very important 

 factor, perhaps the most important factor in water injury, is the 

 oxygen content of the water. Water having a high oxygen content 

 will cause much less injury in a given time than that having a low 

 oxygen content. The oxygen content of flooding water under 

 natural conditions is determined l)y atmospheric pressure, tempera- 

 ture, the quantity of organic matter in the water and substratum, 

 and the light intensity. ^ 



As atmospheric pressure varies only slightly from day to day, this 

 factor may for practical purposes be disregarded. The temperature 

 influences both the capacity of the water to hold oxygen and the rate 

 at which the oxygen is taken up from the water by organic matter. 

 Water reaches its greatest capacity for oxygen at 0° C. This capacity 

 decreases with the rise of temperature. On the other hand, the rate 

 of oxidation of organic matter increases with the rise of temperature. 

 From both points of view, then, the cooler the water the more favor- 

 able for a high oxygen content. 



The presence of decaying organic matter in the water or in the 

 substratum reduces the oxygen content of the water. Decay is a 

 process of oxidation, and decaying organic matter in the water or the 

 substratum can obtain oxygen only from the water. Therefore, it 

 decreases the oxygen content of the water in proportion to the 

 amount of organic matter present and the rate of oxidation, which, 

 in turn, depends on the temperature. 



