6 STUDIES OX FRUIT RESPIRATION. 



SELECTION AND PREPARATION OF THE FRUIT. 



Whenever practicable the variety and locality were selected by 

 Wm. A. Taylor, of the Bureau of Plant Industry, in order that the 

 study should have as direct an application as possible to field work. 

 The fruits so selected came from localities in which the particular 

 variety was grown under typical conditions on a commercial scale. 

 The fruit from the Arlington farm was usually picked from the trees 

 on the day preceding the date of the beginning of the experiments. 

 Except where noted, none of the fruit had been subjected to cold 

 storage or any known condition winch could cause abnormality. 



Each sample was prepared for the experiment by first eliminating 

 unsound or injured specimens. The sample was then divided into 

 two or more weighed lots for the measurement of the rate of respira- 

 tion at different temperatures. After weighing, each lot of fruit was 

 kept at the temperature at which it was desired to measure the rate 

 of respiration for several hours or overnight before starting the exper- 

 iment, in order that it might acquire the temperature of its surround- 

 ings. To effect this the fruit was placed either in open baskets beside 

 the desiccators in which it was to be run later, or in the desiccators 

 themselves. In the latter case a rapid current of air was passed 

 through them in such a way that the air surrounding the fruit was 

 continuously renewed. In the case of the small fruits, the greatest 

 care was exercised in selecting and handling them during the opera- 

 tions of weighing and placing in desiccators. The best specimens as 

 far as freedom from any suspicion of spoilage was concerned were 

 selected for the experiment at room temperature, as it was realized 

 that here was the greatest danger of vitiation of the results, owing 

 to the activities of yeasts and other microorganisms. The red rasp- 

 berries, in particular, were extremely delicate, and it was difficult to 

 avoid breaking them during the necessaiy handling of the fruits. 

 Similar precautions were necessary in the case of blackberries. With 

 the red and black currants, only berries attached to stems were used, 

 to lessen the chances of deterioration due to the development of 

 microorganisms at the pedicels. At times, in the work on the small 

 fruits, the experiments were run for several days in order to obtain 

 duplicate determinations on the same lot of fruit. In all cases well 

 agreeing duplicates were obtained except where visible deterioration 

 due to spoilage occurred. The first lot of black raspberries had per- 

 ceptibly molded at the close of the period of measurement in the 

 desiccator kept at room temperature, and accordingly, a few days 

 later, a second sample of fruit from the same patch was run. This 

 sample also molded very slightly. It is probable that, in both cases, 

 increases of carbon dioxid due to activities of microorganisms were very 

 small. The huckleberries and the wild blackberries were obtained 



