26 



STUDIES ON FRUIT RESPIRATION. 



7 mg of carbon dioxid per kilogram per hour, respectively, were 

 formed. The results of the second day's run were practically a 

 duplicate of those of the first day. 



Black currants and huckleberries were intermediate in physiological 

 activity between raspberries, blackberries, and strawberries on the 

 one hand and red currants on the other. 



Carman peaches when hard-green respired slightly less rapidly than 

 when ripe. After ripening, however, the respiratory activity de- 

 creased slightly but decisively. With Hiley peaches results were 

 obtained at but two temperatures, as the determination at the cold- 

 storage temperature was lost. The curve of Champion peaches 

 closely paralleled that of the Hiley and of the fully ripened Carman. 

 In the case of Connett peaches there was a distinct decline in physio- 

 logical activity from one day to another. During the first day at 

 29.0°, 10.7°, and 1.1° C, 104, 25, and 7 mg of carbon dioxid per kilo- 

 gram per hour were formed, respectively; while during the second 

 day's run, at temperatures of 29.6°, 11.0°, and 1.1° C, 93, 22, and 6 

 mg, respectively, were collected. The curve of Elberta peaches 

 closely paralleled that of Connett peaches during the second day's 

 run and seemed distinctly less active physiologically than the other 

 sorts. 



A special lot of Dover peaches picked on August 24, at three differ- 

 ent stages of ripeness, from the same tree at the Arlington farm, was 

 separated by A. V. Stubenrauch, of the Bureau of Plant Industry, 

 into three lots according to ripeness — hard-green, hard-ripe, and tree 

 or eating-ripe. The measurement of the rate of respiration was 

 begun on the same day. The peaches respired at the rate of 101, 

 98, and 101 mg, respectively, showing that no marked changes in 

 rate of respiration occur during ripening on the tree. The data are 

 as follows: 



Table 3. — Respiration data on peaches picked at three 



of ripeness. 



Stage of ripeness. 



Num- 

 ber. 



Weight. 



Interval. 



Temper- 

 ature. 



Carbon 

 dioxid 

 (milli- 

 grams per 

 kilograra 

 per hour). 



Hard-green 



14 

 15 

 13 



Grams. 

 1,570 

 1,703 

 1,458 



Hours. 

 17.8 

 18.0 

 18.3 



•°c. 



28 

 28 

 28 



101 

 98 



Tree-ripe 



101 



Plums, apples, and pears were less active than peaches. Summer 

 apples respired with perceptibly greater rapidity than the winter 

 varieties. 



The Concord, Delaware, Niagara, and Catawba grapes were found 

 to be distinctly more active than the Vinifera grapes, Flame Tokay, 

 Black Cornichon, and "Almeria," or the Kotundifolia variety James. 



