182 N. E. STEVENS AND R. B. WILCOX 



The possibility should not be ignored that a small part of the 

 observed rise in temperature may be due to heat arising from 

 respiration and that this heat may increase with rise in air 

 temperature ( (7), p. 367). The amount of heat developed by the 

 respiration of ripe fruits was, however, found by Dutrochet 

 ( (2), p. 82), who worked with pears (Pyrus communis L.) plums 

 (Prunus sp.), peaches {Prunus persica L. Stokes) and Ribes 

 Uva-crispa, to be sufficient to raise their temperature only 

 from 0.06°C. to 0.08°C. Rodewald ( (9), pp. 296 and 342), 

 working with ripe apples, found that the amount of heat arising 

 from respiration was slight compared with that necessary to pro- 

 duce such differences in temperature as those cited in the present 

 paper. 



On the other hand rise of temperature due to insolation has 

 been observed in some other plants to be much greater than 

 that reported by the writers even in the strawberry. Askenasy 

 ( (1), p. 441) observed that the temperature of the leaves of 

 Sempervivum exposed to the sun may attain temperatures of 

 43.7°C. to 41.2°C. when thq temperature of the air is only 31°C., 

 while Ewart (4) records temperatures of 45°C. to 50°C. in the 

 leaves of several tropical plants. 



COLOR OF FRUIT IN RELATION TO TEMPERATURE 



So far as the present observations extend, the color of the 

 fruit does not seem to materially affect the temperature reached 

 at a given time. No constant difference could be noted between 

 red (i.e., ripe) strawberries and green or white (unripe) ones 

 of the same variety in the same field. No difference could 

 be found between red and white currants. Although repeated 

 tests were made comparing the temperature of red (ripe) cran- 

 berries of the Early Black variety with that of green or white 

 (unripe) cranberries of the Late Howe variety gathered at the 

 same time, no constant difference could be observed. 



Although it is probably true that fruits of certain colors absorb 

 more heat than others, the loss of heat is so rapid that the excess 

 of heat absorbed over that lost is possibly about the same in all. 



