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



CURRANTS AND GOOSEBERRIES 



In both currants and gooseberries (Ribes spp.) it was ob- 

 served that the temperature of the fruits on the bushes was not 

 nearly so high as was reached by the same fruits when spread 

 out in the sun on a paper. 



Currants picked from bushes in ahnost complete shade at 

 Milton, N. Y., on July 13, 1917, at 9 a.m. were found to have a 

 temperature of 23.5°C., while those picked from bushes in full 

 sunlight had a temperature of 29.5°C. After exposure to the 

 sun for two hours on a paper, both lots showed a temperature 

 of 38°C., whereas berries freshly gathered from bushes in full 

 sunlight had a temperature of 31.5°C. Green gooseberries 

 exposed to direct sunlight for two hours at Arlington Experi- 

 ment Farm, Virginia, reached a temperature of 34°C., while 

 those freshly picked had a temperature of 23.5°C. Air tempera- 

 ture was 20°C. The difference was apparently largely due to 

 the fact that the berries on the bushes were somewhat shaded. 

 In addition, those exposed to the sun were placed near the 

 ground where air currents were slower and loss of heat by con- 

 vection was probably thus reduced. 



RASPBERRIES 



The data on raspberries {Rubus sp.) are so fragmentary that 

 they are not worth tabulating. They do, however, indicate 

 that the same relation holds for these as for the other small 

 fruits. Observations on black raspberries (Rubus sp.) and 

 yellow raspberries (Rubus sp.) were made at Vienna, Virginia, 

 July 20, 1917. The day was partly cloudy and is recorded by 

 the Weather Bureau as giving 41% sunshine at Washing- 

 ton, the nearest Weather Bureau station, about 10 miles distant. 



The temperature of a box of black raspberries picked at 1 



(p. 193) "In round numbers the average difference between the plant and air 

 temperature in full sunshine was 15° F.; in partial sunlight, due to thin clouds 

 or intermittent cloudiness, it was 10° F. and less than 1° F. when the sky was 

 thickly overcast, so that the sun's disk was invisible." One instance is cited 

 in which the leaf temperature was 36° F. above that of the air. 



