EFFECT OF TEMPERATURE. 



9 



TEMPERATURES. 



The fruits were usually held at three different temperatures, 

 although at times four were employed and in several cases only two 

 are recorded. The four temperatures were as follows: (1) A cold- 

 storage temperature of about 2° C, which was usually very steady 

 and rajely varied more than 1° during a run. (2) An ice-box tem- 

 perature of from 7.1° to 12.7° C. The temperature in this case usually 

 rose slowly during a determination as the surface of the ice decreased 

 with melting, and rarely varied more than 2°C. during a determina- 

 tion. (3) Room temperature, which varied according to the season 

 of the year from 20.5° to 31.2° C, but was very steady from day 

 to day, as the darkened cabinet in which the desiccator was kept 



Fig. 2.— Electrically-heated, constant-temperature incubator. . 



was situated out of the way of drafts. (4) The incubator tempera- 

 ture, from 32.6° to 35.6° C, was automatically regulated and varied 

 at most but 0.2° C. during a determination. The temperatures 

 were taken at the beginning and at the end of a run by reading short 

 corrected thermometers placed in the desiccators among the fruit. 



REGULATION OF INCUBATOR. 



The incubator in which the fruit was kept when it was desired to 

 measure the respiration at a higher temperature than that of the 

 room consisted of a wooden cabinet with well-fitting doors. The 

 arrangement of the heating device is shown diagrammatically in 

 fig. 2. The incubator was large enough to contain the desiccator, A, 

 an electric fan, C, an electric heating coil, B, a thermostat, D, and 

 various lots of fruit. In planning the method of heating slightly 

 95678°— Bull. 142—11 2 



