278 BOTANICAL GAZETTE [april 



A 



of the writers, it was decided to conduct the following preliminary 

 experiments. While Shamel believed it was the high relative 

 humidity which was the controlling factor in retarding the ripening 

 of the pears, nevertheless the factor of high temperatures was 

 also present. Hence an experiment was outlined to endeavor to 

 determine whether high temperatures, or humidity, or both were 

 responsible. 



Method 



To obtain for the test what appeared to be the more important 

 combinations of temperature and humidity, compartments were 

 arranged as follows: (1) To maintain high temperature and high 

 humidity a large drying oven, having a ventilation outlet at the 

 top, was arranged with four shelves above two electric heaters. 

 Between the heaters and the shelves were buckets of water with 

 sacks and towels hanging into them to increase the evaporating 

 surface. (2) For high temperature and low humidity a Freas 

 electric oven was used with sufficient ventilation to maintain a 

 comparatively low relative humidity, but sufficient heat to maintain 

 a comparatively high temperature. (3) Two loc 

 tained at room temperature, one with ordinary 

 room and the other with provision for maintainin 

 humidity. (4) The cold storage 



main- 



room 



means of a thermostat 



that the temperature was always between 30. 5 F. and 32 .8° F., 

 with the relative humidity ranging from 67 and 73 per cent. 



^ 



the experiment 



21 days, one 



hygrothermograph was kept on the third shelf (next to the bottom 



the large drying oven, and 



with 



high humidity. These were both 



curial thermometers 



psychrometer and tested mer 



filled with 



m 



Each 



lot was numbered and described as follows: 



Lot 1, top shelf (no. 1) of large oven; high temperature 85 F. and high 



humidity 100 per cent. 



