1908] 



CLAP P— STUDY OF TRANSPIRATION 



257 



ture was raised by an electric heater in the bottom of the case, and 



street 



top of the case. To promote prompt and even warming or cooling, 



Fig. 2 



electric fans of small size were made to blow air over the heating or 

 cooling arrangements. Moisture was decreased by uncovering dishes 

 of calcium chlorid and increased by exposing w^et sponges and cloths. 

 The case was always brought to the standard conditions, the plant was 

 weighed and left in still air for as long a time as the conditions remained 



