12 



air was changed by removing the bell-jars for a few minu- 

 tes. This was done at a time when the himidity of the 

 atmosphere in the greenhouse was relatively high. 



The temperature of the three conditions was the same 

 as that in the open greenhouse, viz., aboxit es^F. during 

 the day and 60 F. at night, ex?ept that on bright, clear 

 days the rays of sunlight caused a rise in temperature of 

 several degrees in the bell-jars above that in the open 

 greenhouse. This change of teiuperature was the same in 

 both the dry and moist. The teiaperature factor must be 

 talcen into consideration when comparing the checTc with the 

 other two conditions. 



The follo'i7ing table gives the number of baskets used, 

 the number of plants in each and the date of the beginning 

 and end of the period during which transpiration records 

 were taken. 



