11 



Water was added at this time until the weight of the basket 

 was a few grams above the optiraom, the excess depending 

 upon the rate of loss. 



The plants wore divided into three lots and each sub- 

 jected to one of the three conditions, which were designa- 

 ted as dry, checlc and moist. The three lots were placed 

 side by side in the greenhouse, the dry and moist being 

 under bell- jars while the checlc was unenclosed. 



The average relative humidity of the dry was 78**, of 

 the ohecfc 88°and of the moist 93". The excess of moisture 

 was removed from the atmosphere of the dry, by placing 

 calcium chloride in open dishes under bell-jars. The 

 calcium chloride was changed as soon as it had become sat- 

 urated with moisture, usually morning and night. The high 

 degree of humidity of the moist bell- jars was maintained 

 by placing pieces of wet filter paper imder them. 



The bell-jars were aerated each morning in the fol- 

 lowing manner : With those subjected to the dry conditlona 

 this was accomplished by forcing air, from which the moist- 

 ure had been removed by passing thru a column of calcium 

 chloride and pumice stone, into the bell- jars. in the 

 case of those in which the moist conditions obtained, the 



