TRANSPIRATION OF SILPHIUM 



319 



removed from the plant, placed in bottles as already described, 

 and placed side by side during the experiment. While this gives 

 the action of the leaves under similar conditions, it does not show 

 what would be their action at their own respective heights. 

 This of itself furnishes an interesting problem for a series of 

 experiments, but is not discussed in this paper. 



In the experiment of August 19 (table 6) four Silphiurn leaves 

 were used. The leaves were all taken from the same plant at 



TABLE 6 



The transpiration (in grams per 100 sq. cm.) of four leaves of Silphium from 

 different heights and the evaporation {in cubic inches) from two evaporimeters at 

 different heights, with the concurrent relative humidity and wind velocity (in 

 miles per hcur). The anemometer was at a height of 5Ii. cm. August 19, 1912 



different heights. No. 1 was taken from a height of 13 cm.. 

 No. II from a height of 47 cm.. No. Ill from a height of 71 cm. ; 

 and No. IV from a height of 100 cm. The leaves being of such 

 unequal size, the results given in the table are on the basis of 

 100 sq. cm. of leaf area, both sides of the leaf being included. 

 From the data for this experiment it will be seen that three 

 of the leaves showed the greatest amount of loss at the same time 

 that one of the evaporimeters showed a maximum less, but an 

 hour before the other evaporimeter indicated a maximum loss. 



