LOSS OF WATER 
of the jar will soon become clouded by a thin film of 
moisture, and within a very short time, this moisture will 
begin to collect in drops (Fig. 13). 
FIG. 15. Aster sp. Series of leaves, all from one plant, showing gradual 
transition from petiolate (lower right hand specimen) to sessile leaf. 
The surface of the control jar will remain perfectly dry. 
If the experiment is set in the sun, the result will be 
greatly hastened. This loss of water from within living 
