62 



are found. The epidermis consists of a single layer of cells 

 with thickened outer walls. IMany of the cells have projections 

 extending into the air spaces. The projections or processes are 

 usually less than the diameter of the cells from which they arise 

 and vary in number from one to several for each cell that may 

 bear them. In form they are tapering-tubular, and have a hol- 

 low center which is continuous with the cavity of the epidermal 

 cell. The end of the projection is closed by a wall which is thin- 

 ner than any other portion of the wall of the cell. 



If a section of the leaf is made, the processes will, in many 

 instances, possess droplets of liquid of varying sizes, borne at 

 the tips. The size of the droplet of any process is perhaps 

 roughly commensurate with the time the seereiion has been ex- 

 uding. This remains true how^ever only till the drops become 

 confluent. 



Figure 2. 



Cross section of a groove showing epidermal processes, some 

 Ol which have drops of exudate. 



]\Iacroscopically, the leaf appears covered with tiny, clear 

 beads of exudate that become dried sooner or later, leaving a 

 salty incrustation that possesses the property of deliquescence. 



