THE FACTORS 



[Part I 



constant. (2) Diminution of intercellular spaces containing air. (3) 

 Augmentation of the vessels and sclerenchyma. (4) Lengthening of the 

 palisade-cells. Frequent but not universal. (5) Increase in the thickness 

 and amount of cutin of the outer wall of the epidermis. (6) Sinking of the 

 stomata. (7) Increased number of air-containing hairs. (8) Supply of 



Fig. 2. Xerophilous structure. Dry climate in Temperate Australia. Stomata. a Franklandia 

 fucifolia. b Eucalyptus giganteus. After Tschirch. 



Figs. 3 and 4. Xerophilous structure. JJ'et saline soil of Javanese mangrove-swamp. Left hand : 

 Aegiceras majus. The upper surface of a leaf. Magnified 260. Right hand: Rhizophora mu- 

 cronata. Stoma and epidermis of the lower surface of leaf. Magnified 550. 



Figs. 5 and 6. Xerophilous structure. Cold soil of Greenland. Left hand : Dryas integrifolia. 

 Transverse section of leaf. Right hand : Loiseleuria procumbens. Part of transverse section of leaf; 

 B palisade-cells, V outer wall of epidermis, c cuticle, A' lumen of epidermis-cell, g inner wall of 

 epidermis. After Warming. 



water-storing cells (double epidermis, aqueous tissue, mucilage-cells, &c.) 

 (Figs. 1-8). 



With the exception of the increase in the sclerenchyma and the lengthen- 



