THE FACTORS 



[Part I 



constant. (2) Dimwutinn nf inter cellular 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 amouiitof cutin of the outer wall of the epidermis. (6) Sinkia§-&f *lve 

 stomata. (7) Increased number of air-con taining 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. Wei saline soil of Javanese mangrove-swamp. Left hand : 

 Aegiceras majns. The upper surface of a leaf. Magnified 260. Right hand : Rhizophora niu- 

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



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

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

 B palisade-cells, K outer wall of epidermis, <: cuticle, R lumen of epidermis-cell,^ 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- 



