RELATION OF LEAF STRUCTURE TO PHYSICAL FACTORS 49 



Thicket C. 50 /* P. i row, 20 M S. 30 c- 



Sunlight C. 175 M P. I row, 65 n S. IIOM 



+ I25/* +45^ (225%) +80^ (266%) 



Light 80/1 ; water (3-5-6-5%); humidity (3-10%); tem- 

 perature + 4. 



Acer glabrum 



SPRUCE SHADE: light 0.03; available water 12-16%; humidity 

 40-70% ; temperature 48-72 : diphotophyll 130/1; epidermis 2O/*, 

 lower epidermal cells with inner flat surface and outer very wavy; 

 cuticle thin; chlorenchym (90/1) I loose row prolate palisade cells 

 45 /*; loose triangular and oblate sponge cells. (Plate VI, fig. I a.) 



THICKET SHADE: light 0.014; available water 15% : diphotophyll 

 no/u,; epidermis 15/1; chlorenchym (75 /t) I row funnel palisade 

 cells 30/1,; loose oblate sponge cells. (Plate VI, fig. i b.) 



Spruce C. 90 M P. i row, 45 M S. 45 M 



Thicket C. 75 M P. i row, 30 A S. 45 y. 



ISA* 15 M (33%) o 



Light \\ other factors unchanged. 



HALF GRAVEL: light i; available water 4.5-7.5%; humidity 30- 

 65%; temperature 5i~76: diphotophyll 225/1; cuticle 3/1; chlor- 

 enchym (175 /x,) i close row prolate palisade cells 75 /*; rather close 

 irregular and prolate sponge cells; numerous mucilage and crystal 

 cells. (Plate VI, fig. i c.) 



Spruce C. 90 M P. I row, 45 v- S. 45 M 



Half gravel . . C. 175 /* P. i row, 75 M S. IOOM 



+ 85 J* +3Q/* (66%) +55M (122%) 



Light 33/1 ; water (7.5-8.5%); humidity (5-10%); tem- 

 perature + (3-4). 



Edwinia americana 



SPRUCE SHADE : light 0.03 ; available water 12-16% ; humidity 

 40-70%; temperature 48-72 : diphotophyll no/x; epidermis, 

 upper 20 /x, lower 15/4; cuticle, upper 2 p, lower thin; chlorenchym 

 (75 A*) I-2 rows prolate and prolobate palisade cells, first row 25 /*, 

 second row 20 /A ; loose irregular and oblong sponge cells. 



SPRUCE SHADE : light 0.0083 : diphotophyll 75 /x ; epidermis 

 io/x; cuticle thin; chlorenchym (55^) i row funnel and prolobate 

 palisade cells 20 ft; lacunose sponge cells. 



