26 



INTRODUCTORY 



evaporation is prevented. In the Hairy Alpenrose a 

 precisely similar arrangement is met with : only, the 

 older leaves do not turn brown below. 



If we were to examine such a leaf carefully under 

 a microscope, by means of thin sections cut with a 

 razor, we should find that the lower surface is covered 

 with a number of green or rusty brown coloured 



FIG. I. The Leaf and Scales of the Common Alpenrose 

 (Rhododendron ferrugimum, Linn.). 



1. Transverse section of a leaf, showing the scales on the lower surface. 



Magnified 14 times. 



2. Transverse section through a scale, on the right side of which a stoma is 



seen sheltered by the scale. Magnified 190 times. 



3. Surface view of a scale. Magnified 190 times. 



scales. Text-fig. I., 1, shows a transverse section of 

 a leaf and the scales below. In Text-fig. I., 2, we 

 see a scale cut in transverse section, on the right- 

 hand side of which a pore, or stoma, is seen sheltered 

 by the scale. In Text-fig. I., 3, the surface view of the 

 scale is depicted. The scales are broad, flat structures 



