409 



50 were found per sq. mm. upon both surfaces; they were some- 

 what unevenly distributed. Cells containing tannin occurred 

 to the number of about 35 per sq. mm. upon the upper sur- 

 face, and were also unevenly distributed; upon the lower sur- 

 face only a few occurred. 



The leaves of R. FaUasii which were investigated had two 



Fig. 49. -R. Pallasii. 



A, Transverse section of leaf ('""'i). B, Epidermis of the upper surface of the leaf ("-Vi); 

 t, cells the contents of which are probably tannin. C, Epidermis of the lower surface of 

 the leaf (*-Vi). D, Surface section of spongy tissue {^h). E, Longitudinal section through 

 the leaf-apex, showing the position of the epithema ("/i). F, Cells of the epithema 



with jiuclei {-'"h)- 



palisade-layers which constituted from ^!-2 to ^ s of the thickness 

 of the mesophyll; the individual palisade-cells were irregular, 

 about twice as long as they were thick, and only slightly in- 

 clined towards the leaf-apex. There was a gradual transition 

 to the spongy parenchyma; the cells of the latter were shortly 

 branched or stellate, and as usual, those of the subepidermal 



