81 



more closely to the other cells, with perhaps less tendency to 

 a lobate form, but like them they consist of more or less irregular, 

 rounded, paren- 



chymatous cells. 

 The lobes men- 

 tioned above cha- 

 racterize more 

 particularly the 

 central and lower 

 cells of the meso- 

 phyll, and are 

 seen most dis- 

 tinctly in the 

 transverse and 

 longitudinal sec- 

 tion ; in surface 

 section the cells 

 of the mesophyll 

 are irregular, but 

 no lobes can be 

 seen. In surface 

 section the inter- 

 cellular spaces, 

 which never attain 

 any considerable 

 size, are sharply 

 defined and shew Fig. 1. Pirola grandiflora. 



. I, Leaf in transverse section. 2, The epidermis of the lower surface. 

 transparent in ^ Hydathode. 4, The epidermis of the upper surface. S, Stoma. 



contrast with the ^' Horizontal section through the mesophyll which answers to the 



palisade-layer. 7, Horizontal section through the lower cells of 



brownish colour the mesophyll. The peculiar intercellular spaces should be noted. 



(Hab. several places in Greenland ; 2 is from Upernivik). (H. E. P.) 



(in Spirit-material) ^.^^ letters which accompany the figures indicate the same every- 



of the cells of ^Ьеге: — Ep, epidermis; Ei, the epidermis of the lower surface; 



Es, the epidermis of the upper surface; Chi, chlorophyll grain; pa, 

 the mesophyll 5 pallsade-tissue; Jnt, intercellular space. The upper and lower 



epidermis seen from the surface are drawn always with the same 

 they are smaller magnification in regard to each species. 



XXXVI. 6 



