116 
The upper and lower epidermis are thin-walled throughout 
and have no thick cuticle or cuticularized layer. The outer 
walls are, however, coloured yellow by chlor-zinc-iodine. The 
Fig. 28. Arctostaphylos alpina. 
1—4, The leaf. Zi, The large air-cavities formed by the epidermis of the lower surface 
having separated from the mesophyll; some of the large cells of this epidermis may also 
be seen. 5, shews how the new epidermis of the stem is formed. (Finmark: Tromsö; 
Jan.5.) (H.E.P.) 
cells of the upper epidermis have slightly undulating lateral 
walls while those of the lower are strongly undulating. Hairs 
are absent. The stomata are confined to the lower surface and 
