MINDTE STRUCTURE. 



63 



leaf of Dendrohium noldle is thin, and its means for the storage of 

 water is limited, presumably therefore needing diffused rather than 

 direct sunlight as under the influence of the latter, evjiporation would 

 be too rapid. 



Fig. 2 shows a similar section of a leaf of Dendruhlum Jenkinsii. The 

 leaves of this species are small and thick, with three layers of cells 

 called from their peculiar appearance palisade cells (3a in figure), 

 underlying the hypodermal water cells, and which are always full of 

 deep-coloured chlorophyll grannies, their numbers, size and intense 

 coloration being always in direct relation to the amount of light. When 

 these palisade cells are well developed it is a sure sign that in their 



Fig. 3. Transverse section of leaf of (Jattleya intermedia across the mid-rib, X 30 diameters. 



1, upper, 2, lower epidermis ; 3, fundamental tissue of soft thin-walled cells containing chlorophyll 

 granules ; 4, Hbro-vaMCular bundle of midrib ; (i, smaller bundles. 



native country the [)lants are expo.sed to bright sunshine ; wliilsl on 

 the other hand their abundant supply of chlorophyll enables them to 

 endure adverse conditions Ijetter than less richly endowed i)lants can 

 do. 



Fig. 3 shows a transverse section of a leaf of Caff/eija /nternte(/ia at the 

 midrib. The cells of the upper part of the fundamental tis.sue are 

 much elongated, approaching the palisade form and are filled with 

 chlorophyll granules. The general structure comi^ared with that of the 

 lahlata Cattleyas is simpler, thus aflbrding another distinctive mark 

 between the two-leaved and usually liing-stemmcd and the one-leaved 

 shovt-stcmmed Cattleyas. It is a remarkable fact too, that similar 



