354 



Tr ansae tions. — Bo tany . 



dermal layers of the upper surface, which serve to store 

 up water. The colourless layers around the pits, when 

 present, would serve to store up the water absorbed by 

 the epidermal cells and hairs. These epidermal cells and 

 hairs could not absorb water if empty of living contents ; 

 but this is not the case, as they contain protoplasm and nuclei. 

 This is the case also with the colourless layers. The tufts of 

 hairs at the opening of the pits of Coprosma petiolata may 

 serve to suck up water without it actually entering the pit. 

 Again, the position of the pits, between the midrib and veins 

 of the leaf, is well adapted to the taking-up of water by the 

 vascular bundles of the leaves, and its transference in this way 

 to the different parts of the leaf. The position of the pits, of 

 course, opening on the under-surface of the leaf, is not favour- 

 able to the absorption of water ; but the absorption cavities of 

 other plants which are similarly situated can absorb water 

 without any difficulty in spite of the position — e.g., the leaf of 

 the cowberry (Vaccinium vitis-idcea) . The presence of dust 

 and other foreign matters in the pit cavities, too, seems to in- 

 dicate that it was washed there by the rain. 



Lettering used in Figures. 



EXPLANATION OF PLATES XLI.-XLIV. 



Plate XLI. 



Transverse section, leaf and pit of C. baueri. 

 Transverse section, young leal and pit of C. baueri. 

 Surface section, leaf and pit of C. baueri. 

 Under-surface leaf of C. baueri : life size. 

 Under-surface leaf of C. lucida : life size. 



Plate XLII. 

 Transverse section, leaf and pit of C. lucida. 

 Transverse section, young leaf and pit of C. lucida. 

 Transverse section, leaf and pit of C. propinqua. 

 Longitudinal section through hair from pit of C. lucida (stained). 



