Gbeensill. — Leaf-structure of Coprosma. 343 



occurrence. On the upper side of the leaf the presence of the 

 pits is denoted by well-marked protuberances. The structure 

 of the leaf and tissues round the pit (fig. 1) is as follows : In 

 transverse section on the upper surface of the leaf there is 

 first a cuticle (cu.) with an irregular outline ; beneath this a 

 layer of small epidermal cells (ep.) ; next a hypodermal layer 

 of colourless, roundish cells, elongated in a transverse direc- 

 tion, and functioning as a storage layer for water (st. I.) ; 

 beneath this again a layer of cells (ho.) approximating to 

 the storage layer, but containing in parts a few chlorophyll 

 granules, though in other parts they are quite empty. This 

 layer is longer than broad, thus approaching in shape the 

 palisade cells (p. p.) of the next few rows. These palisade 

 cells, which are typically elongated in a longitudinal direc- 

 tion, contain a great number of chlorophyll corpuscles (chl.), 

 crowded rather closely together towards the centre. They 

 also contain, in almost all the species examined, drops 

 (a.) of what appeared to be oil. Beneath the cells of 

 the palisade parenchyma are those of the spongy paren- 

 chyma (sp.) of irregularly shaped cells, with numerous air- 

 spaces between. They also contain numerous chlorophyll 

 corpuscles (chl.), though not so many nor so closely crowded 

 as those of the palisade parenchyma. In the spongy paren- 

 chyma, too, in all the species I examined I found numerous 

 bundles of crystals or raphides (r.). Beneath the spongy 

 tissue, which occupied the greater part of the leaf-area, is the 

 epidermis of the lower surface (/. ep.), in which are numerous 

 stomata (st.). On the lower surface there is also a cuticle (cu.) 

 with the same irregular outline as that of the upper surface. 

 The stomata are enclosed by two guard-cells (g.), in trans- 

 verse section smaller and different in shape from the ordinary 

 epidermal cells. The epidermal cells next to the guard- 

 cells are modified to form subsidiary cells (s.), into which 

 the guard-cells fit, and which overhang the guard-cells. The 

 pit is circular in outline, with projecting rims. Its epider- 

 mis (p. ep.) is continuous with that of the lower surface, and 

 similar to it. Above the pit epidermis are two layers of 

 roundish cells (c. I.), slightly elongated in a transverse direc- 

 tion, and colourless in contrast with the spongy tissue im- 

 mediately surrounding the innermost layer. A few of the 

 epidermal cells are occasionally prolonged into papillose pro- 

 jections or hairs (h.), which are usually unicellular, though I 

 saw one such hair consisting of two cells. These hairlike 

 projections are not very numerous, and many pits appeared to 

 be without them. Dr. A. N. Lundstrom regards these pits as 

 hairless. There are no stomata in the pits either of this 

 species or any of the other species I examined. The vascular 

 bundle (v. b.) of the midrib is seen beside the pit, with xylem 



