388 



STRUCTURE OF PHANEROGAMIC PLANTS. 



tares. Even the commonest trees, shrubs, and herbaceous plants, 

 yield specimens that exhibit a varied elaboration of design, 

 which cannot but strike with astonishment even the most cursory 

 observer ; and there is none in which a careful study of sections, 

 made in different parts of the stem, and especially in the neigh- 

 borhood of the "growing point," will not reveal to the eye of the 

 scientific Physiologist, some of the most important phenomena of 

 Vegetation. Fossil Woods, when well preserved, are almost 

 invariably silicified, and require, therefore, to be cut and polished 

 by a Lapidary. Should the Microscopist be fortunate enough to 

 meet with a portion of a calcified stem, in which the organic 

 structure is preserved, he should proceed with it after the man- 

 ner of other hard substances which need to be reduced by grind- 

 ing ( 108-110). 



245. Structure of the Cuticle and Leaves. On all the softer parts 

 of the higher Plants, save such as grow under water, we find a 

 superficial layer, different in its texture from the parenchyma 

 beneath, and constituting a distinct membrane, known as the 



FIG. 180. 



FIG. 181. 



Cuticle of Leaf of Yucca. 



Cuticle of Leaf of Indian Corn (Zea Mais). 



Cuticle. 1 This membrane is composed of cells, the walls of which 

 are flattened above and below, whilst they adhere closely to 

 each other laterally, so as to form a continuous stratum (Fig. 184, 

 a, a). Their shape is different in almost every tribe of Plants ; 

 thus in the cuticle of the Yucca (Fig. 180), Indian Corn (Fig. 

 181), Iris (Fig. 183), and most other Monocotyledons, the cells 

 are elongated, and present an approach to a rectangular contour ; 

 their margins being straight in the Yucca and Iris, but minutely 



1 The term epidermis is applied to this membrane by many Vegetable Physiologists, 

 on account of the analogy it seems to present to the epidermis of Animals; but as 

 epidermis means a membrane that lies upon the derm or " true skin," and as no such 

 subjacent layer exists in the Plant, the transference of the designation is altogether inap- 

 propriate. It would be much more correct to designate by the name cutis or derm what 

 is ordinarily denominated the Cuticle ; and to reserve the term epidermis for the thin 

 pellicle which may be sometimes detached from it ( 247). 



