162 



CASSELL'S POPULAE G-ARDENING. 



vary greatly in different cases, and these diver- 

 sities serve, together with those connected with the 

 shape and disposition of the leaf, as means of dis- 

 crimination between different plants or groups of 

 plants. It must suffice here to give one illustration 

 only. In the majority of Dicotyledonous plants, 

 those in which the seedling plant has two cotyledons, 

 the group comprising most of our trees and shrubs, 

 the ribs of the leaf, or their ultimate branches, are 

 arranged in a reticulate or net-like fashion, so that 

 there are angular spaces between them. In the 

 larger number of Monocotyledons (Palms, Lilies, 

 Grasses, &c.) the ultimate veins are not netted, but 

 somewhat straight and nearly parallel, so that the 

 interspaces are either long and narrow, or if angu- 

 lar, then four-sided, not polygonal. Even in cases 

 where from the thickness of the cellular tissue, or the 

 opacity of the epiderm, the veins are not readily 

 conspicuous, the arrangement can be determined by 

 simply tearing the leaf. Where the veins run in a 

 nearly straight direction, as in an Iris-leaf, for 

 instance, the edges of a tear will be nearly straight ; 

 but where they form net-like meshes, as in a Cab- 

 bage-leaf, then the edges of the tear wiU be angular 

 and irregular. 



The Skin of the Leaf.— It remains now to 

 speak of . the epidermis or skin. This, like the 

 other parts of the leaf, is subject to variation in 



Pig. 50.— Epidermis of a Leaf (magnified) showing Stomata. 



different plants, and it is usually somewhat diiferent 

 on the upper and lower surfaces respectively. It 

 most generally consists of a layer of flattened cells, 

 destitute of chlorophyll. Those on the upper sm-- 

 face are closely packed, with no interspaces between 

 them. Those on the lower sm-face are interrupted by 

 a greater or less number, sometimes by an immensely 

 large number, of pores called " stomata " (Eig. 50). 

 These are apertures communicating with the outer 

 air, and affording access to the interior spongy por- 



tions of the leaf, thus allowing of the passage into 

 or out of the leaf, according to cii-cumstances, of 

 gases or liquids. The entry or exit is regulated by 

 two or more "guard-cells," which encompass the 

 aperture and close it or open it, according to circum- 

 stances. The guard- cejls are enabled to do their 

 work by differences in their degree of fulness ; if 

 full they are distended and the aperture is closed ; if 

 relatively empty, the orifice is unobstructed. In the 

 case of water-plants there are no stomata, at any 

 rate in the submerged portions. In thick-rinded^ 

 succulent plants, natives of dry and hot countries^ 

 where evaporation would be excessive were there not 

 means to prevent it, there are few or no stomata. 

 In cases where, as in the Iris, Gladiolus, or Pink, 

 the leaf is of the same colom" on both surfaces, there 

 the number of these pores is about the same on both. 

 sides. 



These few illustrations must suffice to show how 

 the form, arrangement, and internal structui-e of 

 leaves are co-related to the duties they have to per- 

 form, and to the circumstances under which their 

 work has to be accomplished. The yoimg gardener 

 should lose no opportunity of familiarising himself 

 with details of this character, which will furnish 

 him, if properly used, with a clue to successful man- 

 agement more reliable than any book knowledge or 

 precept. 



THE HAEDY FEUIT GAEDEIST. 



By D. T. Fisk, assisted by Y/illiam Carmichael. 



THE APPLE. 



WITHOUT disparaging the worth or luscious- 

 ness of any other fruit, this is without 

 doubt the most valuable of all our hardy fruits. It 

 is likewise so popular and universally esteemed as to 

 merit the distinction of being called the national 

 fruit of Great Britain and Ireland. It merits this 

 distinction on the double ground of its popularity 

 and parentage. . The Wild Crab [Fyrus malus), the 

 not very remote progenitor of our cultivated varie- 

 ties, is indigenous to Britain and large . portions 

 of the cooler parts of Europe, and our best Apples 

 are but highly-developed Crabs — marvellous ex- 

 amples of the improvement of species by the gradual 

 processes of evolution and cultivation. 



The popularity of the Apple is so great that it is 

 hardly an exaggeration to affirm that every one eats 

 Apples, either raw, cooked, or preserved ; and should 

 any decline to eat them, they probably drink tnem 

 in the form of cider, wine, or brandy. Apple wine, 

 "however, has never become popular, though cider 

 has become a formidable rival to, and fimost a com- 



