168 
THE FLORIST S JOURNAL. 
latent or protruded an active bud : by a parity of reasoning, 
buds are always present immediately above where leaves are 
connected with the stem, and to the non-developement of these 
at the time of their organisation may be attributed the appear¬ 
ance of those adventitious branches which we sometimes see 
sprouting from a hardened stem: it is this property in a great 
degree which enables us to manipulate at our pleasure the 
plants and trees under our care; and it also admits of being 
turned to account in the processes of propagation. 
Leaves consist principally of cellular tissue, which is traversed 
bv the vascular system. In exogenous plants these vessels may 
be seen interlacing each other, and forming a network of ex¬ 
treme delicacy ; and in endogenous plants they run throughout 
nearly parallel with the margin, and branch very little, if at all: 
they are, in all cases, connected with the vessels of the stem. The 
cellular matter of leaves is caWedt parenchyma, and, together with 
the vessels, is covered by a skin called the cuticle, which has, on 
the occasion already noticed, been alluded to as being itself com¬ 
posed of cellular matter in a state of extreme compression. In 
water-plants that have their leaves submersed, the cuticle is 
absent, but it exists on all the parts of plants which are exposed 
to the atmosphere, except the stigma. The arrangement of 
the bladders, or cells of tissue, forming the cuticle, differs mate¬ 
rially from that of the parenchyma, for in the cuticle they are 
much depressed in figure, and adhere firmly, assuming a variety 
of outline in consequence of pressure ; they differ, also, in their 
nature, being perfectly transparent and colourless : probably 
they are filled with air. There is no trace of vessels either 
existing or terminating in the cuticle of the leaves, and there¬ 
fore the opinion entertained by some physiologists, that spiral 
vessels end in the stomates must be laid aside. Stomcites are 
small pores or openings of the cuticle ; they vary much in their 
position; thus in some leaves they exist only on the under side, 
in others, on the upper surface only, and in some on both. 
Floating leaves have them only on the upper surface, whilst 
leaves whose margins are vertical, or nearly so, have them on 
both sides equally. In succulent plants they are very scanty 
and imperfect. It has been calculated, that the leaves of an 
orange tree and those of a Mesembryanthemum vary in this 
respect in the proportion often to one. 
( To be continued.') 
