INTRODUCTION TO BOTANY. 
29 
others become dilated, are slightly coloured 
pink, and occasionally bear a few imperfect 
leaflets at their apex ; in succession are de- 
veloped leaves of the ordinary character, ex- 
cept that their petiole is dilated and mem- 
branous, like the inner scales of the bud ; and 
finally, leaves perfect in all their parts com- 
plete the series of transitions. 
" Among the varieties of root is sometimes 
classed what botanists call a bulb, a scaly 
body formed at or beneath the surface of the 
ground, emitting roots from its base, and pro- 
ducing a stem from its centre. Linnaeus con- 
sidered it the leaf-bud of a root ; but in this 
he was partly mistaken, roots being essentially 
characterized by the absence of buds. He 
was, however, perfectly correct in identifying 
it with a leaf-bud, from which it differs in 
nothing more than in being deciduous, and 
consisting of scales much more fleshy than in 
ordinary leaf-buds. In some plants, such as 
the Tiger Lily, the leaf-buds in their usual 
position in the axils of leaves acquire a fleshy 
consistence, and are spontaneously cast off by 
the stem in the state of true bulbs. 
" A bulb has the power of propagating itself 
by developing in the axils of its scales new 
bulbs, or what gardeners call cloves {nucleus 
and adnascens of the older botanists, adnatum 
of Richard), which grow at the expense of 
their parent bulb, and eventually destroy it ; 
in this respect it behaves exactly like a leaf- 
bud after it has lengthened into a branch. 
Every true bulb is therefore necessarily formed 
of imbricated scales, and a solid bulb has no 
existence. The bulibi soldi, as they have 
been called, of the crocus, the colchicum, and 
others, are, as we shall hereafter find (see 
Cormus), a kind of subterranean stem ; they 
are distinct from the bulb, in consisting, not 
of imbricated scales, but of a solid fleshy 
mass, itself emitting buds. It has been sup- 
posed, indeed, that corms might be buds, the 
scales of which had become consolidated ; but 
the hypothesis leads to this inadmissible con- 
clusion, that, as the corm or solid bulb of a 
crocus is essentially the same, except in size 
and situation, as the stem of a palm, the stem 
of a palm must be a bulb also, which is absurd. 
In truth, the bulb is analogous to the bud that 
is seated upon the corm, and not to the corm 
itself ; a bulb being an enlarged succulent bud 
without a stem, the corm a subterranean 
stem with buds on its surface." — P. 175. 
The stems of Exogenous plants are described 
in a very detailed manner ; after which we 
come to some remarks as to the age of timber, 
a subject on which many curious notions are 
extant. In matters of this kind, theory is apt 
to run riot ; and so it would appear she has 
done in this case. Even the number of zones 
shown in a cross section of the wood, does 
not always indicate the truth, although much 
nearer than any computations based on mea- 
surement. 
Among much interesting matter relating to 
the structure of leaves, is an account of that 
of those " curiosities of vegetation," the pitcher 
plants. The leaf of a plant usually consists 
of two distinguishable parts, the lamina or 
blade, and the petiole or stalk. The " pitchers," 
as they are called, which are borne by the plant 
just alluded to, are regarded as modifications of 
the petioles of the leaves. We may perhaps 
be tempted to quote this passage at some 
future time. 
The following is an excellent definition of 
a flower, according to the ideas of modern 
botanists. Popular notions, however, ascribe 
a much more restricted interpretation to the 
term flower ; and in this respect approach 
somewhat closely to the views held by the 
ancients. The passages are selected so as to 
give a connected description of the different 
parts ; in the work itself a much ampler ac- 
count is given : — - 
" The flower is a terminal bud, enclosing 
the organ of reproduction by seed. By the 
ancients the term flower was restricted to 
what is now called the corolla, but Linnaeus 
wisely extended its application to the union 
of all the organs which contribute to the pro- 
cess of fecundation. The flower therefore, as 
now understood, comprehends the calyx, the 
corolla, the stamens, and the pistil, of which 
the two last only are indispensable. The calyx 
and corolla may be wanting, and a flower will 
nevertheless exist ; but if neither stamens nor 
pistil nor their rudiments are to be found, no 
assemblage of leaves, whatever may be their 
form or colour, or how much soever they may 
resemble the calyx and corolla, can constitute 
a flower. 
" We usually consider the flower to consist 
of a certain number of whorls, or of parts 
originating round a common centre, from the 
same plane ; but Adolphe Brongniart has cor- 
rectly pointed out the fact, that what we call 
whorls in a flower, are in many cases not so, 
strictly speaking, but only a series of parts 
in close approximation, and at different heights 
upon the short branch that forms the axis. 
This is particularly obvious in a cistus, where 
of the five sepals, two are lower and exterior, 
and three higher and within the first. The 
manner also in which the petals overlap each 
other, evidently points to a similar cause, 
although the fact of those pieces being 
inserted at different heights, may not be ap- 
parent." — P. 315. 
" The calyx is the external integument of 
the flower, consisting of several verticillate 
leaves, either united by their margins or dis* 
