CHANGES OF^ THE ORGANS OF PLANTS. 
215 
upon the pistils of another; the seed thus formed will produce a 
plant resembling both. 
Varieties are a less important distinction than races ; they are not 
continued by means of the seed, but produced by grafting or contin- 
uation of the plant under some new circumstances. 
Variations denote the shghtest kinds of difference ; they are occa- 
sioned by pecuHarities of climate, soil, moisture, dryness, &c. 
Degeneration or change of the Organs of Plants. 
The organs of plants, owing to peculiar causes, often experience 
a metamorphosis, and instead of their usual appearance exhibit 
anomalies, or vegetable deformitie>=!. 
We here use the term deformity, as signifying any variation from 
the ordinary course of nature. The causes which produce these 
changes are, 
1st. The adhesion of parts usually separate ; thus we often see 
flowers, leaves, and fruits united, and appearing double. 
Some writers, among whom is the celebrated French botanist 
De Candolle, assert, that a single petal which form.s the corolla of 
many flowers, as the stramonium or the blue-bell, is in reality com- 
posed of several petals which become soldered, or cohere together 
before the flower expands. The same writers consider a mono- 
sepalous calyx to be composed of several little leaves thus united 
before their development. 
2d. Changes are occasioned by a want of sufficient vigour in the 
plant to bring all parts to maturity. Some of the seeds thus often 
fail for the want of nourishment; many plants which in one flower 
produce several seeds, often ripen no more than one. The horse- 
chestnut has six seeds, but seldom matures more than two; in the 
blossom of the oak where six seeds are produced, but one acorn is 
perfected. 
3d. In some cases organs appear from certain changes to be inca- 
pable of performing their original offices, and thus exhibit deformi- 
ties; as where a bud, which, for want of sufficient nourishment, or 
some other cause, does not develop itself into a leaf, but forms a 
permanent protuberance or swelling upon the stem. The prickly 
pear exhibits a thick and expanded stem, which is formed of leaves 
imperfectly developed. 
4th. The stamens and pistils, through excess of nourishment swell 
and become petals ; all double flowers are formed in this manner. 
The poppy in its natural state has many stamens, and but four pe- 
tals ; but you often see double poppies, with scarcely the vestige ot 
a stamen left; the same change may be observed in the rose, which 
naturally has but five petals and many stamens and pistils, but in a 
very full double rose, scarcely any appearance of either stamen or 
pistil is to be seen. The stamens, more frequently than the pistils, 
meet with this metamorphosis, as they appear to be more intimately 
connected with the petals. 
5th. The petioles or foot-stalks often change to leaves. This may 
Ije sef'n in an Arabian plant. Acacia nilotica, which furnishes the 
gum arable. This tree at first exhibits upon one petiole six or eight 
pair of leaves ; this number every year becomes less, until all the 
leaves disappear; the petiole then retaining all the nourishment 
which before was distributed to the leaves, flattens and expands, and 
appears in the form of a thick leaf 
Varieties— Variations— Changes of the organs of plants— Deformities— 1st cause of 
ihe changes of plants — 2d cause of change — 3d case :n which changes appear — 4th, 
k)uble flowers, how caused — 5th, changes in petioles. 
