210 
CHANGES OF THE ORGAJ^S OF PLANTS. 
fail or become abortive for want of nourishment ; many plants 
wbicb 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 hlossom of the oak where six seeds are 
produced, but one acoim is perfected. 
3d. In some cases organs a/pjpear from certain changes to he 
inca/pahle of performing their original offices^ and thus exhibit 
deformities ; as where a bud which for want of sufficient nour- 
ishment, 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 hecome petals ; all double flowers are formed in this 
manner. The poppy in its natural state has many stamens, and 
but four petals ; but we often see double poppies, with scarcely 
the vestige of a stamen left ; the same change may be observed 
in the rose, which naturally has but five petals and many sta- 
mens and pistils, but in a very full double-rose scarcely any 
appearance of either stamen or pistil is to be seen. The sta- 
mens, more frequently than the pistils, meet with this meta- 
morphosis, as they appear to be more intimately connected 
with the petals. 
5th. The petioles^ or foot-stalks^ often change to leaves. This 
may be seen in an Arabian plant. Acacia nilotica^ which fur- 
nishes the gum-arabic. This tree at first exhibits upon one 
petiole six or eight pair of leaves ; this number every year be- 
comes less, until all the leaves disappear ; the petiole then re- 
taining all the nourishment which before was distributed to the 
leaves, flattens and expands, and appears in the form of a thick 
leaf 
6th. The peduncles and petioles someti7nes change into te^i- 
drils, as in the vine ; this plant at first throws out many large 
leaves and clusters of flowers ; but the food not being sufficient 
to support such a profuse vegetation, the new leaves and clusters 
of flowers appear smaller ; the nourishment becoming still more 
scanty, at length neither flower nor leaf is developed, and the 
peduncle and petiole become tendrils which by attaching them- 
selves to some firm bodies serve to sustain the rich fruit which 
is perfected on the lower parts of the branch. 
7th. Buds are transformed into thorns. — ^When a plant forms 
more buds than it can nourish, some of them do not develop 
branches and leaves, but becoming hardened by the accumula- 
tion of sap which is insufficient for their full perfection, they 
Parts not mat-ired— Not developed— Change from excess— One organ changing to a/ other- Pedan 
el«s and petioles become tendrils — Buds, liow transibrmed 1 
