210 CHANGES OF THE OKGANS OF PLANTS. 



fail or become abortive for want of nourisbment ; many plants 

 wkich 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 oah where six seeds are 

 produced, but one acorn is j^erfected. 



3d. In some cases organs a^ypear from certain changes to he 

 incajxcble of performing tJieir 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 leai' 

 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 oiourishmenf^ 

 sicell and Ijecome petals j 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 i^etals 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 tlie pistils, meet with this meta- 

 morphosis, as they apj^ear to be more intimately connected 

 with the petals. 



5th. The petioles^ or foot-stcdks^ often change to leaves. This 

 may be seen in an Arabian plant. Acacia 7iilotica^ 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 ex^Dands, and appears in the form of a thick 

 leaf 



6th. The peduncles and petioles sometimes change into ten- 

 drils^ as in the vine ; this i3lant at first throws out many large 

 leaves and clusters of flowers ; but the food not being sufficient 

 to suj)port sucli a profuse vegetation, the new leaves and clusters 

 of flowers apj^ear 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. 



Tth. 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 j^ei'fcction, they 



Parts not matured — Not developed — ChaTige from excess — One organ changing to another— Pediw 

 cle3 and petioles become tendrils — Buds, how trausformed 1 



