BUD 



BUD 



bark in their vicinity." The pith is therefore 

 considered as the first or most essentiil rudi- 

 ment of the new plant; like the brain or spinal 

 marrow in animais. 



In such plants as have hollow stems, the 

 central cavities, though not filled with pith, are 

 supposed to be lined with it ; and in some this 

 is not only the case, but, whenever a new bud 

 is formed on the summit of the ascending stem, 

 or in the bosom of a leaf, a membrane co- 

 vered with this substance divides the cavity, 

 which distinguishes one bud from another. 

 And in slicing away that part of the stem of 

 others where the new lateral bud adheres, the 

 pith in the centre of the bud is seen to commence 

 near that membrane, which lines the stem, and 

 to pass through the circle of different vessels 

 that constitute the ascending caudex of the new 

 bud, while the descending caudex of it is se- 

 creted in the manner just explained. 



Thus the bud is at first nourished in the 

 bosom of its parent leaf, by a secretion from 

 the vegetable juice suited to the purpose, con- 

 tinuing to he supported in the same way in an- 

 nual herbs and evergreen trees, till it protrudes 

 and expands its own leaf: but if it be a bud of a 

 plant of the deciduous kind, that must lose its 

 parent leaf in winter, a reservoir of nutriment 

 is prepared for it in the roots of some sorts of 

 plants, such as carrots, turnips, liquorice, 

 fern, &c, and perhaps in the roots and albur- 

 num of trees. Hence, in the spring the vessels 

 of each bud of a tree absorb moisture from the 

 earth, and propel it upwards through the roots 

 and sapwood, where it is blended with a nutri- 

 tious material, often discharged from wounds 

 in the bark. And at this period the buds 

 begin to swell out, and to send roots down- 

 wards from their caudexes into the ground ; the 

 outer texture of these caudexes constituting a 

 new bark over the old one, consisting of dif- 

 ferent sorts of vessels. At the same time each 

 bud likewise puts forth a leaf, or respiratory 

 organ, resembling in some manner the lungs of 

 animals, but differing in this respect; that the 

 leaf stands in need of light as well as air for 

 the purpose of perfect respiration. The dif- 

 ferent embryons of the leaf-bud being in this 

 manner provided with their adapted organs of 

 respiration, and various new ones formed in 

 the summer season in the different leaf-buds, 

 they now begin to pullulate in succession, each 

 as in the first having its appropriate leaf, which, 

 as they come forward in order, constitute the 

 annual sprigs or shoots of trees, being of con- 

 siderable length in some, as the vine, willow, 

 &c, having a great number of new leaves. 

 Consequently, when the spring frosts or insects 



destroy the first set of leaves, as often happens 

 in particular sorts of plants, they are succeeded 

 by a second set from the second embryons of 

 the same bud. But when the floral leaves are 

 destroyed, as happens in some cases to fruit- 

 trees, the fruit in the pericarp is not destroyed 

 as in the first embryon of the leaf-bud, as it is 

 supported by the system of absorbing vessels of 

 tbe caudex, and the roots of the flower-bud, 

 which form a part of the bark and run into the 

 earth; but is more sour, and less perfect, on 

 account of the juices from which it is secreted 

 being; less perfectlv oxygenated. 



About the middle of the summer season there 

 is mostly either a new leaf-bud or flower-bud 

 formed in the axilla of each leaf; becoming a 

 branch the succeeding year when a leaf-bud, 

 and affording many other leaves and buds; but 

 when a flower-bud, the growth stops, being 

 terminated in the seed. In the more vigorous 

 growth of the plant, leaf-buds are wholly or 

 chiefly afforded ; but in the more advanced state 

 of growth, when the vessels of the bark are more 

 fully elongated, and the nutritive fluids less abun- 

 dantly provided, or the buds become in a more 

 mature state, the production of flower-buds takes 

 place. 



On these grounds, Doctor Darwin has con- 

 cluded that the grafts taken from vigorous seed- 

 ling apple-trees do not bear fruit till they are 

 many years old; while those cut from weak old 

 trees bear abundantly in a very few. The same 

 principle holds good in various other cases. It 

 is concluded that the facility of forming the 

 long caudexes of the new buds which constitute 

 the new filaments of bark, promotes the increase. 

 of leaf-buds, and affords a vigorous luxuriant 

 aspect to the trees; while the difficulty of pro- 

 ducing these new caudexes increases the quan- 

 tity of flower-buds, and lessens the vigorous ap- 

 pearance of them. It is likewise conjectured that 

 the generation of buds demands a less perfect ap- 

 paratus than that of seeds, as the former con- 

 stantly precedes the latter, in trees as well as 

 herbs. Hence the age of the plant is another cir- 

 cumstance of consequence to the production of 

 flowers, fruit, and seeds, as isexemplified in tulips, 

 hyacinths, as well as in the apple and pear tree. 



It is believed by some, that the buds formed 

 in the summer may be either converted into 

 leaf- or flower-buds, according as the branch is 

 more or less strong or vigorous in its growth, 

 even after the vegetable embryons are formed. 

 In proof of which, Dr. Darwin observes, that 

 " if the upper part of a branch be cut away, 

 the bud^ near the extremity of the remaining 

 stem having a greater proportional supply of 

 nutriment, and possessing a greater facility of 

 2 D 2 



