in PLANTING. 



plants are perfected. It is in these early stages of growth, that the 

 foundation is laid for the future health, beauty, and vigorous growth of the 

 tree. The fibres of the root, with the minute spongeols before mentioned, 

 mm imbibe and send up the food of the plant to the leaves, where being 

 spread out to the influence of solar light, heat, and atmospheric air, it is 

 elaborated and returned through the foot-stalk by the longitudinal vessels 

 of the inner bark to the root, depositing in its course, or in conjunction 

 \\ith the original fluids of the cellular texture forming, the various sub- 

 stances and secretions peculiar to the tree. That the sap ascends by the 

 longitudinal vessels of the alburnum, sap, or soft wood, and descends by 

 those of the inner bark, seems to be proved by the experiments of Mr. 

 Kniu'ht and others, who have more intimately investigated this part of the 

 subject. That a lateral movement of the sap goes on at the same time, 

 and in conjunction with the ascending and descending movement, appears 

 equally certain*. Kvery individual leaf of a tree is furnished with its own 

 particular series of vessels for the course of the sap, and not only prepares 

 and elaborates the sap for the increase of substance of its own branch, 

 but also for that of the parent stem and root. Hence it is that trees re- 

 gularly furnished with branches from the base upwards have more taper- 

 ing strms, tnan trees with branches confined to the upper half of the stem, 

 the increase being equal, from the point where the branches begin, down- 

 wards to the root; or, in other words, whatever length of stem from the root 

 upwards is destitute of branches, that part of it from the period of losing 

 them increases in size equally throughoutf. Without a just knowledge of 

 this principle in the economy of vegetable life, the important process of 

 pruning in the culture of forest-trees cannot safely be performed by the 

 forester: that the sap never ceases wholly to move J is evident in the in- 

 crease of the roots and buds during winter when the plant is leafless; but 

 its ascent is particularly distinguished for greater force and activity at two 

 periods of the year, spring and midsummer. The ascent in spring is 

 the strongest, and continues until midsummer, gradually diminishing in 

 force as the new branches and leaves are perfected. This generally takes 

 place about the beginning of July, when an apparent cessation of ascend- 

 ing motion in the sap immediately succeeds, and continues usually for the 



* The sap in ascending is farthest removed from the action of solar light, heat, and 

 atmospheric air. in descending it is nearest to these important agents, receiving their im- 

 pulse through the medium of the green cellular tissue or parenchyma. The offices of this 

 organ in trans} ir.ition and inhalation, may he compared to that of an universal leaf cover- 

 ing every part of the stem and branches of a tree. 



f This fact may he demonstrated most conveniently, hy pruning the lateral branches 

 off (mite close to the stem of a young fast-growing tree, leaving a certain numher to form 

 a top, and to keep up the growth of the plant. 



J The term curmfation lias been objected to as improper for describing the course of the 

 movement of the sap in plants; because a point from whence the movement, begins, and to 

 which it again return-, fas for instance, the heart in animals,) has not been discovered in 

 plants ; for in these the sap is periodically exhausted in the increase of the substance of the 



::id its pi. ice periodically supplied from the toil to the spongeols of the roots. The term 



lical is here understood to apply to the efiects observed, by the practical planter, of 

 the spring growth, midsummer growth, and leafless or winter cessation of growth, an- 

 nu.dly in the pio^ns-, ol' < '-live. That the roots of fhese plants'i as lo:, 



their Vital ; continue, without intrntiissiiin,hi imbibe fluid or pabu- 



lum from the soil, however small in tpiantity that may he at ceitain seasons, seems highly 

 probable ; as also that a movement or circulation of the fluids of the cellular texture, how- 

 ever languid it may 1 . U in the le.ii Hut there are plants, such as the 

 hyacinth, potatoe, onion, \c. \c., which remain two or three months annually during 

 their i existence, without a possibility of imbibing anything whatever by their 

 lets, or spongeols, inasmuch an during that period of their existence they are 

 destitute of these organs wherewith to imbibe. 



