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THE COURSE OF THE SAP IN PLANTS. 
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perfect observation, and since no such thing as Endogenous growth, in the sense originally intended, 
does exist in the Monocotyledons, the names should be given up. 
In the Monocotyledons, the simplest forms of stem are composed of amass of cellular tissue strength¬ 
ened by a number of completely separate fibro-vascular bundles (consisting of an assemblage of spiral, 
and annular cells, with ducts and woody tissue,) which, when carefully traced, are found to arise just 
within the rind of the stem, to pass more or less slantingly upwards and inwards, till they nearly 
reach the middle, then to turn out again to arrive finally at the leaves, into which they pass out to 
form the ribs and veins. As they exist in large numbers, they form an almost inextricable interlace¬ 
ment by their crossings in the different parts of them course, but they remain quite isolated from each 
other, imbedded in the cellular tissue of the stem, and after the first year alter only by increasing in 
density from the addition of woody deposits inside their cells. In herbaceous stems they are readily to 
be detected as woody strings running through the spongy cellular tissue; in the arborescent Mono¬ 
cotyledons, such as the Palms, they frequently become consolidated into one mass, by the cells of 
the general tissue of the trunk becoming converted into solid wood, but even then their isolated 
nature may be distinguished by their appearing as separate spots in a cross section. The large 
orifices seen in a cross section of a common cane are the ends of large ducts, and each hole marks the 
centre of an originally isolated bundle. Such stems only grow by the addition of new parts, totally 
distinct lengths of the stem with new isolated bundles, while the older portions only grow by mere ex¬ 
pansion or consolidation of parts already existing. The roots of Monocotyledons are traversed by fibro- 
vascular bundles which arise in contact with the ends of those of the stem, just beneath the 
rind ; they form a solid core to the fleshy roots, and enter all the sub-divisions. It should be observed 
here, also, that the roots of Monocotyledons are always lateral or accessory, as they are called, these 
plants never producing a tap-root, that is, a root forming a direct continuation of the stem downwards. 
The peculiarities of the stems of Monocotyledons may be studied by examining the course of the fibro- 
vascular bundles, in such plants as the Flag, which has a creeping, underground stem or rhizome, in 
the Asparagus ; in the little conical solid part from which the scales of bulbs arise, in the Grasses, in 
Canes, and, where accessible, in Palms; but it requires much care and patience to investigate them 
thoroughly. 
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THE COUPvSE OF THE SAP IN PLANTS. 
By J. TOWERS, Esq., C.M.RS. 
S UBSEQUENT to the few remarks made in a recent article on the descent of the sap, others have 
suggested themselves, partly in consequence of a paper in The Gardeners’ Chronicle of June 29th 
last, by Professor Henslow of Hitcham, to wddch we must take the liberty to devote considerable 
attention. That gentleman says, “ I consider the fact established that an absorption of water, with 
whatever it may hold in solution, is constantly taking place through the extremity of the rootlets, and 
that this ‘ crude sap’ is carried forward either through intercellular passages, or through particular 
vessels (tubes, of which there still seems to be need of better proof), or through both, by a force 
which acts by ‘propulsion,’ and not by ‘ attraction.’ The celebrated experiment by Hales upon the 
Vine, and the experiments of Dutrochet and others, have established this.” 
We are not now considering the actual “ descent of the sap” by “ force of gravitation”—like that of 
water or quicksilver from the top to the bottom of a tube, suggested by some : the object pointed to by 
Prof. Henslow is widely different from that; and it involves those very mysterious phenomena which 
have so long been hampered by many conflicting theories. Mr. Knight of Dovmton, appears to have 
approached the truth when he stated that the sap ascended through cells —and so far he met, and 
interpreted the theory of Dutrochet’s endosmose, whereby fluids of different densities were shown to 
permeate through membranous tissues, and commix, till they mutually acquired an equal, or 
nearly equal density. The question, however, which now claims our notice arises out of the opinion 
hazarded by Prof. Henslow, that the sap is propelled—and not attracted, upwards. 
What—I would ask—is propulsion—what and where its agent ? The ground is unquestionably 
the medium which supports the roots of a plant, through which also they ramify in search of food. 
The plant is an organized body, endowed with a vital principle, and pervaded by vitalized fluids—which 
like the living blood of animals, resist the decomposing action of chemistry, and effectually preserve 
the entire body from putrefaction so long as the vital principle is maintained. Now, if a living plant 
require, and seek its food—whether by an act of volition, or as stimulated by an agent from without, 
by what term can we define the act by which it draws appropriate food from an inert mass of earth, 
through a spongy tissue of rootlets, into its ascending cellular system—other than by that of attrac¬ 
tion ? I have long been convinced that to Electricity we must refer for the interpretation of all the 
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