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THE COURSE OF THE SAP IN PLANTS. 
THE COURSE OE THE SAP IN PLANTS. 
By J. TOWERS, Esq., C.M.H.S. 
’[/HATEYEP. may be the result of the arguments, pro and con . the progress of the sap, raw and 
elaborated, will be, in some degree, elucidated by investigating phenomena that follow the opera¬ 
tions of budding and grafting :—A strong shoot had been produced hi the spring of 1849, from the root of 
a Noisette Rose. By the last week of August it had grown to the height of about seven feet, and was 
nearly an inch in the girth at five feet from the ground,—the point where a fine bud was inserted at 
that period. The stock and the scion were both very full of juice ; too much so, perhaps, hi the opinion 
of most gardeners : the bark separated perfectly, and with ease from both; and, consequently, the 
union was immediately effected. The bud remained green but latent, till, by the influence of spring, it 
sprouted, and progressively developed seven main shoots, winch required much cautious care to support 
them from the powerful winds of the late summer. Some of the shoots were more than thirty niches 
long, and have been cut back; thus furnishing many buds to others, most of which appear to have been 
successfully inserted. At the present date (September 1850), the results are,—a bold and pretty equal 
head, and a stock enlarged to 1 f inch in the girth throughout, in which the bark below the insertion 
of the bud is furrowed with some brownish stripes, evidently of organized matter produced by the bud. 
With these faithful data before us, and knowing, as every practised observant gardener assuredly 
does know, that the stock below the bud, though headed down to the point of insertion, retains its 
own individual character, uninfluenced by the qualities or size of the head it supports, we put the 
question :—How, and by what instrumentality is the stock sustained and so enlarged, as we perceive 
it to be, in roses somewhat; but in many trees to an enormous extent ? 
We have been taught that each leaf of a tree, at least every progressive development of the head, 
furnishes some substance, more or less, to the stem. Be it so ; yet we find by experience, that, be the 
size and increase of the head and stem what they may, the development of the latter retains precisely 
the character and qualities of the original stock ; while those of the former remain faithful to then- 
parent tree or shrub. At this point let us refer to principles 
The success of budding mainly depends upon the preservation of what is called the root of the bud. 
Tills root may be traced to a certain white line or track of pithy matter that is observed to traverse 
the woody layers in cutting a twig or branch across at the spot whence a bud emerges. This fact, 
viewed connectedly with the extinction of the pith in full grown and old stems, leads to the opinion 
that the pith ( medulla ) is the original magazine of nutrimental matter to all buds, and that the buds 
contain and carry onwards the matter of the pith; the natural termination of the tree’s life being 
coincident with the final development of the buds (the pre-organized germs of Duhamel ?), and the 
total exhaustion of the medullary matter. 
A Treatise on Vegetable Physiology by the Society for Diffusing Useful Knowledge, published 
many years since, contained the following philosophic remarks :—“ No determinate period is fixed for 
the protrusion of the germ into a bud; but at whatever time tins may happen, its course is traceable, 
from the medullary sheath to the surface on which it appears, by a pale stream of parenchymatous 
matter traversing each annual concentric layer. But this track only marks the advance of the vital 
speck or germ to the surface of each annual belt of wood, and is altogether useless so far as regards the 
germ, except in the belt on the surface of which it is seated, with the life of which, indeed, its own 
vitality is intimately connected. Destroy this, and the germ becomes extinct: augment its vital 
energy, and the germ is unfolded into a perfect bud and branch; but leave tilings as they are, and the 
germ will advance to the surface of the next year’s belt of wood, and so on progressively.” 
We obtain much truth in the above theory; but not a full interpretation of the wondrous facts 
which are daily witnessed. The buds and shoots which frequently emerge from the stock are always 
true to their native character : they are amputated so soon as they are observed, and therefore cannot 
promote the enlargement of the stem. Yet that stem does enlarge by each annual layer of the new 
alburnum and liber. The head, in all its developments, is true to its kind, and all the leaves upon it 
are retained; the currents within it, be then- course as it may, seem to be exclusively devoted to the 
perfecting of its own members ; and yet, one would suppose that some fluids must pass into the stem, 
and be there distributed horizontally through the channels of the convergent medullary processes. 
Two important facts seem to be indisputably established : the first is, that every hud produced in the 
head of a tree, whatever the size and age, had been preorganized and latent in its first parent germ; 
the second, that the entire stem (its wood and bark), however bulky it may become, is normally pure in 
its character, never suffering deviation or change. What then becomes of the crude doctrine of the 
sap’s descent from the head to the foot P 
