105 
GARDENING AS A SCIENCE. 
VEGETABLE PHYSIOLOGY.— No. V. 
The vascular si/stem of plants now claims attention, and in commencing our 
remarks, we at once disclaim any pretensions to explain what are called Elementary 
organs : we know not anything of elements in organization ; but, as in plants more 
or less mature, we can trace a system of vessels and cells, all of which, it is certain, 
must be essential in performing vital functions, we can only presume that in 
extremely young and immature subjects, the organs termed elementary are, in fact, 
rudimental^ the miniature representatives of what they will ultimately become : 
the analogy throughout organic life is herein, we believe, perfect and complete. 
Keith, in his Physiological Botany^ has some very pertinent remarks, which 
now apply. " It is," he observes, " much more likely that the rudiments of all 
the different parts of the plant do already exist in the embryo, in such specific 
order of arrangement as shall best fit them for future development, by the intro- 
susception of new and additional particles, than that the vital principle shall first 
manufacture a membrane, which it converts into cells^ which are afterwards partially 
and accidentally converted into tubes^ and the plant so patched up. For if this 
were the fact, there would be no such thing as saying what species of plant any 
particular seed might produce, when committed to the soil." Yol. II, 203. 
The vascular system of plants comprises a system of vessels which M. Mirbel 
arranged under five heads ; he it was, who originally advocated the theory so 
justly criticized by Keith ; and as further researches have led to new discoveries, 
we will cursorily run over the arrangement now adopted by Lindley in his Elements 
of Botany. 
1. Cellular tissue, composed of little individual vesicles, cohering together, 
according to the position in which they are placed. 
2. The Cells, so arranged, contain fluids ; and, in fact, all the laborated, specific 
fluids of the plant or tree : according to Knight, it is by the cells that the sap ascends, 
and not by the tubular passages which were originally called sap-vessels. 
The Cells of the leaves contain the Chlorophyll, or colouring matter. Starch 
( Amylum ) is deposited in cells, and of this singular substance that of the Potato 
affords the most familiar example. The following very interesting particulars we 
collect from a Prize Essay (published in the Journal of the Hoyal Agricultural 
Society), by Dr. Fownes — On the Food of Plants. 
" Starch is found abundantly in nearly all the tissues of plants : stem, leaves, 
roots, seeds, are occasionally charged with it also, almost, in appearance, to bursting ; 
it is only necessary to instance the common potato, grain of all kinds, the roots of 
the Orchis and Arum, as examples. When these are torn to pieces by grating, 
and placed in a trickling stream of water, the starch is washed out of the cellular 
tissue which contained it, and, on the water being allowed to stand, settles down 
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