268 
REVIEWS. 
oily matters; while a further portion of the absorbed substances is converted into new muc-ns to fill 
the newly produced cells of the growing buds, and into chlorophyll, which is a kind of fat accumulated 
in the interior of the old cells. 
The starch and nitrogenous matters which are lost from the green organs in the autumn are merely 
removed into another part, and converted into new products. The starch which has been accumulated 
in the seeds, tubers, buds, or other parts, is dissolved in the spring, and furnishes the material for 
fresh development; the young plant from the seed, the nascent shoot from the bud. All the new 
structures making them appearance under the genial influence of the aAvakening season, are derived 
from the provision of the preceding season, since they become considerably developed before the new 
roots have grown sufficiently to supply them adequately with newly elaborated nutriment. 
The green parts of vegetables give off oxygen continually under the influence of the sun’s rays, or 
even in diffused daylight. This is a fact which has been long decided ; but the explanation of it is by 
no means clear at present. The “ becoming green” is not the essential point, since it is proved by 
experiment that the green matter is exceedingly small in quantity; moreover colourless or yellowish 
globules are produced hi the dark, which are greened by the action of light. The received opinion is 
that the accumulated nutriment—the starch answering to the fat of animals—is formed independently 
of light; but, in proportion to the degree of light obtained by the plant, this starch becomes more or less 
converted into fatty or oily matters, losing oxygen in the change; and under direct sunlight this 
oxygen is given off so abundantly as to oxidize the colourless chlorophyll which forms a layer over 
the changmg starch globules. VTe cannot venture to give a decided opinion on the real nature of the 
changes; but there is no doubt about the general result of the action of light. Growth can go on 
without it, and to a great extent, as we see in subterranean stems, in the leaf-stalks of Celery, blanched 
Endive, forced Rhubarb, and the like, where abundance of nitrogenous matters are furnished by highly 
manuring the soil; but in all these cases there is a deficiency of the active products of the tissues; 
the cells do not become woody, but remain soft and succulent; the strong principles which give the 
peculiar character to particular plants are not developed; the white Celery-stalks have little of the 
acrid matter which is so abundant in the wild Celery, and the blanched Endive has but a slight trace 
of its naturally strong bitter principle; and we find the influence of deficiency of light even in the 
development of the tropical fruits under the moderated action of the sun’s light in our stoves. 
On the other hand, the aromatic herbs increase in abundance as wild weeds, as we approach 
warmer climates ; even with us the “ wild thyme” audits allies are characteristic of dry, sunny banks, and 
the occasion of a hot and bright summer is always marked by a deeper colour of the foliage of our trees. 
The action of the sun is therefore, on the whole, that of fixing carbon, and also nitrogen in the 
tissues of plants, so that, as a practical conclusion, we shall always endeavour to obtain for our culti¬ 
vated vegetables increase of light when we wish them to develope their active properties, and to 
accumulate elaborated food, either in the shape of woody tissue, of starch, or of the various oils, active 
or aromatic principles ; and moreover, when we -wish them to produce seeds, since they can only effect 
this highest operation of development when they have had the opportunity of laying up a store of 
nutriment to supply the excessive requirements of this process. How great these requirements are is 
proved by all experience; the flowers and seeds of annuals are only produced in the later seasons of 
the year ; biennials require the accumulation of two years ; perennials seldom flower for several years 
under ordinary circumstances, and then, when the product of seeds is very large, the operation is 
sometimes followed by the death of the exhausted plant, as in many Monocotyledons, such as the 
Talipot Palm, the American Aloe, &c. 
These summary Hews are sufficient to give some notion of the general operations of vegetable life; 
when we enter into the minutiae of special processes, the particulars become much more complicated. 
We shall therefore treat of them separately hereafter ; and the continuation of our papers on Vegetable 
Physiology will now pass from the abstract character which they have hitherto necessarily assumed, 
into the more definite form of chapters upon the particular operations of vegetation performed by the 
different organs, such as the roots, leaves, flowers, fruits, &c, 
- + - 
The Royal Walter Lily of South America , and the Wader Lilies of our ovm Land: their History and Cultivation. By 
George Lawsox, F.B.S., &c. Edinburgh: Hogg. London: Groombridge. 
We are glad to find that our correspondent, Mr. Lawson, has, in the little volume before us, provided for the 
million, in the form of a very elegant and very cheap book, a trustworthy, readable statement of all that is known 
respecting the Floral Queen of the waters—the Victoria regia; and has also taken the opportunity to put in a plea 
