« السابقةمتابعة »
sert at the Electoral table at Hanover (1716); as a thing she
Mordeat et tenerum fortior aura nemus :
Martial, Lib. viii. 14.
Rus Entelle, tuæ preferat ille domûs.
Et gelidum Bacchi munera frigus edat ;
Et tegitur felix, nec tamen uva latet.
Calculus in nitida sic numeratur aqua.
Autumnum sterilis ferre jubetur hiems.'--Ibid. viii. 68. On the first Epigram Sir Joseph remarks, that it in all probability describes a peach-house; and the word Pallida, which is meant as a ridicule on the practice, gives reason for this supposition; as we now know, that peaches grown under glass cannot be endowed either with colour or with flavour, unless exposed by the removal of the lights whilst the fruit is ripening; and, if this is not done, the best sorts are pale, green, and tasteless when ripe.
The second Epigram more plainly refers to a grape-house: contrived however, probably, for securing a late crop, rather than as a forcing-house; and the last line leads to this opinion.
Pliny also tells us, that Tiberius was fond of cucumbers, and had them in his garden throughout the year, by means of specularia (stoves), where they were grown in boxes, and wheeled out in fine weather.
Theoretical writers on vegetation, as well as gardeners, are apt to transfer the feelings of animal life to plants; whence arises the recommendation of hungry soils and cold situations for nurseries, seeing how agreeable it is to go from worse to better; and this feeling amongst gardeners has led to a mode of treatment of plants in forcing-houses directly contrary to nature; and as they like a warm ved in a cold night, and fresh air in a hot day, they are apt to treat their plants as they would wish to be treated themselves. But this is contrary to the mode of existence of the plants in a state of nature; and Mr Knight conceives the consequence of this excess of heat during the night, . VOL. XXXIV. NO, 68.
in all cases injurious to the fruit-trees of temperate, and not at all beneficial to those of the intertropical climates.
In Jamaica, and other mountainous islands of the West Indies, the air upon the mountains becomes, soon after sun-set, chilled and condensed; and, in consequence of its superior gravity, descends and displaces the warm air of the valleys; yet the sugar canes are not injured by the sudden decrease of temperature. It must, on consideration, be obvious, that the more nearly Nature in its best climates and most favourable seasons is copied as to temperature, the more perfect will be the production. As yet, according to the common practice, there is hardly a gardener who does not imitate, as he supposes, the cool evening dews of nature, by sprinkling his flues with water, and filling his house abundantly with steam ;-the one in fact resembling the sudden chill of the shower-bath, and the latter that of the hot-vapour baths of Russia.
Mr Knight, in his peach-house, reduced the temperature to the natural state of the air during the night, except when there was an appearance of frost, and every evening sprinkled his peach-trees with abundance of water; and he states, that his fruit blossomed, set, and ripened more successfully than he had ever experienced it. Although the succulent shoots of trees always appear to grow more rapidly on a damp heat during the night, it is rather an elongation than growth. The spaces between the bases of the leaves, indeed, become longer, but no new organs are added; and it is in fact only the quantity of material extended to a greater length. Another of the ill effects of the high temperature during the night is, that it exhausts the excitability of the tree much more rapidly than it promotes the growth, or accelerates the maturity of the fruit, which is, in consequence, ill supplied with nutriment at the
peo riod of its ripening, when most nutriment is probably wanted.
VI. Sir Joseph Banks, some time since, published a pamphlet on the Rust or Mildew in Wheat, which we have already no
* and it contained strong evidence that this disease was a minute parasitic fungus, propagated like other plants by seeds. • The evidence,' Mr Knight observes, would, I think, be suf'ficient, if the means were ascertained by which the seeds of
this species of fungus are conveyed from the wheat plants of
one season to those of the succeeding year. This, however, • has not been done; and some still consider that the mildew • of wheat consists only of preternatural processes, which spring • from a diseased action of the powers of life in the plants them
* Vol. VII. p. 148.
selves. 't Assuming that the various species of fungus are propagated by seeds as the least objectionable hypothesis, Mr Knight observes, it will not be difficult to show that they are sufficiently numerous to account for the ubiquity of the plants they are supposed to produce; and as these apparent seeds are, by their lightness, capable of being everywhere dispersed by the winds, Mr Knight, from an experiment made by him on a mushroom, conceives that 250 million seeds were produced in 96 hours. He has endeavoured to point out some means by which the injurious effects of the common white mildew may be prevented. The secondary and immediate causes, to him appear a want of sufficient supply of moisture from the soil, with excess of humidity in the air; particularly if plants are exposed to a temperature below that to which they have been accustomed. And it is observed, if damp and cold weather in July succeed that which has been warm and bright, without the intervention of sufficient rain to moisten the ground to some depth, the wheat crop is generally much injured by mildew.
I suspect that, in such cases, an injurious absorption of moisture, by the leaves and stems of wheat plants, takes place;
and I have proved that, under similar circumstances, much ' water will be absorbed by the leaves of trees, and carried • downwards through their alburnous substance, though it is
certainly through this substance that the sap rises under other s circumstances. If a branch, be taken from a tree when its • leaves are mature, and one leaf be kept constantly wet, that
leaf will absorb moisture, and supply another leaf below it
upon the branch, even though all communication between • them through the bark be intersected; and if a similar ab
sorption takes place in the straws of wheat, or the stems of • other plants, and a retrograde motion of the fluids be pro
duced, I conceive that the ascent of the true sap, or organiza
ble matter, in the seed vessels, must be retarded, and it may • become the food of parasitical plants, which then only may
+ A hypothesis, differing little from his, has been published in the Quarterly Review, respecting the dry rot, or Boletus Lacrymans of Finiber, in which it is supposed the different kinds of fungus which appear upon decaying timber, are produced by the remaining powers of life in the sap of the unseasoned wood; and that the same kind of living organizable matter which, whilst its powers remained perfect, would have generated an oak branch, will, when debilitated, give existence to a species of fungus. It only requires to pursue this argument, to see its absurdity; which would soon arrive at the conclusion, that a mass of animal matter, as old cheese, might generate a miteand a larger mass of decomposing animal matter, produce us elephants !
• grow luxuriant and injurious.' This is Mr Knight's view of the subject; and, whether correct or not, it is impossible not to see how much good must be derived from inquiries of this nature, pursued with such unremitting care and attention as is bestowed on them by the President. In some experiments made on the cultivation of the Pea, (a plant peculiarly subject to the mildew at the latter part of the year), considerable quantities of water was given to the growing plants, and to the ground before the sowing; and all appearance of mildew was avoided. Several of the more delicate fruits now cultivated in this country cannot be made to produce, unless with the assistance of being trained against a south wall.
VII. The facts observed by Mr Knight with respect to vegetable physiology, have enabled him to improve much in the practice of training wall trees, which was irrational and defective-no attention having been paid to the form which the species or variety naturally assumed; and, be its natural growth upright or pendent, it was constrained to take the same form on the wall. From experiments, Mr Knight inferred, that none of the forms in which fruit-trees are generally trained, are those best calculated to promote an equal distribution of the circulating fluids, by which alone permanent health and vigour, and power to afford a succession of abundant crops, can be given. The principal of his improvements is, to expose a greater surface of leaf to the light, without placing any of the leaves so as to shade the others; and, by selecting the strongest and earliest buds towards the points of the year-old branches, and the weakest and latest near the bases, an equal vigour was thus given to each annual shoot; and when one grew with greater luxuriance by being depressed, and the weaker elevated, they acquired an equal degree of vigour. In France there is an annual publication, called Le Bon Jardinier, which contains much useful information on practical gardening; and we trust, before long, that a similar publication will be produced in this country, under the auspices of the Horticultural Society. In addition, however, to the difficulties arising from the climate, the French materially surpass us in several branches of horticulture; and one of their principal means of success is the division of labour, which has not yet been adopted in this country. In France, whole villages are employed in the cultivation of one single sort of fruit; and, consequently, the whole attention of individuals, for generations, is directed to one point only. At Montreal, the whole population has been long maintained by the cultivation of peaches-their sole occupation; and the inhabitants of Argenteuil derive their chief support from the cultivation of fig-trees. Near the town, are immense fields covered with these trees on the sides of hills facing the south, and in other places sheltered from the north and south-west, and it is at these towns alone, perhaps, that the true management of these delicious fruits can be acquired.
Next in interest to the papers by the President, are those contributed by Mr Sabine the Secretary, and by the late Sir Joseph Banks, who was indefatigable in his exertions to promote the interests of the Society. * We cannot conclude our observations, without recommending that those entrusted with the selection of the papers for publication should in future be somewhat more careful, or at least more sparing in their choice; for though there are many containing useful practical information, yet there is much that might have been omitted; and we confess, that had we, in the early part of our examination, stumbled on some of Mr R. Salisbury's long papers, or the account of Mr Seaton's invention of marked tallies, or garden sticks, accompanied by a plate,' it is most probable we should have been deterred from all further progress; in which case, our general readers would have remained ignorant of the Theory of hybrid plants, and the whole mystery of the propagation of apple-trees, whether by seeds or grafts.
* All must regret the recent loss of the late venerable President of the Royal Society. The annals of science do not perhaps afford an instance of a man who so entirely devoted his time, talents and fortune, to the advancement of knowledge. At his entrance into life, succeeding to a splendid inheritance, he turned aside from the paths of pleasure, and the usual pursuits of his age, to become the companion of Cook; and, scarcely arrived at manhood, was a sharer of the fame of that illustrious navigator.
The zeal and eagerness with which he pursued all subjects connected with science, continued one of the most striking features of his character; and, at an advanced age, and although long suffering under the most painful diseases, the freshness and vigour of his mind, and his interest in those subjects, were unabated. His valuable collections, and his unbounded stores of information, were at the service of all. His library (the richest perhaps in Europe on subjects of natural history) was of far more easy access than any other public library in England. His unostentatious readiness to supply the pecuniary wants of scientific persons will, we are persuaded, long live in the memory of many. No one perhaps, in our time, has gained such universal and unmixed admiration and esteem : unconnected with politics or party, he neither trenched upon the interests, nor interfered with the prejudices of any. It wil be long.indeed before one shall be found capable of filling the vacancy made by his death • Artium tum utilium, tum elgantiorum judex et patranus !!