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uniform degree of humidity in the atmosphere breathed by the cuttings. It is generally necessary to leave one or more leaves upon a cutting, in order to generate organizable matter, and to assist in the formation of roots; but this is a a delicate operation, for, if the leaf is allowed to suffer by excessive perspiration, the cuttings must necessarily perish. To maintain a steady saturated atmosphere around a cutting stops this danger, and hence the use of a bell-glass. A double glass has even been recommended; but, if this precaution is of any value, it must be, not because it preserves an even temperature, which is injurious rather than useful, but because it prevents condensation upon the inner bell-glass, and the consequent abstraction of atmospheric moisture, and probably acts at the same time as a kind of shade.

Notwithstanding the precaution of covering cuttings with a bell-glass, shade is also necessary, as a further security against perspiration; for light acts as a specific stimulus, whose effects are very difficult to counteract. It must, however, be employed with great caution; for, if there is not light enough, the leaves attached to the cuttings cannot form that organizable matter out of which roots are produced.

All gardeners know that the root end of a cutting should be close below a leaf-bud; this is to facilitate the emission of roots by the buds, which emission must necessarily take place with greater or less difficulty in proportion as their exit is facilitated or impeded by the pressure of bark on them.

A mode of overcoming some of the practical difficulties attending the propagation of plants by cuttings has been described by Prof. Delacroix, of Besançon. This gentleman states that he, some years since, conceived the idea of insuring the success of cuttings, by putting the lower end in water, and the middle in earth, a circular incision being made between the earth and water. This was not attended with all the advantages he expected, but it led to the discovery of the following plan, which he designates a simple, economical, and certain mode of propagation. His process is described in the following words :

"My cutting is placed entirely under-ground, so as to form a subterranean curve, of which the convexity is uppermost, the very middle of the curve being on a level with the surface of the soil. At this middle point there must be a good eye, or a small shoot. In this way the whole length of the cutting is protected by earth, and the

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smaller end, instead of becoming the seat of dryness, which is always more or less injurious, becomes a passage for absorption. The bud, which, under these circumstances, is the only part exposed to the air, bears, without injury, or rather with advantage, all the causes of excitement. Although I did not commence my experiments before the end of June, I have seen quite enough to satisfy me that the method may be of serious advantage. Two drills about three inches apart were drawn parallel with each other, in a kitchen garden of indifferent quality, situated on a calcareous plain near Besançon. A hundred cuttings of Apples, Pears, Plums, Apricots, Tulip-trees, Roses, &c., almost all of this year's wood, were bent and buried in the manner described, with their ends in the two drills. They were watered a few times, and at this moment every cutting, in the open air, and exposed to the full sunshine, is just as fresh as it was when planted. In most of them, the part exposed to the air (the bud) is the seat of active vegetation, especially in the Pears and Tulip-trees, the buds of which have already made some progress."

Another ready mode of dealing with cuttings, when the means of the propagator are circumscribed, is that of striking in vials of water. A correspondent of the Gardeners' Chronicle thus describes his practice. "I tie vial-bottles together by the necks, and hang them in the windows of our small greenhouse, having filled them with clean soft water. I then put in slips of Salvia, Calceolaria, Mimulus, Myrtle, or anything I wish to propagate of the same description of plants; in about two or three weeks, or a month, the little silver-like roots appear, and in a week or ten days I plant them in small pots well watered; they never seem to flag or mind the change, and I rarely lose a slip. Myrtles are longer in forming roots-cuttings from the same plant have varied from six weeks to twelve months: they were put in in November. A string of bottles I also hang against the back of the greenhouse, where they have plenty of light, and they do equally well, though not quite so quickly.” The practice is old, and well suited to soft-wooded plants. Even some hard-wooded kinds, such as Azaleas, strike freely in this manner.

Conifers may be increased by cuttings. About the month of September, or any time when the wood is three parts ripe, procure cuttings of the current year's growth with a small portion of the old wood attached, or what is termed a heel, selecting the small terminal short-jointed shoots, which are those most likely to form leaders; for although you may strike some of the more weakly side-shoots much easier and quicker, they are afterwards of little value, as they frequently are years before they form a good leader. Having procured the cuttings fresh from the tree, which is of great consequence, for if they are allowed to remain any considerable time before they are put in after separation from the mother plant, there is little hope of success, prepare them by taking the bottom leaves partly off, which should

298

CUTTINGS OF CONIFERS.

either be done with a sharp knife or scissors. When the cuttings are thus made, procure some wide-mouthed or shallow pots, and well drain them, placing over the drainage a small portion of tufty peat or moss, and over that a layer of loam about one inch thick, filling up the remainder of the pot with white sand (the loam prevents the cuttings from cankering after they are rooted, which they are apt to do when placed in sand only); then plant the cuttings from to of an inch deep, according to their size; but the shallower they are placed the better, provided they are made secure and not allowed afterwards to get dry, and particularly if covered with a bell-glass at first; this is not absolutely necessary if the cutting-pots are put into a frame kept quite close, as an equal temperature, both for heat and moisture, is requisite at this time. Having placed the cuttings properly in the sand, give them a copious watering, and finally remove them to some cold frame, kept close and well shaded when necessary. They may remain in this situation till the end of October, when they should be removed to some cold pit for the winter, care being taken that they do not suffer from frost or damp; but they must on no account have much artificial heat. About the end of February remove the cutting-pots to a moderate hot-bed frame, and place bell-glasses over them (if not done before); the cuttings will then root readily, and many of them will be fit to pot off by the end of June, at which time those cuttings which are not rooted should be again placed in sand, and treated as before. When first potted off, the young plants should be treated like seedlings, and afterwards hardened to the open air.

Cape Heaths, which are among the more difficult plants to strike from cuttings, are treated thus :-No particular time can be specified for the operation, because the plants are in a fit state for taking off cuttings at different times; but the earlier in the season the better, although many cultivators succeed perfectly so late as the months of August and September. The plants from which the cuttings are taken must be perfectly healthy. The wood should be firm and nearly ripe; if taken when very young it is almost certain to damp off. The short lateral shoots, about an inch or an inch and a half long, should always be chosen, the leaves stripped off them to about half their length, and the ends cut across with a sharp knife; in this state they are ready for the cutting-pot. The cutting-pots should be prepared in the following manner:-Fill them about two-thirds with broken pots, and cover these with a thin stratum of turfy peat or some other substance, to prevent the sand with which the pots are filled up from choking the drainage. The silver-sand common about London is very well adapted for striking Heaths, but almost any white sand will answer the purpose. The cuttings must be inserted in the sand, not deeply, but merely deep enough to support themselves; from a quarter to half an inch is quite sufficient. They must then be well watered, which will carry down the particles of

CUTTINGS OF HEATHS.

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sand round each cutting, and render them firm enough without further trouble. Bell-glasses are of great service in striking them, but not indispensable. When they are used, they must be frequently taken off and wiped dry, otherwise the moisture will probably rot the cuttings. When they are dispensed with, the cuttings should be placed in a situation which is moist and shaded, and then they will be surrounded in a great measure with the same circumstances as under a bell-glass. Very little artificial heat is necessary in striking Heaths; much is certainly injurious. A Cucumber or Melon frame nearly exhausted, or the shaded part of a cool stove, will answer the purpose early in spring; and later in the season when the sun-heat is greater a close frame slightly shaded is all that is required. The care afterwards is to shade during bright sunshine, taking means to remove the shade early in the afternoon, so as to allow the rays, which are not then strong enough to injure the cuttings, to heat the frame, and also to see that the watering is not neglected. More, perhaps, depends upon the kind of water which is used, and the regularity with which it is given, than upon anything else in the operation, if we except the selection of proper cuttings. Rain or river water is by far the best kind to use; spring-water is usually injurious. After the cuttings have struck root, they should be gradually hardened by exposure to the air before they are potted off. Small thumb-pots are the best for the first potting, and the soil used should be very sandy peat. The greatest care should be taken to preserve the young rootlets from injury, because if this is not attended to the plants will receive a sudden check at first, which is very prejudicial. These examples will teach any intelligent person how to deal with other kinds of plants.

No further precautions are taken with cuttings, nor does it at first sight appear possible to suggest any nevertheless the enormous constitutional difference among plants is such, that, while numerous species will strike without any difficulty under almost any circumstances, with the wood ripe or halfripe, just formed or aged, there are many others which no art has yet succeeded in converting into plants; and it is by no means uncommon to find that, out of a potful of cuttings of the same species, apparently all alike and subjected to exactly the same treatment, one will grow and the remainder fail.

It has been thought worthy of inquiry whether bell-glasses of different colours will not produce different effects upon cuttings, in consequence of their different power of transmitting light. It has been shown by Dr. Daubeny, in a very interesting paper in the Philosophical Transactions for 1836, page

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EFFECTS OF COLOURED LIGHT.

149, that glass of different colours exercise very different effects upon the plants exposed to the rays of solar light passing through it; that both the exhalation and absorption of moisture by plants, so far as they depend upon the influence of light, are affected in the greatest degree by the most luminous rays, and that all the functions of the vegetable economy, which are owing to the presence of this agent, follow in that respect the same law. In these experiments it was ascertained that the glass employed admitted the passage of the rays of light in the following proportions :

M. Decaisne found, during some experiments to ascertain the effect of light in causing the production of colouring matter in the Madder plant, that when the lower parts of a plant were enclosed in cases glazed at the side with transparent green, red, or yellow glass, the leaves and stem of the part surrounded by red glass, became pallid, and exhibited signs of suffering in a greater degree than under the other colours, but all were affected more or less. (Recherches sur la Garance, p. 23.) Many ingenious experiments of a similar nature have been made by Mr. Hunt as has been already stated (p. 238). But we have not ground at present to believe that they possess practical value. No advantage seems to have resulted from glazing the great Palm House at Kew with green glass of a tint selected by Mr. Hunt himself; and, in short, we have every reason to conclude that the white light which is natural to plants is that which is best adapted to their constitution; nothing more being required of the gardener than to moderate or increase its intensity.

Full details respecting the experiments of Mr. Hunt will be found in the Gardeners' Chronicle for 1847, p. 524, and for 1848, pp. 138, 155. In the same work for 1845, p. 55, are also recorded Zantedeschi's observations upon the influence of coloured light.

* The nature of these experiments has been misapprehended in the translation, by Mr. Francis, of Meyen's Report on Vegetable Physiology for 1837, p. 51.