Chronicle 1: 443 (July 6, 1844)
AMONG the many contrivances by which man has succeeded in converting the wild productions of untamed nature into bodies better adapted to his artificial wants, nothing has produced more past advantage, or promises more future profit, than HYBRIDISING. We shall not refer in this place to what has been done in the animal kingdom, but confine the attention of the reader to its effects upon vegetation.
The practice is regarded as one of very recent date and so it is, as an artificial process, applied by rule to definite purposes. But he must be a bold man who dares assign to it historical limits; on the contrary, it may be supposed to date from the Creation—or rather, it is in a manner certain that it does. The presence of winds or insects must necessarily from the beginning have produced effects upon plants, which resulted in hybrid productions.
Hybridising is effected by applying to the stigma of one plant the pollen of some other; the end of which is the generation of a form participating more or less in the attributes of both its parents. Nature, in her wildest state, opposes no insurmountable difficulties in the way of this operation. Insects, bepowdered with the pollen of one plant, plunge into the recesses of another, and thus effectually destroy the purity of races. The natural brush on the body of a bee will convey the subtile powder as well as the trim camel's hair pencil of the artificial operator.
It is contended, indeed, that this cannot be; because if it were so, all species must, in the lapse of ages, be confounded in one inextricable chaos. But, in the first place, this supposition is of little force, till it is shown that that which is easily done artificially cannot possibly take place naturally; and secondly, it must be proved that the wild races of plants actually do remain in all their original purity. No Botanist would, we suspect, venture upon such an argument as that. The genera Salix, Rubus, Rosa, and Carex, would make the stoutest advocate of original purity pause before he threw himself into the lists. Nobody, in fact, can possibly doubt that wild hybrids exist, are common, and, perhaps, much more frequent than we think for. We will not stop to quote notorious and proved instances of this, because we regard the fact as being beyond all dispute.
Let us not, however, infer from this that no natural obstacles are opposed to the indiscriminate mixture of races in plants; on the contrary, there are barriers which cannot be overleaped. By some mysterious agency there is a complete bar to all intermixture of plants not closely related to each other. An Elm may certainly mix with an Elm, and perhaps with a Nettle-tree; but not with an Oak. A Peach may, peradventure, cross a Plum; but not an Apple. These obstacles are, doubtless, connected with the molecular constitution of plants, the precise nature of which we have no means of examining. Another obstacle consists in the obvious fact that the pollen of a flower has a better opportunity of falling upon the stigma that belongs to it, than pollen brought from any distance; and we know that if pollen has once taken effect, no after-application of other pollen can change the result. In fact, the natural hybridising of wild plants will generally take place when, owing to some accidental cause, the proper stamens of the flower prove defective.
But there is a still more effectual obstacle, to the confusion of races by natural hybridising. Although we conceive that the production of hybrid plants naturally is of more common occurrence than may be supposed, it must be remembered that the preservation of them is quite an artificial process. A hybrid tree springs up; it has no means of multiplying itself, except by seed. That seed has no stable constitution, but has a tendency to return towards the condition of one of its parents; in this way the hybrid disappears, while the parents remain; or it may, and often is, barren; and then it remains as a solitary, childless individual. Again, a hybrid herb appears; it is exposed to the same obstacles as the tree, in the way of perpetuation. It is barren; its seeds of themselves tend towards the original stock, which is recovered in a generation or two; or they are at once fertilised by the pollen of one of the hybrid parents, when the tendency to a return to its original stock is increased tenfold in strength. It is not, therefore, likely that natural hybrids will often be long perpetuated, although they may be frequently produced.
We mention these things by way of vindicating the hybridisers, who have been accused of attempting to subvert the whole order of Nature by monstrous practices. It is clear that they only imitate the practices of Nature. It is equally clear, too, that the occasional formation of natural hybrids is intended as a manifestation to man of one of the sources of power with which he is so largely provided. His reason is to be called upon to turn to profitable account that which, in savage nature, leads to no result.
Be this as it may, the practice of hybridising is, as the politicians say, a great fact, opposition to which would be fruitless if it were desirable. People have found out how much is to be gained by it, and they cannot be checked in its application by the sighs of Botanists over the dreaded advent of a chaos of species. All that Botanists afflicted with the hemionophobia can do, is to abandon gardens, and seek for solace in uncultivated lands.
Hitherto the operation of hybridising has been mainly confined to gardens. But see what advantages have come of it there. What were our Roses in 1789, when the first China Rose reached England? and what are they now? The China Rose hybridises so freely with almost every other, that there is hardly an ancient species to which it has not lent some part of its rich foliage, gay colours, and abundant blooming. Can anything be more striking than the effect of hybridising upon Pelargoniums, Heaths, Gloxinias, Verbenas, and Gladioli? By this process we have given to the hardy Pears of the north all the richness and delicacy of those of the south; to watery Grapes the perfume of the Muscat; to the pale-faced but hardy Rhododendrons of Caucasus and America the rich and glowing colours of their tender brethren of India; to the gaudy Azalea of Pontus the crimson of the small-flowered fragrant species of the United States.
Such striking consequences of the very first operations in hybridising have excited a universal desire to vary and extend them. Everybody now, who cares for his garden, asks himself in the first place what he can do to get new seedlings; and to hybridising he looks exclusively for assistance. If a fine new species of an ancient family appears, its good points as a "brood plant" (forgive the innovation) are among the first things discussed; and its value is much determined by its fitness for hybridising. Nor is it to be wondered at. Hybridising is a game of chance played between man and plants. It is in some respects a matter of hazard; and we all know how much more excitement is produced by uncertain than by certain results. What increases the charm of the game is, that although the end of it may be doubtful, yet a good player can judge of the issue with tolerable confidence, and that skill and judgment have in this case ail their customary value.
What the principles are to which the hybridiser should look, and where the fields lie in which his operations can be best conducted, we shall endeavour to show next week.
THOUGH HYBRIDISING has already led to important results, they are probably nothing compared to what may be expected to come of it. We anticipate through its assistance a change in the whole face of cultivated plants, and we shall be much surprised if even a few years do not bring us acquainted with races of trees, esculents, corn and forage plants, of at least as much importance in their way as those which have already appeared among fruits and flowers; all that is wanted is to call attention to the subject, and to point out what the principles are which the experimenter has to bear in mind.
The effect is produced by applying the pollen of one flower to the stigma of another. The pollen indicates the male parent, the stigma the female. In performing the operation it is necessary to use these precautions:—The female flower must be deprived of her stamens before they burst and disperse their pollen; and as soon as the stigma is glutinous enough to hold it fast, the pollen must be applied with care. Should this care not be taken the stigma is very likely to be inoculated with the pollen of her own or some other flower, and then the pollen which it is intended to use will not take; for it must be always borne in mind that a stigma once inoculated cannot be inoculated again. From want of these have precautions, people are continually fancying they have obtained hybrids when they have only gained natural seedlings. At least half the specimens of hybrids sent to us for examination, are not hybridised at all. When the Dean of Manchester, who is the greatest of all authorities in this matter, wishes to obtain a cross, he always endeavours to force the female parent before others of its kind blow, so as to be insured against accidental inoculation from pollen floating in the air. Want of attention to these minutiae has led to some singular errors on the part of a very ingenious correspondent, who fancied he had obtained seedlings between Crinum, Ismene, Buphane, Calostemma, &c., while he had only raised the usual seedlings.
It is hard to say within what limits the operation may be successfully practised. The general rule is that plants only, which are very nearly related, are able to inoculate each other. But there may be exceptions to this. At least we know that very near connexions have, or seem to have, a great aversion for one another. For example, a Raspberry and a Strawberry are first-cousins, yet they appear to have no mind for an alliance. A Gooseberry, Currant, and Black Currant are still nearer to each other, and their repugnance seems invincible; at least nobody has. yet found means to hybridise them with each other, though many have attempted it. On the other hand, Heaths, different as they are from each other, intermingle freely; Cereus speciosissimus is readily inoculated by the night-flowering Cereus; and even the creeping Cereus has been crossed with the former; the Rhododendron will fertilise the Azalea; and, strangest of all, the Red Cedar has on several occasions been found to inoculate the American Arbor Vitae, the issue from which is that curious whipcord-branched plant called in the gardens Thuja filiformis. This singular shrub was so produced for the first time in Messrs. Loddiges' nursery at Hackney, and has since been obtained in the same manner at Paris. These facts open a very wide field for inquiry, and are especially valuable as affording evidence that the limits of hybridising are far from being narrow.
In the midst of many experiments conducted without exactness, from which no safe conclusion can be drawn, there are some which, in the hands of such men as the Dean of Manchester, seem to justify the important inference, that as a general rule the properties of the male parent will be most conspicuous in the hybrid. For example, Mr. Herbert crossed the long-yellow-cupped common Daffodil, with the small red-edge-cupped Poet's Daffodil; and the seeds of the common Daffodil furnished a bulb with most of the attributes of the Poet's Narcissus. The same gentleman also obtained out of a capsule of Rhododendron ponticum, inoculated by Azalea pontica, seedlings which had entirely the habit of the latter or male parent.
In like manner the arborescent crimson-flowered Rhododendron altaclerense was raised from the seed of the dwarf pallid R. catawbiense hybridised by the arborescent crimson R. arboreum; and when the common scarlet Azalea, with its crimson flowers and narrow leaves, was inoculated at Highclere by Azalea pontica, Mr. Gower found that its seeds produced plants much more like the male than the female parent. Exceptions, or apparent exceptions to this, do no doubt exist, and hybrids could be found who are either half-way between their father and mother, or more like the mother than the father; but as far as any means of judging at present exist these would seem to be the exception and not the rule; and there fore the greater influence of the male may be taken as a tolerably safe guide in all experiments upon this interesting art.
"It is a species of no great attraction, but deserves to be recorded in this work, as one of the genuine wild forms of a genus, which, however beautiful and interesting, has already begun to sink in estimation, in consequence of the ruin that has been brought upon it by the unskilfulness of gardeners. In their haste to improve the works of nature, these gentlemen have converted some of the fairest races in the Vegetable world, into forms in no case more beautiful than the original, and in the majority of instances unhealthy, mongrel, and debased. We strongly recommend all those who value this really beautiful and most singular genus, to abandon a pursuit which has as yet led to few results of which good taste can approve, and to apply the same skill which they have used in spoiling Calceolarias to recovering the pure original races, to preserving them uncontaminated, and to increasing their native charms; not by unnatural combinations, but by those well known methods by which the purity of a species may be maintained while its vigour, health and beauty are augmented.
At least, if the genus must be the subject of hybridizing, let the intermixture be made with some reasonable attention to the only rules by which it is possible to arrive at a really desirable result."