This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
I am very glad to see, Mr. Editor, the prominence your valuable journal gives to such interesting subjects as that of Mr. W. N. White, in your August number. It would not become me, as a practical man, to depreciate the value of mere practical articles; they are highly useful and very instructive; but, at the same time, if ever our profession is to rise to the dignity of a science, it is essential that we should be able to give a reason for all things. With practice on our right hand, to observe and to do, and on our left theory, to investigate and arrange, we may hope to arrive at just conclusions much earlier and easier than by either alone.
I am one who has hitherto had great faith in the efforts of the hybridizer to ameliorate our fruits, as they have already done the beauty and interest of our flowers. Mr. White's paper, tending to show the impossibility of such improvement, is so ably and forcibly written, that I am afraid it will induce many projected experiments to be abandoned. I think such a result is to be deplored, and I would like to offer a few suggestions, per contra, to his remarks.
My greatest objection to your correspondent's conclusions is, that they are for the most part derived from the observations of authors who wrote when the art of hybridizing was in its infancy. Mr. Knight, Gaertner, and others, with their leisure and love of the subject, had they lived to the present day would probably have come to different conclusions than their first experiments warranted.* Decandolle, Gray, and the other authorities quoted, are indeed still living, but their quoted works are either of some years' standing, or their ideas founded on Knight's, or other parties, ancient experiments. One authority quoted, for instance, Dr. Lindley, has more recently asserted (Theory of Horticulture, p. 691), "but facts prove that undoubted hybrids may be fertile." Since the doctor wrote that, we not only have learned that hybrids may be, but actually are fertile. I have at the present writing, seedlings of the Veronica "Imperial blue," a variety three, four, or more generations removed from an original hybrid between V. Speciosa and V. Lindleyana, or Salicifolia. I have raised a brood of Fuchsias, between F. fulgens and F. longiflora, two species as widely distinct as it is easy to suppose any specific terms to characterize; and from some of this progeny again to reproduce seedlings, though I am bound to admit some of them produced berries with great difficulty.
So, also, other parties have had the same experience.
* Even ten years ago it was thought that Orchidacea did not perfect their seed. Every experiment to raise them failed. Now they are not considered difficult to raise, and even to hybridise, not even genera standing in the way, as a hybrid is recorded between Epidendrum aurantiacwm, and Cattleya Skinnerii.
The different species of tropical Begonias have been found to hybridize together so easily, and their progeny again to hybridize and reproduce, that it is impossible to foresee where it is to stop. The same may be said of the Bouvardia and Achimenes. In the latter case, indeed, it is not only difficult to decide which is a species, the genera themselves seem lost in the confusion. Hybridizing has, in fact, quite swamped Sinningia into Gloxinia, and since the introduction of the Central American species of Achimenes, it is hard for a systematic botanist to go into a good garden collection and fix which genus of gesneracea some of them may belong to.
Systematic botany, though it may be termed a "natural system," is purely a work of art,; and if we "could without limit produce crosses," it would not so much break up the "orderly arrangements of nature" as it would, perhaps, the systems of Lindley, Decandolle, or Gray. It is not yet agreed upon what constitutes a true species, and genera are confessedly artificial. If two species, so called, will not intermix, they may in time come to be considered as of different genera. In the case of the gooseberry and currant, for instance, which Lindley could not intermix, some botanists make distinct genera, calling the gooseberry section Grossularia, and the currant Ribesia. The progress of horticulture has quite broken up the old theory of a species, namely, that it was an individual form by which " like could be again reproduced from like" as we now know that varieties of both form and color can, with a very little care, be again reproduced from seed, and after one or two generations becomes as permanent as the species it originated from, reproducing as exactly " like from like".
Many of Mr. W.'s objections as to what has not been done are not conclusive as to what may be. For instance, that dioecious plants should in Lecoq's time be found less easy of hybridizing than hermaphrodie ones, may be that so much attention may not have been paid to them. Quite recently we find an hybrid amongst the Pinacea, which we should suppose, from many circumstances, much more difficult to realize than in the grape. The Thuja meldensis, is said to be a hybrid between Juniperus Virginia and Biota Orientalis, two very distinct genera, and any one who has seen it growing will not for a moment doubt the fact. Whether it will also produce perfect seeds or not I am not aware.*
It is scarcely parallel to illustrate the subject by the mule in the animal kingdom. We can readily suppose that in the animal department of the organic portion of nature, the structure is so very complicated, and so much more perfect, as to place many more checks to variation from normal types. Animal nature is not so easily affected by cross-breeding, or any circumstances, as a plant is. We may look in vain among animals for anything like so great a change in appearance, by any amount of "cultivation," as that process has made on the cauliflower, for instance, which has been " improved " from a wild plant, more resembling the common mustard in appearance than anything else.
I think Mr. White's quotation that Mr. Knight could not get the Duke and Morello cherry to hybridize, is an error. If I am not mistaken, he succeeded in the union, but the progeny did not seed, though they flowered freely. This, and the few other cases on record of experiments with fruits, does not certainly give great encouragement, but on repetition, under other circumstances, might do better. Many experiments fail, that with a slight variation have after all succeeded. The art of hybridizing is ill understood; every day new facts are being developed. It is but quite recently'asserted that two plants, hybridized when in a high state of culture, under glass, do not produce the same progeny as the same plants, comparatively neglected, hybridized in the open air; and that the more artificially the plant is treated the more easily can the hybridizer operate on it. And this is but one of many facts that may yet have considerable influence in the progress of the art.
* One of oar best practical living botanists, Mr. Charles J. Wister, of Philadelphia, has assured me that in his neighborhood Juglans cineria, J. regia and J. nigra, the black, white and English walnuts, hybridize together, and that specimens of the hybrids bear fruit near him.
No one will contend for the superiority of cross-breeding over mere improving, but if it can be effected it would be a natural step towards improvement By crossing a pound pear with a seckel, we should " mix" the flavor of each in the progeny. The pound pear would thus be produced a little smaller perhaps, but something towards the flavor of a seckel, and by saving the seed of the finest of these seedlings (providing, of course, they proved to seed freely,) for a few successive generations, a late, large pear, with a seckel flavor, might be produced.*
I trust that the hybridizers will still continue their experiments. The native and foreign grapes are botanically very closely allied, much more so than the gooseberry and currant, raspberry and blackberry, or the apple and the pear; and they may, like species of fuchsias and veronicas, hybridize and prove fertile, and from this progeny improvements may again arise; but if not, we shall learn something which, even as knowledge merely, may be of great service to us in other affairs.