May 1849 pp. 90-91
HYBRIDIZING is the name of that fascinating process by which we obtain new seedling plants from two distinct species of the same genus, or family, or from two varieties of a single species, by merely crossing the one with the other. We have thus three names, the A B C of the language of hybridizing, or cross breeding, and I may, thus early, state that naturalists, as well as the practitioners in this art, both in the animal and vegetable kingdoms, have by their writings and speculations rendered this most simple art a perfect Babel, and that by not first learning the A B C of the art. It is, therefore, most essential that the first three letters, or names, should be well understood on the threshold, otherwise on entering the temple we may easily lie led away, like the rest, into endless confusion; for there have been as many theories, or rather hypotheses, broached on this subject as on the origin of evil.
A genus, a species, and a variety, are the A B C. The genus is the family, A; the species, B, are the different members of that family, and these members will only interbreed among themselves, and with the varieties C, which must have sprung from the species. In obedience to the divine command to "increase and multiply," the different species of a family of plants, as well as the species in a given family of animals, are formed to breed with each other, under certain restrictions; some with more freedom than others, it is true, and some resist all advances in this direction. But for want of sufficient materials, or data, no theory can yet be constructed by which we could say beforehand that such and such species will cross: we must aim at this knowledge by actual experiments, step by step, and every reader of THE COTTAGE GARDENER may easily try an experiment, and even gain a step, and every step gained is a new fact; and we all know that it is from a multitude of well-attested facts that useful theory can be formed on any subject. Therefore, the more recruits that we can enlist into this experimental field, the sooner these facts will accumulate, on which to construct a sound theory that will assist the whole of us. The only absolute rule that we are yet in possession of, is the one I have referred to already—that plants or species will only intermix with others of their own family. This is certain and settled. I may state, however, that many assertions to the contrary have been advanced, but they are all too apocryphal to require a passing thought. It is true that botanists and zoologists, in their respective spheres, have unavoidably classed many plants and animals in different families, to which they were not assigned in the beginning," and many of these naturalists were at first very jealous of the cross-breeder's art, as it revealed in some instances the looseness of their classification, but all this misunderstanding has happily passed away, and now, if you can clearly prove that two plants will cross together, although they may have been placed in two different families in the arrangement of the greatest botanist, he will give way at once, and range these plants in one family. Therefore, in addition to the great interest attached to cross breeding, as a means of increasing the diversity of our flowers, it is a useful check on the labours of the botanist, by which he may clear doubtful points in his arrangement, or allow the gardener, or rather THE COTTAGE GARDENER, to do it for him.
Now, to attain to such distinction, we must clearly learn the meaning of our A B C; let us, therefore, for illustration, take the genus or family to which we ourselves belong. In every arrangement all families have a particular name to distinguish them from each other; and the name of our family is mankind. "In the beginning" there were only two species of this family or genus—Adam and Eve: although this definition will better illustrate my meaning, it is not strictly correct. Here, then, we have a genus and two species, but no variety, which is the only remaining letter in our alphabet. Now, when Cain and Abel were borne into the world, can you say whether or not they were two more species of the genus, or merely two varieties of it? On this simple question hinges all the learned disquisitions with which philosophers have allowed themselves to be led away into old Chaos again, on the subject of cross-breeding both among animals and plants; and thousands of the unlearned have also followed in their path, some in one way and some in another; for, like other questions that can bear to be handled on all sides, this one has had many expounders, almost every one of whom either adopts a new phraseology of his own, or applies that of another in a different sense to the original meaning intended for it. Hence the Babel of unmeaning or misapplied terms in the language of cross-breeding; and hence, too, my reasons for adverting to those things, in order to guard my readers against falling into these quicksands; for, without first explaining the terms which I mean to use in writing on this fascinating subject, and without shewing the reason why I make use of such terms in preference to others in current use, I cannot expect to make myself so clearly understood as I wish to be, in order to be really useful. I may premise, however, that I do not intend to enter on any of the abstruse points connected with the subject, but merely the simplest rules pointed out by actual experience; and, if I am so fortunate as to succeed in raising an interest on this very interesting topic among our readers, who may not yet have heard of such a process, sure I am that I shall be adding another strong link to that golden chain which already encircles their gardening resolves.
Now, whether we look on Cain and Abel as two varieties from two distinct species of the genus mankind, or as two legitimate species, it makes not the slightest difference. The world was peopled from this stock; and, of all the analogies that have been found to exist between plants and animals, none are more clear than this, namely, that whether we look on plants of one family as distinct species, like Adam and Eve, or as varieties, as we may call Cain and Abel, for argument sake, makes no difference in the process of crossbreeding; for, if they will cross at all, it will only he among themselves, for there is no obvious limit between a species and a variety in as far as cross-breeding is concerned. Here the grand analogy between plants and animals ceases. The family mankind has, in the lapse of ages, branched out into distinct sections, and every section into subordinate forms; so much so, that infidels have made a strong handle of this to cast discredit on the revealed word of God, who, for wise purposes, has so constituted this family that the most dissimilar members of the best marked sections of it will "increase and multiply" in obedience to His will. Not so plants, however: they, too, or, at least, many of them, have branched out into well-marked sections from original types, like the human race; but, in the majority of instances, plants thus far removed will not interbreed with each other, but only within their respective sections.
The offspring of a cross union among plants may be fertile, half fertile, or altogether quite sterile or barren; and, as far as we yet know, either of these conditions are not induced by the near or distant relationship in the parents; for every degree of relationship in the parents has been found to produce these effects in their offspring; so that any two kinds of plants may look as like each other as is possible without being absolutely the same plant, and an offspring from their union will as likely be barren as one produced from two plants which one could hardly think belonged to one family; so that we have no criterion in the outward aspect of plants by which we can pronounce beforehand whether they will cross with each other or not; or, if they do, what degree of fertility may be expected from their offspring.
Zoologists, starting from the well-known point of the cross between the horse and the ass, and at first believing the two parents to belong to different families, have admitted the possibility of union between the members two different families, and that the offspring from such union would, in all cases, turn out to be sterile, as in the case of the Spanish mule; and, not only that, but even went so far as to call such offspring mules. Botanists, reasoning from analogy, unfortunately admitted the same views in the vegetable kingdom, and brought a world of confusion and uncertainty on themselves and their followers in consequence. We are now only groping our way out of this darkness and confusion, but every season, and almost every experiment carried out according to natural laws, shews clearly that those views of naturalists are either untenable, um, at all events, require reconsideration. Therefore, knowing that plants the nearest in affinity many produce a barren or sterile offspring, as well as those the most distant, I shall give up the word mule altogether, as conveying no sensible meaning, or a falsehood. Hybrid and cross-breed I shall use as synonymous, although the two words have been used for two different degrees of crossing by the first authority. I shall so use them as meaning the same thing, because, after all, the difference is only in the words, not in what they represent. The simple act of crossing two plants together, any one, even a child, can learn in two minutes; and next week I shall begin with that process. D. BEATON.
May 1849 pp. 100-101
HYBRIDIZING.—In the introductory remarks on this subject at page 90, we have seen that one family of mammals, (as naturalists term all annuals that suckle their young,) have sprung from two individuals; and that during successive generations the present characters, constitutions, and habits of the different races of the human family were stamped on them by local circumstances and other causes. Some of the most eminent naturalists believe that all the other animals have, in like manner, branched out from a few original types; and, like man himself, owe their present conditions to the influence of climates and various causes. And it is as firmly believed by others that the different races, or families, of plants have had a similar origin, that is to say, have passed into those endless variations, for which they are now so conspicuous, from a few original types. When we see that we ourselves are permitted to add new forms to those already in existence, by the means pointed out to us by the light of science, or rather by the Hand that made them, we may well pause before we can gainsay or dissent from these views, But whether these ideas be right or otherwise, they will not much affect the views of crossbreeding, which I wish to explain to the uninitiated by referring to them. All that I want to explain is, that plants are divided by nature into families, many of which, like the human family, have assumed different aspects in different countries and localities front their progenitors; but that no outward appearance will warrant us beforehand to say whether or not the different members of any one family will interbreed with each other. All that we are certain of is-and that is not yet fully admitted by some that no plant, and probably no animal, is allowed to cross with another plant or animal not originally of the same stock or type; and that all the cases that have been advanced to the contrary by different naturalists are only so many verdicts against their own classifications. It is true that many analogies can be traced between the animal and vegetable kingdoms; and I am persuaded, from what little acquaintance I have with the subject, that all the confusion which now exists, as to the powers and effects of cross-breeding, both in the animal and vegetable kingdoms, have arisen, and are perpetuated, from the fact that naturalists have drawn their conclusions on these matters more from these analogies than from actual facts. I am, also, equally satisfied that, among plants at least, all the facts that we have yet ascertained respecting the power of cross-breeding in any family are little better than blind guides in assisting us to experiment on the members of a different family; and, therefore. that every step in the progress of cross-breeding must be arrived at by actual experiments rather than by the closest analogies; and that any reader of THE COTTAGE GARDENER is as likely to arrive at a just conclusion, step by step, in any family of plants, as the most consummate philosopher. Let us, therefore, take up the subject with the two-fold view of increasing the gaiety of our window favourites, and of recording facts from which, at some future period, a correct theory of cross-breeding may be constructed.
To understand the simple process of fertilising, or, as we may call it, crossing one flower with the dust of another, it is necessary to understand the different parts of a flower. If we look at a geranium flower. for instance, we see some flowers open and some in bud; those in bud are enclosed in a green covering, and only the tips of the flower leaves peeping out at the point: that covering is the first part of a flower, and is called the calyx, a word of Greek origin, signifying a cover, so it is very easy to remember. Some people call this the flower-cup," but it is more of a saucer than a cup, and we of THE COTTAGE GARDENER will take things in their right meaning, and call the calyx a saucer, and the flower a cup, because the flower when wide open sits in the calyx like a tea-cup in its saucer. Now, take one of these wide open flowers of that same geranium, and inside, in the middle of it, you will see a lot of reddish oblong bodies, called anthers, all held up at different lengths on the top of whitish threads, called filaments, from filam, the Latin for a thread. These anthers open with two slits on one side when they are quite ripe, and a yellow dust is seen inside these openings; this dust is called pollen, and is the most wonderful thing in the economy of the vegetable kingdom. The dust, or pollen, is finer than the finest flour, and yet a good magnifying glass will shew that it consists of many small particles of different forms, but always of the same form in the same plant. You would probably think I was drawing on the imagination if I were to say that one of these anthers contained more than a thousand grains of pollen;—what shall we say, then, when it is clearly made out that a thousand multiplied by ten thousand, and that ten times over, would come nearer the truth? Each individual grain out of these numberless thousands is endowed with a power that can produce the largest oak tree in England. The lice gathers this pollen from the flowers, and is the yellow balls you see them carrying into the hive on their hind legs; and if we could make a calculation of the number of pollen grains a single bee could gather in one day, I should not be surprised if it should turn out that the whole would exceed that which could originate a forest larger than any we have in this country. The pollen, therefore, is the father of all plants and trees. Each pollen grain contains matter smaller than pollen, and is the substance which is the fecundating principle in the vegetable kingdom. In the very centre of the same geranium flower we have been looking at, you will see one little thread called a style, coming up by itself, and when it is ripe it divides at the top into five little horns. These little horns are the stigma, and this stigma in each flower is the mother of all seeds it produces. It is of different forms in different plants, but by its style it is in all cases found to be attached to the little nursery where the seeds come to maturity, or, in other words, to the seed vessel. Thousands of conjectures are afloat as to how the pollen fertilizes the seeds; but philosophers are loath to admit anything they cannot well explain, and they have been puzzling their heads for an age to account for this simple process; so simple, indeed, that a child can understand it, if he is first told that a circulation of the juices of all plants, and in all parts of a plant, is constantly going on, and more so when they are in a growing state; part of this circulation goes on between the embryo seeds in the seed-vessel, and the stigma through the style, and when the pollen grains burst by the swelling caused by being moistened with the viscid matter on the stigma, the fecundating principle is carried up or down, according to the position of the style to the seeds, and thus fertilization takes place. Therefore, all that we have to do is to dust the stigma with the pollen when both are ripe for the operation, and seeds of the same kind will follow in due time; but when we wish to have a cross-bred plant from the union of two distinct parents, the pollen bags or authors must be cut out from the one that is to bear the seed, and the stranger pollen used in its stead. D. BEATON.
June 1849 pp. 155-157
|*At first sight this may appear to be opposed to the opinions expressed at p. 125, but it is not so, for the writer of the "Phenomena of the Season" quite agrees with Mr. Beaton, that the petals may be removed without injury to fertility after they have expanded, or "after the stamens, &c., are fully grown." In the Gum cistus they do so naturally.—ED. C. G.|
HYBRIDIZING.—I have said that the stamens, or male organs, in a flower, are analagous to the floral leaves or petals, double flowers being occasioned by the conversion of the stamens into petals; and hence I have inferred that the petals are perfectly useless, either as far as the impregnation of the ovule or the future development of the seed is concerned. I also said that the petals might be cut off whenever they interfered with the operation of dusting the pollen, as they often do in tube-shaped flowers, when the pistils are hid from view, such as the verbena, the florist's polyanthus, and in many other flowers of various forms.* But I will explain this more in detail, as some expert hybridizers, whom I could name, seem not to be aware of this fact. We have the evidence of our senses that stamens are converted into petals-no one doubts that, who has the least knowledge on the subject; the petals must, consequently, partake more or less of the nature of stamens, for the change has not altered their nature, only their outward form; and we all know, by this time, that the office of the stamens is simply to uphold the anthers or pollen bags on their summits, and when the pollen is ripe and dispersed the office of the stamens is at an end. We also know that flowers selected for crossing must be deprived of their stamens, to get rid of the pollen, before either it or the stigma is ripe. Therefore, seeing that this does not affect the operation of the pistils when touched by pollen from another flower, why not get rid of the petals as well as the stamens, if they are in your way when you are crossing the flower, seeing they are exactly of the same nature? If you hold still to the belief that the petals are endowed with the property of supplying nutrition, or are in any other way essential to give power or effect either to the pollen or young seeds, I must refer you to the great Decandolle, who is the first authority in botany and vegetable physiology, and who has clearly explained all this in his "Vegetable Organography," translated into English, a few years since, by Boughton Kingdon, Esq., who was so kind as to present me with the work, although we are perfect strangers, and who, if his eye should ever glance over this page, will be glad to learn that his labours have been of great use to me. Between 1829 and 1836 I obtained perfect seeds from between 90 and 100 kinds of plants, after first depriving them of their petals for the purpose of experiment; and, in 1837, I said in the Gardener's Magazine, that the presence of the petals is not necessary for the purposes of cross-breeding; and, after all this, the future historian of our gardening, in the middle of the nineteenth century, will have occasion to place these three significant marks !!! after telling his readers that, in a standard work on flowers, published in London in 1848, very minute rules are laid down to avoid damaging the petals of a flower in the act of hybridizing it, as if that could make any difference to the issue of the experiment. I shall not mention either the book or the writer farther than to say that both are of the first respectability, and the latter deservedly accounted the most successful of our hybridizers. But we are all of us in our infancy in this department, for it is only about 70 years since the first experiments, to ascertain the possibility of obtaining crosses in the vegetable kingdom, were instituted in Germany by Kolreuter, who, therefore, is the father of this branch of our craft. In England, these experiments were followed out, at a much later date, by the late Mr. Knight, of Downton Castle, then President of the London Horticultural Society, and chiefly with the view of improving our fruits and vegetables; and, about the same time, by the Hon. and Rev. Dr. Herbert, late Dean of Manchester, who took a wider range, and experimented on many of our popular flowers, and more particularly on bulbs, with which lie was more conversant than any other botanist. The late Mr. Sweet, a clever practical botanist and cultivator, much about the same period, was engaged in similar experiments, detached notices of which appeared in several works on which he was engaged. In one of these works, on the Geranium, he gives some very interesting details of how our window geraniums began first to be obtained, by crossing some of the wild species from the Cape. I spent a whole day, last summer, looking through this work in the library of the Horticultural Society; and to compare, in one's mind, the noble specimens of geraniums that were exhibited that week with time little weeds from which they originated, was, indeed, a most singular contrast.
Thirty years of patient industry were expended before a geranium was obtained that would be now thought good enough to plant out in a common shrubbery. Many now regret that the breed or present race of geraniums is not more varied into sections, as they might have been, had the best colours of the original parents been followed out, each in its own strain, instead of pushing on with only a few which yielded more readily to the impatient hybridizer, as has been done, more recently, in the case of the calceolarias. The older florists, however, had more reason to be content with what they could get, as few families that have been experimented on in this way are so obstinate as the geraniums to part with their wild characters. I know of only one other instance, the Lobelia, where the offspring of species almost identical in character and aspect becomes absolutely sterile at the first or second generation, like some of those of the wild geraniums.
In 1837, Dr. Herbert published a large work, with coloured plates, on an extensive division of bulbs allied to the Amaryllis, to which he appended a full description of his own experiments in hybridizing for 30 years, as well as a history of what others had effected in the same field, both here and on the continent. This may be said to be the first popular account of cross-breeding, in the vegetable world, which appeared in any language, and it gave a powerful impetus to the art in both hemispheres. Before the appearance of this work, the crudest absurdities were in circulation about cross-breeding. We have all of us since mended our ways, but many weeds spring up yet here and there. In 1847, Dr. Herbert wrote two long papers on the same subject, in the Journal of the Horticultural Society, full of the philosophy of hybridizing, and containing many startling facts; in short, alter the investigations of 40 years, he has here summed up the result of his own views on the subject, founded on the facts he and others had brought to light by cross-breeding. He finally arrives at this conclusion, "Can we, in the face of these phenomena, assert that no vegetable since the period before the sun and moon gave it light, no bird or fish since the Almighty called them forth from the salt mud, no creature of the earth since it was evoked from the dust, can have departed from its precise original structure and appearance? Let us be more humble in our assumptions of scientific knowledge, less bigoted and self sufficient in our examination of revealed truth, and let its give glory to the infinite and unfathomable power and wisdom of God. I call it self-sufficient to hold that ancient and obscure words can have no possible meaning but that which we have been in the habit of attributing to them inconsiderately. It may be unacceptable to the botanist, who has been accustomed to labour in his closet over dry specimens, and think he can lay down precise rules for the separation of genera, and look with complacency upon the scheme he has worked out, to find that the humblest gardener maybe able to refute him, and force him to reconsider the arrangement he has made; but the fact is so. The cultivator has the test of truth within his scope: and, far from being an evil, I look upon it as a great advantage, because it will lead the industrious and intelligent gardener to take a higher view of the objects under his care, and to feel his own connexion with science; and it will force the scientific to rely less on their own dictation, and to feel that they must be governed by natural facts, and not by their own preference."
|* Magazine of Natural History, vol. i., page 1.|
Without "facts," we may pursue and detail our investigations of the mystery of cross-breeding to little purpose; there is no safety without actual facts, for there is no room yet for much useful theorising. To facts, therefore, let us return, and see how the Gladioli are best crossed. They are, of all plants. the easiest to cross, and the result of the operation is soon known. It is now just 42 years, this summer, since the first gladiolus was crossed in England; and if it was crossed elsewhere before that time, we have no record of it. Therefore, all that is now known respecting the breeding qualities of this family was ascertained by a few individuals as far back as 20 or 30 years since. There is one point, however, which seems to be of much importance, that has lately been mooted in private circles respecting this family, viz., that the higher it is cultivated the more certain it is to produce extra fine hybrids. Although I am quite at home with this family, I cannot say if this is a real fact or not, but I believe in it. Like all other plants that are to be crossed, the gladiolus must have the anthers cut before they open to relieve the pollen. Suppose we have only two sorts, however, and that we wish to obtain seeds from both, each by the pollen of the other. Now, this was a puzzle in my early crossing days, but it is plain enough now. It has been ascertained that pollen which was dried with a flower on a specimen, and kept in a book or herbarium for a number of years, was capable of undergoing a similar process to that of fertilizing a stigma, when placed in water or otherwise damped: but it was not ascertained if such pollen could fertilize seed or not. This account was published in 1829,* and, from that day to this, I have every season reserved unripe pollen for days, weeks, and even months; and I have some by me now six years old. I have found that pollen will ripen though taken from a flower at an early age, say some days before the anthers would open naturally; and all that is necessary for its preservation is an absolute exemption from damp, and not to be dried quickly if extracted before it is ripe. I believe there is no pollen but will keep a month or two, and that is quite enough for ordinary crossing. The best way to keep it is to fold it in silver paper, and to enclose this in coarse brown paper, the packets to be kept in a drawer in a dry room.
Well, then, you see that with only two gladioli you may easily get a cross from each, unless you are extravagant enough to throw away the pollen; however, as the flowers of a gladiolus do not open all at once, there is no need of preserving the pollen at all; but I am anxious not to leave a stone unturned that would throw any light on the subject in hand. There is only one style in the centre of a gladiolus, and that divides into three parts, or stigmas, at the top, and is the part to dust the pollen on. When the parts are ready for the pollen, these stigmas open into two halves, or are dilated, as botanists say, and the edges of these little openings are the real stigmas. The anthers which bear the pollen are always in threes in this flower; each flower invariably having only three stamens, which hold up the anthers. When the pollen is ripe, the anthers burst from top to bottom, and there is a furrow down the centre of each opening, so that the anthers are each in two parts. The easiest way of applying this pollen to the stigma is to cut off the flower whose pollen you are to use, then with a penknife cut off first the petals down as far as they are split, then you will only have the tube of the flower to which the bottom of the stamens are attached; then, with the point of the knife, single out one of the stamens with a ripe anther, keeping hold of it between the knife and your thumb, and in that position apply the anther backwards and forwards on the stigma, when you will see the dusty pollen adhering each time to the stigmas, and then the work is done. It is always a good plan, however, to apply the pollen twice, say in the morning and afternoon; or, after the interval of a clay or two, with some flowers whose stigmas remain fresh for several days. Where a cross is difficult to be obtained, it is a good plan to use pollen from two or three flowers, and from as many plants, if they are at hand; but the pollen plants must always he of the same kind, as no flower will yield to the influence of two kinds of pollen at the same time. If it did so breed from two kinds, the process would be called superfoetation, a monstrous doctrine, so repugnant to nature that few of the more learned physiologists countenance it now, though some of them leaned that way till the labours of the cross-breeders proved how untenable it was; of course, different kinds of pollen may be used for the different flowers on a given plant, and the same kind of pollen may be used with advantage from two or three flowers of the same kind, but from different plants; thus giving two or more chances against failure, as the pollen may be deficient in one plant from various causes: it may be too ripe, or not ripe enough, and wet or too much dampness may have access to it, which would cause the pollen grains to burst and so prevent its full action. We may exemplify in the gladiolus a very mysterious point, which was but very recently cleared up, and that by the late Dr. Herbert. I have already said that the one style of the gladiolus is divided on the top into three stigmas; the seed vessel is also divided into three divisions, each of them holding several winged seeds. Now, for a long time, it was believed that each division of the stigma impregnated only the seeds in the corresponding division of the seed vessel, and that if the other two divisions of the stigma were cut out or left without pollen, their share of the seeds could not be fertilized. But it is not so; one of the three divisions is equal to the task of conveying the pollen to all parts of the seed vessel, which is fatal to the theory of the pollen being conveyed in long tubes spun out of its own substance. It occurred to me, some years since, that if three kinds of pollen were applied to the three divisions of the stigma—seeing that each of them were capable of fertilizing all the seeds—that if there was any truth in the theory of superfoetation, this would he the most likely way of proving it, and I suggested the experiment in 1837. After a great number of experiments, Dr. Herbert was enabled to answer the question in the negative ten years subsequently. Another feature will meet the young beginner in the gladiolus, perhaps, for the first time. There is no trace of a calyx or outer covering in any of them, nor, indeed, in any of the lily-like flowers. Their corolla is mostly divided into six parts, and three of these are the true petals; the other three representing the calyx in a petal-like form. But the most curious of all is the fact disclosed in the stamens of the gladiolus and of all the iris tribe, of which this forms a part. You are aware this name gladiolus is taken from gladius, a sword, on account of their leaves being shaped like a two-edged sword. They are, therefore, gladiators or swordsmen, if there is anything "in a name." The stamens, being the male organs. are the knights of the order, and military knights are proverbial for gallantry; but there is no rule without an exception, and here is a marked exception, both in a military and botanical point of view: for in the whole order of irid, gay and beautiful as they are, the knights invariably turn their backs on the ladies. So if ever you meet with a lily-like flower, with three stamens only, and the anthers holding the opening for the pollen opposite to the style and stigma, you may depend on it the stranger belongs to the iris tribe, of which our gladiolus is one family. D. BEATON.