HYBRIDIZING. Hybridization has, of late years, come to be a distinct branch of agricultural axt, in the production of grains, plants, fruits and flowers. In animals, it has been practiced, in the production of mules, between the ass and mare, the buffalo and cow, Brahmin bulls with Short-horns, Alpacas with the Llama, the dromedary and camel, the common goat with the cashmere. So far, however, tbe results have not been valuable, if we except the mule proper, and the progeny between the male cashmere and the common goat of the country. The plan of proceeding is too simple to need explanation, except that the male animal should be used, to which the progeny is desired to most resemble. The progeny between the ass and mare gives a val uable mule ; that between the horse and hinny, does not. Hybrids are not fertile as to the progeny. Hence, in the hybridization of plants, the progeny must always be propagated by layers or cuttings. The same is true to a great extent in the cross breeding of plants, the seed can not be depended upon to come true. Indeed in hybridization there is always degeneration to a certain extent, so that in the majority of cases greater care is necessary with the hyhrids than with the original parents. In vegetation, in the United States, hybridiza tion and cross-fertilization has hitherto been chiefly confined to the grape, strawberry, and to flowers. Of late years, it has extended in other directions. As showing the difficulty in obtain ing hybrids, from plants of different species, and the impossibility of obtaining species that shall continue fertile each with the other, Dr. Hooker, in discussing the relations aud distribution of species of plants, lays down the following pro positions as axioms: 1. That all the individuals of a species have proceeded from one parent (or pair) and that they retain their distinctive (specific) characters. 2. That species vary more than is generally admitted to he the case 3. That they are also much more widely distributed than is usually supposed. 4. That their distribution has been effected by natural causes ; but that these are not necessarily the same as those to which they are now exposed. Hybridization has been supposed by many to be an important element in confusing and making species. Nature, how ever, seems effectually to have guarded against its extensive operation and its effects in a natural state, and, as a general rule, the genera most easily hybridized in gardens are not those in which the species present the greatest difficulties. With regard to the facility with which hybrids are produced, the prevalent ideas on the subject are extremely erroneous. Gitrtner, the most recent and careful experimenter, who appears to have pursued his inquiries in a truly philosophi cal spirit, says that 10,000 experiments upon 700 species produced only 250 true hybrids. It would have been most interesting had he added how many of these produced seed, and how many of the latter were fertile, and for how many genera tions they were propagated. The most satisfac tory proof we can adduce of hybridization being powerless as an agent in producing species, (how ever much it may combine them,) are the facts that no hybrid has ever afforded a character for eign to that of its parents, and that hybrids are _generally constitutionally weak and almost invar iably barren. Unisexual trees must offer many facilities for tbe natural production of hybrids, which, nevertheless, have never been proved to occur, nor are such trees more variable than her maphrodite ones. The following will show some of the principal facts connected with hybrid izing plants, taken from the work of George William Johnson, of England, on Gardening. The seed vessel is not altered in appearance by impregnation from another plant; therefore, no hasty conclusion of failure is justified hy that want of change. The color of the future seed, not of that first hybridized, seems to be most intluenced by the male plant, if its seeds and flowers are darker than those of the female. Mr. Knight found, that when the pollen of a colored-blossomed pea was introduced into a white one, the whole of the future seeds were colored. But when the pollen .of a white blossom was introduced to the stigma of a colored blossom, the whole of the future seeds were not white. Capt. Thurtell, from his experiments on the pelargonium, also informs me, that he has always found the color and spot of the petals to be more influenced by the male than hy the female parent. Indeed, all experience proves that the progeny usually, though not invariably, most resembles, in color, the male parent. Large stature and robustness are transmitted to the offspring by either parent. It does not absolutely matter for obtaining this characteristic, whether it be the male or female which is large; but Mr. Knight generally found the most robust female parent produced the finest offspring. Capt. Thurtell, from lengthened observation and experiment, has ascertained that the form of the petals follows_most closely that of the female parent. Mr. Knight says that the largest seed from the finest fruit that has ripened earliest and most perfectly, should always be selected. In stone-fruit if two kernels are in one stone, these give birth to inferior plants. The most successful mode of obtaining good and very distinct varieties, is to employ the pollen from a male in a flower grown on another plant than that bearing the female parent. To avoid pre vious and undesired impregnation, the anthers in the female parent, if they are produced in the same flower with the pistils, must be removed by a sharp-pointed pair of scissors; and the flower inclosed in a gauzf bag, to exclude insects, until the desired pollen is ripe. Another effectual mode of avoiding undesired impregnation, is bringing the female parent into flower a little earlier than its congeners, and removing the anthers as above described; the stigma will remain a long time vigorous if unirnpregnated. Although the fertility of all the seed in one seed vessel may be secured by applying pollen only to one style, even where there are several, yet the quantity of pollen is by no means a matter of indifference. Koelreuter found, that from fifty to sixty globules of pollen were required to com plete the impregnation of one flower of Hybiseus Syriacus but in Mirabilis jalapa , and M. longi flora, two or three globules were enough ; and in the case of pelargoniums, Capt. Thurtell
says two or three globules are certainly suffi cient. M. Haquin, a distinguished horticulturist at Liege, has impregnated flowers of the aZalea with pollen kept six weeks; and camellias with pollen kept sixty-five days. He gathers the stamens just previously to the anthers opening, wraps them in writing-paper, places them in a warm room for a day, collects the pollen they emit; and preserves it in sheet lead in a cool, dry place. M. Godefroy suggests, that two conefive glasses, like those employed for vaccine virus, would be better. The globules of the pollen must not be cruslaed. M. Haquin thinks the pollen of one year will be effective, if preserved until the year following. Mr. Jackson, of Cross Lanes Nursery, near Bedale, says, he has found the pollen of the Rhododendron 8mithii tiyrinum retain its fertilizing power even for twelve months. It is easy to discern whether impreg nation has been effected, as in such case the stigmas soon wither. The stigmas which have not received the pollen remain for a long time green and vigorous. Whenever double flowers may be desired, if a double flower should claauce to have a fertile anther Or two, these should be employed for fertilization, as their offspring are almost sure to be very double. Superfcetation has been doubted; but as it occurs in the dog, we see no reason for disbelieving its possibility in plants. Capt. Thurtell thinks it may be done by the bee introducing mingled pollens at the same instant. Then why not if a similar mixture is inserted by the camel's-hair pencil of the cultivator? Plants nearly related, that is, closely similar in the structure of their various parts, are those only which will immedi ately impregnate each other; but it is impossible, at present, to say what families of plants may or may not be brought into fertile union through intermediate crosses. A very short time ago, the azalea and rhododendron were thought incapable of such union, but this opinion is now exploded, for rhododendron pontieum has been fertilized with the pollen of azalea 8i72enSi8 and the progeny between the first, an evergreen, and the latter, a deciduous shrub, is the pre viously unknown phenomenon, a yellow rhodo dendron. In cross-fertilization and hybridizing, suitable male and female plants are to be selected, and which blossom at the same time. The plant to be impregnated is to be carefully divested of its stamens, if it have any, and the pollen from the male plant dusted upon the female organ. The flower is then to be isolated from any possible contact with the polleu of other plants, and the seed taken, when ripe, care fully labeled, saved, and at the proper time sown. To return to animals. Wilson observes that every mule is a compound of two species, aud seems to be, to a certain extent, a malformation of each, and a type of neither ; and while unable to reproduce the specific form of his darn, or of his sire, he is wanting in a sufficient specific character of his owu to be the proper subject of reproduction. Nor do mules exhibit a true blending of the specific properties of their parents; but as regavls the most important prop erties, such as size, form, constitution, temper, and habits, they generally possess a closer resem blance to their dam than to their sire. Buffon says, in the case both of mules and hinnies, that they retain more of the dam than of the sire, not only in magnitude, but in the figure of the body ; whereas in the form of the head, limbs, and tail they bear a greater resemblance to the sire. The same naturalist infers, from various experiments respecting cross-breeds between the he goat and ewe, the dog and the wolf, the canary bird and the goldfinch, that the male transmits his sex to the greatest number, and that the preponder ance of males over females exceeds that which prevails where the parents are of the same spe cies. Any two species of the equine genus will hybridize with each other, but some do so with facility and willingness, and others with diffi culty and repugnance. Mules have been gene rated between the horse and the quagga. They are readily produced between the horse and the ass, as is well known; but they are very reluc tantly and sparingly produced between the ass and the quagga. In an experiment related by Pennant, a he ass and a she zebra were for some time unsuccessfully kept together with a view of their hybridizing; but after the ass was taken aside and painted in such a manner as to resem ble a zebra, and conducted back to his compan ion, they united aud produced a mule; another ass and zebra mule was produced at Turin, but it died as soon as it was born; and another, a well-formed female mule, was produced in a menagerie at Paris, from a Spanish ass of the largest size, and a female zebra, and became larger than its dam, acquiring a form somewhat similar to that of its sire, aud was remarkable for docility% In anothez experiment female zebra was covered by a stallion and became preg nant, but died in the eighth month of her gesta tion, and when her body was opened the fcetus was found to be a male without hair, and marked on the head with black and white stripes. The same authority, after referring to the similarity of the name in different languages of the true mule, produced by the jack crossed upon the mare, tells us that the mule has con siderably more resemblance to the horse than to the ass, and often, in the south of Europe, is a very fine animal of from fifteen to seventeen hands high. Its head has generally a clumsy form and a heavy appearance, and is the most exceptional part of the whole system. These animaLs are considered by naturalists to be dis tinct, but nearly allied, species. According to the latest authorities they are members of two genera, though formerly the horse and the ass were both included under one. The scientific name of the horse is Eguus eaballus; of the don key, Asinus vulgarly and the zebra, or quagga, is called A8i72118 zebra by Baird. In every coun try the mule is sure-footed and hardy. In Spain it has the finest form and appearance; in Savoy it has a remarkably large size; in Egypt it is about equal in value to a medium horse; and in the mountain regions of large portions of both Europe and South America it is far more ser viceable than the horse could be, and com pletely supersedes the horse for packing, and often even for the saddle.