426 H Y D H Y D Graft- Hybridism. The only other subject of importance that falls under the present heading, is that which has been appropriately called "graft-hybridism." It is well known that, when two varieties or allied species are grafted together, each retains its dis tinctive characters. But to this general, if not universal, rule there are on record several alleged exceptions, in which either the seion is said to have partaken of the qualities of the stock, the stock of the scion, or each to have affected the other. Supposing any of these influences to have been exerted, the resulting product would deserve to be called a graft-hybrid. It is clearly a matter of great interest to ascertain whether such formation of hybrids by grafting is really possible ; for, if even one instance of such formation could be unequivocally proved, it would show that sexual and asexual reproduction are essentially identical. The cases of alleged graft-hybridism are exceedingly few, con sidering the enormous number of grafts that are made every year by horticulturists, and have been so made for centuries. Of these cases the most celebrated are those of Adam s laburnum (Cytisus Ada-mi) and the bizzarria orange. Adam s laburnum is now flour ishing in numerous places throughout Europe, all the trees having been raised as cuttings from the original graft, which was made by inserting a bud of the purple laburnum into a stock of the yellow. M. Adam, who made the graft, has left on record that from it there sprang the existing hybrid. There can be no question as to the truly hybrid character of the latter all the peculiarities of both parent species being often blended in the same raceme, flower, or even petal ; but until the experiment shall have been successfully repeated, there must always remain a strong suspicion that, not withstanding the assertion and doubtless the belief of M. Adam, the hybrid arose as a cross in the ordinary way of seminal repro duction. Similarly, the bizzarria orange, which is unquestionably a hybrid between the bitter orange and the citron, -since it presents the remarkable spectacle of these two different fruits blended into one, is stated by the gardener who first succeeded in producing it to have arisen as a graft-hybrid ; but here again a similar doubt, similarly due to the need of corroboration, attaches to the statement. And the same remark applies to the still more wonderful case of the so-called trifacial orange, which blends three distinct kinds of fruit in one, and which is said to have been produced by artifi cially splitting and uniting the seeds taken from the three distinct species, the fruits of which now occur blended in the triple hybrid. The other instances of alleged graft-hybridism nre too numerous to be here noticed in detail ; they refer to jessamine, ash, hazel, vine, hyacinth, potato, beet, and rose. Of these the cases of the vine, beet, and rose are the strongest as evidence of graft-hybrid ization, from the fact that some of them were produced as the result of careful experiments made by very competent experimentalists. On the whole, the results of some of these experiments, although so few in number, must be regarded as making out a strong case in favour of the possibility of graft-hybridism. For it must always be remembered that in experiments of this kind, negative evidence, however great in amount, may be logically dissipated by a single positive result. History and Literature. From time immemorial the leading facts of hybridism have been known in the case of the horse and the ass. The knowledge of corresponding facts as occurring in the vegetable kingdom necessarily dates from a time subsequent to that at which the sexual functions of plants became known, i.e., towards the end of the 17th century. The earliest recorded obser vation of a hybrid plant is one by Gmelin ; the next is that of Thomas Fairchild, who in the second decade of the 18th century produced the cross which is still grown in gardens under the name of " Fairchild s Sweet William." Later on in that century Linnaeus made a number of experiments on the cross fertilization of plants, and produced various hybrids ; but it was ^reserved for the labori ous investigations of Kblreuter, towards the end of that century (1751-1799), to found and largely to build the existing structure of our scientific knowledge upon this subject. To him also belongs the credit of first discovering the part played by insects in the fer tilization of tlowers. He published most of his results at the St Petersburg Academy of Sciences. Next in order of time deserve mention the works of Graf Lavola (Discorso ddla Irri abilita d al- cuni Fiori nuovamente scoprrtn, 1764), and of Conrad Sprengel (Dns entde-jkt,e Gfeheimniss der Natur im Bau und in der Befruchtung der Bht,mcn, 1793). The latter work is full of interesting observations on the connexion between the structure of flowers and the visita tion of insects. Next we come to the celebrated horticulturist, Thomas Andrew Knight, who from 1787 for a number of years de voted an immense amount of labour, with a large measure of results, to the improvement of fruit trees and vegetables by crossing. He published in the Philosophical Transactions and in the Trans. Hort. Sac. During the first quarter of the present century the only names that in the present connexion call for mention are those of J. E. Smith (Flora Britannica, 1800), Villars (Rp. Coll. Bot., 1809), Hoppe (News Bot. Taschenb., 1810), Guillemin and Dumas ("Obs. sur 1 Hybridite d. riant.," in Mem. Paris Soc. Hist. Nat., 1833), Henschcl, and Godron. During this period, besides Knight, already mentioned, there were two other English experimentalists at work, whose names deserve to be placed in the first rank among those which are associated with this subject. These are Sweet, who published an important work on Geraniactce, and Herbert, whose work on Amaryllidece, together with sundry publications in the Journal of the Horticul ural Society, very materially advanced both the facts and the theory of hybridism. We say " theory," because it was in these publications that Herbert carried on his celebrated controversy with Knight regarding the alleged sterility of hybrids. In 1828 there was published a prize essay by Wiegmanu on a thesis which was set several years before by the Berlin Academy of Sciences, and which embodied the question whether hybrid plants are necessarily sterile. We next come, in the second quarter of the present century, to the laborious researches of Gartner, the number of whose experiments in hybridizing has certainly not been surpassed, and probably has not been equalled, by that of any other experimentalist. His principal work is Vcrsuche und JBeobachtungen iibcr die Bastarderzeiujung im Pflanzenreiche. In connexion with this period we may also mention the names of Braun, Wallroth, Zuccarini, Meyer, Ziz, Koch, Schiede, Lasch, Reichenbach, A. P. de Candolle, Whinner, Horuschuh, and Nagcli. In 1854 a research of value was published }>y Klotzsch (l r erhandl. Kgl. Prcuss. Akad. Berlin], and others later by Hegel, Godron, and Jordon. In 1860 a prize was offered by the French Academy of Sciences for the best essay on hybridism, with special reference to three points, the fertility or sterility of hybrids, the cause of their sterility, and the constancy of type manifested by fertile hybrids. In 1865 this prize was awarded jointly to Naudin and Godron, the latter name being identified with researches upon the character of hybrids which deserve to be considered among the most im portant of the present century. The next work of note appeared in 1865, by Max Wichura, on Die Bastardbefruchtnng in Pflan- zcnreich, & e. He combined, in one complex hybrid, six different species of Salix ; confirmed, in opposition to Godron, the doctrine of Kblreuter, Herbert, Gartner, and Naudin, that a hybrid is best fertilized by its own pollen ; and found, in opposition to Naudin, that the progeny of hybrid willows retains its hybrid character. In 1865-6 Nageli published his important observations on naturally produced hybrids (Sitzungsbcr. Akad. Jfiinchen, Math. Phys.}. The highly important experiments of Darwin on dimorphic ami trimor- phic plants have been already alluded to. Those who within still more recent years have contributed to the literature of hybridism are Caspary, Mendel, Seden, Dominy, Kellermann, Fr. Schultz, Timbal-Lagrave, Grenier, A. Kerner, Wirtgen, Michalet, Ritschl, Beckhaus, P. Ascherson, R. von Uechtritz, J. Schmalhausen, 0. Haussknecht, V. von Borbas, Kuntze, Hcnniger, and W. 0. Focke. The last-named author lias just published an elaborate and valuable work on hybridism in plants (Die Pflanzcn-Mischlinge, Berlin, 1881), giving a tabular series of all the known vegetable hybrids, and treating the entire subject in a very comprehensive manner. On the subject of animal hybrids there is virtually no literature, save scattered records of fertile crosses among sundry species con fined in various menageries ; and these are without interest as bearing on any of the principles of hybridism. (G. J. R.) HYDE, a township of England in the parish of Stock- port, Cheshire, is situated near the river Tame and the Peak Forest canal, and on the Midland, and the Manchester, Sheffield, and Lincolnshire Railways, 1 miles east from Manchester and 6 north-east from Stotckport. It is under the government of a local board, and a county court is held there every Wednesday. St George s church, in the Perpen dicular style, was erected in 1832, and St Thomas, in the Early English, was erected in 1868. The principal other public buildings are the mechanics institute, the temperance hall, and the court-house. The town owes its importance to the cotton manufacture, and possesses weaving factories, spinning-mills, print-works, iron-foundries, and machine- works. There are extensive coal-mines in the vicinity. The old family of Hyde, to which the line of earls of Clarendon belonged, held possession of the township as early as the reign of John, but it was a mere village until the establishment of the cotton manufacture at the begin ning of the present century. The population of the town ship in 1861 was 13,722, and in ^71 it was 14,223. HYDE, EDWARD, Earl of Clarendon. See CLARENDON. HYDE, THOMAS (1636-1 703), a distinguished Orientalist, was born at Billingsley, near Bridgnorth, in Shropshire, June 29, 1636. He inherited his taste for linguistic studies, and received his first lessons in some of the Eastern
tongues, from his father, who was rector of the parish. Tn
